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WINTON
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ENGINEERING
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ARTES
LIBRARY
1837
SCIENTIA
VERITAS
OF THE
UNIVERSITY OF MICHIGAN {
PLURIBUS UNUM
TULBUR
SI-QUAERIS PENINSULAM AMOENAMI
CIRCUMSPICE
DEPARTMENT
OF
ENGINEERING
Tram
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GENERAL LIBRARY.
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30489
MODERN STEAM PRACTICE
AND ENGINEERING:
A GUIDE TO
APPROVED METHODS OF CONSTRUCTION AND
THE PRINCIPLES RELATING THERETO.
WITH
EXAMPLES, PRACTICAL RULES, AND FORMULÆ.
BY
JOHN G. WINTON, Engineer,
11
AUTHOR OF
MODERN WORKSHOP PRACTICE."
ASSISTED BY
W. J. MILLAR, C.E.,
Secretary of the Institution of Engineers and Shipbuilders in Scotland;
Author of "Principles of Mechanics," &c.
ILLUSTRATED BY ABOUT 800 ENGRAVINGS IN THE TEXT
AND A SERIES OF SEPARATE PLATES.

LONDON:
BLACKIE & SON, OLD BAILEY, E.C.;
GLASGOW, EDINBURGH, AND DUBLIN.
1883.
GLASGOW:
W. G. BLACKIE AND CO., PRINTERS,
VILLAFIELD.
жо
13-00
fillle
Rec
9-12--39
PUBLISHERS' PREFACE.
·
THE object of the present Work on MODERN STEAM PRACTICE
AND ENGINEERING is to furnish a reliable guide to the Practical
Engineer, a book to assist the draughtsman, the foreman, or the
workman in the engine shop and the building yard, to turn out, each
in his own department, well-designed, substantial, and thoroughly
finished work. In order that this may be satisfactorily accom-
plished some measure of acquaintance with the principles on
which the various operations rest is required, and formulæ and
demonstrations have therefore been introduced where necessary.
As a branch of Engineering Science the construction and working
of machinery must of necessity rest upon established laws, and no
engineer will seek to divorce the practice from the theory of his
profession; but the disastrous consequences occasionally arising
from inefficient material and workmanship in an engine, a ship, or
a bridge clearly point to the importance of attention to minute
practical details, and therefore attention to such details has been
steadily kept in view throughout the book.
An examination of the Table of Contents will give an idea of
the scope and arrangement of the Work. After a brief notice of
Coal and Coal-mining, the Boiler and the Treatment of Steam
are discussed. The Land or Stationary Engine in its many forms
and applications follows. The Marine Engine of the present day
is then treated of; followed by the Locomotive Engine British
and American, with details and specifications of various forms of
engine. The principles and constructive details of Shipbuilding
are considered, examples being given of some of our most suc-
cessful ocean liners and war ships. The larger part of the remaining
section is occupied with examples of Engineering works executed
within recent years. Numerous tables and rules will be found
iv
PUBLISHERS' PREFACE.
throughout the book; and a copious Index has been added, by which
ready reference can be made to the multifarious details in its pages.
In a Work dealing mainly with actual practice, it was not
thought desirable to introduce any of the untried inventions or
improvements which are often brought under the eye of the profes-
sional engineer; and notice has therefore been taken only of such
recent appliances as have been proved by actual work to be of
permanent value. Among these may be mentioned, rivetting by
hydraulic machinery, the manufacture of mild steel for boilers and
ships' plates, the continuous automatic brake on railways, double
bottoms and water-ballast tanks in shipbuilding, gas and hot-air
engines, and the compound arrangement of cylinder for the loco-
motive.
Much care has been bestowed on the preparation of the engrav-
ings placed in the text, as well as on the separate series of
engraved plates. These illustrations were felt to be an important
part of the book, elucidating as they do the text, and in many
cases conveying through the eye the information which it is difficult
to convey by words.
The Work now completed is the outcome of many years of prac-
tical experience by the author Mr. John G. Winton. The super-
intendence through the press has been carried out by Mr. W. J.
Millar, C.E., who has also contributed to the descriptive and theo-
retical treatment of parts of the Work. Thanks are due to the
gentlemen who, by their pen or the use of valuable drawings, kindly
contributed details of the most recent practice; to the Trănsactions
of various Engineering Societies; and also to our ably conducted
professional journals, especially The Engineer and Engineering, for
the information frequently derived from their pages.
GLASGOW, February, 1883.
CONTENTS.
THE BOILER AND STEAM.
COAL AND COAL-MINING. The Coal-beds of Britain-Boring for Coal-"Troubles"
in Working-Position and Form of the Shaft-Dangerous Gases-Ventilation
and Lighting of Mines-The Guibal and other Fans-Methods of working
Coal-Machines for Cutting-Utilization of Coal,
...
...
...
BOILERS FOR STATIONARY ENGINES:
Distinctive Forms of Boilers-Common Cylindrical-Cornish-Tubular—Self-
contained Flue—Vertical-Pot Boiler-With Suspended Annular Tubes—
Annular-Water-tube Boilers-Perkins System,
...
...
...
...
...
...
Shape and Rivetting of Boilers-Strength of Plates and Joints-Professor Ran-
kine's Rule-Prof. W. R. Johnson on the Strength of Cylindrical Boilers-Illus-
trations of their Bursting Pressure-Internal Flues-Table of Working and
Bursting Pressures-Strength of Rectangular Forms or Flat Surfaces-Factors
of Safety,
Strength of Round Boilers with different Qualities of Plates-Use of Steel-
Tables of Strength and Weight of Plates, Angle Irons, Bars, and Tubes,
Proportions for Parts of Land Boilers-Relative Value of Heating Surface,
Boiler Foundations-Form and Position of Boiler House-Construction of Flues,
Area and Dimensions of Chimney,
Arrangements for Smoke Prevention,
Systems of Tubing,
...
...
...
...
...
...
...
Page
I
IO
19
30
34
36
...
41
42
45
...
46
48
Dry Steam-Use of the Separator-Plans for taking Low-pressure Steam from
High-pressure Boiler,
Deterioration of Land Boilers-Experiments on, by testing them to destruction,
BOILERS FOR MARINE PURPOSES:
...
Flue and Tubular Boilers for Dredgers-Multitubular and Double Boilers-Over-
head Flues-Boilers for Royal Navy-Arrangement of Furnaces-High-pres-
sure Boilers-Boiler for Torpedo Boats-The Haystack Boiler,
Proportions for Marine Boilers-Fire Grate and Heating Surface for indicated
Horse-power--Staying-Fire Bars-Tube Area-Furnaces, &c.-Thickness.
of Plates-Strength versus Weight of Boiler-Funnel, Damper, &c.-Recent
Improvements-Boilers of the Steam Ship Parisian-Plates for Coal Boxes,
Prevention of Priming,
...
TREATMENT OF STEAM FROM THE BOILER TO THE CYLINDER.
...
...
...
51
62
78
Forms of Super-
79
heater-Covering of Steam Pipes,
MANUFACTURE OF BOILERS. Preparation and Fitting of the Plates-Punching
and Drilling Machines-Plate and Tube Stays-Report of the National Boiler
Insurance Co.-Safety Valves and Pressure Gauges-Setting of Boilers-
Cleaning-Use of Steel Plates,
85
vi
CONTENTS.
REGULATION OF STEAM BY THE SLIDE VALVE, as applied to Land, Locomotive,
and Marine Engines:
...
Form of older Valve without Lap-Valve with Lap-Proportioning the Slide
Valve-Lead-Back Pressure-Position of the Valve-Means of imparting
Reciprocating Motion-The Eccentric and Cam Arrangements—Link Motion
applied to the Land and to the Locomotive Engine-Slide Valves for various
forms of Engine-Starting Gear-Expansion Valve and Gear,
Geometry of the Steam Engine-Connecting Rod and Crank-Crank and Eccen-
tric Paths-Crank and Eccentric Paths delineated as regards the Cover, Lead,
and Cut-off-Double Eccentrics and Link Motion-Lap of the Valve varies
as the Cut-off and Length of Connecting Rod-Opening of Port by Valve
-Setting out the Valve Faces,
Relieving the Cylinder from Internal Pressure-Relieving the Slide Valve from
Back Pressure,
THE INDICATOR DIAGRAM. M'Naught's Indicator-Diagram from Eccentric
Valve Motion-Diagram from Corliss' Valve Gear-Examples of Compound
Engine Diagrams-Theoretical Diagram-Mechanism for actuating the Roller
of Indicator,
THE EXPANSION OF STEAM:
...
Tables of Hyperbolic Logarithms,
...
...
...
...
...
...
...
...
Page
94
II7
126
...
...
130
Properties of Steam and other Gases-Constituent Heat of Saturated Steam-
Relations of Pressure, Volume, Temperature, and Weight-Motion of Steam—
Velocities of Saturated Steam-Differences of Pressure in the Boiler and
Cylinder-Friction of a Fluid through a Pipe,
...
...
Table of Properties of Saturated Steam at different Pressures,
...
...
141
...
143
147
STATIONARY ENGINES.
{
PUMPING ENGINES FOR MINES:
Details of the Cornish Engine-Details of the Pumping Gear-Valve Gear—The
Cataract Condenser and Air Pump-The Ejector Condenser,
Horizontal, Overhead-beam, Side-lever, and Direct-acting Pumping Engine,
Pumping Gear for Direct-acting Engine-Examples of Pit Work,
Direct-action Compound Pumping Engine, ...
...
...
150
180
192
...
...
...
198
PUMPING ENGINES FOR WATER Works:
Single-acting Engine with Stand-pipe Tower-Engines at Wolverhampton Water
Works-Valve Regulator a substitute for Stand Pipe-Arrangement of the
Pump Valves-Gutta-percha Ball Valves on Metal Seatings-Berwick-on-
Tweed Water Works-Arrangement of Tanks, Engine and Boiler Houses-
Cost of raising Water,
...
...
...
Stand Pipes and Towers-Air Vessels-Stop, Relief, and Pressure Valves,
PUMPING ENGINES FOR DRAINAGE WORKS AND GENERAL PURPOSES:
The London Drainage System-Pumping Engines at Abbey Mills, Deptford,
and Crossness-Arrangement of the Pumps-Discharge of the Sewage into
Reservoir-Construction of the Pumping Station at Crossness,
High-pressure Geared Pumping Engines for emptying Docks, &c.,
The Centrifugal Pump-Gwynne & Co.'s Machinery-The Pulsometer,
WINDING ENGINES. Details of Construction,
BLOWING Engines:
202
221
226
235
236
...
239
:
Overhead-beam Blowing Engine-Details of Construction-Examples of Blowing
Engines erected at Dowlais Iron Works,
...
...
250
CONTENTS.
vii
Side-lever Combined Blowing Engines,
...
...
...
:
Vertical Blowing Engines-Vertical Table Engine,
Horizontal High-pressure Blowing Engines,
ROLLING-MILL ENGINES. Examples at Dowlais Iron Works-Arrangement of
Rolls for working in two directions,
COMPOUND Reversing Rail-MILL ENGINES. Examples at Hallside Steel Works,
near Glasgow,
...
...
...
...
Page
274
277
280
285
291
295
299
THE CORLISS ENGINE. Characteristic Features of this Engine-Diagrams from
Beam Condensing Corliss Engine,
HIGH AND LOW PRESSURE COMBINED BEAM ENGINE,
RULES FOR PUMPING ENGINES. Horse-power-Pumping of Water out of Docks—
Area of Cylinder-Valves-Duty of an Engine-To overcome Friction of
Water through Pipes-Delivery of Water in Pipes-Thickness of Pipes for
conveying Water-Standard Pipes for Water Supply-Weight of Cast-iron
Pipes-Pipes for Pit Pumps-Horse-power of an Engine-Diameter of
Cylinder and Length of Stroke-Speed of Piston-Opening of Port by Valve, 301
RULES FOR THE BEAM ENGINE. The Beam-Wrought-iron Tubular Beams—
Air Pump and Condenser-Cold-water Pump and Injection Water-Feed
Pump-Piston and Connecting Rods-Cranks and Crank Shaft-Fly Wheel
-Governor-Formulæ for Safety-valve Levers,
WATER-PRESSURE ENGINES. Early Hydraulic Cranes-Hastie's Variable Water-
power, Engine,
The Accumulator,
...
...
...
Pumping Engine for charging the Accumulator,
...
...
...
...
...
:
310
314
315
316
317
318
...
322
325
327
Water Wheels: Undershot, Overshot, and Breast-The Turbine,
The Hydraulic Crane-General Arrangement of Machinery-Details of Valves,
Water-pressure Cylinder for opening and closing Dock Gates,
Water-pressure Engines for working Dock Gates, Swing Bridges, &c.,
Water Power from Natural Falls-Engines at Lead Mines in Northumberland
and at Portland Harbour,...
Hydraulic Machinery for Warehousing Grain at the Liverpool Docks—Plan of
Warehouse Throwing-off Apparatus—Distributing Fan-Hoisting Gear, 329
HYDRAULIC MACHINE TOOLS-for Rivetting, Punching, Flanging, Bending or
Straightening-Hydraulic Machines at Arsenal, Toulon,
...
...
345
MARINE ENGINES.
THE OSCILLATING ENGINE:
Details of Construction,
Details of Slide-valve Gear-Starting Gear,
The Link Motion,
...
...
...
...
...
...
...
...
347
365
...
374
Specific Examples of Marine Engines-Steamers with Oscillating Engines-The
Steeple Engine-Side-lever Engine-Penn's Trunk Engine-Diagonal Direct-
acting Engine-Details of the Engine and Hull of the Comet,
The Paddle Wheel-Constructive Details-Disconnecting the Paddle Wheel—
Experiments with Ruthven's Hydraulic Propeller-Professor Rankine's Rule
for the Thrust of a Propeller,
HORIZONTAL DIRECT-ACTING AND RETURN CONNECTING-ROD ENGINES:
Details of Construction-Cylinder-Valves-Link Motion, &c.,
...
...
...
...
...
...
...
377
378
...
...
385
viii
CONTENTS,
...
...
...
Piston for Horizontal Marine Engines-Mr. Howden on Packing and Friction-
Mr. Rowan's form of Piston-Piston Rod-Crosshead and Guides-Con-
necting Rod-Cranked Shaft-Built Crank Shaft-Main Framing-Condenser
and Air Pumps,
Arrangements for Direct-acting Single Piston-rod and Double Trunk Engines,...
Surface System of Condensation-Construction and Arrangement of Surface Con-
densers-Making and Fitting of the Tubes-Arrangement of the Refrigerating
Surface-Pumps-Valves,
Hand Gear-Lubricators-Turning Gear,
Boiler Fittings-Valves-Steam Pipes-Separator-Lagging-Gauge Glass—
Scum Taps-Steam Whistles,
...
Page
424
450
454
Safety-valve Openings-Experiments and Formula-Loading of Safety Valves
by Direct Springs-Conclusions of Investigation Committee on Safety Valves, 462
THE SCREW PROPELLER:
...
Shafting for the Propeller-Repairing Couplings-Pillow Blocks-Stern Tube-
Hollow Propeller Steel Shafts,
Construction and Forms of the Propeller-Number and Configuration of the
Blades-Plan for lowering the Propeller below the Keel,
Raising the Screw Propeller and Shaft,
THE COMPOUND ENGINE:
...
...
General Adoption of the Compound Arrangement-Professor Rankine's Defin-
ition of a Compound Engine,
Arrangement of Cylinders,
Engines of the Parisian, &c.,...
...
Engines of the Screw Steamer Itata,...
...
...
...
Details of the Machinery of the Servia, Itata, and Sir Bevis,
Engines of the Arizona,
Governors for Marine Engines-Dunlop's Pneumatic Governor,
Three-cylinder Compound Steeple Engine for the Paddle Wheel,
:
:
:
47I
477
488
491
494
...
...
496
498
500
505
505
506
508
:
:
:
Table of Average Consumption of Coal, per indicated Horse-power per hour, by
Compound Engines on long Sea Voyages,
...
RULES FOR THE HORIZONTAL DIRECT-ACTION MARINE ENGINE, &c. Nominal
Horse-power-Proportion of Power to Tonnage-Rule for Tonnage-Per-
formance of Screw Vessels-Diameter of Cylinder-Stroke of Piston—Valves
-Eccentrics and Link Motion-Connecting Rod-Main Cranked Shaft-
Crosshead and Guides-Main Frame-Piston-Air Pump and Condenser-
Surface Condensation-Feed Pump-Screw Propeller-Proportions of Grif-
fith's Screw Propeller-Screw Aperture and Shafting-Hand and Turning
Gear-Safety Valve and Waste-steam Pipe-Copper Steam Pipes-Number
and Diameter of Kingston Valves and Blow-off and Injection Cocks-Flanges
for Copper Pipes,
...
•
...
...
...
510
...
LOCOMOTIVE ENGINES.
COMBUSTION IN THE LOCOMOTIVE. The Steam Blast-Its Mechanical Action-
Steam Jets-Arrangement of the Fire Box-Utilization of Smoke and Gases,
THE BRITISH LOCOMOTIVE:
531
547
...
554
Construction of the Boiler and Boiler Mountings-Fire Box-Stays-Dampers,
Shell of the Boiler-Steam Chest and Dome-Tubes-Smoke Box-Chimney—
Ash Pan-Fire Bars-Steam Pipes-Blast Pipe,
...
CONTENTS.
Safety Valves-Gauges-Whistles-Taps-Hand Rail-Stud for Lamp,
Construction of the Engine-Cylinders-Valves—Link Motion,
:
ix
Page
567
578
596
626
...
644
...
651
Piston-Piston Rod, Crosshead, and Motion Bars-Connecting and Coupling
Rods Cranked Axle-Axles and Wheels-Outside Cranks,
Framing and Axle Boxes-Springs and Harness-Compensating Levers,
Bogie Carriage-Buffers, Couplings, Rail Guards, Sand Boxes-Foot Plates and
Steps-Splashers, ...
Feed Pumps and Feed-water Apparatus-Connection Pipe between Engine and
Tender-Auxiliary Feed Pump-Injector,
THE AMERICAN LOCOMOTIVE:
...
...
...
Constructive Details of Boiler, Fire Box, Tubes, Smoke Box, Chimney, Steam
Pipe, Safety Valves, Gauges, Whistle, Bell, Sand Box,
Cylinder and Slide Valve-Valve Motion,
Piston-Piston Rod, Crosshead, and Motion Bars-Connecting and Coupling
Rods-Wheels and Axles and Crank Pins,
...
...
Framing and Axle Boxes-Bogie Frame-Cowcatcher-Cab-Springs,
Feed Pumps-Hose between Engine and Tender, ...
THE LOCOMOTIVE TENDER:
...
663
671
675
679
683
:
Construction of the British Tender-Brake Gear-Couplings with Engine-Water
Tanks and Feed Pipes,
Construction of the American Tender,
...
...
684
688
...
CONTINUOUS BRAKES:
Requirements of the Board of Trade-Varieties of Continuous Brake—Westing-
house Automatic Brake-Vacuum Automatic Brake,
Brake Resistances,
...
COMPOUND LOCOMOTIVE ENGINES. M. Malet's System-Mr. Webb's new Com-
pound Locomotive,
DESCRIPTION OF SPECIAL LOCOMOTIVE ENGINES:
Four-wheel Coupled Bogie Passenger Engine for the Caledonian Railway,
Express Engine for Great Northern Railway,
...
...
Passenger Engine for London and North-Western Railway,
Four-coupled Bogie Passenger Tank Engine on North British Railway,
Passenger Engines for Great Southern and Western Railway of Ireland,
Goods Engine for Great Southern and Western Railway of Ireland,
Goods Engine on Bombay, Baroda, and Central India Railway,
Furness Railway Tank Engine,
...
...
:
:
Narrow-gauge Engines for Steep Inclines-Festiniog Railway-Righi Railway
in Switzerland-Vesuvius Railway-Railroad in Canada,
Engines for Narrow-gauge Mineral Lines having Steep Gradients-Small Engines
coupled together-Details of small Tank Engines,
...
...
689
692
...
693
698
700
703
705
...
710
...
...
712
715
...
717
...
720
Express Engine for the Pennsylvania Railroad,
Haulage Power of Locomotives,
721
727
...
727
SPECIFICATION FOR LOCOMOTIVE ENGINE AND TENDER for London, Chatham,
and Dover Railway:
...
Leading Dimensions-Quality of Materials-Boiler-Fire Box-Workmanship-
Tubes-Smoke Box-Chimney-Safety Valves, &c.,
Frames-Buffers and Draw Gear-Cylinders-Pistons-Piston Rod and Cross-
head-Connecting and Coupling Rods-Valve Motion,
Bogie-Springs and Connections-Axles and Axle Boxes-Wheels-Tyres-Cab
and Splashers-Brake-Injectors-Boiler Mountings-Bolts and Nuts,
...
...
728
733
737
CONTENTS.
Page
Tender for Engine-Tank-Frames-Buffers and Draw Gear-Springs-Axles
and Axle Boxes-Wheels and Tyres-Brake-Painting Engine and Tender, 742
RULES FOR THE LOCOMOTIVE ENGINE:
Effective Pressure of Steam in Cylinder-Tractive Power of Engines-Resistance
of Trains due to Gravity on an Incline-Resistance of Trains at different
Speeds-Load of Engine on a given Incline-Adhesive Power of Locomotives
-Distribution of Load-To find Centre of Gravity horizontally-Loads on
the Axles,
•
...
746
Tables of the Diameter of Cylinders, Stroke of Piston, Diameter of Wheels, and
Wheel Base-Tables of Weight of six-wheeled Engines,
750
Diameter of Cylinder-Length of Steam and Exhaust Ports-Thickness of
Cylinder-Area of Piston Rod and Depth of Piston-Area of Slide-valve Rod
-Maximum Speed of Piston-Ratio of Diameter of Cylinder to Stroke of
Piston-Ratio of Stroke of Piston to Diameter of Driving Wheels-Water
and Steam required for a given Speed per hour,
...
...
The Boiler-Area of Fire Grate-Heating Surface-Strength of Boiler-Working
Steam Pressure-Screwed Stays-Pitch of Stays in Fire Box-Pressure on
Roof Stays-Weight and Stowage of Fuel-Area for Safety Valves—Diameter
of Feed Pump-Giffard Injector,
Area of Axles and Boxes-Dimensions of Wheels-Dimensions of Springs and
Harness-Dimensions of Framing-Area of Crosshead, Motion Bars, &c.—
Area of Connecting Rod-Outside Cranks and Side Rods,
ROAD LOCOMOTIVE OR TRACTION ENGINE. Thomson's India-rubber Tyres-
Mr. Crompton on improved Road Haulage-Dimensions of his Engines,
PORTABLE ENGINES. Description of Engine by the Reading Ironworks Co.,
STEAM ROAD ROLLER. Description of Road Roller by Aveling and Porter,
...
752
754
758
762
764
...
765
IRON SHIPBUILDING.
PRINCIPLES OF MARINE DESIGNING:
Classes of Steam Vessels-River Passenger Steamer-Ocean Passenger Steam
Ship Ocean Steam Ship for large Cargo-The Screw Collier,
Laying down the Lines of Vessels-Forms of Water Line-The Wave-line Prin-
ciple of Construction-Buttock Lines-The Decks,
Construction and Use of Models,
...
...
766
770
...
778
Full-sized Lines in the Moulding Loft-Practice on the Clyde-Lines of a Screw
Steam Ship,
...
...
...
780
Experimental Models and Speed Trials—Mr. Froude's Experiments-The Law
of Comparison-Ship Resistance-Professor Rankine's Formula-Mr. Wm.
Denny's Speed Trials—Mr. Mansel's Investigations-The Shah and Merkara, 782
BUILDING OF IRON VESSELS:
...
...
...
785
The HULL-Quality and Strength of Material,
Framing, &c.-Keels and Keelsons- Stern Posts of Screw Vessels-Connections
of Plate Keel and Keelsons to Forgings-Arrangement of Framing--Floor
Plates-Watercourses-Transom Plates-Reverse Angle Irons-Middle-line
Keelson-Box Keelson-Middle-line Intercostal Keelson-Bilge, Side, or
Sister Keelsons-Hold Stringers-Flat Plate Keels-Bilge Keels-Deck
Beams-Pillars-Stringers and Tie Plates on Beams-Bilge Keels and Double
Bottom of the Parisian-Midship Section of Paddle Steamer Lord of the Isles, 786
t
CONTENTS.
xi
...
...
...
...
...
...
..
...
...
...
...
...
...
...
...
...
Page
807
814
821
831
834
842
Plating, &c.-Thickness of Plates-Butt Straps-Lining Pieces—Rivetting and
Rivets-Top Sides-Transverse Bulkheads-Longitudinal Water-tight Divi-
sions,
The DECK, &c.-Wood Decks-Iron Deck-Framing of Hatchways-Engine
and Boiler Framing-Rudder-Riding Bitts—Bollard Heads-Cat Heads,
The MASTS, &c.-Iron Masts-Wedging Masts-Trusses for Lower Yards-
Chain Plates-Screw Chain Plates-Bitts around the Mast,
Water Ballast-Tanks for Colliers-Lloyd's Arrangement of Water-ballast
Spaces,
Strength of Iron Ships-Strains on a Vessel-Mr. Wm. John on Forces acting
on a Ship at Sea-Mr. Wm. Denny on our future Sea-going Steam Vessels,
Builders' Measurement and Register Tonnage,
Theory of the Stability of a Vessel-Centre of Gravity-Centre of Effort—Table
of Displacement of a River Steamer-To calculate the Displacement, Place of
its Centre of Gravity, and the Metacentre,
Graphic System of Investigation-Diagrams showing Curves of Stability, Weight,
Buoyancy, &c., by Mr. W. H. White,
Position of Paddle Wheels-Diagrams of Waves raised at maximum Trial Speeds
by Mr. James Hamilton,
Examples of recent large Steam Ships-The Orient―The Servia-The City of
Rome The Alaska-The Stirling Castle—The Livadia,
Structural Details-The Framework-Floor Plate-Keel Blocks-Sections for
Deck Beams-Deck Fastenings-Bulkheads-Water-tight Keelsons,
Plating and Rivetting-Diagonal System of Plating—Intermediate Break-bond
System-Rivet and Countersink-Putting the Plates in Position-Rivetting, 878
The Longitudinal System of Framing-Comparison between the Longitudinal and
Transverse Systems,
...
Position of the Masts in a Sailing Ship,
...
...
...
...
-Fore Mast and Yards-Mizen Mast and Yards, &c.,
...
...
...
...
844
858
863
865
870
883
...
...
...
...
...
...
887
Proportions of Masts, Yards, &c., for Merchant Service-Main Mast and Yards
889
Terms applied to the Hull of a Ship,
Terms applied to the Masts, Rigging, &c.,
894
Terms applied to the Sails,
Launching of Large Vessels,
...
...
:
:
898
900
...
...
...
...
901
Tables of Weight of Angle Iron, Length of Rivets, Wire Ropes for Rigging,
Diameter and Weight of Chain Cables,
...
:
:
905
907
908
Steam-steering Gear,
...
Refrigerating Machinery for Ships,
...
ARMOURED AND UNARMOURED WAR SHIPS. Earliest French and British Ironclads
-The Hercules-Devastation-Thunderer-Mr. Barnaby's Description of the
Inflexible-Structural Details of her Hull and Appendages-Description of
the Colossus-Sir William Armstrong on Unarmoured Cruisers-Structural
Arrangements of the Iris-Unarmoured Corvettes-The Leander, Arethusa,
and Phaeton-Belted Cruisers-Torpedo Boats-The Polyphemus,
VESSELS FOR DREDGING:
...
Dredger and Hopper Barge constructed by Messrs. Wingate & Co. of Glasgow—
Dredger adapted to cut in front-Double Dredger of 45 horse-power-Dredger
of 25 horse-power,
Combined Hopper Dredger designed by Mr. Andrew Brown-Dredgers by
Messrs. Simons & Co. of Renfrew,
...
...
...
Dredgers on the river Clyde-Their Dimensions, Cost, and Work,
909
930
936
...
937
xii
CONTENTS.
Į
EXAMPLES OF SPECIFICATIONS:
Requirements under Lloyd's Rules,
...
...
1. Specification of a Screw Steamer of 1767 tons,
2. Specification of a Screw Steamer of 2000 tons B.M.,
3. Specification of a Screw Steamer of 790 tons B.M.,
4. Specification of a Screw Collier of 1500 tons B.M.,
...
...
:::
:::
::
:
Dimensions of Masts, Spars, &c., for a Vessel similar to No. 3 Specification,
EXAMPLES OF SCANTLING:
Scantling for a Clyde River Boat, 225 feet keel,
Scantling for a Clyde River Boat, 154½ feet keel,
Scantling for a small River Boat on the Thames,
Scantling for a small Paddle Steam Vessel of Steel,
Scantling for a Dredger,
Scantling for Mud Barges,
...
: : :
::
Page
...
939
940
947
949
954
...
956
957
: : :
: :
958
958
959
959
960
STEEL for SHIPBUILDING. Constituents of Iron and Steel-Manufacture of Steel
-The Siemens, Bessemer, and Thomas-Gilchrist Processes-Dr. Siemens on
Iron and Steel Ships-Corrosion of Iron and Steel Plates-Tables of the
Weight and Volumes of Iron, Steel, and other Metals-Tempering of Steel
Tools-Admiralty Tests for Plate, Angle, Bulb, and Bar Steel-Lloyd's
and Underwriters' Registry Tests for Steel used in Shipbuilding,
ENGINEERING WORKS, ETC.
CONSTRUCTION OF FLOATING DOCKS:
Description of two Floating Docks, and Scantling,
Navigable Floating Dock and Battery, designed by the Author,
CONSTRUCTION OF IRON ROOFS:
...
• 960
967
973
Strains on a Plain Truss-Covering for Iron Roofs-Roofing for Boiler Houses, 975
Strains on an Arched Truss-Arched Roofs-Roof of South-Eastern Railway
Station, Cannon Street, London-Roof of St. Pancras Railway Station,
London-Roof of the Great Northern Railway Station, London-Roof of the
Joint Railway Passenger Station, New Street, Birmingham-Roof of St.
Enoch Railway Station, Glasgow,
Table of the Scantling of Iron Roofs,
...
...
Tables of the Size and Weight of Iron Laths, and Weight of Roof Coverings,
STRAINS ON WROUGHT-IRON GIRDERS, &c.:
Strains on Girder of I Section,
Cantilevers,
...
...
Professor Rankine on Action upon Beams,
CONSTRUCTION OF GIRDER BRIDGES:
...
►
981
994
...
...
...
996
...
996
...
999
Examples of such Bridges with Roadways at top or bottom-Breaking Weight
for Wrought-iron Box Girders-Strain on Top and Bottom Flanges-Crumlin
Viaduct―Tubular Girders-Conway and Britannia Bridges in Wales and
Victoria Bridge in Canada-Bowstring Girder-Bridge over the Elbe,
Plating Girders,
Drilling the Plates,
...
...
ΙΟΟΙ
...
1002
1006
...
1007
Scantling and Weight of Railway Bridges erected on the Plain-girder Principle, 1007
CONSTRUCTION OF LATTICE GIRDER BRIDGES:
Principles of Construction,
...
...
Details of Construction-Example of a Trellis Girder Bridge,
IOII
...
...
...
1015
#
CONTENTS.
xiii
Formula for Lattice Girder Bridge,
...
Details of Lattice Girder Bridge over the Ohio,
CONSTRUCTION OF SUSPENSION BRIDGES:
...
Page
1032
...
...
1033
Clifton Suspension Bridge at the Falls of Niagara-General Dimensions-Con-
structive Details-Strength of the Bridge, Cables, and Stays-Effects of Tem-
perature and of the Wind-Manufacture of the Cables, Stays, Suspenders, and
Guys-The Towers,
Details of East River Bridge, New York,
1036
...
...
Other Large-span Bridges-The Forth Bridge-Bridge over the Douro,
Action of Wind on Bridges and Chimneys,
Tabulated Statement of some Bridges of large Span,
...
1052
...
1053
...
...
...
1054
1055
MARINE AND SUBMARINE WORKS:
Submarine Tunnels-The Mersey, Severn, and Hudson Tunnels,
Lighthouses-Eddystone-Lighthouse in Iron and Concrete,
Details of Swing Bridge at Leith Docks,
CONSTRUCTION OF TUBULAR WROUGHT-IRON CRANES :
Examples of Small-sized Cranes at Devonport Dockyards-Their Deflection,
Details of Sixty-ton Crane erected at Devonport Dockyards,
...
...
...
...
1056
1058
тоб
...
...
1069
1071
Arrangement of a Forty-ton Crane,
Portable Steam Crane at Glasgow Harbour,
Cranes for Tipping Coal Waggons, Masting, &c.,
...
1076
...
1077
...
1077
Seventy-ton Steam Crane erected at Dundee by Taylor & Co. of Birkenhead,
Five-ton Steam Crane for Ships,
Winches for Ships,
STEAM FIRE ENGINE. Details of Engines by Merryweather and Sons, and Shand,
Mason, & Co.-Engine for River and Harbour Work,
1080
...
1081
...
...
1083
1085
GAS ENGINE. Details of Otto's Engine-Clerk's Engine,
CALORIC OR HOT-AIR ENGINE,
...
...
...
1087
1090
ELECTRIC MOTORS,
...
1091
1091
ELECTRIC LIGHTING. The Incandescent Lamp,
THE STRENGTH OF MATERIALS:
Cohesive Strength of Bodies—of Timber-of Steel, &c.-Transverse Strength of
Bodies-Strength of Rectangular Beams-Table of Lateral Strains-Safe Loads
for Beams-Torsion or Twisting-Crushing and Bending-Table of Tensile
Strength of Wrought-iron Plates-Tenacity of Stone, &c.-Compressive
Strength of Wrought Iron-of Steel-of Wood-Stone, &c.-Factors of Safety, 1093
Specific Gravity of Materials-Iron-Seasoned Woods-Fluids and Gases-
Metals-Stones-Artificial Substances,
...
MECHANICAL MEANS FOR TRANSMITTING POWER,
THE PARALLELOGRAM OF FORCES,
FORMULA FOR WHEELS, SHAFTS, &c.:
...
...
...
...
...
1099
ΙΙΟΙ
1102
Teeth of Wheels-Strength of Round Shafting to resist Lateral Stress-Shaft
Bearings-Couplings and Distance between Pillow-block Supports-Pulleys, 1104
Fittings for Line Shafts,
INDEX,
:
:
...
:
...
1107
IIII
LIST OF THE PRINCIPAL TABLES IN THIS WORK.
Page
905
28
25
1094
1055
854-857
ANGLE IRON, Weight of,
...
BOILERS, Working and Bursting Pressures of,
11
Proportionate Strength of Cylindrical,
BREAKING STRAIN, Lateral,
...
...
BRIDGES OF LARGE SPAN, Tabulated Statement of,
Centre of GRAVITY, &c., in Shipbuilding,
CHAIN CABLES, with suitable Anchors, Diameter and Weight of,
COAL, Average Consumption of, per indicated Horse-power per hour,
COHESIVE STRENGTH of various Materials,
...
...
COMPRESSIVE STRENGTH of Steel by various Manufacturers,
11
"
COPPER PIPES, Flanges for,
of Wood, Stone, &c.,
CRANES, Deflection of Tubular Wrought-iron,
DISPLACEMENT of a River Steamer,
FACTORS OF Safety,
...
·
Fluids and GASES, Specific Gravity, Weight, and Expansion of,
FRAMING OF A SHIP, Longitudinal and Transverse Systems of,
GRIFFITH'S SCREW PROPELLER, Proportions of,
Hull of a SHIP, Terms applied to the,
HYPERBOLIC LOGARITHMS,
...
...
IRON, Weight of a lineal foot of Square and Round Bar,
LATHS, Size and Weight of Iron,
...
:
:
...
:
:
:
:
:
...
...
...
:
:
:
:
...
...
...
:
:
LOCOMOTIVE ENGINES, Diameter of Cylinder, Stroke of Piston, &c.,
Dimensions of Small Tank Narrow-gauge,
:
:
:
:
906
508
1093
1098
1098
529
1070
853
1098
1100
884
526
897
141
34
996
750
#1
11
724
11
Haulage Power of, at speed of 20 miles an hour,
Heating Surface in,
728
755
Performances of,
711, 712, 714
11
751
...
637
...
Weight of, of various classes,
SPRINGS, Deflections of, under given Loads,
MASTS, RIGGING, &c., Terms applied to the,
METALS, Specific Gravity of,
Weight and Volume of,
...
...
PIPES FOR WATER SUPPLY, Proportions of Socket for Standard,
PLATES, Mean Strength of, in direction of and across fibre,
:
:
...
:
:
11
Tensile Strength of Single and Double Rivetted,
...
Weight of a square foot of Wrought-iron, from 1 to 1 inch thick,
RIVET, Length of, allowed for various thicknesses of Plate,
RIVETTED JOINTS, Strongest Form and Proportion of,
ROOFS, Weight of different Coverings for,
2
...
...
898
II00
964
:
:
:
:
307
32
33
33
905
31
996
Sails of a SHIP, Terms applied to the,
Saturated STEAM, Properties of, at different Pressures,
SCANTLING for Iron Roofs,
...
for Railway Bridges,
...
11
for various sizes of Vessels,
SPECIFIC GRAVITY of various Materials,
...
...
Tensile StrenGTH of Wrought-iron Plates at various temperatures,
TUBES, Surface and Weight of Iron, Brass, and Copper,
:
:
:
:
901
147
994
1007
...
957
1099, 1100
1097
34
WIRE ROPES, Iron and Steel, for Ships' Standing Rigging, Comparison of,
906
LIST OF PLATES.
Page
250
TEMPERING OF STEEL TOOLS.-COLOURED PLATE SHOWING SCALE-
USED FOR TEMPERING DIFFERENT CLASSES OF STEEL TOOLS. Devised by
Messrs. Park Benjamin and Joshua Rose, United States,
frontispiece 965
WINDING MACHINERY.-WINDING ENGINES, WITH DOUBLE ECCENTRICS,
LINK MOTION, AND TAPPET VALVE GEAR. Erected in 1881 by Messrs.
Gibb and Hogg, Airdrie, for the Benhar Coal Company,
ROLLING MILL MACHINERY.-COMPOUND REVERSING ROLLING MILL
ENGINES, Steel Company of Scotland's Works at Hallside, near Glasgow.
Constructed by Messrs. Miller and Co., Coatbridge,
HYDRAULIC MACHINE TOOLS.-HYDRAULIC MACHINES FOR RIVET-
TING AND FLANGING PLATES, RIVETTING KEELS, AND ANGLE IRON OR
BEAM STRAIGHTENER OR BENDER. Designed by Mr. R. H. Tweddell,
London,
MARINE ENGINE.-THREE-CYLINDER COMPOUND INVERTED ENGINES OF
STEAM SHIP "PARISIAN." Constructed by Messrs. Robert Napier and
Sons, Glasgow,
MARINE ENGINE.-THREE-CYLINDER COMPOUND DIRECT-ACTING ENGINES
Constructed by Messrs. James and George
OF STEAM SHIP "SERVIA."
Thomson, Glasgow,
291
•
345
LOCOMOTIVE ENGINE. VERTICAL AND HORIZONTAL SECTIONS OF BOGIE
PASSENGER ENGINE. Built for the Caledonian Railway by Messrs. Neilson
and Co., Glasgow,
LOCOMOTIVE ENGINE. -TRANSVERSE SECTIONS OF BOGIE PASSENGER
ENGINE. Built for the Caledonian Railway by Messrs. Neilson and Co.,
Glasgow,
496
•
500
698
698
PORTABLE ENGINE.-VERTICAL AND TRANSVERSE SECTIONS OF EIGHT
HORSE-POWER PORTABLE ENGINE. Constructed by the Reading Ironworks,
Limited,
764
•
IRON SHIPBUILDING. — LONGITUDINAL SECTION AND DECK PLANS OF
THE SCREW STEAM SHIP "ORIENT." Built and engined by Messrs. John
Elder and Co., Glasgow,
DREDGING MACHINERY.-PATENT COMBINED HOPPER DREDGER, to
dredge in 20 ft. depth of Water and carry 200 tons in its own Hopper. De-
signed by Mr. Andrew Brown of Messrs. W. Simons and Co., Renfrew, .
ENGINEERING WORKS.-LATTICE GIRDER RAILWAY BRIDGE OVER THE
RIVER OHIO AT BEAVER, PENNSYLVANIA, U.S.A. Length 1376 ft. with
1080 ft. of Viaduct Approach,
•
•
•
865
936
1033
1080
HOISTING MACHINERY.-SEVENTY-TON Steam Crane, VICTORIA BASIN,
DUNDEE. Constructed by Messrs. James Taylor and Co., Birkenhead, .
STEAM FIRE ENGINE. - FRONT VIEW, PLAN, ELEVATION, SECTION
THROUGH PUMP, CYLINDER, AND BOILER, OF A SINGLE-CYLINDER STEAM
FIRE ENGINE. Constructed by Messrs. Merryweather and Sons, London, 1085
•
WINDING ENGINES.


WINDING ENGINES, WITH DOUBLE ECCENTRICS, LINK MOTION, AND TAPPET VALVE GEAR.
ERECTED IN 1881 BY MESSRS. GIBB AND HOGG, AIRDRIE, FOR THE BENHAR COAL COMPANY.
Diameter of Cylinders, 3 ft. 4 in.
Length of Stroke of Pistons, 5 ft. 6 in.
Diameter of Winding Drum, 18 ft.
P
LONGITUDINAL SECTION.
F
E
E
F
X
H
L
X
V
I
K
HOM
Σ
Y
Z'
2
א
AA Cylinders.
BB Cylinder Covers and Stuffing-box Glands.
cc Piston Rods
DD Prolongation of the Piston Rods.
EE Steam Valves.
FF Exhaust Valves.
GG Valve Casings.
HH Double Eccentrics and Link Motion.
1 Suspension Link.
K Weigh Shaft.
L Lifting Rod in communication with the
Starting Handle.
L' Starting Handle.
M Handle for Stop Valve.
M' Shaft for Stop Valve.
N Lever Handle for Brake.
N' Shaft for Brake Gear.
oo Brake Blocks (of wood).
P Fly Wheel or Drum.
QQ Turned Parts for Brake Blocks.
RR Crossheads and Gudgeons.
ss Connecting Rods.
TT Wrought-iron Cranks.
UU Wrought-iron Crank Shaft.
vv Sole Plates.
ww Pillow Blocks.
xx Motion Bars.
YY Stop Valve and Steam Pipe.
z Exhaust Pipe.
z' Foundation of Concrete.
T
Q
W
H
V
ន
II
R
P
N'
U
Q
T
z'
PLAN.
W
H
V
© X
I
B
C
X
X
H
Y
A
G
E
Υ
Y
2
B
HAD
H
E
F
R
S
B
C
X
G
A
L'
M
N
B
H
D
ROLLING MILL ENGINES.
Y
Y
A High-pressure Cylinder.
B Low-pressure Cylinder.
B' Steam Receiver.
cc Piston Valves.
DD Valve Chests.
E Valve Spindles.
FF Pistons and Rod.
G Crosshead.
H Connecting Rod.
1 Crank Shaft.
K Crank Discs.
L Double Eccentrics and Link Motion.
M Weigh or Reversing Shaft.
N Small Engine for Starting and Reversing.
o Starting Handles.
P Main Framing.
Q Pillar Blocks with Steel Covers.

R Slide Bars.
s Side Framing.
T Oval Boss with Steel Hoop for securing Side Framing.
U Sole Plate.
V Auxiliary Slide Valve.
w Escape Valves.
x Steam Pipe.
Y Stop Valve.
z Platform.
W
A
X
12 8 4 0
W
Π
U
4
5
6
10
11
D
B'
C
E
D
V
D
12 feet.
B
A
-F
LONGITUDINAL SECTION.
B
R
HALF PLAN SECTION.
G
P
Р
N
M
H
Р
I
R
M
H
R
P
Ο
曲​:
T.
א
Ꮓ
Q
U
T
Ι
Q
Ο
O
K
P
Q
D
I
Q
COMPOUND REVERSING ROLLING MILL ENGINES, STEEL COMPANY OF SCOTLAND'S WORKS AT HALLSIDE, NEAR GLASGOW.
CONSTRUCTED BY MESSRS. MILLER & CO., COATBRIDGE.
P
S
HYDRAULIC MACHINE TOOLS.


K
N
A
K
-D
C
र्ब
B
F
L
H-
G
H
E
M
1 Keel of Ship.
M Handle and Screw for adjusting the Rivet. N Balance Weight.
Fig. 4.-MACHINE FOR RIVETTING KEels.
A Trolly. BB Post supporting Turntable. c Pair of Levers. D Carriage
vertical adjustment. HH Flush-topped Cylinder.
E Rivetter. F Parallel Motion, with Eccentric G, and Handles for
K Bottom Plates of Ship. L Hand Wheel for moving the Trolly.
D
H
H
M
B
Fig. 1.-PORTABLE RIVEtter.
A Cylinder.
B Fulcrum.
cc Rivetting Dies.
D Gap, closing large Rivets.
F Tension Rods which draw
the Levers together and
adjust the space G be-
tween them.
E Gap, closing small Rivets; нн The Hydraulic Ram carry-
in this case Abutments
ing the Moving Lever M.
B are transposed with
Dies c c.
K Valve for admitting and
exhausting the water.
I'
Ι
A Stop Valve on Mains.
BB Walking Pipes.
c Swivel Joint.
D Connecting Pipe to Swivel E.
F Carriage.
G Hydraulic Lift.
н Pipe conveying pressure from the
Lift to the Rivetter.
11 Pipe conveying water to the Swivel Q.
1'1' Walking Pipes conveying water to
the Hydraulic Lift.
K Rivetter, 4′6″ opening.
1. Arm of Frame.
M Balance Weight.
K
G
D
B.
B
L
K
C
B
JAGANNADmnana
A
F
G
E
H
A
M
B
Fig. 5.-ANGLE-IRON OR BEAM STRAIGHTENER OR BENDER,
from 5 to 100 tons power.
A A Right- and Left-handed Screws, carrying the Abutting Blocks BB, on
which rests the Angle Iron to be bent c, by the Block D, controlled by
Tappet Gear which regulates the supply of water.
E Tappet Gear working Valve F, admitting pressure to the Cylinder G,
in which works the Ram H, carrying the Block D.
KK Elevating Screws to vary height of work being bent.



M
A
H
I
L
C
T
K
AB Top and Bottom Castings.
c Moving Table or Follower.
E
D Matrix.
E Block.
F Lower or holding-up Cylinder.
G
D
G Vice-Table.
H Plunger for Vice-Table.
1 Main Cylinder.
K Valves.
L Main Ram carry-
ing the moving
Table C.
B
H
F
Fig. 2.—TRAVELLLING CRANE FOR RIVETTER.
Fig. 3.-HYDRAULIC PRESS FOR FLANGING Plates.
HYDRAULIC MACHINES FOR RIVETTING AND FLANGING PLATES, RIVETTING KEELS, AND ANGLE-IRON OR BEAM STRAIGHTENER OR BENDER.
DESIGNED BY MR. R. H. TWEDDELL, LONDON.

ENGINES OF STEAM-SHIP "PARISIAN."
Two Low-pressure Cylinders (each 85"
diam.), with one High-pressure Cylin-
der (60" diam.) between them. Stroke
of each Piston 5 ft. Steam Pressure
70 lbs. Condensing Surface 9624 sq. ft.
Indicated Horse-power 6019.
O
1310
000
0 D
O
о
O
Stuffins
RIMBAULT SC
THREE-CYLINDER COMPOUND INVERTED ENGINES OF STEAM-SHIP "PARISIAN,"
5359 TONS GROSS.
CONSTRUCTED BY MESSRS. ROBERT NAPIER AND SONS, GLASGOW, FOR THE
ALLAN LINE OF ROYAL MAIL ATLANTIC STEAMERS.
12
R2
Z+
N
Q1
C
D1
E
T3
T
Bl
G
11
U
V
D
B
P
B2;
N
Z5
E
=
H
N.
Kl
W
1 2 3 4
L
N
Q1
Fl
Fl
C
H
Q1
H
N
M
Z
E
ENGINES OF STEAM-SHIP
D1
C
B
P
E
Q
Z5
25
21
74
Q1
W
10
SERVIA."


EXPLANATION OF LITERAL REFERENCES.
A High-pressure Cylinder with Steam
Jacket.
A1 Steam Ports.
A2 Exhaust Passage to the Low-pressure
Cylinders.
BB Low-pressure Cylinders with Steam
Jackets.
B¹ Steam Ports.
B2 Exhaust Port into the Surface Con-
denser.
cc Cylinder Covers.
DD Stuffing Boxes and Glands for Piston
Rods.
D1 D1 Stuffing Boxes and Glands for pro-
longation of Piston Rod.
EE Escape Valves.
FF Piston Valves for the High-pressure
Cylinder.
F1 Piston for carrying up the weight of
the Valves.
G Slide Valve for the Low-pressure
Cylinders.
H Piston for carrying up the weight of
the Valve.
I Spring on the back of the Valve.
K High-pressure Valve Spindles. Link
and Lever in connection with the
Double Eccentrics and Link Motion
for the High-pressure Cylinder.
K¹ High-pressure Piston Valve Rocking
Shaft.
L Double Eccentrics and Link Motion
for the High-pressure Valves.
M M Valve Spindles for the Low-pressure
Cylinders.
NN Double Eccentrics and Link Motion
for the Low-pressure Cylinder Valves.
o Steam and Hydraulic Starting Gear,
with Shaft, Lever, and Rods, in
connection with the Link Motion.
P Auxiliary Starting Valve.
pl Steam Pipe.
Q Main Framing for supporting the
Cylinders.
QQ¹ Pillow Blocks for the Crank Shaft.
R Piston for the High-pressure Cylinder:
R1 Piston Rod.
R2 Prolongation of the Piston Rod.
R Nut for securing the Piston.
s Crosshead and Gudgeon.
T Piston for the Low-pressure Cylinder.
T1 Piston Rod.
T Prolongation of the Piston Rod.
T Nut for securing the Piston.
U Crosshead and Gudgeon.
v v Connecting Rods.
w Crank Pin and Shaft.
x Surface Condenser.
y Air Pump.
yl Cover.
y Bucket.
y³ Head Valves.
y4 Hot Well.
y5 Air Pump Discharge Pipe.
z Air Pump Rod.
z¹ Prolongation of the Air Pump Rod.
z² Guide for the top of the Air Pump
Rod.
z3 Links connecting the Air Pump Cross-
head with the Rocking Levers.
z¹ Rocking Levers.
ză Links connecting the Rocking Levers
with the Piston Rod Crosshead.
z6 Throttle Valve and Steam Pipes from
the Boiler.
Hand Gear.
1, Starting Cylinder Valve.
""
2, Low-p. Auxiliary Starting Slide Valve.
3, High-p.
>>
""
4, Low-p.
""
""
""
5, Conical Valve to admit Steam to Reser-
voir.
6, Double-beat Valve to admit Steam to
High-pressure Valve Casing.
7, Jacket Drain Plug Taps and Handles.
8, High-pressure Cylinder Drain Plug
Taps and Handles.
9, Low-pressure Cylinders Drain Plug
Taps and Handles.
ro, Common Injection Valve.
THREE-CYLINDER COMPOUND DIRECT-ACTING ENGINES OF STEAM-SHIP "SERVIA," 7400 TONS GROSS.
CONSTRUCTED BY MESSRS. JAMES AND GEORGE THOMSON, GLASGOW, FOR THE CUNARD
GLASGOW, FOR THE CUNARD LINE OF ROYAL MAIL ATLANTIC STEAMERS.
0
C
D
R
R1
L
L
R3
A
ԱՄ
Α1
Q
F
K
F
10.
X
HZ6
24
One High-pressure Cylinder
72" diam., and two Low-
pressure Cylinders each
100" diam. Stroke of Pis-
ton 78". Two Surface
Condensers, placed fore
and aft. Seven Boilers of
oval form, 14' 10" wide,
18′ high, and 18′ 3″ long;
having thirty-nine Fur-
naces 4′ 2″ diam. and 6′ 9″
long. Effective Grate Sur-
face 1050 sq. ft.; total
Heating Surface 27,000 sq.
Diameter of Propeller
24 ft.
Indicated Horse-
ft.
power 10,500.
Y
Υ
Y2
༔ 。。。
Z2
5
14
A Fire Box.
B Tubes. c Stays.
D Smoke Box.
E Smoke Box Door.
F Chimney.
G Fire Bars.
н Ash Pan.
I Stays.
K Fire Door.
LL Sludge Plugs.
M Steam Dome.
N Safety Valves.
oo Steam Whistles & Handles.
P Cylinder.
Q Slide Valve.
R Regulator, Valve.
s Handle for Regulating Valve.
T Blast Pipe.
u Grease Cup.
v Eccentrics & Link Motion.
w Weigh Shaft, with Levers
and Rod connecting with
Starting Handle wa.
xa xb xc Piston, Rod, Cross-
head. xd Guide Bars.
y Connecting Rod.
ii Buffer Beam, and Hook
with Spring.
k Buffer.
/ Guard.
m Axle Box and Guides for
Driving Axle.
» Axle Box and Guides for
Trailing Axle.
oo Springs.
Compensating Lever.
9 Cab.
Frame for Platform.
s Splasher.
t Injector, with Feed Pipe t'.
❝ Check Valve on the body of
Boiler.
Blow-off Tap.
Steam Pipe for Injector.
x Socket for Lamp.
y Covering for Steam Dome.
Cleading.
z Water Pipe to the Tender.
Sand Box and Pipe.
z Driving Axle.
a Trailing Axle.
bb Bogie Axles.
cc Wheels.
d Crank Pin.
e Side Rod.
f Main Frame.
g End Beam.
hh Drag and Safety Pins.
36...
k
4.0"
75%
·
6'. 9°
12'. 11"
胖
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1.3%
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LOCOMOTIVE ENGINE.

DIAMETER OF CYLINDERS,
18
INCHES.
LENGTH OF Stroke,
24 INCHES.
DIAMETER Of Coupled Wheels,
DIAMETER OF BOGIE WHEELS,
WHEEL BASE,
7 FEET
2 INCHES.
R:
3 FEET 42 INCHES.
21 FEET
22 INCHES.
HEATING SURFACE IN TUBES,
HEATING SURFACE IN FIREBOX,
AREA OF FIREGRATE,
905 SQ. FEET.
82 SQ. FEET.
14'6 SQ. FEET.
4'. 2..
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VERTICAL AND HORIZONTAL SECTIONS OF BOGIE PASSENGER ENGINE.
BUILT FOR THE CALEDONIAN RAILWAY BY MESSRS. NEILSON & CO., GLASGOW.
P
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43/8
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22

D Smoke Box.
E Smoke-box Door.
F Chimney.
PP Cylinders.
Q Slide Valve.
R Cover for Valve Casing.
s End Cover.
T Blast Pipe.
U Steam Pipe.
v Branch for Steam Pipe.
w Solid Ring.
xx Rivets for securing the Solid
Ring to Barrel of Boiler.
y Bottom of the Smoke Box.
z Hand Rail.
a a Studs for Hand Rail.
bb Clothing Plates for Cylinders.
cc Bogie Wheels.
dd Hinges and Handle for secur-
ing Smoke-box Door.
e Studs and Pin for Hinges.
ff Main Framing.
g
Platform.
h Bogie.
¿ Swivelling Centre.
·
·
P
18 diám
1.4½
10°
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Length 4. 3 inside diam 4° N° 8 W.G.
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LOCOMOTIVE ENGINE.
444.
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α
1.54
k Frame for carrying Central
Plate on which Bogie swivels.
77 Bogie Frame.
m Stays.
nn Springs.
oo Studs for taking Spring
Bolt.
g Volute Spring.
✓ Oil Cup.
s Splasher.
tt Blow-off Taps on the Cylinders
and Valve Casings, with Levers
and Rods passing along to
Starting Platform.
u Tube Plate in the Smoke Box.
v Tubes.
ww Stays.
x Mud Plug.
y Socket for Lamp.
z Auxiliary Blower Pipe.
63
I
SECTION THROUGH FIRE BOX.
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flush
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44 rivets flush outside
R
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12'36
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Stay heads thus
between frames.
H
234
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3.8 Centres
4.5% between tyres
A Fire Box
A' Crown of Fire Box.
A” Sides of Fire Box.
B Tubes.
cc Stays.
GG Palms for supporting Frame
for Fire Bars, &c.
H H Stays.
II Stays.
K Fire Door.
TRANSVERSE SECTIONS OF BOGIE PASSENGER ENGINE.—BUILT FOR THE CALEDONIAN RAILWAY BY MESSRS. NEILSON & Co., GLASGOW.
LL Holes for Plugs.
M Hole for Blow-off Tap.
N Seating for Safety Valves.
o Body of the Boiler.
ff Main Framing.

F
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PORTABLE ENGINE.
H
D
T
M
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N
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M
S
A Fire Box.
B Tubes.
c Smoke Box.
D Funnel.
E Ash Pan.
F Cylinder and Valve Casing, &c.
G Motion Bars, Crosshead, &c.
H Connecting Rod.
I Cranked Shaft.
K Fly Wheel.
LL Brackets for carrying the Cranked
Shaft.
м Feed Pump driven by an Eccentric.
N Blast Pipe.
o Regulator Handle.
P Safety Valve.
Q Governor.
R Front Wheels with Swivelling Axle.
s Back Wheels with Fixed Axle.
T Stay Rod.
VERTICAL AND TRANSVERSE SECTIONS OF EIGHT HORSE-POWER PORTABLE ENGINE.
CONSTRUCTED BY THE READING IRONWORKS, LIMITED.
fool
PRINCIPAL DIMENSIONS.
LENGTH BETWEEN PERPENDICULARS,
Breadth of BEAM,
DEPTH, Moulded,
GROSS TONNAGE,
E
CUTTER
ENGINES, COMPOUND.
CYLINDERS, one 60 in. anD TWO 85 IN.
445 FT.
46 FT.
Length of Stroke,
36 FT. 10 IN.
INDICATED HORSE-POWER,
5385 TONS.
DIAMETER OF Propeller,
ன
CUTTER
Foo
26
20
26
25
28
26
28
28
28
28
28
28
BER
2 9
B
PEETE
28
28
28
S A L
D
SKYLIGHT.
28
2B 28
28
N
28
28
28
28
2B
26
2**
HATCH
HATCH
5 FT.
..
5500.
22 FT.
WINCH
WINCH
I
A
I
C
LIFE BOAT
STEAM-SHIP "ORIENT.”
A A Boilers.
BB Funnels.
D Shafting.
GG Coal Bunkers.
E Screw Propeller.
c Engines.
FFF Stoke Holes.
H High-pressure Cylinder.
II Low-pressure Cylinders.
LONGITUDINAL SECTION.
B
B
A
G
F
F
F
UPPER DECK PLAN.
2 B
FIREMEN
28 ZB 28
FIREMEN
26
28
26
HOSPITAL
2NO
ENGINE
CLASS
FUNNEL
CALLEY
D.
SKY LIGHT
LIFE
BOAT
28
28
28
•
28 28
28
2 B
28
28
28
2
SAL 0
O N
28
I
I
H
|ENGINEERS
28
FUNNEL
28
WORKSHOP
PASSENGER S
28
28
28
28
28
O
28
28
2.11
FIREMEN
28
G
PRISON
28
2B
28
CLASE
FUNNEL
KGALLEY
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SMOKING
ROOM
О
SALOON
ENTRANCE
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B
28
B
1001
MAIN DECK PLAN.
IT SALOON
GENTS
OF
-FUNNEL
C28
B
28
患
​bood
28
28
SAL O
SALOON
PANTRY
FOUR DOUBLE-ENDED BOILERS.
PASSENGER ACCOMMODATION.
Length of EACH BOILER,
DIAMETER
17 FT. 3 IN.
FIRST CLASS,
120
"
15 FT. 6 IN.
NUMBER OF FURNACES TO EACH Boiler,
STEAM PRESSURE,
6.
Second Class,
THIRD CLASS,
140
300
75 LBS.

MUSIC
S ALOON
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HATCH
WINCH
WINCH
SKY
SKY
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28
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26
28
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28
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28
28
28
28
28
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2828
LONGITUDINAL SECTION AND DECK PLANS OF THE SCREW STEAM-SHIP "ORIENT.”
BUILT AND ENGINED BY MESSRS. JOHN ELDER & CO., GLASGOW, FOR THE ORIENT LINE OF ROYAL MAIL STEAMERS TO AUSTRALIA.
HATCH-
B
2 B
28
| ST SALOON
00
STEAM
HATCH
WINDLASS
ood o
ORIENT

010

2B
28
28
28
213
28
28 28
25 28
HATCH-
28 28
28 28
CREWS
28 28
28 28
SPACE
PASSENGERS
28
28
28
28
28
28
28
28
2828
28
2 B
28
28
28
28
2B
HOPPER DREDGER.
1000
H
T
Q
LONGITUDINAL SECTION.

G
B
H
II
H
E
E
The Vessel steams to place of working and is moored by the Steam Winches A A at bow and stern
to buoys, the Bucket Ladder B is then lowered by steam power, and thereafter Buckets set
in motion by gearing cc. The depth of water at which the Bucket Ladder dredges is
regulated by the Hoisting Shears and Chain Barrel DD, driven by shafting EE from the
Engines. The Buckets discharge the material by the shoot F into the Hopper G. The
dredged material is discharged by the doors of the Hopper being opened by the Lifting
Chains H H. These doors are hinged on to the side of Vessel, and suspended at centre by
the Lifting Chains, which are connected to geared Crab Winches 11.
A
C
OF-O
E
HOPPER
G
DECK PLAN.
B
1:00
E
D
HDDDDDDDDDD
CAPTAIN & ENGINEER
ROOM
CABIN
1 2 3 4 5 6 7 8 9 10
15
20
25
30
35
4,0
45
50 feet.
PATENT COMBINED HOPPER DREDGER,
TO DREDGE 20 FEET DEPTH OF WATER, AND CARRY 200 TONS IN ITS OWN HOPPER.
WELL
D

STORE ROOM
LATTICE GIRDER RAILWAY BRIDGE.
N
R
WITĀT
M
SIDE ELEVATION OF CHANNEL SPAN.

EKORA
HOST:
Span centres of Piers,
•
··446′ 0″.
21 Panels each of,.....
20′ 1″.
END ELEVATION.
¿R
PLAN OF UPPER CHORD,
R
B
Y
C
m
– DHE ME NIE WE WENSE M
Height of truss centres of Chords,
Distance apart centres of Trusses,
Height from low water to base of Rail,.
•
·
Z
D
**30.10.
180.10
446. 0°
• •
42′ 2″.
18′ 0″.
•
.95′ 0″.
K
KIA RIVER BRINGE
IV.
17/2
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PLAN OF LOWER CHORD,
AT A.
AT PIER.
F
F
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G
B Abutment.
cc Piers.
K
1303
日
​K
KK Oak Guards.
L Upper Chord.
DD Cutwaters.
EE Stone Pedestals.
F Floor Beams.
G Stringer.
H Oak Ties.
1 Oak Beams.
M Lower Chord.
NN End Posts.
oo Intermediate Posts.
P Strut.
QQ Ties.
RR Roller Frames.
N
EUZMENEMY !==!
ENTE=NENTEMENTENE
LES'
s Braces.
T Stiffening Archway.
U Strut.
v Swing Rods.
w Trestles.
x Diagonal Rods.
Y Pratt Deck Truss.
z Double Intersection Pratt through Truss.

Y
Y
K
X
W
C
D
AD
D
260: 0°
230. 0°
230. O'
dron, Kaduce 1080, 1o
GENERAL ELEVATION.
RAILWAY BRIDGE OVER THE RIVER OHIO, AT BEAVER, PENNSYLVANIA, U.S.A.
LENGTH 1376 FEET, WITH 1080 FEET OF VIADUCT APPROACH.

STEAM CRANE.
A
The HEAD OF JIB A is 60 feet in height from the coping of the pedestal.
The FULCRUM is a Ring of 60 rollers running on a cast-iron and steel Roller Race.
The HOISTING ENGINES are a pair of Vertical Direct-acting Engines with
cylinders 10" diameter and 16″ stroke.
Turning round the Crane is effected by a pair of smaller independent
Horizontal Engines. This Crane will deposit its load a clear dis-
tance of 40 feet from the face of the quay wall.
D
D
A A Jibs.
B Trussing between Jibs.
cc Fulcrum and Rollers.
DD Back Stays.
E Wrought-iron Framing.
F Engine and Boiler House.
GG Hoisting Chains.
H Pedestal.
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SEVENTY-TON STEAM
STEAM CRANE, VICTORIA BASIN, DUNDEE.
CONSTRUCTED BY MESSRS. JAMES TAYLOR AND CO., BIRKENHEAD.
STEAM FIRE FIRE
ENGINE.

K
U
Z
N'
Y
N'
M
TO
X
Y
Y
N
L
M
M
FRONT VIEW.
Z
LITERAL REFERENCES.
A Boiler.
BB Tubes.
B'B' Outer ring of Tubes, forming Water
Casing.
c Fire Bars.
c'c' Lining at the bottom of the Fire Box.
D Chimney.
EE Casing.
E' Fire Door.
F Hollow Baffle Piece forming Blast Pipe.
G Exhaust Steam Pipe.
H Blast Nozzle.
I Steam Cylinder.
I' Crosshead for Piston and Pump Rods.
K Pump.
K' Pump Bucket.
L Suction Pipe.
MM Discharge Pipes.
N Air Vessel for Suction Pipe.
N' Air Vessel for Discharge Pipes.
o Twisted Rod for working the Slide
Valve.
o' Starting Gear.
P Whistle.
Q Safety Valve.
R Bourdon Gauge.
s Gauge Glass.
T Foot Plate and Coal Bunkers.
UU Wheels.
u'u' Wheel Axles.
vv Framing.
v'v' Springs.
U
w Seat for Firemen.
x Seat for Driver.
y Foot Board.
zz Lamps.
I
V
D
E
G
A
E
B
SECTION THROUGH PUMP, CYLINDER, AND BOILER.
II
Β'
C
B
Y
X
E'
Y
N
N
Z
U
V'
U
U
W
PLAN.
ELEVATION.
400
V
V'
U
U
D
P
Q
R
U
S
FRONT VIEW, PLAN, ELEVATION, AND SECTION THROUGH PUMP, CYLINDER, AND BOILER, OF A SINGLE-CYLINDER STEAM FIRE ENGINE.
CONSTRUCTED BY MESSRS. MERRYWEATHER AND SONS, LONDON.
T
સ
T
MODERN STEAM PRACTICE
AND ENGINEERING.
COAL AND COAL-MINING.
COAL is the primary source of our commerce and manufactures,
by enabling steam-power and machinery to be produced at the
most economical rate. The economical importance of the coal
deposits in England and Scotland is much enhanced by the rich
beds of iron ore found in their associated shales, as well as in the
contiguity of the carboniferous limestone which is required to assist
in reducing the ore to a metallic state, not to speak of the lesser
advantage of the proximity of the fire-clay, which furnishes the
only material for building blast-furnaces capable of resisting the
heat of the smelting process. The varieties of coal usually met
with are anthracite, caking-coal, cherry-coal, splint-coal, and
cannel-coal.
For manufacturing purposes coals are generally considered to
consist of two parts-a volatile or bituminous portion, and a sub-
stance comparatively fixed, and usually known by the name of coke.
This latter form of coal is extensively used in locomotive engines
on railways, in consequence of its yielding no smoke, the volatile
matter, or that which forms the smoke of coal, being removed by
ignition. As the bituminous or volatile part of coal yields the gas
used for lighting, it has been found that the heating power of the
coal resides in the coke, and no heat is lost by first extracting the
gas from coal by the usual methods of burning, or rather distilling
coal.
Coal is deposited in beds more or less horizontal, although some-
times by movements of the earth's crust their position has become
much inclined. The great coal-field of Britain, which is composed
of numerous subordinate coal-fields, crosses the island in a diagonal
direction, the south boundary line extending from near the mouth.
of the river Humber, upon the east coast of England, to the south
1
2
MODERN STEAM PRACTICE.
part of the Bristol Channel on the west coast; and the north boun-
dary line extending from the south side of the river Tay in Scot-
land, westward by the south side of the Ochil Hills, to near
Dumbarton upon the river Clyde; within these boundary lines
North and South Wales are included. This area is about 260 miles
in length, and on an average about 150 miles in breadth. Coal
also occurs in other formations of later geological age; but none of
these later deposits equal in economical importance the rich stores
of the carboniferous system in our island. Beds of coal are found
in most European countries, as also in China, India, Australia,
Japan, and Borneo; but the coal-fields of the United States of
America are by far the most extensive and richest in the world.
Boring in search of coal is an important branch of mining. In
ordinary practice the boring plant consists of shearlegs, windlass,
brake, brace-head, bore-rods, cutting tools, &c. Steam - engines
specially adapted for boring have also been devised. A very simple
method with hollow rods combined with a force-pump was intro-
duced by M. Fauvelle in 1846.
(C
The "troubles" met with in working coal are various:-for
example, a "want" or "nip" is, as its name suggests, a part of the
field where no coal exists, or only in a very thin streak; if this
streak is followed, however, the coal seam will again be found.
"Dykes" are generally of whin, projecting from below. It rarely
happens that the coal is either elevated or depressed by this
"trouble," but it is much burned and rendered useless for some
yards on either side. A "step" or "fault" is a dislocation, some-
times of considerable magnitude, by which the strata are elevated
or depressed many fathoms. A "hitch" is of the same nature as
a step," but on a smaller scale. A whin bed is perhaps the worst
kind of "trouble" to be met with, as, when found near to and
parallel with a coal-seam, it renders the entire bed useless. When
a miner meets with a step" or a "hitch" he at once knows
whether it is an "up throw" or a "down throw." If a "hitch" lies
off at the top, by following the rise upwards he will find the coal;
if off at the bottom, he must follow the dip downwards. Although
it is both annoying and expensive to meet with these "troubles,"
they often serve useful purposes: "steps," for instance, sometimes
elevate the coal from a depth that would be difficult to reach by
ordinary means to a depth of comparatively easy working. Again,
when a coal-seam is nearly cropping out, a "step" is met with
((
COAL AND COAL-MINING.
3
that throws it down, in this way extending the field. Again, whin
dykes serve the purpose of dams, and prevent water passing from
one
waste" or worked-out space to another.
It is also of importance to fix on the best position and form for
the pits. Where much water may be expected, the best form for
the pit-shaft is circular, so that the water met with in sinking may
be kept back by tubbing; that is, lining the shaft with suitable
material, such as stone, timber, or cast-iron, the latter being pre-
ferred. When the pressure of water is great, sometimes the tub-
bing is formed of half rings, so as to fit the shaft; but where pumps
and brattices interfere, segments of cast-iron are used, about 4 feet
in length and 2 feet in height, and from 3% of an inch to I inch in
thickness. The segments are made to form a smooth surface in
the shaft, and they are fitted to each other by means of flanges,
3 to 4 inches at each end, and the spaces between the segments
are filled up with thin deal. Stone tubbing is merely common
walling, with the foundation made tight by means of grooves cut
in the stone, the joints and backing being filed up with cement,
which, if carefully executed, will answer for light purposes; but the
success of this method of tubbing is of too precarious a nature to
meet with general application for important works, and wood or
iron is preferred. It sometimes happens in sinking pits that all the
wells and springs in the neighbourhood are drained off, but this evil
may be prevented by tubbing the shaft.
Some pits are sunk at great expense, owing to the nature of the
strata which have to be passed through, and other difficulties, as,
for example, a heavy flow of water. Such instances occur in the
north of England, as at Pemberton's Pit, Monkwearmouth, near
Sunderland, and a pit at Seaham near Durham, which is 300
fathoms deep and cost the enormous sum of £100,000. Before the
steam-engine was introduced, the coal-pits capable of drainage with
hydraulic machinery or water-engines were comparatively few in
number; and when drained by wind-mills, as was sometimes the
case, the pits were drowned in calm weather. The driving of day
levels was thus a primary object with the early miner; and this
system of draining is the cheapest where circumstances allow of its
adoption. The day levels were often of sufficient dimensions to
admit of roads, and even in some cases of canals, being formed in
them, so that machinery was not required. In modern times, how-
ever, the water is pumped from great depths by steam power, the
4
MODERN STEAM PRACTICE.
single-acting Cornish pumping engine, having a beam with the
steam cylinder at one end and plunger or force pumps at the other,
being extensively used. Sometimes lift or bucket pumps are
introduced, while in other cases both plunger and lift are combined
in a single barrel. Some of these engines work direct, the pump
rods being attached at once to the piston-rod over the pit.
The deleterious air met with in mines is of two kinds, the one
being heavier and the other lighter than atmospheric air;—the
natural consequence of which is that the heavier gas rests in the
lower parts of the mine, while the lighter ascends to the higher
parts. The heavier is carbonic acid gas, known to the miners by
the names of "choke-damp," "black-damp," and "stythe;" the
lighter gas is carburetted hydrogen, commonly called "fire-damp,”
or inflammable gas. Where the former gas has been allowed to
accumulate there is great difficulty in getting it expelled. In coal
mines it is seldom present except as "after-damp," and is the
result of a preceding explosion. No light will burn in this gas.
We have seen a fire-lamp, with about 3 cwt. of coal in full blaze,
burning in a pit where choke-damp filled the bottom, as completely
extinguished as if it had been plunged in water. At times, though
seldom, the coal has been known to catch fire in mines, and burn
for years; in such cases carbonic acid gas has been successfully
applied in extinguishing these fires.
Carburetted hydrogen or "fire-damp," the lighter gas, is not
explosive until mixed with atmospheric air. According to experi-
ment, the mixture most explosive is I of gas to 6 of atmospheric
air; when it is 1 to 14 a candle burns in it, but with a flame much
elongated. Many of the fearful explosions and attendant loss
of life occasioned by this gas arise from carelessness. Some
obstruction in the air course is allowed to take place, a door has
been left open all night, or a miner enters his room with a safety-
lamp in his hand, but has neglected to remove the open lamp from
his cap; even some of the miners are so fool-hardy as to light their
tobacco-pipes by drawing the flame through the wire gauze, thus
igniting the gas. We need not impress upon all workmen the great
danger arising from such carelessness.
The electric light is being experimented with at present as an
illuminating medium for coal workings. The great difficulty in
fiery mines being the risk of explosion arising from lights, it
becomes an important matter to devise methods to meet this danger.
COAL AND COAL-MINING.
5
The Davy lamp does not emit a strong light; hence if it can be
proved that the electric light will not set fire to the inflammable
gases of the mines in the event of accidental breakage of the
protecting glass globes, its intense light should prove very valuable
to the miner.
It has been found by experiment that the presence of coal
dust in the workings contributes much to the risk of explosions;
and it seems certain that if 3 per cent. of gas exists in the air
of a mine which is thoroughly mixed with coal dust, an explosive
mixture is formed. Mines should have at least two shafts, one
of which serves to admit the pure air, while the foul gases escape
by the other. The ascent of these gases is facilitated by creating
a draught by means of a furnace at the bottom of one of the shafts
or by fans driven at a high speed placed at top. This shaft
is called the upcast shaft; the downcast shaft, which may be within
a few yards of the other, allows the fresh air to pass down to the
workings, to the faces of which it is directed by partitions of wood
or canvas called "brattices." The air in its circuit below will
travel several miles.
The coal lies in parallel layers, between which the gas exists in
a highly compressed state. In order to detach these layers with
the least possible danger, it is usual to cut through them endways,
by which means the gas is allowed to make its escape at once from
a considerable portion of the coal. From observation of some
mines it is seen that discharge of fire-damp, though governed by
atmospheric pressure, takes place before being indicated by the
barometer, so that, as an indicator, that instrument cannot be relied
on. As before said, the explosion of "fire-damp" in a mine results
in an accumulation of the dangerous "after-damp,"¹ and more lives
are lost by it than by the explosion itself. It has the appearance
of a dense misty vapour, and resists the application of ventilation
in an extraordinary manner. It benumbs the faculties and deprives
the miner of all presence of mind, so that, instead of rushing at
once to the pit bottom, if he has escaped the fire, he gets bewild-
ered, and a deadly lethargy comes over him, ending in sleep from
which he never awakes. It is rare to find choke-damp and fire-
damp in the same workings, or if they do occur it is only in small
quantities.
1 ¹ A mixture of carbonic acid and other products of the combustion of the carburetted
hydrogen.
6
MODERN STEAM PRACTICE.
The only effectual means of preventing accidents from these
gases is a complete system of ventilation by air-courses through
the mine. This ventilation is maintained either by the natural heat
of the mine; by mechanical appliances, as pumps, fans, or pneu-
matic screws—either forcing air into the downcast shaft or exhaust-
ing it from the upcast shaft, by water falling constantly down the
downcast, or by furnaces placed at the bottom of the upcast. For-
merly furnace ventilation was considered to be the most efficient
and reliable mode of ventilating very deep pits. The distance of
the furnace from the bottom of the upcast shaft is a point of impor-
tance, 30 to 40 yards being a common distance.
The fans used for ventilation may be divided into two kinds,

C
A
B
A
A
Fig. 1.-Side Elevation of Guibal Fan.
A A, Rotating Fan. B, Discharge Orifice. c, Outlet.
viz. pump and centrifugal. In the first class are the Struvé, Nixon,
Lemielle, and Roots; and in the second class the Guibal, Rammell,
Waddle, and Schielé. Mechanical ventilators of the fan descrip-
tion appear in some cases to effect a saving of about 50 per cent.
COAL AND COAL-MINING.
7
over the furnace system, and the useful effect of a good fan seems
to be from 40 to 60 per cent. of the power employed. The quan-
tity of air discharged varies with the size of the fan and the speed
of rotation. In some of the centrifugal fans of about 16 feet
diameter, the quantity of air in cubic feet per minute passed
amounts to from 40,000 to 50,000, and in larger fans of 30 to 50
feet diameter, 100,000 to 200,000 cubic feet per minute may be
discharged. In the Schielé fan the speed is very high, 150 to 300
revolutions per minute, the diameter being smaller than some of
the other forms, such as the Guibal, which is generally of a larger
diameter with a less velocity of rotation, say about 90 revolutions
per minute. An engraving of the Guibal fan, which is now largely
used, is shown in Fig. 1.
As a general rule no mine should have a ventilating power of
less than 100 cubic feet per minute for each man and boy employed
in the underground passages, and in mines making large quantities
of fire-damp a ventilation equal to from 200 to 600 cubic feet per
minute per man should be attained.
The common methods of working coal in this country are "long-
wall" and "stall and pillars," with a modification of the latter called
"rances." By the "long-wall" system all the coal is excavated,
and it is the most profitable way of working. Before starting any
coal "long-wall," however, there are several circumstances to be
considered, such as the nature of the roof, the property that might
be injured by the subsidence of the superincumbent strata, and so
on. In the “stall and pillar" system there is a great sacrifice of
coal, generally about one-third, but often nearly one-half; this plan,
therefore, should never be adopted if the coal can be worked "long-
wall." Pillars are often left large or worked in "rances," with the
intention of being afterwards removed; but this plan does not
always succeed. Large as the pillars may be, they often sink into
the pavement if it is soft, and cause a "creep," which shatters the
coal, besides forcing the soft pavement up to the roof in the roads and
rooms or stalls, and the contemplated removal of the pillars is thus
frustrated. The edge seams of coal are worked "long-wall" in some
cases, and "stall and pillar" in others. Instead of the pits being
sunk straight down, inclined shafts are driven through the bed of
coal, with rooms branching off from either side of the incline, and
to work these the men stand on the coal as a floor, having the coal
also as the roof. In the shaft, instead of a cage and slides, there is
8
MODERN STEAM PRACTICE.
a tramway, with trucks capable of holding two hutches or small
waggons in each, the tramways being laid double in order to
balance the engine, one truck ascending and the other descending,
as in ordinary vertical shafts. These trucks have likewise boxes
fitted for drawing the water, the mechanism for doing so being
self-acting.
The method now universally adopted for bringing the coal to the
surface is by a steam-engine having a drum on which the wire ropes
are wound, the drum being sheathed with wood; the cages or frames
for holding the hutches or small waggons being attached to the
other end of the wire ropes, which are so arranged that one cage is
descending with an empty hutch, and the other ascending with a
hutch full of coal, the men descending and ascending in like manner.
The shaft has a central division all the way down, formed of timber,
to which are attached balks of the same material; balks are also
fixed to each side of the shaft, to form a guide for the cages, the
cage or iron frame having guiding pieces fitted to it. Many ingeni-
ous devices have been adopted to disconnect the cage from the rope
in case of over-winding, or to prevent the cage from being dashed
to the bottom should the rope snap. All these plans consist of
mechanical contrivances, such as wedges, clips, eccentrics, serrated
and arranged with springs and levers, so as instantly to grip the
guides in the pit, and thus sustain the cage until the defects are
made good. On the engine shaft is fitted a worm wheel and pinion,
with an index, so that the engine tenter-who should always be on
the look out, as this index is intended to point out the approach of
the cage either way-knows when to stop the engine at the top or
All modern engines are fitted with the link motion for
actuating the slide valve; thus the man in charge of the engine
can stop and reverse instantly, and so prevent accidents from over-
winding.
A variety of machines have been introduced for cutting and
breaking down the coal, saving the practical miner much hard
labour. These consist chiefly in an arrangement of a series of
cutters, which are made to revolve by the action of compressed air
or steam; and they answer in certain localities where the seams of
coal are of great thickness, but in many cases the miner has to lie
on his side and use the pick in that position. Machines do not
answer well in thin seams, where, after the coal is broken down, the
men have to push it out of their rooms with their feet.
COAL AND COAL-MINING.
9
The utilization of coal for raising steam has now been adopted
for many years, and the steam-engine may be called a machine.
whereby the power stored in the coal may be rendered available
for the performing of mechanical work.
The history of the steam-engine, like that of other important
inventions, shows a slow and gradual development from compara-
tively simple and rude appliances to the highly finished and complex
machine of the present day.
The earliest notice which we have of the use of steam is in the
writings of Hero of Alexandria (B.C. 120), where a rotatory steam-
engine is mentioned. In 1663 the Marquis of Worcester devised a
steam-engine for pumping water, and in 1697 Savery applied steam
to pump water out of mines. Papin in 1690 improved the earlier
rude machine, and introduced the cylinder and piston. Newcomen
in 1705 introduced the separate boiler, and through the alternate
pressure and condensation of the steam produced the atmospheric
pumping engine.
To James Watt, however, we must look as the inventor who
brought the steam-engine to be a really serviceable machine for
commercial purposes, and this mainly through his invention of the
separate condenser, whereby the steam, instead of being condensed
in the cylinder, as in Newcomen's engine, was conveyed to a
separate vessel, where, by means of a jet of water, it became con-
densed and afterwards pumped out to be used as feed-water to the
boiler.
Attempts were made from time to time to use the steam-engine
as a propelling power for boats, and both in Europe and in America
various experiments were made. To Fulton in America and Bell
in this country, however, the credit of successfully introducing
passenger steamers must be given.
The application of steam to locomotives was attempted by vari-
ous engineers, but the successful introduction of the railway loco-
motive is mainly due to George Stephenson; the main elements of
success being the adoption of the tubular boiler and forced blast.
Steam has also been applied to road locomotive traction engines
and agricultural machinery, and, of course, in the many forms of
land engines it is still supreme.
BOILERS FOR STATIONARY ENGINES.
DISTINCTIVE FORMS OF BOILERS.
The common cylindrical boiler with hemispherical ends is exten-
sively used for colliery engines and other places where space is no
object, and the consumption of fuel but little thought of. For such
purposes it is the simplest, and, as no stays are required, the
strongest of its kind. It rests on a structure of brickwork, having
the furnace underneath, with a return flue all round; the parts ex-
posed to the action of the flame are lined with fire-brick. As there
are usually no internal flues, it is obvious that it is a very safe
boiler, having always a good body of water over the furnace, or
fire-grate; but still it is not free from the rapid corrosion that sets in
with all boilers resting on a substructure of brickwork. Sometimes
boilers of this form have the front end quite flat, for the conveni-
ence of attaching the water gauge glass, steam-pressure gauge, &c.


E
A
C
B
D
Fig. 2.-Cornish Boiler with Single Furnace. Longitudinal and Transverse Sections.
A, Shell. B, Furnace. c, Fire-brick bridge. D, Flue. E, Steam dome.
The Cornish boiler differs materially from the plain cylindrical form:
both the ends are quite flat, with one internal flue running through
and through, and having the fire-grate at one end; or with one in-
ternal flue, and having the furnace underneath the boiler, with return
flues in the usual manner. Another form has two internal furnaces,
meeting in a combustion chamber. This plan of construction is
well suited for the prevention of smoke; but to attain this end the
furnaces should be fired alternately, so that one fire is quite bright,
while the other one is green, or in the act of firing. To assist com-
bustion, small tubes are introduced from the front end, passing
through the water space into the combustion chamber. Thus a
BOILERS FOR STATIONARY ENGINES.
II
current of heated air mixes with the flame and heated gases, and
prevents smoke to a great extent. The simplicity of this arrange-
ment cannot be excelled, as careful firing of itself will, in a great
measure, prevent smoke, while the current of hot air, mixing with
the heated gases in the furnace, largely contributes to the same
result. The top parts of the ends are stayed with gusset pieces, con-
nected to the top and ends of the boiler, and the combustion chamber
is strengthened at the back of the furnace with one or more conical

A
E
B
D D
D
E
B
F

Fig. 3.-Boiler with Double Furnaces.
A, Shell. B B, Furnaces. c, Combustion chamber.
Horizontal and Transverse Sections.
DD, Stay tubes. EE, Flues. F, Steam dome.
tubes, with the water freely passing through them. As large flues
are weak, sometimes they are strengthened with conical tubes at
intervals; the back flue, in some cases, is divided into two smaller
ones, and the conical tubes omitted, thus leaving the flues quite
clear, so that they can be easily cleaned out. Another kind of

E
1)
A
B
B
F

Fig. 4.—Combined Cornish and Multitubular Boiler. Horizontal and Transverse Sections.
A, Shell. BB, Furnaces. c, Combustion chamber. D, Small tubes. E, Stay tube. F, Steam dome.
cylindrical boiler has a number of small tubes set at the back of
the combustion chamber, thus combining, in some respects, the
Cornish with the multitubular arrangement. For low pressure
steam, and where space is an object, and when deposits from
the water are rapidly formed over the heating surface, a self-con-
tained boiler, designed by the author, has done good service. It
is fitted with one round furnace, carrying the flame and heated
gases to the back, returning to the front end through large tubes,
8 inches in diameter, and then repassing to the back through other
12
MODERN STEAM PRACTICE.
tubes of the same diameter; then down at the back, and along the
sides and bottom, through suitable flues of brickwork, so that,
A, Shell.
B, Furnace.
DD, Tubes.
E, Smoke-box.
c, Combustion chamber. F, Flue.
E
A
C
F
B
internally and externally, a large
amount of heating surface is ob-
tained, and this great desideratum
is secured that all the tubes are
easily got at for repairs and scaling
off the deposits.
Thus we have noticed arrange-
ments partly self-contained, but
having external flues of brickwork,
such as are in general use. Next
comes that class which is wholly
self-contained, the heated gases,
after doing duty in the boiler, sim-
ply going up the chimney. There
are several arrangements having all the same object in view,
namely, to economize space. By one of them an ordinary round
shell has a square furnace fitted; the flame, after doing its best duty
in the fire-box, passes through one or two large flues, crossed with
a series of conical tube stays, and the flame interlacing, as it were,

Fig. 5.-Return Tubular Boiler. Longi-
tudinal Section.


E
A
Во
C
תי
F
B
Fig. 6. Self-contained Flue Boiler. Longitudinal and Transverse Sections.
A, Shell. B, Fire-box. cc, Flues. D, Stay tubes. E, Steam dome. F, Fire-door.
amongst them, makes a very effective arrangement, and in cases where
the water, from its impure state, rapidly forms deposit, all the parts.
can easily be reached. Instead of the large flues, small tubes are
sometimes arranged, as in the locomotive boiler, so that the useful
caloric is extracted by honeycombing the water, as it were, with
hundreds of square feet of heated surface; but when very small tubes
are used, they should be of a different material from the boiler—
brass, or composition tubes, are to be preferred—thus the incrusta-
tion is in a great measure prevented. Sometimes the fire-box is
made cylindrical, having a hemispherical outside dome; by this
D
BOILERS FOR STATIONARY ENGINES.
A
13
plan very few stays are required; the tube-plate, however, must be
made flat, with the back of the outside fire-box to correspond, or as it
were part of the cylindri-
cal portion of the fire-box,
cut away in the plan, that
part having screwed stays
in the usual manner. This
arrangement has now be-
come obsolete.

Another form exten-
D
Fig. 7.-Self-contained Tubular Boiler.
A, Shell. B, Fire-box. c, Tubes. D, Smoke-box.
E, Fire-door.
B
E
ca
GMPPY
sively used for general purposes is the vertical type. Such boilers
are made entirely cylindrical; some are constructed with an internal
barrel, with the smoke-pipe passing through the steam space; while

A, Shell.
c, Smoke-pipe.
B, Fire-box. D, Fire-door.
A
C
A
D
Fig. 9.
A, Shell.
B, Fire-box.
c, Tubes.
D, Smoke-pipe.
E, Fire-door.

Fig. 10.
A, Shell.
B, Fire-box.
cc, Flues.
D, Fire-door.
CURIAELIUMIS
B
D
A

B
Pq
E
B
ANTHONCHHAR HA
SUURIMMISI
C
Fig. 8.
Vertical Dome Boiler.
Fig. 9.
Vertical Tubular Boiler.
Fig. 10.
Vertical Return Boiler.
some steam generators of this kind are made very lofty, fitted with
an internal cone fire-box, and arranged in communication with the
waste heat from puddling and other furnaces, &c., and others for
general purposes have small tubes placed vertically, arranged with
the smoke-box underneath the water, and the smoke-pipe passing
through the steam space. Other arrangements have, the tubes
passing to the top of the boiler, with a dry uptake; thus the tubes
can easily be inspected without disturbing the steam-tight portions
of the boiler; and the tubes are easily cleaned by simply taking off
the dry uptake, or lower portion of the funnel. The boiler-tubes
14
MODERN STEAM PRACTICE.
of a steam carriage for common roads having become foul with
soot, thus impeding the draught, gunpowder was wrapped up tightly
in a piece of paper and thrown on the fire, and the fire-box door
immediately shut; a slight explosion took place, sending a cloud of
soot up the chimney, effectually clearing the tubes without stopping
the machine. Of course, it would be somewhat dangerous to carry
an explosive mixture about for such a purpose; but, in most cases,
this means of clearing the tubes can be cheaply and most effectu-
ally carried out, and there is no danger whatever, provided too
much gunpowder is not used at once. All vertical self-contained
boilers should have air tubes 34 inch in diameter, and spaced about
6 inches apart, all round the fire-box, dipping downwards, so that
a current of air may mix with the flame and heated gases at about
the level of the top of the fuel, thus tending to the prevention of
smoke; these tubes are screwed into the outside shell and the
inside fire-box, and then rivetted over.
There is one objection common to all vertical boilers, namely, that
a great portion of the heat passes directly up the chimney without
doing duty; to obviate this defect the flame and heated gases are
directed downwards with suitable flues; this plan must have separate
flues of fire-brick, with a chimney, and is not so compact an arrange-
ment as the multitubular one. The feed-water pipe passes through
the bottom flues, thus heating the water in its passage to the boiler,
and all the flues are easily reached for scaling and cleaning out.
A
F
ID
The pot boiler derives its name from the
peculiar pot-like vessel, fitted to, and hanging
from the top of the fire-box; this spherical
generator is introduced so that the lower part,
made of copper, receives the full benefit of the
flame; the annular space between the pot and
the fire-box is made narrow, thus the flame and
heated gases impinge against the sides of the
fire-box, and then pass through the small tubes
into the chimney. The ebullition of the water in
the pot is very violent, ejecting the sediment and
preventing incrustation; the deposit finds its way
to the bottom of the boiler, and is cleaned out by
Fig. 11.—Pot Boiler. A, Shell. suitable sludge doors. The dry uptake can be
E, Fire-door. F,Smoke-pipe. easily removed, and the inside of the boiler in-
spected through the man-hole, placed exactly over the pot, in the

B
E
B, Fire-box. c,Pot. D,Tubes.
BOILERS FOR STATIONARY ENGINES.
15
centre of the boiler, there being no tubes at the centre, but merely
all round the opening in the top of the pot, which is bolted to the
tube-plate by means of projecting flanges on the pot and tube-
plate.
E
A
In some cases, such as in the Fire-engine, it is a desideratum
to have a rapid steam-producing boiler; a good example is simply
an ordinary vertical boiler, having the tubes suspended inside of
the fire-box, arranged with an internal tube in each, loosely sup-
ported from the tube-plate, these small inside tubes leaving annular
spaces between them and the larger tubes, so that only a thin film
of water is exposed to the heating surface. By this means steam is
raised rapidly; but it must be borne in mind that, as the evapora-
tion of the water is very great, care must be
taken that a sufficient quantity of water is kept
up in the boiler, which would otherwise soon
boil dry. The circulation is very rapid in the
tubes. The bottoms of the tubes are hermeti-
cally sealed; and as the steam is generated,
it ascends, displacing the water in the annular
space between the inner and outer tubes, and
the water from the top circulates down the
inner tubes and fills up the cavity. The smoke-
pipe is connected to the top of the fire-box,
passing through the steam space, and is rivetted
to an angle-iron ring on the top of the boiler;
and there is an open part left in the centre of
the fire-box where there are no tubes, this
opening being blocked up with a lump of fire-
brick suspended by a rod from the top of the
boiler, thus the flame is prevented from going directly up the
chimney, as it impinges against the fire-clay lump, and by this
means it is distributed beneficially amongst the small tubes.

B
F
Fig. 12.-Boiler with Suspended
Annular Tubes.
A, Shell.
B, Fire-box. c, Tubes. D, Fire-
brick lump. E, Smoke-pipe.
F, Fire-door
Instead of a number of annular tubes, one large tube has been suc-
cessfully adopted, the arrangement consisting of an internal fire-box,
having an annular¹ water space all round. On the outside of this
water space there is an annular flue, and the whole is contained in
an ordinary vertical boiler, having a hemispherical top; the flame
and the gases, after doing duty in the fire-box, find their way
1
¹ The space between a small inner and large outer tube is called annular.
16
MODERN STEAM PRACTICE.
A
through an opening into the annular flue, and then escape all round
into a flue of brickwork; thus a large heating surface is obtained.
As in the pot boiler, there is great
ebullition in the annular space around
the inside fire-box, the steam escaping
into the boiler proper through a tube
at the top, the circulation of the water
being effected by a series of small
tubes, connecting the inside and the
outside water spaces at the bottom of
the boiler.

F
E
B
G
Fig. 13. Annular Boiler. A, Shell. B, Fire-
flue. E, Flue. F, Fire-door. G, Ash-pit.
What are termed "water-tube"
boilers show examples consisting
merely of large tubes, so connected
as to form a series of boilers, the whole
being encased in brickwork. This
box. c, Annular water space. D, Annular species of steam generator is capable
of sustaining great pressure, the whole
of the steam pipes and the connections being tested to about 500 lbs.
per square inch; and as they are constructed so that all the joints
are protected from the action of the flame, they ought to be very
durable. Where space is no object they are well suited for small
powers, but for large power it is doubtful if they are so well adapted
as the ordinary Cornish arrangements, fitted with conical water
tubes in the flues.
One arrangement of the water-tube boiler consists of a series of
tubes 4 feet 6 inches long and 7 inches in diameter, closed at the upper
ends, having plates ½ inch in thickness welded in, and round
the bottom ends heavy cast-iron rings with lugs are fixed. The
ends of the tubes are roughened, and the rings are cast on, thus the
contraction of the cast-iron, as well as a partial uniting of the two
metals, render this mode of fastening on the rings a very secure one;
the tubes are arranged in transverse rows in an oven, between the
furnace and the chimney. The lower ends of the tubes for each row
are united to a pipe 10 inches in diameter, and of suitable thickness,
which is strengthened by diaphragm plates cast in, and perforated
with small holes. On this pipe short branch pieces are cast, which
are turned and recessed, for the reception of the ends of the other
tubes, to which they are strongly united by means of bolts and gun-
metal nuts, recessed into the lugs, the rings on the tubes having
BOILERS FOR STATIONARY ENGINES.
17
corresponding lugs. The joint is made with a composition ring, of
lead and tin, dropped into the recess, and then the screws are
tightened; this joint is capable of sustaining as great a pressure as
the tubes, and can be made and re-made at any time without injury.

H
D
B
A
G
F
C
E
Fig. 14.-Water-tube Boiler. A, Furnace. B, Tubes. c, Flue. D, Division plate. E, Damper.
F, Steam receiver. G, Stop valve. H, Safety valve.
The upper ends of the tubes have short pieces of wrought-iron
welded gas pipe, tapped into the end plates, for taking away the
steam to the main pipe, which is placed horizontally. Upon the
main steam pipe smaller pipes are fitted, and connected to the small
gas pipes from each generator; thus the steam flows along them into
the large pipe, to which is fixed the safety-valve and the pipe to
the steam cylinder. All the parts are so arranged that they can.
expand freely, without disturbing the joints. The oven has a
division plate strongly ribbed; by this means the flame impinges.
on the bottom halves of the generators, and passing along the top
half goes to the chimney.
Another arrangement of water-tube generators has simply
wrought-iron tubes, with cast-iron ends, secured with long bolts
inside of the tubes, having the feed pipes joining together at the
bottom; similar pipes are situated at the top of the tubes for the
steam, these lead into one main steam pipe, the whole being
encased in suitable brickwork. All the parts in this arrangement
are well protected, only the plain parts of the tubes being exposed
2
18
MODERN STEAM PRACTICE,
to the action of the flame; the bottom joints are embedded in
the brickwork, and each of the tubes exposes an area of 16 feet,

A
14
F
B
E
C
G
VALINMIMINIM
C
E
F
B
WWHI
ІНІМІМАМНИЦИ
Fig. 15.-Water-tube Boiler. A, Furnace. B, Tubes. c, Flue.
DD, Division plates. E, Damper. F, Stop valve. G, Chimney.
G
A, Shell. B, Fire-box. c, Smoke-
pipe.
D, Circulating water
space. E, Conical tubes. F, Fire-
door. G, Sludge cap

こ
​equal to one horse-power. This arrange-
ment is certainly very simple, and is to
be commended, provided the expansion
of the long bolts does not affect the caps.
at the ends, causing steam to blow at the
joints. These water-tube boilers must be
so manufactured that no destructive ex-
pansion may be allowed to take place, and all the joints should be
metal to metal where practicable.
Fig. 16.-Self-contained Water-
tube Boiler.
Water-tube boilers, sometimes called tubulous, may be of various
forms. The water tubes can be arranged in a variety of ways,
so that the furnaces, the tubes, and the shell are self-contained.
Thus to an ordinary vertical boiler an inside fire-box is fitted, as
likewise a pot-shaped vessel connected by circulating pipes with the
shell, as shown by Figs. 15 and 16. A current of water is continually
descending between the fire-box and the outside shell, and finds its
way into the pot through the circulating pipes at the bottom. These
boilers keep free from deposit, owing to the rapid circulation, and
for some purposes are recommended to be arranged with conical or
common tubes.
BOILERS FOR STATIONARY ENGINES.
19
In the Perkins system of boiler a large number of water tubes are
enclosed in a double shell of plate iron, the space being filied with a
non-conducting medium. The tubes are 24 inches inside diameter
and 3% inch thick. About one half of the tubes are used for generat-
ing steam, the other half being used for superheating. The boiler is
supplied with distilled water, and the furnace is placed beneath the
tubes which run vertically above. Tubulous boilers have been tried
at sea in the Propontis and other vessels on Rowan's system, and
again recently in the steam yacht Anthracite, which lately made
a voyage across the Atlantic and back, carrying a pressure of from
300 to 500 lbs. of steam per square inch. This vessel was fitted
with the Perkins boiler.
ON BOILERS, BY FAIRBAIRN.
We propose under this head to consider the steam-boiler in its
construction, management, security, and economy.
As regards the construction, it is absolutely necessary to study
carefully the shapes which give maximum strength, and require
minimum of material. In boilers this is most important, as any
increase in the thickness of the plate obstructs the transmission
of heat, and exposes them as well as the rivets to injury on the side
exposed to the action of the flame. It has been generally supposed
that the rolling of boiler plates gives to the sheets greater tenacity
in the direction of their length than in that of their breadth. This is,
however, not always the case, as experiments show that the tensile
strain across the fibre of boiler plates is in some samples greater than
their tensile strength when torn asunder in the direction of the fibre.
We consider this may be owing to the way the iron is piled before
putting it through the rolls; more recent experiments plainly show
that the tensile strength of boiler plates is slightly greater in the
direction of the fibre, and from this it would appear that although
it is more convenient to construct circular boilers, with plates rolled
in the direction of the fibre, still we think that boilers diagonally
plated are the strongest.
Next to the tenacity of the plates comes the question of rivet-
ting. On this point we have been widely astray, and it required
some skill, and no inconsiderable attention in conducting the ex-
periments, to convince even some practical men that the rivetted
joints were not stronger than the plate itself. In punching holes
along the edge of a plate, it is obvious that the plates must be
20
MODERN STEAM PRACTICE.
weakened to the extent of the sectional area punched out; and
it is found also that the metal between the holes is deteriorated
by the process of punching.¹ This deteriorating result was clearly
demonstrated by a series of experiments which took place some
years ago, and in which the strength of almost every descrip-
tion of rivetted joints was determined by tearing each directly
asunder. The results obtained from these experiments were con-
clusive as regards the relative strength of rivetted joints and the
solid plates. In two different kinds of joints, double and single
rivetted, the strength was found to be in the ratio of 100 for the solid
plate, 70 was the strength of a double-rivetted joint after allowing
for the adhesion of the surfaces of the plates, and 56 was the strength
of a single-rivetted joint. These proportions of relative strength of
plates and joints may therefore in practice be safely taken as the
standard value in the construction of vessels required to be steam
and water tight, and subjected to pressure varying from 10 lbs. to
100 lbs. on the square inch.
The following is the rule for proportions as given by Professor
Rankine:2___
"Let denote the radius of a thin hollow cylinder, such as the
shell of a high-pressure boiler; t, the thickness of the shell; f, the
tenacity of the material in lbs. per square inch; p, the intensity
of the pressure in lbs. per square inch required to burst the shell.
This ought to be taken at SIX TIMES the effective working pressure,
then p, and the proper proportion of thickness to radius is given
Р
by the formula =
t
r
"}
"The following formula gives approximately the collapsing pressure
p in lbs. on the square inch of a plate iron flue, whose length 1,
diameter d, and thickness t, are all expressed in the same units of
measure: p = 9,672,000"
12
"Tenacity of wrought-iron plates
51,000 lbs. per square inch.
Tenacity of wrought-iron joints, double rivetted = 35,700 lbs. per square inch.
Tenacity of wrought-iron joints, single rivetted = 28,600 lbs. per square inch."
In the construction of boilers exposed to severe internal pressure,
it is desirable to adopt such forms, and so to dispose the material,
as to apply the greatest strength in the direction of the greatest
¹ In the best modern practice, therefore, all rivet holes are drilled where practicable.
2 See Manual of the Steam Engine.
BOILERS FOR STATIONARY ENGINES.
2I
strain.
Professor W. R. Johnson, of the Franklin Institute of
America, whose inquiries into the strength of cylindrical boilers
are of great value, may be quoted as an authority:—
"Ist. To know the force which tends to burst a cylindrical boiler
in the longitudinal direction, or, in other words, to separate the head
from the curved sides, we have only to consider the actual area of
the head, and to multiply the units of surface by the number of
units of force, applied to each superficial unit, this will give the total
divellent. To counteract this, we have, or may be conceived to have,
the tenacity of as many longitudinal bars as there are units in the
circumference of the cylinder. The united strength of these bars
constitutes the total retaining or quiescent force, and at the moment
when rupture is about to take place the divellent and quiescent
forces must obviously be equal.
"2d. To ascertain the amount of force which tends to rupture the
cylinder along the curved side, or rather along the opposite sides, we
may consider the pressure as applied through the whole breadth of the
cylinder upon each lineal unit of diameter. Hence the total amount
of force which would tend to divide the cylinder in halves, by sepa-
rating it along two lines of opposite sides, would be represented by
multiplying the diameter by the force exerted on each unit of surface,
and this product by the length of the cylinder. But even without
regarding the length, we may consider the force requisite to rupture
a single band in the direction now supposed, and of one lineal foot
in breadth, since it obviously makes no difference whether the cylinder
be long or short, in respect to the ease or difficulty of separating the
sides. When the diameter of a boiler is increased, it must be borne
in mind that the area of the ends is also increased, not in the ratio
of the diameter, but in the ratio of the square of the diameter; and
it will be seen, that instead of the force being doubled, as in the case
of the direction of the diameter and circumference, it is quadrupled
upon the ends, or, what is the same thing, a cylinder double the
diameter of another cylinder, has four times the pressure in the
longitudinal direction. The retaining force, or the thickness of metal
of a cylindrical boiler, does not, however, increase in the same ratio.
as the area of the circle, but simply in the ratio of the diameter,
consequently the thickness of the metal will require to be increased
in the same ratio as the diameter is increased. From this it appears
that the tendency to rupture, by blowing out the ends of a cylindri-
cal boiler, will not be greater in this direction than it is in any other
22
MODERN STEAM PRACTICE.
direction; we may therefore safely conclude, since we have seen
that the tendency to rupture increases in both directions in the
ratio of the diameter, that any deviation from that law, as regards
the thickness of the plates, would not increase the strength of the
boiler."
We have been led to the following inquiries from the circumstance
that Mr. Johnson appears to reason on the supposition that there
are no joints in the plates, and that the tenacity of the iron is equal
to 60,000 lbs., rather more than 26 tons, to the square inch. Now the
result of experiment has shown that ordinary boiler plates will not
bear more than 23 tons to the square inch; and as nearly one-third
of the material is punched out for the reception of the rivets, we must
still further reduce the strength, and take 15 tons, or about 34,000 lbs.,
on the square inch, as the tenacity of the boiler plates, or the pres-
sure at which the boiler would burst. By experiment it has been
found that the strength of the single-rivetted joints of boilers is little
more than half the strength of the plate itself; but taking into
consideration the crossing of the joints, 34,000 lbs. may reasonably
be taken as the tenacity of the rivetted plates, or the bursting
pressure of a cylindrical boiler.
It has been stated that the strength of cylindrical boilers, when
taken in the direction of their circumference, is in the ratio of their
diameters, and when taken in the direction of the ends, as the squares
of the diameters; a proposition which it will be difficult to demonstrate
as applicable to every description of boiler of the cylindrical form.
It will be seen, however, that the strain is not exactly the same in
every direction, and that there is actually less upon the material in
the longitudinal direction than there is upon the circumference. For
example, let us take two boilers, one 3 feet in diameter and the other
6 feet in diameter, and suppose each to be subjected to a pressure
of 40 lbs. to the square inch. In this condition, it is evident that
the area, or number of square inches, in the end of the 3 feet boiler
is to that of the area of the 6 feet boiler as I to 4; and, by a common
process of arithmetic, it is found that the edges of the plates forming
the cylindrical part of the 3 feet boiler is subject, at 40 lbs. on the
square inch, to a pressure of 40,714 lbs., or upwards of 18 tons;
whereas the plates of a 6 feet boiler have to sustain a pressure of
162,856 lbs., or 72 tons, which is quadruple the force to which the
boiler only one-half of the diameter is exposed; and the circumfer-
ence being only as 2 to 1, there is necessarily double the strain upon
BOILERS FOR STATIONARY ENGINES.
23
the cylindrical plates of the large boiler. Now this is not the case
with the other parts of the boiler, as the circumference of a cylinder
increases only in the ratio of the diameter, consequently the pressure
instead of being increased in the ratio of the squares of the diameter,
as shown in the ends, is only doubled, the circumference of the
6 feet boiler being twice that of the 3 feet boiler.
Let us, for the sake of illustration, suppose the two cylindrical
boilers such as we have described to be divided into a series of hoops
of I inch width, and taking one of these hoops in the 3 feet boiler, we
shall find it exposed at a pressure of 40 lbs. on the square inch to a
force of 1440 acting on each side of a line drawn through the axis of
a cylinder 36 inches diameter and I inch in depth, and which line forms
the diameter of the circle. Now this force causes a strain tending to
burst the hoops in the 3 feet circle of 720 lbs., and assuming the pres-
sure to be increased until the force becomes equal to the tenacity or
retaining power of the material, it is evident, in this state of the equi-
librium of the two forces, that the preponderance on the side of the
internal pressure would insure fracture; and supposing we take the
plates of which the boiler is composed, of one quarter of an inch thick,
and the ultimate strength at 34,000 lbs. on the square inch, we shall
have 34000
= 472 lbs. per square inch, as the bursting pressure of the
36 × 2
boiler. Again, as the forces in this direction are not as the squares,
but simply as the diameters, it is clear that at 40 lbs. on the square
inch we have in a hoop an inch in depth, or that portion of a cylinder
whose diameter is 6 feet, exactly double the force applied to rend
the iron asunder, as in the 3 feet boiler. Now, assuming the plates
to be quarter of an inch thick, as in the 3 feet boiler, it follows, if
the forces at the same pressure be doubled in the large cylinder, that
the thickness of the plates must also be doubled, in order to sustain
the same pressure with equal security; or, what is the same thing,
the 6 feet boiler must be worked at half the pressure, in order to
secure the same degree of safety as attained in the 3 feet boiler at the
given pressure. From these facts it may be useful to know that
boilers having increased dimensions, should also have increased
strength in the ratio of their diameters; or, in other words, the plates
of a 6 feet boiler should be double the thickness of the plates of a
3 feet boiler, and so on as the diameter increases.
The relative powers of force applied to cylinders of different dia-
meters become more strikingly apparent when we reduce them to
their equivalents of strain per square inch, as applied to the ends
24
MODERN STEAM PRACTICE.
and circumference of the boiler respectively. In the 3 feet boiler,
working at 40 lbs. pressure, we have a force equal to 720 lbs. upon an
inch width of plates, and one quarter of an inch thick, or 720 × 4=
2880 lbs., the force per square inch upon every point of the circum-
ference of the boiler. Let us now compare this with the actual
strength of the rivetted plates themselves, which, taken as before at
34,000 lbs. on the square inch, gives the ratio of the pressure as
applied to the strength of the circumference as 2880 to 34,000,
nearly as 1 to 12, or 472 lbs. per square inch as the ultimate strength
of the rivetted plates.
These deductions appear to be true in every case as regards the
resisting powers of cylindrical boilers to a force radiating in every
direction from its axis towards the circumference; but the same
reasoning is, however, not maintained when applied to the ends, or,
to speak technically, to the angle-iron, and rivetting, when the ends
are attached to the circumference. Now, to prove this, let us take
the 3 feet boiler, where we have 113 inches in the circumference,
and upon this circular line of connection we have, at 40 lbs. to the
square inch, to sustain a pressure of 18 tons, which is equal to a
strain of 360 lbs. acting longitudinally upon every inch of the cir-
cumference. Apply the same force to the 6 feet boiler, with a
circumference or line of connection equal to 226 inches, and we
shall find it exposed to exactly four times the force, or 72 tons;
but in this case it must be borne in mind that the circumference is
doubled, and consequently the strain, instead of being quadrupled,
is only doubled on a force equal to 720 lbs., acting longitudinally
as before upon every square inch of the circumference of the boiler.
From these facts we come to the conclusion that the strength of
cylindrical boilers is in the ratio of their diameters, if taken in the
line of curvature, and as the squares of the diameters as applied
to the ends or their sectional area; and that all descriptions of
cylindrical tubes, to bear the same pressure, must be increased in
strength in the direction of their circumferences, simply as their
diameters, and in the direction of the ends as the squares of the
diameters.
Again, if we refer to the comparative merits of the plates com-
posing cylindrical vessels, subjected to internal pressure, they will
be found in the anomalous condition, that the strength in their
longitudinal direction is twice that of the plates in the curvilinear
direction. This appears by a comparison of the two forces, wherein
BOILERS FOR STATIONARY ENGINES.
25
we have shown that the ends of the 3 feet boiler, at 40 lbs. internal
pressure, sustain 360 lbs. of longitudinal strain upon each inch of a
plate a quarter of an inch thick; whereas the same thickness of plates
have to bear, in the curvilinear direction, a strain of 720 lbs. This
difference of strain is a difficulty not easily overcome; and all that
we can accomplish in this case will be to exercise a sound judgment
in crossing the joints, in the quality of the workmanship, and in the
distribution of the material. For the attainment of these objects,
the following table, which exhibits the proportionate strength of
cylindrical boilers from 3 to 8 feet, may be useful:—
Diameters of
Boilers.
Feet. Inches.
Bursting Pressure equivalent to the ultimate strength
of the Rivetted Joints, as deduced from experiment.
34,000 lbs. to the square inch.
Thickness of the
Plates in decimal
parts of an inch.
6
6
7
33++inio 7 D∞
O
*250
6
*291
4
*333.
4
6
*376
о
6
450 lbs.
*416
*458
*500
6
*541
*583
6
*625
8
о
•666
Boilers of the simple form, and without internal flues, are subjected
only to one species of strain; but those constructed with internal
flues are exposed to the same tensile force which pervades the
simple form; and farther, to the force of compression, which tends
to collapse or crush the material of the internal flues.
From the existing state of our knowledge we must rest satisfied
that the flues of ordinary boilers can be materially strengthened by
the introduction of iron hoops, but we are of opinion they should
never be introduced where deposits rapidly form, such as in marine
boilers, &c.; for it must be borne in mind that there are two thick-
nesses of material at the parts hooped, and the incrustation that
forms proves highly detrimental to the furnaces. In many cases
where deposits have formed at the hoops the furnace-plates have
bulged out very much.
Fairbairn gives a table of internal flues fitted with T-iron or angle-
iron hoops. The length of the flues must be measured between the
rigid supports; in an unsupported flue, as ordinarily constructed,
:
26
MODERN STEAM PRACTICE.
the length is measured between the end plates of the boiler. In
the flues as proposed, between the T-iron ribs, the dimensions given
are for a collapsing pressure of 450 lbs. per square inch; the safe
working pressure should be 75 lbs. per square inch.

THICKNESS of Plates.
Diameter of
Flues in inches.
10 Feet Long. 20 Feet Long.
30 Feet Long.
12
*291
$399
*480
18
*350
*480
*578
24
*399
*548
*659
30
450 lbs.
442
•607
36
*730
*480
•659
*794
42
*516
*707
48
.851
*548
*752
*905
The above are founded on the supposition that the 20-feet and
30-feet long flues have T-iron or angle-iron hoops at the necessary
joints, the hoops to be placed 10 feet

Fig. 17.-Rolled Hoop.
apart. Some makers prefer placing the
T-iron hoops at each joint, the plates
butting on one another, and at the
longitudinal joints likewise.¹ When the joints are planed, and
the butt strips properly fitted, the strain is entirely taken off the
rivets, the compressive strain being taken on the ends of the plates
directly.
In the cylindrical boiler, with round flues, the forces are diverging
from the central axis as regards the outer shell, and converging
as applied to every separate flue which the boiler contains. To
show the amount of strain upon a high-pressure boiler 30 feet
long and 6 feet in diameter, having two centre flues, each 2 feet
3 inches diameter, working at a pressure of 50 lbs. on the square
inch, we have only to multiply the number of square feet of sur-
face-1030 exposed to pressure-by 3.21, and we have the force
of 3306 tons which a boiler of these dimensions has to sustain. We
mention this to show that the statistics of pressure, when worked
out, are not only curious in themselves, but instructive as regards a
knowledge of the retaining powers of vessels so extensively used.
¹ These T-hoops are now almost superseded by rings shaped as above (Fig. 17), and
rolled specially for the purpose. The latter answer admirably, and also allow of ex-
pansion and contraction.
BOILERS FOR STATIONARY ENGINES.
27
To pursue the subject a little further, let us suppose the pressure to
be 450 lbs. on the square inch, which a well-constructed boiler of this
description will bear before it bursts, and we have the enormous force
of 29,754 tons, or nearly 30,000 tons, compressed within a cylinder
30 feet long and 6 feet diameter. This is, however, inconsiderable
when compared with the locomotive and some marine boilers, which,
from the number of tubes they contain, present a much larger surface
to pressure. Locomotive boiler engines are usually worked at
120 lbs. on the square inch; and taking one of the usual construction
we shall find that it rushes forward on the rail with a pent-up
force within its interior of nearly 60,000 tons, which is rather
increased than diminished at an accelerated speed. In a station-
ary boiler, charged with steam at a given pressure, it is evident
that the forces are in equilibrium, and the strain being the same
in all directions, there will be no tendency to motion. Supposing,
however, this equilibrium to be destroyed, by accumulative pressure,
till rupture ensues, it follows that the forces in one direction
having ceased, the others in an opposite direction, being active,
would project the boiler from its seat with a force equal to that
which is discharged through the orifice of rupture. The direction
of motion would depend upon the position of the ruptured part: if
in the line of the centre of gravity, motion would ensue in that direc-
tion; if out of that line, an oblique or rotatory motion round the
centre of gravity would be the result. (An explosion of a plain
vertical boiler may be taken as an example: it gave way at the
bottom of the fire-box or bottom of the boiler, and by the reactive force
of the steam it was lifted about 100 feet in the air like a sky-rocket,
and when the force was spent, and the water and the steam expelled,
it descended, landing on the identical spot where it had rested pre-
vious to the explosion.) The momentum or quantity of motion pro-
duced in one direction would be equal to the intensity or quantity
lost; and the velocity with which the body would move would be
in the ratio of the impulsive force, or the quantity lost. Therefore,
the quantity of motion gained by an exploded boiler in one direction
will be as the weight and quantity lost in that direction. These
definitions, however, belong more to the province of the mathemati-
cian, and may be easily computed from well-known formulæ on the
laws of motion.
The following table shows the bursting pressure of boilers, as
likewise the safe working pressure, as deduced from experiment,
28
MODERN STEAM PRACTICE.
with a strain of 34,000 lbs. on the square inch as the ultimate strength
of rivetted joints:—

Diameter of
Boiler.
Working
Pressure for
3/8-inch Plates.
Bursting
Pressure for
Working
Pressure for
8-inch Plates.
1½-inch Plates.
Bursting
Pressure for
1½-inch Plates.
3
3
4
4
4
4
6
6
6 6
6 9
77780 ∞ ∞
7 3
7 6
8
₤omo ao mo ao mo ao mo ao mo ao mo
OLOLOLOO
ft. in.
3 0
118
7084
1571/4
9444
3 3
109
65334
1454
87134
6
ΙΟΙ
607
134.34
8092
9
942
566½
12534
7552
9812
531
118
7084
3
83/4
500
III
6662
6
7834
472
10434
6292
742
4472
992
5964
7034
425
944
5662
6734
40434
8334
515
6434
3864
82
49234
61/2
3692
7834
472
59
354
752
4534
562
340
72½
43534
54.4
32634
6934
419%
52/2
31434
674
4042
50%
3032
65
39634
4834
293
6234
377/2
47
2834
6034
365/2
452
274
59
354
44
26534
57
3434
4234
257/2
552
33314
41/2
250
Rule for 3%-inch Plates.-Divide 4250 by the diameter of the
boiler in inches; the quotient is the working pressure, being one-
sixth of the strength of the joints.
Rule for ½-inch Plates.-Divide 56666 by the diameter of the
boiler, and the quotient will be the greatest pressure that the boiler
should work to while new; that is, one-sixth of the punched plates.
We now come to the rectangular forms, or flat surfaces, which are
not so well calculated to resist pressure. Of these we have many
instances: the fire-box of the locomotive boiler, the sides and flues
of marine boilers, and the flat ends of cylindrical boilers, and other
boilers of weaker construction. The locomotive boiler is generally
worked up to a pressure of 120 lbs. on the square inch, and at times,
when ascending steep inclines, we have known the steam nearly as
high as 200 lbs. on the square inch. In a locomotive boiler subject
to such enormous working pressure, it requires the utmost care and
attention on the part of the engineer to satisfy himself that the flat
surfaces of the fire-box are capable of resisting that pressure, and
that every part of the boiler is so nearly balanced in its powers of
BOILERS FOR STATIONARY ENGINES.
29
resistance, as that when one part is at the point of rupture, every
other part is on the point of yielding to the same uniform force.
This appears to be an important consideration in mechanical con-
structions of every kind, as any material applied for the security of
one part of a vessel subject to uniform pressure, whilst another part
is left weak, is so much material thrown away; and in stationary
boilers, or in moving bodies such as locomotive engines and steam
vessels, they are absolutely injurious, at least so far as the parts are
disproportionate to each other, because when maintained in motion.
they become an expensive and unwieldy encumbrance. The greater
portion of the fire-boxes in locomotive boilers have the rectangular
form, and in order to economize heat, and give space for the furnace,
it becomes necessary to have an exterior and interior shell. That
which contains the furnace is generally made of copper, firmly united
by rivets, and the exterior shell, which covers the fire-box, is made
of iron, and united by rivets in the same way as the copper fire-box.
Now these plates would of themselves, unless supported by rivetted
stays, be totally inadequate to sustain the pressure. In fact, with one-
tenth of the pressure, the copper fire-box would be forced inwards
upon the furnace, and the external shell bulged outwards, and with
every change of force these two flat surfaces would move backwards
and forwards, like the sides of an inflated bladder, at the point of
rupture. To prevent this, and give the large flat surfaces an
approximate degree of strength with the other parts of the boiler,
wrought-iron or copper stays, I inch in diameter, are introduced.
They are first screwed into the iron and copper on both sides to
prevent leakage, and then firmly rivetted to the exterior and interior
plates. These stays are from 6 inches to 434 inches asunder, form-
ing a series of squares, and each of these will resist a strain of about
15 tons before it breaks. Let us suppose the greatest pressure con-
tained in the boiler to be 200 lbs. on the square inch, and we have
6×6×200=7200 lbs., or 34 tons, the force applied to a square
containing 36 square inches. Now as these squares are supported
by four stays, each capable of sustaining 15 tons, we have 4 × 15=
60 tons as the resisting powers of the stays; but the pressure is not
divided amongst all the four, but each stay has to sustain that pres-
sure, consequently the ratio of strength to the pressure will be 4½
to I nearly, which is a very fair proportion for the resisting power
of that part.
We have treated of the sides, but the top of the fire-box and
30
MODERN STEAM PRACTICE.
the ends have also to be protected, and there being no other part
but the circular top of the boiler to which to attach stays, it has
been found more convenient and equally advantageous to secure
these parts with a series of wrought-iron bars, from which the roof
of the fire-box is suspended, and which effectually prevents it being
forced down upon the fire. It will not be necessary here to go into
the calculation of those parts. They are, when rivetted to the dome
or roof, of sufficient strength to resist a pressure of 300 to 400 lbs. on
the square inch. This is, however, generally speaking, the weakest
part of the boiler, with the exception probably of the flat ends above
the tubes in the smoke-box, where they are carefully stayed. In
the flat ends of cylindrical boilers, and those for marine purposes,
the same rule applies as regards construction, and the due propor-
tion of the parts, as in those of the locomotive boiler, must be closely
adhered to.
Every description of boiler used in manufactories, and also on
board ship, should be constructed to stand at least six times the
working pressure, or a pressure of about 500 lbs. on the square inch;
and locomotive-engine boilers, which are subjected to a much
severer duty, to about 800 lbs. per square inch. Internal flues, such
as contain the furnaces in the interior of the boiler, should be kept
as nearly as possible to the cylindrical form; and as wrought-iron
will yield to a force tending to crush it of about one-half of what
would tear it asunder, the flues should in no case exceed one-half of
the diameter of the boiler; and, with the same thickness of plates,
it may be considered equally safe to the other parts. In fact, we
should advise the diameter of the internal flues to be in the ratio of
I to 2½, instead of 1 to 2 of the diameter of the boiler. Corrugated
flues as now made of iron or steel give increased strength.
THE STRENGTH OF ROUND BOILERS WITH DIFFERENT
QUALITIES OF PLATES.
ас
When the tensile stress of each boiler-plate is not known per
square inch, or the strain that it will bear before breaking, to find
the thickness for a certain diameter, multiply the diameter in inches
by the steam pressure, dividing the product by one-sixth of the
ultimate mean strength of the plate per square inch, and the
quotient is the thickness. When the boiler rests on brickwork, add
inch more. The tensile strain of the best boiler-plate is about
BOILERS FOR STATIONARY ENGINES.
31
62,544 lbs., and the worst 34,000 lbs. per square inch. Taking one-
sixth of the mean, or 8045 lbs.-(this is presuming the best plates
are used; if the plates are of inferior quality, it is obvious the con-
stant is too high proportionally, although it may answer in practice
with a parcel of the best plates untested)-we have, for a boiler
6 feet 6 inches in diameter, and with 60 lbs. steam per square inch,
the following result (the seams being single-rivetted):-
78 x 60
8045
9
58, say inch,
as the thickness, or when set in brickwork say 5% of an inch. This
is allowed on account of the corrosion that takes place with all boilers
resting on a brickwork foundation. The ends should be at least
% inch more than the calculated thickness.
In another form it may be taken thus-
P. Pressure per square inch.
D. Diameter of boiler in inches.
T. Thickness of plates in inches.
C. Constants for varying qualities of plates.
Double Rivetted. Single Rivetted.
C=For Yorkshire plates of best quality,.
C=For Staffordshire plates of best quality,...
C=For ordinary plates,...
7800
6200
6200
5000
3700
3300
T=
C=PD
2
It will be seen that this formula gives a thickness of the plates
somewhat less than the previous rule, using the best quality, a result
not at all to be desired; yet when the quality of the plates is tested
by a strip cut off each plate, one-sixth of the strength of the rivetted
joints, as per following table, may be safely taken as the constant.
The Strongest Form and Proportion of Rivetted Foints, as deduced from Experiment
and Practice.

Thickness of
Plates in Parts
of an Inch.
•18=18
Diameters of
Rivets in
Inches.
Length of Rivets Distance of Rivets
from Head from Centre to
in Inches. Centre in Inches.
Quantity of Lap
in Single Joints
in Inches.
*38
.88
*25=1
*50
1*13
2
'31=16
•63
1.38
1.63
1.25 6
1.50
1.25
1.50 6
1.88
*37=3/
*75
163 45
1.75
2.00 5.5
'50=
.81
2.25
2'00
2.25
•62:
'94 1'5
2.75
*75=
I'13
3.25
2'504
3.00
2.75 4'5
3.25
32
MODERN STEAM PRACTICE.
For double-rivetted joints, add two-thirds of the depth of the
single lap. Where great strength is desirable this form of joint
should always be adopted. It will be seen from the following table
that the double-rivetted joints retain their resisting power, while the
single-rivetted joints lose about one-fifth of the actual strength of
the plates.
The figures 2, 1*5, 4'5, 6, 5, &c., given in the preceding table are
multipliers. These multipliers are considered as proportionals of
the plates; thus, supposing we take 3% of an inch as the thickness
of plates, we have simply to multiply the thickness by the number
to find the proportionate quantities to form the strongest joint:—
Inches.
*375 × 2 = 750 diameter of rivet.
*375×4'5=1'687 length of rivet.
*375×5 =1.875 distance between rivets.
*375 × 5'5=2'062 quantity of lap, single rivetted.
*375×9*1=3'412 quantity of lap, double rivetted.
It will be seen that the dimensions thus found nearly agree with
the dimensions in the preceding table, which are practically correct.
Boilers are now being made of steel: as made by the Siemens or
Bessemer process, the tensile strength is about 29 tons per square
inch, and the elastic strength appears to lie within II to 16 tons
per square inch. Test pieces, 10 inches long, give an elongation of
28 per cent., with a contraction of area of about 49 per cent.
Punching the rivet holes weakens the metal by about 30 per cent.;
the strength can, however, be restored by annealing. Drilling the
holes does not seem to affect the strength. By the use of steel
the weight of boilers has been reduced about 10 per cent. For
further reference to manufacture and strength of steel see article on
Shipbuilding.
Mean Strength of Plates in the direction of and across the Fibre (Fairbairn).


Yorkshire Plates...
Do. do.
Breaking Weight
in the direction of
the Fibre, in tons
per square inch.
Breaking Weight
across the Fibre,
in tons per square
inch.
27.490
25.720
22.760
26.037
Derbyshire do.
21.680
18.650
Shropshire do.
22.826
22'000
Staffordshire do.
19'563
21'010
Mean..
22.509
23.037
BOILERS FOR STATIONARY ENGINES.
33
Tensile Strength of Single and Double Rivetted Plates.

Cohesive Strength of
Plates.
Breaking Stress in Lbs.
per Square Inch.
Strength of Single Rivetted
Joints, of equal Section
to the Plates, taken through
the Line of Rivets.
Strength of Double Rivetted
Joints, of equal Section
to the Plates, taken through
the Line of Rivets.
57,724
45,743
52,352
61,579
36,606
48,821
58,322
43, 141
58,286
50,983
43,515
54,594
51,130
40,249
53,879
49,281
44,715
53,869
43,805
37,161
47,062

Mean, 52,485
41,590
53,633
Ах
t
Area of boiler stays = AX, where A area of surface of plate
held by one stay, and p and t being the pressure and tenacity re-
spectively.
The following value of plates may be fairly assumed with those
of joints:-
Plates....
Double Rivetting.
Single Rivetting.
888
100
...
70
56
In a series of experiments by Napier the tensile strength of iron
plates averaged from 56,735 to 41,743 lbs. per square inch.
Weight of a Square Foot of Wrought-iron Plate from 1 to 1 inch in Thickness.

Thickness
in inches.
Weight
in lbs.
Thickness.
1
I'25
+
32
1
Weight.
21.25
2'5
18
16
22.5
9
18+ 32
3'75
16
14
5'
ala +
+3² 2
23'75
+ 굽고
​6'25
10100
+ 32
25°
26.25
11
1 छ
10
18+37
114
7'5
16
8.75
27.5
28.75
IO'
30°
1 +37
11.25
31.25
13
12.5
5
1/8 +37
13'75
18+32
15'
£100
융​+ 감
​1
कुठ
16.25
215
+ 32
15
1
32.5
33'75
35°
36.25
16
17.5
16
37'5
18+ 32
18.75
15
T6
+ 3 2
38.75
20°
I
40'
Weight of Angle Iron, in Lbs. per Lineal Foot.
Breadth in inches.........
Weight per foot in lbs........
14, 1½, 1¾, 2, 2¼ 2½, 2¾4, 3, 34, 32.
1·8, 2·7, 33, 3′9, 5, 6·5, 8′3, 10˚4, 11'7, 14.
35
34
MODERN STEAM PRACTICE.
Weight of a Lineal Foot of Square and Round Bar Iron, in Lbs.

Size.
Square Round
Bar.
Square
Round
Size.
Size.
Bar.
Bar.
Bar.
Square
Bar.
Round
Bar.
براطوات
*209
*164
14
5°25
4'09
3
30'07
23.60
*326
*256
13%
6.35
4.96
31/4
35°28
27.70
'470
*369
1½
7'51
5'90
32
40'91
32'13
*640
*502
15%
8.82
6.92
334
46'97
36.89
·835
*656
134
10'29
8:03
4
53'44 41'97
I'057
•831
I'305
I'025
I'579 I'241
122
17%
II 74
9.22
44
60°32
47.38
13.36
10'49
42
67·63
53'12
28
15.08
11.84
434
75°35
59'18
3
1.879
I'476
214
16.91
13.27
83.51
65.58
TT
2'205
I'732
238
18.84.
14'79
2'556 2'0II
2
20.87
16.39
مد إسم
ભગ
2.936
2.306
258 23.11
18.07
I
3'34
2.62
234
25'26
19.84
5556
54
92.46
72.30
5½
101.63
79'35
114'43
86.73
120'24
94'43
180
4'22
3°32
278 27'61 21.68
Diameter
Surface......
Surface of Tubes per Lineal Foot, in Square Feet.

inch 5% 3/4
16361963
7/8 I 1% 14 13%
1½
2291 2618 2945 3270 3599 3927
| |
2
3
Diameter inch 15% 134 1%
24 22 234
Surface...... 4253 45804906 5233 5890 6544 7199 7854
Weight per Foot in Lbs. and Decimal Parts of Iron, Brass, and Copper Tubes.



Inches
Inches
Birming-
Gauge.
External ham Wire Iron. Brass. Copper. External ham Wire Iron. Brass. Copper.
Diameter.
1½
138
134
7/8
B B N w w J
Birming-
Gauge.
Diameter.
13 I'402 1'529
|
1627
334
1528 1665
1772
4
13
1.653 1.801
1'917
44
12
2024 2 206
2347
4½
2
12
2.168 2.363
2514
434
21/8
12
2.311 2.513 2.680
5
214
II
2.687 2.928 3116
54
2/2
II
234
ΙΟ
534
3
ΙΟ
4038 4401
6
34
32
9
4826 5 260 5.598
6
9
5215 5684 6.049
3002 3272 3482
3685 4016 4 274
4.684
52
10 10 56 7
¯∞ ∞ ∞ ∞ 777NOO
5.640 6.148 9.500
6.652 7.250 7.716
7.087 7.724 8.220
7497 8171 8.696
7953 8.668 9.225
9*120 9940 10'579
9'596 10:459 11131
10.089 10 997 11 603
10:539 11 487 12:225
12.371 13°484 14*350
14 168 15 444 16 435
PROPORTIONS FOR PLAIN LAND BOILERS.
Shell-Having pointed out the principles to be observed in con-
struction, we will proceed to give the proportions generally adopted
in steam boilers. For each nominal horse-power make an allow-
ance of I cubic yard, or 27 cubic feet capacity; this is simply the
BOILERS FOR STATIONARY ENGINES.
35
cubical contents of the shell, with or without inside flues. Sup-
posing, for the sake of illustration, a Cornish boiler of 40 nominal
horse-power was required, multiply the horse-power by 27 cubic
feet, and the result will be the cubical contents, thus-
40 × 27 = 1080 cubic feet.
Length and Diameter.-The length of the boiler should be about
three and one-half times the diameter for moderate power, or up to
about 20 horse-power inclusive; above that size five times the
diameter can be adopted—a little more or less can do no harm. To
find the diameter, multiply 1080, the cubical contents required, by
the constant 128, dividing the result by the proportion of the dia-
meter to the length, say five times, and the cube root of the quotient
will be the diameter, which, multiplied by 5, gives the length of the
boiler nearly.
1080 x 1.28
5
=276'48 = say 6.5 × 5 = 32'5.
The length of the boiler, in round numbers, is 32.5 feet, and
6.5 feet in diameter. To check the calculation, the area of 6.5 feet
in diameter is 33·18 square feet × 32'5 = 1078.35 cubic feet, within
a trifle of what is required.
Heating Surface, Fire-grate, and Flue Area.-The heating surface
should not be less than I square yard, or 9 square feet, per nominal
horse-power; but in ordinary boilers it will be found that more than
this can be conveniently got. The area of the fire-grate, when the fur-
nace is underneath the boiler, should be I square foot, and when the
furnace is in a flue, forming part of the boiler, 75 of a square foot will
be sufficient, per nominal horse-power. The length of the fire-grate
should never exceed 7 feet. When the furnaces are placed inside of
the boiler, for small diameters, the inside flues should be 2 feet 6 inches
in diameter, and certainly not less than 2 feet 3 inches. When smaller
than this, the fires do not burn well, and they are troublesome to
fire; for large diameters of boilers, the furnace flues can be 3 feet
3 inches in diameter. The area of the furnace flues should be
about 28 square inches per nominal horse-power, a little more doing
no harm; thus for 40 horse-power, we have for two furnaces-
40 × 28 = 1120 ÷ 2 = 560 square inches,
equal say 2 feet 3 inches diameter for each flue in the boiler, and
4 feet 6 inches as the sum of the width for both; thus, for the
36
MODERN STEAM PRACTICE.
length of the grate, making an allowance of 75 of a square foot per
nominal horse-power, we have—
40 x 75 6.6 feet in length.
4'5
=
The area over the bridge is generally about 18 square inches per
nominal horse-power.
Water and Steam Room.-For boilers with hemispherical ends,
the water should fill the boiler two-thirds of its diameter, thus leav-
ing one-third as steam-room. For Cornish arrangement with two
furnaces (otherwise known as the Butterly boiler) the water generally
fills the boiler three-fourths of its diameter, the remainder being the
steam-room. One foot height of water over the furnaces is allowed;
when one furnace is adopted the steam-room in the boiler can be in-
creased, and it is always advisable to have steam domes fitted to
the top.
RELATIVE VALUE OF HEATING SURFACE.
Horizontal surface above the flame,
Vertical
=1'0
=0'5
Horizontal surface below the flame,.
Tubes and flues....
Ο Ο
14 of their diameter.
BOILER FOUNDATIONS.
With the foregoing proportions we may now commence to lay out
the boiler foundations. The boilers are generally ordered in dupli-
cate, so that no stoppage may occur in the event of one of them
requiring repairs; indeed, when deposits rapidly form from impurities
in the water, frequent inspection is necessary, periodical scaling and
cleaning out being required. After the ground is excavated, a bed
of concrete is laid all over, on which is built the superstructure for
carrying and bedding the boiler thereon. The Cornish or London
boiler, with inside furnaces, rests on a mid wall, having cast-iron
supports imbedded in the middle wall, and should be of sufficient
height to leave about 3 feet 4 inches from the stoking-floor to the
dead plates on the furnace front. The boiler is surrounded with
what is technically termed a wheel-flue, that is to say, the flame and
the heated gases pass through the internal furnaces and the back
flues contained in the boiler, then wheel round at the end, and return
to the front—along one side, and pass along the other side nearest
the chimney, an opening being left in the mid wall at the bottom
BOILERS FOR STATIONARY ENGINES.
37
for the flame and the gases to cross from one side of the boiler
to the other side nearest the chimney, and they escape into a flue

K
H
I
E
E
E
E
O
F
H
E
E
E
A
G
D
EXE
E
F
D
I
E
B
DD, Boilers.
E, Furnaces, Flues, and
Chimney.
F, Steam receiver.
GG, Stop valves.
H, Manhole.
I 1, Dampers.
K, Safety valve.
Fig. 18.- Foundations for Cornish or London Boilers. A, End view.
B, Section showing direction of the Flues. C, Longitudinal section.
common to both boilers, and thence find their way into the chimney
placed at the end of this main terminal flue. The flues round the
boiler should have the necessary area, and sufficient room left at
38
MODERN STEAM PRACTICE.
the bottom for the convenience of executing repairs and cleaning out
the flues. To resist the action of the flame the flues are lined with
fire-brick, and at the front of the building openings are left, which
are fitted with cast-iron doors for the convenience of periodical
inspection of the boiler.
Damper-plates are fitted to each boiler. They are simply cast-
iron plates, sliding in suitable frames of cast-iron imbedded in the
building. The damper-plate has a "snug" cast on for attaching a
chain provided with a back balance weight, the chain passing over
a pulley, carried up by means of a cast-iron pedestal, securely fast-
ened down to a large stone imbedded in the top courses of the brick-
work. Sometimes the revolving pulley can be carried up from a
plate and pin secured to the wall of the boiler-house. To protect
the top of the boiler from radiation, it is arched over with fire-bricks,
the space between the boiler and the brick arch being filled in with
ashes, and sometimes sand is used.
The walls of the boiler-house are covered over with a suitable
wrought-iron roof, having a ventilator at the top for carrying away
any waste steam that may blow off. The arrangement of the flues
just described will suit all boilers having internal furnaces; but when
the boiler is constructed with one internal small flue, it is preferable
to form the furnace underneath.
Now for cylindrical arrangements, having hemispherical ends, this
class of steam-generators is usually longer in proportion to the dia-
meter than the Cornish type; in some instances six and three-quarter
times the diameter has been adopted. The buildings are very differ-
ent from the foregoing example. The same height from the stoking-
floor to the dead-plate is allowed, namely, 3 feet 4 inches. This
plate is made long, so that the coal may cake before being pushed
amongst the incandescent fuel, this effecting a considerable economy
when properly attended to. A height of about 2 feet 4 inches is
allowed in large boilers, from the top of the fire-bars to the under-
side of the boiler; and the flues are arranged on the wheel principle,
as in the Cornish type, with this difference, that the flame passes
underneath the boiler, and then ascends at the back, all round, and
thence up the chimney. There is a combustion chamber formed at
the back of the bridge, at the end of the fire-bars furthest from the
front, the flame as it were hanging at the hollow left in the bottom
flue, thus making the bottom surface of the boiler very effective as
heating surface. This recess likewise serves the purpose of collecting
BOILERS FOR STATIONARY ENGINES.
39
both the ashes and the soot that may be drawn over by the draught,
and which are raked out through a hole, fitted with a movable door,

E
E
E
А
E
K
F
E
0910
L
H
H
M
I
I
B
C
G
F
D D, Boilers.
E, Furnace, Flues, and
Chimney.
F, Steam receiver.
GG, Stop valves.
H, Manhole.
11, Dampers.
K, Safety valve.
L, Float.
м, Feed-pipe.
N, Blow-off tap.
Fig. 19.-Foundations for Cylindrical Boilers. A, End view.
B, Section showing direction of the Flues. C, Longitudinal section.
placed at the bottom of the bridge. The boiler is usually set with
a dip towards the back of % inch to the foot, so that the sludge
40
MODERN STEAM PRACTICE.
may collect at the part farthest from the fire. A plug-valve is
fitted to the underside of the boiler, to which is attached a pipe
leading into a drain left in the building; by this means the water
flows away when the boilers are blown off. The buildings are
generally hollowed out to lighten the structure, and the boiler is
fitted with brackets, bolted to the top, so as partly to take the
weight; but the main support is at the sides of the furnace, the
furnace walls being carried up from the bed; but at times when the
sides of the furnace are undergoing repair, the top brackets take the
weight. All the flues must have sufficient area, as likewise doors
must be left in the brickwork for cleaning them out; the height
from the top of the bridge to the under side of the boiler is gener-
ally about 18 inches. The fittings are just the same as for the
Cornish boiler, having a wrought-iron steam-chest connecting all
the boilers, provided with a stop-valve to each boiler, with the
addition of a stone float and back-balance for indicating the height
of the water inside of the boiler. No float is required for the
Cornish class, as the ordinary water-gauge is fitted to the front
end; hemispherical-ended boilers, however, can have a gauge-glass
in front, with suitable pipe connections passing through the brick-
work. The safety-valve is placed on the top, at the fire-end,
then the stop-valves, next the float of stone with weight, then the
manhole, and the feed-pipes at the back of the boiler, all placed on
the centre line.
We will now notice the arrangements for one small internal flue.
The furnace is placed underneath the boiler, the flame acting on the
bottom, and then through the small tube, which carries it to the
front, the flame splitting as it were at the front end, passing down
each side, and meeting at the back in one central flue, in the same
line as the centre of the boiler; this is required so that the draught
may be equalized in the side flues, as the heated gases have always
a tendency to take the shortest passage into the chimney. Some
boilers of the cylindrical type, with hemispherical ends, are hung
from the top with brackets, having no support underneath, the
flame acting on the bottom and the sides, and then passing directly
into the chimney; this is not so good an arrangement as the return
flues, as the flame and the heated gases have no time to act on the
surfaces, unless boilers of inconvenient length are adopted. The
furnace bars should be made in suitable lengths, having a thick-
ness of % inch at the top, and ½ inch at the bottom, with
BOILERS FOR STATIONARY ENGINES.
41
projections at the ends, and the middle of the top, the open-
ings between the bars varying from 3% to ½ inch, to suit soft

E
A
E
E
Q
I
H
H
M
E
B
F
G
D D, Boilers.
E, Furnace, Flues, and
Chimney.
F, Steam receiver.
GG, Stop valves.
H, Manhole.
II, Dampers.
K, Safety valve.
L, Float.
м, Feed pipe.
M,
##
Fig. 20.-Foundations for Boilers with small Internal Flue. A, End view. B, Section showing
direction of Flue. C, Longitudinal section.
and hard coal, the depth of the bars at the middle being from
32 to 4 inches.
AREA AND DIMENSIONS OF CHIMNEY.
To determine the area of the top of the chimney for a given con-
sumption of coal per hour, the average for Cornish boilers being
10 lbs. per nominal horse-power, multiply the number of lbs. con-
sumed per hour by 12, and divide the product by the square root
of the height of the chimney in feet (the usual height for factory
42
MODERN STEAM PRACTICE.
chimneys being 80 feet), and the quotient is the area at the top of the
chimney, thus for 40 nominal horse-power-
40 X 10 X 12
√80
=539, say 26 inches diameter,
or 23 inches square at the top. It is always preferable to make an
allowance over and above this for the convenience of leading other
flues into it. For a chimney 80 feet in height the brickwork should
be divided into three courses: for 30 feet height from the bottom two
bricks in thickness, the next course one and a half brick in thick-
ness, and the remainder one brick thick. For each 25 feet added
in height the brickwork at the bottom should be increased one-
half brick in thickness. The batter or the slope of the side is usually
0.3 of an inch to the foot. Thus, with 26 inches inside diameter at
the top, the bottom of the chimney would be 92 inches external
diameter, while that of the top would be 44 inches. Should the
internal diameter at the top require to be 54 inches and upwards,
the top course should be one and a half brick in thickness, and the
bottom courses in proportion. The inside at the bottom is lined
with fire-bricks, leaving a space of one inch between the inner lining
and the main building, and is carried up to a height of 15 feet from
the bottom. For a chimney 80 feet in height the foundation should
be at least 5 feet in depth, laid on a bed of concrete 2 feet in thick-
ness, but this will depend on the soil; on sand or gravel this bed will
be quite sufficient, but of course some soils require the foundation.
to be carried down to a firm bed. In marsh land, and even for the
Colonies, wrought-iron chimneys may be used with advantage, but
brick chimneys are to be preferred. The best temperature for an
efficient chimney draught is about 600° Fahr.
SMOKE PREVENTION.
Although the distance between the fire-bars varies from 3% to
½ inch, allowing a good volume of air underneath the grate, so
essential for perfect combustion, other means must be taken to con-
sume the gaseous constituents thrown off from coal when in the semi-
incandescent state; the simplest and most effectual way of doing
this is by admitting a current of air through a series of small holes.
drilled through the furnace door, thus supplying the common oxygen
contained in the atmosphere, and of which we have an unlimited
command. Many schemes have been brought forward from time
to time to consume the gases evolved before a dense mass of smoke
BOILERS FOR STATIONARY ENGINES.
43
is formed in the flues, for if the gases are not consumed before reach-
ing the flues, it is impossible to burn the smoke with the ordinary
arrangements; but those who are under the impression that smoke,
or at least what we term smoke, cannot be burned when once formed,
labour under a sad mistake, for the densest volume passing through
a regenerative furnace is effectually consumed.
We will take the Butterly boiler, having two internal flues or fur-
naces meeting in one combustion chamber at the back of the bridge:
fire both of these furnaces at one and the same time, and dense
volumes of smoke will be seen issuing from the top of the chimney;
the smoke is formed in the furnace, and passes over the bridge.
Now this arrangement, with careful firing, in a great measure prevents
smoke issuing from the chimney. One fire should be bright while
the other one is dull, or in the act of firing, and what is the conse-
quence? the combustion chamber is in a perfect glow, from the bright
fire; and the smoke evolved by the dull one is effectually consumed
by the other. This simple fact is half of the battle; careful firing
is the best and most economical means for the prevention of smoke;
so by alternately firing little or no smoke is seen issuing from the
top of the chimney. Such practice every good fireman is perfectly
conversant with.
As hydrogen is the main element in the gases evolved, and by
the admixture of the oxygen of the atmosphere flame is produced;
and as neither hydrogen nor oxygen can burn of itself, it remains for
us to supply a current of air, so as to obtain the most economical
result from the fuel. With the common blow-pipe an intense heat
is obtained by simply blowing a current of air through a flame of
gas, or rushes, as used by the gasfitter. And in the smelting fur-
nace air is forcibly blown through a coil of pipes, surrounded and
inclosed in a furnace, the air is thus intensely heated, and, indeed,
will melt a bar of lead before it is admitted into the smelting fur-
nace; this is termed the “hot blast," and is familiar to all metallur-
gists. Were it not for the complication entailed, this method would
be by far the best plan that could be adopted for steam boilers, but
such an intense heat is not at all desirable, for should the water in
the boiler fall below the working level, the plates would get intensely
hot, and an explosion would be the inevitable result; so a moderate
measure of heated air is all that is required.
A very simple plan for introducing heated air is by arranging
small pipes, fixed to the front plate of the boiler, as in the double
44
MODERN STEAM PRACTICE.
furnace Lancashire class, the pipes passing through the water space
to the combustion chamber plate, through which they are securely
rivetted, or clenched over. Thus a current of hot air passes through
the tubes, mixing with the flame and gases in, the combustion
chamber, so that when the fires are properly attended to, as with all
arrangements introduced for the prevention of this nuisance they
must be, little or no smoke will appear at the top of the chimney.
The introduction of heated air into the combustion chamber after
the smoke or gases have passed the bridge, seems mainly to keep up
the temperature of the flues, by the admixture of the oxygen of the
atmosphere with the flame in the combustion chamber; this plan,
where it can be conveniently applied, should always be adopted.
As before stated, vertical boilers are so fitted with a series of small
air-tubes all round the fire-box, inclining downwards, thus the air
freely mixes with the live coal. In former years some persons
scouted the idea of consuming the smoke after passing the bridge;
the fact of our now being able to do so speaks for itself. Some
may term it gas before it has passed the bridge; but what we
plainly see in the furnace we denominate smoke.
For single furnaces a very different arrangement is adopted,
the smoke being consumed in the furnace: the fire-door is perfor-
ated with a number of small holes 3% inch in diameter, drilled
closely together. It seems impossible to give the exact number of
holes to suit all furnaces, as the same furnace, with different kinds
of coal, requires more or less openings, as the case may be, and even
the same furnace often requires more or less air with the same kind
of coal; this may be owing to the temperature of the atmosphere, or
which way the wind is blowing; if blowing in such a direction as to
fan the fire, as in the forward boilers for marine purposes, less air
will do at the furnace door. Thus it is imperative to have a great
number of holes, say 5 to 6 square inches for every foot of fire-grate
surface; they should be covered with a regulator, or movable disc-
plate, with corresponding holes for regulating the supply; some
adopt slits instead of round holes, but the latter, or jet system, is by
far the best, as it distributes the air equally amongst the gases in
the furnace. This plan necessitates regulation by the damper.
Should no steam be required, or the engine not working, or even
when the fireman is trimming the fire, the damper can be shut, check-
ing the draught for a time; the smoke remains in the furnace, or is
slowly consumed there, thus preventing it issuing at the chimney top.
BOILERS FOR STATIONARY ENGINES.
45
6
Another plan for consuming the smoke is attained by blowing
superheated steam through a number of minute apertures placed
at the front of the furnace; with high-pressure steam in the boilers;
this plan works well, so long as the apparatus remains in good
order. The steam requires to be dry before it is sprayed into the
furnace in minute jets above the grate. The steam from the boiler
is made to flow through a coil of pipes placed in the fire-brick bridge,
and then passes through a pipe laid across the furnace front, fitted
with nozzles having holes inch in diameter; the pipe is fitted
with a plug-valve to regulate the supply to the nozzles, the furnace
door being provided with a number of air holes, the superheated
steam is turned on, causing a powerful current of air to pass through
the fire door, and before mixing with the gases in the furnace is
distributed with the steam jets into minute atoms, and we may
say the mere forcing of the atoms driving the oxygen through
and between the live coal, produces complete combustion, with
great economy in fuel. This is much better than any plan we
know of, from the fact that fuel will burn with this arrangement
that would be entirely worthless in ordinary furnaces. By the use
of the jets of superheated steam all the waste cinders from the
smithy can be utilized, and dross or small coals effectually burned,
without the smoke nuisance; but we unhesitatingly give as our
opinion, that unless the attendant sees that the furnace is kept in
proper trim, firing with the least quantity of coal, oft times replen-
ished, that all the refinements for the prevention of smoke will not
attain the desired object, for careful firing is the main secret to
arrive at.
SYSTEMS OF TUBING.
The triangular and square systems of tubing have certain advan-
tages as well as disadvantages. With the former, almost used
exclusively for locomotive boilers, a greater number of tubes can be
got into less space, the water being honey-combed as it were with
a large amount of heating surface. The tubes for locomotive boilers
are generally made of composition metal; this is absolutely required
where deposits form from impurities in the water. When iron or
steel tubes are used, the small water spaces, in some instances only
half an inch, soon get choked up, and the steam does not rise freely;
and as the arrangement will not allow of much scraping and clean-
46
MODERN STEAM PRACTICE.
ing, were deposits forming to any great extent, it would soon prove
fatal to the boiler. To partially remedy this evil the boiler should

Fig. 21.-Systems of Tubing.
A
be emptied every day, while for other boilers the water must be
blown off frequently. With the triangular system of tubing the
steam generated from the bottom row of tubes must take many a
zigzag course before reaching the top, or the
steam space.
To obviate the difficulties at-
tending the triangular system the square plan
is adopted, more especially for marine boilers,
so that when iron or steel tubes are used there
is some possibility of scraping and cleaning
them occasionally; and even where composi-
tion tubes are adopted the square system finds
favour, as the globules of steam generated
from the tubes pass up in parallel rows be-
tween the tubes, instead of following the zig-
zag course as in the triangular system.

B
C
A
DRY STEAM.
In order to provide as dry steam as pos-
sible, without using a superheater, there should
be steam-chests of ample capacity fitted to
all land boilers, in fact we may say to every
class of boiler where they can be convenient-
ly applied; but as the steam still contains
watery particles, a separator may be fitted to the steam-pipe. The
action of this contrivance is very simple, and consists in abruptly
Fig. 22.-Separator. A, Steam-
pipe. B, Receiver. c, Tap.
BOILERS FOR STATIONARY ENGINES.
47
changing the flow or current of the steam. To a vertical chamber
a right-angled pipe is suspended, passing down into the chamber
a little below the exit pipe; the steam flowing through the pipe
from the boiler impinges against the elbow, causing the moisture
contained in the steam to trickle down the pipe, thus the water is
collected at the bottom of the receiver, and is drawn off at pleasure
with a tap; this plan is very simple, and it can be made self-acting
by means of a float and valve. We consider these separators for
drying the steam, or rather separating the moisture contained in the
steam, should be fitted to all steam-pipes.
D
E
A
C
Taking Low-pressure Steam from a High-pressure Boiler.-Some-
times it is desirable to reduce the pressure of the steam, so as to work a
low-pressure engine from a high-pressure boiler. There are a variety
of plans for doing so; we have an equilibrium valve, actuated by the
pressure of the steam acting on a piston open to the atmosphere,
and regulated by a lever and spring-balance, similar to the safety-
valve on the locomotive engine boiler. The valve is formed of five
rings cast together, with four vertical arms, or ribs, having a boss
for securing the valve-spindle; this annu-
lar tube moves in a corresponding seat,
cast together, with vertical pieces between
the openings; there is an annular passage
all round the seat, with a branch pipe
communicating with the steam-boiler. On
the lower part of the valve-chest a branch
pipe is cast in communication with the
cylinder of the valve-casing of the engine,
and on the top of the chest a short cylin-
der and piston are arranged, the piston Fig. 23-Steam-reducing Valve
being connected to the valve by a screwed
rod and nuts. The combined circumfer-
ential openings in the valve are equal in area to that of the pipe
from the boiler, and the pipe for the engine must be of sufficient
area according to the usual rules for steam-pipes. By this contriv-
ance the steam can be regulated to the greatest nicety. The action
is as follows:-After being properly set with the nuts on the valve-
spindle, and the thumb-screw on the balance at the end of the lever,
should there be an accumulation of steam in the chest, after passing
the valve, the steam acts on the piston in connection with the valve,
and by its pressure lifts it partially, shutting the apertures until the

A, Valve. B, Piston. c, Lever and
spring-balar.ce. D, Branch from
boiler. E, Branch to cylinder.
48
MODERN STEAM PRACTICE.
balance is restored, thus keeping up constant low pressure, regu-
lated at pleasure by the thumb-screw pressing down or releasing
the piston and the valve. One of these valves can be fitted to the
main steam-pipe, or a separate one for each cylinder when required.
THE DETERIORATION OF LAND BOILERS.
After a time the plates of all boilers deteriorate, the iron becomes
brittle, and although the plates have a sound-looking exterior, with-
out the slightest symptoms of corrosion, yet such a boiler should
not be worked beyond a certain number of years, and certainly not
at so high pressure as it was originally designed for; in fact, the
steam pressure should decrease year by year, so as to work it with
any degree of safety. It must be understood, however, that unless
a new boiler is properly managed, it is quite as unsafe as a much
older one well managed. To determine the number of years a
boiler ought to last, with fair treatment, we must have recourse to
experiment. When it is thought a boiler has done enough duty
test it to destruction. Such experiments are very easily carried out,
and it is the interest of steam users to do so, that correct data may
be arrived at by a careful experimentalist.
We place before our readers the results of a series of experiments,
testing two boilers to destruction, instituted by Mr. Peter Carmichael,¹
and which forms a useful contribution on the subject of steam-
boilers. The boilers were cylindrical, with double flues, and were
used at the Dens Works, Dundee, for nineteen years. They were
precisely alike, and of the following dimensions:-Length, 25 feet;
diameter, 7 feet; diameter of furnaces and end flues, 2 feet 9 inches;
diameter of back end of flues, 2 feet 6 inches. The shell was made
of 3% inch "Glasgow best iron;" the flues of Glasgow best scrap iron,
3/8 inch thick, the end plates being inch in thickness. The boilers
were kept in work until the beginning of November, 1869, when it
was resolved to take one out, and test it to destruction by water
pressure. In the case of the above boilers the pressure has never
been so great as 60 lbs., and as reported they were not wasted,
having always been kept in good repair, and have stood the peri-
odical water test of 60 lbs.; therefore we may presume they could
have been worked for a year or two longer. The fact of the iron
getting hard and brittle after being in use for a length of time had
7
16
¹ See Trans. Inst. Engineers and Shipbuilders in Scotland, vol. xiii.
BOILERS FOR STATIONARY ENGINES.
49
been often pointed out, and in consequence the pressure ought to
be lowered, or new boilers introduced, after they have been working
for sixteen or seventeen years. Before testing, all the brick flues
were taken down, so that easy access could be got to all parts of
the boiler, but it was left sitting on its natural seat. The boilers
were filled with water of about 120° temperature, and a force-pump
was then attached. To check off the pressure no fewer than five
pressure-gauges were used, four of which nearly indicated the same
pressure and tallied with the safety valves. At 80 lbs. pressure per
square inch an examination was made, and all appeared to be right;
but as soon as the pump was started again the joint of the safety
valve was blown out, and this stopped proceedings for a time.
After this joint had been made good the pressure was again brought
up, and at 85 lbs. the joint of the feed-pump pipe, at the front end
of the boiler, began to leak, owing to the bulging out of the end.
At 100 lbs. a number of the longitudinal seams of the shell began
to exude water badly. The pressure was then removed, and the
ends gauged above and below the flues, and on the pressure being
again put on the following was the result:-Front end blow flues.
bulged out in centre inch at 35 lbs. pressure; 3% inch at 100 lbs.
pressure; front end above flues bulged out in centre inch at
35 lbs. pressure, inch at 100 lbs. pressure; back and below flues
bulged out at centre inch at 35 lbs. pressure, inch at 100 lbs.
pressure. The pressure was then brought up to 105 lbs., when the
ring seam at the back of the taper of the left-hand flue began to
crack, and the pump became unable to keep up the pressure, owing
to the great leakage. This joint or seam when gauged, before
testing, measured 2 feet 334 inches horizontally, by 2 feet 5 inches
vertically; and it gave way by crushing inwards on the flat or hori-
zontal side, and remained flattened after the pressure was taken
off. This boiler was then removed, and sent to the foundry for
breaking up.
32
3
16
4
32
.5
32
4
32
Mr. Carmichael proceeded to clear away the brick flues from
the sister boiler. On the 15th December, 1869, it was tested in the
same way, having been in use for rather more than nineteen years.
The flues were gauged, and were found, with one exception, similar
to the other boiler. The exceptional one being 1½ inch oval, it
was attempted to support this flat part by fixing a batten in the
line of the shortest axis of the ellipse, but this was not found to
be of any use, as the plate bulged, oozed out below at one end of
4
*
50
the batten and
MODERN STEAM PRACTICE.
16
above at the other end, and loosened it when the
strain came on.
The pressure was noted as before; at 60 lbs. pres-
sure the feed-pipe began to leak, the end bulging out inch. At
80 lbs. the feed valve joint leaked very much, and the longitudinal
seams of the shell began to exude water; at 90 lbs. the south or right-
hand flue began to crack, as if giving way; at 95 lbs. one of the joints
of the shell, and the first rings on the crown of the boiler, commenced
to spout water, and the pressure could not be kept up, the leakage
being equal to the supply of the force-pump. The joints of the feed-
valve were then tightened, and also some parts of the shell caulked,
the right-hand flue being found to be very much flattened. The
pressure was again put on, but it could not be got higher than
80 lbs., as the flues had given way so much as to allow the water to
escape by the fracture as fast as it was pumped in; so that the
highest pressure attained was 95 lbs., and this pressure had so injured
the joints and flattened the flues as to render further experiment
impossible. According to Fairbairn's rules the bursting pressure of
these boilers was about 300 lbs. on the square inch, yet they failed
with one-third of this pressure. When the boilers were broken up
the plates were very brittle; indeed, so much so that it was a diffi-
cult matter to get strips for testing. The rivets had likewise deteri-
orated, and the heads flew off when the plates were struck with a
hammer. The test strips gave the following results:-Shell in the
direction of the fibre, 197 tons; across the fibre, 192 tons; while
Glasgow best plates is 24'04 tons in the direction of the fibre, and
21.8 tons across the fibre. Furnace plates, direction of fibre, 17'1
tons; ditto across, 15.3 tons. It will thus be seen that the mean of
the shell plates is 1945 tons, and that of the furnace 162 tons.
Thus the furnace plates had deteriorated or weakened from 227
tons to 16-2 tons, while the shell had weakened from 22.92 tons to
19:45 tons. Now this is after the boilers had done duty for nineteen
years; so we are of opinion that sixteen years is quite long enough
for boilers similarly constructed to be in use: and we trust other
firms will follow Mr. Carmichael, so that this all-important question.
of the deterioration of boiler plates that have not shown the slightest
symptom of corrosion, as in these boilers, may be finally deter-
mined, with different qualities of plates.
In recording the testing of another old steam boiler, Mr. Car-
michael states,1 "The result of the test so nearly coincides with that
¹ See Trans. Inst. of Engineers and Shipbuilders in Scotland, vol. xxii.
BOILERS FOR MARINE PURPOSES.
51
of the two former boilers-namely, 95, 105, and 112 lbs. pressure,
that it may be accepted as the ultimate strain that boilers of this
construction can bear after being twenty years in use. It is much
less than that due to the formula usually given for a new boiler."
This boiler was twenty-five years old. Some of the plates and
rivets showed little or no change, but brittleness appeared in the
angle-iron.
BOILERS FOR MARINE PURPOSES.
It is not our intention to treat upon the old flue-boiler, with its
multitudinous arrangements, as that class has now become nearly
obsolete, though there is still a demand for them in particular cases,
such as for dredgers. The arrangement of this type of boiler
should be as simple as possible, and all the flues ought to run in
the same direction, and be of uniform width, commencing at the
part where the flame and gases meet from the furnace.
Fig. 25.
A A, Furnaces.
B, Combustion chamber.
c, Tubes.
D, Smoke-box.
E, Uptake.
Fig. 24.
E
A A, Furnaces.
B, Flue.
c, Uptake.
When


C

D
A
B

B
HIG
A
Fig. 24.-Flue Boiler for Dredger.
A
Fig. 25.-Tubular Boiler for Dredger.
Longitudinal and Horizontal Sections.
more than one furnace is adopted all flues from the furnaces which
join into one large flue should taper from the furnace farthest from
the large main flue. This is obvious, as the flame and gases from
that furnace mix with the next, and so on; care ought to be taken
52
MODERN STEAM PRACTICE.
that the main flue is large enough, and that the flame and heated
gases do not meet in opposite directions. As dredgers generally
work in harbours, where the water is very muddy, the mud being
stirred up from the bottom by the action of the buckets, small
tubular boilers should be avoided; the tubes should be at least
8 inches in diameter, with ample water space between them. The
tubes in such cases are joined to the tube-plates, with a flange of
angle-iron rivetted to the tube. In this example there are two fur-
naces, one at each side of the boiler meeting in a back flue, with
return tubes at the same level as the furnaces. By this means ample
water above the tubes, and a large steam space, are obtained. As
it is an object to keep the weights low down, and as dredging
vessels are generally shallow, a low boiler should be adopted, placed
well below the deck, to give free passage fore and aft for the moor-
ing chains, &c.
For ocean steam ships the multitubular boiler is decidedly the
best, although some very good examples of flat flue overhead arrange-
ments find favour. The tubes vary from 2½ inches to 4 inches in
diameter; and in the merchant service they are placed over the
furnaces on the return principle. When for moderate power, and

E
D
C
B
A
A
Longitudinal Section.
Front Elevation and Transverse Section.
Fig. 26.-Ordinary Tubular Boiler.
AA, Furnace. B, Combustion chamber.
B, Combustion chamber. c, Tubes. D, Smoke-box. E, Uptake.
arranged fore and aft, the boiler is generally made in one piece.
Some of these boilers have no bottoms, but are simply fitted with
a dry plate; while others, made in the usual manner, have dry plates
laid on the bottom of the furnaces, thus preserving the rivet heads
BOILERS FOR MARINE PURPOSES.
53
from getting rubbed away by the mere friction of the tools for
raking out the ashes.
Some boilers are constructed, as it were, back to back, in one
large boiler. By this means two ends are saved, but the great
weight of the mass deters many from adopting this plan; but where
large power is required in small space, the arrangement has certain
advantages. The stoke holes must be "fore and aft;" and in general
the fore part of the boiler is the best steam producer, owing to the


E
E
D
D
C
B
B
C
上
​↓
A
A
888
Fig. 27.-Double Boilers. Longitudinal Section and Front Elevation.
B B, Combustion chambers.
A A, Furnaces.
АА,
cc, Tubes. DD, Smoke-boxes.
EE, Uptakes.
air getting better circulated in the stoke hole, but, with suitable
air funnels from the deck, the aft furnaces of the boiler can be pro-
vided with the plentiful supply of air so necessary for combustion,
and for keeping the stoke hole cool. There is a passage left be-
tween the two boilers, forming a communication between the fore
and aft stoking-rooms; two funnels are fitted, and the general
arrangement is best suited for paddle-wheel ships.
Another modification differs materially from the former example,
having one combustion chamber common to both sets of furnaces.
This will tend, in a great measure, to effect complete combustion,
and the prevention of smoke; that is to say, if the furnaces are
properly constructed and fired-the fore and aft furnaces being
fired alternately, so that one fire is bright while the other is receiv-
ing fresh fuel. To assist combustion, air is admitted through the
bridge, thus getting partially heated before mixing with the flame
in the combustion chamber. These boilers are made high to insure
ample steam room, while the large area of the uptakes inside of
the boiler dries the steam. Indeed, some think this is by far the
54
MODERN STEAM PRACTICE.
best plan for superheating the steam; far before the complicated
arrangements of separate superheating boxes, with the extra stop-
valves, &c. In fact, dry superheaters soon get out of order, more
especially when there is no steam in the boilers, as must be the case


D
E
E
C
B
C
A
A
D
J
A
INANANAMUAMMIRANIHAAR MAARANATH
A A, Furnaces.
Longitudinal Section.
Front Elevation and Transverse Section.
Fig. 28.-High Double Boiler.
B. Combustion chamber. cc, Tubes. DD, Smoke-boxes. E E, Uptakes.
for a considerable time when the fires are first kindled. Any one
can fancy the flame acting on a thin tube, roasting, as it were, the
steam, which subsequently dries up the lubricants, and soon plays
havoc with the slide-valves, pistons, and cylinder faces of the engine.
Steam is only partially dried in the best modern practice, and can
be done in the boiler itself. It will be understood, in the boiler
described, that two ends and two furnace backs are saved, the
material being better disposed in the uptakes.
As we are dealing at present with low-pressure steam-boilers
suited for the merchant service, we will draw attention to overhead
flue arrangements. All boilers of this class should be so designed
that every part is easily accessible for repairs; and, when properly
constructed, we do not see why the flues should not last as long as
any other part, and certainly boilers can be designed so that the
flame and heated gases will pass up and down over a greater length
of surface than in the plain tubular boilers. The flues in this ex-
ample are the entire width of the boiler, leaving 6 inches of water
space at the sides; the flame passes to the top of the combustion
chamber at the back of furnaces, then dips downwards, and so on,
BOILERS FOR MARINE PURPOSES.
55
the flues being divided with suitable water spaces, and are strength-
ened at the top and bottom with conical tube stays, through which
the steam rises and the circulation is effected. The water in the
boiler is thus freely circulated, with the advantage of having a mode-


חתון
E
DURGANERINT
Антинины»
TUUH
B
A
A
0 0 0
Fig. 29.-Overhead Flue Boilers. Longitudinal and Transverse Sections.
A A, Furnaces. B, Combustion chamber. c,
c, Flues. DD, Circulating tubes.
Circulating tubes. E, Uptake.
rate body of water, which, under certain circumstances, conduces to
rapid evaporation. There are side doors at the bottoms of the flues
for the convenience of cleaning them out, which can be done in
some instances while the vessel is under way. Another form of flue


E
D
Co
A
B
A
Fig. 30.-Overhead Flue Boilers. Longitudinal and Transverse Sections.
AA, Furnaces. B, Combustion chamber. c, Flues. D, Smoke-box. E, Uptake.
boiler in extensive use materially differs from the foregoing example.
The flues are quite narrow, and are arranged overhead, similar to
tubular arrangements. The flues are 3 feet 9 inches deep, 6 feet in
56
MODERN STEAM PRACTICE.
length, with 2 inches of space for the flame to pass through, and the
pitch of the flues is 434 inches. They are formed of two parallel
plates for the sides, with U-shaped pieces at the top and bottom;
the side plates are flanged at the ends, as well as are the U-pieces at
the top and bottom, for uniting them to the tube plates. The method
of rivetting the top, bottom, and the sides together is as follows: the
rivets are put through the holes, then wedging bars are placed in
at the top and the bottom, and means taken to secure them in their
places. Thus the rivets are firmly held in position, and are clenched
quite cold; and when each section of the tubes are rivetted together
they are placed between the tube plates, and firmly rivetted thereto.
This kind of work requires to be carefully executed; for, should
great leakage occur at sea, the tubes are not easily repaired. The
flues are well stayed every 9 inches apart either way; these stays
also act, to some extent, as heat conductors. When the work in
this class of boiler is well executed it gives very little trouble at sea,
which is essential in all marine steam generators.
The arrangement of low-pressure boilers for ships of war differs

F
E
A A, Furnaces.
B, Combustion chamber.
CC, Tubes.
D, Smoke-box.
E, Uptake.
F, Chimney.

D
C
C
B
'I AS KES KARI KULELENINSU
A
0000
Fig. 31.-High Boilers, as arranged for the Royal Navy. Longitudinal and Transverse Sections.
There
from the tubular class adapted for the merchant service.
are two classes, namely, high and low, the former having the tubes
BOILERS FOR MARINE PURPOSES.
57
over the furnaces on the return principle, while the latter have
generally the furnaces fore and aft, with the tubes athwart ship,
the tubes reaching no higher than the tops of the furnaces. The
best arrangement for the high class are furnaces athwart ship, with
the stoke-hole between the boilers on the centre line of the vessel-
the distance apart from front to front of the boilers being 10 feet;
this is considered ample room for the firemen. As the top of the
boilers requires to be at least I foot below the water line, the ordinary
steam-chest is dispensed with, sufficient height being left between
the top and the water in the boiler. To give free circulation fore
and aft, the uptake or dry smoke pipe is shaped thus, A, flat at
the bottom sides, but rounded at the top, to take the main funnel.
This is a very good plan.
We have also seen many arrangements formed with the steam-
chest over the firemen's heads; a plan that should never be attempted,
as such require an artificial blast to keep free circulation in the stoke-
hole, the usual plan being a fan driven by a separate engine; but
in some classes of war ships, such as "Monitors," even this fan is
necessary, the “free-board” in such ships being so low that in rough
weather the hatches require battening down, and then ventilation.
must be kept up by mechanical appliances.
The low class boiler is
admirably suited for fine.
midship sections, firing
fore and aft.

They are
placed closely together at
the centre line of the ves-
sel, leaving only a space
of 2 inches between the
lagging, or the wood cover-
ing which is placed over
the boilers to prevent ra-
diation. The furnaces, say
three in number, join in
one "athwart-ship flue,"
widening from the furnace
at the centre of the vessel
to those at the sides, and
A
A
B
A
C
D
E

Fig. 32.-Low Boilers, as arranged for the Royal Navy. Lon-
gitudinal and Horizontal Sections. A A, Furnaces. B, Com-
bustion chamber. c, Tubes. D, Smoke-box. E, Uptake.
then passing into the combustion chamber, which runs fore and aft,
this chamber tapering from the furnaces to the extreme end. This
58
MODERN STEAM PRACTICE.
is necessary, as the flame has always a natural tendency to take the
nearest cut to the funnel: thus, when the combustion chamber is
made wide at the furnaces and narrow at the extreme end the flame
and gases are more equally distributed through the tubes. The tube
plates are placed at an angle, for the convenience of getting out
the tubes for repairs; and at the back, under the funnel, there is
space left for cleaning out the tubes.
When the boiler space is rather
E
B
B
C
A
A
D
C
limited, as in narrow vessels
such as despatch boats, the fur-
naces are arranged fore and aft,
with two furnaces at the centre
of the ship, with separate com-
bustion chambers for each fur-
nace. This arrangement will
suit best when the stoke-hole
is forward, so that a current of
air freely passes through, the
air supply being greatly im-
proved by the forward motion
of the ship. The tubes are
arranged at the sides on the
return principle, but they are
placed no higher than on a level
with the top of the furnaces.
The high and low pressure combined engines necessitate a stronger
form of steam-generator, for which circular boilers are decidedly the
strongest. One arrangement of double boiler has three furnaces
at each end, the middle one being placed much lower than the two
side ones; this is done to fill up the dead water space at the bottom.
The furnaces are fore and aft, with one combustion chamber com-
mon to both; they are provided with dry uptakes fitted to the fronts.
When four uptakes are arranged for one funnel, each boiler has a
separate tubular uptake with a flue running through it. All the
uptakes converge to the centre of the vessel; these uptakes serve
the purpose of superheaters, and the inner tube, or flue, is strength-
ened with rings of angle-iron. For 300 horse-power nominal, the
boilers being 13 feet 6 inches in diameter, the heating surface in each
is as follows: 2308.88 square feet in tubes, 100 square feet in fire-
box, 248.22 square feet in furnaces, making a total for two double
boilers, 53142 square feet, or 1771 square feet per nominal horse-
Fig. 33.--Low Boiler for Despatch Boats. Transverse
and Horizontal Sections. A A, Furnaces. BB. Combus-
tion chambers. CC, Tubes. DD, Smoke-boxes. E, Uptake.


BOILERS FOR MARINE PURPOSES.
59
power.
So it will be seen that circular arrangements can be placed
in almost as little space as ordinary marine boilers.

E
F

E
$2
C
D
C
B
C
D
A
A
A
A
A
Fig. 34.-High-pressure Double Boilers. Transverse and Longitudinal Sections.
A A, Furnaces. B, Combustion chamber. cc, Tubes. DD, Smoke-boxes. EE, Uptakes. F, Separate uptake.
Some are arranged for only two furnaces in each single boiler,
with tubes overhead as in the previous example, and having one
combustion chamber common to both furnaces; this chamber at

C
4.off
[<ff·
Total tubes 888.
2½ Dram
E

D
A
B
Fig. 35.-High-pressure Boilers. Transverse and Longitudinal Sections.
AA, Furnaces. B, Combustion chamber. c, Tubes. D, Smoke-box. E, Separate uptake.
the back of the furnaces is made large; indeed, in all boilers hav-
ing tubes on the return principle the combustion chambers should
60
MODERN STEAM PRACTICE.
have ample capacity, so that the flame hangs, as it were, before
passing through the small tubes, giving more time to abstract the
heat from the gases before they pass up the chimney. This is more
required when the uptakes in front of the furnaces are made dry,
or separate from the body of the boiler, so as to keep the stoking-
room as cool as possible. For moderate power, say 300 horse-
power nominal, four boilers are adopted, with uptakes arranged
for two funnels; and should the section of the vessel be very fine,
with a great rise of floor, the back end can be bevelled or cut away
at the bottom to suit the form of the ship. All the flat parts are
stayed in the usual manner. For ships of war, when the stoke-
hole is fore and aft, on the centre line of the vessel, the uptakes
should form part of the boiler, as dry uptakes would make it intoler-

E
F
TA
COCO CO
A
A
D
C
B
Fig. 36.-High-pressure Boilers, as arranged for the Royal Navy.
A
A A, Furnaces. B, Combustion chamber. cc, Tubes. D, Smoke-box. EE, Separate uptakes. F, Chimney.
ably warm for the firemen. The uptakes, or "lumleg,” should be
made double; they can be made slightly oval, and be strengthened
with conical tubes, so that the steam freely passes through them;
and when great steam pressure is demanded the insides and the
outsides of the uptakes should be well secured with screwed stays;
this arrangement will make a very effective superheater. The top
of the uptakes must be below the water line. When one funnel is
required for six boilers, it is placed centrally between the four front
boilers, and the aft boilers have dry pipes, thus joining the three
boilers on a side; the back of the boilers at the bottom are cut
away to suit the form of the ship, but when this is not required
they should be straight, thus simplifying the construction. The up-
takes must be fitted with the usual outer casings, for taking away
the vitiated atmosphere from the stoking-rooms.
BOILERS FOR MARINE PURPOSES.
61
For small power for great steam pressure, one furnace is fitted
with return tubes at the side; while other boilers have the furnace
central with the boiler, with return tubes overhead and at each side.
The lower tubes in such an arrangement should be larger; thus the
flame is drawn down, as it were, and the bottom tubes by this plan
are kept free from soot deposit. Another arrangement has two
furnaces in each boiler, with the combustion chamber at the back
of the furnaces, and then the tubes placed direct through the boiler,
thus entailing a long boiler; and this plan is good when there is


A
A
A
Q
0 0 0 0 0 0 06
D
D
A
B


E
A
B
C
A
B
D

Figs. 37, 38, 39.-Small High-pressure Boilers.
A, Furnace. B, Combustion chamber. c, Tubes.
sufficient room in the vessel.
D, Dry uptake. E, Steam dome.
When a steam-chest can be fitted,
it is preferable to do so; and it is found a great advantage in such
small boilers to line the combustion chamber with fire-bricks, having
apertures for the smoke to freely pass. The steam pressure usually
adopted is from 40 to 60 lbs. per square inch, and such boilers are
best suited for river navigation, where good fresh water is obtained.
As some river boats are made very shallow, and constructed of
very light scantling, it is desirable to have the boiler, and all the
machinery, designed to spread over a large surface; and when
62
MODERN STEÁM PRACTICE.
•
100 lbs. steam pressure is used, boilers of the locomotive type are
decidedly the best, and they can be made of steel, thus tending
materially to increase the carrying power for cargo by lightening the
boiler. The same class is largely used for steam-launches, having
the whole of the machinery fitted thereto.
Torpedo boats are now fitted with the locomotive type of boiler,
carrying a working pressure of about 120 lbs. per square inch. The
draught is forced by a fan blast. The evaporation in these boilers
per lb. of coal seems to be about 7 lbs., and the evaporation per hour
per square foot of heating surface varies from 11 to 18 lbs. The coal
consumed per hour per square foot of grate varies from 50 to 100 lbs.
The haystack boiler, originally introduced in Clyde river practice,
is well suited for vessels of light draft. The shell is cylindrical
with a dome-shaped top. The tubes are placed vertically, with the
furnaces beneath and around the sides.
PROPORTIONS FOR MARINE BOILERS.
When a number of boilers are to be designed of various sizes, it
will facilitate the designer if he fixes on the scale to be universally
adopted, and get the drawing-paper prepared with light lines, ruled
in 2-inch squares, according to the scale determined on, these squares
corresponding to the pitch of the rivets, or 2 inches between centre
and centre. It is by far the cheapest and best arrangement where
the front and the sides are worked square at the corners, the back
at the top and the bottom being rounded, as in many instances
this requires to be done to fit the midship sections of the vessel.
Boilers so designed, and drawn on ruled paper, greatly assist the
draughtsman in getting up the working drawings for the work-
shop.
After making a rough sketch of a boiler, we know about the
length, breadth, and the height required, and commencing on the
side of a square, we lay off the length, breadth, and the height per
scale; thus the configuration of the boiler is represented by so many
squares; the length, breadth, and the height should always be even
dimensions, and there is nothing to prevent all boilers being so
constructed. We may now set out the plating, taking the centre of
the squares as the edges of the plates, wherever we arrange the joints,
breaking bond where required. It is evident that the plates must be
always of even dimensions. Each plate will contain as many rivets,
of the universal pitch of 2 inches, as there are squares; thus by
BOILERS FOR MARINE PURPOSES.
63
counting the number of squares in each line of plating in the length
and the breadth we arrive at the true length and breadth of each
plate without using a scale, the ruled paper being the universal
scale for all flat surfaces; all the other parts of the boiler where
practicable should be set out in like manner, and after they are
marked on the drawing No. 1, No. 2, &c., these are the marks.
that must be numbered on each plate as delivered from the rolling-
mills. No. I plate will contain so many rivets in the length and
breadth, thus the machinemen need never apply a foot-rule, but
simply adjust them on the travelling table of the drilling or punching
machine, and the machine itself will do the work of drilling or
punching the plates with mathematical precision, the plates being
previously planed on the edges to the correct size.
In all Government contracts the top of the boiler must be at
least I foot below the water line. To insure ample steam room
3 feet 6 inches is allowed from the top of the boiler to the top of
the flues. For boilers intended to run out about four times the
nominal horse-power make an allowance of 68 to 7 of a square
foot of fire-grate surface, per nominal horse-power, and from 18.8
to 19 square feet of heating surface, taking the whole circumference
of the small tubes that in multitubular arrangements is available,
including the flues, sides, and the tops of the furnaces above the
fire-grate, and one half of the back tube-plate may be included in
the total heating surface. Composition tubes are usually adopted,
having an external diameter of 2½ to 3½ inches, and the pitch of
the tubes 3% to 434 inches. The length of the tubes may vary
from 5 feet 6 inches to 7 feet, but should never exceed that length.
Fire Grate and Heating Surface for Indicated Horse-power.—For
every indicated horse-power the engine is intended to work at, make
an allowance of about 3 to 3½ square feet of heating surface, and
one-eighth of a square foot, or 18 square inches, of fire-grate for
every horse-power indicated. The consumption of coal per square
foot of grate is about 20 lbs. per hour, and the water evaporated
about 9 lbs. per lb. of coal.
Writing on this subject, Professor Rankine gives as follows:-"The
greatest available heat, or the rate of expenditure of heat upon the
steam, is to be compared in units of work, by dividing the greatest
indicated power required in units of work, per unit of time (say in
foot-pounds per hour), by the probable efficiency of the engine; or,
otherwise, multiply the pressure equivalent to the rate of expendi-
64
MODERN STEAM PRACTICE.
ture of heat by the total cylinder capacity, and by twice the number
of revolutions per minute.
Probable indicated power,..
FIRST METHOD.
× foot-pounds per hour (in indicated horse-power),.
x
The above divided by the probable efficiency of the steam, o'12, gives
the available heat required in foot-pounds per hour,...
SECOND METHOD.
743
1,980,000
1,471, 140,000
= 12,259,500,000
Estimated pressure equivalent to rate of expenditure of heat in steam
(lbs. on the square inch) 108 x estimated total cylinder capacity in
prism of I foot x I inch x inch by twice the number of revolutions per
hour,...
39,033
4,228,575
28,992
12,259,484,650
"Available Heat required in foot-pounds per hour.-The available
heat of combustion of 1 lb. of fuel (or rather coal) is to be estimated
by multiplying the total heat of combustion of 1 lb. of fuel by the
efficiency of the furnace.
"The total heat of combustion of 1 lb. of coal of a good quality for
marine purposes may be estimated at from 9,000,000 to 10,000,000
foot-pounds, and that of the very best at 12,000,000 foot-pounds.
Inferior qualities about two-thirds of the above estimates.
"The efficiency of the furnaces may be roughly estimated as fol-
lows-Divide the intended number of square feet of heating surface
per lb. of fuel per hour, by the same number +0.5, eleven-twelfths
of the quotient will be the probable efficiency nearly. The following
are examples:—
Square Feet
Heating Surface
per Lb. of Fuel
per Hour.
Efficiency
of
Furnace.
Available Heat
per L.b. of Coal
of Total Heat,
10,000,000.
Small Value for Marine Boilers .....
0'50
0'46
4,600,000
0'75
0'55
5,500,000
1'00
0.61
6,100,000
Ordinary Values in Marine Boilers
I'25
0.65
6,500,000
1'50
0.69
6,900,000
2'00
0'73
7,300,000
Water Tube and Cellular Boilers,
3'00
0'79
7,900,000
6:00
0.84
8,400,000
"The most common values of the available heat of a pound of good
BOILERS FOR MARINE PURPOSES.
65
steam coal in marine boilers are 5,000,000 to 6,000,000 foot-pounds,
making an allowance of 20 to 50 per cent. for waste, &c.
"To find the probable greatest rate of consumption of fuel, divide
the available heat per hour by the available heat of combustion of
I lb. of fuel (example) available heat per hour, 12,260,000,000 ÷
available heat of combustion per lb. coal, say 5,500,000 2229 lbs.,
probable consumption of fuel per hour.
"To find the proper area of heating surface, multiply the rate of
consumption of fuel in pounds per hour by the intended area of
heating surface to each pound of fuel per hour, that is usually from
3/4 to 1 ½ square foot.
"To find the proper area of fire-grate, divide the rate of consump-
tion of fuel in pounds per hour by the weight of fuel in pounds to
be burned per hour on each square foot of grate, the quantity ranges
in ordinary boilers from 16 to 12 lbs., and the latter limit may be
considered a suitable rate for the most rapid combustion at high
speed, provided air is admitted above the fuel to burn its gaseous
constituents. In some grates the combustion is as low as from 6
to 12 lbs.
"The total sectional area of flues (or tubes) is from one-fifth to one-
seventh of that of grate, the area of the chimney one-tenth of that
of the grate.
"The capacity of marine boilers is equal to the heating surface
multiplied by about 1 foot for flue boilers, or 0625 of a foot for
tubular ones (exclusive of furnace room), including all internal parts;
the contents may be estimated as nearly equal to the area of fire-
grate multiplied by from 6 to 8 cubic feet, one-fifth being steam-
room, and the rest partly water space, &c."
The following are some of the relations which exist in recent
marine practice:—
Grate Surface in square feet = Nominal Horse-power × %.
Heating Surface in square feet = 25 to 28 times the Grate Surface.
And oths of the total Heating Surface = Tube Surface.
Or Grate Surface in square feet =
Indicated Horse-power,
8
And Heating Surface in square feet = Indicated Horse-power × 3%.
Staying. Flat surfaces, such as for low-pressure marine boilers,
must be strengthened with a suitable number of stays. The dis-
tance between the stays may be 18 inches for pressures below 20 lbs.
per square inch, but for pressures above 20 lbs. per square inch, the
5
66
MODERN STEAM PRACTICE.
distance between should be 16 inches, in the parts that require
periodical inspection, but in confined places where it is not easy of
access 14 inches between the stays may be adopted. As corrosion
rapidly sets in, the stays must be made of greater strength, in the
first instance, than what is actually required; and it is advisable
that all the stays should be rivetted to angle-iron secured to the
boiler, palms or flat pieces being forged on the stays for taking the
rivets. By this plan the angle-iron materially stiffens the sides of
the boiler. When the sides of the boiler are stayed with round bar-
iron, screws are formed at each end, the diameter at the bottom of
the thread being the same as the main body of the bar: thus the
ends being larger than the bar, are more easily passed through
and through. These stays have nuts on the outside and inside of
the plates, with washers for screwing the nuts against: by this means
the plates can neither bulge out nor collapse. The sides of the
furnaces and water spaces all round the combustion chamber at the
back of the boiler have screwed stays similar to a locomotive boiler.
These stays are simply short bars of iron, screwed from end to end,
the plates being tapped to receive them, so that when they are
screwed into the two plates, each bar forms a secure stay to resist
bulging and collapsing; and as they require to be at times removed
they are not rivetted as in the locomotive boiler, but merely fitted with
nuts on each plate. The stays for the sides of the furnaces should
be well kept out of the fire; they can generally be so arranged that
the top rows are above the live coal, as high up as convenient, and
the bottom rows entirely below the fire-bars. The tube-plates should
be properly stayed. Some makers prefer using tube-stays, well
screwed at the ends and fitted with outside and inside nuts. Some-
times collars are formed on the stay-tubes for the inside, and nuts
on the outside. This is not a very good plan, for should anything
happen to a tube, there is a difficulty in taking it out, and it is evident
that it cannot be replaced. The best method of staying the tube-
plates together is by sacrificing some of the tubes as heating surface,
and staying with plain round bars screwed at the ends, with nuts inside
and outside of the plates. Although for the working parts of marine
engines, and all parts subjected to tension, 4000 lbs. per square inch
is allowed for wrought-iron, it is advisable for the stays only to
allow about 3000 lbs. per square inch. We will now run out the
number and diameter required in a flat-sided boiler, supposing the
side is 10 feet by II feet, and say 56 stays can be conveniently got
BOILERS FOR MARINE PURPOSES.
67
3000
in. Find the number of square inches in the surface, multiply by
the pressure per square inch, say 20 lbs.; thus, 10X II X 144=15,840
×20=316,800 lbs., equal pressure on the whole surface, which,
divided by 3000, gives the total area of the stays; and again by 56,
gives the area in square inches for each stay at the bottom of the
thread: 316800
1056561.8 square inch area for each stay, say
1½ inch in diameter. For the screwed stays in the furnace side-
plates the diameter is generally 1/4 inch, with spaces to suit; and the
stays which secure the sides and bind the top and bottom together—
i.e. the stays passing through the water spaces between the small tubes
are made of flat bar-iron, with screwed ends and nuts inside and out.
Fire-bars.-Wrought-iron fire-bars have a breadth of 13% inch
at the top and ½ inch at the bottom, and are 3 inches deep.
Weight of Wrought-iron Bars,……………………..
Weight of Cast-iron Bars,..
Weight of
do.
Weight of
do.
1 Weight of
do.
Weight of
do.
3 ft. 3 in. long = 30 lbs.
♡ 2 2
33
O
6
O
= 19
= 24
= 27.5
6
= 32°0
4 O
""
= 36'5
¡
Cast-iron bars have a breadth of full % inch at the top and full
½ inch at the bottom, the depth ranges from 3 to 4½ inches, and
the distance between bars from 3% to ½ inch.
Tube Area, Furnaces, &c.-The calorimeter of the boiler or sec-
tional area of the tubes is a subject no one need trouble himself
about, as the combined area of the tubes is greatly in excess of
what is required, and in which we have no choice, as it depends on
the length of the tubes that can be introduced. The ordinary size
of tubes for the merchant service varies from 3 to 4 inches external
diameter, and from 6 feet to 7 feet in length; while for the Royal
Navy the tubes are 2% to 3½ inches external diameter, and 5 feet
6 inches to 7 feet in length, consequently it will be seen that the longer
the tubes are the greater the heating surface, while the combined area
through them may be the same. The only thing to be considered
is to arrange them so as to get the greatest effect from the fuel. For
the Royal Navy composition tubes are usually adopted, as their con-
ductive power is greater, and the water spaces are not so liable to
choke up with deposit; but for the mercantile marine iron and steel
tubes are extensively used. The tubes in either case are driven hard
into the holes in the tube-plates, and, after they are all in their places,
are widened out with a suitable tool, and the edges neatly laid over.
68
MODERN STEAM PRACTICE.
Sometimes ferrules are fitted and driven into the tubes nearest the
furnaces, but at the smoke-box end they are simply expanded, and a
slight countersink left in the holes on the outside, thus forming a collar
when the ends of the tubes are laid over. The flues and combus-
tion chamber at the back of the boiler are of great importance, more
especially with short tubes arranged and worked on the return prin-
ciple. In many boilers of this class the flame and heated gases pass
too rapidly through the boiler into the chimney, and if not fitted with
a high uptake causes great waste in fuel, the flame and gases having
little time to act on the heating surface. The combustion chamber
should be made large, so as to make the flame hang in the flues
before passing through the small tubes. The usual size at the top
of the combustion chamber is 18 inches, and at the bottom 22 inches,
from the tube-plate to the back of the chamber, this being actually
required in all cases to properly expand and lay over the ends of
the tubes. It is advisable, however, not to increase this space to any
great extent, more especially for high pressure, as large flat surfaces
are not to be desired. But for moderate pressure, 22 inches at the top
and 26 inches at the bottom will tend to retard the flame and gases in
the combustion chamber. The area over the bridges is from 18 to
19 square inches per nominal horse-power; thus it will be seen that
the calorimeter of the tubes is greatly in excess of this. It must be
acknowledged by all that marine boilers should have as many fur-
naces as possible, bearing in mind that there is a certain size of
furnace very convenient to manage, and other sizes, above or below,
that are not so convenient. A good medium is a width of 2 feet
9 inches, and certainly not less than 2 feet 6 inches, or greater than
3 feet 3 inches, and from 6 feet to 7 feet in length, but should not
exceed the latter, as a 7-feet furnace is quite long enough to manage
properly. But in some instances the boiler room is so limited that
length must be substituted instead of breadth. Some makers have
even gone to the extreme as regards the width, considering if they
make the furnace circular, a diameter of 3 feet 6 inches could be
used with impunity; but experience proves the contrary, as with
ordinary sea water scale will form, and accumulating to any great
thickness, the furnace plates become heated and the tops come
down, even although there is a plentiful supply of water in the boiler.
So as many furnaces of a medium width as can be conveniently
arranged are far better than a less number of a great width, con-
sidering the more furnaces we have there will be more side surface
BOILERS FOR MARINE PURPOSES.
69
exposed to the action of the fire; for undoubtedly at the tops and
sides of the furnaces the water is most rapidly evaporated, and
consequently a better steam-producing boiler will be obtained,-a
result that all should strive to reach, even although it may be at
considerably more cost in manufacturing.
Thickness of Plates for Round Boilers.—As these boilers, for the
compound marine engine, are made large in diameter, carrying high
steam pressure, the best quality of iron must be used, or B, B, equal
to Yorkshire plates, the breaking strain being 57,120 lbs. per square
inch; and taking one-fifth of the breaking strain of the plate or
rivetted seams as the constant for this quality of iron, we have—
DP
11424
-thickness of the shell.
Thus, supposing we have a boiler 142 inches in diameter, and the
steam pressure 70 lbs. per square inch-
142 × 70
11424
=
.87 or 8 inch thick.
The seams should be double-rivetted, which are nearly equal in
strength to the solid plates. For the thickness of the plates for the
other parts of boilers we give two examples by English and Scotch
firms, the steam pressure being 70 lbs. per square inch in each
case:-
London Made.
Leith Made.
inches.
Diameter of Boiler..
Thickness of Shell
inches.
.142
---
120
11
Do.
End Plate....
50 esta es
11
18
Do.
Tube Plate....
111
Do.
Furnace Plate..
76
Do.
Back of Furnace Plate......
16
76
7
18
Strength of Flue Tubes to resist crushing. Example:—
.432 inch thickness of plate x constant 700000
7.25 feet length of tube × 36 inches, diameter of tube
ult. strength 495 ÷ 6th = 82 lbs. working pressure.
In a paper on the Strength of Boilers, by Mr. J. Milton, surveyor
to Lloyd's,¹ the question of factors of safety is considered; and it
is shown that the ordinary cylindrical boiler is the only really reli-
able marine boiler at present in use, and that as the shell plates had
reached up to a thickness of 114 inch, the weight of such a boiler
became an important item in the load carried by the ship. Hence,
¹ See Trans. Inst. Naval Architects, session xviii.
70
MODERN STEAM PRACTICE.
any method whereby the boiler could be lightened, and yet kept
efficient, would be of great value for mercantile purposes. It is
shown that Prof. Rankine and others estimate that a factor of safety
of eight is necessary for such a live load as steam. The author
however, states, "Now experiments show conclusively that up to a
temperature considerably exceeding that at which it is practicable
to use steam, wrought-iron does not lose strength; and as no part.
of a properly designed boiler is subjected to a temperature much
greater than that of the steam within it, without being specially
strengthened, there does not appear to be any reason for this great
difference of factor of safety. The Manchester Steam Users' Asso-
ciation, founded by Fairbairn for the prevention of boiler explosions,
consider that where boilers are well built and carefully examined
periodically a factor of safety of four is sufficient, and the correctness
of these views is shown by the freedom from accidents in boilers
guaranteed by them; but of course we are not warranted in con-
cluding from this that the same factor would be sufficient for marine
boilers, which often cannot be subject to the same careful and
systematic examinations as land boilers. The old-fashioned box
boiler working at from 10 to 30 pounds had only a factor of about
four, and yet the accidents which have happened with this low factor
of safety were quite as few in proportion to the number of boilers.
in use as with the higher factor of six, which is about the present
practice of the country, although at the same time improved appli-
ances have enabled boiler-makers to make better and more reliable
work than formerly. But although the present factor of safety is
nominally six in many boilers which are at present at work, there
are parts which, either from oversight or want of knowledge on the
part of their designers, are very much weaker than the other parts,
and which considerably reduce the actual factor of safety. Yet we
find that these specially weak parts are often quite strong enough
for their work, for even after many years' service they do not show
any signs of weakness. If these parts are strong enough, then un-
doubtedly the extra strength of the remainder of the boiler has been
so much useless weight."
On the question of proportioning the strength of boiler, the effect
of expansion is pointed out as an important agent in the tear and
wear of a boiler. "There are certain strains which boilers are sub-
ject to which are, under certain conditions, much greater than any
which the working pressure can bring upon them, and which are
BOILERS FOR MARINE PURPOSES.
71
altogether independent of the factor of safety employed. I mean
the strains brought upon the boiler by the unequal expansion of its
different parts.
Ordinary wrought-iron plates, if left free from
stress, expand '0000064 of their linear dimensions for each degree
Fahr. increase of temperature. Also if the plates are subjected to
stress they alter in length a certain amount according to the quality
of the iron; the more ductile irons altering more for the same
amount of stress. Taking as the mean value of E, 29,000,000 (the
value given by Rankine) we find that a stress of 186 lbs. per square
inch will give the same alteration in length as 1° Fahr. If, now,
the ends of a plate are rigidly fixed so that it is incapable of altering
its length, an increase of 1° Fahr. will subject it to a compressive stress
of 186 lbs. per square inch, and a decrease of 1° to a tensile stress
of equal intensity; and it is to be observed that these stresses are
totally independent of the sectional area of the plate. Now, in the
case of a furnace, the portion above the fire, especially when coated
with even the thin enamel or scale which is necessary to preserve it
from corrosion, must be considerably hotter than the portion below
the bars. Hence the top of the furnace tends to get longer than
the bottom. If the end fastenings of the furnace were so rigid as
to maintain the top and bottom of same length, the top would have
to be compressed and the bottom stretched, and every difference of
a degree Fahr. in the temperature would produce a compressive
stress in top and a tensile stress in bottom of 93 lbs. per square inch.
But actually the end fastenings are not so rigid, and the strains
caused by the unequal expansion are not distributed from top to
bottom by the ends only, but also in a great measure by the resist-
ance to shear of the plate, and hence the greatest stresses come at
the middle of the length of the furnace. Also, it is evident that
these strains are not uniformly distributed, and hence their maximum
must be greater than their mean, and with a great difference of
temperature the stresses reach a high figure. The only way to
strengthen furnaces from such strains is either to prevent the differ-
ence of temperature, or else to allow the crown freedom to expand.”
The question of reduction of strength of plates by punching or
drilling has had much attention, and experiments go to prove the
greater strength of drilled plates. Steel plates should always be
drilled; if punched, they must be annealed afterwards to reduce the
local strains set up by the action of the punch.
The corrosion of boilers is an important matter, and recently since
1
72
MODERN STEAM PRACTICE.
the introduction of steel the question has been raised as to the rela-
tive resistance of the iron and steel plates to this action. So far as
experiment or experience has gone, the action seems to be pretty
much the same in both materials. The influence of scale upon the
steel plates is prejudicial, as a galvanic action is set up between the
part covered with scale and any parts not so covered, which causes
pitting of the latter. This scale of black oxide can be removed by
exposure to acid, and in ships building at present for H. M. Navy
the plates are immersed in a solution of sulphuric acid and water so
as to clear away any scale which may adhere to them.
Where certain kinds of peaty water is used for feeding, the boiler
seems to be quite unaffected by corrosive action. This is notably
the case in the boilers of the Loch Lomond steamers, some of which
after very many years' service are unaffected by corrosive action.
It appears that a kind of coating, of a dark or brownish colour, is
deposited on the iron, which protects it, and does not appear to
affect the conducting power of the plate.
One method of bringing about the much to be desired lightening
of boilers is to adopt the locomotive type of boiler with forced com-
bustion. This method is now tried in steam launches, or torpedo
boats, where as much as 150 lbs. of fuel appears to have been
burned per foot of grate per hour.
In reference to this question of economy of weight, The Engineer,
in a leading article, July 8, 1881, says “The modern high-pressure
marine boiler is by no means all that a boiler should be. We may take
as a type a three-furnaced boiler to carry 70 lbs. Such a boiler will be
about 12 feet in diameter by 10'6 feet long. It will contain three
furnaces, each three feet in diameter, and a little more than 7 feet
long, and each furnace will have a separate back uptake, and sixty
3-inch tubes 7 feet long. A boiler of this kind, if fitted with a large
steam dome, will steam well, and may be depended upon, with fair
coal, to work a pair of compound engines up to 500 indicated horse-
power. Its shell plates will be nearly 1 inch thick, and its total
weight without water will be roughly 28 tons, and it will hold 14
tons of water. Its gross weight therefore will be, under steam and
allowing for grate-bars, &c., not far short of 45 tons. It will have
a grate surface of about 57 square feet, a tube surface of 900 feet,
the crowns of the furnaces will amount to about 100 square feet,
and the uptakes may be taken as 120 feet more. The total heating
surface will be therefore a little over 1100 square feet.
BOILERS FOR MARINE PURPOSES.
73
"If we contrast this with a locomotive boiler, we find that the
latter will not weigh, complete with water and in working order,
more than 12 or 13 tons. It will have I 100 feet of heating surface,
and 18 to 20 square feet of grate, and it may be depended upon to
develop 600 horse-power in a non-condensing engine.
“The cubical space occupied by the locomotive boiler will not be
more than one-fourth of that taken up by the marine boiler, and it
will be on the whole quite as economical, if not more economical.”
In referring to objections to the use of the locomotive type of boiler
at sea, it is pointed out that a fair trial has not yet been made of
such boilers at sea for mercantile purposes, and that it has proved
serviceable in torpedo boats.
Attempts are being made at present to give practical effect to
this question of decreased dead weight by reducing the diameter of
the shells, and giving increased draught so as to consume more fuel
per foot of grate surface.
As to the question of the relative economy of chimney draught
and forced draught, it has to be borne in mind that although power
has to be expended in driving fans or blowers to produce a forced
draught, still in the chimney draught a large proportion of the heat
of the furnace is spent to produce and keep up such draught,
reaching, according to some authorities, to one-fourth of the avail-
able heat of combustion.
It has been proposed to carry out forced draught by jets of steam
in funnel or air in ashpit, or by fans blowing air into ashpit direct,
or into the stoke-hole, the latter in this case requiring to be air-
tight.
Funnel, Damper, &c. - The ordinary height of funnels for
steamships of the merchant service is about 32 feet 6 inches
from the top of the steam-chest, and about 48 feet height from
the top of the fire-bars, the areath of fire-grate. Where
more than one funnel is required the arrangement of the boilers
will determine the number and positions of the funnels. It is
very usual now in large ocean-going ships to have two funnels,
and in some cases even three funnels, as the City of Rome, Livadia,
and other vessels. In the first-named ship the funnels are arranged
fore-and-aft, in the Livadia athwart-ships. The plates are gener-
ally arranged in four lengths, the three lengths towards the bottom
9 feet each, and the top plates 5 feet 6 inches. The joints are butted,
with strips inside of the chimney, and the circumferential joints are
74
MODERN STEAM PRACTICE.
made with a flat ring and iron moulding. At the top horizontal
joint, or 27 feet from the bottom of the funnel, lugs are forged on
the ring, on which to fix links for the funnel shrouds, which are
secured below to the side of the ship.
Thickness of Bottom Plates,
Do. of Top Plates,
Joint Straps,.
...
16
inch.
41 × 18
Flat Rounded Moulding,.
3 inches.
The bottom of the funnel is fitted to a cast-iron ring secured to the
top of the steam-chest. Where four boilers are used this ring is
divided into four parts, with cross bars of cast-iron, cast in one piece,
to which is fitted a damper for each boiler, having an uptake from
each, independently of the others, that the draught of each boiler
may be regulated separately. One of the cross bars is cast hollow,
forming a pipe from the side to the centre of the ring, or centre
of the funnel; this is termed the blow-pipe, and is fitted with a
plug-valve in connection with the steam-room in the boiler. The
engineer by this means can urge on the fires by blowing the steam
up the chimney, and thereby causing a partial displacement of the
air, which is filled up by the atmospheric air rushing under the fire-
bars and through the holes left in the furnace doors, providing the
large supply of oxygen so necessary for combustion. With high-
pressure engines the waste steam from the cylinders is blown up
the chimney in a manner similar to the blast-pipe of the locomotive
engine.
Funnels of large diameter are usually stayed internally with
round bar iron, to prevent them from getting out of shape in the
workshop or on carriage to the ship. For ships of war the funnel
is made telescopic, the top part sliding into the lower part. The
outside part, or lower portion, is formed conical at top, with a cor-
responding cone for the internal or top portion, fitted at the bottom.
Thus, when the top part is hoisted up, the inside cone fits into the
outer one, and the funnel is screwed hard up with set screws, swivel-
ling in boxes recessed in the funnel. The points of the screws bear
on an angle-iron, fitted round the outer portion. The top part has
likewise the shrouds for securing the funnel to the ship's side. The
mechanism for hoisting up the funnel is a worm-wheel and pinion,
with the necessary barrels, chains, and guide blocks. This gear
should, when possible, be fastened down to the top of the boilers,
or strongly bolted to the side plates of the bunkers, as the worm-
BOILERS FOR MARINE PURPOSES.
75
wheel is apt to jam in the pinion if the frame for it is not rigidly
secured. An outside air-casing must be carried up from the top of
the boiler, or dry uptake if so fitted, to about 8 feet above the deck,
for taking away the vitiated air from the stoke-hole, and protecting
the woodwork of the combings around the funnel from the great heat
radiated from the uptake. On the deck there is another casing, so as
effectually to keep the passage round the funnel cool. There are holes
all round at the tops of the casings, and likewise at the bottom, for
the thorough ventilation of the stoke-hole. The waste steam-pipe is
likewise made telescopic, the bottom part having a suitable stuffing-
box, through which the top part slides steam tight, the top part
having a stay, with collars on the waste-pipe, the stay being attached
to the top or sliding part of the main funnel.
The smoke-doors should be hinged to flat bars, fastened vertically
to the smoke-box. The doors should have an inside plate and an
outer one, kept apart from the door itself, but secured to it by
ferrules and rivets: the inner plate is to protect the door from the
fire, and the outer one to keep the stoke-hole cool. By this arrange-
ment a current of air passes freely between both the inside and the
outside plates. There are handles, fitted with a means of keeping the
door shut, so constructed that the sneck or snib presses the door for-
cibly against the hinge plates. The furnace doors are hinged so as
to cover the apertures formed in the front plates, thus doing away with
cast-iron frames, and are pierced with air holes, having the means of
regulating the supply of air to the furnaces. The ashpits are fitted
with dampers at front, hinged on a pin, having ratchet wheels and
pawls, for regulating the supply of air underneath the bars, or, by
shutting them, damping the fires. The manhole on the top of the
boiler should be cut in the most convenient place, and the door
secured on the outside with a bridge piece, strongly bolted. The size
of the manhole is usually 18 inches by 14 inches, which is sufficient
to allow a man of ordinary size to pass through for inspecting and
cleaning the inside of the boiler. Smaller doors are left in the
front plate of the boiler, between the furnaces at the top, of sufficient
size to allow a boy to pass through for scaling the furnace tops. All
the necessary doors must be fitted at the bottom of the boiler, for
raking out the sludge, the bolts for securing them being made so as
to draw up the door against the inside of the front plate of the boiler;
one large bolt, having a cross bar over the hole, is by far the best
plan for securing them.
76
MODERN STEAM PRACTICE.
Of late years many improvements have been made in connection
with steam boilers, with the view of increasing the economy of the
fuel, and thereby rendering the boiler a more efficient steam-gener-
ator. The loss due to emission of smoke may in many cases be
met by careful firing. Appliances known as mechanical stokers
have been introduced, whereby the fuel is gradually fed to the fur-
nace through a hopper arrangement in front, means being adopted
to work the coal to back of furnace. Another method of fuel feeding
has been recently tried, in which the coal is charged upon a mov-
able truck, which by gearing is pushed inside the grate and below
the fire-bars, the fresh coal is then lifted or pushed up below the
burning fuel, and thus partially cokes before being consumed.
Feed-water heaters are also used, by which it appears a consider-
able saving in fuel is effected. The covering of the boiler and
steam-pipes has also had much consideration, various non-conduct-
ing compositions being used; one of those recently tried is slag
wool or silicate cotton, partly made from blast-furnace slag; it is
applied either as a composition or in slabs curved to suit the surface.
Figs. 39A and 39B illustrate the most modern type of marine
boilers for compound engines, as supplied to the S.S. Parisian, built
by R. Napier & Sons, Glasgow, for the "Allan Line" of ocean steamers.
There are four boilers, each 15 feet in diameter, and carrying a
working pressure of 75 lbs. per square inch, a hydraulic test having
been applied, as is usual in such cases to double the working pres-
sure, viz. 150 lbs. per square inch. The shell plates are treble
rivetted in the longitudinal seams, and double rivetted in the cir-
cumferential seams. The furnaces are double butt strapped (see
A, A in Fig. 39 A on opposite page), and welded for a length of 10 inches
at each end. The stays B, B are 23%" diameter, and are spaced
14%" apart. The tubes are 3½" diameter and 7 feet long, arranged
vertically one over the other as shown in the figure. The total
heating surface of the four boilers is 15,176 square feet, and the
total grate surface is 540 square feet.
It will be seen from the dimensions on Fig. 39B that the
thickness of the plates, which are of iron, vary, the thickest part of
the shell being 1%", and the end plates from 5%" at the tubes
to 18" above these and where the stay rods are affixed.
3"
These boilers supply steam to three-cylinder compound inverted
engines working up to 6000 indicated horse-power, which are
illustrated and described under Marine Engines.
BOILERS FOR MARINE PURPOSES.
77

I
Οι
O
A
ooooo
Fig. 39A.-Vertical Section of one of the Boilers of the S.S. Parisian.

O
O
3-176
17′-9″
•
O
O
O
O
O
•
O
O
•
O
O
O
O
O
•
各
​O
O
O
•
O
O
O
•
Fig. 39B.-Longitudinal Section of one of the Boilers of the S.S. Parisian.
78
MODERN STEAM PRACTICE
THICKNESS OF PLATES, &c., FOR COAL BOXES.
Thickness of Side Plates,..
Do.
Do.
Do.
Corner Angle-iron,.........
Bottom,.
Stay Angle-iron,……….
Stayed every 3 feet apart.
8 inch.
3
16
I
1½ × 1½ ×
2 × 2 × 16
For Coal Stowage allow 46 cubic feet per ton.
PRIMING.
Impurities in the water used is no doubt the chief cause of
priming, and the evil is much increased by the want of proper
circulation. We are apt to crush into small space a number
of tubes, without ever considering how the water is to circulate.
around them. A continual ebullition goes on in all directions, the
globules of steam are hurried through and between the water spaces
in their passage upwards, and the water is allowed to fill up the
cavity as best it can. A simple experiment on a kitchen fire will
clearly point out how this frothing of impure water occurs. Take a
vessel partially filled with pure water, place it on the fire, and the
water will boil without flowing over; but fill the vessel half full of
potatoes, with just sufficient water to cover them, when the water
has boiled for some time a slight scum will be raised, and the water
having thus become impure from matter extracted, will eventually
overflow. This process is greatly accelerated by the small water
spaces between the potatoes, the water having little or no circulation
downwards. The tubes in a boiler fill up the water space in a
similar way, and when the globules of steam are shooting in all
directions there is no time for the water to circulate freely. It is a
good plan to confine the great ebullition to those parts where the
steam is more rapidly raised, by simply fitting circulating plates
between the tubes and the side of the boiler and other parts, thus the
space left between the circulating plates would be comparatively
free from ebullition, and the surface water in the boiler would flow
down and circulate upwards amongst the tubes. Were such plates
fitted loosely over the furnace crowns, allowing the steam to escape
freely at the top, the ebullition would be very great, the water circu-
lating rapidly between the plates and the furnaces would tend in
a great measure to prevent scale forming. The part mostly affected
by the want of good circulation is the bottom of the tube-plate at
#
TREATMENT OF STEAM.
79
the back of the boiler, and the great heat at this part soon cracks the
plate, if the scale that rapidly forms is not frequently removed. Of
course, where water from a surface-condenser is used, little or no
deposit is formed over the heating surfaces; but even with surface-
condenser water, it is found necessary to allow a slight film of
deposit to form, otherwise the corrosion that rapidly sets in would
corrode the plates very quickly. As we cannot prevent the water
frothing up when it is taken into the boiler in an impure state,
we must simply consider the best means to prevent the water priming
over into the cylinders. With a good height of steam-chest, and
with the steam taken from the highest point, the bubbles of water
will be broken up before reaching the top of the inside steam-pipe
in the boiler, and when a slotted pipe is carried along the top of
the boiler, perforated with a number of slits inch wide, should the
globules of steam and water reach that height, as they cannot pass
through the slits, they are broken up, liberating the steam, which
finds its way through the slits into the pipe, while the water con-
tained in the spheres falls down amongst the water in the boiler,
with the additional advantage that the steam is taken away directly
from over the surfaces where it is generated. However, when no
priming takes place, a certain amount of water will be carried along
with the steam; and when the steam-pipe is at one point, the atoms
are all converging to that point, and the mere mechanical friction
of the atoms of steam rubbing against one another tends to carry
water through the steam-pipe into the cylinders, therefore the steam
should be partially dried by an apparatus we will now explain.
16
TREATMENT OF STEAM FROM THE BOILER TO
THE CYLINDER.
Steam generated from ordinary boilers is far from being a pure
gas, properly speaking, it is quite dry and invisible. The vapour
blowing off from the safety-valve shows a transparent ring near the
orifice of the valve; this ring, however, soon widens, and mixing
with the cold atmosphere, takes the form of a misty vapour, highly
charged with watery particles; this vapour is soon dispelled, and
80
MODERN STEAM PRACTICE.
nothing but pure water falls to the ground in a gentle shower. Thus,
wherever the steam comes in contact with cold surfaces in its passage
to the cylinder, condensation takes place, and it is robbed of an
amount of heat, and consequently pressure, thus wasting much valu-
able fuel.
The saturation of steam with watery particles, however, is not
entirely due to condensation, as there are various other causes at
work; for instance, when the steam-room in a boiler is not of
sufficient height above the water in the boiler, the violent ebullition
that goes on has a tendency to surcharge the steam with water.
Again, if the steam is taken away from one end of the boiler, instead
of from immediately over the parts where it is generated, the same
result takes place, the atoms rubbing, too, against one another, in
flowing towards one point, has a great tendency to charge the steam
with water. Violent priming, whether from the want of circulation
of the water in the boiler, owing to defective construction, or by a
sudden change of water injected into the boiler, surcharges steam
with water to an aggravated degree. When the boilers, steam-pipes,
and cylinders are not properly clothed, condensation takes place, and
watery particles will be mixed with the steam to a large extent, thus
reducing its pressure.
Many schemes have been devised to superheat the steam in
marine boilers by the waste heat in the smoke-box, or uptake, with
the view of delivering it into the cylinder in a dry state. Many
of these superheaters have been fitted to boilers defective in con-
struction. Some authorities are of opinion that the best place for
drying the steam is in the boiler itself, drawing it from high steam-
chests and uptakes, thus the steam is taken away at a greater height
from the level of the water in the boiler, while the heated gases from
the tubes have time to act on the lofty uptake contained in the
steam-chest, and drying the steam sufficiently for all practical pur-
poses. In many cases it is not convenient to form lofty steam-
chests, and then other means must be adopted for drying the steam,
separate vessels, termed superheaters, being used for that purpose.
The steam dried by such contrivances generally receives 80° of
superheat above the temperature of the steam in the boiler, this is
considered, with fine lubricants, a good working temperature, that is
to say, steam of 60 lbs. pressure has 295° Fahr., thus the total tem-
perature will be 295° +80° 375° Fahr.; but it should be borne in
mind that the best oil or grease must be used as the lubricant, other-
=
TREATMENT OF STEAM.
81
wise the dry steam hardens the oil, to the detriment of the piston
and slide-valve rubbing surfaces.
Some engineers consider that when the steam is superheated,
it should be mixed with the steam in the boiler; little advantage
exists, however, in this arrangement, for it appears a very doubtful
proceeding to heat up the steam, and then rob it of a portion of
the heat by mixing it again with steam from the boiler. The main
thing to be studied is to give the steam a sufficient degree of super-
heat, so that in its passage to the cylinder it may not be cooled
down below the temperature existing in its primary state in the
boiler; thus steam in a dry state is passing
into the cylinders, whereas without some
contrivance for drying the steam in the
boiler, or in the superheater, an admixture
of steam and water presses on the piston,
tending to diminish the power and increase
the consumption of fuel.

Fig. 40.-Cylindrical Superheater.
The various forms of superheaters may
be classed just as are steam-boilers. The
plain cylindrical form has an outer shell,
containing a single large tube, the inner tube being stayed with rings
of angle-iron; where double round boilers are used, firing fore and
aft, the part fitting on to the boiler is bevelled, while
the other end that joins on to the funnel is quite
square; these superheaters, four in number, converge
to one point, to which a single funnel is fitted, the
bottom part of the funnel or the uptake being
bevelled to suit; this form of superheater is simply
effective, and easily constructed, while the scale can
be readily cleaned out, and as it lies at a consider-
able angle the heat acts better on the surfaces.

..
11

Some superheaters of this class, however, are placed
vertically, and it is an object with the designer to
arrange passages so that the steam travels up and
down within the superheater, time being required
to dry the steam thoroughly. The passages are
formed with plating rivetted vertically between the
inner and outer shells, one of these plates is rivetted
to the bottom and sides, another to the top and sides, and so
on alternately; but at the top and bottom alternately the vertical
Fig. 41.-Cylindrical
Superheater, with
division plates.
6
82
MODERN STEAM PRACTICE.
plates are not carried to the ends of the superheaters, an opening
being left at these points; thus between the inner and outer
shells cellular compartments are formed, the steam
coming in at the bottom of one cell travels upwards,
and then descends into another compartment, and so
on according to the number of compartments, until it
is finally carried away by the steam-pipe, the heated
gases in this arrangement acting on the inside tube,
the outside shell, and the lower end-plate, all of which
are contained within the bottom part of the funnel.

Superheater
Again, we have a vertical superheater of the cylindri-
cal class, but instead of one large tube passing through
it, a series of small tubes are securely rivetted to the
Fig. 42.-Tubular end-plates, thus forming a multitubular superheater;
again, time is required, so it is necessary to place
division plates, rivetted to the sides and one end, having an open-
ing at the other end, thus the steam being admitted at the top
passes downwards, flowing all round the small tubes, and then
upwards in the other compartments according to the number of
division plates fitted, until it passes into the steam-pipe to the
cylinder. Sometimes the multitubular type has the tubes lying
horizontally, and division plates so disposed that the steam from
the boiler enters at the bottom, passing through the small tubes,
then returning, and finally passing through the top rows, thus the
steam goes three times through, from the point where it enters
the superheater, at the bottom, to that point at the top on the
opposite side where it is taken away by the steam-pipe. In plan
this arrangement has the tubes at the central part, the tube-plates
being inclosed with a circular shell, and the tubes arranged in
vertical rows. At the middle and sides there is space left so that
the heated gases are not so much obstructed as when passing
between the tubes; this makes a very effective arrangement, and
may be reckoned a good example where time is required.
Many examples of tubular superheaters have been fitted directly
on the tube-plate, some arrangements having the tubes merely a con-
tinuation of the tubes in the boiler, the pitch of the tubes in the super-
heater being identical. With this plan time is sacrificed and surface
adopted; however, in some cases the tubes are laid the long way of
the smoke-box, having boxes at each end, one end in communi-
cation with the steam-space in the boiler, and the other with that of
TREATMENT OF STEAM.
83
the steam-pipe to the cylinder. In some instances three boxes have
been fitted to the superheaters, involving four tube-plates, the tubes
running right and left from the central box; the steam from the
boiler enters this centre compartment, passes right and left through
the tubes, and is taken away with separate steam-pipes at each end.
Sometimes the superheater forms part of the boiler; and for low
boilers for marine purposes this plan has certain advantages, the
tubes are arranged vertically, and are secured into tube-plates, run-
ning the entire length of the smoke-box, the lower tube-plate being
a few inches above the tubes in the boiler, while the top tube-plate is
placed a few inches from the top of the shell of the boiler. The steam
from the boiler enters the superheater through a number of small
apertures, these take a downward course; a division plate being
fitted, the steam passing this plate ascends, and is taken away by
the main steam-pipe; there are certain advantages connected with
this arrangement, though the main one simply consists in doing
away with a good deal of piping, as the steam from the boiler enters
the superheater directly. The great desideratum to attend to in
tubular superheaters is provision for cleansing them from the soot
in the smoke passages, whether arranged internally or externally;
some mode of access must also be provided to the steam space for
cleansing away the scale that rapidly forms.
To employ a large flat surface, giving time to the steam to be
thoroughly dried, is certainly the correct principle to be studied,
when superheaters require to be placed in small space, though the
complication entailed renders many arrangements of flat flue super-
heaters not at all to be commended in practice. Vertical flat flues,
similar in construction to the overhead flue boiler with U-shaped end-
pieces, and the plates flanged at the ends, for uniting them to the tube-
plates, all of which are inclosed in a suitable casing, properly and
securely stayed, with stay-bolts and ferrules, is an effective arrange-
ment of the kind; the heated gases pass through the elongated tubes,
while the steam is admitted at one end of the casing, and passes
between the spaces left betwixt the flues, and is taken away by the
steam-pipe placed on the opposite end of the casing. This plan of
superheater is expensive in first cost, and complicated in its many
parts in the event of repairing it and keeping the apparatus in
thorough working order. In all cases where separate superheaters
are used for marine purposes, a stop-valve and pipe must be fitted
for each boiler, for shutting off, or allowing the steam free access to
84
MODERN STEAM PRACTICE.
the superheater. One stop-valve is fitted to the superheater for
regulating the steam to the cylinders, while in connection with this
stop-valve and pipe there is fitted a stop-valve on each boiler,
having a pipe connected to the main steam-pipe, thus in the event
of anything going wrong with the superheating apparatus, all the
stop-valves connected to the superheater can be closed, and the
steam taken from the boiler in the usual manner. This will show
how much more preferable it is to form high steam-chests and up-
takes; thus complication is reduced to the minimum, while at the
same time the steam is effectively dried. Superheaters, in all cases
when made separate vessels from the boiler, should be fitted with a
safety-valve, of ample size; this is to prevent rupture, as, in case all
the stop-valves are shut, a certain amount of moisture, or even
steam, is in the superheater when the valves are closed, and this
would generate a highly-explosive dry gas, or steam proper, were the
safety-valve not relieving the superheater from the accumulating
pressure. In the absence of steam in the superheating vessels, the
injurious effect of the waste heat passing up the chimney acting
upon the dry plates and small tubes need scarcely be pointed out.
In concluding this brief sketch of superheaters, that have all been
practically tried more or less, it may be stated that for pressures of
60 lbs. per square inch in the boilers the simplest arrangement that
is found in practice to suit all requirements is a circular shell fitted
with an internal flue. The surface exposed, or total surface of the
internal flues, in this system is 13 square foot for every nominal
horse-power the engine is calculated for; but for low-pressure steam
the surface is generally I square foot for every indicated horse-power
the engine works to; or otherwise from 3 to 4 feet square per nominal
horse-power is reckoned amply sufficient for the superheating sur-
face, as usually arranged, for pressures varying from 20 lbs. to 30 lbs.
steam in the boiler.
We will now consider the different points to be attended to in the
arrangement for conveying the steam from the boiler to the cylinder.
With the view of keeping the steam as free as possible from watery
particles, as has already been discussed in the section on priming,
a pipe is fixed to the interior of the boiler, perforated throughout
its length with a number of holes, by which the steam is removed
from over the parts where it is rapidly generated. This pipe should
be fitted to all boilers, whether using superheaters or fitted with
ordinary arrangements. The use of the separator has also been
MANUFACTURE OF BOILERS.
85
explained, fitted to the steam-pipes, for retaining any moisture that
is carried along with the steam, more especially steam that has not
received a sufficient degree of superheat. The reader on turning back
to page 46 will find the use of the separator fully explained. As the
pipes are made of copper, which is a very good conductor of heat, it
is necessary to clothe them with felt, and then cover them over with
canvas, securely sewn together; the whole is then painted, to pre-
sent a neat and smooth surface. The steam is still further treated
in the cylinder by the use of a steam jacket encircling the cylinder
in all parts where radiation takes place; even the ends and the covers
of the cylinders are steam-jacketed, and are still further protected
with felt, covered with "lagging," the technical term for narrow
strips of wood that are firmly secured to rings of wood bolted to the
cylinder, ribs being cast on for that purpose. Thus it becomes
imperative that pipes and surfaces, exposed to external cold, should
be thoroughly protected to prevent condensation or reduction of
steam pressure. The boilers are likewise covered with felt and wood
lagging, and sheet-lead overall, to prevent radiation.
MANUFACTURE OF BOILERS.
In all branches of industry there are certain methods better
adapted for carrying on work than others, and although one maker
may adopt a very different method from another, they may be
equally successful in turning out as good work, although the one
may have expended more money than the other in doing so. Some,
for instance, adopt modern improvements, and their plant is of
modern make; the punching machine, for example, being superseded
by the multiple drilling machine, and no one can doubt for a mo-
ment that drilling the holes for the rivets is done without straining
the plates so much as with the multiple punching machine forcing
through three holes at once, even although the drilling machine may
be doing twenty holes at one time. The plating for boilers and
other work is now done with mathematical exactness; the distance
between the rivets for ordinary boilers, having 3/4 inch rivets for
securing the plates, is 2 inches between centre and centre, and
from the edges I inch to the centres of the holes; consequently
the plates should be ordered with even dimensions.
86
MODERN STEAM PRACTICE.
Some may say this cannot always be done, so as to give a boiler
of a certain diameter. We will only remark that if the plates will
not run evenly, an inch more or less does not affect the diameter
very much, as likewise the length of the boiler is not generally so
confined. The object of even dimensions is simply that when the
plates arrive they are at once taken to the planing machine to have
the edges planed, and then they are punched or drilled, as the case
may be, the punching machine being provided with a travelling
table, moved along by hand, the table having suitable stops, thus
the machine templates or sets out the holes and punches at one and
the same time. Now this could not be done if the plates were
ordered of uneven dimensions. Those who have not adopted this
plan for plating for all kinds of boilers cannot be aware of the
great saving effected. We have known working drawings going
into the workshop, and the boilers have been plated haphazard,
stock plates being kept for that purpose. We may at once note
this plan a complete barbarism. Plates should be ordered for
each boiler separately, and properly marked both on the drawing
and on the plates as delivered from the rolling mills, when they
should be assorted, and the workman then knows where to lay his
hand on No. I or No. 13 plate, as the case may be. By this rule
being duly attended to much saving is effected. Indeed, a prac-
tised eye can at once detect when boilers are plated haphazard
or regularly; and certainly it is not very pleasant to be told that
this or that boiler has not the same appearance, owing to the
irregularity of the plating as taken from stock; and great waste
occurs when plates require to be cut down to suit a particular boiler.
For all difficult boilers block models should be made, and all the
plates set out and marked, so that the workmen can see at a glance
what the work consists of, the model giving a better idea than a
drawing, and also standing more rough handling;—the drawing, in
some cases, never being required in the workshop.
All the plates should be ordered for planing the edges; 4 of an
inch is the regular allowance for doing so, not that so much is required
to be planed off, but at times the plates are not so square at the
corners as can be desired. This method of planing the edges saves
a great deal of chipping, and the joints are more easily caulked.
In plating the boiler care must be taken so that the flame does not
act on the edges of the plates. All joints should be so laid that the
flame passes over, and does not impinge against the end of the
MANUFACTURE OF BOILERS.
87
plate, and all the outside edges should be placed downwards; thus
the moisture freely runs down, and is not allowed to collect at these
parts, preventing the rapid corrosion that would otherwise set in.
The drawing should plainly show all the laps, to prevent the work-
men from plating the boiler incorrectly. The plates exposed to the
immediate action of the flame should be of the best description,
more especially in the crowns of the furnaces, where they must run
lengthways, and all the joints kept well
out of the fire. Sometimes the furnaces
are plated with butt joints and strips;
this is a good plan for boilers intended
to carry high-pressure steam. The end-
plates of rounded boilers are usually
attached and stayed to the shell with
angle-iron at the corners, having three
or more flat plate-stays, rivetted be-
tween two angle-irons at the ends
and top, dividing the surface to be
stayed equally. When the furnaces
are inside of the boiler the angle-iron
for joining the furnace with the end-
plate is placed inside, at the furnace
end, and outside of the flue-plates at the
extreme end; but should the furnace be underneath the boiler the
flues must be joined to the end-plates with angle-iron outside of
the flues, or, in other words, inside of the shell. The water space
underneath the boiler in this case will be more than in the former
arrangement, with 2½ inches breadth of angle-iron, not less than
5 inches between the flue-plates and the outside shell; and where
two furnaces or flues are adopted, the same space should be between
them: when stronger angle-iron is used the distance may be the
same, but the angle-iron will require to be flattened or cut away
at that point.


Fig. 43.-Plate-stays.
Sometimes boilers are ordered to be flanged in all the corner plates.
When so specified, all the flanges should have a bold radius at the
corners, not less than 2 inches: this makes a neat piece of work, and
the strength of the boiler is materially increased. Water spaces,
having flat sides, should be stayed together with 34 inch screwed
stays, tapped into both plates, and rivetted or fitted with nuts and
washers outside, as occasion may require, the distance between
88
MODERN STEAM PRACTICE.
the stays being regulated by the steam pressure used. For strength-
ening the flues when they are of extra size sometimes angle-iron
Flue Ring.
and manufactured hoops are introduced at the joints
(see sketch on page 26). This plan answers well
where deposits do not form rapidly; and although
Fig. 44.-Flat Iron large flues, whether oval or circular, are not at all
desirable, they can be strongly stayed with conical
tubes, having the water inside of the tubes, which are most efficient
stays, and give extra heating surface, and no boiler having large or
flat flues should be without such a means of support. The tube-


Fig. 45.-Conical Water Tube-stays.
stays are so made that the bottom parts with flanges can go through
the top holes; thus they can be fitted to existing boilers cheaply.
Such a system of staying must tend to decrease the number of


O O O
о
GÐ GÐ CH
Fig. 46.-Flat Fire-box.
boiler explosions; but on no account should a boiler so fitted be
tampered with. For staying the end-plates of round boilers
T-irons are sometimes introduced, having long rods of round iron
passing from end to end of the boiler, and jointed with pins and
MANUFACTURE OF BOILERS.
89
cotters to the T-irons. With boilers having hemispherical ends it is
quite evident that no stays are required. Flat fire-boxes (see page 88)
for general purposes, and similar in construction to the locomotive
type, should be well stayed; the inside fire-box can be made circular
at the top, and for moderate pressure the flat sides are only stayed
to the inside fire-box, with 3/4 inch screwed stays, rivetted on the out-
side, the distance between the squares being 6½ inches for 50 lbs.
per square inch, to 44 inches for 100 lbs. steam pressure per square
inch. The plates are all flanged at the corners, but the fire-box is
sometimes united to the outer casing, with angle-iron at the bottom.
The short flange pipe, to form the furnace-door case, strongly stays
the fire-box at that part.
As we consider that this subject closely affects the interests of
steam users, we append the following from a report presented to
the National Boiler Insurance Company:-"A large number of
the boilers proposed for insurance are so weak in construction
that some general remarks, based on the extensive experience of
the construction and working of all kinds of steam boilers, will
doubtless be found useful to many owners and makers. Of the
numerous varieties none are more generally used than the Lanca-
shire, or the cylindrical two-flued, and the Cornish one-flued boilers,
and where these are well constructed, properly fitted up, and care-
fully attended to, their performance is generally satisfactory. There
are various modifications of these forms, some of which are valuable.
In designing such boilers excessive length, as compared with the dia-
meter, should be avoided. Long boilers strain considerably, and
frequently give great trouble by leakage at the rivetted seams. A fair
proportion is when the length is about three-and-a-half times the dia-
meter. The staying of the end-plates, and the attachment of the flue-
tubes to the ends, should be so arranged that the tube may expand
freely, unless there be some special arrangement in the form of the
flue-tubes to attain the same object. Many boilers, otherwise well
made, have given considerable trouble by leakage and fracture, owing
to the severe strains of unequal expansion to which their rigid con-
struction exposed them. In some of the boilers inspected the ends
were so heavily stayed, and so rigid, that considerable leakage and
occasional fracture at the ring seams of the lower part resulted. In
others the staying was so slight that the ends were bulged outwards,
and serious risk of explosion thus occurred. Flue-tubes should never
be stayed to the shell, but be attached at the ends only. Many boilers
90
MODERN STEAM PRACTICE.
have given serious trouble through being thus stayed. The shell
should be made quite circular, and the longitudinal seams, which
should break joint, be so arranged that when the boiler is set all
those below the water-line may be accessible for examination in the
flues, and be clear of the brick seatings. Many makers now double-
rivet these seams, thus materially increasing their strength, and, when
the work is well performed, reducing liability to leakage. Flue-
tubes are now constructed in various ways, some makers preferring
to use thick plates not strengthened in any way, whilst others prefer
comparatively thin plates, but flanging them at the ring seams, or
by welding each ring of plates and connecting them by solid T-iron
hoops, form a much stronger and more reliable flue-tube. The
liability to leakage, fracture, and excessive expansion is thus much
reduced, as the heat is more freely transmitted through the thin
plates. The cross-tubes and water-pockets introduced by some
makers in that part of the flue-tubes beyond the furnace bridge are
of great value, chiefly from the manner in which they improve the
efficiency of the heating surface by the diversion and breaking up
of the current of gases, whilst they much increase the strength of
the tubes to resist collapse. All large tubes exposed to high pres-
sure should be strengthened by some of the means described. Where
the tubes are formed with the ordinary lap-joints the longitudinal
seams should break joint, as a tube thus made is much stronger than
where those seams are in a line; and at the furnace end all longitu-
dinal seams should be below the fire-grate level. The plan of form-
ing tubes with the plates longitudinally in narrow strips is very
objectionable, as the tubes cannot be made so circular, and the
seams above the bars are injured by the action of the fire, whilst
such tubes are much weaker than those made in the ordinary man-
Multitubular boilers should, as far as practicable, be so con-
structed that every part of the interior may be accessible for cleaning
and examination; and it would be a great improvement if those of
portable and locomotive engines were so constructed that the tubes
could be drawn out without difficulty, so as to allow occasional
inspection of the internal surface of the plates. External flues are
necessary to stationary cylindrical boilers of this class, otherwise
the lower seams are strained, and become leaky through excessive
unequal expansion of the boiler. Plain cylindrical externally fired
boilers, with egg or saucer shaped ends, are preferred by some
owners, chiefly on account of their simple form. Such boilers can
ner
MANUFACTURE OF BOILERS.
91
never work so safely as a properly constructed internally-fired boiler,
as they are so liable to fracture at the seams over the furnaces,
through the excessive alternate expansion and contraction to which
they are exposed. The application of stout longitudinal stays would
add materially to the safety of such boilers. A variety of cylindrical
vertical boilers are used in various iron-works. These boilers are
generally heated from the puddling or similar furnaces, the heat
first entering the external flues, and passing thence by an internal
descending flue-tube to the chimney. They are especially liable to
starting and fracture of the rivetted seams opposite the furnace
necks, owing to the intense heat at that point; and where the feed
water deposits much sediment the solid plate is sometimes fractured.
To avoid this liability the part referred to should be protected by a
screen of brickwork, or the boiler set at a higher level; the brick-
work may be so arranged as to spread the heat before it reaches the
boiler. The bottoms of these boilers are frequently quite inaccessible
for examination, and serious corrosion may go on unknown to those
in charge. If the boilers were supported by brackets at the side, or
by wrought-iron plate standards rivetted to the bottom, so that a
thin wall of brickwork would suffice to form the flues, the condition
of the plates could be occasionally ascertained without much diffi-
culty.
"As the safety of boilers depends so much on the sufficiency and
condition of their fittings, a few remarks thereon will be useful. It
is well to have two safety-valves to each boiler, as a check upon each
other; one of them should be a dead-weight valve, loaded externally,
and the other a lever-weight valve, or a compound valve, which
would allow the steam to escape, if the water were allowed to fall
below the proper level. Safety-valves are frequently met with, the
levers of which are of such length, that the usual working pressure
for which the boiler was made would be much exceeded if the weight
were fixed at the end of the lever. The weight should always be
calculated and adjusted to hang at the end of the lever. All boilers
should be provided with correct pressure-gauges for the guidance of
the attendants. The glass-gauge is undoubtedly the best and most
reliable water-gauge, and it is a good plan to attach two gauges to
each boiler. Where floats are used there should be two, one of
them fitted with an alarm whistle. Boilers with internal tubes should
always be fitted with glass-gauges. Fusible plugs should be inserted
in the furnace crowns of all internally-fired boilers. The feed regu-
.92
MODERN STEAM PRACTICE.
lating valve, which may be constructed to act also as a back-pressure
valve, should always be placed at the front end of the boiler, within
the reach of the attendant, and where boilers work in connection,
each should have a back-pressure valve attached. The feed water
should be delivered a few inches below the surface of the water in
the boiler, and above the level of the tube crowns, and in a horizontal
direction, or by means of a horizontal perforated pipe. Where the
feed water is delivered near or at the bottom of the boiler, it cools
and contracts the lower plates, whilst those of the upper part are
heated and expanded by the steam, frequently causing fracture at
the ring seams at the lower part of the shell. The feed water should
always be heated before it is forced into the boiler. The blow-out
tap at the bottom of the boiler should be so placed that it may be
examined at any time, so that any leakage occurring, it should be at
once noted; valves should never be used, double-gland taps made.
altogether of brass are far preferable. Stout seatings with planed
joint faces, suitable for each fitting, should be rivetted to the boiler.
All manholes should be strengthened by a faced mouthpiece, rivetted
to the boiler, so that the joint may be easily and well made, and
leakage and corrosion avoided. Steam domes are unnecessary in
stationary boilers; a perforated pipe placed in the upper part of the
steam-space is quite as efficient to prevent priming, and the boiler
is not weakened. Where domes are preferable, they should never
be of large diameter, and the shell plates inside them should not be
all cut away, that is to say, the hole should be strengthened with
strips left in the plate. The setting of stationary boilers should
always be intrusted to a man of experience. When boilers are
about to be set, special care should be taken to thoroughly drain the
ground, that no dampness may exist in the flues to cause corrosion
of the plates. All the flues should be quite large enough to allow
a man to pass through, so that every part may be accessible for
repairs and examination. Midfeather seatings are very objection-
able, and no boiler should be so set, except those of very small dia-
meter, and in such cases, thick but narrow iron plates should be
placed on the top of the brickwork to protect the boiler. Cylindri-
cal boilers internally fired should be set on side walls, the boiler
resting on fireclay blocks made for the purpose, and so shaped that
when built in place the bottom of the side flues may be much lower
than the point where the boiler rests on the blocks. If the blocks
be properly fitted to the plates, that the bearing thereon may be
MANUFACTURE OF BOILERS.
93
equalized, the total breadth of both side walls, where in contact with
the plates, need not exceed I inch for every foot of diameter of the
boiler. The top of the side flues should be level with the crown of
the flue tube. All boilers should be roofed over to protect them
from external moisture, otherwise the sides in contact with the flue
brickwork will be weakened by corrosion. Where flues are properly
arranged as described, no serious corrosion could exist in the seatings
undetected by a skilled inspector. The laws for the prevention of
smoke are now being enforced in many districts, but boiler-owners
should be cautioned against too readily adopting any form of appar-
atus which may be pressed upon their notice, as many are unneces-
sarily complicated and expensive.
“It frequently happens that good boilers are injured and serious
risk is incurred through neglect and carelessness. Where the feed
water contains much sediment, and no cleaning apparatus is in use,
frequent internal cleaning is indispensable, or the plates may become
overheated and injured, whilst the efficiency of the boiler is reduced.
The external flues are in many cases allowed to become almost
choked before being cleaned, and the boiler plates so thickly coated
with soot, that a wasteful consumption of fuel is the result. Some firms,
on the other hand, clean their boilers thoroughly about once a month,
and are thereby considerable gainers, as the efficiency of the heating
surface is retained, whilst any defects are at once discovered and
made good, which, if neglected, might entail expensive repairs, or
even lead to serious disaster. When boilers are being restarted after
stoppage, they should be heated very gradually, so as to avoid, as
much as practicable, the severe strains of unequal expansion, and
when at work the feed supply and the firing should be as steady and
regular as possible. Frequent and extreme alterations of pressure,
especially with high-pressure boilers, or irregularity of any kind, is
most objectionable, and sometimes really dangerous."
We consider the foregoing remarks are well worthy the consider-
ation of steam users, although we do not entirely agree with the
writer in limiting the length of land-boilers to three and one half
times the diameter; and we do not advocate too thin plates for
flues, even though stayed with hoops, although the flues are thereby
strengthened; but entirely agree with him that conical water tube-
stays are invaluable for staying the flues, as deposit is not liable to
form, as is the case with the hoops. We have known many instances
where deposits have rapidly formed at the roots of the hoops,
94
MODERN STEAM PRACTICE.
thereby tending to injure the plates, by a thick coating, through
which the heat cannot effectually act on the water, or, as it were, the
water cannot keep the plates sufficiently cool and in proper working
condition. This heating of the plates, whether from violent priming,
or from carelessness in the attendant allowing the water to fall below
the crowns of the furnaces, is the main cause why efficient steam-
boilers at times explode. As already stated at page 32, steel plates
are now being used for boilers, a reduction in thickness being
thereby effected of about 20 per cent., and on the whole weight of
the boiler about 10 per cent.
THE REGULATION OF STEAM BY THE SLIDE-VALVE,
AS APPLIED TO LAND, LOCOMOTIVE, AND MARINE ENGINES.
The reciprocating motion imparted to the piston of the steam-
engine is caused by the steam acting alternately on the top and
bottom of the piston; passages, or ports, as they are technically
termed, being formed in the cylinder to admit the steam: these ports
having a valve so arranged as to admit the steam above and below
the piston alternately, with means of allowing it afterwards to escape
into the atmosphere, or into the condenser, as the case may be. The
valve in its original form was simply an oblong box of cast-iron,
open on the front or face, having a flange all round, this face sliding
on a corresponding part on the cylinder, both being accurately faced
up, and made perfectly steam-tight, reciprocating motion being im-
parted to the valve by a simple arrangement similar to the crank
and connecting-rod for the piston. This valve, from its peculiar
sliding action, rubbing against a corresponding face on the cylinder,
is termed the slide-valve. The older valve arrangements admitted
the steam during the entire travel or stroke of the piston; there were
three ports, two in the cylinder, one at the top and bottom to admit
the steam into the cylinder, and a central one outside the cylinder
for the exhaust or waste steam from it to escape into the atmosphere,
or into the condenser, if so fitted. When the valve was at half
stroke, the steam-ports were covered, the valve face for doing so
being the exact width of the ports, that is to say, the steam ones.
It is quite evident that at this position the piston must be either at
the top or the bottom of the cylinder, and as the crank-pin for the
piston rotates round a fixed point, similar to the crank centre for the
REGULATION OF STEAM.
95
slide-valve, the former drives the shaft that gives motion to all the
minor details, and as the slide-valve must be opened and shut as the
crank-pin travels from one end of its path, in a line with the cylinder,
to the other end, it is quite evident that the centre, or pin, for the
slide-valve must be at right angles to that of the crank centre for the
piston; or, more correctly writing, with the length of the eccentric
rod as the radius, taken from the centre of the engine shaft, on a
horizontal line, sweep the path of the centre of the eccentric, and the
point intersected on the circle is the position of the eccentric centre.
When the crank-pin is at the commencement of the IN stroke, or
when the crank is moving towards the cylinder, at this position the
centre will be above the horizontal line; but should the crank be
moving on the OUT stroke, the centre of the eccentric will be below
the centre line of the engine.
·
It is quite apparent from the foregoing that when the crank-pin
has travelled one half of its stroke that the valve will be full open;

B
IN
Crank Path
IN
12 1/4 OUT
YOUT
E
Fig. 47.-Original form of Valve without Lap.
A, Commencement of the IN stroke. B, The point on crank path at half stroke. c, Centre of
eccentric at the commencement of the IN stroke. D, Centre of eccentric at half stroke of
piston. CE, Length of the eccentric rod. F, Commencement of the OUT stroke.
and that when the crank-pin has travelled to the end of its path,
or one half of the circle delineated by the crank centre, that the
valve has returned, and covers the steam-ports exactly. At this
position the crank-pin centre commences describing the other half
of the circle or path, the piston is returning, and the slide-valve opens
the steam-port for it to do so, at the same time the exhaust is
becoming free, the steam which has acted on one side of the piston
is escaping into the atmosphere as for non-condensing engines, or
into the condenser, as with the low-pressure type; thus the steam
acts alternately on the top and the bottom of the piston. It will
be observed that the full pressure of the steam from the boiler was
admitted into the cylinder the entire length of the stroke of the
piston; this was wasteful, so it became expedient to admit the steam
96
MODERN STEAM PRACTICE.
for only a portion of the travel of the piston, or, in modern phrase-
ology, "cutting off" the supply, the “cut off” being one fourth, one
half, and so on, as might be determined on, the remainder of the
stroke of the piston being actuated by the expansive force of the
steam in the cylinder. So it was found that by adding a little more
width to the slide-face, keeping the opening in ports by valve the
same area, and making a new eccentric
to suit the required amount of cut off,
that the economical duty of an engine
was greatly improved. This addition to
Fig. 48.—Valve with Lap. Vertical lines the face of the slide-valve is termed the
show the outside lap.
lap of the valve, or outside cover. Again,
in high-speed engines it is found advisable to give the valve an amount
of lead or opening before the piston reaches the end of the stroke;
this is required to check the piston at the termination of each stroke
by cushioning the moving mass gradually; thus the piston is brought
to a momentary stand-still by the steam acting upon it directly from
the boiler. It will thus be obvious that a piston of great weight and
high velocity will require more lead or opening by valve than a
piston of less weight, travelling at the same velocity; or, on the other
hand, a much less piston, having a greater speed, may require the
same lead as the heavy piston moving slowly. Were very little
lead adopted in such cases, the moving mass being suddenly stopped
at the termination of each stroke, a succession of blows would be
imparted that eventually would damage the machine, and the lead
is simply introduced to prevent this occurring, and to secure the
earliest possible admission of steam, so as to obtain a large port area
early in the stroke. The inside edge of the valve face should just
cover or be in a line with the port, so that the exhaust is open at
the commencement of each stroke a linear distance equalling the
extent of the outside lap plus the lead; by this means the opposite
end of the cylinder, or rather the piston, is relieved from the steam
pressure, and the condensation fully established before the steam is
admitted into the other end of the cylinder.
In proportioning the slide-valve of the steam-engine, the lead of
the valve must be duly considered, a little more opening of port by
valve greatly affecting the lap or outside cover, as likewise the
length of the eccentric rod must be taken into account; as a rule,
with a proper length of eccentric rod of not less than six times the
throw of the eccentric, the versed sine of the chord contained by

REGULATION OF STEAM.
97
the arc, or travel of the eccentric centre, equals the opening of valve
minus one half of the lead. This may be taken in all cases to be
practically correct when the valve is worked by direct means from
the eccentric, but when levers and rocking-shafts are interposed
between the eccentric and the valve, the versed sine will be more
or less, as the case may be; thus supposing the eccentric rod lever
is longer than the one on the rocking-shaft for the valve, the versed
sine must be greater than for a direct motion, and vice versa; but
in all cases the throw of the eccentric, or the circle described by
the eccentric centre or pin, the lap of the valve, &c., must be found
in the first place to suit the cut off in the cylinder, as for direct
motion, and the levers proportioned accordingly.
Sometimes the valves for land-engines are made double-ported;
this class of valve is simply adopted to reduce the "throw" of the
eccentric, and secure rapid admission and cut off for the steam;
thus with ports of the same length as for single-ported arrange-
ments, we can, by having double or more ports, increase the area
for the entrance and exit of the steam,-a matter of importance
when a high rate of piston-speed is adopted.
When the valve is made large, it is necessary to relieve it from
the steam-pressure that tends to force it against the cylinder face.
There are a variety of plans for doing so: some engineers introduce
a piston working in a short cylinder, placed in the valve-casing
cover, connecting the piston to the valve by means of a vibrating
link; by this plan it is lifted as it were off the face, thereby reduc-
ing the friction, as the valve is partly suspended, and consequently
more easily moved. Others have introduced a flexible plate, con-
necting it to the valve in like manner, the spring of the plate acting
in a similar way as the piston arrangement; both are acted on by
the steam in the valve-casing, pulling the valve from the face, of
course, according to the amount of area exposed. However, such
arrangements are not to be relied on, and the end in view is attained
by simpler contrivances. The usual method, now in extensive use,
is by recessing two rings in the valve-casing cover, and pressing
them against a planed face, on the back of the slide-valve, by a
number of set screws, placed around, central with the recess; these
set bolts press against a ring of iron in the first place, then a plaited
gasket is interposed between this ring and the brass ring, which
presses on the back of the slide-valve, thus making the area covered
by the ring perfectly free from steam; the valve is by this means
ކ
7
98
MODERN STEAM PRACTICE.
relieved of much of the steam-pressure. A small pipe is introduced
through the valve-casing cover, in connection with the eduction-pipe
on the cylinder, thus any slight leakage of steam between the ring
in the recess and the valve is taken over into the condenser when
so fitted.
Other engineers have constructed the valve as a hollow frame,
having merely sides; the back in this arrangement being fitted
with a narrow piston-ring edge, having springs to keep the valve
to the face on the cylinder, and also to press the piston-ring against
the back of the valve-casing or the cover. This is certainly a
refinement, and so long as the rubbing surfaces remain steam-tight,
the plan is to be commended, as it is impossible such a valve, under
any circumstances, can have any more back-pressure than merely
the rubbing surface that is not covered by the piston-ring; but in
the event of leakage between the rubbing surfaces, the plan is not at
all to be desired, as the vacuum would be impaired, and great waste
of steam occur. Therefore, when it can be conveniently applied,
the plain ring system appears best, screwing the ring against the
back of the valve, as such a plan can be adjusted at any time with-
out breaking a joint, the set bolts being simply screwed into tapped
holes in the valve-casing cover; it must be borne in mind, however,
that the valve-gear must be proportioned to meet the full pressure
on the valve, as at times the best arrangements will get out of
order. When cast-iron surfaces are adopted, one-sixth of the total
pressure on the valve may be taken for calculating the strength of
the valve-rod and adjuncts, that is to say, if the faces are in good
working order, and the lubrication properly attended to.
The position of the valve next claims attention. In all cases
where practicable, it should be placed on its edge, so as to drain
or run off moisture or water that may collect when the engine is not
working, a small valve being fitted to the casing for running it off;
thus the faces are kept as dry as possible, preventing the corrosion
that would otherwise set in.
The reciprocating motion imparted to the valve is usually obtained
by means of a simple eccentric, although cam arrangements at times
find favour. The eccentric wheel or sheave has both a rotatory and
reciprocating motion, its action is somewhat the same as a pin re-
volving around a fixed centre, such as the main crank-pin of the
steam-engine; in fact, a plain crank and pin is often used instead of
an eccentric; but when the line of eccentric or valve-rod cuts across
REGULATION OF STEAM.
99
the engine-shaft, it becomes imperative to use an eccentric sheave,
over which is placed a loose strap, to which is attached the eccentric
rod; thus the eccentric sheave revolves inside of the strap, and the
former being firmly attached to the

a
main engine-shaft, communicates
reciprocating motion to the valve
and its adjuncts; the jointed end
of the valve having suitable guides,
so that the valve-rod moves in a
straight line. To set out the ec-
centric, we will suppose the dia-
meter of the engine-shaft is given,
and consequently its centre, which
we will term A; draw a straight
line through the centre of circle
delineating the engine-shaft, and
on this line set off A B; this we will
name the crank of the eccentric, the
point B denoting the centre from which the eccentric sheave is
described; the distance from A to B equals the outside cover, or lap,
plus the full opening of the port by valve; then set off a proper
thickness of metal for the eccentric sheave, around the shaft, and
from the point B describe a circle touching the periphery of the
circumscribed thickness around the shaft, and the circle described
is the full size of the eccentric sheave; thus the basis is given for
constructing the eccentric motion.
Fig. 49.-Eccentric Sheave.
A, Centre of engine-shaft. B, Centre of eccentric.
EF, Thickness of metal round shaft.
CD equals A B, multiplied by 2.
The eccentric is certainly not the best method of imparting motion
to the slide-valve, as cams give a better cut off; but considering the
great number of revolutions per minute many engine-shafts revolve
at, it is the only motion that gives satisfaction, being regular and
easy; whereas with high speeds the cams impart a succession of
blows that would soon shatter the machine, and the noise would be-
come intolerable. However, some steam-engines of the fire-engine
class have neither eccentric nor cam motion, but simply an arm
keyed on the piston-rod, having an oblong eye, working on a twisted
flat bar of iron, thus imparting motion to the slide-valve; an arm is
fixed on the end of the twisted bar for taking the valve-spindle,
a short link being interposed between, with the necessary pins,
guides, &c.
Having now considered some of the leading features demanding
Uor M
100
MODERN STEAM PRACTICE.
thought in designing the slide-valve gear, attention must be drawn
to the beautiful link-motion, as first applied to the locomotive,
in its general application to land-engines, more especially to that
IN AI
ουτ
E


+
D
Valve
Rod
Fig. 50.-Link-motion.
A. Centre of crank-pin at the commencement of the IN Stroke. B, Centre of forward eccentric.
c, Centre of backward eccentric. D, Centre of suspension in link. E, Lifting arm. F, Slide-
rod block.
class of engine requiring skilled men as drivers, or those techni-
cally termed engine-tenters. In days long gone past we have often
handled colliery winding-engines, and it required a great amount
of patience and skill to do it properly; but now it is done in an
easy and satisfactory manner by the double eccentrics and link-
motion, so that with an attentive man there is no fear of drawing.
the cage, with probably a living load, over the pulleys on the pit-
head frame, as he can reverse or stop the engine with a single
movement. Indeed, the numerous small engines handled in this
manner every day lifting heavy weights quickly and under perfect
control, lead many inquirers to consider that the double eccentrics
and link-motion is the greatest improvement yet contrived in the
mechanism for actuating the slide-valve.
There has always been an amount of mystery in explaining the
action of the double eccentrics and link, while all allow that the
common eccentric, or crank movement, is very easily comprehended.
The latter is set to give a movement of the main crank of the engine
in the particular way required; the eccentric centre being fixed, the
crank-pin could by no means travel in the contrary direction per se,
but by placing a twin-eccentric on the engine-shaft alongside of the
other one, with the centre directly opposite, in relation to the main
crank, the backward movement is obtained; then by connecting
the extreme ends of the eccentric rods to a slotted link, so that
this link can be moved up or down at pleasure, bringing the forward
Maou
REGULATION OF STEAM.
ΙΟΙ
or backward eccentric rod in a line with the valve-spindle, we have
the power of moving the crank IN or OUT, as while one eccentric
is in gear the other is simply doing nothing; they have joined
hands, and are ready at a moment's notice for either going forwards
or backwards, or by lifting the rods, and placing the link at mid-
way between the centre of the eccentric rods, on a line with the
valve-spindle; thus no motion is imparted to the valve, or but a
trifle, and in this position the steam is shut off from the cylinder.
In fact, the motion of the one eccentric is identically opposed to
that of the other, and they can only move in contrary directions
to open the ports as required; and being linked together, it is im-
possible that the one can do the duty of the other, or that both
combined can ever fail in making the main crank of the engine
travel in the direction required. When the link is down, the top
eccentric may be named the driver (as in the locomotive) for the
forward motion; but when the link is raised, the bottom eccentric
rod becomes the driver, while the top rod simply moves to and fro
along with the link which oscillates on the pin and block on the
centre line of the valve-rod, reciprocating motion being imparted to
the valve by the forward or backward eccentric, as the case may be.
The radius of the link is found by placing the valve and adjuncts
at half stroke, and the distance from the centre of the pin, for taking
the valve-block, to the centre of the crank-shaft is the radius of the
link, all the other dimensions or lengths being calculated accordingly;
the point of suspension of the link is generally on this arc, described
by the radius of the link, placed midway between the eccentric-rod
ends, the distance between the eccentric-rod ends being usually
three times the throw of the eccentric. When the link is drawn
half up, the lifting arm being level, the suspending link should be
nearly vertical, so as to equalize the motion; there are various
methods of holding the link in position, which will be treated in
detail further on.
The slide-valves for compound engines are so arranged, that two
valves, fitted to one casing, is sufficient, one at the top and another
at the bottom of the high-pressure cylinder, the port at the top and
bottom admits the steam into the high-pressure cylinder, the next
port is in communication with the passages for the low-pressure
cylinder, while the third, or middle ports, are in communication
with the condenser; thus there are three ports at the top, and the
same number for the bottom, of the high-pressure cylinder.
102
MODERN STEAM PRACTICE.
The cylinders are arranged side by side on the centre line of the
engine; the stean, after doing duty on the top of the small or
H
5
L
H
high-pressure piston, expands to the bottom of
the low-pressure piston, and then passes into
the condenser; steam is also admitted to the
under side of the small piston, from there to the
top of the large piston, and then into the con-
denser; two long ports or passages are cast in
the low-pressure cylinder, and there is a belt
cast around the high-pressure cylinder, fitted
with a pipe leading to the condenser. Such an
arrangement, designed by the author, was fitted
to a pair of engines for driving the machinery
at the Royal Gun Factory, Woolwich. The
valve gear was simply a crank-pin fitted to a
cast-iron disc-plate; on the pin was secured a
three-cornered cam, described from the centre
of the disc-plate, one cross shaft driven by
bevel wheels and shaft off the crank
shaft, suited for both engines. This
class of engine requires no cover on
the valves, consequently the length
from the centre of the disc-plate to
the pin or centre of the cam is ex-
actly the width of the exhaust-port
into the low-pressure cylinder.
This cam-motion opens the ports


Fig. 51.-Valves for High and Low Pressure
Combined Engines.
AB, Throw of the cam. c, Passage to condenser.
H, High-pressure ports. L, Low-pressure ports. quickly, while the valve hangs, as it
were, at the top and bottom of the
stroke. With coupled engines the cams are of course set at right
angles to each other, and as the weight of the valves is considerable,
they are balanced with a weight, having a lever and links connected
to the valve-spindle. There was no hand-gear, as factory-engines.
rarely require to be moved by hand, more especially when set at
right angles to each other.
The slide-valve for the locomotive-engine differs very little from
land-engines; but certainly the locomotive type has arrived at a
higher state of perfection than what is usually seen in engines for
ordinary work. The various schemes for working the slide-valve
of the locomotive, and many arrangements have been tried,-have
REGULATION OF STEAM.
103
•
resulted, at this date, in the universal application of the link-motion,
with double eccentrics, as first practically introduced by the Stephen-
sons.
However, there are a variety of link-motions; with some the links
are curved, while others have them quite straight. Referring to
those most in use, namely, those with the curved link, attention
must be drawn to the various plans adopted for connecting the
eccentric rods to the link. Some arrangements have lugs forged on

Fig. 52.-Locomotive Link-motion.
w, Weigh-shaft.
the link, within, and others without, the centre line of the link for con-
necting the eccentric rods (Fig. 52); other arrangements have no lugs
whatever, but merely a plain link, having the eccentric rods connected
to the ends, on the radius line of the link (Fig. 53), this plan neces-`
sitating the eccentrics to have a greater throw than in either of the
two former arrangements. Some links are constructed of two side
plates, with distance pieces, the eccentric rods being placed between
them; while in other arrangements the link is a solid bar of iron,

Fig. 53.-Locomotive Link-motion.
w, Weigh-shaft.
with the eccentric rods at the top and bottom on the centre line of arc,
described by the link. Then, again, the mode of lifting and suspend-
ing the link is by a lever and rod, the point of suspension on the
link is on the arc described by the radius line, and placed half way
between the centres of the pins for the eccentric rods; thus the link
and eccentric rods are raised or lowered simultaneously. With other
arrangements the link is not lifted, but merely oscillates to and fro
104
MODERN STEAM PRACTICE.
on a pin and suspending-rod, having a fixed centre at end on which
the arm oscillates; this arrangement is complicated, as a movable

W
Fig. 54.-Locomotive Link-motion.
w, Weigh-shaft.
rod must be interposed between the link and the valve-rod, with the
necessary lifting lever and rod to raise or lower it as required to suit
the forward and backward motion of the engine (Fig. 54).
Again, some link-motions differ entirely from the foregoing, the
link oscillating on centres, on the guide-bar for the valve-rod, sup-


Fig. 55.-Locomotive Link.
ported close to the link, while the eccentric rods are connected to
the sliding-block; this arrangement admits of the boiler being placed
lower down, as the link requires less head room; the link-block is
of increased length to insure steadiness; and as the reversing lever
supports only the eccentric rods and link-block, the slide-valves are
more easily handled, although all can be so arranged with counter-
weights to ease the labour in reversing (Fig. 55).
The great value of the link-motion not only consists in ena-
bling us to control the movements of the engine, but it is like-
wise admirably adapted for cutting off the steam at any portion
of the piston's stroke, thus working expansively without the aid
of an additional valve and mechanism, and also simplifying the
REGULATION OF STEAM.
105
machine, for undoubtedly all motors, especially those travelling
at such high speed as the locomotive-engine, should be as simple
as possible.
The means adopted for keeping the link in position, to suit the
grade of expansion that is required, is effected by placing a lifting arm
on the weigh-shaft that crosses the engine, having a rod attached, pass-
ing along to the starting platform, to which is fitted a quadrant and
reversing lever for taking the long rod, connected to the lifting arms,
on the weigh-shaft. The reversing handle has a catch and quad-
rant having a number of notches cut on its periphery, so by pulling
the reversing handle the link is raised; the catch is then released,
and being fitted with a spring, instantly drops into any one of the
notches, thus holding up the link. As the weight of the links and
rods is considerable, they are balanced with a weight fitted to an
arm on the weigh-shaft; thus the power required to move the links
and rods is equalized very nearly.
Many well-designed link-motions, from imperfections in the mode
of suspension, have failed to give all the requisites necessary for a
perfect motion, a free admission and release of the steam being of
the first importance. The lead or opening of the port by valve at
the commencement of the stroke should be equal, or nearly so, for
all grades of expansion, both for the forward and backward move-
ment; this being the case, the release must follow as a matter of
course. It is often necessary, when designing a new arrangement,
to make a skeleton model, to practically test the best position for
suspending the link, as the latter becomes very sensitive should this
point not be duly attended to. However, by carefully laying out
the valve-gear on paper, drawing it accurately to scale, testing by
delineation the various positions, the proper point of suspension can
be arrived at without the aid of the model. The point of suspension.
of the link itself is midway between the eccentric-rod ends, on the
arc described by the radius line, or nearly so, and on which the
suspension-rod should vibrate equally forward and backward. Some
links are suspended from the bottom, on the pin, for the backgoing
eccentric-rod; and instead of the valve-rod being guided as in the
former examples, a long rod is jointed to the valve-spindle, and
supported at the link end with a vertical oscillating arm, having a
double joint and pin direct, passing through the long rod, the link-
block working in a double joint on the end of the rod, the block
moves slightly up and down, following the arc of the oscillating
106
MODERN STEAM PRACTICE.
arm, the pin for the arm being placed as near the link-block as
convenient.
It will thus be seen that link-motions for the locomotive are of
three classes. In the first the link moves, or is lifted vertically, carry-
ing the eccentric rods along with it. In the second the link is
stationary, having no vertical movement, but simply oscillating on
the suspending rod, the valve-rod being lifted and depressed for
the forward and backward movements. And thirdly, the link is
likewise stationary, oscillating on pins placed on the valve-rod;
the eccentric rods are connected to the sliding-block in the link,
the rods and block being raised vertically, so as to suit the
forward and backward movements. The latter plan appears the
best motion, as the action of the valves is more correct, from the
link being fixed at the centre, and the valve-rod guided in a
straight line.

A
B
B
For modern marine engines, although the
long and short D slide-valves have almost
become obsolete, they are at times still
adopted, the sectional area resembling the
letter D, hence the name given to this class
of valve; with the long D, the valve is cast
all in one piece, the steam-ports in the cylin-
der being as short as possible. The steam
from the boiler, instead of passing into the
valve-casing, as with ordinary arrangements,
is admitted on the face of the valve, and the
back or curve of the valve is made perfectly
steam-tight by means of a plaited gasket,
and packing pieces of metal inserted in the
recesses at the top and bottom; the steam
exhausting into the condenser at the top and
bottom edges of the valve, the long D-valve,
from its great size, in some instances ex-
ceeding 8 feet in length, was necessarily a
heavy casting, so two short D-valves are
generally adopted, held together by means of
wrought-iron rods. The steam is admitted
into the valve-casing through what, in ordinary engines, forms the
exhaust-port in the cylinder, and passes all round the valve, which is
made steam-tight, as before stated, with hemp packing. The cover

Fig. 56.-Long D-Valves.
A, Steam from boiler. B, Packing
spaces.
REGULATION OF STEAM.
107
for the valve is suited for the under side of the top port and the upper
side of the bottom port, while the exhaust takes place at the top and
bottom edges of the steam-ports. The face on the cylinder is gene-
rally made of brass, rivetted to the cylinder, with brass pins screwed.
into the cast-iron. The valve-gear for paddle-wheel engines is
generally fitted with a loose eccentric, revolving with the main
shaft, having all the necessary stops on the eccentric and the shaft
for the forward and backward movements, the eccentric rod end
taking a lever on the weigh-shaft, fitted with the usual gab for
throwing the valve out of gear, having a long lever handle on the
weigh-shaft for working the valve by hand. As these valves are at
times very stiff to move, provision is made for securing a rope to the
end of the lever, so that a number of men may be employed to shift
them. The weigh-shaft is fitted with a lever for the valve rod, and
another for the back balance weight. This class of valve was gene-
rally used for the side-lever engine, and it is evidently desirable.
that it should be capable of being easily and quickly handled, as
men pulling at a rope, perhaps when the vessel is pitching and
rolling about in a heavy sea, is inconvenient and dangerous. A
wheel and pinion, therefore, is sometimes introduced to secure
greater ease in working the valve.
The slide-valve for oscillating engines is generally of the same
type as is adopted for land engines, being fitted with a pack-
ing ring on the back of the valve to relieve it from much of the
steam pressure. The valve mechanism being entirely different from
any other class of engine, the eccentric is loose on the shaft, and
fitted with all the necessary stops for the forward and backward
movements. The eccentric rod is fitted with a gab at its end,
working on a pin attached to an open curved link, made so as to
suit the oscillation of the cylinder; a rod passing upwards is forged
along with the link, having means of guiding it at the top with a
bracket fitted to the head-stock or framing for the main-shaft, the
link itself being guided at the bottom with suitable slides, fitted to
the pillars for supporting the head-stock. This valve gear, in its
simplest arrangement, has a plain handle, fitted with a rod for
attachment to the quadrant, with a means of throwing the gab on the
eccentric rod out of gear; thus the valve can be moved very quickly
for small engines. The cylinder is usually fitted with two valves,
but sometimes with only one; the double arrangement is introduced
to balance the cylinder. The valve spindles have guide-bars forged
108
MODERN STEAM PRACTICE.
on at the top, fitted with sliding blocks. There is a weigh-shaft,
working in suitable bearings, placed on the cylinder. This shaft
sometimes curves round the cylinder, with a bearing for each end,
I
Centre
AIA
Raddle Shaft
Trunnion Centre
but the general plan is to forge
in one piece the levers for taking
the valve rod and quadrant, in-
troducing a long bearing between
them, oscillating on a single jour-
nal fitted to the cylinder. Both
ends of the levers for taking the
quadrant and valve spindle are
fitted with pins and loose sliding
blocks. Where but one valve is
fitted, the centre of the pin in the
lever for the sector end is placed
on the centre line of the engine.
When the valve is at half stroke,
the levers being at right angles
to the centre line of the valve
spindle, the distance from the
centre of the pin to the centre
line of the trunnion for the cylin-
der is the radius of the link or
sector. Two valves are, how-

Fig. 57.—Valve Motion for Oscillating Engines.
A A, Sector slide blocks. B, Pin for the gab end of
eccentric rod.
ever, generally adopted, necessi-
tating the blocks for the sector
being kept slightly apart; then the radius for the sector is measured
from the centre of one of the pins to the centre of the trunnion.
Thus it is evident that the arc of the sector must sweep the centres
of both pins on the levers, however far distant from each other they
may be placed.
The hand-gear for small power is simply a lever, with link attach-
ment to the sector, but for heavy engines a hand-wheel and pinion,
working in a rack connected to the sector, is usually adopted;
while other arrangements have double eccentrics and link motion,
with suitable pin and block fitted to the sector, at a convenient place
as near to the centre of the sector as practicable. The valve levers
in connection with the quadrant being placed at the half travel of
the valve, the vertical distance from the centre of the guide-block
pin on the quadrant to the centre of the main shaft is the radius of
REGULATION OF STEAM.
109
the reversing link. The forward and backward movement of the
link is actuated by a starting-wheel working a worm-wheel and sector,
the shaft for carrying the sector-wheel being fitted with levers and
rods for connecting to it. Although the link motion and gear for the
oscillating engine is somewhat complicated, the action of the double
eccentrics and link is similar to the locomotive; each must be set
identically the same in relation to the main crank of the engine;
the only difference necessarily existing is the sector for communi-
cating motion to the valves, and at the same time accommodating
itself to the vibration of the cylinder.
For direct-acting horizontal marine engines the valve now gen-
erally adopted is of the multiple-ported type, having the ports
double or in some cases in triplicate. This valve was introduced
so that a large opening of port by valve could be obtained, with
a moderate throw of eccentric, thus reducing the size of the eccen-
trics and gear into as small a compass as possible. The valve
is usually placed on its edge, so that it is worked directly from the
engine shaft by double eccentrics and the link motion. Some
engineers place the valves on the top of the cylinder, working them
with a system of wheel-gearing similar to the back motion of a
turning lathe; the valve spindles are connected by suitable rods
to a revolving crank shaft, then by a series of wheels driven off the
main shaft of the engine, so by shifting the position of the two inter-
mediate wheels the relative position for the forward and backward
movement is obtained in relation to the main crank of the engine.
This motion, somewhat modified, is considered by some authorities
as perfect a motion for actuating the slide-valve as can be conceived,
although the wheel-gearing is very objectionable, and certainly the
link motion and double eccentrics is better calculated for modern
marine engines. As the valves for large engines are of considerable
size, and consequently the gearing heavy, and although only a portion
of the dead weight of the eccentric rods, link, &c., has to be lifted,
that, along with the friction, is considerable; and in all cases where
matter is to be actuated by hand, time must be had, and conse-
quently power, to do so,—it is therefore necessary to arrange proper
mechanical appliances for the handling of the valve mechanism of
the marine engine. The usual hand-wheel, with worm-wheel and
sector-wheel, lifting levers and rods, is by far the best plan, as the
link can be held up in any position, so as to work expansively if
required; but this is rarely resorted to, as it is a much better arrange-
IIO
MODERN STEAM PRACTICE.
1
ment to provide a separate valve to work expansively, allowing the
slide-valve to move always in full gear: thus the valve faces are
worn evenly. Some makers have introduced a cylinder having a
piston and rod so connected to the link that the reverse movement
is actuated by steam pressure; and where marine engines, such
as those in the Royal Navy, require an expeditious means of hand-
ling, this plan has a decided advantage in being able to reverse
the engine, or manoeuvre the screw propeller quickly, when the ship
is in action.
There are a variety of arrangements for link motions applied to
the slide-valves of marine engines, but the arc of the link is described
the same way in all cases, no matter whether the link is slotted out,
or simply solid; when the valve and adjuncts are at half stroke, from
the centre of the crank shaft to the slide-valve block, or centre of
the pin on which the link vibrates, is the length of the radius that
describes the arc of the link. Some
examples of valve-gear have two valve
rods, with eccentric rods on the return
principle, one of the valve rods being
placed above and the other below the
main shaft of the engine. The rods are
guided on the condenser with a long
sliding bar, having snugs forged on
to take the rods. The lifting lever is

Fig. 58.-Link Motion and Starting Gear for Marine Engines.
placed on the top of the condenser, having a rod passing down-
wards, taking the reversing link at the centre and on the arc line;
the lever shaft carrying a toothed sector, working into a worm-wheel
placed vertically, having the starting handle or wheel horizontal.
In this arrangement the reversing lever makes a half revolution,
consequently this mode of suspending the link is not well calculated
REGULATION OF STEAM.
III
to work in any other grade than full gear; but should it be desirable
the lifting lever can be made longer, and so arranged as to travel
merely a portion of the circle, keeping the lifting link nearly vertical
throughout. Thus the suspension of the link in this manner is
better calculated for working expansively; but it must be borne in
mind that when the slide-valve works for any length of time in an
intermediate position it is apt to wear a hollow on the cylinder face.
Instead of the two rods for the slide-valve, as in the previous ex-
ample, with the return eccentric rod system retained, one valve rod
has been substituted, placed above the main shaft of the engine. The
action cannot be so good as with two rods, owing to the eccentric
rods working at a considerable angle, the proper position being in
as nearly a straight line as possible with the valve rods. When so
fitted for direct action the valve rod is guided with a suitable cross-
head, placed at the side of the rod. This works in cast-iron guides,
bolted to the valve-casing; the link is suspended similar to the


Fig. 59.-Link Motion and Starting Gear for Marine Engines.
locomotive arrangements, thus working expansively by the link.
The plan may be adopted for small engines, but undoubtedly for
large power there should be a separate valve for working expansively.
The brackets for taking the reversing lever are placed on the main
framing, the starting wheel is on its edge or at an inclination; the
shaft for carrying it is supported at both ends, and is fitted with a
112
MODERN STEAM PRACTICE.
worm-wheel and pinion. This gear is very generally adopted, as
the link is locked at any position without any other mechanism for
holding it up. Some arrangements for direct action have the eccen-
tric rods too short; where it is not convenient to get in a length of
rod that is the radius of the link, at least six times the throw of
the eccentric, indirect means are preferable for working the slide-
valve; and certainly the return eccentric rod system, as before de-
scribed, seems as good an arrangement for indirect motion as can be
devised. It is essential that the suspending rod for the link should be
made as long as convenient: this is a very necessary point to attend
to when arranging link motions, as when the rod is too short the
versed sine of the chord of the arc that it describes becomes very
great, causing the link to have an up and down motion, which sen-
sibly affects the working of the valves, more especially when the
eccentric rods are short. Indeed, when such faults are both com-
bined in one arrangement there is no truthful action of the valve
whatever, and in all cases this can be avoided with proper attention.
It is quite unnecessary to describe such malformations.
The modes adopted for guiding the lifting rod in a vertical manner
must next be considered, and this apart from the starting-wheel,
as its position varies very much, and is simply arranged in the best
locality for handling the engines, which undoubtedly is on the same
level as the stoke-hole, although some engineers place the starting
gear on the top of the condenser, or about the same height as it,
thus getting a good view of the machinery in motion. With bevel-
wheels and cross shafts it is a very simple matter to place the start-
ing gear in the most convenient situation; but all means should be
as direct as circumstances will admit of. In guiding the lifting rod
for the link in a vertical manner a simple kind of parallel motion is
sometimes used. The lifting rod is suspended downwards, the bot-
tom pin is fixed to the middle of a short link, the ends of the link
taking an arm placed above and another below the lifting centre;
one of these arms merely vibrates on a fixed pin, while the other
or bottom one is keyed on the reversing shaft that passes across the
engine. This shaft is likewise fitted with an arm for taking the
reversing rod, passing along to some convenient part on the con-
denser. In this example the reversing rod is attached to a cross-
head moving in suitable guides, the starting-wheel actuating a screw
cut in its shaft, the cross-head having a female screw to correspond.
It is quite essential that all link motions should be balanced with a
REGULATION OF STEAM.
113
counter weight, keyed and fixed to an arm on the reversing shaft.
Instead of parallel motion for keeping the lifting rod in a vertical
line, a plain cast-iron guide is at times adopted, having a sliding
block for taking the lifting pin, and the reversing levers, similar to

#
#
C
Fig. 60.-Link Motion and Starting Gear for Marine Engines.
the foregoing example, fitted with a short link for connecting the
reversing arm and sliding block; the lifting rod being attached to
the pin on block and main link, doing away with the top arm, as in
the previous example. In some designs the link is not suspended
for the forward movement, but simply rests on the slide block.
When the link is full down, the lifting pin on the arm passing
through a short slotted hole in the rod, the pin being free to move in
the slot to suit the vibration of the link, there is neither upward nor
downward movement in the link, as it is always resting on the slide-
block for the forward movement, the pin in the elongated hole
accommodating itself to the versed sine of the lifting rod. Another
mode of lifting the link is by means of a screwed rod placed verti-
cally (Fig. 61), having bevel-gear overhead in connection with the
starting-wheel. On the screwed part of the vertical shaft at the
bottom is fitted a nut, having two pins, for taking the short links tħat
are fitted to the lifting arm, the lifting rod for the main link being
jointed thereto; the pin is placed between the end and the centre of
vibration of the lifting arm. The shaft for the lifting arm passes
across the engine, having merely a plain lever and rod at the other
end for actuating the main link.
A variety of other examples suited for the slotted link as well
8
114
MODERN STEAM PRACTICE.
as for the solid one could be given. Suffice it to say, however, that
when solid links are adopted the eccentric rods are connected to

1
1
}
•
O
Fig. 61.-Link Motion and Starting Gear for Marine Engines.
the ends of the link, one of the pins taking the lifting rod being con-
nected to the lifting arm with similar mechanism as for the slotted
link. However, when the link is suspended from any other centre
than the true one, at or near the centre of the link, the motion of
the valve is not so correct as with the plans described above. For
very small engines we would certainly adopt the usual starting gear
as applied to the locomotive engine, having a plain lever handle
fitted with a catch, and quadrant notched to suit a varying expan-
sion; but of course this must only be used where the strength of
one man is sufficient to work the valve-gearing.
From the brief sketch above given of some of the plans most in
use for giving motion to the slide-valves of the marine engine, it
will be seen that, where circumstances admit, the two former
examples are the simplest motions, as having fewer working parts;
and it must be borne in mind that simplicity in the machinery on
board ship is the main thing to be studied.
In concluding this part of the subject attention must be drawn to
a species of valve and gear for working expansively, termed the
gridiron expansion-valve, of which there are two kinds; one being
REGULATION OF STEAM.
115
quite flat, while the other is circular. The former is simply a flat
plate, having a number of slots or openings, strengthened with ribs
cast on the back; the valve is of brass, as likewise is the face it works
upon. It is placed as near to the main slide-valve as possible. There
is a considerable steam pressure on the flat type, and to obviate that
B
F


A B, Line of crank,
Fig. 62.-Expansion Valve Gear.
c,Valve chest. DE, The radius of expansion link.
G, Centre of eccentric at the beginning of the stroke.
F, Lever end for ditto.
defect circular valves have been introduced, one species being in
equilibrio, consisting simply of a series of rings and openings cast all
in one piece, and having a central boss with ribs radiating from the
centre. These ribs hold all the rings together, the openings being
I inch broad for large valves; five of these openings have been
adopted, giving ample area. This valve is accurately turned to fit a
similar cylinder of brass, with openings to correspond, held together
with vertical ties, cast all in one piece—the whole being encased in a
cast-iron valve box, having an annular space all round. The steam
from the boiler passes down through the hollow valve, and then round
the annular space into the slide-valve chest on the cylinder. At the
commencement of each stroke the ports are full open, and the valve
gear is so arranged as to cut off up to a little more than one-half of
the stroke; at least, practically speaking, this is attained (while the
slide-valve for the engine is arranged to cut off at five-eighths of the
stroke of the piston). The valve gear consists of an eccentric,
having a throw of 2 inches, the eccentric rod taking a lever 4 inches
in length. This lever vibrates on a short shaft, on which is fitted a
slot link with a movable sliding block, to which is attached the con-
116
MODERN STEAM PRACTICE.
necting rod for the valve spindle. As the circular valve depends on
its fit to make it steam-tight, it is evident that it should be arranged
vertically, so that the wear may be as little as possible. To set out
this valve-gear the line of the main crank is placed level, the crank
pin being at the commencement of the IN stroke; the valve is set full
open, and at a point on the valve spindle, with a certain radius to
suit, describe an arc: this is the curve of the link. It is evident
that when the sliding block in the link is moved to and fro along
with the radius rod in connection with the valve spindle, the line of
the crank being level, that no motion is imparted to the valve, or
even when the crank is revolving the radius link can be drawn to the
centre of vibration of the lever shaft; thus the valve always remains
open when required, the lever and link simply vibrating to and fro.
The motion of the lever is always constant, travelling in an arc due
to the throw of the eccentric, while the pin and block working in
the slotted link can be moved out at pleasure, giving a varying
throw. Hence the valve can cut off the steam supply up to one-half
of the stroke of the piston; but from the nature of the motion, the
eccentric passing the dead centre of its throw, while the crank for
the engine is gaining rapidly, the valve does not commence to open
until the piston has travelled about five-eighths of its stroke, when
the main slide-valve has come into action, and consequently no
more steam can be admitted into the cylinder. Thus the expansion-
valve gives a varying cut off from the valve-casing, while that of the
main slide-valve admits a constant volume into the cylinder, de-
veloping the full power of the engine while so doing. The block
and pin for the separate expansion-valve can be drawn back to the
centre of vibration, leaving the passages in the expansion-valve
always full open. This single eccentric and link motion for work-
ing an expansion-valve separately from the main slide-valve
can be arranged for any class of valve, as likewise the locality of
the valve in relation to the eccentric on the main shaft, the arrange-
ment given being originally designed by the author for marine
engines.
The geometry of the steam-engine next calls for attention, at
least that portion of it which immediately bears on the subject of
valve motions. This must be always carefully studied, in order to
determine all the points requisite in arranging the slide-valve, the
lap and lead of the valve to suit a given cut-off in the cylinder being
of the first importance.
REGULATION OF STEAM.
117
THE CONNECTING ROD AND CRANK.
The length of the connecting rod varies considerably, those of
direct-acting marine engines being much shorter than in other
arrangements. Taking an example, however, where the length
equals five times the length of the crank from centre to centre; when
the centre of the cross-head, where the connecting rod is attached,
is placed at half stroke, from the centre of the engine shaft to the
centre of the cross-head is the length of the connecting rod, delin-

IN
Crank Path
OUT
18
10 14 3%
HALF
3/8 1/4 Yo
Fig. 63.-The Connecting Rod and Crank.
A, Centre of engine shaft. B, Half stroke of piston. c, Point on crank path at half stroke.
D E, Stroke of piston. F, Point on crank path at 8ths of the stroke.
eated as from A to B. With B A as the radius describe the arc A C,
draw a straight line from the centre A to the point C on the crank
path; this is the centre line of the crank at half stroke, the point C
being the centre of the crank pin above or below the centre line of
the engine. It will be seen that there is a great difference of the
travel of the crank pin on its path for the IN and OUT strokes, the
arc described for the IN stroke being greater than that for the
OUT, as delineated from IN to C above the centre line, and from
OUT to C below the centre line of the engine. There is no remedy.
for this variation; it is inherent in all crank motions, and varies as
the length of the connecting rod. It therefore becomes imperative
to find the point C to suit the length of the rod, as likewise to deter-
mine the point on the crank path for the particular part of the
stroke of the piston that may be determined on for cutting off the
steam. Thus supposing it is desirable to cut off at five-eighths of
the stroke of the piston, the arc AC will be greater than for the
half stroke, and vice versa when the point of cut-off is sooner than
the half stroke. The particular point is easily found by taking
the radius, and placing the point of the compasses on the first point
118
MODERN STEAM PRACTICE.
from B to E, then cut the crank path at F, the dotted line A F is the
line of cut-off by crank when the piston has travelled five-eighths of
its stroke. This angle is always the same, no matter whether the
stroke or length of the crank is longer or shorter; that is to say, if
the connecting rod bears the same proportion to the crank, namely,
five to one.
THE CRANK AND ECCENTRIC PATHS.
The crank and eccentric paths are identical; the path of the one
is exactly the path of the other. Each revolves around the same.
centre, namely, that of the main shaft of the engine. The crank and
eccentric centres each describe an arc, the length of the chords
varying with the circles described. The chord A B described by the
crank centre being greater than that delineated by the eccentric

Eccentric Path
Fig. 64.-The Crank and Eccentric Paths.
A B, Chord of the arc of supply on crank path. C D, Chord of the arc of supply on eccentric path.
E F, Versed sine of the chord of the arc of supply on crank path. G H, Versed sine of the chord
of the arc of supply on eccentric path. I, Centre of engine shaft.
centre on C D, consequently their versed sines must likewise vary.
Thus, in the example, the large circle denotes the path of the crank,
and the small circle that of the eccentric; A is the commencing of
the IN stroke, and B the point of cut-off determined on.
It is very
evident that the point A, or crank pin, has travelled from A to B,
while that of the eccentric has travelled from C to D; draw the lines
A B and C D, bisect A B at F, and draw the lines E F and G H through
the centre I. The line E F is the versed sine of the chord for the crank
path, and G H is the versed sine of the chord for the eccentric path.
In all cases the versed sine of the chord for the crank path must, in
REGULATION OF STEAM.
119
the first place, be found due to the length of the crank and connecting
rod, as likewise the point of cut-off; then when the versed sine of
the eccentric is likewise known, which equals the opening of the port.
by valve, minus one-half of the lead, then the eccentric circle can be
found by the rule of three (based on the known property that the
versed sines of circles of similar segments are as the diameters of
the respective circles). Thus, supposing the crank circle was
18 inches in diameter, the versed sine E F being 4 inches, while the
versed sine G H is 14 inch: we have
4:18:125=5'62 inches diameter of the eccentric circle.
THE CRANK AND ECCENTRIC PATHS DELINEATED AS REGARDS
THE COVER, LEAD, AND CUT-OFF.
The length of the eccentric rod being not less than six times the
throw of the eccentric, the versed sine of the chord described by the
arc on the eccentric path equals the opening of the port by valve,
minus one-half of the lead nearly. Thus, supposing the versed sine
of the chord of the arc of supply on the crank path was 4 inches,
the opening of the port by valve 1½ inch, and, for the sake of
illustration, the lead or opening of the port at the commencement
of the stroke of the piston is ½ inch, we have 1½-4=14 inch,
the versed sine of the chord of the arc of supply of the eccentric.
The Chord of Steam Jupp C or pont, of cut ip
I

IN
OUT
Eccentric Rod Valve open Ye vrch
Centre Line
VALVE
Eccentric Rod Valve Start
Cylinder
Supply
Are of
J 2
Crank Path
Fig. 65.-The Crank and Eccentric Paths delineated as regards the cover, lead, and cut-off.
Let A B represent the line of the crank at the commencement of
the IN stroke; as the point A or crank pin travels from A to C, the
point of cut-off, it is evident that the valve must open and shut
while the crank-pin centre describes the arc A C. It is therefore
necessary to lay off the eccentric centre on the opposite side of the
path, as at F. Set off F E, which equals the full opening of the port
120
MODERN STEAM PRACTICE.
by valve, minus the lead, or I inch; this is the distance from E to F.
Then set off E D, the lead equals ½ inch, while the remainder of
the radius of the eccentric circle, or B D, equals the outside cover
or the lap of the valve. With the length of the eccentric rod as the
radius from E, the point 2 on the valve can be determined; this,
for sake of illustration, is measured from the edge of the valve,
instead of the pin on the valve rod for taking the eccentric rod,
and from the edge of the valve, as at 2, cut the eccentric path at
2, and from the point D fix the point 3 on the valve; cut as before
the point 3 on the eccentric path, join the line from 2 to 3 on
its path; that line is the chord of the arc of supply by eccentric.
It will thus be seen that the figures on the eccentric path cor-
respond with the figures on the valve; thus the point 2 gives the
lead, the point I the full opening of the port by valve, and at the
point 3 the valve has returned and just covers the port, this being
the point of cut-off, or no more steam is admitted into the cylinder,
the remainder of the stroke of the piston being actuated by the
expansive force of the steam in the cylinder. It will thus be seen
that when the crank centre is at the commencement of the IN stroke,
as at A, the port is open ½ inch; when the crank pin centre travels
to G the port is full open, and the valve returning, until the crank
centre has travelled to C, then the cut-off takes place, the valve
having closed the port; thus the expansion of the steam in the
cylinder commences. This only provides for the IN stroke; that
for the OUT stroke must be found in like manner, and it will be
seen that with the same throw of the eccentric the opening of the
steam port by valve is less for the OUT stroke than for the IN stroke;
consequently the lap for the OUT stroke must be greater than for
the IN stroke. When great nicety is required, the area of the port
on the cylinder should be arranged for the OUT stroke, and the
length of the port for the IN stroke reduced accordingly, so as to
get equal area of port for IN and OUT stroke, as likewise equal cut-
off in the cylinder. Thus when the versed sine of the chord of the
arc of supply is given for the crank path, and the versed sine of
the chord of the arc of supply can be determined, it becomes an
easy matter for the student to practically delineate the various
points of the crank and eccentric paths in relation to each other.
To find the versed sine of the eccentric rod, working to the for-
mula V=R—(√ R²—C²) [V=versed sine, R= radius, C=semi-
chord], we can take as follows:-Throw off the eccentric, or the
REGULATION OF STEAM.
[21
diameter of the circle of the eccentric pulley centre, round the
centre of the crank shaft (C × 2)=50 parts. Eccentric rod, 300
parts in length (R); opening of port, 20 parts; lap, 5 parts.
300²=90000; C=25; C²=625.
Then taking 90000-625=89375, and 89375 = 299— Then
V or the versed sine would but equal 300-299—; or I × : equal
to but of the entire travel of the valve.
DOUBLE ECCENTRICS AND LINK MOTION.
The mode of setting out the link motion for the marine engine
differs but little from that pursued for the locomotive type. With
the former the double eccentrics and link are simply introduced, so
as to get a convenient arrangement for handling the engines, the
link being rarely used to work with varying expansion, it being
either full up or full down. The reversing lever in general makes
1
1
•
Level Line
A
-
1
1
Down

VALVE
at Half Stroke
Fig. 66.-Double Eccentrics and Link Motion for the Marine Engine.
a half revolution around its axis, the point of suspension on the
lever being either up or down, the link being in full gear for the for-
122
MODERN STEAM PRACTICE.
ward or backward motions, as the case may be. In some instances
the lifting or reversing lever only describes a small arc of a circle,
having the radius of the lever much longer than by the former
arrangement; then the point of suspension is at some intermediate
part of the half circle; in fact, just similar to the examples given
for the locomotive engine in the preceding pages. In all examples
the most convenient method of setting out the link is by placing
the valve and adjuncts at half stroke, A being the centre of the
crank shaft, and B the centre of the pin on the valve spindle for
taking the block on which the link slides. With the radius A B
describe the arc D D; this is the centre line of the curve of the
link; make the distance between the pins for taking the eccentric
rods, as at E E, equal to three times the throw of the eccentric
or diameter of the path. Then from the point B, with a convenient
length of lifting rod as the radius, describe the arc C F; it gives the
position at the half lift of the link of the reversing lever, or, as in
the main connecting rod for the engine, the vertical distance from
B to C is the length of the lifting rod, the radius of the lifting arm
CF being half of the distance between the centres of the pins on
the link for the eccentric rods. Thus we have given the leading
points to attend to in setting out the double eccentrics and link
motion.
THE LAP OF THE VALVE VARIES AS THE CUT-OFF AND
LENGTH OF CONNECTING ROD.
With the opening of port by valve, and the lead remaining the
same, the lap of the valve must vary as the cut-off. The less the
chord and versed sine of the arc of supply becomes on the crank
path the greater is the chord of the arc of supply on the eccentric.
The figure shows the chord of the arc of supply on the crank path in
plain lines, while the eccentric circles are delineated by dotted lines.
The line A A is the opening of port by valve, while the curved line
represents the laps for the various points of cut-off. It will be seen
that when the steam is cut off at five-eighths of the stroke of the
piston that the valve at B has less cover than at C; or when the steam
is cut off at five-eighths of the stroke the valve requires less lap than
for cutting off at the half stroke of the piston, and so on increasing
the diameter of the eccentric path. The diameter of the sheave like-
wise increases rapidly, more especially when cutting off at one-eighth
REGULATION OF STEAM.
123
part of the stroke of the piston, when we have, as in the figure, the
diameter of the eccentric path much greater than the diameter of
the crank path. It thus becomes apparent that the valve must be

IN
D
Crank Paih
4/8
3/8
5/3
Eccentric Paths
E
F
7
B
Curve of Lap
2
#
Fig. 67.-Diagram of the Lap of Valves.
altered, the multiple-ported type being adopted. Thus, by intro-
ducing three steam ports at each end of the valve, with one central
exhaust port, we gain the same area of port on the valve, while the
opening of each port is only one-third of that of the single-ported
arrangements, so when the steam is cut off at one-eighth or one-
fourth part of the stroke of the piston, a valve should be adopted
having three steam ports at each end, with one central exhaust port,
thus greatly reducing the stroke of the valve, and consequently the
lap; the lead may be presumed equal, at least as far as a particular
engine is concerned. The lead is greater for high-speed heavy pistons
than for engines of the locomotive type, some marine engines hav-
ing 3% inch of lead, and even at times more, according to the weight
and speed, while for high-speed light pistons of lead suffices.
It must be borne in mind that the length of the connecting rod
materially alters the chord of the arc of supply on the crank path.
With a short rod the chord becomes longer, and vice versa; and as
the versed sine of the chord of the arc of supply on the crank path
124
MODERN STEAM PRACTICE.
must be a known quantity, as likewise the diameter of the crank
path, when the opening of port by the valve is determined on, as
we now propose to do, the slide valve can be set out as generally
adapted for all classes of engines.
OPENING OF PORT BY VALVE.
The diameter of the cylinder and speed of the piston must also be
determined on to find the opening of port by the valve. Sup-
posing it is required to find the opening of port by the valve, with
a piston speed of 300 feet per minute giving out for a single cylinder
200 nominal horse-power, multiply the constant 33,000 by the power
required, and divide the product by the speed of the piston per
minute, multiplied by the constant 7 lbs., and the quotient added.
to half the area of the piston-rod will give the number of square
inches of cylinder area; thus,
33000 x 200
300 X 7
=3142+28 3170 square inches,
or say 63½ inches, is the diameter of the cylinder, this being the
recognized rule for the nominal horse-power of marine engines. For
high-pressure engines we simply take the steam pressure in boiler
instead of the constant 7 lbs., making an allowance of 15% of the
power required, and the rule for finding the cylinder's diameter is
the same as for the marine engine. Thus, supposing the power
required was 20 horse, and the speed of the piston 200 feet per
minute, with a steam pressure of 30 lbs.,
33000 × 32.5
x =1787 say 15 inches diameter.
200 x 30
=
To find the full area or opening of port by the valve we will take the
former example as for the marine engine, namely 3170, as area of
the cylinder in square inches, with a piston speed of 300 feet per
minute. Multiply the cylinder area by the speed of the piston in
feet per minute, and divide the product by the constant 10,000, the
quotient gives the area of port by the valve--
3170 × 300
10000
= 95 square inches.
Thus the area of the steam port by the valve, divided by the
length of the steam port, will give the opening. The length of
the port is found by dividing the cylinder diameter by 17; thus,
63'51'737'5, or say in round numbers 38 inches, is the length
REGULATION OF STEAM.
125
of the port; and again 95 ÷ 38=2.5 inches, this is the linear
opening of the port by the valve for a single port. As double-
ported valves are generally adopted, the linear opening of each will
be 1.25 inches.
The steam ports in the cylinder are much in excess of this, the
area for the steam port being of the cylinder area, and for the
central exhaust % of the cylinder area is generally allowed,—
3170
19
3170
8
= 171 square inches for the steam port,
=396 square inches for the exhaust port.
Thus we would have for steam port 171÷384'5 for main steam
port on cylinder, but as two are required the width of each will be
2.25 linear inches. As double-ported arrangements have a bridge or
strengthening piece on the centre line of the steam port, say 1½ inch
broad, we would have four steam ports in the cylinder, 19 inches
long and 24 inches wide. The exhaust or central port in the cylinder
is 39½ inches long, and say 10 inches wide, or nearly so, to give
the required area, care being taken that the passages into con-
denser are not contracted.
SETTING OUT THE VALVE FACES.
CENTRE OF VALVE
H
EXHAUST EXHAUST
VALVE
STEAM
STEAM
CYLINDER
Fig. 68.
We will suppose the lap of the valve is...
EXHAUST

STEAM
inches.
1%
The width of the outer steam ports on cylinder..
24
The width of the outer exhaust port equals the half travel of valve.... 3%
The width of face on valve………..
14
The width of the inner steam port..
14
The lap of valve for inner steam port
18
The width of inside steam port on cylinder.
24
The width of face on cylinder..
134
The half width of exhaust port..
บา
5
20%
205% x 2=414 inches, is the length of the slide valve.
The face on the cylinder between the outer and inner steam ports
is found as follows:-
126
MODERN STEAM PRACTICE.
The outside exhaust port on valve.
...
The width of the narrow face on valve.
The width of the inner steam port on valve..
The inside lap for steam port…………….
inches.
3/8
14
14
1%
72
Thus the valve and adjuncts can be delineated from the foregoing
dimensions. The packing ring on the back should be as large in dia-
meter as the length of the ports will admit of. The rubbing ring on
the back of the valve is of brass, while the one the set screws press
against is of wrought iron, a common gasket packing being inter-
posed between the rings. Some have proposed springs along with
the packing, with the object of relieving the cylinder in case of
priming. It need scarcely be stated that when springs are intro-
duced they must be placed so that the set screws press them against
the wrought-iron ring.
RELIEVING THE CYLINDER FROM INTERNAL PRESSURE.
With the desirable object of relieving the cylinder from internal
pressure the author has arranged a species of valve differing mate-
rially from the double-ported class, having the rings on the back
for relieving the valve from back pressure. The arrangement pro-
posed admits the steam from the boiler into the cylinder through
the middle port cast on the cylinder, the valve-casing communicat-
ing with the condenser. The steam by this plan has a tendency to
blow the valve off the face, and to prevent this occurring the valve is
provided with a steel plate on the back, let into and securely attached
to the valve; rollers bear on this plate, fitted with journals and
guide-rods, which pass through the back of the valve-chest cover,
having suitable stuffing-boxes perfectly air-tight. There are curved
springs secured with mid shackles to the valve-casing cover. These
springs have holes drilled at the ends, through which the spindles
pass; the ends of the spindles are screwed and fitted with nuts, so
that by adjusting the springs any amount of pressure on the valve
face can be obtained. It will be seen that, from the steam passing
through the valve, the latter is very nearly in equilibrio; still the
steam has a tendency to blow the valve from the face. This is
counteracted by the rollers, which can be so adjusted as to throw
back a little more than the outward pressure; thus the only pres-
sure on the face of the valve is the difference between the outward
REGULATION OF STEAM.
127
pressure of the steam acting on the valve and the pressure imparted
by the springs, which can be adjusted to the greatest nicety. This

Steam
From Boiler
Figs. 69, 70.-Slide Valve by the Author.
priming occur the
This roller motion
valve requires no packing rings, and should
cylinders are instantly relieved from the water.
should work easily and with less friction than the arrangements
with packing rings on the back. Should the boiler pressure, too,
become higher than the working pressure, this arrangement will
act as a safety valve, blowing the steam through the exhaust into
the condenser or into the atmosphere, as with high-pressure engines.
RELIEVING THE SLIDE VALVE FROM BACK PRESSURE.
The double-ported valve for high-pressure engines differs very
little from those for the marine engine; in fact, the only difference
consists in making the exhaust ports at each end of the valve
smaller, as likewise the ports in the cylinder may also be reduced in
width, and when made very small no packing rings are required,
neither is it necessary that marine engines should be so fitted, as
with small valves the pressure is not much felt. However, correctly
speaking, all valves should be relieved from the back pressure, whether
they are double-ported, or simply the original arrangement, with only
128
MODERN STEAM PRACTICE.
three ports in the cylinder. Some of these valves for marine engines
simply consist of a frame, having metallic packing rings bearing on
the back of the valve casing or cover. In the
valve delineated the middle recess is simply
formed to lighten the casting as the exhaust
steam passes through the valve itself in its
passage to the condenser. The packing ring
fits into a recess on the back of the valve, a
plaited gasket is interposed between the pack-
ing ring and a thin metallic plate with springs
for pressing the valve and ring to their respec-
tive faces. It will be seen that this valve very
nearly approaches to what we may term an
equilibrium valve. The only objection to this
class is that there are two faces to keep tight,
and that the ring depends on its accurate fit,
along with the gasket packing, to keep it steam-
tight. To obviate this difficulty a variety of
packing rings have been devised, depending on
their metallic contact alone so as to make them
steam tight; and as it is an object in some engines of the high-
pressure type, having great piston speed, to reduce the weight of

Fig. 71.-Equilibrium Valve.
the reciprocating parts, the rings have been
made very light. An improvement upon the
preceding example is that the valve is fitted
with a metallic piston, having a spring ring
fitted to the piston, the piston and slide valve
being pressed to the faces with springs inserted
at the bottom of the cylinder, which is cast on
the slide-valve. The exhaust, as in the pre-
vious example, passes through the valve into
the condenser; in such cases it is advisable to
fit a brass face on the condenser casting, the
steam chest for the valve, as it were, forming
part of the condenser, that is, the valve chest
and the condenser are cast all in one piece.
Another form has the piston and face for press-
ing to the back of the valve-casing of a lighter
section, and the piston made steam-tight with steel-spring rings
recessed in the piston. The piston in this arrangement is simply

Fig. 72.-Equilibrium Valve.
REGULATION OF STEAM.
129
a ring of metal, the bearing surface on the back of the valve-casing
being merely the thickness of the metal forming the ring. It is
•

Fig. 73.-Equilibrium Valve.
held to the face on the valve-casing with two flat springs placed
inside of the valve, thus pressing the valve and the piston ring
to their respective faces. A pin is inserted in the valve and ring
to prevent the latter turning round; the valve is fitted with a hoop
to which the valve rod is attached. This arrangement is about
as effective as any. Some engineers have split the piston ring;
others consider, however, that this is not required, as it is a more
preferable plan to make the piston steam-tight with light steel rings
recessed into the piston as already described, as the ring of itself
with a good fit would nearly be steam-tight, while the steel rings
make it perfectly so. This valve is admirably suited for the loco-
motive engine; the rubbing surface on the packing ring is very
small, and there can be no doubt that this is a benefit. Care must
be taken, however, to have ample provision made for running off
any water that may collect when the engine is standing still, so that
the narrow rubbing surface may be kept quite dry. In the large
marine compound engines, piston valves are now being used.
There are other plans for tightening up the slide-valve rings.
The casing, for instance, is pro-
vided with a cover on the back,
its inside face being truly planed
and scraped. To the valve is
fitted a ring with snugs cast on
it, each snug being provided
with a ratchet screw bolt and
spring. This ring carries two
packing rings, which are pressed

Fig. 74.-Ratchet-bolt for Valve Rings.
up against the valve chest door with the set screws. There are
holes` tapped in the valve-casing door for the reception of screwed
plugs. These holes correspond with the snugs and screws for
9
130
MODERN STEAM PRACTICE.
tightening up the packing rings, which is done by means of a
box spanner inserted through the hole, taking a square part on
the screwed studs, which, being turned in a particular way, causes
the ratchet to click. Thus the engineer, by counting the number
of clicks for each set bolt, can set up the faces equally. It is
advisable that the rings should be tightened up under steam, so as
to adjust the faces for the expansion of the metals. This plan is
neat, but many engineers consider it not nearly so effective as the
usual method with plain set screws, packing rings, and plaited
gasket, as before described.
To enter into details of an arrangement for taking the pressure off
the back of the slide valve, with a piston having an oscillating link,
&c., would be of little practical benefit, as such has been very rarely
adopted. Suffice it to say, that the piston works in a short pipe
accurately bored out, and placed or cast in the valve-casing cover,
having a link for connecting the valve; the steam pressure acting on
the piston tends to pull the slide-valve from the face. Thus the
force is suspended, as it were, on the link pin, and consequently
the valve is more easily moved. Sometimes a piston has been intro-
duced to balance the weight of the slide-valve when placed verti-
cally, and no doubt the plan is good when the slide-valve is very
large, as the strain on the valve gear is not so much felt. The
piston should be fitted with small steel spring rings, thus simplify-
ing the arrangement.
THE INDICATOR DIAGRAM.
When the steam in the cylinder is cut off at any part of the
stroke of the piston, and were no condensation taking place, the pres-
sure of the steam at the end of the stroke, or at any intermediate
portion of it, could be calculated to a nicety. The curved line that
would delineate the steam pressure inside of the cylinder from the.
point of cut-off would then be quite regular. But in practice there
are various causes that tend to make the line of expansion a very
irregular figure; for instance, with a slow cut-off, as with the eccen-
tric motion, the line of expansion does not approach so nearly the
THE INDICATOR DIAGRAM.
131
B
1
d
e
A
b
theoretical curve as when the valves are suddenly shut off with a
cam motion. To ascertain the pressure of the steam in the cylin-
der, as likewise how the valve acts in its admission, recourse must
be had to a very simple contrivance, termed the
indicator, or miniature cylinder and piston, similar
to that of the engine itself. This instrument, in
its original form, has a small cylinder, fitted with
a piston and rod. On the top of the cylinder a
light spiral steel spring was placed, fixed to the
cylinder at one end and to the piston rod at the
other end, a pencil fastened to the piston rod
moving along with it. The steam pressure raises
the piston above a line termed the atmospheric
line, and when there is a vacuum in the cylinder
the piston is depressed below the atmospheric
line. Thus the rising and falling of the piston
denotes in the first instance the steam pressure
above the atmosphere, and secondly the vacuum
below it. A roller is placed alongside, fitted
with a pulley, having a cord attached to it; by
pulling the cord the roller rotates, and by slack-
ening the cord it returns to its original position,
being moved by a spring. The cord is fastened
to some reciprocating part of the engine, and
by a reducing lever motion is imparted to the A, Roller. 6, Pulley and cord.
roller; thus the full stroke of the piston is taken
in miniature, the motion being simply changed
from reciprocating action to that of a rotary motion. A roll of
paper is fastened round the roller, and secured with a clip. The
pencil fastened to the piston rod is made to press on the paper
with a slight spring. The cord is moved by hand, and the pencil
marks a straight line on the paper, termed the atmospheric line.
When the engine is in full working order this line never varies until
the steam is admitted by a hand tap to the under side of the
piston, which instantly rises, distending the spiral spring accord-
ing to the pressure of the steam. The roller being in motion, a
figure is traced on the paper with the pencil, delineating the pres-
sure on the piston of the engine, above the atmospheric line, as
likewise, on the return stroke, marking the vacuum in the cylinder
below the line, the spring being compressed by the pressure of the

Fig. 75.—M‘Naught's
Indicator.
c, Piston. d, Spindle.
e, Pencil. f, Plug-tap.
132.
MODERN STEAM PRACTICE.
atmosphere acting on the top of the piston. This is all the indicator
can give off, except showing at what part of the stroke the steam is
cut off, and the behaviour of the valve in admitting the steam into the
A
E
F
D
C
Atmospheric Line
B
Fig. 76.-Indicator Diagram, from Eccentric Valve Motion.
engine cylinder. Such a diagram is delineated: A B is the atmos-
pheric line, C denotes the pressure above it at the commencement
of the stroke, D is the point of cut-off, E is the point where the steam
in the cylinder falls to the atmospheric line, F G is the vacuum line,
and G H is in compression. The valve has shut the opening from
the condenser, and the compressed vapour and steam admitted by
the lead of the valve causes the pencil to rise rapidly to the point C
on the commencement of the stroke. Then from C to E denotes the
steam pressure on the engine piston, and from F to G the vacuum,
while G H is the volume of cushioning required to check the motion
of the piston at the end of the stroke, in a gradual manner. The
amount of compression being greater for a heavy piston having a
high velocity than for a lighter piston having the same velocity,
bearing in mind that lighter pistons of exceeding high velocity may
require more cushioning or opening by valve, technically termed
'lead,” than heavy ones moving slowly. It must be noted that the
point D in the diagram only approximately shows that part of the
stroke where the steam ports are entirely shut, or the communication
from the boiler cut off by the valve.. This defect in the diagram is
inherent in all when the valve is actuated on by an eccentric, as the
motion of the eccentric is very slow when shutting the ports, while
that of the piston is rapid. Thus, to a certain extent, the steam is
wire-drawn, so that the pressure in the cylinder is gradually reduced,
THE INDICATOR DIAGRAM.
133
and rounds off the diagram, rendering it difficult to define the
exact point of cut-off. To illustrate this more fully a diagram is
given from an engine fitted with Corlis's valve gear. This species
C
D
of gear shuts off the steam from
the cylinder very quickly. The
steam pressure in this example was
50 lbs. per square inch, the cylin-
ders had a diameter of 38 inches,
while the speed of the piston was
A
H*
Atmospheric Line
B
E
F
Fig. 77.—Indicator Diagram, from Corlis's Valve Gear.
500 feet per minute. With such high pressure and piston speed
the diagram approaches more closely to the theoretical figure than
that obtained from a valve actuated by the common eccentric.
All manufacturers strive to obtain a diagram from their engines as
near the theoretical curve as possible, not that the engine gives out
more power or indicated measure, but simply that the valve gear
is quick and effective. But as the power given off is measured by
the steam pressure and vacuum as taken from the diagram, no one
will dispute that a full figure in the diagram indicates less power
than a fine figure; on the contrary, more power must be developed,
the speed of piston being identical.
The indicator diagram is of great importance to the engineer, as
from it he can at once tell the steam pressure in the cylinder as
compared with that in the boiler, whether to ascertain the pressure
at the commencement of the stroke, or to discover at what part
of the stroke the steam is cut off,-to notice if "wire-drawing"
occurs, or a sharp cut-off, at what part of the stroke the steam
pressure falls to the atmospheric line, and whether the vacuum is
quickly and effectually maintained until the point of compression is
reached. By comparing the boiler and cylinder pressures, too, he
can tell what amount of condensation takes place in the pipes, and
adopt means to prevent it. In short-and in this lies the great
value of the indicator-by a proper diagram taken off the engine he
Atmospheric Line
13-2
Top
5.31
.14
5.5.
Atmospheric Line'
Do.
134
MODERN STEAM PRACTICE.
can tell how it is performing its duty. By means of the indicator
noting the steam pressure and vacuum acting on the piston, as well
as the velocity of the piston, at the time of trial, a true estimate of
the working of the engine is obtained, and thus steam users are
satisfied and disputes avoided.
Some authorities say Watt invented the indicator, others assert
that M'Naught successfully introduced it, although improvements
have since been made by others to suit modern high-speed engines.
The long stroke of the piston and spiral spring causing the pencil
to, as it were, "jump," made the diagram very irregular. To obviate
this defect the stroke of the piston was reduced, and the range of
the pencil multiplied with a lever parallel motion. Certainly the
improvement is very effective, and fully answers the object in view.
To suit the varying steam pressures it is found advisable to supply
springs of different degrees of power. Thus we have springs for
60 lbs. to the inch, and others 15 lbs. to the inch; and it will thus
be understood that when the 60 lb. spring is used, and the steam
High-pressure Cylinder.
30
Тор
36.
365
3.5
35
26
38.
22
Steam, 45 lbs.
Vacuum, 28½ inches.
Revolutions, 61.
Indicated horse-power, 298'05 H.P. cylinder.
10.5.
do.
310 88 L.P.
608'93
Low-pressure Cylinder.
Bottom
Figs. 78, 79.-COMPOUND ENGINE DIAGRams.
in the cylinders only 15 lbs., that the steam line on the diagram
will only be 4 inch from the atmospheric line, and with the vacuum
$2.5.
8.5.
ha" ht
9.15
39.
39.
14
27
Botton
26 85
24.25


THE INDICATOR DIAGRAM.
135
proportionately less also; consequently this reduction is obviated by
using the 15 lb. spring to suit the pressure in the cylinder of the
engine. For compound engines varying springs are necessary; but
it is considered that for ordinary marine engines, and in all engines
where the variation of the steam pressure is not great, that one
scale, and spring to suit, is quite sufficient, as a variety only creates
confusion. To show this more fully, take two diagrams from marine
engines of the compound type. The full figure shows the behaviour
of the steam in the high-pressure cylinder, and the lesser diagram
steam in the low-pressure cylinder. The same scale is used for
both (the diagrams being reduced from the original). It will be seen
that the diagram for the low-pressure cylinder is very lean, while
that for the high-pressure cylinder is well defined; and to make the
former bolder it is evident that a different spring and scale must
be adopted. This would improve the appearance of the low-pressure
diagram, but were the same scale and spring adopted for the high-
pressure diagram it would make the figure too large. The reading
of the high-pressure diagram is somewhat different from ordinary
high-pressure engines. The diagram in such cases would show the
pressure, commencing from the atmospheric line, while in the
example before us there is a slight back pressure. This is due to
the steam expanding into the large cylinder instead of into the
atmosphere, as with ordinary high-pressure engines.
We give examples in which both the high and low pressure cylin-
ders have diagrams taken from them. Both of the figures are
well defined, the scale for the high-pressure diagram being double
that for the low-pressure diagram, or the spring of double the power.
Thus it will be seen that it is quite necessary to have two sets of
springs for combined engines, so that there may not be so great a
difference in the diagrams, or that the figure be not too minute in
the one nor too bold in the other. When the operator is taking
diagrams off an engine he generally takes them for both ends on the
same paper, provision being made on the cylinder for doing so, the
small steam pipes fitted being in communication with both ends of
the cylinder. Thus the double figures are represented, one for the top
or OUT stroke, and another for the IN stroke of the piston. Care
must be taken that the area of the small pipe connecting both ends
of the cylinder is of sufficient size, not less than 34 inch in diameter,
so that the full pressure may be conveyed instantly to the piston of
the indicator. This pipe must be fitted with a hand-tap for each end
136
MODERN STEAM PRACTICE.
19.
Тор
18 5
16.5
13.4
13:5
Do.
do.
of the cylinder, so that when one of them is shut the other is open to
the indicator, and so on for each end of the cylinder. The examples

Τομ
High-pressure Cylinder.
Bottem
22:5
81
26.
305
Steam, 54 lbs.
Vacuum, 284 inches.
Revolutions, 60.
Indicated horse-power, 457 66 H.P. cylinder.
1171'41
Low-pressure Cylinder.
10 6
5. C
4
Figs. 80, 81.-COMPOUND Engine DIAGRAMS.
18 8.
12 5
illustrated are taken from combined engines of the vertical type;
the top and bottom of the cylinders are taken in the literal sense,
but the IN stroke of all engines-that is, when the crank is moving
inwards towards the cylinder-should be termed the IN stroke, and
when the crank is moving from the cylinder the OUT stroke is
signified: by adhering to these terms confusion is prevented.
Although the two preceding examples show back pressure on
the return stroke of the high-pressure piston, as delineated by the
diagrams, yet the expansion may be carried so far that the steam
may fall to the atmospheric line at the commencement of the stroke
of the large piston or low-pressure cylinder. The following dia-
grams show that this has taken place in the up or top stroke of the
high-pressure piston, the steam expanding to the top of the large
713'75 L.P. "
Bottom
11.84
12.19
37.5
22
ง
13,
25-10
21-51

THE INDICATOR DIAGRAM.
137
cylinder, or down stroke of the low-pressure piston.
For large
power this is an advantage, as the descent of the large piston is
High and Low Pressure Cylinders combined.
·Top

27.03
36.
36.
35-75
35.
4.5
34.
30
24:25.
18.5.
8 25
18 £
4.25
7-25
M2.5
12.25
7 12
Total indicated power, 1551.
Vacuum, 28 inches.
Revolutions, 33.
Bottom
Steam, 40 lbs.
95
17.
9.07
6.85
7.5

24.5
18-5
32
14.5
35.
12.
34.25
:0 25.
37-25
8-5.
38-25
7.5
s-te
6-5.
34-5
30.3
4.5
Figs. 82, 83.-COMPOUND ENGINE DIAGRAMS.
better balanced than if great steam pressure was admitted into the
cylinder. Again, when the steam is raising the small piston, it will
be seen that more steam is admitted, the cut-off taking place at a
later period. The diagram for the large cylinder shows steam pres-
sure above the atmospheric line for a very short period, which of
course is beneficially utilized in raising the large piston. These
two diagrams admirably show the action of the slide-valve, the
opening of the valve being greater for the IN stroke than for the
OUT stroke. This takes place with valves having the same amount
of cover on each steam end, actuated by an eccentric motion.
For reading off the steam and vacuum measures the diagram is
138
MODERN STEAM PRACTICE.
divided into ten parts on the atmospheric line; the tenth space
is subdivided, having one-half at each end, thus having ten ordinates
as shown; so by measuring each ordinate by the scale adopted, the
sum of the ordinates divided by 10 gives the mean pressure in the
cylinder. The power is run out by the usual formula—
Area of cylinder in square inches × mean pressure × speed of piston in feet per minute
33000
thus the real or indicated power of the engine is obtained.
The theoretical line of expansion of the steam in the cylinder is
only useful to show how nearly the diagram as taken by the indi-
cator approaches it. Without comparing the theoretical measure
with the diagram illustrated, we will explain how the theoretical
line of expansion is obtained. It is based on the natural law that
governs pneumatics, namely, that the pressure of an elastic fluid
varies inversely as the space into which it is expanded or com-
pressed. Thus if the steam in the cylinder is cut off at one-fourth of
the stroke of the piston, the space it occupies at the end of the
A
B
20
15
10.
stroke will be four times the volume of
the steam admitted into the cylinder; it
has expanded into four times its bulk,
and the pressure at the end of the stroke
will be only one-fourth of the original
volume admitted into the cylinder. To
find the pressure of the steam at the end
of the stroke, or at any intermediate
part of the stroke of the piston, multiply
the number of inches the piston has
travelled when the steam is cut off by
the pressure, dividing the result by the
total length of the stroke in inches, or
by that portion of it that is required.
Thus, supposing A B in the figure repre-
sented one-fourth of the stroke, B being the point of cut-off, and the
stroke of the piston is 36 inches, with a steam pressure of 20 lbs. per
square inch, we would have-

5
Strake
Fig. 84.-Theoretical Diagram.
9 × 20
36
9 x 20
27
9 × 20
18
5 lbs. steam pressure at the end of the stroke,
=6·66 lbs. steam pressure at three-quarters of the stroke,
= 10 lbs. steam pressure at one-half of the stroke.
THE INDICATOR DIAGRAM.
139
Thus there is one-fourth of the original pressure at the end of the
stroke, at three-fourths of the stroke one-third, and at half stroke
one-half of the original pressure. The initial pressure will be 20 lbs.
cutting off at one-fourth of the stroke of the piston, at one-half it
will be 10 lbs., at three-quarters 6.66 lbs., and the terminal pressure
will be 5 lbs. The stroke is delineated by the horizontal line in the
figure, and the vertical line represents the diameter of the cylinder
with the lbs. pressure marked off, the curved line from B to C being
the theoretical curve of expansion.
The diagram is taken as follows:-The mechanism attached to
the engine for actuating the roller on which the paper is fixed should
be of the simplest construction. A plain arm vibrating on a fixed
pin, having a slot at the downward end so as to take a pin fixed
to the crosshead or piston rod, for direct-acting engines, is by far
the simplest arrangement, the cord being attached to the top, a short
distance from the vibrating centre. A B in the figure represents the
full stroke of the piston, and C D the reduced stroke for the diagram.
The cord can be led away with suitable pulleys should the point of
attachment to the indicator diverge from the straight line, and it is
convenient to have a small pulley, fixed
on a ball-and-socket joint, placed next to
the indicator, so that the cord from the
vibrating lever can be placed at different
angles to that of the part interposed be-
tween the pulley and the roller on the
indicator. For vibrating cylinders, and
other arrangements, the cord can be
attached to the crosshead, and the motion
reduced with a large pulley, a band being
wound round it, the length of the band
being about equal to the stroke of the
engine. This pulley is fitted with a strong
spring, similar to a watch-spring, and the
strain is imparted to this spring instead of to the delicate one in the
instrument. Of course it is necessary to have a smaller pulley on
the same spindle, so as to reduce the stroke for the diagram. Any
part of the mechanism of the engine can, if corresponding with the
motion of the piston, be used as the point of attachment for the
cord, and simple levers for reducing the stroke, with direct means
of guiding the cord to the pulley on the roller of the indicator, is

A
Fig. 85.-Lever for actuating the
Roller of Indicator.
140
MODERN STEAM PRACTICE.
far preferable to intermediate pulleys for taking the motion of the
reciprocating part to which the cord. is fixed. The cord is attached
to the instrument with a hook and running eye; thus the exact length
of the cord is easily adjusted. The indicator should, if convenient,
be fitted to each end of the cylinder, and a diagram taken off for
both ends, without having a small pipe in communication with both
ends of the cylinder; but when a pipe is fitted it must be of suffi-
cient size, not less than 3/4 inch in diameter, so that the pressure
may be the same for both ends. If the pipe is made too small, the
friction of the steam on the internal circumference materially tends
to reduce the pressure on the small piston of the indicator. For
vertical engines the plug-tap, for admitting the lubricant into the
cylinder for the lubrication of the piston, is provided with a screwed
part for taking the indicator, while another plug-tap is fitted to the
bottom of the cylinder. These taps are screwed into the covers or
ends of the cylinder. For horizontal engines they can be placed on
and screwed into the metal surrounding the steam ports; but it
is best when they are fitted into the cylinder itself, or at each end
on the covers, or otherwise, as the rapidity with which the steam
flows through the passages tends to decrease the pressure acting
on the indicator piston, although the actual difference may be very
minute. Care must be taken that no abrupt bends are made in the
small pipe connecting the top and bottom of the cylinder with that
of the indicator. Of course there must be a small plug-tap fitted
to the pipe, so that the communication from the top is shut off when
the operator wishes to take a diagram from the bottom end of the
cylinder, and vice versa. It is essential that the indicator should
be placed vertically, so in some instances large easy bends on the
small pipe are admissible, but in all cases where bends are used
there must be provision made for running off the water collecting
from condensation.
When all is in readiness-the engine going at its accustomed
number of revolutions, and all water in the cylinders and pipes
ejected, with all the run-off valves shut-the operator turns on the
steam to the indicator, the handle for doing so being provided with
a stop, so as to have the passage in the plug-tap full open. When
the instrument has made a few strokes the cord can be unhooked
-the diagram has been taken; and it is only necessary to note
on the card the pressure of the steam in the boiler, inches of mercury
in the gauge, the number of revolutions, and the scale adopted.
THE EXPANSION OF STEAM.
141
THE EXPANSION OF STEAM.
With a given pressure of steam, and the cut-off taking place at
any part of the stroke of the piston, to find the mean pressure
exerted on the piston during the stroke, by means of the following
table of hyperbolic logarithms. Rule:-Divide the length of the
stroke of the piston by the length of the space when the steam is
cut off from the cylinder; find in the table the logarithm of the
number nearest to the quotient, and add 1 to it: the sum is the ratio
of the gain. Then find the terminal pressure by dividing the initial
pressure by the proportion of the stroke during which the steam is
admitted into the cylinder, and multiply by the logarithm + 1, as
above; the product will be the mean pressure exerted on the piston.
Example. Suppose the length of the stroke to be 24 inches,
initial pressure 40 lbs. per square inch, and the steam to be cut off
at 6 inches from the commencement of the stroke, we have—
Then
24÷6=4; hyp. log. of 4 is 1*386+1=2·386.
40÷410 x 2.38623.86 lbs. mean pressure.
HYPERBOLIC LOGARITHMS.

Number. Logarithm. Number. Logarithm. Number. Logarithm. Number. Logarithm.
1'05
*048
2'05
717
3'05
1'115
4'05
I'398
I'I
*095
2'I
741
3'I
1'131
4'10
I'410
1'15
*139
2°15
*765
3'15
I'147
4°15
1°423
I'2
•182
2'2
*788
3'2
1*163
4'2
I'435
1'25
*223
2°25
•810
3°25
1*178
4'25
I'446
1'3
•262
2'3
•832
3'3
I'193
4'3
1*458
1'35
*300
2.35 •854
3'35
I'208
4'35
I'470
1'4
*336
2.4
•875
3'4
I'223
4°4
1*481
1'45
'37 I
2.45
•896
3'45
1*238
4'45
I'492
1'5
*405,
2'5
'916
3'5
1'252
4'5
I'504
1'55
*438
2'55
*936
3'55
I'266
4'55
1'515
1.6
*470
1.65
*500
1'7
*530
1'75
*559
2 2 2 2
2.6
*955
3.6
I'280
4.6
I'526
2.65
*974
3'65
I'294
4·65
I'536
2°7
*993
3'7
1'308
4'7
I'547
2.75
I'OI I
3'75
I'321
4.75
1*558
1.8
*587
2.8
I'029
3.8
I'335
4.8
1'568
1.85 •615
2.85
I'047
3.85
I'348
4.85
I'578
1'9
•641
2'9
1'064
3'9
1*360
4'9
1*589
I'95
2'0
•667 2.95 1'081
3'95
I'373
4'95
I'599
•693 3°0
I'098
4'0
1*386
5°0
1.609
142
MODERN STEAM PRACTICE.
HYPERBOLIC LOGARITHMS-Continued.

Number. Logarithm.
Number. Logarithm. Number. Logarithm. Number. Logarithm.
5'05
1*619
6.7
I'902 8.35
2'122
9'95
2*297
5 I
I'629
6.75
I'909
8.4
2'128
ΙΟ
2*302
5°15
1.638
6.8
1'916
8.45
2'134
5.2
1*648
6.85
I'924
8.5
2'140
II'
2*397
5°25
1*658
6'9
1'931
12'
2.484
5'3
1.667
6'95
1'938
5°35
1.677
7'0
I'945
5'4
1.686
∞∞∞
8:55
2'145
8.6
2'151
8.65
2'157
15'
5'45
1*695
7'05
1'953
8.7
2.163
5'5
1*704
7'1
1*960
7:15
1*967
∞ ∞ ∞
8.75
2.169
17'
8.8
2'174
18.
5°55
1713
7°2
2'974
8.85
2'180
5.6
I'722
7:25
1981
8.9
2.186
5'65
I'731
7'3
1'987
8.95
2'191
5'7
I'740
7'35
I'994
9'0
2'197
24
.575
I'749
7'4
2'001
28.
5.8
I'757
7'45
2'008
9'05
2'202
5-85
1'766
7.5
2'014
9'1
2'208
5'9
I'774
9'15
2.213
40*
5'95
1*783
7'55
2'021
9'2
2.219
6'0
I'791
7.6
2'028
9'25
2'224
48
7.65
2'034
9'3
2*230
6.05
1.800
7'7
2'041
9'35
2'235
6'1
1.808
7'75
2'047
9'4
2*240
6.15
1.816
7.8
2'054
9'45
2*246
6'2
1*824
7.85
2'060
9'5
2'251
6.25
1.832
7.9
2.066
6.3
1.840
7'95 2'073
9'55
2*256
6.35
1*848
8.0
2'079
9.6
2'261
6.4
1.856
9'65
2'266
6.45
1.864
8.05
2'085
9'7
2*272
6.5
1.871
8.1
2'091
9'75
2°277
8'15 2*098
9.8
2.282
6:55
1.879
8.2
2'104
9.85
2.287
6.6
1.887
8:25
2'110
9'9
2'292
100'
miting A♡ào n♡ to no 288
2'564
2*639
2'708
2'772
2·833
2.890
19*
2*944
20*
2*995
3*178
3'332
32'
3'465
36.
3'583
3.688
44*
3'784
3.871
52'
3'951
56.
4'025
60°
4'094
64
4'158
68.
4'219
72°
4*276
76.
4'330
80°
4°382
84
4'430
88.
4'477
92*
4'521
96.
4'564
4605
6.65
1.894
8°3
2'116
TABLE OF HYPERBOLIC LOGARITHMS,
TO SUIT GIVEN RATIOS OF EXPANSION.

Portion of the Stroke
at which the
Steam is cut off.
Ratio of
Expansion.
Hyperbolic
Logarithm.
Portion of the Stroke
at which the
Steam is cut off.
Ratio of
Expansion.
Hyperbolic
Logarithm.
T
3
10
TV
1
NNNWAU∞0
2'3025851
6
10
1'66
*5068176
2'0794414
1.6
*4700036
1*6094379
I'42
*3506568
1*3862943
I'33
*2851788
3'33
I'2029722
I'25
*2231435
2.66
*9783260
I'14
*1310284
2.5
'9162907
*6931472
9
I'II
*1043600
THE EXPANSION OF STEAM.
143
PROPERTIES OF STEAM AND OTHER GASES.
Pressure, density, and temperature are the important character-
istics of steam, as they are the properties which regulate the econo-
mical production and application of steam power. Steam as a gas
is amenable to the common laws of gaseous fluids; and, according
to those laws, the pressure, the density, and the temperature bear
fixed relations to one another. The influence of temperature on
the expansion of gases under constant pressures is nearly uniform
for equal increases of temperature, and is nearly the same for
different gases. The expansion of air may be assumed to represent
that of other gases, and it is found by experiment that air expands
th of its volume at 32° for each degree of temperature communi-
cated.
490
The relation betwixt pressure and volume under constant tem-
peratures is also sensibly uniform within ordinary limits. For an
expansion of four times the initial volume, experiments on various
gases show a corresponding diminution of pressure in the ratio of
I to 3'99, or sensibly 1 to 4.
The total or constituent heat of saturated steam is at all temper-
atures separable into two parts-latent and sensible heat. The
sensible heat is that indicated by the thermometer, and it varies as
the pressure. The latent heat absorbed during the conversion of
water into steam constitutes by far the greater proportion of the
total heat. Thus for saturated steam we have the following
values:-
Pressure.
14'7 lbs.
90 lbs.
...
Temperature.
212°
320°2
...
Latent Heat.
966°.6
891°.4
Total Heat.
1178°.6
1211°.6
The difference of total heat is, in this case, 33° in favour of the
higher pressure. It appears, then, that by expansion perfectly dry
steam becomes slightly surcharged, in virtue of the excess of total
heat due to higher pressures; and should it contain a portion of
water in a state of suspension, a small part of this water must be
evaporated during expansion.
For steam, and for gases generally, the following ratios may be
adopted:
With a constant temperature, the pressure varies simply as the
density, and inversely as the volume.
With a constant pressure, expansion is uniform under a uniform
+
144
MODERN STEAM PRACTICE.
3th
90
accession of heat, at the rate of th of the volume at 32° for each
degree of heat. If then we add (490° - 32°) 458° to the indicated
temperature, the sum is directly as the total volume by expansion,
and inversely as the density.
With a constant volume, or density, the increase of pressure is
uniformlyth of that at 32° for each degree of temperature
acquired, and adding, as in the previous case, 458° to the indicated
temperature, the sum is directly as the total pressure.
Though the law of the formation of saturated steam has been the
subject of much and varied experimenting, it can as yet be reached
only by the aid of empirical formulas. The weight of a cubic foot
of steam at 212°, raised from water under the ordinary atmospheric
pressure, namely, 147 lbs. per square inch, is '03666 lbs., and this
is an expression of the density of the steam, as weight is a direct
measure of mass or quantity of matter. A cubic foot of pure water
at 62° weighs 62 321 lbs.; and the ascertained relative volume of
saturated steam produced under the atmospheric pressure is 1700
times that of the water at 62° of which it is made; therefore
of the weight of a cubic foot of this water expresses the weight of
an equal bulk of the steam so formed, and it is in this way that the
weight of steam already noted was determined. From these data,
with the aid of the ratios already established, the relations of pres-
sure, volume, and temperature may be found.
th
To find the relative volume of steam.—Add 458 to the temper-
ature; divide the sum so found by the total pressure, and multiply
by 373. The product is the relative volume.
To find the total pressure of steam.—Add 458 to the tempera-
ture; divide the sum by the relative volume, and multiply by 37°3.
The product is the total pressure.
To find the temperature of steam.-Multiply the total pressure
by the relative volume, and divide by 37°3; from the quotient sub-
tract 458. The remainder is the temperature.
To find the weight of steam.-Divide 62 321 by the relative
62.321
volume; the quotient is the weight per cubic foot.
Motion of Steam.-It is well understood that steam unimpeded
moves with great velocity from one locality to another, under
slight differences of pressure. Steam may flow into a vacuum, or
it may deliver itself into the atmosphere, or, further, it may flow
into steam of less density. The conditions of its flow in the first
and in the other cases are different; as in the second case, for
THE EXPANSION OF STEAM.
145
example, 14'7 lbs., or approximately 15 lbs., of its total pressure go
for nothing in counteracting the atmospheric resistance, before the
slightest motion is possible. Thus, in the second case, at all pres-
sures the motion of the steam is due solely to the difference of its
inherent pressure and that of the atmosphere. The ordinary
method of estimating the velocity of the flow of gases or liquids
under pressure is founded on the laws of falling bodies; it is a very
beautiful application of the law of gravitation, and it yields results
simply and directly. A quantity of steam confined in a boiler, of
a given pressure and known density, would flow into a vacuum
through an opening from the boiler with a certain initial velocity,
and this velocity would be the same as that which would be given
to a liquid of the same weight as the steam, flowing out under the
same pressure. The velocity of efflux referred to, when unretarded
by physical obstructions, is precisely that which the liquid would
acquire in falling through the height of a column of the same liquid
I inch square, equal in weight to the pressure of the steam per
square inch. By the laws of falling bodies it is known that the
velocity, v, acquired in falling freely through any height, h, is equal
to eight times the square root of the height, or v=8√h. Thus the
velocity of efflux into a vacuum is determinable, and the following
is the method of finding it:-
Given, the total pressure of the steam, which we suppose to be
saturated, as in all ordinary cases it is; divide the pressure per square
inch by the weight of a cubic foot of the steam; the quotient is the
height of a uniform column of steam I foot square, equal in weight
to the pressure of the steam per square inch. Multiply the quotient
as found by 144, the number of square inches in a square foot of
base, and the product is the height of a 1-inch column of the steam,
equal in weight to the given pressure of that steam on the square
inch.
To find the velocity with which saturated steam flows freely into
a vacuum.—Divide the total pressure per square inch in lbs. by the
weight of a cubic foot of the steam in lbs., and find the square root
of the quotient; multiply this result by 96. The product is the
required velocity in feet per minute.
To find the velocity with which saturated steam freely flows into
the atmosphere, or into steam of inferior pressure.-Take the differ-
ence of pressures of the two steams for the effective pressure, divide
the effective pressure in lbs. per square inch by the weight of a cubic
10
146
MODERN STEAM PRACTICE.
foot of the denser steam in lbs., and multiply the square root of the
quotient by 96. The product is the required velocity in feet per
second.
To find the pressure to which saturated steam is reduced when it
flows freely, with a given velocity, from one vessel into another.—
Multiply the square of the velocity in feet per second by the weight
in lbs. of a cubic foot of steam of the initial total pressure, and divide
the product by 9216. The quotient thus found expresses the differ-
ence of the initial and final pressures; subtract this quotient from
the given initial pressure, and the remainder is the reduced total
pressure sought.
Of the loss of pressure generally which accompanies the movements
of steam.-It has been seen that a reduction of pressure, great or
small, necessarily accompanies even the free motion of steam, the
difference being consumed in communicating that motion. By far
the heaviest losses are, however, due to the resistances of bends and
surface friction of pipes, &c. It has been found from experiment on
stationary engines and boilers that the losses on various accounts
follow these general ratios.
The difference of pressures in the boiler and cylinder is—
Ist. As the density of the steam, and as the square of the speed
of piston.
2d. As the square of the ratio of area of piston to cross section of
steam pipe.
3d. As a factor dependent on bends and friction.
The permanent difference of pressure caused by passing through
a stricture in a pipe, otherwise of uniform diameter before and
behind the stricture, is as the density of the steam, and as the
square of the difference of speeds through the larger and smaller
parts of the pipe.
The friction of a fluid through a pipe appears to vary more or
less-
Ist. As the length directly.
2d. As the diameter inversely.
3d. As the square of the velocity directly.
4th. As the density directly.
THE EXPANSION OF STEAM.
147
Pressure in
lbs. per
above the
in degrees of
Total Heat
in degrees of
pressure
Fahrenheit.
Fahrenheit.
of the
atmosphere.
I cubic foot
of Steam,
according to
Pambour.
PROPERTIES OF SATURATED STEAM AT DIFFERENT
square inch Temperature
PRESSURES.

Cubic inches
of water to
produce
Volume of Steam produced
I
Weight of
I cubic foot
of Steam
in lbs.
by 1 of water.
Pambour.
Other
Authorities.
1 234 N∞ a
I
216'3
1179'9
I'09
1572
1515
*0397
219'5
1180'9
1.16
1487
1431
*0419
222'5
1181.8
1*22
1410
1357
'0442
225'4
11827
1.28
1342
1290
*0465
2280
1183'5
I'35
1280
1229
*0487
230'6
1184'3
1'41
1224
1174
*0510
233'I
1185'0
1'47
1172
1123
*0532
8
235'5
11857
1'53
1125
1075
*0554
9
237'9
1186.5
I'59
1082
1036
*0576
ΙΟ
240'2
1187.2
1.65
1042
996
*0598
II
242'3
1187'9
1'71
1005
958
*0620
12
244'4
1188.5
I'77
971
926.
*0642
13
246'4
1189'1
1.84
939
895
*0664
14
248.4
1189.7
1'91
909
866
*0686
15
16
17
18
19
36 7∞0 a
250'4
1190°3
I'95
881
838
*0707
252'2
1190*8
2'02
855
813
'0729
254'I
1191'4
2'07
830
789
'0751
255'9
1192'0
2'13
257'6
1192'5
2'19
20
259'3
1193'0
2.25
21
260°9
1193'5
2°31
22
262'6
1194'0
2*37
23
264°2
1194'5
2'43
24
265.8
1195'0
2'49
25
267'3
1195'4
2'55
26
268.7
I 195'9
2'61
2 2
27
270'2
1196*3
2.67
SO WH NORE OF
807
767
'0772
785
746
*0794
726
*0815
745
707
*0837
727
688
*0858
709
671
*0879
693
655
*0900
640
*0921
625
'0942
611
*0963
28
271.6
1196.8
2'72
634
598
*0983
29
2730
1197'2
2978
585
'1004
30
274'4
1197.6
2.84
608
572
*1025
31
2758
1198 0
2.89
595
561
*1046
32
277'I
1198 4
2'95
584
550
*1067
33
278.4
1198.8
3'01
573
539
*1087
34
279'7
1199°2
3'07
562
529
*1108
35
281.0
1199.6
3°13
552
518
*1129
36
282.3
I 200'0
3'18
542
509
*1150
37
283'5
1200'4
3*24
532
500
*1171
38
284'7
1200'8
3'30
523
491
'1192
39
285'9
1201'I
3°36
514
482
'1212
40
287'1
1201'5
3'41
506
474
*1232
4I
288.2
1201.8
3'46
498
466
*1252
42
289'3
I202'2
3°52
490
458
*1272
43
290'4
1202'5
3'58
482
451
*1292
44
291.6
1202'9
3.64
474
444
*1314
45
292'7
1203'2
3'70
467
437
*1335
1
148
MODERN STEAM PRACTICE.
Pressure in
lbs. per
PROPERTIES OF SATURATED STEAM-Continued.

square inch Temperature
above the
in degrees of
Total Heat
in degrees of
pressure
Fahrenheit.
Fahrenheit.
of the
atmosphere.
Cubic inches
of water to
produce
I cubic foot
of Steam,
according to
Volume of Steam produced
by I of water.
Weight of
I cubic foot
of Steam
in lbs.

Pambour.
Pambour.
Other
Authorities.
61
62
63
64
65
67
68
69
!g8%°$np82ggཉnརྒྱུུ་ུཤཱཤྩ b*ཅི
46
293.8
1203'6
3'75
460
430
*1356
294.8
1203'9
3.81
453
424
*1376
295'9
1204'2
3.86
447
417
*1396
296'9
1204'5
3'92
440
411
*1416
50
298'0
1204.8
3'98
434
405
*1436
299'0
1205'1
4'03
428
399
*1456
52
300'0
1205'4
4'09
422
393
*1477
300'9
1205'7
4'14
417
388
*1497
301'9
1206'0
4'20
4II
383
302'9
1206'3
4'25
406
378
38
*1516
*1535
303'9
1206'6
4'30
401
373
*1555
304.8
1206'9
4'36
396
368
*1574
305'7
1207'2
4'41
391
363
*1595
306.6
1207'5
4'47
386
359
'1616
бо
307'5
1207.8
4'53
381
353
*1636
308'4
1208'0
4'58
377
349
*1656
309'3
1208°3
4'64
372
345
*1675
310'2
1208'6
4.69
368
34I
*1696
311'I
1208'9
4'74
364
337
*1716
312'0
1209'I
4.81
359
333
*1736
312.8
1209'4
4.86
355
329
*1756
313.6
1209'7
4'92
35I
325
*1776
314'5
1209'9
4'96
348
321
*1795
315'3
1210'I
5'02
344
318
*1814
70
316'1
1210'4
5'08
340
314
•1833
316'9
1210'7
5°12
337
311
•1852
72
317.8
12109
5'18
333
308
*1871
73
318.6
I2II'I
5'23
330
305
*1891
74
319'4
1211'4
5°30
326
301
*1910
75
320'2
1211'6
5'43
323
298
*1929
76
321'0
1211.8
5'40
320
295
*1950
77
321'7
1212'0
5'45
317
292
*1970
78
322'5
1212'3
5'52
313
289
*1990
79
323'3
1212'5
5'57
310
286
'2010
80
324'I
1212'8
5'62
307
283
*2030
81
324.8
1213'0
5.66
305
281
*2050
82
325.6
1213'3
5'72
302
278
*2070
∞∞∞∞ ∞ ∞ ∞
83
326.3 1213'5
5'77
299
275
*2089
84
327'I
1213'7
5.83
296
272
*2108
85
327.8
1213'9
5.89
293
270
*2127
86
328.5
1214'2
5'95
290
267
*2149
87
329'I
1214'4
6:00
288
265
2167
88
329'9
1214'6
6:06
285
262
*2184
89
330'6
12148
6.10
283
260
*2201
90
331'3
1215'0
6'14
281
257
*2218
91
331'9
1215'2
6.21
278
255
*2230
92
332·6
1215'4
6'26
276
253
*2258
THE EXPANSION OF STEAM.
149
PROPERTIES OF SATURATED STEAM—Continued.
Pressure in
lbs. per
square inch
above the
pressure
Cubic inches
of water to
Temperature
Total Heat
in degrees of❘ in degrees of
Fahrenheit.
Fahrenheit.
produce
I cubic foot
Volume of Steam produced
by 1 of water.
of Steam,
Weight of
I cubic foot
of Steam
in lbs.
of the
according to
Pambour.
atmosphere.
Pambour.
Other
Authorities.
93
333'3
12156
6'32
273
251
*2278
94
334'0
1215.8
6.37
271
249
*2298
95
334.6
1216'0
6.42
269
247
*2317
96
335'3
1216'2
6.47
267
245
*2334
97
336'0
1216'4
6.52
265
243
*2351
98
336'7
1216.6
6.57
263
241
*2370
99
337'4
1216.8
6.62
261
239
*2388
100
338°0
1217'0
6.67
259
237
*2406
ΙΟΙ
338.6
1217'2
6.72
257
235
*2426
102
339'3
1217'4
6.77
255
233
•2446
103
339'9
1217'6
6.82
253
231
*2465
104
340'5
1217.8
6.88
251
229
*2484
105
341'I
12180
6.93
249
227
'2503
106
3418
1218.2
6.99
247
225
*2524
107
342'4
1218'4
7'04
245
224
*2545
108
343'0
1218.6
7.11
243
222
*2566
109
343'6
1218'7
7.17
241
221
*2587
ΙΙΟ
344°2
12189
7°23
239
219
•2608
III
344'8
1219'I
7:26
238
217
*2626
I12
345'4
1219°3
7°32
236
215
*2644
113
346'0
1219'4
7.38
234
214
•2662
114
346.6
1219.6
7'45
232
212
*2680
115
347°2
1219.8
7.48
231
211
*2698
117
348'3
1220'2
7'57
228
208
*2735
119
349'5
1220'6
7.68
225
205
*2771
121
350'6
1220'9
778
222
202
*2807
123
3518
1221'2
7.84
219
199
*2846
125
352'9
1221'5
8.0
216
197
•2885
127
354'0
1221'9
8.11
213
194
*2922
129
355°0
1222'2
8.22
210
192
*2959
131
356'1
1222'5
8.3
208
189
*2996
133
357'2
1222'9
8:42
205
187
'3033
135
358°3
1223°2
8.51
203
184
*3070
145
363'4
1224.8
9'04
191
174
*3263
155
368.2
1225'I
9'54
181
164
'3443
165
372'9
1227'7
10'04
172
155
*3623
175
377'5
1229'1
10'53
164
148
*3800
185
3817
1230'3
II'O
157
141
*3970
Note.—According to Rankine and others, the relative volume of steam is less than has
been commonly assigned to it by Pambour, following the laws already explained; Pam-
bour having treated steam as a permanent gas, instead of as being, what it is in actual
practice, highly saturated.
STATIONARY ENGINES.
PUMPING ENGINES FOR MINES.
One of the earliest and still a principal use of the steam-engine

TURTHIAMA
H
Fig. 86.—Cornish Engine.
is for pumping the water out of the mines from which we obtain
STATIONARY ENGINES.
151
"
our coal, ironstone, and other ores. There would be great difficulty
in reaching those vast stores of hidden treasure without the power-
ful aid of the steam-engine, which enables us to overcome many of
the risks and difficulties encountered in mining operations.
The single-acting beam engine is generally adopted for pumping
the water from great depths. These great beams of cast-iron-
and in some cases of wrought-iron plates, stiffened with angle or
T-iron—are supported by pillow blocks, resting on a wall of masonry
carried up to a convenient height above the top of the cylinder.
The beam is in two halves, with gudgeons between them, and is
connected to the piston-rod of the steam cylinder by a crosshead


ANN22
E
E
Lam
F
A
A
D
E
G
Fig. 87.-Crosshead and Side-links of Parallel Motion for Piston-rod of Cornish Engine.
A, Crosshead. B, Piston rod. c, Loose collar. D, Key. E, Links. F, Beam gudgeon.
G, Bearings for parallel bars.
and parallel motion; and in some instances the crosshead of the
piston-rod works in suitable cast-iron guides, and is connected to
the beam gudgeons by plain links. This motion is not so expen-
sive in first cost, and the wear and tear is greatly reduced.
The cylinder A is a plain casting with port C cast on at the top,
incased in an outer cylinder B, to which it is bolted, flanges being
cast on each at the top for that purpose. The outer casing or
cylinder is bolted to a separate bed-plate D at the bottom. A space
is left between the two cylinders for the admission of steam from
the boiler; and they are made steam-tight at the bottom, raised strips
152
MODERN STEAM PRACTICE.
being cast on each, and turned slightly conical. A small branch
pipe is cast on the outer casing at the top for the admission of the
B
A
Ꮐ
H
C
steam, which forms a steam-jacket
around the internal cylinder, and
one at the bottom to run off the
water from the condensation of
the steam in the annular space
between the two cylinders; each
of these pipes is fitted with a plug
tap. The bed-plate D is a strong
casting, with port E cast on, and is
bolted down through the founda-
tions with six holding-down bolts.
There is a bottom plate F fitted.
into and made tight by a rust joint.
The cylinder cover G is an open
casting, with separate covering
plate H, and has the stuffing-box I
cast on, which is fitted with the
usual lantern brass K, and gland L,
for the packing of the piston rod.
The piston M is also an open cast-
ing, ribbed at the under side, and
fitted with a junk ring N, having
bolts with nuts recessed in the
body of the piston; there are two
spring packing rings o, of cast iron,
accurately turned and made per-
fectly steam-tight. The piston rod
is let in through the under side,
and is turned conical, fitting into
a corresponding hole in the piston,
the rod being secured with a cot-
ter P at the top. The cylinder is
fitted with a ring Q of wood at the bottom, to deaden the shock
should the piston descend so far.

N
D
M
F
Fig. 88.-Cylinder, Piston, &c.
E
The pump rods are directly attached to the gudgeon at the other
end of the beam by suitable wrought-iron straps, jib, and key. The
end of the pump rod is covered by plates on each side, fastened by
cross bolts passing through and through, to prevent the wood strip-
STATIONARY ENGINES.
153
ping. The pump rods of timber bend to the versed sine described,
but being of great length the motion is but little felt.
The pumps are of two kinds-lifting or bucket pumps and for-

B
B
Q..
D


B
O O O O
A
E

00
O o O o
E

Fig. 89.-Pump Rod of Cornish Engine.
A, Wooden rod. B B, Wrought-iron
straps, with jib and cotter. c, Side plates.
D, Beam gudgeon.
Fig. 90.-Lifting Set.
Bucket, 18 inches in diameter.
A, Suction pipe. B, Suction-valve chest.
c, Working barrel.
D, Delivery-valve chest.
E, Wrought-iron strap shrunk on.
cing or plunger pumps; and in some instances a combination of the
solid bucket and plunger pump is adopted.
In the former of these, as indeed in all pumps, the water is forced
up the pipe by the pressure of the atmosphere, when a few
strokes of the pump bucket have caused a partial vacuum in the
pump barrel. The suction valve should be placed somewhat less
154
MODERN STEAM PRACTICE.
than 30 feet from the surface of the water in the shaft or pit to be
drained, 28 feet being a convenient height; that is to say, when the
water passes through the valve to the top of a solid bucket. But
when a hollow bucket is adopted, with the discharge valve fitted
thereto, the distance from the level of the water to the height to
which the bucket ascends in the pump barrel should not exceed
28 feet; consequently the suction
valve in the pipe will be lower down.
In the former of these arrangements
the water is drawn through the suc-
tion valve on the down stroke of the
solid bucket, and in the up stroke
the suction valve closes, and the
water is discharged through a valve
placed in the stand pipe above the
suction valve, until the return or
down stroke of the bucket, when the
discharge valve closes simply by
the weight of water upon it; the

F
Ꮐ
E
0
B
88
C
Fig. 91.-Forcing Set. Plunger 18 inches in diameter, arranged with one door for each valve.
A, Suction pipe. B, Suction-valve seating. c, Delivery-valve seating. D, Plunger. E, Air valve.
F, Stand pipe. G, Stuffing-box piece and gland.
suction valve then opens, and the pump barrel is filled as before;
and so on. With the hollow bucket the water is drawn through the
suction valve in like manner, but with this difference, that the
STATIONARY ENGINES.
155
bucket is ascending, consequently it is discharging and drawing the
water into the pump barrel at the same time, and the down stroke
of the bucket simply allows the water above the suction valve to
pass through the valve fitted to the bucket, to be again discharged
as already explained.
The force or plunger pump is just a vertical arrangement of that
type universally used as

G
D
F
C
feed pumps for all classes
of engines, the upward
stroke of the plunger, after
the vacuum is fully esta-
blished in the pump barrel,
drawing the water through
the bottom valve, and dis-
charging it through the top
valve fitted to the stand
pipe. The height to which
the bottom of the plunger
ascends should not exceed
28 feet, as in the previous
example; and the suction
and discharge valves should
be arranged below that
height. It is evident that
this pump will discharge a
column of water equal to
the area of the plunger and
length of its stroke, as in-
deed do all pumps, whether
they are lifting or forcing
sets. It is found advisable,
however, to fit a small valve
opening outwards, so as to
discharge the air collecting
at the top of the barrel,
and consequently a little
water is ejected at each
stroke. The plunger is a plain cylinder turned all over, and secured
directly to the wooden pump rod; the rod is turned, and then
driven tightly in and wedged with iron wedges at the ends, a collar
B
Fig. 92.-Forcing Set. Plunger 23½ inches in diameter,
arranged with one door for both valves.
A, Suction pipe. B, Suction-valve seating. c, Delivery-valve
seating. D, Plunger. E, Branch from air valve. F, Stand
pipe. G, Stuffing-box piece and gland.
156
MODERN STEAM PRACTICE.
being left at the top. All the flanges of the pump fittings should
be bracketed, and the valve- chest doors strongly ribbed in the
casting, and secured with deep nuts, the hoop bolts passing round
the valve chest, the flanges having strong wrought-iron hoops shrunk
The arrangements shown are very compact; the bottom
of the pump resting on the cistern placed high up above the lifting
set, the suction pipe of the latter (Fig. 90) being as long as possible
in order to make provision for inspecting the valves in the event of
on.
E
D
F
the water accumulating or rising at
the bottom of the shaft; the valves
also are so arranged that in the
event of the water rising above the
doors they can be drawn out from
the surface for inspection, and again
placed in.
In the combination of the solid
plunger and bucket pump the water
delivery is equalized; the barrel is
accurately bored out, and fitted
with a gland at the top for the
plunger to pass through, making it
perfectly air and water tight. The
area of the plunger is exactly one-
half of the area of the pump barrel,
consequently at the down stroke,
the barrel being full of water, it is
forced through the valve in the
bucket; and the water being forced
into one-half of the space, one-half
of the contents of the pump is dis-
charged in the down stroke and
one-half in the up stroke. The
plunger in this arrangement can be
made to act as an air vessel, thus
the flow of the water is very regu-
lar, and the shock of the valves be-
comes somewhat easier. This pump
can be arranged with a solid piston,
having suction and delivery valves as in ordinary pumps. There
must, however, be a passage in connection with the top of the barrel

Fig. 93.-Combined Plunger and Bucket Pump.
A, Suction pipe. B, Clack or suction valve.
c, Bucket. D, Plunger. E, Stand pipe.
F, Stuffing-piece box and gland.
STATIONARY ENGINES.
157
of the pump and the discharge pipe, and in this way the water at
the down stroke of the piston, being forced through the discharge
valve, one-half flows above the piston and the other half is dis-
charged up the stand pipe; until the up stroke takes place, when
the other half is also discharged. Thus in the up stroke the piston
is drawing the water up the suction pipe, filling the pump barrel
and discharging one-half of its cubical contents at one and the same
time; while during the down stroke the water is forced out of the
barrel, one-half of it fills the vacuity above the piston and the other
half is discharged. It will thus be seen that a smaller stand pipe
will suffice for this class of pump; and where the flow of water from
the pump requires to be uniform, this arrangement has a decided
advantage over the foregoing examples. At the bottom of the air
pipe a suction piece is fitted, having a number of holes of about
I inch in diameter, to prevent extraneous matter lodging in the
pump and destroying the proper action of the valves. All classes
of pumps are so fitted, and lifting sets have in some cases a foot
valve placed at the bottom of the air or suction pipe.
In connection with the stand pipe and suction pipe in lifting
arrangements with solid bucket a small pipe is fitted, having a
branch to the space between the suction and the top valve. The
object of this pipe is to allow water from the stand pipe to flow
into the pump and suction pipe, as at times, when the pumps
are not working, the water would flow past the valves, and were
not the air in the pipes ejected by the water flowing in from the
stand pipe, the shock to the machinery would be very great. There
are three plug valves, one on each end of the small pipe and
branch, to shut the water off when the pipe and pump are full,
which is known by the small pet plug tap placed below the dis-
charge valve passing water-a sure sign that all the air is expelled.
At the bottom of the suction pipe a loaded valve is placed a little
above the water in the well, or sump, the technical term for the
space below the roadway at the pit bottom where the water is col-
lected. This valve is loaded to a pressure of 15 lbs. per square
inch, and is used to test the action of the valves. Should the suction
valve be passing water when the solid bucket is lifting, the valve
will discharge water, simply because the water sucked up the air
pipe is forced down again, and as it cannot pass the foot valve when
in good working order, it naturally escapes at the loaded valve,
where the pressure on the valve is not so great as on the discharge
158
MODERN STEAM PRACTICE.
valve, subjected as it is to the full head of water in the stand or
delivery pipe. This valve can also be used to test if the discharge
valve closes properly, the engine being stopped for that purpose;
the plug tap above the suction valve and the one on the air pipe are
opened, and a communication through the small pipe already men-
tioned is effected between the pump and the suction pipe. If the
discharge valve passes water the loaded valve at once lifts, being
acted on by the full hydrostatic head in the delivery pipe. This
valve is therefore of great use in testing the efficient working of
the pump.

حرا
The pump valves are gen-
erally of the double or treble
beat kind. They are intro-
duced to obviate the objec-
tions inherent in the flap
and conical type of valve,
due to the great lift neces-
sary in the former to pass
the water, and also on ac-
count of the full head of
water in the stand pipe,
which, acting on a large
area, causes the valve to shut
with great violence, tending
to shatter the machinery
and foundations. This evil
is greatly obviated in the
double-beat valve, as it is
adapted to pass a large body
of water with a moderate
lift, which is the principal
object to be attained in all
valves subjected to hydro-
static pressure.
The valve
consists of a metallic cylin-
der, contracted at the top,
having a central ring with
arms radiating from it, and passing down the side of the cylinder to
strengthen it; there is an inside projection at the top of the valve,
which is truly faced in the turning lathe, as is also the bottom edge
C
E
A
D
Fig. 94.-Double-beat Valve.
B
A, Valve seat. B, Valve. CC, Wooden beats.
D, Guide piece. E, Flange and bolts.
STATIONARY ENGINES.
159
of the cylinder, the central ring being accurately bored out. The
seating consists of a bottom ring and a solid disc at the top, having
a guiding piece at the top of the disc, with a loose flange secured
by bolts; the bottom ring and disc plate are connected by feathers
or arms, cast all in one piece. The bottom ring and top plate are
recessed for the reception of a ring of wood or soft metal, termed
the beating surface. The amount of contraction at the top of the
valve is due to its weight, and the pressure brought to bear on it
should be slightly in excess of the total weight of the valve. Thus
very little force is lost in lifting it; and as the head of water in the
discharge pipe only acts on a small area, in comparison to the
water way through the bottom ring-and as the lift of the valve is
moderate, owing to the water being forced or drawn through two
circumferential openings

-the beat on the wooden
or white metal rings, if
so fitted, is very gentle
and but little felt, in
comparison with that
of flap valves made of
leather, fitted with me-
tallic facings to prevent
the leather being forced
through the seatings.
For moderate lifts, how-
ever, and more especially
for lift pumps, the flap
valve is still used.
F
F
1
C
E
鼻
​I
D
LB
C
A
The top and bottom
valves, or clacks, as they
are technically termed,
have deep seatings of
cast iron, turned slightly
conical, fitting into cor-
responding parts bored
out in the pump cast-
ings, and are fixed in
position with thin red lead and spun yarn laid into recesses
turned out on the circumference of the seat; there is a single
feather cast along with the seat, having an oblong hole in the centre.
Fig. 95.-Clack Valve with Leather Hinge.
A, Clack seat. B, Leather disc. c c, Top and bottom plates.
D, Bow. E, Cross piece with cotter for securing the bars.
F F, Recesses.
160
MODERN STEAM PRACTICE.
The valve is a disc of leather, with top and bottom plates of wrought
iron, securely rivetted through and through, and it is held in
position by a central bar of iron, with long projections on the
O
E
оо
under side for taking the entire
diameter of the valve. A key is
driven through the bar, drawing it
up against the under side of the
seating, which likewise presses
down the bar placed on the top of
the leather; thus the valve hinges,
as it were, on the mid feather, and
is perfectly water-tight. The valve
is prevented from opening too far
by pieces forged on the bar, and at
the top of the bar a bow is formed,
for attaching a hook and chain
when drawing the clack from
the surface, as provision must be
made that the clack can be drawn
when the water is above the valve-
chest door. Some of these valves
hinge on a bar, which passes
through lugs forged on the top
plate and through holes in the
bow, for fishing the valve to which
the bow is securely bolted; there
is also a wrought-iron piece at the
centre of the valve seating on which
the valve hinges. There should be
cc, Hinge a slight play in the holes to suit
the varying thickness of the leather
forming the valve.


Fig. 96.-Clack Valve with Wrought-iron
Hinge Plates.
A, Clack seat. B, Leather disc.
plates. D, Round bar for hinge. E, Bow.
F, Centre stud.
The working bucket (Fig. 97) is constructed similarly to the
ordinary clack valve with leather hinge, having means of attaching
the bar to the pump rods; and is packed with deep rings of gutta-
percha, let into recesses formed on the outside circumference, and
pressed against the barrel with hydraulic pressure, holes being bored
from the top of the bucket for this purpose. This plan is much.
more preferable than the old mode of packing the bucket with a
plaited gasket or ring of leather.
STATIONARY ENGINES.
161
The economy of the single-acting pumping engine depends on the
high steam pressure adopted-the higher the pressure in the boiler
is the less water is required to be evaporated or boiled off propor-

F
DA
B
E
D
A
D
Fig. 97.-Bucket.
G
A, Bucket.
B, Leather disc. cc, Top and bottom plates. D D, Gutta-percha rings. E, Holes for
water pressure for the packing rings.
F, Rod.
G, Cross bar for securing the rod with jib and
cotter.
tionally; and, in addition, the facility of cutting off the steam at any
part of the stroke to suit the load on the engine, and the careful cloth-
ing of all the parts where radiation takes place with a non-conducting
material, keeping those parts warm and the surrounding atmosphere
cool. To effect this the cylinder is surrounded with a steam casing
or outer cylinder. Steam is admitted between these two, and the
outer one is covered with felt and wood over all, and in some cases
brickwork; the cylinder cover is hollow, admitting steam, and it is
protected with wood lagging, as it is technically termed. The
11
162
MODERN STEAM PRACTICE.
steam pipes are covered with felt and canvas, and the valve chests
with felt and wood, neatly covered in with ornamental plates. The
boilers are protected with fire-brick or other material on the top.
Thus, with all these precautions, very little radiation takes place,
even although the engine may not have been working for a consid-
erable time.
The action of the single-acting pumping engine is quite different
from that of the reciprocating engine, having the connecting rod
coupled to a crank shaft. The steam from the boiler only acts on
the top of the piston, lifting the water at the other end of the beam,
or as it were the IN-stroke of the pump, when lifting pumps are fitted;

B
A
A
C
E
Fig. 98.-Equilibrium Valve.
A, Valve. B, Spindle for valve. c, Seat for valve. D, Holding-down bot.
B. Cross bar.
and when forcing sets are used in connection with lifting pumps, as
is often the case when pits are very deep, the water is forced up the
stand pipe by the mere weight of the pump rods, &c.
The valves are of the equilibrium kind; two are fitted to the top
STATIONARY ENGINES.
163
chest, namely, the steam and equilibrium valves, and the exhaust.
valve is placed in the bottom chest. There is likewise, in some
examples, a regulating valve worked by hand, for regulating the
supply of steam from the boiler; and a throttle valve is placed in

D
A
葉
​B
C
00
P
C
E
A
.C.
E
Fig. 99.-Nozzle-valve Chest boxed in.
A, Steam-valve seating. B, Equilibrium-valve seating.
cc, Exhaust-valve seating. D, Regulating-valve
seating. E, Pipe for conveying the steam from the
top to the bottom of the cylinder.
Fig. 100.-Nozzle-valve Chest not boxed in.
A, Steam-valve seating. B, Equilibrium-valve
seating. c, Exhaust-valve seating. EE, Pipes
for conveying the steam from the top to the
bottom of the cylinder.
the pipe communicating with the top and bottom valve chests, which
is also regulated by hand, and is introduced to throttle, or rather
wire-draw the steam after passing through the equilibrium valve;
thus the engineman can control the upstroke of the piston with the
greatest nicety without requiring to alter the lift of the equilibrium
valve.
There are three shafts or arbors placed across the engine, arranged
one above another in a vertical line; the top one is for the steam-
164
MODERN STEAM PRACTICE.
valve gear, the middle one for the equilibrium, and the bottom shaft
for the exhaust-valve gear. An arm is keyed on each shaft, having
a connecting rod coupled to the lever for lifting each valve; each
shaft has also an arm with a connecting rod passing downwards to
a loaded lever, the weight of which lifts each valve respectively.

O--------
11
Steam cut off
O
О
Steam shut
Equilibrion shad
Equilibrium open
Exhaust open
о
Weight
Exhaust start
Cataract
Weight
Plug Rod


Fig. 101.-Cornish Valve Gear.
The valves are shut with tappets placed on the vertical rod worked
by the engine, and named the plug rod; the tappets act on slide
STATIONARY ENGINES.
165
handles or horns keyed to each shaft. The tappet or sliding bar for
the steam valve is a long wrought-iron bar, quite parallel in its
entire length, secured to the plug rod with eyes at the ends, and
set screws passing through these eyes, the point of the screw press-
ing against the plug rod. This is necessary, as the steam may be cut
off quickly, or say at one-fourth of the stroke of the piston, conse-
quently the bar would require to be somewhat more than three-
fourths of the stroke of the plug rod, so as to keep the steam valve
shut. The two other tappets are round arms, secured to the plug
rod in the same way, having a series of leather washers screwed up
against a collar, with a nut and metal washer at the end of the
projecting bar. On the steam and exhaust shafts a catch and paul
are fitted for each, keeping the valves shut until released by the
cataract, which consists of a pump worked by the down stroke of
the plug rod, with a weighted lever so arranged that the oil or water
is forced out of the pump, the delivery being regulated by a valve
or plug tap. On the end of the weighted lever there is a rod
passing upwards for raising the pauls, which can be adjusted at
pleasure; thus the catches are freed, and the weight arm lifts the
valve. A quadrant is keyed on the middle and bottom shaft to
keep the equilibrium valve shut. When the exhaust valve is open
the top quadrant abuts on the lower one, and keeps the equilibrium
valve shut until it is released, when the tappet for the bottom shuts
off the exhaust, and allows the quadrant to pass the equilibrium
quadrant, thus releasing it, and the valve is instantly opened by
the weight arm.
Now we will suppose the piston at the top of the cylinder, and
the exhaust valve full open by the cataract releasing the bottom
catch; the cataract rod, still moving upwards, releases the top catch,
and the steam valve is instantly raised by the weight-arm, the piston
at once descends, until the long parallel tappet cuts off the steam; the
plug rod still moves on until one of the tappets shuts the exhaust at
the end of the piston stroke, and as the equilibrium valve was held
in position by its quadrant, at the moment the exhaust is shut the
equilibrium valve opens; so the steam is thus allowed to escape
from the top of the piston to the under side of it, the descent of the
pump rods placed at the other end of the engine beam being regu-
lated by the amount of opening of the equilibrium valve, which can
be further regulated by the throttle valve at pleasure wire-drawing
the steam in the passages from the top to the under side of the
166
MODERN STEAM PRACTICE.
piston; and in this way the outgoing stroke or descent of the pump
rods may be very slow indeed. The plug rod, ascending, shuts off
the equilibrium valve, thus stopping the further descent, or produc-
ing only a slight motion, of the plunger and weight, until the
cataract releases the exhaust and then the steam valve. It will
thus be seen that for a part of the downward stroke the steam and
exhaust valves are both open, and the exhaust remains so until the
end of the stroke, when it is closed; while in the up stroke of the
piston the equilibrium valve is open, and all the rest shut off.
In order still further to explain this intricate valve gear, in Figs.
102, 103, we give an example fitted to an engine at one of our
Cornwall mines, the diameter of the steam cylinder being 90 inches.
"The action of the gear will be better understood if we describe
each stroke separately. First, the steam, or indoor stroke:-This is
the down stroke of the piston, and is produced by the admission of
steam through a valve termed the steam valve, situated in the top
nozzle, and which is actuated by means of the lever B fixed on an
arbor carried in bearings in the two upright castings at the sides,
which are termed arbor posts. It is usual to connect the lever B
directly with the steam-valve lever-by means of a rod carried up-
ward, instead of indirectly by means of a rod carried downwards, as
in the example before us; the reason for the latter arrangement we
will explain as we go on. The lever B is attached by means of a
rod with a 'treadle' or weighted lever of wood situated under the
engine-house floor; the treadle is connected to the steam-valve
lever, so that when the lever B is raised it closes the steam valve.
On the steam arbor, or the arbor carrying the lever B, is placed
a quadrant K, which is supported by means of the catch U, which
catch keeps the steam valve closed till the cataract rod a shall
have released the quadrant K by means of the lever M, and thus
allowed the weighted treadle to pull down the lever B and open the
steam valve. The cataract is actually the governor of the engine,
and acts in the following way. (See illustrations of cataracts, Figs.
104, 105, 106.) In this case a plunger is attached to the lever, on
the opposite side of the fulcrum is placed the cataract rod A, and
on the plunger side of the fulcrum a weight. The plunger works
in a kind of force pump, fixed in a cistern full of water. When the
plunger is raised water follows it up through the suction valve, and
during the down stroke the water thus drawn from the cistern is
forced back again through a delivery valve which is capable of being
STATIONARY ENGINES.
167
varied in the height of its lift by means of a screw on the cataract
governor valve rod, which rod is under command of the engine-
driver. It is evident that the smaller the opening of the delivery
valve the slower will the plunger descend, the weight forcing it
being constant. As the plunger descends the rod A rises, and brings
the roller shown in the front elevation to bear on the lever M, and
thus releases the quadrant K. Let the cataract plunger be up, then
the engine is at rest, and remains so until the rod A shall have raised
the lever M and released the catch U; the weight attached to B then
suddenly falls and opens the steam valve. Steam being suddenly let
in on the piston causes it to commence its indoor stroke, and in doing
so to give a downward direction to the motion of the plug rod S, the
tappets of which coming into contact with the steam horns depress
them, and thus raising the lever B close the steam valve, at the same
time the piston continues its stroke under the expansive force of the
steam in the cylinder, and towards the end of the stroke raises the
plunger of the cataract to prepare it to repeat its functions during
the next indoor stroke. The horn or lever of the cataract being thus
depressed whilst the steam valve is closed, the catch U falls under the
influence of the weight of the lever M under the projection on the cir-
cumference of the quadrant K, thus preventing the opening of the
steam valve when the steam tappets have been raised, during the up
or outdoor stroke of the piston, above or clear of the steam horns, until
the cataract weight shall have fallen sufficiently far to release the catch
U, when the steam valve suddenly opens, as before described, and
the next indoor stroke is commenced. Having described the func-
tions of the steam or top arbor and tappets, we will consider next
the equilibrium stroke. The middle is the equilibrium arbor, and
the horn is shown in the side elevation. There are two quadrants on
this arbor. The first G is released by means of a cataract constructed
precisely like the one just described. The rod of this cataract is
placed inside the gear posts, as shown on the front elevation, whereas
that of the steam cataract is placed on the outside. There is an
adjusting screw A on the equilibrium cataract rod, and two such, P,
on that of the steam cataract. The lever C opens and closes the
equilibrium valve. The opening is done by means of a counter-weight
attached to the lever E, which operates on the release of the quadrant
G. At the completion of the indoor stroke the piston pauses until
the catch O, actuated by means of the cataract, releases the quadrant
G. It will be seen that this cataract rod releases on its down stroke,
168
MODERN STEAM PRACTICE.

Educt
R
Equil.brium Cataract
Steca Plug Roa
i
Eduction Nozzle
Steam Horn
Steam
Horn
Equilibrium Pipe
Stearn Arbor
am.
Equilibrium Arbor
C
書
​Eduction
Arbor
Eduction Plug
Fig. 102.-Valve Gear of a 90-inch Cornish Pumping Engine.-Front Elevation.
whereas the other does it on its up stroke. In the former case the rod
Eduction Horn
Governor
Steam Tappet
Equalibrium Horn
Equilibrium Tappet
F
B
E
ㄣ
​Eduction Tappet
Equilibrium Pipe
STATIONARY ENGINES.
169

Weight
+ Steam
B
G
F
H
Side
Elevation.
Inside
Quadrants
Equilibruim
Weight
Cataract Governer
Steam Catara
Edaction and
N
Fig. 103.-Valve Gear of a 90-inch Cornish Pumping Engine.-Side Elevation.
A is attached to the cataract lever on the same side of the fulcrum as
K
M
Eduction
T
P
Steam
Equilibrum
Horns
Side
Elevation.
f
170
MODERN STEAM PRACTICE.
the plunger. The quadrant G being released, the equilibrium valve at
the top of the cylinder suddenly opens, and a free communication
is established between the top and bottom sides of the piston through
the perpendicular or equilibrium pipes shown in outline on the
woodcut. The outdoor stroke now commences; the piston, being in
equilibrium, is raised by means of the weight of the pump rods and
attachments, which is sufficient to force the water in the pumps and
overcome all other resistances. During this stroke the plug rods
move upward, and towards the end the equilibrium tappet comes
in contact with the horn on the equilibrium arbor, and lifting it
closes the valve, at the same time allowing the catch o to fall under
the projection on the quadrant G. A portion of steam is thus
confined in the top of the cylinder, which gradually brings the piston
to rest, and prevents it striking the cover. The piston now pauses
till the steam quadrant shall be released. The eduction stroke is
performed simultaneously with the steam stroke. The eduction
valve is situated in the bottom nozzle, and opens a passage to the
condenser for the steam passed from the top to the under side of the
piston during the equilibrium stroke. The lever D actuates the
valve through the lever T. As the piston completes its indoor
stroke the eduction tappet comes into contact with a horn on the
eduction or lower arbor. The valve is opened by means of a coun-
terweight at F, when the quadrant L is released by the cataract.
The quadrants H and I are for the purpose of keeping the equilibrium
valve closed until the closing of the eduction valve. It will be seen
that, although the catch 0 may be released, the quadrant H prevents
the opening of the equilibrium valve until the eduction valve is
closed and the quadrant H brought into the position shown on the
woodcut. It will be seen that if the catches M and N are released
simultaneously the steam and eduction valves will open at the same
time, but the times can be varied by means of the adjusting screws
P and R. The hand wheel X is for the purpose of adjusting the
amount of fall given to the weight which opens the steam valve, so
as to give the valve a greater or less opening. The degree of
expansion is varied on the plug rod by means of the screw s.”1
The cataract, as a means of regulating the number of strokes of
the Cornish pumping engine, is exceedingly simple. One arrange-
ment consists of a wooden box, open at the top, fitted with another
box internally, having flap valves at the bottom opening upwards,
1 The Engineer.
STATIONARY ENGINES.
171
as also a plug tap, which can be regulated at pleasure from the
engine-room floor. There is a central rod secured through the
bottom of this internal box or

E
B
Fig. 104.-Cataract with Wooden Tray.
A, Box for water. B, Tray. C, Inlet valve.
D, Regulating valve. E, Small hand wheel.
tray, and connected to a lever
weighted at the end, with a fixed
pin as the fulcrum, placed be-
tween the weight and the box;
this weight is slightly in excess
of the tray and adjuncts when
the internal box is full of water.
The action is as follows:-The
outside box, in the first place,
must be nearly full of water, and
we will suppose the tray empty
and raised by the weight acting
through the oscillating lever; the
plug rod of the engine descend-
ing acts on mechanism that de-
presses the tray, and water flows
through the flap valves in the bot-
tom until the plug rod ascends,
when the preponderance of the weighted lever raises the internal
box or tray above the level of the water in the outside box, conse-
quently the water in the tray gravitates into the external reservoir-
hence the name cataract; and the time the water takes to flow out
of the one into the other is regulated by the plug tap,—if it is full
open the water will flow out quickly, and the tray will rapidly
ascend, the cataract rod releasing the valves; but should the plug
tap be nearly closed, it is evident that the water will flow out of the
tray slowly; and as this tap is regulated, the number of strokes of
the engine will be increased or diminished: but the number of strokes
rarely exceeds twelve per minute as the maximum, and four per
minute as the minimum. This form of cataract is exceedingly
simple, and even rude in construction, yet it answers the purpose
admirably so long as the level of water is maintained in the external
box, which must be looked to occasionally, as evaporation will take
place or leakage occur.
Instead of the wooden tray a plunger pump (Fig. 105) is sometimes
fitted inside of a box of cast iron, having a valve at the bottom for
admitting water or oil into the pump, fitted with a tap for regulating
172
MODERN STEAM PRACTICE.
the exit of the fluid. The weighted lever is so arranged that the plug
rod lifts the plunger and weight, and the cataract rod for disengag-

G
»»» - - - ->
F
B
A
E
D
A, Cast-iron box.
Fig. 105.-Cataract with Plunger Pump.
B, Plunger. c, Inlet valve. D, Plug rod. E, Lever. F, Weight.
G, Regulating spindle and valve.
ing the valves ascends as the plunger and weight descend, the
motion being changed by a lever; the cataract rod for lifting the
paul is jointed at one end of the lever, and the rod passing down to
the arm for the weight and plunger at the other end.
In some examples of the plunger type, when two cataracts are used,
the plug-rod tappet acts on the two levers for lifting the plungers
simultaneously; on the centre of motion of the levers a grooved
wheel is fixed, and the lever for the cataract pump is connected by
means of a chain wound round the wheels, and as the tappet or
plug rod comes in contact with the levers the wheels are partially
turned round, pulling one end of the cataract lever down, and
raising the other end, to which the plunger and weight are fitted.
Some arrangements of cataract pumps have a solid piston, or one
fitted with cupped leather washers, and on the top of the piston rod
a crosshead and side rods passing down under the floor of the
engine house, and in communication with the mechanism for lifting
the piston and weight placed on the top of the crosshead. A central
metallic valve is placed at the bottom of the pump, and a tap is
likewise fitted for regulating the ejection of the oil, which is gene-
rally used when the cataract is placed on the engine-room floor.
This type of cataract has likewise a reservoir for receiving and sup-
plying the oil; and as leakage past the piston ring occurs after
being long in use, an air passage is formed above the piston in
communication with the reservoir, and any oil passing the piston is
STATIONARY ENGINES.
E
173
allowed to fall by gravitation into the cistern or metallic box. In
another example, where refinement of construction is a desideratum,
the cistern is dispensed with, and the oil is
ejected through a valve fitted to the piston
on the down stroke, and passes through the
same valve on the up stroke, it being forced
through by suitable mechanism in the
down stroke, and the ascent of the piston
is acted on by the weight, as in the former
examples. This plan of cataract necessi-
tates a hollow piston rod, with stuffing box
on the pump cover, fitted with an internal
rod attached to the valve, passing up to the
crosshead, for taking the disengaging rod;
this hollow rod is fitted with a stuffing box,
and the internal rod has a thumb screw at
the top for regulating the lift of the valve.
Thus this valve allows of the oil passing
from the bottom to the top of the piston,
and also regulates the flow of the oil from
the top of the piston to the under side of
it, forming a self-contained and handsome
cataract pump.

B
IC
A, Cylinder. B, Cupped leather pis-
ton with valvė. c, Hollow rod.
D, Stuffing box and gland.
E, Thumb screw and gland.
The condenser (Fig. 107) for the Cornish Fig. 106.-Cataract without Cistern.
engine is generally a separate vessel, worked
on the injection principle. As the exhaust
pipe from the steam cylinder is of large
diameter and of considerable length, it is obvious that the cubical
contents of the condenser need not be so large as for ordinary
engines, the exhaust pipe acting as a receiver, and the steam being
condensed in a vessel placed at the extreme end.
The air pump is of the ordinary kind, with metallic head and foot
valves, the bucket being open, with a metallic valve placed on the
top, and it is made tight with ordinary hemp packing plaited, or what
is termed a gasket. In another example (Fig. 108) the air pump and
condensing vessel are placed inside of a cast-iron tank, which is kept
constantly full by means of a pump termed the cold-water pump.
When this arrangement is adopted the condensing vessel is kept quite
cool by the surrounding water, and to a certain extent acts as a surface
condenser, in combination with the injection system. The tank
A
174
MODERN STEAM PRACTICE.

A
C
B
Fig. 107.-Condenser and Air Pump, with Foot-valve Seating.
A, Condenser. в, Air pump. c, Foot-valve chest.
B,

O
A
B
C
Fig. 108.—Air Pump and Condenser without Foot Valve contained in a cast-iron Tank.
A, Condenser. B, Air pump. c, Tank.
STATIONARY ENGINES.
175
must be fitted with an overflow pipe, which is placed in communi-
cation with the discharge from the air pump. When the water is
very bad the air pump should be lined with a barrel of composition
metal, or a brass barrel is so placed, centrally with the condenser;
and when suitably strengthened and supported from the con-
denser vessel, the latter proves a very compact arrangement, com-
bining the condenser and air pump in one. The foot valve, in
ordinary arrangements, is placed at the bottom, between the con-
denser and air pump. It is a flap valve hinged vertically, and is
sometimes made of wrought iron, faced with a brass beating surface,
with a corresponding brass face securely pinned on the cast-iron
seat. The valve is bent to form a hooked hinge, so that it can be
readily taken off the spindle on which it hinges without disturbing
the seat, a door being fitted to the condenser casting for inspecting


A
B !
O
E D

Fig. 109.-Head Valve with Wooden Beat
on Seat.
A, Valve. B, Seat. cc, Wooden beat.
D, Stuffing box and gland.
Fig. 110.-Air-pump Bucket, with Brass Seat for
India-rubber Valve.
A, Bucket. B, Brass seat for valve. c, India-
rubber disc. D, Guard. E, Rod secured with
a nut at the bottom.
and adjusting the valve. The head valve, placed at the top of the
air pump, is a disc of metal having a deep boss at its centre,
strengthened with ribs radiating from the centre, and having a hole
bored through the boss for receiving the air-pump rod, which acts.
as a guide for the valve. Sometimes this boss is fitted with a gland
176
MODERN STEAM PRACTICE.
and packing space, thus making it perfectly water-tight. The seat
in this example is cast separate, and bolted to the air-pump, and
fitted with a ring of wood for the valve to beat against. The valve
fitted to the top of the air-pump bucket is of a similar description,
with a plain hole lined with brass, which acts as a guide. In some
cases the valve on the bucket (Fig. 110) is of india rubber, working
on a grating of brass bolted to the bucket. The air-pump bucket
is fitted with a junk ring and packing space, and when a brass
barrel is used may be packed with hemp, or a metallic, or even
wood packing will be found to answer.
Thin metallic rings sprung
into recesses make a first-class packing, and last much longer than
hemp.
The Ejector Condenser.-In the ejector condenser the air pump is
entirely dispensed with. The principle of the apparatus may be
described as follows:-In every injection condenser the cold water
rushes into the vacuum with a velocity of about 43 to 44 feet per
second; while the exhaust steam from the cylinder of the engine, at
the pressure of 10 lbs. per square inch below the atmosphere, rushes
into the condenser with a velocity of about 1200 feet per second, when
a vacuum of 25 inches of mercury is maintained. In the common
condenser these rapid motions of the water and the steam are com-
pletely checked, and their energy is wasted, and hence an air pump is
imperative, so as to extract the water, air, and condensed steam from
the condenser. In the ejector condenser the exhaust steam from the
cylinder of the engine after each stroke is so directed through a
discharge nozzle as to unite in a jet with the condensing water, by
which it is itself condensed, having, however, imparted a sufficient
velocity to the combined jet to enable it to issue directly into the
atmosphere in a continuous yet impulsive stream. The contents
of the condenser, both water and air, are thus ejected without the
use of an air pump, and at the same time without impairing the
vacuum in the condenser. This result is obtained, however low the
pressure may be to which the steam is expanded before the exhaust
from the cylinder takes place, if the injection water be supplied
with a few feet of head pressure: and the effect is produced by
taking advantage of the high velocity at which the exhaust steam
and the injection water flow into a vacuum. The ejector condenser
not only discharges the products of condensation into the atmo-
sphere from a pressure of 12 lbs. per square inch below the atmo-
sphere, but with a steam pressure equal to the atmosphere at the
STATIONARY ENGINES.
177
commencement of the exhaust, the condenser, when applied to a
pair of coupled engines, is found capable of lifting the condensing
water from a lower level of 6 to 8 feet, or raising the discharged.
water to a proportionate height above the condenser.
In the simplest arrangement the injection water enters the con-
denser in the form of a central jet through the conoidal nozzle
A, which is supplied by the branch
pipe B; and the area of the ori-
fice is regulated by an adjustable
central spindle C, which is raised
and lowered by an external screw
and hand wheel. The exhaust
steam entering at the branch pipe
D, passes through the annular
space surrounding the central
water jet, and the combined cur-
rent passes on through the fixed
conoidal nozzle F, into the dis-
charge tube G leading to the
hot well. This tube is trumpet-
mouthed, so as gradually to di-
minish the velocity of the current
as it passes through, and utilize
its moving force by avoiding use-
less velocity at the point of dis-
charge, the enlargement of the
tube increasing more rapidly to-
wards its outer extremity.

IL
D
A
Transverse
Section at X.X
Fig. 111.-Condenser supplied with Head
of Injection Water.
In starting the condenser the
centre spindle is raised by means
of the hand wheel, and a jet of injection water is discharged
through the centre of the current of the exhaust steam from the
engine: the injection water being in this case supplied from a head
of water a few feet above the condenser, so as to flow into it by
gravity. The condensation of the steam by contact with the injec-
tion jet produces a vacuum within the condenser, and the water
then enters with the velocity due to the difference of pressure between
the external atmosphere and the degree of vacuum maintained in
the condenser, added to the velocity due to the head of water in
the injection supply. The water jet having a straight passage for
12
178
MODERN STEAM PRACTICE.
its exit, without any obstruction, retains its initial velocity, and
rushes on through the combining nozzle F and the expanding dis-
charge tube G, and issues into the atmosphere in a continuous
stream, carrying with it any air mixed with the exhaust steam, the
action being somewhat similar to that of the injector for feeding
boilers.
It is requisite for the injection water to enter the combining
nozzle in a straight stream, without any eddy or rotation of the
water; and whenever the injection is supplied with the pressure of
a head of 10 feet or upwards, a provision is made for stopping any
rotation of the stream, by inserting within the nozzle a guiding piece
R, with several straight radial vanes, as shown in Fig. III.
The proportion that has been found most effective for the injec-
tion jet is for the length of the free portion of the jet, which is
exposed to the action of the exhaust steam, to be about three times
the diameter of the jet, except when the injection water is supplied
with a head of 10 feet and upwards, in which case the length of the
exposed jet is increased with advantage to 3½ diameters.
The moving force in the current of the exhaust steam rushing
into the condenser communicates an additional velocity to the
water jet on issuing from the water nozzle, the amount of this
addition being dependent upon the difference of pressure between
the exhaust steam and the condenser; and when the steam is not
expanded down in the cylinder of the engine to a very low pressure
before its exhaust, the combined moving force in the water jet is
found to be sufficient to effect a continuous discharge into the
atmosphere, not only without aid from a head of water in the injec-
tion supply, but leaving a surplus power sufficient for raising the injec-
tion water from a lower level of several feet below the condenser.
When the injection water is not supplied by a head pressure, but has
to be raised from a lower level, the working of the condenser (Fig. 112)
is started in the first instance by means of a jet of steam direct from
the boiler, introduced through the central spindle C, so as to act in
the axis of the water jet. The steam is admitted to this jet through
the small piston valve J, which has a second piston valve I, fixed
below on the same spindle. This lower piston is supported by a
spiral spring, and communicates with the condenser on the under
side by the pipe H; and as soon as a vacuum is formed in the
condenser, the piston valve is moved, the pressure of the atmosphere
acting on the top of the upper piston J causing this piston to shut
STATIONARY ENGINES.
179
off the steam jet. In the event of the vacuum ever becoming
impaired from any cause, the piston valve is instantly raised by the
pressure of the spring below it,

and a jet of steam from the boiler
is thus applied by self-acting
means to the extent that may
be required for restoring the full
action of the condenser.
When the piston of the engine
makes only a few strokes per
minute, the impulse received from
the successive discharges of the
exhaust steam fluctuates, a por-
tion of the water fails to get the
full velocity of discharge imparted
to it, and escapes at the nozzle
into the chamber K. This over-
flow water is removed continu-
ously by means of the side return
passage L, which communicates
with an annular space surround-
ing the water nozzle A, and
the water is carried forward by
being brought again into con-
tact with the jet of exhaust
steam.
In another form (Fig. 113) the
condenser is shown as applied to
J
I
K
K
P
Steam.
a pair of engines coupled at right Fig. 112.-Condenser with Self-adjusting Jet of
angles; the only alteration being
the addition of a second combining nozzle N, fixed beyond the first
one, and communicating with a second branch pipe M, which brings
the exhaust from the other cylinder of the coupled engines. The first
nozzle F so completely separates the two steam jets from each other
that the alternate discharge of the exhaust steam from either cylin-
der cannot in any way impair the vacuum in the other cylinder:
the degree of vacuum is found in some cases to be rather higher
in the upper nozzle than in the lower one, the steam in the upper
nozzle being the first to come in contact with the injection water.
In this arrangement, as well as in the preceding one, a foot valve P
180
MODERN STEAM PRACTICE.
is provided at the exit orifice of the discharge tube to prevent any
inflow of water from the hot well into the condenser, when the
vacuum ceases when the engine is
stopped.

Ma
Fig. 113.-Condenser for a pair of Coupled
Engines.
Mr. Alex. Morton of Glasgow in-
forms us that he has fitted these con-
densers to all classes of land en-
gines, from the slow-going pumping
engine making three revolutions
per minute, to other engines hav-
ing a piston speed of 500 feet per
minute, and even engines having
a greater piston speed than this
have been fitted with ejector con-
densers.
We give side and end views of
an ordinary horizontal pumping
engine (Figs. 114, 115) fitted with
the condensing apparatus. The con-
denser is placed below the level of
the steam cylinder of the engine, and
may be in any convenient position
either inside or outside of the en-
gine house. The rising main from
the pit pumps delivers the water
into a tank a few feet above the level
of the condenser; having a pipe for
supplying the injection water to
the condenser, and the discharge
from the condenser passes through
a pipe into a drain, as shown.
In another example of blow-
ing engine at an iron-works near
Bridgend in Glamorganshire, the cylinder being 40 inches diameter
and 10 feet stroke of the piston, making fifteen revolutions per
minute, the condensing apparatus maintains a constant and steady
vacuum of 12½ lbs. below the atmosphere. The injection water in
this case is supplied from a head of 1½ foot above the condenser,
and the discharged water has a fall of about 9 feet, consequently
no starting jet is required in such cases.
STATIONARY ENGINES.
181
securely fastened down with a bar of iron to the conical valve seat,
with a suction valve of the flap type, consisting of a disc of leather
ship
The cold-water pump is a cast-iron barrel, fitted at the bottom

Figs. 114, 115.—Ejector Condenser fitted to a Horizontal Pumping Engine. Side and End Elevations.
A, Ejector condenser. a, Injection pipe. 6, Exhaust-steam pipe. c, Pipe from hot well. d, Pipe from pit pump.
e, Cistern. ƒ, Overflow pipe. g, Vacuum gauge.
182
MODERN STEAM PRACTICE.
and arranged with a central feather, the disc being fitted with wrought-
iron plates on the top and bottom, securely rivetted through and
through. The bucket is fitted with a valve of a similar description,
having means of securing it to the pump rod; and it is usually
packed with a plain hemp gasket let into the recess formed in the
bucket, and fastened by means of plain wooden pins driven through
holes bored in the side. Some consider, however, that these buckets
should be fitted with gutta-percha rings, let into recesses formed on
the bucket, with holes bored from the top in connection with the
recesses; thus when the gutta-percha rings are cut and sprung into
the recesses, the head of water acts on the inside of the rings, keeping
them up to the face.
The feed pump is of the ordinary plunger type, fitted with
metallic valves, and draws the water from the hot well above the
air pump, the water being partially heated by the steam in the
process of condensation. All these pumps are generally worked
from rods directly fastened to the engine beam, on the opposite
end from that of the steam cylinder. The rod for the air pump
is generally placed midway between the main centre and the end
of the beam; the cold-water pump rod is situated between the
air-pump rod and the end of the beam; while the feed-pump rod
has a shorter stroke than either, being placed between the air pump
and the main centre on which the beam vibrates.
The beam is generally shorter on the pump end, the steam piston
having a longer stroke; thus the motion of the main plungers or
buckets, if so fitted, is slower than that of the steam piston, and this
diminution of velocity decreases the wear and tear of the pump
gear. Moreover, increased length of piston stroke requires less
diameter of cylinder, which is a great desideratum when high steam
pressure with a large measure of expansion is used, as the parts
need not in this case be made so heavy. Some makers have intro-
duced a small high-pressure cylinder in combination with a larger
one; the steam in the first place acts on the small piston, and then
expands into the large cylinder. The large cylinder and its adjuncts
need not therefore be so heavy as with the single-cylinder arrange-
ment, but it is obvious that greater complication is entailed, and for
economy of fuel the single cylinder with a long piston stroke is to
be preferred. Cornish engineers endeavour to economize fuel by a
careful clothing of the parts where radiation takes place. The
cylinder is inclosed in a steam jacket, as already described; the
#
STATIONARY ENGINES.
183
outside cylinder or casing is covered over with felt or non-conducting
material, and then carefully lagged with wood, with four or more
metallic straps girding it all round; in some instances heated air
has been applied all round the steam cylinder, the annular space
being encircled with brick-work. The thorough protection of the
inside or working cylinder so as to prevent surface condensation,
and the covering of the steam pipes from the boiler with felt and
canvas to prevent radiation-combined with the high steam pressure
used and the large measure of expansion obtained-have raised
the duty performed by the Cornish engine far above that of the
ordinary class of engine used for land purposes.
Figs. 116 and 117 give side and end elevations of an overhead-beam
pumping engine erected at a pit near Kilmarnock. The principal.
advantage in the arrangement here is that it leaves the pit mouth
clear, and in sinking a pit enables the rods to be easily lengthened
as required.
The cylinder is 84 inches in diameter, suited for a 12-feet stroke
in the pump. The piston rod is connected to a strong malleable-
iron beam, made of two plates placed 15 inches apart. The pump
rod is connected to one end of the beam, and the other end is sup-
ported by vibrating columns oscillating on journals working in two
bearings, which are bedded on the top of the stone pedestals for the
foundation, and secured with bolts and nuts passing down through
the foundation, and having a cotter and wall plate at the bottom.
The parallel motion for the piston rod consists of two motion
rods, one on each side of the beam, connected to cast-iron standards
bolted to projecting flanges on the top of the cylinder. The plug
rod for the valve mechanism is worked directly off the beam, from
the same gudgeon as for the parallel-motion bars, and is guided
with a bracket placed underneath the engine-room floor.
The engine is fitted with a blow-through condenser, on a plan
which works as follows:-Steam being admitted to the bottom
of the cylinder, the piston is forced to the top of its stroke; the
steam valve is then shut by suitable gearing, and the steam
passes from the bottom side of the cylinder to the top side, the
piston is then in equilibrium, and the weight of the pump rods
carries it to the bottom, but before it reaches this point the injector
valve is opened with a tappet placed on the feed-pump rod, with
levers and rod carried along to the valve; water is thus admitted
into the condenser, and the valve remains open until the steam is
184
MODERN STEAM PRACTICE.
shut off, and the piston nearly at the end of the up stroke; the
remaining exhaust steam in the top blows the water and condensed

O
-
Fig. 116.-Overhead-beam Pumping Engine. Side Elevation.
steam out of the blow-through valves at the bottom of the condenser
into the overflow cistern, from which it is led into a drain. In
working, the water in the condenser rises to nearly the level of the
STATIONARY ENGINES.
185
injection valve.
Besides the ordinary steam and exhaust valves,
there is a valve worked by hand for regulating the descent of the

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Fig. 117.-Overhead-beam Pumping Engine. End Elevation.
piston, and placed at the bottom of the passage leading to the top
of the cylinder. The feed pump is of the plunger type, worked
directly off the overhead beam; the suction valve is placed at the
186
MODERN STEAM PRACTICE.
bottom of the barrel, and the delivery valve at the top. The annular
space round the plunger is equal to the area of the plunger. With
this arrangement no air can collect at the under side of the gland,
as when the delivery valve is placed at the bottom of the barrel.
The main pump for this engine is of the plunger type, the rods
being cottered to the plunger, instead of the wooden rod passing

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A
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A, Plunger.
Fig. 118.-Pump.
B, Stuffing box and gland. c, Suction valve.
E, Stand pipe with air vessel. F Pump rod.
D, Delivery valve.
down through it, as has been already explained. The diameter of
the plunger is 18 inches, with an annular space all round equal to the
area of the rams. The suction and delivery valves, of the flap type,
are placed at the top of the pump barrel-this arrangement getting
rid of the air that collects in a barrel having the valves arranged at
the bottom. On the stand pipe an air vessel is fitted, to relieve the
shock on the ram in the act of forcing the water. This arrangement of
STATIONARY ENGINES.
187
pump necessitates the use of a separate suction pipe, which is fitted
to the side of the valve chest placed underneath the suction valve.
Side-lever engines have been introduced with the object of re-
ducing the great height of the massive lever wall for carrying the
FOLLO
main beam, and of simplifying the engine by dispensing with the
expensive parallel motion. The arrangement possesses certain
advantages; the main one being that the engine is self-contained,
having a bed plate for carrying the cylinder, main pillow blocks,
condenser, air pump, &c. The side levers are connected to the
piston rod by means of side rods, and a crosshead working in cast-
iron guide frames; the expense of keeping in repair those guides, in
Fig. 119.-Side-lever Pumping Engine.
3

188
MODERN STEAM PRACTICE.
-
comparison with the numerous brasses of the parallel motion, is
very trifling. The air pump is worked in a similar manner, while
the plug rod is actuated with a separate wrought-iron beam, placed
above the main crosshead, and worked therefrom by means of a
small crosshead, fitted to the top of the piston rod with a parallel
motion-an unnecessary refinement, as when the plug rod is guided
at the top and bottom a plain link attachment is all that is needed.

Fig. 120.-Single-acting Side-lever Pumping Engine.
The other end of this beam vibrates on a gudgeon, with pillow
blocks resting on the end wall of the engine-house. The spring
beams of wood are placed on each side of the foundation, these
springs being necessary to check the shock should the engine miss
a stroke or come in or out too rapidly-the ends of the side levers,
striking against the spring beams, greatly reduce the blow, which
would otherwise be felt very severely on the machinery.
There is another example of the side-lever pumping engine, Fig.
120, which although not possessing the advantage of being securely
STATIONARY ENGINES.
189
bedded on a base plate, yet reduces the height of the lever wall
considerably, while its arrangement is somewhat simpler than in the
foregoing example. The valve gear is placed between the cylinder
and the main centre of the side levers; thus the additional beam
for working the plug rod is dispensed with, the rod being worked
directly from a cross gudgeon between the two side levers; this
gudgeon has an elongated hole for the rod to pass through, and is
fitted with two side links connected to a crosshead on the plug rod,
the rod being guided through bushes at the top and bottom. All
the other pumps are worked directly from a gudgeon placed between
the side levers, and securely keyed to them; but the main pump
gudgeon has a bearing at each end, working on turned bushes on
the under side. This gudgeon is made flat in the body, being
deeper at the middle, and the pump rods of wood are securely
fastened to it by means of wrought-iron straps, the great length of
the pump rods causing them to bend with the versed sine described
by the side levers. The pillow blocks for carrying the side levers
are provided with a broad base plate, securely bolted down to the
lever wall; the caps for the pillow blocks are simply shells, fitted for
the sake of appearance, as indeed are all the covers for the pillow
blocks of Cornish engines when adapted for mining purposes. This
arrangement is adopted owing to the steam acting on the top of the
piston at one end of the beam, while the great weight of the pump
rods is being lifted at its other end; and in the outgoing stroke, or
descent of the pump rods, the steam pressure on the top of the
piston is in excess of the under side, and consequently the side
levers have no tendency to lift.
Some mine-pumping engines have been erected on the direct-
action principle, the steam cylinder being placed directly over the
pumping shaft, with the pump rods attached directly to the piston
rod, the steam acting on the under side of the piston. There is no
equilibrium valve fitted to this class, as the steam, after doing duty
in lifting the pump rods, is exhausted into the condenser, which is
in connection with the top of the cylinder, and the downward
motion of the pump rods is retarded. The weight of these rods is
always in excess of what is required for forcing the water, and is
due to the diameter of the pump and the great length of the rods.
Of course the steam in the cylinder can be throttled in its passage
to the condenser, thus gradually reducing the pressure and prevent-
ing the pump rods descending too rapidly. The air pump is worked
190
MODERN STEAM PRACTICE.
by a vibrating lever, linked to the piston rod, and placed underneath

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Fig. 121.-Direct-acting Pumping Engine. Side Elevation.
the cylinder floor; the motion of the lever working the plug rod for
the valve mechanism. This class of engine, modified, has come
STATIONARY ENGINES.
191
into extensive use, and, although cheaper in first cost, we unhesi-

Fig. 122.-Direct-acting Pumping Engine. End Elevation.
tatingly give the preference to the beam engine, or the more
recent example the side-lever Cornish engine, when the depth of
the mine is considerable.
Figs. 121 and 122 show side and end elevations of a pit engine
which may be considered an improvement on the foregoing
example. The steam cylinder has a diameter of 84 inches,
192
MODERN STEAM PRACTICE.
suited for a 13-feet stroke. The pump rods are connected directly
to the piston rod, which is guided by means of a crosshead and cast-
iron guides placed underneath the cylinder. The light wrought-iron
beam for working the plug rod, air pump, and feed pump is placed
overhead, and is worked from a continuation of the piston rod. The
vertical motion of the plug rod is maintained by means of motion
rods fitted on each side of the beam, and is guided with a bracket
bolted to the nozzle chest; the other end of the beam slides in cast-
iron guide bars, with gudgeon and sliding blocks fitted to it. The
air pump is placed centrally with the condenser, and is worked off
a continuation of the plug rod; the air-pump bucket foot and head
valves are fitted with small disc india-rubber valves, with guards.
secured by a single stud bolt in each. The feed pump has a hollow
plunger, and is worked off the overhead beam directly, the pump
being bolted to the side of the hot well. This engine goes far to
meet the requirements of the practical miner, being well arranged,
with easy access to all the parts; and it is much cheaper in first cost
than some other beam engines.
The pumps for this engine consist of two lifting sets 20 inches
in diameter, and one forcing set 26 inches in diameter, placed one
above the other, as shown in Fig. 123. In deep pits this plan is
always adopted, the lifting sets placed at the bottom of the pit
discharging into a cistern from which the forcing set draws its
supply. By this means the bucket and clack of the lifting set can
be withdrawn and replaced should anything go wrong, and the
water rise above the valve chests, which could not be done were the
forcing set placed at the bottom of the pit. The pump valves are
of the ordinary description, with inclined seatings; the plunger of
the forcing set has just the necessary clearance in the barrel, the
valve chests being arranged at the bottom; the water is discharged
into an air vessel surrounding the stand pipe, by which means the
shock in forcing it up is greatly softened.
For very deep pits a series of lifts is necessary. The following
example (Figs. 124 and 125) of pit work in Cornwall forms a good
arrangement: "The diameter of the steam cylinder is 90 inches.
The stroke is II in and 10 out, in miners' parlance; that is to say,
II feet in the cylinder and 10 feet in the pumps. The first lift of
pumps from surface, or 'grass,' is the house lift, which is employed in
lifting water from the adit to the condensing cistern of the engine.
The plunger of this lift is 12 inches in diameter, and the rising main the
STATIONARY ENGINES.
193
same size; it is usual to make the 'pumps' or rising main the same
size as the plunger. The adit is 31 fathoms below the surface, and

C
A
D-
7.0..
B
5.0
6.10.
8:0
Section thro' Line DE
6.0....
Fig. 123.-Pumps for Direct-acting Engine. ·
A, Forcing set. B B, Lifting sets. c, Stand pipe with air vessel.
conducts the water delivered from the pumps into the adjoining
valley. Of course it is an advantage to have the adit as deep as
possible, that the engine may have the minimum amount of work
13
194
MODERN STEAM PRACTICE.
to do. The second lift is situated 47 fathoms under the adit, and
is provided with two suction and two delivery clacks. The third
lift is 80 fathoms under adit; the fourth 120 fathoms, and the draw-
ing lift 140 fathoms. It is not advisable to put in a lift of pumps

+
MoFathom
Level
W.
UNZ
Surface Line
Fig. 124.-Pit Work, showing Pumps, Rods, Cisterns, &c.
with ordinary valves more than 40 fathoms long, because the valves
will not stand the wear and tear consequent on the great pressure
of the column of water. For ordinary use the clack valve with
STATIONARY ENGINES.
195
leather seats enjoys the greatest favour in Cornwall. The pole case,
that is, the case into which the plunger enters, is placed on one leg
of what is termed the H-piece. The H-piece is provided with a

170Fathom
Level
3rd Lift
150 Fathom
Level
710 Fathom
Level
md Lift
USI
MANAL
Tat
78 Fathom
Level
Fig. 125.-Pit Work, showing Pumps, Rods, Cisterns, &c.
door or cover, through which the suction valve may be examined.
The seating of the valve is made conical on the outside, and is
somewhat smaller than the conical neck formed to receive it in the
196
MODERN STEAM PRACTICE.
H-piece. Around the seating is wrapped a strip of coarse flannel
or baize, which makes the joint when the seating is forced into its
place. Above the door of the H-piece is placed the door piece,
which contains the delivery valve, which is fixed in the same way as
the suction valve. On the door piece the pumps or rising main, in
9-feet lengths, are placed. It is usual to place a wind bore directly
under the H-piece, leading into a cistern from which the pump takes
its water, but in the example under notice a much better arrange-
ment has been adopted. The cistern is placed just above the
suction valve, so that the water may more readily follow up the
plunger, and thereby cause the pump to be 'charged solid.' It is
of very great importance that no vacant space whatever should be
left in the pumps at the termination of the indoor stroke of the
engine, for if there be a space not occupied with water, then a shock
ensues, and the engine works as if working in 'fork,' or as if the
pumps were taking air. A 6-inch branch and blank cover is pro-
vided in the U-piece under the H-piece, for the convenience of
getting out anything which may accidentally drop into it. A blank
end and ‘matching' piece is put on to the H-piece under the pole
case, which takes its bearing on the timber bearers below. The
main rods are of Memel timber, perfectly sound and straight, with-
out knots or faults; for the first 50 fathoms they are 18 inches
square, for the next 40 fathoms 16 inches square, and for the last
30 fathoms 14 inches square. The rods are obtained as long as
possible, and are jointed by means of 'strapping plates,' bolts, and
nuts. The timber is sometimes cut in the form of a splice, and
made to form a lap joint, but in this case the rods are all butt-
jointed, the strapping plates are first firmly secured to the piece to
be attached, and then the piece is put in its place on the main rods,
the joint being brought up tight by powerful lifting jacks. The
main rods are kept in a line by means of wood guides fixed at
intervals. The plungers are cast with a plain core through them,
and a little longer than is necessary for the stroke; the casting
should be entirely free from specks-it is usual to cast them on the
side, but we prefer to have them cast on end. The plunger is
'stocked' on the mine; a piece of Memel timber, square in section,
and equal in diameter to the plunger, is obtained, about 12 feet
or 14 feet longer than the 'pole.' For a portion of its length equal
to that of the pole it is rounded down, and the pole is then forced
on to it. When stocked it is fixed by means of staples and glands
STATIONARY ENGINES.
197
to the main rods, a set off, or filling piece, being provided between
the stock of the pole and the main rod, to bring the axis of the pole
in a line with that of the pole case. Key-ways should be provided
in the joint between the stock and set off, and also between the set
off and main rod; when the staples and glands are firmly secured,
the keys—of hard wood—should be driven. It requires great care
that the 'pole connection' may be well made. Square nuts should
always be used for the pit work, because it is not always convenient
to have snugly-fitting spanners, and square nuts are then more
easily managed than others. The stuffing box of the pole case
should be packed with a well-made gasket and tallow.
"The working barrel of the 'drawing lift' is bored a little taper
for 9 inches or I foot at the upper end, that the bucket may easily
enter when dropped in from above; sometimes a door piece is pro-
vided above the working barrel, that the bucket may be examined
without the necessity of drawing it; but the plan is not a good one
when forking, as the water may rise too fast, and if it gets above
the door before the joint can be properly made the consequence
becomes serious. Directly under the working barrel is placed the
'bull's-head,' which is, in fact, a supplementary valve box, available
when the 'door piece' is under water. The neck of the bull's head
should be bored conical, and the valve seating geared similarly to
an ordinary bucket, but the ring should be a little conical, that it
may be prevented from falling through the neck of the bull's head
and retained in its place. A wrought-iron loop or staple is provided
on the seating, by means of which it may be fished up from above
when occasion requires. A small bar is placed across the staple,
which acts as a guard to the clack valve. The ring of the bucket
should be of wrought iron, nearly the size of the barrel, parallel on
its outer face and conical within. For the convenience of removing
the doors and replacing them again a chain with swivel and screw
is sometimes used, suspended from a piece of timber above. For
the facility of sinking, under the suction valve is suspended a
turned pipe which enters a stuffing box placed above the wind bore.
The wind bore is suspended in chains provided with lifting screws,
for the convenience of lowering as sinking proceeds. It will be
seen that as sinking proceeds it becomes necessary to lower the
drawing lift constantly, and that it may be conveniently done the
pumps are suspended in 'yokes' which take their bearings on tim-
bers fixed across the shaft. Yokes are glands made to fit the body
198
MODERN STEAM PRACTICE.
of the pump; they are placed directly under the ribs, and when it
is required to lower the lift the yokes are loosened to let the lift
drop through. Each time there is a new length or pump put in,
the bucket has to be lowered, and that it may be done without the
necessity of making a new drawing lift connection on the main rods,
the arrangement shown in Fig. 125 is introduced; a chain and hook
serves to make the connection between the main rods and the pump
rod, one staple only being used to steady the top of the pump rod.
This arrangement affords facilities both for drawing the bucket
and putting in a new pump. The pump joints are made with flat
rings of wrought iron, covered with baize and dipped in tar.
“Balance bobs are sometimes placed below the surface to take up
some of the weight of the pump rods. The connection with the
main rods is usually of wood; the vibration is given by the elasticity
of the wood. In the example shown in Figs. 124, 125, the connecting
rod is 15 fathoms long, and it is guided and steadied by means of
a plain turned pulley, which bears against a curved filling piece
bolted on to the connecting rod. Plungers are sometimes substituted
for balance bobs, and are, when so employed, constantly submitted
to the pressure of the column of water in the pumps; they are fixed
to the main rods precisely in the same way as the ordinary plunger."1
With the view of securing greater regularity in the motion,
and of equalizing the strain on the various parts, the compound
or double-acting engine has been introduced. An example of
this engine is shown in Fig. 126. The high-pressure cylinder is
36 inches in diameter, and the low-pressure cylinder 54 inches
in diameter, both working an 8-feet stroke in the pumps. The
piston rod of each cylinder is coupled directly to the pump rods,
and from the crosshead of each piston rod run two short connect-
ing rods, attached to two bell cranks; these cranks are connected
to each other at the top by the connecting rods on each side, thus
coupling the two engines and equalizing their duty. From the
longitudinal centre of one of the bell cranks the motion for the
tappet rod is taken, and from the back of the other one; an arm is
cast on each, with connecting rods for taking the crosshead for the
air pump.
The cylinders, with their covers and ends, are steam-
jacketed, and securely bolted down to a bed plate resting on foun-
dations of stone. The cast-iron guides for the piston-rod crosshead
are bolted to the under side of the bed plate, and the bottom end is
1 The Engineer.
STATIONARY ENGINES.
199
secured to the cast-iron beams upon which the bell-crank pillow
blocks and air pump and condenser are fitted. The air pump is of
the ordinary kind, fitted with india-rubber valves for bucket, head,
and foot valves. The condenser is a separate vessel placed alongside

©
Fig. 126.-Direct-action Compound Pumping Engine.
of the air pump, the waste-steam pipe coming in at the top, and
fitted with a packed gland. The valve gear for these engines is of
the usual description, with cataract pumps for regulating the number
of strokes. Although the machinery in these engines is rather com-
plicated, yet when economy in fuel and great regularity in working
200
MODERN STEAM PRACTICE.
have to be studied, they may be beneficially used for pumping water
from moderate depths and forcing or lifting it to moderate heights.
For moderate depths horizontal high-pressure pumping engines
have been used, connected to two bell cranks, directly from the piston-
rod crosshead, with long links, one on each side, taking the long
arm of the bell crank nearest the engine; and the two bell
cranks are connected to each other with wooden connecting links.
strapped with wrought iron, the pins for carrying these links
being nearer the centre of vibration of the bell cranks; thus the
stroke of the engine is somewhat longer than that of the pumps.
The bell cranks are so arranged that the one goes up and the
other down alternately, the steam being admitted into each end
of the cylinder as in ordinary high-pressure engines. The valve
mechanism is worked in a similar manner to that of the Cornish
engine, with tappets, cataracts, and all the necessary starting handles.
One useful feature in this class of engine is that it can be driven at
a higher or lower rate of speed, or more or fewer strokes given, as
the increased or diminished quantity of water in the pit may require.
The exhaust steam is made to pass through a series of tubes, around
which there is a constant circulation of cold water; thus the steam
is partially condensed, and the water pumped into the boilers again,
as in surface-condensing engines. A jet of steam, however, escapes
into the atmosphere at each stroke, which is due to the tube surface
not being of sufficient area, and to give the condensing vessel the
requisite area would make it too bulky and expensive. By this
method of allowing the exhaust steam to pass through the tubes
the water around them is heated to a high degree, and it can be
pumped into the boiler separately, or mixed with the water collecting
in the receiver; but in either case the tube surface acts as a feed-
water heater.
Horizontal high-pressure engines with slide valves and eccentric
motion are sometimes used for pumping water out of coal and other
mines. The valve gear is of the simplest description, consisting of
a rocking lever, fitted with a link for the valve rod, and a pin for
taking the gab end on the eccentric rod, which is made to throw
out of gear when required. The cylinder is securely bolted to one
end and the pillow block for the crank shaft to the other end of the
bed plate, which consists of a heavy box casting placed on each
side of the cylinder, running the entire length of the foundations,
and secured at the ends with cross pieces all cast together, and
STATIONARY ENGINES.
201
bedded on balks of timber, which in some instances form the founda-
tion. In these engines a long stroke and low rate of piston speed
are adopted, the motion for the pump being as simple as practicable
to suit the requirements. The connecting rod is coupled to the pin
on the crank, or cast-iron disc when so fitted, by a strap with jibs
and key, and the crosshead end has a short fork forged on the
connecting rod, fitted with straps, jibs, and keys. The crank shaft
is generally as short as practicable, and is supported by a bearing
on the bed plate, and one at the end carried on a pillow block bolted
to a box girder secured to the foundations. The fly wheel is made
heavy, and is placed at the middle of the shaft between the two
bearings; and at the extreme end a cast-iron crank is fitted, with
holes for the pin to vary the stroke of the pump when required.
The motion for the pit pump is transmitted by a wooden connecting
rod, strapped with wrought iron secured with bolts; the other end
of the rod taking a bell crank or arm fitted to the shaft on which
the bell crank is placed. The latter can be suited to any angle at
which the pump may require to be placed, as in working the edge
coal in certain localities.
In other arrangements, when the pumping shaft is vertical, the
motion for the pump is taken from a crosshead fitted to a pro-
longation of the piston rod, which is continued through the end of
the cylinder; the crosshead is guided the same as for the main con-
necting-rod end, and is connected to the bell crank by wooden rods
strapped with wrought iron. In such examples the pit pumps are
in duplicate, with a bell crank for each, connected together in the
same way; by this means the engine is better balanced, as one set
of pump rods is moving upward and the other set downward. The
pillow blocks for the bell cranks are fitted to balks of timber, and
the foundation for the engine is built of brickwork laid on the top
of these balks, the brickwork being overlaid with timber for bedding
the engine; the bed plate is secured by long bolts passing down to
the bottom of the foundation. There is no feed pump connected
to these engines, a steam pump being fitted for supplying the boilers
with water.
There are a variety of engines for pumping water of the geared
description, working plain cranks connected to bell cranks by a
single rod, the bell crank having a jaw cast on it, with a pin for
taking the end of the connecting rod passing through the jaws.
This type of engine is generally adopted for low lifts, and is a very
202
MODERN STEAM PRACTICE.
convenient form for transportation, as the cylinder is of small
diameter, with a high rate of piston speed, and reducing gear for
the pumps. When the engines are of the horizontal type the whole
of the wheel gearing should be arranged on the same bed plate
as the engine, and kept as compact as possible, since detached
machinery cannot be so securely bolted down on the foundations
as when all the parts are well bonded together on a single bed
plate.
PUMPING ENGINES FOR WATER-WORKS.
Having considered engines for pumping water out of mines,
we now come to that class of Cornish engine used for pumping
water for the supply of large towns. The construction of the
water-works engine differs materially from that of ordinary mine-
pumping engines. It is generally of the single-acting type; the
whole power of the engine is employed to lift a weighted plunger
placed at the end of the beam farthest from the cylinder, and
which acts as an accumulator, forcing the water up the stand pipes
to the height required for distribution through the mains. This
height of course depends on the altitude of the city or reservoir
above the source from which the pumps draw the water. The
engine beam is supported on columns, carrying a spring beam on
which the main pillow blocks are securely bolted, and the ends
are let into and rest on the end walls of the engine house. The
perpendicular motion of the piston rod at the one end of the beam
and of the weighted plunger at the other end, is effected by means
of parallel motion of the ordinary description, with connecting links
from the crosshead, radius, and parallel bars. The air pump is
worked off the centre of the back link for the parallel mɔtion, at
the main pump end; while the feed pump has a shorter stroke, being
connected by means of a long rod with a pin passing through the
main beam. The plug rod for working the tappets of the valve
gear is attached to the beams in like manner, the valve gear being
fitted with all the necessary cataracts, as in the mine-pumping engine.
An engine house incloses all the machinery except the stand pipes,
which are of great height, and require a separate tower. As the
water in these pipes is liable to become frozen in winter, objections
STATIONARY ENGINES.
have been taken to them, and as they are
mainly raised to equalize the duty on the
engine some authorities consider a large air
vessel preferable. The pipes must be fitted
with a valve loaded to a certain pressure on the
delivery side, so that in the event of derange-
ment from a pipe bursting, or from a diminu-
tion of pressure in the main, the engine would
still have about the same duty to perform, as
the water has to be forced through the passage
covered with the loaded valve before it is taken
into the air vessel, a double-beat valve being
used for that purpose. This description of
valve gives a large area for the exit of the
water, while the surface acted upon for raising
the valve is only a small portion of the total
area of the passages; thus less weight or pres-
sure on the top of the valve is required. There
is also a blow-off valve fitted, and loaded to a
0
Fig. 127.—Single-acting Pumping Engine with Stand-pipe Tower.
203

204
MODERN STEAM PRACTICE.
certain weight, so that in the event of any undue pressure in the
mains the water escapes, and prevents the pipes bursting. This
valve acts in a similar manner to relief valves fitted to feed pumps
for steam boilers, the water escaping into the well or reservoir from
which it is drawn.
Double-cylinder expansion engines have been successfully adopted
for water-works; where a high rate of expansion is required they
work admirably, but the complication they entail is not desirable.
For moderate power the single cylinder is to be preferred as suffi-
cient for all practical purposes, but for large power we would recom-
mend a small high-pressure cylinder working in connection with a
large low-pressure cylinder, as the strain on the machinery is not
so much felt, nor do the parts require to be of extra strength, as the
piston rods and adjuncts would require to be, were the high-pressure
steam from the boiler admitted on the top of a large piston.
We are indebted to Mr. Marten, C.E., of Wolverhampton, for the
following particulars of the pumping engines in use at the water-
works there.
The two engines at Tettenhall are single direct-action non-con-
densing engines. The cylinders are 36 inches in diameter, and
9 feet 6 inches stroke. The plunger pumps are 13 inches in
diameter, with a lift of about 300 feet. The steam is admitted to
the cylinder at a pressure of about 35 lbs., and is cut off at two-
thirds of the stroke. The boilers are cylindrical, two in number,
26 feet in length and 6 feet in diameter, with two tubes in each 25½
inches in diameter, and internal flues; the flame from each fireplace
passes along the tube, thence round to the front, again by the side
of the boiler next to its tube, where the two unite and pass along the
bottom into the chimney. The boilers are covered with loam or
moulding sand to a depth of about 6 inches from the top. This
substance, which should be protected by a roof from blowing away,
is found to be a very good non-conductor, little heat radiating
through it to the upper surface; it has also this advantage over
nearly all other materials employed for the same purpose, that no
condensation can take place in it within 2 or 3 inches of the boiler
plates, since for that distance it forms a sand bath as hot as the
steam, which, in the event of a leakage, blows through it dry, and
consequently corrosive action on the plates is prevented. When
escape and condensation of steam takes place, it is detected by a
moist patch on the surface of the sand. With a material of this
STATIONARY ENGINES.
205
description, any portion of the top of the boiler can be uncovered
with a shovel, and
examined at once.
For the purpose of
experiment, steam
blows at two places
in the boilers at Tet-
tenhall were suffered
to remain unrepaired
for a couple of years,
in order to test the
value of this covering,
and the result was
an entire absence of
corrosive action on
the plates. In the
opinion of Mr. Marten
loam sand is much
preferable for this
purpose to any other
material, provided
that it is protected by
a roof or covering. It
is much cheaper than
felt, brick, or sheet
iron casing with air
space; and much
superior to furnace
ashes, cinders, or
riddlings, which are
often placed over
boilers, as these sub-
stances frequently
contain acids and
other chemical im-
purities, which on be-
ing brought in con-
tact with waste steam
act very injuriously
on wrought iron.

Fig. 128.-Tettenhall Pumping Engines. Elevations and Plan.
206
MODERN STEAM PRACTICE.

X---
A
E F
K
K
H
I
HA, Steam cylinder.
B, Pump rods.
c, Steam valve.
E, Equilibrium valve.
F, Exhaust valve.
G, Crosshead.
H H, Columns.
I, Buffing pieces
K, Plug rod.
L, Wrought-iron lever
for working plug
rod & feed pump.
м, Feed pump.
M,
N,
Feed-water heater.
B
M
N
Plan at X.X.
ன
L
Fig. 129.-Tettenhall Pumping Engines. Side Elevation.
STATIONARY ENGINES.
207

F
-
K
A
K
C
B
Fig. 130.-Tettenhall Pumping Engines. Transverse Section.
-
208
MODERN STEAM PRACTICE.
The steam, equilibrium, and exhaust valves are of gun metal, and
on the double-beat construction.
Their areas are as follows:
Steam valve,........
Equilibrium valve,
Exhaust valve,
50
78
50 sq. in.th area of cylinder.
= th
""
""
th
The piston rod and pump rod are connected with a crosshead
working on V-slides attached to the supporting columns. The plug
rod and the valve motion are worked from a slight wrought-iron
beam under the cylinder floor, connected at one end to the cross-
F
C
KC
E
E
B
A
Fig. 131.-Sectional Elevation of Pump.
head, and at the other slung to
parallel links. The feed pump is
also attached to this beam, the
water for the feed being passed
through a heater situated in the
corner of the engine house, and
formed by an enlargement of the
waste-steam pipe. This heater is
I foot 6 inches in diameter; the
feed pipe is conducted along its
centre for some distance, and oc-
cupies about two-thirds of its
area. The engine is regulated by
a water cataract, governed by a
small ratchet wheel and screw.
The number of strokes per min-
ute varies from three or four to
ten or eleven, the average speed
of piston being 130 to 140 feet
per minute; the quantity of water
delivered per stroke is 56 gallons.
The pumps are of the plunger
type, and have the valves placed
at the top of the barrel; by this
means no air can collect at the
top of the pump, as in ordinary

A, Suction pipe. B, Suction-valve chest. c, Delivery. plunger pumps for colliery pur-
valve chest. D, Plunger. E, Stuffing box
and gland. F, Stand pipe.
poses. The area of each plunger
is 132 square inches, and the
pressure on its bottom is 130 lbs. per square inch-making a total
dead load of 17,160 lbs., equal to a pressure of 1634 lbs. per square
STATIONARY ENGINES.
209
inch on the surface of the steam piston. These engines are
worked at a fair duty, performing about 27,000,000 lbs. lifted
I foot high per minute, with a consumption of I cwt. of the
small slack in the neighbourhood; with Newcastle or Welsh small
coal they would perform a duty of 36,000,000 lbs. The pump
valves are of the ring de-
scription, rising on a central
spindle; they are made of cast
iron galvanized, beating on
wooden faces. Originally they
beat upon a mixture of lead
and tin, but this soon became
loose in the seating, causing
leakage; oak was then tried,
but the acid peculiar to this
wood corroded the cast iron,
and it had to be discontinued;
lancewood, box, and beech

A
Fig. 132.-Plan of Pumps.
B
have also been tried, but no wood answers so well as holly, which
is now used for this class of valve. The area of the suction valve is
325 square inches, being about two and a half times the area of the
plunger; and that of the delivery valve is 163 square inches, or about
one and a third times the area
of the plunger. The enlarge-
ment of the suction valve to
this extent is found to be very
serviceable where the velocity
of the plunger is likely to be
great in the ascending stroke.
The water was originally deli-
vered over a stand pipe 180
feet high, whence it flowed by
gravitation to the town; but
now a reservoir is substituted,
and the stand pipe dispensed
with.

C
Fig. 133.-Valve for Pump.
A, Valve. B, Guide bar. c, Valve seat.
DD, Wooden beats.
The engine at Goldthorn Hill is a low-pressure condensing beam
engine. The cylinder is 48 inches in diameter, with an 8-feet stroke.
The boilers are 30 feet long and 7 feet in diameter, with two tubes,
2 feet in diameter beyond the furnace, and 2 feet by 2 feet 4 inches
14
210
MODERN STEAM PRACTICE.
at the fireplace. The pressure of the steam is about 15 lbs. per
Fig. 134. -Engine at Goldthorn Hill Water-
works. Elevations and Plan.
square inch.

To avoid the almost constant trou-
ble caused by leakage at the steam
valves on the boiler tops, from ex-
pansion and contraction of the main
range of steam pipes, the main steam
pipe should have a quadrant curve
between the boilers, so as to allow for
expansion and contraction without a
thrust sufficient to break any joints.
This arrangement is useful and effi-
cient when there is one steam pipe
leading off from between two boilers;
when, however, the steam pipe leads
off from one side, or where there is a
range of more than two boilers, it is
not applicable, and in such cases, in
the absence of packed expansion
joints, no plan is so simple and effec-
tive as the wrought-iron diaphragm
joint, consisting of a couple of circu-
lar wrought-iron plates, about two
and a half times the diameter of the
pipe, dished out about 3 inches, and
rivetted together at the outer rim and
to flanges on the main range of the
steam pipe.
Another useful, although frequently
overlooked, point of detail in connec-
tion with the boilers, consists in lead-
ing the hot and cold feed and blow-
off into and out of the boiler through
the same pipe. This arrangement
avoids the numerous holes usually cut
in boilers for these purposes, and any
impurity which may enter the boiler
with the hot and cold feed is de-
posited near to the blow-off. In the
present instance the pipe is of wrought
STATIONARY ENGINES.
211
iron, and is rivetted on the under side of the front end of the boiler.
The arrangement of the valves is somewhat similar to those of a
bath, where the hot, cold, and outlet valves all take off the same
pipe. It is also important that the feed should enter the coldest
portion of a boiler, which, from the action of the currents in those
with internal flues, is just under the fire grate. When this is not
attended to the seams and rivets are apt to leak from the sudden
changes of temperature to which they are subjected.
Instead of delivering the water over a stand pipe, as origi-
nally in the Tettenhall engine, the Goldthorn Hill engine delivers
through an air vessel into two reservoirs lying near the engine,
holding together 1,500,000 gallons, and raised about 20 feet above
the top lift. The reservoirs are arched over, and covered with
2 feet of soil, for the purpose of preventing vegetation in the water
and variation in its temperature. These objects are well secured,
as the water remains for months at the same temperature, and
perfectly free from all vegetable or animal impurities. The reser-
voirs are kept from being overfilled by a self-acting check valve,
which shuts against any supply beyond a certain limit; and the
man in charge of any pumping engine at a distance at once knows.
when to stop work. The valve is so arranged that when the engine
ceases to work the supply from the reservoir to the town is main-
tained through the flap valves placed underneath the self-acting stop
valve. The object of a stand pipe is that the water may be always
delivered from the engine over one uniform height, and consequently
of one uniform pressure on the engine, whatever varying circum-
stances may affect the delivery after the water has once passed the
top of the stand pipe. For this purpose it is useful, but it is rather
a costly and unsightly mode of attaining what in practice is found
to be an unnecessary degree of perfection, as at a tithe of its cost
all the necessary safety can be secured by pumping into an air
vessel with a self-acting valve on the delivery side, so that, in case
of a pipe bursting, or any sudden diminution of pressure taking
place, it would be impossible for the engine to "go out of doors,'
as it is technically termed, at more than a certain regulated speed,
by the partial contraction of the area of discharge through means
of the check valve. Unless, too, the stand pipes are carefully cased
in winter they are in great danger of being frozen, and very serious
consequences have arisen from this cause. The great weight of the
column of water requiring to be set in motion from a dead stand at
212
MODERN STEAM PRACTICE.
To Steam Throttle
A, Accumulator or
hydraulic cylinder.
B, Loaded piston.
Valve.
B
A
c, Lower weights.
D, Upper weights.
E, Spiral spring.
Fig. 135.-Valve Regulator.
each stroke of the engine is
also an objection to the use
of the stand pipe.
As a substitute for these
tall stand pipes, the follow-
ing arrangement has been
adopted in the St. Peters-
burg water-works, recently
carried out by Messrs. R.
Laidlaw & Son of Glasgow.
A throttle valve or regulator
is placed so as to be con-
trolled by the pressure of
the water in the main. The
pressure
acts through a
small accumulator or hy-
draulic cylinder fitted with a
loaded piston and attached
to the regulator. This loaded
piston, as it moves with
the varying pressure in the
mains, acts on the throttle
valve, and thus regulates
the motion of the engines.
A further arrangement was
made whereby the steam
would be automatically and
instantaneously shut off if
any burst took place. Fig.
135 shows the arrangement
adopted. The lower weights
are slightly less than the
pressure on the water piston,
and thus the piston spindle
is kept in contact with the
upper weights; the steam
valve being then half open,
any increase of pressure thus
causes the upper weights
to be raised and the spiral

STATIONARY ENGINES.
213
spring is compressed and the regulating valve closed. If a burst
takes place the lower weights drop and instantly close the steam
valve.
The successful working of any pumping engine is dependent in
a great degree upon the perfection of the pump valves, which must
be so arranged as to deliver the water with ease and rapidity, and
without any concussion in closing. As an illustration of the great
practical importance of this question, it may be mentioned that when
the Cornish pumping engine was first used for water-works pur-
poses on a large scale, it was on the point of being altogether
abandoned on account of the imperfection of the pump valves.
The valves were of large area, and constructed on the old butterfly
principle, so that, under the heavy pressure at which they were
worked, the concussion caused in shutting was so violent as to occa-
sion serious alarm for the safety of the machinery and foundations.
The difficulty of constructing a valve which should present a maxi-
mum area of discharge with a minimum area of surface exposed to
the concussion of the recoiling load at the termination of each
stroke of the pump appeared for a time insurmountable, but was,
however, happily got over by the introduction of the double-beat
valve.
This valve, as already explained, has the upper area con-
tracted, and by the difference of the upper beat and the inside of
the lower one a surface is afforded for the water to act upon in
lifting and shutting the valve. The valve having two points for
the water to escape by, a very slight distance of lift gives a large
area for discharge; and the area upon which the recoiling column
descends being only the difference between the upper and lower
areas, and not the entire area of discharge as in the old butterfly
valve, forms a surface insufficient to cause any concussion. This
valve also affords, under all circumstances, a means of regulating
the pressure tending to shut the valve, whatever may be the height
of the column of water or the total pressure of the recoiling column,
by adjusting the difference of area of the upper and lower beats
inversely in proportion to the height of the column.
For the ordinary purposes of small lift pumps and colliery engines
the butterfly valve is serviceable, as there are no expensive faces to
be ground up or deranged by impurities or grit in the water, and
it can be readily repaired on the spot. For a higher class of work
there is no description of valve answers better than the double-beat
214
MODERN STEAM PRACTICE.
ring valve, similar to the one employed in the engines at Tettenhall
and Goldthorn Hill. Large valves of this construction, from 16 to
20 inches in diameter, answer well made of cast iron with wooden
beats; smaller valves, from 8 to 15 inches in diameter, are better
made of gun metal, working face to face, some of the latter descrip-
tion having worked for more than two years, under a pressure of
260 feet of head, without any perceptible wear.
At the Hull water-works a special description of valve has been
adopted in one of the pumps with great success. It consists of a

D
C
0 0 0 0 0 0 0
Wooo ooooo
B
Fig. 136.—Gutta-percha Ball Valves on. Metal Seatings.
A, Valve seats. B, Gutta-percha balls. c, Guard pieces. D, Holding-down bolt with stuffing box
and gland.
pyramid of circular seats, one above another, in each of which there
are a number of small circular beats about 2 inches in diameter,
into which a corresponding number of gutta-percha balls drop. It
is 22 inches in diameter, and works under a head of 160 feet, in
connection with a plunger pump with a direct-action steam cylin-
der. The action of this valve, as will be seen from Fig. 136, is very
STATIONARY ENGINES.
215
simple. It was substituted for the double-beat valve in use, and
immediately upon starting it lightened the burden of the engines
about 168 lbs., and has since given great satisfaction. This valve
possesses other advantages. In the first place it is much safer than
any other form of valve, as will be easily seen. Supposing a piece
of wood or other material should pass through the pump, as is
frequently the case: if the wood should be caught on the beat of
the ordinary valve, it would hold the whole valve open and let the
engine "come out” with a run, possibly causing considerable damage;
but with the small balls of this valve a piece of wood so caught
could only affect one out of fifty-six balls-so small a percentage
of the whole opening that it would merely enable the man in charge
to perceive that there was some trifle amiss by an increase of leak-
age. In the second place, the balls, being nearly of the same
specific gravity as the water, are floated open the moment the cur-
rent turns in their favour; whereas in all other valves, in addition
to the column of water to be lifted, there is also the weight of the
heavy metal valve to be opened and held suspended during each
stroke. With large valves this point becomes one of great import-
ance, as they often weigh 5 to 6 cwts. each. Again, in this valve,
whilst the area of discharge may be made fully equal to that of the
plunger, the area exposed to concussive action in closing is reduced
to the smallest possible limits, being practically the impinging force
upon one ball, the last one that shuts, orth part of the total area
of beating surface; this is owing to the fact that the balls do not
all rise to the same height above their seats, and consequently, as
the force of the current acts upon each ball separately, on the
cessation of motion each shuts in accordance with the height it has
to fall, and a communication exists between the water on the upper
and under side of the valve until the absolute closing of the last
ball. The result is, that although the difference in time between
the falling of the various balls must be exceedingly minute, it is
such as practically to prevent all concussion. Lastly, the valves
constructed on this plan are very easily repaired. It is only neces-
sary to keep a few spare balls ready, to be inserted in the place of
any that may become damaged; and the old ones, melted and
recast in a mould kept for that purpose, are again as good as new.
Where it is proposed to work with a high pressure of steam, cut
off so as to allow of a considerable expansion, the beam engine is
to be preferred to the direct-action engine; the latter, as a rule,
འ
A
216
MODERN STEAM PRACTICE.
when working under a high initial pressure, is apt to start off at a
speed which jars and strains the whole of the machinery. Besides,
the speed attained by the piston as driven indoors at the beginning
of the stroke is many times greater than the average velocity per
minute, and therefore, unless all the parts are made proportionally,
the bearings very quickly wear out, and the machinery is loose at
every joint. In a beam engine, on the other hand, a very large
proportion of the initial force is absorbed in overcoming the inertia
of the heavy beam, which thus serves as a reservoir of surplus force
in the earlier part of the stroke, giving it out during the later part,
with the result that a comparatively steady velocity is maintained
throughout the stroke, much to the advantage of the whole ma-
chinery; indeed, it is only with this adjunct that expansion can be
safely carried to a very high degree. The beam, in fact, acts like
a fly wheel, storing force as required, and is attended with precisely
the same beneficial results.
For pumping a large quantity of water through an unusually
great length of main pipe, under a heavy pressure, a description of
engine may be preferred, consisting of a pair of high-pressure
expansive double-acting beam engines, coupled together at right
angles to the fly-wheel shaft. The pumps in this engine should be
of the combined bucket and plunger type. Each pump should have
an air vessel and back-flap valve, with a blow-off valve loaded to a
certain weight, so that in the event of any recoil in so great a length
of main the pumps would not burst. Along the main pipe, at each
50 feet of elevation above the pumps, a back-flap valve is required,
so that in case of any pipe bursting the whole main would not be
run dry. The leading point to be kept in view in the design and
construction of engines for such purposes is the maintenance of a
constantly uniform flow of water through the main pipe from the
pumps. This is provided for by the compound double-acting
pumps and large air-vessel accommodation, together with the
coupling of the engines at right angles. Many engineers prefer a
double-cylinder engine for conducting expansive operations; but
although in some cases such an engine is advantageous, as for
driving machinery where great regularity of motion is a desideratum,
yet for large pumping engines the single cylinder is preferable, as
double-cylinder engines are much more complicated, and all useful
degrees of expansion can be obtained sufficiently with a single
cylinder.
STATIONARY ENGINES.
217
The next example gives the plan of the water-works as adopted at
Berwick-on-Tweed. The works comprise two tanks for storing spring
water, one with the top water at a level of 16 feet above ordinance
and the other 12 feet higher. The upper tank, which occupies the site
of an old quarry, is 80 x 50 feet and 7 feet deep, and has three walls
built of dry rubble stones, to admit the water from the springs

A----
C-
་་་་
Upper Tank
-B
Howe
-D
Section C D
Lower Tork
Upper Tank
Section A B
Fig. 137.-General Arrangement of Tanks, Engine and Boiler Houses, Berwick-on-Tweed
Water-works.
rising behind the walls; the wall next the river is built of water-
tight masonry in cement, with a puddle wall at the back of it. The
lower tank, which is 70 × 20 feet and 7 feet deep, has solid walls
like the large one, and receives the water from several springs, which
rise at a lower level than those stored in the upper tank. An engine
and pump and boiler, with engine and boiler house, complete the
works at the collecting ground; and a 9-inch rising main conducts
218
MODERN STEAM PRACTICE.
the water to a high-level reservoir, placed at a level of about 200 feet
above ordinance. The springs, of which there are several, are esti-
mated to yield 230,000 gallons in the twenty-four hours, and the
engine working ten hours per day is calculated to raise 61 cubic feet
per minute.
Q21
22 d 5'
The height being 178 feet, and the length of track
8145 feet, with a diameter for the rising main of 9 inches, the head
allowed for friction was 24 feet, found by the formula h=
which makes a total height of 202 feet. To calculate the horse-
power required to raise the water to the high reservoir: By the
61½ × 202 × 62½
ordinary method
we have a result of 24, and adding
33000
a fourth more for loss 30 horse-power for the engine. It is worthy
of remark that the pressure gauge on the air vessel registers an
increase of 10 lbs., which is equivalent to 24 feet of head while

Fig. 138.-Engine and Pump.
working, and when standing the pressure is reduced to that due to
the statical pressure, namely, 178 feet.
The engine, which is non-condensing, and is placed vertically, is
STATIONARY ENGINES.
219
calculated to work with a pressure in the boiler of 40 lbs. per square
inch. The piston is 17 inches in diameter, the stroke being 3 feet,
and the number of revolutions of the crank about thirty-five. The
pump is double-acting, consisting of bucket and plunger; the dia-
meter of the barrel is 18 inches, that of the plunger 13% inches,
with a stroke of 3 feet. The bucket packing consists of rings of
gutta percha about 1 inch square in

Fig. 139.-Pump Bucket.
section, let into grooves cut in the
bucket; two holes, ½ inch in diame-
ter, are bored in the top, communicat-
ing with the grooves, the water pres-
sure being always constant presses
out the rings of gutta percha, mak-
ing them perfectly water-tight. The
valves are of the ordinary flap kind;
a large air vessel is fitted to the
pump, 3 feet 6 inches in diameter
and 14 feet 6 inches high. The mo-
tion for driving the pump consists of
a pinion on the engine shaft and spur wheel on the pump shaft,
the gearing being in the proportion of 3 to I. The fly wheel on
the engine shaft is II feet in diameter, and weighs 5 tons 12 cwts.;
a balance is placed on the spur wheel to counterpoise the weight of
the pump ram. The boilers are 26 feet long and 6 feet 6 inches in
diameter, with a single flue 3 feet 3 inches in diameter; the fire
grate is arranged underneath, with return side flues; thickness of
plates in body of boiler, 3% inch; of end plates, ½ inch. The
chimney stalk is 84 feet high, 7 feet 6 inches square at the level of
the ground, and 3 feet 6 inches square at the coping. The boiler
is fed with a small plunger pump, worked off the end of the piston
crosshead, the water being previously heated in a tank by the
exhaust steam. The engine and pump cost £950. The rising
main, 9 inches in diameter, has turned and bored joints except
where lead and yarn ones were required for sharp bends; and also
four air and four scouring plug valves with a clack valve immediately
above the air vessel and another half-way up the track. A branch
pipe leads into the lower service cistern, fitted with a self-acting
ball valve, 6 inches in diameter. The pipes cost when laid about
125. per lineal yard. The actual work done by the engine can be
determined by means of a cast-iron measuring box placed at the
220
MODERN STEAM PRACTICE.
upper end of the pipe, with a trough having a flap valve in the
bottom for passing the water direct into the cistern if required.
By means of an indicator diagram we can calculate the amount
of work required to raise the water from the lower tank to the high
reservoir as follows:-The measuring box is 6 feet x 3 feet 3 inches x
3 feet 13% inch, and has a capacity of 60·64 cubic feet. The aver-
ages of four experiments made by the engineer for the works gave
58.25 seconds as the time required to fill the box, which represents
a discharge of 62.5 cubic feet per minute. The area of the plunger
of the pump being 9398 foot, and the double stroke 6 feet—the
engine making thirty-five revolutions per minute, which represents
11.66 of the plunger-gives a theoretical discharge of 65.73 cubic
feet per minute, and shows a ratio between the theoretical and
actual of 100: 95, or a loss of 5 per cent. This represents an amount
of work = 62.5 cubic feet, weighing 3906 lbs., raised 202 feet high,
which is equal to an expenditure of 23.9 horse-power. The indi-
cator diagram showed an effective pressure of 23 lbs. per square
inch, which with thirty-five strokes per minute at 6 feet, with a piston
of 224'5 square inches, is = 33 horse-power, showing a loss for fric-
tion, &c., of 27 per cent.
CONSUMPTION AND COST WITH VARIOUS KINDS OF COAL.
per ton.
per hour.
Broomhill Nuts......at 6/6 burn 3'7 cwts.
Berwick Hill..... 9/6
Scremerston.
...
per horse-power
per hour.
= 17.3 lbs.
= 11'7,,
,, 2'5
...
›› 9/6 ...
2'7"
...
= 12.6
""
per horse-power
per hour.
= '602d.
= ·586d.
=
...
•631d.
The above table compares the consumption and cost of coal with
the actual quantity of water delivered, which is equal to an expen-
diture of 24 horse-power. If we compare the expense of working
this engine with larger ones in use at some of the English water
works, and use the same standard-namely, the cost of raising 1000
gallons 100 feet, which is equal to 1,000,000 foot-pounds, we find--
The Trent Water-works Company at Nottingham
Boulton & Watts, 29 horse-power, 1809, condensing,
""
30/2
76
1828,
Berwick Pumping Engine, 1871 (high-pressure),
..cost $287d.
›› '543d.
*358d.
,, *333d.
""
*340d.
STATIONARY ENGINES.
221
STAND PIPES, ETC.
Stand pipes were originally introduced to equalize the weight on
the engines, and give the required pressure in the main pipes for
the town supply. The arrangement under notice was erected at
Tettenhall, and consisted of two pipes, one of them open at the top,
inclosed in a tower of brickwork, as shown in Fig. 140.
We are indebted to Mr. Marten, C.E., for the following descrip-
tion of its action:-The engine having only steam on the under
side of the piston lifted the pump rods, and their own weight
was just sufficient to bring them down along with the plunger of
the pump if the stand pipe was only full to the junction at the top,
but it was not enough to let them force the water to the top of the
tower. When the town required all the water the engine pumped
regularly, being worked by a cataract to give the requisite number
of strokes per minute; but if the town did not take the water the
engine stood, because the rods were not heavy enough to make the
down stroke. Whenever the town drew off some water the engines
started again. The state of the water in the stand pipe was shown
in the engine house by a mercury gauge, and the engines were
regulated to keep the stand pipe full up to the junction. There
were no escape valves, because they were not needed; if by any
chance the sudden shutting of the large mains in the town, or air
returning up the main, threw the water over the top of the stand
pipe, it filled the cap of the tower and ran out at small holes, falling
like rain, but this very seldom happened. When there is much
danger of overflow near a town an overflow pipe is fitted, which
allows the water to flow into the reservoirs from which it is pumped.
At Tettenhall there was no provision made for breaking the fall of
the water in the descending leg of the stand pipe. This want caused
much air to be carried into the mains, so that the water when first
drawn was often as white as milk with the minute bubbles of air,
but it cleared in a very short time. The chief use of the stand pipe
was to render undue pressure on the mains impossible, as there was
at first no reservoir. When a reservoir exists, however, always open
to the pumping main, it serves the purpose of a stand pipe, and
prevents any undue pressure.
In some cases, as the South Staffordshire water-works at Bromhills
(Fig. 141), the stand pipe is placed on a hill on the line of the main,
about half-way between the engine at Lichfield and the main reser-
222
MODERN STEAM PRACTICE.
voir at Walsall, and it there acts both as an air pipe and a safety

B
Fig. 140.-Stand Pipe and Tower.
C

A, Pipe from the pumps. B, Pipe to the town. c, Cap. D,
Ladder. E,
Windows.
E
STATIONARY ENGINES.
223
pipe. At Bromhills there is only one stand pipe, open at the top,
and placed in the centre of a brick tower; if it overflows the water
falls down the tower, and flows into a canal.
Mr. Marten states that he has found a 6-inch weighted valve, on
a 9-inch pumping main, do as well as a stand pipe, and it prevents
the required pressure from being exceeded. At Stourbridge a small
district near the reservoir needs higher pressure than the reservoir
gives, and a valve on the main is weighted to give the required

Standpipe
Bromhalls
Engine
22 rn Main
4 Miles
5 Miles
Lichfield
Reservoir
Walsall
Fig. 141.-Stand Pipe, &c.
pressure, the escape water passing into the reservoir. This valve
can be even made self-acting, as it does not quite close, and allows
the quantity of water to pass delivered by the engine at its ordinary
speed; and when the engine delivers the quantity of two or three
extra strokes, the pressure rises, but never beyond the 50-feet extra
head required. As the main to the reservoir is also the supply main
there is a back-flap valve on it in the same box as the weighted
valves, which opens whenever the engine stops, and lets the reser-
voir water return. There is also a similar valve at the engine house,
about half a mile from the reservoir, which enables the engine to
send direct into the town without a reservoir or open-ended pipe;
but this plan is not adopted except in cases of repair of the main
or reservoir.
Various valves are in use for preventing the engine running away
if a main pipe bursts, and they are generally placed beyond the air
vessel when so fitted. A catch, kept open by the pressure, is some-
times used; if the pressure in the main pipe falls, the engines are
stopped by this catch preventing the steam valve from opening.
Mr. Marten states that when testing a long main he was surprised
to note the instantaneous action of the water; any alteration of the
pressure was so instantly seen at the other end that no difference
in time could be detected. On the South Staffordshire main from
Lichfield to Walsall, at every 20 feet or so of rise a back stop valve
224
MODERN STEAM PRACTICE.
is fitted to prevent the return of the water if the engine is stopped or
a pipe bursts. In the case of the latter accident it is of importance
to prevent much water escaping, as the pipe is laid for some distance
along a railway embankment formed of gravel and sand, easily
washed away. During the testing of the main one pipe burst where
there had been a chill in the casting, but so little water came out
as to do but little damage to the embankment. The engine stopped
because of the sudden drop of the pressure acting on the catch
already referred to; and the return of the water was prevented by
the back valves, even the water between the burst and the next
valve placed above being retained, as no air could get in except in
gulps at the break.
Many things which were once considered necessary to the safety
of water-works are now superseded. The constant system, or one
reservoir for the whole town, instead of each customer having one
for himself, has caused great change. Instead of the supply pipes
being led off small pipes called "riders," they are put direct into
the main, and all the ends of the main are connected, so as to give
greater circulation to the water. The use of cisterns is discouraged
as much as possible, as they are likely to deteriorate the quality of
the water. Separate pipes to the reservoir—one to pump through
and the other to supply through-are not used, but only one pipe
for both purposes.
It often happens that the supply is obtained from a spot between
the town and the high ground where the reservoir can be made:
one pipe from the reservoir is then found sufficient, and the engine
pumps into it. If the town, as in the middle of the day, requires
all the water, it is sent direct into it; when the demand falls off, it
is partly delivered into the reservoir; if there is an extraordinary
demand, both the reservoir and engines supply the town. By this
arrangement one main answers, and it may be much smaller than
if two were used, one to the reservoir and another from it to the
town. Much of the water, also, is pumped at a less pressure than
would be needed to pump it entirely into the reservoir.
Stand pipes may be considered as among the precautionary con-
trivances once deemed requisite for supplying water to a town; but
the supply can be obtained direct from an engine as easily and
safely by properly loaded valves, although it is found a more expen-
sive plan. The engines do wretched duty, as the calls upon them
are so irregular. An engine always does best when working regu-
STATIONARY ENGINES.
225
larly at full speed, and therefore a reservoir to receive the pumped
water should be provided if possible.
When pumping under a heavy pressure it is usual to have an air
vessel to each engine on the delivery pipe beyond the pumps;
and sometimes a larger one is placed on the main pipe into which
the others deliver. Of course care must be taken that each air
vessel has its full complement of air; sufficient is usually drawn in

B
O
D
E
B
Fig. 142.-Air Vessels.
A A, Pumps. B B, Air vessels. cc, Sluice valves. D, Main air vessel. E, Main pipe to the town.
by the pump, and a very small hole or tap is sometimes inserted to
supply it.
When more than one pump is arranged for pumping into an air
vessel, stop valves must be fitted on the delivery pipe, to prevent
the return of the water when either or both pumps are not at
work. The air vessel is of great importance, as it equalizes the flow
of the water through the main,
and less weight is required on
the top of the plunger for the
down stroke. The capacity of
the air vessel should be about
ten times the volume of water
delivered by each stroke of the
pump.

A relief valve should be placed
on the delivery pipe to prevent
undue pressure; it is fitted with
a lever and weight. In some
B
A
E
C
Fig. 143.—Relief Valve.
examples a solid plunger is A, Solid plunger. B, Piston. c, Slotted pipe leading
adopted, having a piston and
rod at the top, the piston work-
to reservoir. D, Pipe connecting the cylinder with
the main. E, Waste pipe leading to the reservoir.
ing loosely in a cylinder connected to the main by a small pipe.
The plunger A rises when the pressure increases, being larger at A
than at C, and allows the water to flow through the slots into the
15
226
MODERN STEAM PRACTICE.
reservoir from which it is pumped, thereby relieving the pressure.
The plunger falls again by gravitation, and
the piston B, acting like a cataract, prevents
the action taking place too suddenly.

F
Б
་་་་་་་་་
G
The pressure valve is placed beyond the
air vessel on the main pipe; its sole use is
to prevent the plunger of the engine de-
scending too rapidly in the event of one of
the main pipes bursting. The example under
notice consists of a plunger, loaded with a
certain weight to suit the head of water; on
the bottom of the plunger a double-beat valve
is secured by a cotter, the valve working on
a seat bolted down by bolts passing through
it, and secured by lugs at the bottom of the
bent pipe and nuts at the top bearing on
the valve seat. At each stroke of the en-
A, Plunger. B, Valve chest. c, Guides, gine this valve is lifted, and consequently
D, Valve. E, Stuffing box.
F, Branch pipe from pump. G, De- were a pipe bursting the engine has still the
same duty to perform. As has been stated,
a modification of these valves has been successfully used instead of
stand pipes.
Fig. 144.-Pressure Valve.
livery branch. w, Weight.
PUMPING ENGINES FOR DRAINAGE WORKS AND
GENERAL PURPOSES.
THE LONDON DRAINAGE SYSTEM.
The Abbey Mills Pumping Station is the largest establishment
of the kind on the Main Drainage Works, and provides, by means
of eight engines, an aggregate horse-power of 1140, capable of lift-
ing 15,000 cubic feet of sewage and rainfall a height of 36 feet per
minute. Each of the eight engines is furnished with two boilers;
and they are contained in a cruciform building, arranged in pairs,
each arm of the cross containing two engines. The engines, as
in all the other pumping establishments on these works, are expan-
sive, condensing, rotative beam engines, but are somewhat more
powerful than those used elsewhere, the cylinders being 4 feet
6 inches in diameter, with a stroke of 9 feet. The pumps differ also
in being double-acting, a` circumstance which admits of the air
STATIONARY ENGINES.
227
pump, &c., being worked from the main beam, instead of from a

Fig 145.-Abbey Mills Pumping Engines. One-half Elevation.
敢
​228
MODERN STEAM PRACTICE.
}
distinct beam, as at the other stations. Each engine works two
pumps, having a diameter of 3 feet 10½ inches, and a length of
stroke of 42 feet. The boilers are each 8 feet in diameter and
30 feet long, with double furnaces.
The engine building is divided in height into three compartments,
the lower one being the pump well into which the sewage is con-
veyed from the Low Level Sewer, the second forming a reservoir
for condensing water, and the upper one containing the eight engines
and platform overhead. The lower part of this building lies about
3 feet above the bottom of a thick stratum of clay, overlying a consid-
erable thickness of sand with water, through which the foundations
are carried by piling to a bed of firm gravel below. The boiler houses
and other portions of the work are founded upon the clay stratum
overlying the sand. As the deep foundations are situated in close
proximity to the Northern Outfall Sewer, which is contained in an
embankment above the general level of the ground, great caution was
requisite to prevent any settlement in that sewer. The boiler house
and coal stores are built between the outfall sewer and the engine
house, so as to keep the deep excavations as far distant from the
sewer as practicable. The coal stores are built with their floors level
with the stoke holes in the boiler house, and tramways are laid from
one to the other; this floor is only a trifle below the surface of the
ground, which is 6 feet below high water. One side of the coal
stores forms the front side of the boiler house. Tramways are laid
from the top of the coal stores to the Abbey Mill River, adjacent
to the works, where a wharf wall is built for landing coal and other
materials.
The sewage from the Low Level Sewer, before entering the pump
wells, passes through open iron cages, the bars of which intercept
any substances likely to interfere with the proper action of the
pump valves; and these cages when requisite are lifted above ground
by proper gearing, and the intercepted matter is discharged into
trucks. The sewage then passes into the wells, and is lifted by the
pumps through the hanging valves into a circular culvert of cast
iron, and then forced into any of the three culverts forming the
Northern Outfall Sewers.
It is fortunate that these works were not projected in the year
1306, when coal was first introduced into London, and was regarded
as so great a nuisance that the resident nobility obtained a royal
proclamation prohibiting its use under severe penalties; for this
STATIONARY ENGINES.
229
pumping station alone consumes about 9700 tons of coal per annum.
The expense of pumping, however, cannot be regarded as a wholly
additional item in the cost of drainage under the new system; for
the removal of deposit from the tide-locked and stagnant sewers in
London formerly cost about £30,000 per annum, and the constant
flow kept up in the sewers by means of pumping must necessarily
keep them freer of deposit, and so reduce the outlay for cleaning
them.
The Deptford Pumping Station is situated by the side of Dept-
ford Creek, and close to the Greenwich Railway Station. The
sewage is here lifted from the Low Level Sewer, a height of 18 feet,
into the Outfall Sewer. An iron wharf wall and barge bed, 500 feet
long, has been constructed at the side of the creek, and is provided
with a crane and tramways for landing coal or other materials.
There are four expansive, condensing, rotative beam engines, each
125 horse-power, and capable together of lifting 10,000 cubic feet
of sewage a height of 18 feet per minute. These engines are sup-
plied by ten Cornish single-flued boilers, each 30 feet long and
6 feet in diameter. The cylinders are 48 inches in diameter, with
a length of stroke of 9 feet. The pumps, two of which are worked
by an engine direct from the beam, are single-acting plunger pumps,
the diameter of the plungers being 7 feet, and the length of stroke
42 feet: one pump is worked from the beam midway between the
steam cylinder and the centre pillars, and the other midway between
the centre pillars and the fly wheel. The air, feed, and cold-water
pumps are worked by a separate beam attached to the cylinder end
of the main beam. The pump valves are of the leather-faced hanging
kind, and the sewage is discharged through them into a wrought-
iron culvert placed on the level of the Outfall Sewer, with which it
is connected by a brick culvert, which receives also the sewage from
the High Level Sewer, previously brought by gravitation under the
creek through four cast-iron pipes 3 feet 6 inches in diameter.
Both streams enter the Outfall Sewer, and are conveyed to Cross-
ness, where they are again lifted. The chimney shaft at this station
is 7½ feet in diameter at the base and 6 feet at the top; its height
is 150 feet, and the furnaces draw from the sewers and the engine-
well to assist in their ventilation. The accommodation for coal is
ample, the sheds covering an area of 18,000 feet. Gratings are
used for intercepting the larger substances brought down by the
sewers, in the same manner as at the other pumping stations.
230
MODERN STEAM PRACTICE.
The Crossness Reservoir and Pumping Station.-The sewage on
the south side of the Thames is discharged into the river at the
time of high water only; but the sewer is at such a level that it can
discharge its full volume by gravitation about the time of low water.
Its outlet is ordinarily closed by a pen stock placed across its
mouth, and its contents are raised by pumping into the reservoir,
which is built at the same level as that on the north side, and, like
it, retains the sewage, except during the two hours of discharge
after high water. The sewage is thus diverted from its direct course
to the river into a side channel leading to the pump well, which
forms the lower part of the engine building; from this well it is
lifted by four condensing rotative beam engines, each 125 horse-
power, working direct from the beam two compound pumps, each
with four plungers. The cylinders are 4 feet in diameter, with a
length of stroke of 9 feet; they are situate at the end of the main
beam, which is 40 feet in length, the crank shaft connecting rod being
attached to the farther end, and the pump rods situated on either
side of the beam centre. The air, feed, and cold-water pumps are
worked by a separate or counter beam, fixed at one end to a rock-
ing lever, and attached at the other end to the main beam. The
cylinders are supplied by twelve Cornish boilers, each 6 feet in
diameter and 30 feet long, with an internal furnace and flue 3 feet
in diameter, set so as to have the second heat carried with a split
draught along the sides, and the third heat under the bottom of the
boiler, into the main flue leading to the chimney. The maximum
quantity of sewage ordinarily requiring to be lifted by these engines
is about 10,000 cubic feet per minute; but during the night that
quantity will be considerably reduced, and, on the other hand, it
will be nearly doubled on occasions of heavy rainfall. The lift also
will vary from 10 to 30 feet, according to the level of water in the
sewer and in the reservoir into which it is lifted. These variable
conditions led to some difficulty in the working, but which has been
overcome by an arrangement of the pump plungers. The pumps,
which are single-acting, are placed equidistant on each side of the
beam centre, their cases being each 12 feet in diameter, and fitted
with four plungers 4 feet 6 inches in diameter. These plungers are
placed in pairs, each pair being worked from a crosshead on the
main beam, which is in two flitches for this purpose, and either
pair of plungers can be thrown out of gear. By this means the
capacity of the pumps may be varied in the proportion of one, two,
STATIONARY ENGINES.
231
or three, as the inner pair, outer pair, or both pairs are thrown out
of gear. The sewage is discharged into a wrought-iron trough,

00
00
DO
JU
Fig. 146.-Pumping Engines at Crossness. One-half Side Elevation.
through hinged leather-faced valves, which are suspended from
wrought-iron shackles, and fitted with wrought-iron back and front
plates. Each valve is 12 inches by 18. As has been before stated,
substances which might prevent the proper action of the valves are
232
MODERN STEAM PRACTICE.

636
DONGJEJUT
LESION
JHLET
MOODOW
Fig. 147.-Pumping Engines at Crossness. End Elevation.
intercepted before reaching the pumps by a wrought-iron grating
STATIONARY ENGINES.
233
placed in front of the openings to the pump well. Such substances
are lifted from the face of the grating by an endless chain with
buckets or scrapers and combs attached, working vertically in front
of and close to the grating, the teeth of the combs passing between
the bars. On the descent of the chain the buckets are overturned
and discharge their contents into a trough, from which they are
removed by manual labour.
The sewage, after being delivered from the pumps into the
wrought-iron trough, is discharged through brick culverts into the
reservoir, or, in case of need, provision is made for its discharge
through other culverts directly into the river. After remaining in
the reservoir until the time of high water, it is discharged by a lower

Fig. 148.-Boilers for Pumping Engines at Crossness. End Elevation.
set of culverts into the river. There are two tiers of eight openings
in each compartment of the reservoir, the upper eight for the admis-
234
MODERN STEAM PRACTICE.
1
sion of the sewage from the pumps to the reservoir, and the lower
eight for its discharge into the river. These apertures are all opened
and closed by pen stocks.
The reservoir, which is 62 acres in extent, is covered by brick
arches, supported on brick piers, and is furnished with weirs for
overflows, and with a flushing culvert. The height, level, and
general construction are similar to the one at Barking Creek. Over
the reservoir are built twenty-one cottages, for the engineers and
other persons employed upon the works.
The ground upon which these works are constructed consists of
peat, sand, or soft silty clay, and affords an insufficient foundation
within 25 feet of the surface. To obviate the need of removing this
vast mass of soil, and thereby reduce the expense of the foundations,
trenches were cut down to the solid earth, and the culverts on the
various levels were built as far as practicable in the same trenches,
one above the other; the lowest, leading from the Outfall Sewer to
the pump wells, support those discharging the sewage from the
reservoir, and these again support those leading from the pumps
into the reservoir. On account of the pump wells it was necessary
that the walls of the engine house should be carried down to the
depth of the gravel, independently of the nature of the ground; but
such was not the case with the boiler house. The boilers and stoke-
hole floor are supported on arches springing from walls built up
from the gravel, and the space below the floor is made available as
a reservoir for condensed water. The water from the hot and cold
wells of the engines is conveyed hither, one compartment being
used as a chamber for cooling that from the hot well, previous to
its being used again for condensing water. With the same object
of saving separate foundations, coal stores and workshops have been
erected partly on the external walls of the reservoir and partly on
the culverts in front of them; large coal stores being also provided
in front of the boiler house and on a level with the stoke holes, into
which the coals are brought on tramways. There is also a tramway
for the upper-level coal sheds, on the level of the tops of the boilers,
from whence the coals are shot into the stoke holes below. Tram-
ways are also laid from the coal sheds to the river, where jetties are
built for landing the coals. A wall has been constructed along the
river frontage of the works for a distance of about 1200 feet, by
which a large portion of the "Saltings" has been reclaimed. · This
wall is of brick, carried upon brick arches resting on piers formed
י
STATIONARY ENGINES.
235
of iron caissons filled with concrete, which are carried down to the
gravel.
The chimney into which the flues from the boilers are conveyed
is square in plan externally, 8 feet 3 inches in internal diameter
throughout, and 200 feet high; it is founded upon a wide bed of
concrete brought up from the gravel, which is here 26 feet below
the surface. The reservoir, the several culverts, and the pump wells
are connected by flues with the furnaces of the boilers, for the pur-
pose of ventilation, in the same way as at the Deptford and other
pumping stations.
The outlet into the river from the Outfall Sewer of these works
consists of twelve iron pipes, each 4 feet 4 inches in diameter, car-
ried under the "Saltings" into a paved channel formed in the bed
of the river. These pipes are connected with the Outfall Sewer by
culverts in brickwork on the land side of the wall, the numbers of
these culverts being gradually reduced and their dimensions in-
creased as they approach the junction with the large sewer.
HIGH-PRESSURE GEARED PUMPING ENGINES.
Small high-pressure geared engines may be conveniently used for
pumping water out of docks, and for other drainage purposes, being
arranged for three pumps. The connecting rod runs from the cross-
head of the piston rod, and works a cranked shaft, having a fly wheel
at one side and pinion at the other, geared into a spur wheel keyed
on a cranked shaft for the middle pump; one of the side pumps
is worked from a pin let into one of the arms of the spur wheel, and
the other pump is driven from a crank placed on the other end of
the shaft. The engine is placed horizontally, and the pumps are
vertically arranged against the side of the dock wall. When they
are needed to pump the water out of a dock in course of construc-
tion, the engine is bedded on an overhanging wooden frame, having
a strut let into the wall, or temporary pile foundation, on each side.
of the frame for carrying the engine and the three throw cranks for
the pumps. The pumps are in some instances of the plunger type,
having the plungers cast in brass; while others are simply lift pumps,
fitted with valves of india rubber working on brass gratings. There
is one suction pipe and one discharge pipe common to all the three
pumps; the former has a three-branched pipe fitted to the top, to
which are bolted the pumps, one to each branch; while the latter is
236
MODERN STEAM PRACTICE.
placed across the pumps, in communication with the valve chests,
having one vertical delivery pipe placed at the end.
THE CENTRIFUGAL PUMP.
Centrifugal pumps have been much used for pumping water out
of works in course of construction, and are recommended for their
simplicity and the ease with which they can be applied to almost
any situation. The pump, when placed in position, is driven by a
belt from the fly wheel of a portable engine. This is a temporary
arrangement; but many centrifugal pumps have been fitted up of
a permanent kind, driven by wheel gearing. When the lift is of
moderate height these pumps throw a vast body of water; and as
they are not so liable to get choked with foreign matter, they may
be used in many situations for pumping sewage with advantage.
Fig. 149 represents a pair of centrifugal pumps of the largest size
for drainage purposes connected directly to the engines, a class of
machinery brought to great perfection by the Messrs. Gwynne & Co.
of London. This description of pump is admirably adapted for
works of construction, water works, graving docks, &c., and more
especially for drainage purposes, large tracts of land having been
reclaimed by its aid. Where low lifts only are required it far eclipses
the ponderous pumping engine of the beam type.
The construction of this pump is very simple. The revolving
wheel or disc is formed of two concave plates, placed parallel with
their concave surfaces towards each other. Two saucers, placed
in corresponding positions, will give an idea of the arrangement.
Between these discs is an arm or impeller, radiating from a boss or
hollow axis, mounted on a shaft which works horizontally, vertically,
or at any intermediate angle. This impeller, which regulates the
distance between the discs, varies in breadth; its narrowest part is
at the outer edge of the discs, becoming gradually broader until
its edge intersects the inner surface of the openings for the suc-
tion. Its breadth is varied in such a ratio that the areas of any
section cut from the wheel by the surfaces of circular cylinders,
whose axes coincide with that of the shaft, shall be equal to such
other section at any distance from the centre; and these areas are
so arranged in order that the column of water or other fluid enter-
ing the wheel when in a state of revolution may have an uninter-
rupted flow from the centre to the circumference, and that the
STATIONARY ENGINES.
237
quantity received and discharged may be constantly equal. This
is considered to be essential when large bodies of water are to be
discharged, or when high velocities are required. The inner surfaces
of the discs, or the annular opening around the whole circumference,

Fig. 149.-Arrangement of Centrifugal Pumping Machinery-Gwynne & Co.
has an area equal to the openings at which the water is admitted
into the centre of the revolving wheel. There are two cylinders.
or water passages, one on each side, with a passage for each in
connection with one suction pipe, rendering the pump extremely
238
MODERN STEAM PRACTICE.
compact. In one of the cylinder covers or ends there is a bear-
ing supporting the spindle on which the wheel is fixed, in the
other cylinder cover there are a gland and stuffing box through
which the shaft for the revolving wheel passes. The suction pipe
may, if desired, be run any moderate length horizontally, and the
pump may be placed from 15 to 20 feet vertically above the water
to be raised; in most cases it is advisable to have a foot-valve at
the bottom of the suction pipe, so as to retain the water in the
pump when standing still. The delivery pipes, as seen in Fig. 149,
are fitted with self-acting flap valves, to prevent any water flowing
back on to the land when the pump is not working. The pumps are
fitted to discharge 30,000 gallons per minute, 12 feet high; the pipes
are 42 inches in diameter; the engines are of the horizontal condens-
ing type; diameter of cylinders 21 inches, length of stroke 21 inches.
The action of the pump is as follows:-The pump and pipes
being filled with water, which the foot valve at the bottom of the
suction pipe retains, the wheels or discs are coupled to the engine,
and the latter being started at a high velocity, a centrifugal motion
is given to the wheel, and to the water contained in the disc, which
is driven out into the case or receiver of the pump. The partial
vacuum thus formed in the disc is filled by the water forced up the
suction pipe by the pressure of the atmosphere; the water entering
the disc receives centrifugal motion in the same way, and thus a
continuous stream is received into and discharged from the pump.
To prevent the water from rotating in the case, and to give it a
direction upwards to the discharge pipe, a stop or plate is placed at
the base of that pipe, reaching to the joint between the piston and
the case. The joints between the suction pipes and disc are so made
that sand, mud, or gritty matter cannot lodge near them, by which
means the wear is so reduced as to become almost imperceptible.
The following may be enumerated as the principal advantages
of the centrifugal pump:-(1.) It can be erected easily and quickly.
(2.) It works with an easy rotary motion, without valves, eccentrics,
or other contrivances, which consume power in friction. (3.) It will
discharge a quantity of water greater in proportion to the power
employed than any other pump-75 per cent. being taken as an
average. (4.) It is economical in use, and of very great durability
an important point in all machinery. (5.) It discharges a con-
tinuous and steady stream without air vessels. (6.) It is little
affected by sand, mud, grit, or other foreign matter in the water,
STATIONARY ENGINES.
239
which so rapidly destroy all other pumps. (7.) The large sizes will
admit the passage of solid bodies 6 inches in diameter without
injury, and the smaller sizes in proportion. (8.) It will pump hot
or cold liquids equally well. (9.) It requires a very light and inex-
pensive foundation, as there is no vibration while working.
·
A striking proof of the great superiority of these noiseless machines,
working at a high speed, over the beam pumping engine, may be
seen in the draining of the Haarlem Lake. The weight of the
pumps and valves attached to one of these latter engines was about
200 tons, the pumps were adapted to raise about 70 tons of water
per minute a height of 15 feet when working their usual speed of
eight or ten strokes; but a centrifugal pump of the above descrip-
tion, doing the same amount of work, will weigh only 5 tons.
The Pulsometer Pump has been recently introduced with good
results in many situations where other forms of pump would have
been more troublesome to keep in order. It is a steam pump with-
out moving parts except certain valves. The operation consists in
forcing water to a height by the direct pressure of the steam, and
the lifting of the supply into the pump by the after condensation of
the same steam; this is accomplished through the medium of a ball
valve above and clack valves below, arranged in two vertical
chambers.
WINDING ENGINES.
In modern practice the use of the flat hempen ropes with these
engines has been discarded, in favour of the wire rope of a round
form. The drums and pulleys for these ropes must be of large
diameter, and the angle of the rope from the drum to the pulley on
the pit-head frame should not be too acute. Where the weight
lifted is about 1 ton, the thickness of rope will be about 1 inch,
and will weigh about 4½ lbs. to the foot, the diameters of drum being
about 5 feet and 16 feet, and the time taken to lift through from
250 to 300 fathoms about 1 minute.
The engines used at collieries for winding purposes should be of
the simplest construction, strong, and free from all unnecessary
and expensive complications. With this view spur gearing has
been discarded by many first-class manufacturers, although geared
engines are still in extensive use: the object of using a pinion on the
engine shaft working into a spur wheel on the drum shaft being to
1
240
MODERN STEAM PRACTICE.
reduce the diameter of the cylinder and length of stroke of the
piston, and so to drive the engine shaft at a greater number of
revolutions than the drum shaft. The old type of engine most in
favour is of the beam description, vibrating on a gudgeon on pillow
blocks supported by a single column, having plain cast-iron guides,
with crosshead and link attachment connecting the piston rod with
one end of the beam; this being the simplest arrangement for giving
a true vertical motion to the piston rod. The other end of the beam
is connected to the crank shaft by a cast-iron connecting rod, of
sufficient weight to balance the piston and its adjuncts. These
rods are fitted with wrought-iron straps and brass bushes, with jibs.
and keys for adjusting the brasses. The bed plate for carrying the
cylinder, main column, and pillow block for the crank shaft is cast
in one piece. When the bed plate is securely bolted down on an even
surface, with a firm foundation, this form of engine is very strong and
durable, and is generally constructed on the high-pressure principle.
Horizontal geared engines, however, have in a great measure
superseded those of the vibrating beam type. They are certainly very
compact, and when properly proportioned give great satisfaction,
notwithstanding the objections arising from their wheel gearing.
The DIRECT-ACTING HORIZONTAL ENGINE, with the drum for
the wire rope placed on the crank shaft, may be regarded as the type
of engine to be used for the future. Simplicity is the object to be
attained, and we attain it in the direct motion of this engine simply
by giving a little more diameter of cylinder and a longer piston
stroke, with a certain number of revolutions to suit the diameter
of the drum and the speed usually allowed for running the wire
ropes. Although single engines are in daily use, they are better to
be used in duplicate, with one crank shaft, and cranks at right
angles to each other. With the latter form there is no difficulty
in starting, as is sometimes the case with single-cranked engines,
which have a tendency to stop on the dead centre, or extreme end
of the stroke, and require great attention on the part of the attend-
ant to prevent this occurring. This objection is entirely removed
by coupling the engines at right angles, the one assisting the other
in the extreme position. The perfect ease and certainty with which
these engines can be handled by means of the beautiful link motion
and double eccentrics-combined with the powerful brake on the
periphery of the fly wheel-renders the direct-acting horizontal
engine a great boon to the practical miner.
میں
STATIONARY ENGINES.
241
The cylinder for these engines is a plain casting, with steam and
exhaust ports suited for the ordinary slide valve: one steam port
at each end, and a central port for the exhaust. It is preferable to
fit a cover at each end, more especially for large diameters, as the
boring bar requires to be of a large size to bore out truly these long


BICE
HOE
00
srij
Fig. 150.-Colliery Winding Engines. Side Elevation and Ground Plan.
cylinders free from vibration, and the hole for the bottom bush in
the stuffing box on a solid end is too small in diameter for an
ordinary sized boring bar. There is a deep stuffing box on each
cover, fitted with a gland in the usual manner. The piston rod
passes through both these boxes, an arrangement which takes part
16
242
MODERN STEAM PRACTICE.
of the weight off the piston on the end glands, the piston rod acting
as a round beam loaded at the middle when the piston is at half
stroke; by this means the action of the piston has not so much
tendency to wear the cylinder oval. Trunks or hollow pipes have
been introduced in some classes of blowing engines to remedy this
evil, inherent in all horizontal engines of very large size; and when
properly proportioned they have given good results. The cylinder
is cast with brackets on the bottom half for bolting it down on the
bed plates; of course these palms or brackets should be nearly in a
line with the strain, or a little below the centre line of the cylinder.
Joggles are cast on the bed plate to embrace the brackets, and by
this means end keys are fitted and driven in tightly, thus taking
the shearing strain off the bolts. By attention to these details secure
and firm work is obtained, more especially for high-pressure engines,
where the succession of shocks from the high steam pressure used
has a great tendency to shake the cylinder and loosen the fittings
if not properly joggled to the bed plate. Indeed, for fast-going
engines of the high-pressure type, the repeated shocks received on
the end of the cylinder necessitates the use of wrought-iron stays
to bind the cylinder and bed plate firmly together; some makers
even casting the cylinder along with the bed plate, which effectually
secures this object.
The steam valve is an ordinary D one, and should be fitted with
packing rings on the back, bearing on the valve-casing cover. Some
makers, however, prefer a small piston working in a short cylinder
placed on the valve-casing cover, the piston being connected to the
valve by means of a vibrating link. Some such contrivance is
absolutely necessary to take the back pressure off the valve; and
the former method does so by reducing the area on the back of
the valve—that is to say, the rings are made steam tight, and the
surface exposed to the steam in the casing is reduced; while by the
latter method the valve is drawn, as it were, off the face with a
certain force applied by means of the piston, and which being
received on the pins of the vibrating link, renders it comparatively
easy to move the valves by hand, just as any heavy weight is easily
moved when suspended by a chain. The valve casing is sometimes
cast on the cylinder; but many prefer it to be separate, and secured
with bolts, as in this case the facing for the valve is more readily
planed, and afterwards scraped to a true surface. The usual
stuffing box is cast along with the casing, with brass bush and
STATIONARY ENGINES.
243
gland, and it should have a brass guiding socket at the other end
for taking the valve spindle, which passes through a tube cast along
with the valve, and to which it is secured by means of a nut and
jam nut at each end. Some makers dispense with this guide, and
attach the rod to the valve by a screwed part at its end, having a
nut let into the valve, with a jam nut to lock it securely when the
valve is properly set.
The valve is actuated by double eccentrics and link motion.
The eccentric sheaves are of cast iron, of the usual construction,
and may be cast all in one piece, or have the means of taking them
off the shaft without disturbing the main parts of the engine. The
straps should be cast in brass, or they may be forged on the eccen-
tric rods, and lined with strips of brass rivetted on. The link,
suspension rods, weigh shaft, and reversing handle should be made
of wrought iron, and all the working pins case-hardened; and the
sliding block for the link should be of steel. All the bearings for
the weigh shaft should be bushed with brass, and the whole motion
adjusted in a strong and substantial manner.
The starting handle should be a plain lever, fitted with quadrant
and catch for holding the link in position. The starting platform
should be placed so as to command a good view of the pit head.
Its position depends, of course, on the method of fitting up the
machinery, but in ordinary cases the platform may be arranged at
the back of the winding drum, and of sufficient height to see well
over it. In this position, when the fly wheel is placed at the centre
of the engine shaft, the friction strap and hand gear for working it
is greatly simplified, and the attendant has the two important handles
for reversing and applying the friction brake in a direct line with
the pit head. The handle for working the stop valve of the equili-
brium type should be placed here likewise, on the centre of the
steam pipe between the two engines. The handles are, however,
at times arranged on the outside of the left-hand engine looking
towards the pit head, with a cross shaft, as in the former method,
for the reversing gear placed underneath the bed plates or above
them, supported at the end and middle with suitable pillow blocks.
On this shaft the lifting arms are fitted, with a weight arm at the
centre of the shaft, or between the end and middle pillow block,
having a suitable weight, which may be placed on the starting
handle, for balancing the links and rods, and thus easing the labour
of starting and reversing the engines. The handle will of course
244
MODERN STEAM PRACTICE.
suit almost all attendants when arranged for the right hand. The
lever for the brake is worked by foot; it should be of great length,
and so placed that the attendant can press it with his left foot
whilst he holds the reversing handle. The brake lever must, of
course, be arranged horizontally, and fitted with a cross shaft and
short lever at the end for taking the brake strap of wrought iron
lined with blocks of wood. The shaft is supported on three pillow
blocks, and is fitted with a weighted lever, the weight being suffi-
cient to balance the long foot lever, which should have a suitable
stop to keep it always at a convenient height for treading upon.
Many engineers are of opinion that it would be better to fit a hand
lever and rod to the long brake arm, instead of pressing on it with
the foot; but it must be borne in mind that both hands may be
required at times to lift or depress the link motion, and the foot
can be applied to the brake when the engine requires to be sud-
denly stopped. In other examples the long brake handle is placed
above the floor of the engine room, the engineman moving it by
hand, and the handle is kept up by a catch cast on a suitable cast-
iron column: there is another catch placed on a nut worked by a
screwed rod and wheel, supported by the column. The nut can be
adjusted at pleasure to suit the wear of the wooden friction blocks.
When the handle is depressed and sprung under the catch the
blocks are pressed against the friction wheel, and when the friction.
requires to be increased the wheel on the screw rod is turned by
hand, which firmly locks the friction blocks.
The piston for all horizontal engines should be of the strongest
and lightest construction possible, fitted with a single packing ring,
and the usual junk ring. The packing ring may have steel springs
between it and the body of the piston; but some makers prefer a
plaited gasket. The junk ring is bolted to the piston with screwed
bolts and nuts recessed in the body of the piston. Another form
of piston largely used for high-pressure engines is a plain casting,
turned on the rubbing surface, and recessed for light steel springs.
This is certainly the simplest form of metallic packed piston; and
when it is supported by means of the piston rod passing through
stuffing boxes at each end of the cylinder, it works admirably even
for large diameters. The method of connecting the piston to the
rod is by forming a coned part at the middle of the rod with a
corresponding cone turned in the piston, which is secured by a
cotter passing through the body of the piston, as in the ordinary
STATIONARY ENGINES.
245
packing-ring system; but when the piston is cast solid, and indeed
for all pistons, it is preferable to cut a screw on the rod at the
small end of the cone, which is fitted with a nut for pressing the
piston firmly on the cone; and to prevent the piston turning round
in the cylinder, as it may do in course of time, a small short key is
let into the rod, having a corresponding part cut in the piston for
its reception.
The crosshead and gudgeon for the connecting rod is of wrought
iron, suited for single or forked ends as may be desired; the hole in
the crosshead for the piston rod is bored out slightly tapered, the
rod being turned to suit, and secured with a cotter passing through
them both. Holes should be drilled at the small end of the cotter
for passing a split pin through, to keep it from shaking loose. The
holes for the gudgeon in the jaws of the crosshead are bored quite
parallel, and the gudgeon, being accurately turned, is driven through
tightly, and secured with a key. The gudgeon can be of a less
diameter at the ends for taking the guide blocks, and of sufficient
length at one end for fitting the eye of the feed-pump plunger to it.
The motion bars for guiding the crosshead in a direct line with
the piston rod are of cast iron. The bottom bars are generally cast
along with the bed plate, but they sometimes form separate castings,
which require to be fitted to the bed plate; while the top bars are
generally made—so that the gear can be adjusted—with thin strips
of metal between them and the bottom bars, which can be reduced
in thickness as the guide blocks wear. In this arrangement the top
bars are secured to the bottom ones with bolts at the ends, the same
bolts securing the bottom bars to the bed plate; but in some cases
the bottom and top motion bars are cast in one piece, and fitted
and bolted down on the bed plate. These guiding bars must be
accurately planed, and also the guide blocks, which are cast in hard
brass. Sometimes cast-iron blocks are adopted, in which case the
rubbing surfaces are filled in with white metal, recesses being
left in the casting for that purpose; plain cast-iron blocks, however,
answer very well, when lubrication is properly attended to-that
being a most important point in all rubbing surfaces. Oil cups
should be cast on the top motion bars, and fitted with proper covers
to exclude grit, with siphon pipe and wick to supply the oil drop
by drop.
The connecting rod is of wrought iron, turned from end to end,
with oblong pieces at the ends accurately planed, and fitted with
246
MODERN STEAM PRACTICE.
wrought-iron straps and jibs and keys for adjusting the brass
bushes; suitable lubricating cups are fitted to the straps.
The main cranks are of cast iron, but most engineers would
prefer them of wrought iron, as they are much stronger and better
adapted for engines subjected to severe shocks. They are usually
bored out and shrunk on the shafts hot; but when they are forced
on cold with an hydraulic ram the material is not so much strained,
while the holding power is equally good. The cranks are further
secured with a single key, fitting into a recess planed in the shaft
and slotted out in the crank eye. The crank pin is slightly tapered
in that part fitting into the hole in the crank, and is forced on and
then rivetted at the end, a part being turned out for this purpose;
this makes very secure work. In some recent examples the cranks
are formed of discs of cast iron, with a side flange on the circum-
ference of the disc, strongly ribbed to the boss at the centre. This
plan balances the engine better than the single crank arm. The
crank pin is secured by means of a nut and feather or key on the
pin.
The main pillow blocks are separate castings, fitted with brasses,
and caps arranged at an angle, so that the brasses are adjusted in
the direction of the greatest strain. The bottom of the blocks are
planed, as also the fitting strips on the bed plate, which has extra
strong joggles cast on it for driving in wedges, thus taking the
shearing stress off the pillow block holding-down bolts.
The bed plate is a strong frame of a box section, open at the
bottom; it is tied at the ends and at the middle in the casting, and
should be strengthened with cross feathers between the sides, having
all the necessary joggles and fitting strips for the cylinder, pillow
block, pumps, and other minor fittings. There should be at least
four large holding-down bolts on each side of the frame, passing down.
through holes left in the foundation, and secured on the under side
with a plate and key for each bolt. The foundations should con-
tain suitable man-holes, so that these bolts can be adjusted at any
time. In some instances the plates at the bottom of the foundation
are carried across, embracing two bolts; by this means a foundation
of brickwork laid in cement is firmly bound from top to bottom.
When brick is used for the foundation it is preferable that a layer
of stone-work or balks of wood be placed on the top, for the main
bed plate to rest on.
The main shaft of the engine should be of wrought iron, and all
STATIONARY ENGINES.
247
the bearings and raised parts for the drum, fly wheel if so fitted,
eccentrics, and other minor details, should be accurately turned;
while all the eyes of the various fittings should be bored out to
the exact size, and held by means of keys bearing on a flat part of the
shaft, keyways being cut in the parts. This is by far the cheapest
and best mode of hanging the drum and centre pieces, fly wheel,
&c.; the old mode of hanging these fittings with a number of keys
in each is not to be commended, and has now become obsolete.
The feed pump is of the plunger type, and is bolted down on
the top of the bed plate at the end nearest the main crank shaft.
It is desirable that the plunger should be of brass or Muntz metal,
connected by means of a wrought-iron rod to the end of the gudgeon
for the crosshead-an eye is forged on this rod, and accurately
bored out to take the end of the gudgeon, and held in position with
a set screw. When the pump is placed well back, the plunger is
better balanced at the extreme IN stroke, as there is a considerable
distance from the pump gland to the centre of the crosshead while
in that position; and the plunger by this arrangement is not so
liable to droop, as it would do were the crosshead working quite
close up to the pump gland. The suction and delivery valves and
seatings are of brass, fitted into cast-iron valve chests; an escape
valve should also be fitted, loaded with a certain weight, so that
when the attendant shuts the feed valve on the boiler, the water is
forced past the escape valve, and finds its way by a pipe connection
into the pond or cistern from which the supply is drawn. An air
chamber should be fitted to some convenient part of the feed pipe,
as by this means the flow is more uniform, and tends to lessen the
vibration in the pipes when the engine is working at full speed.
As these pipes are sometimes subjected to the influence of hard
frost, the engine rarely going all night, they should be properly
clothed and protected with a non-conducting material; and a small
plug tap should be fitted, so that all the water may be run off
between the pump and feed valve placed on the boiler: these pre-
cautions taken, there is no fear of breakage occurring, as has too
often been the case otherwise; for when an engine is started in the
morning with the water in the feed pipe frozen a fracture must
take place. In many arrangements the feed pump is dispensed
with, the boilers being fed with a separate steam pump. The steam
pipes must also be protected with felt and canvas sewn over, to
prevent condensation. The exhaust pipe (when the waste stearn
248
MODERN STEAM PRACTICE,
is blown up the chimney) should be trapped at the end, by leading
it into a cast-iron cistern, fitted with a separate pipe into the
chimney, having a bend at the end for directing the waste steam
vertically; by this means much of the moisture is got rid of, being
retained in the cistern and run off by a suitable overflow pipe. In
this way the chimney is kept comparatively dry, and consequently
less liable to the deterioration caused by a blast of steam and water
blown into it. Some engineers prefer blowing off the waste steam
directly from the cylinder by a vertical pipe passing through
the roof of the engine house. By such an arrangement there is, of
course, no steam blast to injure the chimney; but, on the other
hand, we lose its valuable aid in urging the fires, by causing a
partial vacuum in the chimney, which tends to supply through or
between the fire bars the necessary quantity of oxygen to effect
complete combustion.
The drums for the round wire ropes must be of large diameter.
They are of two kinds, conical and parallel; with the conical the
strain on the engines is better regulated. The lift is taken on the
smallest diameter, and the rope unwinds for the empty cage from
the largest diameter; consequently the latter balances in a measure
the ascending cage fully loaded, which is lifted slowly, throwing
less strain on the machinery. The drums are constructed of light
cast-iron wheels, each with eight strong arms, and arranged for
bolting together in two halves; a side flange is cast on to receive the
wooden battens, to which they are securely bolted. For the conical
drums there are two wheels of the same diameter, one at each end,
with flanges bevelled according to the hollow given to the cone,
and a smaller wheel is placed between them, having a flat rim; the
wood is laid quite flat on the inside, and for the outer diameter it is
cut to the cone required. The wire ropes are put on one above
and another below the drum, and are wound from its longitudinal
centre, the cone increasing to the ends at each side. The side and
middle sheaves are keyed on the shaft similarly to an ordinary
fly wheel, and should be fitted with wrought-iron rings, shrunk on
the outer circumference of the bosses. It is preferable to fit a fly
wheel close up to the main bearing; it should be of sufficient weight
for the engine, and made of extra strength in the arms, as the
brake is generally applied on the periphery.
The most approved form of brake consists of wooden blocks
fastened to wrought-iron hinge pieces, vibrating on pins and joints,
STATIONARY ENGINES.
249
secured to the floor in the fly-wheel pit. There are two fitted
under the wheel at each end. On the vibrating centre or fulcrum
of the long brake lever, a shaft carried on suitable bearings has a
double-ended short lever keyed on it, fitted with eyes and pins;
from these joints two side rods pass along, one on each side of the
fly wheel, and are secured to eyes on the wrought-iron pieces for
taking the friction blocks. Both brakes are so fitted, and with a
movement of the long lever the off-brake is drawn against the
periphery of the fly wheel, while the near one, fitted with short rods,
transmits a compressive strain, which of course the short connecting
links are better calculated for. With parallel winding drums the
arrangement is somewhat different. The drums have two side
sheaves for each; the two centre ones are placed sufficiently wide
apart to take a strong ring which is fitted to the skeleton sheaves,
this serving as a brake wheel, which in this arrangement is acted
on by a strap lined with wood placed underneath it, fitted with
suitable levers and shafts. Some authorities consider that this
brake wheel is not so well placed as in the former example, for the
strain acting on the centre of the shaft between the two engines
tends to throw undue stress on the shaft. But we must not lose
sight of the fact that when a separate fly wheel is used, placed at
the side of the drum, the adjoining bearing has more duty to per-
form, and it may be concluded that with extra strength given to
the shaft, to resist the pressure of the brake, the intermediate brake
wheel can be used with advantage, equalizing the wear on the
bearings, which is an important consideration in coupled engines.
In some examples where steam pumps are fitted, instead of the
usual feed pumps, thus simplifying the engine considerably, the feed
water is heated in its transit to the boilers by passing through a
number of small tubes fixed in plates, inclosed in a cast-iron cylinder;
the exhaust steam enters this cylinder, surrounds the tubes, and
transmits its heat to the cold water passing through them. Some
engineers blow the exhaust steam into a receiver, and the cistern.
placed at the end of the exhaust pipe for collecting the condensed
water is a similar contrivance: the steam is blown over the surface
of the water, which becomes thoroughly heated. Of course the
steam that is not condensed is blown up the chimney in either of
those feed-water heaters. In the former plan there is no trouble
attending the operation, as the feed water is simply passed through
the small tubes in its transit from the feed pumps; but the latter
250
MODERN STEAM PRACTICE.
requires attention to keep the water in the cistern at the proper
level, and in many situations the water would require to be raised
by a separate pump, or the cistern placed low enough to admit of
the water running in from an adjoining pond.
We give a Plate of a Winding Engine of approved construction,
erected in 1881 for a pit belonging to the Benhar Coal Company,
at Niddrie near Edinburgh.
BLOWING ENGINES.
OVERHEAD-BEAM BLOWING ENGINE.
We will now consider that form of engine used for blowing air to
the furnaces for melting iron ores, technically termed the "blowing

Fig. 151.-Blowing Engine. Side Elevation.
engine." This engine delivers the air into a receiver, the pressure
varying from 2 to 4 lbs. per square inch, or a mean of say 34 lbs.,
that being the pressure on the large piston of the blowing cylinder.
STATIONARY ENGINES.
251
A variety of forms of blowing engines are now in use, viz. the
beam, the side-lever, the vertical, and the horizontal, which we will
notice in succession.
The high-pressure beam engine has been largely used for blowing
purposes. Its main beam is cast in two halves, held together by
distance pieces; the steam cylinder is placed at one end of the
beam, and the blowing cylinder at the other. The connecting rod
and crank shaft are placed between the steam cylinder and the
main centre of oscillation of the beam, and the cold water and
feed pumps between the blowing cylinder and the main centre of
oscillation.

The steam cylinder is a plain
casting, with oblong branches
at the top and bottom for the
steam ports, which are made
as short as possible. When
the stroke of the piston is long
it is desirable to have the
steam valves so arranged that
the cubical capacity of the
passages on the cylinder side
should be as small as practi-
cable, by which means much
steam is saved at each stroke,
as compared with some ar-
rangements where the pas-
sages extend from the top to
the bottom of the cylinder. A
A
B
F
B
D
о
Fig. 152.-Steam Cylinder and Cover.
E
square base is cast along with A, Cylinder. BB, Steam ports. c, Cone plug. D, Cover.
the cylinder, having a hole in
the centre for the boring bar to
E, Raised lip on flange for catching the oil.
F, Part cut out for the connecting rod.
pass through, which is afterwards filled up with a plug or cover. Part.
of the base is hollowed out on the opposite side from that of the
steam ports, to give the necessary clearance for the main connecting
rod. The body of the cylinder has suitable belts cast on, and also
a projecting moulding near the top for supporting the platform.
The cylinder is firmly bolted down at each corner of the base plate
with long bolts, passing down through holes left in the foundations,
and secured at the under end with plates and cotters; these beam
plates extend across the structure from hole to hole. A cast-iron
252
MODERN STEAM PRACTICE.
plate is laid down on the top of the foundation, having fitting
strips for correctly adjusting the vertical line of the cylinder, cor-
responding strips being left on its base for that purpose. This
makes a thoroughly good fixture, as these foundation plates spread
over a large surface of the stone or brick work, and the action of
the steam in the cylinder and motion of the working parts have
not so much tendency to abrade the stone and loosen the founda-
tions. The cylinder cover is generally an open casting, and should
be turned on the face; the surface is made steam tight by scraping
the faces on the cover and cylinder, and interposing a thin coating
of red lead at the joint. A brass bush is fitted at the bottom of
the stuffing box, and also in the cast-iron gland. The flange of
the stuffing box has a raised part round the edge, to prevent the
oil or other lubricant from flowing over and dirtying the cover.
The cover is turned all over the exterior, and should be finished
bright, as it is then much more easily kept clean. The bolts for
the gland should be cut with a square thread, and have square nuts,
as hexagonal nuts are not nearly so good for parts requiring such
frequent adjustment.
The piston is of the usual description, and made very heavy;

C
A
B
Fig. 153.-Piston for Steam Cylinder.
A, Coned part for the piston rod. B, Junk ring. c, Metallic packing ring.
indeed, some engineers cast the body solid, with a view to balance
the large blowing piston at the other end of the beam. The pack-
ing ring should be in one piece; some use two rings, but this is not
required, and is decidedly objectionable, from the fact that there are
then four faces to be kept steam tight, whereas with one ring there
are only two. The narrow junk ring is accurately turned on the
fitting strips and corresponding parts on the piston, and is made
steam tight by scraping the surfaces. The holding-down bolts are
screwed into nuts recessed into the body of the piston in the usual
manner. The piston rod is secured to the piston by means of a
coned part turned on the former, with a corresponding cone on the
latter, through which a cotter passes and tightly forces the piston
on the coned part of the rod. A better plan is to fit a nut on the
STATIONARY ENGINES.
253
top of the piston, having a screwed part on the piston rod, in which
case a recess needs to be left in the cylinder cover for the nut to
pass into, as the piston works closely up to the under side of the
cover and down to the bottom of the cylinder,
3/4 inch of clearance being quite sufficient be-
tween the piston and the end of the cylinder at
the top and bottom.
The valves are of the piston description,
fitted with metallic packing rings and junk
rings, similar to the main piston; and they
work in short cylinders placed in the nozzle
chest and bolted to the main cylinder. These
cylinders are cast with oblong ports, the bars
lying at an angle; by this means the rings
on the valves work more
evenly, and are not so

C
C
B
B
C
อ!!
Cylinder.
T
1
1
D, Cylinder for valve.
E, Slot holes.
B

liable to form ruts as they Fig. 154.-Piston Valve and
would be were the bars
A, Piston valve. B, Metallic
placed vertically. These packing rings. c, Valve rod.
valve cylinders are pro-
perly secured in the cas-
ing, which is bored out for their reception.
Each valve is connected with a rod passing
through the centre of the piston, and secured
with a collar on the rod and a screwed part
fitted with a nut.
The nozzle chest is arranged with one central
pipe, fitted with an expansion joint, and branch
pieces at the top and bottom for bolting to the
branches on the main cylinder of the engine,
as well as with the main steam branch located
at the top, so placed as to pass well under the
beams for supporting the platform. The steam
from the boiler is admitted into the central
nozzle between the valves, while the exhaust
takes place on the top edge of the top valve
A, Steam pipe. B B, Valve and the bottom edge of the bottom valve; the
cylinders. cc, Exhaust
pipes. DD, Expansion joints. steam from the top passing through pipes on
each side of the central pipe, which are like-
wise fitted with expansion joints. The exhaust steam from the top
Fig. 155.
Nozzle Chest for
Steam Cylinder.
254
MODERN STEAM PRACTICE.
of the cylinder passes down these pipes on each side, and they are
B
A
C
D
ப
connected to a cross pipe at the bot-
tom, which carries away the steam
from both ends of the main cylinder.
Two branch pieces are generally cast
on the cross pipe, for the convenience
of carrying away the exhaust on
either side, as may be determined on;
of course one of them has a blind
flange when completed. A cover is
fitted to the top nozzle chest, and one
to the bottom chest, the latter having
a short pipe turned on the exterior
surface.
The valve spindle passes down this
Fig. 156.—Stoup and Links for Valve Motion. pipe, and is connected to a solid end
on another pipe (technically termed
the stoup), by means of a coned hole

A, Valve rod. B, Stoup. c, Guide pipe.
D, Strap. E, Side link.
on the end of the pipe and a corresponding cone turned on the
"
C
A
B
B
D
1
valve spindle, fitted with a nut on the
end of the rod. On the top of the
stoup a stuffing box and gland is ar-
ranged, which makes it steam - tight
on the pipe that is bolted to the cover.
A wrought-iron strap with two side
pins is fitted on the stoup; these pins
take side rods passing downwards to
the pins on the levers of the weigh
shaft.
The wiper shaft is supported at
both ends on bearings, and is fitted
with a strong cast-iron lever, having
a pin for taking the eccentric rod,
with other two levers for the rods
connected to the stoup for working
the valves. A back balance lever,
fitted with a suitable weight for bal-
Motion.—A, Wiper shaft. BB, Levers for valve. ancing the valves, is also provided,
and this is cast along with one of the

Fig. 157.-Wiper Shaft and Levers for Valve
c, Balance lever. D, Eccentric lever.
levers for the stoup connection; while a socket is left on the double
STATIONARY ENGINES.
255
lever for the eccentric rod for the starting handle. These levers
should be made very strong and well feathered, and may be cast
along with the shaft, at least those for the stoup and balance
weight, but the eccentric lever should be made a separate casting
for adjustment. As the strain is light a cast-iron shaft and levers
may be adopted, when the weigh shaft is placed under the floor of
the engine house out of sight; but a preference ought to be given
to wrought iron in all valvular arrangements, as the material is
better adapted for any sudden strain, even although balance valves
are adopted.
The valves are actuated by means of an eccentric and rod. The

A
1
C
B

Fig. 158.-Eccentric and Rod.
A, Eccentric sheave. B, Eccentric rod and strap. c, Gab end.
eccentric sheave is so arranged that it can be put on and taken off
the main crank shaft without disturbing any other detail, and is
secured on the shaft with a key, as these engines only require to
be worked in one way. The eccentric rod is of wrought iron; one-
half of the strap is forged on with suitable lugs, and the other half
has lugs forged on for bolting the hoop together, with a single bolt
and nut for each lug. The rubbing surfaces are of brass, rivetted-
to the strap, and then accurately turned to suit the sheave. The
lugs on the strap do not fit closely together, so as to adjust at any
time the rubbing surface. Suitable mechanism for lifting the
eccentric out of gear when starting the engine should be arranged.
This may be worked in a variety of ways; with hand levers, or
with a foot lever and rod attachment, which the attendant can press
256
MODERN STEAM PRACTICE.
on with his foot while his hands are free to move the steam regu-
00
A
C
B
B B
OD
Fig. 159.-Bottom of Blowing Cylinder.
lating valve and hand lever, which is
placed in a socket on the gab lever
secured to the weigh shaft. This valve
gear and mechanism for working it is
very simple, and suits admirably for
engines fitted with a crank shaft and
fly wheel.
The cylinder for the air consists of
a round barrel with flanges at the
ends, truly bored out and the flanges
faced; it is bolted down on a square
base, which has nine openings for ad-
mitting the air into the cylinder, and
one large opening for its exit. The
A, Bottom. B B, Valve openings. c,Discharge former openings are fitted with flap
valves, made of an elastic material,

passage.
and backed with suitable wrought-iron plates; while the non-return
D
B
A
B
B
Fig. 160.—Cover and Valve Boxes for Blowing
Cylinder.
A, Cover. BB, Valve openings. C, Valve chest.
DD, Discharge valve openings.
valves for the bottom are fitted on
the passages for taking away the air
under pressure. The base is securely
bolted down with one large bolt at
each corner, passing through holes.
left in the foundation to the girder
plates at the bottom, and the bolts
are secured with keys bearing on
these plates; thus the foundation is
firmly bound together with plates at
the top and bottom similar to the
steam-cylinder end.
The cover for the cylinder is fitted
with a packing box and gland for
the piston rod, and has three open-
ings for the admission of the air, and
five smaller openings placed inside
of the branch cast on the cover for
the exit of the air. The former are
fitted with valve boxes, which are
bolted down on the cover, and have
a door fitted to the top of each box. There are four openings


STATIONARY ENGINES.
257
in each, and the valves are arranged nearly in a vertical position,
hinging from the top; while the valves for the exit of the air are


A
B
A
B
Fig. 161.-Top Chest for Blowing Cylinder.
A, Top chest. B, Passage on the cylinder cover.
Fig. 162.-Bottom Chest for Blowing Cylinder.
A, Passage for cylinder. B, Bottom chest.
placed quite flat on the cover, and are secured—as all these valves
are—with bolts and nuts, having a narrow strip of plate for the nuts
to bear on at the hinge.
The top and bottom chests for taking away
the air are formed of separate plates bolted
together like a tank, and the joints rusted with
a cement made of fine cast-iron borings, sal
ammoniac, and sulphur. The proportions used
for this cement are-sal ammoniac, 2 parts;
flower of sulphur, I part; cast-iron borings,
200 parts. It requires some time to set, and
makes a first-rate joint. The top chest is
bolted to the flange cast on the branch, and
the bottom one is let into the socket cast on
the base plate and then rusted up, and is fitted
with an inclined plate between the socket and
the bottom discharge chest-this plate having
four openings for the non-return valves. The
top and bottom chests are connected by means
of a circular column, securely bolted at the top
and properly jointed, no expansion joint being
required. The pipe for leading the air to the
wrought-iron receiver is fitted to the bottom
piping being circular.
B
A
Fig. 163.-Distance Pipe for Air
A,
Chests for Blowing Cylinder.
Distance pipe. B, Loose ring.
chest, the line of
•

17
258
MODERN STEAM PRACTICE.
The piston for the blowing cylinder should be light, yet strong.
It is fitted with a narrow junk ring for pressing down the packing,
B
A
C
Fig. 164.-Piston for Blowing Cylinder.
A, Piston. B, Junk ring. c, Packing space.
·
and held down with bolts and
nuts let into the piston. The
piston rod has a cone fitting into
a corresponding cone in the pis-
ton, and is secured with a plain
cotter passing through the boss
of the piston and rod.
We will now consider the de-
tails for actuating the pistons of
the steam and air cylinders simul-
taneously. The main beam is


cast in two halves, and held together by cast-iron distance pieces
with flanges for bolting to the halves. All the holes for the main
gudgeons should be accurately bored out, and the gudgeons turned
to fit. The one for the main connecting rod has collars turned on
it, and should be placed in position before the beams are bolted


C
A
B
D
Fig. 165.-Main Beam.
A, Beam. B, Steam cylinder end. c, Air cylinder end. D, Boss for connecting-rod gudgeon.
together; all the other gudgeons, excepting those for the feed and
cold water pump, have the journals on the outside of the beam,
and can be put in at any time; they are held in position with
keys. Some engineers prefer fitting four keys on the main gud-
geons, the hole being left larger, and after the keys are fitted lead
is run in, filling up the space; but this does not make such good
work as boring out the hole the exact size. For heavy cast-iron
beams of all descriptions, neat wrought-iron hoops should be shrunk
on the main boss, thereby binding the part that takes the whole
strain that is transmitted through the beam.
The pillow blocks are of the usual description, fitted with brasses,
STATIONARY ENGINES.
259
which are secured by means of covers and bolts; a broad base is
cast on the pillow block, and bolted at the ends to the spring beam,


A
B
Fig. 166.-Pillow Block for the Gudgeon of the Main Beam.
A, Pillow block. B, Boss for holding-down bolt.
while the large central bolt passing down through each column also
passes through a hole in the spring beam and base of the pillow
blocks, the nut bearing on the top of the base plate-thus firmly
bolting the pillow blocks, spring beam, entablature, and columns
together.
The spring beam is a light frame of cast iron running the entire
length of the engine house, and is built into the walls at the end.
The part inclosing the beam is formed as a half circle at the ends,
and in long spring beams a cross beam runs across the engine
house at each end, and is built into the side walls. The spring beam
proper ends at this cross beam, but its continuity is maintained by
bolting girders to the ends, which are built into the walls; these
and the cross girders are placed in mainly to support the spring
beam and carry the floor. In some cases stone flags are laid down,
but open cast-iron foot plates are preferable, and when neatly
executed give a light and airy appearance to the engine room.
When the engine is under repair, heavy weights must not of course
be placed on such a floor. Planking should be laid down on the
top of the beams which run across the engine room for carrying the
cast-iron floor plates; they should be made with thin raised parts,
260
MODERN STEAM PRACTICE.
with side flange pieces. By this means the floor plates are sup-
ported, and kept slightly apart from one another in the length of

B
C
D
D
Fig. 167.—Spring Beam.
C
D
A
A, Spring beam. B, Cross beam. cc, Pillow-block seats. DD, Bosses for holding-down bolts.
the building, but across the building they are simply placed end
to end.
The entablature placed between the spring beam and the top of
the columns runs across the building, and is built into the side walls,
and securely joggled and bolted to the spring beam. It is best to
form the entablature in two pieces, which are placed a short dis-
tance apart, and are hollowed out to take a projection cast on the
top of each column. All these longitudinal and cross beams are
supported by two columns, which rest on cast-iron plates laid on
STATIONARY ENGINES.
261
the top of the foundation; each column is bolted down with one
central bolt passing down to the bottom of the foundations, and a
cross plate takes both of the bolts, which are secured at the ends


1
A
D
1
E
D
C
Fig. 168.-Pillars and Entablature.
A, Pillar. B, Recess for bolt heads. c, Entablature. DD, Hollows for pillars. E, Wall box.
with proper keys, like all the main holding-down bolts for the
cylinders and crank-shaft arrangements.
The pillow blocks for the crank shaft are fitted with thick brasses
and strong caps and bolts, and at the crank end a plate is laid
down, butting against the steam cylinder and central pedestals of
the foundation. This plate has fitting strips cast on it with the
necessary joggles for fitting and securing the blocks at the ends;
holes are also cast in it for bolting the pillow block to, and for the
262
MODERN STEAM PRACTICE.
holding-down bolts which pass down through the foundation. At


A
B
Fig. 169.-Pillow Block for Crank Shaft.
A, Pillow block. B, Bed plate.
the other end of the crank shaft a plate is let into the side wall, a
proper arch being formed in the wall for its reception.
B
A
The crank shaft and crank
are of wrought iron, the latter
being bored in the main eye,
somewhat smaller than the
part of the shaft where it is
shrunk on. The crank is
slightly heated for that pur-
pose, it is then slipped on the
shaft, and cold water poured
over it, thus shrinking it
tightly on. The shaft should
be only a very little more in
diameter than the eye, as
when too much is allowed it
is apt to strain the material
and weaken the eye. The
crank and shaft should have
a keyway cut prior to the
operation of shrinking on, and when it is cleaned out quite smooth.

Fig. 170.-Main Crank.
A, Crank.
B, Crank pin rivetted in.
STATIONARY ENGINES,
263
ן
A
C
D
and fair the key is driven tightly in with a few strokes of a sledge
hammer, and then cut off and filed quite smooth at the ends. The
crank pin is held firmly in its eye by heating the eye and driving
the pin in with a hand hammer, and then pouring water over it, the
eye contracting and firmly binding the pin, which is then rivetted
over at the end, a part being turned out in the pin for that purpose.
The main connecting rod is generally of wrought iron, turned
from end to end, except
the square parts for tak-
ing the straps, which are
fitted with brasses, having
a jib and key, with a screw
turned on the key, which
passes through an oblong
hole in the bent part
formed on the jib, the
screw being fitted with a
nut on each side of the
jib. The rod is finished
bright all over, or at least
it should be turned all
over and painted. Some
connecting rods for the
blowing engine are made of oak, with wrought-iron straps on
each side, well bolted and hooped, and a metal piece at each end
securely bolted through the straps; this piece is for the brasses to
abut against. The latter are held in position with jibs and keys.
Although this form of connecting rod has not such a handsome
appearance as the metal one, yet it answers the purpose very well.
There is but little strain on it, as it merely (in connection with the
crank) changes the reciprocating motion of the pistons,—in fact, it
should just be made stiff enough to resist the strain at the dead
centre, as it is termed, elsewhere it merely imparts motion to the
fly-wheel shaft. It must be borne in mind, however, that a wrought-
iron connecting rod balances the heavy piston of the air cylinder
much better than one made of lighter material.


E
Fig. 171.-Connecting Rod.
A, Body of rod. B, Butt. c, Jib and cotter.
E, Strap.
D, Brasses.
For convenience of transportation the fly wheel is built up in
segments. Its central part is cast in one piece, and suited for eight
arms, each arm having its segment cast along with it. These seg-
ments are dovetailed into one another at the joinings, and then
264
MODERN STEAM PRACTICE.
firmly secured with oak and thin iron wedges; the same mode of
fastening the arms into the central part being adopted. Of course

D
C
B
A
E
Fig. 172.-Fly Wheel.
A, Boss. B, Wedging space for arm. C,
c, Arm. D, Rim. E, Dovetail at end.
there are other ways of fastening with bolts and nuts, used for fly
wheels for general purposes. The boss is keyed on the shaft with
a number of keys; but it is preferable to bore out the eye the same
diameter at the raised part of the shaft, where it is fitted on with
four keys, and a wrought-iron hoop should be shrunk on each side
of the boss; by this means the keys can be firmly driven home
without danger of splitting the boss, although there is not much
risk of this when the metal is properly proportioned and care is
taken to fit the keys; they should in the first instance be driven
with a hand hammer until nearly home, with the surface bearing
all over and filed quite smooth, then a few blows with a large
hammer are given to complete the operation.
STATIONARY ENGINES.
265
The piston rods of both cylinders are connected to the beam by

B
A
E
D
Fig. 173.-Crosshead.
A, Cast-iron crosshead. B, Gudgeon. c, Collars. D, Piston rod. E, Jib and cotter.
cast-iron crossheads and wrought-iron side links, and the vertical


C
D
B
A
E
Fig. 174.-Main and Back Links for Parallel Motion.
A, Main link,
B, Distance pillar.
c, Jibs and cotter.
F, Cotter for brasses.
F
F
0
DD, Plates.
E, Back link.
266
MODERN STEAM PRACTICE.
line is attained with the ordinary parallel motion, having fore and
back links, parallel bars, radius rods, and cross gudgeons for the
back links. The cast-iron crossheads are turned all over, and are
secured to the piston rods with jibs and cotters; on each side a
cast-iron ring and thin brass collar is laid on the gudgeon, which
is secured with a key at each end; the outside bearings are for
the main links, while the large eye of the parallel bar is placed
between the main links and the brass washers.
The main links (Fig. 174) are plain wrought-iron straps, fitted with
brasses at the top and bottom, having a distance column between
them, bearing on wrought-iron plates fitted between the flanges of
the brasses at the bottom of the top pair and at the top of the bottom
pair; these brasses are held in position with two jibs and one key, a
screw bolt being formed on the bottom jib, fitted with two nuts, one
on each side of the eye formed on the end of the key, an elongated
hole being made in the eye. The straps in some cases are turned
all over on the outside, and oil cups formed on their tops; when got
6

A
B
4
I
I
Fig. 175.-Bull's Eye and Cross Shafts for Parallel Motion.
rod. c,
c, Cross shaft.
A, Cross shaft for cold-water pump rod. B, Bull's eye for cold-water pump rod.
up in first-class style they add greatly to the beauty of the engine.
The back links are two plain round rods; the one for the steam
cylinder has eyes forged on the ends, fitted with brasses held by a
single key, and the one for the air-cylinder end has an eye at the
middle for taking a bent cross bar, to which the cold-water pump
rod is secured. The bottom bar has an elongated eye at the middle
for the rod to pass through, the cross bar for the back link of the
STATIONARY ENGINES.
267
A
steam-cylinder end being quite plain. The parallel bars are fitted
to the crosshead and to the cross bars on the back links, the brasses
being adjusted with a single key;
the radius rods are similar, and
work on a pin fitted to a bracket
which is secured to the spring
beam at the cylinder end, and
the other eye takes the cross bar
for the back links. In setting out
this parallel motion, the length
of the links from centre to centre
is one-half of the piston stroke;

B
Fig. 176.—Bracket for Parallel Motion.
A, Bracket. B, Pin secured with nut.
the centre for the back links on the beam is equidistant from the
end of the beam and the centre of vibration. The parallel and
radius rods are exactly this length
from centre to centre, or the dis-
tance from the back-link centre to
the end centre of the beam; the
true line of the piston rods being
one-half of the versed sine of the
chord contained by the full arc
delineated by the travel of the
beam, taking the distance from the
end centre to the centre of vibra-
tion as the radius.
The cold-water pump is a plain
open barrel, fitted with a suction
valve of leather, stiffened with
wrought-iron plates at the top
and bottom, rivetted through and
through, and hinged on a separate
conical valve seat. A cross bar,
having an eye at the top, is fitted
for holding down the leather, and
for drawing out the valve and
seating; this is secured to the


-
B
B
Motion. A, Parallel rod. B, Radius rod.
latter by a cotter passing through Fig. 177.-Parallel and Radius Rods for Parallel
the shank forged on the cross bar,
the cotter bearing on the under side of the web cast along with
the seating. The bucket is fitted with a valve of a similar descrip-
268
MODERN STEAM PRACTICE.
tion.
The packing of the bucket is a plaited gasket, or gutta-
percha rings may be adopted, and kept to the circumferential sur-
face of the barrel by the hydraulic pressure of the water, a small
hole being bored at the top in communication with the recesses
left in the bucket. The pump rod is connected to the cross shaft
placed at the centre length of the back link, passing through an eye
formed on the shaft at the bottom end. The water is pumped into
a cistern provided with an overflow pipe, the exhaust steam passing
over the surface of the water and then escaping through another pipe
A
E
into the atmosphere; by this means
the feed water is heated before it is
forced into the boiler by a plunger
pump, the rod for working it being
connected directly to the beam by a
gudgeon passing through it, and to the
plunger with a pin joint. The valves
and their seatings are of brass; and
a relief valve should be fitted, loaded
with a weight, to return the water
into the well or pond from which it is
drawn by the cold-water pump. This
of course is only required when a re-
gulating valve is placed on the boiler;
but should the valve for regulating.
the supply to the feed pump be placed
on the suction pipe, a relief valve may
be dispensed with. In either case,
however, it is desirable to have one
fitted close to the pump, so that in the
event of the water in the feed pipes
freezing the line of piping may not
be damaged; and to guard against this evil, a small plug tap
should be fitted to the line of feed pipes, and so placed that all the
water may be run off between the check valve on the boiler and
the pump.

A, Pump.
C
Fig. 178.-Feed Pump.
E
B, Plunger. c, Suction valve.
D, Delivery valve. E E, Brackets.
The steam-regulating valve fitted to the nozzle chest should be
placed so that the attendant can reach it easily when starting the
engine. It consists of a sluice valve of brass, fitted on a cast-iron
face, accurately planed and scraped to a true surface,—the valve
chest being fitted with two covers to facilitate the operation of
STATIONARY ENGINES.
269
scraping truly. One of these covers is fitted with a packing gland
for the valve rod, which is actuated with a lever handle having a
stud fitted to the

valve box, with a
joint and pin for
taking the starting
handle. The valve
rod is secured to
the valve with a
C
pin passing through two snugs cast on the
valve, and has a slot crosshead keyed on the
outside, which the handle passes through.
The arrangement of the boilers for this
engine is described in the section treating on
boilers (p. 39). Three egg-ended boilers
were supplied, each 38 feet in length and
5 feet 7 inches in diameter.
A

AA B
In some examples of blowing engines erec- Fig. 179.—Steam-regulating Valve.
ted at the Dowlais Iron Works the general A, Valve chest. B, Valve.
arrangements are the same as the foregoing.
c, Handle.
The beam is supported on a wall carried up from the foundation,
with a cast-iron wall box on which the pillow blocks are fitted.
This pedestal is secured by long bolts and nuts passing through a
plate at the bottom of the foundation; these bolts, passing from the
top to the bottom, firmly bind together the lever wall. The pillow
blocks are securely bolted and joggled to the wall box, and are fitted
with brasses, but there are no caps, the brasses being held down
with jibs and cotters passing through the sides of the pillow-block
frame. Wooden spring beams are substituted instead of cast iron;
they are let into the box on the lever wall, and pass along to the
end walls of the engine house; transverse beams also are secured
to the longitudinal ones for supporting the flooring. The beam is
fitted with parallel motion, the main links taking the crosshead of
the piston rods being placed between the beams, as are also the
back links. The parallel bars and radius rods are fitted outside
of these, the latter taking a pin on a cast-iron bracket bolted to
the spring beam.
The steam cylinder in this example (Figs. 180, 181) is 55 inches
diameter, stroke of piston 13 ft.; number of strokes per minute, 20;
steam pressure, 60 lbs. per square inch. An ordinary slide valve
270
MODERN STEAM PRACTICE.
are formed in one casting, each having a separate cover; they are
at one-third of the stroke of the piston. Both of the valve chests
E
C
O
GC
A
working on the back of the valve casing, arranged to cut off the steam
worked by an eccentric is fitted, having a gridiron expansion valve,

B
Fig. 180.-Blowing Engine at the Dowlais Iron Works. Side Elevation.
▲, Blowing cylinder. B, Discharge pipe. c, Steam cylinder. D, Slide valve. E, Expansion valve. F, Small slide valve for
moving the engine. G, Cast-iron framing. H, Main beam. 1, Crank shaft. K, Connecting rod.
L, Wall for supporting the beam. M, Pedestal.
STATIONARY ENGINES.
271
placed at the bottom of the cylinder, with a connecting pipe fitted with
an expansion joint, forming the passage to the top of the cylinder.
A separate slide valve is also fitted for starting the engine, which is

P
P
pagina
C
G
G
Fig. 181.-Blowing Engine at the Dowlais Iron Works. End Elevation.
worked by hand; but the main slide valve has the ordinary eccentric
motion, with weigh shaft side rods and crosshead overhead, the
valve rod being guided at the top by a stud placed on the passage
between the top and bottom of the cylinder. The valve rod passes
272
MODERN STEAM PRACTICE.

E
1
I
F
through a stuffing box on the under
side of the valve casing. The
expansion valve rod also passes
through stuffing boxes at the top
and bottom, and may be actuated
by an eccentric or cam motion.
The pedestal for bolting the cylin-
der to rests on massive frames of
cast iron, and is raised somewhat
above the line of the crank shaft;
the castings under the cylinder
weigh 75 tons, and the foundations
contain 10,000 cubic feet of lime-
stone in large blocks; thus securing
a firm bedding for the machinery.
When the main parts of such heavy
castings can be run from smelting
furnaces where the engine is to be
fitted up, of course cast iron is
largely used; but where transport
is necessary recourse must be had
to the usual mode of building the
foundations with stone or brick-
work laid in cement.
The crank is of cast iron, but the
shaft is better of wrought iron, al-
though many cast-iron ones are
in use.
The pillow block for the
crank end rests on one of the
frames to which the cylinder pe-
destal is bolted; the other end of
the shaft passes through the side of
the engine house, and is supported
by a pillow block resting on a mas-
sive wall plate.
The fly wheel is 22 feet in dia-
meter, weighs about 35 tons, and
is fitted up in segments in the usual
manner, the arms being fitted into
D, Slide valve. E, Expansion valve. F, Small valve for moving the engine.
Fig. 182.-Section through Steam Valves.
STATIONARY ENGINES.
273
a large centre piece, and securely dovetailed into the rim at the
extreme diameter.
The main part of the connecting rod is of oak, strapped with
wrought iron from end to end, well bolted together, and in addition
secured with a strong hoop shrunk on at the middle. Blocks of cast
iron are fitted to the ends of the rod for the brasses to bear against,
the blocks being bolted through and through the straps; and as both
ends of the rod are forked, the brasses are adjusted with deep jibs
and keys. The top end is placed between the beam, as in the
previous example.
The beam has a total length of 40 feet between the outside.
centres, and is so arranged as to give a stroke of 13 feet to the
steam piston and 12 feet to the air piston. It is cast in halves, each
half weighing 16½ tons, the total weight on the centre gudgeon,
including all the minor details, being about 44 tons. The wall for
supporting the beam and its adjuncts is 7 feet in thickness, built of
stone accurately dressed; the pedestal on which the main pillow
blocks rest is bolted down with twelve bolts, 3 inches in diameter,
taking a wall plate, the extreme breadth of the lever wall, placed
below the level of the floor, for the blowing-cylinder end.
The blowing cylinder is 144 inches in diameter, stroke 12 feet; and
as the piston makes twenty double strokes per minute, the quantity
of air discharged is nearly 54,283 cubic feet per minute, delivered at
a pressure of 34 lbs. per square inch. The area of the entrance
valves is 56 square feet, and that of the delivery valves 16 square
feet. The cylinder is cast in two pieces, and is bolted down to the
bottom plate, which is strongly ribbed in the casting, and arranged
with a suitable number of openings for the air flap valves. This
bottom plate is supported on pillars of cast iron at convenient
distances all round, which are stepped on a massive cast-iron plate
resting on the top of the foundation, and to which it is bolted with
long bolts passing down through the foundations, and secured at
the bottom with keys bearing on a wall plate built into the stone-
work. The cover is fitted with valve boxes, as in the previous
example, the flap valves beating against the angular sides of the
boxes. The boxes are fitted with covers at the top, through which
the inside of the cylinder may be inspected. There are also fitted
at the top and bottom large entrance valves, placed vertically
immediately over and under the discharge passages. The non-
return or discharge valves are placed in a line with and immediately
18
274
MODERN STEAM PRACTICE.
opposite the large entrance valves, and are fitted to the discharge
chambers. The discharge pipe is 5 feet in diameter, it is carried
140 yards in length, and acts as a capital regulator, providing a

Ꮐ
B
A
E
F
Fig. 183.-Vertical Section of Blowing Cylinder.
A, Cylinder. B B, Bottom valves. cc, Top valves. D, Top discharge valves. E, Bottom discharge valves.
F, Discharge pipe. G, Pillars for supporting the bottom plate of the cylinder.
uniform blast to the furnaces, the engine being calculated for sup-
plying a blast to eight furnaces, whose diameters across the boshes
vary from 16 to 18 feet.
Eight boilers are supplied, of the Cornish description, each 42 feet
long and 7 feet in diameter, with a single flue, 4 feet in diameter,
running from end to end. The length of fire grate is 9 feet—which
is too long to manage properly.
SIDE-LEVER COMBINED BLOWING ENGINES.
High and low pressure combined engines have been successfully
adopted for blowing furnaces. The side levers, two in number, are
placed one on each side of the steam cylinders; the high-pressure
STATIONARY ENGINES.
275
cylinder being at one end, and the low-pressure cylinder at the
other end. The blowing cylinders are placed overhead, and rest
on stone pedestals built up from the foundation. The engine house

O
00
Fig. 184.-Side-lever Combined Blowing Engines, by Wilson of Patricroft.
is about 75 feet long, 60 feet wide, and 72 feet in height, and con-
tains three pairs of engines.
The high-pressure cylinder is 45 inches, and the low-pressure one
66 inches in diameter; the blowing cylinders are each 100 inches.
in diameter; and the length of stroke for all the pistons is 12 feet.
276
MODERN STEAM PRACTICE.
Cornish valve gear, arranged for double action, is fitted to both of
the steam cylinders. The steam, after doing duty on the top of
the high-pressure piston, expands on the top of the low-pressure
piston (and vice versa), and then exhausts into the condenser; it
will therefore be understood that two steam valves and two exhaust
valves are fitted to each cylinder. The hand gear is placed on the
low-pressure cylinder, and is connected by rods running below the
flooring to the gear for the high-pressure cylinder; the attendant,
therefore, from one platform can actuate by hand all the eight valves;
or, in other words, the movement of the one set of gear for the
steam valves of the one cylinder controls the movement of the
steam valves of the other cylinder-the exhaust valves acting in the
same way. Thus it will be seen that, with a steam and exhaust
valve fitted at the top and bottom of each cylinder, the action will be
as follows: Supposing steam from the boiler is acting on the bottom
of the high-pressure cylinder, forcing up the piston, the lower
exhaust valve and top steam valve are shut and the top exhaust
valve open, while the top steam valve on the low-pressure cylinder
is open and the top exhaust shut; thus the steam expands from
the top of the small cylinder into the large one, at the same time
the exhaust valve for the under side of the low-pressure cylinder is
open to the condenser, the bottom steam valve being shut. The
reverse of this takes place on the downward motion of the high-
pressure piston. Thus the high-pressure piston is raised and
depressed by steam direct from the boiler, while the low-pressure
piston is raised and depressed by the exhaust steam from the high-
pressure cylinder. An additional benefit accrues from the final
condensation of the steam, as the top and bottom of the cylinder
are in alternate communication with the condenser; power is thus
gained and fuel economized. The arrangement of the Cornish
valve gear may appear complicated when applied to one engine;
but it must be remembered that this complexity consists merely
in an increase of parts, as the whole of the gearing is joined together
and works in unison.
The main side levers have a length of about 38 feet from centre to
centre, and each weighs upwards of 20 tons; they are connected to
the crosshead of the piston rod, common to both cylinders, by side
rods. The vertical motion of the piston rods and crosshead is main-
tained by cast-iron guides, the distance from the top of the steam
cylinders to the bottom of the blowing cylinders being about 17 feet.
1
STATIONARY ENGINES.
277
C
BOGA
The air pump is worked by means of a crosshead with connecting
rods from the side levers; the
plug rod for the valve me-
chanism is a continuation of
the air pump rod, guided at
the top with a bracket fitted to
the nozzle chest. It is essen-
tial for this class of engine to
have a travelling crane fitted
overhead, so as to lift the pis-
tons, &c., for inspection or
repair.

VERTICAL BLOWING ENGINES.
Another example is the
vertical direct-acting high-
pressure engine, which differs
materially from the foregoing
in having no side levers or
beams. The blowing cylin-
ders are placed on the ground
floor, four strong cast-iron
pillars are securely fitted, one
at each corner, and carried up
F
B
A
D
to the top of the house, with
cross girders for carrying the
steam cylinder and fly-wheel
shaft. The blowing cylinder
is 1084 inches in diameter,
and the steam cylinder, placed
overhead, is 474 inches in
diameter; the stroke of each
is 6 feet 634 inches. The fly-
wheel shaft is 25 feet 10 inches
above the floor of the engine,
and the total height from the Fig. 185.-Vertical Blowing Engine at the Creuzot Iron
F
F

10000
E
00000 900000
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J
Works, dep. Saône-et-Loire, France.
base to the centre of the crank A, Blowing cylinder. B, Steam cylinder. c, Crank shaft.
shaft is about 44 feet 3 inches. D, Fly wheel. E, Bottom of air cylinder. FF, Pillars.
The crank is connected by a rod to a crosshead working in guides,
278
MODERN STEAM PRACTICE.
taking the rod for the steam piston, which passes down through
a stuffing box at the bottom of the steam cylinder, and is con-
nected to the piston for the blowing cylinder. This class of
blowing engine has a fly wheel; the valve gearing is worked from
the fly wheel shaft, spur wheels being used to drive a cam shaft
which actuates equilibrium valves. The steam is admitted into the
cylinder at a pressure of 60 lbs. per square inch, and is cut off at

ΓΙΟΣ
K
K
H
B
I
L
E
M
M
A
M
1140
D
D
Fig. 186.—Table Blowing Engine.
A, Blowing cylinder. B, Steam cylinder. c, Crank shaft.
FF, Eccentrics for air valve. G, Eccentric for steam valve.
K, Crosshead. L, Guides. M M, Air pipes.
DD, Fly wheels.
H, Steam valve.
E, Air valve.
II, Side rods.
about one-fourth of the stroke; the number of revolutions of the
crank shaft is about fifteen. The inlet and exit valves for the
blowing cylinder are arranged on the cover and bottom of the
cylinder; small flap valves are used, one-half of the area being for
the inlet, and the other half for the exit of the air, which is
delivered at a pressure of about 3 lbs. per square inch, and the
quantity is about 90 per cent. of the cubical contents of the cylinder
at each stroke.
STATIONARY ENGINES.
279
B
Vertical Table Engine.-We shall now notice the kind of blowing
engines called "self-contained," that is, those erected on one bed plate
carrying the whole of the engine. Of this class are the vertical table
engines, which are constructed for easy transport, all the parts being
as light as possible (Fig. 186). The blowing cylinder stands on a
pedestal bolted to the bed plate. The diameter of the cylinder is 30
inches; stroke of piston 2 feet 6 inches, making 80 strokes per minute.
These engines being small, a greater number of them must of course
be provided; and when large sizes are adopted the weight of the
various parts becomes a serious matter. The piston of the blowing
cylinder is packed with hemp, with a junk ring to press it
down. The openings for admitting the air into the cylinder
are formed on the circumference at the top and bottom; a
projecting flange is cast on at the top and bottom, the bars
between the opening being inclined, similar to the piston-
valve arrangement already described. The valve is of the
annular description, encircling the whole cylinder from top Fig. 187.
to bottom; the rubbing surfaces are formed of brass rings
accurately bored out. The body of the valve is formed of thin
wrought-iron plates, securely fastened with a number of small bolts
to two cast-iron rings, which are bored out inside for the reception
of the brass packing rings. These rings fit the recesses in the
cast iron and face on the cylinder without any other packing; and
as they are cut through the wear can be adjusted with a thin slip
of metal or paper, and then properly secured with bolts, although
there is but little wear with this description of valve, owing to its
being perfectly balanced. The air from both ends of the cylinder
passes into the annular space between the cylinder and the valve,
from which it escapes by two pipes, placed opposite each other,
with flanges for jointing them to the cylindrical part of the valve.
The pipes at the other end slide on a vertical surface prepared for
them; the motion is small, as the pipes are long, and the vertical
motion of the valve is not great. The valve is driven by two
eccentrics, one on each side of the cylinder, with rods taking pins
fitted to the top cast-iron ring. The steam cylinder is placed
on the top of the blowing one, and is fitted with a common valve,
with sufficient lap to cut off the steam at one-half of the stroke.
The piston-rod crosshead is fitted with two connecting rods taking
the cranked shaft, the crosshead working in suitable guides. Two
1 Section of Air Valve. —A, Valve. B, Plate for connecting valves.
280
MODERN STEAM PRACTICE.
fly wheels are fitted, thus less diameter is required for a given
weight, and it is found desirable to limit the weight to I ton. When
the means of transport is difficult no part of the engine should
exceed this weight. These engines do not require massive and
expensive foundations; they can rest on balks of timber with merely
a few bolts to hold them down. They can also be driven at a high
velocity, owing to the action of the valve preventing all blow and
jar in the working, when the lap and lead are properly adjusted:
a pair of them can be worked together, the cranks being at right
angles to each other, causing great uniformity in the flow of the
blast, and no regulator is required. A pair of these engines, with
a piston speed of 400 feet per minute blowing 3600 cubic feet of
air, make a very compact arrangement for small-power blowing
engines.
HORIZONTAL BLOWING ENGINE.
Horizontal high-pressure blowing engines have been extensively
used. In the following example (Fig.188), which is one of the largest
description, the diameter of the steam cylinder is 4 feet 3 inches,
with a stroke of 9 feet. The blowing cylinder has a diameter of
108 inches, and the length of stroke is the same as for the piston of
the steam cylinder, the number of strokes being about twenty-two,
giving a total speed of 396 feet per minute.
The steam valves (Fig. 189) are of the piston type, which are very
generally used for blowing engines, because they are perfectly
balanced, and therefore suffer little wear and tear, which is a great
desideratum with engines requiring to go day and night for a length-
ened period. The valves are cast together with a pipe connection,
each piston is packed with a single ring, which is kept up to the
working face by a spring; the junk rings are each secured with a
single nut having a thread cut on the valve spindle, which is central
with the valves. The valve casing is a circular casting; the steam
is admitted between the valves, and the exhaust takes place at both
ends. The valves are arranged so as to make the steam ports as
short as possible; and there is an annular ring round the piston, to
give free entrance and exit for the steam all round the circumfer-
ence of the valves. The valve rod passes through stuffing boxes at
both ends of the casing, and as the valves are placed at the side of
the steam cylinder, the motion for working them is direct, a plain
STATIONARY ENGINES.
281

A
B
CH
LO
Fig. 188.-Horizontal Blowing Engine. A, Steam cylinder. B, Crank shaft. c, Blowing cylinder
282
MODERN STEAM PRACTICE.
eccentric and rod being adopted, having a joint placed close up
to the guide block for the valve rod, carried up considerably

C
A
D
B
コ
​D
Fig. 189.-Steam Valve for Horizontal Blowing Engine.
A, Valve.
Valve rod. c, Packing ring. D, Connecting pipe.
B
beyond the stuffing box, thus lessening the length of the eccentric
rod.
The steam cylinder (Fig. 190) is of the ordinary description, with
projections cast on for bolting down to the bed plate. It is provided
with a cover and stuffing box at each end, through which the piston
rod passes, with recesses for the nut and collar that secures the piston
to the rod. The piston should be as light as practicable, and its
ends strengthened with ribs in the casting; the packing is metallic,
held up to the face with a number of short flat springs; the junk
ring is bolted down with bolts and nuts recessed in the piston in
the usual manner. To prevent radiation the cylinder and valve
casing are covered with felt and wood lagging; and straps of
wrought iron or brass are used to bind securely the wooden strips
placed over the felt. The main crank is of cast iron, and is con-
nected to the piston rod by a wrought-iron rod, with straps, jibs,
and keys at both ends, having a wrought-iron crosshead and gud-
geon with blocks working in cast-iron motion bars; thus one end
of the piston rod is truly guided, while at the back end it takes a
crosshead working into a slipper guide, to which the piston rod for
the blowing cylinder is securely cottered.
The blowing cylinder (Fig. 191) is a plain casting, with side flanges
for bolting it to the bed plate which runs the entire length of the
STATIONARY ENGINES.
283
E
00
O
O
O
O
о
о
о
O
O
A
O
plained. The diameter of the piston rod is greater than that for
the steam cylinder, which tends to carry up the piston. Some
T
о
O
O
O
о
о
Longitudinal Section
O
O
o a o
о
A, Cylinder. B, Piston.
OF
engine. The piston rod passes through both ends of the cylinder,
and is guided with crossheads and slipper guides, as already ex-

Transverse Section:
αρ
End Elevation.
Fig. 190.-Steam Cylinder.
cc, Covers. D, Valve. E, Valve chest. F, Brackets for bolting down to frame,
284
MODERN STEAM PRACTICE.
engines of this class have a trunk passing through both ends in a
similar manner, by which means more bearing surface is obtained
for carrying up the piston, it being supported as it were with a
tubular beam,-thus reducing the wear and tear in the cylinder.
The air valves are arranged in the covers, and consist of round
A
discs, working on suitable grat-
ings, with guards to limit the lift.
The valves for the entrance of
the air are placed centrally round
the stuffing box for the piston
rod, that part of the cover being
strongly ribbed in the casting;
and an annular chamber is cast
round the circumference of the
cover, which is fitted with valves
of the same description for the
exit of the air,-a large opening
being left at the bottom, in con-
nection with the main pipes, &c.,
to the furnaces. Small covers
are fitted for the convenience of
inspecting the exit valves.


This engine is used to blow air
to two furnaces; the area of the
blowing piston is 63072 square
feet, and it discharges 24,976
cubic feet per minute. As ample
rubbing surface in all the work-
ing parts has been well consi-
dered, this engine has been found
to be very economical in the
matter of repairs. The diameter
of the fly wheel is about 21 feet;
and as the whole of the ma-
chinery is built up on one frame,
from end to end, the foundation is laid in brickwork, with about
2 feet of stonework on the top. This class of engine is certainly
the cheapest that can be supplied for heavy work; and the engine
house need not be so large as for the overhead-beam arrange-
ments.
Fig. 191.-Blowing Cylinder and Cover.
STATIONARY ENGINES.
285
ROLLING-MILL ENGINES.
Engines for driving rolling mills, &c., should be made strong, as
they require to run for weeks without stopping. The examples
shown in Figs. 192 and 193, of engines erected at the Dowlais Iron
Works, are unusually strong. Cast iron is largely used in their con-
struction. They are of the high pressure kind, coupled at right
angles to each other.
The steam cylinders are 45 inches in diameter, with a stroke of
10 feet, making 24 double strokes per minute. Each cylinder has
a common slide valve of brass, worked by an eccentric on the main
shaft. The expansion valves are of the gridiron sort, worked by a
cam on the main shaft, the steam being cut off at about one-third
of the stroke; an arrangement is made for throwing these valves
out of gear when the engines are doing heavy work. Each engine
is fitted with a small slide valve to be worked by hand, for the
purpose of starting and reversing.
The framing under the engines and machinery is of cast iron,
and consists of four lines, each 75 feet long, 12 feet high, and
21 inches wide, the whole weighing about 850 tons. The whole
engines are thus self-contained,—a very important point in this
class of engine.
Each beam is in two parts, each part weighing about 17 tons,
making the total weight of the beam when complete about 37 tons.
The two beams are supported upon eight columns, 24 feet long
and 2½ feet in diameter, securely fastened at the bottom in deep
jaws cast upon the framing. Upon the top of each group of four
columns is a large and heavy entablature plate, which carries the
pillow blocks for the main gudgeons. Each column passes through
the entablature, the bosses at the junction being 24 inches deep;
these are bored out, and the tops of the columns turned, so as to
insure a perfect fit. The pillow-block brasses are secured and
tightened up by wrought-iron keys in the jaws of the pillow blocks,
which are bolted down on the entablature, and further secured with
joggles and keys.
The connecting rods are of oak, with wrought-iron straps; an
experience of forty years having proved that such rods are the
best, and more easily kept in repair than cast-iron ones, which are
286
MODERN STEAM PRACTICE.
oak rod, strapped with wrought iron, is better calculated to stand
A
E
О
O
H
L
K
L
L
L
Ό
G
O
C
บ
O
OGO
G
A, Slide valve. B, Expansion valve.
c, Cylinder. D, Small valve. E, Link.
F, Piston rod. G. Framing. H, Beam.
1, Crank shaft and spur wheel.
K, Connecting rod. LL, Pillars.
M M, Pedestals. N, Entablature.
o, Fly wheel and shaft.
s, Pinion for driving rolls.
0
O
O
ว
O O O
O
OLIO GO! 0
Fig. 192.-Rolling-mill Engine at the Dowlais Iron Works. Side Elevation.
liable to break, while wrought-iron rods are much heavier. The

O
STATIONARY ENGINES.
287
ROLLS
The driving-wheel shaft is of cast iron, 24 inches in diameter;
T
M
O
Fig. 193.—Rolling-mill Engine at the Dowlais Iron Works.
ROLLS
the severe and sudden strain, as the material possesses an elasticity
which tends to lessen the shock.

ROLLS
End Elevation.
288
MODERN STEAM PRACTICE.
the fly-wheel shaft is also of cast iron, with bearings 21 inches in
diameter. The diameter of the driving wheel is 25 feet at the pitch
A
R
Ов
Fig. 194.-Details of Fly Wheel, Framing, and Pinions.
A, Fly wheel, showing mode of fastening. B, Frame, showing mode
of fastening. c, Pinions.
line; the pitch is 7
inches, and the width
of the teeth 27 inches.
The diameter of the
spur wheel or pinion
on the fly-wheel shaft
is 6 feet, and the teeth
are strengthened by a
flange running up to
their points on each
side. The fly wheel
on the mill shaft is
21 feet in diameter,
and weighs about 30
tons; it makes up-


wards of 100 revolutions per minute. The whole of the fastenings
both of the wheels and framing are of dry oak and iron wedges.
The blowing engines of this firm, described in the preceding
pages, are of 650 nominal horse-power, and weigh about 300 tons,
including the bed plate; the pair of rolling-mill engines are of
1000 nominal horse-power, and contain about 1000 tons of metal,
or I ton per nominal horse-power. This is very nearly double the
ordinary proportion, but it is the practice of this firm to make their
engines very strong, so as to avoid if possible the need of stoppages
of the works caused by a break-down of the machinery. The steam
for the rolling-mill engines is supplied by six Cornish boilers, each
44 feet long and 7 feet in diameter, with a 4-feet tube. The whole
of the plates are best Staffordshire, inch thick; the total weight
of the boilers is about 120 tons.
9
These engines can drive one rail mill capable of turning out
1000 tons of rails per week, another mill capable of making 700 tons
of rails or roughed-down per week, and one bar or roughing-down
mill, capable of making 200 tons per week; thus turning out a
total of about 2000 tons of iron per week. Two blooming mills
with three high-rolls and two hammers, are also worked by the
same engines. The saws and small machinery are driven by
separate engines, as also the punching and straightening machines.
The roofs cover a space of 240 feet by 210 feet, and are formed of
STATIONARY ENGINES.
289
corrugated black plates, No. 14 wire gauge in thickness. The spans
are 50 feet, the roofs being supported upon lattice girders of an
average length of 45 feet. The position of the columns is shown
on the ground plan, Fig. 195; and it will be observed that the entire
$
BB
田
​BB
•
B
B
Bloomang
Hammers
Blooming
Mill $ $ Mill
Rail
Rail
Mil
· Mill
원
​
Roughing down
Mill
B9
Engine
Fig. 195.-General Arrangement of Rolling Mill. Ground Plan.
mill floor is free from obstruction. The flooring is of cast-iron
plates, I inch thick.
It had long been felt that the power of rolling wrought iron of
large section and great lengths had not kept pace with the require-
ments of engineers, who were frequently hampered in their designs
by the impossibility of obtaining iron of sufficient dimensions. For
engineering works of any magnitude bars of great length, consider-
able width, and moderate thickness are often required; and in the
ordinary mode of rolling, the length and width of the bar are
measured by the power of the engine and the time occupied in
rolling. It is obvious that to finish a bar quickly it is necessary
19
290
MODERN STEAM PRACTICE.
that it should be rolled in two directions to prevent delay; and
long and heavy bars can be thus rolled only by an engine of enor-
mous power, such as the large combined engines we have described.
A simple arrangement of rolls for working in two directions has
been adopted, by which means large bars of thin section are finished

•

a,
Fig. 196.-Arrangement of Rolls for rolling in two directions.
A A, Rolls driven from fly-wheel shaft. B B, Rolls driven from the fly-wheel shaft by a pair of
wheels cc, Fig. 194.
in one heat, as it is impossible to get such large bars into the fur-
nace to re-heat. In ordinary rolling so much time was lost in
bringing back the bar over the top of the rolls that it was found
impossible to make the larger sizes required for modern work, and
the plan was therefore adopted of having a second pair of rolls
running in the opposite direction, placed at the back of the first
rolls, as seen in Fig. 196, the lower one of the second pair being
raised just enough above the upper one of the first pair to clear
the bar in coming through, and the bar is passed back through the
second rolls, and then through the third, fourth, and fifth rolls as
may be required, as shown by the figures in the engraving.
By
+
STATIONARY ENGINES.
291
this means much time is saved over the ordinary method, with
the additional advantage of being able to manufacture bars up
to 60 feet long, for deck beams and keels of iron ships, in one
length without a weld, which can only be effected by having a high
speed of the rolls so as to complete the work before the bar gets
too cold. Reversing gear has been used for the rolls, but it is
not to be recommended for them when running above forty-five
revolutions per minute, on account of the violent shock in reversing
the motion at a higher speed. To roll the length required for the
above purposes the speed at the Dowlais Iron Works is nearly
three times as great, the ordinary rolls running at 120 revolutions
per minute, and the others for large sections at 110 revolutions,
the rolls being of the full size-21 inches in diameter.
COMPOUND REVERSING RAIL MILL ENGINES,
AT HALLSIDE STEEL WORKS, NEAR GLASGOW. (SEE Plate.)
"The engines are of the compound direct-acting horizontal type,
and have two high- and two low-pressure cylinders, whose diameters
are respectively 31 inches and 50 inches, while the length of stroke
is 5 feet. They act directly on the rolls, by which arrangement
there is obtained a very high speed in the rolling operation with a
comparatively limited speed in the engines, the latter making from
fifty and sixty revolutions per minute. In each case the high-
pressure is placed in rear of the low-pressure cylinder, with which
it is connected by means of an intervening receiver. Laid upon
a bed of hard and tough blue clay, the foundation of these engines
-the total weight of which is some 300 tons-consists of a solid
mass of Portland cement concrete, 12 feet or 14 feet in thickness,
and weighing between 500 tons and 600 tons. To this foundation
is fixed the soleplate, which weighs about 60 tons, and carries the
two pairs of cylinders, as also the two main frames. The latter,
which are of the box form, are, as will be seen in the Plate,
arranged so as to form a direct connection between the low-pressure
cylinders and the crankshaft, while the pedestals for the crankshaft
bearings are cast solid with them. Under each crankshaft bearing
the frame has a strong foot, which is not only bolted down to the
soleplate by two holding-down bolts, but which has in addition on
292
MODERN STEAM PRACTICE.
each side oval bosses, on which there are shrunk steel hoops for
tying down the central part of the foot to the soleplate; while the
ends are keyed in between strong snugs cast on the same plate.
Each crankshaft bearing

is provided with four
brasses, one above and
one below, and one on
each side. The fore and
aft parts are fitted with
movable wedge blocks
which take up the wear,
these blocks being pro-
vided with slotted eyes,
and being suspended by
means of bolts, which
are flat-headed, but of a
circular form. The top
brasses are adjusted with
set screws, and both they
and the bottom brasses
are held in position by
the top cover, which
bridges over the opening
in the frame. On each
side of this opening there.
is a strong dovetailed
projection over which the
cover is placed. Itself a
strong steel forging, this
cover is most securely
keyed in position, in ad-
dition to which it is
bolted down hard and
fast. The arrangements
D
D
B
....
Β'
Ո
O
Fig. 196A.-Section through Cylinders.
A, High-pressure cylinder. B, Low-pressure cylinder. B', Steam receiver.
D, Valve chests.
u, Sole plate.
just noticed result in the most rigid connection being effected
between the fore and aft portions of the engine framing. Be-
tween the crankshaft bearings and the guide bars the frames have
cast on them horn-like brackets, through which pass stay bolts
carrying suitable distance pieces, thereby securing at this part
of the framing an amount of rigidity quite equal to that which
STATIONARY ENGINES.
293
exists in the anterior portion. Inside the main frames there are
fixed the slide bars, which are adjustable, top and bottom, for
the purpose of taking up the wear. The upper one is made plane
throughout, but the lower one is of a trough shape. They are
made of the best forged steel, as, indeed, are all the working parts
of the engines.
The high-pressure cylinders are each fitted with a liner, the
space between this and the cylinder casting proper forming a steam
jacket; the low-pressure cylinders, however, are not jacketted. At
their forward ends each of the low-pressure cylinders is solid, and is
provided with a bracketted flange where it is in contact with the
main frames; and connection between the frames and the cylinder
ends is effected by means of bolts, no studs being used.
The valves of these engines are of the double-piston type. The
steam ports in the valve casings have triangular openings into the
valve cylinders, the valve pistons having a 9½ inch stroke, and
being fitted with broad packing rings which are furnished with
cylindrical springs of a v shape. A tight-working piston is thereby
obtained, no escape of steam having been observed at any pressure
yet employed. The object aimed at in employing this type of
valve was to relieve the valve motion of the severe tear and wear
resulting from the use of unbalanced flat-faced valves.
The valve casings are placed on the sides of the cylinders in
order that they may be easily got at for inspection or in case of
repairs being necessary. The receiver formerly mentioned as inter-
vening between the high- and low-pressure cylinders of each engine
is immediately underneath the valve casings, and serves to catch
up any water that might otherwise enter the cylinders. The valve
spindles are of steel, and are jointed together by means of a box
coupling provided with cotters—an arrangement which allows of
the pistons and spindles being easily withdrawn for repairs and
replaced in position.
Steam is admitted into the high-pressure cylinder by the piston.
valve entering between the pistons of the valve, and exhausting at
each end into the receiver. The distribution of the steam into the
low-pressure cylinder is similarly effected by its valve, the steam
entering at the middle of the valve, and exhausting at each end as
before. On the top of the low-pressure valve casing there is placed
a small auxiliary slide valve, which is worked from the link motion
of the main valve, and is in direct communication with the steam
294
MODERN STEAM PRACTICE.
of full boiler pressure, so that in the event of the rolls failing at any
time to 'bite' when the ingot or bar in process of rolling is about
to enter, the driver can at once admit steam at full pressure direct
from the boilers upon the pistons in the low-pressure cylinders, and
turn it off instantaneously when the desired effect is accomplished.
The valve just referred to consists of a D-slide working on the face
of a grid plate having openings similar to the valve ports, and
serving the purpose of a shut-off valve as well as a slide valve. The
motion of this valve is governed by the general link motion of the
engines, thereby insuring that there shall never be any uncertainty
as to the admission of the steam pressure on the proper side of the
piston. Both high- and low-pressure cylinders are provided at each
end with spring escape valves.
The crankshaft, which weighs 10½ tons, is a fine steel forging,
and extends from the coupling to the mill to the right-hand engine,
or engine furthest from the mill.
The crankshaft bearings are 18 inches in diameter, as are also
the crank-pins.
The several levers by which the operation of starting, reversing,
&c., are controlled, are all within a few inches of each other, and
there is nothing to intercept the driver's view of what is going on
at the rolling mill, in front or in rear, or of the whole surface of the
engines. The engines are started and reversed by the aid of a small
steam cylinder provided with cataract regulation.
They
The engines we have been describing drive a 26-inch mill.
are worked with steam at 120 lbs. pressure, and are capable of
easily developing 3000 horse-power.
The steam for driving the engines we have been describing is
supplied by boilers of the locomotive type, these being three in
number.
The boilers have barrels 6 feet 2½ inches in diameter, and each
contains 336 tubes, 2½ inches in diameter by 12 feet long. The
tube surface in each boiler is thus 2640 square feet, while the firebox
surface is 171½ square feet and the firegrate area 30 square feet.
The fireboxes are each provided with a longitudinal mid-feather;
and in each case the roof of the inside firebox is stayed direct to
the casing by steel stays. The two front rows of these stays are
arranged with their upper ends in sockets, so as to allow for the
expansion and contraction of the tubeplate of the firebox. Arrange-
ments are made for a firebrick arch resting on angle-irons. No
STATIONARY ENGINES.
295
brick setting is required for the boilers, which are, instead, set on
cast-iron frames, which serve as stands on each side of the firebox
and smokebox, in this way again giving allowance for freedom of
motion during expansion and contraction. Each boiler is supplied
with a couple of Cockburn's 24 inch diameter open-flow pendulum
valves, each of which is loaded to a working pressure of 120 lbs. per
square inch. Prior to delivery the boilers were experimentally sub-
jected to a water pressure of 250 lbs. per square inch, while they
were also tried under steam to the pressure just mentioned They
have already proved themselves to be excellent steam raisers.
Practically the whole of the material of these boilers is steel; the
principal exception being that of the tubes, which are of iron.”1
THE CORLISS ENGINE.
An engine combining economy of working with a moderate first
cost must ever be of primary importance. The distribution of
steam effected by the ordinary slide valve actuated by the single
eccentric has, after long trial, been found to yield unsatisfactory
results; many ingenious improvements have been adopted, and
amongst these is the "Corliss" liberating valve gear, named after
the inventor.
The characteristic features which are common to all the forms of
liberating valve gear may be thus briefly stated:-The steam is cut
off almost instantaneously by the agency of some force suddenly
called into play, such as a falling weight or the recoil of a distended
spring, the cut-off being regulated to the amount of work the engine
has to perform directly by the controlling agency of the governor
and the cut-off gear. The Corliss engine has separate pairs of
steam and exhaust valves, or altogether four for each cylinder.
They are of the cylindrical type; the lower of them, or the exhaust
valves, are wrought directly from the eccentric by means of a disc
plate and levers connected with the valve spindles; they remain
open during the whole period of the stroke, and are not affected by
the cut-off gear. The steam valves are likewise wrought from the
disc plate by levers, which open the valves at first, and so distend
a steel spiral spring whilst the steam is being admitted, till on the
¹ For the description and plate we are indebted to Engineering, vol. xxvii.
296
MODERN STEAM PRACTICE.

lever reaching a certain position it is tripped up by a peculiarly-
Fig. 197.—The Corliss Engine.
Ja
STATIONARY ENGINES.
· 297
shaped toe-piece liberating the spring, which by its recoil instantly
closes the valve. To guard against the damage that might
possibly arise from the too violent impact of the spring, it is closed
in a dash pot or vessel, to which the air is admitted by small
holes, but prevented from escaping freely, and which forms a
cushion to check the impact of the spring and bring it gradually to
rest. The governor is connected with the cut-off gear by levers,
by which the point where the lever is tripped may be altered as the
cut-off requires to be hastened, or delayed according to the power
required from the engine. No throttle valve is therefore employed
to wire-draw the steam, and by a fall of pressure (involving a direct
loss of energy) to vary the power given out by the engine; but the
better expedient is adopted of supplying exactly the quantity of
steam required to perform the work. With what efficiency this
arrangement answers will be best gathered from the following
instance: In a spinning factory a cogged wheel was instantaneously
stripped, the resistance portion of the work which it drove was thus
suddenly removed; but so perfectly did the engine draw the reduced
quantity of steam that on examination not a single thread was
found to be broken. Pumping machinery also affords another
instance, as not even the breaking of a spear rod sensibly affects the
speed of the engine.
As has been already stated the Corliss engine has separate steam
and exhaust valves. Not to mention the good results in the work-
ing of the engines which are due to this arrangement, the separate
valves effect a direct economy, as each valve is kept at a constant
temperature, and the steam that enters through them directly from
the boiler is not cooled down as it would be if it entered through
the same passage by which the exhaust steam had previously
escaped, neither is the exhaust steam again re-heated by contact
with the hot steam valve; we have thus a direct saving of heat,
which in an ordinary slide-valve engine would be lost. The steam
lost by clearance when performing work is with these valves reduced
to a minimum. To test thoroughly the actual working of this
engine the indicator must be summoned to our assistance; and the
diagrams obtained from it will enable us to judge to what extent
the theoretical diagrams, or those that give the maximum amount
of power from a minimum consumption of steam, agree with those
realized in practice. The conditions necessary to insure the maxi-
mum of efficiency may be thus briefly stated: (1) The ports must
298
MODERN STEAM PRACTICE.

32
Vacuum 13 25 U
Atmospheric
DIAGRAMS
FROM
BEAM CONDENSING CORLISS ENGINE
Cylinder 24 ins × 4ft stroke indicating 63 HP when cutting off
BOTTOM SIDE
Line
at 1/8th
Atmospheric
TOP SIDE
40 25
33
23
75 80
12.80
BACK
Atmospheric
30
1
n
HORIZONTAL
35
15
6
Н
8
4
10 lbs Average Pressure
DIAGRAMS
FROM
MESS JAS NORMAND & SONS
CORLISS ENGINE.
DYSART.
6 25
45
76 36 Ubs
Average Pressure
Average Pressure lbs 905
6
8
71
14.5
NON-CONDENSING
75
3
18.5
25 5
38 5
42.5
17 75 lbs
Average Pressure!
Line
Inutial. Pressure 29 5 lbs
FRONT
Line
325
25
73.5
85
Glinder 18 vr 4ft Revols 50p.min Steam in Boiler 35lbs Engine driving 106 Looms and preparing Horse Power 29.25
Figs. 198 and 199.
Trabal Pressure 33 lhs


be fully open during the whole period for the admission of steam.
STATIONARY ENGINES.
299
(2) The cut-off must be rapid. (3) The back pressure must be a
minimum. (4) The steam must be admitted into the cylinder at
its full boiler pressure until the point of cut-off is reached. In the
Corliss diagrams these conditions are strictly fulfilled. The admis-
sion of steam is indicated by a nearly perpendicular line, Figs. 198
and 199, and the cut-off must, with the means employed, be practi-
cally instantaneous. The diagrams exhibit a remarkably small back
pressure; this result, along with the constancy of pressure main-
tained until the point of cut-off is reached, is accounted for by the
large area that can be given to the steam and exhaust passages, as
the valves employed are of the whole breadth of the cylinder.
In ordinary engines a large expenditure of power is required to
move the valves; this loss of power is saved in the Corliss engine,
as one man with an ordinary starting bar can move the valves of
a 1000 horse-power engine against the full pressure of steam.
every part of the engine is readily open to inspection, no difficulty
is experienced in examination, and repair of any of the parts
requiring it; but in practice the wear is found to be very slight.
The Corliss engine is economical in the matter of fuel, its con-
sumption being at the rate of 2½ lbs. per horse power per hour, as
proved by experiment, a result that must go far to recommend it
to the favourable notice of manufacturers requiring steam-power.
1
HIGH AND LOW PRESSURE COMBINED BEAM
ENGINE.
The high and low pressure combined beam engine is much used
where great regularity of motion is required, more especially for
driving spinning machinery. This regularity of motion is due to
the steam expanding from the top of the high-pressure to the
bottom of the low-pressure cylinders, and vice versa, by which the
jerk at the commencement of the stroke of the piston is not so
much felt as in ordinary engines receiving the full force of the
steam on one side of the piston. The example illustrated, Fig. 200, ·
consists of a pair of engines, coupled at right angles, for driving the
machinery at the Royal Gun Factory at Woolwich. The diameter
of the fly wheel is 22 feet at the pitch line, the breadth of the teeth
12 inches, and the pitch 3 inches, gearing into a pinion 4 feet
6 inches in diameter.
300
MODERN STEAM PRACTICE.
Speed of the engine shaft....
Do.
Do.
second shaft
third shaft.......
21 revolutions per minute.
102
150
""
The total length of the shafting is about 932 feet, in parallel lengths,
the diameter of the pinion shaft being 8 inches, and that of the

Ꮐ
F
B
E
D
M
H
Concrete
Fig. 200.-High and Low Pressure Combined Beam Engines of 80 horse-power collectively.
A, High-pressure cylinder. B, Low-pressure cylinder. c, Condenser and cistern. D, Cold-water
pump. E, Governor and feed-pump rod. F, Spring beam. G, Main beam. H, Crank
shaft. I, Pinion shaft. K, Entablature. L, Columns. M, Stone pedestal. N, Foundation.
smaller line of shafting 3 inches at the end. The diameter of each
high-pressure cylinder is 15½ inches, stroke of piston 4 feet 6 inches;
and the diameter of each low-pressure cylinder is 31 inches, with a
piston stroke of 6 feet. The valve mechanism for those engines has
already been described, p. 102, Fig. 51. The diameter of each air
pump is 21 inches, with a stroke of bucket of 3 feet. The crank
shaft is of cast iron, the journals being 10 inches in diameter and
15 inches long, and the crank pins 5½ inches in diameter and
7½ inches long. There are three large boilers, 35 feet long and
7 feet in diameter, with two inside furnaces, and flues running the
entire length, 2 feet 6 inches in diameter, with return wheel flues of
brickwork. The steam pressure is 40 lbs. per square inch, and the
thickness of the plates is as follows:-
Shell.....
Ends....
½ inch thick.
5/%
""
Flues..
Rivets..
3/8 inch thick.
3/4 inch in diameter.
STATIONARY ENGINES.
301
RULES FOR PUMPING ENGINES.
Horse-power. The standard fixed upon to represent the work
of one horse is 33,000 lbs. raised I foot high in one minute. To
find the horse-power, the quantity of water to be raised is reduced
to lbs. and multiplied by the height in feet, and the product divided
by 33,000 expresses the horse-power. A gallon of water weighs
exactly 10 lbs., thus any number of gallons can be expressed in
lbs. by adding a cipher. Hence the following formula:
Gallons to be raised per minute x 10x height = horse-power.
33000
But in practice about one-fifth must be added for the friction of the
engine. Examples:-
Supposing 1000 gallons of water per minute is required to be
pumped through a line of piping to a height of 120 feet, and the
allowance made for the friction in the pipes is equivalent to a head
of water of 150 feet: required the horse-power. Thus we have-
Gals. per minute. Lbs. Height in feet.
1000 X ΙΟ × 150 =
33000
45.45
to which add th for the friction of the engine
9'09
54 54 horse-power.
Again, supposing 1,440,000 gallons of water is required to be
pumped up in the 24 hours the same height, we have-
Lbs. raised
I foot high per
Gals. in 24 hours. Lbs. Height. minute = H.P.
mins. hours.
1,440,000 × 10 x 150 ÷ 33000 × (60 x 24)
45'45
adding as before th for friction of the engine………………….
9'09
54'54 horse-power.
Another method gives the horse-power as follows:-
Gals. in 24 hours. Height.
Constant.
1,440,000 × 150 ÷ 4,752,000 = 45'45
*th added = 9.09
54°54 horse-power.
Supposing the quantity is given in cubic feet to be delivered in
the 24 hours, at the same height as before, we have—
302
Weight
MODERN STEAM PRACTICE.
Cubic feet of a cubic Height
in 24 hours. foot in lbs. in feet.
230,400 × 62.5 × 150
mins.
hours.
Lbs. raised
1 foot high per
minute = H. P.
÷ 33000 × (60 × 24) = 45°45
th added...
9'09
54 54 horse-power.
The power required to raise water to any height is as the weight
and velocity of the water. Hence the following rule: Multiply the
perpendicular height of the water in feet by the velocity in feet, by
the square of the pump's diameter in inches, and then by 341 (the
weight of a column of fresh water I inch in diameter and 12 inches
in height), dividing the product by 33,000; the quotient gives
the horse-power, to which must be added one-fifth for friction,
and say one-fifth for loss, or two-fifths in all. For water-works'
engines 20 per cent. is allowed for friction, &c., and about 50 per
cent. for contingencies, making a total of 70 per cent. additional
power.
When the diameter of the pump and velocity of the water are
given, to find the quantity discharged in gallons or cubic feet in
any given time. Multiply the velocity of the water in feet per
minute by the square of the pump's diameter in inches, and by
034 for imperial gallons, or 005454 for cubic feet, and the product
will be the number of gallons or cubic feet discharged in the time
nearly.
When the length of stroke and the number of strokes are given,
to find the diameter of the pump and the horse-power that will
pump or discharge a given quantity of water in a given time. First,
multiply the number of imperial gallons of water to be discharged
in the given time by 353, or the number of cubic feet by 2201, and
divide the product by the velocity of the water in inches; the
square root of the quotient will be the pump's diameter in inches.
Second, multiply the number of gallons per minute by 10, or the
number of cubic feet by 62'5, and by the perpendicular height of
the water in feet, divide the product by 33,000, then add 4th to the
quotient, which will give the horse-power required. Example:-
Supposing 3,000,000 gallons of water is required in the 24 hours,
the stroke being 10 feet, making 12 strokes per minute-
Gals. in the 24 hours. mins.
3,000,000 ÷ 1440 = 2083 gallons per minute.
Strokes
Constant. Stroke. per min.
*03409 × 10 ×
10 X 12 = 4'09 divisor.
STATIONARY ENGINES.
303
Gals. per min.
2083
4'09
√ 509°2, the square root of which is 22.6 inches, the diameter of the pump.
One-fourth more than the above is usually allowed for waste.
Again, supposing the number of gallons per minute is required—
Constant.
Square of the
Strokes
pump's dia. Stroke. per min.
*03409 × 509°2 X ΙΟ X 12 =
To find the stroke of a pump:—
Square of the Strokes
2083 gallons per minute nearly.
Constant.
pump's dia.
*03409 X 509°2 X
per min.
I2
208.2 divisor.
Gals. per min.
2083 =
208.2
10 feet stroke of pump nearly.
Pumping water out of floating and other docks. Given the
quantity in tons of sea water (35 cubic feet to the ton), the height
to which it is raised, and the time in hours that is allowed to dis-
charge it, to find the horse-power. Divide the quantity in tons by
the number of hours, which gives the quantity to discharge per
hour, and this divided by 60 gives the quantity to discharge per
minute; then take 147 as the third divisor (147 tons=33,000 lbs.,
the weight raised I foot high per minute), which gives the horse-
power required to raise the total quantity I foot high: multiply
this sum by the height at which the water is discharged, and the
quotient is the horse-power required to discharge the whole amount
in the given time,--to which must be added the loss from friction
and waste.
To find the diameter of pump required to discharge a given
number of tons of sea-water in a given time, with a certain velocity
(the usual speed of pump bucket being 160 feet per minute). Mul-
tiply the quantity by the constant 35, and divide the product by
the speed multiplied by the time in hours, and then by 60 for
minutes; the quotient is the pump area in square feet, which can
be subdivided by the number of pumps that are adopted.
Method for finding the horse-power of single-acting pumping
engines. Thus supposing the water is pumped into an air vessel
to a height of 252 feet, and making an allowance for the friction in
the pipe—say a total height of 285 feet-the diameter of the plunger
being 23 inches and the stroke 10 feet, making 10 strokes per
minute, we have as follows:
304
MODERN STEAM PRACTICE,
Diameter of the plunger, 23 inches
Area in sq. feet.
= 2
2.8852
Weight in lbs. of
Plunger area. Lift in feet. I cubic ft.
2·8852 × 285 X 62.5
lbs.
51392
Now allowing th to overcome the load on the air pump and the
friction of the engine, we have:
D2
Load on the Length of Strokes
piston in lbs.
stroke. per minute.
61670 × ΙΟ X 10
and
6167000
33000
6167000
= 186 horse-power nearly.
Approximate rule for power of Cornish engine.—A simple rule used
by some engineers for calculating the quantity of water delivered from
a given pump is as follows:-Let D=the diameter of the pump, then
30 represents the quantity of water in gallons delivered per I foot
stroke of pump nearly. Let S the speed of the plunger of bucket
per minute, then S
the number of gallons delivered per minute.
Let Lthe lift in feet, and the horse-power will be thus obtained:
L 10
D2
30
(s). The following is an example:-Diameter of pump
33000
=16, stroke of pump-75, number of strokes per minute=7'5,
lift 190 fathoms 1140 feet.
=
=
Diameter of pump.
16 × 16
30
Speed.
= 8·5 × (7·5 × 7*5) = 478 gallons per minute.
The work done =
1140 × 10 × 478
33000
= 165 horse-power nearly.
This rule evidently allows for waste in the pump, but one-fifth
must be added to the sum for the friction of the engine.
To find the area of cylinder required to perform a given amount
of work. We may consider the mean pressure in the cylinder as
from 14 to 15 lbs. per square inch, and the velocity of the piston
from 80 to 85 feet per minute. It must be remembered that the
pressure per square inch is derived from the actual water load
divided by the area of the piston, and that one-fifth more power
must be allowed for friction. Thus the pressure multiplied by the
velocity equals so many foot pounds, which may be taken on an
average as 1000.
Therefore we divide the number of lbs. of water
raised I foot high by 1000, and the quotient is the area of the
cylinder in square inches. For example:-Suppose it be required
STATIONARY ENGINES.
305
to find the diameter of a cylinder of a Cornish engine sufficient to
raise 7,000,000 gallons of water 120 feet high in 24 hours. Multi-
ply the number of gallons by 10 (the weight in lbs. of a gallon of
fresh water), and then by the height; divide the product by the
number of hours reduced to minutes, and the quotient gives the
number of lbs. raised 1 foot high per minute, which divided by 1000
gives the area of the cylinder. Thus:
7000000 X 10 X 120
1440
= 5833333÷ 1000 = 5833,
which equals 86 inches diameter nearly; to which must be added
an allowance for the friction of the engine. The divisor used may
vary, owing to the pressure and velocity, and on this account three
eminent firms have used in their practice 926, 1113, and 1140
respectively; but the average of a number of Cornish engines
is 771.
Steam valves for Cornish engine:—
The steam valves..
The equilibrium valves......
The exhaust valves.......
=th toth of the cylinder area.
3th to th
=th to th
""
To find the duty of an engine.—Supposing an engine required
3 lbs. of coal per indicated horse-power per hour, it is required to
find the duty performed by 112 lbs., or a cwt. of coal. The horse-
power being 33,000 lbs. raised I foot high in a minute, or 1,980,000
lbs. raised I foot high in an hour-then by the rule of three we have
lbs.
lbs.
lbs.
lbs.
3:1980000 :: 112 = 73920000
raised I foot high by a cwt. of coal per hour. Formerly the duty
was estimated by the bushel of coal, weighing 94 lbs., but it is
considered most convenient to adopt the 112 lbs. measure. The
average duty of Cornish engines may be taken at 60,000,000 lbs.
raised I foot high in one hour by a bushel of coal weighing 94 lbs.,
or 71,489,361 lbs. with a cwt. or 112 lbs.
The power required to overcome the friction of water through pipes.
-When water is required to be pumped through a long line of
piping an allowance is generally made for its friction in transit. The
quantity of water in cubic feet per minute, and the diameter and
length of the line of piping being given, multiply the square of the
quantity in cubic feet by the length of the piping in feet, and divide
the product by the constant 22 for pumping engine, multiplied by
the fifth power of the diameter of the piping. Thus, supposing
20
306
MODERN STEAM PRACTICE.
61 cubic feet of water requires to be forced to a height of 178 feet,
the length of the piping being 8145 feet and the diameter of the
pipe 9 inches, we have-
Cubic feet.
Length of piping.
61 × 61 = 3721 × 8145 = 30307505
22 × (9× 9 × 9 × 9 × 9) = 1299078
= 23.2 feet,
as the additional height to be allowed for the friction, or say 24 feet
in round numbers; thus 24 feet added to the height the water
requires to be pumped equals 202 feet: then calculate the horse-
power by the ordinary method, namely:
Cubic
feet.
Weight of a
Height. cubic foot.
61 × 202 × 62'5
33000
= 23°3 horse-power,
to which add one-fourth for loss, and the product is 29 horse-power
nearly, irrespective of the friction of the engine.
Formula to find the extra height to allow for friction according
to the above:-
H=
Q² 1
22 dō
where Q is the quantity in cubic feet per minute, / the length of
the line of piping, and d the diameter of the pipes.
Formula to find the horse-power required to overcome the friction:
Q³ 1
P =
140 d5
P represents the horse-power necessary to overcome the friction,
the length of the pipe in inches, Q the quantity of water to be
delivered in one second in gallons, and d the diameter of the pipe
in inches. The formula reads, that the cube of the quantity in
gallons per second must be multiplied by the length of the line of
piping in inches, dividing the product by the constant 140 multi-
plied by the diameter of the piping into the fifth power.
Delivery of water in pipes.—The formula is:
VD5
W = 4'72
H
D='538
Lx W2
H
where D equals the diameter of the pipes in inches, H the head of
water in feet, L the length of pipe in feet, and W the cubic feet of
water discharged in a minute.
Hawksley's formula.—This formula is:
D =
1
5 G2 L
H
G =
(15 D)5 H
L
STATIONARY ENGINES.
307
where G equals the number of gallons delivered in an hour, L the
length of pipe in yards, H the head of water in feet, and D the
diameter of pipe in inches.
Weight and measurement of water:
I cubic foot..
I cubic inch
I gallon..
A column 12 inches high and 1 inch square…..
A column 12 inches high and 1 inch diameter
A cylindrical foot.....
A cylindrical inch..
II.2 imperial gallons
224 imperial gallons..
1.8 cubic feet..
35.84 cubic feet.
I cubic foot.
62.5
*03617
= 10*
*434
*341
= 49'I
*02848
= I cwt.
= I ton.
= I cwt.
lbs. avoirdupois.
""
35
I cylindrical foot.
= I ton.
=
64 imperial gallons.
= 5
""
To find the thickness of pipes for conveying water.-Multiply the
constant 000054 by the head of water in feet, and then by the
inside diameter of the pipe in inches, to which add 3% inch for
pipes less than 12 inches, ½ inch from 12 to 30 inches, and 5% inch
from 30 to 50 inches internal diameter, and the result gives the
thickness. Thus, supposing the head of water was 600 feet and
inside diameter of the pipe 15 inches,
*000054 × 600 × 15 = 000°486000 + *5 = '98,
or nearly 1 inch as the thickness.
PROPORTIONS OF SOCKET FOR STANDARD PIPES FOR WATER SUPPLY.

Internal Dia-
meter.
Thickness.
Depth of
Socket.
Thickness of
Socket.
Space for
Packing.
inches.
inch.
inches.
inch.
inch.
5
6
7
mtio N∞
3
16
3/1/2
4
16
3/31/1
32
HOH20HDIE SOI-HODITH
120
9
16
7
16
7
16
7
16
IO
3
7
9
16
4
4
4
ခ
4
4
11
16
1 1
16
I I
I2
14
To find the weight of cast-iron pipes.—To find the weight of a
lineal foot, square the outside and inside diameters, and find the
difference, then multiply the result by 2:45 lbs., which is the weight
of a circular bar 1 inch diameter and I foot long. Supposing the
pipe is 22 inches diameter outside and 20 inches diameter inside,
308
MODERN STEAM PRACTICE.
(22 × 22) = 484 – (20 × 20) = 400 = 84 × 2°45 = 205·8 lbs. nearly.
Two flanges are generally reckoned equal to 1 foot of pipe.
Pipes for pit pumps.-The most approved form of joint for pit or
pump stand pipes is the spigot and faucet, with a turned face on
the flanges for making the joint, which is done by a ring of wrought

ㅁ
​E
B
H

A
K
F

F
Fig. 200 A.-Pipes for Pit Pumps.
A, Bottom pipe. в, Top pipe. c, Spigot. D, Faucet. E, Ring of wrought iron. F, Flange.
G, Brackets. H, Bolt and nut. 1, Holes. K, Faces for joint.
iron covered with plaiding steeped in tar, and securely bolted
together by means of the flanges and bolts. The spigot is accur-
ately turned a little less in diameter than the faucet, which is
bored out for its reception. The flanges are strongly bracketed
to the body of the pipe, and the holes for the bolts are made
slightly oblong. The length of the pipe is generally about 9 feet
over the flanges, and the body is strengthened with two or more
raised rings cast on.
STATIONARY ENGINES.
309
Horse-power of an engine.-The horse-power of a condensing
beam engine may be found theoretically by calculating the mean
pressure taken from the steam pressure adopted and the point of
cut-off determined on, allowing 12 lbs. per square inch as the amount
to be derived from the vacuum. Hence,
Area of cylinder in sq. in. x total pressure per sq. in. x velocity of piston in feet per minute
33000
gives the horse-power the engine will work up to, adding to this an
allowance of about one-fifth for friction.
Diameter of cylinder and length of stroke.—To find the diameter
of cylinder for a given horse-power, we must first find the number
of square inches to the horse-power, at the speed determined on,
by dividing the constant 33,000 by the total pressure (adding one-
fifth for friction) multiplied by the velocity of the piston in feet per
minute.
Thus,
33000
Total pressure x velocity of piston in feet per minute
and the product multiplied by the total horse-power will give the
full area of the cylinder in square inches. Where great exactness
is required, add one-half of the area of the piston rod, then by the
table of areas the diameter is easily ascertained. The stroke of the
piston ranges from 2 to 22½ times the diameter of the cylinder.
Speed of piston (varying with the stroke):-
2 ft. 0 in. stroke = 160 feet per minute. 4 ft. 6 in. stroke=207 feet per minute.
22334
6
""
O
=170
=180
""
""
""
6
""
=189
=200
""
""
4567∞
""
=215
=228
""
""
""
=245
""
""
=256
Opening of port by valve.—The opening of the port by the valve
is found by multiplying the area of the cylinder in square inches
by the speed in feet per minute, dividing the product by the con-
stant 10,000. The port should be made in excess of this, so as to
give a free exhaust; the breadth depends on the length of the port,
one-twentieth of the area of the cylinder may be allowed in all
For the exhaust port multiply the area of the supply port
by 1.5, and for the length of port multiply the diameter of the
cylinder by '6.
cases.
310
MODERN STEAM PRACTICE.
RULES FOR THE BEAM ENGINE.
The beam. The length of the beam should not be less than
three times that of the stroke, and its breadth one-half of the stroke;
for the breadth at the ends multiply the breadth at the middle by 4.
To find the thickness of web at the centre multiply the total pres-
sure on the piston-i.e., steam and vacuum-by one-half of the
length of the beam in inches, and divide the result by the constant
500 into the depth in inches; the quotient is the sectional area in
square inches for cast iron.
Wrought-iron tubular beams:-
1 = length....
d = depth..
a = area of bottom flanges..
C = constant...
W = breaking weight in tons; hence
W = 56·67 × 5·5 × 80
W=
28.66
= 870 tons,
28 feet 8 inches.
6,
56.67 square inches.
80
5,,
as the breaking weight in the middle. The load on the beam being
from 85 to 90 tons, we may safely consider the ratios of strength
as 870: 90, or nearly 10 to 1. The thickness of sides for a beam of
the above dimensions is 3% inch, supported between the flanges
with T-iron over the joints, and corresponding strips outside; upper
and lower webs or flanges 2 feet wide, with four plates in each,
3/4 inch thick, rivetted to the sides with double angle iron. The
centre boss is cast with a plate, which is rivetted to the sides; the
end and intermediate bosses have also cast-iron plates. Instead of
the box form of beam, the side plates are sometimes made of
sufficient strength, having no angle irons at the top or bottom, but
merely secured with bolts and nuts, and sometimes rivetted to the
cast-iron bosses. The diameter of the main gudgeon is generally
one-fourth of the diameter of the cylinder, and for the piston-rod
gudgeon divide the cylinder diameter by 6·5; or they may be cal-
culated taking them as round beams loaded in the middle.
To find the versed sine described by the beam of an engine.—Divid-
ing the square of the stroke of the engine by 8, multiplied by the
radius of the beam, gives the versed sine nearly, viz., S²÷ (8 × R)=
versed sine.
Air pump and condenser.—The air pump has generally a stroke
STATIONARY ENGINES.
311
of one-half of the travel of the steam piston. To find its cubical
contents, divide the cubical contents of the steam cylinder by 4'3.
When the stroke of the pump equals one-half that of the steam
piston, to find the diameter of the pump, in usual cases, multiply
the diameter of the cylinder by 7. The cubical contents of the
condenser should be about twice the capacity of the air-pump.
The
Cold-water pump and injection water.—To determine the size of
the cold-water pump we must first ascertain the quantity of water
required for condensation. This is found by multiplying the tem-
perature of the steam by '0034; or approximately 0.8 cubic foot, or
5 gallons, are required per nominal horse-power. Multiply this
number by the nominal horse-power of the engine, and then by the
constant 2200; divide the result by the velocity of the pump bucket
in inches per minute, and the square root of the quotient is the
diameter of the pump. When the stroke of the pump is one-half
of that of the steam piston, the usual diameter allowed for the pump
is found by multiplying the diameter of the cylinder by 0'3.
area in square inches of the injection valve should be from
th the number of cubic feet in the steam cylinder.
The feed pump.-To find the water required to be delivered by
the pump, multiply the cubic contents in feet of steam in the
cylinder for an entire revolution by the number given in the table
of cubic inches of water required to raise a cubic foot of steam at
the desired pressure, and the result will give the contents of a
single-acting pump in cubic inches; a little more may be allowed
for waste, &c., but when the steam is cut off soon in the cylinder
no additional allowance will be required.
TABLE OF THE PROPORTION OF WATER TO STEAM.
Pressure of steam
per square inch.
Cubic inches of water
in a cubic foot of steam.
I'099
I 350
1.658
Pressure of steam
per square inch.
th to
Cubic inches of water
in a cubic foot of steam.
3'700
3'981
4*256
4'535
TTTT
2.258
2.552
2.842
3°130
3'415
4.812
5:052
5°317
5.650
The diameter of the valves is found by multiplying the diameter of
the plunger by 0·6.
Piston rod and connecting rod.-To find the diameter of the piston
rod for compressive strain, multiply the area of the cylinder by
312
MODERN STEAM PRACTICE.
the steam pressure, and divide by 2240, which gives the area of the
rod; and for tensional strain divide by 4000, which gives the area
at the weakest part. These proportions will be sufficient for all
the parts subjected to direct strain. The area of the connecting
rod straps equals the area of the piston rod; the thickness of the
strap at the keyways must be more according to the area cut out
for the key. The depth of jib and cotter equals two-thirds of the
diameter of the connecting rod at the ends; the thickness of the
jibs and keys equals one-fourth of the rod at the ends; taper of the
key equals ½ inch to the foot; keyway from end of butt equals the
breadth of the jibs and cotters.
Crank shaft.-To find the diameter of the crank shaft when
made of wrought iron, multiply the length of the crank in inches
from centre to centre by the total pressure on the piston, and divide
the sum by 1206; the cube root of the quotient will be the diameter
of the shaft.
Crank of wrought iron.-The diameter of the crank pin will be
found by multiplying the diameter of the cylinder by 16; for the
length of the pin, multiply the diameter of the cylinder by 22.
The diameter of the eye for the crank pin is twice the diameter of
the pin. The length of the boss at the shaft is equal to the diameter
of the shaft; and for the thickness of the metal around the shaft
multiply the diameter of the shaft by 37. The breadth of the web
at the crank-pin end and journal is three-fourths of the diameter of
the respective bosses, and its thickness is five-eighths of their width.
These proportions are for low-pressure engines, with a steam pres-
sure of 30 lbs. or so per square inch.
Crank of cast iron.—The diameter of the crank pin is the same
as for wrought iron, and also the length of the pin. The diameter
of the eye for the crank pin is two-and-one-half times the diameter
of the pin. The length of the boss at the shaft equals the diameter
of the shaft, and its diameter is twice the diameter of the shaft.
The breadth of the web at the crank pin and journal bosses is
three-fourths of the diameter of the respective bosses, and its thick-
ness is one-half of the diameter of the shaft, with a feather at the
back tapering from the large boss to the crank-pin boss, in thick-
ness one-half of that of the web.
Fly wheel. The diameter of the fly wheel is generally from three-
and-a-half to four times that of the stroke of the engine. The
velocity of the periphery should always exceed the velocity of the
STATIONARY ENGINES.
313
periphery of the stones of a flour or other mill, to prevent back
lash. To find the weight of the rim in cwts. multiply the constant
1366 by the horse-power of the engine, and divide the product by
the mean diameter multiplied by the number of revolutions per
minute, and the quotient is the weight. To find the thickness of
the ring when the breadth is given, in the first place find the area
of the ring in square inches, then divide the weight in lbs. by the
area multiplied by 263, and the quotient is the thickness in inches.
The breadth of the rim for large wheels is generally 4th of the
diameter of the wheel, toth for small wheels.
24
The governor.-The point of suspension of the arms should be
as near the centre of rotation as possible, and the working angle
should never exceed 45°; the diameter of the balls varies from
4 to 9 inches. To find the number of revolutions, divide 375 by
the square root of the pendulum, or vertical distance from the point
of suspension to the working plane of the centre of the balls, and
one-half of the quotient will be the number of revolutions required.
When the revolutions are given, to find the length of the pendulum.
Divide 375 by twice the number of revolutions per minute, and the
square root of the quotient will be the length required; or other-
wise, divide the constant 187.5 by the square root of the pendulum,
which will give the number of revolutions. Thus, supposing the ver-
tical height is 36 inches, the square root = 6 inches, we have—
187.5
6
= 31.25 revolutions.
Given the number of revolutions, to find the length of the pendulum
from the centre of the working plane of the balls to the centre of
suspension. Divide 187.5 by the number of revolutions, and the
square of the quotient will be the length of the pendulum:
187.5 = 6²= 36 inches long.
3125
Formula for safety-valve levers:-
(1)
Weight or pressure on the valve x distance of valve from stud
Total length of lever from stud
Weight or pressure on the valve x distance of valve from stud
(2)
(3)
Weight
Weight on lever × total length of lever from stud
Distance of valve from stud
= weight.
= total length of lever.
= total pressure on valve.
314
MODERN STEAM PRACTICE.
This is when the valve is between the stud or pin and the weight
on lever. When great exactness is required, subtract the weight

4.... 32. F
C
31/2
B
32-
"
Fig. 2008.-Safety Valve, with Lever and Weight.
A, Stud. B, Weight. C, Valve.
of valve and the effective leverage or weight of lever from the total
(steam lbs.) pressure on the valve. Examples:-
Supposing the pressure of the steam in the boiler is 30 lbs. per
square inch above the pressure of the atmosphere, giving a total of
288.61 lbs. on the valve-and the length from A to B is 35 inches,
and from A to C 3½ inches-we have,
288.6 × 3°5
AB=35
288.6 x 3.5
B=28.86
28.86 × 35
AC=3'5
weight on B = say 28.86 lbs.,
=B from A= say 35 inches,
= total pressure on the valve = 288.6 lbs.,
which gives the total load on the valve; to be more accurate, the
weight of the valve and the effective leverage must be subtracted
from 288.6, the total (steam lbs.) pressure on the valve.
WATER-PRESSURE ENGINES.
In 1846 the first hydraulic crane was erected at Newcastle-on-
Tyne, for discharging ships, the supply of water being obtained
from the mains connected with the town service reservoirs. After-
wards one was erected at Liverpool, and another at the new dock
at Grimsby. The Liverpool crane, like the Newcastle one, was
supplied with water from the town mains; but at Grimsby a tower
was built with a tank into which the water was pumped by a steam
engine. In the former cases the irregularity of pressure consequent
STATIONARY ENGINES.
315
on the varying drain upon the pipes for the ordinary consumption
proved a serious disadvantage; but this drawback was not experi-
enced at Grimsby, where the tank upon the tower furnished an
uninterrupted supply. In the absence of a natural head of water,
with pipes laid for conveying it to a lower situation, the erection of
water towers was a serious obstacle in extending the principle of
the hydraulic crane, and engineering ingenuity resorted to another
form of head, which possesses the advantages of being applicable
at a moderate cost in nearly all situations, and of lessening the
size of the pipes and cylinders by affording a pressure of greatly
increased intensity. The apparatus by which this is effected has
been named the "accumulator," because of its accumulating the
power exerted by the engine in charging it. The accumulator is
in fact a reservoir giving pressure by load instead of by elevation,
and its use is to equalize the duty of the engine in cases where the
quantity of power to be supplied is subject to great and sudden
fluctuations. In the application of water-pressure machinery, where
an artificial head of water has to be obtained, the real source of
power is the steam engine employed in pumping the water into the
accumulator, and the water acts simply as a convenient means of
storing up the power of the engine, and applying it whenever
wanted at the distant points where the work has to be done. We
may take as an example of this the Victoria Docks in London,
where the area over which the power is extended is so great as to
require 4 miles' length of mains to convey the water to the several
cranes, hoists, and to the lock-gates.
In Hastie's variable water-power engine the quantity of water is
regulated to the work done automatically. There are two or more
oscillating cylinders rocking on trunnions at their lower ends, the
pistons being solid plungers, and centered on a crank pin which is
free to move in a slide, so that the throw becomes variable according
to the demand on the engine.
THE ACCUMULATOR.
The accumulator consists of a large cast-iron cylinder A (Fig. 201),
fitted with a plunger B, from which a loaded case C is suspended to
give pressure to the water injected by the engine. The load upon the
plunger B is usually such as to produce a pressure in the cylinder
equal to a column of water 1500 feet in height, and the cylinder is
316
MODERN STEAM PRACTICE.
made large enough to contain the quantity of water which can be
required from it at once by the simultaneous action of all the
hydraulic machines connected with it. If, how-
ever, the engine pumps more water into the
accumulator than the hydraulic machines re-
quire, the plunger rises and makes room in the
cylinder for the surplus; and when, on the other
hand, the supply from the engine is less than
the quantity required, the plunger with its load
descends and makes up the deficiency out of
the store. The accumulator serves also as a
regulator to the engine, for when the plunger
rises to a certain height it begins to close the
throttle valve in the steam pipe, so as gradually
to reduce the speed of the engine, until the
descent of the plunger again requires an increase
of power. The introduction of the accumulator
removed all the obstacles to the extension of
water-pressure machinery, which has been now
practically tested in nearly all the principal
docks and in many of the government establish-
ments in this country. This class of machinery
has also been adopted in many of the principal
railway stations, not only for cranage, but also
for working turntables, traversing machines,
waggon-lifts, hauling machines, &c. It is also extensively used for
raising and tipping waggons in the shipment of coal, for opening
and closing bridges, and for many other purposes.

Fig. 201.—Vertical Section of
Accumulator.-4, Cylinder.
B, Plunger. c, Loaded case.
PUMPING ENGINE FOR CHARGING THE ACCUMULATOR.
The most approved form of the pumping engine for charging
the accumulator is that of two high-pressure cylinders fixed hori-
zontally, with double-acting pumps directly connected with the
piston rods; the form of pump being the solid bucket and plunger
system. In the arrangement shown (Fig. 202) the OUT stroke of the
pump forces the water contained in the annular space surrounding
the plunger E into the accumulator, while a further supply of water
enters behind the piston F through the suction valve G. In the
IN stroke the water behind the piston is discharged through the
STATIONARY ENGINES.
317
delivery valve D, half of it passing round into the annular space on
the other side of the piston, the remaining half being forced into
the accumulator. As the area of the plunger E is exactly half that
of the piston F, each stroke of the pump delivers the same quantity
of water into the accumulator. Much difficulty has been experi-
enced to secure proper joints for the pipes of hydraulic machinery;
no plan appears to stand so well as a small ring of gutta percha,

Joint at J.
E
HINA
J
Fig. 202.-Longitudinal Section of Force Pump.
D, Delivery valve. E, Plunger. F, Piston. G, Suction valve. J, Gutta-percha ring joint.
compressed into a recess formed on the end of one pipe, with a
projection on the adjoining pipe accurately turned to fit the recess,
like a spigot and faucet.
Rivetting, both of boilers, girders, and shipwork, is now in many
cases carried out by hydraulic pressure through the action of
accumulators, loaded as high in some cases as 1500 lbs. per square
inch, india rubber or flexibly jointed metal pipes being used to
convey the water to the working parts.
WATER WHEELS.
Water wheels may be classed as vertical and horizontal, of
these the vertical class may be subdivided into undershot, overshot,
and breast wheels, whilst the turbine form represents the horizontal
class. The undershot wheel is simply the old form of water wheel,
made of wood, with radial float-boards, on which the water
presses as it flows past. The efficiency or ratio of the useful to the
total work is small in such wheels, being only about. In the over-
shot or breast wheel the water is led on at or near the top, and the
floats are made of a bucket form; the weight of the water is in
this manner taken advantage of as well as the impulse due to velo-
city. The efficiency of such wheels is about to
10
в
4.
The turbine form of wheel is very suitable for high falls where a
great velocity of flow can be obtained, and is not affected by "back-
318
MODERN STEAM PRACTICE.
water" as the vertical wheels are. There are several forms of such
wheels, depending upon the direction in which the water is allowed
to impinge upon the vanes or blades. These vanes are curved, and
it is of importance that the water should be directed upon them in
such a manner as to cause as little shock as possible; the propelling
action being due to the pressure and reaction on the vane due to the
gliding of the water along its surface. Curved vanes are found in
this manner to be more efficient than flat surfaces, their surfaces
being in the direction of the resultant of the lines of motion of the
jet and vane. Turbines are now largely used on natural falls,
notably so in America and in France and Switzerland.
HYDRAULIC CRANE.
Of the various applications of water pressure, the most com-
mon is that of a hydraulic press with a set of sheaves used in the
inverted order of blocks and pulleys, with the object of obtaining
an extended motion in the chain from a comparatively short stroke
of piston. The general arrangement of the machinery for working
such a crane may be described as follows:-The pressure cylinder A
(Fig. 203) is fixed horizontally below the surface of the ground in a
chamber at the foot of the crane, and is fitted with the ram B, carry-
ing the pulleys C at its outer extremity. The lifting chain is made
fast at one end to the cylinder A, and passes alternately round the
movable pulleys C and the pulleys D at the inner end of the cylinder;
and is then led round the guide pulley E up to the crane post F,
and along the jib to the load. The motion of the lifting chain is con-
trolled by means of the handle G, acting upon the inlet and outlet
valves, which are kept closed by the weights H and I; by opening
the inlet valve H (Fig. 204) the water is let into the cylinder A from
the pressure pipe J, and acting on the plunger raises the load; by
opening the outlet valve I the water escapes from the cylinder into
the exhaust pipe K, allowing the load to descend. The travel of
the ram B in the outward stroke is prevented from exceeding the
proper limit by the pulley block C coming in contact with a stop
connected with the handle G, which closes the inlet valve H, and
prevents the load from being lifted too high. The return stroke of
the ram is effected by the load suspended from the chain; and in
the absence of any load, a small supplementary ram L is employed
to force the main ram B back, the slack chain being made to run
out by the permanent weight M.
STATIONARY ENGINES.
319

N
A
H
B
L
HE BI
Plan
Q
B
N
J
I
HO
K
A,
Fig. 203.-Hydraulic Crane. General Arrangement of Machinery.
Pressure cylinder. B, Ram. C and D, Pulleys. E, Guide pulley. F, Crane post. G, Handle
for valves. н and 1, Weights. J, Pressure pipe. K, Exhaust pipe. L, Supplementary
M, Permanent weight. No, Cylinders and plungers for turning the crane.
valve.

D
N
M
A
B
K
Ins 12 6 0
2
3
5 Feet
Fig. 204.-Cylinder and Valves for Double-power Hydraulic Crane.
A, Cylinder. B, Ram. C and D, Pulleys. E, Piston. F, Valve chest. H, Inlet valve. I, Outlet valve.
J, Pressure pipe. K, Exhaust pipe. L, Valve for higher power. M, Vaive. N, Relief valve.
320
MODERN STEAM PRACTICE.
To meet the variation of load it was formerly the practice to
combine three of the pressure cylinders so as to act either sepa-
rately or collectively upon the lifting chain; but a variation of power
is now obtained with a single-bored cylinder, fitted with a combined
piston and ram, as follows:—A (Fig. 204) is the cylinder, fitted with
the piston E and ram B; the water from the accumulator enters the
valve chest F through the pressure pipe J and the inlet valve H.
For the lower power the water is admitted to both sides of the
piston E by opening the valve L, in which case the power exerted
and the water expended are proportionate to the area of the ram B.
H
M
Fig. 205.-Detail of Valves for Cylinder of Double-
power Hydraulic Crane. - F, Valve chest.
H, Inlet valve. 1, Outlet valve. L, Valve for
higher power. M, Valve. N, Relief valve.
For the higher power the valve L is
closed and the valve M opened, so
that the front side of the piston E is
thrown open to the exhaust K, and
the result, both as regards power
and expenditure, is then propor-
tionate to the full area of the pis-
ton E. It is seldom necessary to
have more than these lower and
higher powers; but where a third
or less power is required, a smaller
ram is used with the other. For lowering the load the valves H and
M are closed and the outlet valve I opened, allowing the water to
escape from the cylinder A into the exhaust pipe K; at the same
time the valve L is opened to allow the water to follow up the piston
in the inward stroke. The packing of
the solid piston A is held in position by
means of a ring of metal B, and secured to
the piston by stud bolts and nuts, and
consists of a cupped leather washer C,
which is pressed against the side of the
for Cylinder of Double-power Hy- cylinder by the hydraulic pressure.
In hydraulic cranes the power is applied
not only for lifting the load, but also
for swinging the jib, which is effected by means of a rack or chain
acting on the base of the movable part of the crane, connected
either with a cylinder and piston, or with two single-acting cylinders
applied to produce the same effect by alternate action; as shown,
the two cylinders N and O (Fig. 203) are fitted with rams, working
by a chain passing round the base of the crane post F. The motion


B
Fig. 206.-Piston and Cupped Leather
draulic Crane.-A, Piston. B, Ring
with bolts. c, Cupped leather.
STATIONARY ENGINES.
321
is controlled by means of a slide valve worked by a handle situated
alongside the handle G, so that while the water is admitted to one
cylinder the other is open to the exhaust. The travel of the rams
is limited by means of a tappet rod connected with the handle of
the slide valve, whereby the crane is prevented from being turned
round too far. Small hydraulic rotary engines have been intro-
duced for working cranes, and in many cases they can be easily
attached to existing hand cranes.
The absence of any sensible elasticity in water renders the motions
resulting from its pressure capable of the most perfect control by
means of the valves which regulate the inlet and outlet passages;
but this property, which gives so much certainty of action, tends to
cause shocks and strains to the machinery by suddenly resisting
the momentum acquired by the moving parts. Take, for example,
the case of a hydraulic crane swinging round with a load suspended
from the jib: the motion being produced by the water entering
into one cylinder and escaping from the other, it is obvious that if
the water passages be suddenly closed, the ram, impelled forward
by the momentum of the loaded jib, but met by an unyielding body
of water deprived of outlet, would be brought to rest so abruptly
as to cause in all probability some damage to the machine. So
also, in lowering a heavy weight, if the escape passages were too
suddenly closed, a similar risk of injury would arise from the sudden
stoppage of the weight. But these liabilities to injury are effectually
removed, in the case of a single-acting cylinder, by fitting a relief
valve in connection with the water passages, consisting of a small
clack valve N opening upwards against the effective pressure, so as
to permit the pent-up water in the cylinder to be forced back into
the pressure pipe, whenever it becomes subject to a compressive
force exceeding the pressure given by the accumulator; and in
the case of a double-acting cylinder fitted with a piston and slide
valve, or where two single-acting cylinders with rams working.
alternately are controlled by a slide valve—as in the instance of the
cylinders N and 0-for turning the crane, relief valves are fitted in
connection with the slide valve. These consist of four small leather
flap valves (Fig. 207), with metal pieces at the top and bottom. The
passages PP communicate with the pressure pipe J, and the pas-
sages EE with the exhaust K. When the slide valve is moved in
the direction of the arrow the pressure is first cut off from the
port R by the top of the valve, the port s being still open to the
21
322
MODERN STEAM PRACTICE.
exhaust K; at the same instant the flap valve T opens upwards.
R
$
and allows a small quantity of water to pass
from the exhaust K into the port R to follow
up the ram until brought to rest. When
the slide valve arrives at the central position
as shown, the port s is closed to the exhaust,
and the pressure in it being increased by
the further motion of the ram before it is
completely stopped, the second flap v is
raised, and a small quantity of water forced
back into the passage P communicating with
the pressure pipe J. When the slide valve
is moved in the opposite direction, the two
Fig. 207.—Section of Slide Valve & remaining relief valves are brought into ac-
tion in the same manner. By these means

Relief Valves for Hydraulic Crane.
E E, Exhaust passages. J, Pressure
pipe. K, Exhaust. PP, Pressure all risk of concussion is avoided, and per-
fect control over the machine is combined
passages.
R and s, Ports.
with great softness of action.
DOCK GATES.
The method generally adopted for opening and closing dock
gates by means of hydraulic pressure consists in applying to each
gate a pair of cylinders with rams and multiplying sheaves, similar
to those used for the hoisting apparatus in hydraulic cranes. One
of these cylinders opens the gate and the other closes it; and the
whole of the machinery is placed in chambers beneath the ground.
The water is admitted from the pressure pipe J to the cylinder a
(Fig. 208) through the inlet valve H by means of the handle G; the
same motion of the handle also opens the outlet valve of the other
cylinder B. The opposite motion of the handle G opens the outlet
valve I, allowing the water to escape from the cylinder A into the
exhaust pipe K, and at the same time admits the pressure to the
cylinder B. A stop M connected with the handle G prevents the
ram from travelling too far in the out stroke, by closing the inlet
valve; and the return stroke of the ram is effected by means
of the weight L. This arrangement has been applied to several
of the London and Liverpool Docks, as well as to some others
throughout the country.
In Fig. 209 we give an engraving of the general plan of a
17.
STATIONARY ENGINES.
323
found to answer extremely well. Instead of connecting the hauling
cylinders with each gate, a line of shafting A, driven by a small
Side Elevation.
A
1
1
Plan
dock entrance which has been adopted in some instances, and

K, Exhaust pipe. L, Weight. M, Stop.
Fig. 208.-Arrangement of Water-pressure Cylinder for Opening and Closing Dock Gates.
H and 1, Valves. J, Pressure pipe.
A and B, Cylinders. G, Handle.
324
MODERN STEAM PRACTICE.
water-pressure engine B, is laid beneath the surface of the ground,
parallel with the coping on each side of the entrance, and by means
of clutches is thrown into or out of gear with each gate crab. A

O
- SATEECES KARU,
Pressure
Engine
O
C
CTO
Pressure Pipe
C
Pressure
Engine
Fig. 209. Arrangement for Lock-gate Machinery.
A, Shafting. BB, Pressure engines. cc, Capstans.
wire from the engine extends the whole length of the shafting, so
that the engine can be regulated from the point where the work
has to be done. A more recent method is to attach a separate
engine to each crab, and also to the sluices; and in some instances.
these engines have been fitted to existing machines without inter-
rupting the traffic. The rapidity with which dock gates can be
STATIONARY ENGINES.
325
opened and closed by these appliances is limited only by consider-
ations of safety to the gates, the time taken in actual practice
being about two minutes. In nearly all the cases in which hydraulic
pressure has been applied for the moving of dock gates, it is also
used for opening and closing the levelling shuttles, and in many
cases also for working the capstans. The former purpose is effected
by the direct application of a cylinder and piston fixed above the
shuttle: and the latter is accomplished by throwing the capstan C
into gear with the shafting A.
WATER-PRESSURE ENGINES FOR DOCK GATES, &c.
These engines consist of a combination of three oscillating cylin-
ders, working cranks inclined 120° to one another. The cylinders A
(Fig. 210) are fitted with plungers B, instead of pistons, and are there-
fore only single-acting. The slide valves V are worked by the oscil-
lation of the cylinders, communicated through the levers L. When
the back end of the cylinder is depressed, the slide valve is lowered,
and allows the water to enter from the pressure pipe P through the
pipe C to the cylinder, where it acts upon the plunger in the out
stroke; and in the return stroke the back end of the cylinder is raised,
the cylinder port C is closed to the pressure pipe P, and open to
the exhaust E. A small relief valve is fitted to the cylinder pipe C,
opening against the pressure, which prevents any shock when the
communication with the exhaust is closed at the end of the return
stroke. These engines have occasionally been made with pistons,
so as to be double-acting; but for the great pressures employed
where accumulators are used, the single-acting arrangement with
plunger is preferred. It will be observed that with the arrange-
ment of cranks dividing the path into three equal parts, there is no
liability of the engine stopping on the "dead centre," as it is termed,
the one crank assisting the other over the extreme points.
In working swing bridges by means of water pressure, a central
press is generally applied to lift the entire bridge clear of its
supports, and it is then turned by an application similar to that
used for swinging a crane. An example of a swing bridge on this
principle is seen at Wisbech, having an opening of 85 feet, arranged
for a double roadway in one leaf, weighing about 450 tons. The
power is derived from an accumulator charged by a hand force
pump, and notwithstanding its great length and weight the bridge
326
MODERN STEAM PRACTICE.
Sectional Elevation

A
E
Plan
P
E
E
A
B
A
B
A
B
1
1
+
Fig. 210.-Water-pressure Engine.
A A, Cylinders. BB, Plungers. c, Pipe to cylinder. E, Exhaust pipe. L, Lever for working slide
valve. P, Pressure pipe. v, Slide valve.
STATIONARY ENGINES.
327
can be lifted and turned in less than two minutes.
The plan of
using an accumulator charged in this way has been adopted for a
railway drawbridge near Caermarthen; and it can be applied to
many other purposes requiring a concentrated exertion of power
with intervening periods of inaction.
One application of water pressure with an accumulator, for the
purpose of rapidly lifting or lowering heavy loads, calls for special
notice because of its growing importance. We refer to vertical
hoists at the landing stations of steam ferries, where the traffic of a
railway is required to be passed over a river or estuary not spanned
by a bridge. The traffic of the Aix-la-Chapelle, Düsseldorf, and
Ruhrort Railway is by this means shipped and unshipped at the
ferry across the Rhine; and such is the rapidity and facility of the
operation that a train of twelve coal waggons, weighing collectively
133 tons, can be transferred from the deck of the steamer to the
railway, a height of about 20 feet, in twelve minutes. Each hoist
lifts two waggons at a time, and raises its load in ten or twelve
seconds. These hoists are so arranged as always to accommodate
themselves to the level of the boat, and also to stop at the exact
level of the railway.
WATER POWER FROM NATURAL FALLS.
Having said this much on that branch of the subject which
embraces the two principles of accumulation and transmission of
water power, we will now notice the applications of water pressure
as derived from natural falls. When the moving power consists of
a natural column of water, the pressure rarely exceeds 250 or 300
feet; and in such cases, to produce rotary motion, a pair of cylin-
ders and pistons are employed, with slide valves resembling in some
measure those of a high-pressure engine, but having relief valves
to prevent shock at the return of the stroke. Where the engine is
single-acting, with plungers instead of pistons, as in the water-
pressure engine already described, the relief valves are greatly
simplified, and indeed are reduced to a single clack in connection
with each cylinder, opening against the pressure, as the relief valve
in the valve chest of the hydraulic crane. The water engines
erected at the lead mines at Allenheads, in Northumberland, pre-
sent an example of the utilization of natural falls in this country.
These engines are used for the various purposes of crushing ore,
328
MODERN STEAM PRACTICE.
raising materials from the mines, pumping water, giving motion to
machinery for washing and separating the ores, and driving a saw-
mill and the machinery of a workshop. Small streams of water,
which flowed down the steep slopes of adjoining hills, have been
collected into reservoirs at elevations of about 200 feet, and pipes
have been laid from them to the engines. Water-pressure machin-
ery is invaluable in such a hilly district, where steam power is
almost impracticable in a commercial point of view, from the great
cost of conveying coals to the works.
An application of hydraulic machinery in situations where falls
of sufficient altitude for working water-pressure engines cannot
be obtained has been carried out at these mines, which deserves
special notice. For the purpose of draining an extensive dis-
trict, and searching for new veins, a drift way or open level nearly
6 miles in length was cut. This drift way runs beneath the
valley of the Allen, nearly in the line of that river, and upon
its course three mining establishments have been erected. At
each of these power was required for the various purposes already
mentioned, and it was desirable to obtain this power without re-
sorting to steam engines. The river Allen was the only resource,
but its descent was not sufficiently rapid to permit of its being
advantageously applied to water-pressure engines; it abounded,
however, with falls suitable for overshot wheels, and it was deter-
mined to employ the stream, by means of such wheels, in forcing
water into accumulators, and then transmitting by pipes the power
thus stored to the numerous points where it was required. In this
arrangement intensity of pressure takes the place of magnitude of
volume, and the power derived from the stream assumes a form
susceptible of unlimited distribution and division, and capable of
being utilized by small and compact machines.
A somewhat similar plan is also adopted at the coaling establish-
ment for the navy at Portland Harbour. The object in this case
is to provide power for working hydraulic cranes and hauling
machines for coaling war steamers. A reservoir on an adjoining
height affords an available head of upwards of 300 feet; but in
order to diminish the size of the pipes, cylinders, and valves con-
nected with the machinery, and also to obtain greater rapidity of
action, a hydraulic pumping engine and accumulator are interposed,
so as to intensify the pressure and diminish the volume of water
acting as a medium of transmission.
STATIONARY ENGINES.
329
HYDRAULIC MACHINERY FOR WAREHOUSING GRAIN
AT THE LIVERPOOL DOCKS.
The dock around which the blocks of warehouses on the Liverpool
side of the river are situated, shown in the general plan Fig. 211,
is 570 feet long, 230 feet broad at one end, and 180 feet at the other.
Three sides of it are occupied by separate blocks of warehouses,
connected by wrought-iron bridges. The blocks on the east and
west sides are 650 feet long and 70 feet wide, and that on the north
end is the same width and 185 feet long. Each block contains five
stories, as shown in the transverse section, Fig. 215; above the fifth
or top storage floor, and partly in the roof, is placed the machinery
floor; and below the quay level are wells and arched subways for
the reception of the underground machinery. There are five dis-
charging berths for large vessels, one at the north block and two
each at the east and west blocks; and additional accommodation is
provided for small vessels. In the centre or north block is placed
the steam engine A, of 370 horse-power, which in addition to
driving the whole of the machinery in the warehouses, supplies
power for working the lock machinery and the bridges. These
consist of two bridges of 60 feet span and one of 50 feet, twelve
sluices, ten powerful ship capstans, and twenty-four machines for
opening and closing the lock gates.
The principal processes required to be performed by the machin-
ery in the warehouses are:-Discharging grain in bulk direct on to
the quay or into the warehouses;-hoisting grain in bags or casks
on to the quay;-discharging ordinary merchandise direct on to
the quay or on to any floor in the warehouses, and loading out-
ward-bound vessels;-lifting and lowering sacks or other merchan-
dise on platform elevators and jiggers, to or from any floor;-
elevating, screening, weighing, and distributing grain in bulk, and
conveying it to and from all parts of the warehouses, and outwards
for delivery into ships or waggons; and transferring grain from
one part of the warehouses to any other part.
The two accumulators which generate the water pressure employed
as the medium for conveying power to the machinery are situated
at CC in the general plan Fig. 211, at each end of the centre or
north block of building; and between the west block and the river
entrances a large auxiliary accumulator is placed. The two accum-
ulators in the north block are each weighted with a load of 70 tons,
330
MODERN STEAM PRACTICE.
acting on a ram 17 inches in diameter, with a vertical range of 17
'feet; and the auxiliary accumulator is loaded with 100 tons, acting

Fig. 211.-General Plan of Warehouse.
A, Steam engine.
200 Feet
B, Boilers. CC, Accumulators.
on a 20-inch ram having a range of 23 feet. The water pressure is
conducted through cast-iron main pipes, varying from 6 inches to
STATIONARY ENGINES.
331
3 inches in diameter, and wrought-iron branch pipes convey it
from the mains to the several machines. In order to economize
the consumption of water, which is obtained from the town supply,
return pipes are laid to conduct the exhaust water from all the
machines back again into a well in the engine house, from which
the pumps draw their supply; and thus the same water is used over
and over again. The steam engine for supplying the accumulators
is situated on the quay level at A, with its boilers at B; it is a hori-
zontal high-pressure engine with two steam cylinders, and the
plungers of the double-acting force pump are attached directly to
the piston rod. The engine is made in duplicate in all its parts,
to admit of either side being worked separately in case of need.
Double-acting lift pumps are provided for raising the supply and
the return water from the storage well into a settling tank above
the level of the engine, from which the forcing pumps draw their
The engine is capable of forcing 209,350 cubic feet of water
per minute against the accumulator pressure of 700 lbs. per square
inch.
water.
A number of experiments were made for the purpose of ascer-
taining the best means of conveying the grain horizontally from
one part of the warehouses to another. The common method by
means of revolving screws was first tried, the experiments being
conducted at a brewery fitted up with this class of machinery.
The screw employed was 12 inches diameter and 4 inches pitch,
made in lengths of about 12 feet from bearing to bearing; the
space between the screw and the fixed casing in which it revolved
was 1/4 inch. At sixty revolutions per minute, which was found to
be the maximum effective speed, this screw discharged the grain at
the rate of 634 tons per hour, and required a power of 004 horse-
power for every foot run. The sectional area of the body of grain
propelled was 49 per cent. of the whole transverse area of the screw.
At a higher velocity than sixty revolutions the grain was simply
carried round, and not propelled forwards at all. With a screw,
afterwards tried, of 12 inches diameter and 12 inches pitch, driven
at seventy revolutions per minute-the most effective speed-34 tóns
of grain per hour were discharged, and the power required to drive
the screw was 0.125 horse-power per foot run, or 37 per cent. less
than in the case of the previous screw for the same delivery of
grain. The sectional area of the grain in motion was 72 per cent.
of the whole area of the screw. The saving in power in this case
332
MODERN STEAM PRACTICE.
was owing to a better construction of parts, as well as the quick
pitch. The effect upon the grain itself was very marked: with the
first screw it was propelled without any appreciable agitation, but
with the quick-pitched screw it was rubbed and polished, and
thereby improved in marketable value.
In order to overcome the objections experienced with this screw,
and to improve still further if possible the conditioning of the grain,
trials were made with screws contained in revolving casings. A
preliminary experiment was made with a 6-inch screw, 6 feet long,
with 2 inches pitch and a depth of blade of 2½ inches; a portion of
the casing was perforated so as to act as a screen, which it did
effectually. A second trial was then made with a 30-inch screw,
calculated upon the result of the preliminary screw to discharge at
the rate of 50 tons per hour. The length of this screw was 18 feet,
and its pitch 12 inches, or ths of the diameter. The body of the
screw was properly balanced, and revolved upon finely adjusted
rollers, carried in cast-iron frames. A third experiment was made.
with a screw 12 inches in diameter and 12 inches pitch, only with
the view of ascertaining the effect of the quicker pitch. The results
of these trials were as follows:-
The 6-inch Screw discharged per minute, at 60 revolutions, o'47 cubic foot of wheat.
'Do.
Do.
Do.
do.
do.
do.
80
""
100
0.60
0'50
""
99
140
o'00 (no delivery).
Showing that, as the grain in this class of screw is propelled for-
wards by gravity, centrifugal force comes into action at high speeds,
and stops the discharge. With the 30-inch screw a speed of thirty-
six revolutions per minute was found to be the most effective. At
this speed the grain was carried up on the rising side of the screw
about 5 inches above the centre of the casing, and the discharge
was 63½ cubic feet, or about 80 tons of wheat per hour, which was
a much higher duty than had been calculated upon. The power
required was 0.40 horse-power per foot run; and the sectional area
of the body of grain was 36 per cent. of the whole area of the
casing. The 12-inch screw, driven at the same speed of thirty-six
revolutions per minute, gave 10 tons of wheat per hour, with a
sectional area of only 17 per cent. The pitch of ths of the
diameter proved the most effective of those tried. The use of these
screws with revolving casings was highly advantageous to the grain,
which became well rubbed and polished; and they also obviated
STATIONARY ENGINES.
333
the principal objection experienced with the screws in fixed casing,
which harboured dirt and caused the grain to be injured by the
action of the screw blades revolving within it. The great power
necessary to drive the screw with revolving casing was found, how-
ever, an insuperable objection to its adoption upon a large scale.
The long distances over which grain had to be conveyed hori-
zontally in the warehouses, amounting collectively to 7000 feet, or
about 1 mile, and the power required for conveying it even with
the best form of screw, rendered it expedient to seek some other
mode of transport requiring less power; and recourse was therefore
had to endless travelling bands. After a few preliminary trials
with small canvas bands, experiments were made with a flat band
12 inches broad, constructed of canvas and india rubber. In work-
ing out this arrangement the first point to ascertain was the highest
speed that could safely be used with different kinds of grain. A
speed of 8 feet per minute was found to be the maximum for oats
and other light grain; and at this speed even bran and flour can
be conveyed without any portion being blown off by the resistance
of the air in the passage of the band. A speed of about 9 feet per
second can be reached with heavy clean 'grain, and a still higher
speed with peas; chaff is blown off at a speed of about 9 feet per
second. The quantity of grain discharged by the 12-inch band,
travelling at a speed of 8 feet per second, was about 35 tons per
hour. Further trials were then made with a band 18 inches broad,
formed of two plies of stout canvas, covered with vulcanized india
rubber; and this pattern was subsequently adopted for permanent
The band was made continuous, extending over a distance
of 37 feet, and was supported on plain cylindrical carrying rollers,
fixed at intervals of 6 feet apart. The rollers were made of wood,
with wrought-iron spindles revolving in bearings of white metal,
and lubricated with hard grease. The band was driven by shaft-
ing, and provided with a self-tightening apparatus similar in con-
struction to that finally adopted in the warehouses, consisting of a
heavy tightening pulley suspended upon the band, and sliding
vertically between guides. The maximum quantity of heavy grain
conveyed by an 18-inch band is at the rate of about 70 tons per
hour, and the power required to drive the band when working at
this rate is equal to about o'014 horse-power (th) per foot run,
The grain has no tendency to fall off the band, and indeed it is
surprising to see separate grains at the edge of the band remain
use.
334
MODERN STEAM PRACTICE.
steadily in position whilst passing over the carrying rollers at the
highest rate of speed. Comparing the amount of power required
to convey a stream of grain at the rate of 50 tons per hour through
a distance of 100 feet, by means of the common screw in stationary
casing, the tubular screw with revolving casing, and the travelling
band 18 inches wide, the following are the results:-
With the common screw.....
tubular screw.......
18-inch travelling band..
J
18.38 horse-power.
25'00
I'02
This shows the great superiority of the band over the screws in
economy of power.
For the purpose of passing the grain off at any point on either
side of the main travelling bands, several contrivances with air-
blast and brushes driven from the band itself were tried, but with
indifferent success; both methods were objectionable on account of
raising dust, and the friction of the brushes proved injurious to the
band in course of time. The idea then occurred of diverting the
stream of grain by means of an upward deflection of the carrying
band, which would throw it clear from the band into the air for a
short distance, and in falling it would be caught and led off by a
spout to either side as required. This plan proved successful, and
has been extensively adopted in connection with the use of the
endless travelling bands for carrying grain. The throwing-off
apparatus is shown in Fig. 212. It consists of a couple of wrought-
iron rollers B B, centred in gun-metal bearings in a rocking frame C,
which is hung in a movable carriage D running upon the timbers E
of the wooden framing that supports the travelling band I I. The
carriage is moved to any position along the length of the band
where the grain is required to be discharged, and is then secured
by the wedges FF and the clamping screw G. The rocking frame C
is rotated in either direction by means of the screw and worm
wheel H, so as to bring the pair of rollers B B into action at the
proper position for throwing the grain off in the direction in which
the band I is running; and the rollers are turned back into the
horizontal position so as to be clear of the band when the carriage D
is required to be moved to another position. A curved spout K is
attached to the carriage D for catching the stream of grain in its
fall, and leading it off on either side of the band I. No difficulty
is experienced in keeping the grain on the band; but it is found
necessary to let it fall upon the band from a feeding hopper through
STATIONARY ENGINES.
335
A
End Elevatio
K
D
of 42½°, so as to give the falling grain a horizontal velocity nearly
equal to that of the band. The fine dust and grit thrown off with
K
T
Ꮮ
B, Rollers.
c, Rocking frame.
Side Elevation.
D
E
G
a spout rather less than half its breadth, and set at an inclination

E
Fig. 212.-Throwing-off Apparatus.
D, Movable carriage. EE, Timbers. FF, Wedges. GG, Clamping screws.
1, Travelling band. K, Spout. L, Roller.
H Worm wheel.
336
MODERN STEAM PRACTICE.

Side Elevation.
J
J
Plan.
J
J
I
I
25
N
the grain at this and other parts of the machinery require it to be
H
M
J
Fig. 213.-Travelling Band and Gear.
I, Band. JJ, Cross bands. M, Tightening pulley. N, Hydraulic engine. R, Driving roller. s, Mitre wheel. T, Clutch.
STATIONARY ENGINES.
337
protected from injury at such places. As the flow of various kinds
and conditions of grain through the spout from the hopper varies
considerably, it is found desirable to place a pair of oblique side
rollers at the point where the grain falls upon the band, in order to
give it a slightly hollow form, and so prevent the grain from
spreading. In passing heavy quantities of grain along the bands.
to great distances it has also been found expedient to apply at
intervals pairs of these oblique side rollers, which are carried on
movable frames that can be set at any required spot.
The cross bands JJ (Fig. 213), for conveying the current of grain
in a direction at right angles to the main bands, are driven from the
lower or return half of the main band, which is passed half round
a driving roller R, at each of the cross bands; and the motion is
communicated from this roller to the cross bands through a pair of
mitre wheels S, having a clutch T for throwing the driving shaft in
and out of gear. The cross bands or other machinery, such as the
centrifugal distributing fan, can also be driven by depressing the
return half of the main band by a roller carried in a rocking frame
so as to bring the band well into contact with a fixed roller situated
underneath, which can then communicate the required motion for
any purpose; and this simple mode of taking off power from the
main bands has proved of service in many ways.
A revolving fan for spreading the grain over the floors of the
warehouses, and for ventilating it and improving its condition, has
been used with success. This fan is carried upon an upright shaft,
driven from the main band by the same arrangement as that
described for driving the cross bands. As the band is required to
travel in opposite directions, the fan is made with straight radial
vanes, to allow of its revolving in either direction. The grain is led
by a spout on to the top of the fan, and to avoid the separation of
heavy and light particles in the mass, and to spread it as evenly
over the floor as possible, the body of the fan has a conical form,
the alternate blades being made of a different length and shape, as
shown in the enlarged view, Fig. 214. A hinged tongue is placed
in the end of the delivery spout above the fan, and the discharge of
the grain can be directed to any particular spot by turning this
tongue round in the required position. The fan is placed 9½ feet
above the floor, and at its usual speed of 250 revolutions per minute
it deposits the grain in a circle of 45 feet diameter.
Five hydraulic cranes for discharging cargo are fixed in towers
22
338
MODERN STEAM PRACTICE.
specially constructed in the warehouses, as shown in Fig. 215. These
cranes are fitted for raising grain in tubs containing 21 cwts. each,
at a rate of 50 tons per hour under the most favourable conditions;
Vertical
Plan
Section
and they are also employed for
landing sacks, casks, and other
merchandise on to the quay, or
to any of the warehouse floors.
The lifting chain has an extreme
range of 130 feet, and the jib an
extreme projection of 24 feet be-
yond the quay; a traversing mo-
tion of 7½ feet is given to the
foot of the jib, but this is only
required for the largest class of
vessels. The motions are all ef-
fected by hydraulic power, under
the control of one man stationed
on a platform in the tower. The
grain is filled into tubs in the
hold of the vessel, and to find the
best form for these tubs has been
matter of some difficulty. The
first form used was the ordinary
tipping tub, which has by long
experience been found to answer
best for the discharge of coal,
salt, gravel, &c. The next form tried required no tipping, but was
fitted with a cone to deliver the grain through the bottom. The
form that proved on the whole most satisfactory also requires no
tipping, and is fitted with a butterfly valve in the bottom; when the
tub is in position for emptying into the upper receiving hopper P,
this valve is opened by a lever from the platform on which the
man is stationed to work the crane. The time required by this tub
for emptying itself depends on the kind and quality of the grain
which it contains: with wheat in good and dry condition it is five
seconds, with barley seven seconds, and with Indian corn from
nine to ten seconds.


Fig. 214.-Distributing Fan.
The hopper P (Fig. 216), into which the grain lifted by the crane to
the top of the warehouse is dropped from the tub, holds about 8 tons,
and from this hopper the grain is diverted into two streams, and
STATIONARY ENGINES.
339

N, Distributing fan. o, Crane.
P, Upper receiving hopper.
Q, Band. R, Receiving hopper.
s, Weighing hopper.
TT, Distributing hoppers.
U u, Spouts. v, Arched subway.
w, Elevator. x, Filling hopper.
LED
R
S
Fig. 215.—Transverse Section of Warehouse, showing Hoisting Gear, &c.
340
MODERN STEAM PRACTICE.
these bands would be sufficient to carry the grain delivered by the
crane, but two are employed to spread it out more, and to separate
R
T
•
allowed to flow through the spouts fitted with regulators on to two
18-inch inclined bands Q, driven by one hydraulic engine. One of

Fig. 216.—Machinery Floor.
P, Upper receiving hopper. Q, Band.
T T, Distributing hoppers. N, Distributing fan.
R, Receiving hopper.
u, Spout.
s, Weighing hopper.
11 Bands.
LL, Rollers.
o, Crane.
STATIONARY ENGINES.
341
the dust from it when required. This separation is effected by an
inclined flap fixed in the inner receiving hopper R, into which the
two bands Q convey the grain from the outer hopper P. From the
hopper R the grain is allowed to drop through the valve into the
I-ton weighing hopper S; after which it is delivered, by a simple
arrangement of doors in the bottom of the weighing hopper, to
either side of the distributing hopper T, from whence it passes on
to one or other of the 18-inch bands II which traverse the entire
length of the warehouses. The man stationed at the weighing
machine S regulates the flow of grain from the several hoppers,
and records the quantity passed.
Two main lines of 18-inch bands, made to run in either direction,
are necessary for the convenient working of these warehouses. A
vessel, for instance, lying at the west block of the warehouses may
require her cargo deposited at either end of that block, or at any
spot in either of the other two blocks; and at the same time
another vessel lying at the east block opposite may have its cargo
housed in the west block. Thus it often happens that two streams
of grain are flowing in opposite directions, and that one or both of
these is carried right round the warehouses. The bands in the
east and west blocks are divided into two lengths, and the bands
connecting these two blocks and passing through the north block
are in one length. Each band is fitted with a separate tightening-
up apparatus, seen in Fig. 213 at M; and is driven by a separate
hydraulic engine N, of about 3 horse-power, having two cylinders,
and fitted with reversing and regulating gear, which can be con-
trolled from any point along the entire length of the band. At
each point where the flow of grain has to be diverted from a main
band to a cross band, a fixed throwing-off carriage is stationed.
Two movable throwing-off carriages are provided on each main
band, for casting the grain off the band into the wooden descending
spouts, 8½ inches square, which convey it from the top of the
warehouse to any floor in the building. There are fifty-six of these
spouts U U, Fig. 215, passing from the upper machinery floor down.
to the lower 12-inch bands in the arched subway v v below the quay
level; they are provided with sliding doors at the different floor
levels, to admit of the grain being shovelled into waggons on the
railway which traverses the centre of the block, or on to the lower
12-inch bands for conveying to the elevators. A number of other
shoots at suitable intervals are built in the walls of the warehouses
342
MODERN STEAM PRACTICE.
fronting the dock at the levels of the several floors, and each is
provided at the first floor with a delivery outlet, to which a movable
spout is hooked on, for delivering grain from the warehouse into
vessels. The arrangement of the lowering band machinery is a
counterpart of the upper, but upon a smaller scale, and without the
movable throwing-off carriages provided on the upper bands, which
are not required for the lower. These lower bands are employed
for the purpose of conveying grain from any of the descending
spouts to any of the five elevators W, which are fixed in the crane
towers. The grain conveyed along these 12-inch main bands is
thrown upon the 18-inch cross bands, which deliver it into the
hopper X, supplying the elevator W; one 18-inch cross band will
carry the full quantity of grain conveyed by the two 12-inch bands,
and the cross bands are arranged to receive their motion from
either line of the main bands. Much of the grain discharged from
the vessels in the dock is sorted upon the quay, and is then thrown
by hand into the hopper X of the elevators.
The elevator for raising the grain from the bottom to the top of
the warehouses is shown on a larger scale in Fig. 217. The wrought-
iron bucket W, capable of containing about 21 cwts., is slung from
the lifting chain by an arrangement of bars and levers, and provided
with guiding rollers running between the upright timbers, so
arranged that on reaching the top the bucket tips over, and dis-
charges the grain into the hopper v. This hopper delivers the
grain upon the same inclined cross bands Q that convey it from
the outer crane hopper P. The bottom hopper is made in two
parts, the upper of which X, protected by a grating, receives the
bulk of the grain, while the lower compartment z contains only one
charge at a time for the elevator bucket W, and is separated from
the upper portion by a sliding valve. The descending speed of the
bucket having been checked, as it approaches the bottom it strikes
the arm of the tappet lever A, which closes the valve between the
two compartments X and Z of the hopper; and continuing its
descent still more slowly, the bucket strikes another tappet arm B,
which disengages the iron flap C that covers the front of the lower
compartment Z; this flap, falling forwards by the weight of the
grain behind it, shoots the contents of the lower hopper z into the
bucket W. As soon as the bucket has received its charge the
motion is reversed for lifting. Beginning to ascend at a moderate
speed, the bucket closes the flap C of the lower hopper, which
STATIONARY ENGINES.
343
is held up against it, as shown dotted, by means of spring

Front View
X
X
Ꮓ
2
C
W
0000000000
W
A
Discharging
W
C
Y

Filling
D
X
Z
Fig. 217.-Elevator for Lifting Grain into Warehouse.
▲, Tappet lever. B, Tappet arm. C, Flap. D D, Spring catches. o, Chain. w, Elevator.
x, Filling hopper. Y, Receiving hopper. z, Filling compartment.
catches DD; and the bucket then strikes the tappet lever A of the
344
MODERN STEAM PRACTICE.
hopper valve, and re-opens the communication between the two
compartments X and Z. The speed is then accelerated until the
bucket arrives near the receiving hopper V, when it is again retarded
before the grain is shot out. The motion of the bucket is regulated
by self-acting gear. These bucket elevators are intended to raise the
grain at the rate of 50 tons per hour, but they are capable of being
worked at a higher speed. The chain o of the crane is employed
for lifting the bucket of the elevator; but it has been found expedient,
on account of the demands of the traffic, to make the elevators also
independent of the cranes, and therefore separate hydraulic cylinders
with their adjuncts have been supplied for working the former.
Trials have been made for lifting grain by means of dredging
machines, and it has been found that with a dredger 30 feet long
50 per cent. of the applied power proved effective. Experiments
have also been made for raising corn by air pressure or suction,
and the results obtained are sufficient to prove that this system
possesses certain advantages over the plan in use; but it is sur-
rounded with difficulties and obstructions which must be removed
before it can be employed with advantage upon a large scale.
Casks, bags, and other merchandise are raised or lowered either
by hydraulic cradle hoists or by jiggers. There are twelve hydraulic
hoists of the ordinary construction, each capable of lifting a load
of 1 ton to the uppermost floor of the warehouses. They are found
also serviceable in breaking out the cargoes from the fore and aft
hatchways of a vessel lying with its centre hatch in line with the
crane or elevator. For this purpose the lifting chain is disconnected
from the cradle of the hoist, and led through a snatch block fastened
to some part of the vessel. The twenty single-acting outside
jiggers, originally constructed only for lowering loads by friction,
have been supplied with auxiliary hydraulic power for lifting loads
from 6 to 7 cwts. Twelve double-acting jiggers, for loads up to
IO Cwts., have been added in the centre of the warehouses, for lifting
or lowering goods to railway waggons; they are so constructed that
they can be used singly or together, and for lifting or lowering.
Both machines may be alternately lowering goods into waggons
below from any of the floors of the warehouses, or by means of the
water pressure they may both be raising goods from the waggons
to any of the floors; or one side of the machine may be lowering
whilst the other is hoisting goods from the hatchways of vessels to
which the lifting chain has been led.
STATIONARY ENGINES.
345
HYDRAULIC MACHINE TOOLS.
(SEE PLATE.)
The application of hydraulic pressure to single machine tools
may be said to date from about the year 1847, when Mr. Fox used
the Bramah press for the purpose of forging. Since then a variety
of hydraulic tools have been introduced, amongst which may be
mentioned those for forging and welding, rivetting boilers and ships'
frames, fixing boiler tubes, for bridge and girder work, bending
angle irons, flanging plates, shears for cutting chain cables, beam
straighteners or benders, &c.
Fig. I in the Plate shows a portable rivetter, having the cylinder
A between the fulcrum B and the rivetting dies CC.
In designing portable rivetters for ship and bridge rivetting some
form of flexible pipe is necessary, to convey the water to the
working parts; and copper pipes or india-rubber hose are used for
this purpose. The cranes carrying the rivetters are either attached
to fixed posts, or, as shown by fig. 2, the posts are movable on a
trolly, and by means of the walking pipes B B, connected to the stop
valve A and a swivel joint C, the whole apparatus may be moved at
pleasure. By means of connections at D and E at the foot of the
crane post, the pressure is conveyed by the pipe II to swivel Q,
where the walking pipes I'I' convey the water to the hydraulic lift
G on the carriage F, and a copper pipe H conveys the pressure to
the rivetter. Such a machine will put in over 2000 rivets per day.
Fig. 4 shows an arrangement designed for the rivetting of ships'
keels, where the small depth of the rivet heads and their great size
requires special arrangement. A post BB carrying a turntable revolves
on the trolly A, a pair of levers C, attached to a carriage D, carry the
rivetter E, which can be raised at pleasure to suit the work, and is
kept vertical by means of a parallel motion F; the whole is counter-
balanced by the weight N. The keels of the City of Rome and
Servia were rivetted by such a machine, and the advantage of so
powerful a method of closing up the rivets is evident when it is
considered that the keels of such large vessels are made up of a
number of plates and bars of great thickness. As a matter of
experiment, as many as 24 plates, each ½ inch thick, have been
closed up or rivetted apparently into a solid piece, showing what
346
MODERN STEAM PRACTICE.
work can be done by a suitable combination of pressure and per-
cussive action.
Fig. 3 shows a machine for flanging plates. On the bottom
casting B a matrix D is fitted, upon which the plate to be flanged is
placed, and by means of the block E descending the plate is turned
over upon its edges; to prevent buckling a cylinder F is fitted with
a plunger H carrying a table G on its ram, by means of which the
plates can be gripped between the table G and the block E.
Fig. 5 shows a machine for bending or straightening angle irons
and beams. The piece to be bent rests upon the abutting blocks
B B, which are adjustable by right- and left-handed screws AA, and by
means of a tappet gear the supply of water and also the travel are
regulated according to the work required, thus insuring exact repe-
tition and accuracy in work.
A very extensive adoption of hydraulic power to machine work
has been made at the French arsenal at Toulon, where amongst
others two punching and shearing machines, and also angle-iron
benders similar to fig. 5 are used, capable of exerting 100 tons of
pressure. There is also a stationary rivetting machine exerting
40 tons pressure, and a number of portable rivetting machines for
rivetting the cellular bottoms and decks of ships, at a distance
of 1300 feet from the accumulator. The pressure used is 1500 lbs.
per square inch. It appears that less steam power is required by
this hydraulic arrangement than would otherwise be the case, and
the author of the paper to which we are at present indebted says, “A
moment's consideration will show that when gearing is used the
prime mover must be equal to the maximum demand which can
be made on it at any moment. The accumulator, however, affords
a smaller engine the opportunity, when not otherwise fully engaged,
of storing up by easy stages an amount of power equal to the greatest
instantaneous demand likely to be made, and as long as the work
required is not equal to the power of the pumps, this process of
putting by power, as it were, is going on, consequently a much
smaller prime mover will suffice, which means less boiler power and
a more economic use of steam.'
"1
¹ See a valuable paper and drawings in Trans. Inst. Engineers and Shipbuilders in Scot-
land, vol. xxiv., by Mr. R. H. Tweddell of London, who has been of late years highly
successful in applying hydraulic pressure to tools on a complete scale.
MARINE ENGINES.
THE OSCILLATING ENGINE.
The vibrating or oscillating engine introduced by Maudslay in 1827,
with its varied modern improvements, is very suitable for paddle-
wheel steamers, the comparatively small space it requires fitting it
admirably for this class of vessel. It is the most direct-acting kind
of engine which we have; the piston rod is connected to the crank
pin directly, thus saving height in the engines where that is a
desideratum, and the weight is most satisfactorily placed, being
neither too high nor too low in the ship. The many examples-
from the small river boats on the Thames of 30 horse-power collec-
tively, to large ocean steam ships such as the Great Eastern, the
largest ship as yet constructed, with oscillating engines for the
paddle wheels of 1000 nominal horse-power collectively-all bear
testimony to the success of the oscillating type of engine. It may
be regarded as the only example left of the many classes of engines
that have been successfully applied to paddle-wheel ships; and
from our being able to couple the crosshead of the piston rod
directly on the crank pin, and keep the weight of the machinery
below the deck, the oscillating engine is likely to remain long in use
for shallow river boats propelled by paddle wheels, for undoubtedly
this method of propulsion possesses many advantages over the
screw propeller for vessels of light draught, especially when they
are built to attain great speed.
The peculiar motion of these engines-the cylinders vibrating on
central hollow trunnions-requires the parts to be nicely balanced;
and as the piston rod takes the side strain and the strains imparted
by the action of the steam on the piston, it requires to be made of
greater diameter than for ordinary engines, where it is only sub-
jected to tension and compressive stress.
The trunnions should be so placed that the preponderance of the
weight of the cylinder is towards the bottom, by which means the
348
MODERN STEAM PRACTICE.
strain on the piston rod is not so much felt, and when the crossheads
are uncoupled from the crank pins the cylinders are not so liable
to tilt. This will be found a great convenience when undergoing
repairs at sea. The larboard and starboard trunnions are for the
steam, which passes through a belt cast along with the cylinder
into the valve casing. The faces for the valves are generally of the
three-ported type, two ports are for the steam and a central one for
the exhaust. The two central trunnions are for the exhaust steam,
which passes into the belt around the cylinder, and then into the

E
G

E
D
B
F

C
A
B
A
B
I
E
Ꮐ
D
A, Cylinder.
Fig. 220.-Cylinder.
BB, Trunnions. c, Cylinder cover.
D, Bottom cover. EE, Valve faces. FF, Steam
passages. G,
G, Exhaust passage.
Fig. 221.-Trunnion Pipe and Stuffing Box.
A, Trunnion pipe. B, Gland for stuffing box. c, Cy-
linder. D, Throttle-valve pipe. E, Bracket for
supporting do. F, Pillow block. G, Frame.
condenser through the hollow trunnions; thus one half of the belt
allows the steam from the boiler to pass into the valve casing, and
the other half acts as a passage to the condenser, the division being
formed by feathers or bars cast in the cylinder.
The trunnion pipes for the steam and exhaust are fitted with glands
and packing spaces formed in each trunnion; the former are bolted
to the branch pipes, which are supported by brackets bolted to the
bottom frames, and the latter are bolted to the condenser casting,
MARINE ENGINES.
349
and packed with hemp or other packing, similar to the piston-rod
packing. The branch pipes are bent upwards, and on the top flanges
are placed the throttle and expansion valves; thus an immovable
pipe, in communication with the valve casing which vibrates along
with the cylinder, is made perfectly steam-tight.
B
The steam valves are generally formed in duplicate, one being
placed on each side of the cylinder; while, for long-stroked engines
of this class, four valves have been introduced. In the former case
the horizontal line of location, or centre line of the exhaust port, is
on the centre line of the trunnions; in the latter, the valves are
placed above and below the trunnion centre line, with the object
of reducing the length of the steam ports, and thereby saving steam
at each stroke of the engine, and consequently fuel. The object of
placing the valves on each side of the cylinder is to balance it,
each valve is also greatly reduced in size; but notwithstanding that
the valve gearing is more complicated, double valves are generally
adopted, as they secure a neater and more equally balanced cylin-
der. One valve may be used for very small power, and a weighted
lever placed on the opposite side of the cylinder to balance it.
The stuffing box and gland for the piston
rod of the oscillating engine is made very
deep, giving a large bearing surface to take
the side strain caused by the vibration of the
cylinder; and in cases where the proportions
allow of great space between the end of the
crosshead and the top of the gland bolts,
the part cast along with the cylinder cover
can be made of any convenient length, with
a brass bush inserted at the bottom, and the
necessary bushes and glands at the top of
the long neck piece, as in ordinary arrange-
ments. Care must be taken to have a
small amount of clearance all round the
piston rod below the stuffing box, or to insert a very deep bush.
The condenser in the ordinary injection system is placed between
the cylinders, and in the surface system it is placed on the centre
line of the ship, behind or before the cylinders as the case may be.
The latter is not so compact an arrangement as the former, but it
is necessary, as the space taken up by the surface system will not
allow the condenser to be placed as with plain injection.

A
C
Fig. 222.- Cylinder- cover
Stuffing Box.
A, Stuffing box. B, Gland.
c, Bottom bush.
350
MODERN STEAM PRACTICE.
The air pumps for the injection system are either single or in
duplicate, lying at an angle; when one pump is used it is

C
B
A
E
A, Condenser. B, Air pump.
Fig. 223.-Single Air Pump and Condenser.
c, Air-pump cover. D, Exhaust passage. E, Hole for injection valves.
generally placed forward in connection with the cylinders; when
two are adopted, one is forward and the other aft of the centre line
of the engine. They are worked directly from the intermediate

C
E
C
B
A
B
F
Fig. 224.-Double Air Pump and Condenser.
BB, Air
A, Condenser. B B,
pumps. cc, Air-pump covers. D, Exhaust passage. E E, Hot wells.
crank shaft, with one rod for the single pump and two rods on the
same crank for the double arrangement. The rods have suitable
crossheads for taking the crank pin, and their bottom ends are
fitted with pins and joints, secured with large brass nuts through
the air-pump buckets, with trunks fitted to them, which serve as
guides, instead of crossheads and guide bars. The bottom part of
MARINE ENGINES.
351
the connecting rod has a hole bored up through it, and is fitted
with an internal steel rod which can adjust the bottom brasses with
a screwed key and jib.
In some examples the air
pumps have been placed
vertically, one on each side.
of the centre line of the
engines, having a single
connecting rod from the
crank pin, taking a vibrat-
ing beam placed above the
pumps, to which the buck-
ets are connected at the
ends by rods and guiding
trunks, the point of con-
nection for the main rod
being placed within the
centre line of the forward
E
F

D
E
A
Fig. 225.-Double Air Pump and Condenser, arranged
vertically.
A, Condenser. B B, Air
pumps. cc, Covers for do.
D. Exhaust passage. E E, Hot wells. F, Rocking beam.
pump, whereby less throw is required for the crank on the inter-
mediate shaft. This plan, however, is not so good as working the
pump directly from the shaft, the

connecting rod taking a crosshead
on the air-pump rod, and which is
guided with cast-iron guide frames
bolted to the top of the air-pump
cover.
D
F
D
E
F
14
B
A
Fig. 226.-Single Air Pump and Condenser,
arranged vertically.
A, Condenser. B,
B, Air pump. c, Air-pump cover.
DD, Exhaust passages. E, Discharge passage.
FF, Pillow blocks.
The air-pump bucket head and foot
valves (Fig. 227) are fitted with round
discs of india rubber, working on
suitable gratings cast on the bucket
and valve seats, with the necessary
guards to prevent or limit the lift of
the discs. These valves are intro-
duced to obviate the disagreeable
knocking action felt in all pumps with metallic valves when working
at great speed. Instead of one large disc of india rubber, several
smaller ones have been fitted to the air-pump bucket head and foot
valve, but for slow-speed engines one disc is quite sufficient. In all
pump arrangements doors should be provided to inspect the valves,
without requiring to draw the air-pump bucket; in this respect it is
352
MODERN STEAM PRACTICE.
more convenient to use smaller discs for the foot and head valves,
the latter being placed above the bucket, at the bottom of the hot
well, which is also fitted with a door to admit of occasional inspection.

B
C
E
•
F
D
A

G
A, Head-valve seat.
Fig. 227.-Bucket and Head Valve.
B, Disc of india rubber. c, Guard.
c, Guard. D, Bucket. E, Disc of india rubber.
F, Guard. G, Joint and pin for rod.
Cranked shaft.-As the intermediate cranked shaft in some engines,
more especially those of large power, has caused great trouble, plain
shafts have been substituted, and the air pumps worked by means of
eccentrics. A single eccentric may be adopted for a small diameter
of pump; but when the pump is large it is preferable to have two,
with rods connected to a crosshead, with a single central rod for
MARINE ENGINES.
353
D
taking the joint at the bottom of the trunk. In this way ample
bearing surface is obtained, and the shaft is not so liable to be
fractured as when the strain is re-
ceived on the middle. The eccen-
trics should also be placed as near
the main bearings in the head-
stock or top frame for taking the
shafting as can be conveniently
done, as the strain on the inter-
mediate shaft is thereby better
distributed.
The feed and bilge pumps are
sometimes worked off a double

A
C B
E
Fig. 228.- Cranked Shaft for Air Pump.
A, Cranked shaft. B, Main bearing. c, Bearing
for eccentric. D, Crank pin for air-pump rod.
E, Part for the piston-rod crank.
lever arm, fitted to the end of the trunnions; this plan necessitates
a large diameter of pump, having a very short stroke, owing to the
length of the vibrating arm. This arrangement does not make so

ов с
C
E
A
G
F
Fig. 229.-Feed and Bilge Pumps.
A, Feed
pump.
B, Bilge pump.
c, Rocking arm and rods. D, Plunger and stuffing box.
E, Suction valve. F, Discharge valve. G, Relief valve and spring.
effective a pump as when the stroke is increased, giving less dia-
meter of plunger, which can be readily attained by placing the
pumps on each side of the air pump, and connecting them to the
crosshead fitted to the top of the trunk, when they have the same
23
354
MODERN STEAM PRACTICE.
length of stroke as the air pump. In this case the one acts as the
feed pump, and the other, technically termed the "bilge pump,"
pumps out the water that accumu-
lates in the hold of the ship. The
feed-pump valves are formed either
of metal or discs of india rubber;
but as the bilge pump takes in many
foreign substances, metallic valves of
the flap type are preferable for it.
Such valves answer very well for
moderate speed, but should never be

C
G
A
E
F
D
A
Fig. 230.-Feed Pump.
A, Feed pump. B,
B, Ram for do. c, Pin for taking the air-pump crosshead at one end, and bilge pump
at the other end. D, Suction valve. E, Discharge valve. F, Relief valve and spring. G, Air vessel.
adopted for quick-going engines, as they would soon be knocked
to pieces, and the noise they make at each stroke is far from
agreeable.
The bottom bed plate for taking the trunnion blocks is a light
casting of a T section; the pillow blocks for the larboard and star-
board trunnions are sometimes cast on, and are fitted with brasses
at the top and bottom, like any ordinary pillow block. Holes are left
in the block piece for the main columns supporting the headstock
to pass through, which are fastened by cotters secured through the
casting. This arrangement makes a very stiff and strong bed plate.
The trunnion blocks are sometimes separate, bolted down on
flanges on the bed plate; and the main columns are secured to
MARINE ENGINES.
355
A,
1

D
A
B
C
D
0

Fig. 231.-Trunnion Pillow Block cast on the Bed Plate.
Pillow block cast on frame. B, Cap for do. cc, Bolts for do. D D, Columns for supporting
the headstock.

E
C
D
B
A
E

O
O.
Fig. 232.-Trunnion Pillow Block separate.
A, Pillow block. B, Cap for do. cc, Bolts for do.
the headstock.
D, Frame. E E, Columns for supporting
356
MODERN STEAM PRACTICE.
strongly feathered bosses, and the necessary flanges are provided
for bolting the bed plate to the condenser casting. The frame
should be no larger than what is required for the oscillation of the
cylinder; and the whole is bolted down on the top of wrought-iron
о
O
F
B
•
"
.
*
14
·
P
1
11
A
I
LE
O
C
A
C
Fig. 233.-Headstock.
A A, Headstock pillow blocks. B, Cap for do.
C
C
O
B, Cap for do. cc, Holes for columns.
bearers, securely riv-
etted to the vessel.
The headstock for
the crank shaft is of
cast iron, but in some
instances, where light-
ness is a desideratum,
wrought iron has been
used. For small en-
gines the headstock
casting is generally
of an I section, but
for large ones a box
section is preferable.
It is usually cast in
two halves, bolted at
the centre on the
centre line of paddle-
wheel ships, each half
being fitted with two
pillow blocks cast on,
fitted with brasses at
the top and bottom,
and secured with caps
of cast iron, having
bolts passing down
through the frame.
Bosses for taking the
main columns are cast
along with the head-

stock. These columns are made of wrought iron, and are of suffi-
cient strength to receive the thrust and weight that they are sub-
jected to; and to give greater rigidity between the bed plate and
the headstock, cross stays of cast-iron are introduced on the lar-
board and starboard columns. The headstock is placed between the
engine beams which are made of plate iron of a box section; these
MARINE ENGINES.
357
beams run from one side of the ship to the other, underneath the
deck, and the lateral strain imparted from the headstock is taken on
them, wedge pieces being introduced between them and the cast-
ing. As the strain is fore and aft, these engine beams should be
made broad in the direction of the length of the vessel. The hatch-
way for the headstock cuts the deck in two at the middle of the
vessel where strength is most required, and breaks the continuity
of the deck stringers running fore and aft on the top of the deck
beams to stiffen the vessel; it
is therefore desirable to pass
bolts of large diameter through
the engine beams and head-
stock, by which the frame is
firmly secured to the engine
beams, and as the stringers are
rivetted to these beams the
longitudinal strength is main-
tained.

C
о
B
A
A
The main cranks are arranged
in the usual manner, the crank
pins being firmly secured in
the inner ones; while the lar-
board and starboard cranks are
fitted with brass bushes for the
reception of the ends of the
pins, in which they work quite
loosely, thus preventing any undue stress on the main shaft in a
heavy sea.
Fig. 234.-Main Cranks.
A A, Main cranks. B, Crank pin. c, Bush.
D, End plate.
Piston ring and block.-We now come to notice the piston of the
oscillating engine, which is fitted with a ring on the top, termed the
junk ring. This is introduced to keep the packing ring in its place,
and is bolted down with screw bolts, the brass nuts for which are let
into recesses left in the body of the piston; the heads of the bolts are
flush with the top of the junk ring, and are screwed down with a box
key. The packing ring is generally in one piece; after it is turned on
the rubbing face it is cut at one part and sprung into its place, the
cut part being made steam-tight by a block piece of brass, with
a wrought-iron guard secured to the spring ring at one end, and
moving in a slot at the other end on a guide pin; the brass block
is also secured to the ring at one end, and left loose at the other.
358
MODERN STEAM PRACTICE.
E
The use of this guard piece is to allow a wedge to be driven between
it and the brass block, which contracts the spring ring; the piston
is then placed in the cylinder, and when the
wedge is removed the ring expands and fits
the cylinder exactly. Curved steel springs are
then inserted between the piston and the pack-
ing ring all round; thus with its own elasticity,
and with the aid of these springs, the surfaces
between the piston and cylinder are made quite
steam-tight. All the parts should be carefully
turned, and the surfaces between the junk ring
and the piston scraped; no grinding material
should be used to make this joint tight; in fact
the use of emery for making steam joints, or
for getting up journals, has long been discarded,
as the small particles of grit are sometimes
Piston Ring and imbedded in the metal, and soon play havoc
with rubbing surfaces.

B
Fig. 235.
Block Piece.
A
A, Piston. B, Packing ring.
c, Junk ring. D, Bolt and
recessed nut. E, Block and
guard.
The piston rod is secured by a nut, sometimes
placed at the top, in other cases at the bottom,
square threads for which are cut on the
The nut is sometimes flush with the top of the piston, and is
screwed into the recess by a spanner, fitted with a pin which takes
rod.


C
立
​A
B
Fig. 236.-Top Nut for Piston Rod.
A, Piston. B, Cone on piston rod. c, Nut.
F
B
A
C
Fig. 237.-Bottom Nut for Piston Rod.
A, Piston. B, Cone. c, Nut.
D, Pin.
the holes drilled in the top surface of the nut; a better plan, how-
ever, is to recess the nut partly, leaving sufficient projection so that
it can be tightened up with an ordinary key. Of course the end of
MARINE ENGINES.
359
the piston rod must be turned with a taper, to secure a perfect fit
between the piston and rod. When the nut is placed at the bottom
of the piston it is screwed up against the face ring, and is further
secured by a cotter passing through the rod; this plan is gen-
erally adopted when the crosshead for the crank pin forms part of
the rod. Some makers leave a collar for bearing on the top of
the piston; and with a solid piston rod and crosshead the glands.
require to be cut. The collar, however, may be dispensed with,
as a plain cone is quite sufficient. Recesses must be left in the
cover and the bottom of the cylinders for the securing nut to pass
into.
The crossheads for the piston rod are of various forms. Some are
forged along with the rod, and slotted out for the reception of

B
E
A
D
E
10

B
D
1
Fig. 238.-Piston Rod and Crosshead forged on.
A, Crosshead. в, Cap. cc, Bolts. D, Piston rod.
E, Brasses.
Fig. 239.-Piston Rod and Socket for Crosshead.
A, Crosshead of brass. B, Cap. cc, Bolts.
D, Socket piece. E, Cotter.
brasses, which are secured by means of caps, held down with bolts
passing through the crosshead; others are forged all in one piece,
and are bored out for the reception of the rod, which is held in
position by a cotter; others again have a T piece left on the rod,
or a T bottom piece cottered to the rod, having the brasses cast to
form the middle part of the crosshead, on the top of which is placed
360
MODERN STEAM PRACTICE.
the cap with bolts for screwing up the brasses. An oil chamber
should be forged on the cap and then bored out, or a separate oil cup
fitted with a siphon wick, for lubricating
the crank pin.

The air-pump rod crosshead is simi-
larly constructed, with a T piece formed
on the rod, having brasses and cap with
bolts passing through. The bottom part
of the air-pump rod is generally left
A
Dc

B

D
B
D
Fig. 240.-Air-pump Rod Crosshead.
A, Crosshead of brass. B, Cap. cc, Bolts and
nuts. D, Rod,
Fig. 241.-Air-pump Rod, bottom end.
A, Kod. B, Inside rod. c, Jib and cotter.
D, Bush.
hollow, and is fitted with a steel bar inside, so as to be able to
adjust the wear of the brasses; this plan is of course only adopted
when the bottom of the rod is attached to the pin on the crosshead
placed in a hollow trunk.
The injection valve generally adopted is the simple cone plug (Fig.
242), cast hollow and fitted with a stuffing box at the top, with a
spindle carried up and supported by a round pillar, on the top of which
is fitted an index; a handle is fitted to the spindle for actuating the
plug, which has passages in connection with pipes from the sea for
admitting water into the condenser. Sometimes flat sluices and
gridiron valves are adopted, worked by levers connected to the
valve spindles; others prefer disc valves having spindles through
MARINE ENGINES.
361
↑
the centre bosses left in the valve seatings, and lifted by separate
screwed spindles with turn wheels and handles; and some small
Fig. 242.
Injection
Plug Tap.
A, Plug.
D, Standard.
B, Chest.
E, Handle.
E
valves of this type are lifted by
levers, the short end of the lever
working in a slot crosshead
screwed on the vertical spindle. The pipe placed
inside of the condenser, in connection with the
injection valve, should be perforated with a num-
ber of round holes or slits, so placed that the
water is distributed or showered over a large sur-
face. Some engineers have adopted distributing
plates, perforated with round holes, so that the
water falls into the condenser as in an ordinary
shower bath. We prefer, however, the perforated
copper pipe, which should taper to a smaller dia-
meter at the end furthest from the valve. By this
means the water is more equally distributed; for
were the pipe to be made of equal area throughout
the pressure would decrease, owing to the water
c, Gland and stuffing box. escaping through the perforations, but when the
pipe is contracted from the valve to the end which
is filled up then the pressure is maintained more equally all
along its length.
The Kingston valve (Fig. 243) is fitted to the side of the ship, with
a cast-iron piece between the iron plates and the brass, to prevent
corrosion from the oxidation caused by placing brass in contact with
wrought iron. These valves are fitted to the vessel before it is
launched; they consist of cone valves lifted by means of spindles,
and are held in position by cotters passing through the spindles
and bearing upon columns fixed to the covers; the spindles pass
through these covers, and are made tight by stuffing boxes and
glands. A gridiron is fitted at the bottom of the case or pipe
containing the valve, to prevent extraneous matter entering the
condenser. The use of the Kingston valve is to shut off the sea
water in the event of any of the pipes which supply the engines
getting damaged, in which case, if some contrivance were not
adopted, the sea water would rush in and fill the engine or boiler
room. A plug valve is also fitted to the Kingston valve, so as
to shut off the sea water effectually.
The blow-through valve (Fig. 244) is fitted to the steam pipe, or

362
MODERN STEAM PRACTICE.
in communication with it and the condenser, so that steam from
the boiler may be blown through the condenser and also into the

ID

О
A
E
E
B
Fig. 243.-Kingston Valve.
A, Valve chest. B, Valve. C, Spindle.
D, Cotter. E, Branch piece on ship's bottom.
Fig. 244.-Blow-through Valve.
A, Valve. B, Chest. c, Lifting spindle.
D, Handle. E, Stud.
cylinder, warming these parts and expelling the air; thus by turning
on the injection a vacuum is formed in the condenser, before the steam
from the valve casing is admitted into the cylinder.
This valve is a spindle one, opened with a lever
handle, and is held down by the steam pressure on
the top side.

B
A
Fig. 245.-Snifting
Valve.
A, Valve. B, Chest.
c, Set screw.
The snifting valve is fitted to the lowest part of
the condenser; by it all the air in the condenser
escapes in the process of blowing through. It is
a plain spindle valve, fitted in a valve chest; the
chest and valve are generally of brass, or a cast-
iron chest may be substituted, with a brass valve
seating let into it. The steam in blowing through
opens the valve, and all the air is driven out; but
when the injection is turned on and the vacuum
MARINE ENGINES.
363
formed it instantly closes, and is secured by a thumb screw, passing
through the baffle plate which
is sometimes fitted for throw-
ing downwards the water ex-
pelled from the condenser.
The relief valves, placed at
the top and bottom of the
cylinder, are for the ejection
of the water collected through
priming and from the conden-
sation of the steam. They are
spindle valves, with seats of
the usual form. The valve for
the cylinder cover has a cap on
the top, on which are placed
the spring and top cap, and a

---
A
E
Fig. 246.-Relief Valve on Cover.
E, Baffle cover.
set screw which passes through A, Valve. B, Cylinder cover. c, Spring. D, Set screw.
the cover required to prevent
E
D
the hot water from scattering. The valve for the cylinder bottom is
provided with a long spindle, on the top
of which are placed the cap and spring, and
which is screwed down by a screw pass-
ing through a bow secured to the valve
casing, the baffle plate being fitted under
the bottom cap. In some examples the
valve is cast with a long spindle on the
top of the disc, which passes through a
hollow screw, fitted to a stud placed on
the cylinder; between this stud and the
valve there is a spiral spring with a cap at
the top; by screwing up the hollow screw
against this cap the spring is compressed
to any desired extent; the downward pres-
sure should be slightly in excess of the
steam pressure on the valve, so that when
water collects in the cylinder the piston

impinges on it and forces it through the
A
B
valve into the bilges. A baffle plate must Fig. 247.-Relief Valve for Bottom of
be fitted to throw the hot water down-
Cylinder.
A, Valve and spindle. B, Chest.
D, Bow.
E, Set screw.
wards; and these valves should be placed c, Spring. F, Baffle plate.
364
MODERN STEAM PRACTICE.
at the back of the cylinder or the part furthest removed from the
starting platform, to prevent the engineer from getting scalded by
the steam and hot water. A supplementary plug valve is also fitted
at each end of the cylinder, for allowing the water to escape; these
valves should have a handle common to both, with a pipe connec-
tion for passing the water down to the bilges; in this way the water
can be blown out of the cylinder independently of the loaded spring
relief valves, which are only brought into action in cases of heavy
priming or other serious causes.
The expansion valve, when one is fitted, is placed on the top of
the trunnion pipes at the side of the vessel. This valve is usually
of the double-beat Cornish type, and is a very convenient form,
requiring but little power to lift it. It is raised by a variable cam
placed on the paddle-wheel shaft, having a balanced lever with rod
passing down to the valve; on one end of this lever there is a small
roller, fitted on a spindle between the jaws of the lever, having a
screwed spindle so arranged that it can be turned by hand, moving
the roller to suit the grade of the expansion required. Sometimes,
when a certain grade of expansion is fixed upon, the valve can be
lifted and shut by a rod from a crank pin placed on a wheel driven
off another wheel on the paddle shaft; by moving the pin in a slot
any amount of opening by valve can be obtained, the rod which
B
connects the valve to the pin being fitted
with a right and left hand screw for adjust-
ing the length.
The throttle valve is placed between the
boiler and expansion valve, where an expan-
sion valve is used; but where it is not, the
throttle valve is placed on the top of the el-
bow trunnion pipe (Fig. 221). The valve is of
the butterfly kind, hung equally by a central
spindle passing through it, fitted with levers
and rods passing along to the starting plat-
form. The seat for the valve consists of a
short flanged pipe, with gland and stuffing
box for making the spindle steam tight, the
other end of the spindle having a reduced
pin let into a hole bored in the casting.
This kind of valve is rather troublesome to get up, so as to properly
fill the cylinder in which it works; two pins, one on each side, should

Fig. 248.-Lubricator for the
Cylinder.
A, Oil cup. B, Plug tap. c, Handle.
MARINE ENGINES.
365
be left in the pattern, placed at the angle the valve is designed for,
and the valve can thus be turned to fit the seating exactly.
The lubricating cups should be plain, having pipes passing down
to the bearings, fitted with siphon wicks; and they should have
covers to prevent dirt lodging in them. Some engineers cast the
cups on the various parts, while others prefer light cups cast in
brass. Fig. 248 shows the lubricator cup with hollow plug fitted to
the cylinder cover for lubricating the piston.
SLIDE-VALVE GEAR.
The slide-valve gear for the oscillating engine differs so much
from other arrangements that it requires to be treated somewhat in
detail. The mode of setting out this valve motion has been already


}
-7.52.
B
51/2
5
F
A
24
5½..
D
134;
1.5--
2.11.
The
-3 · · ·×· ·23/4 * · ·
2.5.
Fig. 249.-Slide Valve.1
A, Slide valve. B, Ring for taking off the back pressure. c, Valve spindle. D, Valve casing.
E, Valve-casing cover. F, Cylinder.
described, and although the various plans adopted may differ in
detail, the motion produced is the same in all. Take, for example,
1 ¹ In this section the various figures are diminished as in working drawings for the
workshop.
366
MODERN STEAM PRACTICE.
the case of a marine engine having a cylinder 4 feet 3 inches in
diameter, and length of stroke 4 feet. The short D slide valve is
usually adopted, with a packing ring on the back of the most
improved description. The ports in the cylinder are not nearly so
short as for direct-acting engines having the multiple-ported arrange-
ment. There is a port at the top and bottom for the steam, in
connection with one half of the passage or the belt cast on or about
the centre length of the cylinder; the trunnion or pipe on which
the cylinder oscillates is cast on the centre line of the belt. The
outside one, or the one nearest the ship's side, in paddle-wheel
engines, is for the steam, and the one nearest the centre line of the
vessel is for the exhaust into the condenser, being in communication
with the central ports on the cylinder. The slide valve is contained
in a suitable casing bolted on the cylinder, and provided with a
movable cover at the back. The inside face is planed and scraped
perfectly true, so that the slide rings are steam-tight; there is a
small hole bored in the back of the valve to take away any steam
that may pass, which of course finds its way into the condenser.
There are generally two valves, one on each side of the cylinder;
such an arrangement not only reduces the size of the ports, but
also balances the cylinder better. When one valve is used, a coun-
terpoise weight, fixed on a lever, is attached to the cylinder, and
oscillates with it; but such a plan, when adopted for large power, is
neither so neat nor so compact as the double slide valves, although
these require more working parts. At the same time, when two
valves are used, the details can be made much lighter, as the area
of each valve is much less. The usual mode of securing the valve
spindle to the valve is by a T nut let into the valve, having a cor-
responding thread on the valve spindle, with a jam nut to secure it
in its position; and in other arrangements a snug is cast on the
valve, with a hole for the reception of the valve spindle, having
nuts at the top and bottom. The centre of the exhaust port and
trunnion may be taken as the starting point for setting out the
valve faces, their place being the centre line of oscillation of the
cylinder. The opening of the port by the valve is found by the
same rule as that used in other arrangements. Thus, suppose for
the cylinder 4 feet 3 inches in diameter, with stroke of 4 feet, the
number of revolutions is 28224 feet of piston speed per minute:
we have therefore—
2042 × 224
10000
= 45'7 square inches,
MARINE ENGINES.
367
which, divided by 2, equals 22.8 square inches of opening of port
by valve for each. The length of the ports is found by dividing
the diameter of the cylinder by 34, thus: 51÷3'4=15 inches long;
and 22.8÷15=1.52 inch, the opening of port by valve. The
combined area of the steam ports equals th, and that of the
exhaustth of the area of the cylinder: thus-
2042
25
2042
13
1
25
= 81·6 ÷ 2 = 40·8 square inches in steam port;
= 157 ÷ 2 = 79 square inches in exhaust port.
Dk…….10
it
out
Ja
A little more or less may be allowed to secure even dimensions.
Throw of eccentric, slide gear, &c.—The oscillating engine differs
from all others in having reciprocating pistons, and no connecting
rod, the piston rod and crosshead being attached directly to the
crank pin. We may, however, term the
distance from the centre of oscillation to
the crank centre the length of the con-
necting rod, as from A to B, and with this
length as a radius, from the point B sweep
the crank path, this radius is the length
of the supposed connecting rod when the
piston is at half stroke. It will be seen
that this length varies, being greatest
when the rod is vertical, the piston com-
mencing the IN stroke, and rapidly short-
ening as the piston descends, until the
crank pin reaches the bottom of the crank
path, when the length will be simply the
vertical height from B to OUT, or the com-
mencement of the up stroke. It will thus
be evident that the radius for finding the
correct angle of the crank for cutting off
at any part of the piston stroke varies.
To explain this more fully: Divide the
vertical diameter of the crank path from
IN to OUT into eight equal parts, fix the
point of the compasses at the point of
oscillation as at B, the vertical distance to
any point that may be determined on for cutting off the steam, say
at five-eighths of the stroke of the piston, as from IN to OUT, is the

Centre of
B
Oscillation
Fig. 250.--Path of Crank.
368
MODERN STEAM PRACTICE.
radius that determines the point C or centre of crank pin, when the
steam is cut off at five-eighths of the piston stroke. Thus the versed
sine of the chord of the arc of supply to the cylinder can be found,
namely, D E, which measures nearly 10 inches. The diameter of
the circle described by the centre of the eccentric can also be now
found, as already described for direct motion; but as the lever for
taking the valve spindle may be shorter than the one for the slot
link, it is evident that the eccentric circle must have a greater
diameter. Supposing this is the arrangement adopted, and the
length of the lever for the valve to be 12 inches, and that for the
slot link 15½ inches (those lengths can be only determined by
laying down in plan the valve and gear). When it is known that
the versed sine of the chord of the eccentric circle for the arc of
supply is the full opening of the port by valve minus one-half of
the lead, we have the following, supposing the lead to be th part of
an inch: The full opening of the port by valve as already found is
15 inch minus inch=1468 inch as the versed sine of the chord
of the arc described by the eccentric circle for direct motion. The
diameter of the crank circle is equal to 48 inches, and the versed
sine of the chord of arc of supply is 10 inches. We have therefore
10:48: 1468-7.04 inches diameter of eccentric circle for direct
motion, or for levers of equal length; but as the levers for working
the valve are of unequal length, we have 7'04:12::15°5=9′01
inches diameter of the eccentric path or full travel of the valve.
Eccentric and hoop.-The eccentric is cast in two halves and bolted
together, for the convenience of taking it to pieces or placing it on
the shaft. Were the eccentric placed on a plain shaft at the end,
with nothing to interfere, it would be cast all in one piece; but as
it is generally placed between collars turned on the shaft, at the
side of the main cranks, the ring requires to be in two halves. The
eccentric sheave revolves freely on the shaft, and has a catch cast
on it, with a corresponding catch fixed to the shaft, so as to suit the
forward and backward movements. The eccentric sheave is also
fitted with a back balance, so that when the engine is reversed by
hand, the eccentric rod being out of gear and the sheave being
loose on the shaft, the latter is perfectly balanced, and prevented
from revolving when the catch is not driving it. This is most
required for engines of great power, where the sheaves being
large would turn rapidly round, and being met by the catch would
impart a smart blow, tending to disarrange the gear. For small
MARINE ENGINES.
369
power the eccentric is fitted with a brass hoop, bolted together, for
taking the eccentric rod, and large engines have the hoop forged

B
3 3/4
D
23.
2030
11/2
C
4/12...10
A
25 7/8
..... 104
Fig. 251.-Eccentric and Hoop.
A, Eccentric. B, Hoop for do. c, Catch. D, Balance.
on the eccentric rod, and lined with brass pieces at intervals. The
siphon cup for lubricating the sheave is either cast on the brass
hoop, or is separate, as when the hoop
and rod are forged all in one piece.

Ahead
K
Aster
H
Catch on shaft. To determine the
position of the catch on the shaft to suit
the forward and backward movements;
the position of the eccentric centre for
the forward movement being directly
opposite to that for the backward move-
ment. Draw A B, the line of crank, and
describe the circle in dotted lines equal
to the throw of the eccentric; then find
the versed sine of the chord of arc of
supply, and the point E can be fixed,
that being the centre of the eccentric
for the forward movement; from the point E draw a line perpendi-
cular to A B, and produce it until it cut the eccentric path on the
opposite side, that is the point or centre of the eccentric for the
I
Fig. 252.-Catch for Eccentric on Shaft.
24
370
MODERN STEAM PRACTICE.
backward movement. Draw the line A E, which is the centre line
of the catch on the eccentric sheave, which is set off equally on
each side as represented in section, F is the forward end of catch,
and G the end of catch for the backward movement. The driving
catch on the shaft, represented in black, is secured by bolts. It will
be seen that the line of crank is so much in advance of the point
on the end of the catch on the eccentric at G, for the forward move-
ment; and that it must be so much in advance of the point F for
the backward movement. Thus, supposing the catch on the eccen-
tric were stationary, and the crank free to go backward to the line
represented at A I, it would travel through an arc the distance from
H to G, when it would be down, and the catch on the shaft would
be moving the eccentric the contrary way from the direction shown
by the arrow, and the crank turning the paddle wheel astern. It
A
10¼
4,0
k-28
A
A
7%
70%
2/4
3
25/5
B
·
will be seen that the catch
on the eccentric sheave is
placed so that the driving
catch embraces one-half of
the circumference of the
shaft, although at times it
may be less, owing to the
length of the catch on the
eccentric; but when conve-
nient this position of the
driving catch on the shaft is
to be preferred. Thus, when
the line of crank A B is in
the position delineated, it
will move in the direction of
the arrow when the end of
the catch at F is the driver;
but when the end of the
catch at H becomes the
driver, it must move in the
contrary direction. The
catch on the eccentric is re-
presented by dotted lines:
the line of crank is equidis-
When the engine is required to
move either forward or backward, the slide valve is worked by





"
24
Fig. 253.
2.
k..
3314...
Eccentric Rod and Socket.
A, Eccentric rod. B, Socket and pin.
tant from the points G and K.
B
MARINE ENGINES.
371
hand, and the eccentric accommodates itself to the catch fixed on
and revolving with the main crank shaft.
Ꭺ
B
(16)
T
-514-
78%
2-
+234-
Di
**
7
73%
58
C
Eccentric rod and valve gear.-The eccentric rod in this example
(Fig. 253) is a plain round bar, with a T end for taking the eccentric
strap; the end for taking the slot link passes through a long guiding
piece, oscillating on the link through a hole having a brass bush.
Some-indeed we may say the most-are arranged with a plain gab
end, that is thrown out of gear when the engine or rather the valve is
worked by hand; but
in this arrangement
the rod always slides
in the socket, and is
thrown into gear with
a plain round pin pass-
ing through the socket
in which the rod slides.
The plain gab end,
however, is usually
considered preferable
for large engines. The
valve rod is attached
to the lug cast on the
valve by a screw cut
on the end, with nuts
on the top and bottom,
which are screwed up
against the lug on the
valve. The top end
has a slot fitted with
a sliding block; a pin
passes through the
block, and is secured
through the eye on the
rocking lever. The
valve rod is guided at
the top by means of Fig. 254.-Valve Rod and Guide. Rocking Levers and Stud.
a bracket fitted to the A, Valve rod. B, Block for do. 'c, Guide for do.
D,
Lever for
valve. E, Lever for eccentric rod. F, Stud for levers.
cylinder. There are
two rocking levers for each valve: one has a slide block working in
the slot link, with a radius suited for the valve gear when placed at

་་
1%
D
2/26
F
2%
E
.752
O
372
MODERN STEAM PRACTICE.
half stroke; the other lever, as before stated, takes the slide valve.
rod. When the slide is at half stroke, the valve covering all the ports,
the distance or vertical height from the centre of oscillation to the
slide rod pin is the position in which the rocking levers are level.
The sliding blocks on the slot link are placed slightly apart, and
from the centre of the trunnions on which the cylinder oscillates to
the centre of the sliding block pins is the radius of the link. The
rocking levers for taking the slot link and valve spindle oscillate
434
4%
C
B
44
C
on a fixed centre or pin fitted to the
cylinder, the rocking centres on levers
being bushed with brass. This bearing
is usually in the form of a pillow block,
bolted to a bracket cast on the cylinder;
the journal and covers are forged all in
one piece, the bearing being in the middle
with the levers on each side. The radius
of the slot link, as before stated, is the
vertical height from the centre of the
trunnions to the centre of the pins on the
levers, when the valve is placed at half
stroke, the levers lying level. The ends
of the slot link are fitted with brass guid-
ing pieces, one of the guides having a
rack or teeth cast on, working into a
pinion fitted to the starting-wheel shaft.
These guides are hollowed out to slide on
and between the wrought-iron columns
for supporting the crank-shaft framing.
A, Sector and rod. B, Hole for socket. The slot link is likewise guided at the
top, a small bracket being bolted to the
headstock, through which the round part of its shank slides. The
length of the slot link must be determined from the angle of oscilla-
tion at half stroke, and the necessary clearance for the sliding blocks
on the levers must also be allowed for. The centre of oscillation of
the socket for taking the eccentric rod has a brass bush fitted to the
slot link, but when a gab end is used a plain pin is simply fastened
to the link.

65%
2.5½.......
Fig. 255.-Sector and Brasses.
c, Lifting rack.
Starting gear.-For working the slide valve by hand, in engines
of small power, a long lever handle is attached to the wrought-iron
columns; this lever is fitted with a link, connected to the slot link
MARINE ENGINES.
373
by means of a pin; the handle vibrates with the upward and down-
ward motion of the sector, and the eccentric rod, fitted with a gab,
is thrown out of gear by a small lever and rod, so placed that it
tends to keep in the gab when in gear, and prevents it falling into
gear when thrown out. In some examples springs and catches are
used for the same object. Sometimes the lever handle is adopted
for heavy engines, in which case it is advisable to have a socket, so
as to detach the handle when the engine is working; but the better

C
D
2/2
32
3
E
1
1/2
75/2...
2/2
.1
450
Fig. 256. Starting Gear.
A, Starting wheel. B, Bracket. c, Pinion-rod shaft. D, Column. E, Throw-out handle.
plan is to have this part of the gearing arranged so as to be able
to handle the valves at the shortest notice. A very general arrange-
ment is by means of a pinion, working in a rack placed on one of
the guides that is bolted to the sector or slot link; on the other
end of the shaft for carrying the pinion is placed the starting wheel.
In the example before us, the starting wheel has four arms, with a
central boss, which is keyed on the shaft. The pinion is thrown
in and out of gear by a lever, the same motion disengaging and
putting in gear the eccentric rod. A spring detent is fitted through
374
MODERN STEAM PRACTICE.
a slot on the throw-out handle, a rod being attached to it and the
pin which passes through the socket on which the eccentric rod
slides. This arrangement of starting gear is certainly very compact,
although for heavy engines we prefer the plain gab on the eccentric
rod. The bracket for carrying the starting wheel, &c., for small
power, is generally bolted to the columns for carrying the head-
stock.
THE LINK MOTION.
The application of double eccentrics and link motion to the
oscillating engine affects but little the general arrangement of the
valve gear. The pin on the sector for taking the gab end of the
eccentric rod, as for the single-eccentric arrangement, is used for
the block on which the link slides; in fact, this pin and block
may be compared to the pin and block on the slide-valve rod,
in the direct applications of the link motion to the locomotive, or in
horizontal direct-acting marine engines. Indeed, the oscillating
engine may be considered a direct-acting engine, whether set verti-
cally, horizontally, or lying at an angle; but as levers are interposed
between the sector and valve spindle, the motion becomes indirect.
As the sector always moves in a direct line similar to the slide-
valve spindle in horizontal arrangements, and as the pin for taking
the block on which the link slides is fitted directly to the sector, it
only remains to consider the application of the double eccentrics
and link motion from this point to the centre of the main crank
shaft. Thus when the levers are placed horizontally or at right
angles to the valve spindle, the slide valve being at half stroke,
then from the centre of the pin on the sector to the centre of the
main crank shaft is the radius for describing the link, to which the
double eccentrics and rods are fitted in the usual manner. So it
will be understood that the double eccentrics, keyed fast on the
crank shaft, having rods and link working directly in a line with
the slot link or sector for taking the levers for actuating the slide-
valve spindle, simply take the place of the single-eccentric rod and
gab end, having means of throwing out and also of actuating the
valve by hand, to suit the direction required for the forward or
backward movements. The link, however, being attached to eccen-
trics for both the forward and backward motions, the combin-
ation of both can never err (with proper mechanism for moving it
on the block which oscillates on the pin attached to the sector) in
MARINE ENGINES.
375
actuating the valves as required. The valve mechanism of oscillating
engines, in combination with the link motion, is beautifully simple
in its multiplicity of parts, and in the science of engine-building it
may be truthfully regarded as the perfection of valve gearing. It
must be borne in mind that, although the positions of the centres
of eccentrics are the same in relation to the centre line of crank as
for direct motion, yet as the lever for taking the sector must move
upwards, to depress the one for taking the valve, the positions of
the eccentrics on the eccentric path are different, that for the oscil-
lating engine being on the circumference of the path nearest the
crank pin, while for direct action the centres are on the opposite
circumference of the eccentric path. The mechanism for actuating
the links acts simultaneously, and a very general arrangement is to
have a thread cut on the shaft for taking the starting handle, fitted
with a crosshead working in suitable guides, the centre of the cross-
head being bored out and screwed to suit the thread on the shaft.
At each end of the crosshead there is a part turned for the reception
of side rods, connecting the crosshead with the main links. Thus
by turning the starting wheel in either direction, the crosshead, side
rods, and links are moved in the direction required. The bracket
for carrying the starting-wheel shaft and for guiding the crosshead
is cast all in one piece, and is fitted to the condenser on the centre
line of the ship, as for paddle-wheel arrangements. This motion
for actuating the link has the advantage of holding it in any position
when at work, without the aid of set screws or any other appliance,
which is a great desideratum when the link is used for working
expansively. In some arrangements the starting wheel and shaft
actuate a crosshead, generally cast in brass, on which lugs are
formed for the reception of a single central rod, which takes a lever
on a cross shaft, vibrating on two pillow blocks. On each end of
this shaft a lever is fitted, having a pin and rod in connection with
each link; thus motion is imparted, and the link put in forward or
backward gear as required. In other arrangements the crosshead
and guides are dispensed with, and a worm wheel substituted, which
is placed on the end of the starting-wheel shaft, and works into a
pinion placed central with the cross shaft, having levers and rods
in connection with the link, as already described. Sometimes the
bracket for carrying the starting-wheel shaft in this arrangement
is simply a pipe bushed at each end, cast along with the hot well,
to which the cross shaft has pillow blocks also.
In fact, the main
376
MODERN STEAM PRACTICE.
thing to be studied in the mechanism for actuating the link motion
is the side rods for taking the link: let them be of sufficient length,
so that the versed sine of the chord of the arc of oscillation may
not affect the link in relation to its block; because, when they are
made too short, a sliding action takes place, which in some instances
seriously affects the proper working of the valve. When this point
is duly attended to, power has only to be applied to the lifting or
reversing rods, and the mechanism for applying this power should
in all cases be as simple as possible. For small engines, a cross
shaft with pillow blocks cast on the condenser, and having levers
and rods at each end, actuated by a plain lever handle, and with
quadrant and catch similar to the locomotive engine, is as good an
arrangement as can be adopted.
The link generally used is of the solid type, slotted to receive
the block on the sector, all of which are made to the proper radius.
The lugs for taking the eccentric rods are forged on, but in some
instances lugs are wanting, and the rods are simply attached to the
ends of the link. The former is the better arrangement, as the pin.
on the eccentric rod is nearly in a line with the pin for taking the
link block, thus direct motion is obtained; while in the latter
arrangement, the eccentric rod pin is all to the one side, and in
addition a larger eccentric sheave is required, which is not desirable.
The pin on the link for taking the lifting or reversing rods is placed
midway between the eccentric-rod ends, on the radius line of the
link, and it is forged on a cross bar secured to the link by rivets.
In some cases the eccentric-rod straps are forged along with the rods,
having a lining of brass, and are secured on the eccentric sheaves
with bolts and nuts; in others they are cast in brass, and the rod
attached by means of a T piece forged on the end, with suitable
bolts and nuts, lock nuts, and securing split pins. The eccentric
sheaves are cast in two pieces, accurately fitted together, and bolted
similarly to the sheaves for single-eccentric arrangements; this is
done for the convenience of getting them on or off the shaft, but
where circumstances will allow of it, the sheaves are better cast in
one piece, which simplifies the manufacture.
MARINE ENGINES.
377
SPECIFIC NOTICES OF MARINE ENGINES.
The oscillating engines of the Great Eastern are the largest yet
made, there being four paddle cylinders of 74 inches diameter and
14 feet stroke; the diameter of the paddle wheels is 58 feet.
The oscillating engines of the Clyde river steamer Columba are
probably the largest yet used in any river steamer, each of the
two cylinders being 53 inches in diameter, and the stroke 5 ft. 6 in.
The Lord of the Isles, another large Clyde river steamer, has two
diagonal oscillating cylinders, working on the same crank pin. The
diameter of these cylinders is 46 inches, with a 5 feet 6 inches
stroke. These steamers are fitted with surface condensers.
In the Post Boy, a vessel of 65 tons and 20 horse-power, built on
the Clyde in 1820, the late Mr. David Napier appears to have tried
a surface condenser, consisting of a series of small copper tubes
through which the steam passed, and was condensed by a circulation
of cold water on the outside of the tubes.
The Fairy Queen, the first iron steamer plying on the Clyde,
launched in 1831, had an oscillating engine.
The steeple engine, first introduced on the Clyde about 1836 by
Mr. David Napier, is a convenient form of engine for river boats.
It consists essentially in an overhung triangular frame from the
crosshead, on which hangs the connecting rod. This frame and
rod are connected with the piston by either one or more piston
rods. In the earlier forms one rod was commonly fixed to the
lower part of the triangular frame, in other forms two and often
four piston rods are used.
The side-lever engine was extensively used in paddle-wheel
steamers, the arrangement being very much that of an inverted
beam engine.
The first paddle steamer to cross the Atlantic from Britain was
the Sirius, built at Leith in 1837, and engined by Messrs. Wingate
& Co. of Glasgow. The Great Western, built at Bristol, also made
the passage, the two arriving in New York about the same time.
The Sirius measured 178 feet long by 25 feet 8 in. beam, depth
18 feet 3 in., and was 450 tons register. She was fitted with two
side-lever engines of 270 horse-power; diameter of cylinder 60 in.,
stroke 6 feet; paddle-wheels 24 feet diameter with twenty-two
floats, and appears to have had Hall's surface condensers.
The Cunard steamer Scotia, the last great ocean-going paddle-
378
MODERN STEAM PRACTICE.
wheel vessel built, was fitted with a pair of side-lever engines, the
diameter of cylinders being 100 inches, with a stroke of 12 feet.
The diameter of paddle wheels was 40 feet.
A specimen of the early side-lever engine may still be seen placed
on a pedestal at Dumbarton pier on the Clyde. It is the first marine
engine made in 1824 by Mr. Robert Napier, the well-known Clyde
engineer, for the steamer Leven.
Trunk engines were introduced by Penn, and have been much
used in H.M. navy. The piston rod is made hollow, and the connect-
ing rod being centered well down in it a saving of room is effected.
A form of engine now common on Clyde river steamers is the
diagonal direct-acting. In these engines the piston rod is attached
to a crosshead working in slides, and from this crosshead the con-
necting rod stretches to the crank pin. It may be of interest here
to state that the first efficiently steam-propelled vessel, the Char-
lotte Dundas, was fitted with a horizontal direct-acting engine; this
vessel was tried successfully on the Forth and Clyde Canal in 1802.
In many of the earlier steam vessels, from the Comet downwards,
spur-wheel gearing was used to connect the engine with the paddle
shaft. A few details of the size of the Comet may be interesting.
She was about 25 tons burden, and was built for Henry Bell in 1812
by Mr. John Wood of Port-Glasgow. She measured 42 feet long,
40 feet keel, and II feet broad, with 5 feet 6 in. draft of water.
The engine, made by John Robertson of Glasgow, was a condensing
one of 3 horse-power, the diameter of cylinder being 11 inches, and
the stroke 16 inches, the crank working below the cylinder; the
engine-shaft, connected with a fly-wheel, is said to have been of
cast-iron, and 3½ in. square. The engine was fitted on board before
launching and steam raised. At first the Comet was fitted with
two pairs of paddles, 7 feet diameter, with spur-wheels of 3% feet
diameter; but soon afterwards she was lengthened to 60 feet, and
a new engine with a single pair of paddles substituted, the speed
being now greatly improved, and reaching from five to six miles an
hour. The diameter of the cylinder is stated as 12½ inches and
the horse-power 4.
THE PADDLE WHEEL.
The paddle wheels now in use are generally of the feathering type,
the floats entering and leaving the water almost vertically; having thus
a better hold of the water than the fixed floats, which enter obliquely,
MARINE ENGINES.
379
o
0 0 0 0
and whose full propelling area is only attained when the arms to
which they are bolted are vertical. Thus when fixed the floats
depress the water on entering, and tend to lift it when leaving, and

•ՈՎ
0....
B
B
B
Float.
D,
B B, Arms. C, Rim.
HH, Stays. II, Brackets. K, Eccentric bolted to the ship's side.
Figs. 257, 258.—Feathering Paddle Wheel, with outside bearing.-A, Paddle-wheel centre boss.
E, Arm for float. F, Driving rod. GG, Radial rods.

to obviate this difficulty each float was formerly stepped, or made
in two or more separate pieces, placed one before another. This
plan, however, is now become almost obsolete; the feathering floats,
although somewhat complicated, being generally adopted for all
380
MODERN STEAM PRACTICE.
fast river steamers, and the screw superseding the paddle wheel
almost universally for ocean-going steamers.
To understand the action of the feathering paddle wheel we have
to consider each float free to oscillate on pins passing through
brackets forged on the paddle arms; on one of these journals an
arm is fixed, and a rod for each float is attached to a pin on the
end of each arm, the arms being all con-
nected to a strap (Fig. 259), which is free
to revolve on a sheave (Fig. 260) placed
B

C
C
eccentrically with the main shaft. One


O
A
A
A
Ά
B
IT
Fig. 259.-Eccentric Strap.
A, Strap with brass lining pieces. B, Seat for
driving rod. cc, Holes for radial rods.
Fig. 260.-Eccentric Sheave for Paddle Wheel.
A, Eccentric. B, Flange for bolting it to the ship's
side.
of these connecting rods is the driver, and is firmly secured to
the eccentric strap in a way similar to an eccentric rod for the
valve motion. When the paddle wheel is overhung, with one
B
A
B
pillow block at the side of the
vessel, this bearing being support-
ed with a wrought-iron bracket
rivetted to the side of the ship, the
eccentric sheave is secured at the
end of the pillow block; and when
the paddle wheel is supported with
an outside bearing bolted to the
sponsons, the eccentric sheave is
bolted to the side of the ship direct.
In setting out the mechanism,
we consider the position of the
driving float, as we may term it; at its deepest immersion it is
quite vertical, and as the rod from the arm that is fixed on the float
is secured to the eccentric strap, as the paddle wheel revolves the


Fig. 261.-Boss for Paddle-wheel Arms.
A, Boss. BB, Seats for arms. c, Wrought-iron ring.
MARINE ENGINES.
381
eccentric ring is dragged round, and the driving float always assumes
that vertical position at the deepest immersion, as indeed do all the
other floats, the only difference being that they are secured to pins
on the eccentric strap, instead of being firmly bolted to it; thus
when the centre line of the eccentric is placed on a level line, all
the floats assume different angles, but at the same time each float
enters the water in a slightly oblique direction, and leaves it verti-
cally. It is obvious that the floats must not be placed too closely


Ό
оо
A
D
оо о
C


E
F
о
F

Fig. 262.-Arm and Brackets for Floats.
A, Arm and bracket. B, Pin and brass bush. c, Brass bush. D, Bracket. E, Pin and brass
bush. F, Bracket.
together, three immersed at one time is considered sufficient; if
closer packed they only disturb the water and clog the action of
the wheels. Some builders prefer simply an eccentric or a circular
sheave (Figs. 264 and 265), revolving on a pin firmly secured to the
sponsons, and fixed aft of the centre of the paddle shaft in a hori-
zontal line; the sheave is formed of two flanges, with a projecting
piece for the driving arm, and pins for all the other rods: in action
this form is similar to the foregoing. All the moving joints must
be bushed with brass, both on the pins and eyes, to preserve and
keep fair the various joints; unless this is properly attended to
corrosion would set in, and soon destroy the feathering paddle
wheel.
The pillow block for the overhung paddle wheel is a plain casting
fitted with a cap, the bolts for securing which pass down through
382
MODERN STEAM PRACTICE.




A
B
о
B
B
A
A
B
о
Fig. 263.-Eccentric rod, &c., for Floats.
A, Driving or eccentric rod. B, Radial rod.
B
B
E
C
D
E
Fig. 264.-Eccentric and Pin for Paddle Wheel.
A, Eccentric.
B, Part for driving rod. c, Pin for
radial rod. D, Bracket bolted to the sponson.
E, Pin for eccentric.

I
G
G
I I
H
A
Fig. 265.-Overhung Feathering Paddle Wheel.-A, Boss. B B, Arms. C, Rim. D,
D, Float. E, Arm for
float. F, Driving rod. GG, Stays. H, Eccentric and pin bolted to the sponson. II, Brackets.
MARINE ENGINES.
383
the bracket fitted to the side of the ship; the sole of the block is
also bolted to the bracket, as shown in Fig. 266.
C
C
B
A
In some ocean steamers the paddle-wheel shaft was arranged so
that it could be disconnected from the engine when the ship was
under sail alone. The simplest plan for effecting this is by fitting
a disc on the end of the shaft, instead of the usual crank, the disc
having a hoop with a projecting
lug piece for taking the crank
pin; the hoop is forged all in one
piece, and is held in position with
a fast-and-loose collar on the
round disc; the grip is attained by
friction blocks, or wedges, firmly
screwed between the disc and the
hoop on the circumferential line,
the disc being keyed to the shaft
with one or more keys. There-
fore when the friction blocks
are released, the shaft and disc
revolve independently of the
engine, the motion of the vessel
through the water, driven by the
sails, causing the paddle wheels to
revolve. In this way the progress
of the vessel is not impeded so
much as it would be were the floats stationary, and offering a great
resistance for the wind to overcome.

curve.
Fig. 266.-Pillow Block for Paddle Wheel.
A, Pillow Block. B, Cap for do. cc, Holding-down
bolts.
The paddle wheel of a ship may be compared to an ordinary
carriage wheel, any point in the circumference describing a cycloid
The circumferential distance a carriage wheel travels over
is an exact measure of the distance the carriage has gone; but as
the paddle wheel acts in a yielding fluid, the distance travelled
over by it is not an exact measure of the vessel's progress through
the water. The difference is termed the slip of the paddle, and
ranges from one-fourth to one-fifth of the circumferential distance
the paddle wheel has gone over, which of course must be measured
on the mean centre of propulsion of the floats, and not on the
extreme diameter.
The reciprocating parts of marine engines are generally balanced
with suitable weights, and notwithstanding that the cylinders of
384
MODERN STEAM PRACTICE.
the oscillating engine are properly balanced, yet the pistons and
cranks must be also balanced by a metal float fitted on each paddle
wheel, although that is partly done by the air-pump bucket and
its adjuncts, the crank of which divides the path of the main
cranks into three parts-that is to say, the cylinder cranks being
at right angles, the line of the air-pump crank divides the longest
circumferential line between the main crank pin centres into equal
parts.
The feathering paddle wheel was tried at various times, but not
with much success till about the year 1850. Fixed floats were
mostly used in ocean-going steamers, being considered less liable to
derangement.
Two pairs of paddle wheels have been proposed to be used.
The Comet had at first, as we have said (p. 378), two pairs, but
these were removed, and a single pair substituted. Single wheels
at the stern and amidship, as in twin-boat arrangements, have also
been tried, as also endless chains with floats attached, passing round
a couple of drums driven by the engine. Iron floats have some-
times been used instead of wood floats in paddle wheels.
Besides the screw propeller, to be afterwards treated of, the
propulsion of vessels by a jet of water has been tried. This con-
trivance is known as "Ruthven's Hydraulic Propeller," and consists
of a turbine-like wheel driven by a steam engine. The water is
first of all drawn in by the turbine, and then driven out at openings
along the ship's side in such a manner as to keep up a constant
stream. A vessel named the Nautilus, furnished with Ruthven's
propeller, had a trial trip on the Thames in 1868. She ran at
the rate of 135 and 72 miles per hour with and against the tide
respectively, or at an average speed of 10'35 miles per hour; and
when going at full speed, with both wind and tide in her favour, she
was made, by reversing the valves, to stop dead in less than ten
seconds and in about a quarter of her length. The plan has also
been tried in H.M. iron-clad gun-boat Waterwitch, of about 780 tons,
with some success. It has also been tried in the United States of
America, but without commending itself as against either the
paddle or the screw.
It should be noted in all questions of propulsion that the principle
involved is the putting in motion of a quantity of water in a back-
ward direction, the reaction from which action is the propulsive
effect. Professor Rankine gives the following rule for the thrust
MARINE ENGINES.
385
of a propeller, whether paddle, screw, or jet, in lbs.:-" Multiply
together the transverse sectional area in square feet of the stream
driven astern by the propeller; the speed of that stream relatively
to the ship, in knots; the real slip, or part of that speed, which is
impressed on that stream by the propeller, also in knots; and the
constant 5'66 for sea water and 5'5 for fresh water."
HORIZONTAL DIRECT-ACTING AND RETURN
CONNECTING-ROD ENGINES.
In these engines the cylinders are placed side by side, as in the
locomotive engine, and the steam valves are worked directly off
the cranked shaft by double eccentrics and link motion. The
condensers are placed on the opposite side of the shaft for return
connecting-rod engines; they are fitted with guides for the cross-
heads; the piston rods are secured to arms forged on the crosshead,
and are so arranged for the rods crossing the cranked shaft, one above
and the other under the shaft. The connecting rod by this arrange-
ment is not in a direct line with the piston rods, but goes backwards,
while the piston rods are connecting to the piston in a forward line
crossing the main shaft of the engine.
The distance between the centres of the cylinders in these engines
is regulated by the arrangement of the air pumps and valves. When
the air pumps are close together on each side of the centre frame,
the distance between the centres is greater than when the air pumps
and adjuncts are placed further apart, close to the outer frames;
however, it is not a good plan to contract the water passages in
connection with the air pumps and condenser to gain a few inches
between the centres of the cylinders. Steam jackets are generally
used, cast along with the cylinder; the fronts and cylinder covers
are also made double, so that the steam from the boiler freely
circulates all round the cylinder, and the full pressure is better
maintained on the piston, a higher indicated measure being given out
than by an unjacketed cylinder. To prevent condensation in the
steam casing the outside of the cylinder should be covered with
felt, and then overlaid with lagging or narrow strips of wood, which
are secured to wooden hoops, bolted to the strengthening ribs left
in the casting. The passages for the steam and exhaust are arranged
25
386
MODERN STEAM PRACTICE.
for double-ported valves, that is to say, there are two steam
passages at each end, and one central passage, in communication
with the condenser. The joints should be placed metal to metal,
all planed or surfaced in the boring lathe, and the rubbing surfaces
A
Figs. 267-268.-Cylinder.'


E
O
for the slide valve should also be carefully
planed as smooth as possible, and then
scraped to a face plate, before the slide
valve is fitted, which should also be care- e
fully faced on the plate, and thus both
surfaces will only require a finishing touch.
All the other joints are made steam-tight
by interposing a thin coating of red lead.
The joints being thus metallic, the work-
ing of the engine has but little tendency
to loosen them, which might otherwise
happen were an elastic joint adopted. On
D

D
C C
the front end of the cylinder a central manhole must be left, for the
boring bar to pass through; with single piston rods there is a small
cover with stuffing box and gland, but with double or more piston
rods a plain cover is fitted; holes are also left in the front end of the
cylinder for the air-pump rod, with suitable glands and bushes, and a
hole at the bottom for the relief valve; narrow fitting strips should
be left at those parts where the main framing abuts against the
other fittings. The cylinders are bolted together, with flanges placed
between them, having narrow fitting strips all round, which are care-
fully planed; all the holes should be drilled, and rimed out to make
1A, Cylinder. B, Annular steam space. cc, Steam ports. D, Exhaust port. E, Exhaust branch.
F F, Piston-rod glands. G, Cover for hole for boring bar.
MARINE ENGINES.
387
them quite fair; by this means the turned bolts fit the holes
exactly, and good firm work is obtained. The flanges at the top
and bottom are planed, and the latter are cast along with the
flanges for bolting down the cylinder on the keelsons. Raised parts
should be left on the casting at all the places where the bolts are
arranged; in this way an even face is easily made for screwing the
nuts up against, which helps to secure first-rate work.
The cylinder cover should be a deep and strongly-ribbed casting,
fitted with a central manhole door, through which the bolts of the
piston and piston rods may be inspected without requiring to break
the joint of the cover, which is a somewhat difficult task at sea,

о
O
о
C
О
о
О
о
O
A
B
D
E

E

B
A
C
10

A
F
Fig. 269.-Cylinder Covers.
E
P
A A, Covers. B B, Manhole covers. cc, Recesses for piston-rod nuts. D, Recess for air-pump rod nut.
E, Hole for relief. F, Recess for single piston-rod nut.
more especially with large and heavy covers. The number of bolts
should be carefully calculated, so as not to have a great prepon-
derance of strength in that part, for in the event of the cover
receiving a violent blow from the piston striking against water in
the cylinder due to violent priming, when the flanges in the cylinder
1
388
MODERN STEAM PRACTICE.
and cover are properly proportioned the bolts should rather give
than a breakage occur. A hole is left at the bottom of the cover
for the relief valve, similar to that in the front of the cylinder.
E
F
The
A
B C
D
The stuffing boxes for the piston rods are fitted with a lantern or
hollow distance piece, with an extra light gland placed on the main
one, the stuffing box of which is packed in the usual manner.
lantern brass is placed in the outside
stuffing box, and then a gasket of hemp or
other packing is placed on the back of it,
and screwed up with the light gland. The
use of this lantern brass is to leave a space
all round the piston rod for containing the
lubricating oil; the piston rod has thus a
ring of oil all round, which is kept in the
space by the hemp packing, and pre-
vented from dropping down and running
to waste. The main glands are gener-
ally screwed down with plain bolts and A, Packing space. B, Gland. c,Oil space.
D, Gland. E, Bush. F, Cylinder cover.
nuts; but in fast-going engines a risk
attends this method, as the gland is liable to be pressed against the
side of the rod, and thereby to throw an undue strain on the piston

Fig. 270.-Piston-rod Gland with
Lantern Brass.

A
B
O
AWO
Fig. 271.-Piston-rod Gland with Adjusting Gear.
A, Packing space. B, Gland. cc, Worm wheels and pinions. D, Spindle.
rods. In order to effect a parallel strain on the packing, as well as
to be able to tighten up the gland when the engines are in motion,
two large bolts are used, with worm wheels and pinions on each,
and a spindle connecting them; thus by one movement the gland
can be tightened up in a parallel manner. In some engines of the
MARINE ENGINES.
389
direct-acting type the packing gland for the piston rod is recessed
into the end of the cylinder, the end being curved, as well as the
piston and cover: by this means a slight gain is obtained in the
length of the main connecting rod, but otherwise it affords no
advantage, and the patterns are more difficult to make.
The exhaust pipe in communication with the condenser is cast
along with the cylinder, and can be made of any required shape,
provided the area is sufficient. The circular shape, however, is the
strongest and best for that part of the exhaust pipe which joins the
thin copper pipe leading to the condenser, as the latter pipe forms
really part of the condenser, and unless it were made circular it
would collapse with the atmospheric pressure. The ends and covers
of the cylinder must be strongly ribbed in the casting with feathers
radiating from the centre; from this not being properly attended
to, the pulsation of the cast iron in some covers is quite visible at
each stroke of the piston. This bending and unbending of the
metal of course deteriorates its molecular particles, and when any
undue strain comes upon the cover from excessive priming, there is
danger of its becoming fractured, or indeed of being blown out
altogether, as has happened to many covers and ends. A small
branch pipe should be cast on the exhaust pipe, for the blow-
through valve, which is connected to the valve casing or the steam
pipe, according to the locality of other details. Small bosses should
also be cast on the bottom of the cylinder at each end, to which
small plug valves are fixed for allowing the water to escape out of
the cylinder before starting; these valves are connected together
with levers and rods, one handle serving to open them both. All
small fittings that are intended to be fixed on the cylinder should
have facing strips cast on, which tends to lessen the labour in the
workshop. To effect this important object more completely, some
makers have cast the cylinders together, but the risk in this method.
is considerable. We have seen castings of this kind that looked
sound, and one of the cylinders on being bored out presented a
good surface, but the other was quite porous and full of blown
holes; both of the cylinders of course requiring to be broken up as
useless. This fact may deter many from trying such a plan, at
least for large cylinders, yet for small ones the advantages are
great, and the risk proportionately less. Care should be taken,
however, that the metal be neither too soft nor too hard, more.
especially the latter, as extremely hard castings should be avoided,
390
MODERN STEAM PRACTICE.
particularly for great steam pressure. Many cylinders cast too
hard have cracked in all directions after being but a very short
time in use, owing, it is considered, to the unequal expansion of
the metal. The core of the casting has been removed in the
moulding pit to cool the inside of the cylinder, which makes
this portion harder than the outside portions, and strains the metal
forming the whole casting, rendering it brittle, and very liable to
give way under steam pressure in those parts where the expansion
of the metal is the greatest. Good metal only should be employed,
and the casting allowed to cool slowly.
The slide valve is a very important detail, and is generally of the
double-ported type, although treble ports are sometimes introduced.
Considering the great size that is required for direct-acting engines,
this valve should be well proportioned, and all its gear of a strong
and substantial make. Some engineers still prefer valve facings of
hard brass, secured to the cylinder face by screwed pins rivetted
over; and even steel facings have been successfully used for high-
pressure marine engines. There can be no doubt that when

A
E
D

Fig. 272.-Slide Valve, with rod passing through it.
A, Slide valve. B, Valve rod. cc, Steam ports. D, Exhaust port. E, Guide for valve rod.
the slide valve is placed on its edge, cast-iron surfaces are found
to answer, when properly provided with means for running off
the water that collects in the valve casing when the engines
are standing, still, as the moisture must impair the cast-iron
surfaces, and the slightest unevenness of the facings will pass
steam, it is perhaps advisable in some cases to use brass sur-
faces. Perfection in detail is doubtless the main thing to be
studied, even although it may entail at first considerable cost in
construction. Various methods are adopted for securing the valve
rod to the valve. In some engines the rod passes through a tube
cast along with the valve, and is secured by a collar at one end of
the rod and two nuts at the other end; in others again the valve
MARINE ENGINES.
391
E
gg
oblong, to allow for the wear and close contact between the faces of
the valve and cylinder. The valve rod, in some examples, is guided
at the end through a hollow brass pipe, or a stuffing box and gland,
similar to the front end. In other arrangements the end of the
valve spindle is screwed into a nut recessed in the valve casing; the
thrust is taken on the end of the nut, and the pull on projections
F
A
D
G
B
rod is screwed (Fig. 272), having a raised screwed part at both ends
and double nuts; by this means the valve can be very accurately
set at any time. The hole through the valve should be slightly


D, Exhaust port.
Fig. 273.—Slidę Valve, with T nut for Rọd, and Packing Rings recessed in the Valve-casing Cover.
GG, Rings for taking off the back pressure.
cc, Steam ports.
A, Slide valve.
B, Valve rod with T nut.
F, Valve-casing cover.
E, Valve casing.
392
MODERN STEAM PRACTICE.
formed on the nut of a T shape; a thin jam nut is fitted, so as
thoroughly to bind the rod and nut together: both of these nuts
should be made of steel, and case-hardened. Another method of
securing the valve rod is by a cotter passing through a boss cast
on the valve, the cotter being fitted with a split pin to prevent it
shaking loose. With the view of relieving the rod and adjuncts
from the severe strain caused by the steam acting on the back of the
valve, packing rings are fitted to the valve, or rings of metal pressed
up against it; in the former case the ring is recessed in the valve,
and pressed up with springs against a planed piece on the valve-
casing cover; in the latter, the ring is recessed in the valve-casing
cover, and pressed up with set screws against the valve.
object of both of these plans is to obtain a large area on the back
of the valve from which the steam in the casing is excluded by
means of the metallic rings, which of course do not leave such
large surfaces for the steam pressure to act upon. This hollow
space is sometimes fitted with a small pipe in communication with
the condenser; thus the valve is partly drawn from the face as it
were by the vacuum.
D
The

E
The valve casing is a separate open frame,
cast with flanges for securing it to the cylinder.
It is very rarely cast along with the cylinder,
at least for heavy engines; although for engines
of small power this plan may be advantage-
ously adopted. The casing cover is generally
cast with a recessed ring, and bosses for
springs, which are accurately turned out for
the reception of the packing rings and springs; Fig. 274.-Spring and Packing
it is of a curved shape, quite plain on the
outside, and well ribbed on the inside, which
prevents the dust from lodging, and the plain
exterior surface is easily wiped down,-an im-
portant consideration in all the parts of a marine engine, as that
operation can only be properly attended to when the vessel is in port.
A snug should be cast along with the cover, having a hole bored in
it for a wrought-iron shackle and pin, to which blocks and tackle
can be secured when taking off and putting on the heavy covers.
for Slide Valve.
A, Slide valve.
BB, Rings for
taking off the back pressure.
c, Spring. D, Set screw.
E, Valve-casing cover.
The branch for the steam pipe is generally placed at the back
of the valve casing, and is cast along with it, the flanges looking
towards each other from cylinder to cylinder. At one end there
MARINE ENGINES.
393
is a stuffing box and gland, and at the other end the copper pipe
is bolted to a plain flange; while the part in the gland is quite
loose, expanding and contracting with the varying pressure.
Eccentric and link motion.--Various descriptions of valve gear
are in use, but the one generally adopted is the double eccentrics and
link motion. This is only introduced as a sure means of handling
the engines, and is but rarely used for working expansively, as in the
locomotive, for the obvious reason that were the slide valve travel-

A

B
B
[B + - +
B
C
DO
Fig. 275.-Eccentric Sheaves.
A, Eccentric. BB, Keys. C, Bolt for
eccentric.
Fig. 276.-Eccentric Strap and Rod.
A, Eccentric strap.
B, Rod. C, Lubricator cup. D, Jaw
and pin for link.
ling only a small portion of its stroke, and kept running for weeks
in this reduced grade, a groove would be formed on the cylinder
face, which would pass steam into the condenser when the valve or
link was put in full gear, and so impair the vacuum; and it thus
becomes imperative to have a separate expansion valve. In the
example in Fig. 275 the eccentrics are cast in two halves and
secured with bolts and nuts, in other examples they are cast solid;
in both cases they are firmly secured to the shaft by keys, as shown.
394
MODERN STEAM PRACTICE.
The eccentric strap (Fig. 276) is of brass, having a wrought-iron rod
with T-piece forged on one end, secured to the strap by bolts and
nuts, the heads of the bolts being re-
cessed in the strap; on the other end a
jaw is formed for taking the link. The
latter has eyes forged on and fitted
with brasses and set screws for adjust-
ing the wear on the eccentric-rod
pins; the suspending pin for the link
is formed with a palm, which is se-
curely rivetted to the link.
The various arrangements of valve
mechanism have been treated more
fully in a former part of this Work (see
page 110).


Fig. 277.-Link.
O O
A
D
A, Link. B, Suspending pin. cc, Eyes for
eccentric rods. D, Block on slide-vaive rod.
When gridiron expansion valves are
used, the seating on the valve face is
cast along with the casing, making a very compact arrangement.
The valve in Fig. 278 is cast in brass, and is worked by a single
eccentric and varying link. In some examples the valve is circular;


O
O
C
A
BI
о
О
O
A
C
D
E
O
H
Fig. 278.-Gridiron Expansion Valves.
A, Expansion valve. B, Facing for do.
c, Steam pipe. D, Main slide valve. E, Cylinder.
by adopting this shape the steam pressure is taken off the back,
and the valve is consequently more easily handled.
MARINE ENGINES.
395
The throttle valve is generally of the butterfly type, and is located
between the expansion valve and the boiler, having hand gear for
each valve passing along to the starting platform. Some engineers
use only one handle for both valves, but this arrangement is not
advisable, as one engine or cylinder may require more or less.
throttling than the other, although the cylinders are lying quite
A
M
Fig. 279.-Throttle Valve.
A, Throttle valve. B, Spindle for do. c, Chest.
close together. A
small plug or other


valve is fitted be-
B
tween the gridiron.
expansion casing
and the main valve
casing, by which
steam can be admitted from the one to the other, in the event of
the engines stopping at a part of the stroke where the expansion
valve covers the ports, and it would be difficult to start again
without this auxiliary valve.
D
B
A
C
The blow-through valve is a common spindle one, guided at the
bottom through a hole in the centre boss cast along with the seating,
with a single feather; or the valve may
be of the three-feather type, turned to
the inside diameter of the seating. The
former has a long spindle at the top,
which passes through a stuffing box on
the cover of the valve box. This spindle
is fitted with a slot crosshead for the
lifting arm to pass through, with a lever
and rod passing along to the starting
platform. Some makers have used a
small slide valve, with steam and ex-
haust ports placed on the top of the
cylinder, with steam passages and
valve chest cast in brass. This valve
is worked by hand off the platform, and can be used for blowing
through, or even turning the engines gently, in which respect
it serves as a means of starting the machinery independently
of the main slide valve--a great desideratum in large-powered
engines. Plain plug valves may be conveniently used for the blow
through, but it is not advisable to adopt them for heavy engines.
The plug should be packed with hemp at the top, having a suitable

Fig. 280.-Blow-through Valve.
A, Valve and spindle. B, Chest. c, Stuffing
box and gland. D, Lifting lever.
396
MODERN STEAM PRACTICE.
packing gland, and the bottom or small end of the plug is merely
fitted, and ground into the seating, which is cast solid at the end;
by this means no leakage can occur except at the top, which is
made steam-tight by the packing gland.
B
E
D
The escape or relief valve, fitted to the bottom of the cylinder
cover and to the front end of the cylinder, is intended to allow the
escape of the water which finds its way into the cylinder from
priming and condensation of the steam. It consists of a disc valve
with a spring fitted to the top, screwed down sufficiently tight to
resist the steam pressure acting on the internal area of the valve.
The valve can only be opened, and the water which is not com-
pressible ejected, by the piston striking against the water, and
forcibly lifting the valve, compressing the spring, which again
reacts when the cylinder is free of water. The valve should be
inclosed in a light dome, with a hole at the bottom side for allowing
the hot water to escape downwards
into the bilges. In other examples a
dash or splash plate is cast along with
the valves, when placed horizontally
and vertically; the plate being of a
curved shape, the water escaping all
round the valve is returned or thrown
back again, and so prevented from being
scattered about the engine room, and
scalding the engineers or those in at-
tendance. The spring is usually screwed c, Spring. D, Crosshead.
down with a crosshead, through which
the valve spindle passes loosely through a hole bored in the centre.
At each end of the crosshead is a column, secured to the valve seat at
one end, and the other end screwed, passing through a hole in the
crosshead, and fitted with nuts above and below. The spring is placed
around the spindle, between the valve and the crosshead, which by
means of the nuts is screwed up carefully, compressing the valve to
a little above the working pressure of the steam in the cylinders,
which can be easily adjusted when the engines are started, and then
the nuts below the crosshead can be screwed hard up; in this way the
valve is guided at the top through the crosshead, and at the bottom
the spindle passes through the hole in the central boss cast along
with the valve seating. Some engineers dispense with the movable
crosshead, using merely a bow or fixed crosshead of wrought iron

Fig. 281.-Relief Valve with movable
Crosshead.
A. Valve and spindle. B, Valve seat.
E E, Columns.
F, Baffle piece.
MARINE ENGINES.
397
secured to the seating with nuts, and a central boss at the top, for
the reception of a screwed stud for tightening up or compressing
the spring; one cap being cast along with the valve for the spring to
rest on, and another cap at the top of the spring on which the screw

E
A
B
D
F
Ꮐ
B
F
F
C
B
F
Fig. 282.-Relief Valve with fixed Crosshead.
A, Valve. B, Valve seat. c, Spring. D, Cross-
head. E, Set screw. F F, Columns.
G, Baffle
G,
piece.
A
D
Fig. 283.-Relief Valve with Stud on Cylinder Cover.
A, Valve. B, Valve seat. c, Spring. D, Cap.
E, Set screw.
F, Stud.
G, Baffle piece. H, Cylinder cover.
Fig. 284.-Relief Valve with Dome.
A, Valve and spindle. B, Valve seat.
c, Spring. D, Baffle dome.
for compressing the spring bears: in this arrangement the valve
is guided by the spindle passing through the seating. A very
simple form of this description dispenses with the wrought-iron
bow, a stud being screwed into the cylinder cover and end, through
which the screw for tightening up the spring passes; while in other
forms the dome fitted over the spring for protecting it from being
injured, as well as for preventing the water flying about the engine
room, is fitted with a boss at the top, through which the tightening-
up screw passes, the dome being bolted to the covers and end with
stud bolts. Many prefer a fixed pressure on the relief valve, but,
398
MODERN STEAM PRACTICE.
on the whole, we think it should be fitted with set screws, to adjust
the pressure against the valve at any time to suit the reduction in
steam pressure that may be considered advisable after the boiler
has worked for a lengthened period. Some makers have fitted an
additional valve opening downwards, seated on the main relief
valve, and opened by hand, while another valve of india rubber is
placed on the top of the main relief one, so that when the additional
valve is opened, in the event of violent priming at the return stroke
of the piston, the disc of india rubber, or metal valve if so fitted,
closes, and does not impair the vacuum. This is a complicated
arrangement, not in general use; and the same object is attained
by fitting a plug valve at the bottom of each end of the cylin-
der, worked simultaneously from the starting platform, and which
can be opened when violent priming occurs, or in the act of
blowing through before starting the engine,-in the same way as
the plug valves in the locomotive engine cylinder, which are left
open for a considerable time to blow out thoroughly all the water
from the cylinders. Some first-class engineers consider that greater
safety would be insured by dispensing with the springs for holding
down the relief valves, and this seems a step in the right direction;
for when valves are so arranged that they are held down simply
by the steam, and have the means of blowing all the water back
again into the steam pipes, and collecting it in a suitable separator,
we secure two advantages, namely, that the valves are not so liable
to stick or get damaged, and that the hot water does not fly about,
but is received into the separator, which can be run off occasionally.
For this purpose, double-beat valves, giving a large circumferential
area for the water to escape, or common spindle valves, are fitted to
the top of the cylinder, in valve chests, which communicate by
pipes with the cylinder on the bottom of the valve and the steam
pipe on the top of the valve; the steam pressure above the valve
being greater than that in the cylinder, the valves are of course
held down by the difference of pressure, and the water is ejected
as in ordinary arrangements, with this difference that it is collected
in a vessel for the purpose, instead of finding its way into the
bilges.
Lubricators.-Grease cups are fitted to the steam ports at the
front and back of the cylinder, for lubricating the valve and piston,
the lubricant being drawn in with the vacuum. These cups should
be fitted in connection with a plug valve having a screwed part at
MARINE ENGINES.
399
the top, to suit the screw of the indicator, with a pipe connected
between the plug valves, so that an indicated card may be taken
from the front end and back of the cylinder without shifting the
instrument. The pipe between the plug valves should be fitted
with an additional valve, for cutting off the communication when it
is desirable to take a card from the front end, and vice versa. The
liquid tallow is poured into the cup, and flows through a hole into
the hollow plug; the valve is then turned by hand, bringing the
hole into communication with a small hole on the opposite side
leading into the port, and the oil is drawn into the cylinder by the
vacuum. Sometimes a plug tap is fitted into the tallow cup, and
opened and shut by hand; but this operation requires some care, as
it is evident that it must not be opened until the vacuum is formed,
or the tallow would be blown out of the cup. The attendant must
therefore watch the motion of the engine, and shut off the com-
munication with the cylinder before the steam is again admitted,
so as to allow the tallow to be drawn into the cylinder with the
vacuum-an operation requiring some dexterity, with the piston
doing sixty strokes or so per minute. It is therefore preferable to
use the hollow plug valve, as described above.
We now come to consider the piston for the various forms of
horizontal marine engines. In the construction of this part the
main point to be studied is to provide ample surface for wear.
The thrust is imparted more directly on the piston in the single-
trunk type than where there is a trunk at each end of the cylinder.
In the latter arrangement the trunks form a hollow support for the
piston, while the thrust of the connecting rod is taken on the bushes
and packing glands in the ends of the cylinder, and the rubbing
surface of the piston can be made much less than for any other
class of horizontal engine. While other pistons must have a broad
surface for wear, the packing rings for the double-trunk system
have in some instances merely slight steel or brass hoops for making
them steam-tight. Pistons for two or more piston rods on the
return connecting-rod principle require less area for the rubbing
surface than those for direct-action single piston-rod engines, the
former being partly balanced by the long rods and heavy cross-
heads, the stuffing boxes serving as a fulcrum by which the weight
of the piston is partly taken off the cylinder surface, and this tends
to prevent them wearing so rapidly as in the direct-acting type,
although the diameter of the piston rod in the latter is increased to
400
MODERN STEAM PRACTICE.
B
C
A
A
B
C
gain more surface in the glands, and by the increased weight of
the rod and its adjuncts to relieve the piston rubbing surface. The
total rubbing surface or depth
of the piston, for double trunks,
may be taken at one-eleventh
of the diameter of the cylinder;
for double piston-rod engines
on the return connecting prin-
ciple, one-sixth; for single
piston-rod and single-trunk в
arrangements, one-fifth: this
depth being the breadth over
the surface in contact with the
cylinder. Most pistons have
projecting rings cast along
with the junk ring, and some




A
B
A
Fig. 285.-Piston Rings.
A A, Pistons. B B, Packing rings. cc, Junk rings.
DD, Bolts with recessed nuts. E, Bolt with hole tapped
in the body of the piston.
H
E
G
6
have also projecting rings cast along with the main body of the
piston-both having in view the equalization of the junk ring and
end surface in connec-
tion with the
the main
packing ring; this is
necessary, as the rub-
bing surfaces on the
junk and back ring have
the weight of the piston,
and in some instances
the thrust of the con-
necting rod, to sustain,
while the packing ring
has not so much duty
to perform. In order
to make the junk ring
and other surfaces to
bear more equally, and
to keep the piston cen-
tral with the cylinder,
two pieces of cast iron
are placed on the under

E
A
Fig. 286. -Piston.
A,
Piston. B, Packing ring. ccc, Springs. DD, Cast-iron pieces.
E E, Bosses for piston rods. F, Boss for air-pump rod.
GG, Ribs
to strengthen the body of the piston. H, Tongue at division.
side, between the packing ring and the main body of the piston,
pitched about one-fifth of the diameter of the piston apart; in this
MARINE ENGINES.
401
way the weight of the piston is transmitted through rigid blocks to
the packing ring, which bears on the internal surface of the cylinder.
Short springs of a bow shape are placed all round the packing ring,
to keep it well up to the cylinder surface. In some cases these
springs are of a U shape, let into recesses in the body of the piston.
The main body of the piston is strengthened with ribs radiating
from the centre, and has the necessary bosses, which are bored out
for the reception of the piston and air-pump rods; the holes are
sometimes tapered to receive the ends of the rods, and in other
examples they are quite parallel; in the former case, the piston rod
is screwed tightly against the cone, and in the latter against a
shoulder left on the rod itself. Holes are cast in the body of the
piston for the purpose of extracting the cores; these are accurately
A
Fig. 287.-Block Piece for Piston Ring.
A, Piston.
B, Junk ring. c, Packing ring.
D, Tongue. E, Bridle.
bored out with a slight cone, and
plugged up with cast-iron plugs,
having a thin coating of red lead
to make the joint perfectly steam-
tight. They are further secured
by boring holes on the circum-
ferential line of the joint, which
are tapped for the reception of
brass or wrought-iron screws,
firmly screwed in, one-half of the
screw being in the body of the
piston and the other half in the
plug; these screws are cut off flush with the surface of the casting.
The junk ring is held down by bolts screwed into the cast-iron
piston, or brass or wrought-iron nuts are fitted, recessed into it,
having a thickness of metal all round; the bolts are kept from
turning by a screwed stud recessed in the head, and tapped into
the junk ring. The ring is accurately turned, as also the surfaces
bearing on the piston and the spring ring, which are then scraped
to a true surface, and made perfectly steam-tight. After the pack-
ing ring is turned, an oblong hole is cut out at the centre at that
part where the ring is cut through, and a brass piece with a flange
all round is fitted into the hole, filling it up, while the flanges make
the spring joint steam-tight; the end of the brass filling-in piece
is secured to the packing ring at one end with screwed studs, and
a wrought-iron bridle is placed over the tongue, and secured like-
wise at one end to the packing ring. The object of this arrangement


26
402
MODERN STEAM PRACTICE.
is to compress the packing ring, by the insertion of a wedge between
the tongue piece at the fast end and the bridle at the loose end, so
that when the wedge is driven in between the two the packing ring
is drawn together, and can be readily placed in the piston when in
the cylinder; the cotter is then drawn out, and the packing ring
expands to its original size, and fills the cylinder somewhat tightly.
The projections left on the junk rings and the body of the piston.
must have recessed parts in the cover and end of the cylinder, with
sufficient clearance at the end and round the projections; and it is
advisable to leave recessed parts at both ends of the cylinder,
making the part bored out somewhat shorter than the actual stroke
of the piston, so that the rubbing surface travels over it at each end,
and prevents a groove forming in the cylinder that would eventu-
ally prove destructive to the engine, in the event of the connecting
rods requiring lining up in the brasses, by causing the piston to
strike hard against the projections. Sometimes the piston for
direct-acting single piston-rod engines is dished out or formed of a
curved shape, with the view of getting more room for the crosshead,
the gland for the rod being recessed into the end of the cylinder.
This is the only advantage to be derived from this plan, and it is
but rarely adopted. The fittings of such pistons are identical with
those for the plain-ended arrangement. When annular cylinders
are adopted for high and low pressure combined engines, the small
piston for the high-pressure cylinder is similar to an ordinary one,
but the piston for the annular cylinder must have two packing
rings, the outside ring bearing on the cylinder surface, as in ordinary
arrangements, but the internal packing ring bears on the inside
diameter of the ring, the ring being pressed up against the barrel
of the high-pressure cylinder with strong steel springs. These
pistons are generally connected to the crosshead by a central piston
rod for the high-pressure cylinder, and two side ones for the low-
pressure cylinder, with one crosshead common to both. There
must be block pieces fitted between each packing ring and the
body of the pistons, to keep them all fair with one another. The
packing rings of all pistons are generally made thicker at the bottom
where these blocks are fitted, and thinner at the top where the
ring is cut; this is necessary, as in all horizontal arrangements the
severest strains and wear are undoubtedly at the bottom of the
piston.
As bearing on this subject the following extracts are from a
MARINE ENGINES.
403
paper on "Pistons," read by Mr. James Howden before the Institu-
tion of Engineers and Shipbuilders in Scotland, session 1880-
81:-" Absolute steam-tightness in a piston at work very seldom
occurs. It is much more difficult to secure than is generally sup-
posed. Probably steam-tightness has never existed in any piston
with a single packing ring after it has worked a short time, even
though the piston has been perfectly steam-tight at first starting.
On removing the junk ring of any such piston after it has worked
for some time, evidences of steam having passed between the faces
of the packing ring and junk ring or piston flange into the interior
space are quite apparent. The scraped or ground faces are in
places dull and steam worn, and if oil or grease has been used to
lubricate the cylinder, grease and dirt will be found in the space
inside of the packing ring.
In pistons with double packing rings leakage over their end
faces is sought to be overcome by a pressure endwise from a spring
which presses the packing rings at same time outwards towards the
walls of the cylinder. This causes undue friction and wear of the
cylinder and packing rings; and where there is much wear there
will soon necessarily be leakage through the packing rings and
interior of the piston. The dirt and grease often so plentifully
found inside the packing rings, show that steam has been passing
about as freely to the inside of the piston as into the cylinder itself.
"The element of friction is an important one, and a piston at
once steam-tight and practically frictionless possesses a value which
it would be difficult to overestimate. There cannot, of course, be
an entire absence of friction, but it may be reduced to the least
possible extent. The piston of a well-made indicator is an example
of a piston steam-tight under any usual pressure, and practically
frictionless. It works without any pressure outwards against the
walls of the cylinder. In pistons with packing rings and compen-
sating springs, one of their greatest defects is the universal excess
of pressure outwards against the cylinder. It is generally supposed
that when a cylinder is found smooth and polished, that the piston
is working with very little friction. This is often a delusive infer-
ence, for in a well-lubricated cylinder the packing rings, if bearing
fairly all round, will make a smooth skin on the cylinder, even
under a strong pressure against it.”
The author, in describing a new form of piston, the invention of
Mr. Wm. Rowan of Belfast, states: "This piston is, however,
404
MODERN STEAM PRACTICE.
distinguished from all other pistons of this class by effecting the
endwise and outward pressures by separate springs, each exactly
suited for the work they have to perform. As I have shown, the
pressure of the packing rings endwise should be strong, and their
pressure outward against the cylinder light, or exactly the reverse
of what occurs in all other double packing ring pistons.
"The springs are extremely simple in their character and con-
struction. They are made from light hoop spring steel, varying in
breadth and thickness to suit the diameter of the piston. Breadths
from ½ inch to 2 inches, and thicknesses from inch to inch,
will serve for pistons from 1 to 6 feet in diameter.
To one
seeing them for the first time these springs look quite inadequate to
accomplish the ends proposed. It is surprising to see a spring of
16

B
A
E
B
D

A
B
B
D
E
Figs. 287A, 287B.-A, Junk ring. B B, Packing rings. c, Spring. D, Flange on piston.
E, Part where the packing rings are cut.
a few pounds weight in a large piston accomplishing an effect
to obtain which in other pistons continuous springs weighing several
hundredweights are used.
"The spring for pressing the packing rings against the junk ring
and piston flange is bent round on its flat to the required diameter,
and may have projections on either side alternately at definite.
distances apart, or the projections may be similarly placed on the
contiguous faces of the packing rings, between which these springs
are placed. The preferable mode, however, and that usually
adopted, is to have the projections on the spring itself in the form
of waves, as shown in Figs. 287A and 287B, and where they are
shown in position between the two packing rings. It is found that
springs made in this manner to definite proportions of height and
length of waves, now fully ascertained for all dimensions, can be
made to give an almost unlimited pressure when screwed to re-
quired position, and the elasticity remains good for years.
MARINE ENGINES.
405

"The springs for pressing the packing rings outwards, against the
cylinder, are made simply of the steel hoop bent round to somewhat
more than the circle of the inside of the packing rings. The ends
meet inside the thin flat sleeve piece shown in Figs. 287C-287E.”
A screwed part at the end of the piston rod, of less diameter
A
B
A
B
Figs. 287C-287E.
A, Piston.
B B, Packing rings.
D D, Bolt holes for junk
cc, Springs.
ring.
C
406
MODERN STEAM PRACTICE.
than the main part of the rod, receives a large nut, by which the
piston rod is secured to the piston. The part of the rod passing
through the piston is of increased diameter and cone-shaped, this
cone is drawn through a corresponding hole bored in the piston,
and held firmly by the large nut at the end, which is kept from
turning backwards by a split pin bearing on it, and passing through
a hole bored in the end of the rod. This cone in some examples
is no larger than the rod at the one end, and is reduced at the end
nearest the nut, in which case no raised part is required to be forged
on the rod; a collar, however, is sometimes left to screw the piston
against. Some makers prefer having that part of the rod which


D
C
A
B
D
A
C
B
Fig. 288.-Tapered Rod and Nut for Piston.
A, Piston. B, Taper on rod. c, Nut.
D, Split pin.
Fig. 289.-Parallel Rod and Nut for Piston.
A, Piston. B, Parallel part on the piston rod. c, Nut.
D, Split pin.
passes through the piston quite parallel, or nearly so, with a shoulder
formed by the reduction of diameter, against which the piston is
screwed. The screw is generally of a v form, rounded at the top
and bottom of the thread; others are cut square, but the v thread
is preferable. The nut in most examples projects from the body
of the piston, and bears on a turned raised part formed on the
casting; in others it is recessed into the piston, and in others again
it is flush with it, or a small projection of the nut is left, so that it
can be turned round with an ordinary spanner. When the rod
passes through a crosshead, its end is turned down quite parallel
and secured to the crosshead with a nut, in the same way as for the
piston. Some engineers place a jam nut on the back of the main
one, with split pins passing through both nuts, thus making a very
secure fastening. These lock nuts should be placed on all the
parts which are liable to shake loose, more especially for direct-
action engines, as the speed at which these are driven is liable to
MARINE ENGINES.
407
loosen the parts if not properly secured. For direct-acting single
piston-rod arrangements a T-shaped piece is formed on the end for
taking the crosshead, or brasses, which are secured to the rod by
two bolts passing through the T piece, brasses, and cap; the nuts
being secured at the ends of the bolts with split pins. The nut
can be fitted with a washer with pin let into the cap, and a small
set screw placed at the top of the one and the bottom side of the
other, passing through the washer and bearing in a hollow turned
in the reduced part of the nut. With the T form there must not
be any raised part on the piston rod at the piston end, so as
to allow the glands and
bushes to pass freely
along; these must of
course be placed on the
rod before it is secured to
the piston, for it is not
advisable, under any cir-
cumstances, to cut the
glands in two, as some
prefer doing in oscillat-
ing arrangements.

B
C

3.8
B
*
B
A
B
ር
The guides and cross-
head for double piston-
rod engines, on the return
connecting-rod principle,
are best arranged with
two guides or motion
bars, one on each side of
the connecting rod. By
this arrangement the
crosshead is well sup-
ported at the ends, and
the strain on the guide bars is in a direct line with the centre line of
the cylinder. The crosshead is a circular forging, with arms forged
on for taking the piston rods. In some cases it is turned quite
parallel between the arms, these being forged on at right angles to
the main part of the crosshead; in others a collar is formed on each
side between the connecting-rod brasses and the guide blocks.
When the arms are forged on at an angle with the crosshead, it is
advisable to make the connecting-rod bearing of a larger diameter,
Fig. 290.-Crosshead Gudgeon and Motion Bars.
A, Gudgeon. B B, Slide blocks.
cc, Motion bars.

408
MODERN STEAM PRACTICE.
finishing up the arms quite square, and fitting the sliding blocks of
brass to them. When this part of the crosshead is turned, the
sliding blocks are bored out, and are held in position with a side
flange; the blocks are planed at the top and bottom. In some
instances cast-iron blocks have been used, lined on the rubbing
surfaces with white metal. The motion bars are of cast iron, the
bottom one is cast along with the condenser, and the top one, of an
I section, is bolted down at each end with one large bolt, passing
down through the vertical distance pieces cast along with the bar;
or two smaller bolts passing through flanges at the bottom may be
conveniently adopted, in which case the bottom motion bar is
generally raised up from the condenser casting, having strength-
ening ribs cast along with it. One or more oil cups, provided
with covers and wick siphon pipes, should be cast on the top of
the guide bar, to lubricate the sliding surfaces. The crosshead in
other arrangements is let into the pillow-block pieces (fitted with
caps and bolts), which are cast along with a T piece at the bottom,
placed centrally, and which is fitted with a separate brass casting,
having clips at the end to take the sliding strain. This guide block
has a large flat surface at the bottom, but the surface at the top is
not of so large an area, owing to the thrust of the connecting rod
being neutralized by the weight of the crosshead and adjuncts.
Some engineers, indeed, have left a small space between the top
surfaces, thus showing clearly that the top thrust is but little felt.
The guide bar is of a trough section, and is bolted down to the
condenser casting, having means of adjusting it to suit the wear of
the brass sliding piece. The lubrication of the parts is effected by
means of an open oil well at each end, which is kept constantly full;
the bottom sliding piece travels a somewhat greater length than
the surface provided on the trough guide plate, consequently its
bottom skims the oil in the receivers at each end, thus keeping the
guide plate thoroughly lubricated. All these arrangements of
crossheads are suited for plain connecting rods; some builders,
however, adopt forked connecting rods, having the crosshead, or
rather the pin for the connecting rod, fixed firmly on the rod,
working in a single pillow block and guide piece, provided with
caps and brasses, as in the previous example. The crosshead for
taking the piston rods can by this means be forged and finished
quite flat, and it is bolted to the guide block with the two large bolts
taking the cap and securing the brasses for the connecting-rod pin.
MARINE ENGINES.
4.09
E
This arrangement of crosshead is certainly preferable to those having
the arms forged on at an angle from the connecting rod bearing, as
it assumes a more direct form of
beam, loaded at the end with the
steam pressure communicated from
the piston through the piston rods,
taken centrally with the connecting
rod, which in its turn acts on the arms
of the cranked shaft, the bearing of
which is subjected to torsional stress.

E
D
D

A
B
C
Fig. 291.-Crosshead for Piston Rods.
We have now to consider the con-
nection between the piston rod and
the connecting rod for direct-action
single piston-rod arrangements. The
brasses for taking the forked end of
the connecting rod are cast in two
halves, on each of which is cast a
bottom guide piece; they are grooved
out for the reception of a wedge plate,
the bottom of which is parallel with the centre line of the rod, but of
a wedge shape on its upper surface, which bears on the brass pieces,
and which is secured at one end, but having the means of adjusting
A, Pillow block on crosshead fitted with brasses.
EE, Eyes for the piston rods.
B, Cap. cc, Bolts and nuts. D, Crosshead,
F, Brass
sliding piece.
D
D
E
B
A
C

F
A, Brass crosshead.
Fig. 292.-Crosshead for Single Piston Rod.
B, Cap. C, T piece forged on the piston rod. DD, Bolts and nuts.
E, Adjustable plate. F, Guide for crosshead.
the sliding brass against the bottom guide plate, as in the examples
already described. The piston rod has a T piece for attachment
to these brasses, and at the connecting-rod end a cap is fitted; these
are all held together by two large bolts passing through the T piece,
410
MODERN STEAM PRACTICE.
brasses, and cap. This is a neat form of connection; whether the
brasses have a plain exterior or are cut out in the pattern, the
bottom part is generally cored out to save weight and metal. For
trunk engines of the single class the brasses are placed in a pillow
block, cast along with the piston, and two bolts pass through the
piston for securing the cap. This arrangement is adopted for forked
connecting rods; but for single connecting rod ends, both in single-
trunk and double-trunk arrangements, the pillow block and brasses
are dispensed with, and a crosshead of wrought iron is substituted,
with bosses forged on the end, through which it is securely bolted
to the trunk. In single-trunk engines raised bosses are cast on the
piston, and accurately faced for fitting against, the bolts passing
through the piston, and having their heads covered with a plate
let into the piston, which prevents the steam escaping through the
trunk into the atmosphere; while in the double-trunk engine the
crosshead is secured by bolts which pass through snugs cast along
with the trunk, and do not require to be made steam-tight, as in
the preceding case. The snugs should be strengthened with a deep
feather, so as to take the thrust and pull which is transmitted on
all connecting-rod attachments.
The most approved form of connecting rod between the cross-


B
A
Fig. 293.-Connecting-rod End for Cranked Shaft.
A, End forged on the piston rod. B, Cap. cc, Bolts and nuts. D, Brasses.
head and cranked shaft is that with solid ends forged on, slotted
out for the reception of the brasses, with caps of wrought iron
secured by two large bolts. The part for taking the brasses can
be bored out, the bedding forming a true circle; the ends and cap
are forged, turned, and finished entire, with holes bored for the
reception of the bolts, which are so spaced that part of the brasses
require to be scooped out, which prevents them turning round in
MARINE ENGINES.
411
1
their seats. After the end is finished it is slotted across the middle,
the part slotted off forming the cap; the brasses have the usual
flanges all round, and are entirely finished in the turning lathe.
The bolts have solid heads, with part of the nuts recessed into the
cap, and a set screw passes through the side of the head, pressing
against the nut to prevent it becoming loose; the bolts are secured
in like manner: these precautions being necessary with high-speed


B
A
}
Fig. 294.-Connecting-rod End for Cranked Shaft.
A, End forged on the piston rod. B, Cap. CC, Bolts and nuts. D, Brasses.
engines. Some engineers prefer to have a flat part left for the
sides of the brasses, made deep enough to take a part of the top
brass, with a cap of sufficient depth to suit the requirements; the
heads and nuts of the bolts are not generally recessed into the
block and cap, but the nuts are turned down, leaving a hollow part,
and a washer fitted with a pin in the cap, with a set screw bearing
in the groove cut out in the nut to prevent it shaking loose. In
some examples both of the ends are forged on in one block; and
others have forked ends to suit the crosshead adopted, having a
pin securely fastened through holes bored out in the forked ends,
with a collar at one end and a pin at the other end securely rivetted
in. Other forms of connecting rods have T pieces forged on the ends,
with brass distance blocks between the T piece and the cap, bolted
together with two bolts. These blocks are lined with white metal,
and are bored out to suit the pin on the cranked shaft; the end for the
crosshead does not require white metal let in. In some cases the
blocks are made quite plain and flat on the sides, in others the
pattern is cut out to save metal. The bolts for securing the brasses
are fitted with nuts and washers, having set screws for preventing
the nuts working loose. Sometimes a round boss is left on the
bottom brass, having a corresponding hole in the T piece; this
412
MODERN STEAM PRACTICE.
helps to take the side strain off the bolts, but the generality of
makers leave these surfaces quite plain. When the bottom end of
A
E
D
the connecting rod is con-
nected to a journal inside of a

1
trunk, it is necessary that the
brasses can be tightened up
from the outside, and for this
purpose the eye of the rod is
forged on solid, and bored and
slotted out for the brasses;
the rod is then bored out for
nearly its entire length, for the
reception of an inside steel bar,
which is fitted at the top with
a cotter for tightening up the
rod against a steel plate let
into the top brass, the bottom
brass having a projection cast
on, which fits into the central
hole in the connecting rod. This is a neat arrangement, and can-
not be dispensed with when the brasses work in a crosshead held

Fig. 295.-Connecting-rod End for Cranked Shaft.
A A, Brass ends. B, Cap. cc, Bolts and nuts.
D, T piece forged on the piston rod. E, Oil cup.
#C
E
+
•
B
A
quite rigid.

The old form of connecting
rod, with straps, jibs, and keys,
may in some instances be bene-
ficially adopted, more especially
for the crosshead for double
piston-rod return connecting-rod
engines; in this arrangement,
having the keys passing through
a slotted-out part left in the
broad rubbing surface, with a
groove formed in the condenser
casting for the end of the key
to travel backward and forward
in, the distance from the centre
of the journal of the crosshead
to the plate on which the block
slides can be greatly reduced, which is a somewhat important con-
sideration. A very simple form of connecting rod has half brasses

C
Fig. 296.-Connecting-rod End for Cranked Shaft,
A, Rod. B,
B, Butt.
cc, Strap. D, Brasses.
E, Jibs and cotters.
MARINE ENGINES.
413
at the top and bottom, with a small rod on each side, on which are
left collars for the bottom part or inside brasses to bear against,
while the two outside brasses are bolted hard up against the inside.
ones, with a screwed part on the ends of the rods having nuts and
washers: these rods therefore act as the main connecting rod and
tightening-up bolts. This plan, however, has not been much
adopted.
C
A
A
B
C
A
A
Fig. 297.-Cranked Shaft.
O
The next detail to consider is the cranked shaft-a term adopted
to distinguish between cranks forged in one piece with the shaft,
and plain ones having cranks shrunk on. The crank arms are
forged on solid at right angles
to each other, they are then bored
across and slotted out for the
part between the jaws, leaving a
part for the crank pin, which is
turned out in the turning lathes
or cutting-out machines used for
that purpose. There are three
main bearings, one on each side
of the cranks at the outside
and one central bearing between
them. When the distance be-
tween the cylinders is great, the
cranked shaft is separated at
the centre between the cranks,
having solid discs forged on, secured with bolts and nuts, and a
cross key for taking the sheering strain off the bolts: in this
arrangement two central bearings are provided, instead of one,
as when both cranks are forged on entire. The end parts of
the crank arms are often finished in the turning lathe, but some
examples have the circular form; the former, however, is the better
plan when counter weights are strapped on for balancing the weight
of the crank arms. These straps are quite flat, except where they
pass through the cast-iron balancing piece, where they are rounded.
The balancing piece is secured with nuts, let into the block at the
extreme end, and joggled into the arms at the crank end; the end
of the strap should have a round pin rivetted in, with a correspond-
ing hole bored on the crank end, which tends to prevent the strap
moving sideways. Some makers leave a joggle on each side of
the strap by planing out the sides of the crank arm, which makes

A A, Cranked shaft. B, Main bearing. c, Crank pin.
414
MODERN STEAM PRACTICE.
a first-class piece of work, effectually preventing these balance
weights moving sideways. The crank arms in some cases taper
B
D
D
A
C
C
B
Fig. 298.-Balance and Cranked Shaft.
A A, Cranked shaft. B, Crank pin. cc, Balances.
DD, Straps.
from the shaft to the crank-
pin bearing, in others they are
left parallel; and when other
modes of balancing the cranks
and connecting rods are adop-
ted, the corners of the cranks
can be finished to a bold radius,
by which part of the weight re-
quiring balancing is removed.
The journals for the cranked
shaft, and indeed all journals,
should be finished with the

tool in the lathe; the use of emery to get up a smooth face is a
practice long ago exploded, and rightly so, as many journals and
bearings have been torn and rutted up by the fine particles of
F
G
D
C
B
0
B
A
Fig. 299.-Main Framing of 1 Section.
emery indented in the iron. All
the collars should be turned
with a bold radius, for when
E they are left square it is gen-
erally here that the shaft gives
way after long use. As the
strain imparted from the thrust
and pull, passing from the
piston through the rods, is
E both rapid and severe, this
accident may occur with the
best arrangements; it is there-
fore always advisable to have
a spare cranked shaft stowed
on board the ship.
What are called built shafts
are those in which the crank
and crank pins are shrunk on.


A, Main frame. B, Brasses. C, Cap. DD, Cotter A fire, generally of wood, is
bolts and nuts. EE, Flanges for bolting to cylinder.
F, Flange for bolting to condenser. G, Oil
cup.
lighted round the cranks, and
when sufficient expansion has
taken place the parts are slipped into position. The crank on
cooling down grips the shaft and pin tightly.
MARINE ENGINES.
415
Fig. 298A shows the crank shaft of the screw steamer Arizona. It
4:11.
LP.
B
CLE
C
B
1
D
D
D
F
E
12 Feel
A, Crank pin for high-pressure cylinder.
placed. F, Disc on which eccentrics are
cc, Cranks.
B B, Crank pins for low-pressure cylinders.
placed. G, Coupling on which turning gear is placed.
is built up of five pieces. Of these
four are made of hammered and
rolled scrap iron, the fifth, or crank
pin, being made of steel. The dia-
meter is 22½ inches.
The immense power of engines in
some of the recently launched ocean
steamships for the Atlantic service
necessitates correspondingly heavy
and strong machinery; thus the
crank shaft of the Servia, City of
Rome, and Alaska are about 25 inches
in diameter; those of the Servia and
Alaska are solid, whilst that of the
City of Rome is hollow. This shaft is
of steel and made by Sir J. Whit-
worth's process, the steel being
known as fluid compressed, this me-
thod being adopted to insure uni-
formity in structure. The process
consists in first of all casting the steel
in a mould having a core; thereafter,
and while still fluid, thecasting is sub-
jected to an intense hydraulic pres-
sure, which forces the air and gaseous
matters out of the fluid mass. After
solidifying the metal is reheated and
forged down to a length suitable for
the purpose for which it is to be ap-
plied. A stronger shaft for the same
weight of metal is thus obtained.
The main framing (Fig. 299) on
which the pillow blocks are cast for
sustaining the cranked shaft may be
regarded as the backbone of horizon-
tal marine engines. It is subjected to
tensional, compressive, and twisting
strain, and must therefore be made
of great strength. Some makers adopt the I section, others the +,

5.1.
4:11"
5:1"
4:11"
5.1.
2.5".
Aft
D
E
A
22
Fig. 298A.-Crank Shaft of Screw Steamer Arizona.
on which eccentrics
are
DD, Bearings. EE,
Couplings
416
MODERN STEAM PRACTICE.
while some consider the box form preferable; and all these forms are
successfully carried out in practice. Strength is the main thing to be
looked to; but the open form of framing has the advantage of giving
more convenient access to the various glands. The frame is firmly
bolted to the cylinder at the top and bottom, and also to a flange.
carried along from the cylinder to the condenser. This flange is

E
A
F
E

A, Frame.
Fig. 300.-Main Framing of + Section.
B, Brasses. c, Cap. DD, Bolts and nuts. EE, Flanges for bolting to cylinder.
F, Flange for bolting to condenser.
secured to the keelson or engine bearers by long bolts passing
down to the under side of the bearers, with cross bars of cast iron
at the under side; in this way the whole depth of the engine bearer
is secured. All the bolt holes should have proper bosses cast on
the framing, to suit the bottom and other flanges connected to the
cylinder and condenser, so that a fair bed for the nuts can easily
be faced up. The brasses for the pillow blocks are fitted just as in
any other arrangement lying on its side, and are secured by caps
of cast or wrought iron; each cap has two large bolts passing
through it into holes cast and bored out in the casting, and fastened
with cotters. The cap is fitted with clips at the top and bottom, nicely
fitted to the pillow block, to prevent its sides springing; and the
nuts for the bolts are fitted with washers and set pins, to prevent
them becoming loose. All the work connected with the pillow
MARINE ENGINES.
417
blocks must be well executed, for the main stress is directly taken
on these bearings. When the distance between the cylinders is
great, leaving a long centre part on the cranked shaft between the
cranks, the centre bearing should be increased in length, so that no
undue strain is taken on the cranked shaft; in fact, the shaft should
be always supported as close to the cranks as is practicable. All
the brass bearings are recessed for the reception of white metal,
which is poured in while in a fluid state, a cast-iron core piece,
somewhat less than the diameter of the shaft, being first inserted

F
E
A
D
B
C
Fig. 301.-Main Framing of Box Section.
A, Frame. B,
B, Brasses. c, Cap. DD, Bolts and nuts. E, Wrought-iron stay. F, Slipper guide.
G, Oil cup.
in the bearing, so as to keep the white metal in its place; the half
brasses are held together prior to this operation, and are bored out
in the lathe and then separated. In this way fair work is secured;
but some makers prefer boring out the brasses in situ, and no
doubt when properly executed this plan has its advantages. In
most machinery there are numerous fittings which can be con-
veniently cast on the main framing, or bolted on fitting strips left
for that purpose; and proper attention to these points shows the
skilfulness of the designer, and saves much work afterwards.
The box form of framing differs materially from the I and +
27
418
MODERN STEAM PRACTICE.
sections, although the brasses are also fitted in lying on their side,
in order to adjust them in a direct line with the strain given off from
the piston. The part of the bottom frame which forms the con-
nection between the cylinder and the condenser is retained, but the
top part is dispensed with, and a wrought-iron stay introduced,
keyed through a boss bored out for its reception in the head or
pillow block; on the other end of this stay a flange is formed for
securing it by bolts and end keys to the cylinder at the side of the
steam jacket. Between the bottom part of the framing and the
cylinder a bed plate is introduced, on which raised parts are cast.
to receive what is termed the slipper guide plate for the crosshead
of direct-acting single piston-rod arrangements. This part of the
framing extends across the engine, embracing all the pillow blocks
for carrying the cranked shaft, which blocks are also cast entire
along with the bottom frame plate; but at the condenser end parts.
are cut out in the bottom having merely projections opposite the
bearings for bolting to the condenser. This form of framing
has a strong yet light appear-
ance, and cannot be excelled
for the peculiar type of engine
for which it is designed, as all
the parts are easily reached-
a great desideratum in the
marine engine; while the whole
framework is firmly united to
the keelsons by one broad base
plate.
In another form of framing,
Fig. 302, we have the means of
tightening up the main brasses
by wedge pieces let into the
pillow blocks. This frame
extends from the cylinder to
the condenser, with ribs and
IB
F

E D
C
O
A

Fig. 302.-Main Framing with Adjusting Wedges.
feathers cast along with, and A, Frame. B, Brasses. C, Cap. DD, Bolts and nuts.
E E, Adjusting wedges. F, Oil cup.
in a direct line with the sides
of the pillow block or bearing piece, the cap for holding down
the brasses being placed on the top, instead of on the side as in
the previous examples. Between the brasses at the cylinder end
two wedge pieces of wrought iron are introduced, extending across
MARINE ENGINES.
419
between the flanges, having a spindle forged on, and passing
through the cap; they have a screw cut on the end with nut and
lock nut fitted, by which means the brasses can be tightened up or
adjusted at any time. In other arrangements a single wedge piece
is introduced, having one central spindle fitted with two nuts for
tightening up against the cap. Some makers introduce the brasses
in four parts, one at each side and one at the top and bottom; by
this means they can be adjusted vertically and longitudinally.
The condenser.-We now come to consider the arrangements for
effecting the condensation of the steam with ordinary injection
condensers. All condensing vessels should be constructed as simply
as possible; and the arrangement of the water pipes leading into
and from them, as well as valve seats, discharge chambers or hot
BA
D
A
C
Fig. 303.-Exhaust Pipe.
E
A, Pipe. B, Stuffing box and gland. c, Baffle plate.
D, Condenser.
E, Hole for running off condensed steam.
wells, and all their vari-
ous fittings, requires
careful consideration.
Where large flat sur-
faces are required, they
should be well strength-
ened with ribbed bars
in the casting; some
makers use wrought-
iron stays, which tend
greatly to strengthen
the condensing vessel

against collapsing. The other parts of the general casting must be
well bound with the various divisions required for the air pump and
valve fittings. The capacity of the condenser is greatly affected
by the size of the exhaust pipe from the cylinder; this pipe should
have a large area, so as to freely pass the steam to that part of the
condenser where the water from the sea is showered in; thus the
large pipe receives the steam, which is at once condensed, and the
capacity of the condensing vessel need not be so large as when the
exhaust steam finds its way into a condenser placed alongside of
a cylinder having no pipe connection.
The exhaust pipe should be fitted with an expansion joint, which
is generally placed on the condenser casting, the end of the pipe
passing through a loose hoop placed at the bottom of the stuffing
box; by this means the pipe can be angled into its place without
disturbing the cylinder or condenser. The loose hoop and gland
420
MODERN STEAM PRACTICE.
being placed on the pipe in the first instance, the hoop is then
slipped into its place, and the gland pressed down on the hemp
packing in the usual manner; the other end of the pipe is secured
by a flange bolted to the cylinder. There are also other forms of
expansion joints. Some have hollow discs formed on the body of
the pipe, with end flanges for securing the pipe to the cylinder and
condenser, thus forming a rigid stay between the two, but having
the power of expanding by compressing the flat discs, and con-
tracting when the strain is off by opening the disc plates. We
prefer, however, the usual mode with stuffing box and gland. The
position of the condensing chambers varies, and depends greatly on
the location of the air pumps. When these are placed together, one
on each side of the middle frame for carrying the cranked shaft,
the condensers are then generally in a line with the outer frames, or
fore and aft of the outer lines of the cylinders. In return connect-
ing-rod engines, with the discharge chambers placed between the
centre lines of the cylinders, and in similar arrangements of air
pumps, the condensing chamber and discharge chambers are both
placed between the centre lines of cylinders; this plan necessitates
the cylinders to be placed further apart from centre to centre-that
is to say, when the air pumps are located at the side of the motion
or guide bars for the crosshead. Sometimes the air pumps are
arranged underneath the motion bars, having the discharge chamber
at the middle between them, and the condensing chambers on each
side; while, in other examples, with one air pump on the outside
of each outer frame, fore and aft, the condensing chamber and
discharge chamber are cast together immediately over the air pump.
In direct-acting single piston-rod and double-trunk engines, the
air pumps are always placed one on each side of the centre frame,
having the condensing and discharge chambers located immediately
above them; while in plunger air pumps with single-acting arrange-
ments for foot and head valves, suited for single trunk and return
connecting-rod engines, the condensing and discharge chambers
are placed immediately over the pumps.
The general arrangement of all these forms of condensers,
exhaust, discharge, and injection pipes, air pumps, with foot and
head valves, &c., cast in one or more castings, is as follows. When
the air pumps are arranged one on each side of the middle frame,
there are generally two separate castings, all the fittings for which
are kept quite independent. The air pump in all the examples
MARINE ENGINES.
421
under notice, whether fitted with an internal plunger or a simple
piston, is of the double-acting type, and is worked directly off the
steam piston by means of a rod connected to it, having packing
D;
B
E
E
A
F
Fig. 304.-Air Pump with Condenser outside and
Discharge Chambers at centre.
A, Condenser. B, Hot well. c, Foot-valve seat.
Head-valve seat. E E, Guide bars. F, Air pump.
glands on cylinder end and
air-pump cover. When the
pumps are placed as above
described, the foot valves are
underneath and the head
valves above them; there are
separate chambers for the
foot valves at each end, but
the head valves are fitted in
one chamber common to both
ends. Doors for the foot
valves are fitted at each end,
one of which forms the cover,
and the other is an ordinary

door; on each of these doors a circular pipe piece is cast, for filling
up the space above the foot valves, so as not to leave so much dead
water in the foot-valve chambers. The doors on the discharge
C
E
B
A
chamber containing the head valves
are of the ordinary description;
these as well as the other doors are
generally bolted by stud bolts and
nuts. Two deep feathers are cast
along with the hot well, which forms
an air chamber tending to relieve
the shock caused by the rapid dis-
charge of the water. The discharge
pipe is fitted to one end of the
hot well, at the top, and is placed
in communication with one pipe
Overboard common to both air
pumps. The condensing chamber
is on the opposite side of the centre
line of the cylinder in regard to the air pump, the exhaust comes
in at the top, and the injection pipe immediately under it. The
condensing chamber is ribbed and cast with circular parts, which are
bored out for the reception of the air-pump barrels; these are cast
in brass, and fitted with solid-ended pistons of the same material.

Fig. 305.-Air Pumps with Condenser and
Discharge Chamber at centre.
A, Condenser. B, Hot well. c, Foot-valve seat.
D, Head-valve seat. E, Guide for piston-rod
crosshead. F, Air pump. G, Discharge pipe.
1
422
MODERN STEAM PRACTICE.
The snifting valve for all condensers is fitted as low down as
possible.
For similar arrangements of air pumps situated on each side of
the middle frame, the foot valves are placed low down on the other
side of the centre line of the cylinder in regard to the air pump,
with the head valves in one chamber common to both, arranged
between the air pumps; the doors for getting at the valves are
placed on the top of the valve chambers, which is found a very con-
venient and handy arrangement. One discharge pipe, placed
centrally with the hot well, serves for both of the pumps. The
exhaust steam comes in at the top end of the chamber, and the
water falls down underneath the air pumps, the condenser being
partly above and partly below
the pumps, and having a divi-
sion cast in for separating and
strengthening it. The injection
valve can be placed above the
exhaust pipes, and thus shower
the injection water down on the
steam, instead of meeting it as
in the previous example.

B
A
E
E
Gl
D
F
When the air pumps are situ- Fig. 306.—Air Pump with Condenser outside fitted with
ated underneath the motion bars,
inverted Foot Valves and Discharge Chamber at
centre.
a good plan is to invert the foot A, Condenser. B, Hot well. c, Foot-valve seat.
valves, placing them in the D, Head-valve seat.
bottom of the condensers, which
E E, Guide bars for piston-rod
crosshead. F, Air pump. G, Discharge pipe.
are seated in a line with the outside frame; thus the condensing
water and the condensed water from the steam fall into each
suction chamber by their own gravity. In this arrangement the
head valves are placed in a central chamber between the pumps;
and this chamber has one discharge pipe common to both sets
of air pumps.
The exhaust steam enters at the top, the injec-
tion pipe is placed under and showers the water upwards to
meet the steam, care being taken that the water cannot pass
into the exhaust pipe. The injection pipe, when placed below the
exhaust pipe, should always be pierced with holes, to shower the
condensing water meeting the steam, instead of pouring it down
vertically; by this means the water and steam are brought into
better contact, and form a more rapid vacuum.
When the air pumps and condensers are arranged in a line with
MARINE ENGINES.
423
the outside frames, the foot valves are inverted, the head valves
being over the pump, with a discharge chamber and pipe, having
the condenser immediately over it, separated by means of division
plates in the casting; the exhaust pipe is placed at one side, and
the injection pipe on the opposite side arranged for showering the
water downwards. A bed plate for carrying the guides for the
crossheads, &c., lies between the two pumps, and forms a very
convenient starting platform, nearly on a level with the engine floor
plate. Some engineers, however, make use of this space for arrang-
ing the condensing chambers between the guide bars, with the air
pumps placed as before inside of the outer frames. The foot valves
G
B
DA
E
E
F
are placed at the bottom and
side of the air pump, and the
head valves immediately over
them, with side doors to each,
and a discharge pipe for the
pump. The exhaust pipes
enter at the top of the cen-
tral condensing chambers,
and the injection pipes are
placed lower down. It is ad-
visable with this form of con-

Fig 307.-Air Pump with Condenser outside fitted with denser, at least for engines of
inverted Foot Valves and Discharge Chamber outside,
all in one casting.
A, Condenser. B, Hot well. c, Foot-valve seat.
D, Head-valve seat. E E, Guide bars for piston-rod cross-
head. F, Air
pump. G, Exhaust pipe.
great power, that the pumps.
should be separate castings;
provision should also be made
on the patterns for attach-
ing and fitting to the general casting the feed and bilge-water
pumps, which are generally worked off arms keyed on the piston
rods, or with studs fitted to the crossheads, or even with direct rods
from the steam piston. We have here given examples of condensers
with their adjuncts which are in general use; but it will be under-
stood that a variety of forms can be arranged for return connecting-
rod engines.
We now turn to arrangements that have been adopted for direct-
acting, single piston-rod, and double trunk engines. There is a
great similarity in the various parts of these, chiefly owing to the
air pumps being located one on each side of the middle frame for
carrying the cranked shaft. The condenser is situated centrally
above the pumps, having the foot valves inverted, so that the water
424
MODERN STEAM PRACTICE.
falls into the pump chamber by gravitation; the head valves are
placed at the side and above the line of foot valves, with a hot well
for each pump fitted with separate
discharge pipes overboard. With this
arrangement of foot and head valves.
air is not so liable to collect between
the piston and valves; it is therefore
preferable to have an air valve-
should it be desirable to place the
discharge valves below the line of
head valves-arranged at the highest
point in the foot-valve chamber, by

1
蓄
​B
E
G
which the air is forced into the dis- Fig. 308.-Air Pumps with Condenser at centre
charge pipe overboard. The exhaust
pipe is of a large diameter, suited for
both engines, placed in the centre of
the condenser, and the injection pipe
fitted with inverted Foot Valves and Dis-
charge Chambers at side, all in one casting.
A, Condenser. B, Hot well. C, Foot-valve
seat. D, Head-valve seat. E, Air pump.
F, Feed pump. G, Exhaust pipe.
is placed at the top on the same centre line, thus the water is
showered down on each side of the condensing chamber: this
arrangement is very effective. In other arrangements the valves
G
A
B
D
E
are placed vice versa, the condensing
chambers being at the side, and the dis-
charge chamber placed centrally above
the pumps, with one discharge pipe
overboard; while there are two exhaust
pipes, each passing into a separate con-
denser, with the injection pipes under-
neath. This arrangement has the ad-
vantage of the condensers for the cylin-
ders being separate from each other,
and this enables us to regulate the in-
jection water required by each, which
we cannot do when one injection pipe
serves for both condensers. These con-
densers, when required for engines of
ordinary power, are generally cast in one piece, but for heavy
engines they should be two separate castings, with air pump and
adjuncts arranged as in the previous examples.

Fig. 309.-Air Pump with Condenser at
Discharge Chamber at centre.
side fitted with inverted Foot Valves and
a,
Condenser. B, Hot well. c, Foot-valve
seat. D, Head-valve seat. E, Air pump.
F, Feed pump. G, Exhaust pipe.
THE SURFACE SYSTEM OF CONDENSATION.-Before describing
the construction of the condenser for the surface system of con-
MARINE ENGINES.
425
densation, we shall notice the disadvantages attending the injection
system for the condensing of steam in marine engines. The chief
objection doubtless arises from the necessity for using a continuous
supply of salt water in the boilers, the salt accumulating to such
an extent that a high degree of heat is required to raise the steam.
This accumulation of salt proceeds so rapidly, that it is necessary
to blow off the water in the boiler every two hours or so, the feed
from the hot well at the same time is turned on, thus the hot brine
being blown off, and replaced with a colder fluid, the temperature
of the water in the boiler is greatly reduced, and requires much
valuable fuel to keep it up to the proper working point. The rapid
incrustation that takes place is likewise a serious objection, as the
scale formed all round the parts immediately exposed to the action
of the flame is a very bad conductor of heat, and not only impedes
the free transmission of the heat to the water, but in many parts
of the boiler it forms to such an extent that rupture of the plates
takes place, more especially on the back parts of the furnaces where
the flame returns through the tubes-necessitating frequent inspec-
tion, for the purpose of cleaning the boilers, and removing the
incrustations, so as to prevent the plates wearing out too rapidly.
In fact, for the high-pressure compound engine system, the injection
condenser has been discarded, because distilled water is preferable
to impure salt water; and with proper precautions we can safely
adopt high-pressure steam with fresh water, and thereby save much
valuable fuel.
The action of surface condensation may be familiarly illustrated
by the well known deposition of moisture on the windows of a
crowded room, due to the cooling surface of the glass. So with
the steam from the cylinder: surface must be provided, and cold
must be applied to that surface, so that with cold on the one side,
and the steam impinging against the cold surface on the other, the
caloric is extracted, and water flows down, similar to that on the
window. Thus when the boilers are provided in the first instance
with pure water, it is used over and over again, with just sufficient
water injected from the sea to meet the waste, and keep the density
of the water in the boiler at about the same as the water in the
ocean, this being considered in practice very safe. And as water
requires a large surface in the boiler for the heat to act upon it in
raising steam, so in condensing the steam rapidly we must have a
large amount of cold surface for it likewise. The surface condenser
426
MODERN STEAM PRACTICE.
is simply an arrangement of tubing placed in a convenient vessel
surrounded with water; in some cases the tubes are filled with
water, in others the water in the vessel flows all round their exter-
nal surface. This water must be kept constantly flowing through
the vessel, so as to maintain the refrigerating surface at a proper
working temperature. For this purpose a circulating pump is
fitted, which draws the water through the tubes or around them,
as the case may be; in other arrangements the water is forced
through or amongst the tubes. The water from the condenser is
carried off by an air pump similar in construction to that used for
ordinary injection condensers, and is delivered into a separate
vessel, from which it is pumped into the boilers, in some instances
directly by the air pump, but usually feed pumps are fitted for the
purpose. In some convenient part of the condenser a valve and
inside pipe are fitted, perforated with slits or holes for showering
into the condenser the sea water necessary to keep up the requisite
amount of feed for the boiler.
1
16
We now come to consider the manufacture and arrangement of
surface condensers. The tubes vary from ½ inch to % inch internal
diameter, thickness about inch; generally 34 inch outside dia
meter; they are made of composition metal, and are known by the
name of cold-drawn composition tubes. The tubes for government
contracts are tinned outside and inside to prevent chemical action.
They are 9 feet long.
9
6
6
The tube plates are of copper, and vary in thickness from
3
inch to 18 inch; they are fitted to plane surfaces on the casting
forming the vessel containing the tubes, and are secured with com-
position metal bolts and nuts. A variety of plans are adopted for
making the ends of the tubes air and water tight. The original plan
(Fig. 310), still much used, consists in forming screwed stuffing boxes
in the tube plate, the packing being a tape of cotton or linen sewn
together, which is slipped over the ends of the tubes, and pressed
into the stuffing box with a screwed gland. These glands are
manufactured from solid rolled tubes of composition or Muntz
metal, and can be obtained of suitable lengths; the inside diameter
must slip easily over the tubes in the condenser, while the thickness
is regulated by the size of the gland, so that a proper thread is cut
in a similar way to bolts in the common screwing machine; they
are cut off into proper lengths by a circular saw, and notched in a
machine with two notches, for screwing them into the stuffing box
MARINE ENGINES.
427
with a screw driver.
with a sheet of india
B
A
Another mode of making the tube joints is
rubber having holes suited to the pitch of the
tube. The holes are left smaller than
the outside diameter, and when the tubes.
are all in position, being merely passed
through plain holes drilled in the tube
plates, the india-rubber sheet is laid over
them, and an outside plate is bolted up
against it, which plate is recessed for the
reception of the tubes, and leaves a
narrow edge round each tube; thus with
the pressure, and the holes in the india
rubber being much smaller than the
diameter of the tube, a raised flange of
india rubber is formed around each tube,
and the tubes are gripped by an elastic
medium, while the pressure transmitted
through the plate by the bolts to the
flat surface of the india rubber keeps it
in perfect contact with the plate, and a
Some engineers, however, think that each
tube should be made air and water tight separately, so that if a
joint gets out of order it can be repaired without disturbing the


Fig. 310.-Tape Packing for Tubes.
A, Tube. B, Packing gland.
good joint is obtained.

B
whole series; besides with such
thin tubes it is an object to have
the joint elastic, so that the tubes
can expand and contract easily.
With these objects in view the
author has arranged a packing ring
of a peculiar construction. The
holes in the tube plate are bored
parallel, and then tapped; a gland
or screwed nut having a recess for
a ring of india rubber or any other
elastic medium is fitted to each
hole. The india rubber ring is a
good fit in the recess, and is put in place by merely squeezing
it together; its inside diameter is made smaller than that of the
tube, according to the amount of grip required; and to facili-
tate the operation of tubing, a loose cone plug is inserted in
A
A
Fig. 311.-Sheet mode of making the Tubes tight.
A A, Tubes.
B, India-rubber sheet. c, Plate.
428
MODERN STEAM PRACTICE.
D
the ring, and the nut being placed over the tube when in posi-
tion, it is screwed up, then the cone is forced through the india
rubber and expands it for the reception of the tube; in this way
the ring is spread out, tightly filling the recess, and binding the
tube firmly; the nut is screwed hard up on the tube plate, against
a washer, or simply metal to metal, having a little red lead inter-
posed. By this plan the tubes can be readily and quickly made
tight, and the elasticity of the ring allows of free movement
for expansion and contraction. When
india rubber is used the tube ends should
be tinned to prevent the deterioration
which takes place when brass and india.
rubber are in contact. In some ar-
rangements when the water is forced
through the tubes, their ends are made B
tight with a simple flat ring washer of
india rubber, placed over the tube
tightly, the flat end surface bearing on
the tube plate, which is recessed for its
reception, and in others wooden plugs
are used, driven over the tubes, and в
firmly held in the tube plate, the expan-
sion of the wood when wetted making
a very good joint.

A
Fig. 312.-Packing Ring for Tubes.
gland and india-rubber ring. D, Cone.
The arrangement of the refrigerat-
ing surface now falls to be noticed.
When the water passes through the A, Tube. BB, Tube plates. c, Screwed
tubes and the steam all around them,
we obtain a larger amount of surface than when the steam is
condensed inside of the tubes; but in the former case any incrus-
tation that takes place tends to choke up the spaces between
the tubes, and so far renders them useless, as there is no pos-
sibility of getting them cleaned; whereas, when the steam is con-
densed inside of the tube, the surface can be cleansed occasionally.
Again, should any of the tubes require repacking at sea, with the
water circulating around them, the large covers which form part of
the condenser require to be taken off, and should any leakage
occur through the joint being imperfectly re-made, air finds its way
into the chamber and impairs the vacuum; whereas, when the
water passes through the tubes, with any leakage occurring, the
MARINE ENGINES.
429
water simply finds its way into the ship, and the working of the
engines is not sensibly affected. Looking, however, at all sides of
the question, we may conclude that the advantages are in favour of
inside condensation,-provided that the circulation of the water is
properly attended to and uniformly distributed all round the
exterior surfaces. When the surface system of condensation was
first introduced into side lever engines for the Royal Navy, 2800
square inches of tube surface was adopted for the condensation of
60,000 cubic inches of steam per minute, the quantity of cold water
-injected being 10 gallons. To compare these quantities with pre-
sent practice, let us take an example of an engine of 400 nominal
horse-power, having 3170 square inches of area in each cylinder,
with a piston speed of 300 feet or 3600 inches per minute:
3170 × 2 × 3600_ 380 × 2800
60000
144
=
7389.
We thus have 7389 square feet of tube surface, equal to 184 square
feet per nominal horse-power. It will be observed that this result
is about the same as that given for total heating surface of boiler
per nominal horse-power, although it is in excess of present prac-
tice, 15 to 16 square feet of condensing tubes being now considered
sufficient. To find the quantity of water required for condensation:
a cylindrical foot of water equals 5 gallons, 10 gallons will be con-
tained in 3456 circular inches, and as 380 times 60,000 cubic inches
of steam passes the engine per minute, we have
3456 × 380
3600
=
364 ÷ 2 = 182
circular inches of area for each pump, when two pumps of the
double-action type are fitted—or a diameter of say 14 inches will be
enough for each of the two circulating pumps. (See pages 508-510.)
The air pumps are generally made of the same capacity as for
plain injection condensers, and when one circulating pump is fitted,
it is of the same capacity as the air pump; one set of patterns thus
serves for both, and in the event of using the condenser with plain
injection, valves are so arranged that the circulating pump can be
used for an air pump. The circulating pump should be fitted with
a valve for turning on the bilge water, in case of great leakage in
the ship; a valve must also be placed on the pipe for shutting off
the sea-water. Should both of the pumps be used as air pumps
(in cases of failure), a bilge injection valve should be fitted. When
430
MODERN STEAM PRACTICE.
a separate centrifugal pump is used, driven by a small engine, for
circulating the water, and two air pumps are fitted, the centrifugal
pump should be arranged to pump the bilge water overboard, and
one of the air pumps turned into a circulating pump, the requisite
valves being placed so as to be opened at the shortest notice. To
provide against any accident to the surface system, a plain injection
valve is placed on the condenser, and a valve is also fitted at some
convenient part to drain all the water out of the condenser when
necessary.
B
A
Connecting-rod Engines.
A, Tube chamber. B, Air pump. c, Circulating
Various arrangements of the tubes for surface condensers are
adopted. For direct-acting horizontal engines of the return con-
necting-rod type, they are ar-
ranged vertically, placed between
the crosshead guides in one, or
else there is a separate condenser
for each cylinder. The steam
from the cylinders enters above
the top plate, and being con-
densed falls directly through the
tubes into the air pump, which
is situated on the inside of the
outer frame, and worked directly
from the steam piston, while the Fig. 313.-Vertical Arrangement of Tubes for Return
circulating pump occupies the
same position as regards the
other cylinder; the water is
drawn through the vessel containing the tubes, coming in at the
top, circulating around the tubes, and being drawn away, instead
of forced, by the circulating pump. The bottom part of the con-
denser is generally cast in two, containing the guide bars for the
piston-rod crosshead, the chamber for the gun-metal air pump or
circulating pump, barrel, valve seats, air vessels, &c. The flange
for holding the bottom tube plate extends the length and breadth
of the casting between the guide bars, and is planed all over; the
bottom tube plate is fitted on it, the vessel containing the tubes is
placed over it, and the top tube plate secured on the top. Above
this is placed the top part of the condenser, where the steam enters;
it is fitted with covers on the top for getting at the tubes, the
bottom joints are reached through a door on the bottom chamber
of sufficient height for a man to enter. Some arrangements of the

pump.
MARINE ENGINES.
431
vertical type have a circulating pump worked directly off the piston,
with an arm keyed on the bottom piston rod for taking the air-
pump rod; two circulating and two air pumps are fitted, in other
B
Fig. 314.-Vertical Arrangement
A, Tube chamber. B, Air pump.
c, Circulating pump.
Å
words the separate condensers have each a
circulating and air pump. As the water,
either from the sea or from the condensa-
tion of the steam, gravitates directly into
the pumps, this arrangement is very effec-
tive, although the circulation of the water
is not so good as could be desired—a fault
inherent in all cases where the conden-
sation takes place inside of the tubes;
nevertheless, when the water passages are
suited for each Cylinder independently. properly arranged, inside condensation is
to be preferred, as there is then some pos-
sibility of cleaning the tubes from lubri-
cating matter carried over by the steam. As an improvement on
the vertical arrangement, some engineers have made the condenser
cylindrical, with a space in the centre for the steam pipe from the
cylinder, around which the tubes are arranged in rings. The ex-
haust steam pipe is perforated with holes for distributing the steam
equally; the condensing surface is on the outside of the tubes, the
water circulating through them. In some cases the condenser is
fitted with circulating and air pumps worked directly off the piston,
in others the air pumps work direct, with a centrifugal circulating
pump driven by an auxiliary engine.

For
The horizontal arrangement of tubes next claims attention.
direct-acting horizontal engines the tubes are placed fore and aft
the ship, arranged in three divisional parcels, with the view of
giving time for the transit of the circulating water which is being
forced; and this passes in the first instance through the bottom
row, returning through the middle row, and then passing through
the third or top row before escaping overboard,-in this way securing
a more equal distribution. The condenser vessel may be cast in one
or more pieces, with all the necessary passages, valve seats, &c., for
the pumps; the joint faces for the tube plates are all planed, and the
tube plate accurately fitted. As the doors for getting at the tubes
are placed at the ends of the condenser, both of the tube plates
are easily managed, whether as regards fitting in the tubes in the
workshop, or repairing leaky joints at sea. To ease the passage of
432
MODERN STEAM PRACTICE.
the water through the tubes, flat air vessels are cast along with the
end doors, by which the flow of water is rendered smoother and
A
Wit
B
Fig. 315.-Horizontal Arrangement of Tubes for Return
Connecting-rod Engines. A, Tube chamber. B, Air
pump. c, Circulating pump.
more equal. The steam enters
at the top through an exhaust
pipe at each corner, the water
from condensation falls down
amongst the tubes and is car-
ried away by the air pumps;
one pump only is fitted to
engines of small power, but
heavier engines have two air
and two circulating pumps.
From the great number of
such tubes required to give the

necessary cooling surface, or about 2 square feet per indicated horse-
power, the length reaches in large vessels to many miles of tubing;
thus in the surface condensers for the new Inman steamer City of
Rome, the total length of tubes is about 17 miles.
It appears to be of little consequence whether the water flows in-
side or outside of the tubes, so long as a good circulation is kept up.
Sometimes the tubes are arranged independently for each
cylinder, the water from the circulating pump only passing through
the tubes twice, instead of three times. The pumps are located on
each side of the middle frame, and are worked directly off the
piston of each cylinder. They are of large diameter, one end being
fitted for the circulating pump, and the other end for the air pump;
thus for each function this arrangement may be termed a single-
action double-acting pump. There is one central chamber and
pipe for the suction to the circulating pumps, which first discharges
the water right and left into a chamber common to both, and then
through the tubes; the water returns through the top row, and is
discharged into one central chamber, with one pipe overboard for
both pumps. The arrangement of the valve seats is simple: they
are sometimes placed at the side of the pump, sometimes at the top
and bottom. It may be questioned whether single-acting circulating
pumps are preferable to smaller sized double-action pumps. Many
engineers are in favour of the double-action type, but consider, so
long as a sufficient quantity of condensing water passes through or
amongst the tubes, that a single-acting pump, discharging into a
capacious air vessel, makes the flow quite uniform enough for all
MARINE ENGINES.
433
practical purposes.
The doors in the arrangement of condenser
under notice only admit of inspecting one end of the tubes; for
packing their central ends a manhole is arranged in the bottom
and top chambers, through which the water enters the tubes at the
bottom, and from which it is discharged overboard at the top. A
plate abutting on both tube plates forms the division between the
two. This arrangement is very good for engines of large power, as
the tubes are of a suitable length, neither too long nor too short.
To facilitate the water from the condensed steam flowing away
from the tubes, when condensation takes place on their internal
circumference, the tubes have been arranged lying at an angle.
They may be so disposed right and left, or all in a cluster; when
arranged right and left, the central chamber, as in the foregoing
example, becomes the exhaust steam chamber, instead of the water
chambers. The air pumps are arranged on each side of the outer
frames of the engine, and the circulating pumps on each side of the
central frame; the suction valves for both pumps are inverted and
placed above the pumps, while the discharge valves are arranged
alongside, the circulating water flowing amongst the tubes at the
bottom end near the central frame, and ejected from the vessel
containing the tubes at the opposite corner at the top: thus the
water is well distributed amongst the tubes-a very necessary thing
to attend to in all arrangements.
The valves for the pumps are of the round disc type, made of
india rubber, having grated seatings and guards of brass. Some of
these valves fold up all round against a saucer-shaped guard per-
forated with holes, and are secured to each hole in the condenser
by a cross bar of iron and a single bolt. This bolt passes through
the centre of the bar, seating, and guard, and is secured with one
nut at the top, pressing the guard and seating downwards, and
drawing the cross bar upwards against the under side of the metal
surrounding the hole in the condenser casting; but the general way
is to secure the guard and valve by a screwed stud with a nut at
the top to a large plate containing all the gratings for valves, the
plate being secured over one large hole in the condenser casting by
gun-metal stud bolts and nuts. Sometimes the guards are made
quite flat, the valve moving upwards and downwards on the boss.
of the guard, the central hole in the india-rubber disc being made
slightly larger, so that it moves easily; this arrangement can be
secured with a cross bar, or with stud bolts, on a plate common to
28
434
MODERN STEAM PRACTICE.
all the valves, as before described. The gratings for these valves
are formed of ribs radiating from the centre, having one or more
concentric rings, keeping the area of each hole in the grating equal
to about I square inch. The ribs on the guard radiate from the
central boss, and the ends of the elongated apertures are rounded
or left square as taste may dictate. Other forms of valves are
oblong shaped, folding up against a flat guard, the india rubber
being secured at the middle with stud bolts; the holes in the
gratings being made hexagonal, formed around a circle I inch in
diameter. This grating resembles a honeycomb, and may be said
to combine the greatest area with the least material, thus obtaining
more free way for the passage of the water-a very desirable point
to attain in designing pump valves. For this object a valve seat
has been designed by the author in which five discs can be placed
in about the same space as is usually occupied by one; the seating
is in the form of a square box open at the bottom, with a flange
all round for securing it to the condenser, one valve being placed
on the top and one on each of the four sides. This plan can be
modified by making the valve seating cylindrical, the side valve
being simply a band of india rubber, secured at one end to the
cylindrical seating, and a round disc valve placed on the top. The
action of the band valve is one of expansion and contraction as it
opens and shuts with the reciprocating motion of the pump piston,
or plunger if so fitted. It is scarcely necessary to state that india-
rubber valves will work in any position, whether lying flat, or at an
angle, or even inverted; the latter position is fast finding favour,
where the passages of the pump are so arranged that the water
gravitates into the pump chamber instead of being sucked or
drawn in.
The pistons for the circulating pumps of direct-acting horizontal
engines are packed with a metallic ring; in some instances wood
packing has been adopted, lignum-vitæ being preferred. In other
cases plungers instead of pistons are used. The plunger consists
of a cylinder of brass working in a central stuffing box, hemp
packing being used in the form of a gasket. The cylinder forms
as it were the pump barrel and piston, as in the double-action
pump: it is worked directly off the steam piston, with a small rod
secured to the cylinder with a single nut. It may be argued that
the plunger is heavier than a plain piston, but it must be remem-
bered that as it is surrounded with water, it partially floats as it were
MARINE ENGINES.
435
in the fluid, consequently the wear is much reduced; however, for
surface condensers it is not so compact as a plain piston. Some-
times the water chambers at the ends of the pumps are partially
filled up with a cylindrical casting, formed on the end covers; the
piston rod works through this at one end, and it is left plain at the
other end of the pump,-that is to say, no stuffing box is required,
but the cylindrical filling-up piece is simply cast along with the
end cover.
Air Pump.-The air-pump barrel is cast in brass, with fitting
C
B
G
B
Ꮐ
A
E
Fig. 316.-Air-pump Barrel and Piston.
A, Barrel.
B, Piston.
c, Rod. D, Junk ring.
E, Packing ring. F, Parallel part on rod.
GG, Tap bolts.
rings at each end and at the
middle, which are turned to fit
the parts bored out in the con-
denser casting; the barrel is se-
cured by lugs cast on the end,
with brass bolts for firmly bolt-
ing it to the condenser. When
internal plungers are used, the
barrel of the pump forms as it
were the central gland, which
is packed with hemp in the usual
manner. All the bolts and nuts
used in the internal fittings
should be of brass or Muntz
metal; this is absolutely neces-
sary, for with wrought-iron nuts
oxidation rapidly takes place,
and the violent motion of the
water passing through the pumps
would wash away the rust as it
formed, and soon render the bolts
useless.
The pistons are of the usual
kind, cast in brass; some are
merely recessed for the recep-


tion of a plaited gasket, while others have metallic spring rings,
the piston being fitted with a junk ring held down with bolts;
a gasket is sometimes placed in the space between the brass
packing ring and the body of the piston, thus dispensing with
springs for keeping the packing ring up to the face of the barrel.
Hydraulic pressure is conveniently employed in some pumps
436
MODERN STEAM PRACTICE.
for this purpose.
A small hole is bored at each end, in com-
munication with the open space between the ring and the piston,
and the mere forcing of the water causes a pressure inside, which
presses the packing ring outwards against the barrel of the pump.
When one ring is used, a small india-rubber ball valve opening
inwards, placed at both ends, will tend to make the action more
perfect; as the piston is going forward the front valve would open
and the back one would shut, and vice versa; thus there would be
no escape through the piston, but probably this is not required, as
a very small hole suffices, and the escape is but little felt; and if
two rings were fitted in recesses, one hole suffices at each end.
Thin spring rings of brass have been used with advantage; in this
case the piston is made quite solid at the ends, with three recesses
turned out on the rubbing surface for the reception of the rings,
which are truly turned a

с
B
A
very little larger than the
interior diameter of the
pump; they are then sawn
through at one part, ex-
panded over the piston,
and sprung into the re-
cesses; in this way there
is a slight spring in the
rings, which keeps them
well up to the surface of
the barrel. Wood packing
with lignum-vitæ has been
often successfully used;
the piston is cast as before,
and the space for the
packing is filled up entirely with curved blocks, which are made
to overlap one another at the joinings, and then the ring is turned
to the exact diameter of the barrel, the body of the piston being a
trifle less in diameter. This arrangement is what may be termed a
solid piston, and is one which can only be adopted with a material
that expands in water; lignum-vitæ is well fitted for the purpose.
Solid brass pistons without any packing have been tried, but did
not succeed, as they soon failed to afford a perfect vacuum. Hollow
plunger pistons have, however, been arranged, both internally and
externally. In the former plan the plunger has a central packing

Fig. 317.-Air-pump Plunger and Gland.
A, Plunger. B, Stuffing box and gland. c, Rod.
MARINE ENGINES.
437
gland for forming the joint between the two ends of the pump; it
is solid at the ends, and has a boss at the centre, bored out for the
reception of the Muntz metal rod, which is secured by a screwed
part at the end with a brass nut, drawing up the plunger against
A
ག.
B
Fig. 318.-Air-pump Plunger and Gland.
a collar formed on the rod. In
the latter plan the plunger is
moved by a connecting rod
working directly from the
cranked shaft, having a bear-
cing inside of the plunger. For
this arrangement the bushes
and glands should be made
very deep; while in others,
when the main connecting rod

A, Plunger. B, Stuffing box and gland. c, End cover. for the engine works a plunger, '
which in its turn moves the
D, Bearing.
steam piston by rods attached to it, it is advisable to form the
bottom bush of the gland the entire length of the stroke, thus
supporting and taking the thrust of the connecting rod on a large
surface. In this arrangement of air pump it is necessary to reduce
the area of the plunger, by having a hollow guiding trunk at the
other end, working through a suitable packing space and gland.

B
A
E
Fig. 319.-Air-pump Plunger acting as a guide for the Crosshead and Piston Rods.
A, Plunger. B, Stuffing box and gland. c, Hollow guide. D, Bearing. E, Rod for adjusting brasses.
All air-pump rods should be made' of Muntz metal, secured to
the rod from the main piston by a cotter passing through a boss
formed on the wrought-iron rod which is bored out for its reception.
The foot and head valves are formed of discs of india rubber,
working on brass seatings. They are introduced in all fast-going
engines, to lessen the disagreeable sound caused by the metallic
valves, and they have materially assisted in bringing the direct-
action engine to that high state of perfection which it has now
438
MODERN STEAM PRACTICE.
attained. Still further to diminish the noise, the lift of the india-

rubber discs is limited by
means of a curved guard, hav-
ing a boss at the centre; this
boss rests on the seating, and
is bored out for receiving one
end of the holding-down bolt,
the other end passing through
a cross piece of wrought iron,
which bears on the under side
of the round hole over which
the grating for the disc of india
rubber is placed. The hole
in the india-rubber disc should
fit loosely round the boss
formed on the guard, and in
no case should the india rubber
be pressed down on the seat-
ing. These gratings consist
of annular rings and ribs ra-
diating to the centre of the
boss, thus forming a number of
oblong holes through which
the water passes. The guard
also requires to be pierced with
holes, as the discs of india
rubber have a tendency to
work or close slowly, were
not the water acting on the
top surface and pressing it
downwards on the return
stroke. Some of these valve
seatings are secured by brass
stud bolts and nuts, with
lugs cast on the seating for
bolting them down over the
holes left in the condenser
casting, the joint being made
with a ring of india rubber
recessed into the seating;
E
A
Fig. 320.-Single Valve for Air Pump.
A, Valve seat. B, India-rubber valve.
c, Guard.
D, Holding-down bolt. E, Cross bar.
B
O
о


C
C
C
a
A
Fig. 327.-Arrangement of Valves adopted for Air
Pump.
A, Grating. B, India-rubber valve.
DD, Studs for guards.
CC, Guards.
MARINE ENGINES.
439
while the guard is secured to the seating by a plain bolt and nut.
The plan now universally adopted is to cast a number of these
circular gratings in one large brass seating, which is bolted down
over the oblong holes left in the casting; this brass plate is
strengthened with bars on the under side, and has a flange all
round for the holding-down bolts, which are screwed in the casting
as studs with nuts on the top; the guards are fastened down to the
valve gratings by a stud bolt passing through each guard, having
a nut bearing on the top of the guard; in other cases the stud is
B
D
B
A
Fig. 322.
Box Valve Seat with sloping sides,
arranged for five Valves for the Air Pumps.
A, Box with five valves. B B, India-rubber valves.
cc, Guards. D, Stud for guard.
formed with a collar to screw up
against in the grating, which
collar is somewhat deeper than
the thickness of the india rubber,
and the guard is bolted down on
the top of it. All the nuts on
these studs should have split pins
passing through the points of the
bolts, to prevent the guards shak-
ing loose. In some arrangements
the valve seats are all bolted
down to one brass seating, having
a number of large holes left in
it and bored out for their recep-
tion; and when the large plate
is properly planed on the surface,
and all the small gratings turned,
the joints may be simply me-
tallic, with a little thin red lead
placed between the surfaces
before they are bolted down. In
some instances it is advisable to
place a number of valves in a
small space; with this object in
view, as well as to decrease the


circumferential opening of the valves, and yet give a large area
for the passage of the water, the valve seating may be made in
the form of a square box, open at the bottom, with side flanges
all round for bolting it to the condenser casting. With this
form one valve can be placed on the top and one on each side,
making five valves in all; thus with this arrangement, and the same
44.0
MODERN STEAM PRACTICE.
lift of valve as in the former examples, five times the area is
obtained; or with excessively
fast-going engines, the lift of
valve can be reduced, a great
desideratum even with india-
rubber valves, for undoubt-
edly the wear and tear cannot
be so great, while the area
for the passage of the water
is always greater than in a
single valve. In another ar-
rangement four valves are
placed on the top of a square
box, and two on each side,
making twelve valves in all.
These sets, and indeed all
india-rubber valve arrange-
ments, can be placed upside
down, or at any angle that

A
C
Fig. 323.--Box Valve Seat with square sides, arranged
for twelve Valves for Air Pumps.
A, Box with twelve valves. B, India-rubber valve.
c, Guards. D, Stud for guard.
may be considered best for the free entrance and exit of the
water from the air pumps. In-
stead of round valves, some
makers cut the india rubber
into oblong flaps, hinged at
the centre and folding up
against the guard on each
side; by this means the holes
for the bolts do not weaken
the india rubber so much as
when they are placed along
the edge. The holes for the
passages of the water are
hexagonal, formed around
circles I inch in diameter,
with webs similar to a honey-
comb. The area through the
valves should be as large as
possible, and the grated space
equal to the length and
breadth of the hole in the

C
D
A

о
О
0000000
Fig. 324.-Double Oblong Valve with Hexagonal
Grating for Air Pumps.
A, Grating.
B, India-rubber valve.
DD, Studs.
c, Guard.
MARINE ENGINES.
441
H
condenser, even although half-grated holes are cut in the pattern;
they are bolted down with stud bolts and nuts, and collar bolts at
the hinge for taking the flat guard, these bolts being screwed into
holes bored and tapped in cross webs cast in the condenser for
supporting the grated plate, because with the peculiar form of
hexagonal holes it is not convenient to introduce strengthening
ribs in the grating.
Discharge Valve. We will now consider the arrangements
Valve.-We

E
0

A
C
G
A
0
D
IE
B
Fig. 325.-Brass Discharge Valve and Box for Dis-
charge Pipe from Hot Well, fitted with Expan-
sion Joint. -A, Valve. B, Chest. c, Stuffing
box and gland. D, Lifting spindle. E, Cover.
F, Cotter. G, Hole for donkey feed-valve box.
H, Branch at side of ship.
Fig. 326.-Brass Discharge Valve and Seat, with
cast-iron Valve Chest for Discharge Pipes from
Hot Well. - A, Valve. B, Chest. c, Lifting eye
and spindle. D, Cover. E, Hole for cotter.
F, Hole for donkey feed-valve box.
G, Branch
at side of ship.
required outside of the condenser. The discharge pipe from the
hot well should be fitted with an expansion joint, placed on the
valve chest at the ship's side; this valve is introduced so that the
sea water can be shut off when the fittings inside of the condenser
and air pump require inspection. The valve in most cases is a
spindle one, with a long rod secured to the top, passing through a
stuffing box on the valve-chest cover, and having a ring handle
fitted at the top, for attaching a block and tackle for lifting it; and
as the valve box is generally placed inside of the coal boxes, means
442
MODERN STEAM PRACTICE.
for lifting it from the orlop deck should be provided. In other
examples the valve is coned, fitting into a seat turned out for its
reception, the rod at the top being secured by a nut on the under side,
and having a ring handle as before; when the valve is lifted up a
flat key is driven through a slotted hole in the rod, the key rests on
the top of the gland, and by this means the valve is held up. Hemp
packing may be placed in a recess turned in the valve to insure its
being perfectly water tight. A variety of forms of gridiron sluice
valves have been introduced, each
having a screwed spindle stepped
at the bottom of the valve chest,
and working in a nut on the back
of the valve, passing through a
stuffing box in the cover, and its
end fitted with a handle. Outside
of the stuffing box a collar is left
on the rod, which is held down by
this collar placed under a cross
bar fitted to the cover with studs;
thus when the handle is turned
round, the nut and valves move
up or down, opening the apertures
or shutting off the sea water when
the handle is turned the reverse
way. For convenience in turning
the handle, the valve chest should
be placed outside of the coal boxes,

Ꮐ
运
​D
cast-iron Valve Box for Discharge Pipes
from Hot Well.
Valve. B,
Chest. c, Lifting eye and spindle.
D, Cover. E, Hole for cotter. F, Hole for don-
key feed-valve box. G, Branch at side of ship.
are used on the side of the
and a strong pipe fitted between Fig. 327. - Conical Brass Valve and Seat, with
it and the ship's side. The valve
chest may be of cast iron, but a,
the valve and seat should be of
brass, and the top spindle of Muntz
metal. Sometimes large flap valves
ship; these are generally hung with a spindle at the top passing
through the side of the box, and may be kept shut with a weighted
lever on the end of the spindle: this plan has the advantage of the
valve opening outwards, and should the engine be started with the
valve shut, the pressure of the water in the discharge pipe would
open it.
Of course spindle and conical valves are likewise placed
so that the discharged water forces them up; but sluice valves must
MARINE ENGINES.
443
be moved by hand before starting the engines, and in that respect
they are not so safe as the spindle valves and other arrangements.
The injection valve is simply a sluice, placed in a suitable valve
M
C
E
B
Fig. 328.-Sluice Injection Valve.
A, Sluice valve. B, Chest. c, Cover. D, Spindle.
E, Condenser.
chest, which is bolted to the
side of the condenser; the
valve is of brass, sliding
against a surface of the same
material, let into the cast-
iron valve box. The valve
is provided with a Muntz-
metal spindle, keyed through
a boss cast on the back of
the valve; at the top end of
the spindle a slotted cross-
head is fitted for the lifting
lever to pass through, and
which is generally arranged
on the top of the condenser.
Gridiron valves are some-

times used, which are moved by a spindle attached to the valve
with an eye and pin passing through a snug cast on the back of
the valve; with this arrangement it is advisable to cast the valve
L
E
B
A
C
白
​O
Fig. 329.-Gridiron Injection Valve.
A, Gridiron valve.
B, Chest.
lifting arm.
О
c, Cover. D, Joint for
E, Condenser.
chest in brass, having a
screwed packing nut at
the top
top for the valve
spindle, with a corres-
ponding screw tapped or
cut in the valve-chest
cover. For engines of
small power plug taps
may be used, so arranged
that the water comes in
through a branch on the
bottom side of the conical
valve seat, and passes


through a hollow plug, the
bottom part of the cone
being tapped for the reception of a screwed brass piece which
is brazed on the tapered copper injection pipe. The top part
of the plug is fitted with a packed gland, or a gland without.
444
MODERN STEAM PRACTICE.
seat.
H
packing may be used; this is introduced to keep the plug in its
A handle is keyed on the plug for moving by hand, or levers
are arranged with rods passing along to the starting platform.
The inside injection pipe is made of a conical form, tapering from
the valve to the end; the apertures are placed so as to shower the
water over a large surface in a way regulated by the form of the
condenser. These apertures are bored out, or else cut across with
a saw; the former plan may be named the jet system, the latter the
sheet system, as the water then falls into the condenser in small
sheets. The injection pipe is sometimes fitted with a longitudinal
plate passing up the centre for one half of its length, by which the
water after passing through the injection valve is divided into a top
and bottom stream, with holes pierced in the pipe for each; but
this is an unnecessary refinement, for the injection valve may be
placed on the condenser, so that the
internal pipe can have a branch on
the middle of its length, and thus
distribute the water right and left.
This form of internal pipe should
likewise taper from the middle to
each end, so that the jets at the
end may rush into the condenser
with about as much force as those
nearest the valve; for undoubt-
edly were the pipe made quite parallel, and pierced with the
same number of apertures along its entire length, the pressure
of the water would decrease at the extreme ends, owing to its
escaping into the condenser, but the tapering of the pipe contracts
the water along its entire length, and the pressure from the head of
water outside of the ship is better maintained, consequently the
water is showered over the condensing area more equally. It is
necessary to support these inside injection pipes, as the weight of
water is considerable; this can be done with a wrought-iron support,
fastened to any of the ribs inside of the condenser.

4

Fig. 330.-Inside Injection Pipes.
A, Injection pipe tapering toward ends.
B, Tapering injection pipe.
The bilge injection valve (Fig. 331) is fitted as low down in the con-
denser as may be deemed necessary, and consists of a spindle valve
of brass fitting into a seat cast along with the valve chest, also of
brass. The valve has a spindle on the top passing through a stuffing
box in the cover; the top end of the spindle is screwed, and works
through a brass bush secured in a cross bar, which is supported
MARINE ENGINES.
445
with suitable studs let into the cover.
F
On the end of the spindle a
plain handle or small hand wheel is fitted, by which the valve is
screwed up from and down on its seat. These
valves are only used in the event of great leak-
age in the ship, the bilge water being then taken
into the condenser, and pumped overboard as in
the ordinary injection system. In order to keep
foreign matter from entering the condenser, it
is necessary to protect the pipe passing from the
bilge injection valve down to the bottom of the
ship with a box piece at the end, perforated with
a number of small holes.

B
A
E
Valve.A, Spindle and
The snifting valve, for blowing all the air and
water out of the condenser previous to starting
the engine, is placed at the lowest part of the
condenser, on which a branch is cast for holding
it. It is a spindle valve opening upwards, and is
Fig. 331.- Bilge Injection fitted with a baffle plate placed on the valve box,
valve. B,Chest. c,Cover. through which a thumb screw works in a screwed
brass bush; by this means the valve is held
down after the process of blowing through is
completed, and indeed, when the vacuum is formed in the con-
denser, the atmospheric pressure comes instantly into operation,
firmly closing the valve, which can then be
secured by the thumb screw at leisure.
D, Crosshead.
EE, Col-
umns. F, Hand wheel.

B
A
The feed pump is generally of the single-act-
ing plunger type; the body of the pump is of
cast iron, with a brass gland and bush at the
bottom of the stuffing box; when bolted to the
side of the condenser casting, the brass plunger
is worked from an arm keyed on the piston
rod, and has an inside rod of iron, by which
the plunger can be disconnected while the
engine is in motion. The disconnecting gear
consists of a thumb screw pressing against a
brass block let into the end of the pump ram,
the inside rod being of sufficient length to
work loosely in the hollow ram when the plunger is at the bottom
of the stroke. When connecting the pump, the thumb screw should
press lightly on the brass block until the plunger is pressed up
Fig. 332.-Snifting Valve.
A, Valve. B, Chest. C, Cover.
D, Set screw.
446
MODERN STEAM PRACTICE.
E
A
against a collar left on the rod (this must take place in the act of
forcing the water), the ram is drawn outwards, and in the return
stroke it slips or slides on the bush piece, until it is stopped with
a collar on the rod, then the thumb screw
can be tightened up. This simple contrivance
is far superior to any other for disconnecting the
plungers when the engine is in motion. Some D
makers prefer placing these pumps at the back
of the condenser, fitting them to the platform
on which the gearing is located for handling
the engine, either above or below the centre line
of motion of the piston and adjuncts; with the
former arrangement the plunger is connected
to a stud placed on the top of the crosshead
arm for taking the piston rods, and in some
cases is worked directly from a prolongation of
the air-pump rod, which passes through a stuff-
ing box at the back of the air-pump cover.
Piston pumps are sometimes used with ad-
vantage, the brass cylinder in which the solid
or packed piston works being let into a part
of the condenser casting, and generally worked
directly off the steam piston, in the same
manner as the air-pump piston; with this ar-
rangement the pump is double acting, one end
being used for the feed and the other for the
bilge pump. The latter, in other arrangements,
is exactly similar to the feed-pump barrel, and
is placed on the condenser on the opposite
side of the centre line of crosshead from that
of the feed pump, and can be worked off an
arm keyed on the piston rod; or when it is
fitted to the starting platform at the back of
the condensers, it is connected to the bottom ▲, Pump.
A,
arm of the crosshead in a similar way to that
of the feed pump. Many prefer the pump ar-
rangements fitted to the condenser, as the labour of fitting up
is thereby greatly reduced, and the engine as a whole rendered
more compact.

Fig. 333.-Feed and Bilge Pump.
rod.
B, Ram. c, Inside
D, Thumb screw.
E, Stuffing box and gland.
The valve box for the feed pump is of brass, and is generally
=
MARINE ENGINES.
447
placed at the end of the pump; the feed or delivery and the relief
valves are placed on the same level, while the suction valve is
C
A B
G
ABSTE
D
F
Fig. 334.—Valve Box for Feed Pump.
A, Valve box. B, Suction valve.
c, Delivery valve. D, Relief valve.
E, Spring. F, Bow. G, Set screw.
immediately under the relief valve, which
is fitted with a spiral spring compressed
by a set screw working in the top of a brass
bow placed over the spring; the pressure
on the valve should be a little in excess of
the steam pressure in the boiler. The sole
use of this valve is to allow the water in
the pump to escape into the hot well when
the feed regulating valve on the boiler is
shut; a branch is cast on the relief-valve
box, with a pipe leading into the chamber
above the head valves, by which the water
When not required in the boiler is returned
and finds its way overboard. A plug valve
for shutting off the suction is also fitted to
the valve box; this is used for shutting off
the water in the event of any of the pump valves requiring inspec-
tion, and may be used for stopping the supply to the pumps, in


B
C
D
A
TG
Ꮐ
C
A, Valve box.
Fig. 335.-Valve Box for Feed Pump.
B, Suction valve. c, Delivery valve. D, Relief valve. E, Spring.
F, Bow.
G, Set screw.
which case the plungers may be kept working, although no water
can be forced into the boiler or through the relief valve. India-
448
MODERN STEAM PRACTICE.
F
rubber valves are sometimes used for the feed pump, having
conical brass seats grated in the casting, and let into a cast-iron
valve box containing the suction, discharge, and relief valves,
the latter being a brass valve fitted with a spring in the usual
manner. All the valves may be placed on the same level; the
suction at one end of the valve box, the discharge in the middle,
and the escape at the other end, with a passage leading underneath
the discharge and escape valves from the top of the suction valve,
and a lower return passage from above the escape in connection
with the suction pipe or hot well. In some instances suction and
discharge valves only are fitted, with a separate relief valve placed
on some other part of the feed pipe. A similar arrangement of
valves is required for the bilge pump, but of course a relief valve is
not needed, as the bilge water is pumped directly
overboard, and a non-return valve placed on the
ship's side. The india-rubber valves are used
to prevent the disagreeable noise caused by
brass valves beating sixty or more times in
the minute. To obviate this evil wooden rings
have been recessed into the valve with advan-
tage. Perhaps the best plan of doing this would
be the Cornish one of recessing the wood into
the valve seating, in the same way as for large
double-beat valves for the pumps in deep mines.
The valves in this case would be discs turned Fig. 336.-Valve Box for Bilge
on the face, with central holes for working on
spindles; thus the valves are guided by this
means, necessitating a central boss with wood-
bearing surface. Of course the valves can be
of the spindle type, working through and guided
in the bosses cast along with the valve seats. An air vessel
should be placed on the feed-pump valve box, or on some
part of the feed pipe between the boiler and the top of the dis-
charge valve, by which any sudden strain caused by the passage
of the water through the pipes is greatly neutralized, and the
discharge into the boiler is rendered more equal.

D
Pump.
A
A,Valve box. B, Suction valve.
c, Delivery valve. D, Guard
with holding-down spindle.
E, Guard. F, Set screw.
by holes bored
The hand pump (Fig. 337) is an additional one, which can be worked
either by hand, or if required connected to the engine. Its duty is
somewhat complicated, as it must be fitted to draw water from the
boiler, from the bilge, and from the sea; while the discharge pipes
MARINE ENGINES.
449
must be arranged to pump water into the boilers, on deck, and over-
board. The most convenient form for this pump is the plunger type.
It is generally placed vertically at the end of the cranked shaft, the
body of the pump being bolted down to the engine keelson; some-
times it is placed horizontally, and is fitted to the condenser, fitting
strips and joggles being cast on the parts for its reception. The
trunk plunger is actuated by a pin and rod; the pin is fitted to the

B
о
K
D
E
end of the cranked shaft, and has a
rod with a plain brass bush, working in
a hollow plunger rod attached to a pin
passing through a joint at the bottom
of the plunger; this hollow rod has a
thumb screw and brass block at the top
for throwing into gear or disengaging
the pump.
When working free, the
inside rod merely moves up and down
in the hollow brass piece, which vibrates
along with the rod as the crank pin
revolves; when the pump is required,
with the engine in motion, a cotter is
driven through a slot in the brass rod,
and forms the stop for the inside rod
butting against, which it does gently
by means of the thumb screw and fric-
tion block, as with the feed pumps; the
thumb screw is then tightened up and
the connection is complete. For work-
ing the pump by hand, a bracket is
cast along with the body of the pump,
on which a lever is fitted, and flat side
gland. D, Hand lever with side connect- rods are connected to the pin at the
ing rods. E, Stud. F, Snug for stud.
Hollow rod. H, Thumb screw. 1, Con- bottom of the plunger, while the lever
necting rod. K, Crank pin on the end has a part forged along with it for the
reception of a long handle. When the
inside rod is disengaged, and when the engine is not going, or even
were it in motion, the pump can be thus worked by hand, the hollow
brass rod merely sliding on the wrought-iron one inside. Of course
when the pump is worked by the engine, the hand lever and con-
nection vibrate with the motion, it is therefore imperative that the
handle should be disengaged from the pump lever, a socket being
A
Fig. 337.-Hand Pump.
A, Pump. B, Plunger. c, Stuffing box and
G,
of shaft.
29
450
MODERN STEAM PRACTICE.
forged on it for that purpose. The pin on the end of the cranked
shaft is forged on a flat ring, which is accurately turned, and bolted
to the end of the main shaft, a projection being left on the shaft for
its reception. Some makers connect the pump by means of a plain
rod, having a sliding block fitted with a pin, working in a guide
formed on the disc that is bolted to the end of the cranked shaft;
this block and pin is moved by a screw and thumb handle, by
which means the stroke can be varied to any extent within the full
throw, and even brought to the centre of the shaft, thus imparting
no motion whatever to the pump ram. This is certainly a very
simple means for disconnecting the pump, but at the same time no
provision is made for working it by hand,
which is the chief thing to be studied in these
pump arrangements.
The valves are generally metallic, or india-
rubber discs may be used, and at the bottom
of the pump an escape valve is fitted loaded
with a lead weight. This latter valve is re-
quired, as there are many valves on the delivery
pipe which may be shut when the engine is
started, or even close when it is in motion, due
notice of which will be given by the water being
ejected through the escape valve. The end of
the suction pipe passing down to the bilges
must have a box perforated with small holes to
prevent foreign matter entering the pump.

B
A
H
茶
​E
G
Fig. 338.-Kingston Valve.
A, Spindle and valve. B, Chest.
E, Crosshead. F, Hand wheel.
G, Thumb screw. H, Grating.
Kingston valves.-Kingston valves must be
fitted to the pipes for injection, feed, and blow- c, Stuffing box. DD, Columns.
off for the boiler, steam pump, &c., and indeed
to all pipes passing through the bottom of the
ship. The arrangement here is similar to that for the oscillating
engine already described; strong cast-iron branches being placed at
the ship's side for preventing the rapid deterioration of the wrought-
iron plates by the galvanic action of the two metals-brass and
wrought iron-in juxtaposition, assisted greatly by the adjoining
copper pipes. In preference to the Kingston, some use spindle
valves, fitted with a screw on the spindle working into a nut in the
cross piece, having a jam thumb screw fitted on the top of the
crosshead.
The various arrangements of hand wheels for starting, reversing,
MARINE ENGINES.
45I
and stopping the engines are given in another part of this Work (see
page 110).
The usual hand gear for the blow-through, injection, throttle
valve, blow-off valve from cylinder, and all the other necessary
handles, should be arranged on the same platform. We prefer this
platform to be on the same level as the engine-room floor plates,
but some engineers place it on the top of the condenser; and cer-
tainly in this position the engineer commands a better view of the
machinery, but his duties when the ship is under steam lying
between the engine and the boiler rooms, the hand gear should be
placed in such a position that it can be reached at a moment's
notice, and as near the main starting wheel governing the link
motion for actuating the steam valves as convenient. The blow-
through, injection, and throttle valve handles should be placed in a

A
B
D
B
D
I
Fig. 339.-Hand Gear.
A, Injection handle and lever. B, Blow-through handle and lever. c, Throttle handle and lever.
D, Sectors. EE, Thumb screws.
row.
Some arrangements have a central rod for the injection valve,
a hollow tube with levers for the blow-through placed over it, and
another over this for the throttle. When thus arranged the rods
cannot be connected directly to the various valves, but the line of
motion can be conveniently changed by small sector wheels cast in
brass, and bevelled to suit the requirements; in other cases short
levers are keyed on the ends of the inside rod and to the outside
tubes, and fitted with pins and rods for changing the direction of
the motion.
Having considered the main details necessary in the manufacture
of the direct-action horizontal marine engine, we will now notice
the means to be adopted for effecting a thorough lubrication of all
the moving parts in the machinery. The main bearings are those
452
MODERN STEAM PRACTICE.
most important, and their friction can always be reduced to the
minimum by giving them ample rubbing surface,-this, combined
with good material and first-class workmanship, being essential in
all engines, more especially in those of great power, encountering
permanent loads, and working at a high velocity. Lubricators
should not be too elaborate in design; in their construction plain-
ness and efficiency should rather be aimed at. The oil cups placed
on the main bearings are cast in brass, with covers and oil pipes for
siphon wicks; they should be divided into two compartments, one
for the oil and another having a plain hole bored down through the
brasses, for water lubrication in the event of the bearings becoming
hot. To effect this properly a pipe is carried across the engine
directly over the main bearings, and supported with standards of
wrought iron secured to the main framing. This pipe is provided
with plug taps and water distributors for each main bearing and
crank pin; it also carries oil cups with long siphon pipes for
lubricating the crank pins, the wick hanging down a very little
past the end of the pipe. The water enters from the sea directly,
a branch pipe being cast on one of the Kingston valves, and an
ample flow is obtained for showering over the bearings in the case
of violent heating. Sometimes the standards for carrying the water
pipe placed over the main bearings are hollow pipes jointed on the
top of the framing, and provided with a valve at the bottom, one
pipe standard being placed on each frame; thus each bearing can
be supplied with water independently. The pipe at the top has
coupling joints with nuts, or simple flange joints may be adopted;
on the standard pipe nearest the Kingston valve a branch is cast,
for connecting the supply pipe to the Kingston, and a plug tap is
generally fitted to one of the standards, with means of attaching a
flexible pipe to it, for showering water over any other part of the
engine. The connecting rods have cups fitted on, with covers
having raised pipes and tongue pieces, for licking off the oil from
the siphon wicks suspended from the oil cup fitted overhead; by
this means the crank pin is thoroughly supplied at each revolution
of the cranked shaft. All the other lubricators for the engine con-
sist of cups cast in brass, fitted with inside pipes and siphon wicks,
and fastened to the various parts in such a way that they can be
removed when they require to be cleaned. Many journal bearings
have cups cast on, and plain holes bored through; this plan is
preferable to that of merely boring a countersunk hole in the journal
MARINE ENGINES.
453
brackets, into which the oil cannot be poured steadily, and generally
runs over on the machinery, whereas in the former plan the oil is
poured into the small oil cup and is beneficially used. The tallow
cups for lubricating the slide valve, cylinder, and pistons are similar
to those in general use, which have been already explained in
treating of the oscillating engine.
Turning gear.—When the vessel is in port, with the steam down,
it is necessary to turn the engines daily by hand, so as to change.
A
C
€
О
E
О
the relative position of the work-
ing parts, and prevent the fur-
rowing induced by the galvanic
action resulting from the contact
of the wrought-iron piston rods.
and brass glands, as well as to
facilitate the adjustment of the
slide valves or any other part of
the machinery. The arrange-
ment for doing so consists of a
worm working into a wheel fitted
to the end of the cranked shaft,
which has a cast-iron coupling
for bolting it to the boss or coup-
ling cast on the wheel; the worm
wheel being thrown in and out
with suitable mechanism. Some
makers simply key up the worm-
shaft bearings, which work in
blocks fitted to a cast-iron guide
plate, arranged across the line of
O the lying shafting; others place
the worm wheel vertically at the
side of the turning wheel, and
draw out the bottom bush on
which the worm shaft is stepped,
by means of a small hand screw
and wheel working through a brass bush cast on the plate the
bush rests on, the top part of the shaft being supported by a
bracket bolted to some part of the engine-room bulkhead. Some
engineers adopt an eccentric motion similar to the back motion of
a turning lathe, as a means of putting the worm wheel in and out


A
B
C
་་་་་
O
О
Fig. 340.-Turning Gear.
о
A, Worm wheel. B, Worm pinion. cc, Eccentrics.
D, Handle connecting the eccentric arms. E, Plate
for bolting to the bulkhead.
454
MODERN STEAM PRACTICE.
of gear.
A square part is formed on the end of the worm-wheel
shaft, to receive a ratchet brace lever, fitted with a double paul to
work either way, and a part is left on the lever to receive the
socket formed on the long hand lever, on the end of which is forged
an eye for securing a rope, which can be taken to any part, so that
a number of hands can be employed in turning the engine-a
needful provision as the back of the engine space is generally
confined.
BOILER FITTINGS.
T
C
Safety valve.-Amongst the boiler fittings the most important
is the safety valve. In river steamers there are generally two valves
fitted to each boiler, placed
in one valve chest, with the
waste-steam pipe between
them. The valves and
seatings are of brass; a
spindle of wrought iron is
fitted to the top of the
valve, passing through a
cover on the valve chest,
and is fitted with an eye
on the outside. This eye
is arranged so as to turn
round the valve with a
hand bar, to prevent it
becoming fast on its seat.
The valve is loaded with

B
G
Fig. 341.-Safety Valve.
B, Chest.
handle. E, Waste-steam pipe.
condensed steam. G, Boiler.
a certain weight placed in A, Valve and spindle.
the valve chest above the
valve; and on the outside
✩
c, Weights. D, Turning
F, Hole for running off the
of the casing flat discs of cast iron are placed on the spindle, or
taken off, as the steam is raised above the usual working pressure,
or is blown off by the waste pipe. The waste-steam pipe is of
copper, fitted with a gland and stuffing box, cast on the valve chest;
and there is a small branch at the bottom of the chest for running
off the water accumulating from the condensation of the waste
steam. This water is generally collected in a tank fitted to the
side of the vessel, and is used for cooking purposes, being an all-
important fresh-water supply for ocean steam ships.
MARINE ENGINES.
455
The safety valves for such ships differ materially from those of
river steamers, inasmuch as the weights are placed entirely in the
valve chest above the valves, or else inside of the boiler; the latter
method requiring a long spindle and socket connected to the valve
spindle. In the former method the valve-chest covers are under
lock and key, and in the latter the weights cannot be got at; the
valves cannot therefore be tampered with, or the boilers subjected
to undue pressure. Two safety valves are fitted to each boiler,
placed in one valve chest, with a branch cast on for the horizontal
copper pipes passing along to the branch pipe for the vertical
A, Valve.
A
TA
C
D
Fig. 342.-Safety Valve.
E
F
B, Chest.
c, Weights. D, Slot rod for
lifting arm. E, Lifting arm. F, Guide.
waste- steam funnel; this
branch is fitted with a stuff-
ing box and gland, to allow
for the expansion of the
copper pipes. The main
waste-steam pipe is fitted to
a flange on the top of the
central branch box, which is
made of cast iron, having a
small branch at the bottom
for running off the water de-
rived from the condensation
of the waste steam in the
act of blowing off from
undue pressure or otherwise.
The valves are lifted by a
lever arrangement, having a
spindle within the valve
chest; this lever is carried
along to any convenient
position, and supported by
a bracket at the end, which

is bolted to the top of the boiler; a long lever handle or other
arrangement is fitted at the end of the shaft, with a quadrant fitted
to the boiler, and drilled with a number of holes; a small pin is
provided, connected to a fine chain to prevent it being lost. By
this means the valves can be raised their full lift, or only a very
small part, as may be desired, and held in position by passing the
pin through the quadrant and lever handle. When the weights
are inside of the boiler, the spindle for supporting them has a pin
456
MODERN STEAM PRACTICE.
joint connected to a collar brass connecting piece, which is cottered
to the valve spindle, the forked lifting arms of wrought iron work
loosely on the collar, and the shaft is bracketed at the one end from
the crown of the boiler, and at the other end it passes through a
stuffing box with gland, fitted to the front plate of the boiler; the
shaft being fitted with a lever handle and quadrant, or any other
suitable appliance, such as a worm wheel and toothed quadrant on
the shaft, with a turning handle and bracket fitted to the worm
spindle.
In all arrangements for lifting the valves it is imperative that
their free action should not be interfered with; at any position of
the lifting levers, the valves when acted on by the steam pressure
must lift solely by that pressure, as the lever handles are only
arranged to lift the valves in the act of blowing out the boilers or
easing them when the engine is not at work. It is also essential
that all the rubbing parts should be bushed with brass to prevent
corrosion: this is a most important point, for where the free action
of the levers and shaft is not perfect, accidents may occur, which
due attention to their fittings will alone prevent. In order that
the surfaces of the valves may be changed occasionally, the covers
are fitted with hollow guides for the ends of the spindles,—that is,
when the weights are contained in the valve chests; the chests are
removed, when the spindle can be gripped and the weights and
valves turned slightly round. When the weights are placed inside
of the boiler, the valve-casing covers can be removed, and the
valves turned with a key or spanner, by means of a projecting
square piece cast on the top of each valve. Many arrangements
do not allow of this being done, for instance, when the lifting arms
work in slotted connections, as is sometimes the case when the
weights are inside of the boiler; but all lifting arms should be
forked, lifting the valves and weight by working on a collar formed
on the weight spindle. For inside-weighted valves the spindle must
be guided at the bottom through brass bushes on the spindle and
guiding piece fitted to the boiler. (See page 462.)
The steam stop valve is simply a spindle one, generally lying on
its side, fitted with a brass seating, placed in a cast-iron valve chest,
having a branch cast on above the valve for the pipe connections.
Where two valves are used, one of these branches has a plain flange,
and the branch on the other valve chest is fitted with an expansion
joint. On the top of the valve is cast a part for taking the head of
MARINE ENGINES.
457
the lifting spindle, in which it can freely revolve; the spindle passes
through a stuffing box on the casing cover, with a gland for pressing
down the packing; between the valve and the bottom part of the
stuffing box a screwed part is turned on the spindle, working in a
brass nut let into the bottom part of the stuffing box. A handle
is fitted to the spindle, and when it can be conveniently reached is
quite close to the gland; but when the valve box is placed beyond
reach of the attendant, the spindle is prolonged by a wrought-iron
connecting piece, fitted with a socket for taking the brass valve
spindle, and a wrought-iron bracket is fitted to the casing cover.
The valve chest in those instances is placed vertically and inverted,
C
E
Fig. 343.-Stop Valve.
F
so as to be worked from the
boiler-room floor plates, which
is decidedly the most convenient
position for turning round the
handle for opening and shutting
the valve. A small branch is
generally cast on one of the stop-
valve chests between the boiler
and the valve, for fitting the small
stop valve in connection with the
auxiliary steam pump, by this
means saving an extra hole in
the boiler plates. Of course the
position of the steam pump must
be fixed in the engine room, and
the branch cast on the stop valve
nearest to it, thus effecting a

A, Valve. B, Chest. C, Cover. D, Screwed spindle. saving in piping, which would
E, Handle. F, Stuffing box and gland.
not be the case if, for instance,
the steam pump was arranged on the starboard, while the small
stop valve was fitted to the larboard main stop valve, as the case
may be. The stop valve for the auxiliary steam pump should in
no instance be fitted to the steam pipes, but connected directly to
the steam space in the boiler, so that it can be wrought inde-
pendently even although the main stop valve is closed.
The branch steam pipe between the stop valves and the engine
must be arranged to suit the number of boilers; where two boilers
are used, the main pipe branch should be larger than the branches
from the boilers. These branch pieces are fitted with expansion
458
MODERN STEAM PRACTICE.
stuffing boxes and glands, to suit the direction of the expansion
and contraction of the copper pipes. In all bends care must be
taken to fit a collar on the end of the pipe, the gland and bottom

B
C
A
Fig. 344.-Branch Steam Pipe.
A, Branch pipe. B, Stuffing box and gland.
C, Loose bush.
bush being first placed on the pipe; this precaution is necessary,
as bends under pressure have a tendency to assume a straight line,
and fatal accidents have occurred from the steam by its reactive
force blowing out the bend and filling the engine room direct
from the boiler.
Clothing the steam pipes.—In order to prevent condensation
taking place in the passage of the steam to the cylinder, all the
steam pipes should be carefully clothed with felt, secured with fine
wire wound round the pipe, and covered over all with canvas sewn
tightly on, which should receive two or three coats of paint. In
some instances the pipes are lagged with wood, and secured with
neat brass hoops.
Separator.-Some makers fit a moisture separator to the steam
pipes. This appliance acts by abruptly changing the flow of
the steam, and is similar to those used for land engines, which
have been explained in a former part of this Work. By this means
much of the moisture is got rid of, trickling down the baffle plate
to the bottom of the separator, and then run off by a valve into the
bilges, or used for washing and cooking purposes.
Covering the boilers.-To prevent radiation, and consequently
waste of fuel, the boilers are lagged in all available parts. This
form of lagging consists in fastening square pieces of wood at the
corners and at intermediate distances on the boiler, the wood being
fastened by small stud bolts and nuts; felt is then laid in between
MARINE ENGINES.
459
the wooden battens, flush with the top of the wood, and the lagging
or strips of wood, which are grooved and feathered, is then laid on,
and securely fastened to the battens with screw nails. The wood
is then painted all over, and on the top of the boiler and round the
top corners thin sheet lead is laid, which thoroughly protects the
top of the boiler plates from the moisture that lodges on the
lagging, and would run between the joints were the lead not form-
ing an effectual waterproof covering. This covering also keeps the
boiler room comparatively cool. In many examples, however, with
dry uptakes, as fitted to high-pressure boilers, lagging cannot be
used, because it would ignite and smoulder away; in these cases
the boiler room is kept cool by air spaces formed with thin plates
placed in front of the uptakes, by which a current of air is continu-
ally flowing up between the uptakes and the plates, and prevents
in a great measure the radiation of heat affecting the attendants.
Check valve.—The valves fitted to the boiler at the end of the
feed pipes, termed the check valves, are spindle valves, contained in


Mill
B
C
E
A
Fig. 345.-Check Valve.
A, Valve. B, Chest. C, Cover. D, Set
screw.
Fig. 346.-Check Valve and Plug Valve, &c.
A, Plug valve. B, Chest. c, Screwed cover.
D, Check
valve. E, Handle.
brass valve boxes; the seating is turned in the box, and the valve
ground in, having a separate screwed hand spindle passing through
a stuffing box on the cover. By this means, when no water is re-
quired in the boiler, the spindle is screwed down hard on the top
of the valve, the water passing through the pumps, escaping by
the relief valve into the hot well. This valve on the boiler also
460
MODERN STEAM PRACTICE.
།
acts as a non-return valve, easing as it were the pipes at each return
stroke of the pump, and in the event of any of the feed pipes giving
way the valve of course instantly shuts with the steam pressure,
and thus prevents an escape of hot water and steam into the boiler
room: in this respect it may be termed the non-return safety valve.
In some examples a plug valve has been fitted in connection with
the non-return valve box. This is a refinement, however, which
has not come into general use; ground plug valves are at the best
very imperfect, and give a great deal of trouble to keep them in
thorough working order. It will be seen in Fig. 346 that there is a
handle secured to the plug at the bottom, which is hollow; and the
non-return valve is fitted to the top of the plug, and guided by a
spindle passing upwards through a hollow tube bored in the cover.
The gauge glass for indicating the height of water in the boiler is
fitted to brass connecting pieces having a screwed packing gland, with
plug tap at the top, and two taps in the bottom connection, screwed
into a separate pipe, on which bosses are cast for that purpose;
there are also three separate test taps fitted to the side of the pipe;
these are required, as the gauge, although protected with a shield,
sometimes breaks, in which case its plug taps are shut, and the
attendant ascertains by opening the side taps if there is a sufficient
quantity of water in the boiler. These taps have funnels and small
pipes for blowing the water down into the bilge. The taps on the
glass gauge should be so arranged on the branch screwed into the
large pipe, that when they are shut a nut on the top of the con-
nection can be unscrewed, and a new glass fitted without disturbing
the joints. Plugs have sometimes been fitted in the connection in
a line with the glass gauge, but such an arrangement is not quite
convenient when a tube requires refitting; for, in the former plan
the nut at the top being unscrewed the glass tube is put in vertically,
whereas in the latter the nut requires to be edged in, and conse-
quently does not fit so nicely; and the only saving effected is the
small test tap placed at the bottom, although some makers fit two
taps at the bottom, one over the other—an arrangement not at all
required. It is preferable to cast the pipe which carries the gauge
glass and test taps in brass, or a copper pipe may be used, with
bosses brazed on for screwing the connection to. As the small
taps are liable to get choked with deposit, they should be always
so arranged with a nut on the connection which can be unscrewed,
and a small rod pushed through to clear away the deposit.
MARINE ENGINES.
461
Scum taps are fitted in connection with an internal pipe, for
collecting the froth or scum at about the level of the water in the
boiler, and a copper pipe is connected to the tap for blowing the
dirty water overboard. The usual blow-off cock is fitted to the
bottom of the boiler, with pipe connection and expansion joints on
the blow-off Kingston valves, which is fitted to a strong cast-iron
pipe at the bottom of the vessel.
Vacuum valve.—In the event of the steam in the boiler falling
below the atmospheric pressure—or a partial vacuum being formed—
a reverse valve is fitted to the
boiler. It is of the spindle kind,
nicely ground into its seat formed
in the brass valve box.
steam acts on the top of the valve,
while the bottom is open to the

The
A

B
E
Fig. 347.-Vacuum Valve.
A, Valve. B, Chest.
D, Boiler.
c, Screw cover.
Fig. 348.-Whistle,
A, Bell. B, Bottom piece. c c, Annular space.
D, Plug tap. E, Handle.
atmosphere; thus when a partial vacuum is formed in the boiler
the atmospheric pressure lifts the valve, and the vacuum is at once
destroyed, consequently the flat sides of the boiler have no tendency
to collapse.
Steam whistles should be fitted to all vessels, for use in foggy
weather. They are generally placed on the bridge, with a pipe
connection to the boiler; and are formed exactly like the steam
whistle for the locomotive engine. The depth of the bell varies to
suit the note desired; but a deep bell, producing a full note similar
to the guard's alarm on the railway engine, is desirable for ocean
steam ships.
462
MODERN STEAM PRACTICE.
The following is an extract from a Report on Safety Valves,
drawn up by a committee of the Institution of Engineers and Ship-
builders in Scotland,' which presents the various features of the
question of area and method of loading in a succinct form:-
'SAFETY VALVE OPENINGS.-Since an orifice, with a square-
edged entrance, reduces the flow from 12 to 14 per cent., this allow-
ance will require to be made in computing the requisite area, and
opening of a safety valve, which cannot be considered as presenting
a much better entrance to the steam than a square-edged orifice.
In making this 14 per cent. allowance the weight in pounds of steam
discharged per minute per square inch of opening, with square-
edged entrance, corresponds very nearly with three-fourths of the
absolute pressure in the boiler as long as that pressure is not less
than 25 37 lbs. Examples of this are shown in the following table:-

Absolute Pressure
in lbs. per Square
Inch.
PI
Weight Discharged per
Square Inch of
Orifice, with Rounded
Entrance, per Minute.
Weight Discharged per
Minute with
Square-edged Orifice.
Ws.
Three-fourths
of Absolute Pres-
sure.
Wr.
3/4 P1.
25°37
22.81
19.6
19
30
26.84
23
22'5
40
35'48
30'5
30
45
39'78
34°2
33.8
50
44'06
37'9
37'5
60
52.59
45'2
45
70
61.07
52.5
52'5
75
65°30
56.1
56.2
90
77.94
67
67.5
100
86°34
74'3
75
The area of opening, requisite to the discharge of any given con-
stant weight of steam, it will be observed, is very nearly in the
inverse ratio of the pressure. Thus, while 3 square inches of open-
ing, with square-edged entrance, will discharge 3 × 23=69 lbs.
weight of 30 lbs. pressure steam per minute, one square inch of
opening will discharge 67 lbs. per minute of 90 lbs. pressure steam.
The quantity of heat, however, requisite to generate (from water
at 100°) 67 lbs. weight of steam, at 90 lbs. pressure, is only I per
cent. less than is required to evaporate 69 lbs. at 30 lbs. pressure.
The boiler which will generate 69 lbs. of steam per minute at
30 lbs. cannot, therefore, possibly generate more than 677 lbs. at a
pressure of 90 lbs. ; but many experiments on record seem to indicate
that the deficiency at the higher pressure is more than ten per cent.
¹ See Trans. of that Institution, vol. xviii.
MARINE ENGINES.
463
In ordinary marine practice there is not often more than 20 lbs.
of coal consumed per hour per square foot of fire grate, and the
water evaporated seldom exceeds 9 lbs. per lb. of coal, which corre-
sponds to 180 lbs. per hour, or an evaporation of 3 lbs. per minute
per square foot of fire grate. Under those conditions the area of
opening requisite to discharge all the steam a boiler can generate
corresponds to four times the square feet of fire grate, divided by
the absolute pressure; or, let a denote the area of orifice in square
inches, and the absolute pressure-
a=
4 × square feet of fire grate
P1
The Board of Trade allowance is half of one square inch area of
safety valve for each square foot of fire grate. Hence, the lift of
valve is proportional to the diameter, and inversely as the pressure.
For a discharge of 3 lbs. per minute per square foot of fire grate the
requisite lift in inches is twice the diameter of a (flat-faced) valve,
divided by the absolute pressure; this, however, does not apply to
pressures less than 25 lbs.
Take, for example, a valve 5 inches in diameter, 196 square
inches in area, which corresponds to 2x 19'6=39'2 square feet of
fire grate, which would evaporate 39′2 × 3=1176 lbs. of water per
minute. Then since the area a in square inches, requisite to dis-
charge any weight, w in lbs. of steam per minute at the pressure
Þ₁ is—
1
a= 4 w
3p
we would have, by taking the pressure p = 60, and the weight
w= 117·6, the area
a=4×117·6—2·61 square inches,
3 × 60
which corresponds to the opening of a flat-faced valve, 5 inches
diameter, when lifting 60
2x5 ='1667 inches.
The circumference of a 5-inch valve being 157 inches and
15'7 ×·1667 = 2·61 square inch、s of opening, as stated.
When the angle of seat of valve is 45°, the lift required in inches
is-
2.8 x diameter of valve
p1
When a boiler is regularly fired, and all the steam generated
discharged through an ordinary safety valve, under a succession of
464
MODERN STEAM PRACTICE.
different pressures, the lift of valve, multiplied by those absolute
pressures, should be a constant quantity, provided the same quantity
of heat is constantly entering the boiler, and provided also that the
absolute pressure in the boiler or pipe below the valve is not less
than 1.726 times the absolute pressure of the steam in the chamber
above the valve.
In actual experiment a deficiency is generally manifested at the
higher pressures. Hence the suspicion of some considerable loss of
heat at the higher temperatures.
It has been suggested that this might be accounted for by the
low-pressure steam carrying water along with it-retarding its
motion-and thereby requiring a larger opening; but this would
only aggravate the case, since the same opening will permit of a
much larger quantity of heat being discharged from the boiler with
wet than with dry steam. This phenomenon may be suggested as
one worthy of further investigation.
According to the Prussian law, as taken from Engineering of
December 6th, 1872, and allowing 30 square feet of heating surface
per square foot of fire grate, the area of safety valve is—
36 × square feet of fire grate.
P
A valve of this size, when full open, is capable of carrying away
nine times the quantity of steam generated at the pressure ₁, and
therefore will, at the designed pressure p₁, be able to discharge all
the steam by lifting 1-36th part of its diameter.
At absolute pressures of 72 lbs., the British and Prussian laws
prescribe precisely the same area of valve.
Take, for example, 20:36 square feet of fire grate, which requires
by British rule a valve 10'18 square inches in area, equal to 3.6
inches diameter, and which if flat-faced would, at a pressure of
72 lbs., require to lift 2x36 equal to 1-10th of an inch.
3.6
72
Then, by the Prussian rule the area of valve is, for 20:36 feet of
36 × 20*36
grate and 72 lbs. pressure: a=
= 10'18 square inches=
72
36 inches diameter; and the requisite lift is (diameter 36) as before
= 1-10th of an inch. The circumference of this valve being
36
11.31 inches, would (if flat-faced) by lifting 1-10th inch give a clear
opening of 1'131 square inch, which opening would, at 72 lbs. pres-
sure, discharge 34 × 72×1·131=61′07 lbs. of steam per minute, and
which corresponds to 3 lbs. per foot of fire grate-as, 20˚36 × 3=61*08.
MARINE ENGINES.
465
At absolute pressures of 36 lbs. the Prussian law prescribes double,
and at 144 lbs. only half the area of the British.
At all pressures above 1726 atmosphere, the area of valve when
full open, by Prussian rule, is nine times that requisite to discharge
all the steam generated, while by British rule it is 4½ times at 36 lbs.
pressure, and 18 times more than is required at 144 lbs. absolute
pressure; and this is after allowing for an evaporation of 3 lbs. of
water per minute per square foot of fire grate, which is considerably
more than is usually realized in marine practice.
Before the ordinary valves rise and give sufficient opening, the
pressure of steam frequently greatly exceeds the load under which
the valve begins to rise. Hence the requirement of large areas.
With a properly constructed valve, however, such as many now in
use, which rise one-fourth of their diameter by an increment of I to
3 lbs. above the load, there is no necessity for the area being much
(if any) more than 1-9th of that prescribed by the Prussian rule.
Say, area a= 4 × square ft. of grate plus the area of wings of valve. The
P1
valves here referred to are so very small that the stems, or wings,
occupy a considerable proportion of the area, and must in the above
equation be allowed for. Those small valves give much more
prompt relief to the boiler, and never permit the pressure to rise
much beyond the load.
"RESULT OF A SERIES OF EXPERIMENTS, made to ascertain
the increase of pressure in a boiler when all the steam raised was
allowed to pass away by the safety valves unassisted.-Two valves
were used, the united area of which was half an inch per foot of
grate surface. The boiler used was tubular, with 2 furnaces; the
grate surface was 25 square feet; the heating surface 746 square
feet. The valves were each 2% inches diameter, the fuel used was
ordinary good Glasgow dross, the firing good, and as nearly uniform
during all the experiments as possible. The valves were loaded by
direct weights. On next page we give table of results.
With flat-faced valves having, according to Board of Trade rule,
half of one square inch area per foot of fire grate, W = 3 PL
But the valve seats being to an angle of 45 degrees,
3 PL
2 D
W=28D=Weight of steam discharged per minute per square foot of fire grate.
P-Absolute pressure in lbs. per square inch.
D= Diameter of valve in inches.
L=Lift of valve in inches.
30
466
MODERN STEAM PRACTICE.

Load on Valve. Press, rose to
Incr. per cent. Lift of Valve.
W. Lbs.
5 lbs.
13 lbs.
160°
*325
3'39
10
""
19
90'
*255
3.223
""
15 ",
25
66.
•18
2.68
20
""
30
50°
'16
2.676
25,,
36
44*
'1425
2.7
30 19
40
33°
•1262
2:58
""
35,,
44
""
25'7
*1125
2.466
40"
482,,
21'
*103
2.437
45 "
52
""
15.5
*097
2'41
The guides of valve would reduce the clear opening by full one-
ninth, for which no allowance has in the above been made.
Table showing the respective area of valve for the boiler in
question, if made according to the committee's recommendation, as
compared with present practice in this country, and at the several
undernoted absolute pressures:-

Absolute
Pressure
of Steam.
Areas of Valve as
recommended by
Committee.
Areas of British
Valves.
20 lbs.
45'
square in.
12.5 square in.
25"
36.
12'5
""
30,
30'
12'5
""
35 ",
25'7
12'5
""
""
40 "
22.5
12'5
""
45",
20'
12'5
""
50,,
18.
12.5
55 ",
16.36
12'5
""
60
15'
12.5
""
65
13.84
12.5
""
70",
75,,
13'
12'5
""
12'
12'5
Safety valves of ordinary construction, if loaded by direct weight,
do not allow all the steam to escape which can be raised in the
boiler until the pressure has increased above that at which the
valve opens, and an additional increase of pressure will take place
when the valves are loaded by springs. That such has been the
case in the past by dead-weight loading and imperfectly propor-
tioned valves is fully illustrated by reference to the foregoing
experiments.
The object in appointing this committee was to investigate the
cause of this increase of pressure, especially with boilers propor-
tioned in strength to work at low pressures, and it is hoped that the
result of these investigations will clearly show that the great cause
MARINE ENGINES.
467
lay in using valves of too small dimensions; and that with valves.
proportioned as proposed, properly constructed and loaded by
springs, anything approaching a dangerous increase of pressure is
entirely avoided.
2 x diameter of valve
-
"ON LOADING SAFETY VALVES BY DIRECT SPRINGS. — It
has been shown that valves having half an inch of area per
square foot of grate surface require to lift
in
order perfectly to relieve the boiler; and if proportioned as is
recommended in this report, then the lift would be in all cases
diameter of valve.
36
P
Having determined the requisite lift, it remains to fix any reason-
able or desired per centage of the load, which is not to be exceeded
by the additional load due to the compression or extension of the
spring, caused by the lift of the valve. Let this, for example, be
restricted to 22 per cent. of the original load.
Then the spring loading the valve should be so proportioned that
the compression or extension, to produce the initial load, shall be
40 times the lift of the valve.
So that with valves having half an inch area per foot of grate
surface, the initial compression or extension of spring would be =
With valves as recommended, the initial com-
80 x diameter of valve
P
pression or extension would be I'II x diameter of valve. The
following formula refers to spiral springs, made of steel in the usual
way:-
E = Compression or extension of one coil in inches.
d = Diameter from centre to centre of steel composing spring in
inches.
w= Weight applied in pounds.
D= Diameter or side of square of steel of which the spring is
made in 16ths of an inch.
C = A constant which, from experiments made, may be taken
as 22 for round steel and 30 for square steel.
E=
d³ × w
X
D4 x C
•
The total compression or extension of such a spring is equal to
that of one coil into the number of effective coils, which may
be taken as two less than the apparent number, the end coils
468
MODERN STEAM PRACTICE.
being usually flattened to serve as bases for the spring to rest
upon.
The relation between the safe load, size of steel, and the diameter
of the coil has been deduced from the works of the late Professor
Rankine, and may be taken for practical purposes as follows:—
3
D=
wx d
for round steel.
3
3
D=
W x ď
4'29
for square steel.
The application of the above formulæ may be illustrated by the
following calculations of three different proportions of springs, all
designed to give the same result. Diameter of valve, 4″ 125 area
in square inches. Boiler pressure 60 lbs. per square inch. Omitting
weight of valve, spindle, and spring; load required=12.5 × 60=750
lbs. Then, assuming that this valve is in the proportion of half a
square inch area per foot of grate surface, the lift of valve would
be=2x4=106, say '1".
75
Initial compression of spring,
80 x 4 = 4" 26, say 4 inches.
4″26,
75
3
750 × 4
1st. Supposed diameter of spring, or d, equal 4 in. D=√7
= 10, diameter of spring steel 10-16ths. E =
=
Effective number of coils = 4 18′3, say 18.
*218
=
64 × 750
10000 × 22
3
218".
Pitch of spiral,
allowing between each coil a distance equal to twice the intended.
compression I"061, say I inch; effective length of spring
= 18 x 1 = 18″, and allowing for two end coils as bases, say 19½",=
the length of spring before compression.
2d. Supposed diameter of spring, 6 in. D =
say 12-16ths. E
216 × 750
20736 × 22
3
750 × 6
3
= 11'447,
*355". Effective number of coils
required, = 11'2, say II. Pitch of spiral, 1'46"; effective length
4
*355
II
of spring, 146 × 11 = 16′06″, and allowing for two end abutment
coils, say 17½" = the length of spring before compression.
3
3d. Supposed diameter of spring 12 in. D = 750
say 14-16ths. E 1728 × 750
required,
4
1.53
=
38416 × 22
✓750 x 12 = 14'42,
3
1533". Effective number of coils
2·61. Pitch of spiral, 3'9"; effective length of spring,
MARINE ENGINES.
469
3'9 x 261 = 10*17", say 10", and allowing for two end abutment coils,
say 1134″ = the length of spring before compression.
In cases where it is desirable or perhaps necessary to employ
springs acting at the ends of levers, the same formulæ can be em-
ployed for determining the proportion of springs, bearing in mind.
that the lift of the end of the lever where the spring is attached, is
to be taken instead of the simple lift of valve.
The above illustrative calculations have all reference to springs
made of round steel, and used in compression. In many cases two
or more springs, one within the other, may be used with advantage.
After consideration of the whole of the experimental information
obtained, and the necessities required in practice, the committee
have come to the following conclusions:-
Ist. The present practice in this country of constructing safety
valves of uniform size for all pressures is incorrect.
2d. The valves should be flat-faced, and the breadth of face need
not exceed one-twelfth of an inch.
3d. The present system of loading valves on marine boilers by
direct weight is faulty, and ill adapted for sea-going vessels, a con-
siderable quantity of steam being lost during heavy weather, in
consequence of the reduced effect of direct load-the result of the
angle or list of the vessel, and also of the inertia of the weight
itself, the latter not being self-accommodating at once to the down-
ward movements of the vessel, and, moreover, the impossibility of
keeping the valves when so loaded in good working order.
4th. That two safety valves be fitted to each marine boiler, one
of which should be an easing valve.
5th. The dimensions of each of these valves, if of the ordinary
construction, should be calculated by the following rule:-
A =
18 x G
or A =
0.6 × HS
Р
P
A = Area of valve in square inches.
G = Grate surface in square feet.
HS
Heating surface in square feet.
P = Absolute pressure in lbs. per square inch.
6th. The committee suggest that only one of the valves may be
of the ordinary kind, and proportioned as above, and that it should
be the easing valve. The other may be so constructed as to lift
one quarter of its diameter without increase of pressure. Valves
of this kind are now in use, and one such valve, if calculated by
470
MODERN STEAM PRACTICE.
the following rule, would be of itself sufficient to relieve the
boilers:
A=4XG
+ area of guides of valve,
Or A =
*133 × HS
P
+ area of guides of valves.
This valve should be loaded, say I lb. per square inch, less than
D
O
E
to funnel
waste pipe
A
F
E
r
Figs. 342A, 342B.---A, Safety valve.
B, Spring.
to silent
blow off
CC, Studs
with screwed ends. D, Cap. EE, Chest leading to waste
pipe and nozzle at the side of ship. F, Hand lever for lift-
ing valve.
Ah
the easing valve.
7th. As experience in
the use of valves of this
description is
is acquired,
both may be of this kind,
and one of them made to
blow into the sea without
any increase of pressure,
as is illustrated by the dia-
grams (Figs. 342A—342C)
from actual practice; the
other to be the easing
valve, and loaded 1 lb. per
square inch in excess of
the working valve.
8th. If the heating sur-
face exceeds 30 feet per
foot of grate surface, the size of safety
valve is to be determined by the heating
surface.
9th. As boilers decay from age it is
necessary gradually to reduce the pressure
of steam, and the committee recommend
that valves should be made of a size to suit
Fig. 342C-Section of Silent Blow- the pressure to which the boiler may ulti-


off Nozzle on Ship's side.
Pipe from safety valve.
Nozzle. c, Nozzle chest.
Ship's side.
A,
B,
D,
mately be worked when it becomes old.
10th. Springs should be adopted for
loading safety valves, and they should be
direct-acting where practicable.
When levers are used, the friction of the joints will cause an
extra resistance, and consequent increase of pressure, when the
valve is rising, and a loss of steam through diminution of pressure
before it will close."
MARINE ENGINES.
471
譬
​THE SCREW PROPELLER.
This mode of propulsion is now universally adopted in ocean-
going vessels. For war vessels the screw propeller recommends
itself because it and its machinery can be placed below the water
line, and thus be protected in a great measure from the effect of
shot; while for merchant vessels the advantages over the paddle-
wheel arrangement consist in a saving in bulk and weight of
the engines and boilers, by which the ship is enabled to carry
more cargo, and greater coal stowage is allowed in cases of long
voyages.
SHAFTING FOR THE SCREW PROPELLER.
A
BB
D
E
Fig. 349.-Coupling for Shafts.
A, Shaft.
B B, Disc coupling. CC, Bolt holes.
D, Projection recessed in. E, Key.
The arrangements in the passage from the engine to the after
part of the ship, technically
termed the "screw alley," first
calls for notice. The line of
shafting which connects the en-
gine or cranked shaft with the
propeller shaft is similar to any
other line of shafting for general
purposes. The most approved
form of coupling is the solid disc
forged along with each separate
shaft, with a projection left on the one, which fits into a recessed
hole turned out in the other. By this means the whole line of
shafting is kept central the one with the other, and the discs are
bolted together with bolts accurately turned and driven tightly into
the holes, the holes being bored and rimelled out, and the discs
faced for the heads and nuts to bear against. A key is fitted into
the two discs, secured by screws into the one, but only fitting
somewhat tightly into the other; by this means the shearing strain
is taken off the bolts. Some engineers dispense with the key and
projecting piece, having the ends turned quite fair, and depend
on a greater sectional area of bolts for holding the discs together
and taking the twisting strain. The part of each shaft which rests
on the pillow block should be raised a little above the main part,
and must be turned quite truly; at the same time in some cases it

472
MODERN STEAM PRACTICE.
is advisable to turn the shaft from end to end with a rough cut, to
insure a fair and true line, which tends to make the machinery run
A
OBO
Ꭰ
E
O O O
Fig. 350.-Repairing Coupling.
A, Coupling. B, Bolt holes. cc, Keys. D, Shaft.
E, Recess for taking coupling on shaft.
more smoothly; but when the
shafting is truly forged this is
not required.
Repairing couplings.—The
lying shafting is generally
fitted rough from the steam
hammer. In the event of one
of these shafts breaking, a
ready means for temporarily
repairing it is of the highest

importance. In the example (Fig. 350), the coupling is made in
four pieces, bolted together lengthways with flanges, and trans-
versely with bolts passing through discs cast on the coupling, the
torsional strain being taken on four keys.
D
D


E
B
   ¡
A
A
Fig. 351.-Repairing Coupling in Cast Steel or Wrought Iron.


F
H
A, Screw shaft.
Figs. 352, 353.—Repairing Couplings in Cast Iron.
B. Coupling. cc, Bolts. D, Set screws. E, Recessed nut.
H, Raised strips.
G G, Set screws.
F, Keys.
We have arranged a simpler form of coupling, which possesses
the following advantages. It is evident that a shaft breaking at
sea must be repaired as speedily as possible, and that the contact
between the rough shaft and the coupling must only be partial,
MARINE ENGINES.
473
otherwise it would be impossible for the best mechanic to adjust
the one to the other in a limited time. The points of contact are
taken on raised strips, cast or forged on as the case may be, forming
a v section, with flat parts cut across the shaft, and the fracture is
drawn together by means of the longitudinal flanges and bolts.
There are four series of strips in the length of the coupling, making
sixteen points of contact in all. These couplings can be fitted with
keys for taking the shearing strain; but it is evident that cutting
and filing up key beds on the shaft in a heavy seaway would be a
work of difficulty, and therefore in emergencies the necessary amount
of grip can be obtained with a series of cupped set screws and nuts
recessed in the coupling, considering that the coupling of the V sec-
tion takes the greater part of the torsional strain. To lighten these
couplings so that they can be easily adjusted, we propose making
them of cast steel. Wrought iron or even cast iron can be used,
but the latter will be of considerable weight; and perhaps the more
expensive material may not be considered too much, when we
remember that the light coupling is more easily handled on board
ship.
The pillow blocks are of cast iron, lined with white metal; they
are quite plain, and are fitted with a cover, parting at the centre
line. Oil cups are cast on the top of the covers, fitted with pipes,
syphon wicks, and light cover. The base of the block is quite


D
11
D
B
B
C
#
A
1
B
A, Pillow Block.
Fig. 354.-Pillow Block for Shafting.
B, Cover for do. cc, Bolts and nuts.
D, Oil cup.
flat, and is generally bolted down to wooden beams placed on the
top of wrought-iron standards, which are carried up from and
strongly rivetted to the floor plates. The pillow block for receiving
the thrust or forward motion of the line of shafting imparted by the
action of the screw propeller-this push being always in the direc-
tion of the path of the vessel, whether moving ahead or astern—
474
MODERN STEAM PRACTICE.
with oil cup cast on, and pieces left to form the pipes for the syphon
wicks, having holes bored through the top brasses for each collar
on the shaft. The block is cast with a long bottom piece, which is
bolted down to a separate plate planed for its reception, and fitted
with joggles for firmly wedging the block and plate together, the
latter being securely joggled and bolted to the wrought-iron stan-
C
must be fitted with a series of collars in the bushes for taking a
corresponding series turned on one of the lying shafts, generally
located near the engine end, although they are sometimes fitted at
both ends of the shafting. These bushes are fitted into the pillow
blocks in the usual manner, and are secured with a cover and bolts,

Fig. 355.-Thrust Block.
A, Thrust block.
B, Cover for thrust block.
C,
Oil cup.
MARINE ENGINES.
475
dard frames rivetted to the top of the floor plates. In connection
with the pillow blocks, a water pipe is carried along the entire
length of the screw alley, supplied from the same source as for the
main bearings of the engine, and fitted with a plug tap for each
bearing, with flexible pipe and water distributor for
showering the water by hand all over the bearing in
the event of heating.

The stern tube is made
of cast iron, and of suffi-
cient length to suit the
fineness of the run of the
vessel. A flange is cast on
for bolting it to the plate
laid across the ship from
frame to frame, by which
C
A
B
J
Fig. 356.-Stern Tube, forward end.
D
A, Stern tube. B, Flange. C, Stuffing box and gland.
D, Shaft.

D
B
B
A
Fig. 357.-Stern Tube, aft end.
A, Stern tube. B, Snugs. c, Stern post. D, Tube with lignum vitæ. E, Brass bush on shaft.
the tube is firmly pressed into the tapered part of the stern post, a
corresponding taper being accurately turned on its own end. A
packing space is left, fitted with a gland cast in brass or of cast iron
lined with brass, for packing the shaft and rendering it perfectly
water tight; care must be taken that ample room is left between
the gland and the skin of the ship. The tube has rings cast on
and turned; these rings are placed to suit the frames of the ship,
which have plates accurately bored out, and in this way the tube is
supported along its entire length. At the extreme end of the tube
a brass bearing is let in, having strips of lignum vitæ for the bearing
surface. This was found an immense improvement over the ordin-
476
MODERN STEAM PRACTICE.
for ships to remain long on any station without incurring constant
expense in docking them to repair the bushes, as was required in
the old method, where the action of the screw soon played sad havoc
with the brass bushes, wearing them by repeated blows out of truth,
and consequently shaking the after part of the ship.
A
Fig. 358. Method of securing the Stern Tube, &c.
A, Stern tube.
B, Nut.
c, Stern post.
D, Tube with lignum vitæ.
H.
End View at Stern Post.
C.
Fig. 359.-Stern Tube, &c.
E, Stern post.
G, Water pipe.
— A B, Across the shaft at the stuffing box.
F, Tube with lignum vitæ.
L
A-
}
tioryat A B.,
CD, Across the shaft at the securing bolts.
н, Shaft with covering tube of brass.
ary brass bushes, and has been a chief cause of the great success
of the screw mode of propulsion. Without this wooden bearing
surface solely lubricated by the sea water, it would be impossible




MARINE ENGINES.
477
Figs. 357 and 358 show methods of securing the stern tube to the
stern post. In some examples where the stern tube is turned tapered
at the end, fitting into a corresponding hole bored out in the stern
post, as will be seen by Fig. 359, the tube is held in position by three
large bolts, with distance pieces of cast iron placed between the
floor plates of the ship, which are strengthened with extra plates at
the front end and at the middle of the tube, and bored out for the
reception of the raised parts on the tube, also truly turned. The tube
is fitted with the usual brass bush, lined with lignum vitæ, and is
bolted by a flange and stud bolts to the stern post. The fore end has
a cast-iron gland bushed with brass, with a brass bush at the bottom
of the stuffing box, which prevents the water entering the ship.
The screw shaft should be made of larger diameter than the lying
shafting, and is fitted with a disc for connecting it to the latter, and
also with a thrust block, by which the longitudinal pressure from the
action of the screw is partly taken, relieving in a measure the for-
ward one. Raised parts are left on the shaft at both ends, for
shrinking on brass tubes for the end bearing, which should be of
great length. At the end of the shaft a tapered part is turned, with
a collar near the front extremity, and screwed with a bold square
thread at the extreme end, which is fitted with a nut and washer for
pressing the screw propeller up against the collar. Sometimes the
end of the tube is fitted with a packing ring, to prevent the water
acting on the end where it is let into the stern tube.
In the navy and also in some mercantile vessels hollow propeller
steel shafts are used. The outside diameter is usually about double
of the inside diameter, and the steel is that known as Whitworth's
fluid compressed steel, i.e. the casting is made with a core, and
compressed by hydraulic pressure of from 5 to 6 tons per sq. inch,
and thereafter drawn out by hammering to the required length.
CONSTRUCTION AND FORMS OF THE PROPELLER.
Before discussing the action of the screw propeller, we will con-
sider its form and construction. The boss or centre piece, as in an
ordinary screwed bolt, may be said to form the bottom of the
thread, and the blade forms the thread itself. The thread of a
screw can be illustrated by rolling a piece of paper cut in the form
of a right-angled triangle round a cylindrical piece of wood: the
base is the circumference, the perpendicular is the pitch, and the
478
MODERN STEAM PRACTICE.
hypothenuse is the line that will delineate the thread when wound
round the wood. Thus a point on the thread, when working in a
nut with a corresponding thread, will move forward the extent of
the pitch in a single revolution. In this way the screw propeller
may be termed an endless screw, working into an endless nut-the
ocean. Thus supposing the pitch of the screw is 20 feet, and the
distance the vessel has to go forward 4000 feet, the screw propeller
would require to make 200 revolutions to move the vessel that
distance. The action of a cork-screw is similar to the action of
the screw propeller: with each revolution of the screw a certain
progressive movement is made through the cork, due of course to
the pitch or spiral of the screw; but as the screw propeller moves
in a yielding fluid, sometimes the action ceases by the thread of
the watery nut becoming as it were broken for a time, and the
propeller revolves without imparting any forward motion to the
vessel. This is termed the "slip" of the screw, and varies from
about 10 to 20 per cent. Again we have what is termed "negative
slip," the screw moving through less space (even although working
as in a solid nut) than the speed of the vessel, the vessel as it were
outstripping the screw and dragging it through the water. This
negative slip occurs only in vessels having full after lines; in those
having a clean run aft it is never felt. The question of the best
pitch for the screw propeller depends on the lines to be given to
the ship, and shows the necessity for the builder and the engineer
working hand in hand. When a maker of marine engines contracts
for the machinery of a vessel built by another firm, he should
always be provided with the full lines of the ship, so as to meet the
requirements of the particular case. Some screw propellers are
made to feather, by which means the best pitch for propelling the
vessel cheaply is arrived at; but it is not advisable to carry this
practice too far, for then the blade of the screw presents neither
more nor less than the action of an oblique board. And although
we may be able to get a little more speed out of the vessel by this
deviation from a truly scientifically constructed propeller to suit
the known run of the vessel as found, surely it is preferable to
arrive in the first instance at the pitch to be adopted, which can
only be successfully found by studying the lines of the ship, and
comparing them with former practice. And when we do get a
good result from the best form of vessel yet constructed, it can be
used as the basis for further improvements, increasing the speed of
MARINE ENGINES.
479
the ship if desired, bearing in mind that the power required varies
as the cube of the speed. The question of relation between power
and speed has received recently much attention through progressive
speed trials carried out by Mr. William Denny of Dumbarton, who,
as to the usual formulæ or rules, says:—“The common fault is the
supposition that the power required to produce certain speeds varies
as the cubes of these speeds. This is a very fallacious theory, and
one which experience does not bear out." See page 513 for an in-
vestigation of this question.
In the moulding shop a nearly uniform plan of constructing the
moulds is adopted for all the forms of screw propeller. In the
early screws the boss was round, tapering from the front to the back
to suit the taper turned on the screw shaft, the thickness of the
boss being greater at the front, with a reduced thickness at the end
of the shaft. The blades are formed or struck up by means of a
board, revolving round a central spindle, placed vertically in the
centre of the mould for the boss. An inclined plane is formed of
wrought-iron plating to suit the pitch required, and this plate is
bent round to the true circumference of the outer diameter of the
blades; in this way the mould is formed of loam by moving round
the board on the edge of the wrought-iron plating, care being taken
that the board always moves upwards on the spindle in a level
manner; the bottom edge of the board then scrapes the loam, which
is built up on a large cast-iron plate, and the true flat form of the
screw's disc is described. It is then necessary to divide the outer
circumference of the blades, which is generally one-sixth of the
total circumference, or the radius of the blade from the centre to
the point, the sides or edges of the blade radiating from those
points on the circumference to the centre. The thickness of the
blades at the point and root is then laid on, the corners of the blade
at the circumferential line are rounded off, and the mould finally
finished for casting. With this form of screw propeller, a great
portion of the central part of the blades strikes the water nearly
flat, merely disturbing the water, and throwing it off at right angles
to the path of the vessel, causing much vibration without producing
any useful effect.
It was also found that the greatest effect was
produced by cutting down the blades at the circumferential line, and
forming the edges curved, having the greatest breadth nearer the
centre, instead of on the extreme circumferential line of configuration.
This effect of vibration in the earlier screws was got rid of in a
480
MODERN STEAM PRACTICE.
measure by making the boss spherical, and filling up a great por-
tion of the central part of the blades with the ball, from which the
water glides off, while the blades cut their passage through the
1
B
generally adopted.
A, Boss. B, Blade. c, Blade
showing thickness of metal.
water in a more direct line, instead of striking
it at right angles to the vessel's path. This
is the greatest improvement that has as yet
been introduced in the formation of the screw
propeller, and it is now universally adopted,
in some cases with slight but non-essential
variations.
Great difference of opinion exists as re-
gards the number and configuration of the
blades for the screw propeller. When the
vessel is pitching or rather plunging in a
heavy sea, a two-bladed screw cannot have
Fig. 360.—Form of Blade very SO much hold of the water as one with three
or more blades; but the two-bladed screw
possesses a great advantage in being more
easily lifted for repair or inspection; and in
addition the “well," as it is termed, that is cut down from the deck
does not require to be so large. For war vessels so fitted, two-
bladed screws are adopted; but for the mercantile marine three
and even six blades are beneficially used.
The common propeller is arranged for two, three, or four blades;
TE
X X



A, Boss.
Fig. 361.-Common Screw Propeller.
B, Blade.
c, Blade showing thickness of metal.
they are generally cast along with the boss, of an elongated or
spherical shape. The side view of the blade is quite parallel and
more or less rounded at the point, and the thickness gradually
tapers from the centre to the point. Some of the common forms
=
MARINE ENGINES.
481
are made to feather, and are arranged for four blades, having a
flange on each blade, which is turned, fitting into recesses cast and
turned out in the boss, the end of the blade having a projection
cast on, and turned to fit holes in the boss bored out exactly. The
blades are bolted to the boss with a number of bolts all round the
flange, fitted with elongated holes

in the blades. The hole for re-
ceiving the propeller shaft is
turned of a tapered form, and
the propeller is screwed hard into
its place with a large nut at the
end, having a recessed key on
the shaft to prevent the propeller
turning round. Some engineers
have fitted keys through the boss
for this purpose, but these are
not required, as practice has
proved that with a proper taper
on the shaft the nut is powerful
enough to hold the screw firmly
in position, the grip being quite
sufficient to resist the torsional
stress imparted from the blades
turning round in the water.
In some arrangements for
twin-screw propulsion, two pro-
pellers have been fitted to each
shaft, one before and another be-
OTTA


8
Blade.
B
hind the hanging outside bear- Fig. 362.-Feathering Propeller with four Blades.
ings, by which plan more pro-
A, Boss.
B
pelling surface is obtained for vessels of light draught. The forward
screw having a finer pitch than the after one, the water given off or
pushed back by the one is taken up by the other. This plan is correct
in theory, whether applied to the screw or paddle wheel. It is more
evident in the latter case, where the tail water given off by the forward
paddle wheel acquires a certain velocity; and when two wheels have
been fitted to each side, the after one must have a larger diameter,
or be driven at greater velocity, so as to pick up the tail water
beneficially. To carry out this principle more fully in the screw
propeller, two blades have been cast on the same boss, one in
31
482
MODERN STEAM PRACTICE.
advance of the other, or, in other words, a two-bladed screw is
formed in duplicate. It is advisable to cut away the sides from the

-B

B
B
B
B
B


Fig. 363.-Two Propellers cast on one Boss.
A, Boss. B, Double blades.
middle of the blades to the centre (as seen in Fig. 363), by which
means the water is not churned so much, while the after blade gets


-A
Fig. 364.-Six-bladed Feathering Propeller.
A, Boss. B, Blade.
c, Blade showing thickness of metal.
a better grip. In other forms six blades have been successfully
adopted. The blades are narrow and almost parallel in the front
MARINE ENGINES.
483
view; in the end view they are bent backwards. This form pre-
sents a number of blades of small area, and it gives equal satisfac-
tion in other arrangements with two or more blades of greater
surface in each; but it is obvious that it is not nearly so strong as
the ordinary mode of construction, and therefore more liable to get
damaged.

We now notice a form of pro-
peller which has been exten-
sively used both in the royal
navy and the mercantile marine.
The boss is of a ball shape,
and may be considered damage
proof; the blades have a curved
shape on the sides, and their
greatest breadth is at the centre
B
B
·B··

A

E
Fig. 365.-Boss for a Six-bladed Feathering
Propeller.
B, Blade. c, Key.
pieces. E E, Plates.
A, Boss.
D, Wedge
Fig. 366.-Four-bladed Propeller cast on
the Boss.
A, Boss.
B, Blade. c, Taper on shaft.
D, Nut with split pin.
or nearly so; the points and that portion cast on the boss are
made narrow; they are bent forward at the points, by which
a better grip of the water is obtained. This form of propeller
has generally either three or four blades, all cast along with the
boss. The success which has attended it has produced various
484
MODERN STEAM PRACTICE.
modifications in the form of the blade, by which its general appear-
ance has been altered, but its usefulness in no way improved. With
the view of arriving at the best pitch for propelling the vessel, the
designer of this form generally prefers the blades cast separate
from the boss, and all keyed to it by a key passing through a shank
accurately turned to fit a corresponding hole in the boss; the flange
has also elongated holes all round through which bolts pass; by
this means a greater or less pitch is given to the blades, the number
of which is generally two, although three can also be conveniently


F
E
B...


·B...
C
#
D


D
A
ம
B
Fig. 367.—Feathering Propellers.
A, Boss. B, Blades.
Fig. 368.-Boss for Feathering Propeller.
A, Boss. B, Taper on shaft. c, Nut and split pin.
D, Key. E, Wedge pieces. F, Plate. G, Plate
fitted to hole for putting in the key.
adopted. All these screws are either fitted with a large nut for
firmly screwing or forcing them in the tapered part left on the
propeller shaft; or are held in position by flat side keys, a part
being cut in the shaft for their reception. The keys are driven
tightly in, bearing laterally and longitudinally against the boss and
the shaft, and are held in position by a nut and lock nut bearing
MARINE ENGINES.
485
on a suitable washer, the whole being inclosed within the hollow
boss properly strengthened in the casting.
The mode of attaching the blades to the boss is by a cotter
passing through the shank and boss, and held in position by nuts
and lock nuts at each end, bearing on washers, the hole being cut
of a wedge form, tapering to the centre of the cotter. By this
means the blade can be turned in either direction for feathering, or
for adjusting the pitch; and when the pitch is once fairly adjusted,

18

E
D
E
D
D
C.
B

A
Fig. 369. Bolt Fastenings.
F
O
Fig. 370.-Bolt Fastenings.
A, Boss.
B, Blade. c, Bolt. D, Plate.
E, Guard plate.
A, Boss. B, Blade. c, Plate.
E, Guard plate.
F
D
C
DD, Bolts.
the blade can then be firmly held in the proper position by driving
in wedge pieces between the boss and the cotter, the washers and
nuts preventing them shaking loose.
The bolts for the flanges of the
blade when so fitted are generally
tapped into the boss, the head bear-
ing on a plate fitted to two of them.
Various plans are adopted for pre-
venting these bolts from turning
round: by notching the head for a
split pin, or by notched washer
plates fitting to the heads and se-
cured with set screws, or with stud and split pin tapped into the
bottom plate, or by small square pieces butting against the nut,
held with a single set screw, the bottom washer or plate being

A
Fig. 371.-Bolt Fastenings.
A, Boss. B, Blade.
c, Bolt. D, Washer.
E, Split pin.
486
MODERN STEAM PRACTICE.
bored with a number of holes, so that the plate can be shifted to
accommodate the head. Others use T bolts, which are let into the
boss, the nut being cross cut at the top for a split pin to pass
through, which prevents it from turning round; a plan likewise
adopted when the bolts are tapped into the boss.
Propeller blades are made of cast iron or steel, and recently

bronze has been used for this purpose. The advantage in
using bronze for propellers lies in the greater durability and the
smoothness of the skin. Manganese bronze has now been in use.
F
AN
O
A, Bulkhead.
Fig. 372.- Lowering Propeller.
B, Sliding bush. c, Radial gland. D, Pillow block. E, Lifting gear.
F, Well.
MARINE ENGINES.
487
1
by the Admiralty and mercantile firms with good results. The
blades can be made thinner and smoother than with steel, the latter
suffering from corrosion. The cost of the former is greater than
steel, but the endurance being in excess economy appears to be
attained by its use.
Plan for Lowering the Propeller below the Keel of the Ship.-
In long ships the pitching in a heavy sea, and the vertical motion
of the waves, injuriously affect the action of the propeller when
fitted in the usual way, causing the engines to "race" dangerously,
as well as diminishing the speed of the vessel. In Fig. 372, the
propeller is shown in its normal position, the shaft being in a
straight line with the rest of the shafting. On the ship arriving in
shallow water the screw is raised so that the point of the blades
rotate above the level of the keel; and the shaft can be still further
raised, exposing the boss, when the ship is in light trim. In this
way a broken blade can also be replaced without dry dock accom-
modation.
To effect this movement of the screw the two last lengths of
the shafting are coupled with a universal joint, the inboard shaft
having a fixed pillow block, while the screw shaft is fitted with a
sliding bush, lined with strips of lignum vitæ in the usual manner.
The bush is guided by the two cheeks of the stern post, and it is
raised by means of a rack which passes upwards and is connected
by gearing to a steam engine placed on the upper deck. The
shaft works through a slot in the after bulkhead, the water being
excluded by a radial gland working on two centres; while the
universal joint works in a chamber in the after end of the screw
alley, and is at all times accessible to the engineers. The lifting
rod and gearing are inclosed in iron casings, which extend to the
upper deck, and exclude any water that may rise.
To prevent
warps from fouling the screw when raised in shallow water, a sliding
keel is run out by a mechanism placed on the upper deck. The
want of the usual keel piece joining the inner and outer stern post
is fully compensated by the increased width and extra thickness at
the head of the screw aperture, the centre of effort of the rudder
being raised above the ordinary height. A false foot is fitted to
the bottom of the rudder post, which can be readily removed,
allowing the screw boss to be changed in a dry dock without dis-
turbing the shaft.
488
MODERN STEAM PRACTICE.
RAISING THE SCREW PROPELLER AND SHAFT.
The first point to be considered in our plan for raising the shaft
and screw at an angle from a point forward from the stern post, is
the swivelling action fitted to a water-tight bulkhead, with all the
usual appliances now in use for securing an efficient bearing for the
shaft. On consideration we think that the hemp-packed ball-and-
socket joint is best adapted for this purpose. A perfectly water-
tight joint with great swivelling action can be attained by clasping
the short swivelling tube with an elastic ring expanded over the
tube, at the same time compressing the ring into a recessed gland,
in a way similar to what we adopted some years ago for packing

H
Li
K
El A
JAGAHA
Fig. 373.-Lifting Gear for Screw Propeller.
C
D E
F, Curved stern post.
A, Propeller. B, Shaft. c, Ball and socket. D, Coupling. E, Pillow block.
I,
1, Well. K, Manhole. L, Steam purchase.
G, Bearing. н, Rack.
H,
the tubes of the surface condenser; but as part of the weight of the
propeller is taken at this swivelling centre, the plan is not rigid
enough, and a hemp-packed metallic ball and socket is to be pre-
ferred. This should be fitted with a lignum-vitæ bearing, and
stuffing box for the shaft; the socket having a projecting ring cast
on, which is accurately turned, and fits into a strong ring rivetted
to the bulkhead, the ring projecting through a hole cut in the
bulkhead, which is made very stiff at that part; this ring is bored
out in the ship in the usual manner. The seating has likewise a
flange cast on for bolting it firmly to the ring. The gland for the
stuffing box of the ball is made very strong, for taking the inward
MARINE ENGINES.
489
pressure due to the head of water, as well as for clasping the ball
firmly, preventing it from turning; while the hemp packing has
but little to do, as there is no movement of the ball when the shaft
is revolving. When the surfaces of the ball and socket are properly
machined in the workshop, the same means being used for turning
the ball-and-socket connections as for the locomotive engine, the
two surfaces will be mathematically exact and perfectly water-
tight.
The stuffing box for the shaft is of the usual description, fitted
with a lantern brass for keeping the shaft properly lubricated with
oil. On the under side of this stuffing box a broad flat sector is
fitted, the principal use of which is for holding the ball at any angle,
and which may be made stiff enough to prevent any movement of
the ball.
The coupling may be of the disc description, having a concave
surface on the one side and convex on the other, or as it were part
of a ball and socket; this form we consider necessary to raise the
shaft easily at an angle. Part of the surfaces remain in contact
when the shaft and propeller are raised for inspection or to replace
a broken blade, or when the vessel is under wind power alone.
But as we consider the propeller shaft should be placed in from
the stern of the vessel, so as to be able to replace a shaft at sea or
when lying in harbour, we propose using a box coupling for the
connection between the propeller shaft and the main line of shafting.
The outside bearing brass for the shaft is cast in two halves, the
division being in a vertical line, and is fitted with lignum vitæ in
the usual way. Flanges are cast on the brass at the under side,
and secured with bolts and nuts. The top is secured by a cap of
brass or wrought iron; if the latter is used it should be dipped in a
zinc bath to prevent oxidation. The flanges cast on the brasses
for taking the cap are quite flat across the bearing; all the bolts
should be of Muntz metal, with brass nuts. There is a bottom
bush of metal, which is accurately turned, and fits into the half eye
formed on the stern post; this bush is bored out conically, for
taking a corresponding turned part on the brass bush. The stern
post is bored out in the ship along with the ring fitted to the water-
tight bulkhead. The cap has two lugs forged or cast on, for taking
an eye formed on the lifting rack; the eye should be bushed, and
the pin forming the joint made of Muntz metal. The cap has a
part cut out at the sides which work in the sector guides, placed on
490
MODERN STEAM PRACTICE.
each side of the well formed in the stern of the vessel, the curve of
the guiding plates being struck from the swivelling centre.
The hoisting gear for small propellers is placed on the deck, and
consists of a screw and worm wheel, with a pinion on the worm-
wheel shaft, working into teeth cut in the rack, which is directly
connected by the pin joint on the bearing cap; the rack slides on
a roller placed at the top, opposite the pinion on the worm-wheel
shaft. This gear is sufficient for small propellers, and has the
advantage of sustaining the weight in any position without the use
of pauls, as in ordinary crane purchases. Of course, steam power
may be used, as shown in Fig. 373; and the arrangement can be
modified for propellers of the largest size.
The inside stern post is carried up just a little above the centre
line of the shafting; the curved guide plates may either be rivetted
or forged on. These guide plates are also rivetted to the side of the
well, which is carried forward to the bulkhead, and strongly rivetted
to the angle-iron ring, as shown. The stern post and the keel are
stiffened with a plate, rabbetted to the keel and to the stern post,
and firmly rivetted to it, and to the under side of the well and the
bulkhead, by means of angle iron. Every alternate floor plate is
also carried up and rivetted to the plating forming the well, which
is carried up to the under side of the deck, forming a very strong
attachment between the keel and the top of the ship. A manhole
is fitted to the top of the well inside of the ship, through which a
sling can be attached to the under side of the shaft, when lifting it
out or putting it in; another sling passes over the boss of the
propeller at the top end. Before lifting the shaft out, a guiding
shackle is hung from and secured to the manhole.
We will now describe the manner in which by this arrangement
the shaft and screw are lifted and again replaced, when the vessel
is at sea or lying in some foreign port. In the first place the box
coupling on the end of the shaft and inside of the ship must be
drawn back; the gland bolts on the socket holding the ball
slackened a very little, and the nuts on the sector underneath eased:
then we are ready to lift the propeller and shaft. Before doing so
the manhole cover should be removed on the top of the well, and
all the necessary tackle be got in readiness. The propeller and shaft
are then raised a little with the hoisting gear, and the blades of the
screw taken off the boss; the shaft is then lifted a little farther, to
the angle of inclination for withdrawing it out of the ball and
MARINE ENGINES.
49!
socket; prior to which a blind flange with a short pipe accurately
bored and turned is slipped over the end of the shaft, with a
ring of india rubber placed over the short tube. The slings are
then put on the shaft, and when the top one can be attached to a
crane, it is easily drawn out of the ball, the blind flange and short
pipe follows it up, and takes the place of the shaft, keeping the
packing in its proper position; the flange is then screwed up with
the same nuts as for the gland, and in this way a double protection
is afforded by the ring joint against water getting into the ship.
The guiding shackle is then fastened to the manhole, and as it is
only a foot or so below the water, it acts as a guide in placing the
shaft in again. When the shaft is clear of the ball it can be easily
lifted out; and it is replaced in the same way; the ball being held
at the inclination by the nuts on the sector placed underneath the
socket. When the shaft is put in again, it is passed through the
top bearing brass, then through the guiding shackle, and is lowered
into the wooden bearing in the ball, and then into the short pipe
on the blind flange. A small testing tap is fitted on the flange, for
allowing the compressed water to escape, as also to prove if the
packing around the shaft is perfectly tight before withdrawing or
taking off the flange or pipe piece.
THE COMPOUND ENGINE.
The Cornish engineers have for a long period taken the lead in
the important matter of the economy of the steam engine, some of
their large pumping engines doing duty with barely 3 lbs. of coal
per actual horse power per hour. This result is due to the high
steam pressure used, cutting off the steam soon, and working with
a large measure of expansion, for which the long stroke of the
piston in these engines is admirably suited; these facts, combined
with the careful clothing of the parts where radiation takes place,
account for the small amount of fuel consumed over that of ordinary
engines. The principle of compounding was tried many years ago
by Hornblower, Woolfe, and M'Naught, but was not introduced
successfully into marine practice till 1854, when Messrs. Randolph,
Elder, & Co. fitted up the steamer Brandon. The first vessel of
492
MODERN STEAM PRACTICE.
H.M. navy to be fitted with compound engines was the Constance,
built by the same firm in 1863. In marine engines the Cornish
principle has to a certain extent been carried out. Large cylinders
have been adopted, but we consider that there is still great room for
improvement. Longer strokes should be aimed at, although there
must be a limit in this direction, owing to the confined space of the
midship section of steam vessels; but with horizontal engines on the
return connecting-rod principle there is nothing to hinder the intro-
duction of strokes of 4 feet 6 inches and upwards for engines placed
in exceedingly fine sections. This for medium power would be a
great advantage over those engines having a stroke of 3 feet or so.
A full measure of expansion with a single cylinder has often been
obtained, and with good results; but there are certain difficulties
to contend with, the chief one lying in the details, as all the parts
require to be made of extra strength, and when 60-lb. steam per
square inch is used, with a large area of piston, the engine becomes
very heavy. This is not at all to be desired, as the permanent load
should be kept as low as possible, more especially for high-speed
horizontal engines, there being no doubt that the wear and tear of
large heavy pistons and their adjuncts forms a serious item of ex-
pense on board ship. Trunk engines have been recommended, so
as to carry up as it were the weight of the piston; and there is little
doubt that the large surface of the trunks tends to lessen the wear,
but it does so at the expense of lubricants, more especially with the
high pressure and dry steam now adopted.
To obviate the defects inherent in the single-cylinder arrange-
ment, using high steam with a large measure of expansion acting
on these great pistons, the Compound Engine has been adopted to
a considerable extent; although the same type of engine is by no
means a novelty, as, for manufacturing purposes requiring great
regularity of motion, beam engines fitted with high and low pressure
cylinders have long been used. The motion is very easy and
uniform, more especially at the beginning and ending of the stroke
of the piston, which is due to the steam expanding from the bottom
of the small piston to the top of the large one, and vice versa; thus
the steam from the boiler acting on the small piston is met by
a counteracting pressure, which tends to lessen the shock more
or less felt with ordinary engines. The large or low-pressure cylin-
der is placed at the end of the beam, and the small or high-pressure
cylinder is usually one-half of the diameter of the low-pressure one;
MARINE ENGINES.
493
the contents of the smaller cylinder is about one-fifth of that of
the large one, owing to the stroke of the high-pressure piston being
shorter, consequently when the steam is admitted the entire length
of the stroke it afterwards expands into the large cylinder, the
measure of expansion, theoretically speaking, being as five to one.
Practice and theory are fully carried out in this arangement;
the steam, after doing duty in the high-pressure cylinder, is imme-
diately taken up and expanded in the low-pressure one, and then
exhausted into the condenser. Some of those engines have a fixed
measure of expansion, the valves having no lap, thus admitting the
steam from the boiler into the cylinder the entire length of the
stroke of the piston; in others the expansion of the steam is more
fully carried out by cutting it off in the high-pressure cylinder.
In marine engines this principle is carried to the utmost limit by
cutting off quickly in the high-pressure cylinder; thus in the first
instance there is a large measure of expansion taking place in the
small cylinder before the steam is admitted into the large one,
where it is still further expanded.
The late Professor Rankine, in treating of this subject, defines a
compound steam engine as "one in which the mechanical action of
the steam commences in a small cylinder and is completed in a
larger cylinder;" these engines, again, are divided into two classes:
"first, those in which the steam passes directly, or almost directly,
from the high-pressure to the low-pressure cylinder," the forward
stroke of the latter cylinder taking place either exactly or nearly at
the same time with the return stroke of the former cylinder; and
secondly, those in which the steam, on its way from the high-pres-
sure to the low-pressure cylinder, is stored in a reservoir, so that
any convenient fraction of a revolution may intervene between the
ends of the strokes of the cylinders. As regards the theoretical
efficiency of the steam the compound engine possesses no advantage
over an engine with a single cylinder of the dimensions of the low-
pressure cylinder, working with the same pressure of steam and the
same rate of expansion." In pointing out the advantages which the
compound engine possesses the following are referred to:-First,
in point of strength the action of the steam when at its highest
pressure takes place in the compound engine upon a comparatively
small piston, thus diminishing the amount of the greatest straining
force exerted on the mechanism and framing; secondly, it is shown
that for economy of heat a single-cylindered engine requires to be
494
MODERN STEAM PRACTICE.
wholly jacketted so that the temperature may be kept up to that
of the steam on admission; but in the compound engine the
smaller or high-pressure cylinder only requires to be kept to this
high temperature; and thirdly, economy of work is obtained
through the equalizing of the strains by the piston-rods on the
bearings.
The machinery employed in our large ocean steamers is now
of a very massive description, the high and low-pressure cylin-
ders being of large diameter and the steam pressure very high. The
Alaska recently launched on the Clyde (1881) is supplied with engines
working up to 10,000 horse-power, the pressure of steam being
100 lbs., the high-pressure cylinder being 68 inches and the low-
pressure cylinders 100 inches in diameter, the stroke being 6 feet.
The arrangements for direct-acting horizontal engines are various.
In some examples the small cylinder is placed on the same centre
line as the large one, bracketed or fitted to the cover of the latter,
with one piston rod common to both pistons. In other arrange-
ments an annular cylinder is placed around the small high-pressure
one; this plan requires a long crosshead for taking the central or
high-pressure piston rod, while there are two piston rods for the
annular piston, one on each side of the high-pressure one, the
connecting rod joining the crosshead directly to the cranked shaft,
while in the former plan the connecting rod can be either direct
or on the return principle. Some makers have introduced a sort
of large hollow cast-iron piston rod, having a piston at each end;
this great rod is kept steam-tight by an internal stuffing box,
placed at the centre length of the cylinder. This arrangement,
therefore, is simply two cylinders placed back to back formed in
one casting, the two central cylinders being the high-pressure ones,
while the low-pressure cylinders are at each end; or, more correctly
writing, the high and low pressure principle is carried out in one
cylinder common to both. A single-acting engine on this mode of
construction would be simply a single trunk engine, the trunk end
being for the high pressure and the other end for the low pressure.
The power, however, is better equalized by adopting the trunk
engine in duplicate, as described above; and this arrangement can
be worked direct, or return connecting rods may be adopted for
marine purposes.
As the cylinder is double the length of the
ordinary arrangements, the latter plan is adopted to suit fine mid-
ship sections.
MARINE ENGINES.
495
In some examples of combined engines the high-pressure cylinder
is placed on the top of the large cylinder, and connected by means
of a rocking beam. Although the valves are greatly simplified in
this plan, yet it cannot be considered a good one. When the pistons
work in opposite directions, the steam expands from the one to
the other, and the OUT stroke expansion of the small cylinder is
taken up by the IN stroke of the large cylinder, and vice versa;
but when the small piston is attached directly to the large one,
the OUT stroke expansion of the small cylinder is taken up by
the OUT stroke of the large one, thus entailing long steam passages
between them, not to be desired. To obviate the objections to
the short rocking beam, spur-wheel gearing has been introduced,
having separate cranked shafts for each cylinder. This plan, how-
ever, involves complication, and is not needed, for when the
high-pressure cylinder is placed alongside of the low-pressure one,
as in the ordinary horizontal engine, such an arrangement meets
all the requirements, and as simplicity on board ship is the main
thing to study, the reduction of the wear and tear becomes of the
first importance.
In reference to this point attention may be drawn to the vertical
class of engine, more especially adapted for the mercantile marine,
so successfully constructed by various engineering firms. The
platform space occupied by these engines is not so great as that
required for the horizontal type, and the wear and tear is greatly
diminished, vertical pistons, valves, &c., keeping longer in good
working order than those lying on their side,—a fact now beyond
dispute. In the ordinary arrangement of this class of engine, the
cylinders are supported overhead on a cast-iron framing securely
bolted to the bed plate, on which is cast the pillow blocks for the
cranked shaft. The cylinders are arranged the same as for inside-
cylinder locomotive engines with the valves placed between the
cylinders, thus placing the valve gear centrally and greatly simpli-
fying the mechanism for working the valve. This engine, strictly
speaking, is not of the direct-acting type, as the air pumps in
most cases are worked by a rocking beam for each; when so fitted
the descent of the pistons and adjuncts is in a measure balanced
by the column of water lifted by the pump. This is a great
advantage, and is decidedly to be preferred to the direct mode of
working the air pumps from the piston by a rod passing through
the bottom of the cylinder and attaching to it the air-pump bucket.
496
MODERN STEAM PRACTICE.
For engines of small power eccentrics have been successfully adopted
for working air pumps lying in a horizontal position, but the plan
is not nearly so effective as a means of balancing the machinery as
working the pumps by the rocking lever already described, with
links in connection with the crosshead of the piston rod at one end
and the crosshead of the air pump at the other end.
The arrangements for compound engines of the vertical class are
similar to those for single engines of the same class. The cylinders
are supported from the top of the surface condenser on the one
side, and there are cast-iron frames on the other; in some cases
wrought-iron columns are introduced. The high-pressure cylinder
is fitted to the side of the low-pressure one, and connected by
means of a rocking beam for each; thus the pistons travel in
opposite directions, and the valve gear is simplified as in horizontal
arrangements. Some engineers place the high-pressure cylinder
on the top of the cover of the low-pressure one, with one piston
rod common to both pistons.
Theoretically and practically, direct action is correct, as the
steam from the one cylinder is immediately taken up by the other;
but the complication of the parts is an evil to be avoided, and
engines are now introduced having the minimum of working parts.
These engines consist of one high-pressure cylinder and a low-
pressure one. The cranks in some examples are at right angles
or 90°, in others the crank centres are 135° apart (and even, going
to extremes, in a line with each other), with which the crank
for the low-pressure cylinder leads, thus the piston being met by
the expanding steam from the high-pressure cylinder, it is cushioned
at each end of the stroke-a point necessary in all engines having
a high rate of piston speed. When the cranks are placed at right
angles, the exhaust steam is admitted into a compartment, generally
taking the form of a casing around the cylinder, before it is
expanded into the large cylinder. This plan is necessary to reduce
the back pressure on the small piston; besides, the large piston is
not in a proper position at the ending and returning of the high-
pressure piston fully to utilize the steam. The large piston, too,
must travel a little more before the expanding steam can be
admitted into the cylinder.
In the large vessels recently built three cylinders are commonly
adopted, two large and one smaller, the cranks being placed at 120°.
See Plate of the engines of the S.S. Parisian.
MARINE ENGINES.
497
The engines are three-cylinder compound inverted-cylinder type,
working cranks set equal distances apart, that is 120°; the high-
pressure cylinder is placed between the two low-pressure cylinders,
into which its exhaust steam is

led by means of two brass pipes
attached to the valve casings.
The admission of steam to
each cylinder is regulated by
means of a piston valve, worked
by a rocking shaft and levers,
which are in turn driven by
means of double eccentrics and
link from the crank shaft.
The crank shaft is a "built-
up" one of steel, and in three
distinct pieces coupled together
with flanges and bolts.
Fig. 373A.-High Pressure.

Fig. 373 B.-Aft Low Pressure.
Fig. 373 C.-Forward Low Pressure.
The surface condenser con-
tains 9624 square feet of con-
densing surface. Two air pumps
are bolted on the back of the
condenser, and worked, along
with the feed and bilge pumps,
by means of levers and links
from the low-pressure cylinder
crossheads. The circulating
pumps consist of two centri-
fugal pumps, each worked by
separate engines.
The high-pressure cylinder is 60 inches diameter x 5 feet
stroke. Each low-pressure cylinder is 85 inches diameter x 5 feet
stroke.
Indicated DIAGRAMS FROM ENGINES OF
SCREW STEAMER "PArisian.
Steam 70 lbs., Vacuum 29,
"
Revolutions 83'7.
The engines of the Servia and City of Rome, the largest ships
afloat excepting the Great Eastern, are also of the compound
inverted type, those of the Servia working up to about 10,000
indicated horse-power. The Alaska's engines are also capable of
working up to this high figure.
It may seem strange to pass high-pressure steam through the
small cylinder, and reduce the pressure before it enters the large
cylinder; but we must take into consideration that when the
D

32
498
MODERN STEAM PRACTICE.
cranks are placed at right angles to each other, the engines are
found to be more easily handled, while it is necessary, as before
described, to reduce the back pressure on the small piston: this
deviation from what theory points out as correct is successfully
adopted in practice. To meet theory on the one hand, and over-
come the difficulty of starting the engine on the other, the cranks
have been placed farther apart; thus the expanding steam from
the high-pressure cylinder is sooner picked up by the low-pressure

Fig. 374.-Compound Marine Engines, by Fawcett, Preston, & Co., Liverpool, fitted on
board the Screw-ship "Itata."
Sectional End Elevation.
piston, while the large piston is properly cushioned, which would
not be the case were the crank centres directly opposite each other
-a position in which it is very difficult to start the engines, although
MARINE ENGINES.
499
when once set in motion they work pretty well, but on the whole
not so steadily as in the intermediate position. The air pump and

Fig. 375.-Compound Marine Engines, by Fawcett, Preston, & Co., Liverpool, fitted on
board the Screw-ship "Itata." Sectional Side Elevation.
circulating pump are worked by rocking levers for large power;
while for small power, eccentrics are used to give motion to the
pistons of the pumps.
500
MODERN STEAM PRACTICE.
SCREW STEAMSHIP "SERVIA."
(SEE PLATE.)
Gross Tonnage 7400, nett 3900 tons.
The Engines are of the three-cylinder compound direct-acting
arrangement; one high-pressure cylinder of 72 inches diameter
and two low-pressure cylinders of 100 inches diameter each, and
78-inch stroke of piston; the valves for high pressure are piston
valves, and those for low pressure slide valves, with four ports, as
shown on plans. The surface condensers (two) are placed fore and
aft, forming part of support for the cylinders; they can be worked
together or separately; the circulation of water is effected by two
of J. & H. Gwynne's 20-inch Invincible pumps; the air and feed
pumps are worked off lever on low-pressure engines. The crank
shaft is in three pieces, of Vicker's steel, and is 25 inches diameter.
The propeller is 24 feet diameter, and the boss and blades are of
Vicker's steel. The starting gear is Brown's patent steam and
hydraulic gear.
Steam is supplied to the engines by seven Boilers, six of these
double-ended, with six furnaces in each, and one single-ended with
three furnaces, in all thirty-nine furnaces, of 4 feet 2 inches dia-
meter and 6 feet 9 inches long; the total effective grate surface being
1050 square feet, and the total heating surface 27,000 square feet.
The boilers are of oval form, 14 feet 10 inches wide, 18 feet high,
and 18 feet 3 inches long.
The engines on trial developed 10,500 I. H. P., and the speed at
sea 174 knots per hour. The dimensions of the ship are: Length
over all, 530 ft.; breadth, 52 ft.; depth from top of keel to top of
upper deck beams, 42 ft. The Servia crosses the Atlantic in little
over seven days, consuming 1300 tons of coal on the passage.
SCREW STEAMSHIP "ITATA."
Tonnage 2391 B.M.
See Figs. 374 and 375, pages 498, 499.
The Engines, of 340 nominal horse-power, have one high-pressure
cylinder 3 ft. 10 in. diameter, and one low-pressure cylinder 7 ft. 2 in.
diameter; length of stroke 3 ft. 6 in. Number of tubes in surface
condenser 1164, diameter I inch. Diameter of circulating pump
I ft. 8 in., stroke I ft. 9 in. Diameter of air pump 2 ft. 8 in., stroke
MARINE ENGINES.
501
I ft. 9 in. Diameter of feed and bilge pumps (two of each) 6 in.,
stroke 1 ft. 9 in.
There are four Boilers, each 9 ft. 7 in. in length, and II ft. 6 in.
diameter. Each boiler has three furnaces, of 3 ft. diameter. The
total heating surface is 5140 sq. feet. Pressure 70 lbs.
The diameter of the screw propeller is 16 ft. 6 in., the varying
pitch 24 ft. to 27 ft.
The feed steam pumps, of which there are two, have each a
cylinder of 8 inches diameter and 9 inches stroke, driving a double-
acting pump 4 inches in diameter. They are arranged to draw
water from either the sea or the bilges, and to discharge into the
boilers, on deck, or into the sea, as may be desired. There is also
a ballast steam pump, with a cylinder 7 inches in diameter and a
stroke of 9 inches, driving a double-acting pump of 9 inches in
diameter, which draws the water from the fore and aft ballast
compartments. A double-acting hand pump is also provided,
having a diameter of 7 inches and a stroke of 15 inches, which can
also be worked from the main engines.
The Itata has a length over all of 305 ft., breadth of beam 40 ft.,
and depth under main deck of 19 ft. 6 in. The average consump-
tion of fuel during a voyage of this ship from Liverpool to
Valparaiso was only 1007 ton per hour of steaming, and taking the
indicated horse-power as 3½ times the nominal horse-power, we
have a coal consumption of under 2 lbs. per indicated horse-power.
(6
SCREW STEAMSHIP SIR BEVIS." Tonnage 919 B.M.
See Figs. 376, 377, 378, pages 502-504.
The Engines, of 115 nominal horse-power, have one high-pressure
cylinder 2 ft. 2 in. diameter, and one low-pressure cylinder 4 ft. 4 in.
diameter; length of stroke 3 ft. The surface condenser has 944
tubes, 6 ft. long and 34 in. diameter; condensing surface of tubes
1112 sq. feet.
The Boilers are cylindrical, with a total heating surface of 1982
sq. feet; area of fire grate 65 sq. feet. Steam pressure in boiler
60 lbs. per sq. inch.
The diameter of the screw propeller (four-bladed) is 13 ft. 4 in.,
the varying pitch 16 ft. to 18 ft. The Sir Bevis has a length over
all of 210 ft., breadth of beam 30 ft., depth 17 ft.
502
MODERN STEAM PRACTICE.
The vessel has a carrying capacity of 1020 tons of dead weight,

Fig. 376.
End Elevation.
о
Plan.
1-141-14
Figs. 376, 377, 378.-Compound Engines for the Screw Steam-ship "Sir Bevis.'
Messrs. Day, Summers, & Co., Engineers, Southampton.
»
Constructed by
о
of which 120 tons of coal is carried in the bunkers. Thus loaded
she has steamed at an average rate of 9 knots per hour, with an
MARINE ENGINES.
503
average consumption of 7 tons 12 cwts. O qr. 12 lbs. of Newcastle

Fig. 377.
I
B
B
Transverse Sectional Elevation.
Sectional Plan.
coal per twenty-four hours; and as the average indicated horse-
power is 360, this gives 19 lb. per hour as the consumption of fuel.
504
MODERN STEAM PRACTICE.

Fig. 378.
Side Elevation,

Sectional Plan of Condenser
and Main Frame,
MARINE ENGINES.
505
The S.S. Arizona, built in 1879 for the Guion line by Messrs.
Elder & Co. of Glasgow, is a good type of the fast ocean steamers
of the present day. She measures 465 ft. in length by 45 ft. 6 in.
breadth, and 37 ft. 6 in. deep, the tonnage being 5146. The engines
developed on trial 6357 indicated horse-power with 56 revolutions
per minute; the speed being 17.3 knots per hour.
The engines are compound with three inverted cylinders. The
high-pressure one is 62 inches diameter, and the two low-pressure
ones 90 inches diameter each; the stroke is 5 feet 6 inches; the
slide valves are of the piston equilibrium form; the surface con-
denser has a cooling area of 12,540 sq. ft., the water being circulated
by two large centrifugal pumps; the crank shaft is "built," and
is 22½ inches diameter (see p. 415); the propeller is 23 feet dia-
meter with steel blades.
There are one single-ended and six double-ended boilers, of a
diameter of 13 feet 6 inches, and length of 18 feet for the double-
ended and 10 feet for the single-ended. These are fitted with 39
furnaces 3 feet 3 inches diameter, having a grate area of 780 sq. feet
and a total heating surface of 19,500 sq. feet. The shell plates are
13/16" thick, the working steam pressure is 90 lbs.
GOVERNORS.-As the piston speed varies greatly in marine
engines when the vessel pitches in rough weather, causing a severe
strain both to the engines and hull, governors have been introduced
to regulate the supply of steam to the cylinders, and so prevent
what is technically termed "racing" of the engines, due to the screw
being only partly submerged when the vessel is pitching. Governors
should be exceedingly sensitive, and quick in acting upon the valve
for throttling as it were the steam in its passage to the cylinders,
when the pistons have a tendency to sudden acceleration of speed.
Various forms have been tried, as the four-ball, the fly-wheel, fly-
wheel fitted with vanes, &c., and others. The first-mentioned
form acts as an ordinary ball governor, the four balls being intro-
duced to remedy an evil felt with the ordinary two-ball arrange-
ment, which did not act in a satisfactory manner owing to the
motion of the vessel. The arrangement consists of a spindle taking
two arms which cross each other, and are jointed with one pin
passing through a jaw on the spindle; on each end of the arm a
ball is fitted, by this means balancing the pendulum arm of the
governor. The spindle is fitted with a sliding collar, and is con-
nected to the pendulum arms with two links, and there is a spiral
506
MODERN STEAM PRACTICE.
spring bearing on the collar, to regulate its return action, while at
the other end of the collar is fitted a lever and rod communicating

Ꮐ
PALMI DELTA.
K
P
with the throttle valve.
This
governor is carried in a suit-
able frame, and is driven by a
band passing round a pulley
fitted to the revolving spindle,
the whole arrangement lying
horizontally.
Fig. 378A shows Dunlop's
Pneumatic Marine Governor,
which has been found very
serviceable for compound
marine engines. In this gover-
nor the controlling power
lies in the level of the water
outside the ship, as this varies
from time to time with the
pitching of the vessel.
A is an air vessel, which is
placed in communication with
the sea by the valve C. The
air becoming compressed the
action is communicated to
the governor G, which con-
sists of a casing containing
an air-tight space in connec-
tion with the pipe P and fitted with an india-rubber diaphragm D.
This diaphragm, as it rises and falls due to the pressure of the air
as acted upon by the varying level of the waves, acts upon the
spring S, which motion is communicated to the throttle valve by
means of the link K.
Eig. 378A.-Dunlop's Pneumatic Marine Governor.
Fig. 378B shows an arrangement of Compound Engine which
appears to have been applied successfully for paddle-wheel steamers.
It is illustrated and described in a paper read by Mr. F. C.
Marshall, at a meeting of the Institute of Mechanical Engineers,
held in Newcastle in 1881, in which he shows that such engines
may be grouped in three typical forms, viz.:-
Ist. The two-cylinder intermediate receiver compound engine
having cranks at right angles. 2d. The Woolf engine in the
MARINE ENGINES.
507
tandem form, having generally the high-pressure and low-pressure
cylinders in line, but occasionally alongside, and always communi-
cating their power to one crank. 3d. The three-cylinder intermed-

A, High-pressure cylinder.
BB, Low-pressure cylin-
ders.
Cc, Piston rods.
D, Crosshead for piston.
rods.
EE, Side rods connecting
bottom and top cross-
heads.
F, Crosshead for connecting rod.
G, Connecting rod.
HH, Frame and guides for crosshead.
1, Crank.
KK, Main frame.
LL, Columns supporting main frame.
M, Condenser.
N, Lever for working air-pump.
F
o, Air-pump.
P, Feed pumps, &c.
H
H
Q, Kingston valve.
E
D
K
K
B
Aj
B
N
О
M
P
о
Fig. 378 B.-Three-cylinder Compound Steeple Engine for the Paddle.
iate receiver compound engine with one high- and two low-pressure
cylinders, the steam passing from the high-pressure cylinder into the
receiver, and thence into the two low-pressure cylinders respectively.
The arrangement shown by Fig. 378B is of the three-cylinder
class. The steeple form of engine is adopted; the three cylinders
of each engine being bolted to each other and to the keelsons.
508
MODERN STEAM PRACTICE.
AVERAGE CONSUMPTION OF COAL, PER INDICATED HORSE-POWER PER HOUR,
(See Mr. F. C. MARSHALL'S Paper "On the Progress and Development of the Marine

No.
High
Class.
ENGINES.
Cylinders.
Piston
Speed
Diam.
Press.
Low
Press.
Stroke.
per
Min.
Con-
densing
Diame-
ter of
Screw
Working
Pressure
'above
Surface. Propeller. sphere.
Atmo-
Number of
Boilers.
Shell.
Diameter. Length.
BOILERS.
Furnaces.
Total Dia-
No. meter.
In.
In.
In.
Ft.
Sq. Ft.
Ft. In.
Lbs.
1 2 3 4 5 6
78
I
AAAAA A
34
61
45 450
2466
15 3
70
42
80
48
552
72'5
35
70
48 400
2400
17 O
46
87
57 484
5000
19
90
80
22
44
30
360
705
II
100
2223 m
Ft. In.
12
13
II
12
I
I2
50
86
W13
54
540
4865
17 6
A
35
70 48
424
2000 17
O
90
A
54 94
60
530
7420
18
9
A
54
94
60 486
7422
18
IO A
30
58
II
A
29 56
12 A 34 66
13
A
36 68
39 400
33 350
42 406
42
1518
14
1250 13 3
1700 15 6 80
434
1821
16
ON MOM
3
14
A
54
60
97
480
7427
18 10
15
16
17
18
19
AAAAA
51
88
60
590
5000
17 6
75
≈ 87N828 FR K
72
4
H16
75
82.5
80
70
77
2062 2 2 26
9 6
12
12
12
II
066 3oo +06 aaoo
Ft. In.
15 O
8
Ft. In.
3 6
18 6
18 6
8
3 6
18 6
12
3 9
8
II
6
3
3
10 of
12
3 6
18 6
8
9
ΙΟ
6
18
3
9
10
6
18
3
ΙΟ
6
ΙΟ
13 4
10
14
42
ΙΟ
70
4
15 10
W15 6
H18 6
IO
66 36
3
3
3 3
6
18
3
O 2 2 2 0 34 2
mmmmMMMMM
3 6
3 4
10
9
12
4
2
28
53
38❘ 380
1560
14
O
75
2
12
I
9 5
4
3 3
W13 8
50
86
54 540
5500
17
6
38
70 48
416
2600
17
35
70
48 408
2005 17
20
A
35 70 48 440
2000
20
21
A
342
64
42
500
1647
15 4
9006
22 A 48
84 бо
550
4468
19
о
23 A 50 86 54
510
4842
17 9
24
A
54
94
бо
441
7420
17
25
A
56
97
54
504
5000
18
26 A
бо
30
36
372
1600
13
27 A 36
45
560
2900
13
28
A
36
36 450
2059
13
996 0 0 O
29
A
36
68
42 530
2500
13
30
A
36
67
42
530
2400 13
Mean
467
28888 2 2288K282 E
70
4
ΙΟ о
12
H17
3 6
31
80
•
90
2
II
6
18 6
8
3 5
2
IO II
18 6
8
3 3
80
2
9 6
13
8
8
(WII 9
70
16 6
18
3
H14 3.
3
2
70
6
11 31
9 10
70
6
12
9
ΙΟ
að
6
༡༠
90
75
70
༡༠
70
O ~ ~ ~ ~ 2
6
13
2
II
2
13
2
13
2
14
14
omo o O O
IO
HHH
3
9 7
14
9 4
II
II
333 M
000000 1
370 4OO
18
18
3
18
3 3
6
3
12
3
6
3
6
3 6
3 6
023 2 H 266
77.4
wwwwww w w
C
32
B
В
∞ 0 2 700 00 00
B A BUUUU
48
26
27
27
28
28
16
26
uus aaca un ci coo
83
бо 523
9000 23 6 70
W14
58
45
444
1700 15
O
80
56
52 395
56
52
412
бо 54 504
бо
34
54 522
30 360
1730
1650
4100
4500
15 9
80
15 9
20
20
768 12
52
42 336 2400 17
9o66 3
75
90
å å å i 282
Co
8
H 9
19 10
32
3 3
2
I
13 4
W12 O
H14 2
9 6
6
3 0
24
О
6
3 4
68
I
70
76.6
H33H 2
I
6
II
II
II
IO 9
W=Width
H = Height
6
17
6
18
6
17 6
18
6
9 10
17
∞ow ã ã
322 mm
3
4
2 10
2 10
3
3
2 N
2
Σ
Mean
4.37
39
D
62
88
90
66 605
21 0
90
00
7
13 6
6 {
'six 18
onero
393 3
Class A-Compound Engines with one High and one Low-pressure vertical
""
B
C
D
""
one
two
one
21
two
"1
one
two
* Always working with early cut-off; engines never pressed; Welsh coal.
MARINE ENGINES.
509
BY STEAM SHIPS WITH COMPOUND ENGINES IN LONG SEA VOYAGES.
Engine,” read at meeting of Inst. Mechanical Engineers, held at Newcastle, 1881.)
BOILERS.
PERFORMANCE.

Tubes.
Total
Heating Surface.
Heat-
Indi-
Coal Consumption.
Fire-
ing
Surface
cated
grate
Out-
Area.
Total
No.
Length. side
Tubes.
Furna-
ces, &c.
per
I.H.P.
Horse
Power.
Total.
In 24
Hours.
Per I.H.P.
Heating
Surface
per lb. of
Coal per
Hour.
per Hour.
Diam.
Ft. In.
In.
Sq. Ft.
Sq. Ft.
Sq. Ft.
Sq. Ft.
Sq. Ft.
I.H.P.
Tons.
Lbs.
Sq. Ft.
800
6 O
3
140
3688
528
4216
4'68
900
14'5
*1'50
3'12
6000
3'19
1881
32°25
1'60
I'993
640
6 10
3
160
3814
626
4440
3'7
1200
21
1.63
2*265
1164
6 7
250
6420
1383
7803
3'545
2200
40
1'66
2'136
172
7 3
49'5
тобо
342
1402
3'34
420
7'5
1*67
2'0
1024
7 0'
273
6530
1192
7722 2'88
2677
48
1'67
1'725
608
6 10
150
3822
952
4774 3'97
1200
21'5
I'69
2*35
1308
7 6
313
8983
1856
10839 4'9
2207
40°3
1'7
·2.88
1266
7 6
324
8735
2605
11340
6°3
1801
32.8
I'7
3'705
344 7 3
69'64 2120
488
2608
4
650
12
1'72
2°34
316
7 0
660
1891
488
2379
4'74
500
9'5
1'76
2'69
352
7
460
7
1314 7
306
107'25 2708
766
3474 3'975
875
16'5
I'76
2'27
IIO
2950
764
3714
4'34
854
16.75
1'763
2°46
329
9198 1847
11045
5'52
2000
38.6
I'80
3'065
1224 7
о
31/2
332'5 7850
1398
9248
3'365 2745
54
1.83
1839
328 7 о 3/31/1
78
2050
383
2433 4'34 560 II
1*84
2°36
J016
7 о
3/1
273
6393
1132
7525 3'105 2422
48
1*85
1'647
65
4864 4'18
1160
23
1.85
2°26
616
6 10
150
3872
954
4826 4'39
1099
22
1'87
2'35
544
6 9
136
3384
1012
4396 3.875
1135
23
I'89
2'05
368
6
тоб
2332
618
2950
3'35
880
το
I'90
I'762
1140
1188
1326 7 6
1062
360
6 9
31
340
7153
1047
8200
3'56
2300
47
I'90
1873
912
380
408
06 3∞ 4400
7776 56 77
310
7603
2236
9839
4'44
2213
43'5
I'90
2'34
312
9149
2601
11750
49
2400
48°9
I'90
2'58
292
6913
1302 8215
3'282
2500
51'9
1'93
I'70
wwwwwJ
115
2230
523
2753
4'59
600
12'5
I'945
2°36
166
3884
738
4622
2.88
1600
32
t20
I'44
хоб
2272
582 2854
2'795 1020
22
t2 125
1'315
130
129
2876
586
3462
2*77 1250
29
12:25
I'23
2866 585
345I
2.8
1230
28
12:25
I 243
3.917
1.828
2.178
2432 7 2
3/3/1
624
15783
3321
19104 3.9
4900
93
I'77
2'2
472
6 6
31 99
2566
594
3160
3.85
820
16'75
I'90
2'026
284
9
296
1116
II16
6
150
544
6
6
6
6 666 o
O
4
←
102
2675
569
3244 4'45
730
15'1
1'92
2°32
6
43343
102
2750
820
3570 4'63 771
16
I'93
2'4
300
6165
1235
7400 3'89 1900
40
I'96
302
6171
1243
7413 4'0
1850
40
2 ΟΙ
47°25 1004
132
346
1350 5°0
270
7
2'25
I'986
I'95
2'22
3033
617
3650 4'06
900
24
2'47
1'641
4.22
2.026
2.096
2522 7 0
31780 16200
3300 19500 3'09
6300
137
2'035
I'52
Cylinder, working two cranks at right angles.
""
""
""
one crank. Cylinders in line (tandem).
two cranks at right angles.
three cranks at 120°.
Cylinders in line (tandem).
+ These four ships are very limited in boiler power.
510
MODERN STEAM PRACTICE.
The preceding table of results from recent practice with the
marine engine is a valuable and interesting one, and not the least
important part of its information is that showing the relations
existing between some of the more particular parts when compared
with each other, and with the power developed by the engines. Thus
it is shown that the heating surface is about 4 sq. ft., and the con-
densing surface about 2 sq. ft. per indicated horse-power. Again, the
consumption of coal is about 18 lb. per indicated horse-power per
hour, and the heating surface is about 30 times the grate surface. The
indicated horse-power appears to be about 8 times the grate surface,
and the heating surface per lb. of coal per hour is about 2% sq. ft.
RULES FOR THE HORIZONTAL DIRECT-ACTION
MARINE ENGINE, &c.
Nominal norse-power.- For calculating marine engines a com-
mercial unit is used, termed "nominal horse-power." A certain
number of square inches of cylinder area, and a velocity of piston
in feet per minute, are given; 7 lbs. per square inch being the
recognized pressure, and 33,000 lbs. the duty of one horse-power
per minute. Hence the formula—
Area of cylinder in square inches x 7 lbs. x feet per minute
33000
×
= N.H.P.
The indicated horse-power of an engine has nothing whatever to
do with the nominal horse-power, and can only be found by means
of an indicator diagram taken off the engine, from which the mean
pressure on the piston is found, as explained in another part of this
Work. The engine maker is often asked to give four, six, or even
more times the nominal measure; and this can readily be calcu-
lated by giving a large steam pressure over that used for finding
the nominal power, determining the point of cut off, besides taking
into consideration the vacuum in the condenser, which may be put
down in round numbers at 12 lbs. per square inch. Hence the
formula-
Area of cylinder in
square inches
× (Mean steam
ean steam pressure
per square inch
+
Vacuum per Velocity of piston attained
square inch
in feet per minute
33000
gives the indicated horse-power, which is simply the actual power
given off on the piston.
MARINE ENGINES.
511
The power varies approximately as the cube of the speed of vessel
(see p. 513).-A vessel of a certain form and tonnage, and of 200
horse-power, has a speed of 12 knots per hour, and we wish another
vessel of the same lines and tonnage to attain a speed of 15 knots
per hour: the cube of 12 is 1728, and of 15 is 3375; thus—
3375 × 200
1728
= 390 horse-power.
Thus very nearly double the power is required to give an additional
speed of 3 knots per hour to the vessel, and this is a serious matter
when we remember that the amount of coal consumed is in the
same ratio. For example: supposing the vessel had to steam over
3000 knots, going at a speed of 12 knots per hour it would take
250 hours to run the distance, and going at 15 knots per hour it
would take 200 hours; therefore taking the horse-power as indi-
cated, and the coal consumed per horse-power per hour at 2½ lbs.,
we have-
200 x 2'5 × 250 = 125,000 lbs. of coal.
390 × 2.5 × 200 = 195,000 lbs. of coal.
or, in round numbers, 31 tons more coal is required to perform the
same distance at the quicker rate of speed. In the construction of
all steam vessels, respect must of course be had to the facilities for
coaling at the stations on which they are intended to run, and their
carrying capacity for coal adapted accordingly. Theoretically and
practically it has been proved, under all circumstances, that a low
rate of speed is the most advantageous in an economical point of
view. Thus when ships of war are cruising at sea it is advisable to
work the engines at half-power, or such a fractional part of the
power as may be thought best under the circumstances; but on no
account should the steam power be decreased in cases where the
full power may be demanded at a moment's notice,-economy in
coal being but a secondary consideration when the safety of the
vessel is in question.
Proportion of power to tonnage.-In the merchant service the
proportion of power to tonnage for vessels of about 2000 tons of
tonnage ranges from 1 to 56 to 1 to 3·8; in a number of vessels,
with a horse-power ranging from 80 to 700, the average proportion
was I horse-power to 46 tons of tonnage. This is only the nominal
or commercial horse-power allowed; but the actual or indicated
horse-power depends on the lines and draught of water of the
vessel, taking into consideration the speed that may be required.
512
MODERN STEAM PRACTICE.
To determine this point correctly the shipbuilder and engineer
should work hand in hand; and by studying the lines and configu-
ration of a particular class of vessel, with a knowledge of the power
actually required to propel her at a certain speed, they may be
able to adapt the power to the requirements of future vessels.
Rule for tonnage.-Multiply the length of vessel between per-
pendiculars, minus three-fifths of the breadth, by the square of the
breadth divided by 2, and divide the result by 94 as a constant:
the quotient gives the tonnage in old builders' measurement.
Performance of screw vessels.-To find the coefficient for screw
ships, multiply the cube of the speed in knots per hour by the
midship section of the vessel in square feet, dividing the result by
the indicated horse-power: the quotient will be the coefficient of
performance-the higher the number the better the result.
To find the speed with the coefficient, multiply the indicated
horse-power the engine is intended to work to by the coefficient
for the class of vessel, dividing the result by the area of midship
section in square feet: the cube root of the quotient is an approxi-
mate of the speed the vessel will attain.
Another method for finding the coefficient of performance is to
multiply the cube of the speed in knots by the cube root of the
displacement in tons squared, and divide the result by the indicated
horse-power. Hence the following formulas-
(First method) _Speed³ × midship section in square feet
3
Indicated horse-power
(Second method) Speed x displacement
Indicated horse-power
= coefficient.
= coefficient.
For 14 knots per hour, the coefficient for ironclads by the
former method-the length of the vessel being seven times its
breadth-may be taken at 600 as a constant, and 500 when the
vessel's length is five times its breadth. For the merchant service
the coefficient varies according to the length of the vessel-the
greater the length the better the coefficient becomes. For instance,
the steamship Cadiz, with a proportion of length of eight beams,
has a coefficient of 800; while in others, with a length of seven
and three-quarter beams, it is about 662. It will thus be seen that
long vessels are the most economical in carrying power, the speed
attained being better than in a shorter vessel for the same indicated
horse-power, while of course more stowage is afforded for cargo;
and many screw steamships, after running for years, have been
MARINE ENGINES.
513
lengthened, with a view to gain these important advantages, whilst
retaining their original engines and boilers.
The following extracts from a recent paper on this subject will
show the conditions involved in this question.¹
"It is an immediate consequence of the fundamental definitions
of mechanics that if the gross indicated horse-power required to
propel a vessel at the rate of V nautical miles per hour be denoted
by E, then the gross resistances to the motion of that vessel is
expressed by a quantity of the form C, in which C is a coeffi-
cient dependent upon the construction elements and development
of power in the engines, or, in an equivalent, but directly opposite
point of view, the construction elements of the hull and circum-
stances affecting the expenditure of the developed power.
C
M V³
E ;
•
Now, a first approximate statement of the problem of steamship
propulsion, according to mechanical principles as stated by Smeaton
and other mechanicians, is furnished by the well-known formula,
sometimes termed the 'Admiralty Formula,' in which M
is the immerged midship area, E the gross indicated horse-power
corresponding to the trial speed, V nautical miles, and C, a numeri-
cal coefficient, which, in the cases where M, E, and V are known, is
easily calculated, and which, subject to the following reservations,
has been generally adopted as an approximate measure of the
efficiency. It is found, however, in trying experiments on the same
vessel at different speeds, where there would seem to be no good
reason for supposing great variations in efficiency, the coefficients
thus found vary in an extraordinary degree; also, in passing from
one vessel to another, the variations have been found irregular, con-
tradictory, and perplexing to a degree which, without the aid of
other considerations, principally derived from experience of the
values which have been obtained in vessels of similar dimensions
and speed, would render these coefficients of doubtful value as a
measure of efficiency; and, although a coefficient of efficiency is
undoubtedly involved in this quantity, all experience points to the
conclusion that it involves variable elements, and the hypothesis that
it is a constant of one term, is not in accordance with the physical
conditions of the problem, and that this formula requires correction
for ignored and misrepresented elements.
1 See paper
on Steamship Efficiency," by Mr. Robert Mansel, Trans. Inst. Engineers
and Shipbuilders in Scotland, vol. xxii.
33
514
MODERN STEAM PRACTICE,
Obviously, the formula may be written-
CE
= MV 2
V
(1)
in which it is asserted, the true form of C in the first member is
unknown, and the quantities represented by the factors M, and V²
of the second, are, at best, but rudely approximate.
It has been stated by me that a better approximate form for the
factor expressed by M in the Admiralty formula is the quantity
LVM, that is to say, the product of the length of the vessel into the
square root of the immerged midship section; only, to meet a
correction necessitated by the known fact that when uninfluenced
by restricted depth of water, small vessels experience greater pro-
portional resistance than larger ones, and also corroborated by
D'Arcy's exhaustive experiments on the flow of water, in which it
was shown that the diameter of the pipe entered inversely as an
element of the resistance. It was therefore proposed, as a practical
but empirical correction, to take the 8th power of this quantity
instead of its full value, and hence, on this hypothesis, the quantity
b comes to be represented by the approximate value-
b
(L√M)%
C
In which C is a constant involving a number of factors, and corre-
sponds to, but is not the same as the C of the Admiralty formula,
and thus we finally arrive at the following equation-
E
V
(LVM)%
C
·1
log. -¹ a V.
(3)
The factor log. 1 a V of the second number being the notation by
which is expressed, the number whose common logarithm is the pro-
duct of a small quantity, a, into the speed, V knots.
E
V'
The crucial practical test of the accuracy of the speed factor of
the second member, is to apply the formula to the progressive speed
trials of actual steam vessels. For, taking the common logarithms
of both members, and with the speeds taken along an axis as
abscissas, if we set up the values of the first number log. as ordin-
ates; these values will range in a straight line, inclined to the axis
at an angle dependent upon the value of a, and having the ordinate
at the origin equal to the value of the factor log.
C , or, simply,
log. b; whence, by measurement and calculation, or calculation
alone, it is easy to obtain the value of C, which will be found a
(L√M)%
MARINE ENGINES.
515
constant quantity in all the experiments, so long as the conditions of
the trial are unchanged. We thus completely remove the objection-
able variations of coefficient of the Admiralty formula, which, in the
same vessel and circumstances, usually gives a new value of C for
every value of V.
To illustrate the constancy of the derived coefficient, in passing
from vessel to vessel, let us make use of experimental data which,
treated by the Admiralty formula, offer great variations; for ex-
ample, to a few cases of paddle vessels with feathering floats, of
which (except the Paris), having only one experiment, and con-
sequently being unable to determine a, it is assumed that the
value of this is '0796. (Tabular results of experiments are given by
the author.) The problem therefore is, having given the length and
area, power and corresponding speed, of certain paddle vessels, to
calculate from the formula,
E
c = = (L√M) % log.
(L√M)% log. −1 ·0796 V,
the value of C the efficiency coefficient, and to contrast the same
with the values yielded by the formula,
E
C
M V2.
RESULTS OF CALCULATION OF EFFICIENCY OF THE FOLLOWING PADDLE VESSELS.

Name.
Length. Mid. Area. Log. (LM) Power.
Trial
Correspond-
ing Speed.
Efficiency Admiralty
Co-efficient. | Co-efficient.
Shannon,
329
610
3'4212
2928
13.90
160'0
559'5
Paramatta, 329
606
3'4199
2940
13'95
160'9
560'0
Admiral, 211
214
3'0557
744
11.87
159.8
485'7
Paris,
219
177
3'0248
1030
13'41
161'0
400'4
Wolf,
239
220
3'1059
1500
14'19
159'2
391'I
It will be seen that the formula virtually embracing the whole is,
=
(LVM)%
E
V log.
-1 .0796 V.
160*4
The efficiency coefficient 1604 giving as close a result as would be
obtained by the use of three values of the Admiralty formula coeffi-
cient, say 560, 486, and 400. Having thus exhibited the range and
accuracy of the proposed system of comparison with the ordinary
run of merchant vessels, let us now apply them to the valuable data
furnished by Mr. White, so as to compare results."
The author then proceeds to a comparison of various experi-
mental results, and finds that the efficiency coefficient for vessels of
H.M. navy and mercantile marine vary from about 80 to nearly
600, and points out that the conflicting elements which enter into
516
MODERN STEAM PRACTICE.
་
this question, especially when dealing with screw steamers, still de-
mand carefully made experiments for their solution.
Diameter of cylinder.-To find the diameter of the cylinder, the
velocity of the piston in feet per minute must be determined, and
it ranges from 300 feet for short strokes, to 600 feet and upwards.
for strokes of 4 feet 6 inches. The maker is generally allowed to
fix the speed he considers best under the circumstances. To find
the number of square inches per horse-power, divide the constant
33,000 by the product of the speed multiplied by 7, the result gives
the square inches per horse-power; then multiply this by one-half
of the nominal power required, and the result is the area of each
cylinder in square inches. When great exactitude is required, add
one-half of the area of the piston rod, or trunk, if adopted for single
trunks, or the whole area for double trunks; this is necessary, as the
trunks take up a large area in comparison to the piston rod. These
combined areas in either case will give the true area of the cylinder
in square inches, and by a table of areas, which the engineer should
always have by him, the diameter of the cylinder is easily ascer-
tained.
Stroke of piston.- For short strokes giving a large area of piston
per horse-power, a good result will be obtained by dividing the
diameter of the cylinder by 1-76. It is evident, however, that when
high steam pressure is used, much longer strokes can be beneficially
adopted; and by this means we can reduce the weight of the parts
below what is required when the steam is admitted into the cylinder
at a high rate of pressure, as in the combined high and low pressure
cylinder arrangements, now extensively adopted.
Depth of piston and length of cylinder inside.—The depth of
piston is usually one-fifth to one-sixth of the diameter of the cylin-
der, to which add the length of the stroke, making an allowance for
clearance at the ends of ½ inch for small, to 3/4 inch for large pis-
tons, and the product is the length of the cylinder inside, or space
occupied by the steam from the inside of the front end to the inside
of the cover.
Steam and exhaust port in cylinder.-To obtain a free steam
and exhaust, the ports in the cylinder are greatly in excess of the
valve opening-one-nineteenth of the area of the cylinder for the
steam port, and one-eighth for the exhaust port. The latter is
ruled by the distance of the face of the valve from the centre of the
cylinder; and as the exhaust into the condenser is greatly contracted
MARINE ENGINES.
517
in the passage at the side of the port, the exhaust port is made
broad in the direction of the travel of the valve.
Length of ports for double-ported valves. The steam ports in
the cylinder are divided by a centre rib about 1½ inch broad, while
the exhaust port is left free. The combined length of the steam
ports is found by dividing the diameter of the cylinder by 17, to
which add the breadth of the centre rib.
Steam way or opening by valve, lap, &c.-The full opening of
the steam way by valve is found by multiplying the area of the
cylinder in square inches by the speed of the piston in feet per
minute, dividing the product by the constant 10,000; the result
divided by 2 gives the openings for double-ported valves, or four
openings formed with the central ribs. The width of the opening
is of course determined by the length of the ports, and it is an all-
important consideration, as it regulates the supply of the steam into
the cylinder, and consequently the number of strokes or revolutions
of the cranked shaft; and from it the correct lap of the valve is
obtained for cutting off the steam at that part of the stroke which is
arranged for giving the greatest indicated measure of power in con-
junction with the steam pressure that is determined on. The lap of
the valve depends on what part of the stroke of the piston the cut-off
commences, and is explained at p. 122; the length depends on which
class of valve is adopted. The length of doubled-ported valves is
considerable, but the benefit of having a short stroke is obvious, as
the eccentrics are not nearly so large, and all the minor details are
correspondingly reduced. The length of the valve is simply the
sum of the ports and bridges or bars on the cylinder face, to which
must be added the two outside laps.
Steam pipe on valve casing and exhaust pipe.—The steam-pipe
branch on the valve casing is about one-twentieth of the area of
the cylinder; the main steam pipe is two-thirds of the two com-
bined. The exhaust pipe into the condenser is one-twelfth of the
area of the cylinder.
Relief valve for cylinder.—The diameter of the relief valve is
found by dividing the diameter of the cylinder by 12. Smaller
cocks are sometimes fitted on the same valve chest, and worked by
levers, rods, and handles from the starting platform.
Thickness of cylinder.-For ordinary steam pressure ranging up
to 30 lbs. per square inch in the boiler, the thickness of a cylinder
25 inches in diameter is % inch, and for every 5 inches of additional
518
MODERN STEAM PRACTICE,
diameter add inch to the thickness.
1
16
The flanges for the covers
should be one-fourth more than the body; the ends and covers one-
tenth more than the body. The ends and covers should be strongly
ribbed with deep bars cast on, radiating from the centre; the depth
of the covers, including ribs, should be about one-eighth of the
diameter of the cylinder. For additional strength the body of the
cylinder is cast with two or more deep rings, to which are secured
the rings of wood fastened to the lagging with ordinary screw nails.
A manhole is cast in the covers of large cylinders, fitted with a lid;
and the hole for the boring bar on the end of the cylinder is of
sufficient size to inspect the inside of the cylinder, and is also fitted
with a cover which can be easily removed. The thickness of the
sides of the steam chest varies from 3/4 inch for small to 1/4 inch
for large diameters, and is strongly bracketed where required. The
steam ports are divided by a central rib, but the exhaust port is
left free, so that the passage for the waste steam to the condenser
is not interfered with. The exhaust is generally carried round the
cylinder through a broad belt, but this depends entirely on the
arrangement of the pipes leading into the condenser.
Double-ported valve.-The thickness of this valve for small sizes
is 5% inch, ranging to 14 inch for larger sizes; and it is cast with
a centre rib to strengthen it. The diameter of the annular space
for receiving the metallic rings, for taking the pressure of the steam
off the back of the valve, should be as large as convenient; the
depth of the recess in the cover is found by multiplying the breadth
of the rings by 2; the breadth of the rings ranges from 12 to 134
inch, their thickness being about 5% inch for large sizes, to 3/4 inch
or more for extra sizes. The set screws are generally 34 inch in
diameter, fitted with jam nuts and washers. The valve casing is
an open casting varying from 3/4 to 1/4 inch in thickness; the
flanges for bolting it to the cylinder, and for the cover, may be
1/4 inch more than the thickness of the sides. The steam pipe is at
one end, and the steam passage tapering to the extreme end.
Piston rod and stuffing box.-To find the diameter of the piston
rod multiply the area of the piston by the full pressure in the boiler,
to which add the vacuum or 12 lbs. per square inch, and divide the
product by 2240; the quotient gives the area of the rod in square
inches for compressive strain. For tensional strain where cotters
are used, or where the piston is attached to the rod by a nut, divide
by 4000, which gives the sectional area at the bottom of the thread.
MARINE ENGINES.
519
No part of the piston rod, such as the sectional area at the part
where cotters are used, should be made smaller, so that the rod may
safely take the greatest tensional strain imparted by the full steam
pressure plus the vacuum. When two piston rods are used for
return connecting-rod engines, add one-fourth more area; this is
necessary as the vibration of long rods is rather severe at the high
rate of piston speed now adopted. The depth of the stuffing box,
from inside of the cylinder end to the face of the flange, equals the
diameter of the piston rod multiplied by 2; the breadth of the packing
space equals the diameter of the rod divided by 4; and the thickness
of the stuffing-box flange equals the rod divided by 3. When four
or more bolts are used for tightening up the gland, their combined
area is found by dividing the piston rod area by 6.
Slide-valve rod.-To find the sectional area of the slide-valve
rod, multiply the full area of the valve by the full pressure, as for the
piston rod (i.e. steam and vacuum), to which add the weight of the
valve in lbs., and divide the result by 2240; one-sixth of the quo-
tient equals the area of the valve rod in square inches at the weakest
part. Sometimes two rods are adopted, passing over the shaft on
the return principle; in such cases each rod is but little reduced
from the single-rod arrangement. To prevent the rods bending or
springing, guides are fitted at about the middle of their length.
Eccentric strap, rod, and link. The dimensions of the bolts for
the eccentric strap are found by multiplying the total area of the
slide valve by the steam pressure, adding the weight of the valve
in lbs. as for the slide-valve rod, and dividing the result by 4000;
one-sixth of the quotient divided by 2 will give the area of each
bolt at the bottom of the thread. Find from a table of areas the
corresponding diameter, to which add the depth of the two threads,
which will give the full diameter; this may be made a trifle more
to enable the thread or screwed part of the bolt to pass easily
through the hole in the strap. The sectional area of the gun metal
strap where it is bolted together at the lugs should be three times the
area of the bolt at the bottom of the thread, increasing in thickness
all the way round; its breadth equals about twice the diameter of
the bolt. The thickness of the snugs should be one-fourth more than
the thickness of the strap at the lugs. The thickness of the eccen-
tric ring equals one-eighth of the diameter of the shaft, and the metal
round the boss for securing the eccentric to the shaft equals one-
seventh of the diameter. The eccentrics are generally cast open,
520
MODERN STEAM PRACTICE.
with a strengthening rib between the boss and the outside ring.
The pins for the eccentric rods are the same diameter as the slide-
valve rod. The rods are forked at the link end, with a T end for
bolting to the gun-metal eccentric strap; they are made quite flat,
the area at the smallest end equals the area of the slide-valve rod,
and for every foot in length add about ½ inch to the breadth of
the rod. The bolts for the T ends are the same diameter as those
for the strap. The slotted link is generally adopted; the distance
between the centres of the eccentric rods on the link equals three
times the throw of the eccentric. The holes for receiving the pins
are fitted with gun-metal bushes cast hard, and adjusted with set
screws, screwed into the lugs on the link. The sectional area of the
slide-block pin is found by multiplying the slide-valve rod area by
I'3. The pin is conical, and fitted with a tapered ferrule of steel,
which is split, having set screws and nuts on pin for adjusting the
The slide block is of brass, with a loose side flange secured
with screws; the length of the block equals twice the diameter of
the pin. The width of the link should be about one-sixth more
than the diameter of the slide rod; the sectional area equals that
of the slide-block pin. The sliding block or crosshead to which the
pin is secured is generally a flat bar, moving in brass guides, the
crosshead having a lug forged on for taking the slide-valve rod.
The point of suspension on the link is midway between the eccentric
rod pins, on the radius line of the link, a cross bar and pin being
rivetted to the link at that point. The suspension rods are found.
by dividing the valve-rod area by 16, which gives the area of the
pin in square inches; their diameter at ends equals the diameter
of the pin. The suspension rods have brass bushes fitted in the
eyes.
wear.
Power required to move the slide valve.-The power required
to move the slide valve depends on the size of the valve and amount
of pressure on the back of it, to which is added the weight of the
valve in lbs. One-sixth of the total may be considered the force
in lbs. that is required to move the valve when under full pressure
(i.e. steam and vacuum). In practice, for an area of 800 square
inches of valve surface on the back of valve, and when provision is
made with rings on the back to relieve the valve from the steam
pressure, a power of 7 to 1 is allowed; with a steam pressure from
20 to 30 lbs. per square inch, supposing the valve's area was 4000
square inches, more of course would be needed, the area being five
MARINE ENGINES.
521
times as much, or a proportion of 35 to I would be required; that
is to say, the starting wheel would require to make 35 revolutions
for one of the shaft on which the lifting arm for raising and lower-
ing the link is fitted. Of course for small power a valve should be
arranged to take the steam pressure off the back, when the slide
valve is moved by hand, thus lessening the labour in reversing the
gear.
Connecting rod.-The thrust and pull on the connecting rod
receive the full force exerted on the piston, and the same rule holds
good as for the piston rod, namely, 2240 lbs. for compressive stress
and 4000 for tensional strain. This gives the number of square
inches of area for the ends of the rod, an allowance of one-fourth of
an inch in diameter for every foot in length gives the diameter at
the middle. The thickness of caps, when so fitted, is one-half of the
diameter of the rod. The combined sectional area of the bolts at
the bottom of the thread is found by dividing the total pressure on
piston (i.e. steam and vacuum) by 4000. When straps are used,
the combined area at the brasses and key-ways must equal the area
of the rod at end. The breadth of jibs and cotters equals the
diameter of the rod, and the thickness of the key is found by mul-
tiplying the diameter of rod by 31; the thickness of brasses at
ends is found by dividing the diameter of the crank pin by 8, and
for the side one-half will suffice. The brasses are planed out and
lined with white metal, the proportion being for large sizes 114 inch
of brass surface all round with a mid strip left.
Main cranked shaft.-The same rule holds good as regards the
diameter of a shaft with cranks forged on in one piece, and plain
cranks shrunk on a straight shaft. When the cranks of two engines
are placed at right angles to each other, the shaft should have the
same area as a single engine having the same force exerted on the
piston, the length of the crank from centre to centre being identical.
To find the diameter of the shaft, multiply the length of the crank
in inches by the total pressure on the piston (i.e. steam and vacuum),
and divide the sum by 1206; the cube root of the quotient will be
the diameter of the shaft. The collars at the bearings for large
diameters may be I inch. The length of the two outside journals
is generally equal to twice the diameter of the shaft at the journal.
The middle bearing is made longer according to the distance
between the frames for supporting the shaft. The crank pin is the
same diameter as the journal; the distance between the jaws of the
522
MODERN STEAM PRACTICE.
crank is found by multiplying the diameter of the journal by 87;
the thickness of the cranks in the line of the length of shaft is found
by multiplying the diameter by 8, and the breadth equals the
diameter over the collars. All the collars should be made with a
bold radius at the journals, for shafts generally give way at the
sharp corners after long running.
Crosshead and guides.-The diameter of the crosshead for return
connecting-rod engines is found by dividing the total pressure on
the piston by 1400, the quotient is the area in square inches. The
width of each block for taking the upward and downward thrust
of the connecting rod equals the diameter of the crosshead, and the
length is twice the diameter. The blocks are of brass or cast iron
lined with white metal. The depth of the top motion bars or
guides equals three-fourths of the diameter of the crosshead. Some
engineers allow clearance between the blocks and guides at the top,
depending on the weight of the crosshead and adjuncts to neutralize
the thrust; one-eighth of the total pressure on the piston can be
safely taken for calculating the bolts; the motion bar being taken as
a beam loaded at the middle, having a section of an ¤ form, or centre
rib, with flanges at the top and bottom. Of course the thrust varies
according to the angle of inclination; it is less with a long than
with a short rod. From four and a half to five times the radius of
the crank, or the length from the centre of the shaft to the centre
of the crank pin, is about the average length for the connecting
rod.
Main frame.—The main framing is subjected to direct tensional
and compressive strains, and to a certain extent also to twisting
stress. As the cohesive strength of cast iron is less than that of
wrought iron in the ratio of one of wrought iron to three of cast iron,
the combined sectional area of the framing should not be less than
three times the area of the piston rods; but when we consider that
the framing forms the backbone of the structure, and may be sub-
jected to tensional, compressive, and twisting strain at one and the
same time, more area is required. When of an I section, the centre
web varies from 7% inch for small to 134 and 2 inches for heavy
engines; the flanges for bolting down to the keelson, cylinder, and
condenser, one-fourth more than the centre web; and all the other
flanges one-eighth less than the centre web. The breadth of frame
equals the diameter of the shaft at the journals. The depth of the
top limb for bolting to the cylinder equals the diameter of the
MARINE ENGINES.
523
shaft, and that of the bottom one at the cylinder is one-fourth less
in depth; the limb for bolting to the condenser may be made a
little more than one-half of the diameter of the shaft. The various
forms of framing have been already noticed. The thickness of the
brasses at the bottom is one-seventh of the diameter of the journal.
The caps when of wrought iron are one-third of the diameter of
the journal, and when of cast iron one-half. The combined area
of the cap bolts is found by multiplying the combined area of the
cylinders by the total pressure of the piston, as for the piston rods,
&c., dividing the result by 4000. The brasses are recessed about
1/4 inch in depth, and filled in with white metal, the brass surface
being about 1½ inch all round for large shafts, with a bottom strip
running lengthways.
Piston. The piston has generally a depth of from one-fifth to
one-sixth of the diameter of the cylinder. The packing ring should
not be less than one-ninth of the diameter of the cylinder; its
greatest thickness one-fifth of its breadth, diminishing to the part
where it is cut through. The rubbing surfaces of the junk and
bottom rings can be made of about the same collective breadth as
the packing ring, with projections formed on the junk ring and
bottom of piston projecting from their respective thicknesses; this
tends to make the wear of the spring ring and piston more equal.
The ends of the piston may be somewhat less in thickness than the
cylinder; they are strongly ribbed, and have all the necessary bosses
cast for the piston rods. The bolts for the junk ring vary from
34 to 14 inch in diameter, according to the size; in some cases
they are merely tapped into the cast iron, in others nuts are inserted
in the body of the piston. The spring ring is kept up to the
cylinder face with flat or U-shaped springs, recessed into the body
of the piston. Two pieces of cast iron are inserted between the
packing ring and the piston, which serve to keep the body and
packing ring central with each other; the pitch of these blocks is
about one-fifth of the circumference of the ring inside. (See p. 403.)
Air pump, condenser, &c.—The capacity of the air pump equals
one-eleventh part of the cubic contents of the cylinder for double
action, and double of that quantity for single action; the length of
the stroke being the same as for the steam cylinder. Thus the
area of the cylinder is divided by 11 or 5'5, as the case may be, to
obtain the area of the air pump. The lining of the air pump varies
from 2 to 3/4 inch in thickness. The depth of the air pump piston
524
MODERN STEAM PRACTICE.
equals one-fourth of the diameter of the pump; the diameter of
the air-pump rod equals the diameter of the pump divided by 7.
The area of the foot-valve passages in the condenser equals the full
area of the pump, but for the head-valve passages more is allowed,
which is found by multiplying the area of the pump by 1.35; this
result is only for one end. The area through the gratings for the
foot valves should not be less than the pump area multiplied by '61,
and for the head valves '83 is the multiplier. Of course more area
in the passages and gratings may be allowed, as a large area reduces
the lift of the valves, and renders the wear and tear of the india
rubber less severe. The valve seats are secured to the condenser
by 3/4-inch stud bolts and nuts of Muntz metal. The capacity of
the condenser is generally about 13 times that of the capacity of
one cylinder, when a condenser is fitted to each, placed side by side.
When the condenser is on the opposite side in relation to the
cranked shaft, the capacity can be reduced, as the eduction pipe
then forms a part of the condenser, and increases the total cubical
contents. The area of the main discharge pipe equals the area of
the air pump, or one-half the area for each. The thickness of the
condenser varies from 3/4 to 1/4 inch; all the flat surfaces should
be strengthened with ribs in the casting. There should be an air
vessel formed in the casting, placed above the head valves, so as to
lessen the shock of the ejected water. The diameter of the snifting
valve varies from 2% to 4 inches, and it should be placed as low
down as possible, so that all the air, water, &c., may be ejected in
the act of blowing through.
Injection valve, &c.--To find the area of the injection pipe,
multiply the cubic contents of the cylinder in feet by '4, which
gives the area in square inches for each condenser; the bilge injec-
tion may be less than this. The former should be placed as high
up and the latter as low down as possible in the condenser.
Surface condensation.-The surface of the tubes, according to
Hall, should have about 2800 square inches for the condensation of
60,000 cubic inches per minute, the quantity of cold water required
being about 10 gallons. Some makers give about the same sq. feet
of condensing surface as there are sq. feet of heating surface in the
boilers (see p. 432). Of course, the pressure of the steam as it
enters the condenser is the point to study in considering the amount
of surface required; a very general rule is to multiply the total heat-
ing surface in the boiler by 75, which gives the number of sq. feet
MARINE ENGINES.
525
of condensing surface. The air pump for the surface system may
be less than for the injection system, ranging from one-twelfth to
one-fifteenth of the cubical contents of the cylinder; it is, however,
often made of the same capacity as the injection system, in the
event of that system being adopted, in case of accident to the
surface condenser.
Feed pump.-The number of cubic inches of water required for
the boilers varies of course according to the evaporation of water
in the boilers. To find the water required, multiply the cubic
contents in feet of steam for one cylinder for an entire revolution
by the cubic inches of water required for the steam used, that is
the quantity required to be boiled off, and the result will give the
cubical contents of the feed pump of the single-acting type. This
result is only for one cylinder, and generally double the contents.
is allowed, so that in the event of one of the pumps getting out of
order the other one will be able to keep up the supply. The area
of the water passages in the grating, if india rubber valves are used,
is found by the same rule as for the air pumps; for brass valves,
divide the pump's diameter by 13, which gives the diameter of the
valve. For the sake of uniformity, the bilge pump is the same size
as the feed pump.
Screw propeller.-The screw's disc, or the circle represented by
the diameter of the screw, should have an area of about 1 foot for
every 2.75 square feet of midship area or immersed section; while
the actual area of the blades may be put down at about 1 square
foot for every 7 to 10 square feet in the midship section. The
thickness of the roots of the blades for cast iron is found by multi-
plying the diameter of the screw by 55, this tapering to 14 inch
at the point on the average. When the screw is made of gun-metal
multiply the diameter by 44, which gives the thickness at the root,
and all the other parts in proportion. To find the pitch of the
screw, multiply 6080, the lineal feet in a knot or nautical mile, by
the speed in knots per hour that is required, dividing the result by
the number of revolutions of the screw multiplied by 60 minutes,
and the quotient will give the pitch of the screw as it were working
in a solid nut. A certain amount, however, must be allowed for
slip. Deduct that amount from 100, which we will name the divisor,
then multiply the pitch as already found by 100, and divide that
quantity by the divisor: hence the formula—
100-slip pitch as found: 100: actual pitch.
526
MODERN STEAM PRACTICE.
Angles on
Sides of
Wedge Box.
Thickness
of Feather
in Boss.
Thickness
at Point of
Blade.
Thickness
at Root.
Width at
Point of
Blade.
Width of
Blade at
widest part.
Widest part
of Blade
above Boss.
Thickness
of Cutter,
Width of
Main Cutter.
Metal
between
Flange and
top of Cutter.
Metal round
Shank.
Diameter of
Shank of
Blade.
Thickness
of Flange
of Blade.
Diameter of
Flange of
Blade.
Length of
Boss.
TABLE OF THE PROPORTIONS OF GRIFFITH'S SCREW PROPELLER.
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commence at centre of blade.



Diameter
of Boss.

Diameter
of Screw.
Screw aperture.—The length
-The length of the screw aperture for a mer-
chant ship depends in a great measure on the configuration of the
screw propeller. Dividing the diameter of the screw by 25 gives
ample room for the generality of propellers at present in use.
Screw shafting and thrust collars, pillow blocks, &c.—The pro-
peller shaft should have the same diameter as the cranked shaft.
The taper of the part for the screw boss should be about 1/4 inch
MARINE ENGINES.
527
for every 2 feet in length, the mode of fastening being a nut on the
end, with feather let into the shaft and boss. To find the area and
diameter of the lying shafting, divide the area of the cranked shaft
at the journals by 1'13, the quotient gives the area in square inches;
and by a table of areas the diameter is easily found, always allowing
over rather than under, and even dimensions being preferred. The
thickness of the solid discs forged on the shaft is about one-third
the diameter of the shaft. A projection of 34 inch, and about
five-eighths of the diameter of the rest of the shaft, is left on, and
accurately fits into a recess bored out in the adjoining shaft, keeping
the shafts central the one with the other; the combined area of the
bolts for the coupling is found by multiplying the area of the shaft
by 35. A key is sometimes sunk into one of the discs and secured
with screws, one-half of the key taking each disc; thus the shearing
strain is taken off the bolts, which can therefore be greatly reduced
in area.
The thrust of the screw is received on a series of collars
accurately turned on the shaft. The combined area of the thrust
surface is found by multiplying the nominal horse-power of the
engine by 125, which gives the number of square inches of surface
in the whole series of collars, the length and depth of the collars
being one-eighth of the diameter of the shaft. The length of the
pillow blocks for the lying shaft is one and a half times the diameter
of the shaft. The length of the plate for the thrust block is about
six times the diameter of the shaft; it is well joggled at the ends
to prevent lateral movement.
Hand gear. The rods must either be unnecessarily large in
diameter, or supported at the middle; the required strength very
rarely exceeds I inch in diameter. The joint pin is of the same
diameter as the ends of the rod, the diameter of the eye equals the
diameter of the pin multiplied by 2, and the depth of the eye equals
the diameter of the pin. This rule is for single joints, which should
always be used when convenient, because they are more easily
made; when double joints are used, the distance between the jaw
of the joint equals the pin's diameter, while one-half of the diameter
equals the thickness at the smallest part. Sometimes hollow rods
are adopted with advantage.
Bolts in cylinder cover.-The bolts vary in size from 5% to 14
inch in diameter; the pitch from centre to centre of the holes is
generally about eight diameters. To find the combined area of
the bolts, multiply the area of the cylinder by the steam pressure,
528
MODERN STEAM PRACTICE.
divide the product by 2240, and then by the number of bolts
required, which gives the area of each bolt at the bottom of the
thread; adding the depth of the threads will give the full diameter
of the bolt.
Turning gear.—The arrangement is generally a worm, working
in a wheel fitted to the end of the cranked shaft, the diameter of
the wheel being about 334 times the radius of the main crank, the
pitch of the teeth being 2½ inches. The diameter of the worm
equals one-sixth of the diameter of the wheel.
Safety valve, waste-steam pipe, &c.-For every square foot of
fire-grate surface, allow 5 of a square inch, this multiplied by
the nominal horse-power gives the total area of the valves; then
dividing by the number of boilers gives the area of one valve for
each. Two safety valves are, however, better than one; and it
would appear that one-half of the area is required for each, but the
practice is to give two valves of the combined circumference of the
large one, on the ground that no more steam can escape with a
certain lift than the circumference of the valve will admit of. If
there were four boilers, of course there would be eight valves: the
main waste-steam pipe for these will be eight times the area of one
valve, or the combined area of all the valves; while the branch
pipes will be reduced in size according to the arrangement of the
valve chests. (See "Report on Safety Valves,” at p. 462.)
16
Copper steam pipes.-The steam pipes, blow-off, bilge, and waste-
water pipes, as used in the royal navy, are not less than 1/4 inch in
thickness; feed and injection pipes inch, and waste-steam pipes
% inch in thickness. The diameters of the pipes depends on the
arrangement of the boilers, &c.: when four boilers are used, for
instance, the stop valves and branch pipes are one-fourth of the
area of the main steam pipe. The blow-off pipes are generally
about 3 inches in diameter. The main feed pipe should equal the
diameter of the feed pump, when plungers are used of the same
stroke as the steam piston; but when the pump is situated a long
way from the boilers, more may be adopted. The branch pipe and
non-return valve on the boiler is generally about 2½ inches in
diameter.
Kingston valves, blow-off and injection cocks. --The following
table gives the number and diameters generally adopted, but of
course these are regulated entirely by the arrangement of the
piping:
MARINE ENGINES.
529

Injection Stop
Cocks.
Horse-
Kingston.
power.
Blow-off Stop
Cocks.
Kingston.
No.
inches.
No. inches. No. inches.
No. inches.
60
I
3½
2
3
I
5
2
32
80
I
3
2
3
Ι
5
2
32
100
I
4
I
4
I
4
I
4
150
I
32
I
I
3/2
2
32
200
2
4
2
4
2
4
2
4
300
2
4
4
3
2
5
2
5
Flanges for copper pipes.—
Diameter of pipe
in inches
1½
2
233+
22
5
5%
Diameter of flange
in inches.
Diameter of pipe
in inches.
4
7/2
8
-∞ ∞
Diameter of flange
in inches.
II
11/2
82
12
6
9
1234
32
634
9%
1314
4
7/2
ΙΟ
1334
4/2
8
10½
1414
5
82
II
1434
5½
9
11½
154
6
9½
12
1594
62
13
12½
163%
7
10%
13
17
Sometimes for large diameters a raised ring is cast along with the
flange for bolting the pipes together, to which the copper pipe may
be securely rivetted; in other cases they are simply brazed on,
having a raised bead left on the flange to give a better hold.
34
LOCOMOTIVE ENGINES.
In this form of the steam engine, which has now advanced to a
high degree of perfection, the agency of steam is employed in the
simplest form in which it is capable of producing power, namely,
by the mere excess of its pressure above that of the atmosphere.
The reason why the more economical process of condensation is
inapplicable in this case is obviously the increase of weight and
complexity attending the use of that process, both of which should
be avoided as much as possible in a machine which propels its own
weight at an immense velocity over a road composed of yielding
materials, all more or less liable to wear and tear from the effects of
momentum and friction. The qualifications for a perfect locomotive
are not easily reconcilable with each other, and demand the utmost
skill, combined with long experience, on the part of the maker.
We have said that lightness and simplicity of parts are desirable;
but these, on the other hand, must not interfere with the safety and
the economical working of the engine. Its stability must be
insured by the position of the wheels and the centre of gravity; and
every available means must be adopted for increasing, first, the
evaporative power of the boiler, and secondly, the mechanical effect
of the steam, without unduly increasing the weight and cost of the
apparatus. It is evident that any increase in the economical work-
ing of the locomotive effects a twofold saving, namely, in the cost
of the fuel and in the weight to be carried. Hence the steam is
worked at a very high pressure (about 150 lbs. above the atmos-
phere), and is cut off and expanded in the cylinder.
It is well understood that railways owe their origin to the
necessities of the trade in coal, and that the improvement of the
engine followed gradually upon the improvement on the road on
which it was constructed to run. Among the names most con-
spicuous for the introduction and improvement of the locomotive
engine stand those of James Watt and his assistant William Mur-
doch, Richard Trevethick, Mr. Blenkinsop of Leeds, the brothers
Chapman, Timothy Hackworth, and George Stephenson.
LOCOMOTIVE ENGINES.
531
Under this section we shall first treat of the Locomotive proper
and its Tender, as used on railways; and then notice various forms
of Engines used for traction or haulage of machinery and road
traffic, Portable Engines employed for driving agricultural ma-
chinery, Steam Rollers for roads, &c.
COMBUSTION IN THE LOCOMOTIVE.
THE STEAM BLAST-FIRE-BOX AND COMBUSTION CHAMBER.
D
E
E
The successful development of the locomotive engine has been
mainly due to the introduction of the steam blast, or an application
of part of the motive power for effecting a rapid and intense com-
bustion of the fuel in the fire box of the boiler. This is produced
by blowing the waste steam from the cylinders into the chimney,
thus causing a partial vacuum, which is filled up by the air rushing
through the fire box, carrying the flame and heated gases through.
the small tubes placed in the body of the boiler. By this means
the water is exposed to a number of highly-heated surfaces; the
thinness of these tubes adding greatly to their effectiveness in pro-
ducing steam. The fire.
box, however, is un-
doubtedly that part of
the boiler where the
water is boiled more
quickly, more especially
at the top. This is due
to the material of which
it is composed—namely,
copper- being a very
good conductor, keep-
ing quite free from in-
crustation, and the con-
centrated and intense
vertical heat, caused by
a due admixture of the oxygen of the atmosphere, forced in a
measure amongst the live fuel. The practical limit to be arrived
at is, that the blast must not be too powerful, so as to lift and
carry off the fuel through the tubes, and then up the chimney

B
Fig. 379.-Diagram showing the Mechanical Action of
the Blast.
A, Fire box. B, Tubes. c, Smoke box. D, Chimney.
EE, Sides of chimney. F, Blast pipe.
C
532
MODERN STEAM PRACTICE.
to waste the power of the blast that is required depending greatly
on the quality of the fuel.
A
B
The mechanical action of the blast is very simple. The waste
steam from the cylinders is led into a pipe concentric with the
chimney. The end of the pipe should be quite
straight, so that the expanding steam may strike
equally on the sides of the chimney, as at EE;
and it is of the greatest importance that the
pipe should be placed exactly in the centre of
the chimney. It is evident that when the steam
is led through bent pipes, placed on each side of
the smoke box, that the blast is imperfect, owing
to the steam striking alternately on the sides of
the chimney. So it becomes imperative that the
blast pipe should be made quite straight at the
end; thus the expanding steam strikes equally
all round the chimney, producing a much better
result. The blast pipe should taper from the
Fig. 380.—Disadvantage of under side upwards, and should be suddenly
contracted at the orifice. Sometimes various
sizes of nozzle or top pieces are provided; they
are generally made of copper, and secured to the cast-iron pipe with
a set screw. It is likewise preferable to braze a ring of brass on
the top, and turn it out correctly to size, thus providing

A,
A
Bent Blast Pipes.
Blast pipes. B, Chimney.
a smooth and accurate aperture for the escape of the
steam.
A
a
When the engine is not in motion a separate plug
valve is used, which is fitted inside of the chimney with
a pipe connection, communicating with the boiler. By
this means the fire can be urged by simply blowing
steam up the chimney directly from the boiler, inde-
pendently of the blast pipe. Of course this separate
valve is only used as a means of creating a circuit Fig. 381.-Form
when the engine is not in motion, or in the act of of Blast Orifice.
raising steam quickly when the fire is kindled, a few
pounds of steam pressure in the boiler being neces-
sary, which is not considered as wasted when used for this pur-
pose.
A, Blast orifice.
a, Enlarged view
In order to still further increase the combustion of the fuel in
the fire box when the engine is in motion, various mechanical
LOCOMOTIVE ENGINES.
533
contrivances have been tried, and none with better results than
independent steam jets fitted to the fire box, forcibly inducting air
by steam pressure amongst the incandescent fuel. With this object
in view, the front and back or sides of the fire box are fitted with a
row of tubes, placed at a convenient height above the fire bars. A
steam pipe is fitted at the front, side, and back of the fire box,
having a nozzle connected with each hollow stay or tube, the
apertures being inch in diameter. A vertical pipe is fitted to
this steam pipe, running to the top of the outside of the fire box,
having a plug tap for regulating the supply of the steam. It has
been proved by experiment that this contrivance greatly prevents
smoke nuisance when coal alone is used, and effects a material
saving in fuel. A much simpler plan, however, has been success-
fully adopted in coal-burning engines fitted with the ordinary fire
box: it consists of a plate, easily removed, fitted to the aperture
or fire door, and which is inclined downwards. By this means the
current of air entering by the fire-door aperture passes downwards,
instead of taking the direct course through the tubes,-thus meeting
the flame and heated gases, and providing the necessary oxygen to
effect complete combustion.
The ordinary fire box of the locomotive-engine boiler has been
modified in various ways to effect a thorough combustion of the
fuel, and likewise to prevent smoke nuisance when coal is used.
All of the following schemes depend more or less on a free admis-
sion of air, with or without the use of a separate combustion cham-
ber, in connection with the ordinary fire box. In land-engine
boilers the air is admitted beyond the fuel, through apertures formed
in the bridge at the back of the fire bars. Mostly all the mechani-
cal contrivances introduced in the locomotive boiler aim at attain-
ing the above objects by similar methods, namely, dividing the fire
box by means of water spaces, formed of the same material as the
fire box, to which latter air is admitted as in the ordinary land
boiler.
The first example we will notice has two sets of fire bars laid at
an inclination, having over them a hanging bridge, provided with
an air pipe at the top. This plan was introduced for burning coal
in combination with coke; the large grate was for the coal, and
the small one, or fore grate, for the coke. Coal alone was charged
on the hind grate, and coke on the fore grate, the design being to
deflect the flame and heated gases by the hanging bridge over the
534
MODERN STEAM PRACTICE.
incandescent coke, thereby consuming the smoke and gases. By
H
G
D
A
B
F
I
C
B
E
Fig. 382.-Combined Coke and Coal Fire Box, tried on the
Liverpool and Manchester Railway.
A, Fire box.
BB,
ގ
Fire bars. c, Hanging bridge. D, Air pipe.
E, Body of boiler, showing tubes. F, Manhole. G, Furnace door.
the arrangement of in-
clined bars the coal gra-
vitated, or was more
easily pushed forward,
to make room for fresh
charges. This is quite
correct in principle, as
the dead coal should
always be pushed gra-
dually forward, and when
this is properly attended
to, smoke is greatly pre-
vented in all furnaces.
The proportion of fuel
used on the Liverpool
and Manchester Railway
was two-thirds coal and
one-third coke.

Another example on the same railway has been tried, giving
T
F
A
Ꮐ
D
B
C
E
G
Fig. 383.-Fire Box, arranged for Coal Burning, with Combustion
Chamber. Liverpool and Manchester Railway.
favourable results, the
fire box being ar-
ranged for burning
coal. In connection
with the ordinary fire
box a second combus-
tion chamber was in-
troduced, which was
divided from the fire
box by a vertical water
partition, containing a
number of short tubes
for the passage of the
flame and gases. Air
was admitted into the
combustion chamber

A, Fire box. B, Combustion chamber. c, Perforated pipe. D, De- through vertical per-
flecting plate. E, Body of boiler, showing tubes. F, Manhole.
GG, Dampers.
H, Furnace door.
forated pipes carried
up from the bottom.
A deflecting plate was likewise fitted to the combustion chamber,
LOCOMOTIVE ENGINES.
535
thus delaying, as it were, the passage of the gases through the tubes
in the body of the boiler, and which we believe gave very favour-
able results. Of course it is essential that the bottom of the com-
bustion chamber should be perfectly air tight, means being adopted
for regulating the supply of air into the chamber up the vertical
tubes.
A
BRAZZA
ZIN BICHID
Various other arrangements were tried on different railways,
amongst these step grates, designed so as to admit a plentiful
supply of air through the grate (Fig. 384). When the bars are
stepped, or laid on an inclination, the fireman arranges the fire so
that the live coal is al-
ways at the foot of the
incline, while the dead
or fresh fuel is at the
top, near the fire door;
thus the gases evolved
pass over the incan-
descent fuel, and with
a due admixture of air
are more readily con-
sumed. This plan
works very well with
free open coal, but with
bituminous coal clinker
forms, stopping up the
space between the fire
bars, and consequently
burns them very soon. In some arrangements of step grates a
movable grate is placed at the foot of the stepped bars, which can
be readily opened for the removal of clinker and ashes.

D
DRURIKIA
Fig. 384.-Step Grate.
A, Fire box. B, Step grate. c, Movable grate with lever
and balance weight. D, Damper.
Another plan (Fig. 385) was tried, providing a much larger area
of fire grate, burning the fuel more slowly, and giving a plentiful
supply of air through the grate, and through hollow stays on the
front and sides of the fire box, the fire box being divided up the
middle by a water space, and carried inside of the barrel of the
boiler to a considerable extent. By this means a large top surface
was obtained, with the advantage of having a combustion chamber
at the back, common to both furnaces. This plan, by careful alter-
nate firing, no doubt tended greatly to consume the smoke of
itself. A curtain plate has in some instances been added with
536
MODERN STEAM PRACTICE.

F
A
J
E
11
B
1
11
C
D
Fig. 385.-Long Fire Box. Longitudinal and Transverse Sections.
Fire box. B, Combustion chamber. c, Tubes in the body of boiler. n, Smoke box and chimney. E, Manhole. F, Furnace door
A.
A
LOCOMOTIVE ENGINES.
537
advantage, which receives the full charge of air from the open door-
way, the air being distributed through a number of small holes in
the front of the curtain plate.
Other methods have been tried to effect complete combustion.
One method (Fig. 386) consists of a small fire box placed at the
back of an ordinary fire box; this plan is introduced for burning
coal and coke, the latter being placed in the large fire box. The
coal being consumed in the auxiliary fire box, the smoke and gases

D
E
B
F
C
E
A
Fig. 386.—Auxiliary Fire Box. A, Small fire box. B, Fire box. c, Fire tile. D, Body of boiler
showing tubes. EE, Dampers. F, Furnace door.
evolved pass through small short tubes into the main fire box, and
are caused to make an upward direction through the interposition
of a fire tile, thus passing over the entire length of the incandescent
fuel in the main box before entering the small tubes in the body of
the boiler.
Another method was designed to burn coal alone. The fire
grate, as in a previous example, is large, and is divided by an
inclined water space into two compartments, having a separate
door, fire grate, ash pan, and damper for each; the largest grate
being at the back, near the foot plate. The flame and gases from
this fire box rise, and, being met by a fine current of air entering
538
MODERN STEAM PRACTICE.

J
G
I
B
F
F
A
A A, Fire boxes.
A
H
C
ZZA
H
D
5107-
E
..
་་
་་
Fig. 387.-Fire Box and Combustion Chamber, fitted with Fire-brick Tiles. Longitudinal and Transverse Sections.
B B, Water spaces. C,
Arch of brickwork. D, Combustion chamber. E, Tubes. FF, Furnace doors. G, Manhole. Hн, Dampers.
LOCOMOTIVE ENGINES.
539
the perforated fire door, pass through a perforated arch of brick-
work into the front chamber. In the second grate the coal is
burned slowly, the combustion being regulated by a careful admis-
sion of air through the damper. This arrangement also includes
a second combustion chamber fitted inside of the body of the boiler,
in which are placed perforated fire bricks at a convenient distance
from the tubes in the body of the boiler. These fire-brick tiles
receive and retain a portion of the heat when the fire is quite clear,
and give off a portion of the retained heat when the fire is green,
thus acting as equalizers of temperature. In some instances the
combustion chambers have no fire bricks placed inside, the flame.
and gases from the fire box simply passing through short tubes
forming the division between the fire box and combustion chamber,
the latter being divided by a vertical water space. A door is fitted
underneath the combustion chamber for cleaning and repairs.
Inclined bars have also been used, in combination with a curved
diaphragm plate, fitted with tubes and a transverse water tube, the

B
D
E
C
E
Fig. 388.—Inclined Fire Grate. A, Curved diagram in the fire box. B, Water tube. c, Tubes
in the body of boiler. D, Furnace door. EE, Dampers.
latter deflecting the flame and gases (Fig. 388). The gases having
free passage through the tubes in the diaphragm, mix with the
fresh air admitted. This plan does not seem to have met the
540
MODERN STEAM PRACTICE.
designer's wish, owing, we have no doubt, to the excessive cooling
surface, and the restriction and obstruction of the top of the main
fire box, where the vertical heat is most beneficially utilized in the
production of steam.
Another example of inclined bars, which differs materially from
the foregoing, and which has been successfully carried out, may be
noted. The fire box is divided by a longitudinal water space forming
two separate fire boxes, uniting in one at the tube plate (Fig. 389).
By this means the fires can be worked alternately, that is to say,

D
B
C
Fig. 389.-Inclined Grate, with Long Run. A, Fire box. B, Combustion chamber.
c, Tubes in the body of boiler. D, Furnace door.
when the one fire is bright the other is provided with fresh fuel,
which slides forward on the incandescent fuel. The smoke and
gases passing over the bright flame, and likewise meeting the flame
from the adjacent furnace, are by this means effectually consumed;
and it will be seen that the top surface of the fire box is better
adapted for the production of steam than that of the foregoing
example. There is a fire-brick lump introduced at the bottom of
the inclined bars, which acts as an equalizer by giving off its heat
during the act of firing, and adds to the efficiency of the boiler.
Indeed, many examples of boilers of all descriptions have been
found to be greatly improved by the introduction of these fire
bricks.
LOCOMOTIVE ENGINES.
541
F
じ
​In another arrangement, with the view oí giving greater length
to the run of the flame in the
fire box, a transverse water par-
tition, and in some instances a
fire-brick arch, was introduced,
secured to the tube plate below
the tubes, and inclining up-
wards towards the furnace door
(Fig. 390). By this means the
flame and gases are retained for
a longer period in the fire box;
and to assist combustion air is
admitted through stay tubes
in the front of the fire box,
as well as through small holes
in the fire door.

G
A
B
E
D
Another plan having thesame
object in view has been tried, in
which the main difference con-
sists in the fire-brick arch being
made shorter than in the pre-
vious example. Some consider this an advantage, as the vertical
Fig. 390.-Fire Box fitted with Transverse Partition.
A, Fire box. B, Fire-brick arch. c, Tubes in the body
of boiler. D, Air stay tubes. E, Damper. F, Man-
hole. G, Furnace door.


E
B
有
​A, Fire box.
D
A
C
Fig. 391.—Tubular Stays, with Slide. Transverse and Longitudinal Sections.
B, Fire-brick arch. c, Tubes in the body of boiler. D, Air stay tubes. E, Furnace door.
542
MODERN STEAM PRACTICE.
flame acts on the crown of the fire box more beneficially. In
F
F
O
7:0″-
C
C
C
D
H
A
D
A
B
A
UUUUU
Fig. 392.-Long Fire Box, fitted with Inclined Deflectors. Longitudinal and Transverse Sections.
E, Furnace door.
F F, Holes of manhole and dome.
A, Fire box. B, Fire-brick bridge. ccc, Water spaces. D, Tubes in the body of boiler.
all these examples having stay
tubes placed in the wall of the
fire box, it is necessary to fit
sliding bars so as to regulate
the supply of air necessary to
effect complete combustion
with the different kinds of
coal used, or to admit more
or less air as may be re-
quired with the same kind of
coal, owing to atmospherical
changes.
In some railways a long
elliptical fire box has been
adopted (Fig. 392), having a
fire-brick bridge at the back
similar to the Cornish boiler,
through which air is admitted
by a number of apertures.
There are also hanging water
spaces fitted to the crown
of the fire box for deflecting
and mixing the gases, thus
detaining the flame in its
passage to the tubes placed in
the body of the boiler. Stay
tubes are likewise placed in
these hanging bridges, which
greatly strengthen them, be-
sides affording free passage
for the flame and gases, and
which seem fully to meet the
views of the designer.
Another plan has merely a
long elliptical fire box, having
a diaphragm of fire brick
placed at the back of the fire
bars, the flame passing through



suitable openings left in the diaphragm. This plan has the advan-
LOCOMOTIVE ENGINES.
543

J
G
F
A
B
C
E
D
Fig. 393-Long Fire Box and Combustion Chamber. End View and Longitudinal Section.
A, Fire box. B, Diaphragm of brick. c, Combustion chamber. D, Tubes in the body of boiler. E, Damper for admitting air into the
combustion chamber. F, Furnace door. G, Manhole.
544
MODERN STEAM PRACTICE.
tage of a separate combustion chamber, to which air is admitted
through a damper placed at the bottom of the diaphragm.
Steam-inducted currents of air have been successfully adopted
for the prevention of smoke, the air being forced through stay tubes
placed on the side walls of the fire box, eight of these hollow
stays being placed on one side and seven on the opposite side.
B
A
B
B
B
Fig. 394.-Steam-inducted Currents of Air.
A, Fire box. B, Steam pipe and jets. cc, Tubes.
By this arrangement the currents
of air (proceeding from these stay
tubes) do not interfere with each
other, as would be the case were
the tubes placed exactly opposite
each other, when the current of
the one impinges against the cur-
rent of the other, whereas in the
arrangement shown the current
passes across the whole width of
the fire box. The air can be
inducted into the fire box at an
angle by merely inclining the stay
tubes, and the arrangement is
fitted with steam pipes and noz-
zles, or small jets, as has been
already described. This plan has
many advantages, the principal
of which are, the easy mode of
regulating the supply of air to
suit the requirements, and that
there are no mechanical difficul-
ties in keeping the apparatus in
efficient working order.
Steam highly superheated has
been blown over and through the coal in the fire box for the sup-
pression of smoke, and when this plan is carried out properly it has
been attended with success so far as the smoke is rendered nearly
invisible; but there can be no doubt that unless the steam is highly
heated, in combination with fine rapid streams of air passing through
the fire door, that the mere fact of blowing raw steam over or
through the fuel damps the fire, and consequently retards com-
bustion, rendering it both more expensive in fuel for the production
of steam, and keeping such apparatus in efficient working order.


LOCOMOTIVE ENGINES.
545
It is evident that in all the foregoing examples the main
thing that has been studied is the utilization of the smoke and
gases in the production of steam, by a due admixture of air passing
into or inducted into the furnace or combustion chamber. It must
be borne in mind, however, that a little smoke may issue at the
top of the chimney with the most perfect arrangements, when the
engine is not working; but when the engine is in motion, the vapour,
erroneously termed steam, issuing from the blast pipe, completely
annihilates the smoke. This is easily explained: the vapour when
seen is of a snowy whiteness, and we all know that a little dirty
water can be made much clearer with a copious admixture of pure
water; the same with the smoke. It gets mixed up in the chimney
with the vapour from the blast pipe, and the latter absorbs the
smoke and becomes more or less coloured with the sooty particles.
Smoke nuisance at railway stations is of more importance to get
rid of. This is accomplished by turning on the blow pipe placed
in the chimney, the primary use of which is to urge the fire while
the engine is not working, supplying oxygen, so necessary for
combustion, by forming a partial vacuum in the chimney as already
described.
It is allowed by all that careful firing is the chief practical diffi-
culty to attend to in effecting the complete combustion of the gases
and the prevention of smoke. The fuel should be supplied at short
intervals, in small quantities, equally distributed. With inclined
grates the fuel is laid on near the fire door, and is fed on the grate
per se by gravitation; thus the stoker's duty is comparatively easy
compared with the ordinary kind of fire grate lying quite flat. In
fact, with inclined bars the continuous forward motion of the fuel
keeps the fire grate always covered, and is the nearest approach to
continuous firing with travelling fire grates, without the incon-
venience of such mechanical contrivances,-not at all to be desired
in the locomotive engine, although for other purposes moving fire
grates answer admirably.
It is of primary importance that the fire box of a locomotive-
engine boiler should be so constructed as to allow of a copious
supply of air above the fuel for the combustion of the gases, and
that the air should freely mix with the gases to give the greatest
effect. To attain this object, length of fire box, breaking up of
the flames by the interposition of fire tiles, fire-brick arches, baffle
plates, and other similar contrivances, are effectual, all tending to
35
546
MODERN STEAM PRACTICE.
delay or lengthen the run of the flame and gases in the fire box
before entering the tubes in the body of the boiler. It must be
likewise borne in mind that the air should be admitted at a high
temperature to attain the greatest measure of economy; this has
been effected in a variety of ways. Some have placed an air
chamber in the smoke box, in connection with tubes carried along
to the fire box; by this means the air is heated before passing into
the combustion chamber. Others have placed tubes, carried from
the front of the smoke box through the water space in the boiler;
thus the air is partially heated before entering the fire box. This
plan slightly tends to reduce the temperature of the water in the
boiler, and consequently the steam pressure. Auxiliary furnaces
for heating the air, as likewise fire-brick tiles placed in the com-
bustion chamber, have been carried out with a measure of success.
A hot-air blast, promoted by the steam blast in the chimney,
is far more economical, and tends more to effect the complete
combustion of the smoke and gases, than simply admitting currents
of cold air, however finely they may be spread over the surface
of the incandescent fuel where the heat is the greatest. With
air inducted by steam jets the air is partially heated in its passage
through the short tubes placed in the walls of the fire box;
and there can be little doubt that if the steam was superheated
before passing through the jets a greater measure of economy
would be the result. The tubes to carry out this plan may be
2 inches in diameter, and their combined area should give 4 inches
of tube area to every square foot of fire grate, which of course can
be reduced or regulated according to the requirements by means of
the sliding bars, worked by hand from the engine platform. This
plan of steam-inducted currents of air is simply a number of
miniature nozzled steam blast pipes, similar in action to the main
steam blast placed in the chimney; the action of the one is almost.
identical with the action of the other, each having the power of
inducting the air into the fire box. The former, however, forces
the air in currents of more or less intensity across the fire box, as
may be required. Thus it is thoroughly mixed with the gases
immediately where it is wanted; and it is remarked that where the
fuel lies in the line of these currents it is scooped or grooved out—
a convincing proof that the admission of air freely above the fuel,
or even partially through it, is the one effectual way to cause
complete combustion.
LOCOMOTIVĖ ENGINES.
547
The practical working of the apparatus now claims our attention.
When a sufficient area of tubes is provided it is not necessary,
under ordinary circumstances, to turn on the steam jets while the
engine is running, as a sufficient quantity of air will be drawn into
the fire box through the tubes by the action of the main steam
blast placed in the chimney; but when the vapour issuing from
the chimney appears dense, it is evident that the combustion of
the smoke and gases is not perfect in the fire box, and the steam
inductor can then be turned on with advantage. In the same way,
when approaching stations, and the steam is turned off the engine,
combustion receives a check owing to the blast having ceased, and
although the fire is burning with great intensity, smoke may issue
at the chimney, which can be prevented by turning on the steam-
inducting current, thus providing the necessary oxygen for con-
suming the smoke in the fire box.
The problem for effectually utilizing coal in the locomotive-boiler
furnace carrying out complete combustion, so far as practicable—
is thus solved by the free admixture of heated air with the smoke
and combustible gases, the air being inducted into the fire box at
or near the surface of the fuel.
THE BRITISH LOCOMOTIVE.
CONSTRUCTION OF THE BOILER AND BOILER MOUNTINGS.
In the practical construction of the locomotive boiler the fire
box is of the first importance. Its outside shell is made of iron,
and the inside shell or fire box proper of copper, or in some in-
stances of iron. The fire box proper is surrounded with a water
space, communicating freely with the other internal water spaces
in the boiler. The union between the fire box and the outside
shell at the bottom is effected by means of a wrought-iron frame of
a square section. This frame is drilled with holes to correspond
with the rivet holes in the plates, all of which are rivetted together
and made perfectly steam tight by caulking the edges of the plates.
Sometimes a U or other section formed of boiler plate is adopted,
as the long rivets which must be used with the solid form are liable
to leak. The flat sides of the fire box and outside shell, being
548
MODERN STEAM PRACTICE.
7/2
E
+
LL
08
8 %
}
exposed to the full boiler pressure, are not of sufficient strength to
resist the stress; and as the strain is in opposite directions, screwed
stays are introduced, binding the inside and outside shells together.
These stays are generally made of copper, and are pitched closely
together; after being screwed hard into the holes tapped for their
K
9- t

29%
13347
ΤΟΣ
Centre Line
B
Copper N:14W G
2/0.2
Fig. 395.-The Boiler.
ว
F, Furnace door.
H, Steam pipe.
A, Fire box. B, Body of boiler. c, Smoke box. D, Chimney. E, Steam dome.
G, Damper.
reception, their ends are rivetted over, thus materially increasing
their holding power. They are screwed for their entire length;
when so made it necessarily takes a long time to screw them into
the plates. The stays are sometimes turned down at the middle.
(Fig. 397), making their diameter smaller in the middle than
at the ends, and so dispensing with the thread except at each end,
G
LOCOMOTIVE ENGINES.
549
and giving elasticity to the stay. This to a slight extent may be
advisable, but it should be borne in mind that the middle part must



A
A
B
C
Fig. 396.—Plate of
B
A
A
C
A
a U form for the
bottom of Fire
Box.
D
D
A, Fire-box plate.
B, Outside fire-box
plate. c, U piece.
D
Fig. 397.-Fire-box Stays.
D
A A, Plates. B, Parallel stay. c, Curved stay. D D, Screwed parts.
be of sufficient strength to resist the direct pressure, and we
believe that the elasticity of stays in narrow water spaces is but of
little moment. The unequal expansion of the fire box, however,
over that of the outside shell must throw a greater bending stress on
the top stays than those at the bottom; the ends of the stays,
therefore, to meet the strains imposed, should be of larger diameter
than the middle of the stay, and the extra cost of their manufacture
is balanced by the ease and less time taken to screw them into the
plates. Of course the direct cohesive strength of all stays subjected
to tension is measured by the diameter of the stay at the bottom of
the thread, and when the threads are turned off to the diameter at
the middle of the stay, the cohesive strength remains the same,
while the elasticity is greatly improved. The top of the fire box
must necessarily be strengthened with a very different form of
stays, as it would not be convenient to connect it to the top of the
outside shell in the same manner as the sides, although in some
instances long screwed stays have been tapped through the top of
the outside fire box and the crown of the inside one. Therefore
the top is prevented from collapsing by means of solid bars of
wrought iron, placed on edge along the top of the fire box, with
projections forged on for resting on the edges of the plates
forming the fire box. The bearing surfaces, in some instances,
are merely the breadth of the bar iron; but as the power to
resist compression in copper is very low, about 3 tons per square
inch, it is obvious that the bearing surfaces should be made of
sufficient area to meet the requirements. These bars have bosses
550
MODERN STEAM PRACTICE.

2
MAN REGJURI
A. Fire box.
14.0"
ZETONOVELLAMAALAGA ARENGUINS,
B
D
JI
E
E
G
1
F
E
LL
4.3%
A
T
CAD
Fig. 398.-Boiler, showing Stays. Longitudinal Section and Plan.
E E, Longitudinal stays. F, Stays between front and back of the outside shell of fire box.
B, Body of boiler. c, Hole for dome. D, Manhole. EE, Longitudinal stays.
G, Beam stays on the top of fire box.
LOCOMOTIVE ENGINES.
55I
forged on at short intervals, which are bored for the reception of
stay bolts passing through the top of the fire box, deep washers


C
B
Figs. 399, 400.—Stays for top of Fire Box.
A, Plate stay. B, Stay forged solid. c c, Palms.
being interposed between the plate and bottom of the bars, while
in some projections are left on the forging. By this means the
top plate of the fire box is drawn tightly up against the bottom of
the beams or stay bars, and a bearing is secured at short intervals
along the entire length of the stays. By this arrangement the
strain on the plate is not too great, otherwise the plate would be
drawn up, which these washers effectually prevent, and a free cir-
culation of the water under the stays is effected, preventing the
plate being injured by the intense heat. Sometimes palms are
forged on for rivetting to the outside shell of the fire box and body
of the boiler.
In some examples the stays are made of wrought-iron plates
rivetted together, and indented where the bolts pass through. As
a means of staying the top of the outside shell, vertical bars are
introduced, secured to the beams on the top of the fire box by a
joint and pin taking a lug forged on the beams, while the top end
is secured to a T iron bar rivetted to the shell, the pin for the joint
passing through the mid feather of the T iron. Longitudinal stays
secure the smoke-box tube plate and the outside shell of the fire
box, as shown in Fig. 398.
The next detail in connection with the fire box is the junction
of the apertures cut out in both of the shells to form the fire door-
way. This was formerly effected by means of a solid bar of iron
around the opening, which is generally elliptical, securely rivetted
between the inside and outside plates. This plan necessarily en-
tailed very long rivets, and sometimes gave great trouble owing to
leakage. To obviate that objection, as likewise to obtain a free
552
MODERN STEAM PRACTICE.
water space at that part of the fire box, the junction between the
shells has been improved by the introduction of a distance piece
formed of plate iron, flanged for rivetting to the inside box, while
an angle iron is worked all round the mouth-piece on the outside,
being properly rivetted to it and to the outside shell. To form


B
B
A
D
C
C
1
Fig. 401.-Fire-door Opening.
A, Inside plate of fire box. B, Outside plate of
shell of fire box. c, Furnace doorway.
Fig. 402.-Fire-door Opening.
A, Inside plate of fire box. B, Outside plate of shell
of fire box. c, Furnace doorway. D, U piece.
the openings for flues between the fire box and combustion chamber,
where such a chamber exists, the distance pieces between the fire
box and the combustion chamber must be of a U section, of plate
iron, interposed between the plates of the fire box and chamber, as
in Fig. 402, so that they may be in contact all round with the water,
otherwise the intense heat of the fire box or chamber would burn
such portions of the distance pieces as were not thus protected.
The fire door is made of plate iron, hinged to the outside shell of
the fire box, and is provided with a latch for shutting it close.
There is a baffle plate fitted inside, which is kept apart from the
door with ferrules and rivets, forming an air space, thus protecting
the door from the intense heat of the furnace.
The next constructive detail with reference to the fire box is the
manner of securing better work and facility for cleansing at the
bottom corners. With this object part of the outside shell is cut
LOCOMOTIVE ENGINES.
553
out at the corners, and a thicker forged plate worked on, having a
raised boss with tapped hole for the reception of a sludge screwed
plug, which would be otherwise difficult to adjust.
There can
be no doubt that these sludge taps placed at each corner give great
facility for cleansing these contracted water spaces from deposit by
means of a water hose.
On the top of the outside shell a short branch piece is worked,
made of plate iron, flanged for rivetting to the shell, and fitted with
an angle iron at the top. This aperture in the shell is to allow the
steam to enter the steam dome or receiver when so fitted, or for
the reception of the plate on which the safety valves are placed.
This plate also forms the manhole door, and can be taken off to
admit of inspecting the inside of the boiler. In working the plates
of the outside shell, the front and back ones are flanged for taking
the top and side plates; the flanged corners should have bold
curves, and should not be worked square, as that form greatly
distorts the fibre of the iron, and consequently weakens the strength
of the plate. Of course all these flanged plates must be drilled, or
punched by a hand machine termed a bear. All the rivetting up
should be executed between the outside and inside fire boxes, before
the holes are drilled through both shells for the reception of the
screwed stays already referred to.
The
It is necessary to fit an ash pan underneath the fire bars.
use of this pan is chiefly to prevent the cinders and live coal
from falling on the line, more especially on viaducts which have a
flooring of timber, as in some cases bridges have caught fire from
the live coal falling from the fire grate. This ash pan is secured to
the outside shell, and is fitted with a damper for regulating the
supply of air to the furnace when the engine is running, or for
shutting off the supply when the engine is standing, as may be
required. In some instances dampers are fitted to the front and
back, more especially in countries subjected to great falls of snow.
This is very desirable when engines are run tender-first for a
considerable journey, in which case the front damper can be shut,
and the back one opened, for, with much snow on the line, if the
front damper was not closed the ash pan would get choked with
the snow. In this case the hind damper admits the air under-
neath the fire grate, but it of course cannot act so beneficially in
promoting a rush of air underneath the grate as the front damper.
With the engine running at a high speed the pressure of the air
554
MODERN STEAM PRACTICE.
against the moving surface provides a powerful blast, which, with
the front damper open, affords a very effectual means for supplying
air to the fire grate.
The fire bars of the locomotive boiler are formed of wrought iron
of a thin deep section, and are supported by a wrought-iron frame,
which should be fitted with hinges or otherwise, so that it can be
dropped easily for the removal of clinker.
The shell of the boiler is of a cylindrical form; a ring of angle
iron is worked on at each end for rivetting it to the outside shell
of the fire box and front tube plate respectively. In some cases the
plates of the outside shell of the fire box are flanged, to which the
shell of the boiler is rivetted, thus
dispensing with the angle - iron
ring.

A
B
C
The longitudinal joints of the
shell are usually double rivetted,
and the circumferential joints single
rivetted; but others have single
rivetting for the longitudinal and
circumferential laps. The rivets are
3/4 inch in diameter, pitch 2 inches,
for plates from 3% to 1½ inch,
while for thinner plates the pitch
is 134 inches, and for rivets 1 inch
the pitch is 15% inch. The holes.
are all punched, and in punching
they assume a conical form; the
small ends being placed together,
the rivet when properly filling the
hole becomes a double cone, which
greatly strengthens the rivetting
and stiffens the joints-converging the line of strain through the
plates. The rivet holes are sometimes countersunk, and when the
rivets are made accordingly the strength is greatly increased, for
should the head be destroyed by corrosion the countersink will
hold good. As the joints in single rivetting are liable to twist,
the plates are sometimes spread out, getting the line of strain more
directly through the line of plating.


Figs. 403, 404, 405.—Rivets.
A, Rivet hole formed conical in the act of
punching. B, Countersunk holes. c, Joint
spread out.
There can be no doubt that the longitudinal seams ought to be
much stronger than the transverse ones. To attain this object
LOCOMOTIVE ENGINES.
555
the plates are made to butt together, and fitted with strip iron
double rivetted, thus having four rows of rivets. A small piece is
worked on the ends of the strips in the inside, making them very
strong at that part, and much more easily caulked. The double-
rivetted welt joint, made of Lowmoor plate, is capable of bearing a
strain of nearly 9000 lbs. per square inch of sectional area, and as
the longitudinal seams have to bear a stress of about double the
other seams, the double-rivetted longitudinal joints are nearly equal
in strength to the other joints single rivetted, and in practice may
be taken at equal value.
The plates for the shell are all planed on the edges, and are
slightly bevelled for setting up, the caulking making them quite

A
A
Fig. 406.-Lap Joint.
A A, Exaggerated effect of caulking.
flat. Great care must be taken in this operation, as undoubtedly
the caulking has a tendency to buckle the plates, thus weakening
the joints. Scarf-welded joints have been successfully introduced.
The plates are planed on the surface to fit each other, and are then
A


B
Fig. 407.-Scarf-welded Joint.
A, Scarf plates apart. B, Scarf complete.
heated on both sides, and hammered as in ordinary welds, very
little hammering being required. When the work is properly
executed, this is no doubt the strongest way of uniting boiler
plates; moreover, the reduction of weight and the non-liability
to leakage is greatly in favour of this plan in its application to
shells or other boilers.
The steam chest is a short round barrel, placed at the centre of
the top of shell or at the front near the chimney, and in some
556
MODERN STEAM PRACTICE.
A
A
for jointing to the turned angle-iron surface on the steam chest,
the two flanges being bolted together, and these can be readily dis-
jointed, forming a manhole for inspecting the inside of the boiler,
When the steam chest is placed on the shell an angle iron is worked
on it at the bottom, and securely rivetted to it and the shell; on
the top of the steam chest a cast-iron plate, on which are the safety
valves, is fitted. This can be taken off at pleasure for inspecting
the stop valve and other parts of the boiler. In such an arrange-
ment it is usual to fit a manhole door on the top of the fire box, on
which the steam whistles may be placed.
DE-
Faja
C
E
F
JI
C
E
A
+12+
D
B
instances on the top of the outside fire box. A short piece is
flanged and rivetted to the top of the fire box; on the top of this
piece an angle iron is worked, which is turned on the top surface



F
B.
ט
Fig. 408.-General Arrangement of Boilers, showing the position of the Fire Box, Tubes, Smoke Box,
Steam Chest, and Steam Pipes inside the Boiler.
A, Fire box.
B, Tubes.
c, Smoke box.
D, Steam dome.
E, Regulator. F, Steam pipe.



LOCOMOTIVE ENGINES.
557
On all the parts of the shell where the check-valve boxes for the
feed pipes are fitted, forged plates having raised bosses are securely
rivetted to the shell. By this means the joints for the check-valve
boxes are made on turned surfaces, instead of fitting the flanges to
the curved plates of the shell-a plan which secures good joints,
and greatly facilitates the jointing and disjointing of all the valve
boxes, plug taps, &c.
inches in diameter and from
a thickness of from 9 to 14
The arrangement of the tubes
The brass tubes are generally 2
10 feet to 12 feet in length, with
wire gauge, or nearly ½ inch thick.
is of the highest importance. Sufficient room should be given for


A
B
Fig. 409.-Arrangement of Tubes.
A,
Free circulation at sides.
B B,
Contracted at sides.
B
the free circulation of the water. It is obvious that with a large
water space between the tubes and the side of the shell of the
boiler, the water has a better circulation than when the tubes are
packed too closely; and that small water spaces between the tubes,
in combination with a mass of tubes, tends greatly to decrease the
evaporative power of the heating surface, as delineated in the circle
having the largest number of tubes. The holes in the front plate of
the fire box, and tube plate in the front of the shell, being all set out
accurately, arranged zigzag or triangular and not above one another,
as in marine boilers, having water spaces between from ½ inch or
5% to I inch, are then drilled for the reception of the tubes. These
are driven tightly in, and then expanded with a tool for the purpose;
the ends are then rivetted over, making them perfectly steam tight.
They are rendered secure by driving in wrought-iron ferrules at the
fire-box end, while every six or so of the tubes at the front end
are likewise ferruled; but some are not so, giving free passage for
the soot and small cinders. Thus the tubes, being firmly held at
the ends, act as stays, tending to prevent the tube plates being
forced outwards by the pressure of the steam. However, long
tie stays must be placed above the tubes, running the entire length
558
MODERN STEAM PRACTICE.
of the boiler, between the back plate of the fire box and the tube
plate in front of the shell. Gusset stays are sometimes applied in
the angles of the fire-box shell, uniting the flat plates with the
cylindrical portion of the boiler; thus the through tie bars may be
dispensed with-those gusset plates being likewise fitted to the
tube plate in the front of the shell.
The smoke box is usually made cylindrical. It is formed of
1/4-inch plate iron, rivetted to the flanged tube plate on the
D
C
.2%
B
B
3/4 bolts
shell, this plate being carried
down for securing the back
flanges of the cylinders. The
front plate of the smoke.
box may be flanged, or an
angle iron worked at the
corner for rivetting to the
shell of the smoke box.
The door for the smoke
box should be of sufficient
diameter to admit of the
tubes being angled with the
holes drilled for their recep-
tion; the hole in the plate
is turned out with a slight
bevel, and the door is accur-
ately turned to fit, an angle
iron being worked inside to
stiffen the plate, and prevent
it buckling with the heat;
an inside plate is likewise
fitted to the door for its protection. The door is secured in its
place with generally three sliding bolts, jointed to a central disc
plate, worked by a handle placed outside of the door, the door being
hinged to the end plate of the smoke box, with one long bolt taking
both of the hinge plates and studs secured to the smoke box.

E
A
310".
Fig. 410.-Smoke-box Door.
A, Smoke-box door. в B, Hinge plates. C,
B c, Handle.
D DD, Sliding bolts. E,
E, Inside plate.
The chimney is usually made single, but at times an inside tube
is introduced to prevent condensation and preserve the full force of
the blast. The tube generally tapers from the bottom upwards;
thus the steam from the blast pipe expands in its upward course,
consequently the vapour and smoke issuing from the top are not of
such density as at the orifice of the blast pipe, where the chimney
LOCOMOTIVE ENGINES.
559
is contracted. The inside of the smoke pipe should be quite plain;
the rivet heads should be countersunk into the plate covering the
joints, so that there will not be any obstruction to the passage of
the steam and smoke. The outside covering can of course be
rivetted in the usual manner; it is secured to the top of the smoke
box by a short flanged plate rivetted to the chimney, and bolted
to the smoke-box shell. At one time the top of the chimney was
ornamented with a finely curved cap made of copper, which was
kept bright, while others were formed of a wrought-iron plate, and
as such presented a very neat appearance; but as the top of the
chimney, when properly formed, stimulates the draught passing
through the fire box
when the engine is run-
ning fast, it is of import-
ance to form the top
with this object chiefly
in view; and we cer-
tainly consider the
plain top, cut quite hori-
zontally, is the best form
that can be adopted,


A
B
C
Figs. 411, 412, 413.-Chimney Tops.
A, Curved top. B, Plain top. c, Curved top with part bevelled off.
slicing the air, as it were, cleanly, while with the curved form the air
impinging against the top is thrown downwards. Some have
bevelled the top backwards to facilitate the escape of the vapour and
smoke, and assist the draught, never taking into consideration that
when so formed, with the engine running backwards, a downward
current of air passes into the chimney, tending to impede the
draught; moreover, a strong side wind must necessarily affect the
draught with such a form.
The ash pan is made of plate iron 14 inch in thickness, framed
with angle iron, having a band of flat iron at the top. The depth
should be at least from 9 to 10 inches, so as to hold a large
quantity of ashes, giving a sufficient air space above the ashes for
the admission of air underneath the furnace bars. It should fit
closely to the bottom of the fire box, otherwise the draught will be
impaired. The ash pan is sometimes fitted with dampers at the
front and back, as already explained, the damper being a flat plate
hinged at the top, and closing accurately the aperture when shut.
It is fitted with a lever and rod, by which it is opened or shut from
the platform; and can be used either to stop the draught by shutting
560
MODERN STEAM PRACTICE.
it completely, or nicely to adjust the quantity of air required under-
neath the grate. It is generally bolted or rivetted to the fire box
with straps for that purpose, and sometimes a small door is fitted
at the bottom to allow the ashes to fall down, thus conveniently
clearing the ash pan. A disc damper should be placed at the crown
of the smoke box to damp the fire effectually at that end. Venetian
dampers have been successfully applied, covering the ends of the
tubes in the smoke box, while some are contented with placing a
plate on the top of the chimney, which must be removed before
starting the engine. Undoubtedly the locomotive boiler furnace
should be damped at both ends when required, which is practically
carried into effect with the damper on the ash pan, and otherwise
in the smoke box or chimney.
The fire bars are of wrought iron from 5% to 14 inch in thickness;
the latter size is thinned at the bottom edge to about one-half of the
thickness. The general thickness adopted is from 5% to 34 inch,
with equal air spaces between them; this thickness being found best
in practice, as the bars are not so liable to twist, being more easily
kept cool. They should not be thinned when of this thickness,
but merely chamfered on the lower edge for the free admission of
air. For bars of 3 feet long and under, the depth varies from
3 to 4½ inches; when of greater length they must be made in two
lengths, or supported at the middle with a cross bar. The bars are
cut and flattened at the end, with raised pieces forged on the sides,
so that they may be kept apart the necessary width for the admission
of air. The frame on which the bars rest is made of wrought iron,
I by 1½ inch deep, fitted all round the bottom of the fire box quite
close up to the rivet heads, and is held up with studs rivetted to
the fire box. Some place angle iron for supporting the bars,
which is rivetted to the fire box, and notched for the bars, by
this means keeping them apart without any forged projections on
the bars. When the bars are not put in one by one it is preferable
to hinge the whole grate, so that they may be dropped down entire,
as sometimes a few of the bars may be choked up with clinker or
impure matter from the fuel, and consequently if only a few were
hinged there might be a difficulty in dropping them.
We give a very good plan adapted for a double fire grate (Fig. 414).
The frames for holding the bars are slightly inclined, and rest on
projections rivetted to the fire box, and at the bottom end projections
are forged on the frames, which rest on projections forged on a bar
LOCOMOTIVE ENGINES.
561

B
C
C
A
D
E
E
D
Fig. 414.-Arrangement for Lowering the Fire Bars.
A, Fire box. B, Foot plate. c, Fire bars. D, Handle, rod, lever, &c. E, Ash pan.
36
562
MODERN STEAM PRACTICE.
running across the bottom of the fire box. This bar is made to slide
in suitable hanging pieces rivetted to the fire box, and at one end
there is a bell-crank lever having a rod and handle passing up to
the foot plate. When the bars require to be dropped the handle
is pulled up, and the pin on the end of the bar having been removed
it is drawn past the projections, and then the frames and bars fall
down. In this arrangement there are no hinges, and consequently
less liability to derangement.
The brackets for supporting the boiler from the frame are gene-
rally made of plate and angle iron; at the smoke-box end and
body of the boiler, these brackets are rivetted to the frame, but at
the fire-box end the boiler is free to expand, sliding as it were
on the frame, yet firmly held thereto with bolts and nuts. The
bracket on the body of the boiler should not be made too rigid,
otherwise a severe strain would be thrown on the framing. The
plate bracket should be of a certain elasticity, to yield to the
expansion and contraction of the boiler. Unless this is provided
for, rupture may take place in the seams of the boiler. Sometimes
the boiler merely rests on this bracket, without being rivetted.
The brackets for the smoke-box end are simply extensions of the
tube and front plate, stiffened with angle iron, when the arrange-
ment of the machinery will admit of this; and in some there is
simply an angle iron rivetted to the smoke box, which is carried
down square at the sides, with an inverted angle iron rivetted to
the frame, and the two secured with bolts and nuts. The bracket
for the body of the boiler is of plate iron, secured to the under side
of the boiler and to the main framing; while for the fire box some
provision must be made for the expansion and contraction of the
boiler.
To prevent radiation and condensation of the steam in the boiler
it is covered with a non-conducting material, consisting of felt
wrapped round in several plies, having wood-lagging over all, con-
sisting of pine battens grooved and tongued, and secured to wooden
rings which are fastened to the boiler with screws; over the lagging
is placed sheet iron, which is banded at the transverse joints with
hoops of the same material, to which lugs are rivetted at the ends,
which are bored out and tapped for the tightening-up screw, thus
holding the felt and covering boards firmly in position, the parts.
lagged being the body of the boiler, the top and sides of the
outside shell of the fire box, and the dome.
LOCOMOTIVE ENGINES.
563
The steam pipe inside of the boiler is made of copper about
% inch in thickness, having brass flanges soldered thereto for
making the joints, the flanges being sometimes grooved and filletted.
The pipe is held up with straps rivetted to the crown of the boiler
where necessary, and in most locomotives is carried up inside of the
dome, with the object of getting the steam made as dry as possible;
while with some arrangements there is no dome, the steam pipe
traversing the entire length of the boiler, the pipe having a number
of slits cut out in it. By this means the steam is taken into the
pipe immediately over the parts where it is generated; thus drier
steam is obtained. However, the general practice is to provide
a steam dome, having the pipe carried to the top, on which is fitted
the regulators, made of brass. Circular-disc regulators have been
adopted, rotating on a centre pin: this plan is
not much in use, as the surface wears un-
equally, the circumference of the disc plate
having a greater travel than the centre, con-
sequently more wear must occur at the edges.
Flat gridiron valves sliding over ports are
very generally adopted, fitted to the top of the
steam pipe inside of the dome, or placed directly
on the cylinders in the smoke box; the former
position is to be preferred, as with the latter
there is a constant pressure of the steam in
the pipes in the smoke box, tending to leak-
age. The fewer joints to keep tight in so
complicated a machine as the locomotive engine
the better. An improvement on the former

B
A
·7"
B
51
H
A, Chest for valve. B, Grid-
iron valve.
plan consists in placing the regulator in a cast- Fig. 415.-Gridiron Regulator.
iron box, bolted to the tube plate on the end
of the steam pipe. By this means, when the
engine is standing or the valve closed, the pipes in the smoke box are
relieved from the pressure; the rod for working the valve passes
through the inside pipe, and is actuated by a lever directly, the rod
being provided with a stuffing box fitted to the back plate of the shell
of the fire box. There is no steam dome in this example, and the
pipe is slotted with a number of apertures for taking away the steam
immediately over the parts where it is generated. However, the ar-
rangement suits equally well when a steam dome is fitted, having a
pipe at right angles for taking the steam from the top of the dome.
564
MODERN STEAM PRACTICE.
When the engine is standing, or the valve shut, the pipe is not sub-
jected to pressure, the only part subjected to pressure being the cast-
iron box. Double-beat valves have been arranged in a similar way to
the foregoing, having a screwed spindle for opening the valve, which
is actuated by a lever, handle and rod; the latter passes through
the centre of the steam pipe, and has a boss forged on it, which
has a square hole. This receives a square part on
the spindle, sliding freely thereon; thus by turning
the handle the valves are opened and shut by the
screw cut at the end of the valve spindle. Another
method for direct-action regulators has a brass

F
E
T
circular box bolted to the back
of the fire-box shell, having a
circular cylindrical valve with a
conical seat at the end. The
handle for actuating the valve
works in a spiral segment; the
handle being turned presses
against the side of the spiral
D
}
A

B
A, Valve chest.
Fig. 416.-Double-beat Valve Regulator.
B, Double-beat valve. c, Screw on the spindle.
F, Regulator handle.
D, Rod.
E, Stuffing box.
segment, thus pushing the valve firmly against the seat; and on
being turned the other way the handle bears on the opposite side
of the segment, thereby opening the valve. With this arrange-
ment the inside steam pipe is subjected to the steam pressure,
tending to collapse it, that is to say, when the valve is shut.
Double-beat valves arranged vertically are very generally used
LOCOMOTIVE ENGINES.
565
for the regulator; a strong cast-iron pipe is fitted to the steam
pipe, at the top of which a
short piece is bolted for the
seating, and is firmly held
in position with a strap, fitted
to some convenient part of
the boiler; the pipe having
an expansion joint with stuf-
fing box and gland at the
bottom, for taking the hori-
zontal copper pipe passing
along to the cylinders; thus
it can freely expand and con-
tract without straining it.
The valve has a jointed rod
passing downwards to a le-
ver, which is keyed on the
shaft which passes through
the stuffing box on the end
plate of the fire-box shell,
the other end being sup-
ported with a boss cast on
the vertical pipe, and which
is bored out for its recep-
tion, a plain handle with
quadrant and set screw or
pin, for holding the valve up,
being placed at the outer end
of the shaft.

16
The steam pipes in the
smoke box when made of
copper are about inch in
thickness; this is to allow
for the wear by the action
of the cinders. Sometimes
cast-iron pipes are substi-
tuted, and should be at least
5% inch in thickness, but
copper pipes are preferable,
Б
E
IL
O
AB
F
HA
B
D
"
V
Fig. 417.-Circular Regulator.
c, Rod.
D, Stuffing box.
E, Regulator handle.
F, Spiral segment.
G, Steam pipe.
A, Valve box.
B, Circular valve.
as the cast iron is liable to deteriorate from corrosion. As the
566
MODERN STEAM PRACTICE.
steam pipes in the smoke box are made of a bent form, it is not
necessary to provide any expansion joints; they are simply bolted
to a cast-iron branch fitted to the end of the tube plate, while at
the bottom end they are bolted to flanges cast on the cylinder
branch pieces.
B
44...
1/8 Copper
The blast pipe is generally made of cast iron, although sometimes
copper is used.
It tapers in a gradual manner from the bottom
upwards. The best arrangement for inside
cylinders is one central pipe taking both of
the cylinders; it is usual to make the nozzle
of copper, which is secured to the top of
the cast-iron pipe with set screws. The
blast orifice should be quite smooth and
true; sometimes a brass ring is brazed on
the copper piece, or in some a flange is se-
cured to the top of the pipe, and which is


·3*3½
A
C
B
C

10
314
A
·6·
Fig. 418.-Blast Pipe.
A, Blast pipe. B, Copper nozzle.
Fig. 419.-Blast-pipe Orifice.
A, Blast pipe. B, Flange. c, Hole bored out.
accurately bored out, so that there is a true and smooth surface for
the exit of the steam. It is of the utmost importance that the
blast orifice should be exactly in the centre of the chimney, blowing
the waste steam in a true vertical line; otherwise, should the waste
steam be blown against one side of the chimney it tends to impair
the exhaust, or partial vacuum, formed in the smoke box, and con-
sequently the draught through the boiler is slightly affected.
With outside-cylinder arrangements there is a blast pipe fitted
to each cylinder, meeting a branch piece at the top, which should
be quite straight for a short length vertically, otherwise the waste
LOCOMOTIVE ENGINES.
567
steam from the bent pipes, curved to the sides of the smoke box,
will strike alternately on each side of the chimney, thus tending to
impair the draught through the fire grate and tubes placed in the
body of the boiler. In modern practice the blast orifice is a con-
siderable distance from the crown of the smoke box, just above the
top row of tubes: this has been found, with a wide spreading
funnel, or even with the usual taper, to create a superior draught
with a wider blast orifice, and is now commonly adopted.
There are generally two safety valves provided, placed on the top
of the steam dome, or on the manhole door situated on the top of
D
37%....
3%

12
+
E
8
B
A
2"
·2'2...
.894
374
D
C
898...
3%
35...
4screw


A, Dome. B, Cast-iron top for dome.
Fig. 420.-Safety Valves.
c, Safety valves and seats. D, Lever. E, Stud for lever.
the fire-box shell. In the latter case a third valve may be fitted on
the top of the steam dome on the boiler, which is loaded directly
by means of a spiral spring placed on the top of the valve, having
two screwed columns or long stud bolts and nuts, taking a cross
bar which is placed on the top of the spring, and then screwed
down with the nuts until a certain and constant pressure on the
563
MODERN STEAM PRACTICE.
valves is obtained to resist the internal steam pressure. The other
safety valves are fitted with a lever and spring, which can be
regulated with a thumb screw to any pressure within range of the
Salter balance fitted with a helical spring, graduated to indicate
I lb., 5 lbs., &c., intervals of pressure; the spring is so adjusted
that a weight of 1 lb. attached to the balance would move the index
to 1 lb. as marked by the scale, the lever being so proportioned to suit
the area of the valve that a pressure of 1 lb. indicated by the scale
gives 1 lb. per square inch on the valve. The valves formerly much
used were conical spindle ones, with the bearing surface bevelled to an
Fig. 421.
C
A
B
angle of 30°. Some makers round the point
of contact on the valve, and although they
are not so liable to gag in locomotive prac-
tice owing to their being frequently opened,
still they are objectionable, as they do not
Safety Valve with point give so free a passage for the steam as the
flat-disc valve or the spherical one. The
former has been arranged in a variety of
ways; one good form being an inverted cone with a flange at
the base which bears on the seating, the two surfaces being accur-
ately turned, and then ground together to make them perfectly
steam tight, the thrust pin on the lever bearing on the internal
of contact rounded.—A,Valve seat.
B, Valve. c c, Part rounded.
D
B
A
C
Fig. 422.—Annular Safety Valve.
A, Valve.
B, Seat for valve. c, Spindle.
E, Stud for lever.
E
D. Lever.
apex of the cone, the valve
being cast hollow for that pur-
The annular flat-sur-
pose.
face valve (Fig. 422) differs
materially from the ordinary
ones and from the foregoing,
inasmuch as the steam, be-
sides escaping round the valve
when raised, escapes also
through an annular aperture
cast in the valve, thus posses-

sing the advantage of two edges, instead of one edge as in the ordinary
disc valves, for the steam to escape by, and consequently with a given
diameter, and the lift of the valves of both kinds being equal, the
annular valve will pass about double the quantity of steam, while
the area exposed to the steam pressure in the boiler being much
less, the holding-down load is reduced in proportion. The spindle
is hollowed out for the reception of the thrust pin, as in the previous
LOCOMOTIVE ENGINES.
569
C
A
example, and in both examples the valves are frictionless in the
act of lifting, which is the main thing to be studied in safety-valve
arrangements. To carry this more fully into effect the ball safety
valve has been designed, fitted
with a lever and spring balance.
All the bearings are of the ball-
and-socket description; thus free-
dom of action is secured, while
the tendency to corrode or stick
is rendered nil. The ball is gen-
erally cast in gun metal, and the
seating of brass. This valve has
the advantage that the ball may
be turned into any position to
suit the wear.

Various forms of direct spring-
B
loaded valves have been success- Fig. 423.-Ball Safety Valve with Lever and Balance.
fully adopted; one form consist-
ing of a large plate 12 inches in
A, Ball valve. B, Seat for valve. c, Lever.
D
D, Stud. E, Salter spring balance.
F
D
E
E
diameter, loaded with a number of volute springs, arranged uni-
formly around the centre of the valve, the bearing surface of the
springs resting in cups on the valve,
while the large flat surface at the
top bearing on the covering plate
renders the action quite true, and
as there are no spindles connected
to the outside springs there is no
liability to jam. So large a valve
is not really required for the loco-
motive boiler; but the principle
can be carried out with one small
valve having a central volute
spring.

A
B
plate. D D, Screw studs for adjusting the springs.
F, Lever. G, Spindle.
Although there may be a differ- Fig. 424.—Safety Valve directly loaded with Springs.
ence of opinion as to the propor- A, Plate valve. B, Seat for valve. c, Covering
tion which the working pressure EE, Volute springs.
of a boiler should bear to its ab-
solute strength, it will doubtless be admitted that the greater the cer-
tainty of a safety valve opening at the required pressure, and the
greater its range of lift under a given excess of pressure, the less will
570
MODERN STEAM PRACTICE.
be the excess of strength required. If a perfect safety valve could be
made—that is, one which will absolutely prevent the boiler to which
it was applied from being subjected to a higher pressure than that
to which the valve was adjusted-it would of course be conducive

Y.....
D
2.
·Z
A
D
Y
Section at Y Y.
Section at Z Z.
E

E
כמות
A A, Pillar.
Fig. 425.-Pillar with Safety Valves and Central Spiral Spring.
B B, Central part for spring. cc, Valves. D, Crosshead. E, Hand lever. F, Spring.
G, Screwed spindle and nuts. н, Shackle. I I, Plate screwed into the top of pillar.
in a high degree both to the safety and durability of such boiler.
The following arrangement goes far to meet the requirements, the
only friction while lifting being from the valves themselves, and
which may be entirely avoided by the substitution of spherical
LOCOMOTIVE ENGINES.
57I
valves. A pillar consisting of one casting, which answers the pur-
pose of the manhole door, is bored out at the top for the reception
of the valve seatings, two in number. The valves are loaded by
the spring placed in the central box, which is secured to a crosshead
taking both of the valves, the crosshead being elongated to serve
as a handle, to enable the driver or engineman to ascertain the
working condition of the valves. The spring is made of sufficient
strength to resist the pressure on both valves, and is adjusted by
the nut on the top of the crosshead. The shoulder on the underside
of the crosshead should be drawn hard up when the maximum load
is put upon the valve. To prevent the valves being blown away
in the event of the spring breaking, the shackle fitted to the lower
part of the crosshead for taking the spring has two projections
formed on it, projecting beyond the slot in the cap which is screwed
into the top of the pillars. The valves, being equally loaded and
of equal size, will be simultaneously lifted with the cross bar when
the steam pressure exceeds the proper limit, and the spring will be
elongated through a range equal to the lift of the valves, and no
more; so that, except when the engineman is testing the action of
the valves, there is no movement in the joints of the apparatus, and
therefore no friction. A spring of 5%-inch round steel, and about
seven coils, is sufficiently strong to load two 3-inch valves to 80 lbs.
pressure per square inch, and in order to load them to this extent
the spring will have to be stretched about 134 inch, or 218 inch for
each successive increase of 10 lbs. pressure per square inch. In the
example we have delineated the spring is of smaller diameter than
the above, and consequently lengthened to make up for the reduc-
tion in diameter. Another arrangement shows the application
of the volute spring, which is placed in a shallow well in the man-
hole cover and adjusted by four nuts, which force down a cover plate
placed on the top of the spring, and so compress the spring until the
requisite pressure is obtained. Packings are then fitted between
the cover plate and the manhole lid to prevent any extra pressure
being applied. It is evident that, under any form, the valves cannot
be easily tampered with; and a brass funnel may be placed over
them in the ordinary way. Several of these valves have been at
work, proving highly satisfactory. They were found to be very
sensitive, having such freedom of action as to get into a state of
vibration, producing in some cases a musical note when at the point
of blowing off; and they allow the steam to blow off more freely
572
MODERN STEAM PRACTICE.
than other safety valves under a given excess of pressure. The
arrangement of the two valves under one lever is not new, but the

A
C
B
D
EU

G
D
F
F
Fig. 426.-Safety-valve Box with Central Volute Spring.
Centre part
for spring. cc, Valves. D, Crosshead.
F F, Plate with bolts for holding down the spring.
A A, Valve seat.
BB,
E, Hand lever.
E
object in the above arrangement is to increase the lift of the
valves, making it equal to the full extension of the spring, giving
great freedom for the discharge of the steam, and preventing it
rising above a dangerous pressure, and also to dispense with
the spring balance. The point of attachment of the spring is rather
below the level of the points bearing on the valves, so that in the
event of one valve lifting before the other it is overloaded, the
other being proportionately relieved, thus tending to secure their
simultaneous action. There is no scale attached; the spring is
adjusted originally to the maximum pressure intended by measuring
the amount of elongation or compression under a given load, and
by adjusting the screw to within 2 or 3 per cent. of the compression
or elongation produced by the desired pressure. The valves are
tested previous to being used, by comparing them with a pressure
gauge attached to the boiler.
The waste-steam funnel for covering the safety valves is made of
thin brass, and is kept highly polished, giving the engine a smart
appearance. It takes in both of the valves, delivering the waste.
steam at sufficient height so as not to interfere with the free vision
of the driver. It is made tapering from the bottom upwards,
ending in a plain circular moulding at the top, and spreading out
LOCOMOTIVE ENGINES.
573
at the bottom with bold curves to suit the curve of the fire box;
at the top it is suddenly contracted with a funnel-shaped piece
brazed thereto, having a hole of only sufficient diameter for the
escape of the steam, a plate being brazed at the top embracing the
outlet and extreme diameter of the moulding. All these funnels
should be as plain as possible, as they are more easily kept clean,
no corners being left with beads or small mouldings for dust to
collect. They serve the purpose of protecting the safety valves
from injury, and when the valves are loaded directly, and so covered,
they are not easily tampered with.
The covering dome for the steam chest is generally of cast iron,
spherical at the top, and when the safety valves are fitted on the
top of the steam chest a curved outlet is formed on the dome for the
escape of the steam. The bottom is finished in a similar way as
the waste steam funnel, with bold curves embracing the body of the
boiler, to which it is securely bolted with stud bolts and nuts.
Sometimes these covering domes are made of brass, kept highly
polished, and present a very handsome appearance; but we consider
it preferable to have them made of cast iron, and properly painted,
as the large brass surface is difficult to clean, and in the act of
doing so the paint on the body of the boiler gets rubbed off, and
soon becomes shabby. In like manner we consider all the mould-
ings on the body of the boiler should simply be painted, for when
they are highly polished extreme care must be taken when cleaning
is going on; in fact a locomotive should be cleaned down very care-
fully, for when the paint gets rubbed off, like an ill-groomed horse,
it is not at all nice looking. The steam horse well kept is most
pleasing to the eye, and is certainly, as a whole, the greatest
triumph in steam machinery.
The water gauge placed on the outside of the fire-box shell is
for showing the height of water above the crown of the fire box
and tubes. It consists of a glass tube 4 inch internal diameter
and % inch in thickness; it should be properly annealed to resist
the sudden and varying temperature it is subjected to. The
ends of the tube are made steam tight, with hemp and a screwed
gland; the stuffing box at the top end allows of the expansion of
the glass tube, while the tube rests on the bottom one. By this
means the glass tube passes through the hole at the bottom of the
stuffing box at the top end, and thus freely slides with the expan-
sion and contraction without compressing the hemp packing.
574
MODERN STEAM PRACTICE.
The connections simply consist of a branch piece at the top and
bottom of the glass tube, having a flange for bolting to the flat part
of the fire-box shell, fitted with a plug tap between the glass and

1
三
​A
10
B
jo-
C
9
16
Fig. 427.-Glass Water Gauge.
A, Top piece. B, Bottom piece. c, Glass tube.
the boiler, with a screwed cap for putting in a fresh tube, and a
screwed plug in a line with the passage through the plug tap. By
this means a rod can be passed through to clear away any deposit.
The packing glands for the glass tube are provided with a loose.
ring, which is screwed down over the packing with a screwed gland.
The plug taps are required in the event of the glass tube becoming
LOCOMOTIVE ENGINES.
575
fractured, thus providing a means of preventing a rush of steam, as
they can be instantly shut when required. There is a plug tap at
the bottom, in a line with the glass tube; this is the test tap for
showing if all the passages are in free communication with the


B
Fig. 428.-Water Gauge. Plug Taps.
A, Plug tap. B, Handle. c, Screwed part.
C
A
"
4
steam and water space, so necessary for truthfully working of the
apparatus. The range of the index in connection with the tube
varies from 9 to 10 inches, the general working height of the water
above the crown of the fire box being from 5 to 6 inches. Three
additional plug taps are screwed into the
fire-box shell; the bottom one should be
placed 3 inches above the crown of the fire
box, while the top one should be tapped in
6 inches above it. These plug taps are used
in the event of the glass tube breaking. An
experienced driver can at once tell by open-
ing them whether there is enough water over
the crown of the fire box. When the gauge
is fitted to the side of the fire-box shell it is
connected with a brass pipe, having distance
pieces of cast iron fitted to the curve of the
box, the three additional test taps being
tapped into the brass pipe, having the main
gauge connection at the top and bottom of
the pipe. This pipe is closed at the ends
with screwed plugs, which can be removed
for clearing it from deposit.

B
=69100
Connections.-A, Top part. B,
Bottom part. c, Glass tube and
index plate.
D, Brass pipe.
The pressure gauge indicates the difference Fig. 429.--Glass Water Gauge and
between the pressure of the steam in the
boiler and the atmospheric pressure. One form
consists of a curved flattened tube, into which the steam is admitted,
and which becomes more or less curved according as the pressure
576
MODERN STEAM PRACTICE.
is less or greater. For it is a law of nature, that bent tubes under
internal pressure have always a tendency to become straight. The
tube has an oval section, is fixed at one end, and in communi-
cation with the steam in the boiler; the other end is filled up, and
has a connecting rod attached to a lever, with toothed quadrant
and pinion, the pinion spindle carrying the index handle, which
revolves in the centre of a disc plate, marked round the circumfer-
ence to indicate the pressure in pounds per square inch, the whole
being inclosed in a suitable box. It is fitted to the cab, or weather
protecting plate, having a U-shaped wrought-iron pipe connection.
Water lodging in the bend, or oil poured in, prevents such delicate
instruments from becoming overheated with the steam so necessary
for their proper action.
The steam whistle is placed at the back of the outside fire box,
or on the manhole door on the top of the box. It consists of a
plug tap screwed into the door, which is in connection with an
annular chamber, the steam escaping through a narrow annular
aperture, blowing against the edge of the bell, which is generally
from 3 to 3½ inches in diameter and 2½ inches in depth. It is
usually cast in hard brass, this size producing the musical note
B
A
Fig. 430.—Guard's Steam Whistle.
A, Valve with handle. B, Annular
D natural, which is sounded with about 80 lbs.
of steam pressure, higher pressures giving a
much shriller sound; and as the fulness of
tone is affected by the pressure, the driver
must open the aperture cautiously, or wire-
draw the steam through the tap to give the
full note when the pressure exceeds 80 lbs.
When the handle is not within reach of the
driver, a lever is substituted, with a con-
necting rod and handle passing through the
weather plate, fitted to the back of the fire
box.
The guard's whistle is of the same con-
struction, but the bell is made larger, about
334 to 4 inches in diameter and about 5 inches
in depth. This gives a much lower note,
which is easily distinguished from the ordin-
ary whistle. Instead of the plug tap, a valve
having a screwed spindle is sometimes used, which is worked with
a suitable handle, or lever and connecting rod. This plan has the

chamber. c, Bell.
LOCOMOTIVE ENGINES.
577
advantage of being better able to adjust the volume of steam, so as
to produce a clear note, according to the steam pressure in the
boiler.
B
MIN
The blow-off plug tap or valve fitted to the bottom of the fire-box
shell, to blow off foul water and sediment, is usually
from 1½ to 2 inches in diameter. It consists of a
solid plug tap, or a hollow tap inverted is used,
with a rod and handle fitted to the small end of
the plug, worked directly from the engine plat-
form. Screw plugs for sludge apertures at the
corners of the fire box are 2 inches in diameter,
screwed into a plate having a boss forged thereon.
The plugs should be made of hard brass to prevent
corrosion, and should have a strong square part
cast on for taking the strain of the screw key.

A
A
Fig. 431.-Blow off, Hol-
low Tap.-A, Hollow-
tap valve. B, Seat
for tap.
When fitted to the
sides of the shell of the fire box, on a level with the crown of the
inside fire box, so that a water-
hose may be inserted, washing
away any sediment collecting,
a good form of sludge door is
simply a brass flanged pipe piece
(Fig. 432), having a screwed cap,
with square piece cast on for
applying a screw key, as in a A, Sludge pipe. B, Screwed cap. c, Square part
water hydrant. This plan has


B
Fig. 432.-Sludge Hole.
for unscrewing by.
a free opening, the screw being cast on the outside, and as such
the screw is protected from injury from the tools used in clearing
the deposit which lodges at the bottom of the fire-box water
space.
Heating plug valves are fitted to the shell of the fire box, being
located above the water line in the boiler. They are used for blowing
the steam into the tender or tank for heating the water, but only
when the engine is standing, or when there is a surplus of steam in
the boiler that would otherwise blow to waste.
The pipe fitted to the heating-plug valves for leading the steam
into one or both of the suction pipes for the pumps is of copper,
I inch in diameter, and is connected with couplings to the valve
and suction pipe, the pipe having a slight bend to facilitate
making the metallic joints, which are screwed firmly together.
These heating cocks and pipes are only fitted when ordinary pumps
37
578
MODERN STEAM PRACTICE.
are used for forcing the water into the boiler, but when an injector
is adopted they are dispensed with.
B
The lubricating plug tap for the steam-regulating valve, slide
valve, and cylinder, is fitted in mostly all instances to the top of
the smoke box, with a pipe connection to the regulating valve, the
oil flowing from thence into the cylinder, or other-
wise carried along with the particles of steam.
It simply consists of a hollow conical plug, into
which oil or melted tallow is poured through a
hole in the shell. The plug has a handle con-
nected to it in the usual way, so when the valve
is filled it is turned half round, until the opening
comes opposite the pipe, when the oil gravitates
into the regulating valve chest, and thence into
the cylinder.

A
Fig. 433.-Lubricating Plug
Tap for Steam Valves, &c.
A, Hollow plug valve.
B, Handle.
A hand rail of iron, or iron sheathed with brass, is fitted to the
body of the boiler, secured with stud eyes screwed into bosses
forged on plates, which are rivetted to the shell. This hand rail
should likewise be fitted across the front end of the smoke box, to
insure safety when passing along the framing while the engine is
in motion.
A stud for the forward lamp is rivetted to the top part of the
front of the smoke box; these lamps have a powerful light, and are
aided with a reflector, so as to show for a considerable distance
whether the line of railway is free from obstruction.
CONSTRUCTION OF THE ENGINE, &c.
Cylinders, covers, and glands.-The cylinders, whether. placed
inside of the smoke box, or, as in more modern practice, between
the frames, and in a variety of examples outside of the frames,
are arranged horizontally in some engines, and inclined in others.
With the inside arrangement the inclination given to the cylinders
and machinery is simply to obtain the necessary clearance above
the axle of the leading wheels, when of the same diameter as
the driving, wheels; while there is no such necessity when the
cylinders are placed outside of the framing, the angle given to
the cylinders and machinery being a matter of opinion with
the various designers. As regards the inclination to be adopted
in connection with the general arrangement—when the leading
LOCOMOTIVE ENGINES.
579
wheel axle is fitted with outside bearings, with springs on the
top of the axle box, the inclination must be greater, so as to
effect the necessary clearance above the springs; while in those
arrangements having only inside bearings for the axle of the
leading wheels, the cylinders are generally arranged horizon-
tally, by which the pattern-making becomes much more easily
executed, while there is evidently a saving in fitting up, and the
weight is kept lower down, with the advantage of direct action in a
horizontal line through the framing. The cylinders are of hard
cast iron, and in some instances wrought iron has been employed,
but it is evident this material is very costly. Toughened cast iron
has been used with advantage, being a mixture of cast and wrought
iron.
In former practice the cylinders were arranged inside of the
smoke box, holes being cut in the prolongation of the tube plate,
as well as in the front plate of the smoke box. The arrangement
was very compact, but the labour of fitting up was expensive, while
the disadvantage of attaching the machinery to the boiler soon
became evident from the expansion of the latter, causing a severe
strain to those parts rigidly held by the boiler and connected to
the framing. To overcome these difficulties the framing is arranged
to take the cylinders between the two horizontal plates running
the entire length of the engine, thus in a great measure keeping
them independent of the boiler. The cylinders are cast open at
the ends in some, while in others the back end is partially closed,
greatly strengthening the casting, only leaving an aperture of
sufficient size for the boring bar to pass through. All the passages
or ports and valve casings are cast along with the cylinder, as
likewise the side brackets, which are well ribbed in the casting,
and which form a strong junction between the cylinder and framing.
The weight of the cylinders rests on the top of the frames, a projec-
tion being left on the casting for that purpose; thus the cylinders
can be fitted to the framing quite independent from the boiler,
which may be in the process of manufacture. The cylinders are
joined together on the centre line, with flanges at the top and
bottom running the entire length, the exhaust passage being placed
at the top immediately over the exhaust ports. In this arrange-
ment there are valve doors fitted to the front and back, the latter
having stuffing boxes and glands for the valve rods, while the
former is fitted with stuffing boxes and glands to take the ends of
580
MODERN STEAM PRACTICE.
the valve rods acting as guides in maintaining a true line of action.
In other arrangements there is only one door at the front, while at
the back the stuffing box for the valve rod is cast along with the

E
限 ​434
k2
D
K
"
717
·
-16
न्त्र
B
A
A
H
JO
2
D
E
+3½ 3/2+
$28
F
K

A A, Cylinders,
B, Valve.
872
Figs. 434, 435.-Cylinders.
cc, Steam ports. D D, Exhaust passages. E, Regulator and chest.
F, Back cover. G, Stuffing box for the valve rod. H, Guide piece for the valve rod.
K K, Main frames.
I,
Front cover.
cylinder. The front cylinder cover is of the usual construction,
and is generally bolted to the cylinder flanges with stud bolts and
nuts; while the back cover is of smaller size, fitted with stuffing
boxes, bottom brass, and gland, and secured to the cylinder in like
manner. The generality of back covers have also projections cast
LOCOMOTIVE ENGINES.
581
on for taking the motion bars, as shown by Fig. 436.
There is
one regulator common to both cylinders, having the passages cast
along with one of the cylinders, while the other one is left plain, the

1
¦ D
C
C
·B-
D
Fig. 436.-Back Cover for Outside Cylinder.
A, Cover. B, Piston rod. c, Stuffing box and gland.
D D, Motion bars.
valve casing being a separate casting bolted to the cylinder. In
some examples with inside cylinders the main steam valves are
placed on the top, with separate valve-casing covers for each cylinder.
Although for all arrangements, whether horizontal or inclined, the
framing forms the chief mode of attachment for the cylinders, some-
times they are likewise let into the tube plate and front plate of the
smoke box, the sides of the smoke box ending on the top of the
framing.
For outside-cylinder arrangements the framing affords the sole
means of attachment. When small leading wheels are adopted,
and in some cases with large wheels of the same diameter as the
drivers, the valve casing is placed on the side, towards the centre
line of the engine, and passes through an aperture formed on the
framing, to which it is securely fastened with bolts and nuts passing
through flanges cast on the cylinder. The centre line of the valve
spindle in the above example is in a line parallel with the cylinder,
582
MODERN STEAM PRACTICE.
but if large leading wheels are adopted it is necessary to incline the
rod to obtain the necessary clearance above the axle. In all these
examples the steam ports are much longer than in ordinary arrange-
ments, but at the same time some are shorter than others, provision
being made by the slide valve so as to make them as short as
practicable. To reduce them to the usual length they may be, and
are arranged on the top of the cylinder; but this plan necessitates
an indirect motion for the valve gearing-that is to say, when the
valve is placed horizontally; but in many arrangements the valve
is inclined, while the valve gearing is direct, although not in the
same horizontal line as the cylinder.
The valve casing is sometimes cast along with the cylinder,
having a door conveniently arranged with a view to its being easily
removed; while in other examples the casing is a separate casting,
bolted to the cylinder with long stud bolts, the same bolts taking
the cover.
The cylinder covers at the front end are sometimes
recessed, having an L section of piston to suit, and which passes
into the recess, while others are recessed at both ends, having a
T section given to the piston. By this means the cylinders and ad-
juncts can be made a little shorter, which may be considered by some
an advantage, but the main advantage consists in the piston, which
is greatly reduced in weight by using any of the above sections.
The inside length of the cylinder, between the cover and the
back end, is equal to the length of the stroke, to which is added
the thickness of the body of the piston, and the clearance at each
end, which is usually 4 inch, and in some 3% inch is allowed.
This is necessary to allow for the variations in the length of the
connecting rod, due to the wear and other causes affecting the
position of the piston in the cylinder: in the event of the water
in the boiler priming over also, some space must be left to get rid
of it, otherwise the ends of the cylinder would be unduly strained.
The steam ports are of a rectangular form, cut square in at
the corners in most examples, while some are slightly rounded
at the corners; the face generally projects above the metal of the
port ½ inch, to keep the valve clear of the metal on port, as
likewise to allow for wear. The steam ports run partly into the
covers at both ends; by this means the piston does not travel past
the edge of the port too much at the end of the stroke.
All the joints are metallic; they are planed all over and then
scraped, to make them perfectly steam tight, and when finally put
LOCOMOTIVE ENGINES.
583
together receive only a thin coating of red lead prior to tighten-
ing up the bolts.
For valve chests exposed to the action of the smoke and dust
collecting in the smoke box, brass nuts of considerable depth are
to be preferred, the nuts so formed as to in-
close the point of the bolts. Those nuts having
no tendency to corrode are preferable to iron.
ones, as they do not strain the bolts when
taken off, being very easily unscrewed.
In order thoroughly to provide for the lu-
brication of the piston and valve rods, cups
are sometimes formed in the brass glands,
fitted with a hinged cover. The stuffing box
has the usual brass lining piece at the bottom;
both it and the gland are hollowed out at the
end bearing on the packing: thus when the
packing is pressed up it is forced out against
the rod. Two stud bolts and nuts are required
for each gland. The valve rod passes through

PIN=
711
B
A
2동
​5
Box of Piston Rod.
the front of the steam chest, and is guided by Fig. 437.-Gland for Stuffing
means of a stuffing box and gland, and in
some instances works in a brass tube, closed
B
A, Gland. B, Oil cup.
at the end, the tube being bolted to the steam chest. With this
arrangement there should be a small hole cut where the rod bears
on the neck of the tube,
so as to allow water ac-
cumulating to be ejected,
which would otherwise
eventually rupture the
tube.


A
8
21
2
8
A plug tap is fitted to
the bottom of the cylin-
ders at the front and back,
placed at the lowest part,
so that any water accu-
mulating may be run off.
Their bore is usually
or ½ inch in diameter; they are fitted with spindles and levers,
with a rod passing along to the starting platform. These taps are
generally left open for a considerable time after the engine is started;

7
16
Fig. 438.-Gland for Stuffing Box of Valve Rod.
A, Gland. B,
B, Oil cup.
584
MODERN STEAM PRACTICE.
the cylinders being of course cold, condensation will take place,
and the water accumulating is forcibly ejected along with the
B
steam. As a considerable waste of steam
takes place, the bore of the taps is made small
to prevent excessive loss.
A plug tap is likewise fitted to the lowest
point of the valve casing, which should be
opened prior to starting the engine, or when
the water from the boiler primes over, thus
tending to keep the water out of the cylinders.
The engine driver can easily detect when
Fig. 439.—Cylinder Plug Tap. priming is going on while the engine is run-
ning, and should always have the means of
opening the plug tap from the platform, in a similar way as the
small taps fitted to the bottom of the cylinders.

A, Plug tap. B, Rod.
Grease cups should be fitted to each top corner of the cylinder.
They are provided with a plug tap at the bottom, which is screwed
into a hole tapped in the cylinder. This plug
B
A
A
tap carries a close cup, fitted with another plug
tap at the top, through which the melted
tallow can be run into the cup while the engine
is in motion, for the lubrication of the piston
and cylinder, the tap for the escape of water
in the cylinder being shut. There is another
Fig. 440.-Grease Plug Tap. grease cup for lubricating the regulating valve,
steam valve, and piston, which is fitted to the
top of the smoke box or side of the smoke
A A, Plug taps. B, Cup.
box, as already described.
The main slide valve is generally of cast iron. Sometimes brass
valves have been adopted, the cylinder faces wearing better with
such valves. But when cast-iron valves are used, placed on edge,
they are found very efficient. The valves are of the short
D description; the valve rod or spindle for working them in con-
nection with the valve gear has a strap forged on, embracing the
whole of the valve, leaving it free to move towards and from the
face of the cylinder, the valve being held to the face with a light
steel spring, secured with stud bolts and nuts to the valve rod.
Sometimes the strap embracing the valve is not in a line with the
rod, but is bent in the forging to suit any peculiarity in the arrange-
ment of the valve gear. It is an object with high-pressure steam
LOCOMOTIVE ENGINES.
585
to relieve the valve from the pressure; with this in view rings
properly packed have been fitted to the back of the valve, thus
placing, as it were, the valves in equilibrium, or relieving them
2.572.
6:4
2'5%-
C
3

B
*1*1*14
-246-*
43/8
·2%5.
-165.*.
A
--Brass
Stide
-7/6.
A, Slide valve.
Fig. 441.-Slide Valve and Rod.
B, Valve rod. c, Spring. D D, Stud bolts.
greatly from the pressure, reducing the wear and tear, and making
them much more easily handled.
A very general plan consists of a separate disc plate and packing
ring (working steam tight against a central plate in the steam
chest), which is secured to the back of the slide valve: thus the
pressure of the steam, acting as it were in opposite directions, tends
to relieve the valve from pressure. At the same time, the arrange-
ment allows for the wear of the valve.
Another plan well suited for the locomotive engine consists in
casting a short cylinder along with the valve, and situated behind
it, which is accurately bored out for the reception of a thin packing
ring. This ring is turned slightly larger, and is cut through at one
part, and sprung in the cylinder: thus it forms as it were a piston
ring, fitting steam tight into the cylinder, while at the same time.
the thin edge is pressed up against a fixed plate, with steel springs
placed between the ring and the valve. A round pin is let into
the valve, a hole being bored in the spring ring to receive it, to
586
MODERN STEAM PRACTICE.
prevent the ring turning round. A hoop is forged on the valve rod
for taking the cylindrical part of the valve, thus forming a loose
connection between the valve and the rod.
E

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Figs. 442, 443.—Eccentric, Expansive Link, &c.
A, Eccentric. B B, Pins and cotters.
G, Rod.
HH, Links. 1, Slide Block.
cc, Set screws. D, Strap. EE, Snugs and bolts. F, Oil cup.
K, Lifting rod. L, Guides for valve spindles.
LOCOMOTIVE ENGINES.
587
Valve motion.-Double eccentrics and link gear are generally
used for giving motion to the steam valves, the parts pertaining to
these consist of sheaves, straps, rods, links, sliding blocks, lifting
links, guide bar and block, weigh bar and lifting arms, with balance
arms, and reversing rod, lever, and quadrant.
The eccentrics are of cast iron, made in two pieces secured toge-
ther with pins and cotters, having a groove and feather for prevent-
ing any movement sideways. The eccentrics are held in position on
the shaft with two set screws and jam nuts. The working surface
in the example shown (Fig. 442) is turned with a raised flat part or
ridge fitting into a corresponding recess in the strap, which is
usually cast in brass, with lugs cast on for holding the strap
together, with one bolt and two nuts for each. There is likewise an
oil chamber cast on the forward half of the strap, and the strap
may be ribbed to give greater strength. AT piece is also cast on
the forward strap for taking the end of the eccentric rod, which is
secured thereto with two bolts and two nuts for each. The rod
has a T piece forged on for connecting to the strap, and a double
eye for taking the link, which is of the open solid kind, coupled on
the centre line, this plan necessitating a greater throw for the eccen-
tric than the travel of the valve. The radius of the link is the length
from the centre of eccentric rod to the centre of the link, the open
part being accurately slotted out for taking the sliding block, which
is made of steel, having a hole bored in it for receiving the pin
passing through the jaw of the valve rod. The link is hung from
the top, with two lifting or suspending rods, one on each side, on
which a part has in some cases been forged on, acting as a guide to
the link, but this is not much adopted in modern practice. The
guide bar on the valve rod is square, with guide blocks secured to
a plate, bolted to the top of the motion bars; these guide bars are
introduced to prevent any twisting strain on the valve spindle.
In the next arrangement under notice the eccentric working sur-
face is circular, and is held in position on the axle with one set screw,
having a wrought-iron nut let into the cast iron. The straps are
divided at an angle to the line of the rod, with oil cup cast on the top
fitted with a hinged cover. The rod is formed with a dove-tailed
piece, let into the strap, and securely rivetted thereto, while the link
end of the rod has a fork forged on for taking the link, fitted with a
plain pin, which is held in position with a split pin bearing on a
loose washer. The expansion link is of the former description,
588
MODERN STEAM PRACTICE.
suspended from the bottom with two side rods. Instead of the
valve rod being guided with a V or square piece in a line with the
rod, the sliding block is fitted to a rod, oscillating on a pin close
up to the gland, and suspended with the vertical oscillating links,
hung from brackets attached to the body of the boiler.

D
A
C
=
F
D.
E
5 6
16
A
KIH
B
ဘဲ
#ဆ
B
E72
G
(toloo)
+4
G
E
Fig. 444.-Eccentric and Rods.
A, Eccentric. B B, Pins and cotters.
c, Set screw. D, Strap. EE, Snugs and bolts.
F, Oil cup. G, Rod
In some arrangements (Fig. 445) the straps and rods are forged in
one piece, working on cast-iron eccentrics in this example; the pump
is worked from a pin on the back-going eccentric rod, having a bent
rod for clearing the axle of the driving wheels, an arrangement not
at all to be desired, although by this means a longer rod is obtained,
which tends to lessen the thrust on the plunger gland. The link is
arranged with lugs forged on for taking the eccentric rods, and the
link is suspended between the two, with side links oscillating on pins
forged on a piece bolted to the link. All the joints are provided
with oil cups forged on as shown. The sliding block for the link
is fitted as in the previous example to a rod, oscillating on a pin
passing through a crosshead, fitted to the valve rod; the rod being
supported by a jointed link hung from a plate bolted between the
main frames.
In all the preceding arrangements the links are of the lifting
LOCOMOTIVE ENGINES.
589
link on the valve rod moves up and down. In the example under
2
2
3-
H
11
ENI
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FO
121"
이번
​א
F
E
Figs. 445, 446.—Back Eccentric and Rod, &c.
D
12
Ꭱ
M
TO
K
« 4x
H
A, Eccentric. BB, Pins and cotters. CC, Set screws. D, Strap. EE, Snugs and bolts. F, Oil cup. G, Rod. H, Bent rod. 1, Link.
KK, Lugs and pins for the eccentric rods. LL, Lifting rods.
M, Oil cup.
description; some are, however, stationary, while the connecting


590
MODERN STEAM PRACTICE.
ཉྩ
29
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O
A
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F
B
C
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B
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1
•

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171
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100
2100
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ofer
K

A, Eccentric.
B B, Pins and cot-
ters. cc, Set screws. D, Strap. EE,
Snugs and bolts. F, Oil cup. G, Ec-
centric rod. H, Link. 11, Snugs for
the eccentric rods. K K, Suspending
rods.
L, Sliding block.
rod.
M, Valve
Figs. 447, 448, 449, 450.--Eccentric and Strap, Expansive Link, Valve Rod, Link, and Sliding Block
LOCOMOTIVE ENGINES.
591
notice the eccentrics are of cast iron, and the strap and rod of
wrought iron. The link is of the double description, rivetted
together and suspended with two hanging links from a bracket
C
A
B
secured to the boiler. The
connecting link is forked at
one end, taking a crosshead,
which works in suitable
guides. The sliding block is
of course double, made in
one piece, with a part cut out.
at the middle for the end of
the connecting lever held in
position with a pin passing
through the block. There is
a boss on the lifting link, a
short distance from the end that takes the sliding block for securing
the link for the up and downward motion. In some examples of
valve gear it may be necessary to bend the valve rods and eccentric
rods to clear the axles; this may be arranged as delineated.


A
Fig. 451.-Valve Rod and Eccentric Rod.
A A, Axles. B, Valve rod. c, Eccentric rod.
A modification of the link motion more recently introduced is
illustrated by Fig. 452. The expansive link is straight; the sliding

A
B
C
F
B
E
D
Fig. 452.-Straight Link Motion.
A, Eccentrics. B B,
B B, Eccentric rods. c, Straight link.
D, Connecting link.
E, Connecting link. F, Radius rod.
block is carried on a radius link, placed between the main link and
the valve rod; both are connected to a long and short lever on
the weigh shaft, so arranged that the one travels up and the other
down, and vice versa, meeting each other at half lift, the greatest
vertical motion of each being only about half of that given to other
link motions. Single eccentrics have been used for each valve,
the reversing and expansion motion being obtained by means of
spirals and wedges. Figs. 453 and 454 give a general idea of the
arrangements; the angular position of the eccentrics being al-
592
MODERN STEAM PRACTICE.
tered laterally with spirals on the axle, and transversely with
wedges.

B A
C
Fig. 453.—Single Eccentric with Lateral Movement.
A A, Eccentrics. B, Sheave for altering the position of the eccentrics. cc, Cranks.


B
B
C
A
A
Fig. 454.-Single Eccentric with Transverse Movement.
A A, Eccentrics.
B B, Wedges. cc, Cranks.
The guide bar for connecting the link motion with the valve

1/2
C
12100
3100
-498-
*-.274.
OON.
-472
13/6
-893/14
X1
A
194square
7/8bolts
D
1/8 square
·472
B
8/67
37%
Fig. 455.—Guide Bar and Block for Valve Spindle.
B
E
A Guide bar. B, Socket for the valve rod. c, Eye for the link.
E, Motion bar steadiment.
D, Guide block.
spindle is of an elonga-
ted V section at the top
and bottom; some are
made of a square section,
with the V at the top and
bottom, which works in a
guide block of brass, which
is generally bolted to the
back steadiment for carry-
ing the motion bars. The
guide bar has a jaw forged
on at one end with a pin
for taking the link and
carrying the sliding block,
and at the other end there
is a socket for the slide-
valve rod, which is secured
with a cotter. The guide
block is fitted with a cover,


LOCOMOTIVE ENGINES.
593

f
-12″.
F
20/4=
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6
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Fig. 456.-Reversing Shaft, &c.
▲, Shaft. BBB, Link levers. c, Rod lever. D, Balance weight and lever. E E, Journals and bearings.
F, Reversing rod.
594
MODERN STEAM PRACTICE.
with coilar bolts for securing it to the angle iron on the steadi-
ment, the bolts being prolonged at the top for taking the cover,
and are fitted with nuts and jam nuts. In some examples
with lifting links the guide bar and blocks are dispensed with,
the sliding block in the link being carried by a connecting rod
jointed to the valve rod; this connecting link has a jointed arm
which is suspended from a pin passing through a bracket bolted
to the under side of the body of the boiler, this arrangement re-
quiring no further guide, the connections vibrating with the motion.
When the link is stationary the sliding block in the link is carried up
in like manner, the connecting rod for carrying the sliding block
in such examples is raised and lowered with a connecting link and
arm, and it is necessary to guide the valve spindle in such an
arrangement, as the connecting rod lies at a considerable angle;
it may be simply guided with a prolongation of the valve spindle,
passing through a bracket bolted to the framing, as with outside.
cylinder arrangements, or any other convenient and simple guide
can be used, according to the design and position of the valve
gear.
The weigh bar or reversing shaft (Fig. 456) is quite parallel in some
examples, and is carried up with brackets bolted to the main fram-
ing, the brackets being in the form of pillow blocks, having covers for
the weigh-bar journals, while in other cases the brackets have merely
solid eyes, and the weigh bar is held in position with loose collars
pinned on. The lifting arms, weight arm, and reversing arm are
separate forgings, which are keyed and pinned on the weigh bar.
In some arrangements two lifting arms are provided, while in
others there are three lifting arms, and it is now the general practice
to forge them on with the weigh bar as well as the weight arm,
which is weighted for balancing the motive links, &c., as likewise
the reversing arm-all of which, along with the weigh bar, form
one solid forging. The reversing rod has a plain flat section, and
is fitted with joints at the ends for taking the reversing lever
and arm of the reversing shaft.
The reversing lever is a simple lever, having the fulcrum between
the end and the handle, as shown in Fig. 457, the stud for carrying it
being bolted to the framing, or to the quadrant as the case may be,
the lever being held in position with a loose washer and pin; it is pro-
vided with a detent which is fitted with a spring for holding it in the
quadrant. The quadrant is simply two curved plates, which can
LOCOMOTIVE ENGINES.
595


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Fig. 457.-Reversing Lever and Quadrant.
B, Fulcrum. c, Quadrant. D, Detent
A. Lever.
rod. E, Detent lever. F, Reversing rod.
?
C
]}
=
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B
HGH
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Fig. 458.-Reversing Lever and Quadrant
Lever. B,
A,
Bracket on the foot plate. c, Quad-
rant. D, Detent rod. E, Joint for reversing rod.
596
MODERN STEAM PRACTICE.
be variously arranged to suit the framing, or that part of the boiler,
or foot plate, to which it may be bolted; the top edge has a number
of slots cut in it for holding the starting lever in position when
cutting off the steam at the different grades of expansion.
The piston consists of three important parts, namely, the body,
the junk ring, and the packing ring or rubbing surface, but in some
the junk ring is dispensed with. The body may be of cast iron or
brass; brass is to be preferred, owing to its lightness, and not
being so liable to rupture as cast iron. The junk ring is made of
the same material as the body of the piston. Packing rings of
cast-iron, brass, and steel rings have been used with advantage.
Brass rings work smoothly, and effect but little deterioration on
the surface of the cylinder, but they wear rapidly and require
frequent renewal. Cast-iron rings are the most durable, and when
properly fitted and well attended to when first put in, give but
little trouble, working smoothly and keeping the cylinder surface
in good condition,-that is to say, when the cylinder is cast in hard
metal, but when the metal is soft the packing rings should be of a
composition of 2½ oz. tin and 4 oz. zinc per pound of copper:
this is found to answer well, keeping the cylinder surface highly
polished. The packing rings should be easy in action, as the
cylinder has a tendency to wear oval, owing to the weight of the
piston. Packing rings cut in four segments accommodate them-
selves better to the unequal wear, and cause more equal friction on
the rubbing surfaces, than a ring cut at one point; as the rings,
having a wedge piece and spring for pressing them up against the
cylinder surface at each division, four wedges and springs will in
the former case be used, whereas when the ring is cut only at one
point the wedge must be pressed up with greater force, which, acting
on one point, must produce unequal friction, the point where the
ring is cut being that of greatest friction, while that of least friction
will be directly opposite. It is customary, therefore, to make the
ring thicker at the part where it is cut to allow for the wear, and
gradually tapering to a less thickness directly opposite the wedging
pieces. It has been found practically that the four segments
equalize the pressure on the surface of the cylinder, the rubbing
surfaces wearing equally; whereas when the ring is cut at one point
the wear is greater at that point, while the single ring is not so
durable. Single rings are sprung into the cylinder, consequently
they act partly with their own elasticity; therefore, the wedge does
LOCOMOTIVE ENGINES.
597
not require to be pressed up so hard at first, until the inherent
elasticity is nil, and then the wedge and spring are pressed up
accordingly. The springing of the ring is effected by turning it
nearly ½ inch larger in diameter for ordinary pistons; a part is
then cut out, so that when the ring is compressed the joint is
hard up, the ring fitting tightly into the cylinder: the part cut out
need not exceed 3/8 inch or so. The ring when new of course acts
with its own elasticity, the expansive force being more uniform
B
A
B
A
C
C
B


-15-
= -100
A
B
C


"
15-
A
Figs. 459, 460, 461, 462.-Piston Rings, showing the Wedge Pieces and Springs.
A, Piston rings. B, Wedge pieces. c, Spring with set bolts and nuts.
throughout the ring; it is then in its best working order. As it
wears the elasticity is destroyed, and the ring is expanded by the
wedge and spring, which tends to throw the strain on one point,
locating the wear of the surface at that part of the ring and cylinder
surface. When single cut rings are adopted they should be sprung
against that part of the cylinder which has the least wear. Taking
the weight of the piston into consideration, least wear must take
place on the top surface of the cylinder; and when two rings are
598
MODERN STEAM PRACTICE.
used, which is generally the case, the wedging pieces should be
placed on each side of the vertical centre line, thus tending to keep
the cylinder truly cylindrical. The wedge should be made at an
angle of 70°, thus securing free action laterally and radially. When
made sharper it is more powerful in pressing out the ring, but
has a tendency to gag it; while with a more obtuse angle the
range is shorter, the thrust being reduced, and the radial thrust
given by the spring is increased, throwing more stress on the ring
and cylinder surface. The springs are in one continuous piece, or
short springs are adopted for packing rings cut at one point; but
when more wedging pieces are introduced, the ring being in seg-
ments, four or more springs are required, just depending on the
arrangement. The set screws are generally fitted with jam nuts, the
screw passing through the spring, or in some it is screwed into the
spring and held in position with jam nuts. The packing rings are
concentric in some cases, while in others eccentric rings are adopted,
the latter being cut at the thickest or thinnest part. When cut at
the thickest part, they wear better and last much longer than those
cut at the thinnest part, while concentric rings seem to answer all
the requirements. However, we certainly prefer, with single cast-
iron rings, the wedge fitted to the thick part of the ring, as has
already been described, taking into consideration the unequal wear
of the cylinder surface due to the weight of the piston and adjuncts.
The weight of the piston
is sometimes carried up, by
having a metallic piece in-
serted between the rings and
the body of the piston, which
is located at the bottom side
bearing on the bottom of the
cylinder; thus the body and
rings are kept as nearly as
practicable in their original
position.

F
A
B
D
D
D
E
E
C
D
Fig. 463.-Piston with Packing Ring in Four Segments.
A, Piston. B, Junk ring. c, Packing ring. D D, Springs
with set screws. E, Cotter. F, Piston rod.
The various arrangements
of pistons now claim our
attention; the example under notice has one packing ring, cut into
four segments, the ends of which are half-lapped, fitted with tongues
to make them steam-tight. The wedges are cut at an angle of 122°;
their radial movement being small, they never rub on the cylinder
LOCOMOTIVE ENGINES.
599
surface, and do not therefore tend to form ruts. The ring being
cut in four segments, the action of the wedges is very free, superior to
that of a single sharp wedge acting on a single ring cut at one part,
while the wedges work more truly as the rings wear, differing less
from the angles of the openings. The spring for pressing the
wedges up to the packing ring is continuous, bearing on the four
bosses for the bolts of the junk ring, which are formed on the
body of the piston; by this means should any of the screws get an
extra turn, the pressure is in a measure transmitted, and better
diffused amongst the others. The body and junk ring, for securing
the packing rings, are of brass, and the packing ring of cast-iron,
the piston rod being secured with a plain cotter, passing through
the central boss cast on the body of the piston.
Another form of piston materially differing from the foregoing,
has two packing rings, with one wedge, spring, and set screw for
OF
D
F
E
لعراقي
E
B
2
4


dada.
A
5100
G
Fig. 464. Piston with two Packing Rings, with Collars formed on the Piston Rod.
A, Piston.
B, Junk ring. c, Packing rings. D, Wedge piece.
F F, Tapped holes for bolts for junk ring. G, Piston rod.
EE, Springs with set screws.
н, Collars on piston rod.
each, the springs being continuous. The junk ring is made of extra
thickness, with five holding bolts, with holes tapped into the body
of the piston, which is made of cast iron. The piston rod is secured
by means of collars formed on the rod, which is firmly held with
the junk ring. This plan has its advantages as there are no parts.
to shake loose, while there is no strain on the junk-ring bolts, the
steam pressure being taken on the collars-the piston too can
be turned round, by simply slackening the bolts, thus altering
the rubbing surface and equalizing the wear.
600
MODERN STEAM PRACTICE.
Another arrangement with two packing rings, fitted with wedges,
has a short spring and set screw, the ends of the spring bearing on
C
D
C

A
B
F
E
બહા
SHIN.
રામ=
F
B
A
Fig. 465.--Piston with two Packing Rings, with short Springs for Wedges.
A, Piston.
B, Junk ring. c, Packing rings.
FF, Holes for bolts for junk ring.
D, Wedge. E, Spring with set screw.
G, Cotter for piston rod.


A, Piston.
ર
cofen-
=alt
-16
F
F
B
A
21"
B
C
CG-
A
D
E
E
BHO
E
F
G
E
F
D

+
Figs. 466, 467.-Pistons with Concentric Ring, and Concentric Spring Ring.
B, Junk ring. c, Packing ring. D, Concentric ring. EE, Springs with set screws.
FF, Bolts for junk ring.
G, Cotter for piston rod.
LOCOMOTIVE ENGINES.
601
projections cast along with the spring rings. The body, junk ring,
and packing rings, are of cast iron; the bolts for the junk ring
are screwed into brass nuts let into the body, the piston rod being
firmly secured with a split cotter. There is a wrought-iron rest
pinned to the body, for keeping the body and packing rings central
with the cylinder.
With the view of diffusing the pressure on the packing rings, a
pair of brass rings have been adopted cut at one point, inside of
which is a concentric spring ring, on which springs and set screws
are brought to bear, thus diffusing the pressure all round the pack-
ing rings, and as these are of brass, the friction is thus reduced.
The action of the concentric spring ring, in this case, differing
from the foregoing examples, is needed, inasmuch as it acts of
itself as a spring keeping the two packing rings equally up to the
face, which would not be the case were the small springs acting
directly on the packing rings. The body and junk ring are of brass,
the piston rod being fitted with a screwed end, which is screwed
into the piston, and has a pin passing through the body and rod.
In one of the examples under notice the piston is parallel, while
in the other one the body is deeper, thus giving a better hold for
the piston rod, and it will be noticed in both arrangements that
snugs are cast on the body, through which the set screws for the
spring pass. We consider that these pistons are excellent examples
of their class, and the packing rings when of brass, as these are, will
undoubtedly wear much longer than others.
All
Another very good method (Fig. 468) for diffusing the pressure, as
applied to single cut rings, is to have a circular steel spring, bearing
uniformly on the entire circumference of the packing rings, the spring
acting between the rings pressing them up to the surfaces of the
piston flanges, as well as the cylinder surface, and supplying of itself
the necessary range of elasticity. The rings are cut obliquely on their
faces, thus preventing grooves being cut in the cylinder surface;
the piston rod in this example is secured by a plain cotter.
pistons should be fitted with some means for preventing the bolts
in the junk rings working backwards. A plate is shown in this
example which bears on the side of the bolt heads; it is
secured with two stud bolts, and two stud pins also pass through
it, having a split pin bearing on the top of the plate. All the
rubbing surfaces of these pistons are turned and rendered per-
fectly steam-tight by scraping them; formerly they were ground
602
MODERN STEAM PRACTICE.
with emery, but the plan was bad, inasmuch as the small gritty
particles became imbedded in the metal, causing great friction and
C
C

47


งา
con=
E
"
E
B
A
B
A
C
A, Piston.
Fig. 468.-Piston with Circular Steel Spring, &c.
B, Junk ring. c, Packing rings. D, Circular steel spring. E, Cotter for the piston rod.
deterioration of the surfaces. When all the rings are adjusted,
and properly finished on their surfaces, thin slips of paper are
introduced, and then the junk ring is screwed hard up; by this
means the rings are held firmly in position, and then the outside
circumference of the piston is finished in the turning lathe, this
being required as the last operation, since in the course of fitting up
the surfaces are liable to get damaged.
C
In order to reduce the weight of the piston,
and likewise to reduce the number of parts,
self-acting steel packing rings have been suc-
cessfully adopted, working longer than the
more complicated arrangements, giving less
trouble for inspection, and requiring but little
repairs. Several good examples of these steel
packing rings have been in use; they are
chiefly of two types, first, spring packing rings,
depending on their own elasticity, and secondly,
Fig. 469.—Piston with a Series those depending on the pressure of steam ad-

A
B
of Steel Rings.
A, Piston. B, Steel springs.
c, Piston rod and nut.
mitted behind, or within the ring, to keep them
up to the cylinder face. In the example under
notice (Fig. 469) the piston is a solid casting, the
packing rings consisting of a series of steel springs to in. square.
They are made in one piece, and cut with a saw at one point, and are
5
18
LOCOMOTIVE ENGINES.
603
simply extended and sprung into grooves turned on the circumference
of the piston. These plain rings work for months, and last as long
as they can hold together, or until they are nearly worn through.
Another form of packing ring, for solid pistons, consists of
a flat cast-iron ring 1 inch
wide and 3 inch in thickness;
the ring is made steam tight
where cut with a tongue ri-
vetted to the body of the pis-
ton, and let into slots cut in
the ends of the ring, the ring
being extended and sprung
into the groove, turned in the
piston. This piston is very
light, and is well calculated
to meet all the requirements.


B
C
Fig. 470.-Piston with Single Cast-iron Ring.
A, Piston.
B, Packing ring. c, Piston rod and nut.
Pistons depending for their
efficiency on the steam being admitted behind the packing ring are
constructed in a similar way; the ring, however, is made deeper, and
not so broad on the rubbing surface-a small hole being bored in
the body to allow the steam behind the ring.
In these latter examples the piston rods are
secured to the body by a nut, screwed on to
a thread cut on the end of the rod.
C
A
B

Piston rod, crosshead, and motion bars.-Pis-
ton rods are generally made of Lowmoor iron
or the best scrap iron, although steel has been
largely used in their construction. The part
fitting into the piston has a taper of about
I in 8 or inch for pistons 4 inches deep.
They are generally secured with a split cotter
passing through the boss, which is strength-
ened for that purpose; while in some the rod
is screwed at the end, and the piston secured
with a single nut, having a round split pin
passing through the nut and rod, thus prevent-
ing the nut turning backwards. Sometimes the A, Piston. B, Packing ring.
piston rod is forged along with the piston, and
consequently requires neither cotters nor nut; this plan, however, has
not been very generally adopted. Piston rods with flanges forged
Fig. 471.-Piston with Single
Ring, with Steam behind.
c, Piston rod and nut.
604
MODERN STEAM PRACTICE.
on, form a very good attachment, being very secure, having no
parts to work loose, while the pressure is taken on the flanges, thus
making this mode for securing the piston on the rod complete in
its simplicity. The piston is held in position by the junk ring, the
De
B
A
Flex
2
B
pressure on the back end is taken
directly on the flange of the pis-
ton rod, while on the front end
the strain imparted to the junk
ring is simply due to the fric-
tion of the piston.


1 E
о
O
B
不
​Aley
A
A
B
9
3
D

Figs. 472, 473.—Crossheads and Guide Blocks.
A, Crosshead.
BB,
Guide blocks. c, Piston rod and cotter. D, Gudgeon.
E, Pin for taking pump ram.
The crossheads are of wrought iron, having a part bored out for
receiving the piston rod, which is secured with a nut in some cases,
and a cotter in others; the taper of the rod fitting into the crosshead
need not be so much as that for the piston, I in 20, or even I in 30,
being sufficient. Crossheads are arranged in two ways; the best
arrangement, we consider, is that in which the crosshead is adapted
B
O
B
A
Fig. 474.-Crosshead for Single Motion Bar.
A, Crosshead. B B, Motion bars. c, Piston rod and cotter.
D, Gudgeon.
for single-ended connect-
ing rods, with motion bars
on each side. The cross-
head is of a forked shape,
with holes bored through
for the reception of the
gudgeon, for taking the
end of the connecting rod,
which is driven tightly

into its place, having flat keys let into it for holding it in its position,
preventing it turning round. The gudgeon is longer at one end than
the other, the short end is simply for one of the sliding blocks, while
LOCOMOTIVE ENGINES.
605
Crossheads for single
the long end likewise takes the pump ram.
motion bars are generally made in one piece, bored out for the recep-
tion of the piston rod, which is secured with a cotter in some, and a
cotter and washer in others, the rubbing surfaces are steeled, and
planed out with cross gutters, cut out for lubrication. The connect-
ing rod is forked in mostly all examples. When the crossheads are
shallow the rod requires to be forked for a considerable length, to clear
the ends of the motion bars, but when made of sufficient depth it is
only forked to clear the crosshead; a sufficient depth is left between
the motion bars, for the connecting rod to work within them. Some
of these crossheads are made to receive a single-ended connecting rod;
the plan, however, is bad, as the connecting rod is shortened, the point
of attachment being overhung and nearer the crank pin, while the
line of action taken on the motion bars is not so perfect, and
cannot act so well as when the pin for taking the connecting rod
静
​
-10
--22-
T
M/D
C
A
ญ
V
लाद
D
·57.

B
5
B
D
Fig. 475.-Crosshead with Cast-iron Guides lined with White Metal.
A, Crosshead. B B, Cast-iron guides. c, Piston rod and nut. D D, Gudgeon.
B
A
C
D
D
is placed central with the slides or crosshead. The crosshead
in many examples is fitted with cast-iron guides, which in some
are lined with white metal, but cast
iron of itself works very well on
iron motion bars, and is preferable
to steeled guides, as the latter are
uncertain, tending to cut the motion
bars. These guide pieces are bored
out, taking a pin at the top and
bottom, which are turned on the cross- Fig. 476.—Crosshead with Cast-iron Guides.
head, no other fixture than this being A, Crosshead. B B, Guides. c, Piston
rod and cotter. D D, Gudgeon.
necessary. In the two examples we
give it will be noticed that the piston rod is secured to the
crosshead, with a nut in the one, and a cotter let in obliquely in

6"
B
606
MODERN STEAM PRACTICE.
the other. In some examples there is an oil-receiver formed on
the brass or cast-iron guides for holding oil for the lubrication of
C
B
B
A, Crosshead. в B, Oil receivers.
B
Fig. 477.-Crosshead showing Oil Receivers.
c, Piston rod and cotter.
the crosshead, while in
others provision is made
on the motion bars. The
guide blocks have occa-
sionally been secured to
the crosshead with stud
bolts, this plan being adop-
ted when blocks have been
made of extra length, and

affording a secure attachment under the circumstances. In mostly
all these examples the part taking the piston rod is turned, and all
the other parts planed or slotted in the machine.

C
A
-14
B
不
​B
-101
D
Fig. 478.-Crosshead with Guide Blocks secured with Bolts.
A, Crosshead. BB, Guide blocks. c, Piston rod and cotter. D, Eye for pump ram. E, Gudgeon.
The motion bars (Figs. 479, 480) are made of scrap iron steeled or
case-hardened. Sometimes solid shear steel bars have been adopted,
while cast-iron has been used with great success. The motion bars
now generally adopted are of a flat section, and are secured with bolts
to the back cylinder cover seats, with side joggles cast on the cover
for their reception; the back end taking the blocks, which are forged
along with the motion plate, or rivetted thereto, the motion plate
being secured to the longitudinal frames of the engine. Sometimes
the motion bars are not connected to the cylinder cover, but are
secured to a front and back motion plate, which is bolted to the
longitudinal framing, flanges being forged on the motion plates for
that purpose. Thin strips of brass or copper are placed between
the motion bars and their seatings; by this means the wear on the
crosshead guides is adjusted by simply filing a little off the lining
LOCOMOTIVE ENGINES.
607
=
222
-1호
​BAIN
2
F
F
ENIN
pieces. When cast-iron motion bars are adopted they are some-
times fitted with a clip at the cylinder end, with a flange cast on the
back end for bolting to the motion plate, and the bar is strengthened
with a vertical feather cast along with it, tapering from nothing at
the end to a sufficient depth at the middle of the bar, this being
required, as the cast-iron is not so well calculated for taking the

B
=3/00
~
M
=mjoo
E
E
E
Fig. 479.—Double Motion Bars.
A, Bracket on motion plate. B, Piston rod.
E. Guide blocks.
O
Crosshead with Brass Guides, &c.
c, Crosshead. D, Crosshead gudgeon.

F F, Motion bar.
E~~
1516
3-
A
strain. Attempts have been made to dispense with the crosshead
and motion bars, this being effected by means of a prolongation of
the piston rod, which is forged along with the crosshead and piston
rod proper, the rod working in a long boss, which is secured to
what would otherwise be termed the motion-bar plate. The piston
rod requires to be of extra diameter for taking the strain, and a
Fig. 480.-Cast-iron Motion Bars, &c.
A, Motion bar. в, Clip. c, Cylinder end.
608
MODERN STEAM PRACTICE.
hollow or tube section has been adopted; this plan for guiding the
piston rod in a true line necessitates a long fork on the connecting
rod. This peculiar arrangement, as applied to the locomotive
engine by Messrs. Sharp & Stewart of Manchester, has not found
much favour. It is, however, decidedly more cheaply executed
than the ordinary motion bars and adjuncts, but we think it
should be confined to agricultural engines, moving at a slow rate
of piston.
The plate for carrying the back end of the motion bars is forged
in some instances, with provision for carrying the end of the pump;
and has flanges at the end fitting against the longitudinal frames,
to which it is securely bolted. In other arrangements the motion
plate is formed of plate iron, with angle-iron flanges for securing
it to the main framing. It is generally made of considerable depth,
with holes cut out for the connecting rods and eccentric motion
rods, and sometimes the plate is carried up and securely rivetted to
the boiler, in fact, forming the support for the boiler; this is to
be preferred to the old method, having the boiler brackets bolted
thereto, and likewise to the rigid framing, as the plate is not so
rigid, yielding to the expansion and contraction of the boiler. The
motion plate for outside-cylinder arrangements is carried beyond
the framing, extending the whole width across the framing, with a
long hole cut out for the wheel coupling rods, working through the
plate extending from nearly the centre of the boiler to within a few
inches of the rails.
Connecting rods.- Much attention has been paid to the con-
struction of the connecting and the coupling rods. The body and
the straps are of scrap iron, with brass bushes and steel cotters.
The length of the connecting rod from centre to centre should be
six times the length of the crank, and even longer when convenient,
shorter connecting rods throwing an undue strain on the motion
bars, causing much friction. In former examples the body of the
connecting rod was turned, but this plan, although cheaper, was
objectionable. Flat sections are now universally adopted, as that
form gives rods much stiffer, and better calculated to take the severe
strains they are subjected to. Long forked connecting rods should,
as far as practicable, be discontinued, as forked ends are not nearly
so strong as plain ends; short forks, however, are extensively
adopted, and are not so objectionable, although we decidedly prefer
single ends.
LOCOMOTIVE ENGINES.
609
F
4
I
315-
E
F
end, and for further security split pins are inserted in holes on the
bottom end bored at a short distance from each other. In other
examples the cotter is prolonged and cut with a screwed part which
passes through a hole in a prolongation of the jib; by this means
the cotter is held in position with jam nuts. The bush and strap at
E
T
N
A
+4=
A, Crank end.
G
|AW=PT=
N
colens
E
F
For inside-cylinder arrangements each end has a butt forged on
the body, which is planed for the reception of the strap, the bushes
being placed between the butts and the loop ends of the straps.
The latter are tightened up with jibs and cotter, by this means.
adjusting the wear on the bushes. The cotter is held with two
side screws for the large end and a single set screw for the small


Colw=
D
F
Fig. 481.-Connecting Rod with Single Ends.
B
1, Oil cup.
B. Crosshead end. cc, Butts. D D, Straps. EE, Jibs and cotters.
H, Set screw.
G, Body.
F F, Brasses.

39
610
MODERN STEAM PRACTICE.
*I
7/12
D
€9
"
91
ened up with a single key and jibs, with side nut for holding the key
in position, as likewise a split pin on the under side. In another
example (Fig. 482) the small end is forked; the bushes at both ends
are lined with white metal; the ends of the bushes are not square, but
A
G
the large end are square, surface thereby being gained for taking the
thrust. The butt has a large hole cut out, for lightening it, tending to
reduce the balance weights placed on and between the spokes of
the driving wheels. The bush for the small end of the rod is tight-


K-- 8 -->
CI
D
ន
22
H
B
E E, Jibs and cotters.
I I, Oil cups.
F F, Brasses.
Fig. 482.-Connecting Rod with Forked End.
B, Crosshead end.
D D, Straps.
HH, Set screws.
cc, Butts.
G, Body of piston.


H
A, Crank end.
LOCOMOTIVE ENGINES.
611
are fitted into parts cut out in the connecting rod and straps, like an
ordinary pillow block for land engines. The strap on the large
end is tightened up with jibs and a single cotter, and at the forked
ends with a single jib and cotter, having set screws and split pins as
before. The cups for lubricating the crank pin and gudgeon for
the crosshead are forged on, and fitted with a siphon pipe and
cover to prevent the oil being thrown out with the rapid revolving
and reciprocating motion the connecting rod is subjected to.
Owing to this rapid motion it is found advisable to secure the
strap at the crank end with two bolts and two nuts to each bolt,

I
F
G

A
H
D
23.
E
I
C
2
Funico
B
H
Fight =

FOL
OF
Fig. 483.-Connecting Rod with Fixed Strap, having Bolts passing through the Strap and Butt.
A, Crank end. B, Crosshead end. cc, Butts. DD, Straps. E, Jib and cotter. F, Cotter
G, Bolts and nuts. H H, Brasses. I I, Oil cups.
thus binding the strap and butt firmly together; there is a single
cotter bearing on the bush for adjusting the wear, the set screws
for holding the cotter in position being screwed into the strap, the
small end in this example having a cotter and two jibs for the bush.
The siphon cups are forged on the straps, and the cover is fitted
with an internal plug bearing on it, and which is held up
with a light spiral spring. In another plan for holding the strap in
a fixed position two sets of jibs and keys are adopted, with joggles
formed on the large butt (Fig. 484). One set draws the strap into
the joggle, where it is firmly held, the cotter being secured with set
screws and split pin, while the other set bears directly on the bush,
and are only used for adjusting the wear. The siphon cup is
forged on the large strap, and the small end is provided with a brass
612
MODERN STEAM PRACTICE.
cup screwed in the strap, which is an advantage when the cup
requires cleaning; but it is preferable to forge them on the large
ends, owing to the violent motion, which is liable to shake brass
cups loose. The slightest derangement in this important part will
with an attentive driver cause a stoppage, perfect lubrication of the
B
B

B
E
"/
6
AIN=
1
cine
C
A
- 5 8
D
D
-310
A
A
C

1-1-2525200
A
10
E
B
Fig. 484.-Connecting Rod with Fixed Strap secured with Jib and Cotter.
A, Body of connecting rod. B B, Brasses. cc, Straps. D, Jibs and cotters. E E, Oil cups.
crank pin being necessary; and indeed all the moving parts of a
locomotive must be plentifully supplied with oil or other lubricant.
In some examples (as Fig. 485), not at all to be commended, dove-
tailed pieces are let into the strap and butt, with a single bolt for secur-
ing them, passing through and through. It is evident that the dove-
tail weakens the strap, and when the strap becomes loose it is sure to
fracture at the weakest part; we therefore consider that the joggles
formed on the butt are to be preferred. Some of the crank-pin bear-
ings are rounded with the bush bored out to suit, while all the bearings
should be well rounded at the corners, thereby materially strength-
ening the shaft. Various other forms of connecting rod ends have
been applied in practice; amongst these we note an example entirely
doing away with the straps (Fig. 487). The large end is cut out em-
bracing three sides of the bush, which is held in position with a plate
on the underside, and bolts passing through the butt, the bush being
adjusted with a single cotter. The small end of the connecting rod
is forked, and is fitted with a long bush, with jib and cotter for
adjusting the bush. In other examples for small ends the wear of
LOCOMOTIVE ENGINES.
613

·3
H
B
E
K
2
D
C
22
E
E
D
G
E
F
D
F
K
·7.
L
1
A
I H
I

A


Figs. 485, 486.-Connecting Rods with Dovetailed Piece let into the Strap, and Rounded Bearing
for the Crank Pin.
A. Crank end. B, Crosshead end.
B, Crosshead end. cc, Butts. DD, Straps. E E, Jibs and cotters. FF, Dovetailed pieces.
G, Bolt,
HH, Brasses.
11, Oil cups.
K K, Set screws. L, Rounded bearing.
614
MODERN STEAM PRACTICE.
the bush is adjusted with a wedge with screwed point and nut, the
end being solid and cut out for the reception of the bush (Fig. 488).
In order to reduce the clearance between the cotters and the
body of the boiler for inside-cylinder arrangements various forms
of connecting-rod ends have been adopted; in some the bush has
been adjusted with bolts and nuts, taking a cap bearing on the
bush, a T form of connecting-rod end being adopted with the distance
piece between the cap and end cast along with the bush (Fig. 489);
these connections have not been much used in the locomotive,
although they have been largely adopted in marine practice.

G
K
08
A
F
Q
G
I
II
D
B
E

A, Crank end.
F, Cotter.
B,
Crosshead end.
GG, Bolts and nuts.
C, Butt.
H, Plate.
Fig. 487.-Connecting Rod with Solid End and Plate.
I I, Brasses.
E, Jib and cotter.
K, Oil cup.
D,
Forked end.


C
E
6
D
A
F
C
B
HO
Fig. 488.-Connecting-rod End with Wedge
Adjustment.
A, Solid end. B, Wedge. c, Oil cup.
D, Brasses.
E
A
B
Fig. 489.-Connecting-rod End fitted with Cap
and Bolts.
A, Crank end. B, T piece. c, Body. D, Cap.
E E, Bolts and nuts. F, Brasses.
Connecting rods for outside-cylinder arrangements materially
differ from those for inside arrangements with cranked shafts, the
end taking the crank pin being much reduced; it is generally
forged solid and cut out for the reception of the bush, which is
LOCOMOTIVE ENGINES.
615
adjusted with a single key, the end for the crosshead being fitted
with strap, jibs, and cotter as for inside-cylinder arrangements.

H
F
-12
₤11 + 5 1/7
B
Q
a
H

G
D
I
A
E
110
A, Crank end.
Fig. 490.-Connecting Rods for Outside Cylinders.
B, Crosshead end.
c, Butt.
D, Strap. E, Solid end. F, Jib and cotter.
G, Cotter and set screws.
H H, Oil cups. II, Brasses.
The crosshead end in some being single, while others are made with
a short fork for taking the crosshead, all the cups for the lubrication


B
O

A
G
H
F
C
H
E
3
2
Fig. 491.-Connecting Rods for Outside Cylinders.
A, Crank end. B, Crosshead end. c, Solid end.
D, Butt. E, Strap.
G, Cotter.
H H, Oil cups.
F, Jib and cotter.
I I, Brasses.
of the crank pin and crosshead gudgeon are generally forged on
along with the butt and strap. In some examples straps are like-
wise used for the crank end, and in some forked ends have been
successfully adopted (Fig. 492), the bush being adjusted with a jib
and cotter; it is evident this form of connection is not so safe as
the solid ends or those fitted with straps; it will be observed that
the jaws of the fork are kept from springing with a tie piece, taking
the two set screws for the cotter.
616
MODERN STEAM PRACTICE.
The rods for coupling the wheels should have the ends forged in
one piece; they are generally fitted with parallel brasses, having an
elongated flange on the same side as the cotter, which is adopted
for adjusting the wear, the cotters being placed each on the same

D

B
E

17
5
A
C
878
ע
"
3
A
Fig. 492.-Connecting Rod for Outside Cylinder
with Forked End.
A, Forked end. B, Jib and cotter. c, Brasses.
D, Oil cup. E, Tie piece.
true distance from centre to centre.
Fig. 493.-Coupling-rod End.
A, Solid end. B, Brasses. c, Cotter and
set screws. D, Oil cup.
side of the crank pins as the other; this is required to preserve the
The cotter is held in position
by two set bolts screwed into snugs formed on the butts, and by
a split pin at the under side of the cotter. Sometimes a metallic
piece is inserted between the bush and the cotter for taking the
strain. The lubricating cups are of brass, or forged on and bored
out, and fitted with siphon pipe having a cotton wick, by which
means a constant supply of oil is kept up, the lubricant falling on
the pin drop by drop. Without this appliance oil poured into the
cup would run to waste, and the pins would soon become serrated;
in fact, the simple application of cotton-wick siphons to the various
oil cups distributed over the locomotive engine tends in a great
measure to its success.
When the leading and trailing wheels are coupled to the driving
wheels, a joint with a pin is introduced; in some cases it is placed
between the driving and trailing wheels, while in others it is placed
between the driving and leading wheels. This joint is located close
up to the bushes, and is introduced to prevent the rod becoming
bent by the irregular vertical motion and vibration of the framing
and wheels, owing to irregularities in the permanent way.
LOCOMOTIVE ENGINES.
617


F
A
□
B
14
| G
A A, Solid ends,
B B, Brasses.
F
C
2-
B
E
A
-3}"″-
D
Fig. 494.-Coupling Rods and Outside Crank Pins.
cc, Cotters and set screws. DD, Crank pins. E, Joint and pin.
}
G||
F
F F, Oil cups. GG, Bodies of rods.
B
A☐


618
MODERN STEAM PRACTICE.
The pins for taking the rods are either fitted into holes bored out
in a solid part formed along with the spokes of the wheel, or
separate cranks are adopted. In some examples the ends of the
coupling rods are quite round, a simple eye being forged on the rod,
which is bored out for the reception of a thick round bush, which is
held in position with a washer and nut, the end of the crank pin
being screwed. In mostly all examples the body of the rod is of
a flat section, while in others it is turned, and in some the top
and bottom are turned and the sides
flattened.

21-
A
B
C
D
回
​G
G
F
Fig. 495.-Coupling-rod End.
A, Butt.
D, Cotter.
E
ADIO
B, Strap. c, Jib and cotter.
E, Oil cup. F, Brasses.
G G, Set screws.
Coupling rods have been fitted
with straps, with two jibs and cotter
for holding the strap rigid, and a
single cotter for adjusting the wear
of the bush, which in many instances
is bored out to fit a spherical-shaped
pin. We certainly prefer the ends of
the coupling rods forged in one piece,
and such ends are universally adopted;
they are better calculated to meet the
violent motion these rods are sub-
jected to. All the parts should be
as rigid as practicable, with no part
liable to shake loose.
Cranked axle.-When the cranked axle is arranged with a main
outside bearing it must have a narrow bearing placed close up to the


E
F
19-
DE
4.....
2' 7" Centres
* 3*
A
·3%.
·7%.
·7/2".
44444/4
G
G
19.
B
Fig. 496.-Cranked Axle.
A, Main body of axle. B, Crank pin. c, Inside journal.
E, Part for outside cranks. F, Part for wheel.
D, Outside journal.
G G, Crank.
cranks, as when the main bearing is outside of the wheels it is impera-
tive that the cranked axle should be supported close up to the
LOCOMOTIVE ENGINES.
619
C
C
cranks; but in many examples of inside-cylinder engines the axles
have no outside bearings, but simply a broad bearing with the side of
the brasses rubbing quite close against the flat sides of the crank.
This plan has been very generally adopted both for broad and narrow
gauge engines; it is certainly much simpler than the cranked axle
having outside bearings on the main framing and likewise narrow
bearings fitted to the horn plates; moreover the breadth over all
is greatly reduced, the outside coupling rods being placed quite
close up to the wheels. In manufacturing cranked axles a long
slab is hammered up, and then swaged down in the middle and at
the ends; the throws are then worked into shape, and the axle is
then twisted at the central part, until the throws are at right angles
with each other-the grain of the iron running across the throws;
by this method they are not so liable to split through. Some
cranked axles are bent with the aid of hydraulic machinery, a long
bar being heated and put into the machine; the throws are formed.
with a die and, mould, the die being pressed up by water power:
these axles give great satisfaction. When the axles are delivered
at the factory the throws are gen-
erally solid with the ordinary
method of construction; they are
then slotted out, and the axle is
then turned in a lathe. All the
corners of the bearings should be
well rounded, as the axle is greatly
strengthened thereby. In some
the crank pin is turned of the
same diameter throughout with
bold curves at the corners, while in
others the pin curves from the
middle to the sides of the crank; by this means greater strength is
obtained over those that are finished parallel. The ends of the crank
throws are rounded at the outside corners, thereby reducing the
weight, while others are left quite square, the extra weight being
balanced on the wheels. In some examples a wrought-iron strap has
been shrunk on each crank, with the view of binding the fibre of the
iron better together; this we consider may be to a certain extent advis-
able, although it adds more weight, which must be properly balanced;
on the other hand, when due attention is paid to the selection of the
scrap iron, with good workmanship, and with the improvements

A
Off
B
Fig. 497.-Straps on Inside Cranks. A, Crank
pin. B, Axle. cc, Straps.
620
MODERN STEAM PRACTICE.
in manufacture, we consider these straps not at all necessary, and
they are but little used in modern practice. With plain driving
axles used for outside-cylinder arrangements the bearings are placed
inside of the wheels in a similar manner as for cranked axles, having
no outside bearings, while the crank pin is rivetted into a hole bored
out in a boss forged along with the wheels. When the wheels
are coupled together the crank pin has two bearings, one for the
coupling rods placed close up to the wheel, while that for the main
connecting rod is placed outside of it considerably overhung, throw-
ing a severe strain on the part, which, fitting into the wheel, is made
conical and rivetted at the end into a countersink, thus making it
very secure. The bearing for the coupling rod on the crank pin is
made larger than what is actually required for the other wheels,
simply to strengthen the pin for taking the strain imparted from
the steam piston and connections. The connecting rod in many
cases is held on with a collar forged along with the pin, while others
have a nut and washer, and some a plain washer with a pin passing
through it. There is likewise a collar turned on the pin between
the two connecting rods, when so fitted, for keeping the brasses
separate, as they would soon tear were they in juxtaposition.
Plain axles consist of four parts, namely, the body or middle, the
C

-12-
B
A
F13/00
១
Fig. 498.-Carrying Axle.
A, Body. B, Journal. c, Part for wheel.
parts for taking the wheels, the journals, and the parts for the
outside cranks. To combine lightness with strength, the axle
should taper from the middle to the raised parts for taking the
wheels, which should be of increased diameter to obtain a large
bearing surface for the eyes of the wheels; in the inside there should
be a shoulder for the nave of the wheel abutting against. When
fitted with outside bearings, the journals are reduced in size, while
the parts for taking the outside cranks are of greater diameter than
the journals. When the axle has only inside bearings all the parts are
generally of the same diameter, excepting the collars for the wheels
and journals. It is preferable, however, to make the part for taking
LOCOMOTIVE ENGINES.
621
the eye of the wheels of increased diameter to secure a larger sur-
face, the boss of the wheel in such cases rubbing closely against
the brasses in the axle boxes, while with collars the nave of the
wheel is kept the breadth of the collar apart. All the journals
should be finished with a tool in the lathe, leaving well-turned curves
at the corners. The old method of using emery to get a smooth
surface has for long been discarded, as particles of the emery got
imbedded in the iron, and soon played sad havoc when the engine
-Centres of Bearings 6 22 -
•*-.7% -.*

-67%
B
7:
グリズ
​A
D
Fig. 499.-Leading and Trailing Axle.
A, Body of axle. B, Journal.
c, Part for outside crank.
D, Part for wheel.
was started. When the wheels are coupled the journals should be
nearly of the same diameters, but this depends on the weight as
adjusted with the springs.
Axles are generally made of scrap iron drawn out at two heats.
When new iron is used it is taken from the puddling furnace, put
through a squeezer, then piled, heated, and rolled twice, and finally
heated, and swaged into shape. There is considerable difference of
opinion as regards the manufacture of axles from scrap iron, on the
one hand, and new iron on the other hand; scrap iron must neces-
sarily vary very much; the pile may be composed of a variety of
qualities of iron, such as old and new, hot short and cold short,
burned and raw; and in the process of heating, one part may be
burning while others are welding; thus it is difficult to pick out
scrap iron that combines all the necessary qualities so essential
in manufacturing a sound axle. The scrap iron generally adopted
in railway workshops is old tyres taken from the carriage wheels,
and this may be considered the best description that can be used for
such forgings. With ordinary scrap iron the pile requires to be
well drawn down in order to secure a uniform grain, as parts of the
pile may be drawn out while other parts may be upset. All iron
is subject to be either more or less burned or worked at too low a
heat; that, combined with bad workmanship, renders it difficult to
say whether new or scrap iron axles are to be preferred; we are
inclined to consider, however, that axles made from new iron of
622
MODERN STEAM PRACTICE.
good quality, and with first-class workmanship, are preferable to
those made from ordinary scrap iron of doubtful quality.
Wheels consist of four parts, namely, the nave, the spokes, the
inside tyre or ring, and the outside tyre. They are manufactured
in a variety of ways; some have wrought-iron rings and plain spokes,
with nave forged on, and some cast-iron naves, with spokes vary-
ing in section: the latter method, however, has now become ob-
solete. In modern practice the nave, spokes, and ring are built
up, and forged in one mass. The spokes are forged with wedge
pieces to form the nave, and T-shaped pieces for the inner tyre
D
B
E
<5%
3/2
or ring; the ends of the
T pieces are bevelled; thus
when the spokes are put to-
gether a series of wedge spaces
are left to be welded up. After
the spokes are forged they are
taken to the grinder to be
ground quite smooth, a re-
volving-stone being used for
that purpose. The spokes are
then put together, and are held
in position with a strap and
screw; the nave is then placed
on the fire and brought to a
welding heat; at the same time a thick washer is brought to a
welding heat in a fire adjacent, two smiths being required, one for
attending to the nave and the other to the washer.

A
으
​Fig. 500.-Wrought-iron Wheel.—^, Nave.
B, Arm. c, Inside tyre. D, Outside tyre.
63A
E, Rivet.
The smith attending to the nave, when it is brought to a proper
heat, gives the screw on the strap an extra turn, thereby forcing the
series of wedge pieces more closely together. When both are ready
the nave is put on an anvil, and the washer is placed on it, and a
few strokes of a suitable steam hammer unite the mass; thus one
side is partly finished, a washer being required for each side, the
other is in like manner welded on; the nave is then dressed off with
hand labour. After the nave is completed the strap is removed
and a straight bar attached, with means of turning the mass over,
so that the wedge space in the ring or tyre can be filled up and
welded bit by bit. The spoke wheel is then taken and placed in
the turning lathe, and the ring turned with a plain surface, at the
same time the eye is bored out.
LOCOMOTIVE ENGINES.
623
;
The outside tyres of iron or steel are generally ordered from the
rolling mills in hoops entire, which are turned out with a plain
surface in the factory. Both spoke-wheel and tyre are then taken back
to the wheel shop, which should be adjacent to the turning depart-
ment, the smith then heats the outer tyre in a furnace for that pur-
pose, the spoke wheel being placed in a circular trough. The tyre,
after being brought to a proper heat, is taken out of the furnace and
placed over the ring on the spoke wheel; the outer tyre having
expanded with being heated, is easily placed over the ring, and
water being let into the trough, it contracts on the ring and
firmly embraces it as it were in one mass. The wheel may then be
fitted to the axles, which have generally the key ways cut in each.
The keys are of steel, and are fitted accurately into the key beds,
and are then driven in with a sledge hammer. The wheels and axle
may then be taken to the turning shop and put in the lathe, the
centres on the axle being left on for that purpose; thus the trods
of the wheels are turned all over and finished off quite truly with
the journals, as the same centres for turning the journals are used
for turning the outer circumference of the wheels.
Six-wheeled engines have generally flanges on all the tyres, for
preventing the engine leaving the rails; but when more wheels are
adopted, with the driving wheels placed in a central position, it is
better to have the tyres for the driving wheels without flanges, so
that the engine can turn round sharp curves easily. A few tap bolts
are fitted to holes tapped through the inner tyre, and partly tapped
in the outer tyre; some are fitted with nuts which are screwed hard
up, and the point of the bolt rivetted over, while the bolt is put in
hot, and the point rivetted over.
Wrought-iron wheels for outside-cylinder engines have the bosses
forged along with the arms for taking the crank pin; weights for
balancing the crank throws, connecting rods, &c., are fitted to the
wheels inside of the inner tyre or ring, having side plates for keeping
them in position, which are held together with bolts rivetted over.
In some the balancing power has been put into the inner tyre, this
being forged of greater thickness at one part for that purpose.
Wheels of small diameter are sometimes made of cast iron, and
are suitable for waggons, &c. The usual practice is to cast the
nave, arms, and ring together, and fit the outside tyre of iron or steel
in the usual manner. The arms are made of a strong sectional area,
as likewise the ring; a T form of arm was formerly adopted, but
624
MODERN STEAM PRACTICE.
in modern practice solid arms are the rule, though some are made
hollow in the casting as well as the naves.
Much attention has
been paid to wheel castings in order to prevent them cracking from
the unequal expansion of the cast iron. A wheel properly propor-
tioned in all its parts will give way if one part is cooled sooner than
another part; for instance, the ring being thinner than the boss,

13
A
B
א
2 61
2
C
00/=
D
2
E
6
1
D
C
A, Nave.
B, Arm.
D, Outside tyre. E, Crank pin and boss.
Fig. 501.-Cast-iron Wheel.
c, Inside tyre.
contracts rapidly, the great body of metal in the nave being still in
a fluid state, which in cooling tears away from the rim; it was there-
fore found necessary to divide the nave, and afterwards fill up the
spaces with iron plates, two wrought-iron hoops being shrunk on the
nave, one on each side, similar to the fly wheel of a land engine.
Cast-iron locomotive wheels are now annealed in a kiln for that pur-
pose. A deep pit made of brickwork is heated red-hot, and while
LOCOMOTIVE ENGINES.
625
the wheel is red-hot it is taken from the mould and placed in the
kiln, which is then covered to prevent access of air; the wheels
taking three or four days to cool, must necessarily cool equally, and
this treatment prevents internal strain.
Sometimes large wheels are cast in a chill on the trod, and it is
a fact worth noting that the chill is not destroyed by the annealing
process, as no heat below that which the cast iron has when the par-
ticles taking the chill are solidified affects the peculiar hardness of
the metal. There are certain objections to chilled wheels: they
cannot always be cast of uniform diameter, and should the nave be
bored out eccentrically much harm will ensue by the wheels wearing
unequally. Besides, when such wheels are acted on by brakes, if
care is not taken to prevent their locking, flat places may be formed
on them by the brakes, which will prove very injurious, and the slid-
ing action will also cause the chill to get soft. These wheels, how-
ever, are much cheaper than those fitted with iron or steel tyres, and
have an advantage over the latter, inasmuch as when the line of rail-
way is rough the cast-iron chilled wheels are not liable to become
indented on the flanges, which sometimes takes place to such an
extent with wrought-iron tyres as to endanger the safety of the
engine. Wheels from 3 to 4 feet are sometimes cast in the plate
or disc form, thereby lessening the tendency to fracture. The
balance weight is cast along with the cast-iron wheels, whether
the disc or radial-arm form is adopted.
Outside cranks.-When the axles are fitted with bearings placed
outside of the wheels, with the wheels coupled together, wrought-iron
cranks are fitted to the ends of the axles, having one large key way
and two smaller ones for keeping the crank firmly on the axle.
The crank pin is forged along with the main body of the crank; when
six wheels are coupled together the width of the crank pin bearing
for the middle crank is made in excess of the other two to allow for
any lateral motion. The sides of the crank are quite straight from
boss to boss; thus they are more easily planed, and at the same time
the crank is much stronger. In other arrangements with inside bear-
ings for the axles, the crank pin for the coupling rod is let into an
eye bored out in a part forged on, or cast along with the nave of
the wheel. The part fitting into the wheel is tapered and securely
rivetted in. A set screw bearing on the side of the tapered part is
screwed into a hole tapped through the eye, thus preventing the pin
from turning; this can be done likewise with a short key let into
40
626
MODERN STEAM PRACTICE.
the pin at the neck, which fits into a hole cut in the eye. On
the end of the pin a collar is turned for keeping the rod in
A
2%...
-3/16
-274-
12.
·34
B
D
674---
- 178
C
3¾....
D
D
Fig. 502.-Outside Cranks.
A, Crank pin. B, Body of crank. c, Eye of crank.
DD, Keys.
position, while others have
a screwed part at the
end, having a nut and
washer bearing on the
side of the brasses of the
coupling rod. When the
coupling rod takes the
crank pin for the piston
connecting rod, the for-
mer being next the wheel,
the pin is enlarged over
the others in order to
strengthen the pin, as the
overhang is considerable.
In some examples the
pins for the outside cranks
are turned spherical, with
the brasses in the rods


bored out to suit, thus the rod swivels as it were with the motion,
tending to throw less strain on the pins.
Framing and axle boxes.-The framing in all modern examples
extends between the front or buffer beam and the back or draw beam,
and is either double or single. With the former, suited for outside
bearings, the frame was originally composed of two thin plates with
wood between, held together with rivets, while the inside frame or
horn plate was wholly of wrought iron.
When inside bearings are adopted the frame plate is of wrought
iron, a plain parallel beam of considerable width and thickness, to
which are fitted the horn plates for the axle boxes, but some have
the horn plates and stays forged all in one piece. The framing is
stiffened by the cylinders when placed between them at the front,
the motion bar plate forms another source of stiffening, then comes
a plate fitted between the frames in front of the fire box, while at
the back of the fire box, plating is arranged for taking the drag links,
and in some instances a casting is introduced, thus giving weight
for adhesion in the hind wheels, and also strengthening the framing for
taking the drag links, the pull and thrust being taken directly on the
framing. Double frames are likewise made entirely of wrought iron.
LOCOMOTIVE ENGINES.
627

Plate
E
·8/8*-
24
D
K
-29
7 874
*6
4:0:-
-1138
2%
5 feet Wheels
3.6..
18
Iz thick
6
23 8
A
9
B
O
Inclination of
Cylinders
Fig. 503.-Plain Plate Framing.
Winick
2%
8 thick
H
7'84
D
4 6
A, Frame plate. B, Horn plate.
G, Guard.
c, Horn plates for the axle boxes. D D, Stays.
E, Draw beam.
H, Leading wheels. 1, Driving wheels. K, Trailing wheels.
F, Buffer beam.
·
-15
& Bolts
F
O

3/8 Plate
628
MODERN STEAM PRACTICE.
The front beam for taking the compression strain, imparted
through the buffers, is generally made of wood fitted directly to the
frame ends, a flange being formed on the ends for bolting the beam
to; sometimes a plate is introduced between the beam and the frame
ends, an angle iron fastening being adopted to which it is firmly
rivetted. The wooden beam in some cases extends the whole breadth
across the light frame work and platform fitted on the top of the
framing for passing round the engine, but it is preferable to end the
beam at the longitudinal main framing, or otherwise bevel it from
that point to each end; thus the blow imparted through the buffers
is taken directly on the main framing, and cannot affect the light
angle-iron frame for carrying the foot plates; moreover, the beam
to a certain extent acts as spring beam for taking the shock. The
draw hook and chain in front of the buffer beam, which is used when
the engine is going backwards, is secured with an eye bolt passing
through the buffer beam and plate, having a nut bearing on the plate.
The hind or draw beam is generally of wrought iron secured to
flanges formed on the longitudinal frames; a framework of angle
iron and plates is rivetted to the beam, spreading over a consider-
able space under the foot plate between the main frames to which
it is securely rivetted; this framework carries the pin for the draw
shackle, and consequently, as the whole strain of the engine comes
on this part of the framing in the first instance, it requires to be
strongly united to the longitudinal beams forming the main frame.
In some instances a framework of cast iron has been adopted,
carried from the draw beam forward to the back of the fire box.
An angle piece is rivetted to the fire box; by this means the boiler
is partly supported on the cast-iron framing, but in most instances
the angle irons are rivetted to the sides of the fire box, taking an
angle iron rivetted to the frame plates. The boiler has the power
of expanding and contracting without straining the main frame-
work, owing to the bolt holes in the angle iron being oblong, a very
important matter to consider in the construction of the locomotive,
for when the boiler is rigidly held with the framework without the
power of expanding, rupture must eventually take place at some
part, and more than likely in the body of the boiler. The other
frame brackets for supporting the body of the boiler are formed by
a continuation of the motion-bar plates, and at the front end the
smoke box is secured to the main framing, the boiler expanding
from that point quite independent of the framing.
LOCOMOTIVE ENGINES.
629
When inside bearings for the cranked axle are used with outside
bearings for the leading and trailing axles, both of the frame plates
are in some examples made of wrought iron, having the horn plates
or plates for taking the guides for the axle boxes forged on; the

2441
92
8
C
*.3%
F
ทา
64
-6
B
ייד
-6%-
8.*.
F
Tok
A
11
Fig. 504.-Inside Bearing and Horn Plate.
F
10.94
<---20ins Radius
A, Inside horn plate.
B, Axle box.
E, Spring.
cc, Guides for axle box. D, Hollow distance piece and bolt.
FF, Spring harness. G, Spring pin.
framing is stiffened with cross pieces between the two frame plates
at each side, and likewise stiffened between the two inside ones.
The buffer beam is carried across as before, the compressive strain
imparted through the buffers being in a more direct line with the
outside frame plate, to which it is securely attached, as likewise to
the inside frame, having a plate between the buffer beam and the
end of the framing.
The back end or drag beam is fitted as before with plate and angle
iron framing for taking the drag link, the framework being securely
attached between the two inside frames.
When the driving and trailing axles have inside bearings, and the
630
MODERN STEAM PRACTICE.
leading axle has outside bearings, double frames are used, and when
the cylinders are placed outside, or between the two frames at each
side, the outside frame is made of reduced thickness from the
curved part of the horn plate at the top for taking the leading axle
to the hind beam. In front of the driving wheel a plate joins the
two side frames, to which the double-motion bars for the piston cross-
head are firmly secured, as they are also to the cylinder cover.
These double frames no doubt tend to make a much stronger
framing, although it is not desirable, with outside-cylinder arrange-
ments, to receive the shock of the buffer beam on the outside frame.
Double wrought-iron plate framing is likewise used for inside-
cylinder arrangements, having the driving and hind wheels coupled,
the leading, driving, and trailing wheels being fitted with outside
bearings, while an additional inside bearing in such cases must be
used for the cranked axle, supporting it quite up to the sides of the
crank throws.
Wrought-iron plate framing is now generally adopted for all
classes of engines; when so fitted the hind or drag beam is some-
times made of wood, with an outside plate running across and bent
in at the ends for taking the longitudinal beams, having a short
plate interposed between the beam and the ends of the main framing,
the part for taking the drag shackle being made of plate and angle
iron, securely rivetted to the two inside frames and to the drag beam
with angle irons, thus making a very secure attachment.
For outside-cylinder arrangements the side frames in some
examples are connected together by one or more water tanks, of
which they form the sides, the whole being framed on angle iron,
with all joints rivetted and caulked the same way as a boiler. By
this arrangement, the tanks being an integral part of the framing,
great rigidity is secured. This principle is applicable to locomotives
variously constructed as regards the number and position of the
wheels.
It is customary with outside-cylinder arrangements to make the
framing deeper at that part where the cylinders are attached, a hole
being cut out in the frame for allowing the valve casing to pass
through; some merely undercut the framing, while with inclined
cylinders, flanges are cast on for bolting to one or both of the frame
plates.
The axle guards, to which the guides for the axle boxes are
bolted, are forged along with the frame plates, or in separate pieces,
LOCOMOTIVE ENGINES.
631

d
d
=34
Ъ
α
Fin100
d
M
IN
Fi/00
19
11
7
e
16
b
a
C
1
812
-10
e
d
C
a, Axle box.
A-
e
d
T
d
Figs. 505, 506.-Axle Boxes, &c.
6, Upper bush. c, Lower bush. d, Guides.
b
a
d
d.
α
4.
2
e
CNN N
e, Ties.
C
о
વાં
632
MODERN STEAM PRACTICE.
securely rivetted thereto. When the framing is composed of two
thin plates, with a wooden beam between them, the guards are
formed along with the frame plating; long guards so constructed
require to be well stiffened by the axle-box guides, which in some
instances are carried up between the plates into the timber, and
securely bolted through and through the frame plates and timber.
The guides are strengthened with flanges and bosses, having holes
cast through, and are securely rivetted to the guard plates; they
are also fitted with a distance piece and bolt underneath the axle
box, thereby preventing the guard plates from springing; in other
examples a tie bar with bolts is fitted to the guard plates. When
a wrought-iron single frame plate is adopted with two guard plates
rivetted thereto, guides of wrought iron are sometimes used of a T
section, which are securely rivetted between the guard plates, the
guards having a flat tie bar taking all the axles, and being inclined
upwards at the end, taking the under side of the buffer beam. When
the guard plates are forged along with the single frame plates the
guide plates are of wrought or cast iron securely rivetted thereto,
having a clip stay bar secured with bolts and nuts to the guard
plates. In some cases both the guard and guide plates are forged
along with the frame plate, thereby dispensing with rivetting,
the guide plate having a distance piece with bolt passing through,
with nut and jam nut, for securing the bolt. In others the guide
plates are cast together, having sides and top piece, with a boss on
the top, having a hole for the spring-bearing pin passing through.
Sometimes one side of the guide plate is movable, with a wedge
adjustment, so that the wear of the axle boxes, caused by the
knocking action due to the working of the engine, can be
adjusted.
The guide plates are planed on the surface and sides, and should
be quite parallel. The guard plates are likewise planed on the
edge, fitting accurately against the guide plates, which are likewise
planed on the part the guard plates fit against. In fitting up the
guide plates they should be screwed hard up against the guard
plates, and then all the rivet holes made fair prior to rivetting up.
The axle boxes are of cast iron with brass bushes; flanges are
cast on each side of the box, which bear on the sides of the guide
plates, thus guiding the axle box vertically; the working sides of
the axle boxes and flanges are planed, bearing against the planed
surface of the guide plates. With the springs placed above the
LOCOMOTIVE ENGINES.
633
A
B
axle box, the whole weight is taken on the top, the spring-bearing
pin resting on the cast iron, a boss with a part cast out or bored
out being left on, forming a step
for the end of the pin. The sides
of the axle boxes are from 3/4 to
I inch in thickness; but when
the springs are underneath the
axle boxes the sides require to
be much thicker, as the weight
is taken through the sides. A
wrought-iron strap has been
used to strengthen the axle
boxes; the strap is bent over
the box, passing down on each
side, the pin for taking the
spring shackle passing through
the strap. Wrought-iron axle
boxes have been used; they are of course much stronger, but
they do not wear so well as the cast-iron ones; solid brass, and
Muntz metal axle boxes have likewise been adopted for underhung
spring arrangements, the brass sides being 1½ inch in thickness,
but of course they can be made much thinner, when a wrought-
iron strap is likewise used.


C
Fig. 507.-Brass Axle Box with Wrought-iron Strap.
A, Axle box. B, Strap. c, Shackle.
The brass bushes for the axle boxes are quite circular, bored out
parallel in some, while in other arrangements the bearing tapers
from the centre, where it is small, to a larger diameter at the
sides, the journal being made accordingly. The bush should be
well fitted into the axle box at the top and sides; it is preferable
that the top surface should bear all over, but the sides may have
fitting strips, thus lessening the labour in fitting up. Flanges for
holding the bush in its place are cast along with the top bush,
and are likewise accurately fitted into the axle box. The bottom
bush is a mere shell of cast iron, fitted into the bottom part of the
axle box, and is held in position with two pins, passing through the
sides of the axle box and bush. The top part of the axle box must
be made of considerable thickness for taking the weight imparted
through the springs; it is formed with a circular seat for the spring
pin, but sometimes two spring pins are used of a flat section. The
sides of the axle box project above the crown, forming a grease cup
for the tallow and oil used in lubricating the journals. The bush
634
MODERN STEAM PRACTICE.
for the journals should be bored out about th of an inch larger
than the journal, as they are not so liable to heat when made a
C
B
A
と
​*10
10
*PO|-
12″ 2
υ
Mia
E
D




HO
Outside Driving Axle Box.
Figs. 508, 509.-Axle Boxes with Tapered Bearing.
Inside Driving Axle Box.
A, Axle box. B, Brasses. C,
A
c, Oil cup. DD, Holes for siphon wicks. E, Boss and hole for spring pin.
little slack in the first instance.
The grease chambers should be
fitted with two siphon tubes, which are screwed into the top part of
the axle box, and provided with cotton wicks, the wicks insuring by
capillary action a constant and steady flow of oil, or other fluid lubri-
cant; holes are bored through the bushes, and grooves are cut from
hole to hole in the brass, thus allowing the oil to flow along the top
part of the journal. Sometimes the grooves have been cut diagon-
ally from each hole; this plan is not so good as the former, as the oil
runs greatly to waste; whereas, when a groove is cut in the brass
along the top, the lubricant flows on the top of the journal, where it
is most required.
Sometimes a separate oil chamber is cast on the top of the axle
box, provided with a cover, and siphon tubes and wicks; and for
the leading and trailing axles, with the wheels uncoupled, the axle
box has an outside plate cast along with it, which prevents dust and
grit from destroying the surface of the journal. In some arṛange-
ments the lubricating cup can be removed through the hinged cover
at the end, while the under shell is so constructed as to catch the
waste oil, thus providing a very efficient mode of lubricating the
LOCOMOTIVE ENGINES.
635
journal, the pin for the spring bearing upon the top of the chamber,
where the oil cup is placed. Sometimes the axle boxes for the


A
B
B
B
6
D
62.
Fig. 510.-Axle Box with Covering Plate.
A, Axle box. B, Plate cast on. c, Oil cup.
Fig. 511.-Axle Box with separate Oil Cups, &c.
A, Axle box. B, Oil cup. c, Hinged cover.
D, Recess at bottom.
driving axle are fitted with wedge pieces between the flanges, one
on each side, acting as guide plates, but adjustable at pleasure,
these wedge pieces sliding on guides which are rivetted to the
frames. At the top and narrow end of the wedge a round part is
forged on, turned, and cut with a screwed thread, which, passing
through a hole in a bracket rivetted to the frame, the wedges are
adjusted and held in position with a nut bearing on the top and


C
A
G
F
B
E
Fig. 512.-Guide for Axle Box with Wedge Adjustment.
A, Axle-box guide. B, Wedge. c, Horn plate. D, Adjusting bolt. E, Set screw. F, Hole for the spring
pin. G, Tie bar.
bottom of the bracket. In another arrangement a single wedge is
adopted on one side, while the other side of the axle box has a
plain guide; the wedge piece is the entire breadth between the
flanges, and is drawn up with a screwed part, which is forged along
with the wedge as in the preceding example. In Figs. 512 and
512A is an arrangement of adjusting wedge and axle box fitted to
636
MODERN STEAM PRACTICE.
more recent engines. The guide is made all in one piece, and
securely rivetted to the horn plate. The adjusting bolt for the
wedge is at the bottom, the nuts bearing on the part forged on the
tie bar, while the adjusting bolt passes through a slot formed on
A
Them!
E
F
B
E
ليا
F


D
C
Fig. 512A.—A, Axle box.
B, Top bush.
c, Bottom. DD, Pins for securing the bottom part.
EE, Oil cups. F, Spring pin.
the guide.
This example of wedge pieces is fitted by some
makers to the back of all coupled axles. The inside bearing used
for cranked axles, when fitted with bearings outside of the wheels,
is likewise, fitted with wedges in some examples, one on each side
of the horn bar, having the guides forged thereon. The wedges are
cut with a groove which works in a feather on the guide pieces.
The tightening parts are forged on and cut with a thread, and are
longer than in the previous examples, passing up through elongated
holes on the top of the horn bar, having a nut and a jam nut for
each wedge. The jaws of the guide pieces have a long ferrule at the
bottom, with a bolt passing through, to prevent the jaws springing.
Springs and harness.-Springs are flexible beams, composed of
thin steel plates, loaded at the middle, and free to move at the ends.
Ordinary springs are much deeper at the middle than at the ends.
This is required to obtain uniform flexibility throughout, the plates.
decreasing in length towards the centre. Every part of a spring
should yield equally throughout. If any part of a spring is more
rigid than another part, it is between those parts that the spring
will give way, simply because the portion that is the most flexible
will become unduly strained. Springs that are properly constructed,
and loaded within the limits of their capacity for carrying weight,
deflect through equal spaces for equal additions of weight applied,
when the span is sensibly constant. When the compass of a spring
is considerable the span or length of the spring must increase with
the weight applied. The elastic strength of a spring is measured
by the weight necessary to cause a given deflection, and vice versa.
LOCOMOTIVE ENGINES.
637
The strength is measured by the greatest weight the spring can
carry without giving way; when over-weighted, the symptoms of
rupture consist in the greater apparent elasticity of the spring, or a
greater deflection under a given increase of weight, independently
of what may be due to an increase of length or span. That point
at which a decided change takes place is an index to the strength of
the spring. Ordinary springs, when loaded, are 2 feet 8 inches from
centre to centre, and when unloaded, 2 feet 74 inches from centre
to centre, and have a set of 54 inches from the point of suspension
to the top of the plates; the breadth of the plates is usually 4 inches.
The following table illustrates the constancy of the elasticity for
sensibly equal spans, and its slight increase as the weight carried
is increased is due to the increase of
span:
DEFLECTION UNDER GIVEN LOADS.-Span in working order, 30 inches.
2 plates of inch in thickness; 14 plates off inch in thickness—16 in all, 4 in. broad.

Compass Measured
inches.
Span Measured
to the Centre of
Suspension.
inches.
Loads.
to the Centre of
Suspension.
Total
Deflection.
cwts.
inches.
о
5ğ full.
O
28990
35
518
5
16
2913
40
513%
7
1 6
2916
45
51% full.
full.
298
50
5
full.
2916
55
4150505
16
11 full.
29/12
60
43 bare.
1 2
18
2919
65
42 full.
7
8
70
411 full.
15
16
2911 bare.
2911 full.
75
48
I
full.
80
41% bare.
Ι
I full.
299
291800
13
85.
41% full.
116
90
43 full.
I
5
95
416
100
41
H
200
29/
30
ko
30
full.
3011/0
after shak-
41
1 (1 set).
301 full.
ing lever.
It will be found that the flexibility is increased 26 times when
the span is a trifle over 30 inches. This extension is entirely due
to the weight applied and to the great compass of the spring. The
elastic strength of a spring is one thing, and its elasticity when
unduly loaded is another. The strength varies as the span or
length between the supports inversely, as the depth or number of
plates directly, as the square of the thickness of the plates, and as
the breadth of the plates; while the elasticity varies as the cube of
the span, as the depth or number of plates inversely, and as the
breadth of the plates.
638
MODERN STEAM PRACTICE.
The flexibility of the engine springs varies in practice from 4 to
I inch per ton of load, and in some is even as low as % of an inch.
Springs should be easy of action, and should be more or less flexible
to meet the requirements. The springs fitted to the axle boxes of
the leading wheels should generally have the least flexibility, as from
the severe strain due to the irregularities of motion of the engine,
and imperfections in the permanent way, their springs are very
severely tested. In a six-wheeled engine, having the centre wheels
as the drivers, the springs fitted to the driving axle boxes should
be made of great elasticity, so that the wheels have always a grip
on the rails, maintaining the full tractive load as equally as possible;
more especially as the load on the driving wheels being the greatest
the rails may yield with the weight, and partially lose a portion of
adhesion or traction due to more weight being thrown on to the
hind spring. The latter should be of great flexibility, so as to yield to
the driving springs when the wheels sink from unevenness or sink-
ing of the rails. At the same time the hind springs should be of
sufficient elastic strength to steady the motion of the engine.
In engines having the hind wheels coupled to the drivers, the springs
may have an elasticity of ½ an inch per ton of load. For
engines much overhung either before or behind 4 of an inch per
ton should be allowed for the elasticity of the springs. If the
overhang be behind it should be reduced to % of an inch per ton
of load; and in six-wheeled coupled engines, running at low speed,
the flexibility need not be more than 4 or of an inch per ton
of load.
16
The springs most commonly adopted consist of steel plates in
close contact with each other for their entire length, with wrought-
iron eyes forged at the ends of the top plate, to which the links are
secured with a pin passing through a hole bored in the eye. This
form of spring from long practical use has been found to answer
all the requirements. In some places where there is not much
ventilation, and a good deal of moisture, as in the draw springs under-
neath the framing, close plated springs are not so good as open
springs, owing to moisture getting in between the plates, which soon
become rusty and stiff, and cease to act in a satisfactory manner.
The plates of the springs are kept fair with each other sideways by
studs punched up at the ends of each plate, entering and sliding in
slots in the plate adjacent. Modern springs have a longer part
punched in a similar way, fitting into a hollow in the plate adja-
LOCOMOTIVE ENGINES.
639
cent; this ridge and furrow gives greater strength for preventing the
plates moving either longways or sideways. The plates are likewise
held in position with a wrought-iron hoop shrunk on at the middle,
binding the whole together, and fitted with a boss and hole to take
the end of the spring pin, which bears on the axle box. The springs
are arranged above the axle in some cases and below the axle in
others, there being independent springs for each axle box; while in
others the trailing wheels are sometimes fitted with one spring for
both axle boxes, arranged across the engine below the foot plate.
The springs are generally fitted with scroll or solid ends for taking
the links and pins, and in some flat ends are adopted.

B
2 5
#
3-
A
B
C
Fig. 513.-Spring with Plain Link Harness.
A, Spring. B B, Harness. c, Spring pin.
The most simple description of spring harness has one link let
into jaws formed on the solid ends of the plates, with a pin passing
through the eyes formed on the top plate, the bottom end of the
link being secured to the framework with a pin, supported with a
bracket rivetted to the frame. All these pins should be fitted with
a washer at the end, and a split pin passing through the main pin.
Another plan adopted for single wrought-iron frame plates has two
links, one on each side, with a raised boss at the bottom end, the
top and bottom being secured with a pin taking the links and the
spring at the top, and another the links and frame at the bottom
end. The spring pin for taking the thrust on the top of the axle
box is round in some, with a reduced part turned at the top, which
fits into a hole bored in the central hoop, and sometimes passing
through the spring and hoop, and secured with a nut at the top. In
others, the spring pins are of a flat section, having two pins for each
640
MODERN STEAM PRACTICE.
spring, one on each side of the frame. These are guided by means
of a wrought-iron bracket rivetted to the frame, with holes bored to
suit the round pins, and a flat part formed in the bracket for the flat
pins, the bottom end of the pin resting in a part formed on the top
of the axle box. In other forms of spring harness adopted for solid
eyes, formed on the top plates, the links are made with a clip piece
at the top embracing the eye, thus no pins are required, the weight
being taken directly on the clips.
When plain links and pins are adopted the spring, when once set,
cannot be altered; this is the only inconvenience attending so simple
an arrangement. It is considered, however, in many examples that
the spring harness should be so constructed that the spring can be
tightened up, as it were, or slackened at pleasure. With that object
in view a box form of link has been adopted, made with jaws for
taking the spring ends; the bottom part of the link is different, being
made with an eye and pin for passing through the framing. It is
likewise screwed for part of its length, having a nut which bears on
the bottom part of the top piece by simply turning the nut, when
the weight is on the spring. It can be shortened or lengthened as
required, by this means adjusting the spring to the greatest nicety.


о
O
о
CO
о

10:
O
D
6%
о
-B
о
-3/2
B
17 Plates 3/2 × 5/8
A
Fig. 514.-Flat-ended-Spring and Harness.
A, Spring. B, Shackle. cc, Shoes. D, Axle box.
When the springs are flattened at the end the link is simply a
round bar, with an eye and pin for the bottom end, and a raised
LOCOMOTIVE ENGINES.
641
screwed part for the top end, which passes through an elongated
hole in the ends of the spring, the spring being adjusted with a nut
on the top, having a jam nut and split pin passing through the end
of the link, and in some a simple strap is indented in the ends, with
a pin for securing the strap to the framing. When flat-ended springs
are arranged underneath the axle (Fig. 514), the spring is connected
to the axle box with two side links and pins, taking a snug on the
central hoop on the spring; a snug is likewise cast on the bottom
half of the axle box bush, which is made of extra strength to take
the strain. Shoes are fitted to the frame or horn plates, having
projecting flanges to prevent the spring moving sideways.
When transverse springs are adopted the spring harness is arranged
at the middle, the spring working in some cases between the trans-

B
A
O
B
Fig. 515.-Transverse Spring.
A, Spring. B B, Axle boxes.
BB,
verse plates, which are rivetted to the framing, and the spring is set
up with a single nut and screwed piece forged along with the cen-
tral hoop. Volute springs have been used for the hind axles; the
vertical pin for taking the thrust on the axle box has a plate at the
top, recessed for two volute springs, one on each side on the top of
the springs; another plate is placed so as to bear on the small flat
end of the springs; a bolt passes through each end down the centre
of the springs, and through the bottom plate, these bolts passing
through holes in brackets which are rivetted to the main frame; the
bolts are screwed at the bottom, and the springs are adjusted with
a nut and jam nut on each. The thrust pin should be guided with
a bracket, placed quite close to the under side of the bottom plate.
These springs certainly occupy less space, but we prefer flat curved
41
642
MODERN STEAM PRACTICE.
springs as usually constructed, as their action is easy, and better
calculated in every respect to meet the requirements. India-rubber
springs have been tried, but have proved a complete failure, as they
get crushed, and at times settle into a rigid mass; moreover they
are very quick in action, and are very destructive to the machinery
and permanent way; in summer, also, they get soft, and in winter
hard, and should oil get near them they deteriorate rapidly.
Compensating levers. To make the action of the springs more
perfect, they are coupled together in some instances with com-

A
a
C
Ъ
D
B
Fig. 516.-Compensating Lever.
A B C, Springs. D, Compensating lever. a b, Links joining lever. c, Fulcrum of lever.
pensating levers. Thus the loads on the springs are equilibrated,
as any deflection in either spring from the motion of the engine
and imperfections in the permanent way is transmitted to the other
spring. The compensating lever is underneath the framing, and
may be arranged with a long and short end, or with the fulcrum
in the middle of the lever. In some arrangements the leading and
driving springs are so fitted, while in others the driving and trailing
springs are coupled to the lever, while others have only springs
fitted to the driving axles, the elasticity of the hind bearing being
transmitted from the driving spring through the compensating lever,
which is directly attached to the hind axle box with a link con-
nection, as shown in the American style of trussed framing.
When there is a moderate distance between the wheels, the centres
being say 5 feet and under apart, a single spring is placed between
the wheels, located on the top of the framing, as shown in Fig.
518, fitted to the bogie in front. In this arrangement the spring
itself is the compensating lever. The concussion from the wheels is
taken directly on the ends of the spring, while the deflection at one end
is transmitted to the other axle through the spring itself, the mechan-
ism thus being simplified, while the action is more perfect. For a
greater distance between the centres of the wheels a lever of the same
LOCOMOTIVE ENGINES.
643
span as the wheel centres is introduced, with pins bearing directly on
the axle boxes. The ends of the spring are linked to the framing,

L
A
A
A
B

B
Figs. 517, 518.-American Methods of Coupling the Springs.
A A, Springs. B B, Compensating levers.
while the butt of the spring is supported by the lever; thus equal
loads are put on the axles. In some cases the springs are inverted,

B
回
​Fig. 519.-Inverted Spring and Compensating Lever.
A, Inverted spring on bogie. B, Compensating lever. c, Spring.
butting against the frame, and connected with links to the com-
pensating beams, the latter being jointed to the axle boxes. The
action is very easy, insuring a constant load on all the axles, but at
the same time it confines the spring base to one half of the wheel
base, which is injurious from the overhanging parts at each end.
Various other arrangements may be adopted; and sometimes the
644
MODERN STEAM PRACTICE.
link is fitted with india-rubber washers, placed between two metallic
ones butting against a swivelling piece, which is fitted to a jaw formed
at each end of the compensating lever, having a nut on the link for

A
B
B
Fig. 520.-Inverted Springs and Compensating Levers.
A A, Springs. B B, Compensating levers.
adjusting the load; these india-rubber washers tend to soften the
action; the other links are fitted likewise with washers bearing on the
under side of the frame.
Bogie carriage.-The bogie carriage is introduced in front of the
engine to assist or ease the rubbing of the flanges of the wheels against
the rails in rounding sharp curves. It is placed underneath the main
framing, and is entirely separate from it, being free to move on a cen-
tral axis either way. In some six-wheeled engines the centre or
driving wheels are left without flanges, with the same object in view,
while in all engines the flanges for the centre wheels are reduced in
thickness, or, in other words, have more clearance from the side of
the rails. If the flanges were to grip the rails, the strain on the framing
would be very severe, and when the curve is very sharp the engine
might be thrown off the rails. The object of the bogie carriage is to
prevent this. It provides a long wheel base, combining the advan-
tage of an ordinary eight-wheeled engine as used for comparatively
straight lines of railway, with the advantage of a short wheel base,
when the curves are very sharp. In fact, the front bogie may be
swivelling into a sharp curve while the driving and hind wheels are
on a straight part of the line, as when crossing from one line of rails
to the other line at the points. The bogie carriage is a frame of
wrought iron carried on four wheels, with springs and axle boxes as
in ordinary frames; two plates on edge pass transversely between
the side frames, and are trussed with plates from the corners. At
the centre of the bogie, where the tie plates radiate from, a circular
boss is formed, which is bored out for taking a ball, thus forming a
universal ball-and-socket joint, the ball being securely fastened with
LOCOMOTIVE ENGINES.
645
plate brackets to the under side of the boiler, and having a projec-
tion forged on, with screwed part and nut bearing on the under side
of the bogie frame; this pin has sufficient clearance in the hole to
suit the inclination of the bogie frame in either direction. The frame,
being pivoted on a ball, can more easily move in any direction. In
this form of bogie the front part of the engine is entirely supported

F
B
C
2
--2.3
A
-2'0″-
E
4
1'72.
4.2
"
B
2.3

3.702
Fig. 521.-Bogie Carriage.
5:8".
A, Bogie frame. BD, Wheels. cc, Springs. D, Centre of motion.
E E, Sliding pieces. F, Engine frame.
on the ball. In some of the centre bearing description the ball is
dispensed with, and the load carried upon a broad flat circular seat;
others rotate on a pin with side sliding pieces fitted on the top of
the bogie frame, corresponding pieces being fitted to the main
framing of the engine, or to the carrying plate, so that the bogie
can move transversely and radially, while some sliding pieces are
t
646
MODERN STEAM PRACTICE.
cast along with the cylinder, and strongly bracketed in the casting,
and secured to the under side of the smoke box. These side sliding
pieces are quite flat in some cases, and in others are formed on an
obtuse wedge or double incline for the transverse motion of the
bogie; the front part of the engine lifting, as it were, when the bogie
is striking a curve, the bogie being free to move 1 ½ inch either way or
rather sideways, and sinking into the flat v-shaped piece when on a
straight part of the line. It is evident with this form of sliding side
piece, that the friction must be very great, and it is simply introduced
to maintain the bogie in an even line with the other wheels when
on a straight part of the line of railway. In some modern examples
(Fig. 521), mostly applied to American engines, the curves on some
of the American railways being very quick, the sliding pieces, fitted
to the main framing of the engine, rest on a segmental roller fitted
to the bogie frame on each side, the axis of this roller being secured
to the frame; with this provision the swivelling action is very easy.
Stops are generally fitted to prevent the bogie turning round too far.
Buffers, couplings, rail guards, sand boxes, &c.—The buffers,
fitted to the front beam or buffer beam of ordinary engines, and
likewise to the front and hind beams of tank engines, are of the
metallic description, consisting of a volute spring placed in a
cylindrical box bolted to the frame, having a telescopic piece cast
with a flange, and fitted with a wooden buffing piece. The spring has
a bolt passing through, taking the telescope piece and cylindrical
box, thus holding the spring and telescope piece in position; in the
act of buffing the spring is compressed, while the telescopic piece
slides in the box, sufficient clearance at the end being left to suit
the range of the spring. These springs are in some examples fitted
between the engine and tender.
The engine is coupled to the tender with a rigid connection in some
cases and an elastic connection in others. With the former a right and
left-hand screw, having a bar for tightening up, is used; each screw
passes through a nut, fitted with journals, taking a link, which is
secured by a bolt passing through brackets on the engine and tender
beams; the bolts are prevented from lifting by means of split cotters
bearing on the under side of the brackets. The engine beam is fitted
with a cast-iron block having a convex surface, and on the tender
beam a block is fitted with a concave surface, both of the blocks
being rounded vertically; by this means they are enabled to take
the vertical and swivelling motion of the engine and tender, the
LOCOMOTIVE ENGINES.
647
blocks being drawn into juxtaposition with the right and left hand
screw. The tender is sometimes fitted with buffers, as on the front of
the engine, to steady the motion of the engine and tender; and
side-chain couplings are fitted in case of accident to the coupling,

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Screw 15 long
84
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Fig. 522.-Coupling between Engine and Tender.
A, Shackle and bolt on the engine beam. B, Shackle and bolt on the tender beam. c, Right and
left hand screw and handle. D, Block pieces. EE, Brackets for draw pins.
thus preventing the engine getting detached from the train; in some
instances plain long links are substituted.
In other arrangements the draw link is connected to a transverse
spring, which is extended as the strain or pull comes on it; with this
method the engine is drawn away from the solid buffing pieces, and
when the engine is suddenly reversed, as is the case at times, a
violent shock between the engine and tender is the result. There
can be no doubt that a rigid connection between the engine and
tender is to be preferred, the pull between these being solid and
inelastic, and side buffing springs being only used to steady the
motion.
Another arrangement of draw gear consists of a plain bar, which
is connected to the engine by an elongated eye, and to the tender
648
MODERN STEAM PRACTICE.
and spring shackle by a plain eye; the transverse spring is fitted
with rods having buffing pieces at the flat ends, the rods passing
loosely through bosses on the tender end beam; thus when the
engine and tender are drawn together a slight compression is given
to the spring through the buffing pieces, and the pin for the draw
shackle is then dropped into its place. This arrangement is rigid when
the engine is running, and when the engine is reversed the shock is
taken on the spring ends, the elongated slot on the draw bar allow-
ing for the compression. The safety chains, one on each side, are
simply single bars with an elongated eye for the engine end, and a
plain eye for taking the pin on the tender frame. This plan of draw
gear is a decided improvement on the foregoing example, as the
shock while reversing the engine is easy, and not at all destructive
to the machine; at the same time, when the engine is suddenly
reversed backwards and then instantly put forwards the strain must.
be rather severe, so on the whole we prefer the rigid connection,
which remains so when the engine is going either way.
The draw bar and hook for tank engines are fitted with an india-
rubber spring, which is placed in a box secured to a wrought-iron
frame underneath the foot plate, the draw bar having a flange bear-
ing on the india-rubber, and secured to the rod with a cotter. The
spring, in some examples, is contained within a wrought-iron shackle,
having a round piece forged on for taking the spring, with a central
hole for the draw bar passing through. The shackle is held by
means of a round pin passing through a hole in the framework
underneath the foot plate. A shoulder is left at the hook outside of
the draw end or beam, and the draw bar is tightened up against
it with a nut bearing on a washer, which compresses the spring; by
this means the rod and shackle are made quite rigid, or, as it were,
drawn taut by the action of the spring. The draw chain in front of
the engine is likewise fitted with an india-rubber spring, which is
contained in a box bolted to the inside of the buffer beams, the
draw bolt being fitted with a loose washer and nut for adjusting the
draw gear.
The rail guards are placed in front of the leading wheels, and
within a few inches of the rails; they are intended to push aside any
obstruction, such as large stones that may fall from deep cuttings,
upon the rails. The guards are made of wrought iron, and are bolted
to the framing, and in some cases to the buffing beam. In no case
should they form part of the framing. As the obstruction may be heavy
maybe
LOCOMOTIVE ENGINES.
649
and bend or even break the guard in the act of displacing it, we
are inclined to think that the buffing beam is the proper place to
fix the guard, as the strain in displacing a heavy stone or other
obstruction would be confined to the wooden beam, which could be
easily replaced were it injured; whereas were the main framing of
the engine strained with the impact of the blow imparted through
the guard in displacing the obstruction, it would entail heavy repairs.
A thin scraper or brush is attached to the guard to clear snow off
the rails. It has been proposed that the sheet-iron scraper should
be acted on by the springs, but this is an unnecessary refinement,
seeing that a snow plough in many instances is required to clear
the track. The thin scraper can only be of use to keep the top
of the rails free from snow, thus preventing the leading wheels
crushing the snow into a solid cake, on which the driving wheels
would slip.
Sand boxes are fitted to the framing of the engine, with a pipe
descending to within a few inches of the rails. This pipe should be
bent at the bottom backwards, so that the sand may be allowed to
drop gently on the top of the rails, and so get them properly
covered. Sand boxes are generally made too small, owing, we
have no doubt, to their unsightly appearance, as fitted to the fram-
ing. In some
cases large sand boxes have been placed on
the top of the boiler, with a pipe descending on each side, so that
with one valve or tap the rails on each side are sanded simul-
taneously. The regulating valve is generally of the disc descrip-
tion, with two apertures for allowing the sand to pass through, the
valve being fitted with a spindle, lever, and rod, passing along to
the platform. In order to obtain sufficient bite for the wheels,
the rails being in a greasy condition, the sand must be clean and
sharp; moist sand will not do, so to free it from moisture and
obtain a hard gritty powder it must be roasted. A good plan for
doing so is by baking it in a fire-brick oven. In most railway-
locomotive workshops a furnace is kept burning, named the
"kindling furnace," where at any moment the stoker can get a
shovelful of live coal to kindle the fire in the locomotive fire box,
and the sand for the rails used to be roasted on a griddle of cast
iron placed over this kindling furnace, but the frequent cracking
and breaking of the plate gave a deal of trouble, as the sand fell
into the fire. The roasting oven should be made entirely of fire-
brick; it is arched over the fire, the flame passing through flues
650
MODERN STEAM PRACTICE.
all round the oven, and then up the chimney. The door of the
furnace is made of cast iron, lined with firebrick, and fitted with a
chain and balance, the chain passing over suitable pulleys. As the
whole of the brickwork gets intensely hot, it is necessary to bind
the building with angle iron round the edges, secured with cast-iron
girders, with bolts at top and bottom running across the brickwork;
in this way the brickwork is prevented from cracking.
Foot plates should be of a ribbed or checkered pattern to give a
secure foothold, the plates being 3% of an inch or so in thickness
behind the fire box, and 4 of an inch in thickness all round the
top of the framework. The plates are secured to angle iron forming
part of the framing, or supported by brackets bolted to the frame,
and edged with angle iron, the foot plates and angle iron forming
the fender when no outside framing is used.
The foot space for the engine-man and stoker at the back of the
fire box is protected with thin sheet iron, supported by wrought-iron
pillars and rail, the pillars being secured to the framing. There
should in all cases be fitted a weather-protecting plate, covered in
at the sides and top so as thoroughly to protect the driver and
stoker, the plate being fitted with two round windows for looking
ahead. Indeed we consider that a cab should be fitted on all
engines in all countries, similar to those on the American engines;
but of course, for very warm climates, the protection should be
freely ventilated, or be, as it were, an open cab, consisting of
wrought-iron pillars, and top awning to protect the head from the
vertical rays of the sun. Hand rails should be fitted all round the
framing at the sides and front, formed of wrought iron, secured to
the boiler with round eye studs, screwed into a plate with boss piece,
which is rivetted to the boiler.
Two iron steps are generally fitted to the framing for ascending
the foot plate at the fire-box end, and front steps may be fitted
when necessary, so as to facilitate the inspection of the machine.
Splashers are fitted on the top of the framing, inclosing the
wheels, which they should do effectually, so that there will be no
danger when passing along the foot plates when the engine is
running at a high velocity. They are formed of thin plates and
angle irons, with angle-iron flanges for securing them to the framing;
they are generally edged with strips, and should be constructed in
a tasteful manner. Of course the top of the arch should be kept
sufficiently clear from the flange of the wheel to allow for the action
LOCOMOTIVE ENGINES.
651
of the springs. Some ornament these parts with bright brass work,
we certainly prefer tasteful painting, as the brass work requires con-
stant cleaning to keep the machine nice looking.
Feed pumps and feed-water apparatus.-Feed pumps, as applied
to the locomotive, are of three descriptions, namely, long-stroke
ram pumps, worked from the piston crosshead; short-stroke ram

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a
b
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e
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f
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Fig. 523.- Feed Punip and Valve Chests of Brass.
a, Working chamber. b, Plunger. c, Valve chambers. d, Suction valve.
e, Delivery and non-return valves. f, Stop plug tap on boiler. g, Eye piece on end of plunger.
pumps, driven with an eccentric; and independent steam pumps,
having a small engine expressly for the purpose of supplying water
to the boiler; while the feed apparatus consists of the much-used
injector.
When long-stroke pumps can conveniently be applied they are
to be preferred, no matter in what position they may be placed. In
frosty weather all pumps are liable to get damaged from the water
freezing in the pipes, where the engine is exposed to the influence
of the weather overnight. It is highly necessary under these
circumstances to have a test plug tap fitted, to see if the pump is free
before starting the engine; a cock and pipe should also be fitted
652
MODERN STEAM PRACTICE.
to allow steam into the pump, to thaw the ice in cold climates;
but probably if the water was allowed to flow out of the pump by
the cock as already described, when the engine was in the shed at
the workshops, there would be no danger from freezing. When
the engine is running there is but little danger from frost, as the
circulation of the water from the tender can always be more or less
maintained. This motion of the water, partial as it may be, tends
to the prevention of accident in all pipes which are liable to be
damaged from the expansion of water when frozen. With inside-
cylinder arrangement the pump ram is worked directly from a pro-
longation of the gudgeon of the crosshead; the pump being fitted to
the main frame, the front end is fitted to the motion plate, and the
back end is bolted to the frame, flanges being cast on the barrel of
the pump for that purpose. These pumps consist of the working
chamber, the plunger or ram, the valve chambers, the suction and
delivery valve, and the non-return valve, fitted to the side of the
boiler, while, in some instances, although by no means general, a
plain plug tap has been fitted to the side of the boiler. We prefer
the self-acting non-return valve, although a plug tap may be fitted
between it and the boiler, to be shut off when the non-return valve
or other pump valves require inspecting when the engine is under
steam.
The pump barrel should be cast of tough brass, but in many in-
stances toughened cast iron has been used. Muntz metal is now
universally used for the plungers, which are connected to the cross-
head of the engine by means of a wrought-iron eye, keyed to the
plunger, a hole being bored out in the prolongation of the eye piece
for receiving the part turned down on the end of the pump ram.
The eye is simply held in position on the crosshead with a set screw,
the point of the steel screw being indented into the gudgeon. When
cast-iron barrels are adopted, the stuffing box for the plunger is
fitted with a bottom ring and gland piece of brass; the latter should
have an oil chamber cast along with it for lubricating the ram, fitted
with a siphon wick.
In the arrangement having the barrel of brass, the valve chest is
cast in one piece, containing the suction, discharge, and non-return
valves, which are of the ball description, having cages for the
guidance of the balls, which are cast along with the screwed caps
on the discharge and non-return valve chests, let into the chest
for the suction valve, and held in position with the flange on the
LOCOMOTIVE ENGINES.
653
suction pipe; all the various fittings are noted by letters on the
engraving Fig. 523.
In the arrangement shown (Fig. 524) the valve boxes of brass are
all separate for the suction, discharge, and non-return valves; but in

C
D
A
2
-2→
E
B
B
о
O
A
Fig. 524.-Feed Pump with Cast-iron Barrel and Valve Chests of Brass.
A, Pump barrel.
B. Plunger and eye-piece. c, Suction valve box. D, Delivery valve box.
E, Non-return valve box on boiler.
some cast iron is adopted for the suction and discharge boxes, and
they are cast along with the pump barrel. The cages are held in posi-
tion with a screw bolt and jam nut bearing on them, while the suction
cage is held in position with a flange when the valve box is of brass,
having a taper union piece and nut for the suction pipe. The non-
return valve box has a flange which fits the curve of the body of the
boiler; in modern practice this flange is quite flat, fitting against a
plate with a raised part, which is faced, the plate being rivetted to
the body of the boiler. The position of the non-return valve on the
body of the boiler is of the highest importance, it should be placed
as near the smoke-box end as convenient; the injected water should
be thrown into the boiler at that part where the temperature of the
surfaces exposed to the action of the flame and heated gases is the
654
MODERN STEAM PRACTICE.
least. If the water is injected at the fire-box end, the tubes, being
greatly heated, contract, and draw out of the holes in the tube plate,
causing leakage; and, moreover, when cold water is injected into
that part of a boiler where the steam is more readily produced, it
must have a tendency to reduce the temperature of the steam,
and consequently increase the consumption of fuel. Wherever
the non-return valve is placed the pipe between it and the pump
should be so constructed that it can yield with the expansion

·B.
E
A
B
A
E
Figs. 525, 526.-Feed Pumps.
D)
C
A A, Pump barrels.
B B, Plungers. cc, Suction valves.
E E, Non-return valves.
D D, Delivery valves.
and contraction of the boiler, which can be easily done by giving
the pipe a round bold radius where it bends up from the pump to
the non-return valve box. Some form a u bend in the pipe. We
prefer the bold radius given to the pipe, as the water flows through
LOCOMOTIVE ENGINES.
655
it more freely. At the same time the pipe is not so much strained
with the expansion and contraction of the boiler; and in fact this is
the only part where the expansion affects the machinery, owing to
the pump being attached to the frame, while the boiler is free to
expand independently of the framing. All the flanges on the valve
boxes should be of great thickness, more especially when of brass,
as with frequent jointing and disjointing the flanges would be bent.
And the bonnets or caps are liable to spring under the great pres-
sure they are subjected to when going at high velocity, unless they
are made very strong.
In other pump arrangements the valves have their webs with broad
surfaces for guiding the valve in the seating, as in Figs. 525, 526,
while others (Fig. 527) have guiding pieces with no webs, with stops
so as to limit the lift. A pet plug tap (Fig. 528) is fitted between the
discharge valve and the non-return valve; it is calculated to allow


A
+
B
Fig. 527.-Feed-pump Valve.
A, Valve. B, Seat.
Fig. 528.-Pet Plug Tap.
A, Pet plug tap. B, Pipe.
any air or steam collecting between the valves to escape, as also to
test the action of the pump. This tap may be fitted directly to the
valve box, with rod passing along to the platform; in other cases a
pipe is fitted, having the tap close at hand near the platform. In
all pumps it is found a great advantage to have the space be-
tween the ram and the body of the pump as little as possible,
as a better vacuum is obtained in the first instance when no water
is in the pump, or in technical language the pump fangs more
readily.
There can be no doubt that the pressure at the commencement
of the stroke is greatest on the ram, owing to the area of the valves
being greater on the top surface, and that the valve closes with con-
656
MODERN STEAM PRACTICE.
siderable shock. With a view, therefore, to soften the action of the
valves, air vessels have been adopted on the suction and discharge
boxes, with cup valves working in a cage, similar to the ball-valve
arrangements, and it is found neces-
sary to limit the lift of the valves,

| A
D


C
po
B
A
Fig. 529.-Air Chambers. Valves.
A, Pump barrel. c, Air vessel and suction valves,
and D, Delivery valve and air vessel.
I
Fig. 530.-Non-return Valve and Box.
A, Non-return valve and box. B, Pipe from
pump. c, Expansion joint.
which varies from 3% to 4 of an inch. A valve with a greater lift
must necessarily return with much greater velocity, giving repeated
blows, which soon injure the surfaces, but the blows can be greatly
softened by the adoption of air chambers, forming elastic cushions.
that tend to relieve the pipes, while they also insure a steady flow
both into and from the pump. The non-return valve (Fig. 530) on
the cup principle is likewise adopted, the box being fitted with an
expansion stuffing box and gland; by this means the feed pipe
expands and contracts freely, thus forming a yielding medium
between the pump and the boiler.
•
LOCOMOTIVE ENGINES.
657
D
Short-stroke pumps, having a hollow plunger, have been used,
the plunger being actuated by an eccentric for that purpose;
placing the rod on the back eccentric for
the valve motion is a bad arrangement,
that should never be attempted. The
strain on these pumps is somewhat severe
owing to their large area; consequently,
when the eccentric for the valve has its
own legitimate duty to do, and likewise
to drive a pump plunger, the wear be-
comes very great, destroying in a mea-
sure the correct action
action of the main
steam valves, so it becomes imperative to
adopt an eccentric for driving the plunger
alone.
Ball valves are sometimes adopted in
these short-stroke pumps, similar in con-
struction to those already described, and
shown in detail. In other arrangements
the valves are feathered, and are guided at
the top with a short spindle working in

E
A
Stroke 54 B
a hole bored out in the cover for the valve Fig. 531.-Short-stroke Feed Pump.
chest; at the side of this guiding piece a A, Pump barrel. 3, Plunger and stuff-
very small hole is bored, through this the
valve spindle ejects the water above it in
ing box. c, Suction valve. D, De-
livery valve. E, Stud for the eccen-
tric rod.
a gradual manner, forming a water-cushion for the valve lifting


B
E
A
C
D
F
B
A
D
Fig. 532.-Feed Pump with Feather Valve having a Spindle on the Top.
A, Pump barrel. B, Plunger and stuffing box. c, Suction valve.
D, Delivery-valve box. E, Stud for the eccentric rod.
F, Oil cup.
Fig. 533.-Non-return Valve.
A, Ball valve. B, Valve chest.
c, Cage. D, Flange for
bolting to the boiler.
against instead of striking against a stop, and which tends to soften
42
658
MODERN STEAM PRACTICE.
the action. The plunger of the pump has a stud secured to the
plunger with a cotter, and in some a nut, while the eccentric and rod
are of the ordinary description, with cast-iron sheave, brass straps,
and wrought-iron connecting rod. The non-return valve connected
with the latter arrangement is of the ball type, with cage secured
to the cover by a single nut, while there is a stop cast along with
the cage for regulating the lift of the ball. In another arrange-
ment of short-stroke pump the jointed stud, placed inside of the
ram is so situated that the thrust of the eccentric rod is taken
on the gland and ring fitted to the bottom of the stuffing box
directly; by this means the pump
ram is not so liable to tilt. The
gland for the stuffing box shows
the arrangement of oil cup, which
is cast along with it for lubricating
the plunger.

A
DO
B
Fig. 534.-Feed Pump.
C, Oil cup. D, Stud for the eccentric rod.
In fixing these pumps it is pre-
ferable to keep them entirely clear
A, Pump barrel. B, Plungers and stuffing box. of the boiler. They are generally
fitted to a vertical plate, the pump
is bolted on with the same flange as takes the gland bolts, the
pump being short requiring no other support. In this arrange-
ment the pump is placed in front of the driving wheels, while
in others, when it is placed behind the driving wheels, a flange
is cast on the bottom of the pump, which is bolted to a vertical
plate placed at a short distance from the fire box, which is
securely rivetted to the framing. With the view of giving greater
strength to resist the thrust of the plunger, the plate for bolting the
pump to has been placed on its side in the form of a beam, having
flanges cast on the pump at the side for bolting thereto. All these
different arrangements are preferable to fixing the pump to plate
brackets attached to the fire box and shell of the boiler, as the strain
is liable to affect the joints of the boiler, causing leakage.
Ball-and-socket joints with a sliding pipe were at one time much
used for forming the connection between the pump and the tender,
fitted with screw couplings for readily connecting and disconnecting
the union between the tender and engine. A branch is made on
the pipe for fitting the heating pipe, with plug tap on the boiler for
allowing any surplus of steam to be blown into the tank for heating
the water; the steam being let into the tank when the safety valves
LOCOMOTIVE ENGINES.
659
blow off, which mostly takes place when approaching stations; and
great waste of steam would occur when the train is detained at the
station were it not profitably utilized in heating the feed water.

A
B
I
I
G
G

Fig. 535.-Union Pipe between
Engine and Tender.
These ball-and-socket connections are very
expensive in first cost, and prove a continual
source of annoyance and expense in keep-
ing such fine fittings in proper repair. A
simpler connection is obtained by using a
flexible hose, manufactured of canvas and
india rubber, with a coiled wire inside which
readily yields with the motion, and prevents
the flexible hose from collapsing, the union
being formed with a screwed coupling. The
flexible hose, however, is also a source of
trouble, as it soon deteriorates unless of
very superior manufacture. To remedy the
practical difficulties in both of these con-
nections various plans have been tried: we
notice one that has given a measure of
The arrangement consists of two cylinders AA (Fig.
535), of brass or cast iron, one of which is bolted in the usual
manner to the feed pipe of the engine, and the other to that
of the tender; they are both bored out smooth and parallel;
B is a connecting tube of brass or cast iron, having the ends
turned, the part from C to D being parallel, and that from D to E
coned; the collars, F, are curved as shown; GG are elastic rings of
vulcanized india rubber, which, when at work, roll between the
cylinders, A A, and the connecting tube, B; II are light chains used
for the purpose of keeping the tube, B, in its proper position; they
are left slack to an extent of one half, the greatest amount of travel
required between the engine and tender. The advantages which
this arrangement appears to possess are its extreme simplicity, and
success.
&
660
MODERN STEAM PRACTICE.
consequently cheapness both in first cost and current repair, and
the great durability of the only wearing parts, the motion of the
elastic rings when at work being a rolling instead of a sliding action.
Also the absolute tightness of the joints when the steam is blown.
from the boiler into the tender tank, as the elastic rings, G G, are
then forced up the cone, DE, by the increased pressure, and are
prevented from blowing out by the collars, F, which are curved as
shown for the purpose of enabling the rings to adjust themselves
readily to their proper position when the pressure is removed, which
they do as soon as the engine is put in motion. The india-rubber
rings, G, are made slightly larger than the space into which they fit,
for the purpose of insuring a thoroughly water-tight joint; the
cylinders, A, are 3 inches inside diameter, and the tube, B, 2 inches
diameter outside; the ring is made 3% inches outside diameter and
1% inch inside diameter, the section of the ring being a circle
5% inch diameter; of course these dimensions vary with the size of
the pumps. Wrought-iron hanging brackets of plate iron or round
forged bars are hung from the framing on the foot plate for sup-
porting the ends of the pipes, placed close up to the screwed coup-
ling; they are fitted with a cap in some, and a strap bolt in others,
for readily connecting and disconnecting without distending the
flanges on the pipe.
The auxiliary engine or steam pump (Fig. 536) is sometimes fitted to
the locomotive as the only means of pumping the feed water into the
boiler, such as on short mineral lines where there are frequent stop-
pages; in such cases the ordinary feed pumps have been entirely
dispensed with. The steam pump is serviceable in all engines as
a means of pumping in the water when the locomotive engine is at
rest. The steam pump possesses the advantage of being allowed to
work at a uniform speed, while the ordinary pumps have often to
work unfavourably at a high velocity. The steam pump should be
so constructed as to take up little room, consequently the best form
of design is long and narrow; in the example given, the suction
and delivery valve chambers are fitted with air vessels, which tend
to soften the action of the valves, and equalize the flow into and
out of the pump. The waste steam should be discharged into the
tank on the tender, thus utilizing the exhaust steam in heating
the feed water.
The injector is an instrument used for feeding the boiler, and cer-
tainly is a very ingenious contrivance; the engraving (Fig. 537) shows
LOCOMOTIVE ENGINES.
661
clearly how it is arranged. The central cone spindle is made adjust-
able so as to allow the exact quantity of steam to pass, while the
outer cone pipe can also be adjusted for allowing the necessary

C
E
A
B
E
D
Fig. 536.—Auxiliary Feed Pump.
A, Steam cylinder. B, Pump plunger. c, Inlet passage. D, Outlet passage.
E, E, Air vessels.
quantity of water to pass around the annular space left between it
and the outer casing. This instrument works best with cold water,
and we are inclined to think that the water is simply injected into
the boiler by the velocity it acquires from the atmospheric and steam
pressure; in truth it works as a condenser. Were the water in the
tank at the boiling point, and the steam turned on from the boiler,
no water could be injected into the boiler from the tank; but the
water, being comparatively cold, will flow in. Now we consider this
is to be accounted for by the steam rushing against the cold water,
forming a partial vacuum; the atmospheric pressure then comes to
bear, and the water is simply injected into the boiler by the atmo-
spheric and steam pressure. The valve shown on the underside is
to prevent the water in the boiler flowing out when the apparatus
is not working. A very large plug tap and pipe is fitted to the
boiler in comparison to the small water nozzle, and in fact the pipe
is much larger than what is fitted to an ordinary steam pump, thus
giving a full command of steam for injecting the water rapidly into
662
MODERN STEAM PRACTICE.
the boiler. The suction pipe should be properly guarded in the
tank with a rose having very small holes, as the smallest hard
substance would lodge in the nozzle, and completely destroy the
action of the instrument. The only benefit in using the injector
seems to be its economy as regards repairs, which in ordinary

to Boiler
Overflow
Water supply
Stearn from
Boiler
Fig. 537.-Injector.
pumps are heavy. But we are of opinion that a steam pump or
auxiliary engine on the double-acting principle is far more econo-
mical as regards the steam required to throw a given quantity of
water into the boiler. The plug tap, as in fact all steam plug taps
worked by hand, should be fitted with a wooden ferrule fixed in the
handle; wood being a non-conductor, the handle always remains
cool, but if of brass or other metal, it at times becomes too hot
to grasp.
Feed-water heaters appear to have been applied with success to
locomotive engine boilers. The principle upon which these appli-
ances depend is the delivery of the feed water to the boiler at a
uniformly high temperature, such as 200° F. and higher, and the
freeing of the water from impurities. Exhaust steam is used, and
in some cases live steam from the boiler. The exhaust steam is
passed into tubes surrounded by the feed water, contained in a strong
casing, and after circulating, passes off. The water receives so
much heat from the surfaces of the tubes, and is afterwards further
heated by a coil of pipes containing live steam. Any matter pre-
cipitated as a deposit is received in a filter chamber containing char-
coal, and the water thus purified and heated passes to the boiler.
When applied to locomotive engines two pipes connect the heater
·with the blast nozzle conveying the exhaust steam to and from the
heater; the water from the condensed steam being suitably drawn
off. This amount appears to be twenty per cent. of the whole used
LOCOMOTIVE ENGINES.
663
THE AMERICAN LOCOMOTIVE.
Details of boiler, fire box, tubes, &c.—The fire boxes of American
locomotive engines are made large as wood fuel is greatly used
in these engines; they are of the usual form, strongly stayed at
the top with beam stays, which run longitudinally, and in some
transversely, care being taken that the ends of the bars rest on
the upper edge of the end or side plates. In addition to these

R
Н
D
W
L
K
$
K
E
F
Z
X
B
A
2
Z
M
Fig. 538.-General Arrangement of Coal-burning Engines.
A, Fire box. B, Body of boiler. c, Smoke box. D, Chimney. E, Steam dome.
G, Bell. H, Lamp. 1, Cab. KK, Cylinders. LL, Valve casings. M, Guide bars.
and link motion. N', Weigh shaft. o, Crank pin. P, Connecting rod.
F, Sand box.
N, Eccentric
Q, Side rod. R, Cow-
catcher. s, Bogie wheels. T, Driving wheel. u, Trailing wheel. v, Platform. w w, Stays.
x, Tender. v, Tender wheels. z, Springs. z', Brake handle.
bars the top of the fire box is stayed with vertical rods secured
to the bars and rivetted to the top of the outside shell. The
sides of the fire box have screwed stays, which are screwed through
the inside and outside shells, and then rivetted over at the ends.
Although these stays have been originally made of the best iron,
they soon become crystalline in texture, and rapid corrosion also
sets in; the former of these effects is attributed to the expansion
and contraction of the plates, causing a bending and unbending
strain, more especially at the top rows, where the expansion of the
plates is the greatest. Were the inside and outside fire boxes.
expanding equally, there would be no cross strain on these stays;
but the inside fire box must expand more than the outside shell,
consequently the stays must bend and unbend, the bending taking
664
MODERN STEAM PRACTICE.
T
The plates of the fire box are flanged as in British practice with
a separate crown plate, which is at times flanged downwards on two
sides, while in others the side plates are bent, and are of sufficient
length to form the crown, the seam of rivets being in the centre of
the fire box. The junction between the inside and outside shells at
the bottom is made with a solid hoop fitted and rivetted between
the two shells. The fire boxes for wood burning are of iron plates;
the sides are 14 inch thick, which has been found less liable to
ZI
W
E
F
B
D
C
K
H
Fig. 538A.—Standard American Woodburning Locomotive.
place when the fire box is thoroughly heated, and vice versa.
The
stays in some instances have been turned down at the middle
of their length, thus securing some lateral strain without permanent
injury.

S
E, Steam
K, Valve
1, Cylinder.
P, Eccentrics and
D, Chimney and spark arrester.
H, Lamp.
G, Bell.
R R, Main framing. s, Cowcatcher and stays. T, Cab. u, Bogie.
c, Smoke box.
F, Sand box.
casing. L, Motion bars. M, Connecting rod. N, Crank pin. o, Side rod.
v, Driving wheel. v', Balance weight. w, Trailing wheel. w', Balance weight. x, Platform.
z, Pipe for the tender
B, Body of boiler.
dome, safety valves, and whistle.
A, Fire box.
link motion. Q, Weigh shaft.
y, Pump and air vessels, &c.
LOCOMOTIVE ENGINES.
665
16
5
16
blister than thicker plates; the tube plates % to 3% inch in thick-
ness, and the crown inch thick, Lowmoor or Bowling iron being
preferred, both as regards soundness and facility for flanging,
although American iron is allowed to be stronger.
The water spaces around the fire box, when wood is used as fuel,
are narrow, varying from 14 inch to 2 inches, while for coal burning
3 inches clear space is allowed. For promoting a free circulation
of the water a thin plate is placed in the middle of the water space,
parallel with the sides of the fire box; by this means an ascending
and descending current is maintained, the ascending current flowing
from the bottom between the partition and the sides of the inside
shell, while the descending current takes place between the parti-
tion and the outside shell. In some fire boxes suited for coal burn-
ing circulating pipes have been fitted, connecting the underside of
the barrel with the bottom of the water space, which tends to effect
a better circulation of the water; however, the best plan for doing
so is by making the water spaces of sufficient width tapering from
the bottom upwards.
The top of the outside fire box in some examples projects above
the barrel of the boiler from 9 to 12 inches, thus affording addi-
tional steam space and facility for inspection. It is connected with
a sloping plate to the cylindrical part of the boiler; in the latter
the plating is what is termed telescopic, arranged in rings which are
largest at the fire-box end. The top of the outside shell in other
examples is on a level line with the body of the boiler, and in both
instances steam domes are fitted, placed on the top of the fire box
in some, and body of the boiler in others. In cases where a large
dome of say 36 inches in diameter is fitted to the barrel of the
boiler, the hole cut in the plates is only 18 inches in diameter; this
size is ample for inspection through the dome, and the barrel is not
weakened so much. The smoke box is a continuation of the barrel,
and as the cylinders are fastened thereto the plates forming it are
of greater thickness than the body. Careful experiments on the
strength of American boiler plates gives the following results:-
Process of Manu-
facture.
Piled iron,
Rough-edge
Bar.
23.7 tons.
21'2
""
Puddled iron,..
...
23°37",
Hammered iron,
Edge Filed
Uniformly.
25' tons.
24.81
22.8
Notches Filed in the Bar
on each Edge.
28.24 tons.
26.1
""
""
27.87
""
with a reduction of say from 10 to 15 per cent. Formerly the body
656
MODERN STEAM PRACTICE.
5
16
of the boiler was formed of plates 3% of an inch in thickness, with barrels
from 36 to 40 inches in diameter, for 80 to 100 lb. steam pressure;
this thickness has been reduced to 4 inch, and in some of an inch,
in thickness for barrels 43 to 50 inches in diameter, carrying 120 to
130 steam lb. pressure, while the plates of the smoke box may be
taken at 3% of an inch in thickness as well as the tube plate in the
smoke box. There is no angle iron used in the construction of the
boiler, all the plates being flanged at the corners with a bold radius,
single rivetting being adopted throughout the entire boiler.
The tubes used for wood burning are made of copper, brass, and
sometimes of iron; with the former they are from No. 13 to No. 16
gauge, and are expanded in the holes with a tool for the purpose;
no caulking should be adopted, as the tube plates are much thinner
than in British practice, consequently not well calculated to bear
the strain in the process of caulking without injury both to the
plates and the tube, whose ends become brittle; in fact all boiler
tubes are now expanded in the holes with an expanding mandrill
for the purpose; ferrules are only used in the fire-box end; they are
made of wrought iron, and in some instances cast iron is used, the
latter permanently expanding with the heat, keeps the tubes tighter;
however, they require to be made thicker than the wrought-iron
ferrules, consequently the draught is partially impeded. The tubes
vary from 134 inch to 2 inches in diameter, the latter being preferred,
with 5% of an inch distance between them; it is generally allowed
that tubes 2 inches in diameter make a better steam-producing
boiler than tubes 134 inch in diameter, the same heating surface
being presented in both cases. The tubes are preferred in vertical
rows to insure free circulation of the water, as well as allowing the
steam to rise freely.
The coals used in American engines are of the anthracite, bitu-
minous, and semi-bituminous kinds. The former contains but little
hydrogen, and is smokeless; bituminous coal produces much smoke,
and both kinds form clinker. The semi-bituminous coal is not
unlike Welsh coal. All the fire bars for coal burning should be
made so as to clear the clinker; with that object in view they are
fitted with a rocking apparatus that can be agitated when the engine
is running, thus loosening the vitrified clinker.
The problem of coal burning without smoke, as in British prac-
tice, may effectually be carried out by using the best kind of coal,
with frequent firing, and by making proper arrangements in the
LOCOMOTIVE ENGINES.
667
furnace for effectually mixing and igniting the gases and air, and
keeping the grate free from clinker.
The induction by steam of currents of air, as in British practice,
has proved the best and simplest mode of mixing the gases and air,
and will no doubt be found advantageous for American coal-burn-
ing locomotive engines.
The smoke box, as before stated, is a continuation of the boiler,
the tube plate is flanged, and the smoke-box plates rivetted thereto,
while at the door end a wrought-iron hoop is worked inside and
rivetted to the plates, while some have a hoop at the back end,
placed between the shell plates of the boiler and that of the smoke
box, thus greatly stiffening the smoke box for bolting the cylinders
thereto. The smoke-box door is generally circular, hinged and
fastened in a similar way to that in British practice, while some
have a segment of the circle cut away, which is hinged vertically
and fastened at the bottom.
The chimney of the American locomotive is a very plain affair,
but the spark arrester attached to it is peculiar. No arrangement
seems to work better than the conical deflector placed a few inches
above the ordinary chimney, which throws down the sparks into
the receiver surrounding the chimney, and from its large diameter
forms a characteristic feature of the American locomotive, present-
ing the appearance of a huge inverted cone, the top being covered
with a fine wire-gauze protection to retain the finer particles, as well
as to allow the smoke and steam to escape (see Fig. 538Â, p. 664).
At the bottom of the receiver a door is fitted for the purpose of
raking out the accumulation of charred wood; and in some a cast-
iron socket is fitted to the top of the smoke box for receiving the
small end of the receiver. The wire-gauze covering can likewise
be readily removed, and is held down with a jointed strap with rod
and catch. In other forms of spark arresters a series of curved
vertical vanes are placed beneath the conical baffle plate; by this
means the sparks receive a spiral motion, which tends to throw
them against the sides of the receiver, and by their own weight
they fall to the bottom, the smoke and steam passing through a
series of wire-gauze rings placed at the top of the chimney. This
form retained a greater portion of the sparks, and was mainly
introduced on those railways where the sparks are so dan-
gerous to trains freighted with cotton; however, the plan is more
complicated, and as wire gauze has a tendency to impede the
668
MODERN STEAM PRACTICE.
T
draught we certainly approve more of the former arrangement,
which no doubt will continue in use until coal finally supersedes
wood as fuel.
The ash pan is similar in construction to those already described,
and is sometimes fitted with a door or damper at the front, while
others have one at the front and back, which can be opened at
pleasure from the foot plate by means of a jointed rod and handle,
with notches for keeping the damper open at any required position.
The fire bars are of cast iron; in some cases cast in pairs, having
a means of rocking them to loosen the clinker; in others four or
more bars are cast in one piece, the bars resting on flat pieces of
iron fastened at the front and back end of the fire box.
The variable blast nozzle is used in mostly all coal-burning loco-
motives; it is placed in some low down in the smoke box, nearly on
a level with the bottom row of tubes, while in others the blast orifice
is on a level with the top row of tubes.
The separate steam jet is likewise fitted to the chimney so as to
increase the draught while the engine is standing, and is used to
keep down the smoke at the stations by gently urging the fire, while
the steam, mixing with the smoke, makes the latter not so black in
appearance as it would otherwise be. Thus the smoke is partly
consumed in the first instance by a rush of air through the grate,
urged by this separate blast pipe with steam taken directly from the
boiler, which, mixing with the smoke issuing from the chimney,
renders it less opaque, and being forcibly ejected into the atmosphere,
tends to scatter the volume that would otherwise issue slowly and
densely from the chimney were not this appliance adopted.
Various contrivances have been adopted in order to equalize the
draught through the tubes, more especially for coal-burning engines.
In all tubular and other boilers, the heat naturally rises to the
highest parts, consequently takes the shortest course through the
upper row of tubes. To effect a better distribution the exhaust
nozzle has been placed on a level with the bottom row of tubes; a
pipe of about 10 inches was placed over the nozzle, extending a few
inches within the base of the chimney, leaving an annular space of
about 2½ inches in width all round the chimney; by this means
the draught was urged through the openings at the top and bottom,
and consequently more equally through the tubes. While in
wood-burning engines a set of short pipes has been arranged one
over another in the form of a truncated cone, leaving annular
LOCOMOTIVE ENGINES.
669
openings, through which the gases pass, the exhaust steam being
discharged from the lower part of the cone.
To prevent radiation, the boiler is covered over with pine wood,
termed cleading, over which is placed a covering of planished
Russian sheet iron, having brass bands highly polished where the
plates meet these bands; they are sometimes beaded or moulded,
American engineers priding themselves on the high finish they give
their engines.
The steam pipe, placed inside of the boiler, is sometimes per-
forated as in British practice, the openings in some being a triple
row of slots, each 3½ inches long and 4 and 3% wide at the fire-
box and smoke-box ends respectively. With this arrangement the
regulator is placed in the smoke box, and can be more easily
inspected than when inside of the boiler. In other arrangements
the regulating valve is placed in the steam dome, an elbow branch
piece being bolted to the side of the dome, taking the steam pipe
passing along to the branch piece of the front tube plate; the steam
pipe in such instances must be made of sufficient strength to prevent
collapse.
Two safety valves are generally fitted, placed on the top of the
steam dome; while in others a separate casting is used; this is pre-
ferable, as with the former arrangement there is a greater tendency
to priming when the steam is blowing off; lever and spring balances
are generally used, as in British practice, for resisting the steam
pressure on the valve, and they are arranged so as to be reached by
hand, as all safety valves should be; but unless experienced and
careful men are employed as drivers and firemen safety valves of the
lever kind may be tampered with in whatever position they may be
placed on the boiler. The safety valves are generally fitted at the
top of the safety-valve chest, while others are arranged on the cast-
iron cover, forming the top of the steam chest, and are carried suffi-
ciently high overhead, thus dispensing with steam funnels for carrying
off the steam. The covering for the steam dome is of polished brass
very elaborate in design; in some there is merely a bottom piece,
with a recess at top of moulding for letting in the wood lagging,
and which is secured at the top with a strap, the whole being
covered with Russian iron highly planished.
Glass water gauges are not generally adopted in American loco-
motive engines; sometimes gauges on the float principle are used
for indicating the height of water in the boiler, while others have
670
MODERN STEAM PRACTICE.
merely test taps, arranged one above another. From three to seven
of these taps are fitted, and an experienced man can tell, on one of
them being opened, whether steam is blowing off, or steam and
water combined, in which case it is seen that the water in the
boiler is so far above the crown of the fire box. When steam alone
is found blowing off, the next tap lower down is tried, and so on
until the limit is indicated below which it is not safe to work the
boiler. The pressure gauge is similar in construction to that
adopted in British engines, Bourdon's being generally preferred;
for a description see p. 575.
The steam whistle is larger than is used in British practice, the
bell being 4½ inches diameter and 6 inches deep; instead of a
plug tap, a conical valve admits the steam into the annular chamber,
it is fitted with a spring, and when the whistle is placed on the top
of the steam chest, on the body of the boiler, or on the top of fire
box, it is fitted with a lever and rod passing along to the platform.
The whistle produces a sound deep and powerful, and is chiefly
used when the train is departing from and entering stations, as like-
wise signalling to the guard to turn on the break in cases of danger.
A mechanical means of sounding the whistle on approaching level
crossings has been carried out with a measure of success, consisting
of a worm wheel placed on any of the engine-truck axles working
a train of wheels which turns a drum, having catches for lifting the
valve lever on the whistle, the catches being adjusted to the distance
travelled over by the truck wheels of the engine. It is obvious that
this plan would work well on certain lines, provided no slip occurred,
and the truck wheels of the engine did not wear on the tyres, increas-
ing the number of revolutions for a given distance travelled over;
but as the wear must be very gradual, a provision for adjusting
the mechanism is all that is required on the part of the engineman.
A large bell weighing upwards of 200 lbs. is fitted to a stand
placed on the top and front of the body of the boiler, having a rope
passing along to the platform, which is sounded on approaching and
passing level crossings.
The head light is placed in a large lantern, fitted with brackets,
secured to the front of the smoke box, and is fitted with a parabolic
reflector plated with silver, the diameter varying from 18 inches to
22 inches, and about 16 inches in depth, concentrating and throwing
the rays of light directly along the line, enabling the engineman on
a dark night to distinguish objects for a considerable distance. Oil,
1
LOCOMOTIVE ENGINES.
671
and in some instances gas distilled from "burning fluid" is used
in the lamps, the latter improving the brilliancy of the light.
A sand box is fitted to the top of the body of the boiler, with
pipes passing down in front of the driving wheels, and is fitted with
valves, levers, and rods, passing along to the platform; by this means
the rails can be sanded simultaneously. These boxes are elaborate
in design, and in some instances support the bracket for the great
bell, by this means lessening the number of fixtures attached to
the body of the boiler.
The blow-off plug valves, heating and lubricating taps, are similar
in construction to those in British practice.
The hand rail is placed somewhat higher up than in British
engines, and passes along from the front of the cab, and across at
the front of the smoke box, the long studs or pillars for supporting
it being secured to the body of the boiler and to the smoke box.
Cylinder and slide valve.—The cylinders are generally arranged
outside of the framing, lying horizontally in some and diagonally
in others, the inclination varying to suit the requirements.
The cylinders are of cast iron, and great attention is paid to
secure the best quality of material. They are cast open at both
ends, the bearing surface of the covers being outside of the
internal diameter, flanges being cast on for securing the covers
thereto. The steam chest is jointed to the cylinder, not cast
along with it as in British practice, thus simplifying the casting,
the joint being metal to metal, carefully faced and scraped, and
secured with bolts or studs in the usual manner. A port is cast on
the cylinder for the admission of the steam from the boiler, which
enters the valve casing through a rectangular port. The fastening
of the cylinders to the smoke box is effectually carried out by means
of brackets cast along with the cylinder, which have flanges for
bolting to the top of the framing, and to the underside of the round
smoke box, while some have the cylinders cast together.
In other examples a separate casting, termed a saddle, is placed
between the framing of the engine, and is curved to the round of
the smoke box, to which it is bolted, as likewise a flange rests on
each frame, both surfaces being accurately planed and strongly
secured together; a flange, turned downwards, takes the inside of
each frame, the whole making an extremely strong fastening
between the framing and the smoke box. The exhaust passage for
the waste steam is cast along with the saddle piece, whilst the
672
MODERN STEAM PRACTICE.
steam passage is let into the side of the steam chest. The cylinder
in this arrangement has a flange which rests on the top of the
saddle, and another, which abuts on the outside of the frame, to
which they are securely bolted.
In other arrangements the saddle is an open-ribbed casting, with
a flange curved to the round of the smoke box, the saddle being the
entire breadth between the frames, to which it is secured at the inside.
and bottom, with suitable flanges cast thereon through which the
bolts pass; on the top side of the saddle vertical flanges are formed
in the casting to which the cylinders are bolted, the waste steam
pipe in such arrangements being cast along with the cylinder.
Provision is made in the saddle for carrying the pin or surface plate
on which the truck or bogie is centered. The steam ports are
located on the top side of the cylinder, placed nearly centrally with
the line of the main connecting rod; a plain valve of cast iron is
used, this has been found to work very well when the cylinder face.
is of hard iron; it is, however, found that these faces work unevenly
if not properly arranged, owing to the varying travel given by the
link motion when cutting off at different grades of expansion. A
steel plate has in some examples been screwed to the cylinder face,
having the ports cut therein; the valve is made of hard brass, all the
surfaces being properly planed and scraped. When separate expan-
sion valves are used they are placed on the back of the main steam
valve directly, or work on a plate having ports to suit, this plate
forming a division across the steam chest. There can be no doubt
that when the expansion valve is placed directly on the back of the
main valve the cut off or suppression of the steam is more perfect,
simply owing to less steam being admitted into the cylinder;
whereas, when the expansion valve works on a plate forming a
division in the steam chest, the steam chest proper must in each
instance be filled with steam, consequently waste must occur. It
must be borne in mind, however, that with the expansion valve on
the back of the steam valve the surfaces work unevenly, and this
is a drawback to their general adoption. Besides there can be no
doubt that with a proper link motion a plain valve is best suited to
work the steam expansively. The reduction of the working parts in
the locomotive engine should be a main object, but expansive valve
gear in many instances is very complicated, while the advantage is
doubtful, and the repairs in some arrangements are heavy.
The steam chest, as before stated, is a separate casting, bolted to
LOCOMOTIVE ENGINES.
673
the flange on the cylinder with stud bolts, and having a round
collar bearing in a recess cut out in the top side of the valve casing,
the bolts projecting beyond for taking the casing cover, having nuts
and washers for securing the cover; the bolts are placed about
4½ inches from centre to centre, and pass down through shields
cast in the valve casing. Were not such a precaution adopted, the
bolts would rapidly corrode when in contact with the steam and
steam currents continually passing through the casing. The
cylinders and steam chests are properly clad and covered over
with Russian sheet iron, and in some instances sheet brass highly
polished, and which may easily be kept so.
The valve rod passes
through the back of the steam chest, having a suitable gland and
stuffing box, with proper means for lubricating the rod; the mode
of attachment to the valve is by means of a loose strap encircling it,
thus the valve accommodates itself to the wear; in some cases the
rod passes through the valve, and is prolonged at the back, working
in a tube piece bolted to the valve casing; the valve is adjusted by
nuts, a thread being cut on the rod.
The valve is lubricated by means of an oil or grease cup placed
on the top of the valve-casing cover, the lubricant finding its way
into the cylinder, keeping the rubbing surface thoroughly lubricated.
Plug taps are fitted to the underside of the cylinder, one at each end
for ejecting the water collecting from condensation and priming.
Valve motion. To recapitulate all the various arrangements of
valve motion that have been used is needless, as the double eccen-
trics and single link for working the steam expansively are now
fully recognized by American engineers. The position of the steam
valve being generally on the top side of the cylinder, the motion is
more indirect than that usually adopted in British practice.
The shifting link is commonly used over that of the stationary
link, and the motion of it given by the double eccentrics is com-
municated to the valve by levers fixed on a short rocking shaft
placed on each side of the framing. The maximum admission of
the steam into the cylinder is about 90 per cent. of the stroke of the
piston, while the minimum admission is about 35 per cent. of the
stroke of the piston; the valve having a throw of from 45% inches to
5 inches, the outside lap being from 5% of an inch to I inch at each
end, while the inside lap is nil; or, in other words, the edge of the
valve is in line with the inside of the port. Some even consider it
advisable to give a little clearance.
43
674
MODERN STEAM PRACTICE.
Cast-iron eccentric straps are very generally used; they are
found to wear better than brass straps when the friction is not very
severe. The rods are of wrought iron, connected to the strap with
side bolts, a broad palm being forged on the rods, having a cor-
responding piece cast along with the front half of the eccentric
strap. The rods are attached to the link with a plain eye having a
pin of steel, and sometimes a bush of steel is placed in the link.
The link is usually of the solid description, formed of wrought iron,
case hardened. The snugs for taking the eccentric rods are at
the back of the link, and very rarely at the ends. In some examples
the link is of cast iron, and although the weight is considerable they
are found to work and wear satisfactorily.
The point of suspension is various, and is generally determined
by trial, which can readily be done with a full sized model; in some
the point of suspension is exactly in the centre of the link, both
vertically and horizontally, while in others it is a few inches above,
or an inch or so in front or behind the centre of the link. The
radius of the link, we consider, should in all cases be the exact dis-
tance between the centre of the link when placed vertically at half
stroke of steam valve and the centre of the eccentric. The weigh
shaft or reversing shaft, on which levers are placed in connection
with the lifting rod on the link, is very similar to those used in
British engines; the brackets for supporting it being bolted to the
top of the frame, one on each side. There are two lifting arms
keyed on, and one reversing arm, as likewise a weighted arm for
balancing the weight of the links, rods, &c.; in some instances a
spiral spring is used for this purpose, which can be placed on the
weigh shaft or at the foot plate according to the arrangement.
The reversing rod attached to the arm on the weigh shaft passes
along to the reversing lever and quadrant placed on the foot plate,
the quadrant being cut with suitable notches for taking the catch
on the reversing lever. When a spring is used at the platform
for balancing or easing the weight of the links, &c., in reversing the
motion, a coiled spring is placed inside of a hollow sheave or drum
which revolves on a central pin, the spring being held with a fixed
point at the spindle, and the other end secured to the drum; a band
connects the drum with the short arm of the reversing lever, so that
when the links are lowered the spring stores up force to ease the
labour of lifting them. As the trains in mostly all double-lined
railways run up on the right-hand line, the levers, and consequently
LOCOMOTIVE ENGINES.
675
the position of the engine driver, being on the outside of the double
line is generally on the right hand, while on some railways vice versa,
or, in other words, the engineman's position should always be on
the side of the engine next the platform of the railway stations, in
order that he may see distinctly the signals given by the guard or
conductor of the train.
Piston. The piston commonly used in American practice is of
cast iron in the body, with a junk ring of the same material secured
to the body by four or more bolts; the packing rings, two in number,
are made of a composition of 9 of copper and I of tin; they are cut
at one part, and the rings are lined or plugged with Babbitt metal.
A ring of wrought iron or cast iron, ½ inch in thickness, is
put inside of the brass rings, and between it and the body of the
piston small springs are placed with set screws for adjusting the
outward pressure against the surface of the cylinder. The inside
ring likewise tends to prevent the steam passing into the body of
the piston. Cast-iron packing rings, even when lined with Babbitt
metal, have invariably been found to rut the surface of the cylinder.
Sometimes the packing rings are expanded with a single wedge as
in British practice, while self-expanding packing rings do not seem
to find much favour with American engineers. Wrought-iron pistons.
have in a few instances been adopted with advantage, as there can
be no doubt that these pistons are light compared with the cast-iron
form, tending to reduce the weight of the reciprocating parts, and
consequently making the repairs less, when the permanent weight
is heavy; with the rapid reciprocation as in the locomotive engine,
the strain on the moving parts is very severe. In these examples
the piston is forged along with the rod, while for the cast-iron
pistons a simple key secures it to the rod, which is made conical,
and properly ground into the conical hole bored out in the boss.
Piston rod, crosshead, and motion bars.-The end of the piston
rod is made conical, fitting exactly the hole bored out in the boss
and ground together with it, making the union perfectly steam tight,
the piston rod being secured to the piston and crosshead with single
split cotters. The gland on the back of the cylinder for the piston
rod is packed with hemp, and in some metallic packing is used.
In the bottom of the stuffing box an annular metallic ring is placed,
surrounding but not nearly touching the rod; it is of a conical form
with the larger opening at its outer end. Composition rings, cut at
one part and bored out to fit tightly against the piston rod, are
i
676
MODERN STEAM PRACTICE.
placed inside of the conical metallic ring already described, the
outer diameter of the rings being turned conically. The gland is
screwed up pressing these rings closely against the piston rod, and
as the outer ring does not fill exactly the stuffing box, and the
gland is bored out somewhat larger than the rod, the packing rings
can thus accommodate themselves should the piston rod from wear
be not in the same centre line as the cylinder. The composition
used for the packing rings is 9 of tin and I of copper. Of course
the piston rod in the first instance must be quite smooth and per-
fectly parallel. The crosshead in a number of examples is of cast.
iron, with the pin for taking the connecting rod cast on, and which
is turned with a tool for the purpose. The sliding block and cross-
head are cast all in one piece, and a snug is also cast on for taking
the pump ram. Wrought-iron crossheads are likewise used, and
certainly we prefer this thoroughly British mode, as they are much
lighter, reducing the weight of the permanent moving parts to the
minimum. The motion bars are of iron, of the double form, placed
on each side of the piston rod. When cast-iron crossheads are used
case hardening is not required, but when the sliding blocks are of
brass or composition metal the bars are case hardened, or steel
used in their construction. The width of each motion bar varies
from 3 to 4 inches, while the length of the sliding block is about
16 inches. The motion bars are secured to lugs cast on the
cylinder cover at the one end and to a bracket through which the
connecting rod works at the back end, the bracket being secured to
the framing and boiler. When no lining pieces with means of adjust-
ment are fitted to the crosshead thin slips of metal are placed
between the lugs on the cover and bracket, which are removed, or
as in British practice filed down to suit the wear of the crosshead.
A lubricating cup is placed on the top motion bars for supplying
the rubbing surfaces with oil or other lubricant.
Connecting rod. The connecting rod is formed, as in British
practice, flat on the sides, the middle part of the rod is rounded at
the top and bottom, with butts at ends for receiving the straps and
brasses; sometimes the middle part of the rod at sides has a semi-
circular groove planed out, thus reducing the weight, while the
section is very stiff. The brasses have all square ends, excepting
the outer half of the small end for the crosshead of the piston rod,
which is made curved, the flanges projecting on each side and made
the full width of the strap. The brasses, with flat ends and flanges
LOCOMOTIVE ENGINES.
677
so arranged, wear much longer than those with the ends circular
and the flanges narrow, being held much more steadily in position.
The straps are secured by two bolts, with nuts and jam nuts; the
cotter for tightening up the brasses bears on an iron plate let into
the brass, thus preventing the thin cotter from cutting the brass,
in which way it would soon become loose were not the plate
interposed between the brass and the cotter. A set screw bears
on the side of the cotter, a hole being tapped on the side of the
butt; by this means the cotter is held firmly in the slot. An oil
cup is placed on the top side of the strap, provided with a siphon
wick.
The rods for coupling the wheels together are arranged in a
similar way with straps, keys, and brasses; the brasses are made to
form a close cap on the outside, by this means excluding dust and
grit; there are two bolts and nuts passing through the straps and
butts at each end, with a single cotter at the one end placed inside,
and at the other end a cotter both in the inside and outside ends of
the brasses; by this means the centres of the bushes can always be
adjusted to the exact distance between the centres of the wheels.
In order to reduce the overhang of the pins for taking the outside
rod, various arrangements have been tried to couple the wheels in
the same line as that of the main connecting rod. One of these
arrangements has a pin formed on the end of the strap for the
main connecting rod, taking the outside rod; but it is obvious that
this plan is highly objectionable, as by the oscillation of the con-
necting rod, the distance between the crank pins of the two pairs of
wheels is alternately lengthened and shortened, imposing a severe
strain on the crank pins. Another plan has the strap on the for-
ward end of the coupling rod prolonged and fitted with brasses for
taking the forked end of the main connecting rod; by this means
the rod is coupled a few inches in advance of the crank pin, and
although by this arrangement an indirect strain is imposed on the
bolts, yet the plan worked much better than the former one. A
third arrangement consists in making the forward pin longer than
usual, and the brasses circular at the middle and square at the
ends. The main rod is forked and provided with straps for taking
the square ends of the brasses, and fitted with bolts and keys.
The coupling rod is fitted with a strap, with bolts and keys, and
is coupled and worked between the forks on the main connecting
rod, the middle part of the main connecting rod brass being turned
678
MODERN STEAM PRACTICE.
for its reception. This form of direct connection recommends itself
as being correct in principle, and may be otherwise arranged in
detail to suit the views of the designer.
Wheels and axles, and crank pins.-—Although cast-iron wheels
are much more liable to fracture, more especially in cold weather,
they are extensively used in American engines; but there can be
no doubt that wrought-iron wheels are preferable, their weight being
less, and having greater elasticity with less liability to fracture.
The driving wheels for goods engines, ranging from about 3½ feet
to 4½ feet in diameter, are made of the plate or disc form, similar
to those used for the bogie or forward-truck wheels. Driving
wheels 5 feet 6 inches or so in diameter have from fourteen to
sixteen arms cast along with the nave and inside tyre. As these
wheels are heavy, and the permanent way rather rough and rigid,
more especially in the winter months, the outside tyres are of great
strength, varying from 24 inches to 3½ inches in thickness ac-
cording to the requirements, the latter thickness being used with
engines having 5 tons on a wheel; and even when those tyres wear
down to about 2 inches they stretch, become loose, and require to
be renewed.
Sometimes the front pair of coupled wheels, where of course a
bogie is placed in front of the engine, have no flanges; this is to
facilitate the engine turning curves; but in recent practice flanges.
are put on all the wheels, while the engines turn as before curves
from 600 to 1000 feet radius, and run more steadily, and the
diameter of all the coupled wheels is better preserved, with seem-
ingly a slight gain in adhesion.
The nave of the wheel for receiving the axles was formerly bored
out conically and the axle turned to suit, the end of the axle being
finished flush, over which was placed a brass plate; this plan is
highly objectionable, for should the wheel become loose on the
axle the covering plate hid the defect; and there can be no doubt
that a cone is a great source of danger, for should the axle become
loose the contact is at once broken. It is imperative that the hole
should be made quite parallel and cylindrical, and the raised part
of the axle turned slightly larger, the wheel being forced on the
axle with a powerful hydraulic machine; the axle then acts as a
mandrill, incorporating as it were the two metals together, the key
way being of course cut before the wheel is finally fixed.
The axles are quite plain. Some, indeed, are parallel bars with
LOCOMOTIVE ENGINES.
679
no collars turned on, while in others deep collars are left bearing on
the inside of the axle boxes, two being required for each axle.
The holes for the crank pins are bored out with a machine for
the purpose, and are not finished until the wheels have been placed
on the axle; by this means they are bored out with a boring bar
truly with one another; the hole is quite parallel, and the pin is
forced in with an hydraulic machine and rivetted over in the inside;
on the outside the hole is recessed about ½ inch, a collar being
left on the crank pin; all the other collars are formed on the
pin, no loose washers being used. The pin is made much larger
where it enters the wheel, as the overhang of the coupling rod is
considerable, and the pin requires to be strengthened accordingly.
Framing and axle boxes, bogie frame, &c.-The framing very
generally adopted is that known as the trussed beam formerly used
by some British makers, but which has now become obsolete in
British practice. The bars forming the beam are about 4 inches.
wide by 2 inches in thickness laid upon the flat side. The horns
by which the axle boxes are guided are forged on, and in some
instances a separate forging or a casting is bolted to the top bar,
forming part of the trussed beam. The bottom of the horns are
connected together with a flat bar which extends the entire length
of the framing, thus forming a trussed beam the whole length of the
engine. The framing is connected to the boiler with braces about
3 feet apart, which is calculated to stiffen the frame; at the same
time these braces must be so arranged as not to throw an undue
strain on the boiler plates, or otherwise the braces must yield with
the expansion and contraction of the boiler, more especially as the
boiler plates are not so thick as in British locomotives. These
intermediate braces are bolted firmly to the frame and are rivetted
to the boiler, broad palms being forged on the end of the tie braces.
At the fire-box end a long angle-iron piece is secured to the outer
fire-box shell, the boiler at the fire-box end being supported by
this means, the angle iron resting on the top of the frame, to which
it is secured by means of a strap which is bolted down at the ends
to the frame, provision being made for the free expansion of the
boiler, say 4 inch for the whole. The boiler is rigidly held at
the smoke-box end, but is quite free to expand towards the back
end. The screw bolts for securing the angle-iron brace to the fire
box pass through the water space, and are screwed and rivetted to
the shell of the inside fire box, and in some a nut having a con-
680
MODERN STEAM PRACTICE.
cave face is screwed. A packing of canvas and red lead is placed
upon the bolt before it is screwed through the inner shell; the nut
is then tightly screwed against the inside plating of the outer fire
box, thus making a perfect joint. The plate-beam frame, 8 to
9 inches deep and I inch in thickness, so universally used in British
practice, is now adopted by American engineers; this form of frame
combines strength and simplicity, giving a ready means of attach-
ment to the various parts, and should have the horns, &c., forged
on the plate beam.
The axle guards or horn plates, as has been stated, are welded on,
and in some instances cast-iron and wrought-iron pedestals are
bolted to the frame, while in the plate-beam frame they are
forged along with it. The wearing surfaces of the axle boxes are
of cast iron, and sometimes of composition metal, and slide on
wedge pieces secured by bolts and confined with the flanges on
the axle box. These wedges adjust the wear of the boxes, and
coupled engines should never be without some such means of adjust-
ment. A good plan consists of a wedge or shoe piece of cast iron
embracing with flanges the side of the horn plate, presenting a sur-
face of say 5 inches. The flanges of the axle box extend upwards,
completely inclosing the opening between it and the under side of
the frame; they support a short roller above, on which the spring
rests, providing a fair bearing no matter what the inclination
may be.
The brasses for the axle boxes are lined with anti-friction metal,
but this is not desirable in some instances, as grit and dust, finding
their way to the journal, soon destroy the rubbing surface. A com-
position of 97% parts zinc and 7½ parts copper has been success-
fully used, the boxes in many instances being entirely cast with this
metal, no separate lining brasses being required. The best brass
bearings are made of a composition of 9 of copper to I of tin, which
gives great satisfaction. The lubricant generally used is oil, and
never grease, provision being made in the oil boxes for supplying
a constant drop by means of siphon wicks.
The front beam of the main framing is of wood, while the back
or drag beam is formed by a frame of cast iron placed between the
longitudinal main frame pieces, to which it is secured; in other
examples the drag beam is constructed of wrought iron.
The engine and tender are coupled closely together, and a cast-
iron wedge with tapered plate is fitted on the back of the engine
LOCOMOTIVE ENGINES.
681
frame, which is screwed up tightly. Draw springs are never used
between the engine and tender, but a draw spring at the back of
the tender is at times adopted.
The front beam is generally stayed to the boiler at the smoke
box, and sometimes to the main framing; this is required to stiffen
the overhanging frame, which is projected in front to clear the
truck or bogie wheels.
The bogie frame or carriage is similar in construction to those
already described in British practice; some are made with two
bearings for each axle placed inside of the wheels, while others have
four bearings, two inside and two outside of the wheels. The truck
has generally a central bearing, swivelling on a pin, and in some
a flat plate is used. In others swivelling takes place on a joint
several feet behind the smoke box; the truck has the ordinary cen-
tral bearing pin, which drives the carriage forward along with the
engine. The back end of the truck frame is connected to a swivel-
ling joint in front of the driving axle by means of two radial bars.
When the engine is running on a straight line the truck is held
steadily in position by means of inclined seats, upon which the
weight of the forward part of the engine rests, and on taking a
curve the truck slides laterally on these seats, the axles and
wheels adjusting themselves radially or nearly so to the curve, which
is a considerable advantage, and the engine runs more steadily on a
straight part of the line with this arrangement.
Cowcatcher. The cowcatcher takes the place of the rail guard
in British engines; but it is more formidable in its character, as it
can remove quadrupeds straying upon the line, and with the train.
going at 30 miles an hour it does so safely and with very little
ceremony. It is generally made of wrought iron in the form of a
coned wedge, consisting of a flat wedge-shaped bottom bar placed
a few inches above the rails, and extending across and a little
beyond the rails. A strong central brace connects the front of this
wedge-shaped bottom bar with the front beam of the engine,
while a number of bars about 5 inches apart placed horizontally,
and in some inclined upwards, likewise form braces between the
bottom plate and the side plate of the cowcatcher, and the forward
beam of the main framing as the case may be, thus forming a strong
guard, which is likewise stiffened with a rod on each side, connecting
the bottom bar with the main frame of the engine. The drag link
is a long bar connected to the central bar of the cowcatcher or to
682
MODERN STEAM PRACTICE.
the front beam in a strong and substantial manner. There are no
buffers placed in front of the engine. (See Figs. 538, 5 38a, p. 66 3,664.)
Cab. The cab or covering for the protection of the engineman
and fireman, which is placed over the foot plate, and partly over
the back end of the fire box, is in the form of a house, having
a curved roof, the clear height from the foot plate being about
6 feet 6 inches. The frame work is strongly put together, having
windows at the front and sides; the front windows can be opened
at pleasure for the attendant passing through to lubricate the
machinery. Seats are provided with cushions, and in cold weather
a screen of canvas is hung up at the back end, so as to thoroughly
protect the men from the cold. As might be supposed these house
coverings are got up in superior style, both as regards architectural
design and the variety of choice woods used in their construction;
and along with the rest of the engine they are superbly decorated
and painted. (See Figs. 538, 538a, p. 663, 664.)
Inside of the "cab" there is placed a large gong or flat bell, fitted
with a spring hammer, so constructed that by pulling a trigger the
gong is sounded. A strong cord is attached to the trigger, and is
carried back throughout the train. Each carriage, or car as they
are termed in America, carries its own length of cord, which can be
coupled and uncoupled very quickly by means of spring hooks.
The cord is within reach of the passengers, and by pulling it gives
a stroke on the gong, which is the signal for stopping the engine,
and consequently the train of carriages.
In some
Springs and equalizing beams.-The springs are very similar in
construction to those used in British practice. The ends of the
spring are formed flat, and the harness consists of a looped strap,
which is connected to the framing in the usual manner.
the top plate is made much thicker at the ends and hollowed out,
the spring harness or strap resting in the hollow, by this means
keeping the harness in position. The steel plates used in the con-
struction of springs are very seldom more than 3% of an inch in
thickness, and in some cases only or 4 of an inch. Pintles or
spring pins are used for taking the bearing on the axle box, and in
some arrangements a roller is carried on the top of the axle box,
the flanges of the axle box extending upwards for this purpose;
the strap at the spring centre rests on this roller, which is calculated
to give a true bearing, with any inclination due to the working of
the spring when the engine is running.
LOCOMOTIVE ENGINES.
683
At the end of the spring which is connected to the equalizing
beam a slot is cut through the plates for taking a flat link, which is
secured with a key at the top, the bottom double link or hoop
taking the end of the equalizing beam. When the driving wheel is
placed in front and the trailing wheel behind the fire box, the pin
for the equalizing beam is carried on a bracket secured to the side
of the fire box and framing. With the view of increasing the elas-
ticity of the spring hanging blocks of india rubber are interposed
between the frame and the straps holding the springs, although this
material is never used for direct springs. In some examples the
equalizing beam is formed as a spring, with the view of giving
greater elasticity to the hanging arrangement.
Feed pumps, pipes, &c.-The stroke of the feed-pump ram is the
same length as that of the piston, the ram being secured to the
piston-rod crosshead with a single nut; the end of the ram passes.
through a snug cast along with the crosshead. The pump is bolted
to the frame at the back end; and at the front or gland end it is
secured to the bracket plate for carrying the motion bars; this is
the plan usually adopted when the cylinders are placed horizon-
tally, and the pumps arranged inside, which is generally done. The
barrel of the pump is sometimes cast in brass, with a plunger of
wrought iron; but we certainly think that a cast-iron barrel and a
Muntz metal ram, such as used in British practice, is to be pre-
ferred, though there can be no doubt that a pump cast in brass is
more compact, and probably better able to bear the strain should
the water in the pump freeze in winter when the engine is cold.
The valves are usually of the cup form working in a suitable cage;
the lift of the suction valve is generally limited to 1/4 of an inch, and
the delivery valve from % of an inch to of an inch rise. The
check valve on the boiler is of the same construction, and the valve
box is fitted with a gland and stuffing box for taking the pipe from
the pump.
16
The valve boxes both for the suction and delivery pipes are each
fitted with an air vessel; with the former it assists the water in its
passage to the pump, tending to fill the barrel more readily; while
for the delivery valve, the shock that is often felt and heard in all
quick-going pumps is reduced to the minimum, thus tending to
lessen the necessity for repairs, which are otherwise often required
in the feed pipes. The bottom of the suction branch on the pump
is fitted with a gland and stuffing box, so that the suction pipe may
684
MODERN STEAM PRACTICE.
give with the expansion and contraction of the pipe, when the feed
water is warm or comparatively cold. There is always a plug tap
fitted to the boiler with pipe connection to each pump and feed pipe;
by this means steam is admitted into the pumps in the winter time
when they are in danger from the water freezing, as likewise the
steam can be admitted into the tender through the suction pipe to
heat the water in the tender, and consequently effect a saving in fuel.
This can generally be done when running slowly or standing at a
station, otherwise the steam would be blown to waste through the
safety valves. Water heaters have been tried with a measure of
success, the feed water being heated by the waste heat in the
smoke box.
The connection between the tender and the suction pipe on the
engine which is universally preferred is a plain flexible hose, which
bends and unbends with the motion of the engine and tender, the
material used in its construction being india rubber and canvas,
with a coiled wire placed inside to prevent the pipe collapsing, and
which springs readily with the motion. A small plug tap is placed
between the delivery valve and the non-return valve on the boiler
for relieving the pipe from any steam that may accumulate, and
which is worked by a rod (having a handle at the end) passing
along to the platform.
THE LOCOMOTIVE TENDER.
THE BRITISH TENDER.
The tender is the vehicle which accompanies the locomotive
engine, and carries the fuel and water, &c., required by the feading
machine, besides in many cases providing the brake power for
controlling the train. The framing of the tender in many examples
is entirely composed of wrought iron, built up in some, or in one
plate with all the parts cut out; while in others the side frame is of
oak, with thin side plates all in one piece, with the guard plates for
the axle boxes cut out in the plates, and in some arrangements
separate from the side plating; the end beams being formed of oak
strengthened with wrought-iron plates. The guide plates are of cast
iron bolted between the thin side plates. The axle boxes are of
LOCOMOTIVE ENGINES.
685
the same material, with a top bush of brass and a bottom part
of cast iron, which is held in the axle box with two pins; the
ends of the axle boxes are capped to exclude dust and grit from
the journals. There are generally six wheels placed under the
tender, but some have only four; of course the number of wheels
depends on the size or length of the tender, although we find equal
lengths have in some cases six and in others four. Four wheels
placed closely together will take curves more readily than the six-
wheeled arrangement, but the wear and tear of the four wheels
must be greater, owing to the carrying weight being more on each,

K
C
F
I
O
O
...........0000000
E
F
A
H
B
F
H
.8.8.
L
A, Water space.
G, Spring buffer.
tion to the engine.
D
U
D
Fig. 538B.-Tender for Passenger Engine.
B, Manhole and water pipe. C, Coal space.
D
DD, Wheels. E, Frame.
FF, Springs.
HH, Brake blocks. 1, Lever screw and rod for brake. K, Hand wheel. L, Pipe connec-
and certainly we think the brake power not so effective as with the
six wheels. The various parts of the wheels, namely, the boss, arms,
and inside tyre, are forged all in one piece, while in some the
boss, arms, and inside tyre are of cast iron, the outside tyre being
shrunk on in the usual manner. The springs are placed on the top
of the framing, and connected thereto with plain side links, or
harness as it is technically termed; the strap at the centre of the
spring has the usual bearing pin for supporting the load, the
end resting in a recess on the top of the axle box, which pre-
vents the pin shifting. Sometimes the springs are located under-
neath the side oak beams, placed between the thin plates; with
this plan the harness and bearing pin are much shorter than in the
other.
The brake power is a screw and lever arrangement, with rods.
connected to arms carried by a top joint fitted to the framing, one
being placed at the front and back of each wheel. These arms
686
MODERN STEAM PRACTICE.
1
00
carry wooden blocks, which are forcibly pressed against the tyres
with the screw and lever apparatus. Willow is considered the best
wood for the purpose, as it grips firmly and is noiseless. The best
result attained is when the wheels are barely kept from skidding,
that is, when they are turning round with difficulty, being held by
the friction of the blocks acting on the tyres. The leverage is
usually about 500 to 1, that is to say, the blocks move towards the
wheels with a reduced speed of of the speed of the handle or
screw; this, we will allow, is suitable for a weight of tender of 12 tons.
This gives a leverage of, say, 41 to I per ton of load: thus any
weight of tender multiplied by 41 will give the power required.
To distribute the strain of the brake, preventing an undue stress on
any particular part of the framing, the motion should be reduced
with the system of levers beyond the screw; the screw should have
a coarse pitch double or triple threaded, and the lever actuated by
it should be long in comparison with the shorter levers which act on
the brake blocks. We will now take examples from practice, and
show what is considered the better arrangement:—
PROPORTIONS.
Radius of hand lever or wheel,
Pitch of screw,
...
Length of lever for screw,
Length of levers linked to brake block,………
No. 1.
12 in.
12
6
1/3
""
No. 2.
7
39
7
1/2
in.
,,
In these arrangements the reduction of speed is effected in the first
instance with the hand lever and screw, and secondly by the un-
equal levers on the transverse shaft which actuated the whole
system of brakes:-
No. I.
REDUCTION.
(1st), 75 to 1, or 225 to 1 by screw.
(2d), 12 to 6, or
2 to 1 by lever.
450
No. 2.
(1st), 44 to ½, or
(2d), 39 to 7, or
88 to I by screw.
5.6 to 1 by lever.
492.8
It will thus be seen in the
first example that the reduction by a
long lever and screw of fine pitch is 225, while in the second ex-
ample it is 88 only; in the latter the motion is reduced beyond the
screw by the system of levers, and even gives a greater reduction
LOCOMOTIVE ENGINES.
687
than the former, the concentration of power in the first example
being severe on the framing, which should be avoided as much as
possible.
In other examples of brake gear two parallel bars are substituted
instead of the levers and rods, having suitable wrought-iron brackets
bolted thereto for carrying the willow blocks; the bars are guided,
and at the end a rack is formed on each, worked by a pinion, with
spindle forged along with it on the end of which the lever for the
screw is secured. This lever is formed with a jaw for taking the
oscillating nut, through which the screwed rod works, the plain part
of the rod being continued to the top of the tender, passing through
a hole in a bracket, on the top of which the brake handle or wheel
is located. The brake blocks in this arrangement simply move to
and from the wheels in a horizontal line, which tends to wear the
willow blocks more equally; but we must bear in mind that the
concentration of power is very severe on the bracket fitted to the
framing, and provision must be made to meet the requirement.
For a description of the Continuous Brake, see p. 689.
The coupling between the tender and engine has already been
described in connection with the main framing of the engine. The
back of the tender is fitted with a draw hook and spring, the buffers
being volute springs placed in suitable circular boxes, while in some
the draw spring is extended the whole width between the centres
of buffers, the spring acting as the buffing medium, as in ordi-
nary railway carriages. Two safety chains are likewise provided on
the back beam to connect with the line of carriages, and are fitted
with hooks for attachment to the chains on the first carriage of the
train.
The water tank is generally of a horse-shoe form, the space
between being for fuel. The capacity of the tank is about 150 or
160 cubic feet, containing from 900 to 1000 gallons of water for
ordinary passenger engines, and the capacity for goods engines of
the heaviest description about 240 cubic feet, containing 1500 gal-
lons nearly; but it must be borne in mind that these quantities
vary with the length of the line. Light tank engines, for example,
for short lines have a capacity of about 80 to 100 cubic feet, contain-
ing 500 to 600 gallons. The tank should be made of the best iron
plates, 1/4 inch in thickness, and should be well stayed, as its form
is weak, and leakage may occur if it is not strongly stayed. It is
provided with a short hollow cylinder fitted with a cover, which is
688
MODERN STEAM PRACTICE.
placed on the top of the tank at the back end, the principal use
of which is for filling the tank with water, but it is also made of
sufficient size for a man to pass through to inspect the inside of
the tank.
Two feed pipes are fitted to the front end, and are coupled to the
feed pipes from the engine. They are provided with valves for
regulating the supply.
It is highly necessary that the water used in a locomotive boiler
should be as pure as practicable, and for this purpose all impuri-
ties should be got rid of in the reservoir before the water enters
the tank.
•
THE AMERICAN TENDER.
The tenders for American locomotive engines are very different
from those of the British type. The tank is of the ordinary form,
and contains from 1200 to 2000 gallons of water, and from 1 to 3
cords of wood fuel, occupying a space of 128 to 384 cubic feet. The
framing under the tank is constructed of wood, the whole of the
weight being carried on two trucks similar to that of the engine;
in the forward truck the weight is carried on the centre, and at the
back end the load is carried on the sides of the truck; by this means
there are three parts on which the load is supported. The brake
gear is
very powerful, each truck carrying its own system of brakes;
the willow blocks are secured to transverse bars of wood, and are
carried up with shackles secured to the truck frames, and which
are actuated by means of a handle and spindle for a chain winding
round, taking a system of levers on the front truck, which draws
the willow blocks forcibly against the wheels, with a similar system
of levers for the back truck, which is connected to the forward
system with a chain; by this means the trucks can swivel without
deranging the mechanism. In some examples the brakes are only
fitted to the back truck of the tender, and are suspended from the
framing. The trucks have each four wheels with axles, having
the necessary axle boxes, the guard plates are of cast iron bolted
to the frame; the springs are placed on the top of the framing, to
which they are secured with suitable harness. A strong chain and
shackle is placed at each top corner of the truck frame, the other
end being carried by the main frame; these are necessary in order
to prevent the trucks swivelling too far.
LOCOMOTIVE ENGINES.
689
CONTINUOUS BRAKES.
In our notice of the Locomotive Tender we have described the
construction of the ordinary brake gear as fitted to tenders and
brake vans; but the vastly increased traffic on our railways has
rendered necessary some more speedy and certain appliance for
diminishing the speed of trains and stopping them within short
distances. It is now over twenty years since the Board of Trade
first urged upon railway companies the necessity for adopting such
appliances; and in 1878 a bill was passed enforcing upon the com-
panies periodical returns to the Board respecting their action in the
matter of brakes. With a view still further to protect the travelling
public a bill was introduced into Parliament in 1882, rendering it
compulsory on all railway companies to adopt some form of continuous
brake which will comply with the following requirements:-To be
instantaneous in action, and capable of being applied by driver and
guards; in case of accident, to be self-acting; to be applied to every
vehicle in the train; to be in regular daily working; and the
materials employed to be of durable character, easily maintained
and kept in order. This bill, however, did not become law.
A variety of continuous brakes have been introduced with a
view to meet these requirements; and there can be no doubt that
the use of such brakes has already been of much service in lessening
the risk of accident, as by their means trains which formerly required
about half a mile to pull up can now be brought to a stand in about
300 yards. Among the forms of continuous brake which have been
tried are Barker's Automatic, Eame's, Fay, Newell, and Eame's
Combined, Sanders and Belitho's Automatic Vacuum, the Steel-
McInnes, Smith's Automatic Vacuum, and the Westinghouse Auto-
matic Brake;-the various arrangements being known as Screw
Brake, Chain Brake, Hydraulic Brake, Vacuum Brake, and Com-
pressed-air Brake. In all these forms the whole or part of the wheels
of the train can be braked by mechanism actuated from the engine.
In the first two methods rigid or flexible bodies are used, in the others
fluids transmit the power required. In the hydraulic brake water
is forced at a high pressure along pipes. In the air brake air is in
a similar manner forced to the point of application, and in the
vacuum brake the air is removed.
For automatic arrangements, whether of air or vacuum, there
44
690
MODERN STEAM PRACTICE.
are chambers or reservoirs underneath the carriages.
These are
fitted with cylinders and pistons, the latter in connection with the
QU'
E
SCRITTO
NOELOIO
M
N
Fig. 338c.—Part of Locomotive Engine and Tender with the Westinghouse Automatic Brake.
A, Steam cylinder. B, Air cylinder. c, Main reservoir. D, Driver's brake valve. E, Brake pipe. FF, Triple valves.
Brake cylinder. 11, Stop valves. J, Release valve. K, Coupling. L, Pressure gauge.
н,
MM, Engine wheels.
G G, Small reservoirs.
NN, Tender wheels.
N
brake blocks; the object
in such arrangements be-
ing to keep up a certain
condition in the cham-
bers, whether of pressure
or vacuum, which if de-
stroyed either intention-
ally or accidentally, as by
the breaking away of the
carriages, the brake blocks
will immediately be ap-
plied to the wheels.
The Westinghouse Au-
tomatic Brake has now
been extensively adopted
on the more important
railways in Great Britain.
as well as those on the
Continent and in the
United States of Ame-
rica. This brake is con-
tinuous throughout the
train, and is operated by
compressed air stored in
a main reservoir on the
engine, and in small re-
servoirs, one upon the
engine, tender, and each
carriage, all connected by
a pipe running the length
of the train. There are
also on each vehicle a triple
valve and brake cylinder
with pistons connected to
the brake levers.

Fig. 538C shows this brake complete fitted to an engine and
tender. The pump on the engine is started by admitting steam to
the cylinder A, air is forced from the cylinder B into the main
LOCOMOTIVE ENGINES.
691
When a
reservoir, which is connected to the driver's brake valve.
train is to be charged-the hose couplings between all the carriages
and engine or tender having been united—the compressed air stored
in the main reservoir is turned into the brake pipe by putting the
handle of the driver's brake valve over to the left. It then fills the
brake pipe and flows by a branch pipe through the triple valve into
the small reservoir on the tender and each vehicle, where it remains.
until the brake has to be applied. Uniform air pressure then exists.
throughout the train except in the brake cylinders, the brakes being
off, and the pressure per square inch is shown on the gauge con-
nected to the brake pipe on the engine and in the guards' vans.
So long as this pressure is maintained the brakes are kept off, as
the passage from each small reservoir to its cylinder remains
closed; but letting the air suddenly escape from the brake pipe
causes the triple valves to move down and uncover the passages to
the cylinders. The air stored in the small reservoirs then flows into
the cylinders and forces out the pistons and rods, thus applying the
brakes. On the other hand, the brakes are taken off by reopening
the passage from the main reservoir, through the driver's valve,
and thus restoring the pressure in the brake pipe; this lifts the
triple valves, and places the cylinders in communication with the
atmosphere by means of an exhaust cavity in each of the valves,
at the same time recharging the small reservoirs; the air used in
the cylinders is thus allowed to escape, and the brake pistons and
rods are pushed back to their places by springs inside the cylinders.
It follows from the above that any sudden decrease of pressure in
the brake pipe, whether produced by the driver or guard operating
his brake valve, or by the separation of the train, or other acciden-
tal severance of, or damage to, the brake pipe, applies the brake.
It is therefore called "automatic" or self-acting; and owing to this
principle the brake acts as a “tell-tale" as to its own condition, for
should anything be wrong a warning is unmistakeably given by
stopping the train. Special provision is made to prevent the appli-
cation of the brake from leakage, and a release valve is fitted on
each cylinder for the purpose of releasing the brake direct, if applied
when an engine is not attached.
Fig. 538D shows the Vacuum Automatic Brake which is adopted
on many of our railways. This form of brake is operated as
follows: By means of a small steam ejector placed upon the engine
the air is drawn out of the main train pipe E, from the bottom
692
MODERN STEAM PRACTICE.
side of the piston or diaphragm A through the branch pipe F, and
from the vacuum chamber B and top side of piston or diaphragm
through the valve D, so that a vacuum of 20 to 24 inches (i.e. 10 to
12 lbs. per square inch) is maintained throughout the system. To
apply the brake a valve is opened by the driver or guards, which

B
DE
Fig. 538D.-The Vacuum Automatic Brake.
allows air to flow to the bottom side of the piston or diaphragm, the
top side and vacuum chamber maintaining the vacuum through the
action of the valve D, which closes immediately air is admitted to
the train pipe. To release the brakes when the engine is detached
from the train, the valve D is raised by means of a small lever
placed on either side of the carriage which admits air to the vacuum
chamber and top side of piston or diaphragm, and the brakes fall
off by gravity. The flexible diaphragms, hose pipe connections,
and miniature sacks C are made of the best rubber and coated with
a material which effectually resists oil and grease.
BRAKE RESISTANCES.
From a series of experiments made by Captain Douglas Galton,
C.B., F.R.S., on the effect of brakes upon railway trains, some
curious and interesting results have been obtained, from which it
appears that—
(1.) "The retarding effect of a wheel sliding upon a rail was
much less than when braked with such a force as would just allow
it to continue to revolve." The resistance due to friction of the
wheel on the rail being only one-third of the friction between the
wheel and the brake blocks.
LOCOMOTIVE ENGINES.
693
(2.) "The coefficient of friction between the brake blocks and the
wheels varied inversely according to the speed of the train." Thus
with cast iron brake blocks on steel tyres the coefficient of friction
when just moving was 330-
At 10 miles per hour,
20
,, 30
'116
*242
At 40 miles per hour,
*140
*192
*164
,, 50
""
60
""
*074
Further, it was found that this coefficient was affected by time,
thus: Starting at 27 miles per hour the coefficient was '171; after
5 seconds, '130; after 10 seconds, 119; after 15 seconds, '081; and
after 20 seconds, '072; and at 47 miles per hour the coefficient at
starting was 132, falling after 10 seconds to '070; and at 60 miles
per hour falling from 072 to 058.
These coefficients are further influenced by material and weather.
It was found that the distance run by a train on the level at 50
miles per hour varied with the percentage of the total weight of train
used for retardation as follows: with 5 per cent, 555 yards; 10 per
cent, 277 yards; 20 per cent, 139 yards; 30 per cent, 92% yards.
Capt. Galton points out amongst other conditions that a perfect con-
tinuous brake should be fitted to act upon all the wheels of engine
and carriages, that it should exert upon the blocks of each pair of
wheels within two seconds a force of about twice the load on those
wheels, that the brake-block pressure should be such that the fric-
tion between the block and wheel may not be greater than the
adhesion between the wheel and the rail, and that the action should
be automatic in the event of a separation of the train or failure of
connections.
COMPOUNDING LOCOMOTIVE ENGINES.
The principle of compounding has been recently applied with
good results to the locomotive engine, and thereby enables the
benefit of expansion to be more fully carried out than could be with
the single cylinder. One of the arrangements consists in having a
high and low pressure cylinder, one on each side of the engine, so
that instead of two independent cylinders of the same size, having
steam to each from the boiler, the steam first enters the high-pres-
sure or smaller cylinder and thereafter passes across to the low-
pressure or larger cylinder.
694
MODERN STEAM PRACTICE,
This system was introduced on some of the French lines a few
years ago by M. Anatole Mallet, and appears to have been success-
ful there. In a paper read by that gentleman before the Institution
of Mechanical Engineers he says:-
"The compound system affording a simple and effective means
of expanding, that expansion should be carried to a high degree,
and for this purpose cylinders of a large size must be used. In new
engines this can easily be done. The application of the compound
system to existing locomotives is much more difficult; if some
engines lend themselves readily to the change, this is by no means the
case always. The author is convinced that the system will be further
extended; and its success, he is satisfied, would be speedily assured, if
a thorough practical trial were made on one of the English railways."
"The usual method of converting an existing engine is generally
to retain one of the original cylinders as the high-pressure cylinder,

B
D
A
Fig. 538E.-Engine with right-hand Cylinder altered.
A, High-pressure cylinder. B, Low-pressure cylinder. c, Steam pipe. DD, Exhaust pipe from the
high-pressure cylinder. E, Blast pipe. F, Safety valve on the starting-valve chest.
and to replace the other by a new one of larger diameter for expand-
ing; the steam and exhaust pipes are suitably rearranged, and a start-
ing valve and reducing valve are added, while the whole of the origi-
nal mechanism is retained for the large cylinder. The first engines
altered in this way were two powerful locomotives, one a passenger
LOCOMOTIVE ENGINES.
695
engine on the Paris and Orleans Railway, and the other a goods
engine on the Northern Railway of Spain. The arrangement of
this altered engine is shown in Fig. 538E. The old cylinders were
173% in. diameter and 235% in. stroke; of these the right-hand one
has been replaced by a cylinder of 235% in. diameter, which was as
large a size as the engine frames would allow to be got in; the ratio
of the two piston areas is therefore 1.86 to 1. The exhaust pipe
from the small to the large cylinder is made to take a long winding
course, so as to get as large a capacity of receiver as possible,
amounting in this case to 169 times the capacity of the small
cylinder; by the same means also the pipe has about 20 square feet
of surface exposed to the heat of the smoke box. As the alterations
were required to be made in the simplest and least expensive
manner possible, the arrangement of the two link motions to work
independently of each other has not at present been carried out in
this engine, which is the more to be regretted as it presented no
special difficulties; but it can be done at any future time. The
reducing valve has been fitted with a spring to prevent any violent
shocks in case of its acting too quickly; and a spring safety valve
has been fixed on the starting valve chest, to avoid excessive com-
pression of the steam when working reversed."
A trial of this principle has now been made by Mr. Webb of Crewe,
who has recently designed and placed on the London and North-
Western Railway a new compound locomotive which appears to
have given most satisfactory results. We are indebted to that
gentleman for the elevation and plan of this locomotive shown on
the following page.
"The new engine has been constructed at Crewe, and is similar
as regards boiler, wheels, and so on, to the four-coupled express
engines of the London and North-Western Railway. The trailing
drivers are driven by a pair of outside cylinders 11½ inches
diameter and 24 inches stroke, secured to the side frames at a
point just in advance of the leading driving wheels. The piston-
rod heads are guided by two flat bars, one at each side, instead of
four, as usually employed, the crosshead being channelled to slide.
on the bars. The slide valves are worked by Joy's patent gear,
and the connecting rods lay hold of pins in the wheel bosses. So
far we have a complete engine with outside cylinders and a
pair of driving wheels behind the fire box, resembling Crampton's
patent engine. In the smoke box, right beneath the funnel, is
696
MODERN STEAM PRACTICE.
fixed a third cylinder, 26 inches diameter and 24 inches stroke,
the connecting rod of which lays hold of the pin of a single crank
in the middle of the length of the leading driving axle. The
exhaust steam from the two small cylinders passes into a kind of

B
A CO
E
A
B
A

A
Figs. 538F, 538G.—Front End Elevation and Ground Plan of Compound Locomotive,
London and North-Western Railway.
A A, High-pressure cylinders. B, Low-pressure cylinder. cc, Steam pipes. DD, Exhaust pipes from
high-pressure cylinders. E, Blast pipe.
gridiron of pipes between the engine frames, which pipes act as an
intermediate receiver, and from thence it is led into a copper pipe
coiled in the smoke box, in order that it may be reheated and
dried. Thence it goes into the valve chest of the large cylinder.
LOCOMOTIVE ENGINES.
697
We have thus a locomotive with a single pair of driving wheels in
advance of the fire box, driven by a single cylinder. It must be
understood that the double engine and this single-cylinder
engine are quite independent of each other-that is to say, each
may run at any pace it can. There are no coupling rods, nor is
there anything to maintain a fixed relative position between the
cranks of the single and double cylinder engines, save the rails.
The single engine depends for its supply of steam on the double-
cylinder engine, and should the latter slip, more steam is sent into
the receiver than the large cylinder will take, and the back pressure
rises, and so tends to check slipping; while for the same reason
the pressure on the large piston is augmented, and it may slip its
wheels. If, on the contrary, the single engine slips first, it will
take more steam away than the other engines can supply, and its
own pressure will fall off while the effective pressure in the other
cylinders will be augmented.
It is found that this controlling
action operates very effectually, each engine doing its own share
of the work fairly. No inconvenience results from the changing
position relations of the crank pin, the size of the intermediate
receiver being sufficient to prevent irregularities in the amount of
back pressure of much moment. With a boiler pressure of 150 lbs.
the pressure in the receiver averages about 50 lbs.
This com-
pound locomotive is a handsome engine, and has been run at
very high speeds with perfect steadiness. Mr. Webb states that
the engine works ordinary passenger trains with a little over 23 lbs.
of coal per mile, which represents a saving of perhaps 20 per cent.
in fuel on the ordinary consumption. It is beyond question the
best type of compound locomotive ever constructed, and we shall
be much surprised if a large number of such engines are not soon
put into regular traffic.”
"1
As already stated, the valve gear employed in this compound
engine is Joy's, the ordinary link motion not being considered in
this case satisfactory. This valve gear is described as follows: "In
a kind of box under the running board is fitted a disc, which may
be said to resemble the plug of an ordinary stop cock. In this
plug is a curved slot, having the same radius of curvature as the
length of the link leading from a die in this slot to the end of the
valve rod. This link is coupled to the connecting rod by two bars.
The effect is that as the crank shaft revolves the die is caused to
¹ The Engineer, Aug. 1879, Feb. Mar. 1882.
698
MODERN STEAM PRACTICE.
travel up and down in the slot in the plug. If the slot is set at
angle with the vertical, the valve stem will obviously be caused to
move backwards and forwards; when, however, the slot is vertical
the valve has no motion imparted to it by the travel of the die.
The plug has a lever arm attached to it answering to the handle
of a tap. This lever is coupled to a reversing lever with quadrant.
By this means the plug can be made to partially rotate, and so
alter the angle of inclination of the slot that the engine will run
forward or backwards."
DESCRIPTION OF SPECIAL LOCOMOTIVE ENGINES.
FOUR-WHEEL COUPLED BOGIE PASSENGER ENGINE FOR
THE CALEDONIAN RAILWAY. (SEE PLATES.)
3
16
3
16
16
The boiler is of the best Yorkshire iron, plates ½ inch thick in
the barrel, tube plate 18 inch, firebox casing sides inch, back
½ inch, and front 5% inch thick. The longitudinal seams are top-
jointed and double rivetted, and the transverse seams single rivetted
with 1 inch rivets placed 17% inch between the centres. The
inside firebox is of the best copper ½ inch thick, except the tube
plate, which is % inch thick where the tubes are fixed, and ½ inch
below. The casing and firebox are stayed together at the ends.
and sides with I inch copper stays, screwed into both plates, and
placed 4 inches apart between the centres. The roof is stayed with
iron through stays 1% inch diameter screwed through both plates,
rivetted on the outside and secured with nuts inside. The tubes
are of copper 134 inch diameter and swelled to 1 inch at the
smoke box end, 13 W. G. thick at the fire box and 12 W. G. at the
smoke box, fixed in the fire box tube plate with solid drawn steel
ferrules 10 W. G. thick.
The frame is of Yorkshire iron 1% inch thick over the driving
and trailing axles and 1½ inch thick over the bogie. The bogie
frame is I inch thick.
The driving and trailing axle-box guides are of steel, of a horse-
shoe form, and securely bolted to the frames; the bogie guides are
of cast iron. Driving and trailing axle boxes are of cast iron with
gun-metal steps and keeps. The bogie axle boxes are of gun metal
with cast-iron keeps. The bearings in all cases are lined with white
LOCOMOTIVE ENGINES.
699
metal. The axles and tyres throughout are of crucible cast steel.
The crank pins are of Yorkshire iron well case-hardened in the
journals.
The slide bars are of Bessemer steel. The piston rods are of best
Yorkshire iron. The connecting and coupling rods, crossheads,
and the whole of the valve motion, including eccentric straps and
the smaller parts of the pulleys, are made of best Yorkshire iron
and well case-hardened where required. The larger parts of the
eccentric pulleys are of cast iron. The cylinders are of a mixture
of cold blast and Scotch pig iron twice melted and as hard as pos-
sible. The pistons are of the same metal, with two cast-iron rings
in each.
The wheels are of the best scrap iron, with cranks and balance
weights forged solid in them. The tyres are secured with clip rings
on the sides recessed into the rim of the wheel as well as the tyre,
and are held in place by rivets passing through the clips and the
rim at the end of each spoke. The springs are of the best spring
steel converted from Swedish iron.
The ashpan damper, cylinder cocks, and sand boxes are all work-
able from the footplate.
Two Friedmann's No. 9 Injectors, fitted with check valves and
all other necessary valves and cocks, are used for feeding the boiler.
The boiler was tested after all the fittings were attached with
water pressure to 200 lbs. per square inch, and carries a working
pressure of 130 lbs. per square inch.
The weight when loaded is as follows:-
Bogie,
Tons cwts. qrs.
13 O o (equally divided). Tractive force 90 lbs. for each lb. of
effective pressure on the piston.
Driving wheels, 14 15
Trailing wheels, 13 12
O
O
Total,
Tender,
41 7
O
27 8 o Full of water and 3 tons of coal.
The tender is carried on six wheels, and contains 1880 gallons of
water and 4 tons of coal. The frames are of the
iron as those for the engine, and % inch thick.
best Scotch iron plates, top and bottom inch and sides ¼ inch
5
16
same quality of
The tank is of
thick well stayed. The wheels are of the same description as those
for the engine, and fitted in a similar manner with tyres of Bessemer
steel.
700
MODERN STEAM PRACTICE.
The axles are of Bessemer steel; the axles boxes and guides of
cast iron fitted with steps of gun metal. A powerful brake worked
by a screw from the footplate acts upon each wheel.
EXPRESS ENGINE FOR GREAT NORTHERN RAILWAY.¹
In the next example to which attention is directed, outside cylin-
ders have been used; perhaps as a necessary consequence of the
adoption of a bogie carriage with four wheels, instead of a pair of
leading wheels, to insure greater freedom in passing round curves at
high speeds, for which special object the engine has been designed
by the locomotive engineer of the Great Northern Railway. The
weight on each of the four front wheels is at the same time propor-

Ꮐ
H
A
F
D
E
M
K
N
P
R
S
A, Fire box.
Fig. 539.-Express Engine for Great Northern Railway.
B, Midfeather. c, Fire door and deflecting plate. D, Body of boiler. E, Mud chamber.
F, Smoke box. G, Chimney. H, Stays. I, Injector. K, Cylinder. L, Valve chest. M, Guide bars.
N, Connecting rod. o, Bogie carriage. P, Driving wheel. Q, Trailing wheel. R, Cab. s, Draw
pin. T, Frame. u, Weigh shaft. v, Line of valve spindle.
tionately diminished, and with great advantage. It will be observed
that there is one frame only on each side of the fire box and inside
the wheels, and that this frame receives the cylinders. These frames
are of one solid plate, 1/4 inch thick, connected behind the fire box
by a cast-iron cross frame, and elsewhere by wrought-iron cross
brackets and by the buffer beam, receiving the cylinders in front on
each side of the smoke box. This position gives convenient access
to the cylinders, the pistons and rods, the connecting rods, the guide
bars, and the motion blocks, all of which are placed outside the
Transactions of the Institution of Civil Engineers.
LOCOMOTIVE ENGINES.
701
frames. The slide valves and their gearing are inside the frames,
though somewhat nearer to them than in inside-cylinder engines.
The train is drawn from the cast-iron cross frame, which, together
with the longitudinal frames, is so attached as to allow of the free
expansion of the boiler, to avoid any strain being put upon the latter
by the haulage of the train, and to free it from the contortions for-
merly occurring when rigidly connected with the frames at several
points. The proper adjustment of the driving axle boxes is secured
by wedge-shaped horn blocks, attached to the frames by a screw
with lock nuts. The boiler is made of Yorkshire plates, ½ inch
thick, and is of the lap-jointed class, having double-rivetted longi-
tudinal and single-rivetted vertical seams. The pressure of steam
employed is 140 lbs. to the square inch.
The fire box is of copper, the tube plate being 3/4 inch thick, the
back plate 5% inch thick, and the sides and crown ½ inch thick. It
is of the usual square form, and is attached to the external iron shell
by a square iron frame at the bottom; and at the front, sides, and
back by screwed copper bolts, rivetted at both ends. The roof is
stayed to the external shell by wrought-iron radiating stays, % inch
in diameter, screwed into the copper plates and into the iron casing.
The fire box contains a sloping midfeather in such a position as to
deflect the heated gases from the fire before they reach the tubes.
The air admitted through the fire door, and directed by the ordinary
deflecting plate, is thus thoroughly mixed up with the heated gases,
thereby securing the best possible combustion.
9
The boiler is fed by two injectors, and the water can be supplied
without reference to the motion of the engine. The tubes are of
brass, 217 in number, and each 1 inch external diameter. This
comparatively small diameter tends to secure the more effectual
abstraction of heat from the gases passing through the tubes.
16
The cylinders are outside the frames; they are 18 inches in
diameter and 28 inches stroke, and may be considered a large
size for passenger engines. The joint of each steam-chest cover
is in the centre line of the valve spindle, so that when the cover
is removed ready access to the valve facing is obtained. The
valve gearing is of the ordinary shifting-link class. The small
ends of the connecting rods are furnished with solid bushes of
gun metal, which succeed admirably, the connecting rods having
run a distance of more than 50,000 miles without renewal. The
driving wheels are 8 feet 1 inch in diameter; and the trailing
702
MODERN STEAM PRACTICE
wheels are 4 feet 1 inch in diameter. The end of the engine is
carried upon six volute springs, placed in a trough under the foot-
plate, as being more conveniently got in than the ordinary elliptical
springs. There is a cab over the foot plate for the protection of the
driver and the fireman.
The front of the engine is carried upon a four-wheeled bogie
frame, with a cylindrical centre pin, the hole in the bush being
bored taper.
It has also sliding bearings in the line of the side
frames under the cylinder steam chests, to give greater stability to
the engine when running at high speeds. This bogie arrangement
imparts flexibility to the engine when passing round curves, and
secures the greatest steadiness of the whole machine, at whatever
speed it runs.
The mode of attaching the inner to the outer fire box, by stays
screwed into each of the plates without the intervention of iron
girder bars, though in use for some time in Belgium, is now in
some cases adopted in this country. By this arrangement the large
amount of deposit generally existing upon girder boxes is prevented,
and the facility for cleansing is much greater. The liability of the
tube holes in the copper plate to become oval, by the pressure of
the ends of the girders upon the edge of the tube plate, is also got
rid of. It is understood that no countervailing disadvantages have
arisen from the adoption of the system.
The heating surface in this engine is:-
In the tubes,
fire box,
Total,
...
:
:
:
The fire-grate area is 176 square feet.
...
...
1043 sq. feet.
I22
1165 sq. feet.
The weight upon the wheels, when the engine is in working
order, is:-
On the driving wheels,
""
"3
hind wheels,
bogie,
...
:
:
15 tons.
8
""
15
The distance from the centre of the hind wheels to the centre of
the bogie pin is 19 feet 5 inches.
The engine is capable of drawing a weight of 356 tons on a level
at a speed of 45 miles per hour (the load drawn includes in all
cases the weight of the engine and tender), with a working pressure
of 140 lbs.
Its consumption of coal, with trains averaging sixteen
LOCOMOTIVE ENGINES.
703
carriages of 10 tons weight each, has been 27 lbs. per mile, includ-
ing getting up steam and piloting; the cost of repairs being about
52d. per mile run. This engine has been designed to fulfil the
requirements of a quick and heavy passenger traffic; and in the
whole arrangement of the parts, as well as in the excellence of the
materials selected for the construction, both durability and economy
of repair have been kept in view.
Smaller engines of this class on the same railway have 7-feet
driving wheels, with cylinders 17 inches in diameter, with 24 inches.
stroke of piston.
PASSENGER ENGINE FOR LONDON & NORTH-WESTERN RAILWAY.
The next example of an engine for passenger traffic, is one
designed for the London and North-Western Railway.

H
V
L
M
Ꮐ
N
B
K
U
T
F
C
B
A
E
P
A, Fire box.
Fig. 540.--London and North-Western Railway Passenger Engine.
B, Fire door. c, Fire-brick arch. D, Air holes.
E, Ash pan. F, Body of boiler.
G, Smoke box. H, Chimney. 1, Steam chest and regulator. K, Safety valves. L, Cylinder.
M, Valve chest. N, Leading wheel. o, Driving wheel. P, Trailing wheel. Q, Frame. R, Weigh
shaft. s, Line of valve spindle. T, Reversing wheel and screw. u, Cab. v, Blast pipe
The cylinders are placed inside between the frames, each of which
is cut out of a piece of solid plate, 1 inch thick. The frames extend
the whole length of the engine, and are connected by the buffer
beam, by the cylinders, the motion plate, an angled bracket in front
of the fire box, and by a vertical buffing plate and horizontal cross
plates behind the fire box. The train is drawn from these frames,
704
MODERN STEAM PRACTICE.
3
which are free to allow the boiler to slide upon them at every point
behind the smoke box. The boiler is of Lowmoor plates, inch
thick, and is lap jointed. The steam pressure employed is 120 lbs.
per square inch, and it is controlled by two safety valves. The fire
box is of copper, of the ordinary form, fixed to the external shell
by a square iron frame at the bottom, and by copper screw stays
placed 4 inches apart, and rivetted over at both ends; the roof
being stayed by longitudinal wrought-iron girders, connected to the
external shell by vertical sling stays. The fire box contains a fire-
brick arch extending backward about half the length of the box.
Under this arch are two circular holes, 7 inches in diameter, covered
by doors which can be worked from the foot plate, so that the
amount of air admitted is well within the control of the driver.
The fire doors are of the double lever sliding kind, and invariably
secure the admission of air in the middle of the firing hole.
The boiler is fed by two injectors, to the arrangement of which
particular attention is directed. They are placed vertically behind
the fire box, so as to be easily manipulated by the driver. A ver-
tical screw with a wheel handle regulates the admission of the water
to the injector, which ascends and passes through a clack box (that
can be closed at pleasure) into the boiler along an internal pipe,
carried forward two-thirds of the length of the barrel of the boiler.
By this arrangement all external pipes running forward outside the
boiler are done away with, and greater simplicity and freedom from
accidents are secured.
The boiler tubes are of brass, 192 in number, and each 17% inch.
external diameter. The cylinders are in the smoke box; they have
a diameter of 17 inches and a stroke of 24 inches, the slide valves
being placed vertically between them. Each piston is guided by
one upper and one lower steel guide bar after the fashion of an
outside-cylinder engine. The valve motion is of the ordinary shift-
ing-link class, the valve rods being square at the back part, and
working in cast-iron guides. The reversing motion is effected by a
screw and fly wheel, to obviate the danger of the lever flying back,
as in the ordinary arrangement, and to lessen the effect on the
motion of the train when diminishing the admission of steam.
There are four driving wheels, each 6 feet 7½ inches diameter,
coupled together by outside rods. The leading wheels are 3 feet
7½ inches diameter. The connecting rods are forked, so as to gain
a greater length in proportion to the length of the stroke. The
LOCOMOTIVE ENGINES.
705
cross-head step bushes are of wrought iron case-hardened. The
coupling rods are furnished with circular step bushes of white metal.
All the rods are of steel. The end of the engine is carried upon
six volute steel springs, three on each side, placed below the axle
boxes, all of which are of solid brass, those for the coupled wheels
working in steel guides. The total heating surface is 1102 square
feet. The fire-grate area is 15 square feet.
Distribution of weight, when in working order, on the leading
axle 9 tons 9 cwts., on driving axle 11 tons, on trailing axle 8 tons
15 cwts.; total, 29 tons 4 cwts. Total wheel base 15 feet 8 inches.
FOUR-COUPLED BOGIE PASSENGER TANK ENGINE ON NORTH
BRITISH RAILWAY.
In Fig. 541 we give sectional and horizontal views of a new
type of engine designed by Mr. D. Drummond, locomotive super-
intendent of North British Railway. Originally intended to work
the company's coast traffic, the engine has been found most useful
for branch work generally.
The cylinders are 17 in. diameter, stroke 26 in. There are four
coupled wheels, 6 ft. diameter; diameter of bogie wheels 3 ft. 6 in.;
total wheel base 21 ft. I in.
The boiler barrel is telescopic, 10 ft. 1 in. long, and 4 ft. 4 in. diameter
outside of the front plate. It is composed of two rings of plates,
each being in one plate. The longitudinal seams are butt-jointed,
and secured outside and inside with butt straps, strongest in their
transverse section, 7½ in. wide and 5% in. thick, double rivetted.
The circular laps are 2½ in. wide and single rivetted. The boiler
barrel is secured to the smoke-box tube plate by a solid rolled angle-
iron ring, 54 in. by 34 in. by I in. thick, double rivetted to the
boiler barrel and single rivetted to tube plate. The outside fire-box
shell is 5 ft. 5 in. long outside, and 4 ft. 64 in. at centre line, and
4 ft. I in. at bọttom. The depth of the back end below the centre
line of the boiler is 4 ft. 4 in. to bottom of foundation ring, sloping
to 5 ft. 6 in. at the front end. The corners of the fire-box are made
to a radius of 6 in. outside. The sides and top of the fire box shell
are made in one plate, flanged, double rivetted at the longitudinal
portion only, and single rivetted to the outside shell of the fire-box.
The fire door is I ft. I in. by 1 ft. 4 in., and is fitted with a solid
wrought-iron ring 14 in. thick by 2½ broad, rivetted with a single
45
plate of fire-box, 5% in.; back and throat plates, 5% in.; barrel plates,
row of rivets. The thickness of the plates is as follows:-Covering
S
F
CI
T
D
L
M
N
G
H
IX
U
B
A
N'
I
D
R
V
W
S
z
Y
A, Fire box.
Fig. 541.-Longitudinal Section and Half Plan of Four-coupled Bogie Passenger Tank Engine, North British Railway.
B, Fire-brick arch. c, Fire bars. D, Tubes. E, Smoke box. F, Funnel. G, Steam dome and safety valves. H, Whistle. 1, Ashpan.
L, Cylinder.
L, Cylinder. M, Crosshead, motion bars, &c. N, Connecting rod. N', Side rod. o, Cranked shaft.
link. Q, Weigh shaft.
K, Stays.
handle.
P, Double eccentrics and
R, Regulator handle. s, Main framing. T, Bogie and wheels. u, Driving wheel. v, Trailing wheel.
w, Brake
x, Springs. Y, Tool box, &c. z, Coal space, &c.
706
MODERN STEAM PRACTICE.

LOCOMOTIVE ENGINES.
707
13
½ in.; tube plate, 3/4 in. The inside fire box has a circular top and
is of copper, 4 ft. 55% in. long by 3 ft. 25% in. wide at top, and 4 ft.
105% in. long by 3 ft. 65% in. wide at bottom. The inside of the
top of the fire box is 11 in. above the centre line of the boiler.
There is water space of 2 in. all round at the bottom of the box,
which is increased at the top of the back plate to 5 in. The tube
plate is flanged at the top to 2 in. radius outside, and is 4¼4 in. broad,
and 3% in. radius outside and 518 in. broad at the bottom. The
tube plate is 3 ft. 8½ in. wide at the top. Back plate flanged at
the top to 2 in. radius outside and is 44 in. broad and 33% in.
radius outside, and 51% in. broad at bottom. It is dished at fire
hole. The crown and sides are in one plate. The sides next to
tube plate are made with a pocket equal to the extra width of tube
plate at this part, and joined to the plain part of the box with 12 in.
radius. Thickness of copper plates: tube plate, % in. and in.;
back plate, in.; covering plate, in. The fire box is single
rivetted, except at the foundation ring, which is double rivetted. Lap
of copper plates, 24 in.; diam. of iron rivets, 18 in., 1% in. pitch.
32
9
1
32
9
16
13
16
16
The stays are of copper ½ in. diameter, twelve threads per inch;
each bar was tested to stand being bent round close, cold, without
fracture. The pitch of stays 4 in. The crown of the box is stayed
with 13 in. in copper, and I in. diameter stays in the iron plates,
twelve threads per inch, with round collars and square ends screwed
in from inside, having nuts on the inside screwed on the top of the
copper plate. The ends are rivetted over on outside shell. The
copper tube plate is secured to the boiler barrel by eight palm stays.
The foundation ring is made from scrap iron of two bars welded
in the centre 3½ in. deep by 2 in. broad, corners 53% in. radius out-
side and 33% in. inside. The bars have projections at each of the
corners to allow for the radius outside, so that no v's were required.
The boiler contains 220 brass tubes, 10 ft. 8 in. long by 134 in. ex-
ternal diameter, Nos. 10 and 11 B. W. G., 34 in. water space; ex-
panded at both ends with Dudgeon's patent tube expander; steel
ferruled and carefully caulked in the fire box, and projecting ½ in.
through the smoke-box tube plate. No ferrules in that end.
The dome is of cast iron 3/4 in. thick at the top and I in. thick
at bottom, flattened to 1334 in. diameter on top for receiving the
safety-valve seatings. Safety valves and seatings are Ramsbottom's,
of the best gun metal. The joints were scraped up perfectly steam-
tight and made with boiled oil only.
708
MODERN STEAM PRACTICE.
The chimney is 13 ft. from rails to top, 16 in. diameter at bottom
and 17 in. diameter at top inside, made of one plate 4 in. thick. The
base plate is best Yorkshire iron 8 in. high, solid welded, and
flanged; secured to the smoke-box by ten 5% in. rivets. Plate tube
butt-jointed with a 3½ in. strap, in. thick on the inside. All the
rivets are countersunk and filed flush. The chimney is fitted with
a cast-iron top, as illustrated.
16
The main frames are of Yorkshire iron in one plate from the
back buffer beam to the front end of the cylinders, where they are
welded. The front part is forged and solidly welded to the frame.
They are placed 4 ft. 1½ in. apart from the back end to the front
of the cylinders, where they are 3 ft. 11½ in. apart. Their total
length is 30 ft. 6 in.; from the inside of the front buffer beam to
the centre of the bogie, 5 ft. 4 in.; from the centre of bogie to centre
of driving axle, 9 ft. 10 in.; from centre of driving to centre of trail-
ing axle, 8 ft.; from centre of trailing axle to end of frame, 7 ft. 4 in.
The height from the rails to the top of the frame is 4 ft.; and the
depth of the frame over axle boxes, 18 in. The front buffer beam
is 1334 in. deep and 14 in. thick by 7 ft. 25% in. long. It is stif-
fened with two 2½ in. by 2½ in. by ½ in. angle irons as shown.
The back buffer beam is 15 in. by 14 in. thick by 7 ft. 25% in.,
with a slot cut for draw bar.
The horn blocks are of the best tough cast iron free from defects,
the sliding surfaces, which are to be 54 in. wide, are continued
across the top, and the flange with which the same is fixed to the
frame is continued round in a similar manner.
The driving and trailing axle boxes are crucible cast steel, 2 in.
thick at the crown, 15% in. and 1½ in. thick at sides, 7% in. wide,
a flange 1 in. thick by 1 ft. running down the sides. The bushes
also recessed at the top for white metal. A gun-metal keep is
placed below the axle
16
The driving springs are volutes, 7 in. diameter by 834 in. long.
The trailing springs are composed of one plate 5 in. broad by
½ in. thick, and seventeen plates 5 in. broad by 3% in. thick, and
one wrought-iron packing piece 5 in. broad by ½ in. thick, 3 ft.
6 in. span and 3½ in. camber when loaded.
The driving, trailing, and bogie axles are of the best Yorkshire
iron, double faggotted. The wheels are solid forged, the coupled
wheels having forged balance weights and crank bases. The tyres
are solid rolled crucible cast steel, 3 in. thick on tread by 5½ in.
7
6
I
LOCOMOTIVE ENGINES.
3
709
wide, and secured on the inside by Drummond's patent clip ring
tyre fastening. The cylinders are 17 in. diameter and 26 in. stroke,
2 ft. 3 in. centres; the back ends are cast solid. They are lagged
with wood and covered with sheet iron. The thickness of metal in
the cylinder barrel is I in.; in the steam chest, ½ in.; the steam
ports are 13% in. by 14½ in.; the exhaust port 234 in. by 14½ in.;
bridges, 1% in.; width over faces, 1034 in. The cylinders have an
inclination 1 in 34. The slide valves are made of gun metal; they
have an outside lap of I in., a travel of 4 in., and a lead of ½ in.
The buckle is of wrought iron, solid with spindle. The pistons are
of gun metal 4 in. deep, with two cast-iron rings 3/4 in. wide by
in. thick. The piston rods and crossheads are forged solid of
selected Yorkshire iron. The slide blocks are of cast iron of the
same quality as the cylinders, 12 in. long by 34 in. wide, forced
on the gudgeon pins with a pressure of 4 tons, and accurately fitted
to the slide bars. The connecting rods are forged in one piece,
without weld, from the best selected scrap iron; section at large
end, 5 in. by 2 in.; at small end, 3½ in. by 2 in.; and 6 ft. 6 in.
centre to centre. The outside rods are made of the very best
selected scrap iron forged in one piece without weld, and fitted
with gun-metal bushes. Bushes are pressed into the rod ends,
secured in their places with taper pins and set screws. The inter-
mediate valve spindles are made of the best selected Yorkshire
scrap iron 3½ in. diameter. The bushes are gun metal.
The reversing gear is of the screw type with cast-iron column
and wheel, worked by a bell crank and rod. The eccentric rods
are made from the best selected scrap iron, having a foot forged on
for bolting to the straps. The straps are of cast iron and fitted
together without liners. The two eccentrics of each side are cast
together in halves, the outside eccentrics are bored, recessed, and
tapped to receive the screw, securing it together. The inside has a
round flange which abuts against a similar flange on the opposite
eccentrics; both flanges are tightly embraced with a wrought-iron
hoop, bolted together with two I in. diameter bolts. A projecting
lug is cast on the outside eccentric, and carefully fitted to the web
of the crank for driving the eccentrics. The throw of the eccentrics
is 6½ in.; they are 25% in. wide.
The boiler is fed by two injectors, No. 8, with movable cones. A
tank is provided on each side of the engine to carry 950 gallons of
water. The iron plates are in., excepting the flanged plates for
3
16
710
MODERN STEAM PRACTICE.
5
the splasher's sides, which are of Yorkshire iron 14 in. thick. The
angle irons are 134 in. by 134 in. by in.; rivets ½ in. diameter
and 1½ in. pitch in bottom. A cast-iron dry sand box is placed
on each side of smoke box. The injector pipes are of copper solid
drawn. Delivery pipe, 1½ in. external diameter, by No. 10 B. W. G.;
feed pipes, 134 in. external diameter, by No. 10 B. W. G.; steam
pipe, 1/4 in. external diameter, by No. 10 B. W. G. All flanges
have been scraped up to a true surface so as to make a perfectly
steam-tight joint, with boiled oil only.
The engine is fitted with the Westinghouse automatic air brake
on the driving and trailing wheels.
The bogie frames are Yorkshire iron, I in. thick by 8 ft. 9% in.
long. A cast-iron frame is fitted between the frames, with a mov-
ing frame supported by two volute springs at the ends. The bogie
centre is rivetted on to a 1% in. thick transverse plate, which is
rivetted to the main frames with 4 in. by 4 in. by 3/4 in. angle irons.
The centre pin is 2½ in. diameter, fitted with a wrought-iron washer
and cotter underneath. The centre on the moving frame is ar-
ranged for and fitted with oil cups for lubricating the moving sur-
faces. The cast-iron frame is rivetted to the plate frame as shown;
frames 2 ft. 84 in. apart, and wheel centres, 6 ft. 6 in.
The springs are composed of twelve steel plates, 5 in. broad by
½ in. thick, and one wrought-iron packing piece, ½ in. thick, 4 ft.
centres, 2½ in. camber loaded.
The boiler was tested previous to being put in the frames by hot
water to a pressure of 200 lbs. per square inch, by the hydraulic
pump; and with steam to 150 lbs. per square inch.
PASSENGER ENGINES FOR GREAT SOUTHERN AND WESTERN
RAILWAY OF IRELAND.
The frames are inside, of solid plate, I inch thick. They are
attached at one end to the cylinders, and at the other end to a cast-
iron foot plate, and are stayed by the motion plate and by a plate.
in front of the fire box. The boiler is of ½-inch Lowmoor plate,
4 feet inside diameter. Each ring of the boiler is formed of a single
plate; and the two sides and top of the outside fire-box casing are
also formed of a single plate. The fire box is of ½-inch copper, the
tube plate being 3/4 inch thick, and the two sides and crown are
formed of a single plate. There are 185 tubes of brass. The cylinders
LOCOMOTIVE ENGINES.
711
are inside, and 17 inches in diameter, the length of stroke being
22 inches. The driving wheels are 6 feet 6 inches in diameter,
and are coupled to the trailing wheels. The valve motion is of the
ordinary kind, a screw being used for reversing. The coupling rods
have cast-iron bushes, lined with white metal. The axle boxes are
of cast iron, and have the brasses cast into them. The horn blocks
of cast steel are attached to the frame all round the opening for the
axle box; they have adjustable wedges for taking up the wear of
the axle boxes. The slide blocks are of cast iron, and the little end
steps are of wrought iron, case-hardened. The boiler is attached
to the frames at the smoke-box end, is free to expand at the fire-
box end, and does not touch the motion plate. The heating surface
consists of: tubes, 835 superficial feet; fire box 96, and fire grate
17½ superficial feet. The wheel base is from the driving to the
leading wheels 7 feet, and from the driving to the trailing wheels
7 feet 9 inches. The weight on the leading wheels is 10 tons, on
the driving wheels it is 108 tons, and on the trailing wheels it is
9.5 tons, the total weight being thus 30.3 tons.
The performance of these engines is shown in the following
table:-

Length
of
Speed
Journey.
per Hour.
Average Load
of Six-wheel
Carriages.
Miles.
1652
Miles.
Carriages.
Carriages.
Maximum Load
for Average
of whole Journey.
Maximum
Load for part
of Journey.
Average Con-
sumption of Coal
per Engine Mile,
252,554 Miles.
Ibs.
Carriages.
""
""
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8.03
11'54
14
38
7.64
10'54
13
8.56
14.67
25.64
21
30
8.59
14'47
16
AVERAGE WEIGHT OF CARRIAGES.
First class,
Second class,
Third class,
Tons. cwts.
Tons. cwts.
ΙΟ 3
...
9
8
Composite,
Post-office vans,
8
ΙΟ
ΙΟ
O
...
...
9 IO
Guards' vans,
9
12
The coal was from South Wales, of good quality, though much
of it was small, being broken in shipment.
These engines have run an average distance of 48,748 miles in
each interval between general repairs. The cost for repairs, exclu-
sive of shop expenses and tools, has been a trifle under Id. per
mile.
The light passenger engines are of similar construction; the chief
dimensions are:-Diameter of cylinders, 16 inches; length of stroke,
712
MODERN STEAM PRACTICE.
20 inches; diameter of the driving wheels, 5 feet 8 inches; the wheel
base is, from the driving to the leading wheels 6 feet, and from the
driving to the trailing wheels 7 feet II inches. The weight on the
leading wheels is 9.2 tons, on the driving wheels it is 9.2 tons, and
on the trailing wheels it is 8.8 tons, the total weight being thus 27.2
tons. The heating surface consists of: tubes, 774 superficial feet;
fire box 88%, and fire grate 16 superficial feet. There are 175 tubes.
The performance of these engines is shown in the following
table:-

Length
of
Journey.
Speed
per Hour.
Average Load
of Six-wheel
Carriages.
Miles.
Miles.
Carriages.
1652
32
6.17
Carriages.
9.64
Maximum Load
for Average
of whole Journey.
Maximum
Load for part
of Journey.
Carriages.
Average Con-
sumption of Coal
per Engine Mile,
644,412 Miles.
lbs.
IO
""
30/2
6.82
11 42
13
30/2
4'93
7.64
ΙΟ
32/2
5.65
12'00
12
26½
7'00
11:55
18
23.36
282
7.68
16.66
25
""
2834
7.17
15'00
15
28
""
7·18
14:58
15
These engines have run an average distance of 54,635 miles in
each interval between general repair. The cost of repairs, exclu-
sive of shop expenses and tools, has averaged four-fifths of Id. per
mile.
GOODS ENGINE FOR GREAT SOUTHERN AND WESTERN
RAILWAY OF IRELAND.
In Fig. 542 is shown an example of a locomotive specially adapted
for goods traffic. It is a six-wheeled coupled goods engine made
for the Great Southern and Western Railway of Ireland, and is
believed to be one of the most powerful goods engines in use upon
an Irish railway.
There are no frames outside the wheels. The two inside frames
extend the whole length of the engine, and are of solid plate, 1 inch
thick, connected in front by the buffer beam and cylinders, under
the boiler barrel by the motion bracket in front of the fire box, by
a strong %-inch angled plate, and by a heavy cast-iron block fixed
firmly between the frames, forming the base for the foot plate.
The train is drawn from this cast-iron block, and the boiler is free
to expand along the frames. The horn blocks are of cast steel, and
extend on both sides of, and over, the top of the openings for the
LOCOMOTIVE ENGINES.
713
axle boxes. The axle boxes are of cast iron with brass bearings,
and they are adjustable by wedge pieces recessed into the horn
blocks so as to take up the wear; these are held up by screws
inserted from the back. The boiler is of Yorkshire plates, ½ inch
thick as a rule, but 3/4 inch where the tubes are fixed. The fire box
is of copper, of the ordinary square form, ½ inch thick, swelled to
3/4 inch where the tubes are fixed, and connected to the outside shell
in the ordinary way.

G
E
F
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C
T
B
Д
P
P
R
L
M-
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Fig. 542.-Great Southern and Western Railway of Ireland Goods Engine.
A, Fire box. B, Fire door. c, Body of boiler. D, Smoke box. E, Chimney. F, Steam chest.
G, Safety valve. H, Injector. 1, Cylinder.
K, Valve chest. L, Leading wheel. M, Driving
wheel. N, Trailing wheel. o, Frame. PP, Wedges for axle boxes. Q, Outside connecting rods.
R, Weigh shaft. s, Line of valve spindle. T, Reversing wheel and screw. u, Cab. v, Steam pipe
for counter-pressure brake system. w, Spark trap. x, Blast pipe.
The boiler is fed by two injectors, placed horizontally on each
side of the fire box. Some boilers now being made have ver-
tical injectors feeding through the back of the fire box into the
front, thus avoiding all outside pipes, as described in the London
and North-Western Railway passenger engine. The tubes are
of brass, 160 in number, and each 2 inches external diameter.
The safety valves are arranged to prevent weighting by the driver.
A spark arrester of wire, of the inverted truncated form, is placed
in the chimney. The cylinders are 17 inches diameter, with a stroke
of 24 inches; the slide valves working vertically between them.
The valve motion is of the usual form, the link being shifted by a
714
MODERN STEAM PRACTICE.
screw motion, so as to insure absolute control by the driver. All
the wheels are coupled, and have a diameter of 5 feet 14 inch.
The tyres and the axles are of cast steel. The coupling-rod ends
are furnished with cast-iron bushes, lined with white metal. The
small ends of the connecting rods have wrought-iron steps, case-
hardened. The sand boxes are fixed in the smoke box to insure
the dryness of the sand. The counter-pressure steam brake is
applied, in order to obtain a greater degree of safety in descending
inclines, and to enable the driver to assist in stopping the train.
The heating surface of this engine is :-
In the tubes,
fire box,
: :
:
846 sq. feet.
93
Total,
•
The fire-grate area is about 17.5 square feet
939 sq. feet.
The weight upon the wheels, when the engine is in working
order, is:-
On the leading wheels,
...
driving wheels,
trailing wheels,
Total,
::
The total wheel base is 15 feet 6 inches.
Tons. cwts. qrs.
IO
12
I
...
II
6
8
15
3 2
30%
14
2
The engine will draw a weight of 607 tons on a level at a speed
of 25 miles an hour, with a working pressure of 140 lbs. Its average
consumption of coal is 35 lbs. per mile with a load of fifty-five
waggons.
The performance of these engines is shown in the following
table:-

Length
of
Journey.
Time occupied
in Running.
Time occupied
at Stations.
Speed
per Hour.
Average
Load for
whole
Journey.
Maximum
Load.
Miles. Hours. mins.
Hours. mins.
Miles.
Waggons. Waggons.
Average Con-
sumption of Coal
per Engine Mile,
1,028,826 Miles.
lbs.
165½
107
107
96%
1652
107
107
962 5 29
Q IS 15 1000 IN 105
9
22
5 50
40
25
37
3233 m
26
1734
31'5
50
16
1814
32'3
50
46
19
24.8
51
52
1734
29.9
49
3
8
194
27'7
37.6
52
40
4
56
19
30.8
54
36
I 45
19
30.7
52
3 30
172
27'5
52
The waggons, which are nearly all covered, weigh from 434 to
LOCOMOTIVE ENGINES.
715
5½ tons, and carry 6 tons. The probable average load is from
3 to 4 tons.
These engines have run an average distance of 44,232 miles in
each interval between general repair. The cost for repairs, exclusive
of shop expenses and tools, has been o'9d. per mile.
GOODS ENGINE-BOMBAY, BARODA, & CENTRAL INDIA RAILWAY.
This engine has been specially designed for the working of heavy
traffic in India, where the gauge, 5 feet 6 inches, has given great

E
K
F
D
C
A
P
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M
S
G
R
Fig. 543.-Bombay, Baroda, and Central India Railway Goods Engine.
a. Fire box. B, Fire door. c, Body of boiler. D, Smoke box.
hole door. H, Injector. I, Cylinder. K, Steam chest.
E, Chimney. F, Steam chest. G, Man-
L, Leading wheel. M, Driving wheel.
N, Trailing wheel. o, Frame. P, Weigh shaft. Q, Line of valve spindle. R, Reversing lever
s, Cab. T, Blast pipe. u, Spark trap.
facility for the construction of a powerful engine on a reasonable
length of wheel base. It will be found that several appliances exist
for suiting this engine to the requirements of a colonial railway, and
in this respect it differs from ordinary goods engines in this country.
The frames consist of a pair of longitudinal plates, 1% inch thick,
placed inside the wheels, connected at various intervals by the buffer
beam, the cylinders, the motion plate, a strong cross bracket in
front of the fire box, a similar one behind it, and by strong plates
and angle irons at the foot-plate end. The train is drawn by a pin
inserted through these plates, and, as the boiler has no positive
attachment to the frames behind the smoke-box tube plate, it is free
from all strain arising from the haulage of the train.
716
MODERN STEAM PRACTICE.
The boiler is of the ordinary form, 4 feet 4 inches diameter, and
10 feet 9 inches long, of Yorkshire plates, ½ inch thick. The fire-
box shell is of the same material and thickness, deep in front, but
sloping backwards, with a long inclined fire grate suitable for burn-
ing the small and inferior coal usually procurable in India. The
fire box proper is of copper, of the same tapering form as the exter-
nal shell, all the plates being ½ inch thick, but the tube plate is
swelled to % inch where bored to receive the tubes. The wrought-
iron roof girders in this engine run transversely, so as to obviate the
necessity for their being so deep as would have been requisite had
they been placed longitudinally. A spark arrester of wire is fixed
on the top of the blast pipe, and extends into the chimney.
The water is supplied to the boiler by two injectors, either of
which is capable of delivering the amount of water usually evaporated.
The tubes are of brass, 222 in number, and each 2 inches external
diameter. The cylinders are 18 inches diameter, with a stroke
of 24 inches; the slide valves being placed vertically between
them. The valve motion is of the straight-link double-lever
form. All the wheels are coupled, and are 5 feet diameter on the
tread. There is a cab with a double roof of wood and of iron over
the foot plate to shelter the driver from the rain and the great
heat. A cow catcher is fixed in front of the buffer beam to fit the
engine for use on the unfenced railways of India.
The escape of smoke, when the engine is standing still, is pre-
vented by the introduction of air above the surface of the fire by
means of jets of steam through hollow stay tubes at the front and
back of the fire box.
The heating surface of this engine is:-
In the tubes,
fire box,
Total,
...
...
The fire-grate area is about 25'5 square feet.
12780 sq. feet.
99'3 ""
1377'3 sq. feet.
The engine will draw a weight of 694 tons on a level at a speed
of 25 miles per hour, with a working pressure of 140 lbs.
Its con-
sumption of coal is 59.25 lbs. per mile for an average load of 490
tons. The cost of repairs has been 2·15 annas, or, say, 3·227. per
mile.
A peculiar feature of this engine is the position of the hind axle
under the fire box, permitted by the long sloping fire grate, and by
LOCOMOTIVE ENGINES.
717
the shallowness of the end of the fire box.
This arrangement
answers the double purpose of allowing a comparatively short wheel
base and an equable distribution of the weight of the engine upon
the wheels, II tons, II tons 16 cwts., and II tons 16 cwts., being
carried on the leading, the driving, and the trailing wheels respec-
tively. As there is less weight on the leading wheels than on either
of the other pairs, it might be supposed that there would be danger
of the engine running off the line under certain circumstances; but
this is not the case, as the weight actually upon the springs of the
leading wheels is greater than on those of the driving wheels.
FURNESS RAILWAY TANK ENGINE.
This locomotive was constructed for the conveyance of mineral
or heavy goods traffic over a portion of the Furness railways, having

E.
F
D
C
A
B
T
ਪੰਜਾ
K
H
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H
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S
Fig. 544.-Furness Railway Tank Engine.
A, Fire box. B, Fire door. c, Body of boiler. n, Smoke box. E, Chimney. F, Steam chest. G, Man-
hole door. H, Injector. I, Cylinder. K, Valve casing. L, Leading wheel.
N, Trailing wheel. o, Frame. P, Weigh shaft. Q, Line of valve spindle.
s, Coal box. TT, Sand boxes. u, Brake gear. vv, Brake blocks.
M, Driving wheel.
R R, Water tank.
gradients of 1 in 100, and 1 in 80, &c., for 11 miles. It was desired
to get as powerful an engine as possible on six wheels, with inside
cylinders, and to carry fuel and water sufficient for a considerable
distance, in case it was found necessary to take the train forward on
the main line. The cylinders are between the two frames, which
extend the whole length of the engine, and are 14 inch thick.
718
MODERN STEAM PRACTICE.
16
Besides being connected by the cylinders, the frames are tied by two
cross brackets under the boiler, by the buffer plank in front of the
cylinders, and by four cross ties behind the fire box; the frames are
further strengthened externally by heavy angle irons arranged for
carrying the water tanks. The train is drawn from the foot plate,
and as the boiler is free to slide in the frames, all haulage strain is
removed from it, as well as that arising from a too unyielding con-
nection with the frames. The horn blocks are of cast iron. Those
of the driving and the front axles are carried round the top of the
horn plate to strengthen the frames. The boiler is of Yorkshire
plates, ½ inch thick as a rule, but 3/4 inch thick where the tubes are
fixed. The fire box is of copper, inch thick, of the ordinary square
form, connected with the outside shell by a square wrought-iron
frame at the bottom, and by copper screw stays at the sides, front
and back. The roof is stayed by longitudinal wrought-iron girders,
connected by means of sling stays, with T irons rivetted to the roof
of the external casing. The proper combustion of the fuel is effected
by the admission of air through the fire door, deflected on to the
surface of the fire by the ordinary scoop, aided by a fire-brick arch,
placed across the fire box under the tubes, which serves also to pre-
vent the emission of sparks through the tubes and chimney. The
fire bars are simple flat pieces of iron, with two corners cut off, and
are supported by two cross bars, with pins to keep the distances
equal. The boiler is fed by two injectors, and the engine can there-
fore stand any required time, when waiting as a pilot, without being
set in motion to obtain water for the boiler. The tubes are of brass,
186 in number, and each 2 inches external diameter. The cylinders
are 18 inches diameter, with a stroke of 24 inches, and the valves
work vertically between them. The valve gearing is of the ordinary
shifting-link class, and is reversed by the common lever handle.
All the wheels are coupled, and have a diameter of 4 feet 6½ inches.
The end of the engine is carried by a transverse elliptical spring.
A coal bunker and cab are conveniently placed on the foot plate.
The arms of the crank axle, which is of Bessemer steel, are hooped,
to prevent accident in case of fracture.
As the engine is intended to work in either direction, the cab is
arranged as a screen both forward and backward.
Tanks to contain 1000 gallons of water are placed along each side
of the smoke box, the boiler, and the fire box above the level of the
frame. The coal is carried behind the engineman's platform in
LOCOMOTIVE ENGINES.
719
bunkers, which hold 2 tons. A powerful screw break is attached to
the engine, actuating six blocks in front of each of the six wheels.
Sand boxes supply sand in front of, or behind each wheel, as
required, and are so contrived as to be opened or closed by one set
of levers for each direction of the engine.
The heating surface in this engine is:-
In the tubes,
>>
fire box,
...
Total,
..
...
The fire-grate area is nearly 15 square feet.
...
1047.8 sq. feet.
96.2
1144'0 sq. feet.
The weight upon the wheels, when the engine is in working order
and the tanks full, is:-
On the leading wheels,
driving wheels,
...
...
trailing wheels,
Total,
...
...
The total wheel base is 15 feet.
Tons. cwts.
...
:
13
16
...
...
...
14
I I
13
8
...
4I
15
...
The engine will draw a weight of 872 tons on a level at a speed
of 20 miles per hour, and a weight of 367 tons up an incline of I in
80 at a speed of 1134 miles per hour, with a working pressure of
145 lbs. to the square inch. Its consumption of fuel with this latter
load has been 40'16 lbs. per mile, taking the whole trip, which
includes the descent as well as the ascent of the gradients before
alluded to. The cost of repairs has not been taken into account,
as the distance run does not usually exceed 76 miles per day.
This engine was designed to obtain as much power as was pos-
sible upon six wheels. The frames have been put inside the wheels,
to allow convenient access to the motive parts; the cylinders being
placed inside, to secure great structural stability. The tanks are
arranged alongside the boiler to distribute equal weights upon the
wheels, whether the tanks are full or empty. The distribution of
the weight, when they are empty, is:-
On the leading wheels,
driving wheels,
""
trailing wheels,
...
Tons. cwts. qrs.
II 7 2
II 16 2
ΙΟ
8 2
It is believed that the engine has in all respects answered the
purpose for which it was built.
For engines with rigid frames, a simple and convenient arrange-
720
MODERN STEAM PRACTICE.
ment has been applied, in the shape of a sliding top to the leading,
and sometimes to the trailing axle boxes. This cap has a double
incline in the transverse direction of the engine. The axle box has
also similar corresponding inclines, so that when passing round a
curve the leading wheels are free to move sideways, without at once
carrying the engine with them. As the axle box incline must at
the same time lift the engine when so sliding, the gravity of the
engine tends to make it assume its normal position on the axle
boxes as soon as the road permits this to be done.
NARROW-GAUGE ENGINES FOR STEEP INCLINES.
To enable engines to draw heavy loads up excessively steep
inclines a system invented by Mr. Fell has been adopted, in which
a set of horizontal wheels are pressed against a central rail, giving
in this manner additional traction hold. A railway on this system
was worked successfully over Mont Cenis during the construction
of the tunnel through that mountain.
The Festiniog Railway in North Wales is the smallest gauge line
in Great Britain used for passenger traffic. The gauge is only 2 feet,
with correspondingly small and light rails and roadway generally.
Some of the curves are as low as 2 chains radius. The steepest
gradients are I in 60 and I in 80.
The carriages are peculiarly constructed, to suit so narrow a
gauge. They are 10 feet in length, and fully 6 feet in breadth and
height, with four wheels 18 in. diameter. The seats are arranged
so that the passengers are seated along the central part of the car-
riage, back to back. The engines weigh about 7½ tons, with four
coupled wheels each 2 feet diameter, the cylinders being 8 inch dia-
meter with a 12-inch stroke.
The small railway line on the Righi Mountain in Switzerland has
a gauge of I metre, and as the gradients are excessively steep, in
some cases as much as 1 in 4, it is necessary to provide for greater
grip of the locomotive than can be obtained by weight on smooth
wheels only. This is accomplished by placing a central toothed
rail or "rack" between the bearing rails, and by means of
suitable gearing sufficient "bite" is obtained. The engine, which
has a vertical boiler, draws only one carriage. The radii of the
curves are 180 metres.
The Vesuvius Railway leads from the foot of the cone to the
LOCOMOTIVE ENGINES.
721
summit, and has a double line of rails with fixed engines which
wind the carriages up and down by means of steel wire ropes. The
inclination is very steep, sometimes about 40°, and the carriages are
so arranged that the seats are kept horizontal, and the wheels are
arranged to grip the rails in such a manner as to prevent their
leaving the rails, and powerful automatic brakes are fitted to prevent
accident in the case of a rope breaking.
A light system of railroad has been introduced into Canada, the
gauge being 3 feet 6 inches. The gradients are steep and the
curves sharp. The permanent way has timber sleepers, and the
rails are flat-bottomed, weighing 56 lbs. per yard, being fastened to
the sleepers with dog spikes. The engines are coupled in eight
wheels, and weigh 30 tons, taking a load of 360 tons up a gradient
of I in 60. Curves are used in some places of 500 feet radius on
gradients of I in 60 and I in 70. In one case a gradient of 1 in 50
extends for four miles.
I
ENGINES FOR NARROW-GAUGE MINERAL LINES HAVING STEEP
GRADIENTS.
The lines leading from the numerous mines and works in our
mineral and manufacturing districts to the main lines of railway
were formerly merely tramways worked by horses, but the need for
more ready and cheaper communication soon led to the introduc-
tion of a special class of locomotive engine fitted for such work.
The following are the details of tank engines employed on one
of these branch lines about 2 miles in length, connecting the lime
quarries with the main line of railway. The quarries are situated
at a height of nearly 1000 feet above the sea; the country is very
bleak, and much exposed to snow and rain storms in winter. Start-
ing from the lowest level the line runs 1400 yards 1 in 80, 360 yards
I in 12, 450 yards 1 in 15, 630 yards I in 18, 680 yards I in 15. The
gauge of the rails is 32 inches; the rails, 28 lbs. per yard. This
single line was originally indifferently constructed, and crosses a
deep ravine on a narrow embankment about 150 yards in length,
before commencing the steep ascent of 1 in 12, with curves of one
and a half chains in some but not dangerous parts of the line. The
first experimental engine on this line was designed and constructed
by Messrs. Hawthorn & Co. of Leith, the usual formula being
adopted, and which has been found to be quite correct in practice.
46
722
MODERN STEAM PRACTICE.
The cylinders were 8 inches in diameter, with a piston stroke of 15
inches. Steam pressure, 120 lbs. in the boiler. There were four
wheels coupled, 27 inches diameter, with a wheel base of 42 feet.
The engine in working trim weighed 7 tons 5 cwts. This locomo-
tive, when put to work, was found to take up the gradient of 1 in
12 about its own weight, besides itself, at 4 to 6 miles per hour in
any state of the rails, sand being used when necessary, and it could
be started or stopped with the load on the incline, the brake power
having ample control over the motion of the train. Taking the
foregoing result by calculation from the formula 2, with four-
fifths of the boiler pressure for average pressure in cylinders, or
96 lbs. against 120 lbs., the engine should take about 7½ tons gross
load, besides its own weight, allowing 224 lbs. per ton friction for
load, and limiting the possible adhesive force to one-fifth of engine
weight on incline. The average cost of maintenance for this engine
amounted to 12s. per day.
D'
Another engine constructed for this narrow-gauge line had cylin-
ders 10 inches diameter, stroke of piston 15 inches, with 150 lbs.
steam-boiler pressure; wheels 27 inches in diameter, coupled 5 feet
apart, or wheel base. The weight in working trim being II tons
II½ cwts., it was found on trial to take over the I in 12 gradient a
load of 18 tons, composed of empty trucks, with 125 lbs. per square
inch in boiler, and holding this pressure well at the summit of the
incline. With 150 lbs. steam pressure in the boiler it is calculated
to take a load of 20 tons, with a margin of one-fifth more, as a pos-
sible result in favourable circumstances.
A line of railway in Portugal, which had been formerly worked
with about seventy mules, with drivers, &c., at a considerable cost,
may be taken as a favourable example of what we may term nar-
row-gauge lines with small-wheeled mountain locomotive engines.
The railway runs a distance of II miles over a very rugged country,
crossing many ravines and torrents, and with many curves, some as
sharp as 12 to 2 chains radius. The gradients, starting from the
sea level to the mines which supply copper ore, are as follows:-
(1) Rising I in 23 to 1 in 1000, 34 miles; (2) falling 1 in 24 to 1 in
I
60, 2 miles; (3) rising 1 in 30 to 1 in 190, 2 miles; (4) falling 1 in 50
to I in 19, 1½ mile; (5) rising I in 1500 to I in 43, 3 miles.
gauge is 3½ feet; rails, 35 lbs. per yard.
The first engine employed had 9-inch cylinders, with a piston
LOCOMOTIVE ENGINES.
723
stroke of 15 inches; steam pressure in boiler, 130 lbs.; the wheels
being 27 inches diameter. This engine hauled 20 tons, waggon
and ore, up the incline of I in 19, and could have done a great
deal more (waggons, say 22 cwts. each, carrying 2 tons of ore);
also thirty waggons and forty men over the 1 in 30-36 tons, in
splendid style; engine in trim weighing 105 tons. The calcula--
tion, as before, meets this load on the 1 in 19 gradient exactly,
namely, 20 tons, and on 1 in 30 gives 38 tons. It was found from
experiments made with such engines that this limit may be
practically increased one-fifth, thus leaving a large margin for
effect.
Small engines coupled together.-Whilst the experiments were
going on in Derbyshire for the proposed Mont Cenis Railway, the
question was discussed whether the central-rail system possessed
any advantage over ordinary locomotives and railway lines, likely
to recommend its adoption unless in very exceptional circumstances.
One point raised was, whether two engines coupled together could
not be used with as much or more advantage than a single engine
of twice the weight.
An experiment was therefore made with two of these small
engines; the front engine having an 8-inch cylinder, 15-inch
stroke of piston, 27-inch wheels, and 120 lbs. steam; and the second
one, 9-inch cylinder, 15-inch stroke of piston, 27-inch wheels, and
150 lbs. steam. These coupled together took over an incline of 1 in
12 twenty empty trucks=24 tons weight, at 4 to 6 miles per hour;
and the latter by itself, with 125 lbs. steam pressure in the boiler,
took 14 tons 12 cwts. over the same gradient, the weight of engine
in working trim being 10 tons. Calculating as before on one-fifth
weight of engine on gradient for adhesion, one-fifth less average
pressure in cylinder than that in boiler, and making extra allow-
ance for friction of load, owing to number and inferior construction
of trucks and railway, the load to be taken would be about 20 tons.
Engines coupled together are often used when the train of car-
riages is heavy. It does not appear that any loss accrues from
using the engines together, but rather the reverse; probably any
disadvantage from want of simultaneous action of wheel trod on
the rails is counterbalanced by the points of adhesion gained.
There can therefore be little doubt of the comparative advantage of
small engines coupled together when required on such railways as
have been under consideration, as arrangements can always be made
724
MODERN STEAM PRACTICE.
to utilize them, when not in use for through haulage, for shunting,
and other purposes.
In these engines the frame plates are connected together by one
or more water tanks, of which they form the sides, the whole being
framed on angle iron, with all joints rivetted and caulked in the
same manner as the boiler. By this arrangement, the tanks being
an integral part of the framing, great rigidity is secured to the
latter, while the weight of water, &c., is carried at the lowest pos-
sible level, insuring steadiness to the engine in running. The work-
ing gear, being entirely outside of the frames, can be examined or
repaired with facility, and without the necessity of using a pit to
get access to any part. The principle is applicable to locomo-
tives variously constructed as regards number and position of
wheels, &c.
DIMENSIONS OF SMALL TANK NARROW-GAUGE ENGINES.

Diameter of
Cylinder.
Stroke.
Diameter of
Wheels.
8 inches.
15 inches.
27 inches.
Centres of
Wheels.
4½ feet.
Steam Pressure
in Boiler.
Weight in tons.
9
IO
""
15
""
27
""
42
""
15
27
9
""
15
""
27
""
IO
""
15
12
18
""
27
30
555 in
""
""
120 lbs.
150 ",
125 ",
130,
7 tons 5 cwts.
10
""
""
II II/2,,
""
IO
IO
""
5
6 in.
In Figs. 545 and 546 we give examples and details of a four-
wheeled and a six-wheeled tank engine, both having the tank placed
underneath the boiler. The dimensions of the first engine are as
follows:-Diameter of cylinders, II inches; length of piston stroke,
18 inches; diameter of driving wheels, 3 feet; distance between
centres of wheels, 6 feet; diameter of body of boiler, 3 feet; length
of body, 8 feet 3 inches; 81 brass tubes, 2 inches diameter
outside; heating surface in fire box, 38 square feet; tube surface,
352 square feet. The dimensions of the second engine are:-
Diameter of cylinders, 15 inches; length of piston stroke, 21 inches;
diameter of wheels, 3 feet 6 inches; 5 feet 9 inches, centres; II feet
6 inches, wheel base; diameter of body of boiler, 3 feet 9 inches;
length of body, 9 feet; 100 brass tubes, 24 inches diameter outside;
heating surface in fire box, 67 square feet; tube surface, 545 square
feet; contents of tanks, 800 gallons; for 4 feet 8½ inches gauge of
rails; weight of engine in working trim, 28 tons.
LOCOMOTIVE ENGINES.
725

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24
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A, Boiler.
casing.
Fig. 545.—Tank Engine with Four Wheels coupled.
B, Smoke box. c, Chimney. D, Blow-off tap. E, Steam dome. F, Safety valve. G, Steam whistle. н, Cylinder. I, Valve
K, Regulator handle. L, Eccentrics and link motion. M, Weigh shaft. N, Starting handle. o, Crosshead. P, Piston rod.
QQ, Guide bars. R, Connecting rod. s, Crank pin. T1 T2, Driving and leading wheels. u, Side rod. v, Spring.
u, Side rod. v, Spring. w, Framing and tank.
x, Check valve. Y, Brake gear. z, Platform. z¹ z² z³ z4, Buffers and end beams, safety chains, rail guards, awning. z5, Coal box.
726
MODERN STEAM PRACTICE.

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Fig. 546.—Tank Engine with Six Wheels coupled.
Blow-off tap. E, Steam dome.
tap. E, Steam dome. F, Safety valve. G, Steam whistle.
M, Weigh shaft. N, Crosshead. o, Piston rod. P, Guide bars.
Leading, driving, and trailing wheels. U; Side rod.
v v, Springs.
z', Rail guards. z², Coal box.
A, Boiler. B, Smoke box.
Smoke box. c, Chimney.
c, Chimney. D,
K, Regulator handle. L, Eccentrics and link motion.
R, Connecting rod.
motion.
s, Crank pin. T1 T2 T3,
x, Check valve. z, Platform, end beams, and buffers.
H, Cylinder. 1, Valve casing.
Q, Steadiment for valve
w, Framing and tank.
LOCOMOTIVE ENGINES.
727
EXPRESS ENGINE FOR THE PENNYSYLVANIA RAILROAD.
The following description of an express locomotive for the Penn-
sylvania Railroad is given by the Engineer, Feb. 10, 1882, as an
excellent example of American practice. The boiler is of the wagon-
top form, and is of steel; the grate is large, for burning anthracite
coal, and therefore water tubes are used instead of fire bars.
Boiler:-
Diameter,
Dimensions.
...
4 ft. 2 in.
Width of grate, 3 ft. 534 in.
Length of grate, 10 ft.;
Mean height of fire-box crown above grate,
Thickness of boiler plates,
internal fire box,
...
3 ft. 1½ in.
3% in.
Grate surface,
...
Total heating surface,
Engine:-
Diameter of driving wheels,
""
bogie
""
Wheel base of coupled wheels,
Total wheel base,
Diameter of axle boxes, 8 in.;
Diameter of cylinders,
Stroke,
...
Centre to centre of cylinder,
Lap of valves,
Width of ports, 1 ft. 4¾4 in.;
Length of exhaust ports
tube plates,
No. of wrought-iron tubes, 201;
Length of tubes,
4 in.
½ in.
Inside diameter of tubes,
15% in.
...
...
10 ft. 1034 in.
35 sq. ft.
...
...
...
...
1205 sq. ft.
6 ft.
6 in.
2 ft.
9 in.
...
7 ft.
9 in.
22 ft. 7½ in.
Length of axle boxes,
10½ in.
...
...
...
I ft.
6 in.
2 ft.
...
6 ft.
5 in.
...
...
...
14 in.
Length of ports,
1½ in.
...
...
34 in.
...
15 tons.
•
Weight full:
On drivers,
On trailers,
On bogie,
...
:
...
...
...
In all,
...
14 tons 3 cwt.
12 tons 4 cwt.
41 tons 7 cwt.
The tractive force is 100 lbs. per lb. of cylinder pressure.
HAULAGE POWER OF LOCOMOTIVES.
The following tabulated statement of the relative haulage power
of locomotives is given by the Railroad Gazette. It is the result of
experiments by an American railway commission, and includes three
types of engine, viz. A. American locomotive with four driving wheels
and 12,000 lbs. on each wheel, total weight of engine 36 tons. B. Ten-
wheeled locomotive with six driving wheels and 12,000 lbs. on each
wheel, total weight of engine about 42 tons. C. Eight driving wheels
and 12,000 lbs. on each wheel, total weight of engine about 54 tons.
728
MODERN STEAM PRACTICE.
WEIGHTS OF TRAIN WHICH LOCOMOTIVES CAN HAUL AT A SPEED OF 20 MILES AN
HOUR UNDER ORDINARY CONDITIONS, IN TONS OF 2000 LBS. (NOT INCLUDING
THE WEIGHT OF ENGINE AND TENDER).
TYPE OF LOCOMOTIVE.
On straight track—
A
B
C
Level,.....
1096
1664
2226
Grade, 20 ft. per mile,.
547
8402
1128
40
350
545
734
60
""
249
3902
522
80
188
>>
302
410
ΙΟΟ
""
པ༷
""
148
242
330
On 5 deg. curves—
Level,...
921
1401½
1876
Grade, 20 ft. per mile,..
464
716
962
40
310
485
654
60
43
227
3602
488
80
173
2792
380
ΙΟΟ
""
""
137
225/2
308
On 10 deg. curves-
Level,.....
662
1013
1358
Grade, 20 ft. per mile,.
401
6212
836
40
278
477
590
60
""
207
3302
448
80
160
""
260
354
100
128
""
212
290
SPECIFICATION FOR LOCOMOTIVE ENGINE
AND TENDER.
As a good example of what such a document should be, we give
the subjoined Specification for a bogie passenger engine and tender
designed by Mr. W. Kirtley, locomotive superintendent of the
London, Chatham, and Dover Railway. This class of engine
differs in some respects from those previously in use on the line,
and has frequently to work heavy trains at express speed.
The engines described in the following specification are known as class
M. The following are their leading dimensions:-Diameter of cylinders,
I foot 5½ inches: stroke of cylinders, 2 feet 2 inches; diameter of bogie
wheels, 3 feet 6 inches; diameter of coupled wheels, 6 feet 6 inches; total
wheel base of engine, 20 feet 11½ inches; total wheel base of tender,
12 feet; heating surface of tubes, 945'6 square feet; firebox, 107 square feet;
total heating surface, 1052 square feet; grate surface, 16'5 square feet;
capacity of tank, 2550 gallons.
Quality of Materials.-Where "brass" is specified it must be good tough
metal. Gun metal must be composed of five parts of copper to one part
of tin. White Metal.-This must be composed of-Tin, sixteen parts;
LOCOMOTIVE ENGINES.
729
antimony, two parts; copper, one part and a half.
Other materials to be
obtained of the manufacture to be hereinafter specified, unless the consent
of the Company's locomotive superintendent in writing be first obtained to
an alteration.
Boiler.—Barrel, dome, fire-box casing, and smoke-box tube plate, and all
angle irons, rivets, and stays to be made of Lowmoor, Bowling, Taylor's,
or Cooper's (best Yorkshire) iron. Barrel to be telescopic, and made in
two plates, the circumferential seams to be single rivetted, and the longi-
tudinal seams to be butt-jointed, with inside and outside strips, double
rivetted. Tube plate to be attached to barrel by a ring of angle iron,
bored, faced, turned on edges, and shrunk on, and zigzag rivetted to both.
The dome to be in one plate welded at the seam, and flanged at the bottom
to fit barrel, to which it is to be double rivetted; a strengthening liner plate
to be placed inside the barrel round the opening for the dome. The top
to have an angle-iron ring rivetted to it, and to be fitted with a strong
wrought-iron cover. The cover and angle iron must be accurately faced
so as to make a perfectly steam-tight joint. Fire-box shell to be made as
shown, the sides and top in one plate, the front or throat plate flanged for-
ward and single rivetted to the barrel, and the back plate to the sides and
top as shown. Angle irons for carrying the sling stays to be rivetted to the
top in the position shown. The manhole to be of wrought iron, flanged
top and bottom, and single rivetted to the casing, the top flange to be
accurately faced to receive the safety valves. The boiler to be stayed by
six longitudinal stays screwed into the back plate of the casing, and passing
through the smoke-box tube plate, with nut and washer on either side, the
back plate to be strengthened where the stays pass through by a liner plate
rivetted to it on the inside. The longitudinal stays to be supported in the
middle of their length in the manner shown. The fire-hole to be circular,
the ring of the section shown to be Yorkshire iron, rivetted to the casing
and fire-box plates, flush outside casing. The foundation ring to be York-
shire iron, the corners of the form shown, carefully rivetted, so as to
be thoroughly tight. Twenty-one brass taper mud plugs for washing out
to be placed in the positions shown on the drawings.¹
Length of barrel
Diameter
Thickness of barrel
Dimensions.
outside at fire-box end
tube plate
...
""
ft. in.
.. IO 2
4 3
0 0178
0 0%
¹ These specifications are only supplied to selected firms of engine builders, who are
invited to tender (upon the specification), and the drawings can be seen at the chief office
of the Locomotive Engineer of the Railway Company. After a tender has been accepted,
a complete set of detail drawings are supplied by the Company, and these have to be
carefully worked to.
730
MODERN STEAM PRACTICE.
Thickness of dome plate
Length of fire-box shell
Breadth
Depth
Thickness
""
...
at bottom, outside
...
...
from centre line of boiler
plates
...
...
...
...
: :
:
...
3 in. x 234 in.
2 in. x 23% in.
Section of foundation ring
fire-hole ring
Diameter of rivets in boiler
""
foundation ring
Height of centre line of boiler from rail
...
...
...
:::
:
ft. in
0 01%
5 9
3 II
5 2
0 0%
|
0 018
0 08
7 2
Fire Box.-The fire-box plates to be of copper of the very best quality,
obtained from Messrs. Everitt & Sons, Grenfell & Sons, Vivian & Sons,
or other approved makers. The stays and rivets to be made from the very
best soft rolled copper bars, by the same maker as the plates. The plates
to be annealed both before and after flanging, and strips cut off must be
tested by being doubled cold, without showing any sign of fracture, and also
to be analyzed, and must not contain more than 5 per cent. of impurities.
The sides and crown to be in one plate, the crown curved as shown, and
stayed with eight Yorkshire iron roof bars of the section shown, each secured.
by thirteen studs 1 inch diameter, screwed through the crown plate into the
bar, with nut on the underside of the plate. Six of the roof bars to be con-
nected to the angle irons on the casing plate by twelve sling stays of York-
shire iron. Great care must be taken to bed the ends of the roof bars accur-
ately on the fire-box plates, and that the sling stays are of the correct length,
bearing on the pins top and bottom. The tube plate to be stayed to the barrel
by six 1-inch copper stays, screwed through the plate into palm stays rivetted
to the barrel. The copper stays to be screwed tightly into the fire box and
casing plates, and neatly rivetted over at the ends, the thread being turned
off the portion between the plates. A brass plug with fusible centre to be
inserted in the crown of the fire box. A brick arch to be built in the fire
box, supported on studs in the manner shown. Fire-box back plate to be
dished at fire hole to meet the ring, and the fire hole fitted with air deflector
scoop, and sliding doors, in the manner shown on the drawings. Fire grate
to consist of nineteen wrought-iron fire bars and two cast-iron fire bars of
the sections shown, supported on two cast-iron comb bar bearers by four
wrought-iron brackets, studded to foundation ring. Fire box to be rivetted
with best Yorkshire iron rivets.
Length at top, outside
Length at bottom,,,
Breadth
""
Depth, inside
...
...
...
Dimensions.
Water space at bottom, all round
Thickness of plates
...
:
::
ft. in.
...
...
5 0½
2
:
...
: : :
...
...
...
...
...
:
536
3 4
O
3
0 02
LOCOMOTIVE ENGINES.
731
Thickness of tube plate
Diameter of fire hole
rivets
copper stays
::
...
::
:
:
ft.
in.
0001300
and
0 0½
I 42
0 0180
0 0%
and
I
Workmanship.-All the plates are to be planed or turned on the edges
before being put together. The holes must be drilled or punched slightly
countersunk, and rhymed out perfectly fair with each other in all plates and
angle irons; drifting will under no circumstances be allowed. Care must be
taken that the smaller diameters of the holes come together, that all burrs are
carefully filed off, and that the plates are brought well together before any
rivet is put in. All rivets must completely fill the holes, and the heads must
be perfectly true and central. Any caulking that may be required must be
done with a broad-faced tool, so that the plates may sustain no injury. Before
being lagged the boiler is to be tested in the presence of the Company's
locomotive engineer, or his inspector, to a pressure of 200 lbs. per square
inch with water, and afterwards to 160 lbs. per square inch with steam, and
it must be perfectly tight under these pressures.
Tubes. To be of copper, solid drawn, of either Everitt's, Broughton
Copper Company's, or other approved make, 9 B. W. G. at the fire-box end
tapering to 12 B. W. G. at the smoke-box end. To be secured by a roller
tube expander—great care being taken that the tubes are not cracked—and
fixed with ferrules at the fire-box end. Ferrules to be of ferrule steel, and
The tubes are to project through
to go into the tubes a tight driving fit.
the smoke-box tube plate inch.
7
Dimensions.
No., 199
...
Length between tube plates
Diameter, outside
...
...
...
ft.
in.
IO
6
...
...
0
134
o 1%
...
No. 9, B. W. G....
No. 12, B. W. G....
0 2½
at smoke-box end for a length of 6 in....
...
Thickness at fire-box end
smoke box end
Distance apart of centres, about
...
Smoke Box and Spark Arrester.—Plates for smoke box and door to be of
BB Staffordshire iron, having a perfectly smooth surface. The rivets are to
be countersunk outside and filed smooth. Wrought-iron liners are to be
placed against the tube plate, and the sides and front of the smoke box. The
door to be dished as shown on drawings, and fitted with baffle plates and
suitable dart, handles, and hinges, the latter to be finished bright.
A wrought-iron grate for arresting sparks to be supported in the smoke box
}
732
MODERN STEAM PRACTICE.
in a horizontal position just below top of blast pipe. Care must be taken
that this grate fits accurately round the steam and blast pipes.
Dimensions.
Length of smoke box, inside.
Width on centre line of boiler, inside
Thickness of plates
Section of angle iron
...
...
...
...
ring round door hole
Diameter of rivets
Pitch of rivets, about
...
...
...
...
2½ in. by 2½ in. by ½ in....
ft. in.
2 88
...
4 II
0 038
3 in. by 34 in...
0 0%
0 3
...
...
Chimney.To be of BB Staffordshire iron; joint to be made with a butt
strip, and the rivets to be countersunk, and filed smooth on the outside.
The bottom, of best Yorkshire iron, to be quite free from hammer marks,
and to be carefully fitted to smoke box.
to drawing.
The top, of cast iron, to be made
Dimensions.
Height of top of chimney from rail
Diameter inside at top...
Thickness of plates
bottom
...
...
...
...
...
...
:
...
ft. in.
13 3%
I 6
I
5
0 04
Ash Pan.—To be made to hold water; to be fitted with a damper, front
and back, each to be worked separately from the footplate; the damper rods
to be on the right-hand side of footplate.
Thickness of plates of ash-pan
Depth of ash-pan
Width
...
...
Dimensions.
...
...
...
:
ft. in.
0 of
I 2
3 4
“Ramsbottom's duplex”
The columns to be of
Safety Valves.—To be of the kind known as
safety valves, to be fixed on the fire-box casing.
brass turned bright, fixed on a cast-iron manhole cover. The springs (of
approved manufacture) and gear to be made accurately to drawing, and set
so as to blow off at 140 lbs. per square inch. The seating to be of wrought
iron, carefully fitted to the fire-box casing. All the joints must be accur-
ately faced, so as to be perfectly steam-tight.
Dimensions.
Diameter of valves
Distance apart of columns
Height of brass columns
Diameter of spring steel
""
manhole cover
Thickness of seat
...
:
...
...
:
:
...
:
ft. in.
0 3½
5
O 10%
I 034
0 018
1 6
0 1%
Regulator and Steam Pipes.—Regulator to be of cast iron, the head to be
fitted with double valves. The steam pipes to be of copper sheets hard
LOCOMOTIVE ENGINES.
733
soldered together on the inside. Flanges and cone to be brass.
Steam
pipe in boiler to be fixed to tube plate by a turned ferrule of best steel and
to regulator by means of three claw bolts.
of cast iron.
Elbow pipe in smoke box to be
Dimensions.
Diameter of steam pipes, inside
Thickness
...
>>
...
...
ft. in.
...
0 42
No. 7, B. W. G……..
Blast Pipe.-The blast pipe to be of cast iron, the top to be bored and
turned to the form shown.
Dimensions.
Diameter of blast orifice
...
Height of blast pipe above top row of tubes
ft. in.
...
0 434
0 2
...
Frames, Inside.—Inside frames and front buffer plate to be Bessemer
steel of Cammell & Co.'s, John Brown & Co.'s, Bolton Iron and Steel Co.'s
manufacture, or other approved makers, solid rolled, and each plate must
have the brand of the manufacturer legibly stamped on its outer side. The
plates are to be planed all over on the inner side, and the outer side must
be finished with a good smooth surface. All holes to be marked from one
template, and drilled and rhymed out to the exact size given. The frames
to be set in and thoroughly well stayed together by the buffer plate, and
with plates and angle irons at the leading end in the manner shown on
drawings, the front footplate to be thinned at the edges as shown. A plate
is to be placed horizontally under the cylinders to carry the bogie pin, and
must be firmly bolted to angle irons on the frames. A transverse stay ar-
ranged to carry the back ends of the motion bars and the intermediate spindle
guides, and a vertical stay in front of the fire-box casing, must be placed
in the positions shown. Over the trailing axle a horizontal flanged stay is
to be securely bolted to the frames, and at the hind end of the frames a cast
iron footplate arranged for the tender couplings, is to be placed. All these
stay plates and angle irons to be of BB Staffordshire iron. The casting and
the transverse stays must be securely fastened to the frames by turned bolts.
The rubbing pieces for tender buffers to be well case-hardened. When
finished the frames must be perfectly true and square in all directions.
The footplate to be of steel, of the same make as the frames, and the rivets
to be countersunk on the top. Guard bars of the form shown are to be
securely bolted to the frames and buffer plates.
Dimensions.
Thickness of frames, finished
Depth over leading bogie wheels
""
between cylinders and driving horns
between driving and trailing wheels, open
Greatest depth of plates
:
::
...
...
ft. in.
O I
...
I 3
1 5½
I 9%
2 1134
734
MODERN STEAM PRACTICE.
Distance from centre of bogie to front end of frame
*
""
""
to centre of driving axle
driving axle to centre of trailing axle
trailing axle to hind end of frame
Extreme length of plates
...
...
ft. in.
5 o
9 9
...
8
4
4
O
27 I
Distance from centre of driving axle to front of fire-box casing
Distance between frames at leading end
...
...
from cylinders to trailing end
Height of top of frame from rail
Depth of buffer plate
...
...
...
...
I 10%
39
4 O
4 1½
I
7 6
0 13%
0 016
Length
""
Thickness
""
Thickness of footplate
Extreme width of footplate
Outside.
...
...
: : :
...
7 10
To be of Yorkshire angle iron-the step plates to be
welded on-and to be stayed to the inside frames as shown on the drawings.
All the rivets to be countersunk outside.
4
inches by 2½ inches by ½ inch.
Section of angle iron for frames
Buffers and Draw Gear.-Buffers to have wrought iron cases and
plungers, with “Timmis" unequal section steel springs, and to be in all
respects similar to drawings supplied. Draw bar to be of best chain-cable
iron, and to be fitted with a screw coupling, and to have an india-rubber
spring (No. 6a), to drawing, of George Spencer & Co.'s make.
Dimensions.
Height of centre line of buffers from rail ...
Distance of centres of buffers apart
Diameter of draw bar
...
...
...
...
:
ft. in.
3 5
5 8
0 2
Cylinders. To be made of the best close-grained, hard, and strong cold-
blast cast iron, twice cast, as hard as can be worked, and perfectly free
from honeycomb or other defects. They must be bored out perfectly true,
the ends being bell-mouthed. The cylinders are to be made with loose
covers at each end, the back cover having provision for carrying the front
ends of the slide bars. All joints and faces to be machined and scraped to
a true surface, so that a perfect joint can be obtained. When the cylinders
are bolted together, they must be tested by hydraulic pressure to 250 lbs.
per square inch. The cylinders to be horizontal, and to be attached to
the frames by flanges-the holes in which and in the frames are to be rose-
bitted—and secured by turned bolts a driving fit. The front flanges and
covers are to project through the frames as shown on drawings. To be
provided with waste-water cocks and gear worked from the left-hand side
of footplate. The top of cylinders to be covered with thin fire-brick or
cement; the bottom flanges to be planed perfectly true, so that the bogie
pin-plate may bear truly against them.
LOCOMOTIVE ENGINES.
735
Dimensions.
Diameter
Stroke
...
Distance of centres
""
...
valve spindle centres
Thickness of metal
Length of ports
...
Width of steam ports
exhaust ports
Thickness of bridges
Length of working face
...
:
:
:
:
...
...
...
...
...
...
...
:
...
:
:
Distance from centre of driving axle to centre of exhaust port ...
1
32
ft. in.
I 52½
2
2
2 4
0 3½
0 0%
I 2
0 12
0 3/2
O I
Ο ΙΙ
9 9
Pistons.—To.be of tough cast iron, made from cylinder metal, and to be
sound and free from all defects. To be accurately fitted to cones on ends
of piston rods, and fixed with nuts as shown on drawings. Piston heads to
be turned inch smaller than bore of cylinder. Packing rings to be of
cast iron, turned only on the outside and on edges, and made ½ inch
larger in diameter than the cylinder bore, and then cut and sprung into their
places. When finished the whole must be an easy but accurate fit in the
cylinder, so that the piston and rod can be moved backwards and forwards
by hand.
Width of piston
Dimensions.
rings, two in each piston
Thickness of rings
""
...
...
:
ft. in.
0 34
0 0½
0 0%
Piston Rod and Crosshead.-To be of the best mild cast steel, manufac
tured by Taylor Brothers, Vickers, Sons, & Co., Cammell & Co., or other
approved makers, with cone and nut for fixing to piston; the crosshead to
be solid with the rod.
Diameter of rod
...
...
Dimensions.
...
Length between cone and shoulder of crosshead
Taper of cone in piston
...
No. of threads per inch piston end
...
...
...
:
...
...
I in 3
6
...
ft. in.
0 234
3 0%
Gudgeon Pins.-To be of best Yorkshire iron, keyed in the crossheads
and well case-hardened.
Slide Bars and Slide Blocks.-Slide bars to be of cast steel from the
same makers as piston rods, and to be provided with brass oil siphons to
drawings. The slide blocks to be of cylinder metal, sound and free from
all defects.
Width of slide bars
Thickness
Length
...
of slide block
""
...
...
Dimensions.
Distance between slide bars vertically
...
...
...
:
...
:
ft. in.
0 3
0 24
3 9
I O
0 338
horizontally
0 68
736
MODERN STEAM PRACTICE.
Connecting Rods.-To be of best Yorkshire iron, forged solid in one
length. The brasses to be of gun metal, those for the big ends to be
lined with white metal. The cotters to be of steel, and the bolts of the
best Lowmoor iron forged from the solid, the heads must on no account
be welded on.
Dimensions.
ft. in.
6
I
Distance of centres
...
Diameter of big-end bearings
small-end bearings
0 734
0 3
Slide Valves and Valve Spindles.—The valves to be of phosphor bronze.
The spindle frames and intermediate spindles to be of best Yorkshire iron,
of the form shown on drawings, the latter to be well case-hardened.
The intermediate spindle guides to be of cast iron, bushed from either
end with gun-metal bushes, and to have oil boxes cast on as shown.
Lap of valve
Lead, in full
gear
Dimensions.
Centre line of valve above centre line of cylinder
Diameter of valve spindle
*
intermediate spindle
...
ft. in.
O
I
3
Ο Ι
0
I
1%
0 3/1/2
""
Length of
,,
""
guides
I O
Valve Motion.-The valve motion to be made from the best scrap iron,
and the working and rubbing surfaces to be thoroughly case-hardened, and
provided with oil siphons and grooves, and finished in the best manner.
Expansion link to be supported at the top from the forward eccentric rod
pin, the reversing shaft being below the motion and behind the link. The
motion pins to be of best iron, thoroughly case-hardened and accurately
fitted. Eccentric sheaves to be in two pieces, the smaller piece being of
best scrap iron, and the larger piece of cylinder metal. Eccentric straps to
be of wrought iron, solid with the rod, and to be fitted with white-metal
liners.
Dimensions.
Length of expansion link between centres
eccentric rods
lifting links
...
Diameter of motion pins
Throw
14.
eccentric sheaves
""
""
...
:
:
:
:
ft. in.
I 4½
...
4 7
I 10%
O 134
I 44
0 3.4
:
Reversing Gear.-Reversing to be performed by means of a screw
arrangement, firmly supported on the right-hand side of footplate.
Coupling Rods.-To be of Bessemer steel of approved make, with solid
ends and siphons, and to be fitted with phosphor-bronze bushes.
rod to be forged solid in one length, and finished bright.
Each
LOCOMOTIVE ENGINES.
737
Dimensions.
Distance of centres
...
Section of rod
...
...
...
4½ in. by 1% in.
ft. in.
8 4
Coupling Rod Pins.-To be of wrought iron case-hardened, accurately
turned to gauge, and to be exact duplicates; to be turned to a taper of 1 in
50 and forced into the wheels by hydraulic pressure, the inner end to be
afterwards rivetted over; the outside end of pin to be fitted with a screwed
washer and taper pin, as shown on drawings.
Diameter of pin
Length of bearing
...
Dimensions.
...
ft. in.
0 4
0 4
Bogie. To have four wheels, and to be in all respects of the form and
dimensions shown on drawings. The frames to be of steel by the same
makers as the engine frames (the brand to be on the outer side), raised as
shown over the axles, the inner sides to be planed all over, and the outer
sides where any attachment is made. The carrying girders to be of best
Yorkshire angle iron bent round and securely rivetted to the frames, and
machined on the outer sides, clearances being made where shown; steel
bearing plates planed and scraped to a good working surface are to be
rivetted to the angle irons. The ends of the frames are to be stayed by
flanged plates of BB Staffordshire iron placed vertically, and bolted to the
frames by the horn block bolts. When finished the frames must be perfectly
true and square. The sliding block is to bear on the steel plates and work
between the angle irons before mentioned, the side play being controlled
by "Timmis" unequal section steel springs, arranged as shown on drawings.
The bogie pin of wrought iron to have a projection on it fitting into a corres-
ponding hole in the horizontal plate under the cylinders before mentioned,
to which it is to be securely rivetted, and to have the end screwed with a
washer nut secured by a taper pin through it. The sliding block to be of
tough cylinder metal perfectly free from honeycomb or other defect; to be
machined on all working and bearing parts, and to be scraped to a good
working surface on the sliding portions, and to have lubricators fixed and oil
grooves cut where shown. The spring cradles are to be made of best
Yorkshire iron, with wrought-iron saddle pieces at each end, shaped to bear
on the axle-boxes, and fitted with oil siphons as shown. The spring shaft
to be of best Yorkshire iron passing through cast-iron bushes in the frames,
with washer nuts and taper pins outside the spring buckles.
Bogie wheel base
...
Thickness of frames, finished
Depth at centre
""
horns
...
Dimensions.
...
...
::
: :
: :
...
ft.
in.
5 9
0 0%
O IO
I 74
47
738
MODERN STEAM PRACTICE.
Length of frames
...
Distance between frames
...
...
:
Section of angle iron for carrying girders, 7 in. by 5½ in. by I in.
steel bearing plates
""
Length
""
Thickness of end stays
Depth
""
Total side play of bogie
Diameter of bogie pin
""
...
10
Section of iron for spring cradles
Diameter of spring shaft
""
Length
:
:
check springs unloaded
19
""
ft. in.
7 612
2 734
6 in. by 3 in. by ½ in.
2
...
...
:
...
:
:
54
0 02
0 8
O
1/2
0 6½
...
5 in. by I in.
0 22
0 319080
...
O TO
Springs and Connections.-The springs to be of the very best spring steel,
manufactured by Messrs. Turton & Sons, or other approved makers. Before
being put in position each spring is to be fully tested until the camber is
taken out, and the spring must afterwards resume its original form. The
bogie springs are to be inverted, the buckles being connected direct to the
shaft before mentioned, through the bogie frames; the ends of springs
are to be connected to the spring cradles by hooks. The driving springs
are to be under-hung, and the buckles are to be connected to the axle-boxes
by T-links. The ends of the driving springs are to be connected to wrought-
iron liners on the frames by adjustable links; the trailing springs to be
"Timmis" unequal section steel springs, two under each axle box, arranged
in the manner shown on the drawings. All the brackets, links, hooks,
buckles, and pins connected with the springs must be of best Yorkshire
iron, and the working surfaces must be thoroughly case-hardened.
Dimensions.
BOGIE.
Length loaded
Camber
Breadth of plates
No. of
Thickness of
:
•
...
...
...
...
...
""
...
DRIVING.
:
:
:
:
...
...
ft. in.
4 O
0 3
3 50
14
O
0 0½
Length loaded
Camber
""
Breadth of plates
No. of
Thickness of,,
...
:
...
...
...
...
...
...
...
...
...
13
3 4
0 3
0 42
0 0½
Axle Boxes.-The axle boxes to be of the very best gun metal, lined with
white metal, and fitted with cast-iron keeps and spring lubricating pads,
and suitable covers. Every axle box must be made accurately to dimensions,
so as to be interchangeable in any of the engines.
Horn Blocks and Horn Stays.—The horn blocks to be of crucible cast
LOCOMOTIVE ENGINES.
739
steel of Vickers', Cammell's, Taylor's, or other approved make; the bogie
horn blocks to be fitted with cast-iron distance blocks and securing bolts as
shown. The driving and trailing horn blocks to be solid, and provided
with adjustable wedges and securing bolts. The horn blocks must be
accurately bedded to the frames, and secured by turned bolts a driving fit.
The horn stays to be of wrought iron; care must be taken that they fit the
horn blocks accurately.
Axles.-To be of crucible cast steel of Vickers, Sons, & Co.'s extra make;
the webs of crank axle to be hooped; all corresponding parts to be of an
exact size and made to template, so that they may be interchangeable, and
each axle must be clearly stamped with the maker's name, and the brand
extra. The journals are on no account to be swaged down, but in all cases
turned from the solid. The wheel seats must be accurately turned to a taper
of 1 in 100.
I
Dimensions.
BOGIE AXLES.
Diameter in middle ...
...
...
on wheel seats
""
""
of journals
Length
""
...
:
Distance apart of centres of journals
Diameter in middle...
:
CRANK AXLE.
on wheel seats
""
of journals
:
:
...
:
...
...
:
ft. in.
0 534
0 7½
0 6
O 9
3 7
...
O 7
:
:
:
:-
Length
Diameter of crank-pin journals
Distance apart of centres of cranks
Do., journals
...
Cross sections of crank arms
Throw of cranks
{
...
...
...
...
...
12 in. by 44 in.
and 12 in. by 4½ in.
TRAILING AXLE.
...
}
Diameter in middle...
...
...
""
on wheel seats
of journals
...
Length
...
:
...
...
:
0 9
0 72
0 7½
0 734
2
4
4 0
...
:
:
0 13
0 7
09
0 7/2
...
0 72
Distance apart of centres of journals
...
4 0
Wheels.—To be of wrought iron, of the best materials and workmanship,
with solid rims, spokes, bosses, and balance weights. The spokes must be
forged with solid T ends, and welded in the centre. The surfaces of rims
and spokes to be shaped so that the wheels are exactly balanced. Each
wheel is to be bored taper and put on the axle, before the tyres are shrunk
on, by hydraulic pressure of not less than 60 tons, and then properly keyed
Great care must be taken that the keys fit accurately.
on.
740
MODERN STEAM PRACTICE.
Diameter on rim
Width of rim
Dimensions.
BOGIE.
ft. in.
3 0
O 4
Thickness of rim
No. of spokes
Section of spokes at boss
""
Diameter of boss
Width of boss
rim
...
Diameter of hole in boss
Diameter on rim
Width of rim
Thickness of rim
No. of spokes
...
...
...
...
...
...
:
:
:
...
...
4 in. by 15% in.
3½ in. by 14 in.
...
IO
0 1%
I 4
0 7
0 7/2
:
:
DRIVING AND TRAILING.
Section of spokes at boss
""
""
Diameter of boss
Width of boss
...
:
...
...
...
rim
...
Diameter of hole in boss
...
...
:
Centre of wheel to centre of coupling pin
Trailing to driving
Driving to centre of bogie
Bogie wheel base
Total wheel base of engine
...
:
:
...
60
...
...
...
...
44 in. by 134 in.
3½ in. by 13% in.
20
0 44
о 13/4
I 7
0 72
o 9
WHEEL CEntres.
...
...
...
:
...
...
...
...
...
...
...
I
O
8 4
9 9
5 9
20 11/2
Tyres. To be of crucible cast steel, of Vickers, Sons, & Co.'s extra
manufacture, and to be of the section shown on drawing; to be shrunk on,
and to be fixed to the wheel by lips on the outside, and by a wrought iron
lip ring on the inside, of the section shown. Each tyre must be clearly
stamped with the maker's name and the brand “Extra.'
Dimensions.
BOGIE.
""
Diameter on tread
Width
...
Thickness, finished
...
...
...
...
Distance between tyres
Diameter on tread
Width
...
Thickness, finished
...
...
...
...
...
DRIVING AND TRAILING.
...
***
...
...
...
Distance between tyres
3
16
...
...
:
:
:
ft. in.
3 6
0 538
0 3
4 5%
6 6
...
0 52
3
:
O
4 5%
Cab and Splashers.-The cab and splashers to be made of best Staf-
fordshire plate inch-full-thick, the former to be fitted with two plate-
glass windows in brass frames, to be made to open. All rivets to be
countersunk and filed smooth. A brass number plate, to pattern, is to be
placed on each side of the cab.
LOCOMOTIVE ENGINES.
741
Width of cab
Height at centre
Dimensions.
...
ft. in.
6 6
...
7 0
Sand Boxes.—To be of cast iron, four in number, and fitted with valves
and substantial gear for working from footplate. The leading boxes to be
fixed on to the splashers of the driving wheels, and the valves are to be
coupled together so as to work simultaneously.
Lagging.—The boiler and fire-box shell to be lagged with well-seasoned
pine, and covered with smooth iron sheets-14 B. W. G.-supported on a
light wrought-iron frame, and secured by belts in the usual manner.
Brake.—The engine to be fitted with the Westinghouse Automatic Brake,
consisting of air pump, steam cock, 3 inch triple valve, release cock, ½ inch
cock, driver's brake valve, air gauge, 10 inch by 24 inch reservoir and nipple,
hose coupling and union, the whole of which are to be obtained of the
Westinghouse Brake Co. The brake cylinder to be the L. C. D. R. stan-
dard pattern, 10 inches diameter. The brake shaft, hangers, brackets, rods,
pins, crossbars and adjusting screws to be of the best scrap iron, the pins
and working surfaces to be thoroughly case-hardened. Brake blocks to be of
cast-iron, one to each wheel, and the whole arranged as shown on drawings.
Dome and Man-hole Casings, &c.—To be of the form shown on drawings,
of charcoal iron 14 B. W. G. thick, thoroughly well finished. Brass moulding
pieces are to be arranged round the back of smoke-box and fire-box casing.
Hand Rail and Lamp Irons.—A neat hand rail to be provided round the
boiler, supported by polished wrought-iron standards. Lamp irons to be
fixed on the smoke-box, footplate, and fire-box casing, in the positions shown.
Injectors. Two injectors, Gresham & Craven's (brass), No. 8, to pattern,
to be fixed on the ashpan sides in the position shown.
Boiler Mountings, &c.-A brass seating to be fitted to the fire-box casing,
to carry two whistles and pressure-gauge cock. Two injector steam valves,
screwed into brass seatings, to be fixed on the fire-box casing in the positions
shown, with spindles through the weatherplate, and brass hand wheels
inside of the cab. Pressure gauge to be Bourdon's manufacture (Paris), with
solid drawn tube (to sample to be supplied), to indicate from 1 lb. to
200 lbs. per square inch. A blower to be fixed on right-hand side of
smoke box, and worked from the footplate. Two glass water gauges, with
asbestos packed cocks, two ball clack boxes, a Furness lubricator to each
cylinder, a displacement lubricator, oil boxes for axle boxes and glands,
lubricators for bogie sliding block, an ash-pan water cock, and a coal
watering cock to be fixed in the positions shown on the drawings, the whole
to be made of brass, in accordance with drawings, and of first-class finish.
Dimensions, &c., of Pipes.
Main steam pipes in boiler and smoke box
Injector suction and delivery pipes
Diameter
inside.
4½ in.
134 in.
Thickness
B. W. G.
7
ΙΟ
UorM
742
MODERN STEAM PRACTICE.
Injector steam pipes
Blower pipe in smoke box, copper solid drawn...
Diameter
inside.
Thickness
B. W. G.
1/4 in.
IO
...
% in.
12
3/8 in.
II
5 in.
16
5
15
1 in.
15
Furness lubricator pipes in smoke box, copper solid drawn
Oil pipes
...
...
Pressure-gauge pipe, copper solid drawn
Bolts and Nuts.-To be made to drawings and gauges, and all threads
to be Whitworth's standard, except where otherwise specified or shown on
drawings. Every nut of the same description, to be exactly the same size.
Gland nuts to be case-hardened. All nuts in the smoke box to be of hard
brass, and made with a cap. All union nuts to be made exactly to drawings.
No. of Threads per Inch.
Brass work of ½ in. diameter and upwards
...
Copper fire-box stays
...
:
Mud plugs
...
Piston rods, piston ends
...
...
...
...
...
:
:
I2
12
II
6
TENDER.
Tank.-Tank to hold about 2550 gallons, to be of the horse-shoe form
with a well, with angle irons, stays, man-hole, and coping as shown on draw-
ings, to be constructed entirely independent of the frames and footplate.
The whole of the plates, angle irons, and stays to be of BB Staffordshire
iron. All the joints to be made with butt strips, and the rivets to be
countersunk on the outside and filed smooth; care must be taken that the
holes are perfectly fair with each other in all plates and angle irons, and
that the rivets completely fill the holes. The man-hole to be fitted with
a lid and strainer. Two water-tight tool boxes of wrought iron, lined with
wood, are to be fixed on the tank. The mouths of feed pipes to be pro-
tected by copper rose boxes. The feed cocks of hard brass are to be pro-
vided with suitable sectors and handles worked from the footplate. The
tank is to be fixed to the framing in the manner shown on drawings.
Dimensions.
Length of tank, outside
...
Width
...
Height
""
Between arms of horse-shoe
Length of
""
well outside
:
...
...
:.
:
...
...
...
:
:
:
ft.
in.
18 2
7 I
3 6
3
6
...
Width ""
""
Depth
""
...
Height of coping above tank
Thickness of side, back, and coping plates
""
Section of angle iron for tank
:
...
:
II 6
3 6/2
I 6
Ο ΙΟ
0 04
inside of horse-shoe and top and bottom plates
0 01%
24 in. by 24 in. by 3% in.
""
stays
2½ in. by 2½ in. by ½ in.
Maou
LOCOMOTIVE ENGINES.
743
...
...
6 in. by 3% in.
ft. in.
0 02
Section of stays
Diameter of rivets
Pitch
""
...
Diameter of man-hole, inside
Height
above tank
""
""
...
0 134
I 6
0 9
Frames. Outside frames and buffer plates to be of steel, by the same
makers as the engine frames; finished with a good smooth surface, angle
irons of the section shown to be securely rivetted to the frames. Inside
frames, vertical and horizontal transverse stays of BB Staffordshire iron,
draw pin washers, and foot-steps, are to be placed as shown on drawings.
All holes are to be marked from one template, and drilled and rhymed out
to the exact size.
Thickness of outside frame...
Depth
""
""
open
Dimensions.
...
Distance from front end of frame to leading axle
""
""
Extreme length
leading axle to middle axle
middle axle to trailing axle
trailing axle to hind end of frame...
...
...
...
...
:
...
...
ft. in.
0 0%
:
:
:
:
2 II
4 0
6
60
3 4
19 4
Distance apart
...
...
...
Height of top of frame from rail
Thickness of inside frame
...
Depth
""
""
Length
""
""
...
:
:
:
5 82
4 1/2
0 0½
I ft. 6 in. and I I
...
...
...
17 6/2
38
Distance apart
Thickness of vertical and horizontal transverse stays
Section of angle iron for stays,
Length of buffer plates
Depth
Thickness
""
""
""
...
""
leading end
trailing end
2½ in. by 2½ in. by ½ in.
...
...
...
...
...
:
:
0 0½
7 6
I 4
0 034
O I
0 01/0
7 10
Thickness of footplate
Extreme width of footplate...
...
Buffers and Draw Gear.-Buffers on trailing end of tender to be in all
respects similar to those on the engine; buffer spindles at leading end to
be of wrought iron case-hardened, and to be guided in cast-iron sockets.
The draw bars, safety links, and coupling chains to be of best chain-cable
iron. Trailing draw bar to have an india-rubber spring, No. 6, of George
Spencer & Co.'s make, and to be fitted with a screw coupling.
Dimensions.
Distances of centres of buffer spindles apart
""
""
buffers apart
Height of centre line of buffers from rail
...
...
...
: :
ft. in.
3 3
5 8
3 5
Hand Rail, Pillars, Lamp Irons, &c.—A hand rail and pillar to be
placed on each side of the footplate as shown, and fixed to the tank and foot-
744
MODERN STEAM PRACTICE.
plate. Three lamp irons, one gong iron, pulleys for communication cord, and
a brass number plate, to be fixed on the tank in position shown on drawings.
Springs.-Bearing springs to be of the very best spring steel, by the same
makers as engine springs, and to be similarly tested. They are to be con-
nected by links to brackets rivetted to the frames by turned cold rivets of
Lowmoor iron. Brackets, links, buckles, and pins to be of best Yorkshire
iron, and the working surfaces must be well case-hardened. A laminated
buffing spring of similar quality to the bearing springs is to be arranged at
the leading end of the tender, as shown on drawings.
BEARING SPRINGS:
Dimensions.
Length, loaded
...
...
Camber
""
Breadth of plates
Thickness
...
...
No. of plates in leading and middle springs
trailing springs
...
BUFFING SPRING:
Length screwed up
Camber ""
1:
...
...
...
:
:
:
...
...
...
...
...
II
...
12
...
ft. in.
3 6
0 3/2
0 4
0 0½
:
| |
3 3
0
32
Breadth of plates
Thickness
""
...
...
I plate ½ in. and 17 plates ¾ in.
0 42
Axle Boxes.-Axle boxes to be of good tough cast iron, and to be care-
fully fitted with gun-metal bearings lined with white metal, wrought-iron
covers, and keeps of cast iron arranged for spring lubricating pads.
Horn Blocks.-Horn blocks to be of cylinder metal as hard as can be
worked, secured to the frames by turned bolts a driving fit: they are to have
cast-iron distance blocks and securing bolts, as shown on drawings.
Axles. To be of crucible cast steel of Vickers', Cammell's, Taylor's, or
other approved manufacture, all corresponding parts to be of the same size
and made to a template, so that they may be interchangeable, and each axle
must be clearly stamped with the brand and the maker's name. The journals
must on no account be swaged down, but turned from the solid metal.
Dimensions.
Diameter in middle ...
...
on wheel seat
...
""
of journal
...
...
ft. in.
0 6
***
0 634
...
...
0 54
0 9½
Length of journal
...
Distance apart of centre of journals
...
...
...
...
6 4
Wheels. To be of wrought iron, of the best materials and workmanship,
with solid rims, spokes, and bosses. The spokes to be made in a similar
manner to the engine-wheel spokes. The wheels to be put on the axles
before the tyres are shrunk on-by hydraulic pressure of not less than
60 tons, and then properly keyed.
LOCOMOTIVE ENGINES.
745
Dimensions.
Diameter on rim
Width of rim...
Thickness of rim
Number of spokes
:
:
...
Section of spokes at boss
""
Diameter of boss
Width of boss
rim
...
Diameter of hole in boss
...
:
...
:
...
II
4 in. by 15% in.
3½ in. by 14 in.
ft. in.
3 3
0 44
0. 1%
...
...
:
...
I 2
O 7
0 634
Tyres.-To be of crucible cast steel of Vickers', Cammell's, Taylor's,
Monkbridge, or Bowling Iron Company's manufacture, of same section as
driving and trailing tyres, and to be fixed to the wheels in a similar manner.
Diameter on tread
Width
...
...
Dimensions.
...
...
...
ft. in.
39
:-
:
0 52
...
...
...
0 3
Thickness (finished)…..
Distance between tyres
4 5%
Brake.—The tender to be fitted with the Westinghouse Automatic Brake,
consisting of 10-inch brake cylinder, 12 inch by 26 inch reservoir, 3-inch
triple valve, release valve, ½ inch cock, brake pipe cock, drip cup, release
spring and hose coupling, which are to be obtained of the Westinghouse
Brake Co. The brake to be arranged so as to be worked independently
by hand. The brake screw and handle to be placed on the left-hand side
of the tender. The brake shaft, hangers, brackets, pins, rods, levers and
adjusting screws to be of the best scrap iron. A cast-iron block to be
applied to each wheel, and the whole arranged as shown on the drawings.
Bolts and Nuts.—To be similar in all respects to those used on engine.
Painting. Each engine and tender is to be painted in the following
manner. The boiler, before being lagged, to receive one coat of boiled oil
and one coat of thick red lead; the inside of tender tank to have two coats
of thick red lead. The lagging plates, cab, splashers, outside frames, tank
plates, and wheels to have one coat of lead colour; then to be thoroughly
stopped and filled up and rubbed down, one coat of vegetable black, two
coats of drop black, then to be panelled in slate colour and lined to
pattern in vermilion, and afterwards to have four coats of best engine copal
varnish, to be properly rubbed down between each coat. The buffers and
buffer plates to be similarly prepared and painted vermilion, with the num-
ber of the engine in gold shaded black on the latter; inside of frames and
axles to be finished with one coat of vermilion and two coats of varnish.
The company's monogram L. C. D. R. to pattern to be painted on each side
of the tender tank in shaded gold letters. The frames, smoke box,
chimney, fire-box casing, ash pan, coal space, footplate, bottom of tank,
brake work, &c., to have three coats of japan black.
746
MODERN STEAM PRACTICE.
RULES FOR THE LOCOMOTIVE ENGINE.
Effective pressure of the steam in the cylinder.-The effective pres-
sure of the steam in the cylinder, cutting off at various grades, is as
follows, assuming 100 lbs. per square inch as the pressure in the
boiler:-
Steam cut off at 3/4 of the stroke of the piston,
""
""
2/3
3/2
""
1/3
1/4
""
""
Effective mean pressure.
90
80
69
50
40
Tractive power of locomotive engines.-The tractive power of
locomotive engines is found by squaring the cylinder diameter in
inches, multiplying by the mean pressure of the steam in lbs. per
square inch, and again by the length of the stroke in inches, and
dividing the result by the diameter of the wheel also in inches.
Hence the following formula:-
T
D². P. L.
W
Where T represents the tractive power; P, mean pressure in lbs. per
square inch; D, the diameter of the cylinder; L, the length of the
stroke in inches; and W, the diameter of the driving wheel in inches.
Resistance of trains due to gravity on any incline. The resistance
of trains due to gravity alone, on inclines, which may be I in 25,
I in 50, or I in 100, as the case may be, is found in lbs. per ton of
train by dividing the constant 2240 by the gradient, which gives the
resistance in lbs. per ton of train; hence with the preceding gradients
we have-
2240 =
25
89.6 lbs. per ton of train.
2240
= 44·8
50
2240
100
= 22'4
and so on according to the gradient or inclination of the rails.
Resistance of trains at different speeds.-To find the resistance of
trains at different speeds, on a level line of railway, in lbs. per ton
of load, square the velocity, and divide the result by the constant
171, adding 8 to the quotient. This will give the resistance in lbs.
per ton of load on a level. Hence the formula—
V2
R= +8= lbs. per ton of load.
171
LOCOMOTIVE ENGINES.
747
To find the load which an engine will take up a given incline.—To
find the load which an engine of a given tractive power will take
up an incline at a given velocity. Divide the tractive power of the
engine in lbs. by the force of the resistance due to gravity and speed
in lbs. per ton, and the quotient will be the load in tons, deducting
the weight of the engine and tender. Hence the formula—
L=
T
G+R¯
=
- W the load of the carriages in tons.
To show what must be considered in designing locomotive
engines for steep gradients, we will take an example from actual
practice. A line of tramways was worked by a contractor's loco-
motive of the ordinary description on various gradients, the heaviest
being I in II for about 800 yards. The cylinders of the engine
were II inches in diameter; the stroke of the piston, 18 inches; the
four wheels were coupled, 2 feet 6 inches in diameter, and placed
4 feet 6 inches apart from centre to centre. The weight of the
engine in working order was 10 tons, and it drew behind it a load
of 13 tons up the gradient of I in II. The pressure of the steam
was from 90 lbs. to 100 lbs. per square inch. On an incline of 1 in II
the resistance due to gravity would be 203.64 lbs. per ton, and taking
the engine friction at 18 lbs. per ton, and the waggon friction at 10 lbs.
per ton, we have the following total resistances to be overcome by
the engine in ascending the gradient:-
Resistance due to gravity, 23 tons at 203'63 lbs.,
Engine friction, 10 tons at 18 lbs. per ton,
Waggon friction, 13 tons at 10 lbs. per ton,
lbs.
4683'5
180
130
I
+
Total,....
4993'5
or, say 5000 lbs. The weight available for adhesion was 10 tons or
22,400 lbs., which would be diminished by one-eleventh on an incline
of I in II. The actual adhesive weight available in the incline
would therefore be—
22,400
-
22,400
II
=2036.3 lbs.;
and the adhesion must therefore have amounted to very nearly one-
fourth of the load on the wheels. An engine of the above dimen-
sion would develop a tractive force of
11' x 1'5 121 × 1'5
2'5
2.5
= 72.6 lbs.
748
MODERN STEAM PRACTICE.
for each pound of effective pressure on the inch of the pistons; and
to overcome the tractive resistance of 5000 lbs. the effective pressure
must then have been
-**
5000 – 68.6 lbs, on the inch.
72.6
This pressure on the pistons could be readily maintained by a boiler
pressure of 100 lbs. per square inch.
In another example of small-wheeled coupled engines on a short
line, the heaviest gradient on which was I in 12 for a length of
360 yards, the engine, weighing 7½ tons, took up a train loaded,
of equal weight as the engine, at a rate of from 4 to 6 miles
per hour. The cylinders of the engine were 8 inches diameter;
the stroke of the piston, 15 inches; there were four wheels,
coupled, 27 inches in diameter, with a wheel base of 4% feet.
Steam pressure in the boiler 120 lbs. per square inch. So we
have-
RESISTANCES.
Resistance due to gravity, 15 tons at 186.6,
Resistance due to speed, 15 tons at 8:21,
Engine friction, 7.5 at 18 lbs. per ton,.
Waggon friction, 7.5 at 10 lbs. per ton,
...
||
lbs.
2799
123
135
75
Total,........
3132
Tractive force per lb. on the inch of the piston,
82 x 15
27
= 35 lbs.
Steam pressure per lb. on the inch,
3132
= 92 lbs.
35
This pressure could be easily maintained, considering the steam
pressure in the boiler is 120 lbs. per square inch.
Adhesive power of locomotives.-The adhesive force of locomotive
engines is due to the load on the driving wheels, when they are not
coupled; but for goods engines, and ordinary coupled passenger
engines, the adhesive force is due to the weight on all the wheels
that are coupled. The adhesive force per ton of load on the wheels
varies from 600 lbs. per ton when the rails are in a good condition,
to 300 lbs. per ton when they are in a moist and greasy condition.
The adhesive force must be greater than the tractive power of the
wheels on the rails, otherwise the wheels will slip; consequently,
we consider that the weight upon the wheels should be so arranged
as to give the full tractive power when the rails are in a moist or
slippery state; in ordinary English weather this may be taken at
450 lbs. per ton of load on the wheels.
LOCOMOTIVE ENGINES.
749
Distribution of the load.—The average distribution of the load on
a six-wheeled engine may be found by multiplying the total weight
of the engine by the following, assuming the total weight of engine
to be I-
PASSENGER ENGINES WITH THE DRIVING AND TRAILING WHEELS COUPled.
Load on the leading wheels, multiply the total weight by.....
Load on the driving wheels,
Load on the trailing wheels,
""
""
*30
*46
*24
GOODS ENGINES WITH THE WHEELS ALL Coupled.
Load on the leading wheels, multiply the total weight by...
Load on the driving wheels,
Load on the trailing wheels,
""
I'
I'
346
*36
*294
To find the centre of gravity horizontally when the load on the axles
and distance apart are given.
Four-wheeled engine. For engines with four wheels, multiply the
load on the driving axle in tons by the length of the wheel base in
feet, and divide by the total weight in tons; the quotient gives the
horizontal distance in feet of the centre of gravity from the other
axle. Note.-When the loads on the axles are equal the centre of
gravity lies half way between them.
Six-wheeled engines.-For engines with six wheels, multiply the
loads on the fore and hind axles in tons, by their respective dis-
tances from the middle axle in feet, find the difference of the pro-
ducts found, and divide this distance by the total weight in tons;
the quotient is the distance in feet of the centre of gravity from the
middle axle, measured towards the axle, for which the greatest
product was found. Note.-When the products are equal the centre
of gravity lies exactly over the middle axle.
To find the loads on the axles, when the total weight, the distance
of the axles, and the position of the centre of gravity horizontally, are
given.
Four-wheeled engines.-For engines with four wheels, multiply
the total weight in tons by the distance of the centre of gravity from
the driving axle, and divide by the length of wheel base. The
quotient is the load on the other axle in tons; and the difference of
this and the total weight is the load on the driving axle in tons.
Note. When the centre of gravity is half way between the axles
the loads on the axles are equal.
750
MODERN STEAM PRACTICE.
F
For engines with six wheels.—When the load on the middle axle
is given, multiply the total weight in tons by the distance of the
centre of gravity from the hind axle in feet. Multiply also the load
on the middle axle by its distance from the hind axle; find the
difference of these two products, and divide it by the wheel. The
quotient is the load in tons upon the front axle; whence the load
on the hind axle may also be found.
When the load on one of the axles is given, multiply the total
weight by the distance of the centre of gravity from the other end
axle, on which the load is unknown. Multiply also the given load
by the wheel base; find the difference of these products, and divide
it by the distance of the middle axle from the aforesaid end axle.
The quotient is the load in tons upon the middle axle; whence the
remaining load may be found.
Mem.-The conditions which chiefly control the arrangement of
the axles are that there shall be a sufficiency of weight on the lead-
ing wheels for safely guiding the machine, and on the driving wheels
for the purpose of traction. To illustrate this, we will take two
engines of the passenger type, with and without coupled wheels,
of which the following are the necessary data:-
Six-Wheeled Passenger Engine, Single Driving Wheel
in the middle or front of Fire Box.
Wheel base,
Front to middle wheel,
Middle to hind wheel,
•
Centre of gravity with respect
to middle axle,………..
Total weight,..
....
Load on front axle,..
Load on middle axle,
Load on hind axle,.
Six-wheeled Engine, Driving and Trail-
ing Wheels Coupled.
12 ft. 0 in.
6 "
...
""
5,
6,, 6
""
6 in. before
::
19 tons.
5 ",
15 cwts...
9"
15
""
3 ",
ΙΟ
12 ft. 8 in.
5 4
""
""
7,, 4,
4 in. behind
19 tons 10 cwts.
5
9
4
""
""
15
о
15
Tables showing the diameter of cylinders, stroke of the piston, diameter
of wheels, and wheel base.
ENGINES WITH ALL THE WHEELS COUPLED.
Diameter of cylinders,
.
Stroke of the piston,
Diameter of the wheels,
Distance between driving and
leading wheels,.
Distance between driving and
hind wheels,
Wheel base,
16 in.
16 in.
16 in.
18 in.
24,,
24,
54,,
60,
24,
60
24,,
""
57 "
7 ft. 8 in.
6 ft. 9 in.
7 ft. 9 in.
7 ft. 1½ in.
7 7
15,, 3,
""
5,, 3 ",
12 ft.
7
""
9
8
15,, 6
15,,
1½
3
""
""
* Engine marked thus, the wheels are all placed in front of the fire box.
LOCOMOTIVE ENGINES.
751
14 in.
Stroke of piston,
""
Diameter of coupled wheels,..
""
Diameter of leading wheels,...
Distance between driving and
ENGINES WITH THE DRIVING AND HIND WHEELS COUPLED.

Diameter of cylinders,.
20
66
44,
15 in.
63
15 in.
66
42,
18 in.
22
20
""
""
24,
73",
""
36
43,
leading wheels,
6 ft. 6 in.
7 ft. 6 in.
6 ft. 0 in.
6 ft. I in.
Distance between driving and
hind wheels,....
6
6,,
6,, 6
8,,
6
9,, o
Wheel base,..
13,
14,
14,
6
་་
""
15,,
I
*
* Engine marked thus is a tank engine, with a bogie truck in front, the distance between
the driving and leading wheels is taken to the centre of the truck, the truck wheels being
4 ft. 6 in. apart from centre to centre.
ENGINES WITH THE DRIVING AND LEADING WHEELS COUPLED.

Diameter of the cylinder,
15 in.
16 in.
16 in.
16 in.
Stroke of the piston,
24,,
Diameter of coupled wheels,
57 ",
Diameter of hind wheels,... ..
42,
20
""
55,"
4334,
5514
42/4,
20
22
""
""
Distance between driving and
leading wheels,...
6 ft. 9 in.
6 ft. 0 in.
6 ft. 2 in.
Distance between driving and
hind wheels,
Wheel base,
6, 6
13,, 3,,
7 ", O
13,, O
""
7"
13 ",
""
*34
I
3
60
""
42,,
7 ft. 3 in.
7
14,,
36
""
*This is a tank engine.
ENGINES HAVING NONE OF THE WHEELS COUPLED.

Diameter of the cylinder,
14 in.
15 in.
16 in.
16 in.
Stroke of the piston,.
22,
20
20
22
""
""
""
Diameter of driving wheels,
72,,
69
""
78
Diameter of front lead-) Both placed
ing wheels, .....
in front of
42,,
42,,
42,,
Diameter of back lead- (the driving
ing wheels,
wheels,
42,
42,
42,
78
48,
48,
""
""
5 ft. and 7 ft. 4 in. 5 ft. 10 in.
7 ft. 3 in.
7 ft. 9 in.
none.
7
12 ft. 4 in.
4% in. 7 ft. 3,,
13 ft. 2%
"14 ft. 6
15
75
""
3,,
O
Distance between driving and lead-
ing wheels,
Distance between driving and hind
wheels,.....
Wheel base,
Table of weight of six-wheeled engines taken from practice.
Length of outside fire box,
Length of body of boiler,.
Diameter of wheels,.
ALL THE WHEELS COUPLED.

.....
6
7 4
""
""
4 ft. 4 in.
14,
O
4 ft. II in. 5 ft.
ft. 2 in.
ΙΟ 6 ΙΟ 6
""
""
O
""
5 ",
O
""
II
29
5 ",
7,,
O
9
...
""
5 3
II
""
7
9
O
812
IO
44",
tons.
O
9/2,:
10½ tons.
9
""
92
""
834
8
""
""
II/2
7/2
""
2614
""
272
""
292
Distance between driving and leading wheels,
Distance between driving and hind wheels,.
Centre of gravity in front of driving wheel centre,
Weight on leading wheels,.....
Weight on driving wheels,
Weight on hind wheels,.
Total weight,
...
72,,
8½ tons.
*
Engine marked thus has all the wheels in front of the fire box.
752
MODERN STEAM PRACTICE.
ENGINES WITH DRIVING AND HIND WHEELS Coupled.
Length of outside fire box,
..
Length of body of boiler,
Diameter of coupled wheels,.
Diameter of leading wheels,
Distance between driving and leading
wheels,......
Distance between driving and hind
wheels,...
Weight on leading wheels,
Weight on driving wheels,.
Weight on hind wheels,.
Total weight,
3 ft. 7½ in.
42
953
""
""
""
7 ft. 0 in.
o
8 6
3 ft. 9 in.
""
O
""
5
6
6
""
3,,
6
5,, 4
6,, 6,,
7,, 4
""
6,
6
534 tons.
9
""
"9
434
192
6 tons 10 cwts.
9 " 15
II
5
6
""
3,, 6 ""
6,, 0,,
8,, 6,,
8 tons
8 cwts.
8
II
""
""
7
""
""
5 ",
8
ΙΟ
""
""
23" 5
""
25, 9,
*
* This engine has an inclined fire box, with hind axle placed underneath the box.
ENGINES HAVING NONE OF THE WHEELS COUPLED.

Length of outside fire box,...
Length of body of boiler,
Diameter of driving wheels,
Diameter of leading and hind
wheels,
3 ft. 7½ in.
ΙΟ о
""
ཁྐྲཾ "
366
780
""
6
""
O
3 ft. 7½ in.
9 9
5 ft. 7 in.
IO
ΙΟ
4 ft. 10 in.
6
""
""
""
""
5 "
6
O
""
""
3,, 6
3,, 6
""
4,,
""
5", 9",
5,, 6
Distance between driving and
79, 0
6,, 6
""
Distance between driving and
leading wheels,.
hind wheels,
Centre of gravity in front of
driving wheel centre, .
Weight on leading wheels,
...
Weight on driving wheels,...
Weight on hind wheels,
Total weight,.
O
""
4,"
པ
7,, I
7,, 7,
7,9
3 "
7,, 3 ",
I
4
""
""
64",
8½ tons.
""
3½
""
10½
52
""
1234
""
62
""
19
27
2734
""
0,, 94
534 tons.
9½
234
18
""
""
O 6
534 tons.
934
II tons.
Diameter of the cylinder.-To find the diameter of cylinder for a
given tractive power, the mean pressure of steam in the cylinder,
length of stroke, diameter of driving wheels being given. We
certainly consider that locomotive engines should be bought and
sold by the amount of tractive power they develop, suitable to the
requirements. Supposing a tractive power of, say, 9266 lbs. is wanted,
the mean pressure being 90 lbs. per inch, the length of the stroke of
the piston 24 inches, and the diameter of the driving wheel, say,
60 inches.
To find the cylinder's diameter, multiply the tractive force by the
diameter of the wheel, dividing the product by the mean pressure,
multiplied by the length of the stroke of the piston, and the square
root of the quotient will be the diameter of the cylinder, thus-
9216 x 60=552960
=
90 × 24 = 2160 √256=16 inches diameter.
LOCOMOTIVE ENGINES.
753
CYLINDER PROPORTIONS.
Area of each steam port, divide the cylinder area in square inches by 10
Area of exhaust port,
Area of each steam pipe,
Area of main steam pipe,
Area of each blast pipe at bottom,
""
Area of blast orifice,
""
""
""
""
6
9
6
9
13
Length of steam and exhaust ports and opening by valve.-To find
the length of the ports, divide the diameter of the cylinder by 1.2.
The opening by valve is found by multiplying the area of the
cylinder by the speed of the piston in feet per minute, dividing the
product by the constant 10,000, this will give the area of the open-
ing by valve in square inches.
Thickness of the cylinder.—To find the thickness of the metal in
the cylinder, multiply the diameter by the steam pressure, as in the
boiler, and divide the product by 120, this will give the thickness in
sixteenths of an inch nearly.
Area of piston rod and depth of piston.-Multiply the area of the
cylinder in sq. inches by the steam pressure per sq. inch, and divide the
product by 4480, and the quotient is the area of the rod in sq. inches.
For the depth of piston multiply the diameter of the cylinder by 28.
Area of slide-valve rod and pins for valve motion.—To find the
area of the slide-valve rod, divide the area of the valve face by 100.
The pin for carrying the sliding block in link equals the diameter
of the rod nearly, being a trifle more, the pin on eccentric rod end
being of the same diameter; the rods are a third more in width than
the diameter of the pin at the small end tapering to the eccentric end.
Maximum speed of piston.-For a speed of 40 miles per hour and
upwards allow 15 feet of piston speed per minute for each mile per
hour; thus at 40 miles per hour 15 × 40=600 feet per minute; at
the same time, so long as an engine runs steadily, the speed of piston
may be more.
Ratio of the diameter of cylinder to the stroke of piston.-The
ratio of the diameter to the stroke of piston varies to suit the
requirements; the usual proportion is as 3 to 4; thus for 15 inches
diameter the stroke is 20 inches; while in some small engines
suited for heavy gradients the diameter of the cylinder may be
8, 9, or 10 inches, the respective strokes being 15 inches.
Ratio of the stroke of piston to the diameter of driving wheels.—
The ratio varies to suit the requirements; from 1 to 3½ to I to 4
work well for high speed on the rails. For lower maximum speed
48
754
MODERN STEAM PRACTICE.
the ratio may be as I to 2; while for small engines suited for heavy
gradients the stroke in some cases is 15 inches, the diameter of the
wheels being 27 inches.
Number of cubic feet of water required to be evaporated for a given
speed of engine per hour.—We will suppose a speed of 25 miles per
hour is desirable with, say, 16-inch cylinders, stroke 21 inches, and
5 feet 6 inches the diameter of wheels.
To find the number of revolutions, multiply the number of feet
in a mile by the speed in miles per hour, dividing the product by the
circumference of the driving wheels, and the quotient gives the
number of revolutions, thus-
5280×25
17.3
= 7630 revolutions per hour.
Now we will suppose the steam pressure is 90 lbs. per square inch,
and that it requires 6 cubic inches of water to raise a cubic foot of
steam at that pressure.
To find the number of cubic feet of water required.-Multiply the
number of revolutions per hour by the cubic contents of both cylinders
in feet for an entire revolution, and then by the number of cubic
inches to raise a cubic foot of steam at 90 lbs. per square inch,
dividing the product by 1728, gives the number of cubic feet of
water required, thus—
X
7630 × 9'7 x6
1728
=256 cubic feet of water required.
The boiler: proportions of fire-grate and heating surfaces:·
Area of fire grate.-Multiply the period of admission in hundreds
of the stroke by '0275, and add 175 to the product; multiply the
sum by the tractive force due to the given dimensions of engine,
and by the speed in miles per hour. Divide the product by 48,187.
The quotient is the area of the fire grate in square feet.
Table giving the dimensions of fire grate, tubes, and diameter of
cylinder, and length of stroke of the piston.
ENGINES WITH ALL THE WHEELS COUPLED.
Diameter of cylinder,
Stroke of the piston,
Length of fire grate,
Breadth of fire grate,
Area of fire grate,....
Number of tubes,
Diameter of tubes
outside,
16 in.
24",
4 ft. 0 in.
o
3, 5 ?
3" 5
136 sq. ft. 13 6 sq. ft.
13.6
ft.
149
16 in.
24,
4 ft. 0 in.
16 in.
24,,
4 ft. 6 in.
16 in.
24,,
4 ft. 3 in.
18 in.
133
3,, 5,
15.5 sq. ft.
158
4, 8
o ft. 2 in.
•
Length of tubes,……...
II
4 "
oft. 2% in. o ft. 2 in.
13,, 10
ΙΟ 4
""
ΙΟ 9,,
وو
....
3 6
148 sq. ft.
191
o ft. 2 in.
II,, 6
24,,
4ft. 10½ in.
27.5 sq. ft.
256
o ft. 2 in.
LOCOMOTIVE ENGINES.
755
Heating surface.—To find the heating surface, multiply the
number of cubic feet of water evaporated per hour by the area of
the fire grate in square feet; find the square root of the product,
which, multiplied by 212, gives the total heating surface in square
feet.
SIX-WHEELED ENGINES, WITH FOUR WHEELS COUPLED.
Diameter of cylinder,
Length of stroke,.....
Length of fire grate,
Breadth of fire grate,
Area of fire grate, .
Number of tubes,………….
Diameters of tubes,..
Length of tubes,..
Fire-box heating sur-
face,.
....
Tube heating surface,
Total heating surface,
13 in.
20
3 ft. 6½ in.
""
3,, 52
119 sq. ft.
158
o ft. 1% in.
IO,, 3,
20
14 in.
6 ft. 6 in.
I 74
1925 sq. ft.
210
oft. 134 in.
9,, 134
""
15 in.
15 in.
20
""
""
3 ft. 0 in.
3 6
10'5 sq. ft.
150
o ft. 1% in.
II
22
3 ft. 54 in.
3,, 034
10'52 sq. ft.
145
oft. 18 in.
1%
IO 4
""
""
16 in.
20
3 ft. 6 in.
3
2
II sq. ft.
212
I
oft. 1% in.
IO,, 7 7 "
""
64 sq. ft.
712.6
107 sq. ft.
58 sq. ft.
65 sq.
ft.
65 sq.
ft.
755
750
662
984
776.6
862
808
727
1094
To find the cubic contents in feet and area in square feet of the
body of the boiler approximately: dividing the cubic contents of both
the cylinders in inches by 80 will give the cubic contents of the
body of the boiler, which, being divided by the length of the body:
will give the area in square feet approximately.
Strength of boiler.
TABLE OF The Working STRENGTH OF JOINTS.

Best Yorkshire.
Best Staffordshire.
Scarph welded,………….
lbs.
I1,000
lbs.
9000
Double rivetted, double welt,.
•
9,000
7000
Double rivetted lap,...
8,000
6500
Lap welded,
7,400
6000
Double rivetted, single welt,..
7,300
6000
Single rivetted lap,
6,700
5400
Body and round parts of boiler.-To find the working steam pres-
sure due to a given diameter, thickness of plates in decimal parts
of an inch, and particular kind of joint; multiply the thickness of
plates in decimal parts of an inch by 2 and by the working
strength of the longitudinal joint in pounds per square inch as above;
and divide by the diameter of the body in inches; the quotient is
the working pressure of the steam in the boiler in pounds per square
inch.
756
MODERN STEAM PRACTICE.
To find the thickness of plates in decimal parts of an inch due to
a given diameter, particular kind of joint, and working pressure;
multiply the working pressure of steam in pounds per square inch
by the diameter in inches, and divide the product by the working
strength of the longitudinal joint in pounds, and then again by 2;
the quotient is the required thickness in decimal parts of an inch.
Flat parts of boilers.-The strength of the flat parts of boilers
depends entirely on the strength of the stays, which are arranged
at regular intervals, dividing the surface into segments, which may
be reckoned as one segment to each stay. The fire-box stays are
arranged in squares, pitched equally.
To find the working steam-pressure due to a given diameter of
the rod, and area of segment stayed, the working tensile strength
of best iron rods being as follows:-
I
8 inch diameter,
inch diameter,
1% inch diameter,
8,000 lbs.
10,000,,
13,000,,
If the section of the rod is reduced by screwing, 10 per cent. is deducted
from the working strength.
Divide the working strength of the tie rods in pounds by the area
of the segment in square inches; the quotient is the working steam
pressure in pounds per square inch.
To find the area of segment due to a given diameter of tie rod
and working pressure, divide the working strength of the tie rod
in pounds by the steam pressure in pounds per square inch; the
quotient is the area of the segment in square inches.
Screwed stays.—Screwed bolts are generally pitched in squares
or right angles.
To find the working pressure due to a given pitch, screwed and
rivetted into the plates, the solid diameter of the stays being 3/4 inch,
the working strength being as follows:—
Copper stay bolt in copper plates,.
Iron stay bolt in copper plates,
Iron stay bolt in iron plates,
3200 lbs.
4800
5600
""
Divide the working strength of the stay in pounds by the product
of the pitches, multiplied together horizontally and vertically; the
quotient is the working pressure in pounds per square inch.
To find the pitch of the stays due to a given pressure, divide
the working strength of the stay bolts in pounds by the working
LOCOMOTIVE ENGINES.
757
pressure in pounds per square inch, and find the square root of the
quotient, the result is the pitch in inches. Note.—The working
strength cannot be materially affected by the thickness of the
plates.
Pitch of the stays in the fire box. The pitch of the stays varies
from 4 inches horizontally and 5 inches vertically to 4½ inches each
way for iron stays. For copper stays from 4 inches each way to
44 inches each way, and some have been pitched 3½ one way and
4 the other way.
Roof stays of the fire box.-To find the pressure carried by the
roof stays of the fire box, multiply the span of the roof in inches
by the pitch of the stays in inches, and by the pressure in pounds
per square inch, and divide by 2240; the quotient is the pressure
uniformly distributed, borne by each roof stay in tons.
To find the working strength of a roof stay of given dimensions,
fixed in its place, multiply the thickness of the stay at the centre in
inches by the square of its depth at the centre in inches, and by 30,
and divide the product by the length of span in inches; the quotient
is the working load, equally distributed in tons, when the stay is
fixed in its place.
Note. The side plates of the fire box sustain part of the pressure
on the roof, and consequently the whole pressure, as calculated for
the roof stays, errs on the safe side.
WEIGHT AND STOWAGE OF FUELS, &c.

Kind of Fuel.
Weight per Stowage weight Space to stow Weight of water
foot.
per cubic foot.
I ton.
evaporated per
lb. of fuel.
Coal,
Coke,.
Pine,...
80
•
63
988
lbs.
lbs.
cubic feet.
lbs.
51
44
9
28
80
9
21
107
22
Equivalent fuel to
evaporate the same
weight of water.
Coal being 1'o.
ratio.
I'O
I'O
3.6
Area for safety valves.—To find the diameter of each valve, two
being fitted, multiply the number of square feet of heating surface
in the fire box by 144, dividing the product by 450, and one half of
the quotient is the area for each valve in square inches; thus, for
68 square feet of heating surface in the fire box-
68 × 144
450
=217÷2=10.8=say, 31 diameter.
The spring balance represents a weight of 100 lbs. more or less
according to the pressure required, and the length of the lever is
758
MODERN STEAM PRACTICE.
calculated in the first instance to the greatest amount of total pres-
sure upon the valve. Thus, with an area 108 and 100 lbs. steam
pressure, the distance of the centre of valve from the short end of
the lever being 3.5 inches, we have-
10'8×100 × 3*5=3780÷100=37·8,
The total length of the lever from the stud to the spring balance.
Diameter of the feed pump.-Find the cubic contents of the steam
cylinder in feet for an entire revolution, multiply the result by the
number of cubic inches of water required to raise a cubic foot of steam
at the required pressure, divide the product by the stroke of the pump
in inches, then multiply the quotient by 15; this will give the area
of the pump. Then, by a table of areas, you can find the diameter.
This is when the stroke of the pump equals that of the steam
cylinder, two pumps always being fitted. We will take an example.
The diameter of the cylinder being 16 inches; stroke of piston,
24 inches; steam pressure, 100 lbs. per square inch, requiring
6.6 cubic inches of water to raise a cubic foot of steam at that pres-
sure, thus-
I
1*396 × 4 × 6.6
24
1'53 × 1'5 = 2'29, say 134 inch diameter.
The Giffard injector.—When Q represents the quantity of water
injected in gallons per hour; P, pressure of steam in atmospheres;
D, diameter of throat in inches--
D = *0158
VP
0 = (63'4 D)² VP

Diameter of throat in
decimal of an inch.
Delivery in gallons per hour with a pressure
per square inch as under:-
30 lbs.
60 lbs.
90 lbs.
120 lbs.
150 lbs.
'I
56
80
98
113
127
*15
127
180
221
255
285
'2
226
321
393
455
508
*25
354
502
615 711
793
'3
505
722
884 1021
1140
Area of axles and boxes.-To find the area of cranked axle: mul-
tiplying the total weight on the axle by 3'5, will give the area at
the pin, and for plain axles by 29, will give the respective areas in
square inches. The cranked axle at centre may be ½ inch less in
LOCOMOTIVE ENGINES.
759
diameter, as likewise the diameter of the inside journals. The out-
side journals may be 1 inch less than the pin in diameter; for the
length of the outside journals multiply the diameter by 1.36; in some
plain axles the length of the journal is the same as the diameter.
The distance between the jaw of the cranks is bare inch less
than the connecting rod brasses, the thickness of the jaws in direc-
tion of the length of axle is three-fourths the diameter of the pin.
The raised part for taking the wheels may be 1 inch larger in
diameter than the inside journals, the length being equal to the
diameter. The bearing surface or top brass in the axle boxes
should have a surface of not less than 18 square inches for every
ton on total load on the axle. For ordinary sides of, say, 5% dia-
meter of axles the brasses are 3/4 inch thick at top and ½ inch at
side, and the axle box 14 inch thick at top and I inch at side.
Dimensions of wheels. For ordinary 5-feet wheels, all of wrought
iron, the eye of the wheel is 7 inches, the length of the boss
634 inches, the greatest thickness of boss is struck with a radius
equal to the diameter of the eye from the centre line. The spokes
are flat, 3 inches broad at point and 3½ inches at the boss, and
from 1% to 14 thick at point, and from 13% to 1½ inch at boss.
The pitch of the spokes at the inside tyre or trod is II inches.
on the average. The inside tyre, 54 inches broad, by 13% at middle
and 7% inch at edge. The outside tyre, 2 inches in thickness at
middle. The flanges about % inch deep and 5% inch broad for
driving wheels, and 14 inch deep and 14 broad for leading and
driving wheels.
For 3-feet wheels all of wrought iron: eye 6 inches diameter;
length of boss, 634 inches; diameter of boss, 10½ inches; spokes, I to
1% thick at point and 14 to 13% inch thick at boss. The inside
tyre 54 by 1% inches, and the outside tyre 54 by 1% inches, the
number of spokes being ten.
Dimensions of springs and harness.-Ordinary springs, when
loaded, are 2 feet 8 inches from centre to centre, and when unloaded
2 feet 74 inches, having a set of 54 inches from centre of scroll to
top of plates, the breadth of the plates being usually 4 inches. To
find the depth of the spring, multiply the constant 8.5 by the total
load on the axle in cwts., then by the length of the spring in inches
when loaded, dividing the product by the breadth of the spring in
eighth parts of an inch, and the square root of the quotient is the
depth in eighth parts of an inch. Top plates, & inch thick at middle,
760
MODERN STEAM PRACTICE.
5
16
and ½ inch at ends; all the other plates, inch in thickness; sus-
pension pins, I inch in diameter; eye, 24 inches diameter.
To find the area at the bottom of the thread for tension rods of
spring harness, divide the total weight on the axle by 4, and then
by 2, and the quotient will be the area at the bottom of the thread,
adding the thread gives the total diameter. The compressive pin
in steel equals the total diameter of the tension rods. When fitted
with side links, the suspension pins being, say, I inch in diameter,
the side links may be 1½ inch broad and 5% inch in thickness.
Dimensions of framing.-The minimum dimension of framing for
a goods engine with six wheels, all coupled, 5 feet in diameter, is
9 inches broad by 7% inch in thickness for inside frame, and 9 inches
broad by 1 inch in thickness for outside frame, the horn plates
being ½ inch in thickness, rivetted to the outside beams, forming
the framing, the inside and outside beams being strongly bracketted
together, and the horns stayed together, and diagonally to the end
beams with flat stays, 234 × I inch in thickness. For ordinary pas-
senger engines the minimum dimension of the inside frame is
about 12 inches in depth, and for the outside frame, 9 inches in
depth for plain bars, the horns being forged on. Of course.
there are a variety of frames made much deeper and cut out to
lighten them. The front and end beams of oak may be from 5½
to 6 inches thick and 12 inches in depth, strengthened with corner
plates, angle iron, &c.
Area of crosshead, motion bars, &c.—To find the area of the gud-
geon of crosshead, divide the area of the cylinder by 28, this will
give the area in square inches. To find the area of the slide-block
pin in square inches, divide the area of the cylinder by 80. The
thickness of the brass blocks is about ½ inch, this, supposing the
pin to be 134 inch, will give 234 inches to the depth of the sliding
or guide blocks; for the length of the sliding blocks multiply the
diameter of the pin by 5.8. For the breadth of the motion bar take
12 less than the diameter of the gudgeon for crosshead, when double
motion bars are used, thickness of the motion bars one-half of the
diameter of crosshead.
Or treating the motion bars as a beam and allowing one-third of
the pressure on the piston as the thrust, multiply this thrust by the
distance between the points of support in feet, dividing the result
by the constant 1338 (for iron) multiplied by the total breadth; then
the square root of the quotient will be the depth of the bars. For
LOCOMOTIVE ENGINES.
761
bolts one-third of the total pressure on the piston by 4000 gives the
total area of the bolts at the bottom of the thread.
Area of connecting rod.-To find the area of the small end, mul-
tiply the area of the piston by the steam pressure in pounds per
square inch, and divide by 4000 for the area at the small end, the
breadth being equal to the diameter of the gudgeon of the crosshead.
For the breadth at the crank end, multiply the breadth at the small
end by 15 for connecting rods of about 6 to I of the crank. The
breadth of the large butt is regulated by the diameter of the crank
pin; for the thickness of the butt multiply the thickness of connect-
ing rod by 142. The breadth of the jibs and keys at the large end
equals the breadth of the rod at that end; for the thickness of the
keys divide the thickness of the butt by 3.3. The breadth of the
jibs and keys at the small end equals the breadth of the rod at that
end, and the thickness is the same as for the large end; the area of
the butt across the key way being equal, at least, to the area of the
piston rod; the same holding good as regards the smallest area
of the straps at the key ways.
Outside cranks and side rods.-The diameter of the crank pin
equals the diameter of the gudgeon for crosshead, the length of the
crank pin being 3% inch or so longer than the diameter. The dia-
meter of the large eye may be 4 inch smaller than the main crank.
pin as for cranked axles; for the thickness at eye multiply the
diameter of the eye by 3; for the breadth of the eye multiply the
thickness by 2; for the breadth of the web divide the breadth of the
eye by 1'4; the sides of the web are straight lines drawn from the
extreme diameters at each end. There is one large steel key let
into the web, 14 by 18 inch, and two other keys, 14 by inch;
for eyes, say, 614 inches in diameter.
5
16
The breadth of the body of the outside rods equals the diameter
of the crank pin, tapering to the centre of body; the thickness
should be regulated to give an area equal to nearly that of the
piston rod; the thickness of the butts should not be less than the
rods at the key ways, and their breadth 1,inch less than the length
of the crank pin. The diameter of the steel coupling pin for the
rods, when six wheels are coupled, may be one-third less than the
breadth of the rod at end; the diameter of the eye being twice
the diameter of the pin, and the thickness one-half of the diameter
of the pin. The thickness of the brasses is 7% inch or so at ends,
and 3% inch at sides. The keys are about 12 inches long, tapering
762
MODERN STEAM PRACTICE.
from 1% to 134, and 5% inch in thickness, for crank pins 3 inches
in diameter.
All the minor details in the locomotive engine, such as handles,
rods, pins, &c., should have ample strength, more so than what is
usually allowed in any other class of engine, so that the parts may
not vibrate or bend with the hand power applied. In the fore-
going rules we have given the leading formulas required, and which
are in general practice; the numerous engravings throughout this
section clearly show the details of handles, pins, and other minor
parts without further investigation.
ROAD LOCOMOTIVE OR TRACTION ENGINE.
Road Locomotives or Traction Engines have been used now for
some time with good results. In large towns they are most useful
for the haulage of heavy loads, which formerly could only be accom-
plished by a large number of horses; for agricultural purposes they
have been used for some time, and extensively in India for the
haulage of trains along the roads there both with goods and passen-
gers.
One of the essential features of a road steamer is the tyres of
the wheels and the method whereby the engine is connected with
the driving wheels. One great advance was made by the introduc-
tion of india-rubber tyres by Mr. Thomson of Edinburgh, whose
road steamers with india-rubber tyres proved very successful,
some of his engines being purchased by the Indian Government,
and a regular service of trains was started in the Punjab as far back
as 1873. These india-rubber tyres lessened the objectionable vibra-
tion of the engine and gave a high percentage of adhesion.
The
tyres are protected by iron shoes.
The engine is connected with the driving wheels by means of
spur gearing working on a counter shaft, by means of which fast or
slow speeds can be obtained by throwing suitable pinions in or out
of gear. These pinions are either made of malleable cast iron or of
crucible steel.
The boilers are sometimes of the vertical Field arrangement, the
engines being also placed vertically. In others the boiler is hori-
zontal, the machine not differing much in appearance from a railway
LOCOMOTIVE ENGINES.
763
locomotive. The wheels number either three or four, there being
two large as drivers and one or two for guides; these latter wheels
are steered by the driver or attendant by suitable gearing.
The speeds obtained by such engines necessarily vary with the
load, but in some cases speeds of 10,16,and even as high as 22 miles
per hour are obtained, and with a train of carriages about 5 miles
per hour over fairly steep gradients. The working expenses are
necessarily varied, being from 14d. to 3d. per ton per mile.
Mr. R. E. B. Crompton, in a paper read before the Institution of
Mechanical Engineers on this subject, says, "It cannot be denied
that the question of improved and cheapened haulage on our tram-
ways and streets is one of great importance for engineers and to the
public. Now when we consider the inconvenience to ordinary
wheeled vehicles of the present system of tramways when laid down
in crowded thoroughfares, the high frictional resistance of the cars
on the unmechanical tram rail, the liability to derangement of all
street traffic by the derailment of the cars or the accidental break-
down of any other vehicle on their line; and when we contrast with
this the traction engine, with its extreme handiness in turning and
steering, its high adhesion, its minimum of harm done to the road
surface, &c.; does it not point to the use of real railways of light
construction carried as far towards the crowded centres as traffic
will permit, and from thence onwards the hauling of the cars by
such engines as have been here described, but of lighter construc-
tion and capable of being readily steered and worked in with the
regular traffic?"-The following are the dimensions of engines as
used by Mr. Crompton:—
"Length of engine and tender,
engine only,
Extreme width of engine,
height to top of spark-catcher,
Outside diameter of driving wheels (original),
""
""
steering wheels,
(altered),
Width of driving wheels, outside armour,
Diameter of cylinders,
Stroke of
""
Diameter of crank shafts,
· counter shafts,
...
...
...
Average pressure of steam-lbs. per sq. in.,
Ratio of gearing, fast speed,
...
:
...
...
ft.
in.
31
ΙΟ
16 O
8
8
13
4
6
2
...
...
6 6
3
I
0
...
...
...
...
...
...
:
...
...
...
...
160
3'75 to I
ΙΟ
7
8
O ΙΟ
O
4
3%
slow speed,
...
(altered),
...
:
:
:.
12
I
8
I
764
MODERN STEAM PRACTICE.
It appears that the wear of the india-rubber tyres is on the inner
surface, which appears to be so far prevented by black-leading the
rubbing surface, but better still by preventing the slipping of the
tyre by making depressions on the wheel.
The traction engine has been used instead of horses for tramway
purposes; in some cases, however, the tramcar has the engine placed
at one end, so that one vehicle only is used.
PORTABLE ENGINES.
(See PLATE.)
Portable Engines are now much used for agricultural and other
purposes. They consist essentially of locomotive boilers, having an
engine placed on the top, and connected with a fly-wheel, which serves
for transmitting the power to any machine by means of belting; the
whole is set on wheels with broad tyres, by means of which it may
be readily shifted from place to place. Single-cylinder engines of
this class work up to about 10 horse-power; the double-cylinder
arrangement being made up to 20 horse-power. The total weight
of course varies with the power, a five-horse power engine being
about 3 tons, and a ten-horse power 5 tons.
The great point to be aimed at with such engines is economy and
durability, ample boiler power, and a steady base for the boiler
and engine to rest on.
Our Plate shows vertical and transverse sections of an eight-
horse power Portable Engine of approved construction. The boiler
is made of best plates (3% in. thick) and strongly stayed, with an
ample allowance of heating surface; and each boiler is tested to a
pressure of 120 lbs. per sq. inch before it is used. The fire box is
of best Yorkshire plates (3% in. and 5% in. thick), with a large grate
surface. The cylinder is 934 inches in diameter, with a stroke of
12 inches, and is furnished with a steam jacket. The piston and
valve rods are both of steel. There is no steam joint between the
cylinder and the boiler; the governor, which is both powerful and
sensitive, acts direct upon the throttle valve. The feed pump is
placed vertically, and is constantly at work whilst the engine is
running, either circulating the water through the heater or forcing
it into the boiler. The feed-water heater heats the water to nearly
LOCOMOTIVE ENGINES.
765
boiling point. The travelling wheels and fore carriage are of
wrought iron; the hind axle is cranked under the fire box, the
weight being taken on the bottom, which prevents the fire box from
being strained and joints rendered leaky. The main bearing
brackets have a large area of base, so that the strain is well dis-
tributed; and the bearings, eccentric straps, pump plunger, valve,
and seats are made of best gun metal.
STEAM ROAD ROLLER.
Steam Road Rollers are of much service in road making or repair-
ing, and effect a considerable saving on the road repairs, as the
road metal is thoroughly and effectually pressed into the roadway,
giving a hard and smooth surface for the traffic. A layer of metal
is laid down and the roller passes over it two or three times. Sand
well watered is then sprinkled over the surface and again rolled.
The mechanism is somewhat similar to the road locomotive, the
rollers taking the place of the wheels. Where four rollers are used
these are of equal widths, and are sometimes arranged so that the
two hind rollers act as drivers and the two in front as steering
rollers, the latter rolling on the space left uncovered by the driving
rollers. The weights of the rollers vary with width covered, such as
from 8 to 15 tons.
The Road Roller manufactured by Aveling and Porter of Ro-
chester weighs 15 tons, and has four broad wheels or rollers. The
front pair, 5 feet in diameter, act as driving wheels; the hind pair,
4 feet 9 inches in diameter, form as it were one broad roller, and
slightly overlap the tracks of the front pair. The rollers cover a total
width of 6 feet. The mounting of the hind rollers is so arranged
as to leave the fore wheels free to adjust themselves to the turns or
inequalities of a road. The arrangement of the cylinder and gearing
is the same as that of the firm's ordinary traction engine. Two men
attend the machine: one acting as steersman, the other, the driver,
stands on the opposite side of the engine, and feeds the fuel by a
side door in the fire box.
IRON SHIPBUILDING.
PRINCIPLES OF MARINE DESIGNING.
Steam vessels intended for the mercantile marine may be divided
into three classes. The first class is built expressly to carry a large
number of passengers and a light cargo, or no cargo at all; the
second class is the ordinary kind of ship, with accommodation for
both passengers and cargo; while the third class comprises ships
constructed to carry cargo exclusively, or ships of burden. The
form of each of these three classes differs very materially from that
of the others.
Passenger boats on rivers are designed to attain great speed;
their draught of water must necessarily be light to navigate the
numerous shallow places in a river's course, consequently the mid-
RIVER BOAT.
at the Fourth Water Line.

Steri
Centre
166 feet
Fig. 547.
Bow
Line
ship section is quite flat or nearly so, having very little slope up
from the keel to the side of the ship, or "rise of floor," as it is
termed. The forward and aft lines are made very fine, so that the
particles of water may have free motion past the vessel. The bow
lines on the line of the deepest immersion are formed like a wedge,
or a hollow line is introduced for that part cutting the surface of
the water. The after lines need not be so fine as those of the forward
part of the vessel, but must be sufficiently fine to enable the wave
raised by the paddle wheels gradually to fill up the vacuity left at
the stern; full after lines tend to drag the water, and when a vessel
has not a clean run aft, waves are raised that become dangerous,
and gradually destroy the banks of the rivers or canals navigated.
The passenger boats on the Clyde in some cases attain a speed
of twenty miles per hour and upwards, and they are fitted up in a
IRON SHIPBUILDING.
767
most luxurious manner. In some respects, however, American river
steamers eclipse those of this country, skimming over their courses
with great rapidity, and being fitted up with all the comforts of a
first-class hotel. They have the outward appearance of a palace
which is transported over a placid lake. The immersed form of
these vessels is quite flat from stem to stern. The bow and stern
are formed of a spoon shape; this is found necessary so as to offer
the least resistance to the water; and as some rivers have shoals of
sand in mid stream, this spoon-like shape naturally sucks the water
underneath the vessel, thus washing away the obstruction and form-
ing as it were a canal for the passage of the vessel.
manner.
The second class of ship, or ocean steamer, is constructed to
afford accommodation for a large number of passengers in addition
to cargo; it must also have greater carrying space for coal, as the
voyages such a ship has to perform are sometimes numbered by
weeks and months instead of days as with river steamers. Our
ocean steamers are now fitted np with every luxury that modern
improvement can suggest. They are designed for great speed, and
perform their voyages to distant climes in an easy and regular
The form of these vessels materially differs from that of
the river steamer. Ocean steamships must of necessity be much
longer and broader in the beam; the draught must be greater, dis-
placing a large body of water, the displacement being regulated by
the weight of the vessel, machinery, coal, &c., together with the
carrying power in cargo. The bow lines of these vessels, instead
of being exceedingly fine, like those of river boats, are made fuller
so as to afford buoyancy on the waves, the after lines having corre-
sponding fulness. This change of lines is required, for supposing
an ocean steamer were made as fine in proportion as an Oxford or
Cambridge outrigger, what would be the consequence in a heavy
sea-way? She would simply cut through the waves like the out-
rigger and drown herself. The light construction of some of our
river boats would not suit the twisting and straining an ocean
steamer undergoes at sea, requiring the structure to be strongly and
firmly put together. Still, this class of vessel must have a certain
amount of fineness to attain the speed that is required; for in these
days speed is the grand object sought for. Those companies having
the largest and quickest fleets are generally selected to carry the
mails—an important item in maritime business. Again, when old
established companies find rivals possessing ships of equal tonnage
768
MODERN STEAM PRACTICE.
and speed with their own, new vessels are ordered, and the builder
receives instructions to make them so long, so broad, and so deep,
with sufficient power to attain economically a speed of one knot or
more per hour over that of their opponents. Fast ships are in
universal favour with the public, so it is the interest of companies
to maintain the speed of their fleets; but it must be borne in
mind that the power necessary to propel a vessel through the water
varies approximately as the cube of the velocity.¹
The third class, or ship of burden, is constructed to give the
greatest carrying power in cargo, necessarily at the expense of a
corresponding loss of speed. Screw colliers, or vessels wholly
engaged in transporting coal from one port to another, are included
in this list. Such vessels are generally fitted up so that the return
voyage is made in ballast. The bottom is made double to form a
water tank or tanks; water is run into these tanks, and on the ship
arriving at the coaling station it is pumped out, with a small pump-
ing engine fitted on board for that purpose. This is certainly the
quickest and cheapest method for ballasting ships, and it is quite
safe, the tank or tanks being at the bottom of the vessel; but the
tanks must be entirely filled with water, for unless this is done water
ballast becomes the most dangerous of all cargoes. The permanent
weights in a ship should be kept down as low as possible, because
the vessel is better ballasted when the weight is low down; but it
must be borne in mind, that when a ship is loaded with a heavy
cargo, such as iron, a portion of such cargo should be kept high or
stowed between decks, otherwise there will be a risk of making the
ship too stiff, and of not preserving a proper equilibrium. Unless
this is attended to the ship will roll violently, and run the risk of
springing a leak or breaking a mast. The circumstances are, how-
ever, entirely changed when the vessel is returning in ballast.
These vessels must be made very strong; for, with a cargo of coal
or iron, the structure may be compared to a hollow beam with the
load distributed. The strains of tension, compression, and torsion
which a ship undergoes at sea are very great, so it is imperative that
all ocean steamers be made of great and uniform strength, having
no parts either excessively strong or comparatively weak; for it has
been truthfully stated, that when a part of a vessel is made very
much stronger than the general structure, it will break near to that
part. This is evident, as a vessel must have a certain amount of
1 For recent data as to this law see p. 783.
IRON SHIPBUILDING.
769
elasticity, and if not uniformly elastic, the part having the greatest
measure of elasticity is sure to separate from that portion of the
structure which is the most rigid. In iron steamships it is usual to
make the length between the perpendiculars from seven to nine
times the breadth of beam, Some builders, however, have gone so
far as to increase that proportion to ten and three-quarters; and
when such ships are properly constructed, locating the greatest
strength where it is most required, namely, at midships, they have
been found to answer without showing signs of weakness.
All vessels may be practically considered as hollow beams;
the deck is the top web, and the bottom of the ship the lower web.
In all scientifically constructed beams of the parallel kind, the
greatest sectional area of the webs is at the centre, therefore at the
bottom of a ship amidships the sectional area of the plating should
be much greater than at the ends, and the deck should be plated
or strengthened with stringers and diagonals. In fact, to make it
resemble a hollow beam, some plate the deck all over: this plan may
answer with corrugated plates, but plain plating is not so suitable.
A plated deck, however, can be covered with a wooden one; this
secures as good foothold as in ordinary ships, while the comfort
afforded in all weathers far exceeds that of plain iron decks. The
latter are very cold for the feet in winter, too hot in summer and
intolerably so in tropical climes; and the foothold in rough weather
is very precarious, the plates becoming smooth and slippery.
The depth of hold varies from one-tenth to one-twelfth of the
length between the perpendiculars. The length between the per-
pendiculars is measured on the line of deck or mid-deck for spar-
decked ships taken from the after end of the stern post to the fore
rake, or exactly the length of the vessel's deck from the after part
of the stern post forward.
The displacement is the cubical contents of the immersed portion
of the vessel; the ship resting on the water displaces a certain bulk,
the weight of the water displaced being equal to the total weight of
the vessel and all contained in it. When the draught of the ship
is made it is necessary to calculate the displacement in cubic feet;
the weight of a cubic foot of sea water is taken at 64 lbs., and there
are 35 cubic feet to the ton. The displacement may be calculated
approximately by multiplying together the immersed length, depth,
and breadth, and taking, according to the class of vessel, from one-
half to three-fifths of the cube thus obtained; this will be the dis-
49
770
MODERN STEAM PRACTICE.
,
placement in cubic feet, which, being divided by 35, equals the tons
of displacement approximately.
LAYING DOWN THE LINES OF VESSELS.
The dimensions of a vessel being determined, the designer can
commence laying down the lines. The sheer plan is the first step.
We will take as an example a river boat, suited for the paddle-
wheel mode of propulsion. The midship section or greatest breadth
of such a vessel is generally located a little abaft the centre of the
length of the boat. Draw a line, which we will name the base or
line of keel; raise a perpendicular on this line at the point deter-
mined on for the greatest breadth, marked thus ; this we will
name the midship section, the configuration of which is delineated,
RIVER
BOAT.
Sheer Plan.

Half Breadth Plan.

12
11
10
8
72
6
5
Figs. 548, 549-
the perpendicular representing the centre line of the vessel. The
rise of floor, or slope up from the keel to the side of the vessel, we
will say is 6 inches, while the half breadth is 9 feet, and the depth
moulded, or height from keel to the side of the ship, 8 feet 6 inches,
and the height of the bulwarks 3 feet, making the total height of
sheer plan at midship, from keel to top of the bulwarks, II feet
6 inches; while the height at the bow may be 13 feet, and the
height at the stern 12 feet, for a vessel 170 feet long from the after
end of stern post to the bow. The curve embracing these points,
with the configuration of the stem and stern posts laid down, is
termed the sheer plan. The half-breadth plan now claims our
attention. The centre line being drawn, it may be divided into
twelve equal spaces, and perpendiculars raised at each point. It
is now necessary to determine the configuration of the load water
line. In this example the draught of water is, say, 4 feet, conse-
quently a line drawn on the sheer plan parallel with and 4 feet
above the keel will be the line of greatest immersion, or line of
flotation. Between this line and the keel other lines are drawn
IRON SHIPBUILDING.
771
I foot apart, each of them being so many more water lines of con-
figuration, depending more or less for the form they will take on
the line of flotation as set off on the half-breadth plan. As all
river boats are built so as to attain great speed, the bow lines must
be made long and fine, and the after lines of corresponding fineness.
So having determined the angle of entrance at the bow, and the
angle of exit, as we may term it, at the stern, lay off on the offset,
corresponding to the section of greatest breadth, as at 7 on the
half-breadth plan, the breadth, as taken from the midship section
on the line of flotation. A long thin strip of wood is then bent,
and held down on the paper with suitable weights, touching the
point set off at 7, and the experienced designer can tell pretty
nearly what form the curved line should assume, taking into con-
sideration the angles of entrance and exit. Some of the fastest
river boats have the bow lines on the line of flotation formed like a
straight-sided wedge, while others have the line slightly hollow.
We prefer the straight line, as we consider such a form offers the
least resistance to the water; a very hollow line tending to throw
the water off at right angles to the path of the vessel. Having
thus found the best form of water line on the line of flotation, the
designer measures the half breadth, from the midship section at
every foot downwards from the line of flotation, for the other lines
of configuration, and setting these breadths off on the offset at 7,
applies the batten as formerly, and it
will be seen in such a vessel that all
the other water lines run nearly equi-
distant at the various offsets from the
line of flotation. The outside line
delineated on the half-breadth plan is
the line of rail, and likewise shows
the deck accommodation that is de-
termined on. The body plan may
now be set out. This is simply the
configuration at the various offsets,
beginning at the midship section,
working to the stem at one side and to the stern at the other side of
the perpendicular, representing the centre line of the vessel. These
various sections are taken from the half-breadth plan,' and in this
part of the operation it is necessary to alter and fair the one with
the other, so as to make the configuration of each most pleasing to

BODY
PLAN
B
A
RIVER BOAT
Fig. 550.
A, Fore body. B, After body.
772
MODERN STEAM PRACTICE.
the eye. The skilled designer in laying down the lines of a ship
must not trust too much to rule of thumb, but will find himself
greatly assisted in forming a pleasing structure by the eye.
Thus we have taken one of the simplest problems the naval
architect has to solve, namely, the delineation of the structure, the
length, breadth, and depth of the vessel being given. Though this
is not in itself such a very difficult matter, yet a person who is skilled
in designing vessels will produce a much finer ship to meet the
desired dimensions and requirements than an inexperienced hand;
and it may be argued that the architect should be left unfettered
as regards the size of the ship to work most economically the trade
she is to be employed in. If we are to adopt the views of the
wave-line theorist, and delineate vessels according to his geometrical
configuration, designing becomes a rather easy matter.
We cer-
tainly think there are many good sea-going ships constructed in
the absence of this refined study of storm waves; nevertheless
there can be no doubt that nature lays down her own lines, and if
we deviate much from the natural laws that should govern the
construction of a good sea-going ship we greatly err. We have to
study the best form to combine speed and good sea-going qualities
with the required carrying power.
In designing vessels objections have been taken to the use of
the model. In our opinion it matters little whether the skilled
naval architect designs his vessel by drawing, or makes a miniature
vessel from a block of wood. We have known both methods
carried out successfully, the modeller working quite distinctly
from the draughtsman, and vice versa. We certainly think,
however, that the most scientific method is that now usually
adopted, of delineating the vessel by laying down the lines on
paper, and afterwards constructing the model according to these
lines; thus the draught assists the modelling, and the owners are
satisfied that the ship will be an exact counterpart of the model.
We consider this is the true solution of this important primary step,
and must tend to satisfy all parties before and after the contract is
signed. Let us have the lines of the ship laid down on paper, place
the model alongside, and we thus unite the science of the architect
with the art of the mechanic in this important preliminary.
For larger sea-going ships the same process is adopted for
laying down the lines as in the example of the river steamer.
The skilled naval architect determines the leading dimensions of
IRON SHIPBUILDING.
773
the vessel, adopts the best form of midship section to suit the
requirements, fixes on a water line that will give great speed, if
speed is an object, or adopts a water line of fuller character, giving
less speed but more carrying power. He will then determine the
most convenient size of deck to suit the navigation of the ship,
and with these primary points will frame the sheer and body plans,
run out a calculation of the immersed portion of the vessel; and
determine if the tons of displacement be equal to the weight of the
hull, machinery, and carrying power required. Having carefully
settled all these details, he may then consider the design brought
to as complete a condition as possible.
In choosing the best form of midship section for ocean vessels
the designer has no great scope, at least practically. If a swift
yacht, cruiser, or clipper is demanded, such a vessel must have
extremely little carrying power, the smallest amount of immersed
body, and the greatest depth of keel, to prevent her going leeward
under canvas. She will then possess the maximum of power
with the minimum of weight. This form can be further improved
on, and greater capacity given, by means of an elliptical section;
but when the vessel has to carry so much that with such a con-
struction her sea-going qualities would be impaired, a much fuller
section is given, somewhat resembling the letter U, while others
have more of the V form from the keel to round of bilge. It is
very evident, if the length, breadth, and depth of vessel be the same
in each case, and each have the best form of water line, that the
V form will require less sails than vessels having a full midship
section resembling the letter U. The midship section is the area to
be driven through the water, and the sails are the power, conse-
quently the vessel having less area and carrying power will attain
a greater speed than a fuller vessel having more carrying power,
the parallelogram of construction being identical; but it must be
borne in mind that with the same midship section a variety of ships
can be constructed, totally differing from one another.
This brings us to consider what is the best form of water line.
According to some, it is a wave line; the greatest breadth, or
what is technically termed the midship section, as deduced from
this theory, should be placed nearer the stern than the bow of
the vessel, in the proportion of 4 to 6. Present practice, how-
ever, cannot be said to follow out the wave-line theory. The
water line on the sheer plan, and the centre line of the vessel
774
MODERN STEAM PRACTICE.
on the half plan, is divided into ten equal parts; perpendiculars
are raised at each end and at the points of division; four of these
parts are the after body and six the fore body. The fourth point.
from the stern we will term the midship offset, and here a circle is
described touching the centre line of the vessel and the greatest
Figs. 551, 552, 553. - The "Wave-line" Principle of Construction.
SHEER
PLAN
WAVE
LINE
PLAN
BODY
breadth on the load water line, as
taken from the midship section. The
half circumference looking forward is
divided into as many parts as the fore-
body line contains offsets, which may
be any number. Lines are then to be
drawn parallel to the centre line of the
ship through these points cutting each
offset. Commencing at the centre line,
the first division gives the breadth of
the first offset from the stern, and so
on working to the midship offset, which


B
A, Fore body. B, After body.
is represented by the
total diameter of the
circle of delineation; the
same process is carried
out for the after body.
Thus a curved line em-
bracing all these points
is termed the true wave
line by its inventor (the
late J. Scott Russell). This line gives
the greatest speed which a given length
between the perpendiculars will admit
of. It is found in practice that this
line must be modified to suit the thick-
ness of the stem and stern posts. This
is done by drawing the line a little
longer, and cutting off the extra length; thus the curve at the bow
works into the thickness allowed for the stem. No such nicety
being required at the stern, it is found by simply increasing the
breadth of the line to suit the thickness of the stern post. Thus
all the other lines of configuration can be found in like manner.
The immersed body is thus deduced from a circle, placed four-tenths
from the stern of the vessel on the load water line, being divided

IRON SHIPBUILDING.
775
into as many parts as there are offsets contained in that line- a
simple geometrical figure that may be considered perfection by
some, but we are afraid the generality of shipbuilders will not
wholly agree to this form of construction. However, we rest con-
tented that those who construct vessels on this principle will not
greatly err; that is to say, if the top part of the ship is so formed
as to give the least resistance, and greatest safety in emergencies.
All ships should be so constructed as to give the best immersed
body for speed and carrying power according to the requirements;
the top part of the vessel should be so formed as to subdue the
enormous force of storm waves in a gradual manner, so as not to
impede the vessel with an abrupt entrance, while the forward lines
should not be so fine as to cut through the waves and drown the
ship. The vessel should meet the waves easily, and by gently
cleaving them at the bow gradually lay them aside, with a gradual
tumbling out of the upper body of the vessel above the line of
flotation; we thus reduce the force of the waves to the mini-
mum.
We now come to consider the form of vessel at the midship
section to suit the wave-line construction. With a parallel wall-
sided midship section, and a flat floor, it is evident that the half
breadths are the same for the various water lines, at say I foot
apart; the semicircles of construction, therefore, for all these water
lines will have the same diameters; and as, if the stem and stern
posts are carried up perpendicular from the keel, the length of
vessel remains the same on all the water lines, therefore the water
lines for the vertical and parallel part will be identical; that is to
say, if all the water lines are to be constructed on the wave-line
principle, a wall-sided structure from stem to stern. Thus it
will be seen that the midship section plays an important part in
the formation of wave lines. As the various water lines run into a
perpendicular stem post, in we may say all vessels, with a wall-sided
midship section, the water lines would thus be identical; but were
the stem to be cut away, or rather the fore foot of the vessel sloping
up from the keel, then we would have different curves, constructed
from the same diameter of circle, owing to the difference of the
length of the various water lines. However, it is possible with
perpendicular stem and stern posts and wall-sided midship sections
to construct a certain length fuller, and add a fine wave bow ac-
cording to the wave principle, even with the floor quite flat amid-
776
MODERN STEAM PRACTICE.
ships, the point where the lines join at the bottom of the vessel
being suddenly rounded the one into the other; such vessels have
been constructed, giving great carrying power, combined with very
fine fore-and-aft lines of entrance and exit for the water.
The elliptical midship section is best calculated to form a hand-
some geometrical immersed body, as each line of flotation varies in
breadth; thus the load water line has its circle of construction, the
next water line its circle, and so on until each water line is delin-
eated.
With a certain length, breadth, and depth it is very evident that
a full midship section will produce a very different vessel from one.
with a handsome elliptical section; but it is clear that the naval
architect must form the immersed body according to the weights to
be carried; he must therefore adopt a form of midship section to
suit these weights, combined with the best form of water line
obtainable by this mode of construction. The displacement must
be equal to the weight of the vessel, machinery, and carrying power
required, and in fact the wave-line principle must have a certain
form of midship section to carry out the principle fully; therefore
it cannot be universally adopted unless, as in other modes of con-
struction, we were to adopt a variety of wave lines by joining, as
before stated, a fine wave bow with a flat bottom midship section.
A vessel of great carrying power, amalgamating as it were any
form of midship section with the wave-line principle, may be thus
designed. Vessels of the wave-line type of the same length, breadth,
and depth will of course vary in carrying power, just as in the ordi-
nary mode of construction.
The sheer line of the vessel should be curved according to the
wave-line theory, the top of the bulwarks for vessels of 200 feet in
length at the fore part may be raised 2 feet 6 inches, and the after
part 9 inches higher than at the midship section, placed four-tenths.
from the stern; however, the curve embracing these points is, we
may say, a matter of taste; a certain amount of curve must be
given, otherwise the vessel would have a hogged appearance.
We now come to consider the buttock lines of the ship. These are
lines which would be formed on the outside of the vessel by vertical
planes cutting the vessel longitudinally and parallel to a main ver-
tical plane in the line of the keel. A line midway between the keel
line and side of the vessel may be termed the chief buttock line,
a curved line commencing at the lower part of the vessel, and
IRON SHIPBUILDING.
777
ending at the top both fore and aft. If the fore part of the vessel
at the deck line tumbles in, the curve of the buttock line at the top
part of the vessel is rounded inwards, and when a proper amount
of flare or overhang of deck line is given, then the chief buttock line
has a regular curve, following the form of the immersed body, so
that we may imagine the water is sucked under the vessel in a
gradual manner; were the bow formed bluff, the buttock lines would
appear quite full. An experienced naval architect can at once detect
the sea-going qualities of a ship by inspecting the chief buttock line;
if it flares much at the top, then we have great overhang, which is
not at all to be desired when the vessel is plunging through a sea-
way; if the buttock line has a bold appearance, and is delineated quite
full, then he knows such a vessel is not calculated for speed, but,
bruising the waves, will be obstructed in its passage through them.
But when the buttock line assumes a nice regular curve from the
bottom upwards, then we have all the qualities to be desired in a
speedy and safe sea-going vessel. It is necessary that the fore and
after buttock lines should harmonize, so that the configuration of
the vessel may be most pleasing to the eye, for, if these buttock
lines are distorted, we may rest assured that the vessel is likewise so;
in fact, the object of placing these sectional lines on the drawing is
to check or keep fair the half-breadth and body plans.
If
When the frames or body plan is drawn, set off a perpendicular
line on each half plan equidistant from the centre line and the side
of the vessel at the greatest breadth, and all the heights of the
various frames that are cut by this line are projected on the sheer
elevation at the respective ordinates, then by bending a thin strip of
wood to these points, we obtain the buttock line at that part.
this line is not a fair curve, then the frame or section of the vessel
at that part must be made fuller or flatter as occasion may require.
It will thus be seen that the naval architect is greatly guided by
his eye, as all artists are, in designing his structures scientifically, as
well as making them conform to the true lines of grace and beauty.
In arranging the internal parts of a ship, it is not absolutely
necessary that the decks should follow the sheer of the vessel; for
if more room is required than what the sheer will allow, then the
decks can be made quite level; this may be more needed in the fore
part of the ship, so as to secure ample accommodation in the fore-
castle. Some prefer a large roomy deck, while others take advan-
tage of the space by constructing deck-house accommodation. The
778
MODERN STEAM PRACTICE.
fore part of all vessels should be covered over, so as to keep the
vessel dry and comfortable, and form a roomy forecastle for the
crew. The deck should not be hampered with deck houses running
the entire length of the vessel; but still a hurricane deck fitted
on to the top may be of advantage in manipulating the sails, and
many Atlantic and other ocean steamships have this construction.
The main deck in small vessels is the upper deck; but in large
ships a spar deck is above it. Sometimes there are three decks
placed above the main deck. As a rule the main deck is placed
about one-ninth of the breadth or beam of vessel above the
load-water line of deepest immersion. The main deck must follow
the configuration of the ship; it must neither be too full nor too
fine. The safety of the ship depends on arriving at a good
mean, and as this safety is of the highest importance, it is a point
which must command our first attention; it will then be found if
there is room enough and to spare for the internal arrangements of
the vessel. In such vessels as the Great Eastern there are four
decks above and four decks below the main deck.-We have thus
noticed the principal points requiring attention in designing vessels.
CONSTRUCTION AND USE OF MODELS.
We will now proceed with the construction of the model, so as to
give a better idea of the external appearance of the ship. The scale
generally adopted is 4 inch to the foot. Pine wood should be used,
quite free from knots. The block of wood should be jointed at the
load water line; a thin piece of paper glued to the adjoining sur-
faces of such portion with very thin glue will answer better than
pins, as will be seen hereafter. The object of the model is not
merely to set before the eye the ship in miniature, so that the
owners and designer may have a better notion what the full-sized
ship will be like; but it can also be used to check the calculations,
although we do not attach much importance to this use of it, which
affords a practical test that requires much care in carrying out pro-
perly to be of value. The model of half the vessel is made to the
drawing exactly, either by forming each foot of depth per scale or
water line separately as taken from the half-breadth plan, and then
jointing it correctly together, or taking a plain block of wood the
length, breadth, and depth of the vessel as per scale, and then model-
ling the block with moulds fitted to the various sections so as to make
IRON SHIPBUILDING.
779
the model an exact representation of the drawing. The model being
completed, the joint at the line of flotation can be separated by
forcing the thin edge of a chisel all round, and by using a little force,
or tapping the chisel with a mallet, the paper that was inserted will
be split in two; thus the model is split into two parts, the bottom
portion representing the immersed body. To find its cubical contents,
plane a cube of wood taken from the same plank as the model is made
of—it should be entirely free from knots-making the block a little
heavier than the immersed portion or bottom half of the model, and
then planing it down until the block and the model are exactly of
the same weight when placed on a pair of nicely-balanced scales;
then by measuring the block per scale of the model, the number of
cubic feet in the immersed portion will be readily ascertained. As
each cubic foot in the block represents a cubic foot in the model,
the quality and weight of the wood being identical in each, whatever
displacement in cubic feet the one has, so must the other: this is a
very good practical test of the displacement of the ship at the load
water line. However, we by no means advocate this mode of finding
the displacement of a ship, as the intelligent naval architect will always
prefer the usual mode of calculation to such a rude process. Again,
the centre of gravity of the immersed body can be found approxi-
mately by suspending the model alternately at each top corner, at
the same time allowing a weighted cord attached to the points of
suspension to cross the plain surface of the half model, or that sur-
face which represents the central longitudinal section of the vessel;
the point in common where the cord crosses on each occasion will
be approximately the centre of gravity of the immersed body. A
vertical line drawn up from the keel through this point will be the
vertical centre line of displacement, and it is evident that the lon-
gitudinal centre line of the vessel must intersect this line; thus all
the calculations can be checked approximately by the use of the
model. However, the most practical use of the model has nothing
whatever to do in checking calculations; we merely mention that it
is the practice of some to make use of this method as a rough and
ready plan when preparing the design; its general application in
the shipbuilding yard is in setting off all frames and strakes or
ranges of plating, as regards the length, breadth, and butts, in order
to ascertain their correct proportions. When the model is divided
into the number of strakes required, a thin strip of wood, or flexible
ruler as it were, having the edges quite straight, is pinned to the
780
MODERN STEAM PRACTICE.
block at the different points with common pins, so that the different
lines of plating can be accurately marked. The frames are divided
on the line of the keel, then squared up the plain side of the model,
and then across to the top of the bulwarks, when by bending a thin
strip of wood from top to bottom, the frames can be lined off; or
another method is to lay the half model on a table on the flat side,
and move a square block of wood along the line of keel to the various
points, running down the side of the block with a flat-sided pencil,
when the point bearing on the model will mark the vertical accurately.
Thus when all the frames, plating, side lights, &c., are marked on
the model, as likewise the position of the water-tight bulkheads, the
model then faithfully delineates the full-sized ship. The workmen
can at once see the nature of the work, what plates require to be
bent warm, and those that do not; the position of all the butt strips,
bulkheads, &c., in fact, from the beginning of laying down the keel
to the finishing of the vessel, the model is constantly referred to. All
the plates are numbered on the model, and there are corresponding
numbers on the invoiced iron, so that, by arranging the plates in the
yard according to the numbers, the workmen can at once select the
frames and plates that are required.
FULL-SIZE LINES IN THE MOULDING LOFT.
The next process in the workshop is laying down the lines full
size on the floor of the moulding loft. This loft is a long room
sufficient to take on the half-length of the largest vessel. The
floor is blacked over with lamp black and size; the sheer and half-
breadth plans (Figs. 554, 555) are laid down on the floor, and the
body plan (Fig. 556) is drawn on a separate board, blacked over;
the lines of the frames are marked with French chalk, a flexible
batten bent round to the various offsets being used, held in position.
by strong wrought-iron pins having flat heads, so that they can be
easily withdrawn out of the board. After the body lines showing
the configuration of the frames are completed, the lines are cut into
the wood with a scriber, thus a permanent drawing is made for the
workman, so that the frames can be accurately bent to the drawing
and cut off to the finished lengths without the use of wooden
templates made to the required form for each frame.
The method adopted, however, varies in different districts. On the
Clyde, for example, the practice is to run fewer water lines and but-
tock lines than are shown in Figs. 554-556, but to depend more on
IRON SHIPBUILDING.
781
112
104
74 B
12
B
Sheer and Half-breadth Plans.
96
88
80
72
64
56
48
40
24
16
8
WL
712
96
56
كة
32-24
Figs. 554, 555, 556.-Lines of a Screw Steam Ship.
WL, Water lines. BB, Buttock lines.
воро
14 B
B
16
32
48
66
64
72
80
96
16
B
B
21
B
104
TR
Bubrark Roar
B
A

Body Plan.
A, Fore body. B, After body.

Gurowale Moulding
48
72
80
88
96
704
T16
120

782
MODERN STEAM PRACTICE.
ribband lines. These would be represented on the body plan by
diagonal lines starting from points on the greatest section about
4 feet apart, and drawn square off the sections to the centre line.
The frames are lifted from these lines in the loft and scrieved on
the boards at the furnaces with the knife without being first drawn
in with chalk. The ribband line, standing square off the average
section, is found to be more suitable for fairing the frames than
either the water line or buttock line.
EXPERIMENTAL MODELS AND SPEED TRIALS.
By the use of models made of solid paraffin the late Mr. Wm.
Froude of Torquay obtained much valuable information regarding
the probable behaviour of the vessels which the models represented.
A tank was prepared 270 ft. long by 40 ft. broad and 10 ft. deep,
and suitable mechanism arranged for the motion of the models.
These latter varied in size from 6 ft. to 20 ft. When experiment-
ing on surface friction the value determined by Mr. Froude appears.
to have been 6 lb. per square foot of a surface 120 ft. long, at a
speed of 10 knots.
1
25
From these experiments a "law of comparison" was found, by
which the performance of the model and ship could be properly
compared, so that say with a model of the length of the ship, the
comparative speeds for resistance would be as follows:-Ship
5 knots, model I knot; ship 10 knots, model 2 knots; ship 15 knots,
model 3 knots.
The various elements of ship resistance have been ably investi-
gated by Mr. Froude, the three principal being: frictional resistance
of the skin of the ship, eddy resistance, and wave-making resistance.
The first is the most important in a well formed ship, and appears
to vary as the 1.87th power of the speed. The horse power he found
to be in general about 2'7 times less the indicated or effective power
expended by the engines;—this loss of power being due to the fric-
tional resistance of the machinery, the friction of the screw itself in
the water, and a resistance due to negative pressure at the stern
arising from the thrust of the screw.
In speaking of ship resistance the late Professor Macquorn
Rankine says: "The coefficient of friction between water and the
bottom of an iron ship is nearly the same with that of water in iron
pipes. The friction varies nearly as the square of the velocity of
rubbing between the water and the ship's bottom;" and he gives as the
IRON SHIPBUILDING.
783
2g
value of the resistance R=LG (1 +45²+s¹), where G is the
mean immersed girth; L, the length on the water line; s² the mean
of the squares of the sines of the angles of obliquity of the stream
lines, or lines which the particles of water follow in gliding over the
ship's bottom; v, the velocity of the ship in feet per second; and ƒ,
a coefficient having a value for clean-painted bottoms of ‘004.
The part of the above formula denoted by LG(1+4s²+s¹) is
what Rankine called the augmented surface.
Of late years important information has been obtained as to the
law of power and speed in steam vessels, and this largely through
the system of progressive speed trials introduced by Mr. Wm. Denny
of Dumbarton; and Mr. R. Mansel in various papers has investi-
gated mathematically the relations so found, which he states as
follows:-"In a given steam vessel under experiment, if we carefully
measure various rates of development of the power, and note for
each the corresponding rate of speed of the vessel; the normal law
of the relation of these elements, power and speed, can be stated
thus: The logarithms of the ratio of the power to the speed, drawn
as ordinates, to the speed laid off as abscissas, will range in a straight
line inclined to the axis: or, otherwise, at any speed; the logarithm
of the power for each unit of speed is equal to the product of the
speed by a factor, constant for the vessel, added to a logarithmic
quantity, also constant for that vessel. Denoting these constants
by the symbols a and log. b respectively; and if, as is usual, we
measure the power by E its rate of development in indicated horses,
and the speed by V, the rate in nautical miles per hour, either of
the foregoing statements written as a formula gives:
E
Log. V = aV + log. b.………………..
(1)"
H.M.S. "SHAH."
Number of
Speed.
Gross indicated
Experiments.
Nautical miles.
horse-power.
I.......
5°32
II.....
8.01
318
772
Revolution of
engine-shaft.
20'II
29.71
Piston
pressures-lbs.
6:07
9'97
III....
12.13
2,506
45'43
21.17
IV.......
...... 16:45
7,477
65°35
•
43'90
S.S. "MERKARA.”
I........
6.20
299
31'15
22.79
II. ...
9'20
718
44'75
·
38.12
III.
11.09
1,225
54'35
53'55
IV.......
12.91
1,948
63°23
73.30
784
MODERN STEAM PRACTICE.
Construction (refer to Fig. 557).—Draw a straight line OX as
speed axis, and with a convenient scale of equal parts lay off from
O, as origin, the respective trial speeds; at each of which measure up-
wards the difference of the logarithms of the corresponding power

"Shah'' Power Normal values Log.
E
"Merkara" do.
do.
do.
do.
-0.
Speed Axis
1 S
IIIS
III S
IVS
IM
II M
111 M
IV M
"Shah" Log (P+P})
"Shah"Revolution Normal.values Log. T
"Merkara'' do.
-do.
do. do.
"Merkara" Pressure Normal values Log (Prp)
1
7
6
.5
.4
.3
.2
.1
2.0 Log.100
.9
.8
.7
X
4
.3
.2
.7
1.0 Log. 10
.9
8
7
6
5
1234 L
Logarithmic Scale.
6
E
7
8
.9
1.0 Log.10
1
.2
3
.5
67
Note. Observation Values indicated by centres of small circles.
.8
.9
2.0 Log.100
0
1
2
3
4
5
6 7 8 9 10 11
Scale of Nautical Miles.
12 13 14 16 16 17
Fig. 557.
and speed. We at once perceive straight lines can be drawn which
will pass through the respective set of points with a degree of
accuracy which is surprising, when we consider not only have we
many data, in which slight errors of observation will affect the
result, but, in addition, we have irregular action of winds and cur-
rents, of which we have neither proper means of detection nor mode
of estimating their effect. Having drawn these lines, representing
the normal law, their relation to the formula (1) is easily deter-
mined. According to
According to the first application of the principles of
IRON SHIPBUILDING.
785
co-ordinate geometry, we know a to be the natural tangent of the
angle which a line thus drawn makes with the axis, and log. b the
perpendicular distance OA, of this line from the origin. These con-
stants being either directly measured or calculated, by the normal
law (1) we at once obtain the law of the power for the particular
vessel, equally represented by
E=bV 10ªV…..
(2).
E=bV Log. -¹aV. The term Log. -¹aV being read, the number whose common
logarithm is the product aV.
In the Shah the values of 6 and a are 22:29 and 0796 respectively,
and in the Merkara similarly, 169 and 0735 respectively; hence,
for the Shah the equation E=22′29.V.10796V and for the Merkara the
equation E=16′9. V. 100735V will give the relation between the power
and speed with the same fidelity as points in the straight line
represent points in the same ordinate determined from observa-
tion. Where they do not agree the question arises, Is this differ-
ence due to observation? Does it arise from an alteration in the
circumstances of trial, in this way forcing itself on our notice, but
not inconsistent with the normal law; or is it a well-defined departure
from the normal law requiring to be recognized and referred to a
higher law? These are questions of some importance and intricacy."
BUILDING OF IRON VESSELS.
THE HULL.
Quality and strength of material.-In all iron ships the materials
must be of the first quality and the workmanship excellent. All
the plates should be stamped with the manufacturer's name, and
be proved in the testing machine. When this is attended to, the
shipbuilder may rest satisfied that the iron he employs will be
capable of bearing a tensional stress of 20 tons per square inch
with, and 18 tons across the grain, a strength that may be de-
manded. For steel plates some have gone so far as to advocate
that a portion of each plate should be tested by taking a piece
sheared off and doubling it up cold, and should it not bear this
severe test without being impaired that it should be rejected. With
such precautions we may feel secure as regards the strength of the
50
786
MODERN STEAM PRACTICE.
material; and with the structure properly designed and first-class
workmanship, both the owners and the builders of the ship should
feel satisfied.
Marine insurance companies have rules for the guidance of the
shipbuilder, and any improvement which the latter may introduce
must of course be submitted for approval. Thus the rules for
the guidance of shipbuilders are established upon those modes
of construction which experience has shown to be of the greatest
advantage.
FRAMING, &C.—Keels and keelsons.—Hollow iron keels were much
used at one time, and were chiefly introduced, in very flat vessels,
to form a channel for the bilge water, as the pumps were thus enabled
to draw off the water more effectually from the ship. These keels
should be rolled in as long lengths as practicable, and the different
lengths welded together, or the butts should be strapped and treble
rivetted; the channel should also be cemented up and over the rivet
heads, thus forming a clear trough from stem to stern. Hollow keels
may be made in a variety of sections. In some cases they have been
filled with wood, while in others the builders ran the garboard or
bottom strake of plates across the hollow, thus forming an external
channel as security to the ship, but the rapid corrosion that set in
rendered the repairs both difficult and expensive. Moreover the
channel for the bilge water is thus destroyed, which was one of the
primary uses of the hollow keel. In another form, with the garboard
strake running across, the keel is formed of two side plates with inside
angle irons, and a bottom plate with outside angle irons, there being
a box keel formed of three vertical plates worked on the inside and
top of the garboard strake, to which it is united with angle irons,
the rivets passing through the garboard strake, and angle irons con-
necting the outside keel therewith. The inside keel may be carried
above the floor plates or on a level with the top, with suitable
covering plates and angle irons running the entire length of the
vessel, the floor plates abutting against the sides of the box keel.
It is evident that the outside keel in this arrangement may be
partially destroyed or parts torn away without causing any leakage
into the ship, but otherwise the plan is complicated, and has not
found much favour with shipbuilders.
We next notice the solid bar keel, formed of a plain bar to receive
the garboard strakes of plates. The rivets passing through the ver-
tical flanges, and through the angle irons of the frames in the
IRON SHIPBUILDING.
787
horizontal seams of rivets, formed the only connection between the
ship and the keel. Vessels so constructed strained very much in
the garboard strakes when the ship was docked or went on shore.
Sometimes the keel was partly rabbeted on each side to receive the
garboard strakes of plates, which finished flush with the keel plate.
By this means the strain came on the edges of the plates, throwing
less stress on the rivets. This plan, however, was rather expensive
and not wholly satisfactory.
Other keels are formed of plates rivetted together. It is obvious
when the keel is formed of a series of plates, three or more in num-
ber, there are just so many joints to keep tight. With three thick-
nesses, along with the hull plates, there are four joints, while with
the solid bar keel there are only two. Considering the difficulty of
getting all the holes fair in a series of plates (the holes requiring to
be broached to make them fair, as has at times to be done even
with the best workmanship), it appears that that mode of construc-
tion which requires the fewest joints is by far the most preferable.
The benefit of hav-

ing the keel formed
of one plate there-
fore becomes appa-
rent. After a vessel
has been subjected
to severe stress in
rough weather, her
keel, if formed with
a number of plates,
begins to work loose,
and great leakage
must take place.
Again, it is necessary

C
Fig. 558.-Groove for Centre
Keelson. A, Keel. B, Groove.
c, Garboard strake. D, Centre
Keelson,
C
Fig. 559.-Centre Keelson rab-
beted on to Keel. A, Keel. B,
Rabbet. c, Garboard strake.
D, Centre Keelson.
In some cases the piece D is carried to the bottom of a, which latter
becomes two separate plates.
to make a good fit of the keel plates, which can only be done by
planing the whole surface, thus making the keel bars quite
smooth.
Notwithstanding all precautions it soon became apparent that
a stronger form of keel was necessary. This was effected by
uniting the keelsons, which are structures of plates and angle
irons running longitudinally along the bottom of the vessel,
through, between, or upon the floor plates according to the con-
struction. By the aid of the planing machine the difficulties of
788
MODERN STEAM PRACTICE.
uniting the centre mode of keelson in a strong and substantial
manner to the keel are overcome, thus securing a great source of
strength absolutely needed for long vessels. This is done in a
variety of ways. One plan is to groove out the solid bar keel for
the reception of the centre keelson, to which it is securely fastened
by rivets passing through and through; another method is by
rabbeting the top part of the keel and rivetting the keelson thereto.
The latter method makes a first-class piece of work. In some cases
the rabbet is planed out the thickness of the keelson, which is finished
flush with the side of the keel; while in others the rabbet is dis-
pensed with, the keelson plate being lapped upon the keel. In both
of these examples the keelson is not in the centre line of the vessel,
but practically this is not considered of much moment.
The keel bars are ordered in suitable lengths, and are planed at
the ends for scarphing; the length of the scarph should not be less
than nine times the thickness of the bar, and even more than this
may be adopted in practice. The stem at its lower part is to be
the same moulding as the keel, and attached to it by a scarph of

A
B

Fig. 560.-Scarph for Keel.
A, Keel. B, Scarph.
the same length as the keel scarph, and may taper from the load
line to the head, where it may be three-fourths of the sectional
area of the stem.
The stern and propeller posts and after end of keel, for single
screw-propelled vessels, should be double the thickness, or twice
the sectional area, prescribed for stern posts, the portion adjoining
the keel being tapered fair into it. The portion of the forging of the
stern frame, forming part of the keel in screw-propelled vessels,
should extend sufficiently forward for the after end of its scarph, at
least twice and a half the frame space before the stern post.
IRON SHIPBUILDING.
789
When the garboard strakes are thicker than required by "Lloyd's
Rules," the thickness of the keel may be proportionally reduced.
When the keel and keelsons are formed of several thicknesses of
plates, the combined thickness should be the same as for a solid bar
keel, and the butts of the several plates made to break band in a care-
ful manner, and differ from the butts of the garboard strakes, which
in all cases must break band so as not to have the joints opposite.
The dimensions of all forms of keels should be in accordance
with the rules laid down, as given by the registries of shipping.
In fact, all the dimensions for the guidance of shipbuilders are in
accordance with these rules, being the combined experience of the
most eminent practical shipbuilders; and though we may look for
slight alterations from time to time, we may expect that such will
not materially affect the present mode of fastening.-The use of
steel for shipbuilding has necessitated a new series of rules and
scantlings, as the material being stronger for the same weight enables
a considerable reduction to be allowed in the sizes as formerly in
use for iron.
In marking off the holes for the keel bar, the top rows should be
no farther down from the top of the keel than will make a good fit
for the garboard strake, and at the same time care must be taken
that the lower holes in the keel bar are not placed too far down,
thus weakening the keel; the vertical distance between the holes
from centre to centre, or rather between the centre lines, should be
equal to two diameters of the rivets, and great care must be taken
to have them properly divided.
In drilling the scarphs the ends should be brought closely to-
gether; three holes should be drilled on the top edge of the keel for
stitching. The upper part of the scarph should be caulked before
the frames are placed in position, and the position of the frames
marked on the keel, this saving much trouble in framing the vessel.
The keel bars must be laid quite straight and fair before the
frames are placed on, and before any of the plating is placed on
care must be taken to fair the keel fore and aft with a line.
The stern posts of screw vessels are generally solid forgings, the
body or fore stern post being formed so as to take the end of the
tube through which the shaft passes for the propeller. The after
stern post has a provision forged on for taking the short tube for
supporting the end of the shaft. These holes in the fore and aft
stern posts are accurately bored out in position for receiving the
790
MODERN STEAM PRACTICE.
tubes. The after stern post has likewise the step at bottom, and
the lugs for the pintles of the rudder forged on; the latter, however,
are sometimes dispensed with, when the rudder is secured with
separate straps embracing the after stern post, to which they are
rivetted. There are various forms of screw aperture. The bottom
in a line with the keel has bold curves, thus affording great strength
in the frame, the part joining the keel being of sufficient length to
form a proper scarph. The contour of the top of the frame is made
square, half round, or elliptical, and
in some ships the top member slopes
from the fore stern post up towards
the after stern post, the latter being


E
F
A
D
A
B
C
Ꭰ Ꭱ
Fig. 561.-Solid Stern Posts and Rudder.
A, Inside stern post, B, Outside stern post. cc, Pins.
D, Pintle. E, Rudder, F, Rudder head.
Fig-562. Screw Aperture in two pieces.
A, Inside stern post. B, Rudder post.
c, Foot on keel. D, Scarph.
carried up a considerable way inboard.
The boss on the fore
stern post where the tube passes through projects from the post
fore and aft. This arrangement is generally adopted when the
screw propeller is overhung, thus giving ample bearing for sup-
porting the weight of the propeller; but when the shaft is sup-
ported with an additional outside bearing on the after stern post,
IRON SHIPBUILDING.
791
the fore one is generally flush on the outside, the after post
being quite parallel throughout, but at times, when the propeller
shaft is supported with an outside bearing, projections are formed
on the fore and aft stern posts. The plating of the ship in con-
nection with the stern post should be arranged in the strongest
manner. When the top of the frame is formed half round, elliptical,
or of a square form, it gives a better bond than when the stern post
top member slopes up aft from the forward stern post, although
with the latter arrangement the water gets away more freely; but
strength in this important part of the vessel is the first consider-
ation, more especially when we take into account the great weight
of these forgings, which in ordinary ocean steamers for the mercan-
tile marine is about 20 tons. The front post and the keel piece are
forged in one, and the rudder post, along with the lugs for the
rudder, forged separately, with a dove-tailed foot for securing with
rivets to the keel, which is made flat, for the double purpose of
stiffening the frame and keeping the screw propeller as low as
possible; the top member being scarphed and secured with a key.
Cast steel stern frames are now being made.
The stern post, after it comes from the forge, should be carefully
inspected, and any twist that may be in the frame taken out, and
it would be seen that the bosses are in line with each other fore
and aft. It is customary to make the scarph for the stern post on
the port side, and in ordering the stern post from a forge at a
distance it would be well to have the part joining on to the
keel of a convenient length, otherwise it may cause trouble in
transit, more especially if conveyed by railway.
The holes around the boss for the plating should be all bored be-
fore the stern post is placed in position; in putting in the rivets they
should be cooled at the points, as in this way the heads can be well
tightened up, and it is necessary to countersink the holes a sufficient
depth, so that the rivets may hold good; the stern post is then bored
out for the reception of the propeller or stern tube. The counter-
sinking should be sufficient to allow of a part to be taken off if
necessary while boring, in case the line of centre should not be quite
In some cases the plates are tap-rivetted from the outside.
The rudder trunk can be secured with two rows of rivets, although
some prefer one row as quite sufficient; and it is as well to arrange
the plating of the vessel, so that one strake covers the stern-tube
boss entire, thus much trouble is saved and a better finish obtained.
true.
792
MODERN STEAM PRACTICE.
When vessels are designed for services where the draught of
water is limited, a hanging keel is sometimes dispensed with, and
the centre keelson is carried down with two angle irons on its lower
Section through a b.
a
O
0
•
D
O
O
O
O
O
O
O
•
O
0
0
❤
•
O
о
O
O
→
C
B
O
O
O
D
B
C⚫
O
•
O
0
00
0
D
O
O
O
O
•
20
O
•
O
O
Fig. 562A.-Details of joining Plate Keel to the forged Stem Frame.
edge connecting it to a
flat plate, and takes the
place of a keel. A very
strong keel is thus
formed, but it is diffi-
cult to make a suffi-
ciently strong connec-
tion between the forged
stem and stern post
and this built-up form
of keel. In small ves-
sels it is usual to weld
on plates, bent into a
V shape, to the forg-
ings, and then connect
the end keel plates to
the v-shaped plates by
butt straps. In large
vessels, however, it is
considered to be risky
to weld a rolled plate
a forging, and the
forging is then gener-
ally lengthened and
increased in thickness
until it takes the form
of the vessel, and per-
mits the keel plates to
be fitted round it.

to
The necessity, how-
ever, of making the
connection to the forg-
ing by means of very
long rivets, or by tapped rivets, and the difficulty of scarphing the
keelson over the butt joint efficiently, are two very great objections
to this plan when the forgings are of large size.
In Figs. 562A and 562B are given the details of the connections
IRON SHIPBUILDING.
793
of the plate keel and keelson to the forgings in the screw steamer
Aberdeen, a vessel of 3600
tons, recently built at Glas-
gow by Messrs. R. Napier
& Sons, in which the diffi-
culties pointed out were
overcome by machining out
the solid forging itself to a
U section, and thus enabling
rivets of moderate length to
be used. In Fig. 562 A the
form of the stem forging
and the method of making
the connections are shown
at the respective parts by
the cross sections drawn
above each. An ordinary
scarph is made at A to
shorten the machined part
of the forging; B is its after
end; C is the termination
of the centre keelson; and
D the fore end of the check
to receive the flat keel
plate.
In Fig. 562B is shown the
method of connecting the
stern frame to the keel.
Here again the forging is
widened and hollowed out.
E is the fore end of the
forging, F the after end of
the vertical keel plate or
central keelson, and G is
the after end of the flat
keel plate where it is checked.
into and wrapped round the
forging. The cross sections
as in the preceding figure

O
•
O
•
O
o
E
F
•
о
O
O
•
•
0
D
•
.
G
•
E
O
O
•
O
O
•
O
O
O
O
O
О
O
O
•
•
0
Fig. 562 B.-Details of joining Plate Keel to the forged Stern Frame,
show the form of the forging at the parts underneath each section.
794
MODERN STEAM PRACTICE.
The stems are bent to a template adjusted for the inside of the
stem, and should be taken out of twist and the fore part forged to
a flat-curved shape, and it is generally the practice to adjust the
length of the ship by increasing or diminishing the length of the
part fitted to the keel; all the holes that are required should be
bored, as likewise the scarphs fitted after the stem bar is quite fair.
It is customary now in a large ship to make the butt of stem and
stern post solid and put in tapped rivets.
In the usual mode of framing vessels the framing consists of the

M
L
I
K
H
F
E
E
D
Н
B
A
D
Fig. 563.-Half Midship Section of the Arrangement of
Framing, &c., for a Vessel of 200 tons.
A, Keel. B, Floor. c, Centre-plate keelson. D, Pillar.
D, Pillar. E, Bilge
keelson. F, Hold stringer. G, Frames and plating. н, Deck.
1, Deck stringer. K, Bulwark or top side.
A, Keel.
stringer.
Fig. 564.-Half Midship Section of the Arrangement of
Framing, &c., for a Vessel of 800 tons.
B, Floor. c, Centre-box keelson. D, Bilge keelson. E, Hold
F, Lower deck. G, Lower-deck beam. H, Lower-deck
stringer. 1, Upper deck. K, Upper-deck stringer. L, Bulwark. M,
Frames and plating.
C
B
A
frame angle iron, the floor plate, and the reverse frame. The frame
angle irons should be ordered in as long lengths as possible, and
IRON SHIPBUILDING.
795
when necessary should be welded or scarphed to each other, care to
be taken that the welds or scarphs shift or break bond with the
adjacent frames. The frames are fitted close on to the upper edge
of the keel; and at the extreme ends of the vessel the lower parts
of the frames opposite to each other are to be lapped and rivetted.
together, and in all vessels to extend to the gunwale. Where either
raised quarter decks, poops, or forecastles are constructed, the frames
are to extend to their deck stringers respectively, except when the
vessel is of a rounded form at the gunwale; they may then terminate
at the lower edge of the curve. When the frames are butted on the
keel (except when centre through-plate keels are adopted) they are
not to have less than 3-feet lengths of corresponding angle iron,
fitted back to back, to cover and support the butts, and receive the
plating for at least three-fourths the vessel's length amidships.
Similar pieces of angle iron are to be fitted, if the frames are
butted elsewhere.
The rivet holes in the frames must be properly divided prior
to punching; for single-rivetted laps, the lap being 234 inches broad,
the holes on each side of the lap may be 5½ inches from the centre
of the lap for 3/4-inch rivets, and the holes between the laps spaced
about eight diameters; for double laps of plating, from the centre
of lap to the hole in frame above the lap, may be 6½ inches to
centre, and the hole below the lap may be 534 inches from centre
of lap, and the holes between the laps on frame spaced eight dia-
meters as nearly as possible.
The heels of frames bearing over the keel should be nicely fitted,
butting closely together, and within the limits of the width of the
keel, but having a full bearing and fair with the keel, otherwise
secure work with the garboard strakes will not be made; those
frames resting on the stem and stern posts must likewise be care-
fully fitted, having a full bearing. The inside flange of the frame
must be punched to suit the size of the reverse angle-iron frames,
the rivets passing through the centre of the angle iron. In frames
that form the sides of the poop, forecastle, and bridge, those which
have no beams fitted on them should be cut to such a height as will
allow the lug pieces which secure the stringer plate to the shell or
plating to pass from beam to beam. The spacing of the frames.
from centre to centre to range from 20 to 24 inches according to
the size of the vessel.
The floor plates to be in size according to the rules at the middle
796
MODERN STEAM PRACTICE.
boilers, where they must be
16
6
line for half the length amidships, excepting under the engines and
inch thicker, when the thickness pre-
scribed is inch or under. They should be moulded not less than
one-half their midship depth at the distance of three quarters the
half breadth of the vessel set out from the middle line on the run of
the frame, and not less at their extreme ends than the moulding of
the frames; and they are to extend in a fair curve well up the bilges,
in no case terminating lower at the outside of the frame than a
perpendicular height of twice the midship depth of floor above the
top of the keel. The ends of the floors to maintain the height pre-
scribed for one-quarter of the vessel's length amidships, they may
then be gradually lowered forward and aft until the upper edges of
the floor plates are level (according to the form of the vessel), from
which to her ends they are to be gradually increased in depth, so
as to efficiently connect her sides; the upper part of the floors forward
and aft are to be high enough to give ample room between the
reverse frames on each side of the vessel for fitting the keelson
angle irons. The thickness of the floor plates for half the vessel's
length amidships to be according to the rules; but for one quarter
of her length at each end they may be reduced in thickness inch
when the plates amidships are and above; and when the plates.
amidships are in thickness and above they may be reduced.
inch for an eighth of the vessel's before and abaft the half length
amidships, and the remainder may be inch less in thickness than
the midship floors.
1
16
9
16
16
16
16
A floor plate is to be fitted and rivetted to every frame, and to be
extended across the middle line, except where a vertical centre plate
is adopted, in which case the floor plates are to be efficiently con-
nected to it on each side by double vertical angle irons of not less.
size than the reverse frames. When floors are made in two lengths
the butts are to be well fitted, and to have double butt-straps treble
rivetted, or the floor plates may be lapped and treble rivetted.
Floor plates to which the bulkheads are attached must be deeper
than the adjacent floor plates, to admit of the bulkheads being
rivetted to them above the reverse angle irons.
Watercourses are to be formed above the frames through all the
floor plates on each side of the middle line, also at the lower turn of
the bilges in vessels of full form, as well as through the vertical centre
plate.
Transom plates are to be fitted and connected to the frames, and
IRON SHIPBUILDING.
797
to the stern post where practicable, so as to efficiently support the
counter.
The reverse angle irons on frames are to be in size according to the
rules. Vessels of a certain size are to have reverse angle irons rivetted
to every frame and floor plate, extending across the middle line to
the upper part of the bilges; while in other vessels the reverse
angle irons are rivetted to every alternate frame and floor plate,
extending across the middle line to the upper part of the double
angle-iron stringer above bilges, and on the remaining floor plates
and frames to the gunwale, or if the vessel is of a depth to require
hold beams, the reverse angle irons are to extend to the upper part
of the hold-beam stringer angle iron and gunwale alternately.
All vessels, except when the vessel as per rule is above a certain
size, are to have reverse angle irons on every frame, extending alter-
nately to the upper deck-stringer plate and top of angle iron on
stringer plate next below it. In awning-decked vessels they are to
extend alternately to the upper part of the main deck stringer angle
iron, and the top of the angle iron of stringer plate next below it.
Double-reversed angle irons are to be fitted on every floor, extend-
ing from bilge to bilge in the engine and boiler spaces, and where the
vessel is of 15 feet depth or above from the hold beams they are
to extend sufficiently high to admit of the stringer at upper part of
bilge being connected to them. Short double-reversed angle irons
are also to be fitted on all frames in way of the keelsons and stringers
in hold. The butts of reversed angle irons, excepting those at
middle line, are to be secured with butt straps, having not less than
two rivets on each side of the butts.
The rivets for securing the reverse angle irons to the frames and
floor plates are to be in diameter in proportion to the greatest thick-
ness of angle or plate iron, through which they pass, and to be
spaced eight times their diameter from centre to centre.
The reverse frames for floor tops at ends of vessel will require to
be bevelled so as to make a fair seat for the centre keelson. The
reverse frames should be well butted together, and must fit well over
the floor ends; the holes in ends for floors should be punched so as
to leave about 3/4 inch from the edge of the reverse angle irons.
All scarphing and lug pieces for the double reverse frames on top
of floor must be rivetted close up to the floor plates. By giving
proper attention to all the minor details better workmanship is
ensured, and also much greater strength in the vessel.
798
MODERN STEAM PRACTICE.
The middle-line keelson, if of a single plate traversing the top of
the floor plates, is to have angle irons fitted and rivetted to its upper
and lower edges of sizes according to rules. In addition there is a
rider plate on the top of the keelson plate, extending over three-
fourths of the length of the vessel amidships, rivetted to the angle
irons, the breadth of which is equal to the sum of the two broad
flanges of the keelson angle irons, together with the thickness of the
centre plate it covers. The butts of the plates and angle iron form-
ing this keelson are to be properly shifted, and to be efficiently
butted and strapped.
The butts of the vertical plate are to be secured with double butt
straps, each not less than two-thirds of the thickness of the plates
they connect, and to be treble rivetted; the butt straps of the rider
plate to be fitted on the upper side, and to be treble rivetted; the
butt straps of the angle irons to be of sufficient length to have
not less than three rivets properly arranged on each side of the
butt.
The box keelson, if a box keelson is adopted, is to be formed
with a foundation plate, with two side plates and a top plate, with
angle irons, and of the prescribed dimensions as per rules. The
box must maintain its depth for half the vessel's length amidships;
it may then be gradually reduced to two-thirds of the same at the
extreme ends.
It will be seen that in these two forms of keelsons there is
no connection between them and the bar keel, and that in both
cases the floors are liable to trip in the entire absence of intercostal
plates between the floors, and that neither arrangement is fully
sufficient; some vessels so fitted have on grounding bowed up the
plain bar keel, leading to the fracture of both the transverse floors
and the longitudinal keelsons. The racking of the floor plates
would, under the peculiar circumstances, take place, concentrating
the strain upon the top of the keelson and of the floors, and tear
them downwards. It thus becomes apparent, that when the solid
bar keel is connected with a middle-line intercostal keelson the
strength of the structure is greatly increased.
Middle-line intercostal keelson.-The intercostal plates are to be
rivetted to vertical angle irons of not less size than the reversed
frames, to be fitted and attached to all floor plates; the intercostal
plates to extend from the keel to the top of the floors and to be fitted
close to them. Sometimes these intercostal plates stand above the
IRON SHIPBUILDING.
799
floors. In either arrangement there are two longitudinal angle
irons worked fore and aft upon the top of the floors to give a
longitudinal tie; sometimes a bulb iron is introduced between the
angle irons, and rivetted to the intercostal plates, adding still
further to the longitudinal tie. When the keelsons do not rise
above the floors this bulb iron is scored down between the floors,
of sufficient depth to lay hold of the keelson plates, to which it is
securely rivetted. When the keelson plates stand up above the
floors the bulb iron rests on the top of the floors; thus the keelson
plate and bulb iron are placed between the longitudinal angle irons
running fore and aft. In some cases the bulb iron is dispensed
with, the keelson plates standing above the floors having simply
an angle iron on each side, resting on the top of the floors; in other
cases a flat keelson plate, lying along the top of the floors, is worked
on each side of the keelson plate under the angle irons, thus greatly
increasing the longitudinal and transverse strength. In these
arrangements of keelsons there is no direct attachment between
the solid bar keel and the keelson.
We have already pointed out the difficulty of connecting the
middle-line keelson plate with the solid-bar keel, which must be
grooved or rabbeted to take the keelson plate. However, if we
make the keel of two side bars we are enabled to place the keelson
plate between them, and by rivetting the garboard strake of plates
through all, we have the keel and keelson united by several rows
of rivets, and likewise the indirect connection from the floors
being rivetted to the keelson and the garboard strakes. In some
examples the keelson plate is continuous, dividing all the floors,
and this is considered the most convenient arrangement, both as
regards the longitudinal strength and the effectual caulking of the
side plates with the keelson.
When the keelson is stopped at the throat or top of the floors a
horizontal keelson plate is worked on the floors, connecting the
keelson by two continuous angle irons. In other cases the reverse
angle irons of the floors are made continuous, being scored down
into the keelson, and the longitudinal angle irons of the keelsons
are placed in short lengths between the floors; while in some
cases the angle irons are placed on the top closely together, in-
stead of under the horizontal keelson plate. However, the verti-
cal keelson plate placed above the floors is the practice usually
preferred.
800
MODERN STEAM PRACTICE.
Bilge, side, or sister keelsons, as they are termed, consist, when
placed at the deeper parts of the floors, of intercostal plates, with
angle irons laying hold of the plating, and two angle irons on the
top of the floors; and when placed near the outer ends of the floors,
of a pair of angle irons only. Sister keelsons may be variously
arranged, both as regards the number and design.
Hold stringers are made of plate, with angle irons, or simply angle
irons placed back to back, and are situated midway between the
bilges and deck, extending all fore and aft. Where bulb iron is used.
for keelson or stringers the joints to be overlapped are rivetted or
otherwise efficiently connected; if overlapped, the length of lap
must not be less than twice the depth of the bulb plate; iron of
other form than bulb may be used for them, if of equal strength.
All angle irons for keelsons or stringers are to be in long lengths,
properly shifted; and wherever butted to be connected with angle
or plate irons, not less than 2 feet long, fitted in the throat of them,
properly rivetted to each flange, the thickness of the connecting
plates not to be less than the thickness of the angle irons they
connect.
When flat plate keels are adopted, intercostal keelson plates, or
centre-through plates, must be fitted down close on the keel, and
connected to it by double angle irons, rivetted all fore and aft to the
keel and keelson. It will be seen that in this arrangement the two
garboard strakes form one central plate, which is termed the flat
keel, while in reality there is no keel whatever.
Bilge keels are fitted on each side of some vessels to check the
tendency of the ship to make leeway when under canvas, they tend
to prevent rolling, and add greatly to the safety of a ship in the event
of her grounding. They are constructed of bulb iron, with two angle
irons for connecting them to the outside plating, and in some in-
stances plain angle irons placed back to back are adopted. In fixing
the positions of external bilge keels, they must be placed to move
endways through the water, so as not to check the progress of the
ship. Consequently they should be arranged in planes parallel to
the path of the vessel, and should extend over only a portion of the
length of the ship at the midship part, ending where the rise of the
body forward and aft commences. They are generally reduced in
depth at the ends in order to cut through the water, tending to
reduce the direct resistance of the fluid. Sometimes the bilge keels
are formed of angle iron tap-rivetted or screwed to the bottom
IRON SHIPBUILDING.
801
plating, the holes not being drilled and tapped completely through
the plate. Between these angle irons are bolted timber keels, to
which false keels are lightly attached, and then sheathed with thin
iron plating. It is supposed that in this arrangement, should the
angle irons get stripped off, the tap screws would be left in the plating,
and prevent leakage. See Fig. 565A, p. 804, for a recent bilge keel.
The deck beams are of size and spaced according to the rules of
Lloyd's, &c. All beams must be well and efficiently connected or
rivetted to the frames with bracket ends or knee plates, each arm of
knee plates not to be less in length than twice and a half the depth
of the beams, and to be in thickness equal to the beams, and not
more than two holes in each beam arm to be punched before the
beam is in place. The beams of the various decks, or of tiers of
beams, are to be placed over each other.
Owing to the great flexibility of the sides of an iron vessel, the
deck beams forming the connection, while the deck also keeps the
sides at a fixed distance, great care must be taken, otherwise the
fastenings will be injured by the working which results from that
flexibility. The beams not merely act as girders which support a
load, but likewise as struts or ties between the sides, constituting
parts of the ship's framing; they are generally constructed of an
uniform depth throughout their length, excepting of course the
knees, which are made deeper.
The pillars, all beams, for at least one half the length of the vessel
amidships, the alternate beams before and abaft this
length,and all carlings of hatchways exceeding in length
six spaces of frames, are to be pillared; in addition,
the beams under deck houses, bowsprit, pall bitt, wind-
lass, steam winches, and capstan are to be pillared.
The pillars to have not less than two rivets in each of
their ends, and to be of the sizes according to the rules.
These pillars add greatly to the strength of the
structure, acting as vertical struts, and when properly
secured at the heads (as shown for instance in Fig. 564 A)
and at the heels form vertical ties. They are gener-
ally constructed of solid bars of round iron, with palms forged on
for rivetting the heads to the bulb irons forming the deck beams,
with horizontal palms for the heels, which are bolted to the deck,
passing through the beam flanges, or rivetted to the keelson as the
case may be.

Fig. 564A.
51
802
MODERN STEAM PRACTICE.
Stringers and tie plates on beams.-As a ship may be regarded as
a hollow beam, having a top and bottom flange, the sides forming
the intervening web, it is evident that the bottom flange is enor-
mously strong, being formed of the keel, keelsons, and plating, while
the top flange is comparatively weak. Hence stringers of various
forms are worked on the ends of the beams of all the decks, ex-
tending the entire length of the vessel.
The tie plates are arranged longitudinally and diagonally; the
former are placed on each side of the hatchways, and the latter run
from side to side between the stringers on the ends of the beams,

Fig. 565.-Stringers and Tie Plates on Deck Beams.
A A, Stringers. B B, Diagonal ties.
CC, Longitudinal ties.
and are of great service in preserving the true form of the vessel,
when she is heeled over or lies across the waves. In that position
the sides become the flanges of the girders, while the diagonal ties,
&c., worked on the top of the beams, form the web, or lattice frame-
work as it were between the two.
In order to secure greater longitudinal strength box stringers
have been adopted both on the top and lower decks; in the former
the simplest arrangement consists of a top and front plate with
angle irons in connection with the usual stringer plate. On lower
decks, where the stringer plate is run along inside the frames, inter-
costal flanged plates are fitted between the frames and overlap, and
are rivetted to the top plate of the box stringer, thereby effecting
direct connection between the outside plating, without weakening
the top plate or stringer. In no case should the stringer plates be
cut through for the admission of wood rough-tree stanchions. When
the frames are extended through the upper deck-stringer plate to
form rough-tree stanchions or bridge houses, there must be a con-
tinuous angle iron wrought on the upper deck-stringer plate inside
the frames.
The Parisian, built by Messrs. R. Napier & Sons, measures
450 feet long, with a breadth of 46 feet, and a depth of 36 feet
2 inches. She is fitted with bilge keels to prevent rolling. In
IRON SHIPBUILDING.
803
Fig. 565 A is given a midship section of this steamer, which was almost
entirely built of mild steel, the service for which she was intended,
viz. from Liverpool to Montreal and Boston, requiring the greatest
strength with the smallest possible weight. To facilitate naviga-
tion in the St. Lawrence, where the draught of water is limited,
a bar-hanging keel was dispensed with, and in case the tendency
to roll would be increased by this, bilge keels, as shown in detail
at A, were fitted. Her gross tonnage is about 5500 tons, with
a load displacement of 10,000 tons. The machinery consists of
a set of compound vertical engines of the three-cylinder type,
capable of developing 6000 indicated horse-power, which propels
the ship in favourable weather at a speed of from 15 to 16 knots per
hour. Four double-ended tubular boilers, with 24 furnaces, supply
the necessary steam. See p. 496, also Plate of Parisian's engines.
As an additional security to passengers against the risks of
damage to the bottom, the vessel is constructed on the double-bottom
principle. The bracket pieces are shown on the figure at BB, the
plate keel at C, and the inner skin is shown by the letters EE. This
double bottom is divided into many water-tight compartments, and
the hull is also subdivided by ten water-tight bulkheads. The
water-ballast space is so arranged that more or less water can be
carried to suit cargo. Under these arrangements the metacentric
height is about 1½ feet. The figure gives the section in the
machinery space, and shows at F the box girder and plate frames
fitted for the whole length of this space to take the place of
beams which must necessarily be left out. It will be seen that
the ship has four strong decks (viz. orlop, lower, main, upper), and
a promenade deck, and that these are supported by lines of
pillars at D on each side of the centre line. With the double
bottom used as a ballast tank the vessel would have great stability,
and might fight half a dozen good-sized guns on the upper
deck, and might therefore do good service as a cruiser in time
of war.
Fig. 565B shows a midship section of the river paddle steamer Lord
of the Isles, built and engined by Messrs. D. & W. Henderson and
Co., Glasgow. The dimensions are: Length 246 feet, breadth 24 feet,
depth 9 feet. The vessel is driven by two diagonal surface-con-
densing oscillating engines, each cylinder 46 inches diameter, with
a stroke of 5 feet 6 inches; indicated horse-power 1800. The
paddle wheels are 20 feet 6 inches diameter. There are two hay-
804
PRACTICE.
MODERN STEAM

A
Fig. 565A.—Midship Section of Screw Steamer Parisian, built by Messrs. R. Napier & Sons.
A, Bilge keel. BB, Bracket pieces. c, Plate keel. DD, Lines of pillars.
EE, Inner skin. F, Box girder and plate frames.
Details of bilge
keel at A.
C
B
E
F
B
B
D
D
D
Lower
:===-=
Orlop Deck.
E
Promenade Deck.
Upper Deck.
Main Deck.
Deck.
IRON SHIPBUILDING.
805
stack boilers, 12 feet 6 inches diameter by 14 feet 3 inches high,
having four furnaces to each. The steam pressure is 50 lbs. per
square inch. There are four transverse water-tight bulkheads. Bow,
M'Lachlan, & Co.'s steam-steering gear is fitted amidships. On
the main deck there are two saloons, and on the top of them a pro-
menade deck 200 feet long, on which is the captain's room and

Fig. 565B.-Midship Section of the Paddle Steamer Lord of the Isles, built by
Messrs. D. & W. Henderson and Co., Glasgow.
ticket office, with flying bridge above from paddle box to paddle
box. The main saloon is a lofty and well-ventilated apartment
50 by 16 feet; at the after end is a retiring-room and lavatory for
ladies. The dining cabin is situated immediately under the main
saloon, and is 60 feet long by 24 broad; the floor is composed of
narrow walnut and oak planks laid alternately. The fore soloon is
fitted in a somewhat similar manner to the after saloon; the for-
ward dining cabin is 37 feet long by 23 wide. The officers and
crew are accommodated forward under main deck. The vessel is
licensed to carry 1369 passengers.
806
MODERN STEAM PRACTICE.

B
B
N
0
I
K
G
F
3
129
E
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a doo
odoo
.00
100
N
o go a
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P
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10000
00 00
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100000.
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B
B
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A
BA
Fig. 567.-Inside Elevation of Plating, Deck Beams, &c.,
for a Vessel of 2000 tons.
B
D
C
A, Keel.
A
Fig. 566.— Half Midship Section of the arrangement of Plating, Deck Beams, &c., for a Vessel of 2000 tons.
B, Floor.
c, Centre keelson. D, Sister keelson. E, Bilge keelson. F, Hold stringer.
GG,
Lower and middle decks. HH, Lower and middle deck beams. II, Lower and middle deck
stringers. K, Upper deck. L, Upper-deck beam. м, Upper-deck stringer. N,
Bulwark. 0, Frames
and plating. PP, Butts.
IRON SHIPBUILDING.
807
PLATING, &c.-The thickness of the plates in a vessel is to be
according to Lloyd's, Liverpool, or other rules. No plates to
be less in length than from five to eight spaces of frames, except
the fore and after hoods.-No butts of outside plating in adjoining
strakes to be nearer to each other than two spaces of frames, and
the butts of the alternate strakes not to be under each other, but
shifted not less than one frame space.
The butts of the upper or main deck and of spar deck stringer
plates, in all cases, are to be shifted not less than two spaces of frames
clear of the butts of the sheer strakes. The butts of the garboard
strakes to be shifted clear of the keel scarphs, and not to be nearer
each other on opposite sides of the vessel than two spaces of frames.
All butts of plating, when practicable, must be planed and fitted
close; the edges of the plating to be sheared from their faying sur-
faces, or the burr caused by the shearing to be carefully chipped off,
and all outside edges of plating are to be either planed or chipped
fair. The butts and edges to be carefully caulked.
The sheer strakes in one, two, three decked, and spar-decked ves-
sels, where the butt straps do not extend to the upper edge in one
length, to be fitted sufficiently high above the upper deck-beam ends,
so as to take two rows of rivets vertically in the butts above the
upper flange of the gunwale angle iron. When plates forming the
outside strakes of plating exceed 44 inches in breadth, their butts
are to be treble rivetted.
Where gutter water-ways are adopted at the upper deck, the butt
straps of the bulwark plating are to be sufficiently broad to receive
the spur in the middle of the bulwark stay; and when the plates do
not exceed 12 feet in length they are to have stays fitted against
the butt straps, and an intermediate stay is to be fitted between the
butts. In no case are the stays which support the bulwarks to be more
than 6 feet apart. Their size may be from 13% inch to 3 inches in dia-
meter, regulated by the length of the stay and the size of the vessel.
Butt straps.-The breadth and thickness of the straps are to be
according to rules by Lloyd's, &c., the fibre of the iron to be in the
direction of the fibre of the plates they connect. In vessels of a
certain size, for half the vessel's length amidships they are treble
rivetted, while in vessels of smaller size they are double rivetted.
When plates have to be doubled, the butts of these plates and of
the doubling plates are to have butt straps double rivetted, and in
addition, these doubling plates are to be well rivetted at the edges
808
MODERN STEAM PRACTICE.
and middle of the plates between the frames in addition to the rivets
which pass through the frames, and the middle of the plates to be
rivetted up before the edges; all butts of inside strakes to be rivetted
complete, independent of the outside strakes.
In no case is the treble rivetting of the butts at the bilges to be
dispensed with, excepting in the case of the strake or strakes, which
are doubled.
A lining piece should be fitted behind the upper-deck stringer
angle iron in one, two, three decked, and spar-decked vessels, from
butt strap to butt strap of the sheer strake when single, to admit of
those butt straps being in one length, the lining pieces being of the
thickness of the butt straps, and increased in depth in way of scup-
pers to admit of being rivetted to the sheer strakes above and below
the upper-deck stringer plate; unless the sheer strake extend suffi-
ciently high above the stringer plate to admit of a butt strap being
fitted above the stringer in the throat of the angle iron, and extend-
ing high enough to take two rows of rivets vertically above the angle
iron. When the sheer strake is doubled, its breadth should be
extended sufficiently high above the stringer plate to take two rows
of rivets vertically in the butts above the upper flange of the gunwale
angle iron.
Lining pieces.-The spaces between the plating and the frames are
to have solid filling or lining pieces in one length, closely fitted; to be
of the same breadth as the frames, excepting in way of bulkheads,
where they are to be fitted as stated further on.
16
16
Rivetting and rivets.—The landing edges of outside plating when
inch in thickness and above, from the keel to the upper turn of
bilge, and of the sheer strake, and when inch and above from the
upper turn of bilge to the gunwale, must be double rivetted; below
these thicknesses the edges may be single rivetted. In all cases the
thickness of the two plates is to regulate the size of the rivets, and the
requirements as to double rivetting. When the plating is of a thick-
ness amidships to require the edges to be double rivetted, the same
is to be continued all fore and aft. The stem, stern post, keel, butts
of outside plating, breast hooks, transoms, stringer and tie plates
on beams, also butts of keelsons, stringers, and all longitudinal ties,
to be at least double rivetted in all ships.
The butts of outside plating to be chain rivetted. All double and
treble rivetting, except in the keel, stem, and stern post, is recom-
mended to be chain rivetting. In chain-rivetted butts a space equal
IRON SHIPBUILDING.
809
to twice the diameter of the rivet to be between each row; where
treble rivetting is adopted, a space equal to twice the diameter of
the rivet to be between each row, with half the number of rivets in
the back row.
The overlaps of plating, where chain rivetting is adopted, are not
to be less than six times the diameter of the rivets; and where single
rivetting is admitted, to be not less than three and a half times the
diameter of the rivets.
The butts of side plating of partial awning decks, poops, top-
gallant forecastles, and bulwarks may be single rivetted.
B
A
C
Fig. 568.—Rivets.
The rivets are not to be nearer to the butts or edges of the plating,
butt straps, or of any angle iron, than a space equal to their own dia-
meter, and in edge rivetting the space between any two consecutive
rows of rivets must not be less than one and a half their diameter.
The rivet holes are to be regularly and equally spaced, and care-
fully punched from the faying surfaces opposite each other in the
adjoining parts, laps, lining pieces,
butt straps, and frames, and to be
properly countersunk where neces-
sary. They are to be spaced not
more than from four to four and a
half diameters apart from centre to
centre, excepting in the keel, stem,
and stern post, where they may be
five diameters, and through the frames and outside plating, and in
reversed angle irons on frames, where they may be eight diameters
from centre to centre. The rivets in the flanges of the gunwale angle
irons to be spaced not more than four and a half diameters apart
from centre to centre, and those connecting iron decks and stringer
plates to the beams to be spaced seven to eight diameters apart.
There are not to be less than four rivets in each flange of the angle
irons between the frames which connect the stringer plates and
intercostal plates to the outside plating, where the spacing of the
frames from centre to centre is 23 inches and above; but where the
frames are closer spaced, there are not to be less than three rivets.

A, Rivet.
B, Head. DD, Plates.
C, Ex-
aggerated cone formed by punching.
The rivets are to be of the best quality, and to be in diameter
according to the rules by Lloyd's, &c., and to be increased in size.
under their heads to fill the rivet holes. When rivetted up, the rivets
are completely to fill the holes; their heads are to be laid up, and their
points or outer ends are not to be below the surface of the plating.
810
MODERN STEAM PRACTICE.
Top sides.-The top sides of iron vessels are generally constructed
of wood, though iron top-sides are adopted by some builders. As has
been already explained, the stringer plate must not be cut, in order to
allow the rough-tree stanchions to pass through. There are various

B
Fig. 569.
A
EL
B
Fig. 570.
B
Fig. 571.
C
B
B
A
B
B
Fig. 574.
Fig. 573.
Fig. 572.
Fig. 577.
C
B
C
B
B
Fig. 575.
Fig. 576.
Fig. 578.
Figs. 569-578.-Top sides, showing Waterways, Beam Ends, Stringers, &c.
A, Top sides. 5, Deck beam. c, Stringer plates.
plans for securing the heels of the stanchions. A very common
method is by working a covering board or gunwale on the top of
the stringer plate which forms a waterway, the heels of the stanchions
being let into the gunwale, and secured by bolts, the stanchions,
rail, and berthing being wholly composed of wood, as in Fig. 569. In
another method (Fig. 570), the sheer strake being carried above the
stringer plate, an angle iron is worked on the top of the stringer
IRON SHIPBUILDING.
811
plate, the stanchions being placed in between the angle iron
and the sheer strake, and secured with bolts passing through and
through. In others a vertical clamp plate parallel to the sheer
strake is secured to the angle iron already mentioned, the stanchions
being placed or stepped in between the sheer strake and clamp
plate, and securely bolted through and through, as in Fig. 571, the
spaces between the stanchions at the heels being filled in with
wooden chocks. A wooden waterway is formed as before stated, while
in some examples an additional covering board is fitted, and in other
arrangements, as in Fig. 572, the wooden waterway and covering board
are dispensed with, a gutter way being formed with an angle iron,
and the clamp plate placed on the top of the stringer plate as shown.
In another method (Fig. 573), where the sheer strake is worked above
the stringer plate, the filling-in chocks at the heels of the stanchions
are not carried up to the top of the sheer strake; the covering board
is supported by an angle iron on the outer edge, and on the inner
edge by a shallow plate, or deep angle iron worked on the top of
the stringer plate, and parallel to the sheer strake. When box
stringers, as in Fig. 574, are adopted, the heels of the rough-tree
stanchions are fitted into iron sockets securely rivetted to the top
of the stringer as delineated.
When the top sides are wholly constructed of wrought iron, the
simplest form consists of a continuation of the side plating, supported
by iron stanchions secured to the plating and deck stringer. The
stanchions may be made of bar iron, or T iron frames are used
instead of bar iron, while in other plans plates may be adopted bent to
a Ʌ form with side flanges formed for rivetting to the plating, while
the heel is secured by angle iron rivetted to the deck stringer. Above
these iron top sides a light border bulwark is sometimes fitted, while
all have a wooden rail secured to the top sides in various ways accord-
ing to the arrangement. In the next plan we notice (Fig. 575), the
frames of the vessel are run up above the deck, and a horizontal
gunwale plate is worked on the top, and above that the bulwarks
are formed of light plating, having bar stanchions. In other
arrangements every alternate frame is carried up to form the
bulwark with side plating, a light top-gallant bulwark of wood
being fitted on; while in some plans, again, as in Fig. 576, the top-
gallant bulwark is dispensed with, and a simple rough-tree rail
substituted; a clamp plate is worked at the foot with gutter way as
shown.
812
MODERN STEAM PRACTICE.
In Figs. 577 and 578 are shown, in the former a vertical plate
placed against the frame forming the top sides, in the latter a box
stringer worked on the top of horizontal deck stringer.
Transverse bulkheads.-Screw-propelled vessels, in addition to the
engine-room bulkheads, should have a water-tight bulkhead built at
a reasonable distance from each end of the vessel. The foremost
or collision bulkhead in all cases (except in awning-decked vessels)
should extend from the floor plate to the upper deck, and be placed
in a suitable position. The engine-room bulkheads should extend
from the floor plates to the upper deck in vessels with one or two
decks, and to the main or middle deck in three-decked cargo and
spar-decked vessels. The aftermost bulkhead will be required to
extend to the height of the upper deck, unless it be connected to a
water-tight platform or deck of iron extending entirely around the
after part of the vessel, thus rendering the lower after body a water-
tight compartment; this bulkhead is to be made water tight by a
stuffing box where the screw shaft passes through.
All plating of bulkheads is to be of the thickness according to
the registry rules, and when fitted between two frames at each
side of the vessel to be strongly rivetted through them; or if attached
only to one frame, then to have brackets or knee pieces rivetted
horizontally against the side plating of the vessel, and to the bulk-
heads on the fore side and after side alternately near the middle of
each strake of the outside plating, and to be strongly rivetted thereto.
Lining pieces between frames and outside plating in way of bulk-
heads are to extend in one piece from the fore side of the frame afore
to the aft side of the frame abaft the bulkhead frames.
The bulkheads are to be supported vertically on one side by angle
irons not exceeding 2 feet 6 inches apart; and to be efficiently
connected and rivetted thereto, and to the corresponding floors,
beams of the several decks, and the frames. On the opposite side
of the bulkheads a horizontal angle iron of the size of the main
frames is to be fitted at the height of the hold beams, and where the
depth of the hold from the top of these beams is over 8 and under
12 feet an additional horizontal angle iron of the same size is to be
fitted half way between it and the top of the floors; and when 12 feet
or above ten such angle irons are to be fitted between the hold beams
and the floors. All such bulkheads to be caulked and made
thoroughly water tight.
In some steam ships longitudinal water-tight divisions have been
IRON SHIPBUILDING.
813
fitted, extending to the upper deck, and for about half the length of
the ship; the sides of the coal bunkers have thus formed subdivisions
extending between the transverse bulkheads, inclosing the engines
and boiler space. As many as five of these water-tight compartments
have been fitted in the space allotted to the engines and boilers.
Even with six transverse bulkheads fitted to such vessels they
have been lost at sea, owing to gross carelessness in the arrange-
ment of the passages or doorways that are sometimes cut through
the division plates, without proper means of closing them being
provided.
It is now the common practice to place the engines and boilers
in water-tight compartments, and in many vessels the engine
compartment is quite separate from that of the boilers, while, as
before stated, the coal bunkers are made as far as practicable water
tight.
There can be no doubt that bulkheads add greatly to the strength
and safety of a vessel; for instance, the forward or collision bulkhead
has saved many a ship when the bows have been stove in from acci-
dental collision with another vessel. It may happen that a vessel
is struck amidships and receives damage in two water-tight compart-
ments, and hence we are of opinion that the bulkheads of a ship
should be so numerous, that even were there two compartments filling
with water she would still float. Objections have been taken to
transverse bulkheads when numerous, as interfering and giving
trouble in the stowage of the cargo; but we think this of little
moment when the safety of the ship at sea is taken into considera-
tion.
Some have proposed, in order to avoid this trouble in the stowage
of the cargo, to divide the hold into compartments by means of
water-tight decks, having water-tight trunks for each, extending
above the water line; or, in other words, to the upper deck. We
have no doubt that this plan in conjunction with transverse bulk-
heads would add greatly to the strength and safety of the ship.
All the water-tight divisions in a ship should have communication
from the upper deck. It is a mistaken practice to form water-tight
divisions in a ship, and have these divisions cut through with
numerous doorways, no matter although they have sliding doors to
make them water tight, as these appliances are so very liable to get
out of order.
814
MODERN STEAM PRACTICE.
THE DECK, ETC.
Wood decks.-The kind and quality of the wood to be used is in
accordance with the rules by Lloyd's, &c. When the deck planks are
6 inches in width and under single fastenings will be sufficient; but
when they are above 6 inches, and not exceeding 8 inches in width,
there must be two bolts in each plank in every beam, one of which
may be a short screw bolt; planks exceeding 8 inches in width
must be double fastened with nut and screw bolts.
Iron deck, &c.—Vessels with very large hatchways have been
plated all over on the deck, as greater strength is thus given over that
of ordinary wood planking. The deck is the top web of the ship,
which represents a girder, and in all scientifically constructed
girders the greatest thickness is located at the middle of the girder,
but with large hatchways the difficulty is to do so, and in some
paddle-wheel vessels the engine hatch very nearly cuts up the deck
for its entire breadth. It is necessary in such cases to increase the
strength at that point with iron hatches, stringers, &c., but in most
screw steam ships, more especially in long vessels, iron decks should
be laid down, and should be covered with planking, as the iron,
forming a good conductor, renders the powerful rays of a tropical
sun intolerably hot, while in more northern climes, when the
atmosphere is at a low temperature, condensation takes place
internally, and the water thus formed runs down, or drips into the
cabins and holds, and valuable cargoes get damaged. However,
the usual method adopted is to have tie plates running fore and aft,
on each side of the hatches, with diagonal tie plates arranged from
side to side; thus the upper and middle deck, in three-deck or spar-
decked ships, can be made sufficiently strong without covering the
whole deck with iron plating. It is necessary, in order fully to
protect large hatchways, that they should be constructed in a
manner more in accordance with the principles of mechanics than
they now are, iron shutters well arranged being preferable to the
plans generally adopted. All the companions should be strongly
framed or covered with plate iron, having boarding over all. To
make a comfortable ship the bulwarks are sometimes carried up
very high and plated over on the side. We need scarcely state
that under such circumstances large openings must be left, the
lower port being flush, or nearly so, with the upper deck, and these
IRON SHIPBUILDING.
815
openings being fitted with hinged boards opening outwards. In-
deed we consider that the bulwarks should not be plated at all, but
merely boarded, so that in heavy weather the boarding can be
easily knocked away, and the waves allowed to sweep the deck, so that
the vessel, with hatches secured, can never be endangered with a
large body of water on the deck. With such precautions many
vessels might have been saved that have been otherwise lost, owing
to this trough, as we may term it, receiving and retaining a heavy
body of water, which cannot readily run overboard.
Framing of hatchways.-The framing for the hatchways consists
of carlings of bulb iron, with flanged top, or plate iron with angle
irons rivetted thereto, for secur-

A
B
C
D
D
ing the wood coamings, &c.; the
corners of the carlings are united
to the deck beams with short
angle-iron pieces; this gives a
better finish than bending the
bulb iron or making knee plates.
These angle irons are rivetted
with four or more rivets in each
angle piece. As the flange on
the top of the carlings is not of
sufficient width to take the ends
of the deck planking, a plate is
worked on the top of the car-
lings and beams for bolting the
coamings, head ledges, and deck
planking thereto, and on the in-
side an angle iron is worked all
round the hatches to strengthen
the coamings and head ledges,
and resist the strain brought on
these parts by caulking the deck planking.
and give a better finish to the hatchway frame this plate and angle
iron is rolled solid, or simply an angle iron with a deep and nar-
row flange is used. When iron decks are adopted this plate is of
course not required, but still the inside angle iron for stiffening
the coamings and head ledges is retained. In some examples the
carlings and coamings are formed of plate iron, as likewise the head
ledges, and are secured at the corners with vertical angle iron, the top

C
Figs. 579, 580.-Coamings for Hatchways.
A, Coaming. B, Carling. c, Deck beam. D, Deck.
In order to save work
816
MODERN STEAM PRACTICE.
edge of the coamings and head ledges having a neat half circle or flat
iron rivetted thereto, giving a proper finish all round the hatchway.
An angle iron is worked on the top of the deck beams for rivetting
the coamings to the bottom edge of the plate, being secured to the
half-deck beams with angle iron. Provision must be made in the
principal hatchways for getting in the engines and boilers, in order
that the openings may be closed after the main parts of the machin-
ery are put in position. In these cases it is usual to run a carling
the entire length of the hatchways (leaving an opening of sufficient
size for the boilers and main parts of the engine), and this carling
should be of equal strength with the deck beams; and the half
beams should be secured to the carlings with angle irons on each
side. These main hatchways are of course much larger than
required, and the deck accommodation would be thereby greatly
reduced. The necessary framings for forming the proper hatchways
are put in after the ship is launched, or when the machinery is in
place, and are of the usual construction, and are made of plating,
with transverse carlings to form a continuation of the half beams
and carlings forming the hatchways proper, thus giving the same
room on deck as with ordinary arrangements.
Engine and boiler framing, &c.—As the hatchways cut up the
deck where the most strength is required, the engine and boiler
bearers should be carefully arranged, not merely as a support for
the machinery, but likewise with the view of stiffening the ship
transversely; box bearers are generally worked on the top of the
floor plates for supporting the engine and boilers, and arranged in
accordance with the class of engine and boilers adopted. The
framing for the thrust block, which transmits the forward push
acquired by the propeller to the ship, should be carefully considered.
It is generally located at the after bulkhead in the engine-room
space. The flat or floor of the screw alley is supported on a middle-
line keelson worked on the top of the floor plates, the edges of this
flat being connected with the sides of the water-tight passage by
angle irons, and the top of the screw alley is sometimes worked
in a half circle, or a flat crown connected to the sides with angle
iron at the corners. At the part where the thrust block is fitted
four or five transverse frames are placed under the plates forming
the flat, and which are secured to the middle-line keelson and
the sides of the alley, as likewise to the top of floor plates, with
angle iron securely rivetted thereto. On the top of the plates
IRON SHIPBUILDING.
817
forming the flat, longitudinal bearers are worked, on the top of
which a thick plate is fitted, all of which are strongly united with
angle irons to the flat and transverse frame; these longitudinals
extend a considerable distance fore and aft beyond the top plate
that the thrust block rests on, and are generally cut in the form of
brackets tapering from the thrust-block plate down to the flat. The
screw alley is generally stiffened with angle iron at top, both out-
side and in; the outside angle irons are bent to the form of the alley


A
B
C
A
Fig. 581.-Thrust-block Bearer.
A, Bearer.
B, Floor plate. c, Top of alley.
and carried down the sides, having knees at the bottom, which are
rivetted to the top of the floor plates. Sometimes a water-tight
door is fitted forward of the thrust block, thus making the screw
alley water tight in case of leakage occurring; of course some
provision must be made at that part where the screw shafting passes
through the bulkhead to render it effectually water tight. Particular
attention should be given to these engine-room details, more espe-
cially in ships where the lower deck is discontinued aft of the engine
and boiler space, as there can be no doubt that with a judicious
arrangement of engine and boiler framing, screw alley, and thrust-
block framing, great additional stiffness can be obtained under these
circumstances. The bearers for taking the pillow blocks for the
lying shafting are arranged in a similar way as that for the thrust
block, with transverse frames between the top of the floor plates
and flat of screw alley, upon which a simple box is fitted for bolting
the pillow blocks to; a block of wood is generally placed between
the pillow block and bearer, by this means the line of shafting can
be more readily adjusted.
Rudder. The frame of the rudder is forged solid, and plated
with necessary strips or stays between the plates at the rivetted
52
818
MODERN STEAM PRACTICE.
joints, the space between the plates being filled up with wood, fir
preferred; this is thought necessary in case the rudder plates get
damaged, when they would otherwise fill with water, thus adding
considerably to the weight. The fore part of the rudder is forged
solid, leaving lugs for welding the back part thereto, the pintles being
slotted out, chipped and filed, or finished quite circular with a tool
for the purpose. The back part of the rudder frame tapers con-
siderably from the head, and when formed to the proper curve is
welded to the lugs left on the main piece. In very large rudders
lugs are left on the front and back in a line, or nearly so, with the
pintles, which are welded together after the main frame is finished

A
C
B
Fig. 582.-Rudder and Stern Post.
DD, Pintles.
in the rough, these cross bars forming
stays between the front and back; they
should be of sufficient breadth for a single
row of rivets on each edge of plate, the
joints of which are central with these
stays. Between the stays the plates are
jointed together with strip iron inside,
punched for double rivetting, and rivetted
up before the plates are adjusted. All
the holes in the rudder frame are of
course drilled to receive the rivets for
plating, which are finished quite flush
and properly caulked at the joints, the fir
being interposed prior to rivetting up.
At the top and bottom stop cleats are
rivetted to the stays for the purpose of
preventing the rudder being put over be-
yond a certain angle. Safety or fishing
chains are fitted with a shackle and pin
A, Rudder. B, Stern post. c, Heel. passing through the back part of the rud-
der frame. But it appears that the best
preventive is securing the rudder in a firm manner to the stern
post; the general plan adopted for screw steam ships is by forming
straps which embrace the pintles, sufficient space being left below,
the pintles being cut out in the solid part of the frame, and when in
place the straps embracing the stern post on each side are firmly
rivetted thereto; thus there is no danger of the rudder becoming
unshipped, an assurance which is of vast importance in a long
voyage, even although the rudder cannot be taken off unless the
IRON SHIPBUILDING.
819
vessel is docked. In some arrangements, however, the bottom
pintle at the heel works in a socket bored out in the after lug left
on the keel plate, while the other pintles work in sockets bored out
in the pieces forged on the stern post; but two of the pintles, one
at the top and the other at the bottom, bear on steel pins fitted in the
braces, steel points being screwed on the ends of the rudder pintles;
thus two convex surfaces of steel sustain the weight of the rudder,
and the friction is thus reduced to the minimum, an important point
for consideration; but on no account should those heavy rudders
be fitted without some other means of securing them in position,
and which can be easily arranged with suitable collars at the top of
the head inboard.

A
о
о
Riding bitts-A very good
form of riding bitt is simply a
cylindrical casting, having a
broad and strong flange cast B
on, and which is secured to the
deck with through bolts and
nuts bearing on a plate placed
underneath the deck beams;
wood chocks being fitted be-
tween the deck planking and
the bottom plate, which makes
a rigid and effective arrange-
ment for taking the strain. It
has been considered desir-
able, however, in order to
give additional strength in
large vessels, that the riding bitt being formed of wrought iron,
and having a central vertical stiffening plate, should be secured to
the deck by a "doubling plate" worked on the top of the deck
beams, and secured thereto by an angle-iron ring, the heel of the
riding bitt being carried down to the lower deck, and secured to a
carling worked between the lower-deck beams; thus greater leverage
is obtained to resist the strain. The former arrangement merely
depending on the strength of the fixtures must be made of great
strength to resist the strain on the cables caused by the ship's action
when riding at anchor.
Fig. 583.-Riding Bitt.
A, Riding bitt.
B, Deck.
Bollard heads.-The bollard heads for iron ships are sometimes
fitted in a very temporary manner, and are generally formed of a
820
MODERN STEAM PRACTICE.
casting bolted to the gunwale; and in some vessels having the
frames worked above the deck stringer, the timber heads or bollards
are of wood bolted to the angle-iron frames.
Modern practice points out a very different.
form; some bollard heads being constructed
of wrought-iron plating, securely rivetted
to the sheer strake of plating, and to the
stringer plate, with flanges formed on the
plates of the bollard heads (which are of a
box section) of suitable size; the plates
are bent to the form, butted together and
rivetted with straps inside, an angle-iron
hoop at the top securing the top plate, the
A, Bollard head. B, Stringer plate. whole being rivetted to the sheer strake and


B
Fig. 584.-Bollard Head.
stringer.
Cat heads. Cat heads for passing the anchor ropes are in some
iron sailing vessels made of wood; but in iron steam ships they are
generally forged of a round section and fitted with sheave, stoppers,
&c., the cat head being fitted for swinging in board; in some cases they
are forged of a flat form, and are jointed so as to fold up. To gain
additional strength, some large vessels have been fitted with box cat
heads formed of wrought-iron plating and angle irons; thus great
stiffness has been obtained with the minimum of material, and a more
secure mode of fastening to the side of the vessel by means of the
angle iron, and of bracket plates and angle iron at top; the whole
resembling the form given to the tubular wrought-iron cranes that
are fitted in the dock yards. With this rigid cantilever form of cat
head the iron sheave or block is inclosed in a frame of wrought iron,
having two turned bearings or spindles working into suitable sockets
secured to the cross plates forming the aperture on the top of the cat
head for the block to work in; by this means the block can swivel
to suit the angle taken by the cat pendant when it is led forward
to the hawse hole. Special arrangements must be made for the
stopper lever, &c., to suit the peculiar box form of cat head. The main
body of these cantilever cat heads is quite square, with inside angle
irons at the corners, the top plate taking the tensional stress spreads
out to form a bracket at each side, and is secured with an angle iron
on the top, taking an angle iron rivetted to the deck stringer-this
arrangement giving great stiffness to resist the side strain; the under
plating, which is subjected to a compressive stress, springs from the
IRON SHIPBUILDING.
821
under deck in a curved line to the end of the cat head. There is
an opening cut in the top and bottom webs for the block, having
cross plates rivetted to the top, bottom, and side of the frame, these
cross plates taking the bearings for the spindles that the block frame
swivels on—the cat head being fitted with a slip stopper lever
and detent pin, bracket, &c., as usually arranged.
THE MASTS, ETC.
Iron masts.—Iron masts are now generally adopted; they are
much lighter than wood ones, and a great deal stronger; when kept
well painted they are not liable to decay, and sometimes they form
the ventilators for the cabins, a small hole being cut in the mast
for that purpose. Iron is eminently calculated, both as regards
strength and durability, for taking the strains the masts are sub-
jected to, although steel may here be used with advantage as well
as in the hulls of ships. Iron masts are constructed like any other
tubular form of iron. The plates are bent in the rolling machine
to the required curve. The transverse joints are butted together
with strips inside, and the longitudinal joints have T iron running the
entire length of the mast, and joggled over the strips, and arranged so
as to break joint one with another. Sometimes the plates are lap
jointed, the inside being strengthened with deep angle iron at the
joints. Some makers stiffen the mast internally with diaphragm plates
and angle irons, and longitudinal cross plates joining the sides of the
tubes. The thickness of the plates varies from 3% to 5% inch, and they
are about 10 feet in length. The trestle trees and all fittings are made
of iron; the shrouds are formed of wire rope, and are of course the
main support for the masts. In some cases, in ships for the Royal
Navy, tripod masts are adopted. These consist of a central tubular
iron mast and a strut of similar construction on each side, rivetted
to the top of the mast and to the side of the ship at the stringer
and aft of the mast; the appearance of the whole is not unlike ordi-
nary sheer legs for lifting heavy weights. Sometimes the bowsprit
is supported in like manner. These modern improvements certainly
strengthen the structure, but detract from the beauty of a vessel.
In the construction of iron masts the plates should be in lengths
varying from 10 to 12 feet. In some examples the longitudinal
joints are lapped for single rivetting, the plates breaking joint; this
should be well attended to. The butts of the plates should on no
822
MODERN STEAM PRACTICE.
·
account be arranged as in some tubular structures subjected to
direct crushing stress, that is, having a ring fitted where all the butts
form a circumferential line; but the butts should break joint in a
careful manner and should be fitted accurately, having a covering plate

A
B
C
D
E
F
Figs. 585-590.-SECTIONS OF IRON MASTS,
A, Mast with T iron at the joints, and sometimes with a ring of angle iron and plates, as shown in
dotted lines.
B, Mast with angle iron running the entire length.
C, Mast with angle iron at the joints, and sometimes with plate stays, as shown by dotted lines.
D, Mast with T iron at the joints and plate stays, and sometimes angle-iron cross stays, as shown by
dotted lines.
E, Mast with T irons and plate stays.
F, Mast with angle-iron stiffeners, and rings of angle iron connected thereto.
worked inside, punched for double chain rivetting. All the rivet
holes are to be countersunk on the outside, and rivetted quite flush.
This is the simplest arrangement in practical use, but it is evident
that with a judicious disposition of longitudinal angle-iron stiffeners,
rivetted to the longitudinal seams, the mast is better calculated
IRON SHIPBUILDING.
823
to take the severe crushing stress imparted by the tension of the
shrouds; and it is imperative that all the butts should bear evenly
and be accurately fitted prior to rivetting up; unless this is properly
attended to a severe stress will be thrown on the rivets, which
would not occur were the butts properly adjusted. To obviate this
more fully the longitudinal angle irons should be welded in a
continuous length, or in as long lengths as can conveniently be
managed, with proper covering plates at the butts. The foregoing
mode of construction is generally arranged with three plates in the
circumference, while others adopt four plates, punched for double
rivetting in the vertical seams, or longitudinal joints, the butts
having a covering plate worked inside punched for double chain
rivetting, the continuous angle-iron stiffeners being worked on the
centre of each plate, and joggled where they cross the covering
plates for the butts. In some masts the plating is quite flush,
forming a true circle, the longitudinal joints butting together, the
strips being formed of T iron, and acting as stiffeners. This plan is
by far the neatest arrangement, more resembling the clean finish of
a mast made of wood. In order to further strengthen iron masts,
and also to provide a means for descending and climbing up inside
for inspection and painting, cross braces are worked on the longi-
tudinal stiffening angle or T irons; these should be spaced at con-
venient distances of not less than 4 feet apart, and certainly not
further apart than 6 feet. Plate, angle, and T iron can be used for
these cross stays, and arranged so as to bind the sides of the mast,
in a judicious arrangement, leaving a free passage for inspection.
Some have fitted diaphragm plates to a ring of angle iron, worked
in lengths between the longitudinal stiffeners, no doubt making an
efficient plate stay, but it is evident that with such an arrangement
free access for inspection is cut off. Another mode of stiffening
with angle-iron rings is at times adopted, making a very efficient
stay, and leaving a free passage down the centre of the mast for
inspection. The rings have vertical angle iron rivetted to them for
attachment to the longitudinal stiffeners; four angle irons being
fitted, with ferrules and bolts, or long rivets, placed at the centre of
each division, thus uniting the mast plating and angle-iron rings in
a strong manner.
In general the lower masts taper from the heel to the deck
wedging, and then from that point to the head the taper is uniform
throughout. But in some masts there is no taper from the heel to
824
MODERN STEAM PRACTICE.
the trestle trees, the mast only tapering from thence to the head. The
trestle trees are in some instances formed of wood, and there being
B
10:
10
A
no shoulder at the hounds, a ring
of angle iron is worked round the
mast, having plate knees, projec-
tions being formed on the angle-
iron ring for securely rivetting
the plate knees to, while the knee
plates have a ring of angle iron
around the mast binding them
at the bottom; the knee plates
thus resemble the cheeks worked
below the trestle tree of our ordin-
ary wood mast. Iron trestle trees
formed of angle iron with plate
knees are sometimes adopted;
these are securely rivetted to the
mast; the fore part of the angle-
iron trestle trees should be round-
ed to take the heel of the top
mast. In the example the cross
trees are of wood, but in modern
practice the trestle trees and cross trees are of iron, the former being
forged in one piece, while the latter are fitted into bosses forged on

Fig. 591.-Trestle Trees, &c.
A, Trestle and cross trees.
B, Mast.
B
A
the trestle trees, and are secured
thereto with cotters.

The caps of lower masts are
likewise forged in one piece and
shrunk on the mast. All the neces-
sary fittings, such as for the heel,
resemble those of wood masts,
but for iron masts the tenon that
prevents the mast turning round
when the yards are swung, under
sail, is fitted to a plate which is
rivetted to the top of the floors,
the tenon being formed of angle
iron rivetted to this plate, while
the bottom of the mast is fitted with a plate and an angle-iron ring
rivetted to it, the mortice which the tenon fits into being formed of

A, Heel.
D
C
Fig. 592.-Heel of Mast.
B, Mast. c, Tenon. D, Plate.
IRON SHIPBUILDING.
825
A
angle iron rivetted to this plate. In some examples, as in the Fig. 592,
the tenon plate that is rivetted to the top of the floors has a raised
ring of angle iron, and this fits round the heel, taking part of the strain
and giving a better finish to the bottom of the mast; of course the heel
is bevelled to suit the rake of the mast. When middle-line keelsons
are fitted projecting above the floors a part of the heel plating fore
and aft is cut out, the end of the mast resting on the plate rivetted
to the floors, which is fitted with a raised angle-iron ring for
embracing the heel, and which is properly secured by means of
bolts and nuts. At that part of an iron mast where it is wedged into
the mast framing secured to the deck beams, the plates on the mast
should be double, so as to be better able to resist the strain at that
part, as likewise to protect the main plates from corrosion, which
would materially affect in course of time the strength of the mast,
were the second plating not fitted on; the outer plating can be easily
refitted at any time. As iron lower masts act as ventilators, it is neces-
sary to leave them open at the top, providing a cover for the exclu-
sion of water, &c., in wet weather. This cover-
ing plate is sometimes constructed of a simple
curved plate open all round, which is secured
to the mast by means of knee plates rivetted
thereto. It is evident that this form of cover
is not so nice an arrangement as could be de-
sired, for, being open all round, the rain is not
excluded. A better plan is to rivet a ring of
angle iron inside of the mast at the top, on
which a reverse ring of angle iron is worked; A, Covering plate.
the covering plate being quite flat or curved,
is fitted with a ring of angle iron whose outside flange pro-
jects downwards, leaving an annular space between it and the
ring on the masthead; the cover is secured to this ring with knee
plates as in the former example, leaving sufficient space between
the head of the mast and the covering plate. By this means
the vitiated air escapes down and around the annular space; the
angle-iron ring on the head of the mast and the iron fitted to the
cover, form, as it were, a baffle annular space for the exclusion of
rain, &c., but at the same time permitting free ventilation. All the
various details fitted to iron lower masts, such as sling and stay
cleats, halyards, stays, eyes for braces, &c., must be provided similar
to wood masts. The modes of attachment must of course be different

B
Fig. 593.- Covering Plate for
Top of Mast.
B, Mast.
826
MODERN STEAM PRACTICE.
to suit the material used, and will be found fully treated in works.
devoted to the rigging of ships. The subject is one of much
importance, more especially when iron masts have now come into
such general use, necessitating an entire reformation in the minor
details of rigging.
The arrangement of plating and framing for wedging iron masts
consists of a plate rivetted to the top of the deck beams, having a
hole for the mast to pass through, the wedging surface being formed
by angle-iron rings rivetted to the top and bottom of the plate
round the edge of the hole for the mast. The plate is generally in
two halves, with half of the hole cut out of each; the joint of the
plate, running fore and aft, is secured with strip iron single rivetted.
B
H
D
A
D
O
D
This plate is of sufficient length to
take three deck beams, the centre
beam being cut, having carlings run-
ning fore and aft between the other
two beams, the carlings being pro-
perly secured by means of angle
irons at each end, and at the mid-
dle with angle irons rivetted to the
half beams; the plating likewise is
rivetted to the flanges formed on the
bulb-iron carling, which is worked
flush with the deck beams, the whole
of the arrangement of plating and
framing making a simple and effec-
tive partner-plate frame. In order to
secure a more rigid frame for large
masts plates are worked on the top
and bottom of the deck beams and carlings, which are constructed of
plate iron and angle irons or bulb iron, as shown, the wedging sur-
face being formed with a wrought-iron tube, with angle irons at the
top and bottom securely rivetted to the plates. The space between
the plates is at times filled up with wood, thus giving great rigidity
in cases where the mast is stepped on the lower deck; this is of
great importance, as the height from the step to the wedging frame
is much shorter than when the step of the mast rests on the top of
the floor plates, consequently the strain taken by the wedging frame
is much greater, and a stronger form of framing is required. The
object in view in steam ships, when the main mast is required to be

Fig. 594.-Wedging Plate for Masts.
A, Short tube for mast. B, Top plate. c, Bot-
tom plate. DD, Deck beams.
IRON SHIPBUILDING.
827
stepped on the lower deck, is to keep the engine or boiler room clear:
at the same time provision must be made to take the vertical thrust;
this is sustained on carlings worked between the deck beams on the
centre line of the vessel, and in some vessels running the entire length
of the compartment, under the carlings is placed a girder formed of
plate and double-angle irons at the top and bottom securely rivetted
to the angles on the carlings, as likewise to the bulkheads in the
compartment, knees being formed on the girder for that pur-
pose; immediately under the step wrought-iron hollow pillars
are placed, having flanges for rivetting to the girder, which are
fitted with brackets rivetted to the girder and under side of the deck
beam, thus transmitting the thrust to the hollow pillars, which pass
down and are strongly united to the floor plates. In order to
transmit the longitudinal thrust to the deck beams a broad plate
is rivetted to the top of the beams in the compartment, on the top
of which are placed teak chocks, which are bolted down to the plate,
thus forming a bed for the step of the main mast when it is not
convenient to step it directly on the top of the floor plates.
The arrangement for the mizzen mast, owing to its vertical and
longitudinal thrusts being much less than those of the main mast,
does not require such elaboration in carrying out the details. When
the mast is stepped near a bulkhead a plate is worked on the top
of, say, two beams, from the bulkhead, and is strengthened with
bracket plates, with angle irons worked all round, which are rivetted
to the top plate, bulkhead, and deck beam. On the top of the
plate the chocks are placed as for the main mast. The bulkhead
vertical stiffeners should be so arranged that the chocks come
between two of the central vertical stiffening angle irons. In some
very large vessels it is desirable to step the fore mast on box beams
worked on the top of the floor plates, with bracket plates or a
continuation of the box plates, embracing a number of the floor
plates, to which they are securely fastened with angle irons, thus
providing a very good arrangement for taking the thrust of the
mast, distributing the strain over a large surface.
Trusses for lower yards.-The iron trusses for the lower yards
of merchant ships are constructed so as to brace up the yard easily;
the first plan under notice has a hoop strap, made in two halves,
round the mast, with lugs forged on each end of the half hoops,
for taking eye bolts for drawing the hoop tightly against the mast.
The hoop on the yard is fitted with a universal joint, with a pin
828
MODERN STEAM PRACTICE.
on the end for taking the bow forming the connection between
the mast and the yard, while the other end of the bow has eyes.
forged on solid, working in the eye bolts; by this means the yard can ·
swivel in any direction.
By the second plan the eye bolts are dispensed with, a plain joint
being substituted, while there are two hoops for the yard, having
a bar between them secured with a pin and lugs forged on the


THO
B
B
Figs. 595, 596.-Trusses for Lower Yards.
A, Mast. B, Lower yard.
hoops; the swivelling joint is attached to this cross bar by a pin
joint, while the swivelling is attained by a pin fitting into a hole.
bored out in the bow, which is secured with a nut and small pin,
or it can be rivetted over as in the previous example.
Chain plates.-There are various ways of securing the chain plates.
When no channels are fitted the shrouds are let down inboard, the
plates being secured to the skin plating, or to the iron bulwarks
when so fitted. It is of the greatest importance that they should
be arranged in such a manner that they may easily be inspected,
as they form a very important point of strength in connection with
the shrouding, which is subjected to severe tensional strain. It is
highly desirable, therefore, that these fittings should be left quite
open, and kept in good condition by frequent painting to prevent
oxidation setting in. In some arrangements having narrow channels
the chain plate or bar is attached to the ship's side with brackets,
having palms forged on, or plate brackets with angle irons on each
side, which are strongly rivetted to the skin of the ship, the chain
plate being secured to the bracket by a pin joint. In other examples
with the usual breadth of channel the chain plate is formed like a
bracket, thus combining the chain plate and chain preventor in one,
IRON SHIPBUILDING.
829
the top part being bent inboard, thus forming the support for the
channel, the bottom of the chain plate having a flat palm forged
on, and which is well rivetted

to the skin of the ship. All
these arrangements of chain
plates have eyes at the top to
which the dead eyes are se-
cured with a pin joint. Al-
though wooden dead eyes are
still much used, modern im-
provements have been intro-
duced, and these fittings are
now frequently constructed of
malleable cast iron. We, how-
ever, consider wooden dead
eyes preferable, and certainly
the generality of shipbuilders
still prefer them. Of course
the chain plates may be se-
cured to the ship in a variety
of ways, the modes of attach-
ment given here are those
most commonly used.
C
A
B
D
B
D
In large sailing ships and
steamers where the bolt ropes
would necessarily be of great size, it would be difficult to ensure
that the strains on the rigging would be equally distributed over
all the shrouds and backstays, when the shrouds are set up by dead
eyes, and it has now become the practice to fit screw chain plates,
as shown in Fig. 600A. The chain plate rivetted to the vessel's
sheerstrake is indicated by the letter B. At the other end is a cast-
iron galvanized heart C, round which the wire rope shroud is passed
and securely lashed to its own part. The central part D has an
eye formed in the middle and screws at the ends, one of which is
right-handed and the other left-handed. The screws work in nuts
E and F attached to the chain plate and heart respectively, and
when the shrouds are seized to the hearts only the points of the
screws are entered, leaving the combined length of the two screwed
parts as available for taking in the slack of the rigging as it may be
required. With this system it will be seen that with the point of a
Figs. 597-600.-Chain Plates.
A, Chain plates. B, Deck beams. c, Top sides. D, Decks.
830
MODERN STEAM PRACTICE.
F
marlingspike inserted at D the shrouds can be tightened in a few
minutes, and all brought to the same tension. It is usual to pro-
OD
E
C
14 Screw-
F
D
B
B
Fig. 600A.-Rigging Screw,
tect the screws from the
sea water by covering
them with tallow, and
then lacing a canvas coat
over them, and if care-
fully looked to they give
no trouble.
Bitts around the mast.
-The wood bitts around
masts in iron ships are se-
cured to the deck beams
with a broad flanged
plate, well rivetted, the
flange being the entire
depth of the beam be-
tween the top flange on
beam and bulb; the plate
has a flange all round at
top, to which the edges
of the deck planking are
secured, and may be fitted
with a suitable moulding
at the bottom. Although
the flange for securing to
the beam is merely the
depth between the top
flange and bulb at bot-
tom, the socket for the
heel is made the entire
depth of the beam, and
it is preferable to give a
slight dovetail to the heel,
the plate socket being
formed similarly, which
prevents the bitt from

being drawn out. It is likewise secured with bolts and nuts to the
deck beams, the bolts passing through the socket, the nuts bearing
on the web of the deck beam.
IRON SHIPBUILDING.
831
WATER BALLAST.
For most ships having to make the return voyage in ballast,
more especially screw colliers, water tanks have been adopted for
ballasting the ship. All ballast should be kept down as low as
possible. Some have placed the water in tanks located between the
bulkheads, high up in the vessel, but this plan is objectionable, owing
to the difficulty of filling them, and to its placing the centre of
gravity too high.
The most approved plan is to arrange the water compartments
at the bottom of the vessel. In a 700 or 800 ton ship a space
is left about 3 feet in height from the top of the keel. A flat
floor, plated and lap-jointed, forms the top of the receiver, this
is supported and strengthened by the middle and side intercostal
keelsons, which are carried up from the keel and top of floor
plates, and securely rivetted to the plating. Stanchions or hollow
columns are placed in at intervals, connecting the deck beams with
the top of the water-tank plating, these columns forming ventilators
for carrying off the gases evolved by the coal, the gases passing
through small holes bored in the columns. The difficult task of
connecting the tank plates to the side of the vessel at bilges requires
a judicious arrangement; probably the best method is to cut the
reverse frames at that part, fit the plating between the frames, and
to joggle angle irons so as to take the frames, tank plating, and the
skin of the ship. This plan of water tank for ballasting ships is
obviously the most suitable, although it is liable to the objection of
not affording convenient access for cleansing, painting, and occasional
inspection, but when the space is about 3 feet in depth ample room
is obtained for boys to get in.
In some ships these double bottoms have been dispensed
with, a compartment being made to hold the exact quantity of
water necessary to make the ship in good sea-going trim. When
empty the compartment could be used for any sort of cargo,
and we consider such an arrangement admirably suited for
colliers. The tanks should be filled quite full, and as they may
be carried along the bottom of the vessel according to the ar-
rangement of the machinery, suitable sluices must be fitted at the
bulkheads connecting the water chambers, thus only one sluice is
required to let the sea water into the vessel. Suitable arrangements
832
MODERN STEAM PRACTICE.

must be made to connect the deck
pump and donkey, or small steam
pump, with them. The top of
the tank is covered with planking
3 inches in thickness, so as to pre-
vent the coals making indenta-
tions or otherwise injuring the
plating in the process of shipping.
In reference to double bottoms
for water ballast, Lloyd's Rules
point out the necessity of having
the double bottom efficiently con-
nected to the outside plating and
frames of the main body of the
vessel. When reversed frames
are cut, the frames must be
doubled with short angle irons of
their own size. Manholes should
be provided to enable examination.
of the interior to be made. And
the double bottom must be tested
with a head of water equal to the
extreme draught of the vessel:
ample provision being made for
the free passage of air from one
division to another, so that it
may readily escape by the air
pipe. The upper side of the
plating is to be protected by 22
inch planking. Figs. 601, 602 are
from illustrations given by Lloyds
of the arrangement of water-
ballast spaces, and show very
clearly the most approved methods
of distributing the weight through-
out the vessel, according to the
construction of double bottom
adopted. The frames and plat-
1
权
​DOUBLE BOTTOM 70 FT. LONG 80 TONS OF WATERY
BALLAST.
MIDSHIP-DEEP-TANK=25.FEETLONG=180 TONS OF
WATER BALLASTE.
CELLULAR CONSTRUCTION OF DOUBLE BOTTOM FOR
WATER BALLAST 280 FEET 500 TONS.

Fig. 601.

ing of the bottom should be covered with a suitable cement, such as
Portland, mixed with a proper proportion of sand.
IRON SHIPBUILDING.
833



|==Water Ballast---
-Fore:Peak=
20 Tons-of
//ast?
- p
Double Bottom 70F Long 80.TonsWater Ballast
Double=Bottom 1.00 Ft.Long 140 Tons of Water-Ballást.
Midship-Deep-Tañk:_
25 Ft LongT80.Tons
ankWate
Ballast
Double Bottom 70F Long 80Tons Water Ballast
· CELLULAR CONSTRUCTION-OF DOUBLE-BOTTOM-FOR-WATER-BALLAST-FIT·TED':ALL FORE˜Â¨NDEAFT:=CELL DTB 280 FEET-500-TONS.
Figs. 601, 602.-Lloyd's Arrangement of Water-ballast Spaces.
53
834
MODERN STEAM PRACTICE.
1
STRENGTH OF IRON SHIPS.
An important point to consider inshipbuilding is the actual strength
of the structure and its capability of bearing strain, and whether the
distribution of material is judicious and efficient, considering the
strains to which it is subjected. As an example in this part of
the subject we will take a ship of 1200 tons, the dimensions of
which are: 205 feet length, 34% feet beam, and 23 feet depth
of hold. One half of the transverse section is delineated to a larger
scale, and the sectional area of the iron is as follows:-


Fron N3
(Wood 120
Deck
233
120.
From 55
Wood
Deck
101
156
P
Q
-
187
139
483
J
76/4 feet
74% feet
D
D
M
-e
758
762
P-
P
R
71/4 feet
хочу 6
D
1
H
E
G
F
E
L
Fig. 603.-Vessel treated as a Girder.
sq. in.
Stringer plates, tie plates, and angle iron on main deck, marked A = 77
Do.
do.
do. on lower deck,
B =
55
Sheer strakes,.
C =
61
""
Side down to top of bilge,.
D = 298
""
Turn of bilges and flat of bottom,
E = 379
Garboard strakes,..
F =
59
Middle keelson,
G
42
•
""
Intercostal keelsons,
H
43
Bilge keelsons,
I
93
Lower hold stringers,
K
""
Keel pieces,
L
|| || ||
20
4I
26
Total,………….
ΙΙΟΙ
The area of the deck planks, amounting to 1170 square inches, is
IRON SHIPBUILDING.
835
excluded from the calculation, for they are of little value in resisting
tension, although considerably increasing the resistance to compres-
sion. Let us take, first, the extreme case, of strain upon the vessel
when supported only at the ends, as in Fig. 604. Allowing 10 feet
length at each end for the support, the distance between the supports
will be 185 feet. In this case the bottom of the vessel is in tension
and the top in compression. The displacement at the load water
line of 20 feet is 2703 tons, and the weight is made up as follows:-
Iron in hull for 1166 tons measurement, at 10½ cwts. per ton = 612
Woodwork
do. at 2½ cwts. per ton = 146
do.
Rigging and outfit,
Water and general stores,
Weight of cargo,
Total,
108
35
1802
2703
The cargo, water and general stores, and rigging and outfit,
amounts to 1945 tons, which load is unequally distributed over the
length of the ship, in consequence of the larger capacity in the mid-
ships as compared with that at the two ends, and the proportionate
distribution as measured from actual sections of the ship is shown
approximately by the figures marked upon the sheer elevation. The
length unsupported being divided into six equal parts, the respective
cargo capacities, or loads of these, are in the proportions of 11, 20,
23, 23, 22, and 14 respectively, taken from the stern forward. The
result obtained by taking the mean effect of these several loads at
the centre of the vessel is, that the strain produced at the centre
by the distributed load amounts in this case to 74 per cent. of the
total load, instead of 50 per cent. or one half of the load, as would
have been the case if the distribution of the load had been uniform
throughout the entire length. Hence the total distributed load
carried being 1945 tons, the equivalent centre load will be in this
case 74 per cent. of that amount, or 1449 tons; and the additional
weight of the vessel itself, 758 tons, may be considered as equivalent
to a load of one half the amount, or 379 tons, at the centre; making
together a total load at the centre of 1819 tons, one half of which,
or 909 tons, is acting at each end by tension on the lower part of
the vessel, with a leverage of 92% feet, or half the length of the
unsupported portion of the vessel.
As the form in which the material is placed in the sectional area
of the ship is necessarily determined by the carrying and floating
836
MODERN STEAM PRACTICE.
requirements of the ship, and is consequently not free to be arranged
in the manner that would give the greatest strength as a girder, this
case does not admit of satisfactory comparison with a wrought-iron
box girder for calculation of transverse strength. It may be con-
venient, consequently, to consider the strains on the whole sectional

Fig. 604
M
ព
20
23
23
22
14
11
Fig. 605.

Fig. 606.

Fig. 606 A.

Figs. 604-606A.-Vessels variously supported.
area as if acting upon a solid girder composed of the material that
exists at each point in the depth of the vessel, concentrated into a
solid girder of the same sectional area and depth as delineated.
In Fig. 603 alongside of the section of the vessel the metal is
shown as condensed into the form of a flanged girder for com-
parison of the areas of resistance in the several portions, in order
IRON SHIPBUILDING.
837
to deduce an approximate neutral axis for the whole section, and
the positions of the several portions of the girder are made to
correspond with the exact positions in the general section of the
vessel itself. The sectional areas of iron at the main deck, lower
deck, and bottom, are 113, 55, and 483 square inches respec-
tively. The top flange of 113 square inches area is made up of
the main deck plates and angle irons, A, of 77 square inches, and
36 square inches of the sheer strakes C from the top at M downwards;
the bottom flange is taken to include the entire section of iron in
the bottom, E E, of the vessel, from the keel L up to the point o
at turn of bilge on either side, together with the keelsons G, H,
and I. The intermediate areas of the sides are 120 square inches
between the upper and lower decks, from the sheer strake C down
to the lower deck N; and 320 square inches from the lower deck N
down to the point O, at which the bottom is considered to begin; the
latter area being divided into two portions of 158 and 162 square
inches respectively above the neutral axis PP. Then these several
areas multiplied into their respective vertical distances or leverages
give the upper dotted line PP as the approximate neutral axis
about which the moments of the areas above and below are equal;
taking the total resistance to compressive strain of the upper por-
tion as five sixths of tensile resistance of the lower portion, since the
ultimate strength per square inch of wrought iron to resist compres-
sion is five sixths of its strength for tension. In this case, the decks
being in compression and the 4 and 3 inch planks of which they are
composed being fixed tight and solid together, the timber will
contribute materially to the strength of the ship. The resistance
of the pine wood to compression may be taken at 3 tons per square
inch, and the compressive strength of wrought iron being 17 tons
per square inch, or five sixths of its tensile strength of 20 tons, the
strength of the wood is about one sixth that of wrought iron; the value
of the timber may therefore be taken at one eighth of the strength of
wrought iron per square inch. Hence the sectional area of the main-
deck planking being 960 square inches, one eighth of this, or 120 square
inches, has been added in the above calculation to the area of the
top flange of the girder, as shown by the outer lines, making the
total area of the top flange 233 square inches. For the lower deck
of 810 square inches sectional area, one eighth of this, or IOI square
inches, has similarly been added, making a total area of 156 square
inches.
838
MODERN STEAM PRACTICE.
The neutral axis P thus found is situated 9 feet above the centre
line of the bottom portion, and the strain tending to produce fracture
at the centre of the vessel will therefore be 909 tons x 922+9=9343
tons nearly. Then assuming this strain to be resisted by the portions
in tension in proportion to their respective distances from the neutral
axis P, the effective area resisting by tension will be 493 square
inches for the bottom portion, and one third of 162, or 54 square inches,
for the lower sides; since the centre of gravity of the lower sides,
from the neutral axis P down to the point O, is only a little more
than one-third of the way down from the neutral axis P to the
centre line of the bottom portion. Hence the total effective area
resisting tension is 547 square inches, on which the above load of
9343 tons gives a strain of 17 tons per square inch upon the iron.
This calculation is on the extreme supposition of the vessel being
entirely out of the water and supported only at the two extremities,
but practically the vessel when carrying her cargo is supported from
end to end by the water, excepting to the extent that this support
may be partially withdrawn by the waves and other causes producing
an inequality of immersion. It has to be observed that, although
the weight of the whole vessel is balanced by its displacement, the
extreme ends are very much heavier than their own displacements,
and consequently a larger weight is left unsupported at the ends of
the vessel while afloat, and this, as it throws a strain of compression
on the bottom, will to that extent reduce the strain of tension to
which the bottom of the vessel is exposed in the case under con-
sideration when she is supported at the ends only.
Now considering the opposite case, of the vessel being supported
only at the centre, as shown in Fig. 605, the strains on the vessel
will be reversed; the top will be in tension and the bottom in
compression. In this case the effect of the unequal distribution of
the load, taken from the same data as before, will be to produce a
strain corresponding to a load at the ends of the vessel amounting
to only 44 per cent. of the total load, instead of 50 per cent., or one
half, as would have been the case if the load had been uniformly
distributed throughout the entire length. The total distributed
load carried being 1945 tons as before, the equivalent load at the
ends will in this case be 44 per cent. of that amount, or 856 tons,
acting at the two ends; and the additional weight of the vessel
itself (758 tons) being taken as before to be equivalent to one half
that amount, or 379 tons, at the two ends, these make together
IRON SHIPBUILDING.
839.
a total load at the two ends of 1235 tons, one half of which, or
617 tons, is acting at each end by tension on the upper part of
the vessel, with a leverage of half the unsupported length of the
vessel, or 92½ feet, as before. The neutral axis in this case, found
in the same manner as before, but omitting from the calculation the
sectional area of the decks which are now in tension, is situated
at a depth of 164 feet below the centre of the upper portion, or
21 inches below the neutral axis P, and is shown by the dotted line
QQ, thus dividing afresh the 320 square inches area of the lower
sides from N to o into two portions of 181 and 139 square inches
respectively, above and below the neutral axis Q. The strain tending
to produce fracture at the centre of the vessel will therefore be
617 tons × 92%÷16=3512 tons. Then the effective area resist-
ing by tension, found in the same manner as before, will be 113
square inches for the main-deck portion, together with three fourths
of 120, or 90 square inches, for the top sides between the decks, the
half of 55, or 27 square inches for the lower-deck portion, and one
fourth of 181, or 45 square inches for the sides below the lower
deck, making a total effective area of 275 square inches resisting by
tension. Hence the strain produced by the above load of 3512 tons
will be 13 tons per square inch upon the iron.
This mode of calculating the strains of ships may be taken
as a fair example of modern practice. Although the ship has
mainly been considered as resting on the keel high and dry,
it is very evident that were the ship buoyed up with a wave at
the bow and stern (Fig. 606), the same result would take place
as if the ship were supported at both ends, the deck would be
in compression and the bottom of the ship subjected to tensile
strain; or supposing the vessel to be supported on a wave at midships
(Fig. 606A), the reverse would be the case, the deck being subjected
to tension and the bottom to compression. Again, when a ship is
plunging into a seaway and supported by a wave near the stern, the
maximum of tension is brought upon the deck, immediately over
the supporting wave, and the bottom immediately below the
supporting wave bears the maximum compressive strain; and in
fact, when a vessel is tossed about in a gale of wind, it is very
difficult to say what strain she is subjected to,-tension, compression,
twisting, or all combined.
840
MODERN STEAM PRACTICE.
In connection with this subject Mr. Wm. John, late of Lloyd's,
says¹"The following considerations have to be borne in mind in
comparing ships of different sizes having similar distribution of mate-
rial: In obtaining the maximum longitudinal bending moment it is
assumed the vessel is suspended either on the crest or in the hollow
of waves of her own length. Obviously, therefore, a large vessel can
only meet with waves capable of inflicting those maximum strains on
her during heavy weather, and therefore only at intervals. Small
vessels, on the other hand, may meet waves capable of producing
the maximum strains on them during ordinary weather, and the
repetition of such strains may therefore with them be a matter of
frequent or everyday occurrence. The fatigue or wear and tear on
the structure will therefore be greater on the small vessel than the
large one. Again, it is well known that the maximum slope of
trochoidal waves diminishes as the length of the wave increases.
In other words, small waves are comparatively steeper than large
ocean waves, and this fact would go rather towards increasing the
proportionate bending moment in small vessels. Long vessels
would escape these heavy bending strains so long as they could
overlap two or more waves, and it would be only in conditions like
an Atlantic storm, when the waves had become several hundred
feet long, that they would become liable to their maximum longi-
tudinal strains.
There is one almost insuperable obstacle to the task of framing
general formulæ for the strength and weight of hull applicable to
ships of all sizes which has perhaps not been sufficiently recognized,
It is the fact that in proceeding from small ships up to large ones
an almost entire change in the structural arrangements takes place;
and this is necessarily so, although it interferes so sadly with our
attempts to construct a general formula.
Among the forces acting on a ship at sea usually omitted
from notice is that which arises out of the lateral motion of the
surrounding particles when a ship is steaming obliquely across
a series of long heavy waves. In a wave 300 feet long and 15 feet
high the velocity of the surface particles is 6'2 feet per second.
Those in the crests are moving forward, those in the hollows back-
ward. If now we suppose a vessel sufficiently oblique to these
waves to bring the fore and after bodies in the crests of two
¹ See Trans. Inst. Naval Architects, 18th session.
IRON SHIPBUILDING.
841
succeeding waves and the middle body in the hollow, there would
be a very considerable lateral bending moment as well as a twisting
force. The two ends would endeavour to move on with the
velocity of the water in the crests, the middle body would
endeavour to recede with the water in the hollow; and soon these
tendencies would have become entirely reversed, the middle body
being in the crest and endeavouring to move with it, while the ends
are being dragged in the opposite direction. Between these two
alternating positions the lateral forces on the ends will not balance
each other, and the vessel, relieved of the strain, begins to yaw."
In connection with the subject of the size of our future sea-going
steam - vessels Mr. Wm. Denny says (Watt Lecture, 1882):—
steam-vessels
"Steamers were increasing in size, and the least costly increase
for weight-carrying and up to certain points for speed was in beam,
provided sufficient draughts could be obtained. Steamers would
follow their natural course of development, and it would be for dock
proprietors, river trustees, and harbour boards to see that their docks,
rivers, and harbours were of such depth as to permit them to favour
steamers to develop. He believed it was found daily more difficult
to build the larger types of Atlantic steamers rigid enough for the
service, even with the great percentage of their displacement devoted
to structural weight. A reaction would set in against their extreme
proportions and absolute length. When that happened beam would
be increased, as a consequence draught increased, and distinct pre-
ferences accorded to ports having great draught of water. Besides,
great draught of water and comparative shortness of a steamer were
more favourable to the efficiency of the screw by keeping it well
immersed, than enormous length, with shallow draught, which told
very much against the screw efficiency.
Mr. Denny further states that he is "convinced that the steamer
which was to do this Atlantic work would be a vessel of what might
be called at the present time moderate length-that was a vessel
which would not only be shorter than the City of Rome, but shorter
than the Servia and shorter than the Alaska, which of the three
steamers, as far as he could learn, came nearest the type he had in
view. He believed the steamer to do this work would be under
500 feet in length between perpendiculars. What her other dimen-
sions should be would have to be fixed by experiment and a very
careful series of calculations and thought."
842
MODERN STEAM PRACTICE.
BUILDERS' MEASUREMENT AND REGISTER TONNAGE.
The mode of calculating register tonnage by ratios is exceedingly
simple. The useful limit of ratios for merchant vessels is from 55
to 75 of the parallelopiped dimensions; every decimal to three or
four places, and any degree of fineness or fulness of the vessel.
Rule, multiply the length between perpendiculars (including the
rake of stern post to main deck), the extreme breadth, and the depth
of hold together, and the product by the ratio of fineness required,
divided by 100, the result will be the tonnage under deck (main or
spar deck, as may be), which may be easily produced on plan by
decimal sections designed to the ratio of form required.
If we have the following dimensions, length, breadth, and depth,
namely, 205 feet length, 34'5 feet breadth, and 20 feet depth,
then 205 × 34'5=1166, which is the builders' measurement, on any
depth; the register calculated for 20 feet depth by ratio 6 is as
follows:-
205 × 34'5 × 20 × 6
=
848-70%.
100
The following figures will explain how the same dimensions can
be made to vary about 300 tons, on the same depth, and nearly 500
between 20 feet and 24 feet hold: 205 × 34'5=1166 builders' mea-
surement, on any depth:-
By ratio,....
*55
*6
...
•65
'7
On 20 feet hold,.
778
...
On 24 feet hold,
934
849
1018
919
990
1188
1188
...
*75
1061 tons.
1273
The difference between 778 and 1061 amounts to 283 tons, and
the difference between 934 and 1273 to 339 tons on the same depth
with varying ratios, while the difference between 778 and 1273 is
495 tons on extreme depths and extreme of ratios, the builders'
measurement tonnage varying throughout.
All those tonnages from 778 to 1061 on the same depth, or from
778 to 1273 on the varying depths, can be modified in 10 tons or
I ton by using the ratios from two to four decimal places. There
is no doubt about the varying weights also, as the smallest tonnage
can be built on the 700-ton scale, even with a poop, while the largest
and fullest must be built on the 1200-ton scale, if built to class; and
experience on all ratios has proved them correct weight to tonnage
on any form. Referring to diagrams Nos. 1, 2, 3, 4 (Figs. 607, 608),
IRON SHIPBUILDING.
843
main deck
which represent midship sections of sailing vessels:-3 and 4 show
the difference of midship form of the limits 55 and 75 on the same
length, breadth, and builders' measurement (the ratio of middle
section below load line being as ratio of displacement +25; thus
ratio, tonnage 65; displacement 61+25; 86 ratio of mid section),

to main deck, 35 ft Dir.
under deck.
No 1.
N° 2.
200×342×23_1135 BM.
200x37x27-927 BM.
Ratis, of Tonnage 65-945 Beg. Ratio 126 945 Reg. under deck
55 poop
1400 gross
55
1000 gress
No 3.
No 4.
*205-342x20 – 1166 BM
Ratio.55-778 under deck
205 × 34h20, 1166 B.M
Ratio. 75 1273 under deck
Keal to matr deck 40 AG.
Keel to main død 35k Dom

Figs. 607, 608.-Midship Sections of Vessels.
but with the depth 20 feet in one and 24 feet in the other, the
circumference of half frame in the small vessel is 32 feet, and in the
large vessel 40 feet to main deck. Of course the plating and other
details of the hull are in the same proportion, scantlings varying as
the tonnage. Sections 1 and 2 show the difference of form and
ratios for the same tonnage. No. I is 200 × 342 x 21 = 1135
builders' measurement, ratio 65 = 945 new measurement under
deck, and with poop 1000 tons gross register. No. 2 is 200 × 31 ×
844
MODERN STEAM PRACTICE.
21=927 builders' measurement, ratio 725=945 new measurement
under deck, and with poop 1000 tons gross register. Both vessels
are the same length and depth and register tonnage; they differ by
3½ feet beam and 208 tons builders' measurement. They must
be built on the same line to class, and the narrow vessel has foot
6 inches longer midship frame than the broad vessel, I foot 6 inches
more circumference of plating, &c., and the vessels take precisely
the same quantities of iron, wood, and other material. Yet many
builders would have no objection to build the latter at an ordinary
rate per builders' measurement, and give over 70 tons register in
addition, while very few would be willing to build the former at any
rate less per builders' measurement with register 135 tons less. We
would prefer the register in both cases, and the former or broad
ship from choice, as a very superior ship to build and to own.
THEORY OF THE STABILITY OF A VESSEL.
The centre of gravity.-To find the correct centre of gravity of
vessels is of the highest importance, more especially with ironclad
ships of war. We will take as an example an armour-clad vessel
suited for the twin-screw mode of propulsion. The position of the
centre of gravity in a vertical line is the most important point to
determine. Divide the vessel longitudinally into, say, five equal
parts, A, B, C, D, E, and the mean centre of gravity of each portion
being found below the load water line, namely, 15 feet 3 inches
above lower part of keel, take the weight of the main parts, such
as plating, longitudinal and transverse frames, beams, deck plating,
bulkheads, stringers, &c., and then the miscellaneous parts of the
structure, as the flat and vertical keels, stern post, steam engine
and boiler bearers, shaft passages, bulkheads of shot and chain
lockers, magazine, and all ship and joiner's work, &c.:—
A
Tons.
51 ΟΙ
B
99*45 ×
C
93'54
D
99'53
E
60.38 x 5'53
Miscellaneous..
157°23
XXXXXX
Feet.
× 1'95
4'56
Moments.
99'469
453'492
5.32
497'632
4'35
432'955
213'141
4:48
704'793
561*14
)2401482(=4'279 below water line.
The battery is taken separately, with bearers, iron deck frames,
IRON SHIPBUILDING.
845
plating, port sills, girders, wood deck, armour plates, and wood
backing:-
Total weight.
115'15
X
Feet above.
8.426
Moments.
970*253
The accessories and outfit, including capstans, bitts, stoppers,
galley, and cooking apparatus, blacksmiths' work, pumps, wheels,
paint, anchors, chain cables, masts, sails, &c.; total weight-
Tons.
Feet.
60 X 3.138
Moments.
118.28
The armour-plating and backing is to be taken in three longitu-
dinal strakes; and a disposition of butts should also be got out,
and the common centre of gravity of the whole strake found as
follows:-

ARMOUR Plates.
BACKING.
Strakes.
Lbs.
Moments
above.
Moments
below.
Cubic feet. Above.
Below.
Upper,.... 110408 4047879
Middle, 137708 99725.8
443'95
1628.277
465.98
350*718
Lower,.... 98315 5362'5
189459'2
446.56
23.892
846*243
2240) 346431 5098762
189459*2
1356'49
2002.887
154.65 | 189459°2
846'243
2
320417'0
1356·5)
1156-644
309°30
31'I
'9249 ft. above L.W.L.
340'4
52 lb.
2240) 70538.0
852 ft. above L.W.L.
31.9.3.6
2
Tons.
62.19.2.12
The position of the centre of gravity of the whole hull will thus be
found:-
Iron and wood in hull,.
Armour and bolts,………..
Backing and bolts,
Tons.
Feet.
Moments
above.
...
561*23 × 4°279 =
•340'4 x *9249 = 314·8359
62.72 × •825 = 51 7440
Moments
below.
2401 5031
Battery, including armour and backing, 115'15 × 8°426 = 970*2539
Accessories and outfit, .
60'
× 3*138 = 188.2800
1139'50
1525*1138 2401'5031
1525*1138
1130*70 )876·3893
*768
Equal 94 inches below the water line.
846
MODERN STEAM PRACTICE.
The position of centre of gravity of engines, boilers, water, pro-
pellers, &c., was found to be 6.3 feet below load water line; thus
we have:-
Feet.
Centre of gravity of whole hull below load water line, 1139.70 × 7689876*3893
Centre of gravity of engine, boilers, water, &c., below water line,
273 × 6°3,
1719'9000
2596*2893
Two 30-pounders, slides, races, &c., above load water line, 42 x 6'914, 290 4000
Below water line,.
1454.7) 2305-8893
1.585
The draught of water corresponding to these weights is 13 feet
1½ inches:-
Displacement corresponding to this draught,
Centre of buoyancy below this, 13 ft. 1½ in. water line,.......
Metacentre above centre of buoyancy,
Centre of gravity below load water line,
Centre of gravity above
do.
Distance between metacentre and centre of gravity,
1454'7 tons.
5*175 feet.
7.800
1.585
""
'542
2.083
""
According to the above calculations the moment for comparative
stability is equal to
1454'7 X 2.083
3030'14
A small amount for sails was required: the moment of sails about
centre of lateral resistance is 208.231; and for moment of stability
for comparative stiffness under sail:
Displacement × GM =
3030140
208231
01455,
with the vessel light; the 300 tons weight of stores to be added
would bring the centre of gravity lower down. This vessel was
armour clad, having 6-inch plates over vital parts, and plates 6 inches
in thickness; on a fixed turret carrying two 300 pounders:-
Length,
Breadth,
Depth moulded,
Draught of water,
200 feet.
33 ""
20
14 to 15 ""
Tons.
558
Iron hull and wood works,...
Battery complete, with armour and backing,
Armour on ship,
Backing,
Accessories and outfit,
IIO
330
63
80
Engines,..
Coals,.....
273
210
Water, stores, men, and effects,
Guns and ammunition,
60
90
Displacement,.
1774
IRON SHIPBUILDING.
847
The centre of effort.—When a body is thrown into water it will
remain at rest so long as the centre of gravity of the body and the
centre of gravity of the displaced water is in the same vertical line,
in such a manner that the distance between the centre of gravity
of the body and the centre of gravity of the displaced water is as
short as possible. The importance of natural stability must be
fully recognized when it is understood that artificial stability cannot
compensate for its loss. If a ship has been brought, say, by the
force of the wind acting on her sails, out of her erect position, it is
important that the circumstances be indicated by which she will
regain it. The ability to do so is termed the stability of the ship,
and the amount of effort exerted for the recovery of the erect
position is the index showing the value of or the amount of sta-
bility; and, as a consequence, the greater the efforts to maintain
the erect position, the greater the stability of the vessel. It must
be quite obvious to all that as we increase the breadth of a vessel
so we improve her stability, but by the increase of a foot or so no
one can say by experience how much; we must have recourse to
mathematical expositions to determine the increase of stability.
The whole theory of stability is embodied in the emergence and
emersion of that part of the vessel in the immediate vicinity of the
line of flotation. While one portion of the side of the vessel is
immersed the opposite side is projecting, consequently an effort is
exerted by the immersed side tending to push the vessel upright,
and by the weight of the opposite side acting downwards, and as
both are acting with the leverage of the half width, it is evident
that the power is increased or diminished by adding to or sub-
tracting from the breadth of the vessel, or by adding to or taking
from the depth. This is all that is expressed in the solution of the
problem of stability, which may be regarded as one of the most
difficult problems in the science of shipbuilding.
We will endeavour to bring before our readers a full exposition
of this important subject. Suppose A D B, Fig. 609, to be the
greatest transverse section or midship frame of a vessel, it will be
found that in the vertical line representing the centre line of the
vessel, running through its centre of gravity, the centre of the dis-
placed water, or its centre of gravity, is located either above or below
E, which represents the centre of gravity of the vessel. Supposing
the vessel to be placed out of its natural position, as in Fig. 610,
and let F be the centre of gravity of the displacement, draw a ver-
848
MODERN STEAM PRACTICE.
tical line from F until it intersects the middle line CD at G, above
the centre of absolute gravity E, at which point the whole weight
of the vessel is concentrated, the value of E representing the entire
weight of the ship. M is found to be the point where the two lines
of flotation, namely, the upright and careened lines, cross each other,
and the efforts of the water to right the vessel are centred at F, in

P
Fig. 611.
G
Fig. 610.
Fig. 609.
C
N
I
MP
M
NB
B
Q
E
S
B
F
LE
Ꭻ
L
Fig. 613.
M
N
Fig. 612.
M
D

N
X
A
B
X
C
}
B
A
C
G
A
9
G
A
K
10
K
0
Q K
L
L
Figs. 609-613.-Diagrams showing the Stability of various forms of Vessels.
a vertical line from M, and operate at G, when the vessel is careened
from her erect position. E, that is the weight of the vessel, works
downwards in a vertical line, combined with the pushing powers
upwards, these forces turn the body, and the ship is righted, when
the power that careened her is removed and she floats with stability.
But if the centre of gravity of the displaced water be at H, and
the vertical HJ meets GD between E and D, then the pressure of
the water acts upwards in the direction HJ, and the weight of the
body downwards in the direction EL; then these forces will tend
to turn the body still further from its former position, and it floats
without stability. Through F, the centre of gravity of the dis-
placed fluid, draw the vertical line FMG intersecting CD in G; the
IRON SHIPBUILDING.
849
point G is called the metacentre, or centre of effort. It is evident
that the equilibrium will be stable when G is above E, and unstable
when it is below E. To determine the centre of effort, let S,
Fig. 611, be the centre of gravity of the body, E that of the dis-
placement in the erect position of the vessel, and F in its inclined.
position, h, h' and R the centres of gravity of NLB, ALM, and BLMC
respectively. If through the point E we draw a vertical plane at
right angles to the section NCA, and take the moments with refer-
ence to this plane, we have, if we represent the perpendiculars from
h' and h upon EJ by P and Q:-
-
MCN × EH MCBL x RT + LBN × P (1)
ACB x 0 = MCBL × RT-ALM × 9
From (2) MCBL × RT = ALM × 9
(2)
(3)
weight of LBN
(4)
But the weight of water displaced by ALM
Substituting (3) and (4) in (1)—
MCN × EH = LBN × h
(5)
whence EH =
making P + q
vol. NLB
vol. MCN
=
h
x h
(6)
If the distance ES=d, and the angle HPE=4:-
SG = EH-d sin &
vol. NLB
x h d sin
vol. MCN
(7)
Designating the weight of the vessel by M, the moment of stability
will be
M
NLB h d sin
MCN +
(8)
The upper sign is to be used when s is above E, and the lower
sign in the contrary case,
EP =
EH
sin
NLB X
MCN
h
sin
(9)
the distance from the centre of displacement to the centre of
effort. We will now determine the analytical values EH, EP, &c.
If we suppose the floating body to be a little inclined, the plane of
flotation AB is replaced by PN; these two planes cut by a vertical
plane give the section NLB: if we continue to draw parallel vertical
planes we shall divide the solid into an infinite number of ele-
mentary solids parallel to NLB. If we take the common intersection
of the two planes NLM and BLA for the axis of x, and place the
axis of y perpendicular to that of x in the plane NL, the ordinates
54
850
MODERN STEAM PRACTICE.
will be the perpendiculars NL, N'L', N'L', &c.
infinitely small, AL=LB; therefore
P = q = 23y and h
2/3 y and h = P + q = */ 3 y
The area of the section BDN is—
½ sin . y² = ½ 12
If the angle be
(10)
Multiplying this section by dx, we shall have the contents of the
elementary solid BDN dr
and for this moment
Hence-
(II)
(12)
1/2 ф 12 d x
½ 4y² d x × 2/3y = ½ y³ d x
S
2
y² d x = sum of the elementary solids.
S.
y³ d x = sum of the moments of the elementary solids.
If we substitute these values in equations (6) (7) (8) and (9), and
represent the volume of the displacement by V, we have
Idr
EH = ½ sin ¢ µ³ d x
23 .
V
S
2/3 $
(13)
SG – ½ sin ¢ √ y³ d x – d sin (14)
V
d
EP
=
2/3 32 2 x
V
x
(15)
(5 sin of dr - d sin ) (16)
Moment of stability
M /
V
If we suppose dr to be finite, and that the vertical planes parallel
to ACN are equidistant from each other, the ordinates being Y₁, 12,
1'3, &c.,-
EH =
23 sin (1º³1+ y³½ + y³s + ...) d x
% p
EP =
2
V
2/3 { y³ 1 + y³½ + ... } d x
2
V
o
2/3 sin 2 y d x
o
V

2/3 Σ y³₁ d x
V
1
ø)
Moment of stability = M (½ sin Zy₁ dx - d sin )
V
Hence, to calculate the moment of stability, we must know the
distance from the centre of gravity of the vessel to that of the
displacement. As it is inconvenient in most cases to determine
the centre of gravity of the ship, the usual method in comparing
the stability of different ships is to suppose that the two centres
coincide. The calculation of y³.dx is to be performed in
the same manner as in calculating the area of a plane figure, the
IRON SHIPBUILDING.
851
cubes of the ordinates being used instead of the ordinates. In the
division of the ordinates in the upper water line, there remain the
two triangles rad and whh, which must be included in the calcu-
lation.
For such a triangle Σ y³ dx is equal to the cube of the base
1

a
W
Y
2Y
BY
4Y
SY
6Y
Y
W
n
a
Fig. 614.-Exaggerated Water Line of a Ship.
of the triangle (Fig. 614) multiplied by one-fourth of its height;
for if a be the base of the triangle and b the height, then a½ b
and the middle ordinate is = ½ α.
CUBES.

α
I
½ a
1/8 as
4
½ as
Sum = 2/3 a³
/½d = 1% b
0
I
0
³/2 a³ × 16 b = ¼ a³ b.
The following formula is for calculating the distance to the centre
of effort from the centre of displacement:-
Ordinates of the upper
water line.
Cubes of the
Ordinates.
131
21
I
Y2
چرو
13
2
133
ᏤᎪ
42 4
I 181
4 y³ 2
2 y³8
4 18
15
135
2
2 135
Yo
4
4 13
Yr
23
I
I I y³
S
Making:
6
y³ï + y³½ + y³3 + y³4 + y³5 + y³% + y³7 = S. / distance between the sections = ½ d x
Sx dx=/ S. dx
Zydx=/ S. dx + ¼ whxhhxra xaa S
Therefore:
Consequently:
=
2/3
Zyr.dx
V
= 3/2 5/15
S'
for the height of the centre of effort above the centre of gravity
of the displaced fluid:
The moment of stability = M (½-
(-a) sin p
ø
852
MODERN STEAM PRACTICE.
In the theory of stability it is assumed that the centre of displace-
ment is the oscillating point, the surface of the water under such
circumstances becomes the fulcrum; this does not affect the solution
of the problem. In the resolution of forces operating on a floating
body that is not homogeneous, the influence of every force is
increased or diminished at every change in the form of the line of
flotation. The construction and properties of the curve that marks
the path of the centre of effort is a subject of geometrical reasoning,
and as such is liable to neither ambiguity nor error; but on what
grounds these properties are applied to measure the stability of
vessels, or to estimate their security from upsetting when much
inclined, has never been fully explained. It may suffice to add
that when the ship's inclination has brought the middle line of the
vessel parallel to the surface of the water, the centre of the absolute
gravity again assumes its prerogative, and when brought vertically
in line with the centre of displacement, the ship is just as likely to
upset as come back. A ship properly constructed should have the
centre of gravity low and the centre of buoyancy high; she would
then return to the natural position, even although the keel were
above the surface of the water-that is to say, when the force that
careened her was removed. In fact, it is only ill-shaped, dispro-
portionate vessels that do not right themselves when they are
thrown on their beam ends. It is quite possible, to be sure, that
any ship may be thrown on her beam ends; but in most cases they
are vessels having a high centre of gravity and a low centre of
displacement.
In studying this important part of the science of shipbuilding the
mechanic will receive additional information by cutting a piece of
pasteboard to the shape of the greatest transverse section, marking
the lines of flotation, the centre of gravity, and the centre of dis-
placement as taken from the calculations; he will then discover the
manner in which these forces perform their evolutions around the
centre of motion; a pin or needle may represent the axis. It should
be remembered that the area of the immersed surface or the solid
of immersion must be invariable, notwithstanding the line of flota-
tion is changed at every change in the inclination. It must also be
remembered that as soon as the centre of gravity emerges by the
inclination of the ship, the centre of displacement becomes the
oscillating point, and the distance between the centre of displace-
ment and the centre of gravity will determine how much further the
IRON SHIPBUILDING.
853
ship will go without being able to return to the upright position.
The centre of effort should not be less according to Mr. J. W.
Griffiths than 8 feet above the centre of displacement, in order that
a ship may have a sufficiency of stability for sea voyages. This
applies to ships of from 800 to 1000 tons burthen. There can be
no variable rule given that will apply to all sizes and descriptions
of vessels.
TABLE OF DISPLACEMENT OF A RIVER STEAMER.
Length, 160 feet; breadth of beam, 18 feet; depth moulded, 8 ft. 6 in.; distance between
ordinates, 1333 feet.
- Multipliers.
Ordinates.
I
Keel
Ist W.L.
4
~ 2nd W.L.
2
I I 'I 'I
'I
'I
'I 'I
'2
4
"I'M PIƐ + N
- 4th W.L.
*2
'2
*2
Moments of dis-
placement.
'I
4
$2
.8
$2
=
4 2 'I 4
I'I
44 15 6'0
2'0
8.0
2.2
8.8
'I
4'4
3'0
8.0
2.2
'I
10.8
2 3 I '2 2.7 54 3'5 7'0
4 4 ‘I 4 44 176_5°4 216
4'I 8.2
8.2
7'0
16'4
6'0 240
'I
17.6
10.8
24.0
6.5
2 5 1 2
'I
4 6 1 7°7
6.1 12.2
24'4
4 64 256
7'0 140
14 '0
76 152
30'4
7.7 30.8
8.3 33 2 8.5 34'0
'I
25.6
15'4
33°2
2 7 'I
'2
7'1 14′2
8'0 16'0
8·5 170
'I
28.4
16.0
34'0
8.7
4 8 1
4 6.8 27.2
17.7 30.8
8.3 332
'I
27.2
15'4
33°2
2 9 '1
'I
23.2
2 58 11.6 6.9 13.8
4 10 1 4 4°3 17°2 5′5 22′0
7.7 154
13.8
30.8
'I
II'O
2 II 'I 2
'I
10'4
4 12 'I
'4
I'I
6.5 26°07′2 28.8
17'2
26.0
2·6 5'2 3'6 7°2 4'6 9°2
7.2
18.4
4'4 1'6 64 23 92
7.2
5'5 11'0
5.5
3'0 12'0
'I
4'4
3°2
9.2
3.0
= 19'9×4=
4.5 9'0
4'5
6.5 26′0
79 15.8
7.9
8.5
8·7 17°4
8.6 34'4
8.6
8.1 16.2
8.1
I'7XI= I'7
= 17°7×4= 70·8× 1=
= 38.8 x 2 = 776 x 2 = 155'2
= 59′0 × 4 = 236′0× 3 = 708′0
= 76·8×2 = 153°6× 4= 614'4
82.8×4 = 331°2× 5=1656'0
= 87°2 × 2 = 174°4× 6=1046°4
= 84·5×4 = 3380× 7=2366'0
= 76′0×2 = 152'0× 8=1216'0
= 61°5 × 4 = 246′0× 9=2214'0
=416×2 = 83.2 × 10 832.0
79.6×11 = 875.6
Moments of centre of
displacement.
70.8



I 13 'I 'I
'I
'I
'I
'I
'2
'2
'2
'2
'I
'4
'2
.8
$2
=
I'7×I =
3.6
I
145'2
4
175.8
199'0
213.8
I'7 × 12 =
1945.8
20'4
11774.8
2
4
I
3.6
580.8
580.8
351.6
351.6
649 × 13°33
796'0
213.8
=
=
7960
3
213.8
11774 × 13'33
1945.8
1945.8
2884·635 82°4 × 2 = 164.8 tons.
80.6 feet centre of displacement from after
end of stern post.
854
MODERN STEAM PRACTICE.
To calculate the displacement, the place of its centre of gravity, and
of the metacentre. For these calculations we will take a ship of
500 tons, and suppose the drawing divided by ordinates in the
usual way, section being the greatest breadth, the ordinates for-
ward of the greatest breadth are marked with letters, and aft of the
greatest breadth by figures.
To find the areas of the transverse sections.
The distance between the water lines on the drawing is 2.31, and
one third of this distance is = 0.77 feet.

No. of
Water-
Section Z.
Section S.
Section M.
Section F.
line.
Ord
Ord.
1234567
5'00
3'10
I'42
0'35
142 4H
6.65 I 6.65
10'9
I 10'7
Ord.
14'58
20'00
9'4 4
37.6
14:27
6'2
7.38 2
14.76
13'55
142
I
14'58
4 57 08
Ord.
15'05
15'02 4
27'10
15'00
142
15.05
60'08
30'00
5'68
4'92 4
19.68
I
0'35
2.5 2 5'0
0.86 4 3'44
O'25 I O'25
11.88 4 47'52
8977 2
4'03 4
O'25 I O'25
14.60 4 58'40
17'54
16.12
12.85 2
25.70
7.52 4
30'08
0°30 I 0'30
38.88
0'77
91.63
0'77
180.19
0'77
219.61
0'77
½ Area=29'94
½ Area 70'56
1/2 Area=138'75
½ Area = 169'1
Section.
Section 6.
Section 12.
Section 18.
Ord.
1234567
I
15'13 I 15'13
Ord.
15'13
Ord.
Ord.
15'13 4 60.52
15'12 4
15'13
2 30.26
15.00 2
14'90
4 59'60
13.61
2 27.22
2
8.91
4 35'64
0'45 I 0'45
0'50
I
0.50
I 15.13 14.80 I 14.80
60.48 14.75
4 59'00
30.00 | 14°55 2 29.10
14'75 4 59.00 14.00 4 56'00
13.25 26.50 12.30 2 24'60
8.65 4 34.60
6.75 4
4 27'00
0°50
I 0'50
14'20
14'00
13.60
142
14'20
56.00
27'20
12:35 4 49'40
2
9'20
18.40
3'45 4
0'50
13.80
I
0.50
228.82
0'77
226.21
0'77
211'00
0'77
179'50
0'77
½ Area=176*19
½ Area=174'18
½ Area = 162'47
½ Area=138.22
Section 24.
Section 30.
Section 32.

Ord.
Ord.
1234567
I
12.90 I 12'90
12.38 4
4❘ 49'52
10'95 2 21'90
7.96 4 3184
3'95 2 7'90
I'25 4 5:00
0'50 I 0'50
8.95
I 8.95
6.30 4
25'20
3'55 2 7.10
I'92 4 7.68
Ord.
4.80
I
4.80
2.50 4 10'00
I'45 2
2'90
O'93 4
3'72
I'00 2
2'00
0'57 2
I'14
0'50 4 2.00
0'50 I 0.50
0.50 4
2'00
0'50 I
0.50
129'56
0'77
1/2 Area=99.76
53'43
0'77
25.06
0'77
½ Area=41°14
½ Area 19°3
=
IRON SHIPBUILDING.
855
To find the cubical content and centre of gravity of the part
from section 30 to the aftermost perpendicular: From section 30
to the aftermost perpendicular is 777 feet, therefore the distance
between the section 3·885, and one third of this distance = 1.295 feet.
Section. ½ Area.
30
32
41 14 I 41*14 | 0
19 30 4 77'20 I
77.2
Stern post
0.00 I
0'00 2
118.34
I'295
77.2
3.885
½ Cubical content, 153 25
118.34)299'92
2.534 Centre of gravity from section 30.
7'77 Sect. 30 from aftermost perpendicular.
5 246 Centre of gravity from
do.
To find the cubical content and centre of gravity of the part from
section 30 to section S: Distance between the sections = 12, and
one third of this distance = 4 feet.
99.76 4399'04 I 399'04
Section. ½ Area.
30
41 14 I 41 14 0
24
18
138.22 2 276 44
2
552.88
12
162 47 4 649.88 3
1949 64
6
174 19 2 348.38 4
1393 52
Φ
176 19 4
704 76
5
3523 80
F
169.10 2 338*20
2029 20
M
138 754 555.00 7
3885.00
70.56 1
70.56 8
564.48
4
3383°40 )14297*56
2 Cubical content, 13533.6
4*2258
12
50 7096 Centre of gravity from section 30.
7'77 Section 30 from aftermost perpendicular.
58.4796 Centre of gravity from
do.
To find the cubical content and centre of gravity of the part from
section S to the foremost perpendicular: From section S to the
foremost perpendicular is 962; distance between the sections 481,
and one third of this distance = 1·603 feet.
Section. ½ Area.
S
70.56 | I 70.56 0
Ꮓ
29'94 4 119.76
119.76
Stem
0'00 | I
0.002
190*32
1.603
119.76
4.81
½ Cubical contents, 30508
190*32)576'05
3'026 Centre of gravity from section S.
103 77 Section S from aftermost perpendicular.
106.796 Centre of gravity from
do.
856
MODERN STEAM PRACTICE.
To find the whole displacement D:
2 Cubical content from section 30 to the stern post,
51
½ Displacement,..
...
30 to section S,...
S to the stem,
...
...
153°25
13533.60
305'08
13991'93
The whole displacement =D=
2
27983.86 cub. ft.
To find the centre of gravity of the whole displacement.
This centre is from the aftermost perpendicular:
05'08 × 106.796+13533'6 × 58°4796+153′25 × 5*246
13991'93
Half of the length between the perpendiculars,
= 58.95
56.695
Centre of gravity before the middle of the load water line 2255 feet.
The displacement should have been 279167 cubic feet, and the
centre of gravity of the displacement 2·268 feet before the middle
of the load water line; consequently the displacement has been
67.16 cubic feet too large, and the centre of gravity has come
O'013 feet 0156 inches too far abaft; but this small incorrectness
is of no consequence in a machine of this magnitude, and might
easily have been obviated if the drawing had been made to a larger
scale.
To find the area of the water lines. The distance between the
sections is 12 feet, and one third of this distance is = 4 feet:

1st Water Line.
2d Water Line.
3d Water Line.
4th Water Line.
Sections. Ord.
Ord.
Ord.
Ord.
S
10.90 I 10'90
9'40 I 9'40
7.38 I
7:38
4'92
M
14.58 4 58.32
14:27 4
57:08
13:55 4
54 20
F
1505 2 30 10
| |
15:02 2
3004
15:00 2
30.00
11.88
14'60
142
I
4'92
4 47'52
Φ
1513 4 60 52
15'13 4
60.52
15'13 4
60 52
14'90
29'20
4 59 60
6
15.13 2 30 26
||
15:12 2
30 24
15'00 2
|
3000
14'75
2
12
14.80 4
59 20
14'75 4
59.00
14:55 4
58.20
|
14'00
4
29'50
56.00
18
14 20
2
28 40
14'00 2
|
28.00
13.60 2 27.20
12 35
2
24
12.90 4
5160
12 38 4
49 52
10 95
4 43.80
7.96 4
30
¡ 8.95 I
8.95
6.30 | I
4'30
3'55 I 3'55
I'92
24'70
31.84
I I'92
338.25
4
330'10
4
314.85
4
285·20
4
1353'00
Before section S 60'59
Abaft
30 36.84
1320'4
47.13
21'49
1259'4
31 71
12'43
1140.8
17.95
7'53
½ Area=1450°43 ½ Ar.=1389 02 ½ Ar. =1303°54
½ Ar. =1166.28
IRON SHIPBUILDING.
857

5th Water Line.
6th Water Line.
7th Water Line.
Sections.
Ord.
Ord.
Ord.
S
2.50 I 2.50
M
8.77 4 3508
0.56 I 0'56
4'03 4 16.12
0.25 I
O'25
O'254
I'00
F
12.85 2
25*70
7'52 2 15'04
0.30 2
0.60
Φ
6
13.614 54°44
13:25 2
8.91 4 3564
0'45 4
1.80
25.50
12
12.30 4 49°20
8.65 2
6.75 4 27.00
17.30
0.50 2
I'00
0.50 4
2'00
18
9 20 2
18.40
3.45 2
6'90
0.50 2
I '00
24
3'95 4
15.80
I'25 4
5'00
0.50 4
2.00
30
I'00 I
I '00
0.50 I
0'50
0.50 | 1
0°50
228.62
124'06
10'15
4
4
4
Before section S
Abaft
914.48
6.97
30 4.36
496*24
40.60
2'44
Ο ΟΟ
I'17
I'I
½ Area 925.81
½ Ar. =499'85 ½ Ar. = 41×7
To find the displacement and the place of the centre of gravity
below the load water line:
Water Lines.
Water
½ Area of
Lines.
I
1450'43 I 1450'43 O
1234567
1389'02 4
5556'08 I 5565'08
1303'54 2
1166.28 4
925.81 2
2607'08 2 5214'16
4665'12 3 13995 36
1851.62 4
7406.48
499.85 4
41'70 I
1999'40 5
41'70
9997'00
250°20
18171-43
)42419.28
'77
½ Displacement
=
13992'00
2'334
2.31
2
Whole displacement=D=27984'00
To find the metacentre:
Ordinates
Cubes of
Sects.
of first
Ordinates.
Water Line.
S
10'9
1295'03
M
14.6
3112 14
I 1295'03
4 12448.56
F
15'1
3442'95
2
6885'90
Φ
15'1
3442'95 4 13771 80
6 15'1
12
14.8
18
14'2
24 12'9
3442'95
2863.29
2
6885'90
3241 79 4 12967.16
2 5726.58
2146.69 4 8586.76
30
9'0
729'00 I
729'00
69296.69
4
277186.76
The triangle before sect. S
3114'55
abaft
""
30
1416'08
281717.39
5 391 Centre of gravity of displacement
below the load water line.
281717.39
2
3)563434'78
27984) 187811*593
6.711 Metacentre above the cen-
tre of gravity of D.
5 239 Centre of gravity below
the load water line.
1320 Metacentre above the
load water line.
858
MODERN STEAM PRACTICE.
It is now the practice in large shipbuilding yards to find the
centre of gravity of the vessel by experiment as is done for all of
her Majesty's war ships.
About 15 tons of cast iron weights are generally used, and are
divided into two lots, one on each side of the deck, and the ship
trimmed perfectly upright, and marks taken by means of plumb
lines suspended in each of the hatch openings. The one lot of
weights are then rapidly transferred to the top of the other lot on
the other side of the ship, and the distance travelled by the weight
on the end of the line carefully recorded.
By the following formula the centre of gravity is found—
r

C
m
"Z
T
Z
r'
When rr is horizontal,
Shifted weight=r,
0=ZmZ'.
T (rr)=cd=mT.
D
mTcot 0=mc=distance of centre of gravity below m,
the calculated metacentre.
Fig. 614A.
The metacentre and centre of buoyancy are then calculated from
the lines, and the distance between the centre of buoyancy and
the centre of gravity thus found gives the measure of stability
GRAPHIC SYSTEM OF INVESTIGATION.
1
The following diagrams are from a paper by Mr. W. H. White,¹
on the Course of Study at the Royal Naval College, Greenwich, and
show the graphic methods adopted to indicate the straining action
to which vessels are subjected.
"Figs. 614B-614E show the curves of stability, weight, buoy-
ancy, loads, shearing forces and bending moments for an armoured
turret ram. This vessel is 256 feet long, 57½ feet broad, and 18 feet
draught of water, displacement about 5000 tons. She carries two
25-ton guns in her turret, has 12-inch armour on turret and sides,
¹ See Trans. Inst. Naval Architects, 18th session.
IRON SHIPBUILDING.
859
2-inch and 2½-inch deck armour. Her central battery is about 96 feet
long, and the battery deck is 9½ feet above water. Before and abaft
the battery there is an armoured deck about 2½ feet above water, and
the sides to the height of the battery deck are continued by light

Arms of Righting Couples
feet C
4.0-
3.5
3.0
2.5
2.0
1.5-
⚫5
Curve of Statical Stability (Ends intact)
Curve of Dynamical Stability (Ends Intact)
‚Curve of Statical Stability (Ends Riddled')
Curve of Dynamical
A
78
270
860
Stability (Ends Riddled)
1
45° 5010
630
72076 810 B
Angles of Inclination
Fig. 614B.
plating, forming living spaces for officers and crew. It is possible
to admit large quantities of water to these spaces by a few shot
holes, and the curves of stability have therefore been constructed
for both the intact and the riddled condition. The contrast between
the curves of statical stability in these conditions is very great, as
the following comparative statement will show:-
Intact....
Superstructures riddled…………….
Maximum Arm of
Angle of
Righting Couple. Maximum Stability.
3.85 feet.
34°
I'7"
23°
Range of
Stability.
764
50%
The contrast between the curves of dynamical stability is no
less remarkable. The length of the ordinate for the curve in
the riddled condition at the upsetting angle (50%), represents
the work to be done in capsizing the ship in still water-neglecting
that done on the water disturbed. It will be seen that when
the sides are intact an equal amount of work has to be done
in heeling the ship over only about twenty-six or twenty-seven
degrees out of her range of 76½ degrees.
The waves upon which the ram is supposed to float are 256 feet
860
MODERN STEAM PRACTICE.
Curve of Buoyancy
Curve of Weight
long and 17 feet in height; and in Figs. 614D and 614E the
outline of the ship is shown when poised upon a wave crest or

Curves
on
rest in hollows
Curve of Shearing
Bending Moments
Curve of Bending Moments for Comparison-witi
M
Curve of Loads
10
16
15
174
13
12
astride a wave hollow, in the position of instantaneous statical
equilibrium assumed for purposes of calculation."
Fig. 614C
Force
♡
-
2
Οι
IRON SHIPBUILDING.
198

116
15
174
171
Curve of Bending Moments
Curve of Buoyancy,
Curve of Weights
Curve of Loads
170
Scale
8
of_Lengths
Curve, of Shearing Force-
Fig. 614 D
12
862
MODERN STEAM PRACTICE.

15
1
Curve
of
Weights
1
1
Curve
1 of
Buoyancy
الا
Curve
of
Shearing
13
10
--Curve-tõf” Loads
Force
Curve
of
Bending
Moment
Co
Fig. 614 E.
2
IRON SHIPBUILDING.
863
POSITION OF PADDLE WHEELS.
The following diagrams are taken from a paper recently read by
Mr. James Hamilton, junr., before the Institution of Naval Archi-
tects, the scope of the paper being to show "Two sources of loss of
power in paddle steamers: that is, energy absorbed in creating and
maintaining waves, and also the effect of this wave-formation on
the wheels."

дом
A
B
C

Fig. 614 F.-Waves raised at Maximum Trial Speeds.
A, Speed 11'4 knots. B, Speed 10'88 knots. C, Speed 16'18 knots. D, Speed 17°9 knots.
"The first of these, due to constant wave-making, is common to
all vessels pushed to a speed beyond what their size and form fit
them for. It is irrespective of the description of the propeller, and,
according to the late Mr. Froude, forms a large proportion of the
total resistance.
In paddle-steamers wave making has a second and special im-
portance beyond what it has in screws and other vessels, which is
due to the nature of the propeller.
In the former class, as in the latter, it is of every importance
that the lines should close in 'with graceful curves and slow degrees,'
and it is fortunate when a wave crest, and not a hollow, fits in at
the after-run to utilise this quality to the utmost. But in paddle
steamers an additional consideration of importance is the position
the wave crests will take up in relation to the wheels.
We draw a straight line on our plan to represent the water
surface, and, with great nicety, fix the area of the floats and calcu-
864
MODERN STEAM PRACTICE.
late their centre of effort. We carefully adjust the diameter of the
wheels, so that they may make the exact number of revolutions to
suit the proposed engine and boilers; and theorists devise elaborate
rules connected with effective diameter, slip, &c., and we forget the
shifty nature of the base we found on.
If the ship be hard to drive she sets up a wave formation of her
own, and with an utter disregard for our paper water line, raises or
lowers the water surface in the neighbourhood of the wheels, and
upsets our theories and calculations.
The diagram Fig. 614F illustrates both of these causes of wasted
energy. It represents four vessels, marked A, B, C, and D respec-
tively, and the waves that each sets up in smooth water at her
maximum speed.
It may be mentioned here that exhaustive trials on the same
measured mile were made with each of the vessels. The types are
widely different, the maximum speeds ranging from less than
eleven to eighteen knots, and it is only fair to say that, notwith-
standing any imperfections that may be shown to belong to any of
them, each vessel is amongst the fastest, or is the fastest, of her type
and class. They may therefore be regarded as representative
vessels.
The wave
The wave formations of the first three were carefully measured
at the trials, and while running at the speeds marked on the dia-
gram. For the data connected with the fourth I am indebted to
Messrs. James and George Thomson, the builders.
surface was not, however, measured, but has been taken from a
photograph of the ship at full speed, and, as her length and form
are well adapted to her high speed, the slight change of surface
shown is likely to be correct.
The first, marked A, raises three waves in the length, and brings
the wheels into a wave hollow, thereby reducing the area of the
paddle race considerably. It will be observed also that the centre
wave curves too close behind the wheel to make the increased head
of water of use in giving forward pressure to the vessel.
The second, marked B, is a case of four waves in the length, a
wave coming just in front of the wheels, the one abaft it being in
this case also too far forward to be of service.
The third and fourth, marked respectively C and D, have about
two and a half waves in the length, and show the wheels working
at the normal level. These vessels are of a length and form more
IRON SHIPBUILDING..
865
nearly corresponding to their speeds, and so the waves once raised
will travel along with the ship without a great expenditure of
power to maintain their speed. In the case of the first two,
however, as the dotted wave lines drawn under each vessel
show, the length of rolling waves corresponding to the speed is
in each case much greater than the waves made by the ship, so that
short waves are made to travel at a rate beyond their natural
speed, and a constant expenditure of power goes on to accomplish
this.
The diagrams show just what one would expect, namely, that
broad, full vessels exert power in raising a series of waves, whereas
longer vessels of narrower and sharper design are more or less free
from this."
EXAMPLES OF RECENT LARGE STEAM SHIPS.
The ORIENT (see Plate) was built and engined on the Clyde by
Messrs. Elder & Co. for the Orient Steam Navigation Company,
and is employed in the Australian trade. Her principal dimensions
are: Length between perpendiculars, 445 ft.; breadth, 46 ft.; depth,
36 ft. 10 inches; gross tonnage, 5385 tons; displacement weight,
9500 tons.
Her engines are of 5500 indicated horse-power; aver-
age speed at sea, 14½ knots; while on trial 15% knots were
attained. The ship is barque-rigged with four masts, has three
iron decks, and is divided into thirteen water-tight compartments
by bulkheads; while, as a security against fire, from the lower to
the main deck she is divided into six compartments by five
fire-proof bulkheads, fitted with fire-proof doors. She has been
equipped beyond the requirements of her class, 100 A1, the highest
at Lloyd's, and has satisfied government inspection as regards her
defence by means of water-tight compartments and coal bunkers,
so that she would be available in time of war as a cruiser or troop-
ship, and indeed she has already been employed by government
in conveying troops to Egypt. Her coal bunkers are so placed
as to protect her engines, while they carry coal enough to keep
her at sea, steaming full speed, for forty days, and she could not
be sunk by penetration of less than three of her water-tight com-
partments.
•
The Orient can carry, in addition to 3000 tons of Welsh coal,
3600 tons of measurement cargo, weighing about 1000 tons. She
55
866
MODERN STEAM PRACTICE.
also carries 120 first-class passengers, 140 second-class, and 300
third-class or steerage passengers. By a sacrifice of cargo space,
however, she could carry 285 more third-class passengers.
A
different arrangement of space would enable 1500 troops and 400
horses to be carried in addition to the other passengers. If entirely
devoted to troops the ship could convey 3000 men and 400 horses
at once with the proper stores.
The engines have three cylinders, one high-pressure of 60 inches
diameter, the other two low-pressure of 85 inches diameter. The
crank shaft is built in separate pieces shrunk together and keyed,
the diameter of the shaft being 20 inches, and that of the steel crank
pins 21 inches. The propeller is four-bladed, the boss being of
annealed cast iron, and the blade of cast steel specially made for the
purpose by Messrs. Vickers. The blades are bent backwards to
diminish vibration. The diameter of the screw is 22 feet, and the
pitch 30 feet. The condenser contains nearly 12,000 square feet of
cooling surface, and the water for condensation is circulated by
means of two independent combined steam centrifugal pumps made
by Messrs. Gwynne & Co. The condensing surface and the
capacity of the centrifugal pumps are made larger than they other-
wise would be because the temperature of the water on part of the
voyage home—namely, in the Red Sea is so high that an un-
usually large quantity of it is required to cool and so condense the
steam. The reversing engine is a special feature. Simply moving a
lever not only stops the engines when at full speed, but immediately
turns them full speed astern. The boilers are four in number, 15 feet
6 inches diameter by 17 feet 6 inches long. They contain twenty-
four furnaces, each 4 feet diameter by 6 feet long, and the working
pressure is 75 lbs. on the square inch. The furnaces are constructed
with special arrangements for the economical consumption of
Australian coal on the passage home.
A great feature of the first-class accommodation, as will be seen
in the Plate, is the splendid saloon forward, free from the smell
of the engine and smoke from the funnels, running through from
side to side, 44 feet square and very lofty. It is fitted with electro-
plated brass furniture, richly carpeted, and opens into the music
saloon above. The third-class accommodation supplies separate
cabins, and the crew's forecastle is very spacious and comfortable.
The chief saloon passengers have a promenade deck 160 feet long,
and the whole breadth of the vessel, for their exclusive use; whilst
IRON SHIPBUILDING.
867
the interior fittings of the dining saloons, music saloon, smoking
rooms, and passengers' cabins are of an elegant description.
The vessel is fitted with patent hand and steam steering gear,
steam windlass, five powerful steam winches, two condensers for
supplying fresh water, four large lifeboats and five other boats;
punkahs or large fans worked by steam in the chief dining saloon,
pneumatic bells to all saloon state rooms, speaking tubes, and
telegraphs. There are sixteen steam engines, for different purposes,
in the ship. The arrangements for a constant and ample supply of
fresh water are very complete. The large tanks fitted below the
orlop deck in the after part of the ship hold about 80 tons. These
are of course filled when the ship leaves the docks; but to keep up
the supply required for daily use there are two large condensers.
which will condense if required 200 gallons per minute. The water
when leaving the condenser enters a cooling tank fitted with a large
spreader or aerator. From this tank it runs direct to the main
tank, from which it is again pumped by a small steam pump in the
engine room to a very large tank fitted on the promenade deck,
whence it runs to every compartment into smaller tanks. Ice rooms
are fitted on the lower deck for carrying 60 tons of ice. As a pro-
tection against fire, the sea can be admitted bodily into any two of
the thirteen water-tight compartments without sinking the ship.
The protection against drowning is supplied by four lifeboats, carry-
ing eighty each; two cutters to convey ninety each, a gig and a
mail boat calculated to sustain forty-five each; a large steam launch
and twenty-six life rafts, each capable of saving from forty to sixty
people. In every berth in every class is a life jacket, which, rolled
up, might be used as a bolster. Mosses' and Mitchell's automatic
ventilators, used in the British and American navies, are fitted to
all the lower decks of the ship. When scuppers are closed in stormy
weather, these ventilators increase in activity, and expel the foul
air through gigantic cowls. A special ventilator by Mr. Shepherd
of the Orient Company keeps the first and second class cabins sweet.
This magnificent vessel and the other ships of the Company sail
monthly from London to Adelaide, Melbourne, and Sydney, touch-
ing at Plymouth for the mails. The passage out is by the Cape of
Good Hope, returning home by the Suez Canal, and the Australian
mails can be delivered in thirty-one days. To meet the require-
ments of the Australian fresh-meat trade the Orient has, since
building, been fitted with the refrigerating machinery.
868
MODERN STEAM PRACTICE.
The dimensions of the Cunard screw steam ship SERVIA are:
Length over all, 530 feet; breadth, 52 feet; depth from top of keel
to top of upper deck beams, 42 feet. She has three complete.
decks and two partial decks, and is divided into twelve main
water-tight compartments by transverse bulkheads. The Servia
is constructed of steel, on the lattice double-bottom system, and has
capacity for 800 tons of water ballast. Her decks are formed of
1½-inch steel plates, covered with 4 inches of teak wood. The upper
deck has on it the forecastle for part of the crew, and the necessary
wash-houses, &c., for emigrants; hospitals, stairways to main and
lower decks, winches for working cargo, officers' rooms, smoking
room, galleys and baker's shop, music and ladies' rooms, entrance
to main saloon, and a steering-wheel house right aft.
The main deck has accommodation for seamen, stewards, and
engineers; also 86 state rooms, capable of berthing 344 passengers;
also main saloon for dining, &c., with necessary pantries. The lower
deck has accommodation for 328 passengers in 82 state rooms,
also for 730 emigrants. The speed at sea is 174 knots per hour,
and attained on trial 1734 knots. The gross tonnage is 7400, the
nett being 3900 tons. The Servia carries 5000 tons dead weight
in 26 feet draught, but could carry 10,000 tons with safety if the
depth of harbour would permit. She consumes 1300 tons of coal
in crossing the Atlantic, and has bunker accommodation for 1800
tons. Swan's incandescent electric light is used for lighting the
ship.
The CITY OF ROME measures 600 feet in length, breadth 52 feet
3 inches, depth 37 feet, and is constructed of iron. The plating
is worked flush upon the frames, with doubling strakes along all
the longitudinal seams. The vessel is divided into eleven water-
tight compartments. There are four decks, and a water ballast
tank holding 380 tons of water. State rooms are provided for 290
saloon passengers, and accommodation is provided for over 1000
emigrants. The saloon is 72 feet long, and extends the whole
breadth of the vessel, and can seat 250 people at dinner. To pro-
tect the ends of the vessel from heavy seas she has a forecastle and
turtle-back poop.
The ALASKA, which has made the fastest Atlantic passage on
record, measures 500 feet long, 50 feet broad, depth of hold 38 feet.
Gross tonnage, 6932. Nett register, 3579. The Alaska has five
decks, the highest being a promenade deck, the second, or upper
IRON SHIPBUILDING.
869
deck, are cabins for the officers, &c.; on the third or main deck, are
the saloon and state rooms. The passage across the Atlantic
referred to was made in 6 days 20 hours, about 400 miles being
run daily.
The fastest passage on record from Shanghai to London has also
just been made by the STIRLING CASTLE, the time under steam
being about 28 days, and the whole time with detentions being
under 30 days. The distance travelled is about 12,000 miles. This
vessel measures 430 feet in length by 50 feet beam, and is 32 feet
9 inches deep. The engines are three-cylinder compound, with six
boilers loaded to 100 lbs. steam pressure.
Fig. 614G shows a section of the Russian imperial yacht LIVADIA,
recently built on the Clyde. Her dimensions are: Length, 260
feet; breadth, 150 feet; depth, 50 feet; tonnage, 11,609; and dis-
placement, 4000. The propelling power consists of three sets of

B
E
M
C
PO
P
201
5
10
20 30
0 50
60
70 80 90 100 FEET
B B, Boilers.
Fig. 614G.-Midship Section of the Livadia.
PP, Propellers. c, Coal bunkers
EE, Engines.
engines, each having three cylinders, the diameters of which are, for
the high pressure 60 inches, and for the low pressure 78 inches, with
a stroke of 3 feet 3 inches. The propellers themselves are of man-
ganese bronze, thus securing strength and lightness; and with the
view of obtaining the greatest possible strength, steel has been largely
used in the construction of the engines and boilers, which are the most
powerful as yet constructed for their weight. The indicated horse
power is 10,500. On the trial trip the Livadia attained a speed. of
about 15 knots an hour. Having received damage to the hull in
the Bay of Biscay, and at present laid aside, further data as to the
870
MODERN STEAM PRACTICE.
advantages or disadvantages of this novel mode of construction are
awanting. All accounts describe her as very steady in a sea-way.
STRUCTURAL DETAILS.
After the draught of the ship is completed, a model is made on a
scale of 1/4 inch to the foot, in which the frames, plating, butts, and
the general arrangement of the bulkheads, are shown.
D
B
In order to help the workmen and prevent confusion, the strakes
of the plating are marked alphabetically and the various plates in
the strakes numbered, and all the plates are dimensioned on the
model and taken from it, the length of the plates on an average
being about 10 feet, or otherwise, according to the specification.
In ordering the plates an allowance of I inch in length and
½ inch in breadth should be allowed for the middle plates, but
for the end plates, where the curve and twist
is considerable, more must be allowed. The
length of the angle-iron frames may likewise
be taken from the model, or from the full-sized
drawing of the body plan, laid down in the
moulding loft. And in some instances the
breadths of the platings are transferred from the
model to the full-sized drawing on the floor, and
all the edges of the plates are "faired," and the
correct breadths taken from the body plan, while
the lengths are taken from the model; by this
means they can be ordered more correctly from
the makers, but still I inch is generally allowed
in the length and ½ inch in the width above the
correct sizes. The mode of plating in general
use is what is termed inside and outside strakes,
Fig. 615.—Modes of Plating. the inside strakes are placed directly against the
plate. c, Liner. D, Frame frames, while the outside overlaps the two adjoin-
ing ones, the space between the outside strakes
and the frames being filled up with liners of the same thickness
as the plates, thus effectually combining the shell plates with the
frames. Another method in modern practice is to place all the
plates directly against the frames, the longitudinal joints being
butted instead of lapped, thus lining pieces are not required; all
these flush longitudinal joints are covered with strips externally.


A,
C
D
Inside plate. B, Outside
IRON SHIPBUILDING.
871
This plan has the advantage that the vertical strains to which a
vessel is subjected come on the butts instead of sheering the rivets.
Some take objection that with this mode of construction the strips
are deficient in strength; but various ships constructed in this way
have given every satisfaction. Due attention being paid to the
quality of the strip iron, we consider this plan by far the best devia-
tion from the usual mode of plating vessels.
THE FRAMEWORK.
The frames of a ship are bent to the proper shape per drawing,
or to wood templates prepared for that purpose; with the former
the lines representing the contour of the frames are transferred from
the moulding loft to a large board prepared for the body lines, the
surface of which receives a coating of lamp black and thin size,
and after the lines are delineated with French chalk they are cut in
with a scrivor, or razing tool, made for the purpose; thus the lines
cannot be rubbed out, and are more easily seen by the workmen.
This board is taken into the workshop and placed near the level-
ling or bending slabs, which are of cast iron, pierced with holes
every 6 inches or so apart. It is convenient, likewise, to show the
position of the plate edges, diagonals, heights of floors, beam ends,
&c., which may be taken as the bevelling points, on the body
drawing, before it is taken into the workshop. The bending of the
frames may now be proceeded with. To facilitate that operation a
bar of soft iron is bent to the particular frame, having the bevelling
points marked with chalk; it is taken to the bending slab and the
line of frame drawn on the slab with chalk; pins are then inserted
in the holes, and small blocks are prepared with suitable wedges
to make up the distance between the line and the pins fixed in the
nearest holes. The heated angle-iron bars are then laid on the slab,
and bent round to the curve with lever power, hammers, &c. The
bending and bevelling is finished before the bar is reduced in
temperature. Care must be taken that the bevelling is proceeded
with cautiously; the blows should not be so heavy as to cause the
angle iron to open at the root, and especial care must be taken that
the back of the angle iron is quite straight, as it is very liable to work
hollow. Some builders prefer twisting the angle bars; by this
method the sides of the angle iron are always at right angles to the
plating, no doubt giving greater strength, but in most ship-building
872
MODERN STEAM PRACTICE.
yards in this country it is preferred to bevel the frames. The
frames, when somewhat cold, are then taken to the drawing board
and adjusted as occasion may require. When templates of wood
prepared as skeleton frames are used for bending the frames to,
instead of working off the drawing, one of these templates may
suit for a number of frames amidship. With this plan no bars of
iron are required to transfer the form of the frame on to the slab,
as the wood template answers this purpose, and the bending is
proceeded with as before; but as these templates are liable to get
damaged and twisted, the former plan of bending the frames or
adjusting them to the drawing is to be preferred, taking into con-
sideration that the frames can be cut to the exact line of sheer as
per drawing, whereas there is some risk with the templating system.
The plate edges, heights of deck beams, ribbands, &c., are notched
in, and on, the frames, and the rivet holes for the fastenings of
plating are set off, the pitch varying from six to eight diameters
according to the size or width of the plates. The rivets for the
reverse bars are likewise marked off, the usual pitch for the rivets
being eight diameters, as for the frames; care should be taken that
the transverse sections of the frames are not reduced by placing
two rivets in the same line. The punching being completed the
frame is then tried on the drawing, to adjust any irregularity, as the
strain from the punching is liable to alter the form slightly. Some
prefer punching the angle iron prior to bending, and in all cases
it should be punched from the back, thus forming a countersink,
which, being filled with the rivet, makes very secure work. The
holes in the frames for the rivets in the plate edges are generally
drilled when the frame is in position. The floor plates are then

B
A
Fig. 616.-Floor Plate.
A, Floor plate. B, Reverse angle iron. c, Frame.
prepared, and are ordered to the required taper, and bent to the
curve. When a centre-line keelson is fitted, the plates for the floors
are in two pieces, but when bar keels are adopted the plates are
welded together, the welds being placed on opposite sides of the
IRON SHIPBUILDING.
873
centre line, in the frames adjacent. In some examples the floors
are ordered in three plates, and welded together, the centre plate
being cut out to the form required, while the two other plates are
bent to the curve. It is not thought necessary to alter the shifts in
adjacent frames with this method. After the plates are finished
they are laid on the frames, and all the holes marked off for
punching, as well as the holes for the reverse angle irons. The side
keelson's holes are likewise set off and the position of the water-
courses, or limber holes, marked. The holes for the reverse angle
iron are marked from the floor plates after they are punched, the
reverse irons being previously bent; the holes in the fore and aft
flanges for taking the ceiling may be punched, as likewise all other
holes where the reverse bars are bent. Some use a batten fitted
with thin pieces of iron, or zinc, which can be adjusted to the holes
in the frames and floor plates, and then transferred to the reverse
bars. The frames, floor plates, and reverse angle irons are then
rivetted together at the side of the ship before they are raised in
position, but some builders lay the frames across the keel before the
rivetting is proceeded with. It is thought, however, that with this
process the frames are liable to become unfair in the act of rivetting
up, but we consider that when the frames are securely held in
A
C
C
C
position the impact of the rivetting
hammers can but little affect the
form, more especially with heavy
scantling. Prior to this operation
the keel is got ready; it is generally
fitted temporarily on the side of the
slip, with all the scarphs for stem and
stern post adjusted and all the rivet
holes drilled. The frame stations are
marked on, and the keel is then re-
A, Cap piece of oak. B, Wedges. cc, Red moved to the keel blocks, on which
pine. DD, Slabs.
the vessel is built, and all the scarphs
rivetted up. The keel blocks of red pine should be kept pretty
high, more especially with flat-floored ships, so as to enable the
workmen to get under the vessel for rivetting and caulking. The
keel blocks should be spaced about 7 feet 6 inches apart, having a
double block between every second and third block alternately.
This is required to admit of shifting any of the blocks to get at the
work without the danger of the vessel settling down, which of course

Fig. 617.-Keel Blocks.
874
MODERN STEAM PRACTICE.
depends in a great measure on the nature of the soil, some soils
requiring fore-and-aft logs for the blocks to bed upon; and in all
cases it is preferable to use this precaution at the after end of the
vessel.
The stem and stern posts are in the meantime being forged and
bent, but the work amidships may be proceeded with before the
stem and stern posts are placed in position. Staging is erected on
standards placed all round the space that is to be occupied by the
hull of the ship, and a gunwale harpin is put in place and secured
with stiffening cross spals attached to every sixth frame, all the
frame stations being marked thereon, and as the frames are hoisted
in position they are properly secured at heads and heels, and are
then made quite fair by ribbands and harpin, secured with temporary
bolts and nuts to the framing.
The deck beams are of various sections, as shown below. When
bulb iron is used with double angle irons or solid flange it is bent and
TITSTE
TTITIS
Figs. 618-629.-Sections for Deck Beams.

shaped to the curve of the deck by hydraulic or steam presses; or screw
presses worked by hand may be adopted, the beam being perfectly
cold. The ends are heated and bent down to form the knees, the
top corner being filled up with a plate welded on. Some prefer split-
ting the plate at the end and then turning it down to form the knee,
the space being filled up with a plate welded to the knee, or a vertical
plate is welded on, leaving a triangular hole in the knee; another plan
is to rivet a plate to the knee after it is bent instead of welding a
plate on, but we certainly consider the welded knees preferable, both
as regards strength and appearance. When angle irons are worked
on the top edge the holes of one template those of another, and the
rivetting is done by the machine, although some builders prefer
hand rivetting as it is not so liable to alter the curve. The beams
IRON SHIPBUILDING.
875
are cut to the proper length and bevel by templates taken from the
drawing, and in no instance should the template be applied to the
frames in the ship. The position and number of the fastenings are
set off both in the frames and beam knees by templates. Some
builders dispense with the template, the beam being brought to and
laid on the frames, in the same way as the floor plates which are
first secured to the frames, and all the holes being punched in the
frames for the beam knees, they are simply templated off, punched,
and then rivetted up at the same time as the floors, &c. Thus the
frames and top beams are lifted into position entire, at least when
the weight is not excessive, the lower deck beams being placed in
after the frames are in position. The holes for the bolts of the deck
planking are drilled and punched by hand (technically termed
"beared)," after the frames are all rivetted up, due attention being
given as regards pitching these holes, so as to have a good hold of
the planking, the bolts being kept free from the edges of the
planking, and thus better work secured.
A
E
E
C
D
Figs. 630, 631.—Deck Fastenings. A, Wood screw.
B, Bolt and nut. c, Head of bolt. D, Plate. EE, Deck.
The deck fastenings are
arranged in a variety of
ways. "Lloyd's" require
two bolts through each
beam and plank when the
planks exceed 6 inches in
width, one of them may
be a short wood screw
bolt when the planks are
not wider than 8 inches.
Two wood screws are
sometimes adopted, in
other cases bolts are

driven from above or below, with proper nuts for screwing tightly
up, and as before stated one of these fastenings may be a wood
screw, with the head bearing on the angle iron or solid flange of
the deck beam. In other fastenings a hollow nut is tapped into the
deck plating on the under side, into which passes a bolt having a
round head with two notches cut out for receiving a tool for screwing
it into the nut from the upper side of the planking, a washer
being interposed in the holes made in the deck plank, between the
wood and the head of bolt, the hollow nut prior to screwing up
being filled with tallow or other substance to make the threads per-
fectly water tight. The holes in the deck planking for receiving
876
MODERN STEAM PRACTICE.
the bolt heads, or nuts, are filled up with a plug of wood driven hard
in, the plug being previously dipped in paint.¹
The transverse water-tight bulkheads should be temporarily fitted
to the frames to which they are secured before the frames are put in
position. In bulkheads the plates are generally so arranged that they
lie lengthways across the ship, there being vertical stiffening angle
irons for small vessels, and for vessels of large tonnage stiffening
angle irons running vertically

on one side of the plating
with others horizontally on the
other side, the plating being
arranged for lap jointing, with
liners between the stiffening
bars and the plates, having
the corners of the plates ham-
mered to a thin edge where
the vertical and horizontal
joints cross each other. As it
is obvious that when a vessel
grounds at or near the bulk-
heads severe shearing stress
comes on the rivets, to meet
this the plates have been ar-
ranged so that the vertical joints
are lapped for single rivetting,
D
C
B
B
B
A
B
" •
A, Plating. B B, Angle irons.
D, Frame. c, Deck-beam angle iron.
and the horizontal joints butted Fig. 632.— Bulkhead.
or lapped with strips single
rivetted. The vertical stiffening bars are worked directly on the plates,
no liners being required, horizontal stiffening bars are arranged in
same manner as before on the opposite side of plating; with this
arrangement the shearing stress is taken on a greater number of
rivets in the vertical seams. In some yards it is preferred to fit the
bulkheads by means of a template fitted to the frames after they are
in position. The modes of connecting bulkheads to the side of the
hull plating are various. Lloyd's and the Liverpool rules require
double angle-iron frames with the plates between, or the single angle-
iron frame may be adopted, with bracket plates on each side rivetted
to the bulkheads and to the side of the ship, thus distributing the
¹ Of course the hull at this stage is not sufficiently advanced for receiving the deck
planking.
IRON SHIPBUILDING.
877
B ●
strength to the adjacent plating, which greatly tends to preserve the
rivets from fracture, the vessel having a certain flexibility between
the bulkheads, and unless provision was made to take the strain from
the bulkhead on to the adjacent plating the rivets in the angle frames
must receive the full stress, and consequently fracture and great
leakage would be the consequence. To carry out this connection
more fully belts have been worked all round and connected to the
frames with a single angle iron on each, the bulkheads being con-
nected with an angle iron to the belt. By this means the bulkhead
is not held so rigid, the belt yielding directly to the strain, thus
forming, as it were, an expansion connection across the ship, which
is made perfectly water tight by caulking the edges of the angle
irons. The frames may now
be considered to be all rivet-
ted and in position, properly
horned and plumbed, and se-
curely fastened, the ribbands
and harpins put up, and all
the frames "faired." The in-
side work of the ship having
been prepared, such as centre
and side keelsons, intercostal
and stringer bars bevelled,
can now be placed in position,
the stringer plates being fitted
to the frames, and marked and
scored out between the frames.
(Sometimes a mould is made
which serves for the stringer
plates and for cutting the
wood waterway.) The deck
beams may now be put in and fastened, and the deck work can
be proceeded with. As it is of the greatest importance to pre-
serve the continuity of the keelsons, they are carried through the
bulkheads, and are made perfectly water tight by working an angle
iron all round, which is rivetted to the bulkhead, and the edges of
the angle iron caulked. This plan is likewise adopted with all
stringers passing through the bulkheads, the keelsons being gener-
ally of a box form, or bulb iron, with angle irons rivetted thereto,
while the stringers are formed of plates and angle iron, rivetted on

B
•B●
B●
B
•в
Figs. 633-635-Modes for making the Keelsons water-
tight at Bulkhead. A A, Keelson. BB, Angle irons.
878
MODERN STEAM PRACTICE.
one or both edges, and in some vessels double angle irons, placed
back to back without plates, are adopted.
PLATING AND RIVETTING.
With regard to the plating of the vessel, the disposition of butts
commonly adopted is known as the diagonal system, there being
always two strakes of plates between two vertical butts in the space
between two frames, the butts being of course alternately on the

n
1
B
A
n
Fig. 636.-Diagonal System of Plating.
A A, Outside plating. B B, Inside plating.
CC, Frames.
outside and inside plating or strakes. Another mode of plating has
four plates between the vertical butts in the space between two
frames, the butts being on alternate inside and outside strakes. With
another method sometimes adopted there is only one plate between
two vertical butts, thus the vertical butts of the inside strakes are
in one line and of the outside strakes on another vertical line, the
butts of the alternate strakes being placed at the middle of the plate
above and below, the former (Fig. 636) having five frames on each
plate, and the latter (Fig. 637) six frames, while the butts on alter-
nate strakes are not less than two frames apart. Some builders
order the plates so as to make the distance between the outside
edges of equal breadth with the outside strakes, while others make
the strakes of equal breadth, thus making the distance between the
edges less than the breadth of the outside strakes; it must be
IRON SHIPBUILDING.
879
understood, however, that with the latter method the section through
a line of butts will be stronger, and on that account alone should
always be preferred. When double rivetting is adopted the holes
for the rivets are either arranged zigzag or the chain method is em-
ployed (see Fig. 567, p. 806), the breadth of the laps being five and
C
C

M
B
B
M
A
A
द
1
Fig. 637.-Intermediate Break-bond System of Plating.
A A, Outside plating. BB, Inside plating. cc, Frames.
one half times the diameter of the rivet; while some builders adopt
six diameters as the breadth of the lap, the rivet holes being one
and one sixth diameters from edge of plate. For single-rivetted
laps the breadth varies from three and one quarter to three and one
half diameters. The butt straps are arranged for double-chain
rivetting (see Fig. 567), or the zigzag method may be adopted, and
it is imperative that the fibre of the iron must run in the same
direction as the hull plates, the butts being cut from plates having
the fibre in the line of breadth of butt straps. In some very long
ships the butts of the sheer strakes are quadruple chain rivetted, for
one half the length amidships. The butts of the inside strakes
extend the whole width of the plates, as likewise the butts for the
outside strakes take the edge seam of rivets, the ends of the butts
being joggled to bear on the plates; in some recent examples the
butt strap has been fitted between the edges of the inside plates,
having a covering plate taking the edge rivetting and butt strap.
In outside sheer strakes the butt strap and liner to the adjacent.
frame is made in one piece; this method is more especially required
in parts subjected to great strain, such as are at the stern near the
propeller. The rivets commonly adopted have pan heads, and
are formed with a conical part under the head to fit into the cone
880
MODERN STEAM PRACTICE.
The
A
D
C
that is formed in the plate in the act of punching, these cones
tending greatly to increase the strength of the joint, for it has been
known that when the heads have been reduced by corrosion the
countersinks held good. The rivet holes should be punched from
the faying surfaces of the
plates; then the narrow
parts of the holes are at
the joint surfaces.
holes in the outside plat-
ing are, however, counter-
sunk much greater in dia-
meter, and in some cases
the countersink is equal to
the thickness of the plate,
while in others a part is
not countersunk. We cannot pass over this part of the work
without expressing a strong opinion that the ordinary form of
countersink and head for uniting the plates together is the best that
could be adopted, when it is known that the bilge water in a ship
rapidly wears off the heads if not covered with cement, more
especially if there is any grit rolling forwards and backwards with
the water; we are of opinion, however, that the plates should be
countersunk on both sides,

Fig. 638.-Rivet and Countersink.
A Rivet. BB, Plates. c, Countersink formed in punching
D, Countersink done by a drill.

C
A
B
and that the countersink
should not spread out too
much, for we consider that
when the iron is forced out
to fill a large countersink
it is greatly distorted, an
acute angle is formed at
the middle of the rivet, and
its strength is thus im-
paired. We would suggest
the form of rivet and coun-
tersunk hole as shown in Fig. 639; part of the head is retained
to resist the impact of the rivetting hammers, and there seems
to be but little doubt that if the head is reduced by corrosion the
countersink will hold good. Of course the labour of counter-
sinking the plates would be doubled as compared with the present
method.
Fig. 639.-Proposed Form of Rivets and Countersink.
A, Rivet. B, Conical countersink. c, Curved counter-
sink. DD, Plates.
IRON SHIPBUILDING.
881
In commencing the plating of a ship the inside strakes are the
first to be laid on, according to the arrangement made on the
model, this being the only guide to go by, forming, as it were,
the true miniature vessel. The lowest strake next the keel is
usually an inside one, and is laid on first, two inside strakes are
laid on, and then the outside one is worked over them. The
inside strakes are rivetted as the plating proceeds, the harpins
being removed where the outside strakes come, while the structure
is shored under the inside strakes, and so on until the frames are
plated all over.
The original method of putting the plates in position and then
marking them prior to punching is still adopted, thus the one strake
acts as a template for the adjoining strake, and so on. Some
builders prefer templating the plates: light wood battens, with cross
battens, are applied to the plating already placed in position,
these templates corresponding to the length and breadth of plates,
the cross battens also being pitched according to the distance be-
tween the frames; when these are applied to inside or outside strakes
the edge holes and holes in frames are marked through the holes in
plates from the inside by means of a plug of wood with a slight
hollow at the end, which is dipped in prepared whiting, and which
leaves a white ring on the template. When all the holes are marked
off the template is removed and the position of the holes transferred
on the plate by means of a "reverser," which simply consists of
two thin pieces of tough wood, kept apart with a block at the end
to which they are secured with screwed nails; a round hole is made
in the top piece and a plug of wood placed on the under side of the
bottom piece, this plug is made slightly hollow at the end, which
being dipped in prepared chalk forms the marker. The plate to be
marked is placed on a slab or bench for the purpose, the template
is laid over it and raised sufficiently above the plate to allow the
forked marker, or reverser, to be placed between the plate and tem-
plate, the end of the plug nearly touching the plate; then the work-
man places the hole in the reverser above the ring of chalk on the
template, and presses down the plug, which leaves an impression on
the plate corresponding to the holes in the plating already placed
on the frames, thus all the holes are transferred from the template
to the adjoining plates, and then they are taken to the punching
machine.
The plates are then sheared or planed on the edges, and the butts
56
882
MODERN STEAM PRACTICE.
planed according to the lines required, and which are marked
from the template, and after the punching and fairing the edges
and butts are completed, the proper curvature is then given to the
plate by passing it through the rolls, a mould being used for that
purpose.
Some templates are formed of wrought-iron strips jointed together
and secured with cross slotted bars, having movable pieces for
taking the holes in the frames; with this method a reverser is not
required, as the strips are fitted with separate pieces all bolted
together, which can be expanded or contracted at pleasure, the
strips and cross movable pieces being pierced with holes represent-
ing the holes in the plates already placed on, as likewise the holes
in the frames. A very convenient form of template is a simple
sheet of fine wire-gauze distended on a frame of wrought iron, the
holes being marked on the gauze in the usual manner with a wood.
plug dipped in prepared whiting, and transferred to the plate by
means of a stiff brush applied through the gauze.
The liners between the frames and the outside strakes are tem-
plated when the plating is fixed, a wood template being used for
that purpose; the holes are marked upon it through the holes in
the plates, and then transferred to the liners; the lining pieces after
they are punched are bent to the curvature of the frames, and are
then driven in between the frames and the plates and fixed in
position. The butt straps are templated from wood templates,
or from the plates.
Where difficult plating is required, as at the stern, around the
boss formed on the stern post, a frame of wrought-iron rods welded
together is bent to the shape the plate requires to take, and a block
is constructed of bent angle irons, thus forming a bed for fitting
the plates to prior to placing them in position, which being done,
the holes are then marked off and drilled. The iron for these
plates requires to be of the best quality, as some of the curves are
very difficult to work on the plates without cracking them.
Where the labour of supplying the platers with plates in the
required positions is not performed by cranes running on rails over-
head, as in some yards fitted with covered sheds, the work is done
by manual labour, a plater having a number of labourers for carry-
ing the plates, the number varying according to the size and weight
of the plates. Some builders allow one man to each hundred-
weight, or from four to six men are employed; but this of course
IRON SHIPBUILDING.
883
depends on the position of the plates. After a considerable portion
of the plating is placed on the frames men proceed to close up the
joints, and fair any holes that are out of truth; this is done by
riming them, after which the rivetting may be proceeded with.
Two rivetters, one holder-up, and one and sometimes two boys, are
employed in this operation.
Below the water line the points of the rivets are left rounded,
and above that they are all flush with the plates, the heads of the
rivets being laid up, or hammered all round the edges by the
holder-up. The caulking and rivetting proceed simultaneously,
and the closeness of the joints is ascertained by trying to insert the
thin edge of a knife or other instrument made for that purpose.
As soon as the rivetting and caulking have been passed by the
surveyors, the painter proceeds to give the finished portion a coat
of paint to prevent oxidation setting in.
After the hull is rivetted the rivet heads at the bottom are
filled in with cement flush with the plates, and the whole hull then
receives two coats of red-lead paint before the vessel is launched.
The various fittings in the hold, deck work, top sides, &c., are
finished as the building of the vessel advances; and the rudder
and in some cases the lower masts are fitted to the ship before
launching.
THE LONGITUDINAL SYSTEM OF FRAMING.
In the longitudinal system of framing (see Fig. 648, p. 896), the
ship is divided by as many transverse water-tight iron bulkheads
as the practical use of the ship will admit, and there should be at
least one bulkhead for every breadth of the ship in her length. Thus
a ship eight breadths to her length should have at least eight trans-
verse bulkheads.
Between these bulkheads are placed partial bulkheads, or the
outer rims of complete bulkheads, with the centre parts omitted, so
as to form a kind of continuous girder running transversely all
round the ship, and not interfering with stowage.
From bulkhead to bulkhead longitudinal iron beams or stringers
are built along the centre of every plate of the skin, so giving each
strake of plates the continuous strength of an iron beam, one por-
tion placed at right angles to another. This longitudinal beam or
stringer forms one continuous scarph across all the butt joints of the
884
MODERN STEAM PRACTICE.
plates, hitherto their weakest parts, and diminishes the strain on
the rivets of the joints by the help of a line of rivets and angle irons
along the centre of the plate.
The superfluous iron left after this work was formerly used in ribs.
It is now made into a continuous iron deck, mainly carried by the
bulkheads and by longitudinals under it, and it is believed this iron
is infinitely better applied in a deck than in ribs fastened to the skin.
TABLES OF COMPARISON BETWEEN THE LONGITUDINAL AND TRANSVERSE SYSTEMS.
LONGITUDINAL SYSTEM.-Minimum Section of Metal, midship.

Total.
Rivet
holes.
Effective.
sq. in.
sq. in.
sq. in.
Keel plate,
...
28.29
2'4
25.89
From keel plate to upper part of bilge and
sheer strake,
251.6
17.0
234.6
...
From upper part of bilge to sheer strake,
Webs,
182.4
12'0
170'4
...
...
...
221.87
19'2
202.67
Deck webs,
Extra shelf,
Iron deck,
T-iron under deck,
Gunwale angle iron,
82.8
...
...
3.5
79°3
28.0
...
...
...
...
...
...
24'0
8.0
552
5'0
23°0
5'0
19'0
...
...
2.25
5'75
...
...
15 '0
2.5
12'5
841.96 68.85 773'II
Deduct for seven butts single rivetted, two butts doubleĮ
rivetted, butts of iron deck single rivetted,
Total square inches,
TRANSVERSE SYSTEM.-Minimum Section of Metal, midship.
124'0
...
649'II

Sheer strake,…..
Garboard strakes,
From garboard to upper part of bilge,
From upper part of bilge to sheer strake,
Centre keelson,
...
...
...
Angle iron for do.
...
...
...
Side keelsons and angle iron,
Bilge stringers,
...
Hold do.
...
Upper deck shelf,
...
Angle iron for do.
...
Deck stringers,
...
Rivet
Total.
Effective.
holes.
::
sq. in.
31.6
sq. in.
sq. in.
5.6
26'0
208.0
15 '0
193'0
180°0
6.8
173.2
...
...
52'0
2.8
49'2
...
...
10'13
0'75
9:38
13'5
I'5
I2'0
40'5
4.5
36'0
...
...
14'0
2.25
II 75
14'0
:::
2.25
II'75
27.0
0'75
26.25
...
7'0
1'25
5 75
12'0
...
1'25
10'75
10'5
I'5
9'0
620'23
46°2
574'03
...
...
54'0
...
...
520'03
Flat plate in centre keelson,
Deduct nine butts double rivetted,
Total square inches,
IRON SHIPBUILDING.
885
DIFFERENCE BETWEEN THE LONGITUDINAL AND TRANSVERSE SYSTEMS.
In the skin,
...
Iron used in the General Structure.
In transverse internal strengthening,
In longitudinal strengthening,...
Transverse system. Longitudinal system.
IIO tons.
IIO tons.
40"
130
40
""
130
It will be seen from the foregoing tables that the ultimate strength of
these two ships to resist a strain tending to break them across, or
resist hogging, is as 650 to 520, or about 25 per cent. is gained by
the longitudinal system, and probably 18 per cent. of additional
strength is gained when a ship of the same tonnage is plated accord-
ing to Lloyd's Rules intending to occupy the highest grade. The
advantages claimed for the longitudinal system of framing are-
greater strength and simplicity, and the better distribution of the
strength from the transverse bulkheads by means of the longitudinals.
The support given to the plating from the longitudinals and angle
irons on each strake crossing the butts, and being securely rivetted
to the plating, materially strengthens these weak parts, to which is
added the facility in construction for making the frames in place
and bending the angle irons to the easy curves required by the
system, and also the ease and convenience in stowing cargo, clean-
ing and painting, and the prevention of the deterioration of the
inside plating from the rolling about of the bilge water.
The additional strength in the bow framing is another very im-
portant point, as the longitudinals form, as it were, a number of
breasthooks that take the strain in the event of collision in a direct
line through the vessel; this is important in the mercantile marine,
and all-important in ships of war. It has been argued that with
the longitudinal system of framing a greater area of bottom plating
is not so well supported as with the vertical system of framing; no
doubt this is quite true, but at the same time it is evident that when
a vessel takes the ground the damage done to the vertical system is
very great, whereas in the longitudinal system a hole or indentation
is only made in the plates, or at least there is not so much tendency
to rupture the partial bulkheads, simply because there are fewer of
them; and it is evident that when a double bottom having an inner
skin is adopted, the outer skin may get damaged while the inner
one remains intact. There can be no doubt that great skill is required
in the design, and greater accuracy in the workmanship and con-
struction with the longitudinal system; but there is no doubt that
886
MODERN STEAM PRACTICE.
with skilled workmen properly trained, the system offers consider-
able advantages in point of economy of material and workmanship,
more especially in fine long bows, where it is very difficult for large
bodies of men to work conveniently, and where, as in some in-
stances, expedition is of the highest importance.
The following description of an iron auxiliary screw clipper of
the 600-ton scale, 845 tons B.O.M., classed A 1 twelve years at
Lloyd's, gives a farther illustration of the system:—
LONGITUDINAL SYSTEM.
Scantling of the iron hull of a ship built
on the 600-ton grade longitudinal principle,
to class A 1 for twelve years at Lloyd's :—
I
Dimensions of Ship.
...
Length,
Breadth,
Depth at side,
Depth in hold,
190 ft. 0 in.
30 O
18
18
""
O
3
Tonnage, N.M., under 700 tons.
Outer plating.
Specification.
Keel strakes, 11 inch.
From keel strake to upper part of bilge,
8 in.
From upper part of bilge to sheer strake,
18
2 in.
Sheer strake, 18 in.
All longitudinal seams single rivetted.
Butts of sheer strake double rivetted.
Five bottom webs, 18 in. deep by ½ in.
Twelve side webs, 13 in. deep by ½ in.
Angle iron, 3½ × 3½ x ½ in. and 3×3×
½ in.
Iron deck, 4 in. thick; shelf, 2 ft. 6 in.
wide, and ½ in. thick.
Bulkheads, five water-tight, 34 in., stiffened
with 3×3×½ in. angle iron.
Ten partial bulkheads, 13 ft. apart.
TRANSVERSE SYSTEM.
Scantling of the iron hull of a ship built
under Lloyd's Rules for the 600-ton grade,
to class A I for twelve years.
Dimensions of Ship.
Length,
Breadth,
Depth at side,
...
Depth in hold,
...
190 ft. 0 in.
30",
O
18
O
17,,
O
""
Tonnage, N.M., under 700 tons.
Keel, 7 × 234 in.
Garboard strake, in., longitudinal seams
double rivetted.
10
From garboard to upper part of bilge, 18 in.,
double rivetted.
From upper part of bilge to sheer strake,
9
in., longitudinal seams single rivetted.
Sheer strake, 18 in., upper edge double
rivetted.
All butts double rivetted.
Frames, 4×3× in.; spaced 18 in.
18
6
16
Reversed angle iron, 3× 234 × in.
Floors, 18x in.
Deck beams, 7× in., with double angle
irons on top edge.
Centre keelson intercostal, 18 × in., with
double angle irons.
Flat plate on top of centre keelson, 21 × ½
in.
Side keelsons, 12 x in., with double
angle irons.
Bilge stringers, double angle irons, 5 × 3 × ½
in., back to back.
Hold stringers, double angle irons, 5 × 3 × ½
in.
Upper deck shelf, 24 × in.
Angle iron for do., 5 × 3 × ½ in.
Two deck stringers, 12 × ½ in.
Three water-tight bulkheads, 3% in., stif
fened with angle iron 3× 3 × ½ in.
IRON SHIPBUILDING.
887
SAILS, MASTS, ETC.
In vessels propelled by steam power the disposition of the sails
is not of primary importance; but it is evident that when a vessel
is driven through the water simply by wind power a proper dis-
position of the sails becomes of the highest importance. To illus-
trate this subject we select an example of a first-class merchant
ship (Fig. 641), having a register tonnage of 1554 tons, and of the
following dimensions:-Length of keel and fore rake 240 ft., length
on load line 237 feet, breadth of beam 38 feet, depth of hold 23 feet,
area of midship section to load line 727 square feet, area of sails
64,500 square feet, draft 21 feet 10 inches, with a freeboard of 4 feet
9 inches.
The position of the masts varies: in ships having fine forward
lines the fore mast should be placed nearer the centre of the vessel
than in those having full bow lines. With fine forward lines the
masts should rake or incline aft, this disposition easing the pitching
of the vessel, although by no means improving her sailing qualities;
this is evident, as the wind cannot have so much power on the sails
when lying at an angle as when upright. To set off the position of
the masts we have the load water line as the base to work from, the
point on this line half way from the after end of the stern post
being the point we start from. The fore mast in first-class sailing
vessels will be so much forward of this point, viz. the centre of the
length on the load water line, and the main and mizen masts so much
aft of it. Taking the length of the load line at 237 feet, and regard-
ing the centre of displacement as located about the centre of vessel,
the figures 28, 052, and 32 may be used as multipliers for finding
the position of the fore, main, and mizen masts with regard to the
centre point, thus—
237 × 28
237 × 052
237 × 32
=
66.3 for fore mast,
= 12.3 for main mast,
=
75.8 for mizen mast,
this giving the points on the load water line for a first-class sailing
vessel. The naval architect must study the form of the ship, and
the peculiar trade the vessel is destined for, as these positions may
vary with different forms of vessels. It is usual to give the fore
mast a certain rake aft (but less than the main and mizen masts)
to ease the vessel forward, more especially with a fine-bowed vessel;
but the main and mizen masts should have more rake, for the wind
888
MODERN STEAM PRACTICE.

Fig. 641.-Rigging Plan of Merchant Ship, to illustrate position of Sails, Masts, &c. Scale % inch = 6 ft. nearly.
IRON SHIPBUILDING.
889
acts most advantageously on all the sails, when close hauled, when
the masts are thus separated.
The centre of effort of all the sails should be located immediately
over the centre of displacement. The centre of effort of each sail,
as likewise the area of each, must be found separately; then by
measuring on the plan forward, from a vertical line drawn up from
the after end of the stern post to the centre of effort of each sail as
per scale, multiplying those distances by the area of each sail, and
dividing the result of the whole sum of these products by the total
area of canvas, we obtain the longitudinal distance of the centre of
effort from the after end of stern post. Again, by measuring ver-
tically to the centre of each sail from, say, the load water line, and
multiplying these distances by the area of each sail, the sum of
these products, divided by the total area of canvas, gives the ver-
tical axis of the centre of effort; and when a line is drawn at right
angles to the load water line through the longitudinal distance as
found, and another drawn horizontally through the vertical distance
from the load water line, then the point where the two lines cross
each other is the centre of effort of all the sails.
To facilitate the management of the upper sails, the top sails and
sometimes the topgallant sails are divided in two. The diagram
Fig. 641 shows a three-masted ship with her top sails arranged in
this manner, but in some cases this arrangement extends to the
topgallant sails. When the ship is of large size it is found that by
giving an additional mast the area of the individual sails and the
size of the spars can be reduced, so that a four-masted ship can be
worked by about the same number of men as a three-masted vessel
of smaller tonnage.
PROPORTIONS OF MASTS, YARDS, ETC., FOR MERCHANT SERVICE.
As the breadth of a ship forms the standard of the vessel's stability,
the height of the masts must be in proportion to the breadth, and
so also the diameters of the masts can be deduced from the breadth.
We give the following rules for finding the masts, &c., of a ship,
premising, however, that there are various opinions held by rigging
shipmasters and others as to sizes of spars, and these rules are
not therefore necessarily uniform in practice. Where double top sail
and topgallant sails are used there will be additional yards for these
sails, having a size suitable to the yards above and below them.
MAIN MAST AND YARDS.—To find the length of the mast, from
890
MODERN STEAM PRACTICE.
the vessel's extreme breadth deduct one-twelfth, and the remainder
multiplied by 2 gives the length of the main mast from the deck
to the head (one-fifth of this gives the length of the mast head from
the upper part of the hounds); add to this length the depth from
the deck to the step, and we find the total length of the main mast;
thus if the vessel's breadth is 25 feet, deducting th gives us
22.91 feet, which, multiplied by 2, gives 45.82 feet from deck, and
say the depth of vessel is 16 feet, or otherwise the depth from deck.
to the step, and we have 45·82+16=61·82 as the total length.
12
To find the diameter of the mast at the deck, multiply the
reduced breadth by the constant 75, this will give the diameter in
inches at the deck.
...
22′91 × '75 = 17·18 inches diameter.
One-eighth less gives the diameter at hounds,
One-eighth less than the diameter at hounds gives the diameter above hounds,
One-eighth less than the diameter above hounds gives the diameter at head,...
15'02 in.
13*15 in.
11°41 in.
Main top mast.—To find the length of the main top mast, mul-
tiply the reduced breadth by the constant 15, thus 22'91 feet X 1.5=
3436 feet, the total length, one-seventh of which is the length of
head, that is to say, 34'36÷7=49 feet.
To find the diameter at fid, multiply the reduced breadth by the
constant 5.
22'91 × 5 = 11°45 in. diameter.
One-eighth less than the diameter at fid equals the diameter at hounds,
Three-fourths of the diameter at hounds gives the diameter above hounds,
One-eighth less than the diameter above hounds equals the diameter at head,...
2
IO
in.
7.5 in.
6.6 in.
Main top-gallant mast.—To find the length of top gallant mast,
divide the length of the top mast by 2: 34:36=17.18 feet length, one-
sixth of this equals the length of head, that is, 17·18÷6=2·8 feet.
To find the diameter at fid, divide the diameter of the main top
mast at fid by 2: 11'49-574 inches. One-eighth less than the dia-
meter at fid equals the diameter at hounds = 5 inches.
If, in addition to the top-gallant mast, there is a royal mast, the
length of the top-gallant mast becomes from heel to sheave hole
145 feet; the length of royal mast is two-thirds of the top-gallant
mast, that is, 9'66 feet, length of the pole head 6 feet, diameter in
the heel, one-eighth less than diameter at hounds, equals 44 inches,
at the head 4 inches, at the pole head 3.5 inches by 3 inches.
Main mast yards-main yard. To find the length of the main
yard, multiply the reduced breadth by 2; thus 22·91 × 2=45·82 feet.
IRON SHIPBUILDING
891
To find the diameter, multiply the half length by the constant 5,
thus 22.91 X5=1145 inches diameter, one half the diameter at
slings as found gives the diameter at yard arm, 11:45÷2=5'72
inches. For the stop at each yard arm allow I foot for every 20 feet
of the yard's length, that is, 45·82÷20=2·29 feet.
Main top-sail yard.—To find the length of the main top-sail yard,
multiply the reduced breadth by 15 as a constant, and the product
is the length: 22′91 × 1'5=34'36 feet. The diameter in the slings
equals two-thirds the diameter of main yard, 1145 × 2÷3=7·63
inches. One half of this gives the diameter at yard arm, or
3.8 inches. The stop at each arm, I inch to the foot of yard's
length, or 2.8 feet.
Top-gallant yard.-Length of the top-gallant yard equals the
reduced breadth, or 22'91 feet. One half of the diameter of the main
yard gives the diameter at the slings, or 5.72 inches. Diameter at
yard arm equals one half at the slings, or 2·86 inches; for the stop
at each yard arm allow I inch to the foot of yard's length, or
1.6 feet.
Royal yard.-Length of the royal yard equals two-thirds the
length of the top-gallant yard; thus 22′91 × 2÷3=15.27 feet long.
The stop at each arm I inch to the foot of yard's length, or 1.27
feet. Diameter at the slings two-thirds the diameter of top-gallant
yard, 5·72 × 2÷3=3.8 inches. One half gives the diameter at yard
arm, or 19 inches. The top I inch to the foot of yard arm, or
I'27 feet.
12
FORE MAST AND YARDS.—To find the length of the fore mast from
the deck to the head, from the height of the main mast above the
45.82
deck subtract one-twelfth, thus: = 3.81 and 45'82-3.81=
42 feet. The mast head equals one-fifth of the length, or 8:44 feet
long. To the length of the mast from deck to head add the length
below the deck to step, say 15.5 feet, the result, equal 57.5 feet, gives
the total length of mast. The diameter at deck is one-twelfth less
than that of the main mast.
17.18
=
1'43 and 17.18 – 1°43 = 15°75 in.
12
One-eighth less equals the diameter at hounds,
...
13'79 in.
in.
One-eighth less than the diameter at hounds equals the diameter above hounds, 12
One-eighth less than the diameter above hounds equals the diameter at head,
10.5 in.
Fore top mast.—The fore top mast is one-twelfth less in length
than the main mast, or 31.5 feet, of which the head is 4'5 feet.
892
MODERN STEAM PRACTICE.
The diameter at the fid, 10'6 in.
One-eighth less equals the diameter at hounds,
...
Three-fourths the diameter at hounds equals the diameter above hounds,
One-eighth less than the diameter above hounds equals the diameter at head,
9'3 in.
...
7 in.
6.1 in.
Fore top-gallant mast.—To find the length of the fore top-gallant
mast, divide the length of the fore top mast by 2=15.7 feet, length
of the head 2'75 feet; if the top-gallant mast has a pole the length
of the pole will be 13.3 feet, the length of the royal mast two-thirds
of the fore top-gallant mast, or 8.8 feet; pole head, 4'4 feet.
The diameter of the fore top-gallant mast in the fid is one-half of the diameter
of the top mast, or 5.3 in.
One-eighth less gives the diameter at the head,
Diameter at the royal-mast heel,
Do. at the head,
Do. at the pole head,
...
:
...
...
...
...
4.7 in.
4'25 in.
3'75 in.
3'25 x 2.87 in.
Fore-mast yards-fore yard. The length of the fore yard is one-
twelfth less than the main yard; thus 45·82—3·81 and 45·82—3.81 =
12
42 feet. The diameter in the slings, 10'62 inches; diameter at the
yard arm, 5·62 inches; the stop at each yard arm 1 foot in 20 of the
whole length 2 feet.
Fore top-sail yard. The length of the fore top-sail yard is 315
feet; diameter in the slings, 7 inches; diameter at the yard arm,
3.62 inches; the stop at each yard arm I inch in the foot, in the
entire length of the yard=2·58 feet.
Fore top-gallant yard.-The length of the fore top-gallant yard is
one half less than that of the main, or 21 feet; diameter in the slings
one half the diameter of the fore yard=5.3 inches; the diameter at
the yard arm 2.75 inches, the stop at each yard arm 1 inch in foot
of the length, or I foot 9 inches.
Royal yard. The length of the royal yard is two-thirds of the
top-gallant yard, 21 X2÷3=14 feet. The diameter of the slings
3'75 inches; the diameter of the yard arm 18 inch, the stop at
each yard arm, I inch to foot in length, gives 14 inches.
MIZEN MAST AND YARDS, &c.-To find the length and diameter
of the mizen masts and yards, take one-fifth less than the fore mast;
thus 42=84 and 42-84-336 feet. The mast head equals one-
5
sixth of the length, or 5'6 feet, and with 14 feet from deck to step,
gives 476 as the total length of mast.
IRON SHIPBUILDING.
893
Diameter at the deck,
...
12.75 in.
Do. at the hounds,
...
11.25 in.
Diameter above the hounds, 9.87 in.
Do. at the head,
8.5 in.
The length of the mizen top mast is 25 25 feet,
Mizen top mast.
take 3.6 feet for the head.
Diameter at the fid,
Do. at the hounds,
...
8.5 in.
7.5 in.
Diameter above the hounds, 5'75 in.
Do. at the head,
4'75 in.
Mizen top-gallant mast.-The length of the mizen top-gallant
mast is 105 feet, take 9 feet for the pole head.
Diameter at the fid,
Do. at the head,
...
4'5 in.
3'6 in.
5
Diameter at the pole,
Do. at the head,
...
3' in.
2.5 in.
Mizen yard. To find the length of the mizen yard, take one-fifth
less than the fore yard: 42=84 and 42-84-336 feet. Diameter of
in the slings, one-fourth less than the fore yard, 8 ins.; diameter at the
yard arm, one-half of at the slings, 4 ins.; length of the stop, 1·6 ft.
Mizen top-sail yard. The length of the mizen top-sail yard is
25.25 feet; diameter in the slings, 5.75 inches; diameter at the yard
arm, 2.25 inches; length at the stop, 2 feet.
Mizen top-gallant yard. The length of the mizen top-gallant yard
is 17 feet; diameter in the slings, 4'62 inches; diameter at the yard
arms, 2.25 inches; length of the stop, 14 feet.
Spanker boom.The length of the spanker boom is one and a
quarter of the reduced breadth, thus 22'91 X 125=28.6 feet; dia-
meter at the sheet, 4 inch to the foot of the reduced breadth=
5.75 inches; diameter at the ends one-fifth less=4'5 inches.
Gaff.—The length of the gaff is 22.91 feet; diameter 3 feet from
the mast, inch to the foot of the reduced breadth equals 4'5 inches,
two-thirds of which give 3 inches for the outer end.
Bowsprit.-The length of the bowsprit should be one and a half
times the reduced breadth, 22′91 × 1'5=34′36 feet; diameter in the
17.18
12
bed one-twelfth less than the main mast =143 and 17'18 —
1'43=15.75 feet; diameter at the outer end seven-eighths of the bed,
1575×7÷÷8=13.78 inches; diameter at the heel, 14 inches.
Jibboom. The length of the jibboom should be one and three-
eighths of the reduced breadth, which gives 31.5 feet in length, the
diameter in the cap 762 inches, at the outer end one-eighth less, or
6.75 inches.
Flying jibboom.-Length of the flying jibboom, one half of the
jibboom; diameter one-fifth less, or 5'62 ins., at the outer end 4'5 ins.
894
MODERN STEAM PRACTICE.
ILLUSTRATION OF TERMS APPLIED TO THE HULL OF A SHIP.
20
A
Poop
70
70
5 W
tw
9
a
M™
Fig. 643.

M
Warst
18
E
L
13
74
10
Fig. 645.
Fig. 644.
10
no
W
V
W
23
24
24
X
10
K
8
A
Aft Cross Section at (a)—“Roslin Castle."
For explanation of reference letters and figures, see p. 897.
Sectional Elevation.

Deck
Plan

IRON SHIPBUILDING.
895
PLANS OF THE IRON SHIP "ROSLIN CASTLE," BUILT BY MESSRS.
K. NAPIER & SONS, GLASGOW.
Fig. 643.

Waist
n
..... Forecastle
15
R
N
16
76
E
•k
•he
K
Partial External Elevation.
Fig. 644.

Fig. 646.
75
15
T
V
T
76
16
E
E
K
X F
X
S

Fore Cross Section at (6)—“Roslin Castle."
For explanation of reference letters and figures, see p. 897.
896
MODERN STEAM PRACTICE.
K
ď
Fig. 647.

L
E
E
E"
E'
K
d"
C'
Midship Section of an Iron Ship similar in construction to the "Roslin Castle."
"
で
​I
28
K
K
Fig. 648.

L
E
E
E
X
X
K
28
K
B
Α Α'
Midship Section of an Iron Ship constructed on Scott Russell's Longitudinal System.
For explanation of reference letters and figures see next page.
IRON SHIPBUILDING.
897
REFERENCES TO PLANS (Figs. 643-648).
The corresponding parts in all the plans have the same reference letters and figures.
M
Foremast.
M'
Main mast.
M"
Mizen mast.
S
CENTRAL PART OF SHIP.
mm Wash basins.
15
Forecastle rails.
n n
A A Keel.
Paint locker and stores.
n'n' Sheep pens and hen coops.
U
Windlass.
22
Windlass bitts.
B B
Floors.
uu
Paul bitts.
CC
Centre keelson.
Boats.
3
Capstan.
CC
Sister keelsons.
5
Cutter.
V
dd Bilge keelsons.
dd Hold stringer.
DD Lower deck.
D'D' Lower hold.
dd Lower hold stanchions.
EE Upper or main deck.
E' E' Diagonal stringers for stif
FF
fening main deck (see Deck
Plan).
'Tween decks.
ff 'Tween deck stanchions.
Jolly boat.
10, 10 Boats' davits.
6, 6
Lifeboats.
Skylight.
16, 16 Berths in forecastle.
7,7
Boats' skids.
8
Gig.
9
AFTER PART OF SHIP.
Keel.
Floors.
Stern post.
A A
BB
Masts.
P
Q
Rudder.
CC
Centre keelson.
C
Sister keelson.
Step of mizen mast.
GG'G" Cargo hatches.
¿
Bilge keelson.
H
Sail room.
اله
Hold stringer.
AN
h
Scuttle to sail room.
Fore Part of SHIP.
D D
Lower deck.
I
Water tank.
D'D' Lower hold.
J
Pump well.
Stem or cutwater.
J'J' Pumps.
Figure head.
dd
Lower hold stanchions.
EE
Upper or main deck.
KK Outside plating.
R
Bowsprit.
kk Side lights.
Knight heads.
Bowsprit bitts.
FF
Bulwarks.
LL
Main bulwarks.
ll
Main rail.
SS
Cat heads.
ff
XX
Iron water-tight bulkhead.
G"
K K
Outside plating.
XX
EE Diagonal stringers (Deck
Plan).
'Tween decks.
'Tween-deck stanchions.
After hatch.
Water-tight bulkhead.
I, I
Ports.
2
L'L' Topgallant bulwarks.
''Topgallant rail.
Mooring pipe.
k k
Side lights.
Y Y
Store rooms.
12
Hawse pipe.
EE
Upper deck.
Poop.
G
Fore hatch.
W
Poop deck.
13, 13 Chain pipes (see Deck
18
Stair to poop.
Plan).
Bulwarks.
3, 3 Capstans.
On Deck.
G
Fore hatch.
G'
Main hatch.
G"
After hatch.
L L
Main bulwarks.
21
22
Main rail.
22
h
Scuttle to sail room.
L'L' Topgallant bulwarks.
J'J' Pumps.
Topgallant rail.
Cabins.
4
Cargo winch.
H 2
I, I
Ports.
23
Saloon.
Mooring pipe.
24
Private cabins or
state
Deck house.
rooms (see Deck Plan).
N Cook's galley.
N'N' Berths for cook and steward.
T
Forecastle.
Forecastle deck.
26
225
25
Stern cabins.
Steward's pantry.
N"
Berths for petty officers.
14, 14 Forecastle ladders.
V
Skylight.
N N 8 5
19
Binnacle.
20
Poop rail.
Taffrail.
Steering wheel.
57
ཐ
898
MODERN STEAM PRACTICE.
ILLUSTRATION OF TERMS APPLIED TO THE MASTS, RIGGING, &c.
1. Bowsprit.
2. Jibboom.
3. Flying joboom.
4. Martingale.
5. Fore mast.
6. Fore top mast.
7. Fore topgallant mast.
8. Main mast.
9. Main top mast.
10. Main topgallant mast.
II. Mizen mast.
12. Mizen top mast.
13. Mizen topgallant mast.
14. Spanker gaff.
15. Spanker boom.
16. Fore mast trestle trees.
17. Fore mast cap.
18. Fore topmast trestle trees.
19. Fore topmast cap.
20. Main mast trestle trees.
21. Main mast cap.
22. Main topmast trestle trees.
23. Main topmast cap.
24. Mizen mast trestle trees.
25. Mizen mast cap.
26. Mizen topmast trestle trees.
27. Mizen topmast cap.
28. Fore yard.
29. Fore topsail yard.
30. Fore topgallant yard.
31. Main yard.
32. Main topsail yard.
33. Main topgallant yard.
34. Crossjack yard.
35. Mizen topsail yard.
36. Mizen topgallant yard.
37. Fore stay.
38. Fore topmast stay.
39. Jib stay.
40. Fore topgallant stay.
41. Fly jib stay.
42. Fore royal stay.
(Fig. 649).
43. Fore lifts.
44. Fore braces.
45. Fore topsail lifts.
46. Fore topsail braces.
47. Fore topgallant lifts.
48. Fore topgallant braces.
49. Fore rigging.
50. Fore topmast back stays.
51. Fore topgallant back stays.
52. Fore royal back stays.
53. Main stay.
54. Main topmast stays.
55. Main topgallant stays.
56. Main royal stays.
57. Main lifts.
58. Main braces.
59. Main topsail lifts.
60. Main topsail braces.
61. Main topgallant lifts.
62. Main topgallant braces.
63. Main rigging.
64. Main topmast back stays.
65. Main topgallant back stays
66. Main royal back stays.
67. Crossjack lifts.
68. Mizen topsail lifts.
69. Mizen topsail braces.
70. Mizen topgallant lifts.
71. Mizen topgallant braces.
72. Mizen stay.
73. Mizen topmast stay.
74. Mizen royal stay.
75. Mizen rigging.
76. Mizen topmast back stay.
77. Mizen royal back stay.
78. Spanker vangs.
79. Ensign halyards.
80. Spanker peak halyards.
81. Jibboom martingale stay.
82. Flying jibboom martingale stay.
83. Martingale back ropes.
84. Bob stays.
IRON SHIPBUILDING.
899

75
70
74
13
36
20
27
62
26
14
80
67
68
80
69
12
25
68
67
79
78
71
72
77
58
61
69
57
99
56
10
33
61
56
65
64
22
48
48
32
8
46
54
53
47
45
cb79
18
47
38
45
29
17
03
16
62
57
ος
Fig. 649.-Masts, Rigging, &c., of a Ship.
28
37
40
39
42
41
84
83
32
900
MODERN STEAM PRACTICE.

Fig. 650.--Sails of a Ship.
19
31
!
16
30
29
17
18
2
33
2232
23
24
32
28
20
10
27
25
35
26
11
15
14
$2
2
36
IRON SHIPBUILDING.
931
ILLUSTRATION OF TERMS APPLIED TO THE SAILS.
I. Fore sail.
2. Fore topsail.
3. Fore topgallant sail.
4. Fore royal.
5. Fore skysail.
6. Main sail
7. Main topsail.
S. Main topgallant saii.
9. Main royal.
10. Main skysail.
II. Mizen.
12. Mizen topsail.
13. Mizen topgallant sail.
14. Mizen royal.
15. Mizen skysail.
16. Lower studding sail.
17. Fore topmast studding sail.
18. Fore topgallant studding sail.
(Fig. 650.)
19. Fore royal studding sail.
20. Lee lower studding sail.
21. Lee royal studding sail.
22. Main topmast studding sail.
23. Main topgallant studding sail.
24. Main royal studding sail.
25. Lee main topmast studding sail.
26. Lee main topgallant studding sail
27. Lee main royal studding sail.
28. Fore staysail.
29. Fore topmast staysail.
30. Jib.
31. Flying jib.
32. Main topmast staysail.
33. Main royal staysail.
34. Main spencer.
35. Mizen topgallant staysail.
36. Spanker.
LAUNCHING OF LARGE VESSELS.
1
As the successful launching of a large ship is a matter of great
importance, it may not be out of place when treating of the con-
struction of vessels to give a description of how the launching ways
and the various appliances and arrangements therewith connected,
should be designed. Mr. J. D. A. Samuda, in a descriptive paper
on this subject, gives the following interesting particulars of
preparations made for the launching of two large iron-clads, viz.
the German iron-clad frigates Kaiser and Deutschland. The prin-
cipal dimensions of each of the vessels were: Length, 285 feet;
beam, 63 feet; gross displacement (when fully equipped and engined),
7400 tons.
"Preparation of Slip.-This slip is formed of no less than 400*
piles of Dantzic fir, each 16 inches square and about 30 to 40 feet
long. These are arranged in transverse rows of seven piles in each
row; spaced with intervals of seven feet for the entire length of the
slip. Cross baulks of Dantzic fir, 16 inches square, are worked on
the top of each row of piles and tenanted on the tops of them.
¹ Trans. Inst. Naval Architects, 18th session.
902
MODERN STEAM PRACTICE.
Additional piles are also driven under the forefoot of the vessel to
support the extra weight of the overhanging bow. The piles are
in every case driven down to the gravel (generally about 30 to
35 feet below the surface of the ground), for which purpose a pile-
engine and a 20-cwt. monkey is used, and when this weight falling
through 26 feet fails to drive the pile more than half an inch, the
required solidity is considered to have been attained. Longitudinal
baulks are worked on the top of the cross baulks at the fore end,
where the piles project much above the ground; and aft, where,
from the rise and fall of the tide, the ground is shifting, 50 tons of
chalk were also placed round about the ship to obviate the action of
the tide. On the top of the cross baulks shorter baulks are fastened,
also of Dantzic fir, and these are surmounted with hard-wood blocks
on which the keel of the vessel rests.
Buttresses. In addition to the solid foundation thus obtained,
it is a usual practice to build up at least six buttresses, three on
each side (in this case four on each side were adopted), under the
bilges of the vessel. These buttresses are formed of baulks of timber
about 16 inches square and 8 feet long, and are laid alternately
lengthwise and transversely, forming a solid pedestal 8 feet square,
and reaching from the ground to the under side of the bilge, and
thus relieving a large portion of the weight of the ship from the
blocks under the keel in the centre line.
9
6
Inclination. The inclination of the ship while building was
ths of an inch per foot, and the blocks were kept a sufficient
height to allow convenient room for working under the vessel, and
for giving additional inclination for launching. If this is not
attended to when the keel is laid, great difficulty and risk may
occur when the launch has to be prepared. The launching ways
are laid with a camber of 8 inches in their length, the line being
carefully set off to form the arc of a circle; the inclination at the
top is ¾/4 of an inch per foot, increasing lower down in accordance
with the camber.
Launching Ways.-These are of rock elm, 4 inches thick, bolted
together and to the cross baulks on the top of the piles, and sup-
ported by blocking up between the piles wherever they are suffi-
ciently out of the ground to enable this to be done. The ways are
3 feet 8 inches wide, with a ribbon of oak 8 inches x 4 inches,
increased at the fore-end to 11 inches x II inches to receive the
heel of the dog shores on the outer side of each.
IRON SHIPBUILDING.
903
Bilge Logs and Launch.—The bilge logs are of oak, each 260 feet
long by 3 feet 1 inch wide, and are each composed of five lengths
attached together by chains. The total area of the bilge logs on
both sides was 1600 feet-the launching weight of the Kaiser was
3500 tons-thus giving a weight of 2:15 tons on each superficial
foot of bilge-log surface. The Deutschland weight as launched was
somewhat less, viz. 3000 tons, giving a weight of 2 tons (nearly) on
each foot of bilge-log surface. The greatest weight that I find by
practice may safely be allowed is 3 tons of weight to each foot of
greased bilge-log surface; anything within this may be considered
safe.
On the top of the bilge logs is worked the stopping up, which
is composed of Dantzic fir timber, carefully fitted to the ship with
poppets at fore-and-aft ends. The tops of the poppets are lined
with iron and fitted with iron forgings abutting against the lands
of the skin plating, and secured by two iron bars, each 3½ inches
diameter, lashed together at both ends by chains passing under the
forefoot of the vessel. The fore ends of the launching logs are also
securely lashed together by chains and ring bolts, having forelocks
for disengaging after the launch, which is done from the deck of
the ship. By this arrangement the fore poppets and launch are
maintained in their places, and prevented from spreading out
when the extra strain comes on the fore end of the launch at
the time when the stern is lifting, and are easily and instan-
taneously disengaged and set free when the launch has been
effected.
Sustaining Power of Slip.-The sustaining power of each pile
may be taken, approximately, to be 30 tons (it is really more).
The slip, therefore, under the entire ship (280 feet long) would
support no less than 8400 tons; but during the building of the
ship, and before the launch is laid, the weight would have to be
carried on the two centre piles only, and then 2400 tons only
could be carried-showing that, with all these preparations,
there would still be 1000 tons weight to be carried by the but-
tresses, shores, and the distribution of weight from the centre to the
side piles.
Shoring up inside the Ship.-A tier of shores between the
inner and outer bottom is placed over each launch, with shores
above the inner bottom up to each deck above; particular care
is taken to shore up strongly over the foremost poppets to resist
904
MODERN STEAM PRACTICE.
the extra strain that part receives when the vessel is partly in the
water.
Launching. -After the whole of the launch, stopping up,
poppets, &c., have been accurately fitted to the vessel, and about
three weeks previous to the launch, the launch is turned out and
the ways coated with hot tallow and soft soap, then replaced and
fixed. On the day of launching oil is forced between the bilge logs
and the launching ways through oil holes provided for the purpose,
the qualities used being as follows, viz. for the entire operation of
launching: tallow, 4 tons 6 cwt.; soft soap, 5 cwt.; oil, 55 gallons.
On the morning of launching the vessel was set up by driving in
wood wedges between the bilge logs and stopping up; and when
the weight is so far taken on the launch, the blocks under the
keel, and the bilge blocks and shores are gradually removed,
beginning from aft, but leaving ten to twenty blocks, according
to circumstances, under the forefoot of the vessel until after
the dog shores are down. Cleats at the after part of the launch
are provided to assist the dog shores till near the time of launch-
ing, when they are gradually and carefully removed. The dog
shores are removed by the fall of weights, one on each side, of
6 cwt., acting on its own dog shore and suspended over them by
a rope passing round the stem. This rope is cut by the lady
who launches the vessel, thus releasing the two weights at the
same instant and insuring the two dog shores being removed simul-
taneously.
Hydraulic Rams for starting Vessel.-One sixty-ton ram was
fixed at the end of each bilge log, and one one-hundred-ton, one
sixty-ton, and one forty-ton ram under the forefoot of vessel,
besides a large tackle on each side led to a double-purchase
crab. These were provided in case of need to start the vessel,
but were not required, as she began to move as soon as the
dog shores were down, tripping most of the blocks left under the
forefoot.
Check Rope.-A hawser was fixed to the stern of the vessel, and
attached to a chain cable and anchor carried some distance up the
stream, and so arranged in length and position as to cant the stern
of the vessel up the river as soon as she became clear of the slip,
and so prevent the danger of the vessel running on shore on the
opposite side of the river,"
IRON SHIPBUILDING.
905
TABLES OF WEIGHT OF ANGLE IRON, LENGTH OF RIVETS,
WIRE ROPES FOR RIGGING, DIAMETER AND WEIGHT
OF CHAIN CABLES, &c.
WEIGHT OF ANGLE IRON PER Foot run.
Scantlings
1/2 × 14 ×
1/2 × 1/2 × 14
134 × 134 × 4
Weight in lbs.
Scantlings.
1'614
...
3
...
2.310
3
×3 × 5%
×24×34
...
2.730
13/4 × 134 × 3/8
3'937
3
2 2 2 2 2 2 2
X 2
X 16
2'402
3/4 ×23/4 × 1/2 × 16
3/2 × 3/2 × 1/4
3/2 × 3/2 × 3/8 × 16
3
Weight in lbs.
11.287
II 34
7.822
...
...
5
5.63
X 2
X
× 14
3.150
32×2/2×38
7.691
7'087
X2
X
3.870
3/2×3/2
5 full
8:00
16
X 2
X3/8
4.567
32×3/2 × 3%
8.347
X 2
× 76
5'237
32×3 × 1/2×3/8
9'03
X2
× 1/2
5.880
3/2×3/2 × 1/2
I0'92
24×24 ×
2.716
16
32×32×
T6
12.167
24×24 × 14
3'570
4
×32×5%
13.387
21/4 ×21/4 × 16
4'397
4
X 2 × 14
14.83
21/4 × 2/4 × 3/8
5*198
4
x22
9
T6
8.912
3
×16
x2½
1/2×3/8
3
×3 X3/8
24×24×16
2 1/2 × 2/2 × 3/8×4
5
2/2×2/2
x22 × bare
22×2/2 ×
T6
22×22 × 3% bare
18
2×22 × bare
22×22½ × 1½ bare
5
22×22 × 2 × 16
234 × 234 × 14
X
3 X2
× 1/4
3 x3 × 14
3 ×22×3%
3 × 3
X
3 x3 x3/8×4
5.972
4
×3
x3/8
8.347
4.927
4
×3
x 5/8
...
13'4
4.500
4 ×4
× 14
6'51
16
...
4'922
4
×4
x3/8
9'60'7
5.827
4
X4
X
× 38 full
10'3
...
6.700
4
×3
X
...
...
7.560
4 ×4
...
...
10'92
12.62
6.300
4
x4 X
13'33
4'410
4
X4
...
...
14'53
...
3'990
4 X4
...
15'487
4'515
4 x4 × 34
18.27
...
4.830
42×3 × 3/8
8.977
5'565
42×38 × 3/8 × TU
5
X
9'345
5'972
5.985
...
6'457
7:087
3 ×3 × ½ bare
8.190
5566
5 ×5
5½
7
x 5/8
× 5
5/2×5/2 × 2
x21/4x3/8
x6 × 5%
14'057
19.687
13'44
9'922
...
23.887
×3
9'240
LENGTH OF RIVET ALLOWED FOR VARIOUS THICKNESSES of Plates.

Thickness of
Plates.
Diameter.
Length for
Counter Sink.
Length for
Snap.
inch.
1/4
3/8
7
T6
1/2
T6
5/8
11
3/4
13
16
7/8
inch.
inch.
inch.
1/2
I
14
16
5%
11/8
1½
5/8
11/4
15%
5/8
138
1½
1 2
134
1 1
16
216
3
7/8
116
5
T6
7/8
216
3
238
258
7/8
238
234
7/8
22½
I
258
23
278
15
I
16
234
3/8
I
I
278
314
905
MODERN STEAM PRACTICE.
IRON AND STEEL WIRE ROPES FOR SHIPS' STANDING RIGGING, &c., COMPARED
WITH EACH OTHER, AND WITH HEMP ROPES OF EQUIValent Strengths.

HEMP.
IRON.
STEEL.
STRENGTH.
Circumfer- Circumfer-
ence.
ence.
Lbs. Weight
per Fathom.
Circumfer-
ence.
per
Fathom.
Lbs. Weight Working Load.
Breaking
Strain.
cwts.
234
I
I
1/2
1½
I
334
158
2
...
...
134
2/2
1½
42
1%
3
2
3/2
15%
2
5%
2%
4
13/4
22
I
...
...
1/2
6
9
12
15
18
21
tons.
23456 7∞
21000
24
8
6
6
:0:0:
24
42
...
27
9
238
5
1%
3
22
52½
258
6
2
32
234
6½
218
4
།
2 3
278
7
24
4/2
72
...
7½
8
3/8
8
238
5
34
8/2
...
338
9
22
5½
32
ΙΟ
25%
6
60
∞
8½
3%
II
234
6/2
66
334
12
72
NOOAAAwwww.
30
ΙΟ
33
II
36
12
39
13
42
14
45
15
48
16
17
54
18
20
22
24
92
38
13
314
8
78
26
IO
4
14
84
44
15
338
9
90
ΙΙ
438
16
96
42
18
3/2
IO
108
36
12
45%
20
334
12
120
40
I wwwx
28
30
32
Diameter of
Cable.
Average
Weight per
Total Weight
of Anchor
Fathom.
inches.
cwts.
DIAMETER AND WEIGHT OF CHAIN CABLES, &c.

lbs.
suitable.
Total Weight
of Anchor
suitable.
cwts.
Diameter of
Cable.
Average
Weight per
Fathom.
inches.
Ibs.
1/2
14
2
138
102
21
16
17
2/2
7
116
IIO
23
21
234
122
26
25
3
116
9
132
30
3/2
15%
143
35
5
154
I
7/8
15
тв
4I
612
134
166
48
13
72
I
16
178
54
9
1%
191
1
I
61
T6
10%
11800
201
1%
I
14
116
68
122
2
217
3
16
76
15
2716
230
84
17
218
244
5
93
19
24
268
QUACIAAAA www.
ww
30
32
35
38
40
43
46
48
50
53
57
IRON SHIPBUILDING.
907
STEAM-STEERING GEAR.
Steam-steering gear is now found requisite for our larger steam
vessels, giving greater control over the movements of the ship than
could be obtained by hand power.
M
N
Various forms and arrange-

AA, Cylinders.
B, Crank shaft.
c, Crosshead guides, &c.
D, Worm pinion.
E, Worm wheel.
FF, Framing.
G, Bed plate.
H, Hand-steering wheel.
1, Sliding pinion.
K, Spur wheel.
L, Chain drum.
MM, Reversing handles.
NN, Hand wheel for steam valve.
H
F
M
A
G
E
B
Fig. 651.—Simey's Hand and Steam Steering Gear.
ments of such machinery are being used and fitted on board sea-
going vessels. One of the most recent, which appears to have the
advantage of simplicity, is shown in Fig. 651, and is thus described :—
Two cylinders AA are bolted to the base plate G, and their valve
gear are connected by slot links which are operated by a weigh bar
and reversing or steering levers MM. The shaft B driven by the
908
MODERN STEAM PRACTICE.
Cold Air Trunk ! »
Walls
Meat Chamber
Fig. 652.-Plan of Bell-Coleman Refrigerating Machine.-From Engineering, Feb. 17, 1882.
two engines is fitted with a worm
pinion D which gears into a worm
wheel E on the main axle. This axle
is fitted with a drum and recesses L, in
which the main rudder chain works.
The engine power is thus applied
direct through the worm and worm
wheel to the rudder chains, so that
the arrangement is comparatively
noiseless, and there is no jar or rattle
as there would be from cog gearing.
The steam gear can be worked
either by a short tiller or by a small
hand wheel N N from either the upper
deck or from the bridge. The ordi-
nary hand wheel H is fitted to a special
counter shaft which is fitted with a
sliding cog pinion I. This cog pinion
may be put, when desired, into gear
with a large cog wheel K keyed on the
main shaft. The hand-power can
be thus thrown into gear should
occasion arise. The engine has an
exhaust valve so arranged that any
condensed water is got rid of through
the exhaust the moment the engine
starts.

Bulkhead
To Main Engine Room Bul
REFRIGERATING MACHINERY.
During the past few years refriger-
ating machinery has taken an impor-
tant place amongst the fittings of
merchant steamers. Fig. 652 shows
the application of the Bell-Coleman
Machine to the screw steamer Strath-
leven, the first steamer to bring fresh
meat from Australia. In the figure
"A represents the steam cylinder, B
the air compressor which draws the
IRON SHIPBUILDING.
909
air from the chamber by the pipe KK, compresses it, and then
discharges it into the pipe DD, by which it is conveyed to the
tower C. The heat generated by compression is partly removed
by water injected into B during the act of compression, and
partly by water spray injected into the tower C. The air passes
from the tower C into the drying pipes EE, which are subjected
to the return waste cold air. A further reduction of tempera-
ture is there obtained than could be attained by the use of
water alone, and this has the effect of causing the moisture of the
air to be deposited inside the pipes. The moisture is drained off
by automatic traps. The air returns from the drying pipes by the
pipes FF to the expansion cylinder G, where in the act of expand-
ing it does work by helping to drive the apparatus, is reduced in
temperature, and then discharged into the cold air trunk through
which it is led to the ice-pail box, then into the meat room, vege-
table and wine rooms, and is drawn back as before described to the
compressor along KK.”
ARMOURED AND UNARMOURED WAR SHIPS.
The idea of constructing war ships able to encounter successfully
the fire of a powerful land battery seems to have originated with the
Emperor Napoleon III. during the period of the Crimean war;
and in a few years thereafter the French government had added to
their fleet the ships La Gloire, Solférino, and other vessels, built of
wood and protected by plates of iron for a considerable length
amidships. It was soon felt to be needful on the part of Britain,
if she wished to maintain her naval supremacy, to provide herself
with a fleet of similarly armoured steamers; and in this way our old
“wooden walls" gave place to iron-clad vessels as the Pallas,
Lord Warden, &c. Iron was afterwards employed in the construc-
tion of the hull of such ships; and more recently still these broad-
side-firing vessels are being gradually superseded by the turret ship,
mounting a few heavy guns which can be brought to bear more or
less all round the vessel.
The earliest ironclad ships added to the British navy were the
Warrior and Black Prince, which were built of iron, and launched
in 1860-61. The dimensions of these vessels are nearly the same;
910
MODERN STEAM PRACTICE.
viz. 380 feet in length, 58 feet in breadth, displacement 9210 tons.
The Warrior is a broadside ship, mounting 28 guns, protected by
a belt of armour 42½ inches thick, and extending for 218 feet. The
thickness of armour plating was increased to 5½ inches in the
Agincourt and other vessels built shortly afterwards. The bracket-
Sheer Plan.

Half Breadth Plan
Showing Central Battery

Fig. 653.-Sheer and Half-breadth Plans of H.M.S. Hercules.
frame system of construction was introduced in the Bellerophon,
launched in 1865, and has since been generally adopted for all
armoured ships. The Hercules, added in 1868, was protected at the
water line by a belt of armour plating 9 inches thick, and her
battery was so arranged that an all-round fire could be maintained.
It will be seen from the figure that this vessel is provided with a ram
Fig. 654.-Section of the Plating
of H.M.S. Hercules.
bow. The dimensions of the Hercules are:
Length, 325 feet; breadth, 59 feet; displace-
ment, 8680 tons; indicated horse-power,
8530. The armour of the Hercules (see Fig.
654) consists in the first place of plates of
rolled iron 9 inches in thickness at most
parts. Behind these plates is a backing of
12 inches of timber, in which are stringers of
angle iron 12 inches by 3½ inches by 5%ths
of an inch. This iron armour and backing, with a total depth of
21 inches, projects beyond the side of the vessel. The area protected
by this outer armour in the Hercules extends all round the vessel
from 5 feet below the water line to the level of the main deck 9 feet
above it. The outer skin of the side of the vessel within this armour
is composed of two layers of iron, each of which is 3/4 inch thick.
This outer skin is supported by the main ribs of the vessel, which
are 2 feet apart, and are made of angle iron 10 inches by 3½ inches
by ½ inch, and the spaces between the ribs and beneath their

IRON SHIPBUILDING.
911
turned-over portions are packed with teak. Next comes a second
backing of teak, with an average thickness of 18 inches, and finally
there is an inner skin of 34-inch iron plate, supported by the inner
ribs of the vessel, also made of angle iron. The bottom of the
vessel is a double cellular one.
Various other vessels were constructed more or less on the central
battery system, and as the battle between the guns and the armour
went on, new designs had to be adopted by naval constructors for
defence against the increasing weight of the projectile. The applica-
tions of the ram and the introduction of turret ships are the most
important of these modifications. Vessels built on the ram system
are armed at the prow below the water line with a powerful beak,
intended to sink an enemy's ship by the force with which the
vessel thus armed is driven against it. The first turret ships intro-
duced into the British navy appear to have been the wooden ship
Royal Sovereign, which was converted from a line-of-battle to a
four-turreted ship, and the Prince Albert, built of iron in 1866.
The latter measured 240 feet long by 48 feet broad, having a dis-
placement of 3880 tons, with an indicated horse-power of 2130.
Her armour was 4½ inches on side, and 5½ inches on turrets, of
which there were four, each having one 12-ton gun.
The mastless ironclad turret ships were first represented by the
Devastation, commenced in 1869. This vessel measures 285 feet
long, and has a displacement of 9330 tons, the indicated horse-
power being 6650. Draught of water about 27 feet. She is deeply
immersed in the water, and has a ram bow. There are two turrets
covered with 14-inch armour plating, whilst the hull is protected
with from 10 to 12 inch plates. She is armed with four 12-inch
rifled guns, the projectile weighing 700 lbs., and the charge 140 lbs.
The Devastation is propelled by twin screws, each driven by an in-
dependent pair of engines of the direct-acting trunk type, constructed
by Messrs. John Penn and Sons of Greenwich.
The Thunderer, launched in 1872, is of similar dimensions to the
Devastation, differing only in details of construction, in motive
machinery, and in armament. The general arrangement of this
vessel is shown in Figs. 655, 656, 657. The forecastle is shown
at F in Fig. 655, where the height of the side armour above and
below water is also indicated. The position of the armoured deck
is shown by the black line along the upper edge of the side armour.
An end view of the deck house, and the hurricane deck which it
912
MODERN STEAM PRACTICE.
supports, is seen in Fig. 657. The broadside superstructure, as it
is usually called, is shown at BB in Fig. 655 and EE in Fig. 657.
The superstructures and other parts are clearly shown in Fig. 656,
where, commencing with the highest points, II are the funnels, H is
the conning¹ tower, AA the hurricane deck, B the elevated deck
house which supports it, CC are the turrets, D the breastwork, E E
the broadside superstructure level with the breastwork, F the fore-
castle, 3 feet lower than the breastwork, and G the armoured deck,
about 7 feet lower than the breastwork in the only part where it

F
Fig. 655.-H.M.S. Thunderer-Broadside view.


A
F
G.
A
Figs. 656, 657.-H.M.S. Thunderer-Plan of Upper Deck.
Section through Fore Turret.
comes in sight, though it extends of course under E and F, and
indeed throughout the ship except inside the breastwork. The
same letters apply to Fig. 657. The conning tower will be
noticed in Fig. 655. It is sufficiently high to give a view over
the hurricane deck bulwarks, and wide enough to command a view
forward and aft past the funnels, which are oval. The steering
house is erected on the hurricane deck, and from it, or the conning
tower, by means of connecting mechanism, electric wires, and
speaking tubes, the ship and her formidable armament can be
directed.2
Figs. 658, 659, 660 give views of the Inflexible, the most formida-
ble turret ship yet added to the British navy, and which rendered
special service in the recent bombardment of Alexandria. She
was built at Portsmouth and launched in 1876. The side armour
on the hull varies from 16 to 24 inches, and on the turrets 16 inches;
displacement, 11,400 tons. The armament consists of four 80-ton
¹ Conning has been understood in the art of naval gunnery to denote the pointing and
laying of the guns with a precise aim.
2 The War Ships and Navies of the World, by Chief-engineer J. W. King, United States
Navy.
IRON SHIPBUILDING.
913
guns. She has twin screws, and is propelled by two sets of inverted
three-cylinder compound engines by Messrs. Elder & Co. of
Glasgow; indicated horse-power 8000, speed on trial about 14
knots. The Inflexible has two turrets with a central armoured
citadel, and carries two masts, which are intended to be removed in
time of action.
Mr. Barnaby, the designer of the Inflexible, thus briefly describes

田
​B
B
日​甘
​A

B

COAL
COMPARTMENTS
BOLLER COMPARTMENT|
ENGINE COMPARTMENT
DI
BOILER COMPARTMENT
COMPARTMENTS
COAL
Figs. 658, 659, 660.-H. M.S. Inflexible-A, Broadside view. B, Plan of Upper Deck.
C, Plan of Lower Deck.
C
the ship:-"Imagine a floating castle 110 feet long and 75 feet wide
rising 10 feet out of the water, and having above that again two
round turrets planted diagonally at its opposite corners. Imagine
this castle and its turrets to be heavily plated with armour, and that
each turret has two guns of about 80 tons each. Conceive these
guns to be capable of firing all four together at an enemy ahead, astern,
or on either beam, and in pairs towards every point of the compass.
Attached to this rectangular armoured castle, but completely sub-
merged, every part being 6 to 7 feet under water, there is a hull
of ordinary form with a powerful ram bow, with twin screws, and
a submerged rudder and helm. This compound structure is the
fighting part of the ship. Seaworthiness, speed, and shapeliness
would be wanting in such a structure if it had no addition to it;
58
914
MODERN STEAM PRACTICE.
there is, therefore, an unarmoured structure lying above the sub-
merged ship, and connected with it, both before and abaft the
armoured castle, and as this structure rises 20 feet out of the water
from stem to stern, without depriving the guns of that command of
the horizon already described, and as it moreover renders a flying
deck unnecessary, it gets over the objections which have been raised
against the low freeboard and other features in the Devastation,
Thunderer, and Dreadnought. These structures furnish also most
luxurious accommodation for officers and seamen. The step in
advance has therefore been from 14 inches of armour to 24 inches;
from 35-ton guns to 80-ton guns; from two guns ahead to four guns
ahead; from a height of 10 feet for working the anchors to 20 feet;
and this is done without an increase in cost, and with a reduction
of nearly 3 feet in draught of water.
I cannot attempt to describe the numerous novel and interesting
features of such a design, but I may say that no pains have been
spared to protect her against underwater attacks by the isolation of
the independent engines, the subdivision of boiler compartments,
and such further subdivisions as were possible with due regard to
proper facilities for moving about. The result is that the ship is
perfectly and easily workable, although she is divided into 127 water-
tight compartments. My belief is, that in the Inflexible we have
reached the extreme limit in thickness of armour for seagoing ships.
The temptation is always great to secure more and more power by
the expenditure of ever-increasing sums of money, but it is my
conviction that we shall not in any future ship go beyond this ex-
penditure. Some of the ironclads designed ten or twelve years ago
cost more than the Inflexible; but succeeding ships were more
reasonable in cost until the Dreadnought again approached them.
In the Inflexible provision has been made both offensively and de-
fensively for an enormous increase in the powers of artillery without
any increase in the cost of the ship.”
Mr. King, in his work on war ships, gives the following particulars
of the dimensions of the Inflexible, with structural details of her
hull and appendages:-" The length of the vessel between perpen-
diculars is 320 feet, and she has the extraordinary breadth of 75 feet
at the water line; the depth of hold is 23 feet 3½ inches; freeboard,
10 feet; mean draught of water, 24 feet 5 inches (23 feet 5 inches
forward, and 25 feet 5 inches aft); area of midship section, 1658
square feet; and displacement when all the weights are on board,
IRON SHIPBUILDING.
915
11,407 tons, being the largest man-of-war hitherto constructed.
She is a rectangular armoured castle; the whole of the other
parts of the vessel which are unprotected by armour have been
given their great dimensions for the simple purpose of floating and
moving this invulnerable citadel, and the turrets by which it is sur-
mounted. Her immense bulk, unprecedented armament, powerful
machinery, and the provision for ramming, and for resisting the
impact of rams as well as of shot and shell, have made it necessary
that strength and solidity should enter into every part of the
structure.
7
While the cellular compartments of the double bottom have a
little less depth than in the Devastation class, they are built up of
heavier angle irons and plating, and steel has been very largely em-
ployed for the purpose of securing great strength with comparative
lightness of material. The hull is composed of flat and vertical
keels, transverse and longitudinal frames, inner and outer bottom
plating. The vertical keel is formed of steel plates, 3/4 inch thick
by 40 inches deep, and the flat keel plates are of iron in two thick-
nesses of inch and 34 inch, the two being connected by angle
irons 5 by 5 inches by 34 inch. On the upper edge of the vertical
keel the angle irons by which it is fastened to the inner bottom
plates are 3 inches by 3½ by ½ inch. The framework of the
vessel below the armour is composed of longitudinal and transverse
frames. The former, eight in number, are formed of steel plates
inch in thickness, the shelf plate being of iron ½ inch thick.
These frames extend as far forward and aft as is deemed practic-
able. Within the double bottom, which extends through 212 feet
of the ship's length, the transverse frames are solid, and water-tight
at intervals of 20 feet. The intermediate frames, which are 4 feet
apart, are of the thickness of 3% inch, but are considerably lightened
by having holes cut through them, the upper parts at the same time
being much narrowed. Additional intermediate frames are worked
in the engine room in order to secure greater strength. The angle
irons forming the frames vary from 5½ inches by 3 inches by
½ inch to 3 inches by 3½ inches by ½ inch. The outer skin plating
of the bottom varies from 1 inch in the garboard strakes to 5% inch,
with the exception of the ends, where the thickness is increased to
7% inch, and behind the anchors, where the plating is doubled.
The plating of the inner bottom, which extends through the length
of the double bottom, and which, like the outer bottom, is made
916
MODERN STEAM PRACTICE.
7
16
perfectly water-tight, is of the uniform thickness of 3% inch, except
under the engines, where it is inch. As is usual in iron vessels,
the stern of the Inflexible consists of a solid iron forging, scarphed at
its lower end to the keel plates. The stern post and after piece of
the keel were also made in a single forging. The rudder is a solid
iron frame filled in with wood and covered with iron plates. In
consequence of its immense weight-some 9 tons-it is made to
work upon double pintles in combination with the ordinary pintles
and braces. It is moved by a tiller 4 feet 6 inches below the water.
Indeed, the whole of the steam-steering gear is placed below the
water line and armoured deck, so that it will be impossible for the
rudder head to be injured by shot or shell during an engagement.
To receive the propeller shafts, two iron tubes are constructed, one
under each quarter. The fore parts of these tubes, where they leave
the run of the ship, are supported by the framework of the hull,
which is bossed out for the purpose, the after parts being supported
by struts from the ship's bottom. There are four decks-the lower,
middle, upper, and superstructure decks-the last being a middle-
line erection placed forward and aft above the upper deck for work-
ing the ship, carrying and lowering the boats, &c. Outside the
citadel the lower-deck beams are covered with iron 3 inches thick.
This deck is depressed at the fore end so as to meet that part of
the bow which is intended for ramming, thus conferring upon it
greatly increased strength and resistance when engaged in butting
an enemy's ship. It may be here stated that the ram of the In-
flexible is of the spur kind, and though it is fixed at the present
time, it will eventually be made to unship during ordinary cruises.
The middle-deck flat consists of ¼-inch plating covered with 3-inch
deal planks; while the upper-deck beams in the vicinity of the
citadel are covered with 3-inch plating, and in other places with
½-inch plating. The beams, pillars, and bulkheads for supporting
the various decks and platforms, and forming the different compart-
ments and rooms, are arranged and fitted so as to give great strength
to the sides of the vessel. The largest beams are on the main deck.
They are 14 inches deep, while those on the upper deck are
10 inches, and those on the lower deck are 12 inches deep. Every
beam is either supported by wrought-iron tube pillars or is trussed
where pillars cannot be erected, the strongest being under the
The two superstructures in no wise add to the strength of
the ship. Their purpose is to afford accommodation for the officers
turrets.
IRON SHIPBUILDING.
917
and crew; and as the structures are erected on the upper deck, there
is abundance of air and natural light. Their dimensions are: fore
superstructure, extreme length, 104 feet 4 inches; breadth, 21 feet
4 inches; after superstructure, extreme length, 105 feet 4 inches;
breadth, 30 feet. The frames are formed of angle iron 7 inches by
3 inches, placed 4 feet apart, and between them are intermediate
frames made of angle iron 4 inches by 3 inches. The ends are
covered with 3%-inch plates, and the whole surface with 3-inch deals.
The cabin walls are all coated with Welch's wood-faced cement, as
a protection against the results of atmospheric condensation. The
officers and men together number 350. As a protection against the
casualties of war and the sea, the hull is divided, by means of the
transverse and longitudinal bulkheads, into no fewer than 127 water-
tight compartments, and arrangements have been made for quickly
removing therefrom any water that may collect within them through
collision or other cause. Powerful steam pumps, among which may
be mentioned two ejectors, capable of discharging 300 tons of water
each per hour, have been fitted. All the bulkheads are provided
with water-tight doors, which can be opened from above and below
decks. Each of the water-tight compartments has been tested by
hydraulic pressure. Great attention has been bestowed upon the
question of ventilation. The fresh air is drawn into the midship
part of the vessel through a series of downcast shafts, by means of
eight powerful fans, worked by four three-cylinder engines. The
air is then conducted into main pipes, which run around the sides
of the hull to the extremities, and from these, subsidiary or branch
pipes discharge the air in ample quantities to every part of the
ship.
Figs. 661 and 662 show the arrangement of armour for defence
on the sides and on the turrets; also the double bottom, hold,
decks, cork compartments, and the truncated cones on which the
weight of the turret is taken and revolved. It will be observed that
over the shot-proof deck, at a level a little above the water line,
comes the middle deck, and, as may be seen from the figures, the
entire space between the two decks is divided into compartments
arranged partly to carry coals and partly stores packed in water-
tight tanks, forming further subdivisions of the space. Next to the
sides of the ship the compartments are about 4 feet wide, and are
filled with cork, and inside this again are compartments 2 feet
wide, filled with layers of canvas and oakum, The cork and canvas
918
MODERN STEAM PRACTICE.
compartments are carried above the main deck 4 feet and 2 feet
respectively, and 30 feet forward of the citadel and 37 feet aft of
it. Thus, if a shot hit the unarmoured ends of the vessel at right
angles to the water line, it would travel through, first 4 feet of
cork, then 2 feet of canvas and oakum, then such coal and stores as
were unconsumed, and finally pass through oakum and cork to the
sea, on the opposite side from which it entered. The cork is, of
course, intended as a life belt to the ship, to give her additional
buoyancy when the unprotected ends are riddled and filled with
water.
Since the report of the committee on the stability of the ship

QUARTERS
TURRET DECK
WATER
'TIGHT
COMPARTMENTS
COFFER DAM
TURRET
TURRET DECK
ENGINES A NO BOILERS
Fig. 661.-H.M.S. Inflexible-Section
abaft Citadel.
Fig. 662.-H. M.S. Inflexible-Section
through Citadel.
was made, a further series of cork chambers have been constructed
above the lower deck forward and abaft the citadel; and several
tons of cork have also been packed in the larger cork spaces on the
lower decks. In the latter case division bulkheads and intermediate
cork flats have been introduced and secured to the armour deck.
The protected portion of the ship is confined to the citadel or
battery, within whose walls are enclosed the engines and boilers,
the turrets, the hydraulic loading gear, the magazines, and, in fact,
all the vital parts of the vessel. It measures 110 feet in length,
75 feet in breadth, and is armoured to the depth of 6 feet 5 inches
below the water line, and 9 feet 7 inches above it. The sides of the
citadel consist of an outer thickness of 12-inch armour plating,
IRON SHIPBUILDING.
919
strengthened by vertical angle-iron girders II inches wide and
3 feet apart, the space between them being filled in with teak back-
ing. Behind these girders, in the wake of the water line, is an-
other thickness of 12-inch armour, backed by horizontal girders
6 inches wide, and supported by a second thickness of teak backing.
Inside this are two thicknesses of 1-inch plating, to which the
horizontal girders are secured; the whole of the armour backing and
plating being supported by and bolted to transverse frames 2 feet
apart, and composed of plates and angle irons. It will thus be
seen that the total thickness of armour at the water-line strake is not
less than 24 inches. The armour belt, however, is not of uniform
strength throughout, but varies in accordance with the importance
of the protection required and the exposure to attack.
Conse-
quently, while the armour at the water level is 24 inches in two
thicknesses of 12 inches each, above the water line it is 20 inches
in two thicknesses of 12 inches and 8 inches, and below the water
line it is reduced to 16 inches in two thicknesses of 12 inches and
4 inches. The teak backing with which it is supported also varies
inversely as the thickness of the armour, being respectively 17 inches,
21 inches, and 25 inches in thickness, and forming with the
armour, with which it is associated, a uniform wall 41 inches thick.
The depth of armour below the load water line is 6 feet 5 inches;
but as the vessel will be sunk a foot on going into action by letting
water into its double bottom, the sides will thus have armour pro-
tection to the depth of 7 feet 5 inches below the fighting line.
The outside armour is fastened by bolts 4 inches in diameter, secured
with nuts and elastic washers on the inside. The shelf plate on
which the armour rests is formed of ½-inch steel plates, with angle
iron on the outer edge 5 inches by 3½ inches by inch. The
armour on the fore bulkhead of the citadel is exactly the same in
every respect as that on the sides, but the armour of the rear bulk-
head is somewhat thinner, being of the respective gradations of 22,
18, and 14 inches, and forming with the teak backing, which is 16,
20, and 24 inches, a uniform thickness of 38 inches. Before and
abaft the citadel the frames are formed of 7-inch and 4-inch angle
irons, covered with-inch plates. The armour shelter for the pro-
tection of the officers manoeuvring the ship is in the shape of a
cross, and is plated with iron 12 inches thick."
The Inflexible carries two guns in each turret. The ordinary gun
carriage is done away with, the guns resting on blocks which are
920
MODERN STEAM PRACTICE.
free to slide. Two hydraulic cylinders are used to check the recoil,
and for replacing the gun in position. The weight of shell thrown
by these guns is 1600 lbs., with a bursting charge of 60 lbs. of
powder. The charge of powder in gun is 425 lbs. The destructive
effect of these immense projectiles has recently been practically
proved at Alexandria, especially when directed against forts of
masonry; the result against earth work seems to have been very
much less destructive. It appears that during the bombardment
those vessels which anchored were hit much more frequently than
those kept moving. One troublesome matter seems to have been
the smoke arising from the discharge of the ships' guns, which hung
about and prevented a sight of the enemy, and some mechanical
means might be adopted to dispel or otherwise prevent such ob-
struction to the gunners.
The latest additions (1882) to our fleet are the Colossus and
Edinburgh (the latter formerly known as the Majestic). These
vessels are turret ships, and resemble the Inflexible. One important
matter to be noted is that these are the first war ships built of steel.
The armour plating is steel-faced, and measures 18 inches on the
hull and 14 inches on the turrets. The armament consists of
four 43-ton guns in the turrets, four 6-inch breechloaders, six
20-pounders, and ten Nordenfelt guns on the decks. The latter
guns will be fitted so as to eject Whitehead torpedoes.
The following is from a description of the former vessel which
appeared in the Times:—“The Colossus is the first steel ship which
has been laid down in the Portsmouth yard, and consequently
differs from the Inflexible, which is wholly built of iron. While,
however, the vertical keel, flat keel, garboard strakes, bracket and
solid frames, longitudinals, inside and outside plating, and bulk-
heads will be all formed of low steel, it has been deemed ad-
visable to construct the heavy forgings, such as the solid stem
and the stern post, as well as the afterpiece of keel, of iron.
The vertical keel plates are ½ inch in thickness, and 38 inches
deep; while the flat keel is composed of plates in two thicknesses,
the upper being 5% inch and the lower 34 inch. The flat and
the vertical keels are connected together by angle steels, and
similar angle steels run along each side of the upper edge of the
vertical keel. As it has been found that these bars are liable to
fracture in the flanges and rivet holes, owing to causes which the
usual tests have not been able to discover, Mr. Barnaby has insisted
IRON SHIPBUILDING.
921
upon very stringent precautions being observed in dealing with a
material apparently so erratic in its behaviour as steel. All plates
or bars which can be bent cold are to be so treated; and if the
whole length cannot be bent cold, heating is to be had recourse to
over as little length as possible. All plates or bars which have
been heated for bending or flanging are to be annealed afterwards
over the parts which have been heated; and if desired, exception-
ally long or quickly curved bars, such as frames, may be formed of
shorter pieces with the butts suitably shifted and strapped. No.
bar or plate which exhibits signs of failure in working is to be put
into a ship; but pieces should be cut from such plates and bars
and subjected to quenching and tensile tests. In the outer bottom
plating, again, the holes which are to be countersunk should be
punched about ½ inch less in diameter than the rivets which are
used, the enlargement of the holes being made in the countersinking,
which should in all cases be carried through the whole thickness of
the plates. All butt straps to plating forming an important feature
in the general structural strength, should have the holes drilled, or
be annealed after the holes are punched. Snap-rivetting is only to
be employed for internal work of subordinate importance; but on
stringers, deck plating, and other parts subjected to considerable
tensile strain, countersunk rivetting is to be used, and the holes
treated similarly to those in the outside plating. Acting on these
principles, Mr. Barnaby is satisfied that steel bottom-plating needs
neither drilling nor annealing after punching. Iron rivets only are
used."
The war vessels already described are those more or less in-
tended for coast defence combined with sea-going qualities, but
another and important class falls to be referred to, viz. unarmoured
cruisers. Indeed, it is not improbable that owing to the increasing
difficulty of carrying the necessary heavy armour, and to the pro-
bably still increasing power of the guns, the armour may gradually
be decreased, until at length, like the coats of mail used by the old
warriors, it is stripped off, and our war ships go into action freed
from its encumbrance. That such is not at all unlikely we have
so high an authority as Sir Wm. Armstrong, who, in a late presi-
dential address before the Institute of Civil Engineers, says:-
Presuming that our naval superiority had ceased to depend on
seamanship and an unlimited supply of sailors, and was now largely
dependent on scientific skill, he said it was not too much to say
"
922
MODERN STEAM PRACTICE.
意
​that for the cost of one ironclad we could have three unarmoured
ships of far higher speed, and carrying collectively three armaments,
each equal to that of the armoured vessel. It might be asked
which would be the better investment? If it were imagined that
three were matched in combat against the one, it would be perceived
that, in addition to their numerical superiority, the former would
possess many advantages. Being smaller, they would be more
difficult to hit. Being swifter, they could choose their positions
and be free to attack or retreat at pleasure. Being more nimble in
turning, they would be better adapted both for ramming and for
evading the ram of their adversaries. Finally, the conditions of
superior speed and agility would favour their use of torpedoes and
submarine projectiles, although it was a question whether, for the
sake of a much-needed simplification, it would not be better to
confine that species of attack to separate vessels specially con-
structed for that one particular purpose. With the crews in
safety it was scarcely possible that unarmoured vessels, with under-
water decks and all their machinery beneath, should suffer any
disabling injury by being pierced in a few places by either shot or
shell.
It might perhaps be rash entirely to abandon armour so long as
other nations continued to use it, because nothing but the experience
of an actual war would remove all question as to its possible utility;
but considering the indisputable value of a numerous fleet of swift
and powerfully-armed ships, built with a view of obtaining the
maximum amount of unarmoured defence, and considering that
such vessels, unlike armour-clads, could never grow much out of
date, it did not seem to be expedient that the chief expenditure
of this country should be upon ships of that description. Light-
ness should be the special aim in the construction of such vessels.
Steel plates should be used for the hulls, and guns and engines.
should be of the least possible weight consistent with the necessary
power. Every ton of weight saved would enable higher speed to
be attained, and there was probably no quality in a fighting ship
which would so much develop in importance as that of swiftness. He
took it for granted that all new ships would be armed with the best
guns that could be now made, and that the more important of the
old vessels would speedily receive the same advantage; but beyond
this, so long as experience of novelties was deficient, it was a case
for cautious procedure. In the meantime no expense should be
IRON SHIPBUILDING.
923
spared in judicious experiments, seeing that the expense of experi-
ments was trifling in comparison with that of mistakes."
Of these unarmoured cruisers the Iris is perhaps best known
from the various experiments made to determine the best form of
propeller. She is built of steel, and measures over all 333 feet in
length, with a displacement of 3750 tons. The plating is from 3/4 inch
to ½ inch thick. The armament consists of eight 64-pounder
broadside guns, and two similar guns, but capable of revolving, and
placed at bow and stern. She also carries Whitehead torpedoes.
With an indicated power of about 7700 horses the speed was
18½ knots, the steam pressure being 62 lbs. and the revolutions
96 per minute. The propellers, which are twin screws, are 16 feet
3 inches, with a pitch of 20 feet.
Fig. 663 shows a profile view of this ship, and Figs. 664, 665

ladook
COALS
C
ENGINE ROOMS
A
L
COAILS
A

B

C
A
S
Figs. 663, 664, 665.—H.M.S. Iris-A, Broadside view. B, Upper Deck Plan. C, Plan at water, line.
show the disposition of the guns and the manner in which the hold
is occupied and subdivided. Her structural arrangements are thus
described by Mr. W. H. White of the Royal Navy:-" The engines
and boilers are kept below the water line, and protected throughout
by wing coal bunkers, varying in thickness from 5 feet to 8 feet be-
tween the upper and lower decks, and decreasing in thickness as
the depth below water increases. Fig. 663 shows the heights of the
decks and platforms, the positions of the bulkheads, &c. Reference
to the figures will show that there are ten complete water-tight
924
MODERN STEAM PRACTICE.
transverse bulkheads; and thať in wake of the stoke holes, where
the main bulkheads are 44 feet apart, intermediate or 'partial'
bulkheads are introduced in the coal bunkers. The longitudinal
bunker bulkheads are also water-tight; and throughout the length
occupied by the machinery and boilers there is a water-tight inner
skin, forming a complete double bottom across the ship between
the bunkers. Before and abaft the double bottom, a water-tight
platform is built about 7 feet below the lower deck, and extending
to the bow and stern respectively. This platform does not extend
quite to the foremost boiler-room bulkhead, because the small
'forehold' (about 14 feet in length) is nearly occupied with water
tanks and chain lockers. In the coal bunkers also there is a plat-
form about mid height between lower deck and bilge. As is usual
in her Majesty's service, the magazines and other enclosed spaces
are formed into water-tight compartments; and altogether there
are no less than sixty-one separate compartments; twenty-one in
the hold proper, and forty in the double bottom and bunkers. The
various partition bulkheads just mentioned of course contribute
largely to the structural strength, especially to the transverse
strength; and this must be kept in view when examining the fram-
ing. In some respects the system of framing adopted in the Iris
resembles that commonly used in iron vessels of the Royal Navy,
but in other respects it is novel. It may be said that the arrange-
ment of the framing has been governed by the desire to efficiently
stiffen and support the comparatively thin skin plating, while
avoiding the use of closely spaced transverse frames. The skin
plating is ½ inch thick, with a double sheer strake; the garboard
strakes are 5% inch. Throughout the length of the double bottom
the transverse frames are spaced 4 feet apart; before and abaft
the double bottom the spacing is 32 feet. By means of the
longitudinal framing, the unsupported spaces of the bottom plating
are kept down to 16 or 20 square feet, and buckling or unfairness
is prevented.
As regards the framing in wake of the double bottom, the outer
or frame angles are 6 by 3 by; they are made continuous from
the first longitudinal on one side to that on the other, passing
through scores cut in the centre or vertical keel plate, and are
again continuous from the upper deck down to the second longi-
tudinal. Up to the turn of the bilge the transverse frames below
the inner skin are on the well known 'bracket-plate' system, the
IRON SHIPBUILDING.
925
16
16
brackets being formed of-inch plates, and the short angles on
their inner edges being 6 by 3 by 3% between the keel and second
longitudinal, but only 3 by 3 by between the second and third
longitudinal, where a lightened plate is substituted for a bracket.
Within the coal bunkers the reversed frames are 3 by 3 by. The
centre plate keel is 3% inch thick, with lightening holes in the spaces
between the frames; its lower edge is rivetted to the bar keel (iron).
The longitudinals in the double bottom are formed of-inch
plates, with 3 by 3 by 3% bars on the outer edges and 2½ by 2%
by bars on the inner edges. Plates and bars are worked con-
tinuously, with butts carefully shifted and strapped, in the same
way as is usually done in armoured ships. The first longitudinal
out from the keel on each side is made water-tight throughout the
double bottom. In wake of the bunkers the light transverse fram-
ing is well stiffened by the lower-deck stringer, and by the platform
below the lower deck; besides which there are longitudinals formed
of 10 by 3½ by 3% by z-bars (similar to those now used for
frames behind armour in iron-clads). These z-bars are scored in
over the 6-inch frames and secured to the skin plating; a continuous
3 by 3 by 3% angle bar being worked inside the reverse frames and
rivetted to them and to the z-bars. A strong and simple stiffener
is thus secured with very little workmanship.
7
6
Outside the limits of the double bottom the framing closely re-
sembles that described for the coal-bunker spaces, with the addition
of a floor plate, and a gutter plate at the middle line. Care is taken
to scarph on the z-bar longitudinals before and abaft the double
bottom to the deep longitudinals within the double bottom. The
plates of the longitudinals are gradually reduced in depth, and a
strake of the inner bottom is extended over the tapered portion of
the longitudinal to strengthen the connection.
16
The inner bottom plating is inch and 4 inch in thickness; the
edge joints are single rivetted, and butts double rivetted. It is worked.
flush, as is usual in ships of the navy. Its vertical continuations,
forming the coal-bunker bulkheads, are of 4-inch plating with 3 by
3 by 3% vertical stiffeners placed 30 inches apart. This plating is
lapped and single rivetted at the edges, the butts being double
rivetted. The coal-bunker bulkheads are continuous, the transverse
bulkheads being cut off where the two systems cross one another.
This is a departure from common practice, but has obvious advan-
tages. For nearly one-half of the length of the ship, where all the
926
MODERN STEAM PRACTICE.
principal strains have to be resisted, and where the largest hatch-
ways have to be cut in the decks, the ship's sides are constructed
strictly on the cellular system, the inner and outer skins being
stiffened independently as well as strongly connected to each other
by the horizontal plating on deck and platforms, and by the vertical
transverse bulkheads. The desire to provide coal protection for the
engines and boilers was the primary cause of this arrangement; but
it might probably be imitated with advantage in other classes of
ships.
The outer bottom plating up to some distance above the bilge
is worked in the usual manner with double chain rivetted lap-
joints. Above this height the plates are flush-jointed at the edges,
with continuous single-rivetted internal strips; this is purely for the
sake of appearance. The butts are all secured by double chain
rivetted straps; iron rivets are used throughout the ship, the sizes
being the same as would be used with iron plates of the same thick-
nesses.
Respecting the transverse and other bulkheads in the hold, it
will suffice to say that the usual practice is followed in construction;
the plating is 4 inch and inch thick, with vertical stiffeners,
3 by 3 by 3%, placed 30 inches apart. Single-rivetted lap-joints are
used in this work.
5
16
There is nothing in the deck framing which needs to be described;
but it may be interesting to summarize the arrangements of the
deck plating:-
Upper Deck—A partial steel deck (3% inch) on each side, about
8 feet wide amidships, forming a top to the coal bunker; before and
abaft the bunkers this plating is gradually tapered to a stringer
about 4 feet broad.
Lower Deck-A stringer plate, 30 inches wide, and 3% inch
thick.
Platforms Before and abaft double bottom (water-tight), 4-inch
plating. In coal bunker,-inch plating.
The butts of all the longitudinal tie-plating are carefully strapped,
and double chain rivetted.
The framing of the extremities calls for very few remarks. A
bar-stem (iron) is used, and the bow-framing is of the ordinary
character. At the stern the only unusual features are consequent
upon the extreme fineness of form. In order to decrease the labour
of building and the volume of internal spaces requiring to be filled
IRON SHIPBUILDING.
927
in with cement, the bar keel is ended about 30 feet before the stern
post. The true keel from that point is really a flat plate turned
upwards, and carried along about 6 feet above the height of the
under side of bar keel produced. The space between the flat keel
and the base line is made good by means of an external centre
plate, having double angle irons on the upper and lower edges, and
wood chocks bolted to the sides, with frequent bracket stiffeners in
steel.
In the Iris, owing to her great power and fine form, the length
of external shaft tubes is about 50 feet. Each tube is supported by
two struts or A-frames; and the attachment of these to the hull has
been arranged with only trifling additions to the framing proper.
Under the very severe and repeated tests consequent upon the
long series of steam trials, there has not been the least indication of
weakness or want of rigidity at the after part of the ship. As to
her capacity for resisting the principal strains to which a ship at sea
is subjected, there can be no question."
A class of unarmoured corvettes, called the Comus class, of steel
and iron cased in wood, were added in 1878, the object being to
attain a high speed. The displacement is 2380 tons, with an indi-
cated engine power of 2300, the draught of water about 19 feet. The
speed attained is fully 13 knots. The armament is two 7-inch and
twelve smaller guns, all of which are able to penetrate 8-inch
armour. The engines are horizontal compound surface-condensing,
having steel boilers carrying 60 lbs. steam. The propellers are twin
screws.
I
What is known as the Leander class of cruisers consists in some-
what similar vessels to the Iris, but of less power, the indicated
horse-power being only 5000, and the addition of a steel deck
1½ inch thick to protect the engines, &c., and placed about the
level of the water-line. The dimensions of the Leander, Arethusa,
and Phaeton are:-Length between perpendiculars, 300 feet;
breadth, extreme, 46 feet; depth, moulded, 27 feet 3 inches. The
load draught of the Leander class is estimated to be 17 feet
6 inches forward and 20 feet 6 inches aft, and the corresponding dis-
placement is about 3800 tons. The vessels are of steel, and the plates
are subjected to an acid bath to remove the scale previous to their
being worked into position.
The armament of these vessels differs greatly from that of the Iris
in its arrangement, and is of quite a novel description. It consists of
928
MODERN STEAM PRACTICE.
»
ten 6-inch breech-loading guns, two Gatling guns, six Nordenfeldt
guns, and ten Whitehead torpedoes. Four of the breech-loaders
are mounted on what is known as the Albini carriage, and are fixed
on revolving turntables which project beyond the sides of the ships.
They are placed on either side of the upper deck at the fore end of
poop and after end of forecastle. These bow guns can be trained
from a cross fire of 4 degrees forward to 45 degrees abaft the beam,
and the after guns from right aft fire to 45 degrees before the beam.
The Albini carriage, which is the invention of an Italian of that
name, is being largely adopted by foreign governments, and is now
being introduced to our own navy.
The remaining six 6-inch breech-loading guns which these vessels
carry are fitted at broadside ports on the upper deck in the ordi-
nary way. The six Nordenfeldt guns are fitted in projecting parts.
of the topsides, and are so arranged as to give great training and
great depression for firing into boats alongside. The shot used
with these modern weapons is of steel, I inch diameter, and
pointed. Each gun is capable of firing 250 rounds per minute.
The Whitehead torpedoes are discharged from broadside ports
on the lower deck-two forward and two aft. These torpedoes are
about 18 feet long and 14 inches diameter. The heads, which
contain the explosive material, are stowed in a separate magazine;
and the body of the torpedoes, in which are the chambers for com-
pressed air, the engines, screw propeller, rudder, &c., are stowed in
a separate store room. Air-compressing machinery, with pipes to
the discharging ports, is also fitted.
The armoured or "belted" cruisers Nelson and Northampton,
recently built on the Clyde, have a belt of plating about the water
line, 181 feet long and 9 feet deep, as also armoured bulkheads at
each end of these belts. The lower deck, covering the machinery,
is of 2-inch plating. Their armament consists of four 18-ton guns
and eight 12-ton guns on the main deck, with smaller guns on the
upper deck.
Before passing from the subject of war ships, we may notice the
Polyphemus, an experimental vessel combining the armoured ram
and torpedo boat, which was built at Chatham, and launched in
1881. She is a twin-screw vessel of 2640 tons displacement and
5500 horse-power. The following is a description of the Polyphemus
when far advanced in building: "The leading features are a strong
ram bow, a powerful torpedo battery, great speed and handiness,
IRON SHIPBUILDING.
929
moderate size, and a small extent of surface above the water ex-
posed to the enemy's fire, such portion of the vessel as is above the
water line being convex in form, so as to deflect any projectile that
may strike it. The appearance she will present when at sea will be
that of a cylinder, floating on its side and deeply immersed, which is
tapered at the ends to form a bow and stern. The top of the cylinder
will be 4 feet 6 inches above the water line, and will be flattened over
a large portion of its area to form a deck. The whole of this flat-
tened cylindrical surface will be plated over with steel armour, and
will cover in and protect the ship and all her machinery and fight-
ing appliances. The armour is made up of two ½-inch thicknesses
of Landore-Siemens steel, one being the skin of the ship, on which
are laid 1-inch plates of Whitworth compressed steel. The ship pro-
per as she will thus appear will be surmounted by a light structure
carrying a hurricane deck of about two-thirds of her length, and upon
this deck will be seen a signal-mast, funnel, pilot-tower, boats, and
other fittings. The curvature of the sides is carried down several feet
below the water line, and armour-plated to that depth. Below this
point the section assumes a v form, and ends in a sharp angle at the
keel. A complete cross section of the vessel is therefore very similar
to that of a peg top. The flattened convex curvature of the upper
part of the peg top would represent the part of the Polyphemus that
is above water, and the lower portion, which ends in a point, would
also represent the part of the ship that is below water.
If the peg
top be imagined to float in water at a depth below where its breadth
is greatest and where the section thus begins to curve towards the
centre line, a rough idea may be obtained both of the form and
proportions of the above and under water parts of the Polyphemus.
The Polyphemus is 240 feet long between perpendiculars, 40 feet in
extreme breadth, and will have a load draught of 20 feet. She
will be propelled by twin screws, and will have two pairs of high-
pressure compound horizontal engines, which are being constructed
by Messrs. Humphreys & Tennant, Deptford. Each high-pres-
sure cylinder will be 38 inches in diameter, and the low-pres-
sure 64 inches. The stroke will be 45 inches. The boilers will
be of the locomotive type, twelve in number, and will be made of
steel. They will work up to a pressure of 110 lbs. per square inch."
"The Polyphemus is built throughout of steel, and will carry no
guns save one or two small pieces on deck; but she will be able to
launch torpedo after torpedo from the orifice in the cutwater, and
59
930
MODERN STEAM PRACTICE.
about 8 feet below the water level. Besides this she can discharge
other torpedoes at each side. She is divided into a great many
compartments by suitable bulkheads, and in her bottom keel, if we
may so call it, she will carry blocks of cast iron each weighing
20 tons. Should she take in much water from being pierced by
an enemy's shot, these blocks can be dropped into the sea at a
moment's notice, and the ship so far lightened. Her turtle back
10%

10
Fig. 666.-Armour Plating of the Polyphemus.
will be covered with scale armour secured to 2-inch plates. This
scale armour consists of a series of tiles or plates, each 10% by
10 inches by inch thick, made of Whitworth compressed steel.
The tiles are secured, as shown in Fig. 666, with screw studs
13% inch diameter, one in each corner and one in the middle,
the whole surface being flush."
VESSELS FOR DREDGING.
Figs. 667 and 668 show a dredger and hopper barge constructed
by Wingate & Co., Glasgow. This dredger is designed so as to be
able to steam to its destination; and when ordered for foreign
stations the principal parts of the machinery are dismantled and
stowed on board, and temporary masts, rigging, and sails fitted, so
that she may be propelled both by steam and wind power. Com-
pound engines are adopted for the large dredgers, made of sizes
varying from 10 horse-power up to 80 horse-power, fitted to dredge
in water from 3 to 40 feet in depth, and capable of lifting from
20 tons to 1000 tons per hour.
The steam hopper barges with compound engines are considered
preferable to the ordinary mud barges with steam tug, as they convey
IRON SHIPBUILDING.
931
the material away at a cheaper rate; they are made from 50 to 600
tons capacity, and can be made larger with advantage to suit the
requirements.
In all dredging vessels the principal use of the steam engine is to
drive the machinery for excavating the soil, to drive the powerful
lifting hoist for raising and lowering the bucket ladder, and to work
the forward and aft crabs for advancing the vessel; all of these
operations are effected by means of shafting and gearing driven off
the crank shaft of the engine.
The bucket ladder is generally made of wrought-iron plates.
trussed together, with rollers on the top for supporting the links
carrying the buckets. The top end of the ladder is carried on
brackets bolted to the wrought-iron framing worked up from the
floor of the vessel; the bottom end is slung with a shackle with
movable pulleys and chain connected to the hoisting crabs. On
the tumbler shaft is fitted securely a square driver technically
termed the "tumbler," and at the bottom of the ladder a five-
sided tumbler with shaft is placed between the girders forming the
ladder and revolves in bearings fitted to the girders. As the
buckets may catch on a hard substance they cannot lift, a friction
coupling must be placed between the engine and the tumbler shaft,
by which means, when any undue strain comes on the bucket
ladder, the engine revolves without imparting motion to the tumbler
shaft, and consequently the buckets remain stationary until the
obstacle is removed, thereby lessening the risk of fracturing the
driving machinery. It is likewise advisable that a disengaging
clutch should be fitted, so that the engine may be used in moving
the vessel to and fro, without imparting motion to the tumbler
shaft.
The hoisting gear for the bucket ladder is fitted with a clutch or
friction cone, so as to throw the winding barrel in and out of gear
at pleasure, the chain from which takes a fast pulley fitted to the
hoisting framing, and a movable pulley fitted to the shackle at the
bottom of the ladder. When the barrel is thrown out of gear the
descent of the ladder is regulated with a wheel-and-friction strap
and when the strap is tightened up the ladder is suspended at any
position that may be required.
All first-class dredging vessels should be fitted with crabs and
surging heads at the bow and stern, to move them forwards or back.
wards, and sideways, as may be required. In Fig. 668 it will be
932
MODERN STEAM PRACTICE.
O
Fig. 667.-Longitudinal Section of Dredger.
·
"1
"
"
"1
11
ร

IRON SHIPBUILDING.
933

O
x
DODDDDDDDD
B
Fig. 668.—Plan of Dredger with Hopper Barge.
Figs. 667, 668.-A, Dredger. B, Hopper barge. c, Well. D, Compound steam engine.
E, Screw propeller. F, Boiler. G, Spur gear.
H, Spur wheel on the tumbler shaft. 1, Bucket ladder. K, Hoisting gear. LL, Advancing gear. M, Hand crane. NN, Mud shoots.
oo, Crabs.
PP, Chains for advancing the vessel. QQ, Chains for side movement.
934
MODERN STEAM PRACTICE.
7111
Fig. 669.-Steam Dredger, adapted to cut in front as well as dredge in the usual manner.
seen there are three chains
at each end of the vessel,
one central one and two
side ones, having a coned
barrel or surging head for
each, and which are made
to revolve either way by
throwing in or out the bevel
wheels, which are driven by
means of shafting connect-
ing to the engine. The
crabs should likewise be
arranged for working by
hand, so as to move the
vessel when required, as
more fully delineated in
Fig. 669. A hand crane
should be fitted as in Fig.
667, for the convenience of
fitting up and replacing
the buckets for ordinary
repairs.
Instead of having the
well for the bucket ladder
placed in the central part,
the vessel is sometimes
made open at the end;
by this means the bucket
ladder is lifted up, and pro-
jects beyond the end of the
vessel, and is adapted to cut
in front as well as dredge
in the usual manner.
The part of the shoots
projecting beyond the sides
of the vessel should be made
to hinge, and be drawn up
or lowered with suitable
blocks and tackle, as shown
in Fig. 669.

I
IRON SHIPBUILDING.
935
DOUBLE DREDGER OF 45 HORSE-POWER.
This is a very simple arrangement of dredger, the pinion on the
engine shaft gearing with a spur wheel on the tumbler shaft over-
head. The hoisting gear is placed between the engine and the

A
"
111
B
G
C
E
E
E
Fig. 670.-Double Dredger of 45 horse-power. Longitudinal and Transverse Sections.
▲, Dredge boat. B, Boiler. c, Engine. D, Tumbler shaft. E, Bucket ladder. F, Hoisting blocks.
G, Hoisting drum.
boiler; the shaft for carrying the hoisting drum is of large diameter,
fitted with a friction cone for throwing out; the shaft is driven by
wheel gearing and diagonal shaft from the tumbler shaft overhead.
DETAILS OF DOUBLE DREDGER OF 45 HORSE-POWER.
Length of boat, 110 ft.
Breadth of do., 26 ft.
Depth of do., 8 ft. 6 in.
Draught of do., 5 ft.
Depth to dredge, at an angle of 45°, 40 ft.
Number of buckets in each ladder, dis-
charging 400 tons per hour with both, 32.
One Oscillating Engine.
Diameter of cylinder, 3 ft. 3 in.
Stroke of do., 3 ft.
Number of revolutions, 30.
Diameter of main spur wheel, 16 ft.
Pitch of teeth, 3½ in.
Diameter of pinion, 4 ft.
Pitch of teeth, 3½ in.
Diameter and stroke of air pump, 25 in. ×
13 in.
Depth of piston, 8 in.
Diameter of rod for do., 434 in.
Exhaust pipe, 9 in.
Diameter of crank shaft, 84 in.
Do. of tumbler shaft, 12½ in.
Revolution of hoisting gear per minute, 6·8.
Diameter of drums, 3 ft.
Revolution of advancing gear, 1*7.
Diameter of surging heads, I ft. 9 in.
Ladder to lift 40 feet in four minutes, with
six sheave blocks.
Boiler:-Length 15 ft. 3 in., breadth 11 ft. 6 in., depth 6 ft.; 18 tubes, 12 ft. long and
8 in. diam.; heating surface per horse-power 14 sq. ft.
936
MODERN STEAM PRACTICE.
Engines, 14 tons.
DETAILS OF DREDGER OF 25 HORSE-POWER.
Boiler and bars, 8 tons 14 cw't.
Machinery, 22 tons 15 cwt.
Oscillating Engine.
Diameter of cylinder, 2 ft. 7 in.
Stroke of do., 2 ft. 6 in.
Diameter of air pump, I ft. 6½ in.
Stroke of do., 10 in.
Diameter of engine shaft, 6 in.
Length of ladder, 53 ft.
Number of buckets, 25.
Depth to dredge, 24 ft.
Bevel Gearing.
Large wheel on tumbler shaft, 8 ft. 4 in.
diameter, 9 in. broad, 33% in. pitch.
Pinion, 3 ft. 2 in. × 9 in. × 3% in. pitch.
Friction wheel on engine shaft, 3 ft. 2½ in.
× 7¾ in. × 33% in. pitch.
Diameter, 7¾ in. broad, 3% in. pitch.
Wheel on vertical shaft, 3 ft. 10½ in.
Diameter, 734 in. broad, 3% in. pitch.
Pinion on vertical shaft, 1 ft. 8 in. × 4½ × 2.
Wheel for do., advancing gear, 3 ft. 4 in. ×
4½ × 2.
X
Advancing gear travels 9'5 ft. per minute.
Number, I.
Length, 14 ft.
Boiler.
Breadth, 7 ft. 6 in.
Height, 6 ft. 4 in.
Number of tubes, 12.
Diameter of do., 8 in.
Heating surface, 382 sq. ft. = 15 ft. per H. P.
Fire grate, 2 ft. 9 in. × 6 ft. 6 in.
COMBINED HOPPER DREDGER.
In our Plate are shown a longitudinal section and deck plan of a
Combined Hopper Dredger, designed to dredge in 20 feet depth of
water, and to carry 200 tons in its own hopper. To the kind-
ness of its designer Mr. Andrew Brown, of the firm of Messrs. W.
Simons & Co. of Renfrew, we are indebted for some notes on this
vessel and the two systems of dredging in use. A hopper dredger
combines in itself the properties of a powerful dredger and screw
hopper barge, with one crew for working the vessel both whilst
dredging and steaming to the place of discharging, as compared
with an ordinary dredger and a fleet of hopper barges with a
skilled crew in each vessel. The vessel illustrated propels itself
to the place requiring dredging. It is then moored by steam
winches to the guide buoys at both bows and quarters. The bucket
ladder is then lowered to the bottom by steam, and the machinery
connected therewith is set in motion. The buckets discharge the
spoil into its own hopper or hold, as seen and described more fully
on the Plate. The hopper may be constructed to contain from 100
to 2000 tons, according to the size of the vessel. The top tumbler is
placed only about one-half the height of an ordinary dredger for
loading hopper barges, and a considerable quantity of soil is saved
which is usually lost. The saving of cost on the work done by the
hopper dredger compared with that done by the stationary dredger
is estimated at fully one-third
IRON SHIPBUILDING.
937
Messrs. Simons & Co. have of late years constructed a number
of Hopper Dredgers for work in different parts of the world, and
they are found to work satisfactorily even on exposed coasts. The
hopper capacity of these vessels ranges from 200 to 1400 tons, with
a nominal horse-power of from 32 to 140. Examples of the latter
capacity and power are the Greenock, employed on the Firth of
Clyde; and the Willunga, employed at Port Adelaide, South
Australia. The principal dimensions of the Willunga are: Length
182 ft., breadth 38 ft., depth 13½ ft., hopper capacity 20,000 cubic ft.
The buckets excavate to 30 ft. depth of water, and lift at the rate of
350 to 400 tons of limestone and sand per hour.
DREDGERS ON THE RIVER CLYDE.
In no part of the country has the advantage of dredging opera-
tions in creating and maintaining a navigable channel been more
remarkable than on the Clyde, and the following particulars of
dredging machinery and work on that river, kindly furnished by
Mr. J. Deas, Engineer to the Clyde Trust, will be found of interest.
No. 1 Dredger is 156 feet in length, 324 feet in breadth, and
10 feet in depth, has engines of 50 horse-power, and can dredge in
32 feet depth of water. It has two bucket ladders, and loads into
hopper barges. In the year 1881-82 this machine dredged 426,800
cubic yards or 533,500 tons of material in 2482½ hours. The sum
for wages, coals, and stores for the year was £1171, and for repairs
£2012. This machine was built in 1851 at a cost of £7923; and in
1875, at the Clyde Trustees' own works, she was lengthened, her
dredging capability increased, and she was adapted to load into
hopper barges instead of into punts as formerly, at an additional
cost of £15,826. Total cost £23,749.
No. 6 Dredger is 121 feet long, 33% feet broad, and 10 feet deep,
has engines of 40 horse-power, and can dredge in 25 feet depth of
water. It has two bucket ladders, and loads into hopper barges. In
the year 1881-82 this machine dredged 289,400 cubic yards or
361,750 tons of material in 2665 hours. The sum for wages, coals,
and stores for the year was £1230, and for repairs £1020. The
original cost of the machine was £13,663.
No. 7 Dredger is 108½ feet in length, 23½ feet in breadth, and
9 feet in depth, has engines of 25 horse-power, and can dredge in
25 feet depth of water. It has one bucket ladder, and loads into punts.
In the year 1881-82 this machine dredged 22,860 cubic yards or
938
MODERN STEAM PRACTICE.
28,575 tons of boulder clay and blasted rock in 2310 hours. The
sum for wages, coals, and stores for the year was £903, and for
repairs £1414. The original cost of the machine was £6655.
No. 8 Dredger is 161 feet long, 29 feet broad, and 10 feet deep,
has engines of 75 horse-power, and can dredge in 28 feet depth of
water. It has a single bucket ladder, and loads into hopper barges.
In the year 1881-82 this machine dredged 246,480 cubic yards or
308,100 tons of material in 2740 hours. The sum for wages, coals,
and stores for the year was £1331, and for repairs £2626. The
original cost of the machine was £17,653.
No. 9 Dredger is 161 feet long, 29 feet broad, and 10 feet deep,
has engines of 75 horse-power, and can dredge in 30 feet depth of
water. It has a single bucket ladder, and loads into hopper barges.
In the year 1881-82 this machine dredged 323,760 cubic yards or
404,700 tons of material in 2694 hours. The sum for wages, coals,
and stores for the year was £1108, and for repairs £947. The
original cost of the machine was £16,160.
The Clyde Trustees have a fleet of eighteen steam screw hopper
barges, built of iron; the first four of the fleet carrying 240 cubic
yards or 300 tons each, and the remaining fourteen 320 cubic
yards or 400 tons each of dredgings. The dimensions of these
vessels vary from 130 feet by 23 feet by 9½ feet to 150 feet by
26 feet by 12 feet, and their first cost ranged from £4326 to
£7660 each. The maximum draught of the vessels is 11½ feet
when loaded and 8 feet 2 inches when light, and the speed attained
is from 8 to 9 miles per hour. The punts used for carrying the
dredgings from No. 7 dredger are each about 32 feet long, 15 feet
broad, and 3 feet deep, and contain about 8 cubic yards or 10 tons of
material. The punts are towed in trains by a tug steamer 105
feet long, 20% feet broad, and 9% feet deep, with engines of
80 horse-power nominal. The ordinary speed of the tug when not
towing is about 8 miles per hour, and its original cost was £3885.
The average cost of dredging on the Clyde between Glasgow
harbour and Port-Glasgow, and depositing, chiefly in Loch Long,
for the year 1881-2, was 6'94 pence per cubic yd.; average cost for
the last four years 5'97 pence per cubic yd. 2400 hours per annum
may be taken as the average actual working time of each dredger.
During the 38 years from 1844-5 to 1881-2 the Clyde Trustees
have expended £706,230 in dredging from the river and Glasgow
harbour 26,382,854 cubic yds. or 32,978,567 tons of material.
IRON SHIPBUILDING.
939
EXAMPLES OF SPECIFICATIONS.
REQUIREMENTS UNDER LLOYD'S RULES.
As a fitting introduction to our Examples of Specifications, we
give the following recent requirements according to Lloyd's Rules
as to the material and construction of iron vessels.
The Iron used must be capable of withstanding a tensile strain of
20 tons per square inch with, and 18 tons across, the grain.
Keels, Stem, Stern, and Propeller Posts are to be either scarphed
or welded together.
Where the Keels and Keelsons are of several plates, the keel
plates must make a thickness equal to that for a solid keel.
The Frames are to be spaced from 20 to 26 inches apart, accord-
ing to size of vessel, and to be in as great lengths as possible, and
to extend to the gunwale.
Floor Plates are to be rivetted to each frame, and water courses
are to be formed above the frames through all floor plates. Re-
versed angle irons are to be rivetted to the frames and floor plates.
Keelsons and Stringers, when made of bulb iron, must have the
joints overlapped and rivetted, and all angle irons used for these
must be in long lengths.
Beams are to be rivetted to the frames with bracket ends or
knee plates. The spacing of beams and stringers varies with the
depth amidships.
Pillars must be fitted beneath the beams, and must have solid
welded heads and heels.
The thickness of the Plating varies with the size of vessel, and
with its position on the vessel.
Five spaces of frames is the least length of a plate.
Rivet Holes are spaced from four to four and a half diameters of
the rivet from centres. The rivets are to be of best quality, and
increased in size under the heads to fill the rivet holes.
The Foremost or Collision Bulkhead must extend from the floor
plates to the upper deck, as also the engine-room and aftermost
bulkhead, and their water-tightness must be tested by hydraulic
pressure.
Double Bottoms must be made so as to permit examination
through manholes; tested with water pressure.
940
MODERN STEAM PRACTICE.
Cement is to be used for coating the frames and plating of the
bottoms of vessels to the upper part of the bilges.
I.-SPECIFICATION OF A SCREW STEAMER OF 17678 TONS.
Service.-The vessel to be employed in the conveyance of the mails and
passengers between New Zealand and
a distance of about 7000
knots, without a calling station. She is to be provided with water-ballast
tanks, containing about 100 tons to compensate in a measure for the
lightening of the ship as the fuel is consumed.
Performance. The vessel is to carry 1200 tons of coal in the holds,
bunkers, and water-ballast tanks, in addition to other necessary stores, and
when so loaded she is to run on an average 13 knots per hour under
steam only, with a consumption of fuel not exceeding 274 tons of coal per
day of 24 hours. The purchasers are to decide on the duration of the trial,
which is to be undertaken at the risk and cost of the builders.
Guarantee.—The builders are to guarantee the purchasers free from cost
of rectifying any accident arising from defective proportions, material, or
workmanship, which may occur to either ship or machinery for twelve
months after the final completion of the work.
Time of completion.-The vessel to be completed and ready for service
within eight calendar months after date of order.
Accommodation. The vessel is to have a saloon and other accommoda-
tion for as many passengers as can be put on main deck. The fittings of
cabins to be equal to those in vessels on similar services, belonging to the
Peninsular and Oriental Steam Navigation Company. She is to have mail,
post-office, sorting, specie, and baggage rooms, also all necessary store
rooms for the accommodation of officers and crew.
Class. She is to be built under Lloyd's special survey, and to be
classed AA as a spar-decked ship. Should any scantlings or other details
in this specification be shown, to the satisfaction of the company's surveyor,
to differ from the requirements for the above class, such parts are to be
modified accordingly.
Certificate.—The vessel is to be provided with a Board of Trade certificate.
Drawings.-Drawings showing the detail arrangements of cabins, &c.,
are to be provided and submitted to the builders, and must be approved of
in writing by the purchasers.
Specification. The specification is not supposed to indicate every detail
which will require the attention of the builders. It is given as a fair
description of the class of vessel required. The vessel is to be completed
and equipped in all points equal to any ship of her class, notwithstanding
any omission in the specification of items necessary for that purpose,
IRON SHIPBUILDING.
941
excepting only chronometers, plate, linen, cutlery, stone ware, glass, and
bedding. No payment will be made beyond the contract price of the ship
on account of extra work or materials, unless the same shall have been
authorized in writing as extras by the purchasers.
Surveyors.-The whole of the work to be done to the satisfaction of the
company's surveyors and inspectors, who are to have free access to inspect
the progress of the work during all ordinary working hours while the ship
is building; and they are to have power to reject any material or workman-
ship which in their judgment is not in accordance with agreement.
Payments.-Payments will be made on the certificates of the surveyors
that the work has proceeded, to their satisfaction, to the stages at which
payments are agreed to be made.
Materials.-All materials used in the construction of the ship are to be
the best of the respective descriptions. The iron is to be of such quality
that the tensile strain requisite to break it shall not be less than 20 tons per
sectional square inch on the dimensions of the bar before it is tested. The
builders are to test any portion of the iron, and in every way satisfy the
surveyors that it is of a suitable quality. Each plate and bar is to be
branded with the maker's name.
General specification of workmanship.-The butts of all plating and
stringers, as well as those of centre plates and side bars of intercostal
keelson and keel, are to be planed and drawn hard together. All butt
strips are to be equal in section to the plates or angle irons that they are
intended to connect, and are to be so cut that the grain of the iron runs in
the same direction as that of the parts to which they are attached. Butt
strips on beam stringers and ties to be on the under side. All lugs or short
second reverse bars or frames for the attachment of stringers are to be of
the same scantlings as reverse bars, and fixed with at least four rivets. The
liners behind frames at alternate strakes of outside plating, and wherever
required, are to be in one piece, accurately filling the space in length,
breadth, and thickness. All countersinking is to be done through the
entire thickness of the plate. The rivet holes to be fairly opposite each
other. Should any unfair holes occur they are to be rimered out. The
holes are to be punched from opposite sides of the parts to be connected
together, so that the small end of the tapered holes, formed by the act of
punching, may lie against each other. The rivets are completely to fill the
holes, are all to be laid up close round their heads, and those in counter-
sinks are to be cut off outside, fair with the surface of the plates, excepting
those through garboard strakes and keel, where they should be slightly
rounded. Wherever double or treble rivetting is required, the rivets are to
be in straight rows, square with the edge of the plate (chain rivetting), and
are not in any case to be "zigzag." All surfaces rivetted together are to
942
MODERN STEAM PRACTICE.
bear fairly against each other through their length and width, so that a knife
the thickness of which does not exceed No. 26 Birmingham wire gauge
cannot be introduced between them at any part. All stringers are to be
continued fore and aft; bulkheads and other obstructions to be notched and
made good up to them. Wherever a stringer has to be cut, as in the engine
room or elsewhere, the loss of strength is to be compensated for by other
arrangements, to be approved of by the company's surveyors. It will be
preferred that the floor plates and reverse bars, as well as the various angle-
iron lugs, be rivetted to each frame before it is set up in position. It will
also be preferred that the landing holes in the frames to receive the beams
of outside plating be marked from the plates and drilled.
Dimensions.
Length between perpendiculars,
Beam,
...
...
Depth from top of floors to top of spar deck,
Tonnage O. B. M.,.
Engine, nominal power,
...
...
...
...
...
285 ft. 0 in.
35,, 6
26 8
17679 tons.
350 H.P.
11
""
Keel.-To be formed of a centre plate 35 inches by inch, with two
3
16
side plates 9 inches by 1 inch at the bottom, with a flat plate on top of
floors 36 inches by 4 inch, and two angle irons 5 inches by 6 inches by
inch.
16
14
Stem.-Of best scrap iron, average size 9 inches by 3 inches, properly
scarphed and attached to keel.
9
6
Frames.-To be of angle iron 5 inches by 3 inches by inch, spaced
21 inches apart from centre to centre throughout.
Reverse bars.-To be of angle iron 3 inches by 3½ inches by ½ inch,
extending to main deck and spar deck alternately.
Floors.-To be of plate iron 26 inches by ½ inch at centre, and ½ inch
at ends, tapering in depth to size of frame at bilge.
9
11
16
Intercostal keelsons.-An intercostal keelson on each side of main keelson,
fitted between the floors, of plate 1 inch thick, with double angle iron
5 inches by 6 inches by inch on each side of the plate, to extend under
engine and boiler room, and to continue as much farther forward and aft
as may be thought necessary.
9
16
Bilge keelson.-To be framed of two bars of angle iron 6 inches by 5 inches
by inch, carried as far fore and aft as it can be got. To be rivetted to
double reverse angle irons, and to have an 8½-inch by inch bulb
plate betwixt as far as engine and boiler room extends.
9
16
Spar-deck beams.-To be of bulb iron 8½ inches by ½ inch, with knees
properly on, and double angle iron on upper edge 2½ inches by 2½ inches
by inch.
5
16
Main and lower deck beams.—Of bulb iron 8½ inches by 2½ inch, with
#
IRON SHIPBUILDING.
943
knees properly welded on, and double angle iron on upper edge 3½ inches
by 3½ inches by 3% inch.
Beam stanchions.—To be provided where necessary.
10
10
16
Spar-deck stringers.—Of plate iron 36 inches by 18 inch amidships, taper-
ing to 27 inches by 18 inch at ends, with angle iron 5 inches by 4½ inches
by inch all round the ship.
9
11
16
Main-deck stringers.—Of plate iron 42 inches by 3/4 inch amidships,
tapering to 31½ inches by 1 inch at ends, fitted to skin with a 5-inch
by 4½-inch by inch angle iron rivetted to skin and stringers, and a
continuous bar 5 inches by 4½ inches by inch carried all round the ship
inside of the frames.
9
6
9
Lower-deck stringer.-Of plate iron 31 inches by 18 inch all round the
ship, with an angle iron 5 inches by 4½ inches by inch.
9
16
Bilge stringer.—To be formed of two bars of angle iron 5 inches by
4½ inches by inch, rivetted back to back, and to double reverse bars
placed between the bilge keelson and lower-deck stringer.
16
Deck ties.—On spar deck to be 14 inches by 18 inch; on main and lower
deck, 14 inches by 18 inch, placed on each side of hatchways.
16
Bulkheads.-Four water-tight bulkheads to be carried up to main deck
of-inch plate iron, stiffened with 3½-inch by 3-inch by ½-inch angle
iron, and fitted with two sluice valves to each, worked from main deck.
Outside plating.-Garboard strakes, 18 inch; bottom, 12 inch; sides,
1 inch and 18 inch; main shear double, 3/4 length, 12 inch.
18
10
13
16
Rudder.-Stock, 7½ inches diameter, with 4-inch pintles 3½ inches
diameter, the frame all welded in one piece, and plated with 5-inch plates;
to have a stuffing box on deck, and to be fitted with a screw-steering
apparatus and two steering wheels.
Rivetting.-The whole of the rivetting to be as per Lloyd's Rules, of the
best material and workmanship.
Water tanks. To contain 3000 gallons, with plumbing work complete.
Coal bunkers. To suit arrangement with engine.
WOOD WORK.
Waterways of main deck and spar deck to be formed of
teak, as per Lloyd's, and well secured by bolts and nuts.
The Decks shall be of sound yellow pine, free from objectionable knots,
strakes, or defects. The spar deck, 5 inches by 3 inches; main deck,
6 inches by 4 inches, securely bolted with galvanized bolts and nuts, and
dowelled; teak plank to be laid for capstans, stoppers, riding bitts, where
eye bolts have to be fixed, and in range of chain cable. The space below
beams under capstan to be filled in solid, and lined with 2-inch elm plank.
Hatch combings.-To be of oak or teak 4 inches thick, and protected with
galvanized iron.
Bulwark stanchions.—Of oak or teak 5 inches by 4½ inches, with clead-
944
MODERN STEAM PRACTICE.
ing of 134 inch thick, to be lined and panelled inside, except forward and
aft, where the iron work will be carried up.
Main rail.—Of teak 11 inches by 3 inches, protected with yellow metal
where any chafing may be expected.
Ceiling in bunker and hold.-To be of American elm, 2½ inches thick,
to be fitted to the under side of bilge stringer between frames and caulked;
above this to be sparred 6 inches berth, and space with 2-inches stuff.
Hawse pipes.-Four in number, two to each bow, of cast iron, properly
fitted and secured; other pipes as required.
Cat heads. Of wood or iron, as may be arranged, with stoppers complete.
Top-sail sheet bitts.-Round masts to be of teak, capped with brass.
Boats.-The ship to have a full set of boats as required by the Board of
Trade, complete with blocks, falls, spars, &c., and two sets of lowering
apparatus.
Bollards.—Of sufficient dimensions and in number as may be required,
with mooring pipes and fair leaders as may be arranged.
Scuppers. Of lead of the best construction.
Anchor davits.-Fitted with blocks, falls, &c., complete.
Chains and anchors.-As per Lloyd's Rules, properly tested, and the
certificate given to the purchasers.
Chain lockers. To be fitted of elm, 2½ inches thick, in a convenient
position, with a provision for getting inside to stow cable.
Anchor capstans.-Of approved construction, with movable stops, wrought-
iron bitts, &c., and worked by steam power.
Warping capstans.—To be placed in position to be arranged.
Cabins. To be arranged according to a plan to be approved of; fitted
in a comfortable, substantial, and elegant manner, with cabinet work
and upholstery work complete, with tables and oil covers to each, seats,
sideboards, mirrors, and clocks, stoves, water closets, baths, and basins,
with ewers and tank complete. This work to be done in a manner similar
to vessels recently built by the P. and O. Company.
Officers and seamen.-Accommodation as arranged for on the plan to be
approved of.
Ventilation.—The cabin and engine room to be ventilated with suitable
apparatus.
Galley. To be fitted with approved cooking and distilling apparatus,
sufficient for crew and passengers, and the floor fitted with tiles.
Mail room. Specie room, post office, sorting room, store rooms, &c., to
be fitted up in the best manner, and as arranged on drawing to be ap-
proved of.
Hen coops, sheep pens, &c.—To be of teak, made and fitted where may be
arranged.
IRON SHIPBUILDING.
945
Carving. To be neatly executed in accordance with the name of the
ship.
Rigging. The vessel to be barque-rigged according to plan to be
approved of, with a full set of masts and spars. The lower masts to be of
iron, fitted with lightning conductors. Standing rigging of galvanized wire
rope; remainder of hemp and manilla, fitted with a complete set of blocks
and dead eyes, and all iron work connected therewith; dead eyes to be of
lignum vitæ; halyard brace blocks to have patent roller bushes; chain plates
to be outside on channels.
Sails.—To have two complete suits of sails of best long flax canvas, the
number to be hereafter decided by company's superintendent;
one suit of
sail covers to be provided; two of the boats to be fitted with masts and sails.
Awning.—To be fitted to cover the entire spar deck, with stanchions of
galvanized iron, ridge ropes, and all complete.
Winches. To have two steam winches, with derricks, gins, and chains
complete.
Side ports.-There shall be brass side ports, two to each cabin and state
room, all 10 inches diameter in the light. Iron port riddles to be provided
outside and rivetted to plating.
Water ballast.-Tanks, or water holds, to be provided, capable of con-
taining 100 tons of water, with all the requisite fittings for filling the same
and emptying them from the engine room.
Screw tunnel. To be provided as required for the engines, and to be
fitted with a water-tight door at engine bulkhead.
Plumbing and glazing.-To be done in the best and most substantial
manner; all glazing to be in best plate glass.
Hawsers. As required by the Board of Trade.
Sky lights.-Companions and other deck fittings to be of teak.
Galvanizing.-All stanchions, eye bolts, &c., above deck to be galvanized.
Boats' davits. Of iron, of the requisite number and size, and securely
fixed.
Pumps.-A 6-inch pump to be fitted on each deck, with all proper con-
nections, and so as to pump from holds and sea, and acting as a fire engine,
the requisite length of leather hose for direction pipes being provided; also
pumps on each deck from fresh-water tanks.
Compasses.-There shall be four compasses with 12 cards, with binnacle
lamps, and everything complete. One compass fitted as a standard com-
pass (approved Azimuth), to be at such elevation above deck, and in such
a position as may be thought advisable. The steering compass to be one
of the best Liquid. The other two compasses to be by Blackney on his
improved anti-vibration principle. Adjustments of compasses to be made
by a competent person, appointed by, or approved by the purchasers.
60
946
MODERN STEAM PRACTICE.
Bells.-There shall be two bells, one in a brass and the other in a cast-
iron belfry, with ship's name engraved thereon.
Flags.-One Barque, one Union Jack, one Blue Peter, one Company's
flag, and a full code of signals, with books, all fitted in lockers.
Accommodation ladders.—One on each side, with platform davits and
fittings complete; these and all other ladders to be of teak.
Guns.-There shall be two 9-pounder guns, with 2 ports forward and 2 aft.
Cement. The vessel to be coated with approved composition inside, and
an approved paint outside.
Painting.-All the iron work to receive two coats of red lead, or other
approved paint. The outside to have other two coats, as the superintendents
may approve. All wood work, where not grained and varnished, to receive
four coats of paint, or if grained to have two coats of paint besides varnish.
Lamps. The set of Admiralty signal lamps, three globe hold lanterns,
cook's lanterns, and two forecastle lamps. Also proper lamps for saloon
and cabins throughout ship.
Life buoys.-Four buoys with ship's name on each, and four cork fenders.
Tarpaulings. Two tarpaulings for each cargo hatch, covers for wheel
binnacles, skylights, and boats.
Cooper's stores.-1 dozen deck buckets, 1 dozen fire buckets, 1 dozen
mess kids, 4 harness casks, 2 steep tubs, with galvanized iron hoops.
Brass speaking trumpet.
One fog horn.
One 14 second glass.
One 28
do.
One deep-sea lead and line.
Two hand leads and lines.
One log reel.
Two log lines.
One patent log and line.
One grindstone and trough.
One dozen paint scrubs.
paint brushes.
brooms, assorted.
hooks and thimbles.
marline spikes.
deck scrapers.
coir door mats.
paint pots.
Sundries.
Two dozen sail needles.
Half
sail hooks.
Half
One
hanks.
handspikes.
One pitch pot and ladle.
Four oil feeders.
Two oil funnels.
One crosscut saw.
One axe.
Six chisels.
One hand saw.
Two tillers.
One safety hold lantern.
One spare shackle, fall and anchor.
One dozen chain hooks.
Two hooks for fishing anchor.
Two chain stoppers.
Two shank painters.
One
One
Two
One
""
One
One
Half
""
""
""
Half ""
Half
ballast shovels.
""
Half
cold chisels.
""
Two
""
Three dozen spare blocks, assorted.
Six
One spare cut block.
Two
One doz. serving boards and mallets.
mops.
Three snatch blocks.
Six assorted crate and other hooks.
Six crowbars.
Two dozen hooks and thimbles, assorted.
firelocks.
pairs handcuffs.
carpet stools.
IRON SHIPBUILDING.
947
Cordage. One ton of rope.
Stores.-Spun yarn, house line, or twine, all inclusive, will be allowed as
the extra stores on board of the ship.
II. SPECIFICATION OF A SCREW STEAMER OF 2000 TONS B.M.
Dimensions and material.-Keel and fore rake, 300 feet. Breadth of
beam, 37 feet; depth moulded to spar deck, 28 feet 6 inches. Keel to
be of the best hammered scrap iron, 11 inches by 3 inches. Stem post
II inches by 3 inches, tapering to 7 inches at the top. Stern post of the
best hammered scrap iron 9 inches by 4½ inches, and inner 9 inches by
6 inches; frames of angle iron for 120 feet amidships, 5½ inches by 3½ inches.
by 18 inch, fore and aft 5 inches by 3½ inches by inch, to be spaced
throughout 18 inches from centre to centre, all to butt in keel. Floors for
120 feet amidships 26 inches by 11 inch thick, rising gradually to fore and
aft bulkheads; angle iron on top of floors to be 4 inches by 3 inches by
½ inch, running up to the main deck on every frame for 120 feet amid-
ships, and every alternate frame to fore and aft bulkheads to spar deck.
16
9
16
Keelsons.—There shall be three rows of keelsons the same depth and
thickness as floors; the centre one running fore and aft until the floors are
only 3 feet long, and the side ones until the floors are only 12 inches long;
centre one with two rows of angle iron, 8 inches by 3 inches by ½ inch
thick; side ones with two rows of angle iron, 5 inches by 3 inches by
½ inch thick.
Engine and boiler seats.-According to drawings furnished by the
engineers. Engine seats to be all furnished with 5%-inch plates.
13
Plating.-Garboard strakes % inch; from that to bilge strake 18 inch;
bilge strakes 12 inch; two next strakes 5% inch; sides ½ inch, above that
5% inch; second strake from top ½ inch; top strake 18 inch.
13
Rivetting.—Rivets to be of the best iron, the whole ship to be double
rivetted horizontally and vertically, and about 10 to 12 rivets in each foot
of double rivetting. Single rivetting above main deck. The rivet heads.
to be of the usual proportion, and properly hammered up, the plates
having all the holes countersunk. The frames to be rivetted to the plates
with a suitable number of rivets depending on the width of the plates.
Behind each frame a filling piece or lining piece must be fitted as thick as
the jointing strap over which the frame passes; the plates to be fitted all
close, and no filling piece of iron or any other material is to be used.
Beams.—Main-deck beams to be of plate iron 12 inches deep and 5% inch
thick, with two angle irons 3½ inches by 3½ inches by ½ inch rivetted to
top edge, and half rounds rivetted to bottom edge (or bulb iron may be
used); all the deck beams to be in one length. Twixt-deck beams to be of
948
MODERN STEAM PRACTICE.
plate iron 9 inches by ½ inch, with two angle irons at top 5 inches by
3 inches by ½ inch, and half-round iron at the bottom edge; spar-deck
beams to be of patent iron 8 inches deep; all the beams to have knees
properly welded on, and securely rivetted to the frames.
Spaces.-Main-deck beams to be spaced every third frame, likewise for
the twixt and spar deck.
Knees.—To be 2 feet long in the arm throughout.
10
16
9
Stringers.—Main-deck stringers to be of plate iron 42 inches by 3/4 inch,
with angle irons 5 inches by 4½ inches by inch; spar-deck stringers of
plate iron 36 inches by 18 inch, with angle iron 5 inches by 3 inches by
½ in.; twixt-deck stringer of angle iron, back to back, 8 ins. by 3 ins. by ½ in.
Bulkheads. —Six in number, or as many as may be considered necessary,
to be of ½-inch plates, with angle iron 4 inches by 3½ inches by ½ inch,
spaced 2 feet apart, made perfectly water tight, and two of them for the engine
room to be made water tight to spar deck. The frames of the ship, to which
they are to be fastened, to be double.
Diagonal plates.-To be placed on main and spar deck beams where
practicable, with side plates on each side of hatchways from stem to stern.
Rudder.—To be of suitable size and strength; the stock to be 6½ inches
diameter; plates, ½ inch.
Coal bunkers.—To contain 750 tons of coal, and to be placed according
to the direction of the engineer.
Tanks.—To contain 8000 gallons of water. A tank to supply water
closets to be fitted and arranged so that a condensing apparatus can be
made of it; the description to be given by engineer, as it will be connected
with a small pump worked by the engine to force water into the tank to
condense steam.
Twixt decks.-If considered necessary, to be of iron plates 4 inch thick,
to be rivetted to beams and perfectly water tight. Stanchions for hold beams
to be of 4-inch round iron, or 5-inch wrought-iron piping, as may be
decided, and to be placed where thought necessary.
WOOD WORK.—Waterways for main deck of Moulmein teak, 13 inches
by 7 inches; spar and twixt deck, Moulmein teak 12 inches by 5 inches.
Deck planks.—The main deck to be of yellow pine 3½ inches; spar deck
3 inches; tween 2½ inches, if iron 4 inch; stanchions of African oak on
teak 6 inches by 5 inches, excepting where davits are secured, and then
they are to be of increased strength.
Rails. To be of Moulmein teak 7 inches by 2½ inches, and lined on
both edges with yellow pine.
Ceiling. From keelsons to bilge to be of elm 2½ inches thick; from
bilge to lower deck beams to be spaced with half-round iron 1 foot from
centre to centre.
IRON SHIPBUILDING.
949
Capstans and riding bitts of approved construction to be provided where
usual; two on the quarter deck to have brass heads.
Winches.-Three or more winches to be provided as may be found
necessary, and all chain and cargo gearing connected therewith.
Pumps.-Manual-labour pumps with copper chambers 7 inches diameter,
to be fitted complete for working into each compartment.
Boats.—Six in number shall be provided of a size to be afterwards given;
davits to be 4 inches in diameter.
Masts, sails and rigging, &c.—The ship to have three masts of iron, to
be barque-rigged; the rigging to be either of wire or hemp, or both. Sails.
to be of the best canvas. Anchors and cables according to Lloyd's regula-
tions. Rigging chain of all sizes that may be required.
Steering gear.-To be of the most approved construction.
Binnacles. To have as many as the adjuster of compasses may think
necessary for the safe navigation of the ship; also liquid compasses to be
supplied: all of an approved make.
Cabins, &c.-To be fitted up complete like those of similar vessels on the
station in all joiner, ironmongery, brasswork, ventilators, deck lights, paint-
ing, and ornamental work; to have main berth fitted on main deck, and as
can be arranged to advantage; cabin plans to be submitted for approval,
with deck houses for captain, officers, and engineers. There shall be a
galley fitted complete, mess rooms, &c., and at least twenty house water-
closets. Upholstery, glass, earthenware, and silver plate not to be included.
Bulkheads, &c.—Of cabins to be 14-inch plate iron, rivetted to angle iron
on main deck. Bulkheads of state rooms to be plate iron 4 inch thick
rivetted to angle iron. Skylights and deck and side lights of glass to be fitted
with secure iron work where required for ventilation or light.
Spare mast, blocks, and rigging dead eyes to be of lignum vitæ.
All locks and hinges throughout the ship must be of brass; and all joiner's,
plumber's, painter's, and glazier's work, although not heretofore mentioned in
the specification, must be done to the satisfaction of the company's super-
intendent, or any other person that may be appointed to inspect the same.
Sundries.-The owners will furnish at their own expense all upholstery,
linen beds and bedding, cooking utensils, earthenware, crystal, plate, cutlery,
and all other steward's furnishings, but the contracting party to supply
everything else, although not mentioned.
•
III.-SPECIFICATION OF A SCREW STEAMER OF 790 TONS B.M.
Length of keel and fore rake,
Breadth of beam,
Depth moulded,
...
...
Height of topgallant forecastle,...
::
:
200 ft. 0 in.
...
28,,
6
...
...
18
""
3,,
...
66
950
MODERN STEAM PRACTICE.
To have a poop aft 64 feet long and 2 feet 3 inches high, with cabin
accommodation fitted aft under poop deck, but should cabins be fitted on
deck the vessel to be flat decked fore and aft.
Keel.—Stem and stern posts to be of the best hammered scrap iron; keel
8 inches by 22 inches thick, made in as long lengths as possible and well
scarphed at joinings, with scarphs about 25 inches in length. Stern post
to be 8 inches by 2½ inches at bottom and 7 inches by 2½ inches at top,
and to have about 5 feet of the keel forged on it, and well scarphed to keel.
Frames. Of angle iron for 8 feet midships to be 5 inches by 3 inches by
½inch; remainder, 4 inches by 3 inches by ½ inch by inch, to be
spaced 16½ inches from centre to centre throughout.
7
16
Floors. All floor plates but those under engine seat to be 18 inches by
7 inch for 120 feet midships, the remainder to run gradually fore and aft
to 30 inches deep at peak. The floor plates under engine seat to be
24 inches deep. The angle iron on top of floor plates to be 3 inches by
3 inches by 3% inch, and run up to stringer plate of lower-deck beams, and
well rivetted to frames, the floor plates in engine and boiler space to have
double angle iron.
Keelsons.-There shall be three rows of keelsons of the same depth and
thickness as the floors; the centre one running fore and aft, until the floors
are only 3 feet long; the other two to run fore and aft as far as possible for
the run of the vessel. They shall have two rows of angle iron 6 inches by
3 inches by ½ inch rivetted back to back, and to the angle irons on the
top of floors.
16
16
Plates.-Garboard strake to be 18 inch thick from sheer to 1-foot water
line, 1 for 90 feet midships to 10-feet water line, to mouth strake, mouth
strakes 5% inch, all plates above 1 foot of the water line fore and aft to be
inch thinner, except mouth strake, which is to be tapered to inch.
thick, double rivetted in flat of floors to 2 feet of the water line fore and aft;
all butt joints to be flush, and to be rivetted with four rows of rivets. Lon-
gitudinal joints to overlap. Bulwark plates to be 4 inch thick, and flush
jointed; keel stem and stern posts to be double rivetted, as also all butt
joints throughout; all longitudinal joints to be overlapped except bulwarks.
Beams.-Main-deck beams to within 40 feet of stem from front of poop
to be 4-inch by 2½-inch angle iron, and plates 4 inch thick, 12 inches
deep at centre, and 8 inches at ends; the remainder of the deck beams to
be of angle iron 8 inches by 3 inches by ½ inch. Top-gallant forecastle
beams to be of angle iron, 6 inches by 3 inches by inch. Poop-deck
beams 4-inch by 4-inch T iron. Main top-gallant forecastle and poop
beams to be placed on every alternate frame. Twixt-deck beams from
10 to 12 feet apart of 4-inch by 3-inch angle iron, four bars and plates
8 inches by ½ inch. Lazarette and forecastle floor beams to have 8-inch
7
16
IRON SHIPBUILDING.
by 3-inch by ½-inch, and 6-inch by 3-inch by
every alternate frame; main deck knees to be 2 feet
5
16
7
6
95 I
inch angle iron on
long in the arm, and
3/8 inch thick; poop-deck knees 15 inches by inch; the remainder
18 inches by inch.
16
Bulkheads.—Five in number, one in after run as high as cabin floors;
one in fore peak; one at each end of engine space, and one abaft the fore
hold, all of 3% inch to within 5 feet of the water line, and 4 inch for the
remainder of plates, with angle iron 3 inches by 3 inches by 3% inch.
Stringers.—Main-deck stringers to be of angle iron 3½ inches by 3½
inches by ½ inch thick, with plate for 90 feet amidships 22 inches by inch
fore and aft. Poop-deck stringer to be of angle iron 3 inches by 3 inches by
3% inch, with plates 14 inches by 3% inch. Rail stringer to be 2½-inch by
2½-inch angle iron. Twixt-deck stringers to be of double angle iron back
to back 6 inches by 3½ inches by inch. Twixt-deck beams to be well
rivetted to beams and reverse frames, all the plates and stringers to be in
as long lengths as possible, and flush jointed with straps underneath and
double rivetted at joints, as also well rivetted to beams and angle-iron
stringer.
7
16
Engine beams.—All as required for engine and boilers, as also hatchways,
skylights all to suit to plan of engines.
Rudder. The rudder stock to be 5 inches diameter down to below the
counter, the remainder to be 5 inches by 3 inches, the plates to be 4 inch;
the proper steering gear, with mahogany wheel, all complete, to be con-
nected therewith, and a spare stand tiller provided.
Beam ties.—A tie of bar iron 4½ inches by 34 inch shall extend along
the top of the main-deck beams at each side of the hatchways from bow to
front of poop, and be well rivetted on top of deck beams.
Waterways and decks.-The main waterways to be of pitch pine 12 inches
by 6 inches; the main deck to be of yellow pine 3½ inches thick and 5 inches
broad, carefully screwed to deck beams; the poop and forecastle covering
boards of red pine 12 inches by 3 inches, and their decks of yellow pine
3 inches thick. Forecastle and cabin floors of yellow pine 2 inches thick.
The whole of the decks to be well seasoned and free from sap or other
imperfections.
Bulwarks.—The bulwarks to be of iron, having every alternate frame of
the vessel running up to the main rail; height of bulwarks to be from
3 feet 6 inches to 4 feet, with top-gallant bulwarks of wood about 16 inches
above main rail, carried all the way round the vessel; main rail of best rock
elm 12 inches by 3 inches, edged with yellow metal 30 ounces to the square
foot.
Windlass.—A windlass to be furnished of British oak 18 inches in the
ring, fitted with patent purchase and cast-iron whelps complete.
952
MODERN STEAM PRACTICE.
Bitts. To be of British oak of sufficient strength. The timber heads to
be covered with cast iron where required.
Masts and spars.—The ship to have three masts schooner rigged, with all
requisite spars and iron work for the same.
Sails and rigging, &c.—A complete set of sails with sail covers; two
tarpaulings for each hatchway, and boat covers shall be provided complete.
All standing and running rigging shall be furnished of the best quality,
including chains, stays, all necessary blocks of wood or iron for rigging,
warps, hawsers suitable to size of vessel, as also iron stanchions for poop
deck, capstan for forecastle, anchor and chains, one complete set as
required by Lloyd's Rules, with 100 fathoms 1-inch mooring chain.
Catheads, chocks, fenders, hawse pipes, rubbing pieces of iron, scuttles,
chains, and lockers shall be furnished complete.
Ceiling. The ceilings of holds to be laid with 2½-inch elm, and the
sides railed with 2-inch red pine, the whole to be caulked and well
ventilated; the stern and quarter timbers to be of oak or angle iron as may
be deemed most suitable. Hatchways and companions shall be all made
complete as may be required. Hawse pipes to be provided very strong and
well secured.
Cargo derricks and winches.-There shall be two crane derricks for
working main and after holds, and a winch and derrick for the fore hatch,
furnished with all chains, slings, and cargo gear necessary for loading and
unloading each hold; the two crane derricks for main and after hatchways
to be of sufficient strength to lift 4 tons, and so arranged as to swing over
the bulwarks.
Ladder.-Ladders shall be provided on each side of the vessel capable
of letting down, with strong iron hinges, and for holds and man traps, with
all other necessaries for same.
Platform above deck.—A platform about 6 feet broad shall be fitted for-
ward or aft of the funnel above the deck, with brass rail and suitable ladders
to communicate with the deck.
Top-gallant forecastle.-To come as far aft as the fore side of paul bitts,
suitable lockers to be fitted under same, as also water closet for crew. The
deck to be laid with 3-inch yellow pine.
Boats and life buoys of suitable number and dimensions, with oars
and all complete, shall be supplied in accordance with act of parlia-
ment.
Bilge pumps.-One pump shall be fitted up complete with all necessary
hand gearing and brass boxes in each division of vessel, the barrels to be
copper 5 inches internal diameter. Bilge pipes for pumps to be of lead
with suitable roses for same, also bilge pipes to be laid from each compart-
ment of vessel and connected with engine bilge pumps.
IRON SHIPBUILDING.
953
Scuppers.-To be of lead through the sides of main deck, and of such a
size and number as may be required.
Cook house.—To be of iron placed on deck before the funnel, and fitted
with suitable cooking range and apparatus, with iron bulkhead aft, and lined
with sheet lead where necessary, also fitted up with all necessary convenience
for cooks. If preferred said cook house to be all wrought iron.
Binnacle.-To be made of mahogany, having brass lamp with compass
complete; also two additional compasses, one in the captain's room, the
other where necessary, all properly adjusted.
Figure head. The figure head and all carving work suitable to name of
vessel, with carved stem and quarter, to be all richly gilt.
Flags.-One complete set of flags and set of full-size signals to be
provided.
Signal lamps.-One complete set of brass or copper signal lamps shall
be provided of the most approved make, and fitted complete with shades,
&c., according to act.
Guns.-There shall be two 4-pounder guns, with carriages, rammers,
sponge, and screws complete.
Windows.—Brass-hinged circular side windows to be fitted where required
for cabin and forecastle, to be fitted up in the usual way.
Cabins.-To be fitted up in half poop, with accommodation for ten or
twelve passengers in a neat and substantial manner, according to plan to be
approved of by the proprietors, said cabins to be fitted in a style equal to
similar vessels on the station; made complete with captain's room, water
closets, steward's bar, oil floor cloth, sofas stuffed and done up with red
plush, basin stands with marble tops and plug basins, gilt mirrors, book-
case, berths complete with hair mattresses, bolsters, pillows, and curtains,
blankets, &c.
Painting. All the wood and iron work to have coats of the best oil
paint. The cabins and deck fittings to be finished in rich colour or grained,
as may be directed by the owners.
Bells, cooper work, hose.-Contractors to furnish all cabinet and upholstery
work, one large bell and one small one; the large one to be fitted on paul
bitt, the small one at binnacle, and both to have ship's name engraved
thereon as also on steering wheel. Four water casks, two varnished casks,
and twelve buckets. Leather hose of sufficient length to go from stem to
stern of vessel, with copper conductor and keys for hose couplings.
Skylights.--Of cabins to be fitted with plate glass and brass protectors,
suitable seats to be made all round skylights, to have a neat brass railing at
front of half poop, with steps and brass railing complete.
954
MODERN STEAM PRACTICE.
IV.—SPECIFICATION OF A SCREW COLLIER OF 1500 TONS B.M.
Length over all,
Breadth of beam,.
Depth,
...
...
:
...
252 ft. 0 in.
35"
O
18 6
""
""
Keel.—To be of the best hammered scrap iron 11 inches by 2½ inches,
with long scarphs not less than ten thicknesses. Stem II inches by
2½ inches; stern post and frame of scrap iron 11 inches by 5 inches, with
a long shank piece for taking the keel, and the necessary bosses for the
screw shaft.
9
16
Frames.-Of angle iron 5 inches by 3½ inches by inch, distance from
centre to centre 18 inches. To be in three lengths in holds, one across
from bilge to bilge, and the other two down each side of the ship, to iron
ceiling from bilge to bilge, where knees are to be formed, and the frame
returning on top of ceiling, so as to give equal strength; these knees are to
be strengthened with a plate. Fore and aft of holds the frames to be in
two lengths, and securely rivetted to plating and iron ceiling.
16
Floors.-On every frame 21 inches deep and 11 inch thick, and rising
gradually at ends to suit the form of the ship.
Reverse angle iron.—To be 3½ inches by 3 inches by ½ inch, securely
rivetted to frames and floors, and to be fitted to every frame in hold, extend-
ing down alternately from gunwale, and from 18 inches above hold beams.
to iron ceiling, also on top edge of floor, from bilge to bilge fore and aft.
Keelsons. To be seven in number formed 24 inches by inch, with two
angle irons 3 inches by 3½ inches by ½ inch on each side, and strongly
rivetted to reverse angle irons.
9
9
16
Bilge keels. To be formed of bulb iron 8 inches by inch, with two
angle irons 6 inches by 4 inches by ½ inch, well rivetted to bottom plating,
and to extend for about 100 feet amidships.
7
16
Bulkheads.—Five in number of inch plates, with vertical bars of angle
iron 3½ inches by 3 inches by 3% inch, spaced about 24 inches apart. All
bulkheads to be fitted with valve or cocks at the bottom, to be worked by
handles from the deck.
7
16
Water-ballast tanks.-To be formed at the bottom of the vessel, with
plate iron ceiling extending across from bilge to bilge, and about 4 feet in
depth from top of keel, the thickness of top plating inch, securely attached
to athwart beams resting on keelsons; these beams to be constructed of
angle iron back to back 4 inches by 3 inches by inch, rivetted together
to floors, ceiling, keelsons, and frames. Knee plates ½ inch thick, and
extending at least 36 inches along ceiling beams, to be placed on each
frame under ceiling plate, and well secured to frames and beams. The
7
16
IRON SHIPBUILDING.
955
edge of plates of ceiling all round to be ½ inch thick, and the plates must
be of good quality to allow of a flange being turned on the edge, without
showing signs of weakness, the flange to be on the top side, and double
rivetted to plating of hull and bulkheads, and carefully caulked, forming the
water-tight joint between ceiling and hold of vessel. Air piping, and the
usual piping fitted with cock, for filling and discharging the water, to be
provided.
Engine and boiler seatings.-According to drawings furnished by the
engineers, to be formed of strong plates and angle irons as required.
16
Coal bunkers. To be made of plates inch thick, with stiffening angle
iron 3 inches by 3 inches by 3% inch spaced 30 inches apart, with iron stays
across where required, with four scuttles on deck and two trimming doors.
The upper edge of bunkers to form the boiler hatch, with beams to the side
of the ship.
7
16
Hold beams.—Of plates 10 inches by ½ inch, with two angle irons
5 inches by 3 inches by inch rivetted on top edge and two on bottom
edge, and to have a plate 12 inches by inch at each end, the beams to
be spaced about 9 feet apart, the plate to be well rivetted to frames and
hold stringers.
Clamp plate. Of plate iron 18 inches by ½ inch, running all round the
ship, attached to frames above hold stringer and rivetted to reverse angle
irons, and to gunwale-stringer angle iron.
Hold stanchions.-Of hollow wrought-iron pillars, or 3-inch round iron,
to be placed under and over every hold beam, and properly secured to deck
and hold beams.
Deck beams.-To be on every alternate frame formed of patent beam iron
8 inches by 5% inch, with two angle irons 3 inches by 3 inches by 3% inch
rivetted to the top edge. The beams and framing for hatchways of extra
strength. Knee plates ½ inch thick, and 18 inches on the side, to be
rivetted to deck and hold beams and frames.
Gunwale stringer.—Of plate iron 27 inches by ½ inch amidships, for about
140 feet, tapering to 20 inches by ½ inch fore and aft, with angle irons
6 inches by 4 inches by ½ inch, to be securely attached to sheer strake.
Deck ties. Of plate iron 14 inches by 3% inch, extending the entire
length of the vessel, with diagonal ties, securely rivetted to deck beams and
stringer.
Forecastle sole beams.-Of angle iron 5 inches by 3 inches by ½ inch, to
be on every alternate frame, with fore-and-aft stringer on the under side of
angle iron 6 inches by 4 inches by ½ inch, securely rivetted to each beam.
Top-gallant forecastle beams. Of angle iron 5 inches by 3 inches by ½ inch
spaced on deck beams.
Plating.-Keel strakes 13 inch; bottom, bilge, and sheer strakes 11 inch;
956
MODERN STEAM PRACTICE.
9
16
plate in line of ceiling 3/4 inch; sides inch. The gunwale to be strength-
ened with a plate 18 inches by ½ inch secured to the outside sheer strake.
The sheer strake to be carried 12 inches above gunwale all round the vessel.
Rivetting.-The keel and stern to be double rivetted, and the stern
post to be treble rivetted. All butt joints in stringer plates and deck ties
to be treble rivetted; all butts in outside plating, floor plates, plate-iron
ceiling, and keelsons to be double rivetted. The rivet holes to be counter-
sunk on outside plating, plate-iron ceiling, and gunwale stringer; bottom,
bilge, keel, stem and stern posts to be left full, or a slight round left.
Painting. All iron work to receive three coats of oil paint, and to be
painted with red lead before receiving the wood work; all the deck fittings,
&c., to be properly painted.
DIMENSIONS OF MASTS, SPARS, &c., FOR A VESSEL SIMILAR TO
No. III. SPECIFICATION.
The main mast to be 72 feet high, with head 7 feet 6 inches, heel
15 inches, partners 17 inches, cross trees 14, cap 10 inches.
cap 10 inches. Fore mast
68 feet, head 7 feet 6 inches, heel 15 inches, partners 15 inches, cross trees,
18, cap 10½ inches.
Mizen mast 65 feet, head 6 feet, heel 12 inches,
14
cross trees 10 inches, cap 7 inches.
Fore top-mast 32 feet 6 inches, heel 9 inches by 92½ inches, cap 9 inches,
top 74 inches; top gallant 12 feet 6 inches, pole 8 feet. Main top-mast
21 feet 6 inches, heel, cap 7 inches, top 7½ inches; top gallant 12 feet
6 inches, diameter 4 inches, pole 4 feet 6 inches, top 24 inches.
Jib boom.-Heel to cap 18 feet, to hounds 17 feet, end 3 feet. Diameter
at heel 7 inches, cap 10 inches, hounds 8 inches, end 5 inches.
Fore lower yard 54 feet, arms 2 feet; diameter 11 inches, at ends
6½ inches. Top-sail yard 40 feet, arms 2 feet, slings 8½ inches, ends
4½ inches. Top-gallant yard 26 feet, arms 1 foot.
Gaffs.-Fore gaff 31 feet; diameter at middle and lower end 8 inches,
upper end 6 inches. Main gaff 32 feet, middle and lower end 8 inches,
upper end 6 inches. Mizen gaff 25 feet, middle and lower ends 5½ inches,
upper end 4 inches.
Booms.-Fore boom 38 feet, diameter at middle roinches, fore end 7 inches,
after end 7½ inches. Main boom 37 feet, diameter at middle 11 inches,
fore end 7½ inches, aft end 8 inches. Mizen boom 32 feet, diameter at
middle 8 inches, fore end 5½ inches, aft 5½ inches. Studding-sail boom:
lower 30 feet, sheet 8 inches, ends 5½ inches; top mast 26 feet, sheet
6 inches, ends 4 inches; top gallant 19 feet, sheet 4½ inches, ends 3 inches.
Martingal 7 feet by 1½ inch by 14 inch.
Cross trees.—Fore 9 feet aft, 8 feet fore, dimensions at middle 4 inches
IRON SHIPBUILDING.
957
by 4½ inches, end 2½ inches by 4½ inches; main single 13 feet, dimen-
sions at middle 4 inches by 4½ inches, end 2½ inches by 4½ inches; mizen
single 8 feet, dimensions at middle 3½ inches by 3 inches, end 3 inches by
2 inches.
Mizen shrouds,
Topmast rigging,
Topgallant backstay,
Mizen stay,
Topmast stay,
Main shrouds,
Topmast stay,
Topgallant,
Stay,
Fore stay,
Jib,
...
Topmast stay,
Topgallant,
Funnel shrouds,
...
:
...
:
:
:
:
Mizen Rigging.
...
:
:
:
:
...
:
...
:
:
:
:
:
:
:
:
...
6 in. ropes, or equivalent.
3
2
52
34
62
4
314
6½
8/2
614
5
44
7
""
""
""
""
""
""
་
""
Best bower,
One spare do.
Small bower,
...
...
Stream,
...
...
Anchors.
cwts. grs. lbs.
23 2 12
1
21
0 0
One kedge,
One do.
Boat's anchor,
10 O
Chains.
...
Best bower cable,
Mooring chain,
Small bower cable,
:
:
:
...
:
cwts. qrs. lbs.
400
2 O O
I O
...
:
...
120 fathoms I in.
80
120
I
5
I
11%
ह"
EXAMPLES OF SCANTLING.
SCANTLING FOR A CLYDE RIVER BOAT (225 Ft. Keel).
Length of keel and fore rake,
Breadth of beam,
:
225 fect.
21
...
9 ";
Depth,
...
Keel, 4 in. x I in.
Frame, 2½ in. x 2½ in. ×
in.
Deck beams, 3 in. x 2½ in. x
in.
16
Cabin floor beams, 2½ in. x 2 in. x in.
Floors, 10 in. x in.
5
16
! Deck stringer, 12 in. × ¾% in.
Bulkheads, 4 in. and in.
T6
Plating garboard strake midships, ¾ in.
Fore and aft, in.
5
Remaining strakes, in.
18
Paddle beams, 9 in. × 12 in. × ¾½ in. plates. Midship, fore and aft, ¼ in.
958
MODERN STEAM PRACTICE.
SCANTLING FOR A CLYDE RIVER BOAT (154% FT. KEEL).
Length of keel and fore rake,
Breadth of beam,
Depth,
...
...
Keel of angle iron, 3 in. x 3 in. x 3 in.
Stem, 2½ in. × 5% in.
Stern post, 12 in. at top, 4 in. at bottom,
3/8 in. thick.
Frames for 75 ft. amidship, 2½ in. × 2½ in.
× 1/4 in.
Fore and aft, 2 in. x 2 in. x 14 in.
...
Spaced 3 ft. apart.
154 ft. 6
16 1/2
8,, 7
""
in.
>>
Reverse frame, 2 in. × 2 in. x 14 in.
Floors in boiler space, 6 in. x 18 in.
3
16
Do. in engine space, 17 in. × in.
Deck beams at middle, 3 in. × 2½ in. x 3 in.
Do. fore and aft, 3 in. x 2 in. x 4 in.
Knees, 12 in. x in.
Plating.
For 63 ft. amidship.
Keel strake,
Remainder at bottom,
Bilge and top sides,
Counter,
Bulkheads, in.
3
18
...
1/4 in plates.
3
I6 "
3
""
...
16 "
3
16
16 "
:
Stiffening angle iron, 3 in. × 3 in. x 3 in.
Coal bunkers, % in.
Stiffening angle iron, 134 in.
Paddle beams, 8 in. deep x 3% in.
Angle iron for do., 3 in. × 2½ in. × 3% in.
Engine beams of two plates, 16 in. × ¾½ in.
Angle iron for do., 2½ in. x 2½ in. x 38 in.
Connecting knee plates, 3% in.
Angle iron for do., 2½ in. × 2½ in. × ¾ in.
Frame for pillow blocks, 6 in. × 3 in. × ½ in.
Angle iron for do., 3 in. × 3 in. × ½ in.
Top plating, ½ in.
Stanchions of oak, larch, and red pine.
Paddle boxes, 4 in. x 3 in.
Bulwark do. 3 in. x 3 in.
Quarter timbers, oak, 7 in. x 6 in.
Stern timber, larch, 5 in. × 4 in.
Gangway stanchions, 6 in. sq.
Remainder, 3% in.
...
Fore and aft.
1 in. plates.
3
16 ”
/%
""
""
Wing wales, 38 in. deep x in.
Stiffening angle iron, 2½ in. × 2½ in. × ¾ in.
Wing carlings, plates in.
5
16
Edge angle iron for do., 2 in. x 2 in. × ¼ in.
Gunwale for 47 ft. amidships, 15 in. × 3% in.
Fore and aft, of 2½ in. x 2½ in. x 4 in.
Bilge keel for 80 ft. amidship, 4 in. plates.
Radius of do., 2 in., projection 5 in.
Angle iron for do., 2 in. × 2 in. × 4 in.
Rudder stock, 7½ in. diam., ½ in. thick.
Plates of do., 1 in. × 4 in.
Wood work.
Top of paddle boxes, yellow pine, 2 in.
Cleading for do., I in.
Stern plank, 2 in.
3
16
Rails of elm, 6 in. x 2 in.
Paddle box rims of elm, 4 in. x 24 in.
Covering boards of red pine, 12 in. × 2½ in.
Deck planking, from stern to midship, 5 in.
x 2 in. yellow pine; from midships for-
ward of Memel, 7 in. × 2 in.
I
Cabin soles, fore and aft, of elm, 14 in.
thick.
Bearers for cabin sole, 2 in. square.
SCANTLING FOR A SMALL RIVER BOAT ON THE THAMES.
Length of keel and fore rake,
...
Breadth of beam,
...
Depth,
...
...
...
Draught without passengers,
:
...
...
126 ft. 0 in.
13,,
7
""
O
2 6
,,
""
""
IRON SHIPBUILDING.
959
Keel, 6 in. x ½ in.
Stems, 6 in. x ½ in.
Plating garboard strake, 4 in.
Bottom and bilges,
Sides, in.
Bulkheads, in.
Coal boxes, in.
in.
5
16
Frames, 2 in. x 2 in. x in.
Spaced amidship, 18 in.
Do. fore and aft, 24 in.
Engine bearers, 12 in. deep.
Do. thickness of plate, 4 in.
Distribution of the weight of machinery,
30 ft. in length.
SCANTLING FOR A SMALL PADDLE STEAM VESSEL OF STEEL.
Length between perpendiculars,
Breadth of beam,
Depth,
...
...
:
...
150 ft.
::
...
20 ft.
3 ft.
I ft.
Draught of water,
Frames of angle iron, 134 in. x 1½ in.,
18 in. centre spaced.
Keelson plates, 9 in. ×
in.
Angle bars for do., 1½ in. x 134 in.
I
Floor plates, 9 in. × in. every fourth
1
frame.
Gunwale of angle iron, 1½ in. × 134 in.
Plating and Rivets.
Bottom plates to 12 in. water line, ½ in.
3
Sides, in.
Rivets for %-in. plates, in.
3
ठ
Do. -in. do. 3 in.
3
Bulkhead plates, in.
Angle iron for do., 134 in. x 1½ in.
Main-deck beams of 2½ lbs. angle iron.
Engine beams, 6 in. × ¼ in.
Angle iron for do. on upper edge, 1¾ in. ×
1½ in.
Paddle Boxes.
Paddle-box beams, 6 in. × 4 in.
Covering plates, ½ in.
Sides, in.
Σ
Angle irons, 14 lb. per foot.
SCANTLING FOR A DREDGER.
Length between perpendiculars,
...
Breadth of beam,
...
...
Depth of hold,
...
Rise of floors,
...
Camber of deck beams,
:
: :
::
...
...
...
...
::
90 ft. 0 in.
28 O
""
9,, 8
O 6
""
""
""
6
""
"9
Keel of plate iron, 8 inches x 4 inches x 3/4 inch thick; flanges, 3 inches
wide; stem and stern plates, 18 inches wide, 3/4 inch thick; frames of angle
iron, 4 inches × 3 inches × 5% inch. Floors every second frame 9 inches ×
5 inch; angle irons, 3 inches × 3 inches × 3% inch. Two keelsons, 12 inches
deep and 6 inches wide, of 4-inch plate, with 24-inch angle iron for
16
securing them together at the top and to the floors of the barge.
Deck beams of plate iron, 7 inches × 5/8 inch, with angle iron on the top
edge, and hanging knees at the sides of the barge of plate iron inch thick.
Shelf all round, 9 inches × 6 inches, plates inch thick, with angle iron
for securing to the side of the vessel.
5
16
7
16
Plates.-Bottom plates, 3/4 inch thick; top sides of ½-inch plates, with
proper weltings on the vertical joints, the whole of the rivet holes to be
countersunk.
960
MODERN STEAM PRACTICE.
50 ft. o
17,, о
6,
in.
6
04
SCANTLING FOR MUD BARGES.
Length over all,
Breadth,
...
...
...
...
...
:
Depth,
...
...
Thickness of plates,
Size of frames,
...
...
...
Distance from centre to centre,
Contents of hopper,
Weight of barge,
...
...
:
:
:
:
:
O
2½ in. x 2 in. x× ¾½ in.
...
...
:
...
:
24 in.
30 tons.
122
STEEL FOR SHIPBUILDING.
In speaking of steel as used for ship's plates it may be well to
consider what this metal is in its essential characteristics as dis-
tinguished from iron.
In ordinary pig iron the constituents are more or less as follows:
Carbon, 32; manganese, 12; silicon, 21, sulphur, 32; phosphorus,
13. In Bessemer pig, made principally from the hematite ores, we
have: Carbon, 4'5; manganese, 1'1; silicon, 2'3; sulphur, '02; phos-
phorus, 3. The noticeable point here is that the percentage of
sulphur and phosphorus is much lower in the latter pig, and it is
from the small proportion of phosphorus that this pig is so much
used in the manufacture of steel by the Bessemer process. In this
process the pig-iron, already melted in a cupola, is run into the
converter, a large vessel holding several tons, and a blast of air at
a pressure of about 20 lbs. per square inch is driven through the
molten metal for about twenty minutes. The oxygen of the air
attacks the silicon, and thereafter the manganese and carbon, an
intense heat being generated during the process. The metal is in
this manner left pretty much as a pure iron, but with the sulphur
and phosphorus untouched. A proportion of spiegeleisen or
ferromanganese is now added, which confers the requisite propor-
tions of carbon and manganese required to constitute steel.
Spiegeleisen contains,
Ferromanganese contains,.. 6.5
Carbon. Manganese. Silicon.
4'I
17'0
65 I
Sulphur. Phosphorus.
*33
'03
*07
•18
*08
*06
The whole is then run into ingots in cast-iron ingot moulds, and
it is from this that it becomes known as "ingot metal," a term
sometimes used for "mild steel."
It will be seen from this description that it is the final addition of
IRON SHIPBUILDING.
961
the constituents (notably the carbon and manganese) contained in the
spiegeleisen or in the ferromanganese that confers upon the metal
in the converter the character of steel; and further, that it depends
upon the proportions of the carbon and manganese added as to the
kind or temper of the steel so produced.
Of course it will depend on the kind of steel required as to the
final proportions of the various constituents in the finished steel, but
for boiler or ship plates these will be about as follows: Iron 99; car-
bon, 15; manganese, 63; silicon, 03; phosphorus, 06; sulphur, 06.
In the Siemens or open-hearth process of manufacture of steel,
the furnace consists of a bed of silicious sand, the walls and roof
being built up with silica or Dinas bricks. The furnace is charged
with pig iron and scrap, and by means of the combustion of a
current of heated gas and air which plays upon the materials the
whole is gradually melted. To remove the carbon, iron ore is added,
its oxygen being given up to remove the impurities in the molten
metal; thereafter the necessary quantity of carbon and manganese
is added, by means of spiegeleisen or ferromanganese, and the metal
is finally run into ingots as in the Bessemer process. The Bessemer
process is the more rapid of the two, the duration of the "blow
being about twenty minutes, but the Siemens process gives greater
facilities for examining the charge from time to time, so as to ascer-
tain its condition, the time occupied being about four hours.
Within the last year or two the Bessemer process has been
extended with success to the more phosphoric irons, such as are
found in the Cleveland district; and by what is termed the Thomas-
Gilchrist process, large quantities of steel are now turned out
from ores not formerly suitable for steel manufacture.
The essential difference lies in the lining of the converter.
This vessel, where Bessemer or hematite pig is used, is lined with
gannister, a silicious refractory lining. In the new process, how-
ever, it is lined with a basic material consisting of a magnesian
limestone, lime also being from time to time added to the converter.
In this manner the phosphorus is removed, as it combines with the
limey materials, and so leaves the iron free from this decided
enemy to steel.
The ingots, after removal from the moulds, are taken to the
heating furnaces, and thereafter placed under the steam hammer,
and after undergoing another heating are put through the rolls
until the necessary size and thickness of plate are obtained.
61
962
MODERN STEAM PRACTICE.
Considerable experience has now been gained in the working
of these plates in the ship and boiler yard, and it is found that,
to insure success in the manufacture, they should in no case be
worked at what is known as a "black heat," or about 600° F. (which
is about the temperature of boiling tallow). As this seems the
critical temperature, any work put upon the plates should take place
at temperatures above or below this. As a rule all holes should be
drilled, but if punched the plate at these parts should be afterwards
annealed, so as to reduce the local strains set up by the mechanical
action of the punching process.
The use of steel has proved most satisfactory for sea-going
vessels, and its value has been tested on several occasions where
the vessels passed over sunken rocks or went ashore, the plates being
simply bent but not broken. A saving in weight also is effected,
amounting to about 16 per cent.
Bearing upon the question of iron and steel ships, Dr. Siemens
says:¹-"A new material was introduced for the building of ships
by the Admiralty in 1876-78, when they constructed at Pembroke
dockyard the two steam corvettes, the Iris and Mercury, of mild
steel. The peculiar qualities of this material are such as to have
enabled shipbuilders to save 20 per cent. in the weight of the ship's
hull, and to increase to that extent its carrying capacity. It com-
bines with a strength 30 per cent. superior to that of iron such
extreme toughness that in the case of collision the side of the
vessel has been found to yield or bulge several feet without show-
ing any signs of rupture, a quality affecting the question of sea risk
very favourably. When to the use of this material there are added
the advantages derived from a double bottom, and from the division
of the ship's hold by means of bulkheads of solid construction, it is
difficult to conceive how such a vessel could perish by collision
either with another vessel or with a sunken rock. The spaces
between the two bottoms are not lost, because they form convenient
chambers for water ballast, but powerful pumps should in all cases
be added to meet emergencies. The following statement of the
number and tonnage of vessels building and preparing to be built
in the United Kingdom on the 30th of June last, which has been
kindly furnished me by Lloyd's, is of interest as showing that
wooden ships are fast becoming obsolete, and that even iron is
beginning to yield its place, both as regards steamers and sailing
¹ Address to British Association, Southampton, 1882.
IRON SHIPBUILDING.
963
ships, to the new material, mild steel; it also shows that by far the
greater number of vessels now building are ships of large dimensions
propelled by engine power:-
No.
Mild Steel.
Tons gross.
No.
Steam,....... 89... 159,751
Sailing,...... II... 16,800
555...
70... 120,259
Iron.
Tons gross.
929,921
Wood.
No. Tons gross.
No.
49
Total.
Tons gross.
4
100... 176,551
625...1,050, 180
6 460
...
...
4635
55 5095
...
650 ... 1,090,132
130.. 141,694
780... 1,232,826
If to the improvements already achieved could be added an engine
of half the weight of the present steam engine and boilers, and
working with only half the present expenditure of fuel, a further
addition of 30 per cent. could be made to the cargo of an Atlantic
propeller vessel-no longer to be called a steamer-and the balance
of advantages in favour of such vessels would be sufficient to restrict
the use of sailing craft chiefly to the regattas of this and neighbour-
ing ports."
As it is important to have the rust removed from all metal work
before painting, so it has been found that for steel plates it is of
importance to have the mill scale removed by some more com-
plete process than hammering. This is accomplished by placing
the plates in a bath of dilute hydrochloric acid, where they are kept
for four or five hours.
The following results of experiments on the corrosion of steel
and iron plates have been submitted recently in a paper by Mr.
Farquharson, read before the Institution of Naval Architects. The
plates were treated with dilute hydrochloric acid, and the loss of
each plate noted as follows:-
Steel
combined, .
Iron
Steel,
•
Iron,
Steel } combined, .
.
oz.grs.
0'427
oz.grs.
Steel,
4'0
7'417 Iron,
3'190
3*340 Steel
combined, .
2°337
3°327 Iron
6'0
O'297
Steel,
4'157
17.77
Iron,
Iron
4'57
The loss of the separate plates of steel and of iron appears pretty
much the same, but it is very noticeable that in the combined plates
a greater loss takes place in the iron plate, showing that electrical
action has been set up. This is of considerable importance when
we consider that in some cases iron rivets are used for fastening
steel plates.
The following table gives the weight of iron, steel, and other
metals for these volumes-I cubic foot; I square foot 1 inch thick,
964
MODERN STEAM PRACTICE.
orth of a cubic foot;
I lineal foot I inch square, or th of a square
2
2
foot; I cubic inch, or th of a lineal foot; and a sphere, I foot in
diameter. The specific gravity due to the respective weights per
cubic foot is also given, and the specific weight or heaviness, taking
the weight of wrought iron as I or unity.
WEIGHT of Metals.

METAL.
Cubic Foot.
Square Foot,
1 Inch Thick.
Lineal
Foot, Cubic
T Inch Inch.
Square.
Sphere,
1 Foot Specific Specific
Dia- Gravity. Weight.
meter.
Water
Steel.....
Wrought Iron.
Cast Iron.
Copper, Sheet
Copper, Hammered
lbs. or cwts.
480 or 4.29
450 or 4.02
lbs.
or cwts.
lbs.
Ib.
lbs.
Wro'ght
1. Iron=1.
40 or .357
37.5 or 335
3.333 | .278
3.125.260
251
7.698 1.000
236
7.217.9375
489.6 or 4.37
40.8 or .364
3.400 .283
257
7.852 1.020
...
Tin
Zinc
Lead....
Brass, Cast..
549 or 4.90
556 or 4.96
462 or 4.13
437 or 3.90
712 or 6.36
505 or 4.51
45.8 or .409
Brass, Wire......
Gun Metal…………….
Silver.....
Gold
Platinum
533 or 4.76
524 or 4.68
655 or 5.85
1200 or 10.72
1342 or 12.00
46.3 or .413
38.5 or .344
36.4 or .325
59.3 or .530
42.1 or .375
44.4 or .396|
43.7 or .390
54.6 or .488
100.0 or .893
111.8 or 1.000
|
3.813.318
3.861.322
3.208.268
3.035 .253
4.944 412
287
8.805 1.144
291
8.917 1.158
242
7.409
.962
229
7.008 .910
373
11.418 1.483
3.507.292
264
8.099|| 1.052
3.701 | .308
279
8.548 1.110
3.639.304
4.549.379
8.333 .694
9.320.777
274
8.404 1.092
343
10.505 1.365
628
19.245 2.500
703
21.522 2.796
The following table gives the volumes of iron, steel, and other
metals for these weights-1 ton, in cubic feet; I cwt., in square
feet, I inch thick; I cwt., in lineal feet, I inch square; I pound,
in cubic inches; I ton, as a sphere, in feet of diameter; and I ton,
as a cube, in feet of lineal dimension.
VOLUME OF METALS FOR GIVEN WEIGHTS.



METAL.
Cubic Feet Square Feet, Lineal Feet,
to a Ton.
1 Inch Thick, 1 In. Square,
Cubic Inches
to a cwt.
to a lb.
Diameter
of a Sphere
Side of a
Cube of
to a cwt.
I
of 1 Ton.
I Ton.
cubic feet.
square feet.
feet.
cubic inches.
feet.
feet.
Wrought Iron.
4.67
2.80
33.6
3.60
2.07
1.67
Cast Iron.
4.98
2.99
35.8
3.84
2.12
1.71
Steel....
4.58
Copper, Sheet
2.75
32.9
3.53
2.26
1.66
4.08
2.44
29.4
Copper, Hammered
3.15
1.98
1.60
4.03
2.42
29.0
3.11
1.98
Tin...
4.86
1.59
2.91
34.9
3.74
2.10
1.69
Zinc..
5.13
3.08
36.8
3.95
2.14
1.73
Lead...
3.15
1.89
22.7
Brass, Cast..
2.43
1.81
1.47
4.44
2.67
31.9
Brass, Wire.
3.42
2.04
1.64
4.20
2.30
30.3
3.24
2.00
1.61
Gun Metal..
4.28
2.56
30.8
3.30
2.02
1.62
Silver...
3.42
2.05
24.6
2.64
1.87
1.51
Gold
Platinum
.....
1.87
1.12
13.4
1.44
1.59
1.28
1.67
1.00
12.0
I.29
1.47
1.19
IRON SHIPBUILDING.
965
TEMPERING OF STEEL TOOLS.
In our Frontispiece is shown a Tempering Scale for steel tools,
devised by Messrs. Benjamin and Rose of the United States, and
intended as a guide to select the exact colour suitable for different
tools. The scale shown is a facsimile of a bar of polished steel
hardened and then tempered to all the colours exhibited. In addi-
tion to a series of practical experiments by the inventors themselves,
the scale was submitted to a large number of tool manufacturers,
before being finally adopted. The workman finds on the scale the
name of the tool which he desires to temper, and to the colour
opposite that name the steel should be tempered. The colours are
here adapted to American tool-steel of good quality, and where
other steels are employed a slight change in the relative position
of the marks may be required.
We give below the Admiralty, Lloyd's, and the Underwriters'
Registry tests for various forms of steel:—
ADMIRALTY TESTS FOR PLATE, ANGLE, BULB, and BAR STEEL.
Strips cut lengthwise or crosswise to have an ultimate tensile
strength of not less than 26 and not exceeding 30 tons per square
inch of section, with an elongation of 20 per cent. in a length of
8 inches.
The beam, angle, bulb, and bar steel to stand such forge tests,
both hot and cold, as may be sufficient in the opinion of the
receiving officer to prove soundness of material and fitness for
service.
Strips cut crosswise and lengthwise 1½ inches wide, heated
uniformly to a low cherry red and cooled in water of 82° Fahrenheit,
must stand bending in a press to a curve of which the inner radius
is one and a half times the thickness of the steel tested. The strips
are all to be cut in a planing machine, and to have the sharp edges
taken off. The ductility of every plate, beam, angle, &c., is to be
ascertained by the application of one or both of these tests to the
shearings, or by bending them cold by the hammer.
All steel used to be free from lamination and injurious surface
defects.
966
MODERN STEAM PRACTICE.
One plate, beam, angle, &c., to be taken for testing from every
invoice, provided the number of plates, beams, angles, &c., does
not exceed fifty. Steel may be received or rejected without trial of
every thickness on the invoice. The pieces of plate, beam, angle,
&c., cut out for testing are to be of a parallel width from end to
end, and for at least 8 inches of length.
LLOYD'S TEST FOR STEEL USED IN SHIPBUILDING.
Strips cut lengthwise or crosswise of the plate, and also angle
and bulb steel, to have an ultimate tensile strength of not less than
27 and not exceeding 31 tons per square inch of section, with an
elongation equal to at least 16 per cent. on a length of 8 inches
before fracture.
Strips cut from the plate, angle, or bulb steel, to be heated to a
low cherry red, and cooled in water of 82° Fahrenheit, must stand
bending double round a curve of which the diameter is not more
than three times the thickness of the plates tested.
UNDERWRITERS' REGISTRY TESTS FOR STEEL USED IN
SHIPBUILDING.
The material is to be tested in the presence of the surveyor, as
in his judgment may appear desirable, both as to tensional resist-
ance and as to cold bending.
Angle, tee, and bulb bars to be submitted to closing, and opening,
and “ram's horn" tests, as the surveyor may direct.
The ultimate tensional resistance of plates and bars to be not
less than 28 nor more than 32 tons per square inch. The cold
bending test to be as follows:-The sample to be tested to be
heated to a full red, and quenched in water, and afterwards bent
double cold without fracture, with a curvature of which the inner
radius does not exceed one and a half times the thickness of the
plate tested.
The tests to be applied as frequently as the surveyor may deem
necessary, but must not be less than one in every parcel, or in each
fifty plates or bars, or fraction of fifty.
If necessary, arrangements may be made for testing the material
at the steel makers' works, in the presence of the surveyor.
ENGINEERING WORKS, ETC.
CONSTRUCTION OF FLOATING DOCKS.
Floating docks may be arranged under two classes—plain and
navigable. The former class, or "camel," has long been in use for
transporting to the sea vessels built up rivers, taking them over
bars or banks in the bed of the river. A dock of this class is simply
a pontoon, sunk by letting water flow into it; the vessel is then floated
over it and the water pumped out, when the pontoon rises with the
vessel resting on it. When a structure of this kind is required so
large as to be capable of raising large vessels of war, it requires
more than ordinary care in arranging all the parts in a strong and
substantial manner. When such floating structures are designed
for raising vessels in a harbour or sheltered basin, the section may
be of the simplest form practicable. The basement or bottom
chamber consists of a rectangular pontoon, with side walls carried
up sufficiently high to suit the draught of water of the class of
vessels it is constructed for. As these docks are more generally
required for foreign stations, it is advisable to construct them
suitable for the largest of our ordinary war and other vessels, so
that they may be serviceable for lifting for repairs either small or
large ships.
DESCRIPTION OF TWO FLOATING DOCKS MADE FOR THE SPANISH
GOVERNMENT.
We will first proceed to describe the construction and dimen-
sions of two of the plain class of floating dock made for the Spanish
government, and in the construction of which the author was
specially concerned.
First floating dock, made in London.-Length over all 320 feet,
extreme breadth 105 feet, depth of the basement 11 feet 6 inches,
height of the side walls 48 feet from bottom of dock, breadth of the
968
MODERN STEAM PRACTICE.
I
side walls 13 feet 1½ inch, width of the inside of dock proper
78 feet 9 inches.
Second floating dock.-Length over all 350 feet, extreme breadth
105 feet, depth of the basement 12 feet 6 inches, height of the side
walls 50 feet from the bottom of dock, breadth of the side walls
13 feet 1½ inch, width of the inside of dock proper 78 feet 9 inches.
These were both constructed according to the section shown in

D
B
A
D
B
A, Basement.
Fig. 671.-Transverse Section of Floating Dock.
B B, Middle chambers. cc, Floating chambers.
DD, Engine houses.
Fig. 671. The former has a basement of 320 feet long, 105 feet broad,
and a depth of II feet 6 inches, displacing a body of water equal to
11,040 tons; this may be considered the carrying power of the dock.
The chambers placed on each side on the top of the basement are
simply to allow the water to flow in and out again as the structure
is being sunk or raised, thus greater command is obtained over such
a mass of material. Floating chambers are placed on the top of
the middle ones; these form the upper portion of the side walls,
and are intended to keep the structure afloat in the event of water
finding its way through holes accidentally made in the dock: with-
out this precaution, were the basement and middle chambers full
of water, the structure would sink to the bottom of the basin or
harbour, causing great expense in raising it. With the view of
accommodating this great floating pontoon to a vessel that may
not be placed centrally in the dock either fore or aft, or athwart
the structure, the basement is divided into ten water-tight com-
partments, formed by a central division plate extending the entire
length of the dock, with transverse bulkheads. These bulkheads.
ENGINEERING WORKS, ETC.
969
extend up the side walls to the bottom of the cellular compart-
ments at the top; thus when the weight of the vessel preponderates
more to the one side than the other, with the aid of levels placed
on each side at the top both longitudinally and transversely the
dock master can at once tell if the dock is on an even keel; and
if not, by allowing water into the proper chambers as the dock
and vessel are lifted, he can place it so. Thus the dock is raised
vertical both longitudinally and transversely. In the event of any
sudden lurch caused by the accidental shifting of the vessel, baffle
plates or splash plates are placed at each side of the central division;
by this means the water left in the basement to balance the heavy
top weight of, say, a war vessel fully armour clad is prevented
following the downward inclination, and causing the structure to
list to a dangerous degree. When no vessel is in dock the structure
can be careened for inspection and painting by simply filling one
side of the basement with water. The arrangement for doing this
forms one of the most important principles in these modern docks,
all the sluices being so arranged at the centre length, that a few
men have perfect control over the mass.
In considering the mode of construction, it was deemed advisable
to adopt a series of lattice girders, plating them on the top and
bottom in the direction of their length, and this arrangement has
proved satisfactory. As before stated, the basement is divided
in the direction of its length into ten water-tight compartments;
the dock being 320 feet in length, each of these divisions is 32 feet;
there are nine lattice girders in each division, and immediately over
them nine systems of diagonal trussing, placed from the top of the
basement to the bottom of the cellular division plates on the top of
the floating chambers. From the bottom of the inside of the floating
chambers in connection with the top of the basement diagonal truss-
ing was introduced, running from bulkhead to bulkhead the entire
length of the dock, thus connecting in a direct line the inside of the
dock proper with the top of the basement. There was no plating
between the basement and top chamber except on the sloping sides
of the dock forming one side of the middle chambers. At the top
of the slope a foot gallery ran the entire length of the dock, and the
sloping side had steps formed of angle iron and plates covered with
thick battens of wood; these steps are simply for the shoring-up
poles to rest on. There were likewise two ledges for the shoring poles,
placed on the side of the floating chamber above the foot gallery.
970
MODERN STEAM PRACTICE.
On the top of each girder balks of teak were placed for the entire
breadth of the sill, or the bottom of the dock proper, and the whole sill
was covered over with planking. Keel blocks and movable bilge block
pieces were provided and placed on the top of the balks of teak.
Vertical and longitudinal timber rubbing pieces were attached to
the sides and ends of the dock with suitable angle iron. Two
capstans and mooring bollards for each end were provided for
moving and mooring the dock; and on the top and galleries hand
rails were fitted, as likewise the necessary staircases reaching from
the top of the floating chambers down to the top of the basement.
The pumping engines were of the high-pressure type, and were
placed on the top of the floating chambers; the cylinders were fitted
side by side, and the piston rods were connected directly by means
of connecting rods to the cranked shaft, on each end of which was
placed a pinion gearing into a spur wheel, which was geared into
another spur wheel of equal diameter having a proportion of 2 to I
of the pinion. The arms of the spur wheels have bosses cast on
them for the pins of the connecting rods actuating four pumps
placed on each side of the dock. The suction pipe of the pumps
was connected to two wrought-iron barrels, on which were fitted
the sluices and pipes for the various compartments. At the end of
each pipe a bell-mouthed suction piece was fitted, extending
to within a few inches of the bottom of each compartment; thus
all the water could be pumped out of the basement, or nearly so.
This arrangement of sluices and piping materially lessened the
labour in sinking and raising the dock, all the handles for sluices.
being situated at mid length on the top of the floating chamber.
The engine seat was made in the form of a tank for holding a supply
of fresh water, and the boiler was placed at the end; the whole
inclosed in an engine and boiler house.
SCANTLING.—Lattice girders.—The top and bottom webs of girders are
double plated with 5/8-inch plates; the vertical webs are 16 inches broad
and 5% inch thick, as likewise the vertical plates at the ends, and are united
to the web plating at top and bottom, and at the middle to the central-
plate division, and to the outside plating with angle iron on each side,
3½ inches by 3½ inches by ½ inch; the diagonal trussing and bracing is
T iron 4½ inches by 3½ inches by 5% inch spaced about 4 feet 6 inches.
from centre to centre, having three verticals on each side of the central
division, with plates for securing the diagonals thereto; these lattice girders
are braced together at the top, bottom, and ends with bars of angle iron
ENGINEERING WORKS, ETC.
971
3 inches by 3 inches by ½ inch, spaced about 2 feet 6 inches apart, whose
ends are carried down, and are rivetted to the vertical and end plates of
girders, as likewise to the outside plating; they were considered necessary
in order to withstand the great head of water the basement plating is sub-
jected to; the frames were likewise braced diagonally in the direction of the
length of the dock.
Middle and floating chambers.-The system of diagonal trussing was
adopted for the middle and top chambers immediately over the lattice
girders, consisting of T iron 4 inches by 3 inches by ½ inch for the middle
chamber, and 3½ inches by 3 inches by 3% inch for the top chamber,
having vertical plates at the top, bottom, and sides, 9 inches by ½ inch and
6 inches by ½ inch, securely rivetted to the outside plating, with angle iron
2½ inches by 2½ inches by 3% inch, and these trussing frames were tied
together with angle iron 2½ inches by 2½ inches by 3% inch, thus stiffen-
ing the plating. At the corners there were suitable gusset plates, and
between each bulkhead for the middle chamber lattice work was introduced
running longitudinally, thus binding the inside plating at the top with the
basement.
Bulkheads, &c.-The transverse bulkheads are plated with 3/8-inch plates
having angle iron 3 inches by 3 inches by ½ inch on each side all round
the various compartments, and are stiffened with vertical angle iron. The
centre division plate is 5% inch thick, with angle iron on each side, top, and
bottom, 4 inches by 4 inches by ½ inch. The cellular plates at top of dock
are 3% inch thick, with angle iron on the top and bottom, 2½ inches by
2½ inches by 3% inch on each side of the plates. Manholes and doors are
fitted to each bulkhead for the convenience of getting from one compart-
ment to the other for inspection and painting, &c.
Plating. The top, bottom, sides, and ends of the basement have plates.
5/8 inch thick, and double plated immediately over the lattice girders form-
ing the top and bottom webs, making the sill of the dock from end to end
quite flat and even; the corner angle iron for the basement being 4 inches
by 4 inches by 5% inch. Half way up the outside walls the plating was
6
9 inch, as likewise the ends and inside of the dock; all the other plates
were 3% inch in thickness; and the angle iron for the middle chambers was
3½ inches by 3½ inches by ½ inch, and 3% inch in thickness for the top
chambers, placed on each side of the plates at corners.
Slope at inside.-On the sloping sides of the dock proper steps were
formed of angle iron 2 inches by 2 inches by 4 inch, plated over with
14-inch plates, on which were placed vertical and horizontal beams for
taking the thrust of the shoring poles.
Foot gallery.-Immediately over the sloping sides a gallery is formed of
angle-iron brackets 2½ inches by 2½ inches by 3% inch, covered with
972
MODERN STEAM PRACTICE.
planking secured with screw bolts, a hand rail formed of stanchions of
wrought iron, and round-iron bars being fitted from end to end. A similar
hand rail is placed all round the platform at the top of the dock, as like-
wise for the staircase from the platform to the top of the basement.
Fenders.-Angle irons 4 inches by 4 inches by ½ inch are arranged on
the sides and the ends vertically for taking the beams of wood forming the
fenders, with longitudinal beams at the top and bottom of basement, as
likewise at the top of the middle and floating chambers.
Teak beams.-Above every girder on the floor of the dock are placed teak
beams 24 inches by 18 inches at the centre, tapering to the sides of the sill,
having angle iron at the bottom 4 inches by 4 inches by ½ inch, and the
floor of the dock is covered over with teak planking 3 inches in thickness.
Sluices and piping.—As near the central length of the dock as convenient
at the bottom of the sides of basement, two sluice valves 40 inches in dia-
meter are placed on each side, having a wrought-iron pipe of the same
diameter connected to each, on which branch pipes 18 inches in diameter
are fitted for bolting the sluice valves to, one to each water-tight compart-
ment, four being placed on the side, and one at the end of the large pipe;
to these are fitted wrought-iron pipes in connection with each compartment,
each having a bell-mouthed suction piece of cast iron, conducted to within
2 inches of the bottom of the basement. The wrought-iron piping was
strongly rivetted to the bulkheads, and materially stiffened the structure.
These sluices allowed the water into the basement, and when the large ones
at the sides were closed the 18-inch sluices regulated the supply to the
pumps. Any one of the compartments could be pumped out quite inde-
pendent of the others; thus the basement formed the balancing power of
the dock. In connection with the middle chamber two large sluices
40 inches in diameter were fitted higher up on each of the sides of the base-
ment, having a large wrought-iron pipe connected to each sluice, with a
branch pipe so placed that it came exactly in the centre of one of the open-
ings in the lattice girders. A straight pipe was run fore and aft, tapering
from 40 inches to 18 inches at the end, with branch pipes on top connected to
top of the basement, through which holes were cut into the middle chambers.
These pipes were strongly rivetted to the bulkheads, holes being cut form-
ing a communication from end to end. The flow of water into the middle
chambers was thus regulated by the sluices, and the water simply flowed in
and out by gravitation.
•
Air pipes.—On the top of the basement cast-iron air pipes were fitted
from each compartment, and these pipes were carried to the top of the
dock; thus when the water was let into the basement the air was not at all
compressed, but escaped up the air pipes.
Engines and boilers.-The engines were of the high-pressure type, the
ENGINEERING WORKS, ETC.
973
cylinders being 14 inches in diameter, and the stroke 18 inches; they were
placed closely together, with the valves outside worked direct from the
eccentrics. The engines were bolted down to water tanks placed on each
side of the dock. The boilers were round, carrying a pressure of 40 lbs. per
square inch, the diameter being 5 feet 6 inches, and the length 8 feet
6 inches; furnace 2 feet 9 inches diameter, with tubes arranged around
the sides and at top on the return principle. There were 86 tubes, 2 inches
diameter, 7 feet 2 inches long, and number 7 wire gauge, and 6 tubes
at bottom, three on each side, 3 inches diameter, 7 feet 2 inches long, and
number 9 wire gauge. These large tubes at the bottom were introduced
to induce a downward draught, which they did effectually.
Pumps.-There were four pumps to each engine, 20 inches in diameter,
with a stroke of 2 feet 9 inches, driven by two pinions and four spur wheels
to each engine. The rods for working the pumps were connected to a pin
on each spur wheel. As the rods were long they had wrought-iron ends
and wooden distance pieces, the wood being embraced with straps and
bolted through and through the wrought-iron jaws, thus a strong and light
rod was obtained.
These docks were merely temporarily put together in this country. All
the plating, lattice girders, &c., were simply held together with bolts and
nuts. All the butts of the plates were planed and machine punched,
taking three holes at a time. The punching machines had tables moved
by hand, and templated and punched the plate at one movement. These
machines are invaluable for this class of work; indeed, in such large under-
takings, hand labour is out of the question. The pitch of the rivet holes
was 234 inches, and the diameter of the rivets 3/4 inch, and there were
about 1,300,000 rivets in the dock. The weight of the wrought iron, not
including the engines or machinery, was as follows:-
Hull,
...
...
Pipes and bearers,
Rivets,
...
...
...
...
...
3594 tons.
95 ""
267
""
...
Total,
...
...
...
...
...
3956
NAVIGABLE FLOATING DOCK AND BATTERY, DESIGNED BY THE
AUTHOR.
In the construction of the second class or navigable floating dock
it is obvious that a different form from the preceding must be
adopted. Such docks possess great advantages over the former
class, not merely in having the means within themselves of moving
from one station to another, or in following a fleet in time of war;
but their first cost is greatly reduced; for the labour of putting up at
++
974
MODERN STEAM PRACTICE.
first, and then taking down, and fitting up in a foreign station where
skilled labour is scarce, are saved, and also the freightage. Such
structures can readily be fitted up entire in this country, and
steamed or tugged out to their destination. With this object in

Fig. 672.—Navigable Floating Dock-Longitudinal and Deck Plans
seen, is like an ordinary ship,
The middle chamber is formed
view the writer has suggested the above form of navigable dock
(Fig. 672). The hull, it will be
having a pointed bow and stern.
accordingly, and the top chamber is curved, and the ends filled in
with lattice work, having gates at the stern just like an ordinary
dry dock, or the end of the dock may be filled up with a caisson;
with this mode of construction more water ballast can be left in
the basement when a vessel is being docked, as the dock can be
sunk to within a 'few feet of the top of the middle chamber. There
is another advantage in the proposed form-the side surface is
greatly reduced, and the wind has not so much effect as on a wall-
sided structure. With the view of making the dock complete it is
proposed to place two screw propellers at the stern, having engines
of sufficient power to propel the dock at a moderate speed. Tur-
bine wheels could likewise be adopted for that purpose, so arranged
that the water is ejected from the basement when required. Large
and commodious workshops can be arranged in the top chambers,
with punching, shearing, turning machines, &c.; in fact this type
of dock for foreign stations should be fitted up as a large floating
factory. It is likewise proposed to utilize the middle chambers
by placing guns of the heaviest calibre within them, with indented
embrasures suited for the end-on mode of attack; thus making
the dock serviceable alike in time of peace or of war (see Fig.
673). With the view of inspecting the outside plating at the
ENGINEERING WORKS, ETC.
975
bottom of the basement it has been proposed to construct the base-
ment with a series of pontoons securely bolted to the upper cham-
bers; thus any of these pontoons can be removed and lifted by the
dock, and thoroughly overhauled and painted. This is no doubt

Fig. 673.-Transverse Section of Navigable Floating Dock and Battery combined.
an object in some waters, as wrought-iron structures soon become
very foul, requiring frequent inspection; but when we consider that
all forms of docks can be careened by filling one side of the base-
ment, so that the bottom can be inspected, we see no necessity for
departing from the mode of construction already described.
CONSTRUCTION OF IRON ROOFS.
To compute the strain on a plain truss by a figure of construction.
In a truss B, Fig. 675, there are three bays, each loaded point a, e, l,
receives about one-third of the weight on the rafter, the weight
carried at / is less than that of a full bay, the load being uniform ;
but in practice the difference is quite immaterial.
To find the strains, set off a b by scale equal to the weight at that
part as at a, draw b c parallel to the rafter, and c d to the tie meet-
ing a b in d, then the measure of a c by the scale gives the strain on
the strut, and c b the compression on the rafter from the point m
to a, and c d gives the tension on the tie from the point m to f.
The strut a ƒ impresses on ƒ e a tension measured by a d, which,
together with one-third of the weight on the rafter, is impressed on
the point e. Draw down e ƒ by scale equal to this pressure; draw
ƒg parallel to the rafter, and g h parallel to the tie, then the mea-
sure of ƒ g gives a second strain of the rafter from m to e, to be added
976
MODERN STEAM PRACTICE.
to the previous strain from m to a, and the measure of h g a second
strain on the tie from m to k, and the measure of eg the strain on the
strut ek. The strut ek then impresses a tension on kl which is
measured by eh, and which, together with the remaining third por-
A

น
t
Fig. 674.
B
m
a
h
f
k
Fig. 675.
C
S
t


t
K
Fig. 676.
D
9
S
t
9
T
19
t
9
Τ
S
S

Fig. 677.
Figs 674-677.-Iron Roofs. All the dark lines in compression and the light lines in tension.
A, Spans from 20 feet to 30 feet.
B,
C,
""
30
40
40 ""
50
D,
""
50
το
""
k, King rod. 19, Queen rods. rr, Rafters.
ss, Siruts. tt, Tie rods.
tion of the weight on the rafter, is impressed on the point . Draw
down li by scale equal to this pressure; draw ij parallel to the tie,
then the measure of i j'and jl gives the respective strains on the
tie and rafter throughout.
ENGINEERING WORKS, ETC.
977
The strains may be measured off with the scale as follows:-
Thrust on the rafter.
Between / and e lj
""
Strain on tie rod.
Between k and ƒ = ij+gh
e and a =a=lj+gf
a and m=1g+gf+cb
Thrust on struts.
Between e and keg
a and f=dc
""
""
fand m=ij+gh + c d
Strains on king and queen rods.
King 2 eh
Queen = a d
In plain iron roof trusses of the preceding description the inclina
tion of the rafters is I in 24, and that of the tie rods I in 15.
In truss A, Fig. 678, the tie rod and rafter are secured by a cast
iron shoe, a wrought-iron jib and key passing through the shoe, and
the rafter is secured to the shoe by a bolt and nut (Fig. 680).
The other ends of the tie rods are formed with eyes, and are fitted
between two disc plates, and secured by bolts and nuts; the same
bolts take the struts, the ribs being cut off at that part, and the ends
of the top flange bent with a hole punched, as shown in Fig. 681.
The king post likewise passes through holes in those disc plates,
and is secured at the top and bottom with a nut. There are also
two holes at right angles to those for the tie rods, for securing
longitudinal tie rods between each principal when so fitted.
At the point where the struts meet the tie rod (Fig. 682) the latter
is forged with an eye, through which the queen rod passes, as like-
wise through the bent end of the strut resting on the top of the tie
rods, and is secured with two nuts as shown.
At the upper end the strut is bevelled to suit the under edge of
the rafter (Fig. 683), and rivetted to two strips of wrought iron, one
on each side of it. The end of the queen rod is forged with a jaw,
with bolt and nut, for securing it and the strut to the rafter.
The heads of the rafters and the king rod are fixed in a cast-iron
king head (Fig. 684), the king rod being secured by a cotter passing
through the king head; on the king head two lugs are cast on each
side for securing the rafters thereto, with a bolt and nut for each.
On the top of the king head two flanges are cast for securing the
ridge bar with bolts and nuts; on the top of the ridge bar a wooden
ridge is fixed, with lead or sheet-iron capping.
In truss B, Fig. 679, the tie bar and king and queen bars are formed
of flat wrought iron, the king and queen bars having palms forged on
for taking the tie rod and rafters, to which they are securely rivetted;
there is a shoe fitted resting on the top of the brickwork. This frame-
work is much simpler than the previous example, and is generally
used up to spans of about 60 feet.
62
846.
MODERN STEAM PRACTICE.

B
A
Figs. 678, 679.—Iron Roofs.
A
Rafters T iron.
Struts
>>
King bar round iron.
Queen,,
Tie rod
""
..
B
Rafters T iron
Struts
King bar flat iron.
Queen,,
Tie rod
>>
Fig. 678.
Fig. 679.
ENGINEERING WORKS, ETC.
979.
D
C
B
C
E
D
E
со
B
A
Fig. 683.-Queen Rod.
A, Queen rod. B, Strut. Cc, Plates. D, Rafter. EE, Laths.
A
C
B
A
A
E
A
C
B
Fig 680.-Shoe.
A, Shoe. B, Tie rod. c, Rafters.
D
Fig. 684.-Head of Rafter. -A, King head.
B, King rod. cc, Rafters. D, Ridge bar.
Fig. 682.-Tie Rod.
A, Tie rod. B, Queen rod. c, Strut.
Fig. 681. Tie Rods.
A A, Tie rods.
B
B B, Longitudinal ties.
E
A


cc, Disc plates.
D, King rod.
EE, Struts.





980
MODERN STEAM PRACTICE.
Iron roofs may be covered with slates, tiles, zinc, galvanized iron,
&c. The most durable coverings are those of slates or tiles.
"Duchess" slates are generally employed with wrought-iron laths of
angle iron, the slates being secured by copper bands to the angle iron.
When tiles are used they are held in position on the laths by small
projections moulded on their under surfaces, and as they overlap
each other their own weight tends to keep them down; they are
much heavier than slates, but are preferred in some instances. In
respect of ventilation they are suitable for many manufactories, the
numerous interstices between them affording means for the egress
of heat and vapour; and they are less liable to be broken by heat,
such as in roofing over furnaces. Slate and tile roofs require a
slope of from 25° to 30° as the minimum in order to prevent the rain
from being driven under them by the force of the wind. Galvanized
iron forms a very light covering, while its rigidity when corrugated
imparts great stiffness to the framing when properly secured thereto;
galvanized iron which is coated with zinc, or zinc itself, should never
be used in situations much exposed to air impregnated with the gases
arising from the combustion of coal, such as over the retort house
of a gaswork, as decomposition of the zinc sets in very rapidly.
Plain sheet iron well painted is sometimes used, and should be laid
on boarding, with which the entire roof is in the first place covered.
Cast-iron galvanized plates have been used with advantage; the
plates are made sufficiently wide to span the distance between the
principals, upon the rafters of which they are secured either by bolts
with nuts beneath or by screws, drilled and tapped into the rafter;
the principals are about 2 feet 6 inches apart, and the plates of
widths to correspond; the vertical joints being covered with cast-
iron rolls, cast separately, and secured by galvanized screws. This
form of covering gets very hot under the influence of the sun, and
where coolness in the upper story of an edifice is a desideratum the
rafters should be covered with 1½-inch boarding, with corrugated
or galvanized sheet iron secured over it.
When a number of steam boilers require to be roofed over it is
an object to keep the space above the boilers quite clear, the roof
being supported without the aid of columns resting on the brickwork
encircling the boilers; this is needed in the event of the boilers
requiring to be renewed.
At the Abbey Mills pumping station for the main drainage of
the English metropolis, there are eight boilers arranged in a line
ENGINEERING WORKS, ETC.
981
on each side of the vestibule or side entrance to the engine house.
Each roof is of small span, forming together ridges and furrows, and
the rafters are supported transversely by means of lattice girders
running across the building and resting on the side walls, thus
keeping the space above the boilers quite clear. The roof over the
entrance to the engine house requires no support but the side walls,
the form of the building being square in the plan.
In another form of roof for the boiler house at the pumping
station at the southern outfall for the main drainage system of the
metropolis the boilers are arranged on each side of the doorway
underneath the floor, where the firemen attend to the furnaces, the
coal being run on a railway for the purpose. The boiler and stok-
ing rooms are covered over with three-trussed roofs, and supported
from the end walls and from columns and girders placed in front of
the boilers. In such an arrangement the columns for supporting
the roof are not so objectionable, as there is ample room to get out
the boilers in the event of their requiring to be renewed.
To compute the strain on an arched truss by a figure of construction.
-This example (Fig. 685) of a trussed arched roof has, we will say, a

K
H
B
Dr
C
q
m
F
S
Fig. 685.
of 50 feet, with a depth of truss of 7 feet. The whole of the bow,
or one half, as represented from A to D, is in compression, and the tie
rod A E F in tension; BE and C F are struts, and CE and DF ties.
We will suppose that the whole roof is uniformly loaded with
2 tons, or I ton on the half principal as delineated, which will be
divided as follows:-There will be one third situated at each of the
points B and C=0'33 ton, and one sixth at A and D=0·166 ton.
It will, however, be apparent that the weight of o.166 ton at A
is supported directly by the vertical reaction of the abutment, and
982
MODERN STEAM PRACTICE.
consequently produces no strain whatever on any part of the truss.
Its action may be therefore ignored, and the total weight on the
principal producing strain on its various parts will be equal to 0.825
ton instead of I ton. This theoretical assumption will not hold
unless the distance A B, or unsupported length of the rafter between
the abutment and the strut B E, be sufficiently limited so as not to
allow of any bending taking place.
The relative positions of the load being settled, we come to con-
sider the strain on the various parts. At the point of support A, the
vertical reaction producing strain upon the roof is the sum of the
weight at B, C, and D, since they must all be ultimately transferred
to that point. This reaction is therefore equal to 0·825 ton. We
have therefore three forces at the point A, namely, the vertical
reaction of 0.825 ton, the strain along A B, and the strain in A E,
tending to equilibrium at the point A.
On a scale of 1 ton to the inch, make A H equal to 0.825 ton;
join A B, and produce the line to any convenient length. From the
point H, draw HK, parallel to A E, meeting AB produced to K;
measuring by the same scale, A K will give the strain upon A B and
HK that upon AE respectively=190 and 157 ton. To find the
strain upon the point B in B C, we must find the resultant of the
strain upon A B, and the weight at B. Upon A B produced, lay off
Ba=AK or 1'90 ton, the strain already found for A B; draw a b ver-
tically equal to the weight at B equal to 0.33 ton; join Bẻ, which is
the resultant required. From the point b, draw bd parallel to B E,
and meeting BC produced in d, then Bd will give the strain upon
B C, and b d that upon the strut BE. There now remains only the cen-
tral part CD of the upper flange upon which to ascertain the strain.
This, allowing for the change in direction, will evidently be less than
that upon BC by the action of the weight at C plus the pull upon
the queen rod CE, therefore before the strain upon CD can be deter-
mined that upon CE must first be obtained. This obviously pro-
ceeds from the pull at the point E, for since CE is a tie it cannot be
affected by the weight at the apex C, which is supported directly
by the arch and the strut CF. At the point E there are two forces
acting, a compression along BE and a tension along A E, and the
resultant of these will pull upon both CE and E F. The amount of
these pulls or tensile strains may thus be ascertained. Produce A E
to any convenient length; make E h equal to the strain upon A E or
H K; from h, draw hm, parallel to B E, and equal to bd, the strain on
ENGINEERING WORKS, ETC.
983
BE. The resultant of the strains in A E and BE will be represented
by Em. From m draw m n parallel to E F, and m n will be the strain
upon EF, and E n the pull upon the queen rod CE. The compres-
sion upon CD can now be calculated: produce B C, and upon it lay
off Cp Bd; from p draw pq equal to the weight o'33 at C plus the
pull En; from q draw qr parallel to CF, meeting CD produced in r,
and the strain upon CD is measured by Cr, and that upon CF by q r.
The question of what becomes of the weight D at the central apex
will now be considered. As DF is a tie, the whole of the weight D
is conveyed in equal subdivisions to each of the two abutments, and
it has already been accounted for, since it was included in the value
of AH, which was made equal to the vertical reaction at A. There
is yet one more strain to be determined, and that is the pull on the
king rod, DF. This rod can only be affected by the strain on the
strut CF, since it is at right angles to the tie EF. But the corre-
sponding strut upon the other half of the girder will bring a similar
strain upon D F, so that by producing C F, making F S equal to twice
qr, and drawing St parallel to E F, the total strain upon DF will
equal Ft. The strain upon DF is in fact the vertical resultant of
the strains in CF and the corresponding strut upon the other half of
the roof.
For a variety of purposes, such as the roofs over railway stations,
the arch form of truss has been adopted with advantage. This form
presents a fine interior and requires less height of supporting walls.

Fig. 686.-Arched Roof. Truss designed for tropical climes.
For moderate spans ties or trussing may be entirely dispensed with;
but it is desirable for very large spans to introduce internal bracing,
more especially in exposed situations subjected to hurricanes. The
ribs of these roofs are of the latticed-girder principle, varying in
depth according to the span, and are covered over with corrugated
iron.
It is desirable in roofs designed for tropical climes to have an
inner lining of corrugated iron of a thinner description than that of
L
984
MODERN STEAM PRACTICE.
the outside, to form an air space so as to admit of a current of air
passing between the two coverings, keeping the inside of the build-
ing comparatively cool.

Fig. 687.--Arched Roof. Truss designed for
Truss designed for spans of 200 feet.
The next example of an arch truss, of 187 feet clear span, the
outside radius of the main rib being 108 feet 4 inches, is for the roof
of the city terminus of the South-Eastern Railway in Cannon Street,
London (Figs. 688-693). The depth of the truss at the centre is about
one-seventh of the span of the total arch. The main rib is of the
plate form I foot 10 inches deep and 3% inch thick, and the breadth
of the top and bottom flanges I foot 2 inches, secured at each corner
with angle iron as shown in detail on p. 986. The purlins are similar
in construction, having a depth of I foot 8 inches and 3% inch thick,
and a breadth of top and bottom flanges 10% inches wide, secured
to the principals as shown. The struts are formed of flat bar iron
with T irons, bolted together and kept apart with cast-iron distance
pieces, and are secured at the top to a T piece rivetted to the main
rib, and at the bottom to a plate, which takes likewise the diagonals
and tie rods. The struts and diagonals, which are formed of bar iron
secured by two plates rivetted to the T piece at the top and plate
at the bottom, are secured at each end with rivets, while the struts
are secured at each end with bolts and nuts as shown in detail.
The St. Pancras Station roof of the Midland Railway in London
is certainly a bold and novel form of arch truss, springing as it were
from the ground, covering an area of 690 feet in length by 240 feet of
a clear span (Fig. 694). The side walls offer no support to this roof,
being merely screens, to give it the appearance of an ordinary station-
house. The curve of the main ribs internally is of two radii, of
ENGINEERING WORKS, ETC.
985

B
AG
B
I
A
Figs. 688–690.—Roof of City Terminus Station, South-Eastern Railway, London. Span, 187 feet in the clear.
A, Section of the main rib. B, Purlins, showing method of fastening ditto.
986
MODERN STEAM PRACTICE.
57 feet at the springing; and two of 160 feet meeting at an angle at
the centre, 100 feet in height above the level of the rails.
The lattice ribs are 6 feet deep, formed with open box flanges
10½ inches deep, the flanges being braced together by diagonal


A
D
D
B
D
•
OF
C
A
B


ക

Figs. 691-693.-Detail of Rib and Trussing for City Terminus Station Roof.
A, Main rib. B, Strut. c, Tie bar. DD, Diagonals.
channel iron, and radial struts forming the end of the purlins. At
the bottom parts to a height of about 25 feet the truss is constructed
of plates and angle irons rivetted together. The main ribs are
29 feet 4 inches from centre to centre, and have three intermediate
ENGINEERING WORKS, ETC.
987
ribs between them at equal distances apart, braced with diagonal
bents 10½ inches deep, and consist of angle iron carried at every
18 feet 6 inches by trussed purlins between the ribs; they are con-

57fc
·160 ft....
240 fb.
Fig. 694.-St. Pancras Station Roof of Midland Railway, London.
structed so as to stiffen the main ribs laterally. The bracing is so
arranged to carry the proper portion of the three intermediate ribs,
and to keep the main ribs in their proper position.
The main ribs are tied underneath the platform by wrought-iron
girders to counteract the outward thrust which all arched roofs are
subjected to. These iron girders not only serve this purpose, but like-
wise support the platform, and can be made to cover a certain number
of spans, the space thus obtained being utilized as storage vaults.
The load on a roof is of a double character, and consists of the
permanent load and the accidental load. The former takes in the
weight of the material used in its construction, and the latter that
of snow and the pressure of the wind; for the former from 6 to 20 lbs.
a square foot is allowed, and the wind pressure may be put down at
30 lbs. per square foot. In England 35 lbs. for wind and 5 lbs. for
snow, or a total of 40 lbs. per square foot, is allowed, the greatest
roofs being generally constructed for a uniformly-distributed vertical
accidental load of this amount. The weight of the structure must
of course be added in calculating the strength of the various parts.
A uniformly-distributed vertical load is not the worst casualty a
roof may be subjected to, as the great force of the wind acts on the
broadside. In some instances ribs have been tested with 40 lbs.
per square foot hung on one half of the roof, the other half being
unloaded, thus imitating approximately with a vertical load the
stress the roof would be subjected to with the wind acting on the
broadside; but it must be borne in mind that the force of the wind
988
MODERN STEAM PRACTICE.
is more felt on a roof having a great inclination than one of a flatter
construction.
The height of the floor of the store rooms to the under side of the
girders is 13 feet 6 inches, from the level of the floor to the bottom
of the columns I foot 6 inches, and the height of the columns
15 feet. The wrought-iron floor girders are I foot 9 inches deep
and inch thick, with a width of flange I foot 2 inches by inch
thick, the angle irons being 3½ inches by 3½ inches by 5% inch
thick. The cross girders are 1 foot 9 inches deep and inch thick,
the angle iron being 3½ inches by 3 inches by ½ inch thick.
16
16
9
16
Wind screens are fixed at each end of the station, composed of a
framework of iron of the lattice-girder description, of a width of
6 feet 8 inches placed horizontally, the main vertical of the framing
being of similar construction. The intermediate vertical members
are of H iron 9 inches deep, and two are placed between each of the
main verticals. The whole is filled in with wood-framing sash bars,
glazed with inch sheet glass, and which is calculated to withstand
a pressure of 40 lbs. per square foot, which is considered ample for
ordinary requirements.
3
16
The weight of iron in the whole structure is over 9000 tons, the
proportions of part of which are as follows:-
The main and cross girders of floor comprise about
The main ribs and spandrils about
...
The cast-iron columns and caps supporting the floor, about
Buckle plates,
...
...
Intermediate ribs, purlins, and connections,
...
20
per cent.
13
""
...
122
9
6
There are also about 120 tons of T iron to buckle plates of flooring,
and also 300 tons of cast iron in the roof, besides the two end screens,
and 13,248 feet of galvanized iron, No. 8 B. W. G.=1.86 lb. per
square foot.
The travelling staging, for the purpose of fixing the roof in its
position, was divided into three parts, the side ones consisting of
five and the centre of six divisions each, and from the back to the
front there were four divisions. The first staging travelled on 123
wheels 2 feet 8 inches in diameter, running on a beam of timber
I foot 6 inches by I foot 6 inches. The horizontal transverse pieces
were I foot by 6 inches, except the bottom pieces, which were I foot
by I foot, upon which rested large cast-iron shoes or sockets to
receive the feet of the standards, which were I foot by I foot. Two
side stages were used in the fitting up of the roof. Each main rib
ENGINEERING WORKS, ETC.
989
was supported by the staging until the wind ties were finally fixed.
More than 50,000 cubic feet of timber were employed in these
travelling stages.
The roof at the Great Northern Railway Station, London, is
an example of the plain-rib description; it is formed in two spans
of 105 feet 3 inches in the clear.
The wrought-iron principals or main ribs are spaced 20 feet apart,
and are accurately curved to a radius of 52 feet at the bottom edge
and fit exactly between the cast-iron shoes built in the walls. The
depth of the rib is 2 feet, the web being 4 inch thick, and the top
and bottom flanges are 9 inches wide, with angle iron at each corner
334 inches by 334 inches by 3% inch thick.
The intermediate ribs or rafters are of rolled iron 8 inches deep,
with top and bottom flanges 5 inches wide and ½ inch thick; the
lower ends are fitted with cast-iron corbel shoes on stone templets
built into the station wall, and the upper ends rest upon T-iron
supports 5 inches by 2 inches by 3% inch thick, and have wrought-
iron brackets rivetted on each side, which are also rivetted to the
purlin stiffeners. The first and sixth lattice purlins from the spring-
ing on each side are I foot 6 inches deep, and formed of T-iron
flanges 5 inches by 4 inches by ½ inch thick, with flat bracing
2½ inches by 4 inch thick, and T-iron stiffeners 5 inches by 2 inches
by 3% inch. They are rivetted at each end through the main ribs.
to each other, so as to be continuous from end to end. These
purlins being of less depth than the main ribs, the difference is made
up by T-iron supports 5 inches by 2 inches by 3% inch thick,
rivetted to the web of the principal rib.
The second, third, fourth, and fifth purlins on each side of the
rib are formed of T-iron bars 5 inches by 4 inches by ½ inch thick,
with 1%-inch tension bars and 14-inch struts; the ends of these
purlins are fixed to angle-iron jaws rivetted to the main ribs, and
to which also the ends of the tension bars are bolted. In the last
bay at the north end the purlins are of a stronger section and com-
posed of T iron for the flanges 5 inches by 4 inches by ½ inch thick,
and T-iron bracing bars 5 inches by 2 inches by 3% inch thick, to
sustain the lateral thrust of the roof; and the intermediate rafter is
carried over from wall to wall.
An angle-iron bar 6 inches by 3 inches by 3% inch thick is rivetted
to the top of the first purlin on each side, and a ventilating opening
is formed above it by means of flat bars bent to a curved shape, and
990
MODERN STEAM PRACTICE.
carrying an angle bar 2½ inches by 2½ inches by 3% inch thick, to
which the glazing bars are rivetted, the latter being inverted T irons
3 inches by 134 inch by 3% inch thick.
A double angle iron or z bar 4 inches by 2 inches by 3% inch
thick is rivetted on the top of the second, third, fourth, and fifth
purlins on each side, and to the main ribs where they occur, to
which the glazing bars are rivetted; these angle-iron bars are fixed in
their places so as to give a perfect bed for carrying the glazing bars.
An angle-iron bar 6 inches by 3 inches by 3% inch thick is rivetted
along the top of the sixth purlin on each side, and to the main ribs
where they occur, to which T-iron arched bearers 4 inches by 3 inches
by ½ inch thick are rivetted, to carry the raised portion of the roof
for ventilation. On the arched bearers longitudinal angle irons
4 inches by 2 inches by 3% inch thick are rivetted for carrying the
glazing bars; at the centre these angle irons are 9 inches apart, and
the open spaces are covered with a wrought-iron capping, No. 12
B.W.G., secured by brackets 14 inch by 4 inch thick, and spaced
every 3 feet 3 inches apart.
The whole of the wrought iron employed in the construction of
this station roof was specified to be capable of bearing a tensile
strain of at least 20 tons to the square inch. All the plates in the
flanges were planed truly square at each edge, and those in the webs
of the ribs were planed at their butting joints; the junctions of bars
and angle iron and T irons are fitted to butt truly together. The
rivet holes throughout are specified to be punched inch smaller
than required, and rimered out to the proper size when fitted in place,
no drifting or straining of the iron being allowed under any circum-
stances. The bolts, nuts, and rivets were specified to be of iron cap-
able of bearing a tensile strain of at least 24 tons to the square inch.
The bending of angle and T irons and the rivetting to be done hot.
1
6
The whole of the timber is of the best red Riga fir, thoroughly
seasoned, and free from large or dead knots, sap, strakes, or other
imperfections.
The fir packing with stop-chamfered edges is fixed by 3-inch
by ½-inch coach screws to the main and intermediate ribs; it is
carefully bent to the curved portion of the ribs and bedded down
on thick white lead; that on the top of the main rib being composed
of No. 2 wrought and stop chamfered packings 6 inches by 3 inches,
and that on the intermediate rib being 9 inches by 3 inches, also
wrought and stop chamfered.
ENGINEERING WORKS, ETC.
991
The whole of the roof in its length, and to the height of the first
purlin on each side, is covered with 1½-inch wrought, one side
grooved, tongued, and chamfered red Riga boarding, securely nailed
down to the packings, and a wrought one-sided facia II inches by
1½ inch, with chamfered edges, and scribed between the main and
intermediate ribs, is fixed against the brickwork at the bottom of
the boarding along each side on the inside of the roof.
The last bay on the north side is covered with No. 16 gauge zinc
of Italian pattern on 1½-inch boarding, and all proper fitments,
flashings, &c., necessary to make this portion of the work perfectly
water tight. The gutter on each side for the whole length of the
roof is laid with 7-lb. lead, turned up 6 inches on properly framed
and blocked 1½-inch gutter board and bearers; with cess pits, pipes,
&c., having 5-lb. lead flashings let into walls and secured with
proper wall hooks, and pointed with Portland cement.
The whole of the internal woodwork of the roof is knotted, primed,
and stopped, and has three coats of the best oil colours; the external
woodwork is knotted, primed, and stopped, and both wood and iron
has four coats of the best oil colours.
The whole of the iron work in the roof was properly freed from
rust, and had one coat of gray colour before leaving the con-
tractor's yard, and after completion had two other coats of the best
oil colours. Mineral colours without any admixture of lead or zinc
were alone used, on account of the sulphurous fumes from the loco-
motive engines.
The following is a detailed list of ironwork in one bay of 20 feet,
that being the distance of the principals from centre to centre:—
Lattice purlins,
Trussed do.
Ventilators at bottom of glass,
8 Z bars 20 ft. long,
No.
tons. cwts. qrs. lbs.
Weight of rib when put together, exclusive of cast iron,...
7 II I 9
48
28 2436
I
8 0
...
4
I
...
...
9 3
20
O
6
I
26
0 12
...
о
...
...
...
I
O 4
O IO
4 O 12
0 2 2
O O
34
O
24
26
16
5
14
8
60
120
48 4
Angle irons, 6 in. x 3 in., for ventilators,
Do. 4 in. x 2 in., do.
T-iron arches for lantern,
T-iron brackets for do.
...
...
30 ft. super ridge cover, at 4 lbs. per foot,
T-iron glazing bars, 8 ft. 6 in. long,
Do.
do. 8 ft. 3 in. long,
...
I
2
...
...
Intermediate rafters, H iron, each 20 ft. 10 in. long,
Wrought-iron angle-iron brackets, under ends of purlins,
Lugs, top of intermediate rafters,
::
...
60 8
I 0 2 12
о O I 24
O O
O O
16
992
MODERN STEAM PRACTICE.
No.
tons. cwts. qrs. lbs.
4
Castings at foot of rib,
...
4
Bolts and nut for do.
4
...
Cast-iron shoes for intermediate rafters,
...
: :
::
o 8 I
4
O
0 0 6
O
I I 4
...
17
Total weight,
...
...
...
3 2 14
Our next example of roof, that over the Joint Railway Passenger
Station, New Street, Birmingham, is in one span. The ground
being irregular on plan, the span varies from 211 feet at one end to
191 feet at the other end, the total length being 864 feet. The
roof is supported on one side upon brick pilasters projecting from
the wall of the office buildings, and on the other side upon hollow
cast-iron columns 2 feet in diameter, weighing 5½ tons each, the
columns being connected together by cast-iron arched girders.
The principals are spaced 24 feet apart from each other; the
height of the springing is 33 feet above the level of the rails; the
rise of the tie rod, which forms a curve, is 17 feet in the centre of the
largest principal, and the depth of the curved principal is 23 feet,
making the rise of the main rib 40 feet, and the total height is
84 feet to the top of the louvre in the centre of the roof.
The main rib of each principal consists of a vertical plate of
wrought iron 15 inches deep and 1 inch thick, with two angle irons
6 inches by 3 inches rivetted upon each edge, forming a flange at
the top and bottom 12 inches wide; the junction of the angle
irons are made to break bond with each other, and junction plates
are rivetted on each side of the vertical rib at the joinings.
The tie rod is 4 inches in diameter, enlarged at the ends where
screwed to maintain the full sectional area at the bottom of the
thread, and the several portions of the tie rod are joined at the foot
of each strut by a wrought-iron coupling box with a right and left
hand screw.
There are in each principal twelve vertical struts, each constructed
of four angle irons set diagonally in the four angles of a square, and
separated by a series of small cast-iron crosses secured by bolts
passing through the hollow arms of the cross; these struts are
enlarged in the middle to give the requisite strength by proportion-
ing the length of the crosses to give a curved outline. Each end of
the strut is secured to a cast-iron shoe, the upper one being bolted
to the bottom flange of the main rib, and the lower one clips the
coupling box of the tie rod. The diagonals in the principals are of
flat wrought iron from 3 to 5 inches wide and 5% inch thick; they
ENGINEERING WORKS, ETC.
993
are rivetted together where they cross, and attached at each end by
bolts to the lugs upon the cast-iron shoes.
The foot of each principal, on the wall side, has a cast-iron bed
plate, rivetted on the under side, which is recessed into a stone built
into the top of the pilaster. The foot of the principal at the column
has a flat wrought-iron bed plate, resting upon four wrought-iron
rollers, 2 inches in diameter and 19 inches long, which work upon
a corresponding cast-iron plate fixed on the top of the column, to
allow for the expansion and contraction of the principal from varia-
tions of temperature.
The purlins are fixed at 10-feet intervals, and consist each of a
wood batten 6 inches square, trussed with a 34-inch rod. The cast-
iron shoe at each end clips the back of the principal, and is bolted
to it, serving as an abutment for the two adjoining purlins.
A large louvre for ventilation, 5 feet in height at the sides, is fixed
along the whole length of the ridge. Diagonal wind ties, 14 inch
diameter, extend over the whole roof, starting from the foot of every
alternate principal, and bolted to the main ribs at each intersection.
One half of the roof is glazed, and also the louvre in the centre;
the remaining portion is covered with galvanized corrugated iron,
No. 16 gauge, nailed down upon the wood purlins.
3
The glass is rough rolled fluted plate inch thick, weighing
44 ounces per foot, each plate being 6 feet long by I foot 4 inches
wide. The total area of glass is 94,000 square feet, weighing about
115 tons; the whole area of the roof is 175,000 square feet, or rather
more than 4 acres. The total weight of the ironwork is about
1050 tons.
Another example of a large iron roof is that recently constructed
for St. Enoch Railway Station, Glasgow. This roof is of the arch
type, the ends of the ribs, unlike those at St. Pancras Station
(which are tied across at bottom) are fixed at the springing by
heavy bolts and cast-iron anchor beams built into the brickwork.
The form of the arch is elliptic, with a clear span of 198 feet, and
a height of 83 feet from the rails to the soffit. At the springing
of the arch the radius is 40 feet, at the haunch 125 feet, and at the
soffit 90 feet.
There are 15 principals or main ribs, 36 feet 10 inches centre to
centre, except the eastmost two, which are only 18 feet 5 inches
apart, and carry the eastern screen. The western screen comes
down to within 35 feet of the platform, and finishes with a lean-to
63
994
MODERN STEAM PRACTICE.
roof against the booking-hall wall. The length of the roof is
525 feet, and the width from wall to wall is 204 feet 6 inches, so
that it covers an area of 11,929 square yards. The main ribs are
attached to shoes, each of which is fixed in position by four bolts
24 inches diameter, the double-tapered heads of which rest on the
cast-iron anchor beams. There is therefore no provision for expan-
sion by change of temperature.
The main ribs are 5 feet deep over the channel irons, the top
and bottom flanges being alike, and each consisting of one plate
16 inches by ½ inch, and two channel irons 94 by 3½ by ½ inch.
There are seventeen rows of purlins, 14 feet centre to centre. They
consist of light girders with angle-iron flanges and T-iron web
bracing. The intermediate ribs are of the ordinary rolled joist
section, 10 by 5 inches, weighing 35 lbs. per foot. They are placed
on the top of the purlins, and are about 7 feet 4½ inches centre to
centre.
16
A length of 112 feet on the crown of the roof is glazed with
3 -inch rolled plate glass on the well-known Paxton system. There
are gangways at each side, and by means of footboards laid over
the valley gutters from gangway to gangway it is easy to reach any
pane in the whole roof. Below the gangways the roof is covered
with 134-inch boarding, grooved and tongued, and large Welsh slates.
The weight of wrought ironwork per bay is 87 tons 16 cwt. Of
this there are 6 tons 10 cwt. in two shoes: 36 tons 12 cwts. in one
main rib.¹
TABLE OF THE SCANTLING OF IRON ROOFS.
2
The following table gives an approximate scheme of scantling
for rafters and struts of T iron, for plain and inclined spans from
20 to 50 feet, and with double rafters for spans from 51 to 60 feet
of the section as shown, as also the diameter of the tie rods and king
and queen bolts. The strength of the various parts is calculated
for principals placed 6 feet apart, and covered with any
of the ordinary materials. If the principals are more
][
Fig. 695.
1 For the above details of the St. Enoch Station roof we are indebted
to a paper by the resident engineer of the works, C. P. Hogg, Esq., read
at a meeting of the Institute of Engineers and Shipbuilders in Scotland,
April, 1882.
2 Two bars, as in Fig. 695, are placed 1½ to 2 inches apart, and are secured by means
of cast-iron struts or stretchers fixed between the bars by bolts passing through them.
·
ENGINEERING WORKS, ETC.
995
than 7 feet apart, a little in excess should be allowed in the dimen-
sions of the rafters, &c.

Span.
Rise in Centre of Rafter.
Rise of Tie Rod.
Distance apart of King and
Queen Bolts.
Number of pairs of Queen Bolts.
Number of pairs of Struts.
Width of Top Flange.
Thickness of Top Flange.
Total Depth.
Thickness of Rib.
Width of Top Flange.
Thickness of Top Flange.
Total Depth.
Thickness of Rib.
Tie Rod.
King Bolt.
Queen Bolt.
Queen Bolt, 2d pair.
Queen Bolt, 3d pair.
DIMENSIONS OF DIMENSIONS OF
RAFTERS.
STRUTS.
DIAMETERS OF
27 5 5
28 5 74
29 5934
ft.
ft. in.
in.
ft.
20 4 O
40
6
5 O
21
4 2½ 645 3
22
4 5
65%
23 4 74 7
244 934
934 74
25 5 0 7½ 6
26 5 2½
734 6 6
8 69
83% 7
₤omo aom
in.
II
2/243
in. in. in. in. in. in. in. in.
2 4 22 38 14 4 12 4
244 2343% 12 413 4
3/8 1344 2
in. in. in. in. in.
3/4 5/8 1/2
7/8 3/4 16
9
1/4
I
7/8 5/%
2/2
3
3/8 134/42
15
I
ΙΙ
163
5
163
3/8 2
1/4 2
16
118 11
3/8 2
42
16
8347 3
2/23/8 3
2 1/4 24
5
1% 7/8 3/4
16
о
3/41/42
5
16
5
16
30 60 9
31 62% 94
32 5 95%
33 6 74 10
34 6 934 104
35 7 0
102
36 7 221034
37 7 5
2
5555 10 10
ON +0∞00N +0∞
11% 6
2
38 7 7411½
39 7 934 1134
40 80
12
12
2/23/8 3 3/8 134
21/2
16 134
3/41/42
Tठ
5/8 3/8 16 134 3/4 1/4 21/4 3/%
5/8 3/8 3/4 2 1424 3/8
23/4 3/8 3/4 218 4 2/2 3/8
23/4 3/8 3/4 214 1/4 1/4 22 3/8
3/8 32 1/2
3/2/22/4 1/4 1/4 23/4 3/8
3/8 3/2 1/2
3½ ½ 24 16 234 3/8
3342 23% 1234 3/8
341 342 23%
3
3
3
34 16 4
1½
3/4 6 4
43 874 12345
4/2
45 9 0 13/2 5 7/2
23
41 8 22 1245
42 8 5 1225 3
44 893413% 5 6
46 9 2½ 134 5 9
47 9 5 14 5 102
48 9 74 144 O
49 9 934145% 6 1½
50 10 0 15 6 3
51 10 221546 4½
52 10 5 15% 6 6
53 10 74 16
6 72
54 10 934 1646 9
55 II O 162 6 10/2
56 11 22 1634 7
57 11 5 17 7 1/2
58 11 741747 3
59 11 934 1734 7
60 12 0 18 7
4/2
23
7
3416 4
3/4 TB 4
7
5
5
16 234
5
1/2 3/2 163
-1% % %%
I
14 345%
7
16
1/2 244 234
1/22/4 2343/8
1/2 2/4
244 234
1/2 238 234
16
5
3½ 16 44 1/2 238 16 3
7
3/2 18 44
9
18
T6 23%
5
3
5
16 3
9
3½ 16 42 TT 238
5
ਨ | 3
5
33/4 7/4/2 16 238
334 16 434 ₩ 238 1 3
334 0 434 56 238
334 16 434 % 2%
7
Double Rafters.
11/83/84
1/8 16 4
7
13%1% % 45%
I
16
12117834
5
3
7
3% 3
18
7
16
1/42/23/83
22 3/8 3
5
18
5
1/8 1/6 4/4 2/2 3/8 3/4
1/4 1/2 4/4 16 22 34
1/4/24/2
5
T234
2343/8 3/4
1/2
9
4 16 42 38 234 3/8 34 18
14 16 434 38 2343/8 3½
9
-15% 141 784
I I 3/4
3½ 16
9
16
134 13% 1% 1 %
13% 5% 4 3/8 234 3/2
13% 5% 5
138
16
To 234 0 32 56
16 3½
23/4 16 3½ 1
| 16
7
16234
7
11
996
MODERN STEAM PRACTICE.
TABLE OF THE Size and WEIGHT OF IRON LATHS.

QUEENS.
27 inches wide.
Laths 12 inches apart.
Distance Width of | Thick-
each side
PRINCESSES AND DUCHESS.
24 inches wide.
Laths 10½ inches apart.
Width of Thick-
ness
COUNTESS.
20 inches wide.
Laths 8½ inches apart.
Width of Thick-
each side
of lath.
Weight
of ditto.
ness
of lath
per foot.
Weight
Weight
apart of
ness
of lath
each side
Principals. of lath.
of ditto.
per foot.
of lath.
of ditto.
of lath
per foot.
455007
ft. in.
in.
lbs. ozs.
in.
lbs. ozs.
in.
lbs. ozs.
14
8 w.g.
I 8
1%
9 w.g.
I 4
1%
9 w.g.
I 4
о
138
7 0
1/2
6 w.g.
4 in.
I 12
114
8 w.g.
1 8
28
13/8
6 w.g.
I 12
14
8 w.g.
I 8
WEIGHT OF DIFFERENT KINDS OF COVERING.
Lead covering weighs about 7 cwts. per square of 100 superficial feet.
Zinc
""
Corrugated iron,
1½
34
""
""
Slates,
6 to 9
Tiles,
""
Boarding 14 in. thick,
about 12
4/2
་
STRAINS ON WROUGHT-IRON GIRDERS, ETC.
Wrought iron is now most extensively used for structures requir-
ing great strength and lightness, and the strains to which it can be
subjected is therefore a subject of the utmost importance as bear-
ing on the stability and safety of the structures.
For the purpose of illustration, we will take a wrought iron
beam having an I section. When it is supported at each end

Fig. 696.-Beam with Weight placed at Centre.
and a weight placed on the top flange, at the centre of the
beam, the beam first takes the weight, which is then transmitted
to the piers, each pier supporting one half of the weight of the
loaded beam; thus there is a vertical strain transmitted through
the beam. When the force is applied at the centres on the top
flange the strain or line of transmission can be delineated by
drawing a straight line from the point where the force is applied,
ENGINEERING WORKS, ETC.
997
running directly through the beam to the extreme end or point of
support at the bottom. When the weight is distributed equally

Fig. 697.-Beam with Weight Distributed.
along the top this line will assume a curved shape. Thus in either
case—when the beam is formed straight, as in the dotted lines on
Fig. 696, and the weight placed at the centre, or when it is curved,
as in Fig. 697, with the weight distributed-the strain will be
uniform throughout. In practice, however, girders are generally
made parallel. Other strains also come into action, namely, com-
pression on the top flange, tending to crush the material; and tension
on the bottom flange, tending to draw the material asunder. The
compressive and tensional strains are equal, and, considering the
beam as a lever, are found by multiplying the half weight by one
half of the length of the beam, dividing the result by the depth of
the beam: or by the following formula-Multiply the weight at
centre by the length of the beam between the supports, and divide
the result by the depth multiplied by the constant 4-
WxL
= strain at top and bottom flange at centre.
4D
Supposing a beam was 24 feet in length between the supports, the
depth 2 feet, and the weight 10 tons applied at centre—
5 × 12
2
IO X 24
4×2
=30 tons, strain by the first method;
=30 tons strain, by the second method.
It may be asked how this constant 4 is obtained? The answer is
simple, inasmuch as a beam supported at both ends and loaded at
the centre will carry four times the weight of a beam or lever sup-
ported at one end and loaded at the other; or otherwise, a beam
of double the length supported at both ends will carry the same
weight as a beam of one half of the length supported at one end
and loaded at the other. When the beam is parallel the strain
diminishes in a gradual manner towards the end, where it is nil; but
when the beam is formed so that it diminishes in a gradual manner
towards the end, forming a curve on the top flange diminishing from
998
MODERN STEAM PRACTICE.
the centre at top to a point at each bottom end resting on the sup-
ports or piers, the strain on the top flange would be uniform
throughout.
When the weight is not placed at the centre of the beam the dis-
tribution on each pier is as the distance of weight from pier; thus,
supposing the force applied to be placed three-eighths from the
0100

Fig. 698.-Beam with Weight placed out of the Centre.
end, the pier furthest from the weight (or arrow) will sustain a
downward pressure of three-eighths of the load, while the nearer
pier will support five-eighths of the load. Thus, supposing 8 tons
pressing in the direction of the arrow, placed three-eighths of the
length of beam from the pier, the beam being 24 feet in length,
three-eighths of 24 feet equals 9 feet: thus-
tons. feet.
8×9
24
3 tons, distributed on the furthest pier from the point where the force is applied.
Again, to find the pressure on the nearest pier, take five-eighths of
the total length of the beam or 15 feet, multiply by the force
applied or 8 tons, divide the result by the total length of the beam,
namely 24 feet, and the quotient gives the number of tons distri-
buted on the pier nearest the weight: thus-
feet. tons.
15×8
24
=5 tons, distributed on the nearest pier from weight.
The horizontal strains are found by multiplying that portion of the
weight transmitted to each pier by the distance of the weight from
that pier, dividing the product by the depth of the girder.
When a beam is loaded, and the weight distributed uniformly
along its length, each pier receives a downward pressure equal to
one half of the load, and a vertical strain is transmitted through the
beam, the same as when the load is placed at the centre, but instead
of the strain being in a straight line from the centres of force to the
ends of the beam at the piers, the line assumes a regular curve. The
vertical pressure commences at the centre of the beam between the
supports, and increases to the ends of the beam, where it is equal to
ENGINEERING WORKS, ETC.
999
one half of the load. To find the horizontal strains, multiply the
weight by the length of the beam, and divide the product by the
depth into the constant 8 (this constant is double than when the
load is placed at the centre, because a beam can carry double when
the weight is distributed; or, in other words, the strains will be
one-half less than when the load is placed at the centre of the beam).
Thus with the former length of bearn 24 feet, and the depth 2 feet,
and 10 tons of load distributed, we have-
10X24 =
8x2
15 tons, strain on the top and bottom flanges.
The strain as before diminishing towards the ends, where it dis-
appears; but this is not in as regular a manner as when the load is
placed at the centre of the beam.
The strain can be found by dividing the beam into ten equal
parts; at the centre the strain may be named I, at the next point
·36 -64 ·84 ·96 1

Fig. 699.-Beam showing the Strain on the Flanges.
towards the end '96, and so on to the last division, which we will
call 36; so when the actual strain at the centre is known, the strains
at each division can be obtained by multiplying the strain at the
centre by the corresponding decimals; consequently, a beam can be
plated at the top and bottom webs with flanges diminishing in
thickness from the centre towards the ends.
Or generally, w (c³ —
2
-bending moment, where w=load per unit
of span, c= ½ span, and x=distance from centre of span.
CANTILEVERS.
Cantilevers are beams of metal or wood supported at one end
and loaded at the other, or with the load distributed, the top flange
being in tension and the bottom flange being in compression.
When the weight is at the unsupported end the horizontal strain at
any point is equal to the weight multiplied by the distance in feet
from that end to the point where the strain is required, and divided
by the depth of the cantilever at that point (see Fig. 700), also in
feet.
1000
MODERN STEAM PRACTICE.
When the weight is equally distributed along the whole length
of the cantilever, the horizontal strain is equal to the weight per
foot multiplied by the square of the distance of the point of the strain
in feet from the unsupported end, and the result divided by twice
the depth of the cantilever in feet. Or otherwise, multiplying the
length of the cantilever from the point of support by one half of the
weight and dividing by the depth, or taking the whole weight mul-
tiplied by one half of the length of the cantilever and dividing by
the depth (see Fig. 701), equals the strain. It is evident that the

Fig. 700.

1
*64
•36
•16
•04
0
Fig. 701.
strain is least at the point of the cantilever where the weight is
suspended, and increases to the point of support; therefore, by
dividing the cantilever into five equal parts, naming the point of
support 1, the first point from that 64, the succeeding points 36,
•16, 04, and 'o at the end, the actual strain at the point of support
multiplied by these numbers will give the strain at the points
indicated.
Thus the top and bottom webs of the cantilever will be increased
from the point where the weight is suspended to the point of sup-
port, the thickness remaining the same, or otherwise the thickness
of the top and bottom members is increased from the point where
the weight is suspended to the point of support. Where the canti-
lever is imbedded in a wall or fixed at the end, the top and bottom
members are parallel.
}
ENGINEERING WORKS, ETC.
1001
In treating of this subject the late Professor Rankine con-
siders the beam to be under two actions, viz. a shearing force
and a bending moment. Thus a beam subjected to a load, as
at Fig. 696, would be under the action of shearing forces in each
half of the beam, each equal to half the load, and to a bending
moment equal to either of these shearing forces multiplied by the
half span; thus if W be the total load at centre, then =supporting
forces at ends, which give rise to shearing stress throughout each
half the beam, equal also to and the bending moment, therefore,
where L= span of beam. For a uniform
W L WL
becomes X
>
2
4
WL
load this becomes
8.
W
2'
W
2
The moment of resistance of a beam is its
fbd2
6
strength to resist a load applied as above, and for a rectangular
section is written thus, a, where f= strength of material, b and d
being breadth and depth respectively. By equating the bending
moment and the moment of resistance we can proportion the beam
to the load it has to bear; thus for a rectangular beam loaded
uniformly we have WL-bd. In any such equations we must be
fbd²
6
8
careful to have the dimensions in both sides in the same terms;
thus w and ƒ should be say lbs. or tons, whilst L, b and d must both
be feet or inches. ƒ in such a case as above given is called the
modulus of rupture. Thus if we have say a cast-iron test bar of
36 inches span, and a breadth and depth of 1 inch and 2 inches
respectively, and if we find that such a bar breaks with a load on
centre of say 3600 lbs., then
3600 × 36 _ ƒ× 1 ×
4
6
or
3600 × 36 × 6=ƒ=48,600 lbs. per square inch.
4×4
And this would be known as the modulus of rupture of cast iron.
The moment of resistance is sometimes expressed by the follow-
ing symbol, Д, where I represents what is known as the moment of
inertia of the section, and y being the distance of the most severely
strained layer from the neutral axis; the latter being a supposed
line in and at right angles to the neutral layer. The neutral layer
is that part of a beam which during bending is unaffected; all
layers above this being compressed, while all below are extended.
ƒ is a factor of strength which, if representing the ultimate strength
of the material, becomes the modulus of rupture as already stated.
1002
MODERN STEAM PRACTICE.
CONSTRUCTION OF GIRDER BRIDGES.
Experience has shown that the most economical proportion for
a wrought-iron girder bridge is for the depth to equal one-twelfth
of the span, that is, I inch of depth to I foot of length; and also,

Fig. 702.-Wrought-iron Plate Bridge. Roadway at Top.

W
Fig. 703.-Wrought-iron Triangular Bridge. Roadway at Top.

Fig. 704.-Wrought-iron Lattice Bridge, Roadway at Bottom.
when circumstances will admit, to have the railway or roadway
placed on the top of the girders, instead of being carried on cross
girders at the bottom of the main ones.
ENGINEERING WORKS, ETC.
1003
1
The usual forms for parallel girder bridges are plain web plating
(Fig. 702), triangular (Fig. 703), and lattice and trellis work (Figs.
704-706). The roadway can be placed on either the top or bottom
of the bridge. If on the top, the girder is generally surmounted
with a railing; but when the roadway is between the main girders,
no railing is required. If a footway is desired, it is carried on each
side by cantilevers or prolongations of the cross girders, with the
necessary railing for the protection of passengers.
Sometimes plain plated girders, curved on the top flange, are used
with advantage; such a form is more pleasing to the eye than plain

Fig. 705.-
-Wrought-iron Lattice Bridge. Roadway at Top.

Fig. 706.-Wrought-iron Trellis Bridge. Roadway at Bottom.
plated parallel girders. The cost, however, is somewhat greater,
owing to the plates requiring to be cut to waste, and the angle iron
requiring setting and forging.
In designing wrought-iron girder bridges for railway purposes, as
the weight of a locomotive is taken as the basis for the calcula-
tions, the testing load is generally a number of locomotive engines
coupled together; and it is desirable to make an allowance of
1 ½ ton per foot run as the load for a single line; this distributed over
the length of the girder is the greatest weight that can be brought
on it, taking the weight of the bridge likewise into the calculation.
1004
MODERN STEAM PRACTICE.
To find the breaking weight for wrought-iron box girders.—Multi-
ply the area of the bottom flange in square inches by the depth of the
girder in inches, and then by the constant 80 when the weight is at
the centre of the girder, or by the constant 160 when the weight is
equally distributed, dividing the product by the length of the girder
between the supports also taken in inches, and the quotient gives
the breaking weight in tons:-
Length of girder,
do.
:
150 feet.
II ft. 6 in.
Depth of
Between side plates,
73.5 × 138 × 80
1800
...
2 ft. 6 in.
= 450-8 tons breaking weight at centre.
The sectional area of the top and bottom flanges being as follows:-
Sectional area
of top flange.
Sectional area of
bottom flange. sq. in.
36 × 34
7x34 = 10°5
2 plates,...
36 x 76
=
3 do.
14×7
sq. in.
31.50
18.38
2 plates,
2 longitudinal do.....
2 longitudinal do……..
7×76
10 angle irons, ......3 × 3 × 16
6·13
= 26°25
2 angle irons,..
82.26
= 54°0
·3 × 3 × 3/4 = 90
73'5
Again, to find the strain on the top and bottom flanges in tons.
Multiply the weight distributed by the length between the supports
in feet, dividing the product by the constant 8 multiplied by the
effective depth of the girder in feet, and the quotient will be the
strain in tons. If the depth equals one-eighth part of the length
of the girder, then the strain on the top and bottom flanges
equals the weight distributed, as the factors above given, viz.,
WL will eliminate, leaving only W. If the depth equals
8x effective depth
one-tenth part of the length of the girder, then the strain on the
top and bottom flanges equals one and a quarter time; and when
the depth is one-twelfth, one and a half time.
Thus supposing a bridge is 200 feet between the supports, having
four lines of rails, with the load distributed, including the weight of
the girders, say 900 tons in all, and the depth is 25 feet, we have,
900 x 200
8x25
=900 tons, depth th of the span.
With the same span and the depth 20 feet, with the same load dis-
tributed we have
900 x 200
8 × 20
=1125 tons, depth th of the span;
ENGINEERING WORKS, ETC.
1005
and again, when the depth is 16·66 feet we have
900 x 200
8x16.661350 tons, depth th of the span.
The bottom flanges being in tension may be strained to 5 tons per
sq. in.; while for the top flanges, being in compression, 4 tons per
sq. in. may be allowed. For warm climates 4 tons per sq. in. may
be allowed for tensile, and 3 tons per sq. in. for compressive strain.
The Crumlin Viaduct in South Wales is a notable example of
the light open type of zig-zag or half-lattice girder. There are ten
spans in all of 150 feet each; these are carried on piers of open
ironwork, rising 200 feet high. The ties and struts were at first
connected to the flanges by pins, but were afterwards rivetted.
cases.
Tubular girders may be looked upon as enlarged forms of box
girders. Great examples of these girders are found in the Conway
and Britannia Bridges in Wales, and in the Victoria Bridge across the
river St. Lawrence in Canada. These bridges were all designed
by Robert Stephenson. The Conway Bridge consists of two
tubular girders, placed side by side, of 400 feet span, and through
which the train passes. The weight of each tube is 1300 tons. The
Britannia Bridge consists of two continuous tubular girders resting
side by side on three centre piers and two land piers or abutments.
The two great centre spans are each 460 feet, and the two shore spans
230 feet each. Engineers, however, do not now favour the tubular
form of girder, preferring rather the lattice type already described.
The Bowstring girder is a very suitable form of girder in many
Here the upper flange is curved, the lower flange acting as
a tie, whilst intermediate lattice work is fastened between. An
example of a bridge somewhat of this character was erected by
Brunel at Saltash. There are two spans of 433 feet each. The
upper part of each span consists of a hollow bow of wrought-iron
plate, and oval in section; the ends of this bow are connected by a
chain which hangs below the roadway. The bow rises in the
centre 29 feet, drop of chain 27 feet; total depth at centre 56 feet.
A bridge of rather peculiar construction has been built over
the Elbe at Hamburg, the largest spans of which are about
316 feet. The design is that of two bows, one placed like the chains
of a suspension bridge and the other being curved in the opposite
direction. The platform is supported by rods depending from each
of these bows.
гооб
MODERN STEAM PRACTICE
2C
PLATING GIRDERS.
We have already stated (see page 999) that the top and bottom
webs of parallel girders may taper in thickness from the middle of
the girder towards the ends. Of course, when the girders are short
this is not so much required-indeed, in such cases the fewer joints
the better; but when we use girders for long spans the plates on
the top and bottom webs are made to taper, which lessens the
weight of the structure, and also reduces its cost.
The plates should be ordered in as long lengths as convenient,
and should be arranged to break band one with another. The side
plates, as in box or web beams, afford very little strength to the
girder. The thickness of the plates varies from 14 inch for girders
of, say, 18 inches in depth; and for girders of 10 feet in depth for
120 feet spans, the thickness at centre is 1/4 inch, and at ends
3% inch; while for the great tubular girders crossing the Menai
Straits the side plates are ½ inch at centre and 5% inch at ends. The
plating in ordinary girders is arranged vertically, butted together,
having T iron joggled to take the top and bottom flanges, to
which it is securely rivetted, and at every alternate joint butt strips
are substituted. The platform is carried on cross girders resting
on the bottom flanges, and strongly rivetted to the sides on webs,
the flanges of the cross girders being turned down at the ends to
meet the web, as likewise to the bottom flanges; the depth of these
girders is regulated according to the width of the bridge, and they
are spaced every 4 feet apart. To the top of the girders imme-
diately below the rails a plate 18 inches wide and 4 inch in thick-
ness is rivetted for the entire length of the bridge, to which the
buckled plates for the roadway are securely rivetted. On the top
of these plates beams of wood are fitted, to which the rails are
fastened, as in the various modes adopted for permanent way, with
ordinary cast-iron chairs, or simply flanged rails secured to the
beams with screw bolts screwed into the wood.
It is necessary that all the joints forming the roadway should be
made perfectly water tight with a covering of asphalt, having proper
gutters for running off the water, and pipes placed at the ends for
carrying it away. In all cases this should be properly attended to,
as the rain water will otherwise drip through, to the great incon-
venience of passengers underneath, and likewise to the deterioration
of the structure.
ENGINEERING WORKS, ETC.
1007
DRILLING THE PLATES.
Where the plating, &c., of girder bridges is of a plain and parallel
kind the multiple drilling machine has been used with great advan-
tage. The old mode of punching the plates tends to distort the
material, leaving the upper surface slightly concave and the lower
surface convex. This deterioration has been found by experiment
to amount to about one-sixth less strength in the rivetted plates,
compared with those drilled by the multiple drilling machine.
Some of these machines are capable of drilling a row of holes in
a bar or plate 26 feet in length, the drills for ordinary work being
4 inches from centre to centre; but in some the drills can be arranged
to suit a variety of pitches of rivet holes. The plates are put on a
table which is raised by hydraulic machinery, and are thus forced
against the drills with a certain pressure regulated by a valve,
and the holes are all drilled at one operation with great speed and
exactness. The hydraulic pressure is given by an accumulator,
which is simply a vertical cylinder fitted with a loaded piston to the
required pressure, which forces the plate against the drill with a
pressure of about 672 lbs. The superior workmanship obtained by
the drilling machine without distorting the plates obviously recom-
mends itself, although the cost may be a trifle over work done by
the multiple punching machine. The rivetting of bridges is of as
much importance as that of ships or steam boilers. If the rivets
do not fill the holes exactly the influence of the weather soon tells
on the structure; water will lodge around the rivets and corrosion
take place. More especially all the struts and ties in lattice
bridges should be securely rivetted; unless this is attended to at
first, the vibration caused by the passing trains, combined with the
corrosion that sets in, soon loosens the rivets, tending to weaken the
structure. With rivets 3/4 inch and I inch in diameter, the holes
are pitched about 6 inches from centre to centre for the top webs,
and 3 inches from centre to centre for the bottom webs on flanges.
EXAMPLES OF SCANTLING AND WEIGHT OF RAILWAY BRIDGES
ERECTED ON THE PLAIN-GIRDER PRINCIPLE.
Bridge for three sets of rails, plain girders, with two facing girders,
having arched plates for the roadway, with wooden sleepers laid on
the top of the cross girders.
1008
MODERN STEAM PRACTICE.
Span,
Depth of girders,
Top flange (width),
Thickness of plates (two),
Bottom flange (width),
Thickness of plates,
Thickness of web,
...
Vertical stiffening pieces (6 off),
Diameter of rivets,...
:
...
...
:
:
...
:
:
:
...
51 ft. o
6
3,,
I 8
O
I
о
""
4
034
O 04
""
in.
"
,,
""
5 in. x 2 in. x ½ in. x ½ in.
o ft. 034,,
Angle iron for connecting web to flanges (2 off),
...
...
""
4 in. × 4 in. × 5%
2 ft. 6 in. x 2 ft. 0 in. × 34,,
Bearing plates at ends,
Four bolts for do.,
Top flange,
...
I in.
FACE GIRDers.
II in. wide by 4 in. thick.
9 in. wide by 14 in. thick.
Bottom flange,
Web, 4 in. thick; flange angle iron, 4 in. × 4 in. × ½ in.
The weight of eight girders is
WEIGHT.
The whole weight of the bridge is
38 tons 14 cwt.
...
50
""
14 "
Bridge for three sets of rails, plain girders, with two face girders
similar to the foregoing example, and having arched plates for road-
way 4 inch thick, with a rise of 3 inches, rivetted to the top of the
flanges of the girders, with rivets ½ inch in diameter and 4 inches
pitch. Longitudinal timbers for rails, 16 inches wide and 6 to
9 inches in thickness, laid on the top of cross girders:-
Span,
Depth of girders,
Top flange (width),
Thickness,
Bottom flange (width),
Thickness,
Thickness of web,
...
...
:
:
:
...
...
Angle iron for connecting web to flanges,
Vertical joints, two T irons,
Top flange,
Bottom flange,
Angle iron for do.,
Diagonal braces,…….
...
FACE GIRDers.
...
...
...
:
...
...
WEIGHT.
The weight of six main girders is
The weight of two face girders is
The whole weight of the bridge being
...
...
...
...
:
:
...
41 ft. 0 in.
2 6
""
I
I
""
""
O
4
034
3
034
04
4 in. ×4 in. × 34
""
""
3/4"
5 in. × 2½ in. x 3%
9 in. wide by 4 in. thick.
9 in. wide by 4 in. thick.
3 in. x 3 in. x ½ in.
3 in. x ½ in.
...
:
26 tons 5 cwt.
15 ",
4,
43,
The depth of plain girders for bridges of this description varies as
follows:-
ENGINEERING WORKS, ETC.
1009
37-feet spans = 2 ft. 6 in.
41-feet spans = 3,, O
1
""
=
46-feet spans
3 ft. 6 in.
51-feet spans = 3,, 6
Sometimes it is advisable to secure cross girders to the under side
of the two main girders of the single-web description; but this plan.
should be avoided as much as possible, as the cross girders are
secured to the main ones with only a few rivets, whereas they should
rest on the flanges of the side or main girders, thus much greater
strength is obtained. We give an example of this mode of con-
struction. One end of each main girder rests on eight rollers
4½ inches diameter.
Length of main girders,
Depth at centre,
...
Depth at ends,
...
Top flange (width),
...
:
::
:
:
...
82 ft. 3 in.
7 ",
6
2
35
360
""
2
་
35
Thickness at middle, four plates, each...
Thickness at ends, three plates, each
Bottom flange (width),
...
...
...
Thickness at middle, one 34-in. plate and two 5%-in. plates.
Thickness at ends, one 34-in. plate and two
Angle iron for flanges,
Plating-two end plates,
Next two plates,
The remainder,
Vertical joint T iron,
...
...
%-in. plates.
::
:
::
O
""
""
05%
0%,.
2
о
""
NO
6 in. × 6 in. × 34 in.
2 ft. 0 in. x 3/8 in.
2 ft. 4 in. x 3 in.
3 ft. 0 in. x 4 in.
6 in. x 3 in. × 3% in.
Vertical rivets, I in.; all other rivets, 34 in. diameter.
Length,
Depth,
Spaced,
Flanges (width),
Thickness,
...
CROSS GIRders.
...
:
39 ft. 0 in.
I
", 4
""
3 ",
O
I
,, 3
་
O
""
034
...
Web, 4 in. thick, with angle iron 5 in. x 3 in. × 5% in.
Two main girders,
WEIGHT.
The total weight of bridge being
...
...
49 tons 16 cwt.
141 ", 13,
Another example like the foregoing is for two sets of rails.
Length of girders,
Depth at centre,
Depth at ends,
...
...
:
:
:
:
...
85 ft. o in.
6,, 6
5,, 3
2
O
O 0%,,
Top flange (width),
Thickness, four plates at centre, each…..
Thickness at ends, three plates, each
Bottom flange (width),
...
...
...
...
2
Thickness at centre, one 34-in. plate and three %-in. plates.
Thickness at ends, one 34-in. plate and two 5%-in. plates.
Two angle irons for web, 6 in. x 6 in. x 3/4 in.
""
""
0%,,
O
64
ΙΟΙΟ
MODERN STEAM PRACTICE.
CROSS GIRDERS.
Depth,
Thickness of web,
Two angle irons top and bottom,
...
I ft. 4 in.
0 ""
""
4 in. x 4 in. × 34
Three vertical T irons for stiffening the cross girders.
Diameter of rollers,
...
4½ in.
The upper and lower plates 2 in. thick, the frames of wrought iron 3 in. x 1 in.
WEIGHT.
The weight of two main girders is
The weight of the cross girders
The total weight of the bridge
...
49 tons 5 cwt,
29,, 16
94,
O
A larger example differs slightly from the former arrangement, the
bridge being skewed, span on skew 118 feet.
Length of girders,
Depth at centre,
:
134 ft. 0 in.
o
12
""
O
9", O
2 6
""
Depth at ends,
Top flange (width),
...
Thickness at middle, five plates, each
Thickness at ends, three plates, each ...
...
...
O
""
""
0%,,
O
0%,,
Angle for connecting ribs, as likewise for edge of plate, 5 in. x 5 in. x 18 in.
Thickness of bottom flanges at middle, one -in. plate and four %-in. plates.
at ends, one 1-in. plate and two 5%-in. plates.
Do.
do.
Bar on each side of angle iron,
Web plates, width at middle,
Do.
at ends,
99
...
...
Thickness of nine plates at each end,
All the other plates,
End vertical plates,
Stiffening angle iron,
:
:
9 in. x 18 in.
2 ft. 2 in.
2
""
O
O 03/8,
""
5
O 016
""
14 in. thick.
3 in. x 3 in. × ½ in.
Intermediate vertical joints have two T irons 6 inches by 3 inches
by 3% inch thick; all alternate joints have strips 6 inches by 3% inch
thick, joggled to take the longitudinal angle iron.
CROSS GIRDERS.
Length,
Depth at middle,
Depth at end,
Spaced,
...
Flanges (width),
Thickness of do.
Angle iron for do.
Additional top plate,
Thickness of do.
:
:
:
:
:
:
41 ft. 6 in.
2 ×
I
""
4 ",
I
O
4
O
", 3
""
""
""
""
04"
4 in. × 4 in. × 5%,,
""
I ft. 7
0,, 0¼
""
The ends of the cross girders are rivetted to the main girders with
twenty-four 1-inch rivets. The rivets through longitudinal angle
iron and web are 1 inch in diameter, and through vertical T iron
ENGINEERING WORKS, ETC.
ΙΟΙΙ
and strips 3/4 inch diameter. One end of each main girder has a
bearing plate 5 feet by 4 feet by 34 inch thick, and the other end
has a cast-iron plate 2 inches thick, bearing on eight rollers 4½ inches
in diameter, the roller beds being of cast iron 2 inches in thickness
strengthened with ribs.
WEIGHT.
The weight of each main girder is ...
The weight of all the other cross girders
Total weight of bridge,
...
:
...
:
...
65 tons.
80
248
CONSTRUCTION OF LATTICE GIRDER BRIDGES.
PRINCIPLES OF CONSTRUCTION.
In illustrating the principles upon which lattice girder bridges
are constructed, it will be necessary in the first place to discuss the
nature of the strains to which the different parts of such bridges are
.S.

2
6
2
15
13
10
--------------------------
Ն
B
Fig. 707.-Girder.
subjected. Take for example a gross load uniformly distributed over
the length of the girder.
Let A and B represent two piers supporting a lattice girder, as
shown in Fig. 707.
1 = clear span of the girder in feet.
d =
depth of the girder in feet.
L
=
length of one lattice bar in feet.
S
= distance between the summits of two contiguous triangles in feet.
w = load in tons per lineal foot of girder.
We will first consider the struts and ties. It is evident that as the
girder is uniformly loaded, each of the piers at A and B will bear
one half of the load, so that all the weight on the left of the centre
of the girder will be transmitted through the bars to the pier A, and
on the right to the pier B. The load being supposed to be on the
top of the girder, the strain on the bar I will evidently be in com-
pression, while that of the bar 2 will be in tension, the strain again
1012
MODERN STEAM PRACTICE.
x
_y_
appearing as compression on bar 3, with an addition to it in the
compressive strain on the bar due to the load carried at the junc-
tion of the bars 2 and 3. Let us now consider what relation the
strain on the inclined bars will bear to the weight imposed on them.
The load upon the summit of
each triangle will evidently
be equal to the load per lineal
foot multiplied by the dis-
tance in feet between the
apices of two contiguous tri- b
angles, or if W equal this load,
then
W=w, s
a
灰
​
a
N
b
Fig. 708, 709.-Diagrams for Strains.
The strain produced by such load upon the inclined bars can be
solved by the well-known principle of the parallelogram of forces.
In the case before us two solutions will be required, which will be
made clear by reference to the diagrams x and y, Figs. 708, 709.
x shows the method of solving the strain for the central bars of the
lattice girder.
Let ab and ac represent the directions of the inclined bars, and
the line ae, which is vertical, the weight of the load at a; taking
a e as the diagonal, complete the parallelogram a feg, then the strain
upon the bar a b will be equal to
af×W.
a e
The bars being at equal angles to the horizon, a condition which
always occurs with the central bars of a lattice or triangular girder.
Let S the strain upon the bar ab, and a=the angle which it
makes with the horizon, thus
S=
W s
W
2 sin a 2 sin a
and supposing the bars to be placed at the same angle to the horizon,
a strain of this intensity will pass through all the struts and ties
between the centre of the girder and the pier A, being due to the
load on the centre triangle. It may be as well to note that the bars
inclining towards the centre of the girder are in compression, while
those inclining from the centre of the girder are in tension.
The second case to be solved is shown by the diagram y, and
applies to all the struts except those at the centre.
Let ae be equal to the load at a, ab indicating the direction of
ENGINEERING WORKS, ETC.
1013
•
the inclined bar, and ac that of the top flange of the girder; from
the point e complete the parallelogram a bec, the strain a b, due to
the load on a, will then be equal to
or in mathematical language
abxW;
a e
W
W s
S=
sin a
sin a
and this strain will pass through all the struts and ties between the
bar to which it refers and the nearest point of support upon which
the girder rests.
From these formulæ we can now determine the strain upon the
struts and ties of any triangular or lattice bridge whatever, but it
will be as well to distinguish the angles of the struts and ties, as in
some cases they are not made equal. Let the angles made by the
struts and ties respectively with the horizon be represented by a
and ß. It must also be observed that if there be more than one
series of triangles, the distance s is to be measured between any
two contiguous points where the struts and ties meet the flange; or
if measured on the base of one large triangle, the strain must subse-
quently be divided by the numbers of series of triangulations, for
where two, three, or more series of triangles are used, they may be
regarded as a splitting up of one main system of triangles.
The following is a very convenient method of summing the strains
upon the struts and ties of a lattice girder; tension is represented by
the minus (—) sign and compression by the plus (+) sign.
+
W s
2 sin a
Strain on Ist strut from centre,
...
Do.
Ist tie,
Do.
2d strut,
:
Do.
2d tie,
:
Do.
Do.
Do.
3d strut,
3d tie,
4th strut, ..
...
Do.
4th tie,
...
Do.
nth strut,...
Do.
nth tie,
...
W s
+
sin a
ᏃᏪ -
2 sin ẞ
W s
+
3 ໃບ 8
2 sin a
2 sin a
3 w s
W s
3 w s
+
2 sin ß
5 w s
= +
sin a
W s
2 sin a
5 w s
+
sin a
2 sin a
...
= +
2 sin a
5 w s
2 sin ß
7 w s
2 sin a
7 w s
2 sin B
(2 n − 1) w s
2 sin a
2 n − 1) w s
2 sin B
1014
MODERN STEAM PRACTICE.
The last two give the general formulæ for any strut or tie of the nth
pair from the centre of the girder.
The commonest angles used in the construction of lattice girders
are 45° and 60°, and the sines of these are as follows:-
hence
sin 45°=0*707.
sin 60°-0.886.
I
sin 45°
I
=1'412.
sin 60°=1'1287.
But the formula may also be stated thus-
As an example, let it be
I L
sin a d
required to determine the strain on the
fifth pair of bars from the centre of a girder under the following
conditions:-
w=1'5 tons per lineal foot.
S=7 feet.
a=60 degrees.
I
sin a
=1*1287.
There being only one system of triangulation in the girder, then the
strain is
S=(2
− _
X
tons.
2 n − 1) w s _ (2 × 5 − 1) 1°5 × 7 × 1'1287=53°33′
2 sin a
2
The strain being thus ascertained, the next step is to determine
the least sectional area for the strut and tie, in order that they may
safely sustain the load imposed upon them.
For this class of work wrought iron may be safely strained up to
35 tons per square inch in compression, and 4'5 tons per square inch
in tension, for bridges intended for warm climates; hence the sec-
tional area of the bars will be-
Sectional area of strut=53°33=15.2 inches.
3'5
Sectional area of tie
53.33-11.8 inches.
4.5
We will now proceed to consider the strains which are brought
to bear on the top and bottom flanges of the girder: the strains on
the top flange will be due to the ties, and will be of a compressive
character; those on the bottom flange will be produced by the struts,
and will be tensile in character.
ENGINEERING WORKS, ETC.
1015
Let F the strain on the top flange produced by one tie on
which S'the strain, then,
F=S'
sin (a+B)
sin a
;
thus F will be the strain produced upon one part of the top flange
by the resolution of that one tie, and the strain from the first tie
next the pier will pass along the top flange to the centre between,
increased at every tie by the strain which is brought upon the flange
by that tie. On the lower flange the tensile strain due to any stress
is in like manner determined, thus,
f=strain on the bottom flange produced by one strut on which S'the strain, then,
f=S'
sin (a+ẞ)
sin ß
Hence for any strut and tie the formulæ for the corresponding incre-
ments of stress on the lower and upper members will be
For the lower flange
f=
(2n-1) ws
2 sin B
X
sin (a + B) _ ws (2 n − 1) sin (a+ẞ).
sin B
3 (sin ẞ)²
For the upper flange
F_(2n-1) wssin (a+B)_ws (2 n − 1) sin (a+ẞ)
3 sin a
X
sin a
2 (sin a)²
By calculating the increments from these formulæ and summing
them up according to the number of struts or ties between the point
at which the strain is required and the nearest pier or point of sup-
port, the data will be obtained wherefrom the proper sectional areas
of the flanges may be determined.
DETAILS OF CONSTRUCTION.
We now proceed to give the practical application of the above
formulæ. Let it be required to design a lattice girder bridge to
a
а1
as
as
аб

b
05
Z....
Fig. 710.-Girder.
B
carry two lines of rails of the ordinary 4 feet 8½ inches gauge, the
trussing consisting of bars at an angle of 45 degrees to the horizon,
1016
MODERN STEAM PRACTICE.
as shown in Fig. 710, there being two systems of triangles, and the
girder being divided into ten sections or bays inclosed by the
uprights a b, a₁ b₁, &c. Let the span of the bridge be 100 feet, then,
as it consists of ten squares, the depth of each girder will be 10 feet.
In the first place, we must consider the nature and intensity of the
load the structure is designed to sustain. In the present case it is
that due to the weight of railway trains, of passengers, and of the
bridge itself. The variable or moving load is called the live load, and
is usually taken as a maximum at one ton per lineal foot for each
line of rails. The weight of the structure itself per lineal foot will
vary with the span; we will here assume it to be one ton per lineal
foot for the entire bridge. There being two lines of rails, the total
load per lineal foot will be-Live load for the two lines=2 tons,
dead load for the whole I ton=3 tons per lineal foot. This load
being carried by the two main or principal girders, the actual load
per lineal foot on each will be=1.5 tons.
=
The weight on each of the standards a b, &c., will evidently be
equal to that between two contiguous ones, and as these are 10 feet
apart this load will be
=15×10=15 tons;
and of this one half is passed to each of the triangles, hence for each
set of bars the loads at the apices will be = 7.5 tons.
In the formula already given this load is ws, but that refers to a
single system of triangles. To find the load when there are m
systems and N girders, we have
W S
m N
In the present case there are two systems, two main girders: the
total load w=3 tons per foot, s 10 feet; hence,
5
3x10=7.5 tons=W.
2 X 2
It is only necessary to treat one half of the bridge, as it is sym-
metrical. When the load is on the top of the girder, a5 b5 will be a
strut and a bá a tie; but the intensity of the strain will be the same
on both. If the load be carried at the bottom of the girders the
strains on the uprights will be tensile. The strain in amount on
each will be 75 tons; one half of each total load goes direct to
one set of triangles, the other half passing through the upright
to the other set of triangles.
ENGINEERING WORKS, ETC.
1017
Commencing from the centre, we will now calculate the strain on
The general formula is
each bar of one set of triangles.
s=(2n-1) W
2 sin a
;
but a=45 degrees; hence sin a=0'707.
I
I
=1'412,
=0'707;
sin a
2 sin a
hence the formula becomes
S = (2 n − 1) 0·707×7°5=5′3 {2 n − 1};
the strains on the diagonal bars will therefore be as follows:-
On the Ist,
""
2d,
5'3 × (2× 1−1) = 5'3 tons.
5°3 × (2 × 2 − 1) = 15′9
""
3d,
""
4th,
53 × (2 × 3−1) = 26°5,,
5°3 × (2×4 −1) = 37°1
47'7"
5th, 5°3 × (2× 5 − 1) = 47°7
Allowing 5 tons per square inch as the safe load for the ties and
4 tons per square inch for the struts, both being of wrought iron,
we have for the least sectional areas the following:-
Ist tie,
5°3
= 1'06 square inches.
5
5'3
Ist strut,
|}
I'32
4
2d tie,
2d strut,
3d tie,
tinin in +
15'9
= 3.18
""
5
15'9
3.97 ",
4
26.5
5'30
บา
5
26.5
3d strut,
= 6.62
""
4
4th tie,
37'1
= 7°42
""
5
37 I
4th strut,
9'27
4
47'7
5th tie,
9°54
5
47'7
5th strut,
= 11'92
4
Having ascertained the strains on the diagonal struts and ties, we
can now determine those which fall upon the top and bottom hori-
zontal flanges, or booms as they are sometimes technically termed.
It is observed that the strains on the web or diagonals is at a
minimum at the centre, and increases towards the ends or piers
A and B; but, on the other hand, the horizontal strains increase from
the piers towards the centre. Thus the strain thrown by the bar ba
1018
MODERN STEAM PRACTICE.
on the top flange passes right through, and at a₁ an additional
increment of strain is derived from the bar b a, and so on. The
strains on the top flange are compressive, those of the bottom flange
tensile. If T=the strain on the flange due to that transmitted from
any bar on which there is a strain S, we have for the general formula,
T=S sin (a+B);
sin B
but a=3=45 degrees, hence the formula becomes
T=s sin 90 ;
sin 45
but sin 90=1, hence
T=S_I
=1'4142 S.
0'707
The intensity of the strains on the segments of the horizontal flanges.
will be as follows, commencing at pier A:-
Ist segment,
2d
3d
ཙྩཊྛཾ
1'4142 = (1'4142 × 47°7)
67.45
4th
5th
119'91
157.38
179.86
67'45 tons.
+ (1°4142 × 37′1) = 119'91
+ (1'4142 × 26°5) = 157°38
+ (1°4142 × 15°9) = 179·86
+ (1'4142 × 5*3) 187.36
=
From this series it will be observed that the first segment receives
strain from the last strut or tie; the second segment sustains this
strain, and in addition thereto one brought on it from the last strut
or tie except one, and so on to the centre of the girder, where the
strains from each half meet and balance each other.
Using the factors of safety for tension and compression as before,
we have the sectional areas of the flanges as follows:-
Tension,
Ist segment,.
67.45
5
sq. in.
= 13'49
......
Compression,
67.45 = 16.86
4
Tension,
119'91 =
23.98
2d segment,
......
Compression,
3d segment,..
.....
Tension, 157:38
5
Compression, 157'38
29'97
= 31'47
5
119'91
4
= 39°34
4
Tension,
4th segment,....
179.86
5
35'97
Compression, 179.86
44.96
Tension,
5th segment,....
Compression,
4
187.36
5
187.36
4
= 37'47
= 46.84
ENGINEERING WORKS, ETC.
1019
We must now ascertain the necessary area of the struts at the end,
as ab. As has been already said, one half of the whole load on
the girder is sustained by the pier A, and of this one half is trans-
mitted to the pier direct from a b, and the other half passes from
the bar b₁ a through the end strut a b; therefore a b carries a load
equal to one quarter the load on one girder, or one-eighth of the
total load on the bridge; hence the load or strain on the strut a b
=100x3=
8
and its sectional area will be
=37.5 tons,
37°5=9*37 square inches.
4
The sectional areas of the pins or rivets for joining the diagonal
bars to the flanges must also be determined. These have to resist a
shearing strain, and the sum of all the areas of those sections which
would be sheared through in case of a breakdown must not be less
than the areas of the respective struts which are sustained by them,
if the pins are made of wrought iron; but if steel pins are used,
their dimensions may be reduced according to the quality of the
metal employed.
The cross girders now require attention. They may be either
plate or lattice webbed; we shall assume the lattice form, as shown
in Fig. 711.
Let A B represent one cross girder, attached at the ends to the
lower flanges of the main girders c and d; the load may be taken
as uniformly distributed, the distance between the flanges of the

A
C
Fig. 711.-Cross Girder.
a
B
main girders representing the span of the cross girders, the distance
being 21 feet 6 inches. The depth of the cross girders may be taken
as 2 feet. It is usual to make all these girders of one size, hence
it will be sufficient to calculate the area of that one which is most
strained. The cross girders being 10 feet apart, the total load on
each will be (taking the moving load at 2 tons, and the weight of the
girder, &c.. at I ton, an ample margin being allowed),
3× 10 30 tons,
1020
MODERN STEAM PRACTICE.
half of which passes to each main girder: hence 15 tons will be the
heaviest load on any strut, giving as the strain
15×1*4142=21*21 tons,
and the corresponding section will be
21'21
4
=530 square inches.
In this case we have placed the cross girders rather wide apart, but
the reason for doing so will subsequently appear.
In calculating the area of the flanges we may use a simple rule,
obtained by treating the flanges and depth of the girder as forming

C
B w
x
A
1
-2
.............
W
Fig. 712.
a bent lever, Fig. 712. As one half of the load on the girder is sup-
ported at each end, each pier must react upwards with a correspond-
ing force; using the former notation the reaction of the pier
wl.
;
2
and regarding A B C as a bent lever, the pressure at C will be
w/AB
X
2
BC
but A B equals, and BC=d, hence the above expression
W
w 12
Ad
2
but acting in an opposite direction we have the weight, which
may be considered as aggregated at its centre of gravity at W, the
force of the pull at c due to this weight will evidently be
W12
8 d
hence subtracting this from the last we have the resultant strain
W 12
W12 2012
4 d
8 d 8 d
call w/= total load=w, when this expression
WI
8d;
ENGINEERING WORKS, ETC.
1021
but in the case under consideration w=30 tons, l=21.5 feet, d=
2 feet, hence the strain on either flange
30×21˚5–40°3 tons,
8x2
and the sectional areas will be
Top flange 40'310'07 square inches.
4
Bottom flange=40°38′06
5
""
""
Between the cross girders the rails will be carried by four lines of
rolled girders, each 10 feet long and 10 inches deep, hence the main
central load on each will be that produced by a locomotive engine
passing over; when at the centre assume this to be 10 tons, then the
strain on either flange
ΙΟ ΧΙΟ
=
8x0·83
and the area of the flanges will be
= 15 tons,
Top flange = 15=3'75 square inches.
4
Bottom flange = 15 €3.00
5
""
From the data given we shall now proceed to determine the form
of the various details of the bridge which has been selected for an
example. It is to be remembered, that in determining these forms
of which the sectional areas have been found, whilst we are not
strictly tied to the results obtained from previous calculations, in
no case must the net sectional area be less than that determined
by the formulæ. The net sectional area of any element is that
area which is available to resist the strain bearing upon it, and is
A
C
e
D
C
A
D
Fig. 713.—Cover Plate.
B
B
exclusive of what is rendered
useless through the presence of
rivet holes, &c.
If two plates be butted to-
gether, as shown in Fig. 713,
and joined by a cover plate,
then the strain may be trans-
mitted from one to the other;
but care must be taken that the
joint be equally strong with the


solid section, for the weakest part is the measure of the strength
of the work. In the plan view A and B are two plates united by
1022
MODERN STEAM PRACTICE.
the cover plate CC placed over the joint D. In the side elevation A B
are the two plates to be joined, and CC the cover plate. In some
instances two cover plates are used, one above and another below
the main plates, thus utilizing two sections of each rivet instead of
one; for it is evident that when one cover plate only is used each
rivet is strained at one place, but if two cover plates are used, then
the strain on the rivet must be in two places, making a much
stronger fixture.
If the strain on the plates is compressive, and the ends of the
plates are planed to make an accurate joint, then the cover plate does
not take any of the strain, for the ends of the main plates being in
contact the thrust passes direct from one to the other, and all the
duty of the cover plate is to retain the ends of the main plates in
their proper position; hence in this case the cover plates may be
made quite short, and no deduction need be made from the gross
sectional area of the plate for rivet holes, as the compressive strain
will be transmitted laterally through the rivets.
it
Where the strain to be transmitted is tensile, then the whole of
passes from one main plate to the rivets in that plate, from those
rivets it passes to the cover plate, or plates if two be used, and thence
through the rivets on the other side of the joint to the main plate
on that side. Thus it is evident that the rivets on either side of the
joint must offer sufficient sectional area to enable them to resist the
whole strain. Practically the net sectional area of the rivets is
usually made equal to the net sectional area of the plate, which
under tension is found by deducting the loss from rivet holes from
the gross sectional area of the plate. In arranging the rivets as
shown in Fig. 713, care must be taken to pitch the alternate rows
of rivets sufficiently far apart, so that the sectional area taken on
the line ee shall not be less than that taken diagonally across
the plate through two rivet holes as represented by the dotted
lines. On the line e e there is only one hole, so the area must be
greater.
In order to show practically the method of designing cover plates
for tension joints, we will take one example which will serve as a
guide for other cases. We will assume that one cover plate
only is used, and that there are two rows of rivets in it of 3/4 inch
diameter, set at a pitch of 3 inches from centre to centre;—and it
may be remarked, that for general work this size and pitch is
very commonly employed. The following table may be useful as
ENGINEERING WORKS, ETC.
1023
showing suitable diameters of rivets for uniting plates of various
thickness:-
Thickness of Plate.
4 in.
5
16
3/8
7/8
T
1/2
""
...
:
16 ""
...
5%
Diameter of Rivet. | Thickness of Plate.
½ in.
5/8
33
1 1
긇 ​in.
...
5%
5/8
3/4
3/4
""
I
3/4
13
7/8
15
16 "
""
:
:
3/4
""
...
...
...
:
:
:
Diameter of Rivet.
% in.
7/8
7/8
""
I
""
I
I
""
Let a joint be required to be made between two plates, 10 inches in
width and ½ inch in thickness. The gross sectional area will be
=10×0.5=5 square inches,
but from this must be deducted the loss from rivet holes. There are
two rivet holes in a line across the plate, each 3/4 inch in diameter,
hence the loss of area
=0*75×0°5×2=0'75 square inch,
wherefore the net area will be
=5-0°75=4°25 square inches,
and the number of rivets on each side of the joint must be sufficient
to present the same sectional area in the aggregate. As each rivet.
is 3/4 inch in diameter, its area will be
=(0*75)²×0*7854=0'44 square inch,
hence the number of rivets will be found by dividing the required
sectional area by 0'44, thus-
4:25
0'44
=9'7=say ten rivets.
There will, therefore, have to be ten rivets on each side of the joint,
that is, twenty rivets in the whole length of the cover plate, in two

.7.3%..
.1.3.....
oooooooooo
০০০০০০০०००
2.6
B
Fig. 714.-Cover Plate. AB, Plates. c, Joint.
rows of ten each, as shown in Fig. 714. From this the length of
the plate may be determined: the pitch of the rivets being 3 inches,
and allowing 1½ inch lap at each end of the plate beyond the
rivets, the total length of the plate will be 2 feet 6 inches, or I foot
1024
MODERN STEAM PRACTICE.
3 inches on each side of the joint. If two cover plates are used it
is evident, as each rivet will do double duty, that only one half of
the number of points will be required. Taking a single cover to be
the same width as the main plate, where two are employed they
will be of half the thickness, in order to give the requisite strength.
The following table of the areas of rivets will be found useful
in calculating cover plates:-
Diameter of Rivet.
1
o in.
16
1/8
3
16
1/4
5
16
3/8
7
16
1/2
""
""
""
>"
""
:
...
:
Area of Rivet.
0'0030 in.
O'0122
0'0276
""
""
0'0490",
0.0767
O'1104",
0*1503,,
0'1963
Diameter of Rivet.
9
16
It in.
5/8
1 1
3/4
1 S
He
6
7/8
""
""
""
་
""
""
1 5
16
""
I
""
...
:
...
:
:
Area of Rivet.
0.2485 in.
0*3068
0'3712,,
0'4417,
0.5185
""
0.6013,,
0*6903
0.7854",
We have entered thus fully into the particulars of joints, as the
security of the bridge will depend as much upon their proper con-
struction as upon the strength of the metal used.
necessary to determine the actual sec-
It is now
7.6'
tions of the different elements of the
bridge, and in the first place we will
settle the general form of the flange
sections. The central area of the top
flange is to be 46.84 square inches. The
general section for both flanges may
be as shown in Fig. 715, but the thick-
ness of the plates will vary in the differ-
ent segments according to the areas
required; throughout the flanges the
angle iron will be 3½ inches wide by ½ inch thick at the points,
being thicker at the neck. The strain on the top flange being in
compression, there is no deduction to be made for loss by rivet.
holes, the whole area being effective, and the thickness at the centre
of the girder may be as follows:-

Two top flange plates, each
Two side
do. each
The sectional areas will then be
Two top plates,
Two side do.
Two angle irons,
...
...
...
Total area,
Fig. 715.-Section of Top and Bottom
Boom Plates of Girder.
:
5% in. thick.
3/4
18 in. x 2 x 5% in. =22.5 sq. in.
12 in. x 2 x 34 in. = 180
3½ in. × 3½ in. x ½ in. = 7'5
48'0 sq. in.
ENGINEERING WORKS, ETC.
1025
46.84 square inches being the minimum area, this will meet the
requirements of the case.
From this point the areas diminish towards the piers, the thick-
nesses of the plates being reduced according to a ratio which will
be afterwards shown. At present we will determine the area at
the centre of the bottom flange, assuming the general section to be
the same as for the top flange, but of course inverted. And, first,
we must ascertain what holes there may be in the metal whereby
the net area is reduced. Let the rivets be in this case 34 inch
in diameter and 4 inches pitch, then in one section there will be
four sets of rivet holes to take out, and in addition to this the
holes in the side plates for the pins by which the ties and uprights
are attached to the flanges of the main girder. These pins, in case
of failure, must be cut through in the sections by the side plates
of the flange, hence if we allow 3 tons per square inch for the
safe load on steel pins, the load at each pin being 15 tons, the sum
of the areas of the two sections will be
– 15
3
5 square inches,
therefore the sectional area of each pin will be 2.5 inches, and its
diameter
2.5
0·7854=1'78 inch.
This is for the centre pin, where there is no strain from the struts
and ties; but the pins must be increased towards the piers, where
they have to transmit the strain from the struts to the tie, and vice
versâ. The strain on the end bar is 477 tons, and this load is sus-
tained by two sections of the pin, hence the sum of the areas of those
sections should be
.47.7
= 15'9 square inches,
3
so we will call the sectional area of the pin at the pier 8 inches,
which corresponds to a diameter
8
0*7854 =3'19 inches.
The intermediate pins will vary in area in direct ratio to their dis-
tances from the centre pin.
Calling the centre pin 134 inch in diameter, the actual losses upon
the sectional area with plates of the sizes shown in the preceding
figure will be as follows:-
65
1026
MODERN STEAM PRACTICE.
Rivets in flange plates,
...
2 × 2 × 34 ×
5% = 1·875 sq. in.
Do.
side plates,
2 × 3/4 × 3/4
= 1'125
Do.
angle iron,
=
2.625
Pin in side plates,
2 × 2 × 3/4 x ½ = 1'500
2 × 134 × 34
I
""
,,
7.125 sq. in
Take the total sectional loss at 8 square inches, then the net area
left after deducting this, would be
48-8=40 square inches.
The actual area required would be 37'47 square inches; hence by
making the plates in the bottom the same size as those at the top,
a slight excess of strength is obtained over what is required.
From this it may be inferred that, in bridges of this kind, the gross
sectional area of the bottom flange may always be made the same
as that of the top flange, hence it is not necessary to calculate the
section of the latter.
The loss through rivet holes with rivets of any constant diameter
necessarily varies as the thickness of the plate, wherefore it is bene-
ficial to the strength of the work to keep the plates and bars as thin
as is consistent with due rigidity, in order to diminish such loss as
much as possible.

A
d
e
C
B
Fig. 716 shows the general arrange-
ment of one of the main joints of a
bridge. A B is a section of the flange,
to which the bars are connected by
the screwed bolt cc passing through
the two side plates, the uprights, and
the ties and struts. Each tie and
strut is formed of two flat parallel
bars, the struts being rendered rigid
by suitable diagonal bracing placed
between the bars. In the cross sec-
tion dd are the bars of a strut, ƒƒ
being those of a tie, and gg are the uprights which are carried on
the ends of the screwed bolt. A hollow cast iron distance piece e
surrounds the bolt cc, preserving the proper distance between the
strut bars dd; and the whole is kept tight up by the head and
nut bearing against the uprights gg. Sometimes the pins have a
cotter instead of the nut, according to taste or convenience.
Fig. 716.-Main Joint.
In the main joints of the bottom flange provision has to be made
for fixing the cross girders, which are bolted to the under side of the
ENGINEERING WORKS, ETC.
1027
flange plate, hence the load will be carried by bolts, which should
be 3/4 inch in diameter. It will be necessary to ascertain how many
of these will be required: the load at each end of each cross girder
is 15 tons, hence by allowing 5 tons per sectional square inch as the
safe resistance of wrought-iron bolts, the area will be
15=
5
= 3 square inches,
the number of bolts requisite to secure the cross girders at each
end will therefore be
3_
0'44
= 6·8 = (say) 8.
Of these four may be outside, and four between the side plates. In

B
A
Fig. 717.-Mode of Fastening the Cross Girders.
Fig. 717 A is the section of the bottom flange, and B is a portion of
one of the cross girders; cccc are four of the bolts, and there are
four more beyond them, which pass through the other edge of the
cross girders.
The cross girders in some cases rest on the top of the flange, and
are securely rivetted thereto and to the side plates, instead of being
bolted to the under side of the flange as shown.
We will now proceed to determine the sectional areas of the
flanges at the various sections between the centre of the girder and
the points of support. The side plates will be of the same size
throughout, namely, 12 inches deep by 3/4 inch in thickness; the
angle irons also retain their dimensions intact; hence the variations
of sectional area will be obtained by varying the thickness of the
1028
MODERN STEAM PRACTICE.
top and bottom plates of the flanges. The various areas for the
different segments must not be less than 46·84 square inches, 44′96
square inches, 39'34 square inches, 29′97 and 16·86 square inches,
as already determined; hence the diminution of area for each
section from the central ones will be
From 5th segment to 4th segment,
4th
3d
...
""
""
2d
3d
2d
Ist
""
...
...
46.84-44'96 = 1.88 sq. in.
44'96-39'34 5.62
39 34-29'97 = 9'37
29′97 — 16·86 = 13'11
""
This shows the reductions of area allowable to retain the areas
required to withstand the strains on the various segments of the
horizontal members; but it is not practically convenient to reduce
the areas near the piers to so small a quantity as indicated by
theory.
The sections of the top plates for each segment will be as fol-
lows:-
5th segment, two plates, each ...
5% in. thick.
4th
>>
one plate,
...
""
one plate,
3d
one plate,
...
one plate,
2d and Ist,
one plate,
: :
5/8
""
3/8
""
1/2
""
1/2
The gross areas are found by adding the areas of the top plate to
the "constant" area 25.5 square inches, thus—
5th segment,
4th
3d
2d and Ist segments,
...
...
=
25.5+ 22.5 48.00 sq. in.
25°5 + 20°25 = 45°75 ""
25′5 + 15'75 = 41*25
25'5 + 9'00 = 34'50
These are all in excess of the calculated areas as shown:
Areas determined on,
Areas calculated,
""
48.00, 45'75, 41°25, 34°50, 34'50
46.84, 44'96, 39°34, 29'98, 16.86
It may here be observed that the greater the span of the bridge, the
more nearly can the calculated areas be approached; but there will
always be a considerable excess of metal at the points of support.
We will now calculate the cover for the central net area of the
flange plates, the covers for the side plates and angle irons being
subsequently considered. Where the cover plates occur, four rows
of rivets may be used, without reducing the strength of the flanges
below that required. The rivets being 3/4 inch in diameter, and
the plates at the centre together 1.25 inch in thickness, the loss of
area due to the two extra rows of rivets will be equal to 1·875 inch,
ENGINEERING WORKS, ETC.
1029
and it has been shown that the total loss of area on the normal
section at the centre is 7:125 inch, hence where the cover plates
occur the loss will be
7*125+1.875=9 square inches,
and the net effective area for the bottom flange will be
48-9=39 square inches,
the minimum as found by calculation being 37°47 square inches,
thus even here leaving an excess of area equal to
39-37°47=1'53 square inch.
The sum of the areas of the rivets on each side of the line of joint
must therefore be 39 square inches; but the area of each rivet is
0'44 square inch, hence the number of rivets will be
39
0'44
=90.
This would be the number, supposing only one cover for the joints
of the two flange plates; and as the flange plates will be arranged
so that the joints in the two do not come together, the number of
rivets on each half of the cover plate (which acts as a cover to one
main plate only) will be 45, or say 46, giving in each of the outside
rows II rivets, and each of the middle rows 12 rivets. If the rivets
be 4 inches from centre to centre, the length of each cover plate

h
A
8 feet
C
..
A

Fig. 718.-Cover Plates for Flanges.
will be 8 feet. Fig. 718 shows the arrangement of the joints. AA
is the main plate, on which is the cover to the joint at the dotted
line b b. If it is desired to use only the necessary amount of
metal, the top flange covers may be made as shown at C, the number
of rivets there seen being ample to retain the ends of the main
plates in juxtaposition.
Before concluding this important subject we give a design
1030
MODERN STEAM PRACTICE.
D
[ɔ.
of a trellis girder bridge embracing some recent improvements,
Figs. 719-722. In the example shown in these figures all the work


Side Elevation.
E
A
F
Cross Section.
F
F
G
G
G
Plan.
I
H-
A, Trellis girder bridge.
Figs. 719-722.-Trellis Girder Bridge of 200 ft. span,
B B, Piers.
cc, Cross girders at top. D, Arrangement of top flange plating.
E, Arrangement of bottom flange plating. FF, Cross girders for platform. GGG, Plates and short
girders for carrying the rails. H, Compression bar.
A


ENGINEERING WORKS, ETC.
1031
is rivetted, no large pins being required in the ties and struts, and
the cross girders for carrying the platform are laid on the top of
the bottom flange, and securely rivetted to it and to the side plates.
The platform is covered with buckled plates, and then asphalte laid
down. Longitudinal wooden sleepers for carrying the rails are laid
on the top of the cross girders and secured to the short longi-
tudinal girders, which are fitted between the transverse ones and
rivetted thereto.
As already noticed, the lattices formed with the ties and struts
between the bars in tension and those in compression are placed at
an angle of 60° in some, in others they form an angle of 45°. Other
angles, however, are adopted, making the ties and struts of lighter
section, because there are more points of support; thus forming a
trellis girder bridge more approaching the principle of a plain plated
one. As regards economy of construction there is no great dif-
ference, for although less material may be required, this is counter-
balanced by extra workmanship. But we consider a bridge so con-
structed with a number of points of attachment to the main webs
very secure, which is the chief point to aim at in a bridge requir-
ing to carry heavy and rapid-moving loads. The example on
p. 1030 illustrates this mode of construction. The top and bottom
webs have vertical plates securely rivetted to the bottom and top
plates, with angle iron on each side of the vertical and longitudinal
plates, forming a semitubular section; the bars in tension, forming
the trellis work, are quite plain, and are rivetted at the top and
bottom to the outside of the vertical ribs; the compression bars are
formed with a stronger section of iron with a raised bead or half
round at each side, and are strongly braced together, and then
rivetted to the inside of the vertical ribs.
The roadway for two lines of railway is carried on cross girders
placed 4 feet apart, and plates running the entire length are placed
on the top of the cross girders, for the longitudinal sleepers to rest
on.
The cross girders have likewise vertical plates underneath the
sleepers between each pair of girders running the entire length of
the bridge, and rivetted to the girders for carrying the roadway.
Diaphragm plates are placed at each end of the cross girders
between the vertical ribs forming the bottom and top webs, and are
rivetted to the vertical plates with an angle iron on each side.
In order to stiffen the structure curved overhead girders, embracing
the two main girders, are spaced at certain intervals, thus binding
1032
MODERN STEAM PRACTICE.
the mass more firmly together. The floor is composed of 1/4-inch
buckled plating, and is covered over with a layer of asphalte tc
protect the whole surface from the influence of the weather, a very
important point to attend to. The plating for the bottom flange
has three thicknesses, while that for the top flange has four thick-
nesses at middle, tapering in both bottom and top to one thickness
at ends. The rivetting across the bottom and top flanges has four
lines of rivets for single plating, and six lines of rivets for double
plating and upwards.
Light trellis girders are often adopted for foot bridges; these are
very simple in construction, having merely an angle iron at top and
bottom for the longitudinal webs, which are joined together with
plain bar iron, for the tension ties as likewise for the struts; some-
times the girder is slightly curved, and the footway laid with
chequered cast-iron plates fastened down to the cross girders of
angle iron; in other arrangements buckled plates are substituted,
having a thin layer of asphalte, while others have simply boarding
secured to the cross angle iron.
FORMULÆ FOR LATTICE GIRDER BRIDGE.
Distance between the supports 80 feet, divided into thirteen
spaces forming equilateral triangles; depth of girder 5·33 feet, side
of triangles 6'15 feet. Let / be length between supports = 80 feet;
let d be depth of girder=5.33 feet; let ▲ represent side of triangle
=6'15 feet; let w be total load 250 or 500 tons, as the case may
be; let S represent the horizontal strain; let X represent strain on
diagonals or lattice bars, with load at centre, not taking the weight
of the girder, say 250 tons, we have
S =
X
W l
4 ď
4 × 5'33
250 x 80
= 938 tons.
144 tons.
20 4 = 250 x 6·15
Δ
2 d
2 x 5'33
This is uniform throughout the whole length, being alternate com-
pression and tension on the alternate bars.
Uniform load of 500 tons.
S
W /
=
500 x 80
938 tons.
8 d 8×5°33
Thus it will be seen that with the load distributed the girder carries
double the weight.
ENGINEERING WORKS, ETC.
1033
The horizontal strain at any point whose distance from abutment
is represented by r, is found thus:
S =
ลบ
2 dl
(lr-r2).
The strain of the diagonals is expressed by the following for
mula; y is for single triangulation :
W
X =
▲ y.
dl
With load on top of the girder:
X = 500 × 6·15 × 33·82
80 × 5°33
With load on bottom of the girder:
246 tons.
X =
500 × 6·15 × 36′9
80 × 5°33
= 268 tons.
LATTICE GIRDER RAILWAY BRIDGE.
The Plate gives elevations and details of a railway bridge over
the river Ohio at Beaver, which may be considered as a good
example of recent American practice. We subjoin the following
particulars of this bridge.
The bridge is built for a single track, and consists of six spans
of iron trusses across the river, and over 1000 feet of iron viaduct
that carries the railroad across the flats to the bluff on the north
side of the river. The spans are divided up as follows, commencing
on the left side of the Plate:-Span No. 1, 30 feet long, plate deck
girder; span No. 2, 180 feet long, Pratt deck truss; span No. 3, 446 feet
long, double intersection Pratt through truss; span No. 4, 260 feet
long, double intersection Pratt through truss; span No. 5, 230 feet
long, Pratt deck truss; span No. 6, 230 feet long, Pratt deck truss.
Viaduct 30 feet long, 36 spans of plate girder. Making a total of 1376
linear feet of bridge proper and 1080 linear feet of viaduct approach.
The masonry of the piers for the channel span are started from
the bed rock of the river, the bottom of the river being exposed by
the use of coffer dams; that for the other piers in the river was
started on cribs of timber built up to within 2 feet of the low-water
mark. On the south side the abutment and shore pier were built
in the sides of the bluff, and on the north side stone pedestals were
built to receive the legs of the trestles forming the viaduct. Piers
Nos. 1 and 2, carrying the channel span, are 90 feet high above the
1034
MODERN STEAM PRACTICE.
low-water mark, and are 12 feet thick and 30 feet long under the
coping on top; they have a batter of ½ inch per foot on each side
to the foundation courses. Pier No. 3, for the north end of the
260 feet span, is built to the same height as piers Nos. 1 and 2, and
to the same batter. It is 10 feet thick and 28 feet long under the
coping at the top. Piers Nos. 4 and 5, for the 230 feet span, are
built to a height of 60 feet above low water, and are 8 feet thick
and 24 feet long under the coping at top. The cutwaters of all
these piers are protected for a distance of 3 feet on each side, and
from low water to a height of 30 feet above with wrought plates
5% inch thick, with a 6 x 6 angle covering the joints at the cut-
water.
The floor system for the two through spans is formed of iron
beams framed between the vertical posts of the trusses, and longi-
tudinal iron stringers framed between the floor beams. These
stringers receive the 8x8 inch white oak ties spaced 18 inches apart
between centres, upon which are laid the rails. The floor of the
deck spans of the bridge is formed of white oak beams 8 x 14 inches,
also spaced 18 inches apart between centres, to receive the rails.
The floor of the viaduct is of 8x9 inches white oak ties 18 inches
apart between centres. Two lines of white oak guards 7 × 8 inches
placed 18 inches from each rail extend the full length of the bridge
and its viaduct approach. The channel span of 446 feet between
centres of piers is formed of two trusses, placed 18 feet apart
between centres of the double intersection Pratt system, each truss
being divided into 21 panels of 21 feet 1 inch each, making a total
of 442 feet 9 inches between centres of end pins, and is 42 feet
2 inches high between centres of chords. The upper chord is formed
of a top plate-in one plate-42 inches wide, with three lines of
web plates 24 inches deep, all joined and stiffened by eight lines of
4 inch angle-irons. The lower chord is of 8 inch links, with die-
forged eyes for connecting on the pins. The end post is inclined,
and is of similar construction to the upper chord. The inter-
mediate posts are double, each half being formed of an 8-inch
beam, with plates varying from 12 inches to 9 inches wide rivetted
on each flange. These posts are stiffened longitudinally at their
centres by a strut which extends the full length of the bridge, from
end post to end post, formed of two 6-inch channels, stiffened with
straps.
The main and counter ties are in two lengths, the joint being
1
ENGINEERING WORKS, ETC.
1035
formed by means of two splice plates to each line of ties, with pins
to receive the bored eye of the ends of the ties to be spliced. The
main ties, of which there are four at the foot of each post, are of
links varying from 6 inches wide at the ends to 3 inches wide at
the centre of the span; the counter ties are of square bars. The
pins in the upper chord vary from 6 inches diameter to 4 inches
diameter at the centre, while those in the lower chord are all
6 inches in diameter. The pins forming the splice in the ties are all
of a diameter of at least three-fourths of the width of the bars
coupled. The free end of this span rests upon eleven turned rollers
of 3 inches diameter, set in a frame that has a planed base 1% inch
thick. This roller frame at one end and the base plate of the
post at the other end rest upon a dead plate of wrought iron 5 feet
wide and 1½ inch thick, and extending the full width of the pier, to
receive the ends of the adjoining spans.
·
The lower lateral bracing is formed of rods, with nuts on each
end, which are placed between the beams and connected to them
by means of wrought-iron skew backs, to receive the nuts, rivetted
to the beams. The upper lateral bracing is of struts of two 8-inch
channels at the panel points, with rods attached to them by means
of bolts, at their ends: in addition to this upper system there is an
intermediate strut of two 6-inch channels between each of the oppo-
site posts and at the centre of the height of the truss, these being
braced to the top struts by a diagonal system of sway rods 13% inch
in diameter. Each end of this span has a portal formed of a
lattice frame of the half depth of the truss with a stiffened archway
beneath and a plate girder 24 inches deep, with the name of the
bridge punched out of the web, on top. This span was erected on
a temporary bridge of threè equal spans of 135 feet of Howe truss,
rough masonry piers being placed in the river to a height of 10 feet
above low water, upon which a timber pier 55 feet high was built to
receive the Howe trusses.
The 260 feet span is of similar construction to the channel span,
each truss being divided into fifteen panels of 17 feet 1 inch, making
a total of 256 feet 3 inches between centres of end pins, and a
height of 34 feet 2 inches between centres of chords. Rollers of
2½ inches diameter and 1½ inch thick dead plates, similarly to
those for channel span, are at the ends. This span was raised on
temporary trestles of timber resting upon the river bed and extend-
ing to the full height of the piers.
1
1036
MODERN STEAM PRACTICE.
The deck spans of 180 feet and 230 feet between centres of piers
are all of similar construction; the trusses were of the Pratt system,
and were placed 13 feet apart at centres. All these trusses have
a height of 28 feet 3 inches from centre of chords. The upper
chord is composed of a top plate 30 inches wide with two lines of
web plates 18 inches deep connected and stiffened by four lines of
4-inch angles. The lower chord is formed of 6-inch eye bars. The
posts are formed of a 9-inch beam with 12-inch plates on the
flanges, and the main ties of eye bars in two lengths, of 6-inch de-
creasing to 4-inch wide bars. Rollers of similar pattern to those of
the through spans were used for this span also, and dead plates
1½ inch thick, extending across each pier, tied the adjoining spans
together. The lateral system was an upper, lower, and intermediate
system of struts, thoroughly braced together by rods both laterally
and diagonally.
The viaduct portion on the approach was divided into spans
30 feet between centres of trestles, and, with but few exceptions, was
of the uniform height of 60 feet from the ground to the rail.
CONSTRUCTION OF SUSPENSION BRIDGES.
THE CLIFTON SUSPENSION BRIDGE AT THE NIAGARA FALLS.
This structure (Fig. 723), designed and completed by the late
Mr. Roebling, has been now in use for a number of years, and has
fully answered the purpose for which it was designed—namely, to
form a connecting link between the Great Western of Canada and
the New York Central Railroads. It has a clear span of 821 feet
4 inches between the centres of towers. The upper platform carries
a single track having a mixed gauge 5 feet 6 inches and 4 feet 8½
inches, over which the freight and passenger cars and engines of
both roads are continually passing, their speed, however, limited to
5 miles an hour. The lower platform has a double track for the
accommodation of foot passengers and carriages.
This bridge has been designed not for heavy traffic, but for the
accommodation chiefly of foot passengers, for carriages employed by
visitors to the Falls, and for the local traffic between the towns on
both sides of the river. To meet this it was assumed that the
ENGINEERING WORKS, ETC.
1037
ordinary moving load of
passengers and vehicles
passing over the bridge at
any one time would seldom
exceed 50 tons, while on
rare occasions it might rise
to 100 tons. The bridge
has been designed of ade-
quate strength in all its
parts to sustain the greater
load with safety. It has a
single track 10 feet in width,
affording ample room for a pedes-
trian to pass a carriage or sleigh
at any point on the suspended road-
way. From motives of economy
the towers were built of wood, but
they can at any future time be re-
placed by iron or stone, and the
bridge then becomes a permanent
structure.
General dimensions.-The span
between the points of suspension, or
centres of towers, is 1268 feet 4 inches.
The deflection of the cables at centre,
or greatest depression below the
horizontal line, varies from 89 feet
in winter to 92 feet in summer.
The difference of 3 feet is owing to
the effect produced upon them by
the changes of temperature, ranging
through 100° Fahr. The roadway
is suspended at an elevation of 183
feet above the water on the Canada
side, and 188 feet on the New York
side, while the centre, according to
the season, varies from 190 to
193 feet, there being a rise of 4 feet
in the curvature of the bridge in
summer and 7 feet in winter. The

Fig. 723.-Suspension Bridge
at the Niagara Falls.
1038
MODERN STEAM PRACTICE.
tops of the towers being in the same horizontal plane are therefore
105 feet high on the left bank, and 100 feet high on the right
bank. The length of the cables at medium temperature is 1286 feet
between centres of towers, 1828 feet between the anchor pins, where
they are connected with the anchor chains, and 1888 feet in all,
between the anchors embedded in the masonry on either side. The
prolongation of the cables under ground is effected by anchor chains
of Lowmoor iron 30 feet in length, in links of 10 feet each, firmly
built in hydraulic masonry.
Anchorages.—The anchors are of cast iron, 3½ by 5 feet, weigh-
ing upwards of a ton each, pierced for the reception of the anchor
bars, and having deep flanges on the back, against which the anchor
bars are secured by steel pins. They are placed 17 feet below the
surface of the ground, and are embedded in the rock. The whole
is built in with hydraulic masonry, and carefully grouted so as per-
fectly to fill all cavities.
The weight of the bridge and its greatest load (363 tons) will
produce a maximum strain of 705 tons upon the cables and stays,
but one-tenth of this strain is thrown down vertically upon the bear-
ing stones where the cables enter the ground, by virtue of the change
of direction at that point. Hence the greatest pull upon the anchors
cannot exceed 634½ tons, and as this strain scarcely exceeds one-
fourth of the dead weight, or total resistance opposed to it, it is
apparent that the anchorages cannot be disturbed, or in any way
affected, by the greatest tension of the cables and stays.
Load.-The weight of the suspended portion of the bridge
between the towers, including the cables, the roadway, the stays,
suspenders, and guys, is 263 tons net. This constitutes the per-
manent load. The ordinary load, as before stated, is 50 tons, and
the extraordinary load 100 tons. The permanent and moving
load will not exceed 363 tons. This load is supported by the united
strength of the cables and stays.
Roadway.-At the centre the curve of the roadway rises 4 feet
above its chord in summer, and 7 feet in winter, there being a rise
and fall of 3 feet due to the changes of temperature alone. The
chord line is not in a horizontal plane. The end resting on the right
bank is 5 feet the highest, but in so great a span that the difference
is imperceptible.
The two ends of the roadway are fixed to the rock on either side,
but the middle must necessarily rise and fall the 3 feet just stated.
ENGINEERING WORKS, ETC.
1039
The framing had therefore to be adapted to this variation. It is
sufficiently rigid to resist the influence of a moving load, and dis-
tribute it over 100 feet of the platform; but it is not too rigid

Fig. 724.-Platform, side elevation.
to yield fairly to the necessary changes in the position of its
centre.
The platform is wonderfully stiffened by a light, yet strong, reti-
culated truss on either side, 6½ feet deep, going down 2 feet below
the road, and rising 4½ feet above it, forming at the same time a
strong parapet for the protection of foot passengers (Fig. 724).
The floor beams are of pine, 13½ feet long and 2½ inches by
10 inches in the middle, bolted
together in pairs, and sus-
pended 5 feet apart between
centres, the tension bolts pass-
ing down between them (Figs.
724-726). They are notched
upon the lower chord of the
truss which passes under them,
and are fastened to it by screw
bolts. The floor is made of
two courses of Norway pine, 1½ inch thick. Between it and the
floor beams is a series of horizontal braces, which act with the floor
to keep the bridge in line.

Fig. 725.-Platform, cross section.
The upper chord of the truss is 6 inches by 7 inches, made of two
pieces of pine 3 inches by 6 inches, and covered with an oak cap
7 inches by 1½ inch, breaking joints, and bolted together. Ten-
sion braces from the floor beams to this chord serve to keep the
truss in a vertical position (Figs. 724 and 725).
The lower chord is made of pine, 6 inches by 8 inches, in
two pieces of 3 inches by 6 inches, breaking joints, and bolted
1040
MODERN STEAM PRACTICE.
together, and under this a wrought-iron channel bar (Fig. 726),
6 inches by 4 inch, with flanges turned downwards 2 inches
deep, and weighing 30 lbs. to the yard. These
channel bars extend the whole way from shore
to shore. The joints are fished with cover-
ing plates, 15 inches by 5 inches by 3/8 inch,
and eight screw bolts at every joint, the holes
being slotted to allow for the contraction and
expansion of the material. This continuous
connection of wrought iron under the truss
gives it great additional stiffness and tensile
strength, and prevents the stays pulling the
Fig. 726.—Lower Chord and lower chord asunder.

Tension Bolt.
Between the top and bottom chords of the
truss is a series of diagonal braces and vertical tie bolts, binding
the two members firmly together through the oak cap and channel
bar at top and bottom (Fig. 724).
At the middle of the bridge the weight of the cables, which here
descend to the level of the roadway, is brought to bear directly upon
it, and act as an insistent weight to prevent it being lifted by the
wind. At the point of oscillation (Fig. 724) of the two reverse curves
formed by the cables and roadway, the floor beams are screw-bolted
close up to the cables, and at every 50 feet of the 200 feet each side
of the centre a stud or pillar formed of a 2-inch gas pipe inclosing
the suspender is placed between the cable and roadway.
Strength of the bridge.-The cables, as they hung freely between
the towers, before they were loaded with the roadway, formed
a purely catenarian curve;¹ but when the roadway was added,
which in any suspension bridge is much, or many times, greater
than the weight of the cables themselves, their original character
was changed, and under the influence of an equally-distributed load
they assumed the form of a parabolic curve.
The difference between these two curves in deducing the strength
of the bridge is inconsiderable, but in calculating the lengths of
the suspenders it cannot be disregarded. The parabola gives the
readiest means of finding them, and the lines it furnishes approximate
¹ In geometry the catenarian curve is a curve formed by a rope or chain, of uniform
density and thickness, when suspended or allowed to hang freely from two fixed points.
It is interesting on account of the light it throws on the theory of arches, and also by
reason of its application to the construction of suspension bridges.-Ogilvie's Imperial
Dictionary.
ENGINEERING WORKS, ETC.
I041
more nearly to the curve of equilibrium. A foreshortened view of
the bridge, as seen from either bank, brings out the harmony of
these lines in a very agreeable manner.
Strength of the cables.—To find the length of the arc A DB (Fig. 727),
considered as a parabolic curve, if s=half the arc-A C, y=half
the span=A B, and x=the deflection=D C, then accurately
S = Y √ 4 m² + y²
+ m. log€
y + √4 m² + y²
4 112
2 m
the symbol logɛ being the hyperbolic logarithm.
X
By the equation to the parabola, y²=4 mn and 22 =4m, the
parameter. The vertical deflection of the cables at medium tem-
perature is 91 feet, consequently the swayed cables will have an
inclined deflection of 92:22 feet, and the length of the arc must be
measured by this deflection. Substituting the values of x and y in

A
ç
K
Fig. 727.-Diagram of Suspension.
the foregoing formula, i.e. x=92′22, and y=634'17, then S, half the
arc, becomes 643'00, and the whole arc, ADB, is 1286'00 exactly. (1)
Similarly, if the deflection be taken at 90 feet vertical, the swayed
deflection becomes 91°24 feet, and the length of the arc ACB will
be 1285.62 feet exactly.
For a deflection of 92:22 the arc measures
For a deflection of 91°24 the arc measures
1286'00 ft.
1285.62 ft.
The increment of difference o'98 gives increment of arc 038 and
vice versa. (2)
The greatest tension upon the cables being at the points of sus-
pension A and B,
Then,
Let y=half the span=634'17 ft.
x=vertical deflection=9100 ft.
P total weight of cables, roadway, and load equally distributed.
T=greatest tension in cables resulting from this load.
P
T=
4x
√ y²+4x².
66
1042
MODERN STEAM PRACTICE.
By substitution,
P
T=
√ 634*17²+4×91²=P×181.
4× 91
(3)
The factor 181, multiplied into the load P, equally distributed,
expresses the strain upon the cables at the point. In other words,
every ton spread equally over the platform produces a strain of
1.81 ton in the line of the cables.
Strength of the stays.-If 0 be the angle of inclination of the stays,
or the angle at which they intersect the horizontal plane, then their
effect in sustaining a given load varies, as sin. 0, the smaller the
angle the less their effect in giving vertical support; but to com-
pensate for this difference the strength of the stays increases in the
inverse ratio. Three sizes of rope are used, the longest being nearly
thrice the strength of the shortest. The angles vary from 16 to
672°.
As they are applied every one of the forty-eight stays is found,
by the resolution of forces, to possess a lifting power varying from
9 to 14 tons ultimate, or 2 to 3 tons effective strength.
The aggregate strain upon all the stays is represented by the fol-
lowing representative triangle of forces as adduced from the plans:
The sum of all the breaking strains being represented by the
diagonal AC=1344 tons net, the sum of the horizontal thrusts
against the abutments will be represented by the base BC=1148.67
tons, and the aggregate lifting power of all the ropes by the vertical
side AB=628.54 tons. The same proportions will hold good for all
other strains less than the breaking strain. If ABI, then AC=
2'14, and BC= 1.83, let AB represent the entire weight P to be sup-
ported, then the strain upon AC will be 2·14 P.
The bridge is supported by cables and stays.
rately, the cables have to support:
1. Their own weight. By (1)
1286 × 54 × 14
6 x 2000
2. The weight of 634 ft. of the
(4)
Take these sepa-
central portion of the bridge, includ-
ing all the suspenders, the cable bands, tension bolts, and
washers over the whole length of the bridge,
3. The weight of the under floor guys attached to the central por-
tion of the bridge, including 4 ton strain on each guy to keep
it taut,
The weight of the bridle and horizontal stays between the cables,
including the strains upon the former,
4.
...
...
...
Total weight resting on the cables, net tons,
...
81'00 tons.
79'60 tons.
5'00 tons.
2'00 tons.
167.60
ENGINEERING WORKS, ETC.
The strain upon the cables produced by this weight is,
By (3) 167.60 × 1.81 = 303 35 tons
The stays have to support:
303.35
1. Their own weight and attachments,
2. The weight of the landward quarters of the platform, equal to
one-half of the roadway, less the parts resting on shore,
1043
(5)
18.00 tons.
...
65'00 tons.
12.40 tons.
...
95'40
3. The weight of the forty-two guys attached to this portion, and
4 ton strain on each of the inclined guys,
The total weight resting on stays, net tons,
The strain produced by this load is,
By (4) 95'4 × 2*14 = 204°15 tons.
(6)
The calculated strength of the cables has thus been determined.
The manufacturers' rule for ascertaining the strength of the best
quality of charcoal wire-rope heretofore made is as follows:-
If w=the weight of the rope in pounds per fathom, B= its break-
ing weight in tons, then, making all due allowance for the lay,
B = 22.
This rope weighs 54 lbs. per fathom, and its breaking strength
B = 2 × 54 = 108 (tons English) = 120°96 tons (United States).
There is reason, however, to believe, from the superior quality of
the material employed in their manufacture, that the strength of
these ropes is even greater than this. The wire was drawn to a
specified tension of 100,000 lbs. on the square inch, and the registry
of tests shows that, on the whole, they exceeded it. While the
ropes were being made one of the wires was tested by direct weights
and lever power. The gauge was 154 inches, the weight per fathom
376 lbs. It broke with a weight of 19:20 lbs. Since a bar of wrought
10,000
iron, I yard long and 1 inch square, weighs 10 lbs., we have •188
532 wires of this size to the square inch, and the strength of the
wire is 53.2 X 1920 102,144 lbs. per square inch, and the strength
of the rope by this test is
133 X 1920 = 255,360 lbs. =
...
and deducting 5 per cent. for rope making
...
the breaking weight B =
U.S. tons.
127.680
6.384
121.296
It is therefore within bounds to assume that the breaking strain
is at least 121 tons, and, consequently, that the two cables possess
an ultimate strength of 121 x 14= 1694 tons net.
1044
MODERN STEAM PRACTICE.
By the same rule the ultimate strength of the stays at the lowest
estimation is as follows:-
I
Stays.
12
24
12
in. circ.
44
314
3
...
Ibs. per fathom.
English tons.
40
20
II
8
48 stays have an aggregate breaking strength of
Equal to
22
16
...
:-
English tons.
480
528
...
192
1200
1344 U.S. tons.
By (5) the permanent load exerts a strain upon the cables of
5'58
parts, between one-fifth and one-sixth their breaking strength.
By (6) the permanent load on the stays exerts a strain of 6.58
parts, between one-sixth and one-seventh their ultimate strength.
Collectively.
The permanent loads are
The resulting strains are
The breaking strains are
...
On cables.
tons.
167.60 +
On stays.
tons.
tons.
95'40 = 263
303 35+ 204'15 = 507½
1694* +1344′ =3038
I
Being designed for light traffic, the bridge may be considered
safe if the permanent load does not exceed one-fifth, and the per-
manent and moving loads, taken together, do not exceed one-fourth
the breaking weight.
Let P=weight of the bridge, the permanent load.
L=greatest load admissible upon the bridge.
T=the factor of tension on cables and stays produced by P + L.
B=breaking weight of cables and stays.
Then allowing a strain of 25 per cent. of the breaking strain, the
greatest load L -P, and by substitution for cables,
B
4 T
L=
and by substitution for stays
1694
4 × 1·81
· 167·60 66·37 U.S. tons.
L =
1344
4 x 2'14
-
95'40 = 61'37
""
The maximum load on the whole bridge is 127'74
While, therefore, a load of 127'74 tons equally distributed would
not strain the ropes more than 25 per cent. of their full strength,
there can be no question of the sufficiency of the structure to sustain
safely the load of 100 tons, for which it was designed.
Effects of temperature.—It is assumed that under the modifying
influence of the Falls, the greatest cold will not be below zero of
ENGINEERING WORKS, ETC.
1045
Fahrenheit, and the greatest heat will not exceed + 100 degrees by
the same scale. The range of temperature provided for in the
adjustment of the levels and the construction of the roadway was
100° Fahrenheit.
The length of the cables exposed to atmospheric changes is
1800 feet. It is known by experiment that wrought iron expands
0012 part of its length between the freezing and boiling points of
water, that is, between +32° and +212°, equal to 180° of range.
The expansion of the cables for 100° range of temperature is
therefore 100
X 1800 × 0012= 1.20 feet in the whole length.
180
By (2) ·38: 98 :: 120 : 3·09.
That is, the increase of 1.20 in the length of the cables will produce
an increase in the deflection of 3'09 feet, which is the rise and fall
of the bridge due to changes of temperature alone.
Effects of the wind. Every wind that blows rushes into the chasm
crossed by this bridge with redoubled force. Winds that are but
gentle breezes on land strike the bridge with the force of a brisk
gale, and a gale on land becomes a storm on the water. They
crowd through the gorge as through a funnel, with increased velo-
city and power. The bridge is undisturbed by ordinary winds, but
in the course of construction there were severe storms that affected
it to a considerable extent until all the stays and guys were attached
and brought to bear upon it. By these and by the cradle form of
the bridge the lateral force of the wind, tending to produce oscilla-
tion, is at once resisted and checked. The undulations from the
upward pressure of the wind and from transitory loads are also
checked by the stays and guys as far as they reach; and, beyond
this, over the remaining space of 400 feet at the middle, it is
counteracted by the vertical studs placed between the cables and
the roadway.
The prevailing and strongest winds are from the south-west, and
these striking the bridge square upon its beam act with more power
than any other. In a severe storm which strikes the bridge fairly
on one side, the wind will press with a force of 30 lbs. upon the
square foot, and exert a lateral power of 108 tons upon the whole
length of the structure. But the wind passing under the bridge has
always an upward tendency. Then, if the angle of incidence be
taken at 45°, its greatest effect, we find that while the lateral force.
1046
MODERN STEAM PRACTICE.
on the side is reduced to 68 tons (as I to 8 in 45°), it is also increased
by the horizontal resultant of the pressure on the bottom by 140 tons,
and hence the greatest lateral pressure will be 208 tons. To resist
Figs. 728, 729.—Saddles and Rollers
this disturbing force we have: (1) The in-
herent stiffness of the platform fixed at both
ends to the solid rock, and fastened at the
middle to cables weighing 81 tons. (2) The
cradle form of the bridge, the cables and stays
being inclined at an angle to resist any lateral
motion. (3) The weight of the active sus-
pended system, 263 tons. (4) The direct
power of the guys, their united strength on
each side being 280 and 260 tons respectively.
The upward pressure at the small angle of
incidence will likewise be 208 tons. The plat-
form, with the guys attached to it, weighs
150 tons, or 58 tons less than the lifting power
of the wind; but the united strength of all
the guys that hold it down is 460 tons, and
the central half of the cables also presses upon
it, through the studs, with a dead weight of
40 tons.
Cables.-There are two cables, one on each
side of the bridge, descending to the level of
the roadway at the middle, where they are
only 12 feet apart between centres, while at
the towers they are 42 feet apart-the sway
of each cable being 15 feet from the perpen-
dicular. Their vertical deflection at medium
temperature is 91 feet, but in the plane of the
swayed cable it is 92:22 feet. The horizontal
projection of the cables, or bird's-eye view
from above, represents the landward portion
as tangential to the curve between the towers
which is formed by swaying them in at the
centre. The angle of depression from the
points of suspension varies so little on either side of the towers that
the resultant of all the forces in both horizontal and vertical planes
produces only a direct vertical pressure upon the towers,
The sus-
pended system has been so arranged as to exert no lateral strain.

ENGINEERING WORKS, ETC.
1047
upon the towers. When the cables pass over the towers there is
necessarily a movement of nearly 3 inches, arising from atmospheric
changes, but the cables rest in cast-iron saddles which move freely
upon rollers interposed between them and
the cast-iron caps which crown the summit
of the towers, and in this way the irresistible
force of contraction is eluded (Figs. 728
and 729).
Each cable is composed of seven ropes,
each rope of seven strands, and each strand
of nineteen wires, o'155 inch in diameter,
this size being between No. 8 and No. 9 of
the Birmingham wire gauge. There are
133 wires in each rope, and 931 wires in each
cable. The ropes are 2 inches in diameter,
74 inches in circumference, and weigh
54 lbs. to the fathom. The calculated break-
ing strain of one of these ropes is 121 tons
of 2000 lbs. The guaranteed breaking
strain was 100 tons gross, equal to 112 tons
net, and they bore a test of 108 net tons
fracture, the fastenings having given way
under that strain.
When a solid rope of this kind is sub-
mitted to a dead pull, the central strand
being straight, while the others are spirally
arranged about it, it is the first to feel it,
and would, were they all alike, be the first
to break; and, therefore, the central strand
is made of soft wire, while the others are of
hard wire. The softer wire having greater
ductility, will stretch until the surrounding
strands are brought to full tension, and they
will then all pull evenly together.
All the ropes were manufactured in Eng-
land, and on testing gave 96½ per cent. of
the guaranteed strength. It was desirable,

そ
​Figs. 730, 731.—Yokęs.
however, if possible, to find a mode of fastening that would give
100 per cent. of the strength of the rope. With this view experi-
ments were afterwards made at Clifton on the Canada side of the
1048
MODERN STEAM PRACTICE.
river. One end of the rope was fastened into a wrought-iron socket,
and the other into a cast-iron yoke, and in every case the end
fastened in the socket was the first to give way. The result was
entirely in favour of the yoke. The yoke is simply an elongated
eccentric (Figs. 730 and 731), the least diameter of which is about
twice the circumference of the rope, and the length about three
times the diameter (ie. 16 by 48 inches). There are two holes at
the upper enlarged end—one of which is cylindrical, and of the
same size as the rope; the other conical, into which the end is
fastened. The rope is passed through the cylindrical hole, then
round the eccentric in a hollow groove, and then fastened in the
usual manner in the conical socket.
It may be interesting to know how this was done. The end of
the
rope being in the first place pulled 6 inches through and above
the conical hole, every strand and single wire was opened out and
arranged, so that from 1% to 2 inches of each wire could be bent
and doubled quite back, and inwards to the centre. This done,
power was applied to pull the end by main force, aided by pound-
ing with a wooden maul back into the socket, leaving the end flush
with the top. Iron points-some long, some short-were then
driven in between the wires until the socket was quite full, and made
to ring like a piece of solid metal. Lastly, the top was leaded as a
protection against the weather.
The point of attachment being eccentric, and near to one side of
the yoke, falls directly in line with the rope, as soon as it is sub-
mitted to strain. The eye of the yoke is slotted to allow of a move-
ment of 6 inches for adjusting the ropes. It is obvious, from mechan-
ical considerations, that if the fastening in this socket is only 25 per
cent. of the strength of the rope, the rope must fairly be broken
before the fastening will give way. But since fully 96% per cent.
can be counted on, as decided by the former test, it is quite impos-
sible for the fastening to yield before the rope breaks, and therefore,
by adopting this plan, the full strength of the rope can be relied
For suspension bridges more especially, the importance of
this device cannot be overrated. The ropes were adjusted at the
centre with great facility by means of the slot, and with perfect
confidence in the unyielding nature of the fastenings at either end.
upon.
At the anchorage the ropes are connected with the underground
anchor chains by means of adjusting links of 4 feet, 8½ feet, and
13 feet in length, of a uniform section of 6 by 1 inches (Fig. 732).
ENGINEERING WORKS, ETC.
1049
Three of the yokes are in the direct line of tension, two are thrown
down, and two up, in order that all the ropes may be gathered into
cable form and clamped as near as possible to the point of attach-
The sectional area of the two cables is 37.8 square inches;
ment.

Fig. 732.—Anchorage.
that of the anchor chains 84 square inches. The aggregate force or
ultimate strength of both cables is 121 × 14=1694 tons; that of the
anchor chains 84 × 32 = 2688 tons net.
The wires were made by a new process of sufficient length
(1910 feet) for the ropes, without weld, joint, or splice. The rods
were rolled from billets by one operation in less than a minute.
Billets weighing 140 lbs., 15 feet long and 134 inch square, were
heated to a white heat in a gas furnace, and passed through a series
of rollers set close to the furnace, until they were gradually reduced
to rods of No. 3 Birmingham wire gauge. One end of the billet
was in the furnace while the other was being wound upon the reel.
The rods were then drawn through three holes down to the required
size-0.155 inch diameter. As they were required to bear a tensile
strain of 100,000 lbs. to the square inch before breaking, tests were
made from time to time as they were run off, and a daily register
kept of the results. By this register it appears that while a few of
the wires fell short of the specified strength, nearly all of them ex-
ceeded it. Some of them were drawn to so high a degree of tension
as 120,000 lbs. as determined by direct weights and lever power,
while by the hydraulic test it was much greater.
Stays. Apart from their important functions of stiffening the
roadway, and preventing undulations and oscillations, the stays are
a real support to the bridge. They form, as it were, two rigid and
powerful brackets extending out from either shore, and carry one
1050
MODERN STEAM PRACTICE.
half its weight and one half its distributed load. While they relieve
the cables of half their duty, the two systems are so arranged as to
work in harmony, the primary object of the construction being so
to combine these two independent systems as to make them act in
concert the moment a load comes upon the bridge.
There are twelve stays on each quarter, forty-eight in all, reaching
half way to the centre, and supporting one half of the suspended
roadway. They are carried back to the anchorage and secured there
in the same manner as the cables, and to the same anchors, save as
regards the means of adjustment, which for the stays is effected at
the other end by means of a nut and screw (Fig. 733). The longest
stay is tangential to the curve of the cable at the point of suspension.
Fig. 733.-Platform showing Stays.
The rest fall within this angle, and are attached to the platform at
intervals of 25 feet. They are of various sizes, according to position
and the strain they have to bear. The three outermost stays are
made of 44-inch rope of 45 tons ultimate strength, the next six
of 34-inch rope of 25 tons strength, and the last three of 3-inch
rope of 18 tons strength. The whole of the twelve ropes on each
quarter are united with seven landward ropes that are bound up in
one cable and reach from the anchorage to the towers, over which
they are carried by a saddle and rollers independently of the cables
(Figs. 728, 729). The three longest ropes pass over the towers un-
broken from the anchorage to the suspended roadway—the next six
ropes are yoked or coupled to three of the largest ropes on the river
side of the towers-and the last three are joined to one of the largest
ropes on the same side. The cast-iron yoke is used at both ends
of the stays. The aggregate strength of the whole of the stays,
forty-eight in number, is 1344 tons net. By the resolution of forces
1

ENGINEERING WORKS, ETC.
105 1
this affords 628½ tons of vertical lifting power.
120 tons of wire
ropes were used in forming the cables, and only 25 tons in making
the stays, both carrying an equal load. I ton of stays is equal in
effect to nearly 5 tons of cable. Four stay braces of 3-inch rope
are placed horizontally between the cables, binding them together
above the roadway to keep them from swaying about, and four
bridle stays are attached to the cables, extending from the rock at
the base of the tower to a distance of 110 feet out upon the cables,
serving to check vibrations under a moving load.
Suspenders.—The suspenders are made of wire ropes 5% inch
diameter, 2 inches in circumference, and 10 tons ultimate strength.
Being placed 5 feet apart, there are 480 suspenders, of 4800 tons
aggregate strength, which is more than ten times the load they have
to sustain. The ends are crowned in wrought-iron sockets, con-
necting above to cable bands, and below to the tension bolts that
pass through the floor beams and hold up the bridge. Towards the
middle of the bridge, where the suspenders are short, all of less than
12 feet in length, they are made of solid rods of Lowmoor iron
¾ inch in diameter. All the tension bolts are terminated by a
screw 6 inches long, to admit of adjustment (Fig. 726).
Guys.-The overfloor stays, by virtue of their inclined position,
have a very good effect in preventing any lateral movement in the
suspended roadway, but the underfloor guys offer a more direct
resistance to it. These guys are made of the same size rope as
that used for the suspenders, and are attached to the cords by
`ring bolts (Fig. 733). Altogether they contain a reserve power of
540 tons, and offer a resistance of 260 tons to the force of the
wind whichever way it blows; and yet to all appearance they
are mere gossamer threads, scarcely visible to the naked eye.
(See Fig. 723).
Towers. On each side of the river are twin towers, constructed
of white pine of superior quality. Each tower presents the outline
of a truncated pyramid, 28 feet square at base and 4 feet square at
top. They are placed 13 feet apart at base, and the roadway passes
between them. They are 105 feet high on the Canada side, and
100 feet on the New York side. They are built up of four timbers
12 by 12 inches in each corner of the pyramid, with a space of 1 inch
between the timbers for ventilation, through which the connecting
bolts pass, and suitably braced. The lower ends of these timbers.
are stepped into cast-iron shoes, having cells for the reception of
I
1052
MODERN STEAM PRACTICE.
each post.
The shoes are set in the solid rock in beds cut out fairly
to receive them at right angles to the direction of the post.
The sixteen posts all come together at the top, where they are
crowned by a heavy cast-iron cap, having sixteen cells on the inner
side to receive them individually, and deep flanges on the upper side
forming channels for the reception of the saddles and rollers which
carry the cables and stays. The timbers break joint with each other,
and are firmly bolted together, and wrought-iron plates inch
thick and central dowels are inserted in every butt joint. The posts
are so firmly built and braced as to warrant them being considered
in detail as short square struts or pillars having a breadth of base
equal to one-fifth their height, and therefore not liable to bending
under a heavy load.
The crushing force of white pine being about 5000 lbs. to the
square inch, or 2½ net tons, the weight required to crush down one
of the towers will be 132 × 32 × 2½=10,560 tons, or forty times the
weight of the permanent load it has to carry. The effective
strength of pine is estimated at one-tenth of its crushing force, and
10560
hence the towers should be able to bear safely a load of =1056
tons.
EAST RIVER BRIDGE, NEW YORK.
IO
The following are some details, as given by the Scientific
American, of the suspension bridge now building to connect New
York and Brooklyn, and which has the largest span as yet actually
carried out.
The bridge is designed to carry three kinds of load: the outside
roadways being for waggon traffic, the middle one for a promenade,
with the railway tracks on either side of it and between it and the
roadways.
The total weight of metal in this bridge in round numbers is 1000
tons. Of this 1,658,279 lbs. are wrought iron, 82,092 lbs. steel,
27,440 lbs. steel pins, 146,891 lbs. cast iron. The width of the
bridge over all is 88 feet, length on the longest side 206 feet, length
of longest truss 198 feet 5 inches, length of shortest truss 163 feet
10 inches. The outside roadways will be 16 feet 7 inches wide
between fenders, the two railroad ways will be 12 feet each, the
promenade 17 feet 7 inches wide.
The following are the principal dimensions of the bridge:-
Size of New York caisson, 172 × 102 feet.
Size of Brooklyn caisson, 168 × 102 feet.
ENGINEERING WORKS, ETC.
1053
Timber and iron in caisson, 5253 cubic yards.
Concrete in well holes, chambers, &c., 5669 cubic feet.
Weight of New York caisson, about 7000 tons.
Weight of concrete filling, 8000 tons.
New York tower contains 46,945 cubic yards masonry.
Brooklyn tower contains 38,214 cubic yards masonry.
Length of river span 1595 feet 6 inches.
Length of each land span 930 feet, 1860 feet.
Length of Brooklyn approach, 971 feet.
Length of New York approach, 1562 feet 6 inches.
Total length of bridge, 5989 feet.
Width of bridge 85 feet.
Number of cables, 4.
Diameter of each cable, 1534 inches.
Length of each single wire in cables, 3578 feet 6 inches.
Ultimate strength of each cable, 12,200 tons.
Weight of wire, 12 feet per pound.
Each cable contains 5296 parallel (not twisted) galvanized steel, oil-coated wires,
closely wrapped to a solid cylinder 1534 inches in diameter.
Depth of tower foundation below high water, Brooklyn 45 feet.
Depth of tower foundation below high water, New York 78 feet.
Size of towers at high-water line, 140 × 59 feet.
Size of towers at roof course, 136 × 53 feet.
Total height of towers above high water, 278 feet.
Clear height of bridge in centre of river span above high-water, at 90° Fah.,
135 feet.
Height of floor at towers above high water, 119 feet 3 inches.
Grade of roadway, 34 feet in 100 feet.
Height of towers above roadway, 159 feet.
Size of anchorages at base, 129 × 119 feet.
Size of anchorages at top, 117 × 104 feet.
Height of anchorages, 89 feet front, 85 feet rear.
Weight of each anchor plate, 23 tons.
OTHER LARGE-SPAN BRIDGES.
THE FORTH BRIDGE.-This bridge will consist of two main
spans of 1700 feet each, two of 675 feet, fourteen of 168 feet, and
six of 50 feet, and is really a continuous girder of 5330 feet. The
two main openings are spanned by a combination of cantilever and
lattice girder, that is to say, the form is such that from the piers a
triangular framework projects outwards on either side, the ends
of which are connected by a lattice girder. The projecting can-
tilevers are each 675 feet in length, whilst the girder between them
is 350 feet. The smaller openings are spanned by lattice girders;
the material is to be steel, of which about 42,000 tons are calculated
to be required for the main spans alone.
1054
MODERN STEAM PRACTICE.
THE DOURO BRIDGE, near Oporto. This is the largest ex-
ample of an arch rib bridge yet constructed. The central span is

Figs. 734, 735.—Elevation and Plan of one half of
Central Span of Douro Bridge.
520 feet, and the height of rails to water surface is 201 feet. The
weight of central opening is 727 tons, of which 504 are in the curved
arch part alone. Fig. 734 shows one half of span of the great arch,
and Fig. 735 plan of same.
ACTION OF WIND ON BRIDGES AND CHIMNEYS.
Considerable difference of opinion exists among engineers as to
the pressure exerted by the wind upon exposed surfaces, as in many
cases it appears that anemometer registrations are misleading. The
late Professor Rankine, however, in his Engineering Manuals clearly
lays down the necessity of designing all lofty and exposed struc-
tures to be able to withstand a wind pressure of 55 lbs. to the square
foot, and that this value had been obtained from anemometer
registrations at Glasgow Observatory, and since then confirmed by
the fall of chimneys and other structures.
Recently and following upon the investigation into the cause of
the fall of the Tay Bridge, a scientific and engineering committee
have recommended 56 lbs. as the wind pressure to be allowed for
per square foot of exposed surface.
ENGINEERING WORKS, ETC.
IC55
TABULATED STATEMENT OF SOME BRIDGES OF LARGE SPAN.
Bridge over the Dee, at Chester
Hammersmith Bridge, over Thames
Suspension Bridges.
Arched Bridges, W. Arched Bridges,
& C. Iron and Steel. Stone and Brick.
Truss Brdgs.
Girder or
London Bridge, over the Thames
Gloucester Bridge, over the Severn
Waterloo Bridge, over the Thames
Maidenhead Bridge, over the Thames
Douro Bridge
St. Louis Bridge, over Mississippi
Coblentz Bridge, over Rhine
Southwark Bride, over Thames
Sunderland Bridge, over Wear
Severn Valley Railway Bridge, Colebrook Dale Railway
Victoria Bridge, over Thames
East River Bridge, in course of construction for connect-
ing New York and Brooklyn
Clifton Bridge, over Niagara
Cincinnati Bridge
Niagara
Fribourg
Bridge-Road and Rail
Bridge
Clifton Bridge, over Avon
Pesth Bridge
Menai Bridge
Union Bridge, over Tweed
Cincinnati (Southern Railway) Bridge
Kuilenberg Bridge, Holland
Cincinnati
Louisville
Bridge over Weichsel at Dirschau, near Dantzig
Bridge over the Rhine, at Cologne
Royal Albert Bridge, Saltash, over Tamar
Tubular Britannia Bridge, Anglesea .
Bridges. Conway Bridge
Victoria Bridge over the Wear, Durham Junction Railway
Form or
Description.
Circular Arch.
Do.
Material.
No. of
Spans.
Span.
Rise of
Arch.
Depth of rib
or Voussoir.
Soffit above
High Water.
Sandstone.
I
Do.
4
H*
200 ft.
42 feet.
4 feet.
160
""
Elliptical Arch.
Granite,
5
{ce
Centre 152,,
72
37½
37/2,,
"
2 140,,
2
130,,
Do.
Sandstone.
Do.
Granite.
Do.
Brick in Cement.
··
Circ. Braced Arch
Steel.
HON H
I
150,,
35
9
Each 120,,
32
""
2
128,,
244
525,
130
>>
Centre 520,,
Do.
Do.
Do.
50
3
""
Sides 502 >
"
Wrought Iron.
3
Each 314",
28
>>
Circular Arch.
Cast Iron.
3
24
"
23
Side
:
Do.
Do.
I
Do.
Do.
Do.
Wrought Iron.
4
+ HH
""
34
I
nect-}
Suspension
Steel Wire.
3
Sides
Centre 240,,
210
236
200,,
Each 175 ››
Centre 1,600,,
900",
20
>>
17 ft. 6 in.
Deflection of
Chain.
128 feet.
4 ft. 9 in.
4 ft. 6 in.
5 feet.
5 ft. 3 in.
33 feet.
12
""
10 ft. 9 in.
6 feet.
5
3 ft. 6 in.
29% feet.
27/2
24/2
""
75 feet.
28
:
""
Suspension
Iron Wire Cables.
I
1,268,,
92
►
Do.
I
Do.
Do.
Iron Wire Cables.
Do.
I
Do.
Wt. Iron Bar Links
Do.
Do.
HHHHH
обо
1,060,,
821
::
I
I
I
870,,
702,,
666
63
"
70 ""
::::
Do.
Do.
I
Do.
Rods of Round Iron
I
..
Do.
Wt. Iron Bar Links
HHH
579,
43 ""
449,
30
""
I
422,,
29
Truss.
I
517",
Wt. Iron & Steel.
420,,
400,,
Lattice Girder.
Wrought Iron.
6
Each 397??
Do.
Bowstring
Tubular.
Do.
4
Each 322 ft. 6 in.
Do.
2
Each 445 ft.
Bow andChain.
Do.
Do.
Do.
2 H
I
493 ››
Each 459,
400,
">
Depth of
Girder.
65 ft. 8 in.
38 ft. 6 in.
27 ft. 2 in.
56 feet.*
30,,
ft. 6 in.
25
* Of this 29 feet is rise of how,
27 feet drop of chain.
::
100 feet.
103 ››
18
"

1056
MODERN STEAM PRACTICE.
MARINE AND SUBMARINE WORKS.
SUBMARINE TUNNELS.
Subaqueous tunnels laid on the bed of the sea have been pro-
posed to effect direct railway communication between England and
France. Our study of the matter has led us to the belief that a
metallic and concrete structure is best adapted for the purpose.
There should be an inner and outer tube, well trussed together and
filled in with concrete, inclosed in a metallic casing of a horse-shoe
pattern; this could be made in sections, and run down on a carriage
or wheels fitted to the mass, and then lowered into soffits. A
hydraulic joint should be made between each section, by means of
a packed metallic ring pressed up with set screws against a ring
of india rubber let into a recess formed on the end of the adjacent
tube. The temporary bulkheads fitted at the ends of the sections
could then be removed, and the two parts firmly rivetted together,
and so on until the whole length was laid down. The ventilation
of such tunnels could be easily effected by means of pneumatic
tubes, drawing the vitiated atmosphere from the centre of the
tunnel, the exhausters being placed at the mouths of the tunnel,
and fresh air flowing in from each end.
In driving submarine tunnels under the bed of the sea across
such a channel as the Straits of Dover, a shaft must be sunk at
each end; this is necessary to ascertain the geological strata from
shore to shore. The bed of the channel must also be bored to
ascertain as far as practicable whether there are any breaks. From
the bottom of these shafts the inclines landward are greater than
under the bed of the channel; the latter being only intended for
drainage, 2 feet per mile is considered enough. Any water met
with flows down the inclines to the bottom of the shafts, where
it is pumped to the surface by pumping engines. The two starting
points at the bottom of the shafts being determined on, the exca-
vations are commenced at each end; and if the work is carefully
and equally carried on the two headings should meet at mid
channel.
In the trial works which have been lately carried out, a passage
7 feet in diameter has been excavated for about 2000 yards beneath
the channel. The boring machine consists mainly of two cross
ENGINEERING WORKS, ETC.
1057
3
16
arms fitted with teeth and making two or three revolutions per
minute. At each turn about of an inch was removed from the
chalk. The machine was worked with compressed air, and the
excavated material removed by a moving bucket apparatus some-
thing like the bucket arrangement of a marine dredger.

B
B
મ
Fig. 736.-Section of Single Tunnel with Brickwork Lining.

B
C
B.
Fig. 737.-Section of Proposed Twin Tunnels with Brickwork Lining.
AA, Ventilating pipes. B B, Ventilating pipes carried up at the middle of the tunnel. c, Drainage
subway.
In ordinary cases the double line of rails is contained in a single
tunnel (Fig. 736); but we consider that twin tunnels, each having
a single line of rails (Fig. 737), would be much more cheaply
executed, owing to the excavations and building material being
much less than for a single tunnel containing two lines of railway.
There have been various plans proposed for driving the tunnels.
In the twin system the excavation would be driven on the long-
67
1058
MODERN STEAM PRACTICE.
wall principle, that is to say, a division wall would be left in the
chalk or other material cut through. We would recommend lining
up as the work proceeds; the lining material being either brickwork
as shown, or cast-iron tubbing, grouted between the cast iron and
the chalk. With the twin system there should be crossings running
right and left, joining the two tunnels, and placed at about 1 mile
apart, so that the trains could shunt from one tunnel to the other
when occasion required.
Both at the Mersey and Severn extensive tunnelling operations
are in progress for carrying the railway under these rivers.
The Severn Tunnel is about 8000 yards in length, of which about
one-half are below water. The tunnel passed through sandstone
and shale, strong springs being met with. It is 26 feet wide, and
is lined with brick in cement from 2 to 3 feet thick.
The Mersey Tunnél extends about 1300 yards below the river,
and is excavated through the new red sandstone. Two shafts were
sunk to a depth of 180 feet, and the works carried on from these
points. As much as 4500 gallons of water per minute have been
raised from one of these shafts. The whole length of tunnel,
including inclined approaches, is nearly 4000 yards. The lining was
brick in cement.
In the Hudson Tunnel at New York two single-line tunnels were
used, 30 feet apart and over one mile in length.
LIGHTHOUSES.
When we can secure a good foundation for a lighthouse on the
rock, there can be no doubt that a stone edifice is a safe building,
resisting the force of the waves from generation to generation.
There are, however, many places where we cannot get such a foun-
dation, and we must therefore have recourse to other modes of con-
struction. Lighthouses should have a bold appearance by day,
and if possible an electric light by night, and it is absolutely neces-
sary that the light should be placed at a sufficient elevation. We
know that the waves become powerful only when resisted, and that
a lighthouse depending on its weight, and not on its strength of
fixtures, which are very liable to deteriorate, is the best means of
resisting the enormous force of the waves. Such a structure should
present the least surface or point of attack, for if it divides the wave
it thereby lessens its force.
ENGINEERING WORKS, ETC.
1059
Various well known stone-built lighthouse towers have been
placed on dangerous reefs around our own coasts. The first of these
was the Eddystone, built in 1756-59, from designs by Smeaton.
This lighthouse replaced one of timber, which was consumed by fire
in 1755, and which, in its turn, had replaced one also of timber,
erected by Winstanley in 1696, and overthrown in a storm in 1703.
Smeaton adopted stone as his material, and so proportioned the
structure and dovetailed the stones together that the building has
stood till the present time, and has only been now replaced by a
new tower, 130 feet high, erected in 1881, from designs by Sir J. N.
Douglass, M.Inst.C.E., and engineer to the Trinity House, London.
The necessity for the new tower arose from the rock itself giving
way where Smeaton's lighthouse was erected.
The general form of these stone towers is curved, a vertical
longitudinal section giving more or less a parabolic outline.
Fig. 738 shows a design proposed to be carried out in iron and
concrete to meet the difficulty experienced in foreign waters of
working stone blocks. It is a bad plan to build on the sand; but
where we cannot obtain a better foundation than that offered by
a sandy or gravelly bottom, we must lay down a base of sufficient
area, so that the great weight necessary may be distributed over a
large surface. Of course the nature of the soil will determine the
size of the basement. For a depth of 16 feet or so of water we will
presume that a square of 80 feet would be sufficient for the base-
ment. The main column or central pillar would be continuous,
built up from the bottom to the requisite height, while there would
be cylinders ranged all round, carried up from the bottom of the
basement to the top of the platform; they would be all secured one
to another at the bottom, and the basement built round them with
suitable metallic plates, securely jointed together, and made per-
fectly water tight, the space between the columns being filled in
with concrete. The structure could be erected in shoal water, say
to the height of the platform, and buoyed up and towed to its
destination by pontoons. In some instances, however, the pontoons
could be dispensed with, as the columns would be perfectly water
tight, having sufficient buoyancy of themselves. When brought to
its destination the structure could be sunk on a level bed by admit-
ting water into the columns, sluices being provided for that purpose,
and then the water would be gradually pumped out, and the
columns filled up with concrete, as likewise the platform, which will
тобо
MODERN STEAM PRACTICE.
form a ring placed on the top of the columns. By this means

0
0
0
0
0
0
Fig. 738.-Proposed Cast-iron Lighthouse.
a foundation of great weight, strength, and stability could be laid
down in moderate depth. It would then merely be a work of time
ENGINEERING WORKS, ETC.
1061
erecting the main column, with all the necessary staircases, apart-
ments, &c.
In the case of a lighthouse erected in a moderate depth of
water, the waves would not rise to a great height, so the height from
the level of the sea to the under side of the platform need not be
more than is really required, as the waves would be broken up by
the columns; while the space inside of the platform ring would be
left open as far as practicable; having merely girders joining the
main columns and platform together. Such a form of lighthouse
provides an ample promenade for the keepers, instead of their being
always confined in a tower as in the usual form of structure.
SWING BRIDGE AT LEITH DOCKS.
This bridge (Fig. 739) has a clear span of 120 feet, the roadway
having a double line of rails for railway traffic, and being also suited
for the passage of horses, carts, and other road vehicles, as well as for
foot passengers. The bridge rests on a massive block of masonry and
Portland cement concrete about 50 feet square, carried down to the
solid clay, 26 feet in depth below high water of spring tides. The
fore end rests on a masonry pier, also carried down to the clay and
connected by an arch to the quay wall. The depth of water at this
point is about 18 feet; the headway under the bridge is 4 feet, and
the level of the road and rails is 6 feet above high water.
The bridge is constructed of wrought iron and timber. The dis-
tance from the centre of motion to the fore end is 147 feet and to
the tail end 67 feet, giving a total length of 214 feet at the centre
line. The main girders consist of two massive trusses about 212
feet long, and 27 feet deep at the centre of motion, decreasing
towards the ends to a depth of 7 feet. These girders are each 2 feet
in width, and spaced 24 feet apart, carrying a flush roadway for a
double line of railway, as well as for carriage traffic between them.
Footways, each 5 feet in width, are carried by cantilevers outside.
the main girders, making the total width of the bridge 39 feet over
all. The main girders are formed of open box-shaped upper and
lower booms, connected together with triangulated bracings of great
strength and stiffness, in order to resist the heavy blows to which
the bridge may be subjected from vessels drifting against it. The
booms are 2 feet wide and 2 feet 6 inches deep, made up throughout
of two side plates 5% inch thick, and one top or bottom plate 3/4 inch
1062
MODERN STEAM PRACTICE.

thick, connected together by two
angle irons, 5 inches by 5 inches by
I inch, rivetted with 1 inch rivets at
4 inches pitch. Two additional top

୪୪:୪
о о
O o O
Od
Od
Fig. 740.-Section of Boom.
or bottom plates ½ inch thick are
added over the bays at the centre of
motion, thus making the maximum
gross sectional area 97 inches for
each boom. The side plates of the
booms are stiffened by diaphragm
plates at every 5 feet, composed of
1/4-inch plates and 3-inch by 3-inch
by 3%-inch angle iron rivetted be-
tween them.
The triangulated bracings, most
of which act both as struts and ties
F
2.30
F
7.4...
Fig. 741.-Section of Triangulated Bracings.
under different conditions of load,
consist of H beams, varying accord-
ing to position from 16 inches to
24 inches wide, and 5% inch thick,
Fig. 739.—Swing Bridge at Leith Docks.

ENGINEERING WORKS, ETC.
1063

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Plates.
743.-Covering
Figs. 742,
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1064
MODERN STEAM PRACTICE.
connected by diaphragm plates varying from 4 inch to 34 inch
thick, and four angle irons varying from 3 inches by 3 inches by
3/8 inch to 4 inches by 4 inches by ½ inch. The diaphragm plates
are perforated with oval holes to give a light appearance to the
bridge. The side plates of the bracings are flush with those of the
booms, to which they are connected by 5%-inch covering plates and
1-inch rivets (Figs. 742, 743).
The roadway is carried on cross girders with longitudinal trim-

ว
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О
со
O
о
O
о
Ü
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O
O
O O
O
O O
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O
Fig. 744-Section of Cross Box Girder.
ming girders between them. The cross girders of a box section are
2 feet deep, with webs 3% inch thick; top plates I foot 6 inches wide,
and 7% inch thick, and bottom plates 2 feet 2 inches wide, and 3/4 inch
thick, all connected together with angle irons 4 inches by 4 inches
by 5% inch. These box girders are spaced at 20-feet centres, and

C
C
C
Fig. 745.-Joining of the Longitudinal Girders with the Cross Box Girders.
securely rivetted between the lower booms at every vertical trian-
gulated bracing by angle irons, knees, and gusset plates. Between
ENGINEERING WORKS, ETC.
1065
these cross girders four longitudinal girders are rivetted, one under
each rail, 18 feet 6 inches long by 1 foot 9 inches deep, consisting of
3/8-inch web plates, top and bottom bars 7 inches by ½ inch, and

O
O O O
оо
Fig. 746.-Section of Footway.
angle irons 3 inches by 3 inches by 3% inch. At the tail end of the
bridge the lower booms are connected by a number of cross girders
to carry the counterweight. Horizontal diagonal bracing bars,

ARCHED
GIRDER
O
1
Fig. 747.-Cross Section of Bridge.
4 inches by 3/4 inch, are rivetted across the whole roadway, which is
laid transversely with 4-inch Memel planking, covered longitudinally
with 2-inch green-heart slabs.
1066
MODERN STEAM PRACTICE.
The footways (see Figs. 746, 747) are carried on cantilevers of
1/4-inch plate in the web, and angle irons 3 inches by 3 inches by
½ inch, rivetted to the outside of the lower beams, and spaced 10 feet
from centre to centre, those at the tail end of the bridge being
deeper and heavier, and plated over on the outside to contain
kentledge for the counter-weights.
The hand railing is formed of gas tubes, 2 inches
and 1½ inch respectively, fitted and keyed to strong
wrought-iron stanchions forged from bars 4 inches by
2 inches, spaced 6 feet 8 inches from centre to centre,
which are bolted to timber curbs and angle irons, and
stringers connecting the ends of the cantilevers. The
planking of the footway consists of 2-inch Memel Fig. 748.-Section
planks bolted to the curbs.
of Arched Girder.
The main girders are connected together at the top by a system
of diagonal bracing and struts; the latter (see Fig. 747) consisting of
seven arched girders of plate and angle iron, spaced 20 feet from
centre to centre, giving a headway of 16 feet 3 inches at the centre

k....
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Fig. 749.-Upper Cross Bracing.
line of the bridge. The diagonal bracing consists of tie rods 2 inches
diameter, tightened with double nuts on wrought-iron palms securely
rivetted to knee gussets attached to the triangulated bracings.
The bridge is counterweighted with about 240 tons of kentledge,
ENGINEERING WORKS, ETC.
1067
closely packed between the cross girders at the tail end, and inside
the tail end of the girders themselves, which are shaped to admit of
a large stowage for this material between the side plates.
The total weight of wrought iron in the bridge amounts to 320
tons, and the timber to 60 tons, which, with the 240 tons of counter-
weight, makes the gross weight 620 tons.
The bridge is carried on a pair of heavy cross-box lifting girders,
each 29 feet long by 3 feet wide, by 4 feet 6 inches deep, laid side
by side at the centre of motion. On the under side of these girders
is bolted a cast-iron bearing plate 7 feet square, having a convex
under side cast to a radius of 32 inches, fitting into a concave surface
on the hydraulic ram of the lifting press by which the bridge is
worked; by this means the bridge swivels on a ball and socket, the
fore part being raised and the tail end depressed by the counter-
weight. The ram, which is 66½ inches in diameter, works in a cast-
iron cylinder 34 inches in depth and 6 inches in thickness, resting on
a granite block 7 feet square by 3 feet thick. The bridge turns
entirely on this water centre, rollers being dispensed with. On the
admission of water to the cylinder at a pressure of about 700 lbs.
per square inch the bridge is lifted 3 inches at the centre, the fore
end rising 7 inches, and the tail end bearing lightly on a couple of
rollers 30 inches in diameter, travelling on a radial tramplate, the
object being to steady the mass in swinging.
The turning machinery consists of a pair of hydraulic rams,
14 inches in diameter, and 10 feet 6 inches stroke, working in
cylinders placed underneath the bridge between the centre of motion
and the tail end. The turning chain passes over double sheaves
from one of these rams to the other round a wrought-iron ring
25 feet in diameter, rivetted to the under side of the lifting-box
girders for carrying the bridge. By this means the bridge is turned
either up or down stream at the pleasure of the man in attend-
ance, the levers for opening the valves being placed at a point
on the coping of the bridge pit at the tail end of the bridge. The
time occupied in lifting, turning, and lowering the bridge does not
exceed two minutes; the friction being reduced to the minimum by
means of the mass resting and turning on a water centre.
The hydraulic pressure is obtained from the engine house of the
adjacent dock; but a hand force pump is provided in the bridge pit
for lifting the bridge in the event of any interruption in the hydraulic
supply from the accumulator. This hand pump is so arranged that
1068
MODERN STEAM PRACTICE.
Resting Blocks
ROAD
Emd
AND
RAIL
LEVEL
Under side of Bridge
I
"
་་
"
་་
"
"
་་
41
Press
·
Tinting
ong for Newer a
LIFTING
GIRDERS
各
​"
་་
་་
#1
LIFTINGLAós.
Centre of Main Giräer
"
it can also be applied for working the bridge should any accident
befall the central lifting press. By means of two presses 20 inches
in diameter, one under each main girder at the tail end of the

וי
་
LYLINDERN
Grain
Centre Line
Thain
ress
bridge, the weight can be taken off the resting blocks at this point,
and upon their removal the counterweighted end of the bridge would
sink down, raising the fore end clear off its bearings, and so allow-
GIRDERS
ERS
Centre of Main Girder
•
་་
་་
་་
1
•
"
"
་་
་་
"
་་
་་
LIFTING
•
1
--
་་
01
10
Ashlar
Coping
1
11
"
Fig. 750.—Turning Gear for Swing Bridge at Leith Docks.
ENGINEERING WORKS, ETC.
1069
ing the bridge to be turned round by capstans or other hand power.
The tail rollers are enabled to sink below the level of the tramplate
by means of two small hydraulic presses 5 inches in diameter, con-
trived so as to allow the bridge to droop as already described.
CONSTRUCTION OF TUBULAR WROUGHT-IRON
CRANES.¹
These cranes are composed of wrought-iron plates rivetted
together, and so arranged as to give the back or convex side an
adequate degree of strength to resist tension, and the front or con-
cave side, which is of cellular construction, a corresponding power
to resist compression. The form is similar to that of the prolonged
neck of the bird, tapering from the point of the jib to the level of
the ground; from this point it again tapers to a certain distance
below the surface, and terminates in a cast-iron shoe forming the
toe on which the whole revolves. The lower or concave side, which
has to resist a force of compression, consists of plates forming three
cells, and varying in width in the ratio of the strain; and the con-
vex or top side, which has to bear the pull or tension due to the
suspended weight, is formed of long plates connected together by
a system of chain-rivetting. The sides are of uniform thickness
throughout, the joints being covered with T iron internally, and on
the outside with strips or covering plates.
The form of jib, together with the point at which the load is sus-
pended, is probably not the most favourable for resisting pressure,
but the crane nevertheless exhibits great powers of resistance. It
may be considered as a curved hollow beam having one end im-
movably fixed, the load being applied at the other, and viewed in
this light, the strength is easily determined from the formula
W=cad;
where w is the breaking weight at the end of the jib in tons; C the
ultimate resistance of wrought iron to compression in tons per square
inch; a the sectional area of the lower or cellular flange in square
inches; d the depth in inches; and the horizontal length or sweep
of the jib in inches: the strength being supposed to be limited by
the resistance of the lower or cellular flange to compression.
1.
¹ Abridged from a paper by Sir Wm. Fairbairn in Trans. Inst. Mech. Engin. 1857.
1070
MODERN STEAM PRACTICE.
Six small-sized cranes which were erected at Keyham Docks at
Devonport are of the following dimensions, and were calculated to
lift a weight of 12 tons to a height of 30 feet from the ground; each
of them was intended to sweep a circle of 65 feet diameter, so that
the projection of the jib was 32 feet 6 inches from the centre of the
stem; and the extreme height 30 feet above the working platform;
the point of the jib is 2 feet deep and 18 inches wide, and the jib
increases to the level of the ground, where it is 5 feet deep and
3 feet 6 inches wide; from this point it tapers to a depth of 18 feet
below the surface, terminating in a cast-iron shoe. From the pre-
ceding formula it is found that it would require a load of 63 tons to
break one of these cranes.-The following table gives the results of
progressive experimental tests of the strength of these cranes:-
DEFLECTION OF TUBULAr WroughT-IRON CRANES.

Deflection at End of Jib.
Load at End of Jib.
No. 1.
No. 2.
No. 3.
No. 4.
No. 5.
No. 6.
Tons.
2
in.
in.
in.
in.
in.
in.
*32
*31
*37
*25
*27
*3I
3
*50
'50
45:
*65
•62
turned round,
88
*90
·87
.87
*75
'90
.87
·87
*75
8888888
•82
88
.89
6
1'05
I'06
7
8
I'20
1.18
I'35
1.37
9
I'50
I'50
ΙΟ
I'70
1.68
I'70
I.62
I'62 1'76
turned round,
1.85
1.87
1.80
1.62 1.67
1'76
""
II
2'05
2'05
12
2'22
2.19
13
2'40
2'40
14
2.60
2.62
15
2.80
2.80 2.69
turned round,
2.80
2.86 2.69 2.56 2.68
2:56 2.63
2.31
2'31
16
3'00
3°00
HH
78
17
3'20
3°31
18
19
3'50 3'50
3*73 3.69
20
turned round,
3'97
3'97
3'92 3'56 3'56 3*62
3'92 3'56 3'56 3.62
3'75
3'75
In the construction of cranes, whether of wood or iron, it has been
the usual custom to place the jib in an inclined position at an angle
of about 40° or 45° with the stem, so as to obtain the greatest
strength; in this position the extreme point from which the load is
suspended has to be stayed or held in its place by oblique or hori-
zontal tie rods.
ENGINEERING WORKS, ETC.
1071
DESCRIPTION OF SIXTY-TON CRANE ERECTED AT KEYHAM
DOCKYARD.
This crane consists of a rectangular wrought-iron tube, curved to
a radius of about 46 feet, and tapering uniformly from 9 feet deep
by 5 feet 6 inches wide at the level of the ground, where, from the
leverage of the crane, the strain is the greatest, to 3 feet 6 inches
deep by 2 feet wide at the point of the jib. It is also tapered
downwards to about 1 foot 8 inches square at 23 feet below the
level of the platform, where it fits into a cast-iron shoe B (Fig. 751),
working in a socket or step on which the crane revolves. The
point of the jib is 60 feet above the level of the platform, and
sweeps a circle of 53 feet radius; so that it can lift the heaviest load
perpendicularly from a mean distance of 37 feet from the quay wall,
and to a height of no less than 85 feet above low-water mark, and
land it at 69 feet from the edge of the quay.
The crane itself is built on precisely the same principle as a
tubular bridge, and may indeed be considered as a curved tubular
girder inverted, the top side being the front or concave side of the
crane, and the bottom side forming the convex or back part of the
structure. Hence it may be described as composed of back plates,
side plates, and cell plates.
The back plates. CC, which correspond with the bottom plates of
a tubular girder, having to resist a strain of tension, are made as long
as possible to avoid joints, and are carefully chain-rivetted. They
are 3% inch thick, and each half the width of the crane. Taking
those on one side and beginning at the top of the well, the
first plate is 13 feet 9 inches long; the second which passes the
point where the downward taper ends and the upward begins, is
13 feet 6 inches long; the next is 12 feet 6 inches, followed by six
others, each 12 feet long, and these again terminated by a plate
15 feet long, which curves round over the pulley at the extreme
point of the jib. These plates are covered externally by a long
strip 8 inches broad and 3% inch thick, extending the entire length
of the crane and covering the longitudinal joint between the back
plates. The cross joints are placed alternately, and at each side of
the crane there is a line of angle iron connecting the back plates CC
with the side plates DD; so that the sectional area of the back of
the crane subjected to tension is
1072
MODERN STEAM PRACTICE.
At the bottom,
At the platform,
...
...
square inches.
10'50
27.75
12'00
At the point of the jib,
The sides of the girder are formed of plates 3 feet broad at the
outer edge or back of the crane, rivetted together with T iron 4× 2
x inches at every joint inside, and a strip outside, to give the

I.
C
A
A
A
C
E
H
W
H
Fig. 751.-Wrought-iron Cellular Crane. Plan and Sectional Elevation.
5
necessary rigidity. Beginning at the toe, the first three plates are
inch thick; the next three inch; the next five, which have to
resist the horizontal thrust against the cast-iron circle at the top
edge of the well, inch thick; and the remainder inch thick.
16
ENGINEERING WORKS, ETC.
1073
16
The front of the crane is constructed with four cells to resist the
immense strain of compression to which that part is subjected. The
construction is shown in the sectional elevation and the transverse
sections, Figs. 751-754. The two series of plates EE and FF, which
form the front and back of the cells, are composed of plates varying
from 5 feet to 7 feet 6 inches long, and inch thick. Each of these
plates is rivetted by two angle irons to the side plates D of the crane;
the front plate EE projecting beyond the side plates D, and the
intermediate plates FF being placed within the tube thus formed
at a distance of 12 inches from the front plate E E, so as to divide
the tube into two. The narrow space between the plates E E and
F F is further subdivided into four cells by three vertical plates G G,
parallel to the side plates D D (Fig. 753). Eight angle irons connect
the plates G G with the plates EE and F F, and further strengthen
the structure thus formed. The reason of this arrangement is that
wrought-iron plates from their flexibility offer but a small resist-
ance to compression in the direction of their thickness, as they bend
or buckle with a comparatively small force. The five vertical
plates, however, which form the sides of the cells, are placed in the
position in which they offer a maximum resistance to compression,
namely, with their width or depth in the direction of the strain; and
the angle irons and the plates EE and F F serve to keep them in
position and give great rigidity to the structure. The centre plate
G of the cells is inch thick, and the two remaining plates inch
thick. The sectional area of the concave or front part of the
crane subjected to compression is therefore-
16
At the platform,
At the point of the jib,
...
...
...
62.58 square inches.
34.83
4
1
Attached to the back of the crane is a tail piece H, or box of wrought
iron, containing cast-iron weights acting as a counterpoise to the jib.
The chain I is attached to the crane by a bolt and nut at the point
of the jib, and passes round four pulleys, two movable and two fixed
in the end of the jib; it is then conducted down in the interior of
the jib over three rollers K K to the barrel L, which is also in the tube
near the ground. On each side of the crane a strong cast-iron
frame is fixed for receiving the axles of the spur wheels and pinions.
Four men, each working a winch M of 18 inches radius (Fig. 752),
act by two 6-inch pinions upon a wheel N, 5 feet 334 inches diameter;
this in its turn moves the spur wheel 00, 6 feet 8 inches diameter, by
68
1074
MODERN STEAM PRACTICE.
*
means of an 8-inch pinion, and on the axle of the former the chain
E F

W
E
B
H
R
T
S
Fig. 752.—Wrought-iron Cellular Crane. Vertical Section through Platform and Well.
barrel L, 2 feet in diameter, is fixed. Hence the advantage gained
by the gearing will be—
W
Р
18 × 63.75 × 80
6x8x12
=
=158;
or taking the number of cogs in each wheel
W 18×95 × 100
Р
12 × 9 × 10
158;
and as this result is quadrupled by the fixed and movable pulleys,
the power of the men applied to the handles is multiplied 632 times
ENGINEERING WORKS, ETC.
1075
by the gearing and blocks. A break wheel P, 5 feet 2 inches dia-
meter, is fixed on the other end of the spindle of the spur wheel N;
and the power applied at its circumference is accordingly multiplied
about 100 times by the gearing and blocks.
At the level of the ground the crane is firmly fixed in a strong

S
S
о
E
G
C
S
W
•
S
W
M
W
H
V
Figs. 753, 754.—Wrought-iron Cellular Crane. Plans at Roller Path and Chain Barrel.
cast-iron frame R, the outer edge of which is a circle 11 feet 3 inches
diameter; and on the edge of the well a similar ring ss is embedded
in the masonry and secured by long holding-down bolts, leaving
a space of 10 inches all round between it and the inner ring R.
In this space a number of strong cast-iron rollers TT are placed,
1076
MODERN STEAM PRACTICE.
10 inches in diameter, to prevent friction and facilitate the move-
ment of the crane as it revolves round its axis. Upon the cast-iron
ring SS on the quay wall is fixed a circular rack U U, composed
of cogged segments bolted together, into the teeth of which a small
pinion works, whereby the crane is made to revolve. This pinion
is worked by a worm and wheel v placed in the counterpoise box H;
and two men are sufficient to move round the crane with 60 tons
suspended from the extreme point of the jib. In working the crane
the men stand upon a cast-iron platform w attached to it a few
inches above the level of the ground.
This crane, taking it altogether in regard to strength, height,
and the extent to which the weight raised can be swung round, is
probably one of the most powerful yet erected. It can raise
boilers out of or lower them into the holds of ships of the line;
pick up the heaviest ordnance from any of the decks; and ship or
unship masts with the same or greater ease than is now done
by the large shears used for that purpose in any of the dock-
yards.
There is, however, in these cranes a serious practical difficulty to
contend against, namely, they are not easily inspected internally.
Rapid corrosion of the plates, chains, &c., sets in, and if not kept
properly painted, serious accidents may occur. To facilitate inspec-
tion, the sides of the jib, &c., have been formed in lattice work
instead of solid plating, and the machinery placed outside as in
ordinary arrangements, by which means all the working parts are
in view, and more easy of access. In many of these cranes steam
engines are fitted for hoisting, with a separate engine for turning
round the crane.
ARRANGEMENT OF A FORTY-TON CRANE.
The following arrangement of a forty-ton crane slightly differs
in form from the preceding examples. The concave side of the
jib was plated similar to the convex or top side; but we certainly
consider the cellular arrangement is better calculated to resist com-
pression, although it affords no ready means for inspection and
occasional painting. The top and bottom sides were strongly united
together with diaphragm plates rivetted with angle irons to the top,
bottom, and sides of the jib. In other respects this crane is much
similar to the curved examples.
ENGINEERING WORKS, ETC.
1077
WHEELS, &C., FOR FORTY-TON CRANE.
Diameter at Pitch Line. Breadth.
Pitch.
Large spur wheel,......
Diameter of Shaft.
8 ft. 23% in.
8 in.
3 in.
Pinion for do.
74 in.
I ft. 0½ in.
8 in.
Second spur wheel,
3
in.
33/4 in.
4 ft. 2% in.
5½ in.
24 in.
Pinion for do.
334 in.
o ft. 10 in.
5½ in.
21/4 in.
24 in.
Two steam engines, 6½ in. diameter of cylinders, stroke 9 in., with 40 lbs. steam.
PORTABLE STEAM CRANE.
A twenty-ton portable steam crane has recently been erected at
Glasgow Harbour, by Messrs. George Russell & Co. of Motherwell.
Its weight is 103, or with ballast 150 tons, and its height from
ground level to top of spur wheel and feed tank 25 feet.
The jib
is 50 feet long, of malleable iron plates of box section, and its radius
is variable by steam power. The chain barrel is 2 feet 3 inches
diameter. The central post is a malleable' iron forging, 2 feet
diameter, upwards of 7 tons in weight, on which the revolving
portion swings or revolves. The carriage which supports the whole
is of malleable iron plates, 1½ inch thick, and 4 feet deep. It is
mounted on sixteen wheels, four at each corner of the carriage, with
double compensation levers of malleable iron, so that each wheel
is self-adjusting to meet irregularities in the ground level, and also
balance the pressure equally. The length of the wheel base is 21 ft.,
so that the total weight of the crane is distributed over a large
area. The eight wheels nearest the edge of the water bear directly
on the granite kerb, and the eight inner wheels on a grooved rail-
way. Steam power is applied for moving the crane along the quay
to suit the various steamers by a pitched chain. By the arrange-
ment of the carriage just described, the pressure on each wheel or
point of support is no more than the two smaller cranes which are
ranged one on each side of it. The crane lifts 20 tons at a radius
of 30 feet, or 16 tons at 35 feet. The engines have two cylinders,
each 9 inches diameter and 13 inches stroke. The boiler is vertical,
and has a tank for feed-water above it and surrounding the chimney.
CRANES FOR TIPPING COAL WAGGONS, MASTING, ETC.
Fig. 755 shows a form of crane used for tipping coal waggons.
The waggon is first run on to the cradle, and is then hoisted; prior
to that, the tipping chain is attached to the cradle, taking the back
of the waggon, and keeping it in its position on the cradle; when
1078
MODERN STEAM PRACTICE.
the waggon is raised to a proper elevation to clear the side of the
ship the tipping chain is tightened by means of a small winch
attached to the main framing of the crane, and the crane is slewed

1
round with suitable bevel gearing worked off the upright shaft for
driving the general machinery. The hoisting gear may then be
thrown out, and the waggon lowered by means of the brake. In
the act of lowering, the back part of the cradle is held up with the
#
Fig. 755.—Side and End Elevations of Twenty-ton Steam Crane for Tipping Coal Waggons. By Hawthorns & Co., Leith.
ENGINEERING WORKS, ETC.
1079
tipping chain, and the front descends until the weight of the
coals opens an end door in the waggon working on hinges, and
the coals thus fall into the hold of the ship. The crane is then
turned round, and the cradle lowered to receive another loaded
waggon, and so on.
The motive power of this class of
crane is a horizontal engine placed
underneath the roadway, and on
the engine shaft bevel or mitre gear
drives an upright shaft, on which is
placed pinions working into wheels
for the hoisting and turning gear.

་་
"
01
"
"
"
**
Fig. 756.-Crane for Masting and other Purposes.
By Taylor & Co., Birkenhead.
The crane and machinery
turn on a pivot secured to
the masonry, and at the foot
of the jib two radial bevelled
wheels are fitted to the main
framing, working on a circu-
lar track which is likewise
bevelled to suit the wheels;
thus the arrangement re-
sembles an ordinary turn-
tableupon which all the parts
of the crane are fitted. The crane is likewise arranged so that it
can be worked by hand as occasion may require.
The boiler house is quite independent of the machinery, and
can be placed in any suitable position at a considerable distance
from the cranes; the steam pipes being led to the various cranes
underneath the roadway, and it is evident that any number of
cranes can be working from one set of boilers, depending of course
on their power.
Fig. 756 shows a crane differing from the foregoing in carrying
1080
MODERN STEAM PRACTICE.
the boiler and machinery on the same turntable. It was erected
by Taylor & Co. of Birkenhead, and is principally used for masting
purposes, as likewise for lifting heavy weights into and out of steam
vessels. This crane is nearly all made of wrought iron. There are
two tubular jibs, spreading out at the bottom and contracted at the
top, strongly trussed together with diagonals for the entire length.
The stud on which the crane rotates is securely held down with
a number of bolts and plates passing down to the bottom of the
foundation, and is fitted with radial rollers between the stud and
top washer. The bearings for the radial wheels of the turntable are
placed immediately under each jib, the thrust given through the
jibs is taken on the bearings directly. The crane is provided with
two lifting chains, taking two movable pulleys. Each hoisting chain
and barrel is separate, whilst they work simultaneously. The boiler
is of the vertical description, and is placed well back on the platform.
SEVENTY-TON STEAM CRANE.
The Plate illustrates a crane erected at Victoria Basin, Dundee,
by Messrs. James Taylor & Co. of Birkenhead. Its lifting power
is nominally 70 tons, the test load being 90 tons, but the makers
have no fear of putting 100 tons on it.
The crane will deposit its load a clear distance of 40 feet from
the face of the quay wall, or 56 feet from the centre of the pedestal
of masonry on which it is fixed. The head of the jib is 60 feet
in perpendicular height from the coping of the pedestal.
The main features of construction are in the arrangement, by
which the centre post common in cranes gives way to a central pin,
only subject to direct upward tension, the whole crane acting as
a lever to raise it vertically. The fulcrum is the ring of sixty rollers
running on the cast-iron and steel roller race on the top of the
stonework, eight or nine of which at a time take the thrust at the
foot of the jib, and constantly changing as the crane revolves, and
the resistance is the weight of the masonry secured by six massive
radiating holding-down bolts by which the central pin is anchored.
The hoisting is effected by two barrels winding simultaneously
the two ends of the chain, which from the barrels lead to pulleys on
the jib head, thence drop to and rise again from the gin block, the
middle or loop of the chain being on a fixed compensating pulley
hung fast close below the jib head. The gin block weighs 4 tons.
ENGINEERING WORKS, ETC.
1081
The winding barrels are grooved right and left, by which an even
distribution of strains on the crane framing is secured. There are
three speeds of lift, besides a separate crab with a single chain for
light lifts up to 10 tons. The hoisting engines are a pair of vertical
direct-acting engines with cylinders 10 in. diam. and 16 in. stroke.
The revolving is effected by a pair of smaller independent hori-
zontal engines. The boiler is a vertical one, very large in propor-
tion to the work to be performed, and is fed by an injector. All
the valves and levers are easily within reach of one engine or crane
driver. Wrought iron is principally used throughout.
FIVE-TON STEAM CRANE FOR SHIPS.
Steam cranes are largely used on board ship for loading and
discharging cargo. The crane post is fastened to the deck plank-
ing, and may be carried down to the lower deck and firmly secured
thereto. The chief feature in the arrangement shown (see Figs.
757-760) is that the post is hollow, and acts as the steam pipe for
the engines; with this end in view the top pivot on which the crane
turns is stepped into a socket secured to the side frames, and is
provided with a stuffing box and gland; by this means a stop cock
can be placed at the top of the socket, which revolves with the
crane and has a hole in communication with the hollow post, so that
the steam can be put on or shut off at pleasure. The pipe in con-
nection with the boiler is jointed to the post underneath the deck,
thus making a very snug arrangement. The engines are of the
trunk description coupled directly to a cranked shaft, two cylinders
with cranks at right angles being adopted; with this arrangement
the engines are under perfect control. The cylinders are bolted to
the ring between the frames, the ring being truly bored out to fit
a turned part on the post; at the bottom of the ring there are two
snugs cast with hole and pin for the bottom end of the jib, while
the top end is secured to the framing with a back stay for each
frame, having a roller for the chain fitted to the back stays.
These cranes have sometimes double eccentrics and link motion
fitted for each valve, while others have fast eccentrics only, so set
for lifting the weight; while it is lowered by throwing out of gear
the engines and lowering with a brake wheel. The turning gear
is worked directly off the crank shaft with mitre wheels turning
a vertical shaft, having a pinion at the lower end working into a
1082
MODERN STEAM PRACTICE.
wheel fitted to the large flange for securing the crane to the deck
planking.

These cranes are likewise arranged so that they can be worked
by hand at pleasure.
Figs. 757-760.—Elevations and Sections of Five-ton Steam Crane for Ships. By Hawthorns & Co., Leith.
ENGINEERING WORKS, ETC.
1083
WINCHES FOR SHIPS.
The winch is another form of crane which is extensively used
It is arranged for loading or discharging cargo,
on board ship.
lifting and hauling weights
where the ordinary form
of jib crane is not appli-
cable, and it may also
be used for hoisting the
sails; in fact, where a rope.
can be led and a snatch
block applied, this form of
crane is invaluable. They
are generally fitted with
double eccentrics and link
motion; with such the
engines can be driven at
a high velocity, and in an
instant the motion can
be reversed; thus great
expedition is attained in
loading or discharging

cargo.
The arrangement shown
in Figs. 761, 762, con-
sists of two side frames,
which are firmly secured
to a bed plate on deck;
the cylinders, one on each
frame, are arranged for
overhung cranks. The ver-
tical motion of the piston
rod is attained by means
of a prolongation of the
rod working through a bush
fitted to the side frames;
this necessitates a forked
Figs. 761, 762.—Side and End Elevations of Steam Winch with two Speeds and Hand Gear. By Hawthorns & Co., Leith.
connecting rod; in others the connecting rod is plain, taking
a crosshead which works in suitable cast-iron guides fitted to the
cylinder end, thus making a very efficient and compact arrangement.
1084
MODERN STEAM PRACTICE.
For hoisting purposes in loading or discharging cargo the usual
chain barrel is used, with the chain passing upwards to a block.
secured overhead to a boom or otherwise. In addition to the chain
barrel, surging heads are fitted to the ends of the shafts for the first
and second motion; thus a few coils of a rope passing round the
"surging head" at once obtains a means of communicating lifting
or hauling power to any part of the vessel.
The boilers for these crane engines are generally of the vertical
description, placed on deck, or any other convenient place between
decks, or in the engine room, the chimney being led into the main
funnel. The boiler is likewise suitable for providing steam for the
small auxiliary pumping engines, for feeding the main boilers,
washing the decks, &c.
1
STEAM FIRE ENGINE.
1085
STEAM FIRE ENGINE.
The ordinary fire engine is simply a kind of force pump, in which
the water is subjected to pressure sufficient to raise it to the required
height. The first application of steam power to this engine was
made many years ago, and the steam fire engine is now a recog-
nized part of the outfit of every large fire brigade.
In the Plate are shown an elevation, plan, front view, and section
of a single-cylinder Steam Fire Engine capable of throwing 350
gallons of water per minute to a height of 160 feet, constructed by
Messrs. Merryweather and Sons of London. In the boiler of this
engine, the water is inside the tubes, which, as will be seen, hang
down into the fire box, thus exposing the whole of the tube-heating
surface to the action of the fire. Steam can thus be raised to the
working pressure of 100 lbs. in eight or ten minutes after lighting
the fire; while the consumption of fuel is small, a boiler of this
design evaporating 10 lbs. of water for I lb. of coal. Safety from
explosion is also secured, for if allowed to run short of water, the
fire will be extinguished by the escape of steam from the tubes,
which act as fusible plugs. The burnt tubes can readily be replaced
by others dropped into the tube plate and tightened with a hammer.
None of the working parts of the engine are attached to the
boiler. The engine is horizontal and direct-acting, and being fixed
on a strong iron frame is very rigid. The frame is made of Low-
moor iron or steel, well stayed and pivoted over the fore car-
riage; and the weight is equally distributed over the four wheels.
The stroke of the piston is long and the speed moderate, such a
speed of working alone being required to raise the maximum
amount of water. The piston rod is in one piece, having the steam
piston at one end and the pump piston at the other. In the centre
of the rod is keyed a light crosshead carrying a brass clip which
glides along and gives a rocking motion to a slightly twisted bar,
and this again imparts a reciprocating motion to a lever, which
actuates a single slide valve, so arranged that a fixed action
places it in such a position as to close the steam inlet and exhaust
ports when the main piston is at the end of its stroke, and when
this is done the stroke of the piston valve is completed by steam
so as to open the reverse steam and exhaust ports. This valve
motion works with great regularity; and the speed of the engine can
1086
MODERN STEAM PRACTICE.
be regulated from I up to 160 or more double strokes per minute.
The pump is direct and double-acting, and is made in one solid
gun-metal casting. The valve openings are clear, so as to pass
anything that may come up the suction way; the piston is small
and self-lubricating. The pump is frost-proof, and draws water
from a depth of 30 feet; and owing to the long stroke and moderate
speed of engine, it always fills. Air vessels of copper are fitted
on the delivery and suction ways.
Water is supplied to the boiler by a direct-acting feed pump,
which can either take its supply from the main pump or from a
separate source. There are other arrangements for supply: as, by
the opening of a single cock, when the whole contents of the main
fire pump can be passed direct into the boiler at each stroke; or
by means of a portable hand pump, which fits to the blow-off cock
of the boiler with a short piece of hose and a back-pressure valve;
or by an injector, which is fitted on the boiler for the purpose.
The engine is provided with accommodation for the driver,
stoker, and firemen, bunkers containing about two hours' supply
of coal, and stowage-room for the necessary hose and accessories.
In the larger forms of three-cylinder arrangement of steam fire
engine as constructed by Messrs. Shand, Mason, & Co. of London,
the engine is placed in front of the boiler, and in a horizontal or
inclined position, so as to distribute the weight more evenly over
the framing. The boiler is of the water-tube class, having the
tubes arranged in separate layers, each layer at right angles to
the one immediately above or below it, and inclined so as to insure
a circulation of the water. The engine consists of a set of three
direct-acting pumps on the bucket and plunger principle, worked
by the same number of steam cylinders, the whole firmly fixed to
the boiler. The following table gives the results of experiments with
engines made by this firm from 19 to 120 indicated horse-power:—
Water Pressure.
130 lbs.
140",
Size of Jet.
7/1
15//
18
16
•
140",
140,
150 ",
150",
160
160
140",
165
""
140",
Vertical Height.
130 ft.
150,,
Gallons per minute.
200 gallons.
260
""
I"
1 //
I
16
150",
260
""
160
""
350
""
1 //
11"
190,,
160
450
""
350
195",
450
11"
2-11"
1 3//
I
16
21"
....
240,
210
220
230,
600
""
900
1000
·
""
1350
""
GAS ENGINE.
1087
The use of the steam fire engine has been extended to river and
harbour work, the apparatus being carried on steam boats specially
arranged. A recent example of large floating fire engines is one
built for the Brazilian government. The propelling engine and fire
engine are supplied from the same boiler, which is of the inclined
water tube form. The engines are designed to deliver the water at
a pressure of 220 lbs. per square inch. A speed of ten miles an
hour was obtained on trial, and steam was raised to 100 lbs. per
square inch in less than ten minutes. The vessel is made of steel,
and measures 51 feet long by II feet broad.
GAS ENGINE.
Gas engines have of late years been brought to considerable
perfection, and have proved most useful and economical. The
principle upon which they depend for their action is the expan-
sive force of a mixture of gas and air when burned or exploded;
and the plan most in favour at present, is to compress an explo-
sive mixture of gas and air into a chamber behind the cylinder,
and thereafter fire it behind the piston by means of a gas jet. The
proportions of this mixture are about 1 of gas to 12 of air.
The most successful of several different types of explosive gas
engine has been that of Otto, which is silent and effective in its
working. Recently another form, known as Clerk's, has been intro-
duced. The principal difference of these apparently is that the
former engine has the explosive action taking place only once in
every two revolutions, whereas in the latter the explosion takes
place at each revolution. A heavy fly wheel is necessary in both
cases to ensure regularity of motion.
In both these engines a great advantage is derived from the com-
pression previously of the mixture of gas and air, thus rendering
the combustion more gradual as the piston moves forward. The
temperature of the exploded gas is very high, probably about
2800° F., and it is believed that about one half of the heat is lost
through conduction to the outside of the cylinder. The pressure
ranges from over 200 lbs. at beginning of stroke, to about 30 lbs.
at end of stroke. The consumption of gas appears to be about
22 cubic ft. per indicated horse-power for a six horse-power engine,
but it is expected that this may be much reduced in larger engines.
1088
MODERN STEAM PRACTICE.

--BORE--SUPPLY-PIPE-
inch pipe
to supply
water vessel.
K
WATER LEVEL
Ball tap to keep the water level
always above the top of upper
circulating pipe.
[60 REV $ PER MIN.
C
Fig. 763.-Side Elevation of Otto's Silent Gas Engine-3 horse-power.
PHS
2". EXHAUST
PIPE
H
C
PIPE
TO SLIDE
A
LIGHTS
IBORE PIPE TO CYLE
A A, Gas pipe.
B, Air mouth.
cc, Circulating water pipes.
D, Gas bag.
HH, Stop and drain cocks.
1, Stop cock to regulate supply
of
gas at starting.
K, Water reservoir.
I'BORE GAS PIPE
GAS ▼ BAG
20 LIGHT
DRY GAS METER
GAS ENGINE.
1089
There is no doubt a great future for engines worked in this
manner, greater economy being secured by the use of an inferior
kind of gas.
From a calculation made by Professor Kennedy,¹
from the results obtained by a two horse-power Otto engine, it
appears that the-
Foot-lbs. Per cent.
} 11,000
•
Mechanical equivalent of heat due to the complete combustion
of the gas used per (effective) stroke is about
Work done per (effective) stroke, by diagram
Mechanical equivalent of heat discharged
•
not accounted for
2,050 = 18.6
3,250 = 29'5
5,700 = 51'9
Actual efficiency of engine
2050
I 1000
= 0.186.
Maximum temperature in cylinder (about) 1900° Fahrenheit.
Maximum efficiency which could be attained by a perfect engine working between
the same limits of temperature (say 80° and 1900° F.)=0.77.
Ratio of work actually done to work which could have been done had the engine
0.186
been a perfect one, = 0'241 or 24'1 per cent.
0.770
Fig. 763 is a side elevation of a 3½ horse-power "Otto" gas
engine, the following details of which have been supplied by the
makers, Messrs. Crossley Brothers:-A A, Gas pipe for the slide
light, for exploding the gas in cylinder. B, The air mouth,
coupled as shown below the cylinder. CC, Circulating water
pipes, 14 inch bore, for cooling the cylinder, the inlet connected
for cold water to the bottom of water vessel, and the outlet for
hot water to the top of water vessel. The upper of these pipes
must slope upwards at every point, and have no sharp elbows.
D, A gas båg to give regularity to the supply required. H H, Stop
and drain cocks on bottom or inlet circulating pipe, the drain cock
being put as near the cylinder as practicable. They are for use
when cylinder jacket requires emptying. I, A cock to prevent gas
pressure from causing too much gas to go into cylinder when turn-
ing by hand at starting. K, Water reservoir for supplying circulat-
ing pipes to keep the cylinder cool.
Mr. Clerk, in explaining the action of his engine, says: "The
general action of the engine was this: in a cylinder moved a
piston which served simply to take in the gaseous charge, and at
the proper time to force this charge into the motor cylinder, dis-
placing at the same time the products of the previous combustion.
This cylinder-which he called the displacer cylinder-took into it
for two-thirds of its forward stroke an explosive mixture of gas and
See Minutes of Proceedings of Inst. of Civil Engineers, vol. Ixix. part 3.
2 Ibid.
69
1090
MODERN STEAM PRACTICE.
air; the gas was then cut off, and air alone admitted for the remain-
ing third. The cranks of the displacer and motor cylinders were
so arranged, that when the motor piston began to pass over annular
parts at the out-end of its stroke, the displacer piston was moving
in. As soon as the pressure in the motor cylinder had fallen to
atmosphere, an automatic lift valve rose, and the charge flowed into
the motor cylinder; the air which entered last leaving first, and
entering the cylinder in advance of the inflammable mixture. The
effect of this arrangement was to prevent premature ignition of the
charge by the hot gases which were being expelled through the
exhaust. The capacity of the displacer cylinder was greater than
the united volume of space at the end of the cylinder, and the
volume swept by the motor piston from the moment of closing the
exhaust; the consequence was that a portion of the contents of the
displacer cylinder passed through the motor cylinder, and away in
the exhaust pipe. It was intended that the portion which passed
away should be nearly pure air, and that what remained should be
inflammable throughout. The motor piston thus compressed the
cool fresh charge, which was ignited when the crank was crossing
the in-centre."
CALORIC OR HOT-AIR ENGINE.
This form of engine was invented by Dr. Robert Stirling, and
has since been improved and applied to practice by Ericsson and
others. One great defect, however, is the low pressures obtained
from the heated air, causing a large area of piston, and consequent
excessive weight of machinery for power obtained.
The general arrangement of such engines consists of a cylinder
whose piston is worked by the contained air being heated by a fur-
nace placed below it; an air pump, worked by the engine, for sup-
plying the cylinder with this air; and a "regenerator," or arrange-
ment of wire gauze or metal plates, which picks up some of the heat
in the air as it is expelled after it has done its work. Recently some
engines have been made to work more economically through pass-
ing the working air, as supplied by the air pump, through the
furnace itself, the latter being in fact a retort. In this way the
waste heat from the furnace has been utilised, and higher pressures
obtained.
ELECTRIC LIGHTING.
1091
ELECTRIC MOTORS.
Recently several very successful attempts have been made to
obtain motive power by means of electricity. In the earlier form
of the electric engine, magnets were used so as to produce a
rotatory motion, a galvanic battery being required to generate
the electricity. By means of the dynamo machine, so much
in use for the production of electricity, it is not now neces-
sary to depend upon chemical action, and by means of a fall
of water or a fixed steam or gas engine electricity may be de-
veloped by the dynamo machine, and conveyed by conductors
to a carriage fitted with a somewhat similar dynamo machine,
which reconverts the supplied electricity. into motive power by
attraction due to electro-magnetic influence. Recently a small
vessel was tried on the Thames driven in this manner. The
engines are a pair of Siemens' dynamos, and the motive power
was derived from accumulators, which were charged by currents.
generated by dynamo machines, and led by wires to the accumu-
lators previous to starting. The speed obtained was about 9 miles
per hour. In this case the source of electricity was derived from.
a Sellon-Volckmar accumulator or "secondary battery." The
secondary battery is in a sense a store of electricity, which in this
manner may be utilized at a point removed from that at which
it was originally generated.
The dynamo machine consists essentially of a number of electro-
magnets rotating at a high velocity close to a series of fixed electro-
magnets,-induced electric currents are thereby set up.
ELECTRIC LIGHTING.
A great advance has taken place of late years in the production
of light by electricity, as during the last year or two many of our
large open spaces in towns, workshops, ships, have been fitted
with electric lamps.
¹ A secondary battery is one in which by means of a current of electricity a chemical'
change has been brought about, and the reaction due to this, after the current is stopped,
generates in turn a current of electricity, which can be utilized directly for motive or light-
ing purposes. Lead plates coated with red lead and immersed in a solution of sulphuric
acid and water are used for such batteries.
1092
MODERN STEAM PRACTICE.
The older form of arc light-whose brilliancy is due to the resis-
tance experienced by the electric current in passing from one carbon
point to another, has been much improved, and may be seen at
many of our railway stations. The irregularity in the brilliancy of
the light has been largely removed by improved form of lamps,
carbons, and motive power in generating the electricity. The
power required to produce the light varies somewhat, about 1000
candles and sometimes considerably more being obtained from
one horse-power.
The greatest step in advance, however, lies in the introduction
of what is known as the incandescent form of lamp, invented by
Swan, Edison, and others, and which enables the light to be sub-
divided, and thus rendered suitable for the lighting of several
apartments, very much in the manner of gas.
This lamp consists of a small globe of glass, in which a very fine
filament of carbon is placed, and connected with the wires from a
dynamo machine or source of electricity. A vacuum, as nearly as
possible perfect, is secured in the glass globe, after which the globe
is hermetically sealed. On the passage of a current of electricity
through the fine filament of carbon, it is rendered incandescent, but
no combustion takes place on account of the absence of air. A
brilliant pleasing light is in this manner obtained. The average
light from one of those lamps-about fifty being in circuit-is about
18 candles, and to obtain this about one-tenth of an effective horse-
power has to be expended, or probably about 115 candles for
indicated horse-power. From experiments it appears that large
spaces can be illuminated by the electric light more economically
than can be accomplished by gas. Great improvements are, how-
ever, being made on gas burners, the rivalry between the two lights
stimulating invention in the utilization of both.
THE STRENGTH OF MATERIALS.
1093
THE STRENGTH OF MATERIALS.
Cohesive strength of bodies.—The tenacity of any material is its
resistance to tearing. The tensile strength varying directly as the
section of fracture, the stress applied is totally distinct from the
length or weight of the material operated upon.
Cohesive strength of timber.—The average stress necessary to tear
asunder a rectangular bar 1 square inch of area is—
Lbs. avoirdupois.
Lbs. avoirdupois.
Lbs. avoirdupois.
Ash,
Beech,
Birch,
Cedar,
Deal,
17,200 Elm,
...
11,000 Hornbeam,
13,000 Oak, English,
20,000 Oak, Canadian,
...
17,000
10,000
...
...
...
15,000 Lancewood,
11,000 Larch,
12,000 Mahogany,
Cohesive Strength of Wrought Iron.
23,400 Pine (yellow, 11,000); red, 12,000
...
...
9,000 Teak,
16,000 Yew,
...
...
15,000
8,000
Lbs. avoirdupois.
Lowmoor bar,
Staffordshire bar,
64,000
59,000
Lancashire bar,
57,000
Lbs. avoirdupois.
Staffordshire plate,
55,000
Yorkshire plate,
55,000
Taking the mean of a number of experi-
ments, the plates above are equal.
Cohesive strength of steel, &c.-The tensile strength of steel varies
with its constituents, the "mild steel" as now used for boiler and
ship-plates has a tenacity of about 29 tons per square inch. Bar
iron varies from 66,886 lbs. to 47,855 lbs., and iron plates from
56,735 lbs. to 41,743 lbs. Mem.-One-fourth of the ultimate strength
of each body is considered sufficient for a permanent load in most
instances, but in machinery much less is used.
To find the safe tensile strain a batten of red pine 6 inches by
3 inches will carry, 12,000 lbs. per square inch being the breaking
stress. One-fourth of the breaking strain multiplied by the area of
the batten will give the permanent load the batten will sustain:
thus-
12000 = 3000 × 6 × 3 54,000 lbs.
4
Again, supposing the permanent load is given, namely, 54,000 lbs.,
and the breadth of the batten is known, namely, 6 inches, what
will be the area of the batten, as likewise its thickness? Divide the
permanent load by one-fourth of the tensile strength, namely,
3000 lbs., and the quotient is the area, which divided by 6 inches,
the breadth, will give the thickness required: thus-
54000
3000
18÷63 inches thick.
1094
MODERN STEAM PRACTICE.
When the thickness is given proceed as before, and the area, 18 inches,
divided by the thickness, 3 inches, leaves 6 inches as the breadth.
To find the side of a square to sustain the load, proceed as before,
and the square root of 18 inches, the area, gives the side of the
square.
54000
3000
=
√18=4°242 inches side of square nearly.
Again, when the area is known, namely, 18 square inches, to find
the diameter of a round batten that will sustain the same load,
divide the area by the constant 7854, and the square root of the
quotient is the diameter.
18
7854
√22.9 = 4'79 inches nearly.
Transverse strength of bodies.-The resistance that a body has
when acted upon transversely or across the fibre is termed its
transverse strength; when the force applied acts perpendicularly to
the length of the body. The strength of beams is inversely as
their lengths, and directly as their breadths and square of their
depths, and when cylindrical as the cubes of their diameters. A
beam, supported at the middle and loaded at each end, will bear
the same weight when supported at both ends and loaded in the
middle. When supported at one end and loaded at the other with
a weight of say 2'5 cwt., the same beam will carry when the weight
is distributed double that, or 5'0 cwt.; when supported at both ends
and loaded at the centre it will carry four times the weight over
that of a beam supported at one end and loaded at the other,
or 100 cwt.; and when supported at both ends, and the load distri-
buted, eight times, or 20'0 cwt.
Strength of rectangular beams.-Take one-fourth of the ultimate
strength as per following table, then multiply by the breadth and
square of the depth, dividing the result by the length of the beam
between the supports in feet, and the quotient will give the per-
manent load the beam will carry.
Table of the Lateral Strain that will Break various Materials, having a section of I square
inch and a length of 1 foot between the supports, lying loosely at both ends.
Cast iron,
Teak,
Ash,
Canadian oak,
Pitch pine,
...
...
...
2548 lbs.
820
""
675"
588
""
544",
Red pine,
English oak,
Riga fir,
Larch,
447 lbs.
400",
376
280
"9
""
THE STRENGTH OF MATERIALS.
1095
To find the safe load for a beam of Canadian oak, breadth
6 inches, depth 12 inches, length between the supports 20 feet,
lying loosely at both ends, and the weight placed in the middle:-
588
4
147; × 6 × (12 × 12) =
127008
=
20
6350'4 lbs.
With the permanent load 63504 lbs. given, the depth 12 inches, and
the distance between the supports 20 feet, to find the breadth of
the beam. Multiply the weight by the distance between the sup-
ports, and divide the product by one-fourth of the ultimate strength,
namely, 147 lbs. as before, into the square of the depth, and the
quotient will be the breadth: thus-
6350˚4×20=127008÷147 × (12 × 12)=6 inches.
Again, when the breadth is given, multiply the weight by the dis-
tance between the supports, and divide by one-fourth of the ultimate
strength multiplied by the breadth, and the square root of the
quotient will be the depth: thus-
6350°4 × 20=127008÷147×6=144; √144=12 inches.
Thus it will be seen that a beam of Canadian oak, 6 inches broad,
12 inches deep, and 20 feet between the supports, lying loosely at
both ends, will carry a safe load of 63504 lbs. placed in the middle,
and when the weight is distributed it will carry double or 12700·8 lbs.
When a beam is firmly fixed at both ends it will carry twice as
much load as when the ends are resting on the supports loosely.
When the weight is not in the middle we must find the effective
length, by multiplying twice the length of the long end by twice
the length of the short end, dividing the product by the total
length of the beam between the supports, and the quotient is the
effective length. Thus supposing the beam to be 20 feet long, and
the weight placed 6 feet from the end, we have 28 feet as double
the length of the long end, and 12 feet as double the length of
the short end-
28 × 12 =16·8, the effective length of beam.
20
And taking 6 inches as the breadth of a beam, 8000 lbs. as the
weight, and 147 lbs. as the one-fourth of the ultimate strength of
Canadian oak, to find the depth of the beam:-
8000 x 16.8
147 × 6
= √152=12°32 inches deep.
To find the downward pressure on the supports, multiply the weight
1096
MODERN STEAM PRACTICE.
by its distance from the nearest end, and divide the product by the
whole length of the beam between the supports, and the quotient
is the downward pressure on the support furthest from end: thus—
8000 x 6
20
=2400 lbs. downward pressure on the support furthest from end, and vice versa.
8000 × 14 – 5600 lbs. on the nearest support, irrespective of the weight of the beam.
20
=
Torsion or twisting.-The resistance to twisting or power of
torsion of a square bar is as the cube of the side, and of a round bar
as the cube of the diameter.
Rule.-Multiply the force applied by the length of the lever in
inches, and divide the result by the value of the ultimate strength
of the material as per following table, and the cube root of the
quotient is the diameter of the shaft or bar.
Cast iron,
...
Wrought iron,
Cast steel,
Gun metal,
Copper,
Brass,
...
:
...
Value for the diameter of shafts.
1500
1700
3200
460
380
425
...
Value for a square shaft.
1800
2000
3800
1
540
440
500
Thus supposing a power of 800 lbs. was exerted on a lever 48 inches
in length, what would be the diameter and side of square of a
wrought-iron shaft or bar when subjected to a steady strain?
800 × 48 — 3/22·5=2·8 inches diameter.
1700
800 × 48 = 3/19′2=2·6 inches side of square.
2000
Again, supposing the diameter and side of square given, and the
length of the lever, to find the power applied at the end of the lever.
Multiply the value as per table by the cube of the diameter, and
divide by the length of the lever in inches; the quotient is the
power applied at the end of the lever.
Crushing and bending.-By reference to the following formulæ
the weight in lbs. that a column of given dimensions will carry may
be practically found. Thus, taking—
Weight the number of lbs. the column will support.
b
=
=the breadth of column in inches.
the length of
do.
do.
a
the diameter
do.
do.
THE STRENGTH OF MATERIALS.
1097
For a rectangular column of cast iron,
For a rectangular column of wrought iron,
=
15300 × 1 × 63
4 × 6² + ·18 × 12
4 × 6² + ·16 × [²
3960 × 1 × b³
4 × 6² + ·5 × 12
Weight=
17800 × 1 × b³
Do.
For a rectangular column of oak,
Do.
...
For a solid cylinder of cast iron,
...
For a solid cylinder of malleable iron,
Do.
For a solid cylinder of oak,
Do.
Do.
9562 x d¹
4 × a² + •18/2
11125 × d¹
4 × d² + '16 × 1²
2470 x d
4 x d² + ·5 × 12
Take a column of oak of a rectangular section 6 inches on the side,
and 10 feet in length, what weight will it carry?
3960 x 10 x (6 × 6 × 6)
4× (6 × 6) + '5 × (10 × 10)
8553600
= 44090 lbs.
194
TABLE OF THE TENSILE STRENGTH OF WROUGHT-IRON PLATES
AT VARIOUS TEMPERATURES.

Breaking Weight Breaking Weight | Breaking Weight
per square inch
per square inch
in Tons.
Mean Breaking
Weight per square
inch in Lbs.
in Lbs.
in Lbs.
33,660
60°
49,009
31,980
21.879
49,009
60
40,357
18.001
27,780
60
43,406
19'377
31,980
44,498
50,219
ΙΙΟ
22'414
29,460
44, 160
112°
19'714
28,620
42,088
120°
18.789
37,020
42,291
212°
40,625
31,980
18.136
212°
39,935
17.828
30,300
212°
45,680
33,660
20*392
45,005
49,500
270°
28,620
22.098
44,020
340°
19'651
31,980
44,020
49,968
340°
28,620
22.307
42,088
395°
18.789
46,018
30,720
66,086
20'574
46,086
We may fairly assume the following value of plates with those of
joints:
Plates, 100 Double rivetting, 70 | Single rivetting, 56.
Slate,
Marble,
Glass,
...
TENACITY OF STONE, &c.
lbs. per sq. in.
lbs. per sq. in.
9,000
6,000
9,000
Brickwork, in Portland cement, 290
Cement, Portland,
Mortar,
350
50
50
Brickwork, in mortar,
The tensile strength of cast-iron varies, but may be taken at about
9 tons per square inch, and the compressive strength at about
50 tons per square inch.
1098
MODERN STEAM PRACTICE.
The compressive strength of wrought iron may be taken at 38,000
lbs.
Compressive strength of steel, by various manufacturers.-In the
following table the diameter of the various specimens tested was
72 inch, and the area in square inches 4071, the weight laid on in
lbs. being 91,840:—

Weight laid on per Square Inch of
Section.
Value in Work
expended in Crush-
ing the Bar.
Compression per
Unit of Length.
lbs.
tons.
225,568
100'700
•286
32,300
225,568
100'700
•267
30,014
225,568
100*700
*328
36,906
225,568
100'700
*398
44,888
225,568
100*700
*347
39,136
225,568
100*700
*339
38,233
225,568
100*700
*379
42,720
225,568
100*700
*315
35,551
225,568
100'700
*419
45,813
225,568
100'700
*278
31,391
Mean 225,568
100*700.
*335
37,695
Box,
...
Oak, English (dried),...
Ash (dried),
...
Plumtree (dried),
Elm,
...
Hornbeam,
Larch,
...
:
:
:
Crushing force in
lbs. per sq. in.
COMPRESSIVE STRENGTH OF WOOD.
Crushing force in
lbs. per sq.
in.
9,771
9,509
9,363
Beech,
Deal,
Cedar,
...
6,402
...
...
5,748
...
8,241
10,000
Pine, yellow,
:
Pine, red,
5,674
5,375
5,800
7,000
5,500
Mahogany, Spanish,
Teak, Moulmein,
COMPRESSIVE STRENGTH OF STONE, &c.
Crushing force in
Ibs. per sq. in.
Limestone, Anglesea,..
Crushing force in
lbs. per sq. in.
8,000
...
12,000
Granite,
Sandstone, Yorkshire,
11,565
7,579
6,127
""
Magnesian,
5,074
Do.
mean of nine
Brick (hard),
1,888
experiments,
9,824
Do. (red),
805
Do. Runcorn,
2,185
Limestone,
...
8,525
Do. mean of four ex-
periments,
1,424
FACTORS OF Safety.
Tensile Stress.
Cast iron, one-fourth per sq. in. of the ultimate strength for dead weights.
Do.
Do.
one-sixth
one-eighth
""
""
Wrought iron and mild steel about one-fifth.
for bridges.
for crane posts and machinery.
THE STRENGTH OF MATERIALS.
1099
Compressive Stress.
Cast iron, free from flexure, 8 tons per sq. in.
Do.
arches, 3 tons per sq. in.
Do.
Do.
pillars supporting dead loads, one-sixth of the ultimate strength.
do. subjected to vibration, one-eighth
""
one-tenth
Do. do. subjected to shocks,
Wrought iron, without flexure, 4 to 3 tons per sq. in.
Do. in columns subjected to shocks, one-sixth, quiescent load one-fourth, of
the breaking weight.
Timber, one-tenth of the ultimate strength per sq. in.
Mason work, working load on rubble masonry, brick, or concrete, one-sixth of the
crushing weight. In an arch, one-twentieth of crushing weight.
Ropes-round ropes, one-seventh, and flat ropes, one-ninth of the ultimate strength.
SPECIFIC GRAVITY OF MATERIALS.
The specific gravity of a body is its weight as compared to the weight of an equal
bulk of water, the weight of water being taken as 1.
Specific gravity of iron.-The specific gravity of wrought iron
varies from 7.8 to 76. Taking 77 as the mean, a cubic foot will
weigh 479.8721664 lbs. Thus, 480 lbs. being the weight, or nearly
so, we may reckon 40 lbs. as the weight of a square foot 1 inch in
thickness; so inch will be 5 lbs. We can therefore readily cal-
culate the weight of all other thicknesses according to the number
of eighth parts and lesser fractional parts of an inch. Cast iron
varies in specific gravity from 75 to 6'9, the average of a variety
of brands being 7:057. Hence the following table:-
½
Wrought iron.
Cast iron.
lbs.
Ibs.
Cubic foot,
Cylindrical foot,
479.872
439'800
376.891
344'407
Spherical foot,..
251.261
230.279
Cubic inch,
O'277
O'254
Cylindrical inch,
...
0.218
O'199
Spherical inch,
O'145
O'133
WEIGHT AND SPECIFIC GRAVITY OF WOODS (Seasoned).

Gravity.
Specific Lbs. per
Cubic Foot.
Specific
Gravity.
Lbs. per
Cubic Foot.
Ash,
Beech,
.8
50
Mahogany, Spanish,
.8
•69
43
Oak, English,
'93
Birch,
71
44
Oak, Canadian,
·87
Cedar,
*48
31
Pine, red,
·65
Deal,
'7
..
44
Pine, yellow,...
'45
Elm,..
•6
37
Teak, Moulmein,
•
•65
7555W
555
50
58
54
4I
29
4I
Hornbeam,
*75
47
Yew,..
50
Larch,
*55
35
I 100
MODERN STEAM PRACTICE.
SPECIFIC GRAVITY, WEIGHT, AND EXPANSION OF FLUIDS AND GASES.

Specific Gravity.
Weight per Cubic Foot.
Expansion.
Alcohol,
.8
pounds.
50°
Ether,
*74
46.
Oil,
Water, fresh,
'90
I'000
56.
62'4
'II
'07
*08
*047
Water, sea,
1'028
Water being 1'
Air,
'0012
Carbonic acid,
*0018
Carburetted hydrogen, 0005
Hydrogen,...
Oxygen,
*00008
*00125
OZS.
I'000
I'524
*420
*069
I'103
627
64'I
Air being I'
Weight of a Cubic
Foot in Grains.
527
800
220
43
Cast antimony,
SPECIFIC GRAVITY OF METALS.
Cast zinc,
Cast iron,
Cast tin,
Bar iron,
Cast nickle,
Cast cobalt,
Hard steel,
...
Soft steel,
...
Cast brass,..
Cast copper,
6.70
Cast silver,
...
10'47
7.19
Hammered silver,
10'51
7.20
Cast lead,
11:35
7'29
Mercury,
...
13.56
7.78
Jewellers' gold,
15.70
7.80
Gold coin,
17.64
7.81
Cast gold, pure,
...
19.25
7.81
Pure gold, hammered,
19.36
7·83
Platinum, pure,
...
19'50
8.39
Platinum, hammered,
20'33
8.78
Platinum wire,
21'04
WEIGHT AND SPECIFIC GRAVITY OF STONES.

Gravity.
Specific Lbs. per
Cubic Foot.
Chalk,
2.3
Clay,
2'0
Coal,
I'3
Coke,...
.8
πω ότ
143
125
Limestone,....
Marble,..
82
Sand,
50
Sandstone,
Earth, rammed,
1.6
100
Stone, Bath,
Flint,
2.6
163
Gravel,
1'9
120
Stone, Portland,…………….
York flag,...
Granite,..
2.6
164
Slate,
Grindstone,
2'I
131
Shingle,
Specific
Gravity.
Lbs. per
Cubic Foot.
2 212-22 21
2'5
156
2'7
168
I'9
120
2.5
156
1.8
II2
2'1
131
2.3
143
2.8
175
I'4
90
WEIGHT AND SPECIFIC GRAVITY OF ARTIFICIAL SUBSTANCES.

Specific
Lbs. per
Gravity. Cubic Foot.
Specific
Lbs. per
Gravity. Cubic Foot.
Brick,...
2'0
124
Cement, Roman,
Brickwork, in mortar,
1.6
100
Glass,
1 2
1'0
63
2'5
156
Brickwork, in cement,
1.8
II2
Lime, quick,………..
.8
50
Concrete, ordinary,..
I'9
119
Mortar,
1'7
106
Concrete, in cement,...
2'2
133
Tile,
1.8
II2
Cement, Portland,...
1.3
81
.
MEANS FOR TRANSMITTING POWER.
I IOI
MECHANICAL MEANS FOR TRANSMITTING
POWER.
There are three mechanical contrivances for the transmission,
distribution, and changing of the direction of power exerted by
living agents, or by active agents of nature, namely, the lever, the
inclined plane, and the pulley. Various arrangements of these
powers exist, however, which require to be carefully studied by
those who would master the subject thoroughly. For example, the
steelyard, weighing balance, &c., are levers. The wheels and axles
of an ordinary crane are simply a system of levers revolving around
fixed centres. The wedge is a double inclined plane; while the
screw is a revolving inclined plane.
The mechanical advantage of a machine is the ratio of weight to
power, or p ;
thus
W
I. Lever
W arm of power
:.
P
arm of weight
W
radius of wheel
II. Wheel and axle
Р
radius of axle
W
III. Toothed wheels
number of teeth in wheel
P¯number of teeth in pinion'
W N*
2n+
IV. Pulley
or
P
I
I
V. Inclined plane
W length of plane
P - height of plane
W
=
height of wedge
P¯half back of wedge'
VI. Wedge
VII. Screw
Р
W_circumference described by power
pitch
It may be stated in regard to the wedge that its advantage
lies principally in the suitable transmission of the percussive action
of the blow of the hammer to the particles of the wood or other sub-
stance upon which it is used; we see this very well exemplified in
the case of a nail driven home by a hammer, where a few slight
taps will accomplish much more than a very heavy load or weight
simply placed on the top of the nail.
Ist system. N=number of cords or plies acting at lower block.
+ 2nd system. n=number of movable pulleys.
I 102
MODERN STEAM PRACTICE.
Compound arrangements of the simple machines now referred to
enable us to extend our advantage still further, as in the case of the
weighing machine as used for heavy loads, where one lever is
arranged so as to act upon another, whereby the advantage obtained
by the first lever is intensified by a second lever, and so on.
One
great matter to be remembered in all such considerations, is that
no power is created by any machine, the energy expended by
the power is always equal to the work done or resistance over.
come, or
Power x space traversed
moved through.
W (or resistance) x height or spac
THE PARALLELOGRAM OF FORCES.
In the construction of roofs, cranes, bridges, and general machi-
nery, it is necessary to consider the direction and amount of strain
on the various parts, in order to proportion the parts according to
the strain they are subjected to.
To fully understand the theorem of the parallelogram of forces, it
is necessary to study the following definitions:-
When two forces act in lines of direction making an angle with
each other, the single force which will balance both is named the
resultant, and the forces themselves are called the components.
The point at which the force is applied in the line of its direction
is named the point of application.
The theorem of the parallelogram of forces.-If any two forces be
represented in direction and magnitude by the sides of a parallelo-
gram, the diagonal of the parallelogram is their resultant in magni-
tude and direction.
A
D
Fig. 764.
B
C
If A, B, C, D (Fig. 764) represents
the parallelogram, and the line A B
represents the direction and magni-
tude of one of the forces, and A D that
of the other, then the diagonal A C is
the resultant of both forces in magnitude and direction.
If a force acting from A to B (Fig. 765) is represented by say
40 lbs., while another force operating at right angles, from A to D,

THE PARALLELOGRAM OF FORCES.
1103
is represented by 20 lbs., the sides have a value to each as 20 to 40.
When the parallelogram is completed the diagonal A E is the
resultant of the two forces, and the path described by the moving

A
1
10
20
30
40
B
D
70
20
Fig. 765.
E
body. The diagonal thus described is the path of the greatest velo-
city. A body will move along this diagonal in the same time that
it would move along either side if acted on by one force alone;
that is to say, a body will move from A to E with the resultant force
in the same time as it would take to move from A to B, or from A
to D, if acted upon by either force separately.
The resultant force, acting through the line A E, is never equal to
the two forces added together as represented by the line A B and

E
$10
F

10
A
8 TONS
W
Fig. 766.
A
E
W.
B
6 TONS,
Fig. 767.
A D, but is somewhat less, and consequently there is a loss of power
attendant upon compound force.
To illustrate this more fully, we will take for example an
ordinary crane. From the centre of the jib A (Fig. 766) drop a
1104
MODERN STEAM PRACTICE.
vertical line A D, and divide it into as many parts as w has tons;
draw D E parallel to the jib A C, until it cuts the line A B (which is in
tension) produced to E, draw the horizontal line EF, and produce
the vertical line A D to F. The thrust on the jib equals the line E D,
20 tons, as per diagram, the tension on A B≈ 15 tons on the line A E-
The crane post, BC, may be considered as a fixed beam, with
a bending strain=E F, and a vertical load a F.
As another example we will take a beam of any material, repre-
sented by the line A B (Fig. 767), which is firmly fixed into a wall,
having a strut, B D, likewise firmly fixed into the wall at D. A
weight of 6 tons is suspended from the end of the beam as at B.
Required the amount of the strain on A B and B D. Divide the
vertical line B Winto as many equal spaces as there are tons,
namely, 6; draw WE parallel to A B intersecting B D at E. The line
WE represents the tension from A to B, while B E represents the
compression on the strut B D, which is found by dividing the line
BE as per scale on B W, or nearly 8.8 tons of compression.
FORMULE FOR WHEELS, SHAFTS, ETC.
Teeth of wheels.-To find the thickness of tooth, the strain at the
pitch line being given, divide the pressure in pounds at the pitch
line by 3000, and the square root of the quotient is the thickness of
the teeth in inches, the breadth being 2.5 times the pitch.
PROPORTIONS.
Thickness of rim of wheel = pitch × 0.45.
Thickness of arms
x 0'45.
From pitch line to top of tooth = pitch × 0.33.
Total depth of tooth
× 0'75. | Ordinary width of tooth = × 2.25.
وو
When the teeth are struck or drawn with compasses, from the centre
of the teeth on the pitch line is the point for delineating the tooth
from the pitch line to the point, while the root of the tooth is radial
from the pitch line.
In the configuration of epicycloidal teeth, the teeth of all the
wheels of the same pitch, working into each other, should be gene-
rated by the same rolling circle. The best diameter of the rolling
circle for any pitch equals the pitch multiplied by 2:2, unless any
wheel in the set should have less than fourteen teeth. It is not
advisable that any wheel should have less than fourteen teeth; but
if so, the diameter of the rolling circle may be determined by the
following formula-
FORMULÆ FOR WHEELS, SHAFTS, ETC.
1105
When D equals the diameter of the rolling circle, P equals the
pitch of teeth, and N the number of teeth in the smallest wheel of
the set-
D=
NP
6.3
Pitches of Teeth of Wheels of equal Strength in different Materials.
Pitch of cast iron,
...
brass,
hard wood,
""
:
I'00
I'12
1.26
WROUGHT-IRON SHAFTING.
D=
3/ExC.
H
N
That is, when D equals the diameter of shaft in inches, H the num-
ber of nominal horse power to be transmitted, and N the number
of revolutions per minute. To find the diameter, divide the horse
power by the number of revolutions, multiply the quotient by the
constant for the different materials, and the cube root of the pro-
duct is the diameter approximately.
For plain crank shaft the constant is 320.
For second motion shafts
For ordinary shafting
200.
""
IOO.
""
It is, however, preferable to calculate shafts by the direct force
applied. Thus, when the length of lever or radius of wheel is known,
and the force applied in lbs.: to find the diameter, multiply the
length of the lever by the force applied in lbs., divide by the con-
stant for the different materials, and the cube root of the quotient
is the diameter:
Constant for cast iron is
Do. for wrought iron is
Do. for cast steel is
Do.
for gun metal is
Do. for brass is
...
1500
1700
...
3200
460
...
...
Do. for copper is
...
425
380
The same rule holds good for square shafts, but with different con-
stants, thus:—
Constant for cast iron is
Do. for wrought iron is
Do. for cast steel is
Do. for gun metal is
Do. for brass is
Do. for copper is
:
:
:
1800
...
2000
3800
...
:
540
...
500
440
70
1106
MODERN STEAM PRACTICE.
Strength of round shafting to resist lateral stress.-Multiply the
length of shaft supported at both ends in feet by the weight or stress
applied at centre, divide by the constant 700 for wrought iron, and
the cube root of the quotient is the diameter in inches; when the
weight is equally distributed the constant is 1400.
Shaft bearings.-The bearings for the shafting are hung from the
rafters, girders, or placed on brackets bolted to the walls of the shop
or factory; the strength of the brackets depends on the amount of
overhang. The proportions of the pillow blocks may be taken from
the diameter of the shaft; ordinary pillow blocks have a proportion
as follows, when the diameter is given:-
Diameter multiplied by '4 equals the thickness of cover.
Do.
Do.
*3
'25
thickness of sole.
diameter of bolts when two are used.
The thickness of the bottom and top brasses equals one-seventh of
the diameter of the shaft, and at the sides three-fourths of the bottom
thickness will suffice.
Couplings and distance between pillow-block supports.—The coup-
lings for general shafting are of cast iron. When D equals the
diameter of shaft, B the diameter of the coupling, and A the length
of the coupling box or short cylinder embracing the ends of
shafting-
A = the diameter multiplied by 3'6,
B = the diameter multiplied by 2'4,
that is for medium sizes; but when the shaft is of extra diameter
this proportion can be reduced, and wrought-iron rings shrunk on
the ends; the coupling is secured with ordinary keys, one being
quite sufficient for the usual run of shop and factory shafting.
For ordinary shop shafting, 3 inches diameter, the distance between
the centres of the bearing is from 9 to 10 feet. To find the
distance for other sizes, square the diameter of the shaft; extract
the cube root, and multiply by 45, or 5 where there is no power
taken off between, and the product is the distance between centres
in feet.
Pulleys.-The curve or convexity of pulleys driven by means of
belting is about ½ inch per foot in width. The final speed of a
series of pulleys is found in the same way as a series of toothed
wheels, provided there be no slip. The velocity of the driving
pulley is multiplied by the drivers and divided by the driven, which
gives the final velocity. It is usual to split pulleys and bolt them
FITTINGS FOR LINE SHAFTS.
1107
together for the convenience of putting them on or taking them off
without disturbing the shafting; and they are generally secured to
the shaft with a single key, while others adopt a conical ferrule, so
that the pulleys can be shifted to any part of the shaft; the eye of
the pulley is turned conical, and the ferrule is driven in, and depends
entirely on the surface in contact with the shaft, which in some cases
is sufficient to prevent the pulley turning round.
FITTINGS FOR LINE SHAFTS.¹
Since the time when Sir William Fairbairn began his improve-
ments in the manner of constructing and arranging line shafts for
factories, there has been a constant succession of modifications and
changes of what may be termed line-shaft fittings, especially of bear-
ings and couplings. As a general proposition, line shafts placed
beneath machine floors, and upon earth foundations, form an arrange-
ment favourable to engineers who construct and furnish shafts, but
in many cases unfavourable to those who own and operate factories.
The expense of pits, which is always considerable, and sometimes
very great, is generally a matter of no concern to engineers who
furnish shafts, but the difference between a line shaft which will
operate well on earth foundations and one which will operate well
when suspended to a ceiling, is a matter of considerable importance
to these engineers.
A line shaft adapted for earth supports and mounted on masonry
can be, and generally is, made from one-third heavier to twice as
heavy as a shaft for the same duty should be if suspended from a
ceiling. The latter require to be of a minimum weight; the bear-
ings should be pivoted, and so arranged that the shaft may be
readily adjusted up or down to suit the settling of floors, or of
pillars on which floors are supported. Couplings on cuspended
shafts have not only to transmit the torsional strain of the work
performed, but must be secure enough to withstand the bending
strains from a shaft being more or less out of line. The shafts being
one of the first objects seen in entering a factory, they must run true
and without noise; and pulleys must be turned true and balanced.
Shafts constructed to fill these conditions last named, while they
may not cost any more for a given duty than heavier shafts adapted
for pits, must be more carefully fitted. Shafts adapted for suspend-
¹ Abridged from Engineering.
1108
MODERN STEAM PRACTICE.
•
ing to ceilings cannot be produced so as to class with what is termed
pound work," and engineers who have attempted to reduce the
weight of line shafts and fittings, have generally had to contend
with rival estimates, in cases where the difference could not be fairly
explained to those who purchase.
Two other things in connection with the arrangement of "over-
head" and "underfloor" shafts, may be noticed-danger from fire,
and floor space. In regard to the first, especially in factories where
fibrous material or wooden wares are manufactured, there is no mana-
ger of experience who will not admit that a concealed pit shaft causes.
more anxiety and calls for more circumspection than a whole factory
besides. Belts passing down through a floor carry with them, by
the air currents induced, much of the light dust arising from
machines, and generally, we may say unavoidably, shavings or other
débris, so that shaft pits become in effect tinder boxes. A piece of
iron, a stone, sometimes even a nail, coming in contact with an iron
pulley running at great speed, will cause a shower of sparks to be
discharged, and in an instant all is in flames. In respect to floor
space it is perhaps useless to say that belts coming down from over-
head shafts to machines consume the least possible amount of use-
ful room; besides, the arrangement of most factory machines, espe-
cially machine tools for iron, renders overhead counter-shafts indis
pensable. Holes cut through floors to accommodate belts, with the
safety cases which must surround them, consume valuable room.
There are, no doubt, in many cases, especially where heavy shafts
are employed, sufficient reasons for mounting line shafts on earth
foundations, but such reasons are too well understood to require
discussion. What has been explained thus far is preliminary to
some notice of couplings for line shafts.
Experience has shown that conditions other than a capacity for
torsional resistance should govern the size of line shafts and coupled
joints. The engineer who after careful calculation had reached a
theoretical factor of safety for a line shaft, and then instructed his
draughtsman to "quadruple it," was but following what ordinary
practice demands. Solid sleeves, to embrace both ends and flange
couplings with clutch faces, have long been abandoned by American
engineers, and they were succeeded by plain flange couplings, as
shown in Fig. 768; the two halves being joined in some cases by
taper bolts, as drawn, in other cases by fitted parallel bolts, and
not unfrequently by loose bolts, depending for adjustment on a
FITTINGS FOR LINE SHAFTS.
1109
dowel formed by one of the shafts projecting a short distance into
the second coupling, as shown at a. Such couplings were objection-
able because of the danger arising from
the exposed bolt heads and nuts, also
because the projecting end or dowel a
was difficult to withdraw in disconnect-
ing shafts, and required that a shaft be
moved endwise to the extent to which
it lapped over the joint between the
flanges. This last objection, which may
for some reasons seem a trivial one, is
nevertheless often a cause of much in-
convenience. If a long shaft is to be dis-
connected in the centre it not unfrequently happens that in order
to move either part ½ inch endwise several pulleys, wheels, or
collars must be loosened; the couplings, if placed against the bear-
ings, as was often the case, rendered such movement impossible.
The next improvement which fol-

C
Fig. 768.

Fig. 769.
lowed was the flange coupling (Fig.
769), having a guard rim c to prevent
from danger of belts or clothing catch-
ing on the bolt heads or nuts. This
rim also gave a stronger form to the
plates, so that they could be reduced in
thickness and weight, and in many
cases permitted couplings to be em-
ployed as pulleys for belts. The dowel
was formed by a slight interlocking,
as shown at e, in most cases not exceeding % inch in depth, so
that in disconnecting, it rarely happened that by straining a
shaft its supports would not yield enough to allow a section to be
taken out. The coupling flanges were usually keyed on flush, as
a dowel formed by the shafts of % inch in length would have been
of but little use; besides, from the increased bearing surface gained
by interlocking at the periphery of the flanges, the shaft dowel was
not required.
In the course of time it became evident that, however safely
solid or flange couplings would hold shafts, there were important
conditions wanting. Factories growing up from small beginnings,
as is common in America, there was a necessity for often changing
IIIO
MODERN STEAM PRACTICE.
shafts and machines; pulleys had to be moved, new sections of shafts
had to be added, and it was impossible to drive off or refit couplings
each time a pulley was to be put on, or a shaft changed from one
place to another Split or half pulleys were clumsy, heavy, expen-
sive, and regarded as a device to meet the difficulties of removing
couplings and swinging the shafts on their bearings so as to put
pulleys on. Each coupling had to be fitted to the shafts by draw
filing, and as the couplings had to be taken off in such cases as have
been alluded to, a forced fit could not be made, and the only way
of keeping the couplings on was to key them with taper keys, or
wedges properly speaking, driven with great force. Such wedge
keys, no matter how perfect the couplings were fitted, strained them
out of truth, so that the shafts required to be put in a lathe and the
faces of the couplings be again “trued up” after keying on. When
a coupling was driven off and again put on it seldom ran true, while
by driving off and on a few times the fit was destroyed.
The operation of "facing off" of course constituted the couplings
what may be called an integral part of the shafts, that is, the
couplings belonged only where fitted, and as each half coupling had
also its fitted mate because of the dowel joint and bolts, a line shaft,
no matter how long, became a kind of special machine, whose parts
were all fitted and matched together, each piece being numbered,
arranged, and in no way interchangeable.
Such conditions, from the force of experience rather than by any
inductive reasoning, led to what will be termed "compressive
couplings," or rather it prepared a market for such couplings when
engineers produced them.
INDEX.
Abbey Mills Pumping Station, 226, 980.
Aberdeen, keel of the screw steamer, 792.
Accidental loads on roofs, 987.
Accumulator, the, 202, 315, 329.
— pumping engine for charging the, 316.
Adhesive power of locomotives, 748.
Adit in mines, 193.
Admiralty tests for steel, 965.
After-damp in mines, 4.
Agincourt, war ship, 910.
Air cylinder of blowing engines, 256, 273, 279, 282.
Air pump of Cornish engine, 173.
of oscillating engine, 350.
for condensers, 435.
rod crosshead, 360.
and condenser, rules for, 310.
of marine engine, rules for, 523.
bucket head and foot valves, 351.
Air vessel for water works, 211, 225.
Alaska, details of the, 415, 494, 497, 868.
Allenheads, water engines at, 327.
American locomotive, the, 663.
Anchorages of suspension bridge, 1038, 1049.
Angle iron, weight of, 33, 905.
Angle irons, hydraulic machine for bending, 346.
Annular safety valve for locomotive, 568.
water spaces in boilers, 15.
Aperture for screw propeller, rule for, 526.
Arbors in pumping engines, 163.
Arched roofs, 983.
Area of locomotive piston rod, to find the, 753.
slide-valve rod, to find the, 753-
of the water lines, to find the, 856.
Arethusa, dimensions of the, 927.
Arizona, details of the, 415, 505.
Armstrong, Sir Wm., on unarmoured war ships, 921.
Ash pan for locomotive fire box, 553, 559.
specification for locomotive, 732
of American locomotive, 668.
Ash pits in marine boilers, 75.
Atmospheric line, 132.
Auxiliary fire box for locomotive, 537.
Available heat in coal, 64.
Axle of locomotive, 620, 678.
specification for, 739, 744.
rules for, 758.
of American locomotive, 678.
Axle box of locomotive, 626.
specification for, 738, 744.
-- rules for, 758.
of American locomotive, 679.
B.
Back pressure, relieving the slide valve from, 127.
Balance bobs on pump rods, 198.
Ball safety valve for locomotive, 569.
- valves on metal seatings, 214.
Ballast in ships, water, 831.
Bar iron, weight of, 34.
Bars in locomotive fire box, 533, 539, 549.
Battery and floating dock, construction of, 973..
Beam of engine, rules for the, 310.
Beam engine, single-acting, 151, 162.
-high and low pressure combined, 299.
Bed plate of winding engine, 246.
for trunnion blocks, 354.
Bell-Coleman refrigerating machine, 908.
Bell cranks for pumping engines, 200.
Bellerophon, war ship, 910.
Bells for American locomotive, 670, 682.
'Belted' cruisers, 928.
Bending moment for beam, 1001.
-- of an iron ship, 840.
Bessemer process of steel making, 960.
Bilge injection valve, 444.
Bilge keels, 800, 802.
Bilge, side, or sister keelsons, 800.
Bitts around masts, 830.
'Black damp' in mines, 4.
Black Prince, dimensions of the, 909.
Blades for the screw propeller, 480.
Blast orifice, form of the, 532, 566.
pipe of locomotive, 532.
construction of the, 566.
specification for the, 733.
nozzle in American locomotive, 668.
Blowing mills at Dowlais Iron Works, 288.
Blowing engines, 250.
horizontal high-pressure, 280.
self-contained, 279.
side-lever combined, 274.
vertical, 277.
vertical table, 279.
Blow-off plug tap for locomotive, 577
valves for American locomotive, 671.
valves for water mains, 203.
Blow-through condenser, 183.
- valve for oscillating engine, 361.
for horizontal marine engine, 395.
Bogie carriage for locomotive, 644.
specification for, 737.
for American locomotive, 681.
Boiler Insurance Co., report of, 89.
of the locomotive, 547.
- specification for, 729.
for mountings of, 741.
rules for strength of, 755.
Boiler plates, rivetting of, 19.
strength of, 19, 30.
Boilers, distinctive forms of, 10.
economy in weight of, 72.
II12
INDEX.
#
Boilers, manufacture of, 85.
- strength of cylindrical, 20.
for blowing engine, 274.
for marine purposes, 51.
for river boats, 61.
for stationary engines, 10.
for torpedo boats, 62, 72.
for war ships, 56.
Bollard heads, 819.
Bolts for locomotive engine, 742.
Boring for coal, 2.
Bowstring girder, 1005.
Box girders, breaking weight for, 1004.
keelson, 798.
Brackets for locomotive boiler, 562.
Brake gear for locomotive tender, 685.
resistances, experiments on, 692.
- specification for locomotive, 741, 745.
Brakes, continuous, 689.
for winding engines, 248.
Branch steam pipe, 457.
Brandon, compound engines of the, 491.
Breast wheel, 317.
Bridges of large span, tabulated statement of, 1055-
examples of railway, 1007.
Britannia Bridge, 1005.
British locomotive, the, 547.
Bronze for propeller blades, 486.
Bucket for pumping engine, 160.
Bucket ladder of dredging vessel, 931.
Buffers, locomotive, 646.
-- and drawgear, specification for, 734, 743.
Builders' measurement and register tonnage, 842.
Building of iron vessels, 785.
Buildings for pumping engines, 228.
Bulkheads, construction of, 812, 876, 971.
"Bull's-head' in pumping machinery, 197,
Bursting pressure of boilers, 28.
Butterly boiler, the, 43.
Butts and butt straps for ship's plating, 807.
C.
Cab, specification for locomotive, 740.
of American locomotive, 682.
Cables of suspension bridge, 1041, 1046.
Caloric or hot-air engine, 109o.
Camel or floating dock, 967.
Cantilevers, 999.
Casings of locomotive engine, 741.
Cat heads, 820.
Cataract of pumping engine, 170.
Catch for eccentric on shaft, 369.
Centre of displacement, 847.
of effort, 847.
of gravity in a ship, 844.
to calculate the, 854, 858.
Centrifugal pumps, 236.
Chain cables, diameter and weight of, 906.
Chain plates in ships, 828.
Charlotte Dundas, the first steamer, 378.
Check valves for marine boilers, 459.
Chests for cylinder of blowing engine, 257.
Chimney, area and dimensions of, 41.
Chimney of locomotive, 558.
Chimney of locomotive, specification for, 732.
of American locomotive, 667.
Choke damp in mines, 4.
Circular regulator for locomotive steam pipe, 563.
Circulating pumps for condensers, 432.
City of Rome, details of, 73, 345, 415, 432, 497, 868.
Clack valve with leather hinge, 159.
Cleaning of boilers, 93.
Clifton Suspension Bridge, Canada, 1036.
Clothing steam pipes, 458.
Clyde, dredgers on the river, 937.
Clyde river steamers, engines of, 378.
Coal and coal mining, 1.
— consumption and cost of, 220.
— machines for cutting, 8.
machines for raising, 8.
Coal-burning fire box of locomotive, 534, 537-
American locomotive, 663.
Coal boxes, thickness of plates for, 78.
Coals used in American engines, 666.
Coamings for hatchways, 815.
Cocks for marine engines, table of, 528.
Coefficient for steam ships, 513.
of steam ship Cadiz, 512.
Cohesive strength of bodies, 1093.
Coke, uses of, I.
Cold-water pump, 181.
rules for, 311.
of blowing engine, 267.
Colossus, constructive details of the, 920.
Columba, engines of the Clyde steamer, 377.
Combustion chamber in locomotive fire box, 534.
Comet, details of the steamer, 378.
Compartments for water ballast, 831.
Compensating levers for locomotive springs, 642.
Compound engine, the, 491.
diagrams, 134.
-beam engines, 492.
Compounding locomotive engines, 693.
Compressive strength of bodies, 1098.
Comus, details of the, 927.
Condensation, surface system of, 424.
Condenser of Cornish engine, 173.
- for a pair of coupled engines, 180.
with self-adjusting jet of steam, 179.
for horizontal marine engines, 419.
for oscillating engine, 349.
of marine engines, rule for, 524.
Connecting rod and crank, 117.
of blowing engines, 263, 273.
of winding engine, 245.
for horizontal marine engines, 410.
rules for, 311.
of marine engines, rule for, 521.
Connecting rods of locomotive, 608.
for outside cylinders, 614.
rules for the, 761.
specification for the, 736.
of American locomotive, 676.
Connections between engine and tender, 646, 659,
680, 684, 687.
Conning tower in war ships, 912.
Constance, compound engines of the, 492.
Constant pressure, 143.
temperature, 143.
volume or density, 144.
7
INDEX.
1113
Consumption of coal, table of, 508.
Conway Bridge, Wales, 1005.
Copper steam pipes for marine engines, 528.
Corliss engine, the, 295.
diagrams from beam condensing, 298.
Cornish boiler with single furnace, 10.
and multitubular boiler, 1I.
- engine for mines, 150.
valve gear, 164.
Corrosion in boilers, 71.
of steel and iron plates, 963, 1076.
Corvettes, unarmoured, 927.
Countersink, and rivet, 880.
Coupled locomotive engines of small size, 723.
Coupling rods of locomotive, 616.
specification for, 736.
of American locomotive, 677.
Coupling between engine and tender, 646, 687.
Couplings of screw shafts, repairing, 472.
for factory shafting, 1106, 1108.
Covering for boilers at Tettenhall, 204.
of marine boilers, 458.
of locomotive boiler, 562.
for iron roofs, 980.
Cover plates, 1021, 1063.
Cowcatcher in American locomotive, 68r.
Cradle hoists, hydraulic, 344-
Crane, hydraulic, 318.
steam, of 70 tons, 1080, and plate.
Cranes, tubular wrought-iron, 1069.
for tipping coal-waggons, masting, &c., 1077.
- table of deflection of, 1070.
Cranked shaft for air pump, 353.
for horizontal marine engines, 413.
Crank and eccentric paths, 118.
Crank pin, rules for, 312.
Crank shaft and crank of blowing engines, 262, 272.
Crank shaft, rules for, 312.
Crank shafts, built, 414.
Cranked axle for locomotives, 618.
Cranks and side rods of locomotive, rules for, 761.
Crank pins of American locomotive, 679.
Creuzot Iron Works, blowing engine at, 277.
Crompton's traction engine, details of, 763.
Crosshead of Cornish engine, 151.
for rod of winding engine, 245.
of oscillating engine, 359.
for single piston rod, 409.
and guides of marine engine, rules for, 522
Crossheads for blowing engine, 265.
Crosshead for piston rod of locomotive, 603.
rules for the, 760.
- specification for the, 735.
of American locomotive, 675.
Crossness Reservoir and Pumping Station, 230.
Cruisers, unarmoured, 921.
Crumlin Viaduct, Wales, 1005.
Crushing and bending, 1096.
Currents in locom. fire box, steam-inducted, 544-
Curtain plate for locomotive fire box, 535.
Cut-off of steam, 117.
Cylinder of Cornish engine, 151, 492.
of horizontal marine engine, 385.
of oscillating engine, 347.
of winding engine, 241.
area of, and length of stroke, 304, 309.
Cylinder of marine engine, rules for, 516, 527.
cover for blowing engine, 256.
of horizontal marine engine, 387.
Cylinders of hydraulic crane, 318.
arrangement of high and low pressure, 494.
Cylinder of locom. engine, construction of, 578.
to find dimensions of the, 752, 753.
specification for the, 734.
of American locomotive, 671.
Cylindrical boiler, different kinds of the, 10.
- strength of, 20.
D.
Deck beams, sections for, 874-
— fastenings, 875.
Decks, construction of ships', 814.
Denny, Mr. Wm., on future sea-going steamers, 841.
Deptford Pumping Station, 229.
Depth of locomotive piston, to find the, 753-
Despatch boats, boiler for, 58.
Devastation, details of the, 911.
Diagrams in steam cylinder, 130.
of compound engines, 134.
from engines of the Parisian, 497-
Diaphragm in locomotive fire box, 539, 542.
Direct-acting horizontal engine for winding, 240.
— pumping engine, 189.
Discharge valve for condenser, 441.
Disconnecting paddle-wheel shaft, 383.
Displacement of a vessel, table of, 853.
to calculate the, 854.
Distance pipe for air chests, 257.
Distributing fan for grain, 338.
Distribution of load on locomotive, 749.
Dock gates, opening and closing of, 322.
Docks, hydraulic machinery at, 329.
construction of floating, 967.
Dome for locomotive, 573.
Dome vertical boiler, 13.
Double-acting pumping engine, 198.
Double-beat valve, 158, 203, 213.
regulator for locomotive steam-pipe, 564.
Double eccentrics and link motion, 121.
furnace boiler, 11.
marine boilers, 53, 59.
bottoms for ships, 803, 831.
Douro Bridge, near Oporto, 1054.
Dowlais Iron Works, blowing engines at, 269.
rolling mill engines at, 285.
Drainage works, pumping engines for, 226.
Draining of mines, 3.
Draughts, economy of forced, 73.
Dreadnought, war ship, 914.
Dredger, boilers for a, 51.
of 45 horse-power, details of, 935-
of 25 horse-power, details of, 936.
combined hopper, 936, and plate.
scantling for a, 959.
and hopper barge, construction of, 930.
Drilling and punching of plates, 71.
Drilling plates for girder bridges, 1007.
Drum for winding engines, 239, 248.
Dry steam, 46.
D slide valves for marine engines, 106.
II14
INDEX.
Dunlop's pneumatic marine governor, 506.
Duty of an engine, to find the, 305.
Dyke in mining, 2.
Dynamo machine, the, 1091.
E.
East River Suspension Bridge, U. States, 1052.
Eccentric for slide valve, 98.
and rod for blowing engine, 255.
of horizontal marine engine, 393.
of oscillating engine, 367.
gear of marine engines, rules for, 519.
Eccentrics of locomotive, 587.
Edinburgh, war ship, 920.
Efficiency of paddle vessels, calculation of, 515.
Ejector condenser for pumping engine, 176.
Electric lighting, 41, 1091.
motors, 1091.
Elevator for raising grain, 342.
Elliptical fire box for locomotive, 542.
Engine, duty of an, 305.
Engineering Works, &c., 967–1084.
Engines for water works, 204.
Entablature of blowing engine, 260.
Equilibrum valve for reducing pressure, 47.
-
for pumping engine, 162.
Escape valve for horizontal marine engine, 396.
Exhaust pipe of horizontal marine engine, 389.
Expansion in boilers, 70.
-
of
gases, 143, 1100.
of steam, 141–149.
valve for oscillating engine, 364.
Explosion of boilers, 27.
Express engine for Great Northern Railway, 700.
for Pennsylvania Railroad, 727.
F.
Factors of safety, 69, 1098.
Fairy Queen, engine of the, 377.
Fan for spreading grain in warehouses, 337.
Fans, varieties of ventilating, 6.
'Fault' in mining, 2.
Feathering paddle wheel, 378.
←
- propellers, 481.
Feed pump of overhead-beam blowing engine, 268.
of Cornish engine, 182.
of winding engine, 247.
rules for the, 311.
for marine engine, 445.
rules for the, 525.
Feed and bilge pumps, 353-
Feed-water heaters, 76, 249.
--for locomotives, 662.
Feed pumps of locomotive, 651.
rules for the, 758.
of American locomotive, 683.
Fell's system for steep railway inclines, 720.
Festiniog Railway, Wales, details of, 720.
Fire bars of marine boilers, 67.
of locomotive, 560.
―― of American locomotive, 668.
Fire box, flat, 88.
Fire box of locomotive, 533, 547.
specification for the, 730.
of American locomotive, 663.
stays in locomotive, 548.
rules for the, 757.
Fire-brick arch in locomotive fire box, 541.
Fire damp in mines, 4.
— engines, steam, 1085, and plate.
-grate for marine boiler, 63.
-- of locomotive, to find area of, 754-
Firing, necessity for careful, 545.
Fittings of boilers, report on, 91.
-for marine boilers, 454.
Flanges for copper pipes, table of, 529.
- strain on girder, 1004.
Flanging plates, hydraulic machine for, 346.
Flat plate keels, 800.
- surfaces in boilers, 28.
Flexibility of locomotive springs, table of, 637.
Floating docks, construction of, 967.
Floor plates, construction of ships', 795, 872.
Flue boiler, self-contained, 12.
Flues in boilers, 25.
Fluid, friction of a, 146.
Fluids and gases, specific gravity of, 1100.
Fly wheel of blowing engines, 263, 272.
--rules for the, 312.
Foot plates for locomotives, 650.
Foot and head valves for air pump, 437.
Forcing set of pumps, 154.
Fore mast and yards, rules for, 891
Formulæ for lattice girder bridge, 1032.
- for wheels, shafts, &c., 1104.
Forth Bridge, 1053.
Foundations for boilers, 36.
Framework of an iron ship, 871.
Framing of locomotive, 626.
rules for the, 760.
specification for the, 733, 743.
- of American locomotive, 679.
Framing, arrangement of ship's, 794.
construction of ship's, 786.
for ship's engine room, 816.
— longitudinal system of, 883.
— transverse system of, 884.
Friction of a fluid through a pipe, 146.
- of water through pipes, 305.
Froude's experimental models of vessels, 782.
Fuel, economy of, 182.
Funnel, construction and dimensions of, 73, 74.
Furnaces in marine boilers, 68, 75.
G.
Galton, Capt. D., on brake resistances, 692.
Gas in coal workings, 4.
- engines, Otto's and Clerk's, 1087.
Gases, expansion of, 143, 1100.
Gauge glass for marine boilers, 460.
Geared engine for pumping, 201.
Giffard injector for locomotive, 758.
Girder bridges, construction of, 1002.
Girders, plating, 1006.
strains on wrought iron, 996.
Gland for piston rod of oscillating engine, 349.
INDEX.
1115
Goods engine for East Indian Railway, 715
for Furness Railway, 717.
--for Great South. & West. Ry. of Ireland, 712.
Governor, rules for the, 313.
Governors to prevent 'racing,' 505.
Grain, machinery for warehousing, 329.
Graphic system of investigation of strains, 858.
Grease cups for locomotive cylinder, 584.
Great Eastern, details of the, 347, 377, 778.
Great Western, voyage of the, 377.
Gridiron expansion valve, 114.
for horizontal marine engine, 394.
– injection valves, 443.
— regulator for locomotive steam pipe, 563.
Griffith's screw propeller, proportions of, 526.
Guard's whistle for locomotive, 576.
Gudgeon for rod of winding engine, 245.
pins, specification for locomotive, 735-
Guibal fan for mines, 6.
Guides and crosshead for double piston rod, 407.
Gutta percha ball valves, 214.
Gwynne's centrifugal pumps, 236.
H.
Haarlem Lake, draining of the, 239.
Hallside Works, rail-mill engines at, 291, and plate.
Hand gear for horizontal marine engines, 451.
for marine engines, rule for, 527.
- pump for horizontal marine engines, 448.
rail for locomotive, 578, 741, 743.
for American locomotive, 671.
Harness for locomotive springs, 639, 759.
Hastie's variable water-power engine, 315.
Hatchways, framing of ships', 815.
Haulage power of locomotives, 727.
Hawksley's formula for water pipes, 306.
Haystack boiler for river boats, 62.
Head light for American locomotive, 670.
stock for crank shaft, 356.
Heat, expenditure of, 63.
Heating surface, relative value of, 36.
for marine boiler, 63.
-- in locomotive, to find the, 755.
-plug valves for locomotive, 577-
Hercules, details of the, 910.
High boilers for royal navy, 56.
High-pressure beam engine, 251.
- geared pumping engines, 235-
--marine boilers, 58.
Hoists at landing stations, 327.
Hoisting gear for dredging vessel, 931.
for grain warehouse, 339.
Hold stringers in ships, 800.
Hopper for receiving grain, 338.
· barge, 930.
- dredger, combined, 936, and plate.
Horizontal high-pressure pumping engine, 200.
— marine engines, 385.
Horn blocks, specification for locomotive, 738, 744.
- plates for locomotives, 629.
Horse-power of land engines, to find the, 301, 309.
-- of marine engines, to find the, 510.
Hull of a ship, construction of the, 785.
terms applied to the, 894.
Hydraulic crane, 318.
- machinery for warehousing grain, 329.
- machine tools, 345, and plate.
Hyperbolic logarithms, table of, 141.
I.
Incandescent lamp, 1092.
Indicator diagram, the, 130.
from Corliss valve gear, 133.
from eccentric valve motion, 132.
Inflexible, constructive details of the, 912.
Injection pipes of marine engines, rules for, 524.
- valve for oscillating engine, 360.
for condenser, 443.
Injector for locomotives, 660, 741.
Internal pressure on cylinder, 126.
Iron and steel ships, Dr. Siemens on, 962.
Ironclad ships, 909.
Iron Shipbuilding, 766–966.
- ship, midship section of an, 896.
Iron roofs, construction of, 975.
coverings for, 980.
- scantling of, 994.
Iris, constructive details of the, 923.
Itata, details of the screw steamer, 498, 500.
J.
Jib of hydraulic cranes, 320.
Jiggers for loading and unloading, 344.
Joy's valve gear for compound locomotive, 697.
K.
Keels and keelsons, construction of, 786, 798, 877-
Keel blocks, 873.
Kingston valve, 361, 450, 528.
L.
Lagging for cylinder, 85, 161.
for locomotive boiler, 562, 669, 741.
- for marine boiler, 458.
La Gloire, French war ship, 909.
Lamp iron for locomotive, 741, 743.
Land Engines, 150-346.
— boilers, deterioration of, 48.
proportions for plain, 34.
Lap of the valve, 122.
Lateral strain, table of the breaking, 1094.
Laths, size and weight of iron, 996.
Lattice girder bridge, illustrations of, 1002, 1003.
construction of, 1015.
strains on, IOII.
―――over the Ohio, 1033, and plate.
Launching of large vessels, 901.
'Law of comparison' in shipbuilding, 782.
Lead of the valve, 96.
Leander, details of the, 927.
Leven, engine of the, 378.
Lifting set of pumps, 153, 192.
Lighthouses, construction of, 1058.
*
1116
INDEX.
Line shafts, fittings for, 1107.
Lines of vessels, laying down the, 770.
Lining pieces in ship's frame, 808.
Link motion, 100.
for horizontal marine engine, 393.
for oscillating engine, 374
for locomotive, 103, 587.
Links for parallel motion of blowing engine, 265.
Livadia, details of the, 73, 869.
Liverpool Docks, hydraulic machinery at, 329.
Lloyd's Rules, requirements under, 939.
-
tests for steel, 966.
Load of locomotive, to find the, 747.
Loaded beam, experiments with, 996, 1095.
— girder, experiments with, 10г1.
Loading safety valves by direct springs, 467.
Loam covering for boilers, 204.
Locomotive Engines, 530-765.
description of special, 698
Logarithms, table of hyperbolic, 141.
London drainage system, 226.
'Long-wall' in coal mining, 7.
Lord of the Isles, details of the steamer, 377, 803.
Lord Warden, war ship, 909.
Low boilers arranged for royal navy, 57.
Lowering of the propeller, plan for, 487.
Lubricating cups for horizontal marine engine, 398.
for oscillating engine, 365.
— plug tap for locomotive, 578.
Lubrication of horizontal marine engine, 451.
M.
Main beam of blowing engines, 258, 273.
cranks of oscillating engine, 357.
—
of winding engine, 246.
cranked shaft of marine engines, rule for, 521.
frame of marine engines, rules for, 522.
- framing for horizontal marine engines, 415.
- pillow blocks of winding engine, 246.
shaft of winding engine, 246.
slide valve of locomotive, 584.
- mast and yards, rules for, 889.
Mallet's compound locomotive engine, 694.
Manhole in marine boilers, 75.
Marine Engines, 347–529.
- boilers, proportions for, 62.
designing, principles of, 766
Masts, position of the, 887.
construction of iron, 821.
dimensions of, 956.
for merchant service, proportions of, 889.
terms applied to the, 898.
Mechanical stokers, 76.
Merkara, speed trials with the, 783.
Metacentre of a vessel, to calculate the, 854,
Mineral engine for Furness Railway, 717.
- lines, narrow-gauge engines for, 721.
Mining, coal, 1.
Mizen mast and yards, rules for, 892.
M'Naught's indicator, 131.
Models, construction and use of, 772, 778.
Modulus of rupture, 1001.
Moment of resistance, 1001.
Motion of steam, 144.
Motion bars of winding engine, 245.
of locomotive, 606.
of American locomotive, 675.
Moulding loft, work in the, 780.
Mud barges, scantling for, 960.
Multitubular boiler for ocean steamers, 52.
N.
Narrow-gauge engines for steep inclines, 720.
Nautilus, experiments with the, 384.
Navigable floating dock and battery, 973.
Nelson, war ship, 928.
Nominal horse-power, 510.
Northampton, war ship, 928.
Nozzle chest of blowing engine, 253.
valve chests, 163.
Nuts and bolts for locomotive engine, 742.
0.
Ocean steamers for passengers, 767.
Opening of port by valve, 124.
Orient, details of the, 865, and plate.
Oscillating engine, 347.
Outside cranks for locomotive, 625.
Overhead beam blowing engine, 250.
pumping engine, 183.
flue boilers, arrangements of, 54
Overshot water wheel, 317.
P
Packing ring for condensing tubes, 426.
for locomotive piston, 596.
Paddle wheel, the, 378.
theory of the position of the, 863.
Pallas, war ship, 909.
Parallel motion of blowing engine, 265.
Parallelogram of forces, the, 1102.
Parisian, details of the, 76, 496, 802, and plate.
Passenger engine for Caledonian Railway, 698,
and plates.
for London and North-Western Railway, 703.
for North British Railway, 705.
for Great Southern and Western Railway of
Ireland, 710.
Performance of locomotives, tables of, 711, 712, 714.
Perkins system of boiler, 19.
Phaeton, details of the, 927.
Pillar safety valves for locomotive, 570.
Pillars for ship's beams, 801.
Pillow block for paddle wheel, 381.
blocks for blowing engine, 258, 261.
for screw shafting, 473.
Pipes for delivery of water, 306.
for pit pumps, 308.
- of marine engines, rules for the, 517, 528.
Piston of Cornish engine, 152.
of blowing engine, 252.
- cylinder, 258.
- of horizontal marine engine, 399.
- of oscillating engine, 357.
INDEX.
1117
Piston of marine engines, rules for the, 516, 523.
of winding engine, 244.
— speed of, 309.
of locomotive, 596.
specification for the, 735.
- of American locomotive, 675.
Piston rod of beam engine, rules for the, 311.
of horizontal marine engine, 405.
of oscillating engine, 358.
of marine engines, rules for the, 518.
of locomotive, 603.
specification for the, 735.
of American locomotive, 675.
Pit shafts, form of, 3.
work, examples of, 192.
Plate bridge, 1002.
Plate keel, joining of the, 792.
- stays, forms of, 87.
Plates, tables of strength of, 32.
tables of weight of, 33-
for shipbuilding, quality of, 785.
Plating girders, 1006.
Plating for floating docks, 971.
Plating of ships, 806, 870, 878.
diagonal system of, 878.
- intermediate break-bond system of, 878.
- of H.M.S. Hercules, 910.
- of H. M.S. Polyphemus, 930.
Plug tap for locomotive cylinder, 583.
Plunger and bucket pump combined, 156.
of pumps, 154.
Polyphemus, constructive details of the, 928.
Port, opening of steam, 124, 309.
of locomotive, to find the length of the, 753.
Portable engines, 764, and plate.
Portland Harbour, water power at, 328.
Post Boy, condenser of the Clyde steamer, 377.
Pot boiler, 14.
Power versus speed of a vessel, 511.
tonnage of a vessel, 511.
Power, mechanical means for transmitting, 1101.
Pressure, working and bursting, 28.
-cylinder of hydraulic crane, 318.
difference of, in boiler and cylinder, 146.
loss of, 146.
- on piston, 141.
- valve on water pipe, 226.
- in locomotive cylinder, rule for the, 746.
-
gauge for locomotive, 575.
for American locomotive, 670
Prevention of smoke, 544-
Priming, 78.
Prince Albert, war ship, 911.
Propeller, construction and forms of the, 471, 477.
Proportion of water to steam, 311.
Pulleys, rules for, 1106.
Pulsometer pump, the, 239.
Pump bucket for water-works engine, 219.
rods of Cornish engine, 152.
- valves for pumping engines, 213.
Pumping engine for drainage works, &c., 226.
for mines, 4, 150.
for water works, 202.
rules for the, 301.
Pumps for floating docks, 973.
Punching of plates, 71.
R.
Rail guards for locomotive, 648.
Rail mill at Dowlais Iron Works, 288.
- engines, compound reversing, 291.
Railway bridges, scantling and weight of, 1007.
Raising the screw propeller and shaft, 488.
Ram in war ships, 911.
'Rance' in coal mining, 7.
Rankine on the compound steam engine, 493.
Ratchet bolt for valve rings, 129.
Ratio of diameter of cylinder to stroke of piston in
locomotive, 753-
- of stroke of piston to diam. of driving wheels, 753-
Refrigerating machinery, 908.
- surface in condenser, 428.
Register tonnage, mode of calculating the, 842.
Regulators for locomotive steam pipe, 563, 732.
Relative volume of steam, to find the, 144.
Relief valve on delivery pipe, 225.
for horizontal marine engine, 396.
for oscillating engine, 363.
Reservoirs at water works, 211.
Resistance of trains, to find the, 746.
Return tubular boiler, 12.
Reverse angle irons, 797.
'Reverser' for ships' plates, the, 881.
Reversing gear of locomotive, 594, 736.
Revolving screws for discharging grain, 331.
Riding bitts, 819.
Rigging of a ship, terms applied to the, 898.
Rigging screw, 829.
Ring pump valves for waterworks engines, 209.
River boats for passengers, 766.
plans of, 770.
Rivetted joints, form and proportion of, 31.
Rivetter, portable hydraulic, 345, and plate.
for ships' keels, 345, and plate.
Rivetting of locomotive boiler, 554.
of ships' plates, 808, 878.
Rivets, table of length of, 905.
for ships, quality of, 809.
Road locomotives or traction engines, 762.
- rollers, steam, 765.
Rolling bars in two directions, 289.
- mill engines, 285.
Roofs for steam boilers, 980.
Roof of Great Northern Rail. Station, London, 989.
of Joint Railway Passenger Station, New Street,
Birmingham, 992.
of Railway Station, Cannon St., London, 984.
St. Enoch Railway Station, Glasgow, 993.
St. Pancras Railway Station, 984.
Ropes for winding engines, 239.
iron and steel wire, compared, 906.
Roslin Castle, plans of the ship, 894.
Round boilers, strength of, 30.
thickness of plates for, 69.
Rowan's form of piston, 403.
Royal Sovereign, war ship, 911.
Rudder, construction of the, 817.
Rules for beam engine, 310.
for marine engines, 510.
for pumping engines, 310.
1118
I
INDEX.
Rules for the locomotive engine, 746.
Ruthven's hydraulic propeller, trial of, 384.
S.
Safety valve, construction of the, 454.
openings, 462.
experiments with, 465.
for marine engine, rule for the, 528.
of locomotive, 567.
rules for the, 757.
specification for the, 732.
in American locomotive, 669.
Sails of a ship, 887.
terms applied to the, 900.
Sand box for locomotive, 649.
specification for the, 741.
of American locomotive, 671.
Saturated steam, heat of, 143.
rules for, 145.
-- table of properties of, 147.
Scale on steel plates, 72.
Scantling for a Clyde river boat, 225 ft. keel, 957-
-
154 ft. keel, 958.
for a small river boat on Thames, 958.
for small steel paddle steamer, 959.
for a dredger, 959.
for mud barges, 960.
for floating dock, 970.
for iron roofs, 994.
- for railway bridges, 1007.
Scotia, engines of the Cunard steamer, 377.
Scott-Russell's longitudinal system, 896.
Screw chain plates, 829.
- colliers, 768.
- propeller, construction of the, 471, 477.
rules for the, 525.
shafting, thrust collars, &c., rules for, 526.
vessels, performance of, 512.
Scum taps for marine boilers, 461.
Self-contained flue and tubular boilers, 12, 13.
Separator, the, 46.
for marine engine, 458.
Servia, details of the, 345, 415, 497 (and plate),
500, 868.
Setting out the valve faces, 125.
Shaft bearings, rule for, 1106.
Shafting for screw propeller, 471.
- strength of round, 1106.
Shah, speed trials with the, 783.
Shearing force on beam, 1001.
Shell of locomotive boiler, 554.
Shipbuilding, Iron, 766–966.
Ship resistance, elements of, 782.
Ships for carrying cargo, 768.
Side-lever engine for paddle steamer, 377.
links of parallel motion for Cornish engine, 151.
pumping engine, 187.
Siemens process of steel making, 961.
Silent blow-off nozzle, 470.
Simey's hand and steam steering gear, 907.
Sir Bevis, details of the, 501.
Sirius, description of the, 377.
Slide bars, specification for locomotive, 735.
- blocks, specification for locomotive, 735.
Slide valve, the, 94, 126.
for horizontal marine engine, 390.
gear for oscillating engine, 365.
of marine engines, power to move, 520.
—— rod of marine engines, rule for the, 519.
for locomotive, 102, 584.
specification for the, 736.
of American locomotive, 671.
Slip of the paddle, 383.
of the screw, 478.
Slip for launching large vessels, go1.
Sluices and piping for floating docks, 972.
Smoke box of locomotive, 558.
specification for the, 731.
of American locomotive, 667.
doors in marine boilers, 75.
— prevention, 43, 544.
Snifting valve for condenser, 445.
for oscillating engine, 362.
Sockets for standard water pipes, 307.
Solférino, French war ship, 909.
Spark arrester, specification for locomotive, 731.
Spars, dimensions of, 956.
Specification for locomotive engine and tender, 728.
for a screw steamer of 1767 tons, 940.
of 2000 tons B.M., 947.
of
790 tons B.M., 949.
collier of 1500 tons B. M., 954.
- for masts, spars, &c., 956.
Specific gravity of materials, 1099.
Speed of locom. piston, to find the maximum, 753.
―
trials by Messrs. Denny & Mansel, 783.
Splashers for locomotive, 650, 740.
Spring beam of blowing engine, 259.
Spring-loaded safety valve for locomotive, 569.
Springs for locomotive, 636.
rules for the, 759.
- specifications for the, 738, 744.
for American locomotive, 682.
Stability of a vessel, theory of the, 844.
'Stall and pillar' in mining, 7.
Stand pipes, 202, 211, 221.
Starting gear for marine engines, 110.
for oscillating engine, 372.
handle of winding engine, 243.
Stationary Engines, 150-346.
Stays for boilers, 29.
of suspension bridge, 1042, 1049.
Stay tubes in locomotive fire box, 541.
Staying of marine boilers, 65.
Steam, admission of, 94.
- expansion of, 141-149.
- properties of, 143.
treatment of, 79.
to find the motion of, 144.
-to find the relative volume of, 144.
to find the temperature of, 144.
-to find the total pressure of, 144.
to find the weight of, 144.
blast, mechanical action of the, 531.
- cylinder of blowing engines, 251, 269, 279, 282.
- engine, the early, 9.
jacket for cylinder, 85.
reducing valve, 47.
- regulating valve of blowing engine, 268
stop valve, 456.
Steam tightness in a piston, 403.
valve of oscillating engine, 349.
of winding engine, 242.
chest of locomotive, 555.
- pipe in locomotive boiler, 563.
pipes, specification for locomotive, 732.
pump for locomotive, 660.
- jet in American locomotive, 668.
pipe in American locomotive, 669.
road roller, details of the, 765..
- ship efficiency, Mr. Mansel on, 513.
— steering gear, 907.
Steam cranes, 1077, 1080 (and plate), 1081.
Steel boilers, 32.
for shipbuilding, 960.
Steeple engine for river boats, 377.
Steering gear, by hand and steam, 907.
'Step' in mining, 2.
Step grate för locomotive, 535.
Stern posts of screw vessels, 789.
tube for the screw propeller,. 475.
Stirling Castle, details of the, 869.
Stoup for valve motion of blowing engine, 254
Straight link motion for locomotive, 591.
Straightening, hydraulic machine for, 346.
Strains upon iron ships, 836.
- on an arched truss, 981.
- on a plain truss, 975.
- on wrought-iron girders, 996.
Strathleven, refrigerating machinery of the, 908.
Strength of iron ships, 834.
of materials, 1093.
Stringers on ship's beams, 802.
Stud for locomotive lamp, 578.
Stuffing box of horizontal marine engine, 388.
of oscillating engine, 349.
of marine engines, rule for the, 518.
Stythe' in mines, 4.
Sump' in mines, 157.
Superheaters, use of, 54.
-forms of, 80.
INDEX.
Surface condensation in marine engines, rules for,
524.
Surfaces, relations of, 65.
Suspension bridges, construction of, 1036.
Swing bridges, working of, 325.
constructive details of, 1061.
T.
Tank for water works, 217.
in locomotive tender, 687, 742.
- locomotives, 705, 717, 721.
-narrow-gauge locomotives, dimensions of, 724.
Tappets for shutting valves, 164.
Temperature of steam, to find the, 144.
Tempering of steel tools, 965, and frontispiece
Tender for locomotive, 684.
- specification for, 742.
for American locomotive, 688.
Tensile strength of wrought-iron plates, 1097.
Testing old boilers to destruction, 48.
l'ests for various forms of steel, 965.
Thomas-Gilchrist process of steel-making, 961.
Three-cylinder compound engines, 497.
1119
Three-cylinder compound steeple engine, 50%.
Throttle valve for horizontal marine engine, 395.
for oscillating engine, 364.
Throw of eccentric, 367.
Throwing off apparatus in discharging grain, 334-
Thrust of a propeller, Rankine's rule for, 384.
Thrust block for screw shaft, 473, 816.
Thunderer, constructive details of the, 911.
Tie plates in ships, 802.
Tonnage of a vessel, rule for, 512.
Tools, tempering of steel, 965, and frontispiece.
Topsides in iron ships, construction of, 810.
Torpedo boat, the, 928.
Torsion or twisting, 1096.
Total pressure of steam, to find the, 144.
Toulon Arsenal, hydraulic power at, 346.
Towers for suspension bridges, 1051.
Traction or road engines, 762.
Tractive power of locomotive, to find the, 746.
Transom plates in ships, 796.
Transverse bulkheads, 812.
- strength of bodies, 1094.
Travelling bands for carrying grain, 333, 341.
Trellis bridge, 1003, 1030.
Trestle trees for iron masts, 824.
Triangular bridges, 1002.
'Troubles' in coal mining, 2.
Trunk engines, 378, 492.
Trunnion blocks, 354.
— pipes for steam and exhaust, 348.
Trunnions of oscillating engine, 347.
Trusses for ship's yards, 827.
Tube area in marine boilers, 67.
stays, conical water, 88.
Tubes, surface and weight of, 34.
for surface condensers, 426.
arrangement of the, 430.
for locomotive boiler, 557.
specification for the, 731.
in American locomotive, 666.
Tubing, triangular and square systems of, 45.
Tubular boilers, forms of, 12, 13.
– girders, examples of, 1005.
Tunnels, submarine, 1056.
Turbine, the, 317.
Turning gear for horizontal marine engines, 453.
for marine engine, rule for the, 528.
for swing bridge, 1067.
Turret in war ships, 911.
Tweddell's hydraulic tools, 345, and plate.
Twin screw propellers, 481.
Tyres, specification for locomotive, 740, 745-
for traction engines, 762.
U.
Undershot water wheel, 317.
Underwriters' Registry tests for steel, 966.
Uptakes for marine boilers, 58, 60.
V.
Vacuum automatic brake, details of the, 691.
valve for marine boilers, 461.
1120
INDEX.
Valve, the slide, 94, 126.
without lap, 95.
with lap, 96.
- casing for horizontal marine engines, 392.
— faces, setting out the, 125.
gear, Corliss liberating, 295.
Cornish, 164.
of horizontal marine engine, 393.
of oscillating engine, 107, 371.
regulator for water works, 212.
spindle of blowing engine, 254.
motion of locomotive, 587.
specification for the, 736.
of American locomotive, 673.
Valves for blowing engine, 253.
for direct-acting horizontal marine engine, 109.
for high and low pressure combined engines, 102.
for hydraulic cranes, 318.
for marine engines, rules for, 517, 528.
for water pipes, 203.
Velocity of saturated steam, to find the, 145.
Ventilation of mines, 6.
Vertical boilers, various forms of, 13.
- compound engine, 495.
Vibrating engine, 347.
Volume of metals, table of, 964.
W.
Warrior, details of the, 909.
War ships, armoured and unarmoured, 909.
Waste-steam funnel for locomotive, 572.
Water, power required to pump out, 303.
weight and measurement of, 307.
pipes, thickness of, 307.
power from natural falls, 327.
pressure engines, 314.
for dock gates, 325.
tube boilers, 16.
wheels, 317.
works at Berwick-upon-Tweed, 217.
at Bromhills, Walsall, 221.
at Goldthorn Hill, Wolverhampton, 209.
at Tettenhall, Wolverhampton, 204.
gauge for locomotive, 573.
Water gauge in American locomotive, 669.
space in locomotive fire box, 534, 540.
tank in locomotive tender, 687.
required for given speed of locomotive, 754-
-ballast in ships, 831.
courses, construction of ship's, 796.
- line, best form of, 773-
--tight compartments in ships, 812.
Waterwitch, experiments with the, 384.
Wave formations, diagram of, 863.
Wave-line principle of construction, 773-
Webb's compound locomotive engine, 695
Wedging plates for iron masts, 826.
Weigh bar of locomotive, 594.
Weight of cast-iron pipes, 307.
of wrought-iron plates, 33.
of metals, table of, 964.
of steam, to find the, 144.
of railway bridges, 1007.
of woods and other bodies, 1099.
Westinghouse automatic brake, 690.
Wheels for locomotive, 622.
rules for the, 759.
specifications for the, 739, 744
for American locomotive, 678.
- rules for the teeth of, 1104.
Whistle for steam vessels, 461.
for locomotive, 576.
for American locomotive, 670.
Willunga dredger, dimensions of, 937.
Winches for ships, 1083.
Winding engine, the, 239.
for a pit at Niddrie, 250, and plate.
Wind pressure on bridges, 1045, 1054.
on chimneys, 1054.
—— on iron roofs, 987.
Wiper shaft of blowing engine, 254.
Woodburning American locomotive, 664.
Working pressure of boilers, 28.
Workmanship of locomotive boiler, 731.
Y.
Yards in ships, proportions for, 889.
'Yokes' in pumping machinery, 197.
THE END.
GLASGOW: W. G. BLACKIE AND CO., PRINTERS, VILLAFIELD.
UNIVERSITY OF MICHIGAN
3 9015 06708 6887

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