jones
XJ J\
atmospheric
railways
Pr ice j/ó
1 t f
1 690
1 jt
A
POPULAR SKETCH
of the
VARIOUS PROPOSED SYSTEMS
OF
ATMOSPHERIC RAILWAY,
demonstrating the applicability of the
mechanical properties of the atmo¬
sphere, as a motive power.
lElIustrateti by numerous lB,oots ßCuts.
BEING HUE
substance of lectures, delivered on the subject,
at the
ROYAL ADELAIDE GALLERY.
In the month of February, 1845.
with additions and corrections.
By the late Proprietor, ^
WILLIAM JONES, ESQ. ^
M.D. M.E.C.S. L.S.A. A.C.E. ETC. ETC.
LONDON:
SHERWOOD AND CO., 137, STRAND.
and
sherwood, gilbert, and piper, paternoster
row.
1845.
TF690
•Ti
LlUr,«,.l
BUREAU OF RAILWAY tC JI. ..„,0"
WASHI^TON. D. 0,
Û., f.e£W?, !•
^AY 1 10^3
PREFACE.
The frequent demands made by the nu¬
merous attendants of the Lectures on the
Atmospheric Railway, delivered at the Royal
Adelaide Gallery ; for some popular descrip¬
tion of its principle, and the absence of any
such publication, in a succinct and separate
form, have induced me to compile the fol¬
lowing brief sketch of this now all-engrossing
subject of public interest.
In its consideration I have carefully pe¬
rused and have drawn largely from " A
Treatise on the Adaptation of Atmospheric
Pressure, to the Purposes of Locomotion, on
Railways." By J. D'A. Samuda. London.
John Weale, 1841. Also, " Atmospheric
Railway and Canal Propulsion." By James
Pilbrow, C.E. London. John Weale, 1844 ;
vi PREFACE,
but am more especially indebted to a very
able article on the subject in the " British
and Foreign Review," of April, 1844. Art.
XI., embodying a review of—1. Report of
Lieut.-Colonel Sir Frederic Smith and Pro¬
fessor Barlow, to the Right Hon. the Earl of
Ripon, President of the Board of Trade, on
the Atmospheric Railway. Presented to
Parliament by command of Her Majesty.
London, 1842.
2. Rapport, addressé à M. le Ministre des
Travaux Publics, sur le nouveau mode de
locomotion, dit Système Atmosphérique.
Par M. Edmond Teisserenc. Paris, 1843.
3. Report on the Railroad, constructed
from Kingstown to Dalkey, upon the Atmo¬
spheric System, and upon the application of
this System to Railroads in general. By M.
Mallet. London, John Weale, 1844.
PREFACE. vii
5. The Atmospheric Railway. A Letter
to the Right Hon. the Earl of Ripon, Presi¬
dent of the Board of Trade, &c. By James
Pim, Jun., M.R.IA. London, 1841.
6. Observations on the Report of Lieut.-
Colonel Sir Frederic Smith, R.Ë., and Pro¬
fessor Barlow, on the Atmospheric «Railway.
By. T. F. Bergin, M.R.I.A. London, 1842.
to which, and to the publications therein
mentioned, I must refer such of my
readers as may be desirous of farther inves¬
tigating the subject; the plan of this work
being merely intended to give some popular
idea of the principle, rather than to enter
into an elaborate consideration of all the
arguments that may be adduced in favour or
against it.
For the purpose of giving to it additional
interest, several wood cuts have been added.
viii
PREFACE.
in the hope of rendering intelligible such
portions as might otherwise appear obscure
and insufficiently explained.
The whole question has, it is believed, been
considered with such a spirit of impartiality
and candour as is most consistent with the
character of an individual at the head of a
large establishment in London, having for its
object the investigation and dissemination of
useful knowledge; uninfluenced in his opinion,
having no personal interest to serve, and only
desirous ofj discovering and promulgating
truth.
Being about to retire from the proprietor¬
ship and management of this institution, I
feel it incumbent on me to avail myself of
this opportunity to express my sincere thanks
to the numerous friends and supporters who
have honoured it with their patronage during
PREFACE. ix
the past three years ; and in regretting that
the means at disposal have not been adequate
to the accomplishment of all the good that
might have been effected, yet I feel conso¬
lation in the knowledge of the fact that those
who have had the best opportunities of
knowing me, believe that my talents, humble
as they are, have been constantly, zealously,
and sedulously, employed, to the best of my
apprehension, in promoting the truest welfare
of the public; and that, however, much I
may be chargeable with weakness of under¬
standing, or error in judgment, nothing can
be imputed to my character which has the
slightest reference to an impure, dishonest,
or corrupt, intention.
Thus then I retire, not defeated, but tri¬
umphant ; defeated as regards the possession
of the usual reward of labour, the summa res
X PREFACE.
pecuniœ, but triumphant in the possession of
a bank of intelligence (derived from the
various resources, constantly brought before
me), which will, I trust, long continue to
honour the cheques I may have occasion to
draw upon it; hut more especially triumphant
in the possession of that habitual satisfaction
which is the glorious reward of constantly
striving to act an honest and an honourable
part; while I have yet the honour of sub¬
scribing myself
The Public's
Humble yet grateful servant,
WILLIAM JONES.
26, Park Lane, Piccadilly.
INDEX.
Page
Frontispiece
Title page
Preface v
Index xi
Explanation of frontispiece xvii
Introduction 1
Mechanical Properties of the Atmosphere . . 4
Weight 5
Elasticity 6
Condensibility 6
Expansibility 7
Papin's application 8
Taylor's original suggestion of the application
of the mechanical properties of the atmo¬
sphere, as a locomotive power 9
xii
INDEX.
Medhurst's suggestions No. 1 . .
Ditto ditto No. 2 . .
Ditto ditto No. 3 ..
Ditto ditto No.4
Vallance's plan
Pinkus's ditto
Diagram thereof
Clegg and Samuda's
Diagram 2, representing section of the tuhe
on this plan
Diagram 3, showing the oblique armature of
the piston
Diagram 4, showing the form of the piston
rod
Mode of action of Samuda's system
Diagram 5, showing the mode of connecting
the piston with the train
Samuda's description
Diagram 6, showing the equilibrium or
entrance valves
Mode of stopping
Application of a fall of water, in lieu of
stationary engines and air pumps
11
12
13
14
14
15
16
17
20
22
23
24
25
28
31
33
34
INDEX.
Xlll
Diagram 7, showing the mode of connecting
the travelling tubes with the stationary
engines and station houses 35
Diagram 8, showing the mode of junction
of other lines 36
Mere weight of atmosphere hitherto employed 36
Pilbrow's patent 37
Absence of long valve 38
Diagram 9, showing vertical section of tube
on Pilbrow's plan 39
Diagram 10, showing the application of cogs
and pinions to the piston rack 40
Modification of piston 41
Diagram 11, showing a vertical section of
tube, with projecting and prolonged pinions 42
Mode of action, Pilbrow's description 43
Diagram 12, Hallette's lip valve 49
Hay's modification 50
Advantages of the atmospheric railway .... 51
Original formation 51
Diagrams 13 and 14, showing the inclines
and curves traversed on the Dalkey exten¬
sion of the Dublin and Kingston Railway 53
XIT
INDEX.
Applicability of the atmospheric system to
common turnpike roads 54
Relative first cost 54
Relative costs of working 57
Parliamentary report thereon 59
Economy effected by the employment of gra¬
dients 60
Inapplicability of the Steam Locomotive to
steep gradients 61
Table showing the gross load in tons which a
locomotive engine capable of evaporating
sixty cubic feet of water per hour will drag,
exclusive of the tender, at different rates of
speed, on different inclinations of planes. . 63
Cause of loss of power from increased veloci¬
ties on the ordinary locomotive system. ... 64
Cause of velocity on the atmospheric system,
and superiority of the patent of Pilbrow
in this respect 64
Power exactly proportioned to the power re¬
quired on the atmospheric system 65
Report of Monsieur Teisserenc thereon .... 65
Velocity capable- of being obtained on the at¬
mospheric system _67
Comparative safety of the atmospheric system 68
INDEX.
XV
Principal causes of accident on the ordinary
locomotive system 72
Opinion of Möns. Mallet thereon 73
Recommendation of the atmospheric principle,
by I, K. Brunei, Esq 75
Advantages of Pilbrow's patent 76
Patentee's description thereof, in construction 76
Ditto, in safety 79
Ditto, in simplicity 80
Ditto, in first outlay 81
Cheapness in working 83
Observations on Pilbrow's statement 85
Applicability of exhaustion and compression,
and consequently all the mechanical proper¬
ties of the atmosphere, by this system .... 86
Fate of present railroads 87
Samuda's remarks thereon 88
Smaller fares and larger profits, by the amo-
spheric system 91
Calculation in reference thereto, showing that
a greater profit would be realized at 5s. per
head and 6s. 3d. per ton for goods, from
London to Birmingham, by the atmospheric
system, than can be obtained by the present
system, at 25s. per head and 40s. per ton 93
xvi
INDEX.
Proved by dismissal of useless weight, and
saving in fuel, &c. 95
Still greater diminution capable of being
eifected by Pilbrow's patent 97
Advantages of penny trains 97
The public largely indebted to Messrs. Clegg
and Samuda 98
Appendix.—Parliamentary Report of the Com¬
mittee of the House of Commons 101
EXPLANATION OF FRONTISPIECE.
Fig. 1 represents the mode of connecting the
travelling piston, with the train of carriages, on
Pilbrow's system, in which d. represents the
square compartment, containing f. the cogged
piston-rack ; c. is the main tube, containing the
cylindrical piston, of which e. is the head; g. re¬
presents the armature, connecting the piston with
its rack ; h. represents the lower cogs of the
pinion, projecting into the square compartment d. ;
i. is the spindle, connecting the lower cogs with
the upper cogs k. ; L is the carriage rack, running
between them and through them, receiving the
motion of the piston-rack.
In fig. 2, the same letters are used to express
the same portions of the apparatus ; where it will
be seen that the racks, both of the piston f. and
carriage, are no longer cogged, hut obliquely
xviii EXPLANATION, ETC.
grooved, to catch in passing the projecting por¬
tions of the spiral threads in the pinions h.k., as
described in p. 43 ; m. is a prolonged lever, pro¬
jecting from the centre n., intended to be pressed
downwards by the under surface of the carriage-
rack, in its passage, so as to open a valve at o. and
allow the atmospheric air to enter immediately
behind the piston.
THE
ATMOSPHERIC RAILWAY.
The present century, more than any other, has
been charaeterized by the remarkable development
of human ingenuity and mechanical contrivance,
exemphfied in the numerous inventions, which,
under the sanetion of patent, have laid claim to
public patronage. Foremost amongst these are
the appliances of steam, and more especially the
railway. Twenty years have not yet elapsed since
the first application of steam to locomotive power
was brought into action. The Liverpool and
Manchester line was opened to the public Septem¬
ber 15, 1830, when, as it will be recollected, that
great and enlightened statesman, Mr. Huskisson,
became its victim. Since that period upwards of
^100,000,000 sterling have been embarked in
railway speculation in the United Kingdom, and
a mania for this species of monopoly is daily on
b
2
the increase, not only in Great Britain, but
throughout both the continents of Europe and
America. In November last, upwards of one
hundred applications for new railroads was sub¬
mitted to the Board of Trade, in London. In
the present session of the Chamber of Deputies,
in Paris, thousands of millions of francs have
been voted to the Minister of Public Works,
to carry out the numerous proposed railroads in
that kingdom. Eussia, Austria, and Germany,
are also spending their millions sterling in the
same cause, and, in all probability, ere the close
of the present century, Europe, in every depart¬
ment, will be intersected by this means of com¬
munication. Who can contemplate these vast and
stupendous undertakings without awe, admiration,
and gratitude ; without reflecting on the immense
advantages which such facilities of intercourse,
the consequent interchange of commodities, and
collision of intellect between the inhabitants of
different nations of the earth, must ultimately
confer on the great family of man.
It is a fact, which is daily gaining ground among
mankind, that it is impossible for a single disco-
3
very to be made in any of the physical sciences,
for a single blade of grass to spring up more
readily under the application of greater agricul¬
tural knowledge, or any new motive power to be
advantageously applied to mechanical science,
without a consequential benefit extending through¬
out the whole chain of civilization ; and how much
more potent does this argument become when
aided by the rapid facilities of intercourse afforded
by the railroad. The invention and successful
application of such a power as the steam engine
locomotive might appear sufficient for one age,
did we not know that it is the characteristic of
power to multiply itself, and that every new dis¬
covery acts only as an incitement to fresh efforts
of inventive genius. What is done is great!
What is to be done is greater far I Fresh hours
demand fresh energies, new means beget fresh
wants, and these again are the stimuli to those
whose task it is to provide for them. In the pre¬
sumed self-sufficiency of present means we look
back on the puny efforts of our ancestors, and
can scarcely believe it possible that an age could
have been so ignorant as to have condemned to
4
perpetual imprisonment, as a lunatic, the genius
which foresaw the vast and important objects
capable of being effected by the application of
the mechanical properties of steam.* May not
future ages look back upon our present exertions
with the same wonder at our ignorance, may not
a similar self-suiRciency and self-complacency, to
that which we now manifest, be held by them
when they shall have developed and successfully
applied numerous inventions as yet unknown and
buried in the womb of time. For upwards of
five thousand years (since the creation of the world)
mankind has had at disposal, and constantly sur¬
rounding him, means far more powerful than any
that ever could be realized by the application of
steam, viz., the atmosphere, whose mechanical
properties are now being, for the first time, suc¬
cessfully applied to the comfort and conveniences
of life, in the facilitation of human intercourse.
The question which naturally suggests itself to
the mind is, what are the mechanical properties
of the atmosphere ? The answer is, weight and
• Soloman dc Caus was imprisoned.
5
elasticity. First, as regards the weight of the
atmosphere : a pint of this elastic fluid weighs
14 grains, and forming a halo as it were around
our globe, it presses equally on all bodies with a
pressure equal to 141bs. on every square inch, is
capable of supporting a column of mercury 30
inches in height, and a column of water 34 feet.
It is true we do not feel the atmosphere pressing
on our bodies with a weight equal to 141bs. on
the inch, because it presses equally in every direc¬
tion, and consequently the weight on the anterior
portion of the body is compensated by that on
the posterior portion ; and so in an ordinary glass
bottle, the pressure is equal on the inside of the
glass and on the outside, but if you attach a
bottle by a stop cock to an air pump, and exhaust
the air therein contained, it is immediately crushed"
into a thousand pieces by the pressure of the
atmosphere on its outer surface. Again, if you
take a glass tube 30 inches in length and exhaust
the air therein contained and invert it into mer¬
cury, the pressure of the atmosphere on the
surface of the mercury immediately drives up the
mercury and fills the tube. In the ordinary M ater
B 3
6
pump on exhausting the air on the surface of the
water contained in the tube in which the sucker
or piston rests, the pressai e of the atmosphere
on the water surrounding that tube, drives the
water into the tube to the height of 34 feet. It
is not therefore the sucker which draws up the
water, as believed by the vulgar, but the pressure
of the atmosphere which forces the water into the
vacuum caused by the exhaustion of the air
within the tube. Next as regards its elasticity.
In consequence of this property it is capable of
being compressed under pressure, of expanding
when that pressure is removed. It is also capable
of expansion under the application of heat, and
of being condensed when that heat is removed.
As a proof of its compressibility, we may men¬
tion, that a vessel which ordinarily contains one
volume of air, may, if sufficiently strong, be
made to contain one hundred or two hundred
volumes, on which principle is formed the air
gun. In this illustration, the air so compressed
on the valve being open for its exit, rushes out
with great impetuosity by its expansibility, carrying
with it the bullet or charge in its course. It is
7
the law with all gaseous bodies that they expand
or contract of their volume for every degree
of heat imparted, or abstracted therefrom ; so
that one volume of air at a temperature of one
degree, would fill double the space at the tempe¬
rature of 480 degrees, or vice versa ; and in the
same way a vessel containing 100 volumes of
atmospheric air at a temperature of 480 degrees
would contain 200 volumes, under the same pres¬
sure, at a temperature of only one degree ; and
by allowing this 200 volumes of air, at a tempe¬
rature of one degree, to escape through a tube
heated to 480 degrees, it would expand to 400
volumes, by the application of that 480 degrees of
heat, and as each volume of atmospheric air
presses on the surface of bodies with a power
equal to 141bs. on the square inch, and as 400
X 14 = 5,600, a power equal to 5,6001bs. on the
square inch will be thereby generated.—A mecha¬
nical power in all probability so great as never to
be " fully" employed by human means.
With such a mechanical agent ever at command,
is it not wonderful that it should have remained
for the present age to apply its enormous power.
8
and even now to be satisfied with only a modicum
thereof, viz ; its mere weight ; as in the application
of atmospheric pressure, obtained by the exhaust¬
ing power of the air pump. Mr. Papin, in the
year 1654, originally suggested employing atmo¬
spheric pressure against a vacuum as a motive power»
and the system was adopted in Nieucomem's Steam
Engine, now obsolete, but not for the purposes of
locomotion. According to the learned Editor of
" The British and Foreign Review," * "Thefirst
idea of employing the power of air in land
carriage occurred to a gentleman, at Manchester,
Mr. Taylor, (the inventor of the first power loom,)
in 1805. In conversation with two friends, Mr.
Duckworth and Mr. Clegg, the subject was dis¬
cussed, and, although these gentlemen were all of
opinion that the idea was capable of being realized,
the means of accomplishing their object was so
surrounded with difficulties, that the subject was
ultimately dropped, without any steps heing taken,
or experiments made. The plan proposed was in
principle the same as that which is now in suc-
* No 33, April 1844, Article XI.
9
cessful operation, in Ireland, on tlie Dalkey
extension of the Dublin and Kingston Line. Mr.
Taylor's scheme only extended to the conveyance
of letters and despatches ; he suggested that a
tube, large enough to contain a parcel, should he
laid down from one town to another : at these
places a stationary steam engine should be erected,
which should exhaust the tube.
The parcels being placed in the tube at one end,
and the latter exhausted by the engine at the other,
the pressure of the air would carry the contents
of the tube along with immense velocity : at each
station, or town, the letters or parcels intended
for that district would he taken out, and the rest
forwarded to their destination.
In 1810, Mr. George Medhurst, an engineer in
London, published a pamphlet, in which he pro¬
posed " A New Method of conveying Goods and
Letters by Air," and in 1812 he published his
calculations and remarks on the practicability of
his scheme.
In 1827, he printed another pamphlet, entitled
" A new System of Inland Conveyance, for Goods
and Passengers, capable of being applied and
10
extended throughout the Country, and of con¬
veying all kinds of Goods, Cattle, and Passengers,
&e," in which, not confining himself to the mere
weight or pressure of the atmosphere, he suggests
four applications of its mechanical properties to
purposes of travelling, which are thus descrihed
in his own words,—first ; " In order to apply this
principle to the purpose of conveying goods and
passengers from place to place, a hollow tuhe, or
archway, must he constructed, the whole distance,
of iron, hrick, timber, or any material that
will confine the air, and of such dimensions as
to admit a four-wheeled carriage to run through
it, capable of carrying passengers, and of strength
and capacity for large and heavy goods. The tube,
or aërial canal, must he made air-tight, and of the
same form and dimensions throughout, having a
pair of cast iron or steel wheel tracks, securely laid
aU along the bottom, for the wheels of the car¬
riage to run upon ; and the carriage must he nearly
of the size and form of the canal, so as to prevent
any considerable quantity of air from passing by it.
If air he forced into the mouth of the canal, behind
the carriage, by an engine of sufficient power, the
Il
carriage will be driven forward by the pressure
of the air against it ; and if the air be continually
driven in, the pressure against the carriage, and
consequently its motion, will be continually main¬
tained. When the carriage is to go through the
canal from the engine, the air must be forced into
the canal behind it ; but when it is to go the
contrçlT3^way, the same engine is to draw the air
out ¿Í the canal, and rarify the air before the
carriage, that the atmospheric air may press into
the canal behind the carriage, and drive it the
contrary way."
In this scheme it will be seen that Mr. Medhurst
did not confine himself to the mere weight of the
atmosphere acting as a motive power, against a
vacuum, but rather proposed to employ its elasticity
and consequent compressibility, as exemplified in
the air gun ; and it would appear to have immedi¬
ately occurred to him that few travellers would
adopt a mode of conveyance, wherein they should
form as it were part of the charge of an air gun, or
the pellet of a pop gun, to be driven forward with
any velocity that compressed air might be capable
of imparting ; for in his next suggestion, he says.
12
" Suggestion, No. 2." It is practicable upon the
same principle to form a tube so as to leave a
continual communication between the inside and
outside of it, without suffering any part of the
impelling air to escape ; and by this means to
impel a carriage along upon an iron road, in the
open air, with equal velocity, and in a great
degree possessing the same advantages as in passing
withinside of the tube, with the additional satis¬
faction to passengers of being unconfined, and in
view of the country. If a round iron tube,
24 inches in diameter, be made with an opening
of 2 inches wide in the circumference, and a flanch
6 or 8 inches deep, on each side of the opening,
it will leave a channel between the flanches, and
an opening into the tube. If such a tube is laid
all along upon the ground, with the iron channel
immersed in a channel of water, and a piston or
box made to fit it loosely, and pass through it upon
wheels or rollers, this box, driven through the
tube by the air forced into it, may give motion to
a carriage without, by a communication through
the channel and the water. No air can pass out
of the tube while the channel is immersed in
13
water, unless the air be of such density as to force
the water out of the channel, and then the air will
follow it and escape ; but there is an opening made
for a bar of iron to pass from the running box in
the interior of the tube, to which a rod or crank
may be brought from the carriage in the open air,
and from that receive its motion.
His third suggestion was as follows :—
" A plan to combine the two modes together,
that the goods may be conveyed within the canal,
and a communication made from the inside to the
outside of it, so that a carriage may be impelled in
the open air, to carry passengers, would be an im¬
provement desirable and practicable. It must be
effected without the aid of water, so that it may
rise and faU as the land lies ; and it must give a
continual impulse to the outside carriage, without
suffering the impelling air to escape. For this
purpose there must be some machinery which
will diminish the simplicity, make it more expen¬
sive, and more liable to be disordered, unless exe¬
cuted in the most substantial and perfect manner,
but by skill, experience, and sound workmanship,
it may be accomplished in various ways."
c
14
Mr. Medhurst's fourth ideáis thus described:—
" The same principle, and the same form, may
be advantageously applied to convey goods and
passengers in the open air, upon a common road,
at the same rate of a müe in a minute, or sixty
miles an hour ; and without any obstruction, ex¬
cept at times contrary winds, which may retard
its progress, and heavy snow, which may obstruct
it. If a square iron tube be formed two feet on
each side, four feet in area, with three sides, and
one half of the top of cast iron, the other half of
the top made of plate iron or copper, to lift up
and shut down in a groove in the cast iron semi-
top plate, as before described, this arm may give
motion to a carriage in the open air, and upon the
common road, without any railway, if the pressure
within the tube is made strong enough for the
purpose."
Previous to Mr, Medhurst's second tract, in
1827, from which these extracts have been drawn,
a patent was taken out by Mr. Vallance, in 1824,
for a plan of locomotion by atmospheric pressure.
This was merely a modification of Mr. Medhurst's
first suggestion of exhausting a tunnel large
15
enough to contain a train of carriages : a stationär)
engine was to be erected at one end of this tunnel,
which it was supposed would create a sufficient
vacuum for the pressure of the air acting on a
piston, attached to the first carriage, to impel the
whole train forward. A model of this railway was
exhibited at Brighton, but this was the extent of
its application.
March 16, 1834, Mr. Pinkus obtained a patent
for a pneumatic railway, which was, however, con¬
trived on a plan precisely similar to that published
in Medhurst's fourth suggestion, excepting that
he proposed to use a rope for the continuous
valve, and substitute a cylinder for a square tube.
To use his own words, " A flexible cord lies in
the groove, at the top of the cylinder, for the pur¬
pose of closing the longitudinal aperture : this
cord is to be of the same length as the pneumatic
railway, and to fit tightly into the groove or
channel."
In 1836 he took out a new patent, in which he
says, " The method of carrying it into practice
consists in a method, or in methods, of construct¬
ing the pneumatic valve, and the valvular cord.
16
and in the manner of using the same, one of
which methods, hereinafter described, I design to
substitute for, and in lieu of, the valve and cord
described in the specification of my said former
patent." In this second patent, as in the former,
a rope made of oakum, saturated with tallow, or
some other unctuous substance, was intended to
close the valve, and communicate the motion of
the piston, effected by atmospheric pressure on it,
against a vacuum, by means of a perpendicular
armature to tbe first carriage of the train, the
valve being raised by means of a friction roller,
immediately in fronl of the armature, and closed
by a second roller, immediately after the piston,
as seen in the following diagram No. 1, where a a.
represents a tube exhausted, in front of h. the
piston ; c. is the perpendicular armature of the
piston communicating its motion to the train of
17
carriages ; d d. is the- rope valve, formed of
oakum and tallow ; e. the friction roller raising
the valve in front of the armature of the piston ;
and f. the second friction roller, closing the valve
after the passage of the perpendicular armature.
In practice it was found that this valve, being
elastic, was incapable of rendering air-tight the
exhausted tube, for the pressure of the atmosphere
on the surface of the valve, forced the elastic sub¬
stance into the tube, destroyed its vacuum, and
prevented the onward progress of the piston, and
it remained for Mr. Clegg to develop a valve pos¬
sessing sufficient elasticity to render the tube air¬
tight, and at the same time sufficient solidity to
resist the pressure of the atmosphere, which was
happily accomphshed by the patent taken
out by him, on the 3d of January, 1839. The
principal feature of this invention consists in " A
method of constructing and working valves, in
combination with machinery, to be applied to
railways, or other purposes, by a line of partially
exhausted pipes, for the purposes of obtaining a
direct tractive force to move weights, either on the
railway, or otherwise." And is thus explained in
c 3
18
the following extract from Mr. Clegg'a specifica¬
tion. " My improvements consist in a method of
constructing and w^orking valves in combination
with machinery. These valves work on a hinge of
leather, or other fiexible material, which is practi¬
cally air-tight, (similar to the valves usually used in
air pumps,) the extremity or edge of these valves
is caused to fall into a trough, containing a com¬
position of bees' wax and tallow, or bees' wax and
oil ; or any substance, or composition of sub¬
stances, which is solid at the temperature of the
atmosphere, and becomes fluid when heated a few
degrees above it. After the valve is closed, and
its extremity is laying in the trough, the tallow is
heated sufficiently to seal up, or cement together,
the fracture round the edge or edges of the valve,
which the previous opening of the valve had
caused; and then the heat being removed, the
tallow again becomes hard, and forms an air-tight
joint, or cement, between the extremity of the
valve and the trough. When it is requisite to
open the valve, it is done by lifting it out of the
tallow, with or without the application of heat,
and the before-named process of sealing it, or ren-
19
dering it air-tight, is repeated every time it is
closed. This combination of valves with machinery
is made in the application of these valves to rail¬
ways, or other purposes, hy a line of partially
exhausted pipes for the purposes of obtaining a
direct tractive force to move weights, either on the
railway or otherwise.
In the formation of this valve to obtain the
necessary degree of density to resist atmospheric
pressure, and sufficient elasticity to attach it
closely to the exhausted tube, a double series of
iron plates, connected by leather, are employed,
and the tube, although circular in the centre, has
a prolongation of metal, or lip on each side of its
upper surface, and the tube is not of the same
thickness throughout, but has an accumulation of
metal also in its lower portion, to prevent that
tendency to spring open which might occur were
the tube of equal thickness in all its parts, as
seen in the following diagram. No. 2, representing
a vertical section of the tube :—
20
Where a. represents the circular aperture of the
tuhe, which is filled up by the head of the piston
as it travels ; b. the thickened hase of the tube ;
c. the thinner portion of the tuhe ; d. the outer
lip on the upper surface of the tuhe, to which the
valve is attached; c. the inner lip, forming a
groove for the lodgment of the unctuous substance
destined to seal the valve ; f. the valve itself;
composed of g. the larger plate of metal ; and A.
the smaller plate of metal, which two are con¬
nected by means of i., the intervening leather,
prolonged towards the outer lip, forming a hinge
for the valve at k. The internal surface of the
21
tube A. being properly prepared by a coating ot
tallow, a travelling piston made air-tight by leather
packing is introduced therein, and is connected to
the leading carriage of each train, by an iron
plate, or armature, passing through the aperture
f. under the valve. A very important modification
of this armature, as compared with that of Pinkus's,
is employed by Messrs. Clegg & Samuda ; by refe¬
rence to diagram No. 1, it wiU be seen that the
armature in Pinkus' patent is perpendicular, and
consequently were a similar armature employed
with the valve of Clegg & Samuda, it would be
necessary to lift that valve to an angle of 85 or
90 degrees, to allow the onward passage of the
piston ; thus producing constant strain on the
hinge, and its consequent immediate destruction ;
to obviate this inconvenience, Clegg & Samuda
make the armature of their piston to pass diago¬
nally, or almost horizontally, from the exhausted
tube, so that the valve is never raised to an angle
of more than 45 degrees, and has consequently
a tendency to fall by its own weight, and close the
longitudinal aperture in the tube after the piston
22
has passed, as seen in the following diagram.
No. 3
Where a a. represents the circular aperture of the
tube; b. the armature of the travelling piston,
with its diagonal direction ; c. the valve raised to
an angle of 30 degrees ; d. the groove for the lodge¬
ment of the unctuous substance ; e. the foul
weather covering, raised by the armature of the
piston during its passage onwards, and falling
after the closing of the valve over the groove, d.
containing the unctuous substance, to protect it
from the influence of snow, rain, and other in-
clemêncies of the season. The iron armature
23
being fixed to the travelling piston within the pipe,
and also to the leading carriage of the train, con¬
nects them together. Diagram No. 4, represents
24
the form of the travelling piston, where a. is the
piston head, i. the compensating balance, hhhh.
four vertical wheels intended to lift up the valve,
and allow the atmospheric pressure to enter
immediately behind the piston head ; k. is the
point at which the armature of the piston is
attached to this rod.
Diagram No. 5. represents the mode of con¬
necting the piston rod with the first carriage in
the train, by means of the armature at k. pro¬
ducing the motion of the train, r. is a roUer of
which there are two attached to the posterior
portion of the carriage, intended to close down
the valve after the passage of the armature, and
leave the pipe in a fit state to be again exhausted
of its air, while n. is the heating apparatus travel¬
ling behind the whole and liquifying the unctuous
substance so as to seal the valve.
The internal surface of the pipe being properly
prepared by a coating of tallow, and rendered air¬
tight by the closure of the valve and its travelling
piston, if a part of the air be withdrawn from
that length of pipe in front of the piston, by an
air pump, a certain amount of atmospheric près-
25
Diagran'i No. 5.
26
sure on the back of the piston will take place,
proportionate to the vacuum produced. If a per¬
fect vacuum be effected, a pressure of 141hs. on
the square inch will he produced behind the tra¬
velling piston ; hut it will he found much more
advantageous in practice say the inventors to pro¬
duce an exhaustion of air in the pipe equal to
causing a pressure from the atmosphere, of 81bs. on
the square inch only, by which means considerable
power wUl always he left at disposal. Supposing
the main pipe to be of 18 inches internal dia¬
meter, it will receive a piston of 254 superficial
inches area, on which, with the above pressure, a
tractive force of 2,0321hs. is consequently ob¬
tained ; and this is capable of propelling a train
weighing 45 tons, (or eight to nine loaded car¬
riages,) at the rate of thirty miles an hour, up an
acclivity of 1 in 100, or 53 feet per mile. Two
and a half miles of pipe, say the patentees, will
contain 23,324 cubic feet of air, -g-fths of which,
or 12,439 cubic feet, must he pumped out, to effect
a vacuum equal to 81bs. per square inch ; the air-
pump for this purpose should be 5 feet 7 inches
diameter, or 247 feet area, and its piston should
27
move through 220 feet per minute, thus discharg¬
ing at the rate of 24.7-1-220=5,434 cubic feet
per minute at first, and at the rate of 2,536 cubic
feet per minute, when the vacuum has advanced
to 16 inches mercury, or 81bs. per square inch;
the mean quantity discharged being thus 3,985
feet per minute; therefore VsW =3.1 minutes,
the time required to exhaust the pipe ; and as the
area of the pump-piston is 14 times as grerft as
that of the former, or 220 feet per minute -|-14 =
3,080 feet per minute, or 35 miles per hour. But
in consequence of the imperfect action of an air-
pump, shght leakages, &c., this velocity will be
reduced to 30 miles per hour, and the time requi¬
site to make the vacuum increased to four minutes :
the train will thus move over the 2^ miles section
in five minutes, and it can be prepared for the
next train in four minutes more—together nine
minutes; 15 minutes is therefore ample time to
allow between each train ; and supposing the
working day to consist of 14 hours, 56 trains can
be started in each direction, or 2,520 tons,
making a total of 5,000 tons per day. The fixed
engine to perform this duty wUl be 110 horses'
28
power, equivalent to 22 horses' power per mile in
each direction.
The following description of railway is borrowed
from Clegg and Samada.* On this system of
working railways the moving power is commu¬
nicated to the train by means of a continuous
pipe or main, laid between the rails, and divided
by separating valves into suitable and convenient
len'gths, for exhaustion. A partial vacuum is
formed in this pipe, either by steam-engines and
air-pumps, fixed at intervals along the road, or by
water power, if the nature of the country be such
as to afford it. These valves are opened by the
train as it advances, without stoppage, or reduc¬
tion of speed. A piston which is made to fit
air-tight, by means of a leather packing, is intro¬
duced into the main pipe, and connected to the
leading carriage of each train, by an iron plate
which travels through a lateral opening the whole
• A Treatise on the Adaptation of Atmospheric
Pressure to tlie purposes of Locomotion on Railways,
hy J. D'A. Samada.— London, 1841, Weaie, High
Holborn.
29
length of the pipe. This lateral opening is
covered hy a valve extending the whole length,
formed of a strip of leather rivetted between iron
plates ; the top plates are wider than the groove,
and serve to prevent the external air forcing the
leather into the pipe when the vacuum is formed,
the lower plates fit the groove when the valve is
shut and making up the circle of the pipe, pre¬
vent the air passing the piston : as shewn in the
diagrams. One edge of this valve is securely
held down by iron bars, fastened by screw bolts,
to a longiludinal rib d. cast on the pipe on one
side of the lateral opening, and the leather between
the plates and the bar being flexible, forms a
hinge as in a common pump valve ; the other edge
of the valve falls on the surface of the pipe on
the opposite side of the opening, thus forming
one side of a trough d. as shewn in figure 3.
This trough is filled with a composition of bees'
wax and tallow, which substance is solid at the
temperature of the atmosphere, and becomes
fluid when heated a few degrees above it. This
composition adheres to the edge of the valve,
which forms one side of the trough, and to that
D 3
30-
part of the pipe which forms the other, and pro¬
duces perfect contact between them ; hut as the
piston advances, the valve must he raised to
allow the connecting plate to pass ; and this is
effected by four wheels H. H. H. H. fixed to the
piston rod behind the piston, and the ^aperture
thus formed serves also for the free admission of
air to press on the back of the piston, by this
operation of raising the valve out of the trough,
the composition between it and the pipe is broken,
and the air-tight contact must he re-produced. To
effect this another steel wheel R. is attached to
the carriage, regulated by a spring which serves
to insure the perfect closing of the valve by
running over the top plates immediately after the
arm has passed, and a copper tube or heater N.
about five feet long filled with burning charcoal is
also fixed to the under side of the carriage, and
passes over and re-melts the surface of composition
which has been broken by lifting the valve, and
which upon cooling becomes solid, hermetically
sealing the valve as before. Thus each train in
passing leaves the pipe in a fit state to receive the
next train. A protecting cover formed of thin
31
plates of iron about five feet long, hinged with
leather, is placed over the valve, and serves to
preserve it from snow or rain ; whieh eover is
raised by wheels fixed under the carriage, as it
passes.
The " exit" separating valve, or that, at the
end of the seetion nearest to its steam engine, is
opened by the compression of air caused by the
piston after it has passed the branch whieh com¬
municates with the air punip.
Diagram 6 is the equilibrium or " entrance"
separating valves. The arrow denotes the direction
in whieh tiie trains advance. The pipe is exhausted
on the side of the valve lettered C. and is only
32
prolonged on the other side to allow the piston to
enter the pipe before the valve is opened. Attached
to one side of the main is a semicircular box,
B. A. divided into two compartments by a par¬
tition, of which a. a. a. is a sectional view, and
through which is a circular opening : in the top
of the box are two small square holes, one on each
side of the partition, furnished with a box slide,
by which either, or both of them, may he covered
at pleasure; within the box B. A. are two valves h.
and c. (of which 6. is the greater) connected by
an arm d. d. to each other, and to a vertical axis e.
on which they can swing horizontally, or about
100 degrees. When the pipe is to he exhausted,
the valves are placed by hand, or otherwise, in
the position represented in the plate ; h. filling the
opening in the partition, c. closing the main D.
The box slide also covers the hole on the side B.
of the partition, leaving the outer hole open as the
exhaustion proceeds ; A. and C. are in vacuum ;
B. and D. open to the air. There is then the
same pressure on each square inch of b. and c. ;
but h. being larger than c., both remain closed for
the total pressure on h. preponderating, will
33
keep c. against its seat. But the train on ap¬
proaching moves the slide box so as to cover both
holes, and a passage is formed through which the
air in the partition B. rushes into the main C.
so that A. and B. are both in vacuo, and the pressure
being removed from b. that on c. forces it back,
and allows the piston to pass. The valve, or rather
piston, b. is a cup leather, rivetted between iron
plates, and shuts into the opening in the partition ;
c. is a flat leather valve, and shuts against a facing
in the main.
The main pipe is put together with deep socket
joints, in each of which an annular space is left
about the middle of the packing, and filled with
a semi-fluid ; thus any possible leakage of air into
the pipe is prevented.
When it is necessary to stop, or retard a train,
in addition to the use of a common break, a valve
in the travelling piston is opened by the conductor,
by which means the external air is admitted into
the exhausted portion of the pipe, and the pro¬
pelling power destroyed.
In localities where a sufficient quantity and fall
of water can be obtained, the atmospheric system
34
can be worked without the assistance of " any
machinery whatever by constructing a tank or
tanks, (of a total capacity double that of the
section of pipe they have to exhaust,) filling them
with water, and allowing it to run out through a
descending perpendicular pipe, about 32 feet long,
(which it will do by its gravity alone,) the whole
of the air contained in the pipe will expand itself
into the tanks, and by the time they are half
emptied of water, half a vacuum will be formed in
the pipes, as the air will be expanded into twice
its bulk, and the other half will run out while the
travelhng piston and train are advancing ; thus
increasing the speed in the tanks, as that in the
pipes is diminishing by the approach of the piston,
and by this means maintaining the same degree of
vacuum, during the whole time the train is passing,
whatever be its speed."
Fig. 7 gives an idea of a station-house, one of
which, in Clegg and Samuda's plan, is located at
the distance of every three miles ; intended to
contain the stationary steam engine and exhausting
pump —d. e. represent two sections of the main
tube, communicating with the station by means of
35
Diagram No. 7.
the tubes b.c.—the curved lines f.f. show the
mode of erossing at the various stations, so as to
render one line of rail sufficient for the purpose of
traffic in both directions, the main tube e. being ex¬
hausted by the tube c. when the train is proceeding
in the direction from c. to d. and by a similar tube
to that of b, d. at its other extremity when the
train proceeds in the opposite direction.
Fig. 8 shows the mode of junction of other
lines, or branches of rail communicating with the
main line.
36
Dingram, No. 8.
From the preceding remarks, it will be evident
that in the patents of Vallance, Pinkus, and
Messrs. Clegg and Samuda, the inventors have
only proposed to avail themselves of the mechanical
properties of the atmosphere, resulting from its
mere weight, in the application of atmospheric
pressure on a piston against vacuum, regardless of
the power at disposal from its elasticity, compres¬
sibility, condensibility, and expansibility; the valves
of the two latter inventors being formed expressly
for the purpose of resisting pressure from without.
To effect this object they have had in common
a main pipe, a piston, or diaphragm, fitting this
pipe, an air pump to exhaust it, and a connecting
mateñal between the piston and carriage, through
37
a continuous slit, or valve, along the top of the
main pipe, which valve must be ripped up every
journey, by the passing of the carriage, and
cemented down again for the next exhaustion ;
and, says Mr. Pilbrow, in bis work, entitled,
" Atmospheric Railway and Canal Propulsion."*
The presence of this continuous valve seems ever
to have been considered a sine qua non, with all the
difficulties arising from it ; and to connect a car¬
riage outside the pipe, to a piston inside, so that
the one shall be acted upon by the other, without
this opening, seems never to have been dreamt
of in the philosophy of the several projectors of
atmospheric railways.
In this gentleman's patent, (Mr. Pilbrow's,)
the continuous opening or slit along the tube, to¬
gether with the valve, is entirely dispensed with, yet
the carriage and piston are so connected together,
that their motions become dependant one on the
other, and the travelling piston readily imparts its
• Atmospheric Railway and Canal Propulsion, by
James Pilbrow, 2nd edition, John Weale, High Hol-
born, 1844.
£
38
motion to the train of carriages. Many persons
would doubtless be inclined to believe that such
an arrangement is impossible, yet it is effected by
means so simple as at once to convince the most
sceptical of its perfect practicability, while a little
reflection will point out the immense advantages
to be obtained from its adoption. Thus the valve
being dispensed with, leakage will be prevented,
and the elasticity, compressibility and other
mechanical properties of the atmosphere may be
employed.
In the application of this principle, the con¬
tinuous valve being dispensed with, and a con¬
tinuous tube being employed, the tube,although eir-
cular, is somewhat modified in its form to admit of
the necessary arrangements for effecting the com¬
munication between the travelling piston and the
train of carriages, as seen in the subjoined
39
Diagram No. 9.
a
■which represents a vertical section of the tube,
in which it will be apparent that, though the
continuous valve is dispensed with, yet the longi¬
tudinal slit or aperture b. in the upper portion of
the tube is retained, the atmosphere being pre¬
vented from entering through it by means of a
solid square compartment, a. cast with the tube
itself, on the upper portion thereof, and extending
throughout its whole length. To fit this double
tube and render it air tight, it will be evident that
the piston also must undergo some modification,
and in reality it is two-fold, as seen in
41
consisting of, primarily, a cylindrical Lead, tra¬
velling in the lower portion of the tube c. and a
long square tail fitted to, and travelling in, the
square compartment d., the two being held toge¬
ther by a solid fastening passing through the lon¬
gitudinal aperture b. to communicate the motion.
The means of communicating the motion of
this double travelling piston outwards, is re¬
presented in the same diagram, where e. the
cylindrical piston head is represented in a section
of the lower compartment c. of the exhausted
tube, communicating by an armature g. through
the continuous slit 6., with the upper portion
or tail of the piston situate in the square com¬
partment d.
This upper portion or tail is grooved or cogged
on one or both sides, forming a rack, whose
grooves at various intervals receive the cogs of
pinions h. projecting into the square compartment
d, ; the axle of the pinion i. is prolonged upwards,
to receive a second set of cogs k. destined to work
in the grooves of a similar rack, attached under
the first carriage of the train.
E 3
42
representing a vertical section of the tube, where
a set of these pinions occur ; the lower cogs hh.
are seen projecting into the square compartment
d. communicating the motion resulting from the
passage of the piston-rack by them, through the
spindles i. i. to the upper cogs k. k.
In practice the piston-rack and carriage-rack
must be of equal lengths or thereabouts, and of
such extent that each will be in gear with two sets of
pinions at once, and thus in working never quit
the posterior pinion till the rack is in gear with
4-A
the pinion in advance. On the working scale
these vertical pinions are about 25 feet asunder.
The piston-rack and carriage-rack having each an
extent of about 30 feet in length.
Objections having been urged against the use of
cogs on the rails, as described above, on the ground
of their liability to fracture, and the noise which
would accompany their action; the patentee has
since substituted in their place spiral threads or
worms, on the pinions, and oblique channels on
the racks, by which means the racks enter between
the pinions without concussion, or fear of fouling,
and producing a screw motion of the pinnion, does
away with the noise that would attend the use of
cogs, and prevents the possibility of slipping,
which might occur in the use of plain surfaces, or
adhesion only.
In action a vacuum being formed in front of the
piston, theatmosphericpressureacting on its hinder
part with a greater or less force, according to the
degree of vacuum produced, propels it onward,
the motion of the piston-rack is conveyed to the
lower cogs of the pinion, and through the upper
cogs thereof to the carriage-rack, and consequently
to the whole train. The operation of this inven-
44
tion, or manner of its working, is thus described
by its inventor.
" A pipe or tube, of sufiScient diameter, being
laid along in a hollow between the rails of a rail¬
way, and being exhausted of air, and having the
spindles and pinions arranged as described at
intervals throughout its length ; the piston with
its " rack" attached is placed in this tube at the
farther end from where the air has been or is being
exhausted or withdrawn, the "piston-rack" being
in gear with the pinions inside the tube ; a railway
carriage, having a " carriage rack" attached to it,
being placed upon the rails, this " carriage rack "
being also in gear correspondingly with the pinion
on the upper part of the same spindles, outside
the tube, that is to say, the relative position of
each rack being the same, the " piston rack ''
being precisely under and matching end to end
with the " carriage rack," the one rack cannot
therefore move backwards or forwards without
turning the spindles and pinions, these being also
in gear with the other rack, that must move also,
and in the same direction ; if the vacuum, then,
has such an effect upon the piston, that it advances^
the "rack " upon the carriage will be affected, by
45
and through the medium of the spindles and
pinions, and will advance also, and keep its rela¬
tive situation exactly with the other, the racks
being long enough to reach as described, at least,
two pairs of pinions at one time, the next in ad¬
vance is acted upon before the one acting has
ceased, and therefore as long as the power applied
continues, and the piston advances, the carriage
will do the same to the end of the tube, neither
arriving before or after the other, but together,
as they cannot separate, nor can one move or stop
without the other ; thus would the carriage be
propelled, and others, if attached to it.
" As it is necessary and important that the atmo¬
sphere should be admitted as nearly behind the
piston as possible, the spindle and pinions maybe
lifted up by the advance of the " piston rack " or
by the "carriage rack," and the air will enter
through the space allowed by the lifting of the
conical or flat portion of the spindle or axis of
the pinions, thus would there always be, at least,
two or more such passages open, as the " rack "
may act upon any required number of pinions.
After the rack has passed by, the spindles by their
46
own weight fall into their original places, and thus
make an air-tight tube ready for the next ex¬
haustion ; when, if an air-pump be set to work at
the other end, and the direction of the piston and
rack changed, and placed again as before into
proper gear, the carriage would return in like
manner.
" As there will not be required by my plan, even
in a single line of rails, any discontinuance of the
main tube but at a place arranged for trains to
meet and cross, which will always be at a station,
(and for general purposes not less than twenty
miles apart,) it will be only at such places that
the main will require any kind of valve to close
its open end. The end of the main would simply
require a disc of iron or wood placed against it,
with a little composition, to make an air-tight
joint, when the vacuum is to be made by the air
pump, which disc or valve will fall or be pushed
aside when the piston arrives at the end, and will
require no more attention, excepting being replaced
or closed by the time this engine is again required
to work.
" The piston would, when it arrives here, either
47
partially or wholly leave the tube, after displaciug
the disc or door by its remaining momentum, and
the train with the "carriage rack"' will pass on, and
take one of the sidings, and be stopped by the
conductors by " brakes " as usual ; but the
operation of the stopping would have been begun
before arriving here, the train now only moving
slowly and with sufficient momentum to carry it
to the place required, or middle of the siding*
When the piston and rack reach the end of the
main, and are out or withdrawn, I propose
there shall be placed at each of the two ends of
the mains (and all similar ends), a receptacle or
trough mounted upon four wheels or rollers, so
that the piston coming on to it, could be immedi¬
ately removed for inspection, &c., and another
piston newly greased, &c. brought and placed (by
the same nuans) with its head in the tube ready
for the next returning train. The trains having
both arrived, each train would be (by any suitable
means) urged on to the commencement of the
opposite "main," where the fresh pistons having
been already inserted (and held by any convenient
contrivance) and the vacuum formed, the carriage
48
rack coming into gear with the first pair of pinions
and the piston released, the train would start on
its journey. Thus the pistons would never leave
the main, or enter another, but at a very slow
pace, and at a place for stopping ; and the same
piston would not be required to go on the whole
journey, but a fresh one might be applied every
twenty miles, leaving the other to be examined, &c.
"When this method of propulsion is used upon
COMMON ROADS, the tube will be sunk or buried
along the side or centre of the road, and its
operation would be as before described, there
merely being the absence of the rails."
On the relative advantage of this mode of
atmospheric travelling, as compared with that of
Samuda, we will subsequently dilate, in the mean¬
while sufficient has probably been said to explain
its simplicity, ingenuity, practiÄbility, and
efficiency.
It would probably be unjust to the inventors to
pass to the consideration of the advantages of
atmospheric railways generally, without arresting
our attention for a few moments on other modifica¬
tions of the valves in Clegg and Samuda's plan.
49
one suggestedby the ingenuity of Monsieur Hallette,
and another by Mr. Hay, of Portsmouth.
The former gentleman, Monsieur Hallette, having
remarked the facility with which a vacuum may
be formed in a tube, surrounded by the human
lips, has proposed to produce artificial lips, one on
each side the longitudinal aperture of the piston
tube, by means of semicircular tubes attached on
each side, to be filled with elastic circular bags,
containing water under pressure, as in the follow¬
ing diagram. No. 12.
F
50
where a. represents the travelling piston ; h.
its armature ; c. c. the semicircular tubes,
containing the elastic bags d. d. ; compres¬
sing the armature of the piston in its passage to
the train, yielding to the pressure of its onward
motion, and closing after it has passed.
The latter gentleman, Mr. Hay, reflecting on
the time necessary to effect the removal of any
portion of injured valve on Samuda's plan, owing
to the necessity of taking off the horizontal plates
of iron which hold it down on one side, suggests
that it should be free on both sides, and made to
travel through a forked armature, being only
held at its two extremities. Probably in practice
neither of these valves will be found, although
ingenious, (especially the former,) equal to that
of Samuda.
The principle of the application of the mecha¬
nical properties of the atmosphere, as a locomotive
power, being fully established by the repeated ex¬
hibition of models in London, at Wormhalt
Scrubs, and on a working scale on the Dalkey
extension of the Dublin and Kingstown railway, we
have now to consider the advantages resulting
51
from this mode of locomotion over the present
system of steam conveyance, together with the
objections that have been urged against its use.
To this end we wül first inquire what are the ad¬
vantages proposed to be gained by any line of
railway ? These are as follows, viz.—rapid com¬
munication between distant places, combined with
safety to passengers, and although last, not least,
a fair return for capital employed ; and on each
of these respective grounds it will, I think, be
fully shewn that the atmospheric system has pecu¬
liar claims for public patronage. First, as to
original formation—To form a railroad on the
locomotive system, whatever may be the line of
country proposed to be traversed, it is necessary
to produce almost a level line of road, for which
purpose a vast outlay must be incurred in
cuttings, embankments, and tunnelling ; not only
a level line, but almost a straight line, not having
a curve greater than 800 yards radius, must also
be obtained, rendering it imperative in many in¬
stances, to purchase at an enormous expense the
privilege of passing through certain properties in
a projected line of rail, and also to purchase more
52
than' quadruple the width of road necessary for
the mere passage of the train, for the foundations
of the slopes required, the cuttings and embank¬
ments, for the spoil banks, the side roads, the
drains and ditches, and sidings for stations on
the line, which have not only to be made in the
first instance, but to be maintained and repaired :
no such expenses are necessary on the atmospheric
principle and in addition the weight of the rail may
be materially diminished, in consequence of fifteen
to twenty tons, the weight of the locomotive
engine, being dispensed with.
On the atmospheric system, the power employed
being a perpendicular power, any incline may be
travelled with facility, and the highest mountains
traversed with ease, consequently the level line
with its cuttings, embankments, and other ex¬
penses, are not needed ; thus, on the Dalkey ex¬
tension of the Dublin and Kingstown line, where
the power employed is merely atmospheric pres¬
sure acting against vacuum with a force equal
to 81hs on the inch only; an incline of 1 in 100
(as represented in diagram No. 13.)
is traversed by a train of 72 tons weight, at 20
53
miles an hour round curves similar to those repre¬
sented in diagram No. 14,
No. 13. No. 14.
54
of something less than 300 yards radius.
It is therefore applicable to the common turnpike
road, and all expenses dependant on the forma¬
tion of an appropriate line of road may be avoided.
One single line of rail also being all that is neces¬
sary on this system, it may even be adjusted to
the side of a turnpike road leaving suificient way
for the ordinary traffic.
Next as to first cost in the power to be employed,
this will of course be dependant on the presumed
traffic to be accomplished. On the locomotive
systern, with a traffic of 1700 tons per day, one
engine will be necessary for every mile of road ;
making the calculation, therefore, for a line of
30 miles in length 30 locomotive engines must be
purchased, and, as each engine costs about 361500,
and as ¿£1500x30=3645,000, that sum will be
sunk in the first cost of motive power.
On the atmospheric principle, according to the
plan of Clegg and Samuda, a hne of thirty miles
in length would require ten stationary engines,
air-pumps and engine-houses ; supposing three
miles to be the distance between each, and
if it were calculated to transport 5000 tons
55
per day over the whole distance, the expense of
each establishment complete would be ¿64200,
which multiplied by ten=¿642000; or ¿63000 less
in the first cost of power to accomplish a traffic
three times as great as that proposed by the loco¬
motive system, viz. 1700 tons.
The comparative first costs of the locomotive
and atmospheric systems are summed up as follows
by Samuda, in his work :—page 28.
LOCOMOTIVE SYSTEM.
Per mile.
Taking five of the principal Kailroads
as the hasis of our calculation, their
average expense of formation has
exceeded ..... ¿636,000
And the original stock of Locomotives 1,600
¿637,600
56
ATMOSPHERIC SYSTEM.
Per mile*
The average expense of forming a turn¬
pike road throughout England has
been ¿63000 per mile, but for our
road say ..... ¿64,000
Allow extra for road-bridges . . 2,000
Rails, chairs, sleepers, and laying down 2,500
Main pipe and apparatus complete (on a
scale for transporting 360 tons per
hour, or 5000 tons per day of four¬
teen hours, on a road with gradients
of 1 in 100) 5,200
Fixed engines, air-pumps and engine-
houses ...... 1,400
Travelling pistons .... 20
Saving per mile in forming and furnish¬
ing on the Atmospheric system . . 22,480
¿637,600
From this table it appears that the saving per
mile, in forming and furnishing on the Atmo-
57
spheric system, is no less than ^622,480 per mile,
or nearly two-thirds of the whole sum expended on
the Locomotive system.
This, however, is not the most important
economy capable of being effected, much greater
saving resulting from the employment of stationary
power in lieu of locomotive.
It is universally admitted that when once a
stationary engine is established, for whatever
purpose it may he employed, the cost for repairs^
and wear and tear, rarely exceeds more than five
per cent, per annum on the first cost, and many
stationary engines have been known to work for
years together with scarcely a single hour's inter¬
mission as in many of the mines.
By reference to the half-yearly accounts of the
Liverpool and Manchester Railway, the annual
expense for locomotive power and coke, is found
to be from ¿657,000 to ¿660,000 a year, nearly
¿62,000 a mile per annum, on a traffic of 1,700
tons a day, which sum is exclusive of first stock
and interest on the original stock.
The comparative expenses of working are thus
stated by Sarauda. (Page 29.)
58
LOCOMOTIVE SYSTEM.
Per mile.
5 per. cent interest on capital sunk,
^637,600 £1,880
Maintenance of way .... 450
Locomotive department, including coke 1,800
¿64,130
ATMOSPHERIC SYSTEM.
Per mile.
5 per cent, interest on capital sunk, viz.
¿615,120 ¿6756
Maintenance of way, and attendance on
mains ...... 300
Wear and tear of fixed engines, 5 per •
cent, of cost .... 70
Coal 0.751b. per ton per mile, 214 tons,
at 20s ...... 214
Wages to engine-men and stokers. . 60
Wages to train conductors ... 26
Renewal of travelling apparatus and
composition ..... 50
Sundries . . . . . . 150
¿61,626
59
Annual saving per mile on the Atmo¬
spheric system .... 2,504
^£4,130
Total expenses per ton per mile on the Locomotive
system ...... l"54rf.
Ditto ditto ditto on the Atmo¬
spheric system . . . .0 6d.
This assertion relative to the comparative ex¬
penses of the two systems, is corroborated by the
the Parliamentary reporters, as follows :*—
"We have no doubt that a stationary engine pro¬
perly proportioned, according to the rules we have
indicated, for a pipe three miles long, would be
able to work trains on a line every quarter of an
hour, or every half hour, each way, during the
day, (say of 12 hours,) amounting to 144 miles.
Now to work this distance by a locomotive engine,
at the moderate estimate of Is. 4d. per mile,
would amount to £9 18s., say £10. per day;
whereas the stationary engine power would not
British and Foifimi Review. April, 1841. •. I'age Ï19
60
cost half that sura, and consequently a saving in
working expenses would arise of ^1800 or ¿62000
per annum. But if only half this duty were re¬
quired, the expenses of the two ways of working
would be much nearer equal : and again, if only
half the latter duty were to be performed, that is
of trains starting only every two hours each way,
the advantages would be on the side of the loco¬
motive engine. The fact is, that in one case the
expenses per diem will be nearly the same, whether
working at intervals of an hour or at every quarter
hour ; whereas, in the other, the charge is nearly
proportional to the work actually performed.?#*
Great economy in the working on the atmo¬
spheric principle also results from the fact of its
admitting of the employment of much steeper
gradients than the locomotive system, and from
the whole force employed to surmount them being
exerted on the load itself by the atmospheric prin¬
ciple ; instead of being in great part absorbed by the
motive power, viz. the engine andits tender, as in the
present system of railways.—The extent of this
defect will be more clearly apparent by an example,
says Samuda. (Page 21.)
61
" Supposing a locomotive engine to possess a gross
tractive force of 17001bs., and its weight, including
tender, to be 20 tons, (this is the actual weight
and tractive force of the best locomotive engines
in general use when travelling at a mean rate of
20 miles per hour,) and as 141hs. per ton is
required to attain this velocity on a level road,
2801hs. will he consumed to impel the engine and
tender, leaving 14201h8. available for the train.
This, ^t 141hs. per ton, will draw 101 tons on a
level road. We will now place the same train on
an inclined plane rising 1 in 50. The power
required to draw a ton at the same speed is then
increased from 141hs. to 59lhs., or nearly 4^ times
as much as on a level : therefore the engine and
tender weighing 20 tons will consume llSOlhs.
instead of 2801hs., and will leave hut 5201hs.
available for the train, instead of 14201hs. ; hut
as the train now needs 59591hs. to enable it to
ascend, 11|^ locomotives, each possessing a tractive
force of 17001hs., together 19,5501hs., will he
required to produce that available force : we thus
have an absolute waste of more than two-thirds of
the power employed on an ascent of 1 in 50, while
G
G2
on a level it is less than one-sixth. By (he same
calculation it will be seen, that if the acclivity be
slightly increased, the locomotive engine will not
have sufficient power to draw itself and tender,
even without the train."
This considerable inconvenience of the employ¬
ment of gradients in the locomotive system is more
fully demonstrated in the following table, taken
from "Wood's Practical Treatise on Railways," show¬
ing the gross load, in tons, which a locomotive
engine capable of evaporating sixty cubic feet of
water per hour, will drag, exclusive of the tender,
at the undermentioned rates of speed, on different
inclinations of planes.
Note.—Gross load in tons wliicli a locomotive engine, capable of evaporating sixty
cubic feet of water per hour, vill drag, exclusive of the tender, at the under¬
mentioned i ates ofspeed, on different inclinations of planes.
10
124
15
174
20
224
25
274
30
Inclination
miles an
miles an
miles an
miles an
miles an
miles an
miles an
miles an
miles an
of plane.
hour.
hour.
hour.
hour.
hour.
hour.
hour.
hour.
hour.
tuns.
tons.
tons.
tons.
tons.
tons.
tons.
tons
tons.
level.
346.
251-10
187-84
142-64
08 75
82-38
61.29
44 04
29-66
1
n 4480
325-72
236 09
176'35
133-66
01-65
76-76
56-83
40 54
26 95
1
n 2240
307-58
222-67
166-06
125-62
95-30
71 71
52-84
37-40
24-54
1
n 1120
276 47
199-65
118-44
111-85
84-41
63-07
45.99
32-03
20-39
1
n 1000
269-87
199-76
144-70
108-93
82-11
61 24
44-54
30-89
19-51
1
n 900.
264 59
190-85
141-70
106-58
80 25
59 77
43-38
29.98
18-80
1
u 800.
255-56
184.17
136-59
102-5
77-09
67-25
41-40
28-42
17-60
I
n 700.
246-17
177-22
131 27
98 43
73-81
54-65
39-33
26-79
16-35
1
n 600.
234-68
168 72
124-75
93-34
69 78
51-46
36 80
24-81
14-82
1
n 500.
220-02
157-87
116-45
86-85
64-65
47-38
33-58
22 28
12-86
I
n 400.
201-04
143 82
105-69
78-44'
58-01
42-11
29-40
19-
13-33
1
n 300.
175-39
124-85
91-16
67 09
49-03
34-99
23-70
14 57
6-91
1
n 200.
138-48
97-54
70-24
60-74
36 12
24 74
16-64
8-20
1-99
1
n 100.
84-07
55-30
37-89
25 46
16-14
8-88
3-09
—
—
See Wood on Railroads, 2nd edition.
64
By reference to the same table, it will also be
seen that the power of the engine is constantly
diminished as the velocity of the train is increased ;
thus, an engine drawing 346 tons on a level, will
only draw 108 at the rate of 20 miles per hour,
and to obtain that speed for the whole 346 tons,
more than two other engines must be added, and
the cost of working at this increased speed will,
in consequence be more than trebled.
This loss of power from increased velocities,
principally arises from the great velocity in the
movement of the pistons, preventing the steam
from acting on them with full force, causing a
back pressure thereon, and reducing their force in
proportion to the velocity at which they move.
In the atmospheric system of Clegg and Samuda,
the power and velocity depends entirely on the
rapidity with which the air is withdrawn from the
tube, and a vacuum established in front of the
piston ; and, therefore, by simply enlarging the
air-pump, increased speed and power may be
obtained ; and, in that of Pilbrow, the velocity
and power may be still farther increased by the
introduction of compressed air immediately behind
the piston.
On an atmospheric line, increase of speed does
not increase the cost of transit ; and the power
expended may he exactly regulated to the power
required, by diminishing or increasing the action
of the exhausting engines proportionately to the
resistance, and making more or less rarefaction as
may be necessary.
It would be possible, for example, to use. on
ordinary occasions an exhaustion of twelve or
thirteen inches column of mercury, orabout (ilbs.
to the inch of atmospheric pressure, and to increase
it to 10 or 121bs. on the inch when required, either
for increased speed or ascending inchnes.
In all atmospheric systems the loss of power
occasioned by the locomotive engines having to
draw their own weight is entirely avoided, and
steep hills may be ascended with no more additional
power than that actually due to the acclivity, as
there is no weight except the train, and, conse¬
quently, the whole force employed will be
exerted thereon.
Monsieur Tisserenc, in his report to the French
government, remarks (p. 107) " That the eost of
a locomotive engine in action is nearly the same
66
whatever load it carries, and the cost of repairs is
proportionably smaller upon an engine of large
size and power ; such a motive power can, therforc
be only profitably worked with large trains, and
this very fact tends to limit considerably the
number of daily trains, and consequently the
advantages of railway travelling.
On the atmospheric principle, on the contrary«
a saving in the' cost of working is effected by the
very means which the public advantage requires ;
namely, by despatching trains as speedily as pos¬
sible. Their weight is consequently diminished,
and the piston having less to draw, may be pro¬
portionably smaller in diameter. This reduces the
tube (which is the principle item in the first ex¬
penditure) in nearly the same proportion as the
speed is increased, and as the rapid succession of
trains is effected ; so that the economy of working
and the advantage to the public are here identical.
By the registered experiments on the Dalkey rail¬
way, a train with a load of 72 tons, takes 5 minutes
and 33 seconds to perform the journey of one mile
and three quarters. Now, as upon this system no
two trains can possibly move at once on the same
67
section of pipe, no delay is required in starting
the trains to avoid danger from their overtaking
one another. As soon, therefore, as one train
has passed off a section, the tube is ready to be
exhausted again, and to receive the next train imme¬
diately and, therefore, according to the length of the
tube and the relative diameter of it to that of the
piston of the air-pump, trains may be started
every 15 or 30 minutes during the day, and even
more frequently if desired.
The correctness of the foregoing premises being
admitted, it will be evident that both in its first
formation, and in the expense of working ; the
atmospheric principle offers much greater security
for accomplishing the grand desideratum of railway
speculation (viz. a fair return for capital employed)
than can ever be even hopied for by any other prin¬
ciple of locomotive railway.
We have now to consider the other proposed
advantages of railway travelling, viz.—rapid com¬
munication between distant places combined with
safety to the traveller. First, as to velocity :—
on this head it will be apparent that the only limit
to velocity on the Dalkey line is the relative size
f)S
of the exhausting pump, as compared with the
tube to be exhausted, and no one will attempt
to deny that the tube may be exhausted more
rapidly, and a consequent greater rapidity given
to the train in motion by increasing the size of
the air pump, and more rapidly effecting the ex¬
haustion of the tube in front of the travelling
piston ; yet even on this line a velocity of 50 or
60 miles per hour is readily obtained. It will be
borne in mind that in this application the only
principle employed is merely the mechanical
pressure of the atmosphere acting on a piston
against a vacuum, which when fully employed is
only equal to 141bs. on the inch; while the
employment of the other properties of the atmo¬
sphere puts at disposal the means of increasing
that power at least one hundred fold, and conse¬
quently of commanding any velocity that may be
desired, consistent with prudence and safety ;
and there is little doubt in my mind that a velocity
of one thousand miles per hour, or even more,
might be as easily effected as that of 50 miles
per hour only, if it were considered prudent to
employ it ; and that letters, merchandise, and
69
luggage might be as safely and surely transmitted
from John O'Groat's to Land's End, in the same
time as they are now conveyed from London to
Oxford.
The Atmojpheric principle then, admitting of
the highest velocities, the question of the velocity
to be adopted resolves itself into the question of
" What velocity is consistent with the safety of
the traveller ?" Even to this inquiry we can give
no definite answer, as we possess no data on
which to base our calculations, so as to fix a
limit. Thirty years ago it was deemed prepos¬
terous to advocate the possibility of travelling at
the rate of thirty miles per hour, and a variety of
plausible arguments were put forth to show the
dangers to be apprehended primarily to the respi¬
ratory organs in the animal economy, and through
them to the brain, in the production of conges¬
tion, apoplexy, &c. should such velocities be
attempted. But we now see the Exeter fast
trains travelling at the rate of fifty miles per
hour, with perfect safety to the health of passen¬
gers ; and I can conceive no difficulty in adopting
such means in the formation of railway carriages
70
as to secure perfect immunity from danger to the
animal economy, even though they travelled at
the rate of a thousand miles per hour. For myself
I am inclined to believe that even the present
generation will not be content till the ordinary
velocity of travelling equals, if it do not exceed,
one hundred miles per hour; and which will even
be effected with much greater security to the public
safety than exists in the present locomotive system.
It has been very justly observed by Mr.
Samuda, in his pamphlet, (page 39.j " The
first grand object in railway undertakings
is to render them a perfectly secure mode of transit
—a conveyance by which the most timid may
travel without hesitation, without a thought of
fear, and of course without an example of ill,
arising from the badness of their workings, to
refer to : these great works, destined as they are
to effect much good to all classes of society, will
never be, nor indeed deserve to be, looked upon
as a permanent benefit until they have arrived at
this point. Precisely as a country flourishes under
a well regulated system of police and justice,
where the liberty and right of the subject are
71
respected, so will railways flourieli as human life
in their keeping becomes secure. The high roads
of England became more travelled over as the
robbers that infested them fell into the hands of
justice ; and it is a matter of small importance to
a person contemplating a journey whether he have
to fear falling a prey to the assassin's knife, or
losing his life from the collision of two railway
trains. The possibility of either would equally
prevent the timid from travelling, and the cou¬
rageous from travelling more than necessity
required.
To render the railway system perfectly secure
is, then, the first object, and to this end should
those who have its prosperity at heart look well.
Humanity dictates it, and interest prompts it ;
and what greater inducements, we would ask,
need be urged ?"
The learned Editor of the British and Foreign
Quarterly Review, remarks (page 325.) " If any
one feature characterizes the principle of the
Atmospheric Railway, it is the very element of
safety which lies in its construction, and in the
mode of its working." And in support of this
TI
opinion he quotes the authority of Messrs.
Teisserenc, Samuda, and Mallet.
The first of these gentlemen, Monsieur Teisse¬
renc, states " In reference to security, it is easy
to show that the Atmospheric system remedies
all the principle causes of accident on the ordinary
railroads," and he asks in fact, what are those
causes ? " They are principally collisions between
trains, running off the roads, breaking of the
axle trees of the locomotives, the falling down
into deep cuttings, and taking fire. With the
Atmospheric apparatus," he says "there are no
collisions, no taking fire, no rupture of axle
trees, the road being adapted to the ordinary
incline of the soil, renders embankments, unne¬
cessary, and there can consequently be no falling
down the-sides, and the train being held by a
fixed point, can scarcely ever get off the rails."
Mr. Samuda remarks.—" This system possesses
advantages of great importance to the public.
iVb collision between trains can take place ; for
as the power cannot be applied to more than one
piston at a time in the same section of pipe, the
trains must ever be the length of a section apart
73
from each other ; and if from any cause a train
should be stopped in the middle of a section, the
train which follows it will be obliged to stop also,
at the entrance of the pipe, ,as there will be no
power to propel it until the first train is out. It
is also impossible for two trains to run in opposite
directions on the same line, as the power is only
applied at one end of each section. A train
cannot get off the raU, as the leading carriage is
firmly attached to the piston, which travels in the
pipe between the rails ; and the luggage and car¬
riages cannot be burnt, as no engines travel with
the trains."
The opinion given by M. Mallet fully confirms
this statement. " Firstly," he says, " this sys¬
tem, from not employing locomotives, is exempt
from all the dangers to which accidents to them
expose us. In the second place, the risk of
collision entirely vanishes, and perfect security
may be enjoyed on that head, two trains never
being able to run in the same pipe at once."
Again he says :—
" Upon an atmospheric railroad there is no
possibihty of running off the rails ; or at least,
H
74
if one carriage gets off the rails no accident can
result from it. First, the leading carriage, firmly
and closely attached to a pipe, which may well
be regarded as immovable, from its own weight
and the strength with which it is fastened down,
cannot run off the rail. Those which follow it,
and are linked to each other, would have even
more difficulty in getting off the rails. But on a
railroad, whilst the guiding carriage maintains its
way, it is of litfle consequence if one of those
behind misses the rail ; its wheels may plough up
the soil beside the track, but as it cannot get
away, no danger is to be apprehended, and the
worst that can happen will be a check in the
speed. This is an important result for the con¬
struction of roads upon the atmospheric system."
The opinions here quoted in favour of the su¬
periority of the atmospherie principle are still
further corroborated by a preponderating ma¬
jority of those who have examined into its merits ;
amongst whom may be particularized a gentleman
of no mean authority, who, when he has com¬
pleted his present undertakings, (should he live to
accomplish them,) will leave a lasting monument
75
of his fame, greater probably than any man now
living, in railroad affairs ; viz.—Mr. Brunei, the
engineer of the Great Western Railroad, and sou
of Sir. I. M. Brunei, of Thames Tunnel and
Portsmouth Block-Machine notoriety. In the
prospectus of the Gravesend and Chathafti Com¬
pany, published in 1844, was found a »recom¬
mendation of the committee, founded upon the
opinion of their engineer, I. K. Brunei, Esq. to
adopt the atmospheric system. The prospectus
stated " The committee having made a satisfactory
inquiry as to the decided economy with which the
Dublin and Kingstown Extension Railway, is now
being worked as an atmospheric line, and their
engineer having satisfied himself as to the ad¬
vantages this plan of motive power affords, re¬
commend its adoption on the proposed line of
communication, 6otA as a mums of keepiny the
capital within avery moderate compass, and of in¬
creasing the profits by a reduced charge of work¬
ing." In accordance with this recommendation,
we find that he has recommended its adoption also
to the Directors of the Great Western Railroad,
and at the present moment is engaged in bringing
70
it into action on the Falmouth extension of that
line of rail.
Great as are the advantages of the atmospheric
principle of Clegg and Samuda over the present
system of locomotive railroads, they form but one
step in the progress to perfection, and, if brought
into operation, will in all probability be soon
superseded by other more important and more
economical inventions ; already the patent of Pü-
brow, to which we have alluded, bids fair to put
if completely " hors de combat." The compara¬
tive advantages of this invention over that of
Clegg and Samuda, are described by its inventoras
follows :—First,
IN CONSTRUCTION.
I. In having no discontinuance of the "main,"
and therefore no "'section valves," &c. at crossings
of roads, lanes, &e.
II. In having no necessity for bridges for cross
lines, roads, lanes, &c.
III. In having no continuous valve with all its
complication, and necessary care in fitting, com¬
position, &c.
77
IV. In having fewer engine establishments, one
to every ten miles being sufficient, instead of one
to every three miles—thus saving twenty-three
engines, Sfc. out of thirty-four in 100 miles.
The reason why a less number will be required on
this plan than the other, is, that there being no long
valve here, the leakage wUl be so diminished that
it will amount to less in ten miles than now in
one ; it is estimated that now the leakage equals
5-horse power per mile, * and therefore should there
be but one engine to ten miles of main, .iO-horse
power out of the 100 would be lost for leakage
alone, so it is found absolutely necessary to have
one engine every three miles, thus reducing the
loss to 15-horse power out of the 100. Why the
pinion-valves as proposed will not leak so much
as the long valve is, first, because the surfaces are
ground truly, and are pressed together by the
weight and fall of the pinion, (and the more used
• See Mr. Samuda's evidence'before the Committee
of the House of Commons. Mr. Bergin, in his evidence,
said 5 or 6-horse power per mile, &c., but doubtless tbis
will be found under-rated for extensive practice.
II d
78
the better they -will stop) ; and secondly, on
account of the small quantity of surface or space
that can leak, the proportion being as 1 to 20
between the two systems, for the pinion-valve or
seat being but about 9 itïches in circumference at
the aperture where the air is admitted, and being
only two of them to every 30 feet of main = 1 -5
feet, whereas, the present long valve would be
the whole thirty feet exposed and liable to leakage ;
hence, even were the pinion-valves to leak as
much as the long valve, surface for surface, this
plan would only leak 2J-horse power instead of
50-horse power, in ten miles !
V. In there being no necessity for the main to
be cast thicker at the lower part than at the top,
for strength, as now the tube being with an open
groove along its top, when therefore a vacuum is
made within, the superincumbent atmosphere
pressing all round the tube, has so large a surface
to act upon and so strong a tendency to press these
edges together, that it is found necessary to cast
the " main " much thicker and heavier at the
lower part and altogether than otherwise would be
requisite, if it were without any cut or open groove.
79
VI. In having no necessity for the " heating
apparatus."
VII. In having no necessity for 'cranes,' or
elevated rails, for the taking on and oif carriages,
as that would he done in the usual manner, &c.—
Secondly,
IN SAFETY,
AND THEREFORE GREATER POPULARITY.
I. In there being no necessity for a discontinu¬
ance of " main " between the stations, therefore—
II. In the fact that the piston will never leave one
part of the main and enter another at full speed.
III. In there being no section valves under the
doubtful control of an attendant, or the liabilities
of machinery to get out of order (and so not act
at the instant reqnired), which neglect or accident
would be attended with the most fearfnl concussion
and consequences.
IV. In the piston never leaving or entering a
" main " but at a station where it is required to
stop.
V. In no liability of obstruction or destruction,
by snow, frost, and bad weather.
80
VI. In being able to retard trains in descending
inclines, by not lifting the valves, and thus rarify-
ing the air behind the piston.
VII. In the ability, in case of stoppage or
accident between stations, to disengage the piston,
and thus send that information to the next station,
and then the facility by which a carriage, contain¬
ing men and tools, &c. can be dispatched to their
assistance :—Thirdly,
.. IN SIMPLICITY.
I. In having no heating apparatus and com¬
position.
II. In havihg no long valve, or section valves,
between stations, bridges, &c.
III. In having so few engine establishments,
&c. &c.
IV. In being able, without any alteration from
the present mode, and without cranes, or elevated
rails, to remove or place carriages upon the line :
—Fourthly,
IN CHEAPNESS OF FIRST OUTLAY.
I. In requiring fewer engine establishments.
81
II. In requiring no bridges, &c. for crossing
of roads, &c.
III. In greater simplicity and lightness of
" main."
In the above three items and founded upon
Messrs. Clegg and Co.'s own calculations, and
evidence before the House of Commons, the saving
in 100 miles would stand thus:—
By the present system, there would be
34 engines and establishments re-
required, at ^65000 .... 170,000
By the proposed system, at
ten miles apart, 11 at
^65000 55,000
36115,000
By saving in bridges, &c. for roads and
cross lines : Messrs. C. & S. in their
pamphlet, p. 20,haveallowed 362000
per mile extra for bridges, but allow¬
ing that half the quantity would be
required upon the common locomo¬
tive railway, I consider ¿61000 per
mile on the average of lines a very
moderate calculation, 1000 x 100 100,000
By simplicity and lightness of "main,"
the estimate given of the present
plans, by Messrs. C. & S., stand
thus, per mile :
¿6215,000
82
Brought over 56215,000
Main, (15 inches diameter). . . . 1632
Long valve, &c 770
Composition for lining and valve 250
Planing, drilling, &c. . 295
Laying, jointing, &c 295
Station valves and piston appa¬
ratus 100
3342*
The saving in the above may be safely
taken thus : —
In main, (less weight, &c.). . . 200
In difference of cost of long
valve and pinions 375
Difference in composition (being
none required for the long
valve 125
In planing, drilling, &c. (which
must be wholly connected with
the long valve) 150
850
850x 100 miles 85,000
56300,000
• See Mr. Samuda's ICvideiicc l)ctoie the (ioinmittee
of the House of Commons.
83
Thus showing a difference, in first outlay, in
favour of Pilbrow's patent over the present
"atmospheric railway" apparatus, in 100"miles,
no less a sum than «6300,000 ; and in which it
is presumed there can be no difference of opinion,
when the two plans are examined and compared,
even by the most partial or sceptical :—Fifthly,
CHEAPNESS IN WORKING.
Interest upon capital saved in first
outlay (300,000 per annum) 15,000
Wages to engine men and stokers (as
34 is to 11)* 4,058
In composition (being no long valve,
and therefore none required for that
purpose, «6200 being allowed by C.
& S. per mile for composition and
renewal of travelling apparatus, &c.;
one-fourth only is here supposed to
be saved )t 5,000
Saving in fuel,—there being only in
this case, 11 furnaces to light and
keep going between trains, instead
«624,053
• See pamphlet by Messrs Clegg and Co, p. 21, upon
which the above is founded. John Weale, London,
t See Mr. Samuda's Evidence.
84
Brought over j624,()58
of 34, and the fuel at present
WASTED by such means being two-
thirds of the whole quantity used,
where the trains are not very fre¬
quent indeed. When we consider
that the engine will only work 5
minutes to standing still 25 minutes
the fire must be kept up during this
time, and the waste in getting steam
up every day,* we shall be under¬
rating, if any thing, by taking only
the saving of the two-thirds for 23
engines out of 34, and a propor¬
tionate saving in the 11 used ; it
will stand thus:—As 154 tons of
coals are consumed in 80 daysf by
If miles of road, (and that working
but one way) the saving for 100
miles per annum, at 20s. per ton,
would be for the two-thirds waste of
23 engines, ¿618,038 and one-third
waste upon the 11 engines used,
¿63,009, together 21,047
¿645,105
• See Mr. Bergin's Evidence : he states that 42 tons
and a half of coals were used to get the steam up alone,
to 111 tons and a half used while the trains were at work,
t See Mr. Bergin's Evidence.
85
Brought over £45,105
Mr. Samuda, in his examination, (by
Mr. Mereweather,) before the House
of Commons, stated that " there
would be a man per mile extra for
attending to the valves : " such not
being required where there is no
long valve or composition to attend
to, the expence would be saved,
amounting to, per annum, for 100
men at 12s. per week 3,120
In saving of wear, and renewal of 23
boilers, &c 2,300
In saving of fuel expended on extra
leakage, the difference of leakage
in the two systems being equal to
one-seventh of the power employed ;
therefore, if we suppose here half
the gross fuel used to be usefully
expended 1,528
Total saving for 100 miles per annum
in working, as compared with the
estimated cost by the present " at¬
mospheric" system £52,053
Without absolutely pinning our faith to the
accuracy of these calculations, the most candid
inquiry and the most careful observation fully
86
justifies the assertion, that the patent of Pilbrow
offers very important advantages over that of
Samuda, alike in the first outlay, in the expense
of working, in the absence of the long valve, and
in the facilities for crossings without the interven¬
tion of bridges ; and that, although, it is as yet
untried on the working scale, there are no diffi¬
culties connected with its application that inge¬
nuity and perseverance wiU not overcome. That
as the ordinary roads have to a great extent been
superseded by railroads and locomotive power,
these will be dispensed with, by the employment
of the atmospheric principle and stationary power,
and the first application of this principle will be
set aside by the later invention, which in turn
will be shelved by some other application of the
same principle, combining the advantage of
vacuum before the piston with compressed air
acting as propulsive power behind it ; unless the
inventor, Mr. Pilbrow, immediately secures to
himself the right of employing such combination,
for which his invention is peculiarly adapted.*
* Since Uie above was written, 1 lind that Mr. Pilbrow
87
I do not mean to contend that the combination
of these two sources of power :—viz. exhaustion
before the piston, and compression behind it, are
impossible in the patent of Clegg and Samuda; on
the contrary, I beheve it to be perfectly practi¬
cable, but that its application would be much less
easily eifected than in that of Pilbrow.
It may be asked " What are to become then of
the present railroads, are they to be abandoned?"
The answer is " No, but the locomotive power
employed must be set aside, and stationary power
and the atmospheric principle be substituted, if
l^iey wish successfully to compete with other hnes
of rail, already projected, or in progress of comple¬
tion. By this means alone can they defy competition.
On this point Mr. Samuda justly remarks, p. 40,
has become aware of the important advantages derivable
from^the combination]of vacuum before the piston, and
compression after it ; and that he, moreover, proposes
tlie employment of back vacuum ; that is, a certain
degree of exiiaustion bebind the piston, as a means of
arresting the too rapid progress of trains down steep
gradients,—a principle which cannot be applied to the
long valve system of Clegg and Samuda.
88
" Perhaps the next point, after having arrived at
that degree of security required to satisfy the
public, is to obtain that system of working which
is the most economical. A large portion of the
British commercial public have, with that enter¬
prise which characterizes all their actions, em¬
barked large sums of money in establishing railway
communications between most of the principal
towns in the kingdom. They saw the advantages
that were certain to result from such an improved
communication, but they did not know, indeed it
would have been too much to have expected from
them, the expense of making and maintaining,
this communication. They only knew what their
engineers told them. Their engineers' estimates
in most cases were considerably less than was
found necessary for the work, and this, added to
the increased annual expense of working (above
that originally contemplated when most of the
present lines were projected), has placed these
undertakings in a very questionable light as com¬
mercial speculations and permanent investments.
If we show this to be the present position of most
railways, which we intend doing by reference to
89
their own accounts, we wish it to be understood
that we do not from this circumstance draw a
conclusion that they cannot be made a lucrative
investment. On the contrary, we are of opinion
that they can : we think it has been clearly shown
that all their difficulties have arisen and are per¬
petuated by the use of an improper system of
working. So long as the locomotive system is
adhered to, a strict economy may in a small degree
lessen the expenses, but no material improvement
can be hoped or obtained. To strike at the root
of the evil, the system must be abohshed; any
thing short of this will not be productive of
benefits on a sufficiently extensive scale to enable
railways to maintain their present position, and
yield a return for the millions they have cost. A
better instance of this fact can scarcely be needed
than an inspection of the receipts and expenditure
of those railways already in operation. From the
official weekly returns in the " Railway Times,"
we perceive seventeen railways are in operation
the whole of their length, and out of the whole
number only three are earning sufficient to pay
their subscribers more than common interest for
I 3
90
their money. Of the remaining fourteen, six are
not taking as much for their gross receipts as the
interest of their capital embarked, independent of
working expenses ; and the receipts on the remain¬
ing eight, after deducting the working expenses,
do not leaye £b per cent, dividend for their sub¬
scribers.
" Fifty millions sterling have been embarked
in railway speculations, and seventeen lines have
come into full working activity, of which number
only three can show a return beyond common in¬
terest to the subscribers : it well behoves capitalists
to ascertain the cause of their disappointments,
and to seek to recover some of the golden harvests
they were led to expect, and which have melted
away before their eyes, like ice in the rays of the
sun. Any thing short of perfect indifference to
their own interest will force on them the conclusion
that they must investigate and judge for them¬
selves ; that they must no longer shut out the idea
of improving, and listen only to the counsel and
advice of those at present in their confidence,
whose interests are served by maintaining things
as they now are, and by clinging to preconceptions
91
and prejudices as part and parcel of their exiat-
ence. When looking oyer the half-yearly accounts
of a railway worked by locomotive power, common
sense and observation cannot fail to lead to the
conclusion, that a very large portion of what
would be profits is absorbed by the nature of the
power applied ; but although a cursory notice of
the accounts would prompt this conclusion, .few
would imagine, without giving the matter very
close attention, how great this portion is. Some
idea of it may be drawn from the following facts:
—Each train on railways is drawn by an engine,
the average weight of which is 20 tons : therefore
20 tons carried with each train is perfectly useless.
On the London and Birmingham Railway the
lowest charge for goods is £2 per ton, for the
whole 112 miles. Supposing, for the sake of
argument, the expense of maintaining and working
the locomotive department to remain unaltered,
but the engines to weigh nothing; it is clear that
the Company would be able to transport 20 tons
more with each train for the same coat, or 15 tons
of profitable merchandise, after deducting one-
fourth for the waggons, wliich at £2 per ton
92
would add to their revcuxie ¿^30 per journey, or,
with their present number of trains, (12 each way
daily)—3^306,000 a year. No doubt tfiis fact will
take many railway proprietoi-s by surprise, who by
a natural course of reasoning will immediately
seek to discover by what means so large an amount,
at present wasted, can be made to find its way
into their pockets. The means are obvious : the
waste is occasioned by transporting useless weight j
remove the useless weight, and the objection
ceases of itself. Before the introduction of the
atmospheric system, it was hopeless, by any
known mechanical means, to effect this ; every
previous application of power carried considerable
useless weight with it. The atmospheric is en¬
tirely free from this objection ; and it was mainly
from a knowledge of the benefits that must result
from this source that we have laboured so inces¬
santly (and happily with such success) to mature,
and bring it before the public, for their conside¬
ration and approbation.
" Such would be the effect of dismissing only
the useless weight; but add to this the other ad¬
vantage possessed by the atmosplieric system, and
93
the London and Birmingham Railway (notwith¬
standing its present large capital sunk) would be
enabled to carry passengers at 5s. each, and
goods at 6s. 3d. per ton, the whole 112 miles, and
share the some dividend as now.
The calculations from which this statement is
adduced are shown as follows ; viz.*
Per day. Per year.
2500 persons at 5s. each .... £625
5930 tons merchandise at 6s. 3d.
per ton 1853
362478
Year's Income ¿6805,350
Expenses, viz.— -
Coals, 38 stations x SOOlbs.
per hour x 16 hours per day
= 6867 tons per year, at
10s. per ton 3,434
• This estimate of traffic is of course much gieater
than at present exists on the line, but considerably less
than the reduced prices would produce : it is scarcely
necessary to add, that at these rates any extent of traffic
could be obtained in coals and iron alone, as it is less
than a sea-borne freight from the north.
94
J'en year.
Year's income brought forward , ¿6805,350
Year's expenses brought for. ¿63,434
76 engine-drivers at
¿6100 per year ¿67,600
76 stokers at ¿650
a year 3,800
Repairs to engines,
oil and tallow, at
£70 each X 38 2,660
14,060
Renewal of travelling appara¬
tus, composition, charcoal,
&c. £100 per mile X 112 11,200
Maintenance of way and
attendance to main ¿6300
per mile 33,600
Police, coaching, waggons,
&c. (as on locomotive
lines) 80,604
General charges (as on loco¬
motive lines) 15,400
Parish rates (as on locomo¬
tive lines) 14,400
Add 5 per cent, interest on
¿61,500,000, the total
amount required to furnish
the atmospheric apparatus
i on a scale fortransporting
9600 tons per day 75,000
247,698
Balance,
£557,652
By reference to the last Gene¬
ral Meeting of the London
and Birmingham Kailway
Company, (see " Kailway
Times," 13th February,
1841,) the present re¬
ceipts average per year £810,000
And the present expenses. . 260,000
Balance £550,000
The present charges are—
For passengers (average). . . . 25s. each.
Lowest charge for merchandise 40s. per ton.
" We have already shown the expense of forma¬
tion in railways to be greatly influenced by a portion
of the power employed being unavailable, and
that the road is levelled as a convenience for the
propelling power, not the traffic conveyed. We
have also shown that the destruction to the road
is attributable to the weight and shocks of the
engines, not of the trains ; that the enormous
expense of locomotive power and coke arises from
the bad application of power and the artificial
means employed to work engines at an unnatural
speed. In other words, all the expenses have
96
been traced home to the use of locomotive engines,
which have, from the opening of railways for
passenger traffic to the present day, been a source
of continual annoyance and vexation ; breakage
after breakage has occurred, and been succeeded
by increasing the weight and power of the ma¬
chines ; this in turn has led to the necessity of
increasing the strength and stability of the rails
and foundations on which they travel, and in¬
creasing the strength of the passenger-carriages,
to resist any shocks they may occasionally receive
from their ponderous neighbour ;—until we have
arrived at this conclusion, that on an iron railroad,
where the surface is by comparison smooth and
the track marked out, a carriage to convey
eighteen passengers must weigh about 3 tons,
while over a rough paved road an omnibus weigh¬
ing only 1 ton will perform the same amount of
duty. Here are facts which must at once convince
every one that there are in the present system,
radical defects to be weeded out : if no remedy
were suggested, it might be difficult for Railway
Companies to determine how to extricate them¬
selves from their present position ; but under
97
existing circumstances their position is by no
means a difficult one." •
If these arguments still hold good in refe¬
rence to the atmospheric principle of Clegg and
Samuda; notwithstanding the various improve¬
ments which have taken place in i steam loco¬
motive, since the date of Mr. Samuda's writing,
and founded as they are on truth and sound
reasoning it cannot be otherwise, how much more
forcible do they become when applied to the
system of Pilbrow, where the first cost of the
alteration and subsequent expense of working are
so materially diminished, and the charges of
transit and travelling may be reduced at least one-
fourth more, and yet afford the same amount of
profit. It is useless to contend that the diminu¬
tion of fares and charges for transit of merchan¬
dize does not increase the amount of traffic, and
that only a limited quantity of traffic will take
place whatever may be the amount charged. The
fact is abundantly disproved by the working of
pleasure trains, and the establishment of penny
trains, which have already carried thousands of
persons who would never have travelled by railway
K
î»8
conveyances, unless such economical charges had
been adopted.
All the objections that I have^hitherto seen or
heard urged against the atmospheric principle
appear to me to be untenable, and little more than
the cavillings of interested paVties against means
they are unwilling to see adopted. There will
necessarily be difficulties in the commencement,
we cannot expect perfection on the outset, but the
principle being correct, all apparent defects wUl
readily be remedied by practice and experience.
In conclusion, it is impossible to calculate the
immense advantages that must flow from the
adoption of this principle, ^or even to form a
limited idea of the immense boon conferred by its
inventors, Clegg and Samuda, not alone on the
members of the British empire, but on the whole
family of man. Proudly and justly may they
adopt the motto, " Exegimonumentum aere peren-
nmm," it is, however, to be regretted that ere
sufficient time could elapse to enable them to reap
that ample remuneration which their sanguine
expectations anticipated, and their energies and
application so richly deserve, their prize is likely
99
to be borne off by the inventor of anotlier adap¬
tation of the same principls, more important to
the public, because more simple in its application
and more economical its working.
The merit of demonstrating the practicability
of the atmospheric principle, and bringing it fairly
before the public, is entirely due to Messrs. Clegg
and Samuda, the expenses thereof have been
borne entirely by them, and their friends, and
should it so happen that the application they have
adopted should be superseded by others, it will
require very little argument to show that to them
the public is largely indebted, and that, either by
public subscription or Parliamentary grant, some
remuneration should be secured to them.
Parliamentary grants have been voted to parties
having less claims on the public than these gentle¬
men, and a similar liberality in the present instance
would not only be their just due, but would act as
a stimulus to future inquirers, by convincing them
that should they fail in obtainingjall they antici¬
pated, a wise and liberal government would amply
reward their energies and exertions, should they
succeed in promoting the public good.
100
Since the foregoing went to press, a Select
Committee having been appointed by the Honour¬
able House of Commons to inquire into the At¬
mospheric System of Railway, consisting^ of the
following gentlemen :—
Mr. Shaw.
Mr. Bingham Baring.
Lord Harry Vane.
Sir George Clerk.
Mr. Baring.
Viscount Mahon.
Sir Charles Lemon.
Mr. Hawes.
Viseount Howiek.
Mr. Hodgson Hinde.
Mr. Morrison.
Mr. Pakington.
Mr. Gibson Craig.
Mr. Lascelles.
Mr. Wyse.
with power to send for persons, papers and records,
and report their opinion to the House ; we have
deemed it advisable to annex their Report by way
of appendix.
APPENDIX.
The Select Committee appointed to inquire into
the merits of the Atmospheric System of Rail¬
way have examined the matters to them re¬
ferred, and haveagreedto thefollowingreport :—
Your Committe have given their best attention
to this interesting subject. Adverting to the great
number of railway bills now in progress, they
consider that one of the most practical results of
this inquiry would be lost if their report were
delayed until after these biUs had passed through
committee, and a decision had already been made
on their comparative merits.
Your Committee have endeavoured therefore to
present to the House, with as little delay as is
consistent with the due discharge of their duty,
the evidence which they have taken, and the
opinions to which they have come ; and they trust
that their labour may not prove altogether useless
to the committees that have to decide on the par¬
ticular railway schemes now pending.
K d
102
The House are aware that a railway on the at¬
mospheric principle is already in operation
between Kingstown and Dalkey, in Ireland.
The first object of your Committee was to
make a full inquiry into the result of this expe¬
riment. From Mr. Gibbons, Mr. Bergin, and
Mr. Vignoles, gentlemen oifieially connected with
the Kingstown and Dublin and Kingstown and
Dalkey Railways, they received the fullest and
frankest evidence on all the points connected with
their management. Your Committee had also the
advantage of the opinion of Dr. Robinson, of
Armagh, whose scientific knowledge and acquire¬
ments render his testimony particularly valuable
on the theoretical merits of such an invention.
From this evidence, and from that of Mr.
Samuda, it appears that the Dalkey line has been
open for 19 months, that it has worked with
regularity and safety throughout all the vicissi¬
tudes of temperature, and that the few interrup¬
tions which have occurred have arisen rather from
the inexperience of the attendants, than from any
material defect of the system.
Your Committee find, moreover, that high
velocities have been attained with proportional
loads on an ineliije, averaging 1 in 11.5, within a
course in which the power is applied only during
one mile and an eighth.
These results have been displayed under circum¬
stances which afford no fair criterion of what may
be expected elsewhere ; for, in addition to the
curves on the line, which would have been con-
103
sidered objectionable, if not impracticable, foi-
locomotive engines, there are alleged to exist
defects in the machinery and apparatus, occa¬
sioned partly by the difficulties of the situation,
partly by mistakes inseparable from a first attempt,
which very seriously detract from the efficiency
of the power employed, for the remedy of which
provision has been made in the experiments now
in progress.
These are important facts. They establish the
mechanical efficiency of the atmospheric power
to convey with regularity, speed, and security,
the traffic upon one section of pipe between two
termini ; and your Committee have since been
satisfied, by the evidence of Messrs. Brunei,
Cubitt, and Vignoles, that there is no mechanical
difficulty which will oppose the working of the
same system upon a line of any length. They
are further confirmed in this opinion by the con¬
duct of the Dalkey and Kingstown directors, who
have at this moment before Parliament a proposi¬
tion to extend their atmospheric line to Bray.
In addition to the witnesses already mentioned,
your Committee have had the advantage of hear¬
ing the objections urged by Messrs. Nicholson,
Stevenson, and Locke, against the adoption of
the atmospheric principle, and the grounds of
their preference for the locomotive now in use.
Your Committee must refer the House to the
valuable evidence given by these gentlemen. It
will be seen that great difference of opinion exists
between them and the other witnesses to whom
104
your ComiuiUct' have beibi'e referred, both in
their esiitnatioii of what has already been eii'eeted,
and in their calculations of future improvement.
But without entering upon all the controverted
points, your Committee have no hesitation in
stating, that a single atmospheric line is superior
to a double locomotive line both in regularity and
safety, inasmuch as it makes collisions impossible
except at crossing places, and excludes all the
danger and irregularity arising from casualties to
engines or their tenders. Now, the importance
of these considerations will be best estimated by a
reference to the return of accidents for 15 months
appended to this report. It will there be seen
that there have been during that period 14 colli¬
sions upon the road, and 13 accidents to engines,
which would altogether have been avoided on the
atmospheric system, and that these casualties
entailed the loss of 11 lives, as well as the serious
injury of 45 persona. From the other 20 acci¬
dents, common to both systems, resulted only
four deaths, and two persons injured. There is
certainly one case in which the engine passed
uninjured over cattle lying upon the road, toge-
thei- with its entire train ; but then against this
security derived from the advantage of weight in
surmounting obstacles, must be set the great
danger to which the engine driver and stoker are
exposed, standing as they do upon an open
platform.
Your Committee desire also to bring to the
attention of the House a peculiarity of the atmo-
105
spheric system which has been adduced by the
objectors to prove how unsuited it must be profit¬
ably to carry on a small and irregular traffic—
namely, that the greatest proportion of the ex¬
penses of haulage on the atmospheric principle
are constant, and cannot be materially reduced,
however small the amount of traffic may be. This
is, no doubt, a serious objection to the economy
of the atmospheric system under the circumstances
above alluded to. But, on the other hand, as the
expenses do not increase in proportion to the fre¬
quency of the trains, it is to the interest of com¬
panies adopting the atmospheric principle to in¬
crease the amount of their traffic by running fre¬
quent light trains, at low rates of fare ; by which
the convenience of the public must be greatly
promoted. Upon an atmospberic railway the
moving power is most economically applied by
dividing the weight to be carried into a consider¬
able number of light trains. By locomotive en¬
gines, on the contrary, the power is most con¬
veniently applied by concentrating the traffic in a
smaller number of heavier trains. The rate of
speed at which trains of moderate weight can be
conveyed on an atmospheric line makes compara¬
tively little difference in the cost of conveyance ;
while the cost of moving trains by locomotive
engines increases rapidly with the speed.
Now, when it is considered that we surrender
to great monopolies the regulation of all the
arteries of communication throughout the king¬
dom, that it depends in a great measure upon
lOíj
their view of tlieir interest when we shall travel,
at what speed we shall travel, and what we shall
pay, it becomes a material consideration, in
balancing the advantages insured to the public by
rival systems, to estimate, not so much what they
respectively can do, but what, in the pursuit of
their own emolument they will do.
The main objection of the opponents of the
atmospheric system seem to rest — 1st, on the sup¬
posed increased expense of the atmospheric appa¬
ratus over and above the saving made in the con¬
struction of the road ; 2nd, on the inconvenience
and irregularity attending upon a single line.
With reference to the last point, your Committee
felt it their duty to direct their first attention to
the question of security, and they have already
stated that there is more security in a single at¬
mospheric line than in a double locomotive. They
may further observe, that they find the majority
of the engineers who have been examined are
decidedly of opinion that any ordinary traffic may
be carried on with regularity and convenience by
a single atmospheric line.
Mr. Brunei has proposed to double the line in
those places where trains are intended to meet ;
and he has further shown that in a hilly country,
with long planes of sufficient inclination to allow
of the descent of trains by the unaided power of
gravity, it might be possible to effect this object
without the expense of the tube.
With respect to expense, and to some other
contested points, your Committee do not feel
107
themselves competent to reporta cleciJecl opinion.
It would scarcely be possible at the present time
to institute a fair comparison of a system which
has had 15 years of growth and development,
with another which is as yet in its infancy. That
comparison would, after all, be very uncertain ;
it must depend much on details of which we are
ignorant, much on scientific knowledge which we
do not possess.
There are, however, questions of practical im¬
portance, having reference to the present state of
the railway bills before the House, to which your
Committee consider themselves bound to advert.
There is a doubt raised in the Keports of the
Board of Trade, whether the atmospheric system
has beeti sufficiently tested to justify the prefer¬
ence of a line which can only be worked on the
atmospheric system, or which presents gradieut.s
less favourable than a competing line for the use
of the locomotive engine.
If it were practicable to suspend all railway
legislation until the result of the Devon and
Cornwall, and of the Epsom and Croydon atmo¬
spheric lines were known, it would be, perhaps,
the most cautious and prudent course to await
that result ; but such a course, independent of all
considerations of e.vpediency, is evidently im¬
practicable. Your Committee venture, therefore,
to e.xpress their opinion to the Ilcuse, that in
deciding between competing lines of railway, those
which have been set out to suit the atmospheric
principle ought not to be considered as open to
108
valid objection merely on account of their havii
gradients too severe for the locomotive, nor shoe,
they be tested .in comparison with other Un
solely by the degree of their suitableness to t)
use of the locomotive.
No doubt, in matters like these experience alo
can decide*the ultimate result, but your Committ
^'bliiivk that there is ample evidence which wou
jicstify t^ {^option of^^n atmospheric line at t'
present time. All the witnesses they have es
amined concur in its mechanical success. M)'
Bidder says, " I consider the mechanical probler
as solved, whether the atmosphere could be mai
an efficient tractive agent. There can be i
question about that; afid the apparatus worke
as far as I have observed it, very well. The oif
question in my mind was as to the commerci
application of it." Mr. Stephenson admits tin,
under certain'circumstances of gradients (1,316^
and under certain circumstances of traffic withor
reference to gradients (1,204), the atmospher'
system would be preferable.
While your Committee have thus expressed
strong opinion in favour of the general meritá.x
tlie atmospheric principle, they feel that experient
can alone determine under what circumstances'c,
traffic or of country the preference to either sys;
tem should be given.
April 22, 184.5.
1-'^