A TREATISE ON O It D N A N C E AND ARM OK; EMBRACING DESCRIPTIONS, DISCUSSIONS, AND PROFESSIONAL OPINIONS CONCERNING THE MATERIAL, FABRICATION, REQUIREMENTS, CAPABILITIES, AND ENDURANCE OF EUROPEAN AND AMERICAN GUNS FOR NAVAL, SEA-COAST, AND IRON-CLAD WARFARE, AND TIIEIK RIFLING, PROJECTILES, AND BREECH-LOADING. ALSO, RESULTS OF EXPERIMENTS AGAINST ARMOR, FROM OFFICIAL RECORDS. AlSf APPENDIX, REFERRING TO GUN-COTTON, HOOPED GUNS, ETC., ETC. BY ALEXANDER L. HOLLEY, B. P. With 493 Illustrations. NEW YORK: D. VAN NOSTRAND, 192 BROADWAY. LONDON: & COM FEISTY. 1865. Entered according to Act of Congress, in the year 1864, BY D. VAN NOSTKAUD, In the Clerk's Office of the District Court of the United States for the Southern District of New York. GIFT A. ALVOKD, KLKCTBOTTPER AND PRINTER. THE "SOLFERINO," DEDICATION. foj i MY DEAR SIR : THE inscription of your name in this work on ORD- NANCE AND ARMOR, is not only gratifying to me on personal grounds, and appropriate from a civilian student in the Art of War, to a civilian ever foremost in improving and devel- oping the materiel of war ; but it is an expression of that respect, shared by my countryn at large, for the liberality and enterprise to which, together with the efforts of your associates, we are indebted for the timely " Monitor," the first home-made steel Ordnance, and the introduction of the Bessemer process. I am, dear Sir, Very respectfully your friend, A. L. HOLLEY. NEW YORK, September 21, 1864. P EE F A C E. ALTHOUGH the want of a work on the construction, requirements, and results of modern Ordnance, will be gen- erally admitted, the attempt of a Civil Engineer to supply it, demands a word of explanation. In Europe, the improvement and fabrication of ordnance, and in America, the additional occupation of war, have so engrossed the attention of the profession, that the compila- tion and publication of the results and the practice, have been almost necessarily neglected. During several visits to Europe, with reference to his own profession, the author had various and perhaps extraordi- nary facilities for acquiring information on the subject. His first intention, seeing that many of the facts had not been published, was to throw them together in the form of one or more pamphlets, with enough comment to make them homo- geneous. But some account of the American practice 1 appeared indispensable ; then an abstract of the opinions of experts, professional and otherwise, was obviously appro- priate and useful ; and, as only the intervals in professional pursuits were devoted to the compilation of the matter, time was constantly developing new facts and phases, which should of course be considered ; so that what was originally x PREFACE. intended as a mere record of results has, unintentionally, and perhaps unavoidably, grown into the present treatise. If the voluminous and, certainly, the important facts, have been so presented as to aid the profession in improving the great art of Defence, the highest expectation of the author will have been realized. As to the discussions and conclusions, he should say, in justice to himself, that, although they have not been aided by professional training and experience, they certainly have not been influenced by partisanship, nor by professional traditions and prejudices. ' to CONTENTS. PART FIRST. ORDNANCE. CHAPTER I. STANDARD GUNS AND THEIR FABRICATION DESCRIBED. Section I. Hooped Guns. PAGE I. THE ARMSTRONG GUN. Details of Fabrication: Breech-Loading; Rifling; Par- ticulars, Charges, and Number made; Proof; Service and Experimental Guns described; Cost; Endurance; the new British Gun 1 II THE WHITWORTH GUN. Principles; Fabrication; Rifling; Particulars and Charges; Notes on History and Cost 27 III. THE BLAKELY GUN. Structure; Two Principles involved; Particulars and Charges; Description of Guns; Treatment of Steel and Fabrication; Early Experiments 36 IY. THE PABROTT GUN. Fabrication : Material; Particulars; Ammunition; Rifling; Endurance 50 V. MISCELLANEOUS HOOPED GUNS. Spanish Guns Structure and Endurance; French Guns Structure, Particulars, and Endurance; Particulars and En- durance of Cast-Iron Guns tested by Ordnance Select Committee; Longridge's Wire- wound Guns and Cylinders Details of Structure and Experiments; Brooke's Hooped Gun Particulars; Attick's Bronze Reinforce; Atwater Gun; Bumford 12-in. Gun hooped; Mallet's 36-in. Mortar 56 Section II. Solid Wrought-Iron Guns. I, THE MERSEY STEEL AND IRON COMPANY'S GUNS. The Horsfall Gun Fabrica- tion, Particulars, and Endurance; the Prince Alfred Gun; Brooklyn Navy Yard 12-in. Gun; New Guns for British Government Particulars and En- durance. II. THE STOCKTON GUNS. III. MISCELLANEOUS SOLID WROUGHT- IRON GUNS Thomas's, Ericsson's, Ames's 81 Section III. Solid Steel Guns. KRUPP'S GUNS. Fabrication; Relative Strength; Weight and Cost; Description of 8 and 9-in. Guns, and Guns for Russia; Details of Endurance in England and France; Capacity of Works. BESSEMER GUNS. Production and Charac- ter of the Material; Test; Prices; Naylor, Vickers & Co.'s Gun-Steel; Details of Test of 20-Pounder; Mushet and Clare's 20-Pounder; Endurance. MERSEY PUDDLED-STEEL GUNS. . 90 xx CONTENTS. Section IV. Cast-Iron Gun*. PAGE RODMAN and DAHLGREN GUNS. Figure, Fabrication, and Test of Hollow-Cast Guns; Test of New Ordnance; Columbians; New Guns 20-in. Guns; Particu- lars and Charges of U. S. Army and Navy Ordnance; British Cast-Iron Guns Endurance, Particulars, and Charges; Miscellaneous Cast-Iron Guns and Mortars Particulars and Charges; Russian Cast-Iron Guns Cost of Guns.. 106 CHAPTER H. THE REQUIREMENTS OF GUNS ARMOR. Section I. The Work to be Done. Necessity of Iron-Clads; Unsettled State of the Question; Two Systems of de- stroying an Iron-Clad Enemy Racking and Punching Denned and Illus- trated; Effect of Velocity; One Gun cannot do both Kinds of Work 132 Section II. Heavy Shot at L.OW Velocities. EXPERIMENTS. 15-in. B.all, 10-in. Iron; 11-in. Ball, 10-in. Iron; 11-in. Ball, 14-in. Iron; 15 and 11-in. Balls and Parrott 150-lb. Bolt Various Plates Late Ex- periments; 15-in. Ball, Iron-Clad Atlanta; 13-in. Steel Shell, Warrior Target; 13-in. Steel Bolt, 11-in. Iron; 13-in. Ball, 4|-in. Iron; 13-in. Ball and 131-lb. Steel Shot, Warrior Target; 10-in. Ball, Warrior Target; 150, 230, and 307-lb. Bolts and 113-lb. Ball, and 12 and 13-in. Target; 300 and 330-lb. Bolt, 7 fin. Target; lOf in. Ball, Scott Russell's Target; 10^-in. Ball, Minotaur Target; 301-lb. Bolt and 150-lb. Ball, Chalmers Target; 150-lb. Ball and 300-lb. Bolt, BeUerophon Target; 110-Pounder, Plates on Masonry 138 DETACHING ARMOR BY HEAVY SHOT. CONSIDERED. Quality of Plates; Fastening Armor; Targets compared as to Effect of Vibration; 15-in. Ball better than Rifle-Bolts 151 SOLID AND LAMINATED ARMOR. Strength compared; Inferior Resistance of Lami- nated; 68-Pounder and 110-Pounder against Laminated 6-in. and 10-in. Tar- gets; Backing; 130-lb. Bah 1 against 6^-in. Laminated Target compared with 150-lb. Ballon 4|-in. Solid Plate; Cause of greater Resistance of Solid Plate; Solid and Laminated Armor combined; Wire-Rope Bolt 154 SMASHING SHIPS' SIDES BY HEAVY SHOT, CONSIDERED. Cannot be judged from Small Targets; lUustrations; Popular Theory of Destroying Armor by Shot of Medium Weights and Velocities its Error; Local Effect prevents Distributed Effect, and vice versa; Examples; Object not to destroy Armor, but the Enemy within it 158 DUCTILITY OP ARMOR SAVES THE VESSEL UNDER VERY LOW VELOCITIES OP SHOT. Effect of Rams; Ductility illustrated by Thames Iron Works Plate; Difference in Quality of Armor illustrated by American and English Plates 167 DIFFICULTY OP ADAPTING THE HEAVY SHOT SYSTEM. Difference in Range and Armor changes Conditions of Useful Effect; Other Defects of the System; Too much Time required; Armor hurt more than the Enemy; Illustrations; Broken Plates still a Protection against Shells; Greater Strains in Large Guns; Blakely's and Scott's Calculations HI CONTENTS. xxi PAGE ADVANTAGE OP SINGLE HEAVY SHOT OVER MANY LIGHT SHOT. Commander Scott's Results; Effect of Salvos; Recapitulation 176 Section III. Small Snot at High Velocities. EXPERIMENTS. Law of Resistance; Quality of Armor; lO^-in. Ball, Warrior Target; 10-J-in. Ball, Minotaur Target; 13-in. Ball, Warrior Target; 301-lb. Bolt, Chal- mers Target; 130-lb. Steel Shell, Warrior Target; 151-lb. and 130-lb. Steel Shells, 4i and 5|-in. Plates; 288-lb. Steel Shell, 5fin. Plate; 148-lb. Steel Shell, 5|-in. Plate; 300-lb. Steel Shells, 4-in. Plate (Russian Experiments); 610-lb. Bolt, Warrior Target; 15-in. Ball, 6-in. Iron; 11-in. Ball, 4^-in. Plate, "Wood Backing and Pacing 179 AMERICAN ARMOR-PUNCHING GUNS CONSIDERED 188 CONDITIONS OF GREATEST EFFECT. Law of Penetration; Examples; Conditions of High Velocity; Mr. M. Scott's and Sir W. Armstrong's Views; Velocity of Round and Rifled Shots; Remediable Defects of the Smooth-Bore; Captain Fishbourne's Views; Greater Liability of Balls to waste Power in Self-De- struction, and their greater Penetrating Area; Effect of Lead Shot on Iron Plates; Merits and Defects of Light Elongated Projectiles.; Sub-Calibre Pro- jectiles; Necessity of Rifling; Armor-Punching Shells; Long Range Fight- ing; Loss of Velocity of Round Shot : 192 RANGE OF IRON-CLAD WARFARE. Probability of Short Range; Importance of Rifles for other Purposes; Kind of Rifles required 203 SHOT OF LARGE DIAMETERS. Ranges of Large Balls 13-in., 15-in., 9'22-in. ; Strain of Large Balls on the Gun; Professor Treadwell's Views 205 MERITS AND DEFECTS OF THE SYSTEM. Least Power "Wasted by High Velocities and at Short Ranges; Destructive Effects in Turrets; Splinters; Illustrations; Sir Howard Douglass's Views; Advantage of Laminated Armor in this Re- gard; Punching below Water; Mr. Whitworth's Experiments; Armor- punching Shells; Effects considered 212 Section IV. The Two Systems combined. Merits and Defects of each Reviewed; the Two Kinds of Shot prepare the Way for each other, and less Power is Wasted 218 GENERAL CONCLUSIONS 220 Section V. Breaching Masonry. ABSTRACT OF REPORT OF ORDNANCE SELECT COMMITTEE ON BREACHING MARTELLO TOWERS WITH SMOOTH-BORED AND RIFLED GUNS. Towers, Guns, and Charges; Expenditure of Ammunition; Masonry Displaced; Times of Plight; Velocity; Conclusions on the Value of Different Projectiles 222 BREACHING FORT PULASKI (From the Report of General Gillmore). Description of Work; Shot fired; Guns; Penetration; Conclusions 227 BREACHING FORT SUMTER (From the Report of General Gillmore). The Work; Ranges and Nature of Batteries; Projectiles thrown; Character of Breach... 229 BREACHING FORT WAGNER (From the Report of General Gillmore). Metal required to remove Sand Armor 230 xxii CONTENTS. CHAPTER III. THE STRAINS AND STRUCTURE OF GUNS. Section I. Resistance to Elastic Pressure. PAGE PRESSURE. Four Kinds of Strains brought on Guns, and their Relation 233 I. INCREASING THE THICKNESS OF THE WALLS. Rule for Increase of Strength ; Il- lustrations; Captain Blakely's, Professor Treadwell's, and Mr. Longridge's Demonstrations 234 II. HOOPS WITH INITIAL TENSION. Theory; Professor Treadwell's Plan; Another Use of Hoops 240 DEFECTS OF THE SYSTEM. Want of Continuity; Mr. Longridge's Demonstration; Theoretical Accuracy of Tension; Difficulty of attaining it 245 FORCING ON HOOPS. Shrinking on Hoops; Unequal Shrinkage of Metal; Experi- ments; Want of Continuity of Substance; Permanent Enlargement of Hoops under Strain; Elasticity; Safety due to Ductile Hoops; Influence of Ranges of Elasticity in Different Parts; Defects of Wrought-Iron Hoops in this Regard 250 LONGITUDINAL STRENGTH. Dahlgren's Breech-Strap; Views of Siemens, Blakely, Parsons, and Lancaster; How Provided by Whitworth, Lancaster, Blakely, Parrott, and Armstrong; Length of Hoops 256 WIRE- WOUND TUBES. Defects and Advantages 264 III. HOOPS WITH VARYING ELASTICITY. Theory; Advantages; Notes on the Origin of the System; Experiments; Mr. Parsons' s Method and Demonstra- tion; Defects; Captain Palliser's Theory, Method, and Experiments; Captain Blakely's Specification and Practice 266 Section II. The Effects of Vibration. 281 Section III. The Effects of Heat. Theory ; Mr. Wiard's Views ; Remedy 283 CONCLUSIONS 285 CHAPTER IV. CANNON METALS AND PROCESSES OF FABRICATION. Section I. Elasticity and Ductility. ELASTICITY. Use; Limit of in Metals Experiments; Heavy and Light Forgings; Statements of Colburn, Clark, Mallet, and Anderson 288 DUCTILITY. Gain of Strength by Stretching Experiments; Effect of Sudden Vibration and Different Rates of Application of Force; Experiments; Safety of Ductility in Guns; Work done in Stretching Metals to and beyond the Elastic Limit; Mr. Mallet's Reasoning and Illustrations 292 Section II. Cast Iron. Weakness a Serious Objection; Tensile Strength; American and British Irons; Rifled Guns; Endurance of Guns; Greater Shrinkage of Strong Irons Ex- periments Cause; Want of Uniformity in the Same and Different Irons; Chemical Differences; Detection of Failure in Guns 308 CONTENTS. xxiii PAGE DEFECTS IN FOUNDING. Solid-Cast Guns; Initial Strains; Effect of Time in Re- moving Strains; Effect of Heat of Firing; Want of Density in the Grim 318 IMPROVEMENTS IN FOUNDING RODMAN'S PROCESS. Hollow Casting; Objects; Requirements; Effects of Rapid and Slow Cooling; Defects from Exterior Cooling; Actual State of Strain in the Gun; Advantages; Effects of Heat of Firing; Density of Metal 322 WIARD'S PROCESS. Object; Structure of Gun; Probable Advantages and Defects; State of Strain; Effect of Heat of Firing 326 SHAPE or GUNS. Effect of Re-entering Angles on Initial Strength 331 RESISTANCE TO CONCUSSION AND WEAR 332 WEIGHT AND COST 332 Section III. Wrought Iron. Tensile Strength; Uniformity; Deterioration Causes; Detection of Weakness; Safety; Resistance to Compression and Wear; Experiments; Testimony about Armstrong Guns; Compression of Gun-Chambers; Hardness; Manner of Corrosion 334 WANT OF HOMOGENEITY. Welds; Strength of Coils in Armstrong Gun; Shape; Weight and Cost of Guns 344 SYSTEMS OF FABRICATING- WROUGHT-IRON GUNS SOLID FORGING. Defects Im- perfect Welds; Causes; Maintained Heat; Longitudinal Direction of Fibre; Effect of; Small Hammers; Effects of; Unequal Cooling and Contraction; Experiments and Illustrations; Strength of Iron in Large Forgings; Advan- tages of the Process; Failure of Forged Guns; the "Peacemaker;" Fabrica- tion; Appearance of Fracture; Strength of Metal; Professional Opinions 348 HOLLOW FORGING AND ROLLING. Mersey Iron and Steel Company's Process; Griffen's Process; Rolling up a Gun from a Plate; Yeakel's Plan; Ames's Process 363 THE ARMSTRONG GUN. Process of Fabrication; Leading Features; Advantages of the System; Strength and Endurance of Guns; Guns Returned for Repair; Nature of Injury. Defects of the System; Failures before Issue; Softness and Compression by the Powder-Gas; Examples; Stretching of Hoops ; Frac- ture due to Vibration; Failure of 10^-in. Guns; Causes; Defects of 12 0-Poun- der Shunt and Small Guns; Defective Welds; Resistance to Enemies' Shot; the System for Heavy Guns Considered; Great Cost of the Process 366 WELDING. Nature of the Process; How to perfect it; Cinder; Shape of Surfaces; Exclusion of Oxide; Gas Welding; Bertram's Process and Results 382 HITCHCOCK'S SYSTEM OF FABRICATING GUNS. Description; Principles; Comparison with Armstrong System; Making Hoops of Iron and Steel 385 Section IV. Steel. High and Low Stee* Defined; Uses of Elasticity and Ductility Iron and Steel Compared; Work of Guns and Armor-Plates Compared; Steel Hoops; Cost, Weight, Quality; Improvements and Prospects of the Steel Manufacture; Causes of Previous Failure of Steel Guns; Strength of Steel; Uniformity; Temper Test by Specific Gravity; Effect of Treatment; Resistance to Com- pression and Wear; Strains on a Homogeneous Tube Remedies 388 xxiv CONTENTS. PA6E METHODS OP PRODUCING STEEL. Puddled Steel; Low Crucible Steel; Krupp's Steel Specimens Exhibited; Bessemer Steel Process Illustrated To be used in America Specimens produced; Aboukoff's Steel: French and Amer- ican Experiments 406 SYSTEMS OP FABRICATION. Solid Forging; Forging Hollow; Compressing by Hydraulic Machinery; Rolling and Joining Hoops; Solid Cast-Steel Guns. . . 414 Section V. Bronze. Properties; Fitness for Guns; Strength; Difficulties of Manufacture; "Where and how successfully used . . 418 Section VI. Other Alloys. Phosphorus and Aluminium with Copper Properties and Strength; Sterro-Metal; Austrian and English Experiments on its Strength and Properties 422 CONCLUSIONS 428 CHAPTER V. RIFLING AND PROJECTILES STANDARD FORMS AND PRACTICE DESCRIBED. Early Experiments. Russian; Cavalli's; Wahrendorf's; Timraerhaus's; Germs of all the Present Sys- tems.. 431 The Centering Sytcm. Explanation; Modifications; FRENCH, Early, Present, and Experimental; Field and Naval Guns 432 AUSTRIAN. Early; Modern for Guu-Cotton ; Eccentric Shot; RUSSIAN; SPANISH; French System in other European Countries 437 LANCASTER. in the Crimea; Experimental. Iladdan; Early and Experimental. . 440 WHIT WORTH. Principles and Improvements Illustrated; Machine-dressed Pro- jectiles; Standard Projectiles; Tables of Practice 442 SCOTT'S "Centrical" System; Explanation; Experimental Projectiles; Lynall Thomas's New System; like Scott's; Practice 447 SAWYER; PATTISON 449 The Compresing Sytem. Explanation; Early PRUSSIAN 451 ARMSTRONG. Principles and Changes ; Going out of Use ; Coating Projectiles with Lead; Segmental Shell; Cartridges; Tables of Practice; Armstrong and Whitworth Competition 452 SHUNT. Principles and Operation; Changes; Table of Practice; Particulars and Results of 600-Pounder; Russian Shunt Rifling; Particulars 460 CONTENTS. xxv The Expansion System. PAGE Explanation; American System; JAMES; HOTCHKISS; LTNALL THOMAS'S Early Results; SCHENKL; REED; BLAKELY 470 PARROTT; Particulars; Diagrams of Accuracy; Tables of Range, Pressure, Prac- tice, and Endurance 477 STAFFORD, BUCKLE, JEFFERY, BRITTEN; Experiments and Charges 478 Armor-punching Projectiles. WHIT WORTH; Manufacture of Shot and Shells; How Shells are fired; Early Practice 492 SCOTT; PARROTT; STAFFORD; BATES 495 Shells for Molten Metal. LANCASTER; SCOTT 500 Competitive Trial of Rifled Guns, 1862. Description of Guns; Britten; Thomas; Jeffery; Haddan; Lancaster; Scott; French; Shunt; Cost of Projectiles; Tables of Particulars; Endurance; Ac- curacy; Adaptation to Round Shot; Efficiency of Shell; Liability to Injury; Velocity, etc. ; Conclusions of Committee 500 DUTY OF RIFLED GUNS. General Uses especially, Use in Naval "Warfare; Velocity the most Important Consideration; Object of Rifling 516 ACCURACY. Effects of Want of Symmetry, and Remedy; Position of Centre of Gravity; Friction against the Air; Drift; Rate of Twist; Views of Mr. Longridge, Captain Blakely, Mr. Whitworth, etc.; Character of the Projectile Expanded and Compressed Shot; Views of Major Owen, Commander Scott, etc 520 RANGE. Conditions; Mr. Britten's Conclusions; Form of Projectile; Results of Experiments 530 VELOCITY. Conditions; Systems Compared; Disadvantages of Armstrong's; Windage Advantages in Rifled Guns French Experiments Atwater Gun . 536 STRAIN. Failure of Cast-Iron Guns; Weight of Projectile; Twist of Rifling; Wedging of Projectile; Lancaster and Whit worth Guns Experiments at Woolwich; Character of Groove Scott's System Shunt; Increasing Twist; Character of Projectile; Systems Compared 544 LIABILITY OF PROJECTILE TO INJURY. Systems compared 560 FIRING SPHERICAL SHOT FROM RIFLED GUNS. Systems of Rifling Compared 562 MATERIAL FOR ARMOR-PUNCHING PROJECTILES. Cause of Superiority of Steel; Results of Experiments 564 SHAPE OF ARMOR-PUNCHING PROJECTILES. Mr. Fairbairn's Experiments 568 CAPACITY AND DESTRUCTIVENESS OF SHELLS 569 ELONGATED SHOT FROM SMOOTH-BORES. Mr. Michael Scott's Views; Schemes Bessemer's Mackay's 570 CONCLUSIONS 572 VELOCITY OF PROJECTILES (Table) 576 xxvi CONTENTS. CHAPTER VI. BREECH-LOADING. Advantages and Defects of tbe System. PAGE The Practice with Large G-uns against it in the United States, Russia, and Eng- land; Small Breech-Loaders in France and on the Continent. 580 Material not Adequate in Large Guns Weakened by Breech-Loading Parts 581 Gun Strained by Heat of Gases when rapidly fired Remedy; Minor Objections; Professional Opinions . . 582 Great Advantage Fast Firing; Sighting takes more Time; When Fast Firing is Important; Time of Firing with Breech-Loaders and Smooth-Bores, Large and Small; Probability of quicker Loading Heavy Guns from the Muzzle... . 583 Convenience of Breech-Loading in Turrets 586 Rapid Firing and Cooling Guns by Machinery. Advantages; Fewer Guns and more Rounds; Stevens's Steam Loading and Cool- ing Machinery Described; Use on the Naugatuck; Experiments; Many Plans for Working Heavy Guns allow Steam Loading and Cooling 587 Standard Breech-Loaders Described. ARMSTRONG. Screw Breech-Loader Described; Material; Gas-Check; Defects; Endurance; Wedge Breech-Loader Described; Rapidity of Fire 595 KRUPP. Breech-Loader Described; Forma of Gas-Check; Good Endurance of Trial Guns; Advantages 602 BROADWELL; STORM 605 FRENCH. Adapted from American Plan; Description; Why old Plan failed; Adopted in England; Advantages 608 BLAKELY; NASMYTH Failure of Ordinary Screw 610 WHIT WORTH; Similar Plans; CLAY; CAVALLI; WAHRENDORF; PRUSSIAN; ADAMS; CONCLUSIONS. . 612 PART SECOND. EXPERIMENTS AGAINST ARMOR. Account of Experiments from Official Records, in Chrono- logical Order. Stevens, U. S., 1812; Paixhans, France; Ford on Protected Masonry, England 623 Stevens, 1841; Thin Plates, England, 1846 to 1856, and f-in. Plates, 1850, and 4|-in. Plates, 1854 624 Totten, U. S., Embrasures, 1853 to 1855 626 Floating Batteries, Kinburn, 1855; Stevens, U S., 1856; Burgoyne, French 627 Cast-Iron Blocks, England, 1857 629 4-in. Iron Steel, England, 1856-7 630 Firing through Water, England, 1857 631 Comparison of 68-Pounders and 32-Pounders; Whitworth; 8-in. Plate, England, 1858.. 632 CONTENTS. xxvii PAGE Thorneycroft 14-in. Target, England, 1859 636 Special Committee, England, 1859; various Plates 636 The Trusty 637 4-m- Plates, Armstrong Gun, 1859 638 Jones's Inclined Target 639 Comparison of Elongated and Spherical Projectiles, 1860 642 Thorneycroft 10-in. Target 643 Iron Embrasure, Special Committee, 1861 643 Thorneycroft 10-in. and 8-in. Shields 646 Different Qualities of Iron and Steel, England 653 Armor on Brick- work 654 Inclined Plates ; 6^-in. and 4^-in Plates ; Roberta's Target ; Fairbairn's First Tar- get, England, 1861 665 Captain Cole's Cupola 667 Various Backings, England, 1861 668 Warrior Target, England, 1861 669 Hawkshaw's 6-in. and 10-in. Laminated Shields ; Warrior Target, and "Alfred" Gun 673 Conclusions up to 1862 674 Stevens's Laminated Armor, U. S., 1862 679 " Committee" Target, England, 1862 680 Warrior and " Committee" Targets, England, 1862 684 2-in., 2'35-in., 3-in., and 4'5-in. Plates; Scott Russell's and Samuda's Targets, England, 1862 690 Minotaur Target, England, 1862 697 Warrior Target ; Whitworth Shells, England, 1862 703 Warrior Target ; Horsfall Gun, England, 1862 713 Firing through Water, England, 1862 716 Inglis's Shield, England, 1862 717 Millboard Backing, England, 1862 723 Wire Target ; Inclined Laminated Targets ; 4-in. Plates, and Rubber and Oak Backing, U. S., 1862 724 8-in. Plate, Parrott Gun; Iron-Clad Atlanta; 10-in. Solid and Laminated Targets; 15 and 11 inch Guns, U. S., 1863 733 14-in. Target; Laminated Target; 4^-in. Plate; Nashua Target, U. S., 1863 734 5, 6, and 7^ in., Brown's Target, England, 1863 737 4-in. Solid Plate, Rubber Facing and Wood Backing, U. S., 1863 744 Chalmers's Target; Clark's Target ; England, 1863 746 4-in. Plate, 12-in. Oak Facing, 20-in. Backing; Sandwiched Iron and Rubber, U. S., 1863 753 Warrior Target, St. Petersburg, 1863 757 Belkrophon Target, England, 1863 760 13-in. 610-lb. Shell, 4^-in. Plate, 11-in. Plate, and 6^-in. Plate, England, 1863-4. . 765 15-in. and 11-in. Balls and Parrott Shot; Various Plates, U. S., 1863-4 766 Steel Shot against Armor, England, 1863-4 766 Nasmyth's Wool Target, England; Brady's Hog's-hair Target, U. S., 1864 772 Mantelets for Embrasures 775 La Flandre Target 778 xxviii CONTENTS. APPENDIX. Report on the Application of Gun-Cotton to Warlike Pur- pose;* British Association, 163. PAGE Chemical Considerations 785 Mechanical Considerations 789 Practical Applications; Experiments against Palisades, Bridges, and Ships 791 System of Manufacture as carried on in Austria 797 Composition and Properties 799 Hydroscopic Qualities , . 803 Information given by Baron Lenk, concerning Manufacture, Nature, and Applica- tion 806 Eeport by Professors Redtenbacher, Schrotter, and Schneider 822 manufacture and Experiments in England. Nature, Application, and Theory of Explosion Scott Russell 832 Guns Hooped with Initial Tension History. Thiery, 1834 837 Chambers, 1849 852 Treadwell, 1855 855 Blakely, 1855 860 Armstrong, Blakely, Treadwell Evidence from the Report of the " Select Com- mittee on Ordnance," on the Question between Blakely and Armstrong, as to Hooping and Material ; Treadwell vs. Armstrong, as to the Method of making Wrought-iron Tubes 863 Parrott's Patents of 1 861 and 1862 870 How Guns Burst, by Mr. Wiard 874 Lymau's Accelerating Gun 885 Endurance of Parrott and Whit wort h Guns at Charles- ton 886 Hooping old United States Cast-iron Guns 887 Endurance and Accuracy of the Armstrong 6OO-Pounder 888 Competitive Trials with 7-in. Gnus 889 LIST OF TABLES. NO. I. Particulars of Service Armstrong Guns 12 n. Service Ammunition of Service Armstrong Guns 12 III. Armstrong Guns issued for Service showing where made 13 III. A. Particulars of Armstrong Guns of the Latest Elswick Patterns 15 IV. Return showing the Amount of Money expended on Plant at Woolwich, for the Manufacture of Armstrong Guns and for other Purposes, from the Commencement of the Manufacture, in March, 1859, to the 31st March, 1862 22 V. Cost of Labor and Material, including all Incidental Expenses, to pro- duce one 100-Pounder Armstrong Gun, ready for Proof, with two Vent-Pieces 24 VI. Return showing the Prices of the Armstrong Guns Manufactured by the Elswick Ordnance Company to March 31, 1862 25 VII. Statement showing the Cost of Armstrong Guns made in the Royal Gun Factories, in which Indirect Expenses on Labor and Material, and Depreciation, are charged 26 VIII. Particulars and Charges of Whitworth Guns 34 IX. Return of Sums paid on Account of Experiments connected with Mr. Whitworth's Proposals 37 X. Particulars of Blakely All-Steel Ordnance and Ammunition 48 XI. Trial of Blakely early 9-Pounder with Service Iron and Brass 9-Pounders 49 XII. Particulars and Ammunition of the Parrott Guns 55 XIII. Particulars and Endurance of the Strengthened Cast-Iron Guns tested by Ordnance Select Committee since 1858 61, 62 XIV. Experiments on Longridge's Brass Cylinders 66 XV. XVI. Results of Experiments on Wire-wound Cylinders 72, 74 XVII. Experiments with Longridge's 2'96-in. Gun 76 XVIII. Approximate Proportions of Dimensions, Weights, and Prices of Krupp's Solid Cast-Steel Blocks and of Guns 97 XIX. Proof of Krupp's 110-Pounder Rifle 98 XX. Proof of Krupp's 20-Pounder Rifle 99 XXI. Proof of Krupp's 40-Pounder Rifle 100 XXII. Particulars and Charges of U. S. HoUow Cast-Iron Army Ordnance.. . . 119 XXIII. Particulars and Charges of U. S. Heavy Cast-Iron Navy Ordnance in Service 120 XXIV. Guns burst at Sebastopol and Sweaborg 124 XXV. Particulars and Charges of British Cast-iron Guns 126-129 xxx LIST OF TABLES. NO. PAGB XXVI. Particulars and Charges of British Mortars 130 XXVII. Cost of Guns 131 XXVIII. Principal Experiments on Smashing and Dislocating Armor, chiefly by Heavy Shot at Low Velocities 162-165 XXIX. Weight of Shot that may be Fired from Various Wrought-Iron Smooth- Bored Guns without Straining the Metal more than that of Service Guns is Strained 1*75 XXX. Showing the Advantage of one Heavy Shot over several Light Shots. 177 XXXI. Principal Experiments with Shot at High Velocities, and Shells against Solid Armor 190, 191 XXXII. Velocities of Parrott (6'4-in.) 100-Pounder, May 1, 1862 194 XXXIII. Effect of Reducing Windage 195 XXXIV. Point-Blank Ranges of 68-Pounder, 100-Pounder, and ]3-in. Gun 196 XXXV. Experiments at West Point on Lead Shot against Armor 200 XXXVI. Work done by Different Guns, the 68-Pounder being taken as Unity. 205 XXXVII. Ranges, etc. Armstrong Muzzle-Loading Smooth-Bore 9'22-in. 100- Pounder 208 XXXVIII. Guns and Charges used in Breaching Martello Towers 222 XXXIX. XL. Ammunition expended in Breaching Martello Towers 223 XLT. Masonry displaced in Breaching Martello Towers 223 XLII. Range, Velocity, Ammunition, etc., of Projectiles used in Breaching Martello Towers 225 XLIII. XLIV. Relative Values and Bursting Charges of Projectiles, and Work done in Breaching Martello Towers 225, 226 XLV. Comparative Penetration of Armstrong Rifled and Spherical Projectiles into Brick-Work at 1032 Yards 226 XL VI. Number, Character, and Range of Shots fired in the Breaching of Fort Pulaski 227 XLVII. Penetration in Brick- Work Fort Pulaski 228 XLVII. A. Range and Nature of Batteries employed in Breaching Fort Sumter. . 230 XL VIII. Radii of Rings for Hooping Guns 249 XLIX. Calculation of the Strength of an Ordinary Service 68-Pounder Cast- iron Gun, by Mr. Parsons 272 L. Calculation of the Strength of the same 68-Pounder, strengthened by a Wrought-Iron Lining Tube 273 LI. Relation of Elastic Limit and of Extension to Ultimate Cohesion 290 LII. Resisting Powers of Krupp's Cast-Steel as Compared with other Metals for constructing Ordnance 290 LILT. Resistant Vis Viva of Elasticity and of Rupture by Tension of the Metals Applicable to the Construction of Ordnance 291 LIV. Properties of Light and Heavy Wrought-Iron Forgings 294, 295 LV. Endurance of a United States 9-inch SheU Gun 312 LVI. Tensile Strength of Wrought Iron Whildin 334 LVII. Tensile Strength of Wrought Iron Kirkaldy 335 LVIII. Resistance of Iron and Steel to Compression Anderson 341 LIX. Expansion of the 40-Pounder Rifle made by the Mersey Iron and Steel Company 343 LIST OF TABLES. xxxi LX. Strength of Heavy and Light Forgings Kirkaldy 356 LXI. Strength of Heavy and Light Forgings Mallet.. .' 357 LXII. Strength of Iron in the " Peacemaker " Gun 359 LXILT. Strength of Iron in the Horsfall Gun 362 LXIY. List of all Armstrong Guns returned to Woolwich and requiring Repairs, to June 3, 1863 .372, 373 LXV. List of Armstrong Guns rendered unserviceable by proving Vent- Pieces 374 LXVI. The Work done in Stretching to Rupture several of the best Speci- mens of Iron and Steel, as tested by Kirkaldy 392 LXVIL Tensile Strength of Low Steel Kirkaldy 400 LXYIII. The Uniformity and Extensibility of Wrought Iron and Steel Com- pared 401 LXIX. Showing that decreasing the Specific Gravity of Steel increases its Ultimate Tenacity and diminishes its Ductility 403 LXX. Showing the Effects of Treatment on Steel 404 LXXI. Hardness of Cannon Metals 405 LXXII. Various Qualities of Cannon Metals 405 LXXIII. Tensile Strength of Sterro-Metal Experiments of Polytechnic Insti- tution, Vienna 424 LXXIV. Tensile Strength of Sterro-Metal Experiments at the Arsenal, Vienna 425 LXXV. Analysis of Austrian Sterro-Metal 425 LXX VI. Composition and Strength of Sterro-Metal, Woolwich 427 LXX VII. Experimental Practice Whitworth Breech-Loading 80-Pounder, Southport, July 25 and 26, 1860 446 LXX VIII. Ranges of Whitworth Rifled Guns 446 LXXIX. Range and Deflection of Lynall Thomas's 9-in. Gun, Shoeburyness, Nov. 20, 1863 450 LXXX. Range and Deflection of Whitworth and Armstrong Guns 457 LXXXI. Experimental Practice Armstrong Breech-Loading 12-Pounder, Shoeburyness, April 2, 1861 458 LXXXII. Experimental Practice Whitworth Breech-Loading 12-Pounder, Shoeburyness, April 2, 1861 459 LXXXIII. Range and Accuracy of Long and Short Armstrong 12-Pounders, H. M. Ship Excellent, May 22. 1861 460 LXXXIV. Range and Deflection Armstrong Side Breech-Loading and Service 40-Pounders 461 LXXXV. Range and Deflection of the Armstrong Side Breech-Loading 70- Pounder 461 LXXXVI. Range and Deviation of the Armstrong 600-Pounder 462 LXXXVII. Range and Deflection of the Armstrong 70-Pounder Muzzle-Loading 6-Grooved Shunt Gun 467 LXXXVIII. Range and Deviation of 70-Pounder Side Aeech-Loading Armstrong Gun 468 LXXXIX. Practice with Armstrong's 7-in. Shunt-Rifled Mortar Shells with Copper and Zinc Ribs 470 xxxii LIST OF TABLES. NO. PAGE XC. Range of, and Pressure in, the Parrott 6-4-in. 100-Pounder Rifle, West Point, July 22-28 478 XCI. Trial of Parrott 6'4-in, 100-Pounder Rifle, by firing it 1000 times with 100-lb. Projectile and 10-lbs. charge, West Point, July ] to July 19, 1862 483 XCII. Trial of Parrott 8-in. 200-Pounder Rifle, West Point, commenced May 28, and ended April 2, 1862 485 XCIII. Trial of Parrott 10-in. 300-Pounder Rifle, West Point, March, 1863 488 XCIV. Endurance of Competitive Rifled Guns 502 XCY. Endurance of Cast-Iron Guns Rifled on Mr. Britten's System 504 XCVL Particulars of Rifling of Competitive Guns 505 XCVIL Windage of Competitive Rifled Guns 506 XCVIII. Bursting Charges of Shells Trial of 1861 506 XCIX. Practice with Rifled 3 2 -Pounder Cast-Iron Guns with Improved Projec- tiles and -/j Charges, 1861-'62 508 C. Practice with Rifled 32-Pounder Cast-Iron Guns with Improved Projec- tiles, 1859-61 510 CL Velocities of Projectiles Trial of Rifled Cast-Iron Guns, 1861-2 511 OIL Practice with Rifled 32-Pounder Cast-Iron Guns, with Improved Projec- tiles and proposed Service Charges, 1861 512 GUI. Showing that the Rifle is more accurate than the Smooth-Bore with Spherical Shot 516 CIV. Twist and Deviation 522 CV. Ranges of Large and Small Rifled Projectiles 532 CVI. Resistance of Bodies to the Atmosphere 535 CVII. Resistance of Bodies to the Atmosphere 536 CVIII. Comparative Ranges of Jeffery and Armstrong Projectiles Jeffery 539 CIX Strain due to Various Kinds of Rifling 551 CX. Windage of Round Shot in Rifled Guns 563 CXI. Resistance of Plates to Flat and Round Punches 569 CXII. Velocities of Projectiles, as determined by the Electro-Ballistic Pendu- lum; and Particulars of Guns compiled from British and U. S. Artil- lery Records 576 CXIII. Penetration of Water and Wood Whitworth 24-Pounder Rifled Howitzer 63 1 CXIV. Penetration of Water and Wood Whitworth 24-Pounder Rifled Howitzer 632 CXV. Penetration of Water and Wood Whitworth 24-Pounder Rifled Howitzer 633 CXVI. Whitworth 68-Pounder against 4-in. Plates H. M. S. Excellent, Oct. 3, 1858 635 CXVII. Experiments against Jones's Inclined Target, Aug. 21, 1861 640 CXVIII. Experiments against Jones's Target placed Vertically, Sept. 18, 1861. . 642 CXIX. Experiments against the Thorneycroft 8-in. and 10-in. Targets, June G, 1861 649 CXX. Experiments against Masonry protected by Iron, May 9, 1861 658 CXXI. Experiments againstthe Warrior Target, Oct. 21, 1861 671 CXXII. Experiments against the "Committee Target," March 4, 1862 682 CXXIII. Experiments against the Warrior Target, April 18, 18G2 685 CXXIV. Experiments against the "Committee Target," April 18, 1862 687 LIST OF TABLES. xxxiil NO. PAGE CXXV. Experiments against 2-in., 2'35-in., 3-in., and 4'5-in. Plates with 12- Pounder and 40-Pounder, and against Mr. Scott Russell's Target and Mr. Samuda's Target, June 26, 1 862 694 CXXVI. Experiments against the Minotaur Target, July 7, 1862 699 CXXVII. Experiments with Whitworth 12-Pounder, 70-Pounder, and 120- Pounder, against the Warrior Target, etc., Sept. 16 and 25, 1862. 706 CXXVIII. Experiments with the Whitworth 120-Pounder and 70-Pounder against 4|-in. and 5-in. Plates, and the 12-Pounder against 2^-in. Plates, Nov. 13, 1862 888 CXXIX. Experiments against Captain Inglis's Second Shield, March 3, 1863. 720 CXXX. Experiments against Wire Target 725 CXXXI. Experiments against Laminated Target 728 CXXXII. Experiments against Inclined Iron and Rubber Target 729 CXXXIII. Experiments against Inclined Iron and Rubber Target 730 CXXXIV. Experiments against Solid 4^-in. Plate, with Rubber and Oak Backing '. 731 CXXXY. Experiments against 54-, 6|, and 7-J-m. Plates, rolled by Messrs John Brown & Co 740 CXXXVI. Experiments against 4-in. Plate, backed with Rubber 745 CXXXVII. Shot and Shell that struck the Chalmers Target 747 CXXXVIII. Experiments against the Chalmers Target 749 CXXXIX. Experiments against 4-in. Plate faced with 12-in. Oak 753 CXL. Competitive Test of Armor-Plates, Portsmouth, Feb., 1864 770 CXL. A. Experiments with Steel Shot on Gunnery Ship Excellent, Feb. 24 and 25, 1864 773 CXLI. Ordnance Committee's Experiments since October, 1859, on Mante- lets for Embrasures to protect Gunners against the Enemy's Rifle- men 775 CXLIL Experiments with Gun-Cotton, Initial Velocities, etc., in 12-Pounder Gun 814 CXLIII. Analysis of Austrian Gun-Cotton Laboratory of Engineers' Com- mittee, 1861 823 CXLIV. Analysis of Guu-Cotton of Various Years 824 CXLV. Analysis of the Gases of Gunpowder and Gun-Cotton 827 CXL VI. Comparison of Pressures and Velocities with Loose and Compressed Powder 890 CXLVII. British Cannon Powder 893 3 LIST OF ILLUSTRATIONS. PAGE THE " NEW IRONSIDES" v THE " SOLFERINO" vi THE " WARRIOR" xi THE " BENTON," perspective view xii " longitudinal section xii " horizontal section xiii cross section through boilers xiii cross section through paddle-wheels , xiii British steel-lined coil gun. Longitudinal section xiv U. S. hollow-cast Columbiad xiv U. S. hollow-cast hooped Parrott gun. Longitudinal section xv Blakely steel and cast-iron gun xv " LA GTLOIRE" xvi French field-gun, mounted. From a photograph xvii Armstrong 20-pounder gun and limber. From a photograph xviii The Armstrong 600-pounder xlvii Parrott 100-pounder, mounted ccxxxii Armstrong Gun. FIG. 1. Bar for coil. Section. 2. Bar coiled to make a hoop. Elevation. 3. Hoop welded and recessed to fit others. Elevation. 4. Furnace for welding hoops into a tube. Section. 5. "Weld thus formed. Section. 6. 110-pounder. Longitudinal section, -&- in. to 1 ft. 7. 12-pounder. Longitudinal section. 8. Field-gun of 1859. Longitudinal section. 9. 10, 11. Top, side, and end of early 12-pounder. 12,13. 12-pounder rifling four times enlarged. Section. 15. Thread of breech-screw. Section. 16. 12-pounder vent-piece, chamber, and projectile. Longitudinal section, ^d size. 17. 110-pounder, showing breech-loading. Longitudinal section, -5% in. to 1 ft. 18. 110-pounder, showing breech. Longitudinal section, f in. to 1 ft. 19. 110-pounder, showing breech. Plan, | in. to 1 ft. 20. 110-pounder, behind vent-piece. Cross section, f in. to 1 ft. 21. 110-pounder, behind vent-piece. Rear elevation, f in. to 1 ft. 22. 10|-inch gun; 300-pounder when rifled. Longitudinal section, -f 6 - in. to 1 ft. 23. 10|~inch gun (the first built) after bursting. From a photograph. 24. 600-pounder mounted. From a photograph. 25. 10^-inch gun ; Arsenal construction. Half-longitudinal section. xxxvi LIST OF ILLUSTRATIONS. Whitworth Oun. FIG. 26. 7 -inch 120-pounder, as made by Mr. Whitworth. Elevation. 27. 7-inch gun as built at Woolwich, and rifled for Mr. Whitworth. Longitudinal section, -fa in. to 1 ft. 28. 7-inch gun as designed by Mr. Whitworth. Longitudinal section, -fa in. to 1 ft. 29. Breech of muzzle-loader. Longitudinal section. 30. Breech-loader. Elevation. 31. New 70-poimder. Elevation. 32. 70-pounder shot and rifling. Cross section, full size. Blakcly Gun. 32 A. 8-iVkich gun in the Great Exhibition of 1862. From a photograph. 32 B. 7 inch rifle, captured at Shipping Point, 1862. Long, section, -fa in. to 1 ft. 32 C. 9-inch rifle. Low-steel barrel, hooped by high-steel and cast-iron. Longi- tudinal section, -fa in. to 1 ft. 32 D. 8-inch steel 200-pounder. Longitudinal section, -ft in. to 1 ft. 33. 5 '8-inch steel rifle. Longitudinal section, fa in. to 1 ft. 34. 900-pounder (12|-in.) rifle sent to Charleston. Longitudinal section, -fa in. to 1 ft. 35. 11-inch rifle for Russia. Longitudinal section, -fa in. to 1 ft. 36. Rifling of 9-inch gun. Cross section, full size. 37. Machine for rolling hoops from solid cast-steel rings. 38. Experimental 18-pounder. Longitudinal section. 39. Experimental 9-pounder. Longitudinal section. 40. Dundas's experimental wrought-iron gun. Cross section. 41. 132-pounder of 1857. Longitudinal section, -ft- in. to 1 ft. Parrott Gun. 42. Coil as wound. Section. 43. 100-pounder (6'4-inch) rifle. Longitudinal section, -fa in. to 1 ft. 44. 10-inch rifle. Longitudinal section, -fa in. to 1 ft. 45. 8-inch rifle. Longitudinal section, -fa in. to 1 ft. Miscellaneous Hooped Gum. 46. Spanish steel-hooped gun. Longitudinal section, -ft- in. to 1 ft. 47. French steel-hooped gun (Carron. de 30). Longitudinal section, -ft in. to 1 ft. 48. Rifle-groove and stud of (Carron. de 30). Cross section, full size. 49. Armstrong hooped cast-iron naval gun. Longitudinal section, -ft- in. to 1 ft. 50. 68-pounder, hooped at Woolwich. Longitudinal section, -ft- in. to 1 ft. 50 A. Armstrong cast-iron 70-pounder of 1860. Longitudinal section, -ft in. to 1 ft. 51. Mr. Longridge's experimental brass cylinder. Longitudinal section. 52. Mr. Longridge's experimental wire-wound 3-pounder. Longitudinal section. 53. Mr. Longridge's experimental wire-wound cylinder. Longitudinal section. 54. Mr. Longridge's experimental wire-wound cylinder. Longitudinal section. 55. Mr. Longridge's experimental wire-wound 2-96-inch gun. Longitudinal section. 56. Brooke's 7-inch hooped gun, made for Confederate service at Richmond, Va. Longitudinal section, fa inch to 1 ft. 57. Brooke's 7-inch hooped gun, made for Confederate service at Richmond, Va. Breech-plan, -fa in. to 1 ft. LIST OF ILLUSTRATIONS. xxxvii FIG. 58. Brooke's 7-inch hooped gun. Rifling. Cross section. 59. Attick's bronze reinforce. Longitudinal section, -fa in. to 1 ft 60. The Bumford 12-inch cast-iron gun, hooped. Longitudinal section, -fa in. to I ft. 61. Mallet's 36-inch wrought-iron mortar. Elevation. Solid Wrought-Iron Guns. 62. " Horsfall" solid forged 13 -inch gun. Longitudinal section, -fa in. to 1 ft. 63. *' Horsfall" solid forged 13-inch gun. Elevation, -fa in. to 1 ft. 64. " Horsfall" solid forged 13-inch gun. Pile for forging. Cross section. 65. "Prince Alfred" hoDow-forged 10-inch gun. Elevation, -fa in. to 1 ft. 66. 12-inch gun in Brooklyn Navy Yard. Longitudinal section, -fa in. to 1 ft. 67. Lynall Thomas's 7 -inch gun. Mode of fabrication. Cross section. 68. Ames's 50-pounder. Longitudinal section, -fa in. to 1 ft. Solid Steel Gun*. 69. Krupp's 9-inch gun in the Exhibition of 1862. Longitudinal section, -fa in. to 1 ft. 70. Krupp's 9-inch gun in the Exhibition of 1862. Plan, -fa in. to 1 ft. 71. Krupp's 9-inch gun for Russia. Longitudinal section, -fa in. to 1 ft. 72. Krupp's 12-pounder after being hit by shot. Cross section. 73. Krupp's jacketed gun burst at Woolwich. Longitudinal section. 74. Krupp's jacketed gun burst at Woolwich, after fracture. Longitudinal section. 75. Bessemer steel gun. Longitudinal section, -, fi - in. to 1 ft Cast-Iron Guns. 76. British 8-inch (68-pounder) laid over United States 8-inch Columbiad. Half- longitudinal section of each, -fa in. to 1 ft. 77. U. S. Army 15-inch Columbiad. Longitudinal section, -fa in. to 1 ft. 78. TJ. S. Army and Navy 13-inch guns. Half-longitudinal section of each, -fa in. to 1 ft. 79. U. S. Army 10-inch Columbiad. Longitudinal section, -fa in. to 1 ft. 80. U. S. Army 4'2-inch rifled siege-gun. Longitudinal section, -fa in. to 1 ft. 81. U. S. Navy 15-inch gun. Longitudinal section, -fa in. to 1 ft. 82. U. S. Navy 11-inch Dahlgren gun. Longitudinal section, -fa in. to 1 ft. 83. U. S. Navy 7-|-inch Dahlgren rifle. Longitudinal section, -fa in. to 1 ft. 84. U. S. Navy 7^-inch Dahlgren rifle. Cross section, -fa in. to 1 ft. 85. Dahlgren's breech strap for 74-inch rifle. Plan, -fa in. to 1 ft. 86. Dahlgren's breech-strap for 7|-inch rifle. Elevation, -fa in. to 1 ft. 87. British 68-pounder (8-inch), 95 cwt. gun. Longitudinal section, -j%- in. to 1 ft. 88. British 8-inch shell-gun. Longitudinal section. -&- in. to 1 ft. 89. Russian 120-pounder. Elevation, -^ in. to 1 ft. 90. Russian 56-pounder. Longitudinal section, -j fi - in. to 1 ft. 91. British and U. S. 13-inch sea-service mortars. Half-longitudinal section of each, -fa in. to 1 ft. 92. British 13-inch mortar, burst at Sweaborg. Longitudinal section. xxxviii LIST OF ILLUSTRATIONS. Projectiles against Armor. FIG. 93. 10-inch target for 15-inch gun. Side elevation, -fa in. to 1 ft. 94. 10-inch target for 15-inch gun. Front elevation, -fa in. to 1 ft. 95. 10-inch target for 15-inch gun. Cross section, 4- in. to 1 ft. 96. 10-inch target as struck by 11-inch shot. Front elevation. 97. Ericsson 14-inch target. Cross section. 97 A. Confederate iron-clad Atlanta. Cross section. 98. The Warrior target. Side elevation, % in. to 1 ft. 99. Scott Russell's target. Front elevation, in. to 1 ft. 100. Scott Russell's target. Cross section, | in. to 1 ft. 101. Chalmers's target. Horizontal section. 101 A. The Bellerophon target. Cross section, { in. to 1 ft. 102. Hawkshaw's 10-inch laminated target. Cross section. 103. 6^-inch laminated target punched by Dahlgren 10-inch gun. Cross section, 104. Target, Fig. 103. Side and front elevations, -fa in. to 1 ft. 105. Shot-hole through laminated armor. Cross section. 106. Shot-hole through solid armor. Cross section. 107. Scott Russell's armor. Cross section. 108. The Warrior's armor. Cross section. 109. Wire-rope bolt for armor. Elevation. 110. Thames Iron Works plate after two G8-pounders. End elevation. 111. Thames Iron Works plate after two 68-pounders. Front elevation. 112. Thames Iron Works plate after two 68-pounders. Plan. 113. Thames Iron Works plate after two 68-pounders. Rear elevation. 114. 4-^-inch Dahlgren target "No. 5" after firing. From a photograph. 115. Nashua Iron Works target. Cross section. 116. Nashua Iron Works target after 6-inch shot. Front elevation. 117. Thames Iron Works "A 2" plate after test. Front elevation. 118. John Brown & Co.'s " Y good A 3" plate after test. Front elevation. 119. Warrior target. Side section, J 8 in. to 1 ft. 120. Whitworth's flat-fronted armor-punching shell. Elevation. 121. 122. Whitworth's flat-fronted armor-punching shell. Longitudinal sections. 122 A. 4-inch plate; wood backing and facing, after an 11-inch shot. From a photograph. 122 B. 4-inch plate; wood backing and facing, after an 11 -inch shot. Cross section. 1 22 C. The Warrior's side and armor at cross bulkhead. Horizontal section. 122 D. The Warrior's side and armor through ports. Horizontal section. 123. 9^-inch cannon chamber with 100-lb. ball and 35-lb. cartridge. Longitudinal section. 124. 7^-inch cannon chamber with 50-lb. ball and 34-lb. cartridge. Longitudinal section. 125. Fracture of spherical shot upon striking armor. 126. Flat-fronted Whit worth projectile. Elevation. 127. Stafford's sub-calibre shot. Longitudinal section. 128. Armor of the Galena (wooden vessel). Cross section, ^ size. Concerning the Strains and Structures of Oun. 129-135. Illustrations of the superior stretching and strain of the inner layers of cylinders subjected to internal elastic pressure. Cross section. LIST OF ILLUSTRATIONS. xxxix FIG. 136. Cylinder burst by internal pressure. Cross section. 137. Diagram illustrating the strain on a homogeneous gun. 138-142. Diagram illustrating strain due to want of continuity of hoops. 143. Wrought-iron cylinder after 20 heatings and coolings. Elevation. 144. Dahlgren breech-strap. Plan. 145. Dahlgren breech-strap. Elevation. 146. Breech-screw of Whitworth gun. Longitudinal section. 147. Armstrong hooped cast-iron naval gun. Longitudinal section, ->% in. to 1 ft. 148. Lancaster's strengthened 32-pounder. Longitudinal section, - t % in. to 1 ft. 149. Lancaster's hooping to give longitudinal strength. Longitudinal section. 150. Armstrong trunnion -hoop. Longitudinal section. 151. Gun burst under a seam in the hooping. Longitudinal section. 152. 68-pounder, hooped as proposed by Commander Scott. Longitudinal section. 153. 68-pounder, shrunk over wrought-iron tube, at Woolwich, 1860. Longitudinal section. 154. 68-pounder, strengthened by Parsons's internal tube. Longitudinal section, fa in. to 1 ft. 155. 68-pounder, strengthened by Captain Palliser's internal tube. Longitudinal section, -fg- in to 1 ft. 156. 68-pounder, strengthened by Captain Palliser's internal tube. Plan of muzzle, -fg- in. to 1 ft. 157. Captain Blakely's breech-loading gun with internal strengthening tube. Longi- tudinal section. 158. Captain Blakely's 9-inch high and low steel and cast-iron gun. Longitudinal section, -fa in. to 1 ft. Concerning the Materials and Fabrication of Guns. 159. Illustration of the effect of different rates of applying force. 160. Diagram illustrating the "work done" in stretching metals within and beyond their elastic limits. 161. Diagram illustrating the increase of weight by decreasing the strength of can- non metals. 162. "Wiard's cast-iron gun. Elevation. 163. Wiard's cast-iron gun. Longitudinal section 164. Wiard's cast-iron gun. Cross section. 165. Cast-iron gun distorted to show the effects of irregular cooling and bad shape. 166. Forging for Mallet's 36-inch mortar-chamber. Elevation. 167. Pile for Mallet's 36-inch mortar-chamber. Cross section. 168. 169. Rents from cooling, in forged masses. Cross section. 170. Rents from cooling, in Mallet's mortar-chamber. Longitudinal section. 171. The "Peacemaker" 12-inch wrought-iron gun. Longitudinal section, -^ in. to 1 ft. 172. The "Peacemaker," fragment after bursting, showing defects. Longitudinal section. 173. Sheet of iron rolled up to form a gun. Cross section. 174. Armstrong hoop. Elevation. 175. Armstrong coil. Elevation. 176. Armstrong 110-pounder. Longitudinal section, -,% in. to 1 ft. 177. Armstrong's lOA-inch gun (the first). Longitudinal section, -fo in. to 1 ft. xl LIST OF ILLUSTRATIONS. FIG. 178. Armstrong's 10-inch gun (the first), after bursting. From a photograph 179-181. Illustrations of the effect of shape of surfaces in welding. 182. Hitchcock's machinery for forging cannon. Longitudinal vertical section. 183. Armstrong coil. Elevation. 184. Krupp's method of making solid rings. 185. Bessemer converting vessel. Front elevation. 186. Bessemer converting apparatus. Plan. 187. Machine for rolling hoops. 188. Krupp's method of making solid rings. Rifling and Projectiles. 189. Cavalli rifled breech-loader. Longitudinal section. 190. Cavalli projectile. Elevation. 191. Wahrendorf's lead coating. Section. 192. Timmerhaus's expanding shot. Longitudinal section. 193. Beaulieu's, or first French service rifle-shot. Longitudinal section. 194. Early French rifling for ordnance. Cross section. 195. French rifling of I860. Cross section. 196. French projectile of 1860. Elevation. 197. French shell in British competitive trials of 1861. Longitudinal section. 198. French field-gun, mounted. From a photograph. 1 99. Present French groove and stud, Canon de 30. Cross section. Full size. 200. Austrian shell for 3-inch field-gun. Gun-cotton. Longitudinal section. 201. Austrian shell for 3-inch field-gun. Gun-cotton. Cross section. 202. Austrian fuze for shell. Elevation. 203. Austrian 3-inch field-gun and rifling. Cross section. 204. Russian studded shell. Elevation. 205. Russian studded shell. Cross section. 206. Russian rifle-groove. Cross section. 207. Spanish rifled gun. Cross section. 209. Spanish shell. Half-longitudinal section. 210. Lancaster's rifling. Cross section. 211. Lancaster's shell; competitive trials of 1861. Longitudinal section. 212. Hadrian's rifling. Cross section. 213. Hadrian's shell; competitive trials of 1861. Longitudinal section. 214. Hadrian's projectile for wood sabot. Longitudinal section. 215. Whitworth's rifling. Cross section. 216. "Whitworth's short round-fronted projectile. Elevation. 217. Whitworth's long round-fronted projectile. Elevation. 218. Whitworth's long flat-fronted projectile. Elevation. 219. Whitworth's 7 0-pounder shot and rifling. Cross section. Full size. 220. 221. Scott's rifling. Cross section. 222. Scott's rifling ; projectile leaving the gun. Cross section. Full size. 223. Scott's groove and rib on the projectile. Cross section. 224. Scott's shell; competitive trials of 1861. Longitudinal section. 225. Sawyer's projectile. End elevation. 226. Sawyer's projectile. Side elevation. 227. Pattison's projectile. Longitudinal section. 228. Pattison's projectile. Cross section. LIST OF ILLUSTRATIONS. xli FIG. 229. Early Prussian rifling. Cross section. 230. Ea-rly Prussian lead-coated shot. Half-longitudinal section. 231. Original Armstrong rifling. Cross section. 232. Adopted Armstrong rifling. Cross section. 233. Armstrong rifling of 1861. Cross section. 234. 235. Armstrong rifling, 6 and 12 pounder. Cross section, four times enlarged. 236. Armstrong 12-pounder chamber, projectile, and vent-piece. Longitudinal sec- tion, one-third size. 237. Armstrong undercut lead-coated projectile. Half-longitudinal section. 238. Armstrong segmental shell. Longitudinal section. 239. Armstrong segmental shell. Cross section. 240. Armstrong 14-lb. cartridge and Boxer's lubricator for 110-pounder. Longitudi- nal section. 241. Armstrong 14-lb. cartridge and Boxer's lubricator for 110-pounder. Elevation. 242. Armstrong 12-lb. cartridge and Boxer's lubricator for 110-pounder. Longitudi- nal section. 243. Armstrong shunt projectile with rib to hold zinc strip. Elevation. 244. Armstrong shunt projectile going in. Cross section at muzzle. 245. Armstrong shunt projectile coming out. Cross section at muzzle. 246. Armstrong shunt rifling development of groove. Plan. 247. Armstrong shunt shell competitive trials of 1861. Longitudinal section. 247 A. Armstrong shunt rifled mortar. From a photograph. 248. Eussian shunt rifling. Cross section at muzzle. 249. Russian shunt rifling. Cross section at 36 in. from muzzle. 250. Russian shunt rifling. Cross section at 92 in. from muzzle. 251. Russian shunt rifling. Cross section at 124 in. from muzzle. 252. 253. Russian shunt steel shells. Elevations. 254. Rifling of 4-2-inch U. S. siege-gun. Cross section. Full size. 255. James's projectile. Perspective. 256. James's projectile without packing. Perspective. 257. James's shell. Longitudinal section. 258. James's new shell. Longitudinal section. 259. Hotchkiss's shell. Longitudinal section. 260. Lynall Thomas's early projectile; competitive trials of 1861. Longitudinal section. 261. Schenkl projectile without sabot. Perspective. 262. Schenkl projectile with papier mache sabot. Perspective. 263. Reed's shell. Longitudinal section. 264. Blakely's projectile. Longitudinal section. 265. Blakely's rifling for 9-inch gun. Cross section. Full size. 266. Brooke's rifling for 7-inch gun. Cross section. 267. Blakely's rifle-groove for 12|-inch gun at Charleston. Cross section. Full size. 268. Parrott's hollow shot. Elevation. 269. Parrott's 100-pounder shell. Elevation. 270. 271. Targets showing accuracy of Parrott 100-pounder shell at 200 yards. Elevation. 272. Stafford's new projectile, rear. Longitudinal section. 273. Buckle's new projectile, rear. Longitudinal section. 274. Jeffery's shell; competitive trials of 1861. Longitudinal section. 275. Jeffery's rifling. Cross section. xlii LIST OF ILLUSTRATIONS. FIG. 276. Britten's rifling. Cross section. 277. Britten's shell; competitive trials of 1861. Longitudinal section. 278. Rifling used with Britten's and other expanding projectiles. Cross section. 279. Britten's early projectile. Cross section. 280. Whitworth's flat-fronted armor-punching projectile. Elevation. 281. 282. Whitworth's flat-fronted armor-punching projectile. Longitudinal section. 283. Whitworth's round-fronted projectile. Elevation. 284. Scott's steel shell for armor-punching. Longitudinal section. 285. Parrott's chilled flat-headed cast-iron shot for armor-punching. Elevation. 286. Stafford's sub-calibre shot for armor-punching. Longitudinal section. 287. Stafford's sub-calibre shell for armor-punching. Longitudinal section. 287 A. to 287 E. Bates and Macy's sub-calibre ordnance and projectiles. 288. Lancaster's loam-lined shell for molten metal. Longitudinal section. 289. Scott's loam-lined shell for molten metal. Longitudinal section. 290-294. Diagrams explaining the causes of the deviation of projectiles and the effects of rifling. 295-304. Diagrams of projectiles with reference to their resistance by the atmosphere. 305. " illustrating the shape of projectiles. Cone. 306. " " " " Conoid. 307. " " " " Ogival. 308. " " " " Newton's form. 309. " " " " Piobert's form. 310. Atwater's rifling near the chamber. Cross section. 311. " near the muzzle. Cross section. 312-314. Diagrams illustrating the strain due to rifling, in different grooves. EXPERIMENTAL BORES AND PLUGS TO TEST THE STRAIN OP RIFLING. 315. Lancaster. Cross section. 316. Decagon. Cross section. 317. 3 grooves. Shunt. Cross section. 318. 3 grooves. Scott. Cross section. 319. Whitworth. Cross section. 320. 3 grooves. Scott. Cross section. 321. 2 grooves. Experimental. Cross section. 322. 3 ribs. L. Thomas. Cross section. 323. 3 grooves. Scott. Cross section. 324. 10 grooves. Shunt. Cross section. 325. Three rounded grooves. Cross section. 326. Square groove and rib. Cross section. % 327. Scott's groove and rib. Cross section. 328-335. Diagrams showing the amount of the original bore untouched by different systems of rifling. 336, 337. Bessemer's elongated projectile for smooth bores. Elevation. Breech-Loading. 337 A. French iron-clad two-decker, Solferino. From a photograph. 338. Stevens's steam loading and cooling apparatus. Longitudinal section. 339. Stevens's gun-carriage on the Naugatuck. Elevation. 339 A. Stevens's steam gunboat Naugatuck. Longitudinal section. LIST OF ILLUSTRATIONS. xliii FIG. 339 B. Stevens's steam guuboat Naugatuck. Cross section. 339 C. Hyde's method of running in guns. Plan. 339 D. Brown's method of running in guns. Plan. 340. Breech of Armstrong 110-pounder. Longitudinal section. 341. " " " Plan. 342. " Cross-section behind vent-piece. 343. " " " Rear elevation. 344. Armstrong 11 0-pounder. Longitudinal section. 345. Breech of Armstrong 40-pounder. From a photograph. 346. Armstrong 2 0-pounder gun mounted, and limber. From a photograph. 346 A. Armstrong 11 0-pounder on barbette carriage. Elevation. 347. Alger's breech-loader. Horizontal section through breech. 348. Krupp's breech-loader. Horizontal section through breech. 349. Krupp's gas-check. Horizontal section. 350. Krupp's breech-loader. Breech-wedge in. From a photograph. 351. Krupp's breech-loader. Breech-wedge out. From a photograph. 352. Krupp's breech-loader wedge or sliding-block. From a photograph. 353. Broadwell's breech-loader. Horizontal section through breech. 354. Storm's breech-loader. Longitudinal vertical section through breech. 355. Storm's breech-loader. Plan of breech. 356. Castmann's breech-loader. Elevation. 357. Castmann's breech-loader, with plug out. Perspective. 358. Blakely's breech-loader, with inner strengthening tube. Longitudinal section. 359. "Whitworth's breech-loader. Elevation. 360. Screw breech-loader. Rear elevation. 361. Screw breech-loader. Longitudinal section. 362. Clay's breech-loader. Longitudinal section. 363. Cavalli breech-loader. Longitudinal section. 364. Cavalli breech-loader. Plan of breech. 365. Cavalli breech-loader. Wedge. Horizontal section. 366. Cavalli breech-loader. "Wedge. Elevation. 367. "Wai irendorf breech-loader. Breech. Horizontal section. 368. "Wahrendorf breech-loader. Longitudinal vertical section. 369. Prussian breech-loader. Horizontal section. 370. Prussian breech-loader of 1861. Wedge out. Horizontal section. 371. Prussian breech-loader of 1861. Wedge in. Horizontal section. 372. Adams's loading and cooling from the breech. Experiment* againt Armor. 373. The floating battery Trusty. From a photograph. 374. Jones's inclined target. Elevation. 375. Thorneycroft 8-in. target. Front elevation. 376. Thorneycroft 8-in. target. End elevation. 377. Thorneycroft 8-in. target. Bar. Cross section. 378. The Warrior. Side at ports. Horizontal section. 379. The Warrior. Armor. Cross section. 380. Hawkshaw's 10-inch target. Cross section. 381. Scott Russell's target. Elevation. in. to 1 ft. 382. Scott Russell's target. Cross section. in. to 1 ft. xliv LIST OF ILLUSTRATIONS. FIG. 383. Scott Russell's armor. Cross section. 384. Warrior target. Cross section. | in. to 1 ft 385. Hodge's wire target before firing. Cross section. 386. Hodge's wire target after two 11-in. shot. Elevation. 387. 388. Laminated inclined target, backed by rubber and timber. 389. Solid 8-in. target after a 10-in. Parrott shot. Elevation. 390. Solid 8-inch target, after a 10-in. Parrott shot. Cross section. 391. 392. Target of bars before and after firing. Elevation and section. 393. Confederate iron-clad Atlanta. Cross section. 394, 395, 397. Ten-inch target, Washington Navy Yard. Elevation. 396. Ten-inch target, "Washington Navy Yard. Cross section. 398. Fourteen-inch target, Washington Navy Yard. Cross section. 399. Laminated 6^-inch target, after 10-inch ball. Cross section. 400. Dahlgren 4^-inch target, No. 5, after firing 11-in. shot, etc. Elevation. 401. Nashua Iron Works target after firing. Elevations. 402. Solid 4-inch plate, faced with 4 inches of rubber, and backed. Elevation. 403. Chalmers target. Cross section. 404. 405. Solid 4^ -inch plate, faced with 12-inch oak, and backed with 20-inch oak. Elevation. 406. Warrior target, fired against at St. Petersburg. Elevation. 407. Bellerophon target. Cross section. 408. Bellerophon target. Frame of ship. Cross section. 409. The Belkrophon. Elevation, Gun-Colton. 410. Palisade, 12 and 8-inch, cut down by 25 Ibs. of gun-cotton. Elevation. 411. 412. Bridge, 12-inch scantling, 24 feet span, cut down by 25 Ibs. of gun-cotton, before and after firing. Elevation and plan. 413. Ship and 400-lb. gun-cotton torpedo. Elevation. 414, 415. Bridge destroyed by gun-cotton, showing local effect. Plan and elevation. 416, 417. Gun-cotton cartridge. Elevation and cross section. 418. Gun turned down to measure the pressure of gun-cotton. Elevation. 419. Austrian rifled field-gun for gun-cotton. Cross section. 420. Austrian rifled projectile for gun-cotton. Cross section. 421. 422. Rifle-musket cartridge. Gun-cotton. Cross section and elevation. 423. Palisade opened by 25 Ibs. of gun-cotton. From a photograph. 424. Palisade opened by 25 Ibs. of gun-cotton. Before firing. From a photograph. 425. Palisade opened by 25 Ibs. of gun-cotton. After firing. From a photograph. Miscellaneous 426. Thiery's hooped gun, 1834. Elevation. 427. Chambers hooped gun, patented 1849. Longitudinal section. 428. Treadwell's hooped gun, patented 1855. Longitudinal section. 429. Blakely's hooped gun, patented 1855. Longitudinal section. 430. Parrott's hooped gun, patented 1861. Longitudinal section. 431-450. Diagrams illustrating Mr. Wiard's theory of the bursting of guns by the heat of firing. 451. Lyman's accelerating gun. Longitudinal section. PART I. ORDNANCE PART FIRST. CHAPTER I. STANDARD GUNS AND THEIR FABRICATION DESCRIBED SECTION I. HOOPED GUNS. 1. I. The Armstrong Gun. This celebrated Artillery has been fabricated only for the British Government,* at the Royal Gun Factory, Woolwich, under the superintendence of Mr. John Anderson, and at the Elswick Works, Newcastle-upon-Tyne, under the superintendence of Sir William G. Armstrong. f 2. After the production of nearly 3000 guns, the manufacture of what may be strictly called the Armstrong Gun is at present entirely discontinued, partly because the Army is well supplied with them, and partly because the larger sizes have not, consider- ing their cost, successfully endured the vibration and pressure due to heavy charges.^: Their comparative liability to injury, * By special act of Parliament, Sir William Armstrong's patents have never been made public. These patents are now the property of the British Government. The history of the invention is more fully referred to in the Appendix. f Previous to his resignation, February 5th, 1863, Sir" William Armstrong was Superintendent of the Royal Gun Factory, and also the Government "Engineer for- Rifled Ordnance." Mr. Anderson was then "Inspector of Machinery" at Wool- wich. Report of Select Committee on Ordnance, 1862. % It should not be argued from this fact, that the Armstrong guns on hand do not constitute a formidable armament. When the manufacture was started, the Britisli Government was without a rifled cannon, and had nothing more powerful as a naval gun, or as a gun of position, than the 68-pounder, while Continental Powers- were well supplied with rifled artillery. To remedy this alarming defect,, the Government 1 2 ORDNANCE. from dampness and rough usage, is a further objection urged against the breech-loaders especially, as ^Naval guns.* 3. While some of the distinctive features of the Armstrong O gun are retained in the heavy ordnance at present construct- ing (41), the principal improvements, indicated both by practice and experiment, are the use of a larger amount of steel and of a smaller number of parts. 4. Ample appropriations, and over eight years' experience in the selection of iron and the improvement of processes and tools, have contributed to bring the manufacture of the Armstrong gun to a degree of perfection hardly surpassed in any other branch of machine building. Any immediately remediable de- fects in the gun would therefore appear to be due to the mate- rials or to the design, and not to the workmanship. The defects and improvements referred to will be considered more at length, and in order, in following sections (432). 5. The Armstrong gun is a series of concentric wrought- ironf tubes made from spiral coils. All the service Armstrong guns are rifled with fine grooves, to carry lead-coated projectiles. Some 9-22 in. and 10'5 in. experimental guns are smooth bores. The service guns up to 7 in. bore are breech-loaders ; the muzzle- loaders, generally of larger bore, are as yet experimental guns, excepting, perhaps, the-10'5 in. gun. G. The specification to the makers of the iron prescribes " a tenacity (ultimate) of about 2G tons (582-10 Ibs.) per square inch, not over 27 tons (60480 Ibs.), nor under 25 tons (56000 Ibs.) ; elongation not to become permanent under 13 tons (29120 Ibs.) felt obliged to resort to great and perhaps unnecessary haste and expense. In the present time of better preparation and greater security, the Government is experi- menting, at no inconsiderable cost, with reference to future improvements. * The recent bombardment of Kagosima is said to have demonstrated the weak- ness of the Armstrong gun in this particular. . j- The original Armstrong gun a 3-pounder, delivered in July, 1855 was a breech-loader, having an inner barrel of steel throughout its length. This was hooped with one thickness of coils from the muzzle to the trunnion-ring, and with three coils over the chamber, giving it a maximum diameter there of 9 in. The bore was If in. These facts are obtained from the Report of the Select Committee on Ordnance, 13G3. HOOPED GUNS. 3 tension per square inch, nor compression to become permanent under 14 to 15 tons (31360 to 33600 Ibs.) pressure on like sur- faces."* The greater part of the iron, especially that for the inner tubes, is supplied by Messrs. Taylor Brothers, of Leeds, at the cost in the bar, delivered at Woolwich, of 20 per ton,f and is a mixture of about 85 per cent, of Yorkshire, and about 15 per cent, of cold- blast, Swedish, charcoal pig.* :f Mr. Anderson states that this is the best of seven or eight sorts of iron tried, and that it is quite uniform, and " does not blister at all."f The forgings are sup- plied by Messrs. Taylor, Messrs. Cammell of Sheffield, and the Low-Moor Iron Company.f 7. FABRICATION. All parts of the gun proper, except the breech-piece and the trunnion-ring, are formed from bars about 3 by 5 in., made in 30-feet lengths, welded end to end so as to be, say, 120 feet long, and of the section shown at Fig. 1. The upper or narrower side of the bar is placed next a revolving mandrel of the inner diameter of the intended tube, so that when the bar is wound round the mandrel, the upsetting of its thinner side, and the drawing of the other, will change its section to rectangular. The bar is drawn hot upon the man- drel, and coiled around it into a close spiral of any required diameter (Fig. 2). The spiral is heated in a reverberatory furnace, placed upon end under a broad- faced six-ton steam-hammer,;]: and " up- set" into a hoop (which, for convenience of handling, and to prevent excessive bulging, is limited in length to three to four feet for the small rings, and four to five feet for FIG. 1. Section of bar for coil. FIG. 2. Bar coiled to make a hoop * " Practical Mechanics' Journal. Record of the Great Exhibition, 1862." f Evidence of Mr. Anderson. Report of Select Committee on Ordnance, 1862. j Mr. Anderson states that the Elswick hammer weighs ten tons, and that the new hammer at "Woolwich weighs twelve tons. Report of Select Committee on Ord- nance, 1862. ORDNANCE. the large ones), the sides of the adjacent coils thus being welded together.* The hoop is also "patted" on its periphery by a steam-hammer, to smooth down any large bulges, and to preserve its cylindrical form. 8. It is then recessed in a lathe about half an inch on each end (Fig. 3), so that one hoop will tit into the end of another. FIG. 3. FIG. 4. Hoop recessed to lit others. Furnace for welding hoops into a tube. FIG. Section of weld. Two hoops are thus set end to end, squeezed together by a heavy bolt passing through them, and placed in a narrow reverberatory furnace (Fig. 4), where the joint receives a weld- ing heat. The nut on the bolt being then tightened by the power of say ten men, applied to a wrench ten or twelve feet long, the joint is upset (Fig. 5) longitudi- nally (460). The hoops are then slipped over a loose mandrel, and patted under a steam-hammer, to perfect the weld and the shape of the short tube thus formed. f Another hoop is then slipped over the man- drel, and added to the tube by the same process, and so on until the required length is reached. Except for the 110- pounder, only the hoops forming the inner tube are welded together in this manner ; and in all the guns, the outer courses of hoops are not welded end to end. In the Armstrong gun of 1859 (Fig. 8), the second tube from the bore was formed of two slabs, semi-cylindrical in section, welded together lengthways.^ * The same process has been very successfully applied in France for the manu- facture of locomotive tyres. Mr. Longridge, " Construction of Artillery," Inst. Civil Engineers, 1860. f During this process, much iron is oxydized, as the scale is jarred off as fast as it forms, exposing fresh surfaces. \ Capt. Blakely. Journal Royal United Service Inst., March, 1861. HOOPED GUNS. FIG. 6. PIG. 7. O. Inasmuch as the fibre of the iron runs spirally around the gun, and the welds are perpendicular to the bore, the structure is thus far very strong radi- ally, but extremely weak longitudin- ally. To prevent the breech from being blown off by the explosion of the powder, the breech-piece (in which the breech- FlG. 8. Armstrong 110-pounder. -j d o in. to 1 ft. Armstrong 12-pounder. -, 6 -in. to 1ft. Armstrong Field-gun of 1859. 6 ORDNANCE. screw turns, C D, Fig. 17) is forged solid and bored out, so that its fibre is parallel with the bore; it is also made thicker than the other tubes. It is welded to the second tube from the inside, in the same manner that the rings are welded into a tube. The breech-piece was formerly made of a slab bent into a cylindrical form, and welded at the edges.* The breech-piece of the new 70-pounder, and of other small guns, is not welded to the adjacent tube-end, but retains its position solely by the friction of the tubes around it. Since the breech of the 10| in. gun pulled apart in its thickest section without fracturing its welded joint with the tube which formed a continuation of it, the longitudinal strength of the piece, due to the grip of the rings upon each other, would appear to be sufficient, so long as that grip is not impaired. (See 300, 304, and Figure 23.) Indeed, the whole rear of the gun has been, in some cases, prevented from blowing out in other words, the pressure of the powder gas upon the bottom of the chamber has been transferred to the trunnions by the friction of the tubes upon each other. 10. Generally, however, the trunnion-ring (which is welded up and shrunk on in the usual way) is slightly recessed (Fig. 25) to fit a corresponding projection on the ring beneath it, and is slipped on when sufficiently expanded by heat. The outer rear ring is also flanged over the breech-piece (Fig. 6). 11. The outer tubes and rings thus formed are turned and bored without taper ; the inner tube, for the recent class of guns, is slightly largest at the breech end, so that it may not be slipped forward by the enormous friction of the Armstrong projectile. The tubes and rings are shrunk together in the following man- ner : A tube, turned accurately without, is set on end ; a larger tube, turned smoothly within and roughly without, is heated to redness by standing on end over a wood fire, of which it forms the chimney. This larger tube is then raised by a travelling crane, placed above the other, and then slipped home. Water * Construction of Artillery. List Civil Engineers, 1860. HOOPED GUNS. FIGS. 9 & 10. jets are then turned on to shrink the outer tube. The mass is then accurately turned without, to receive other tubes and rings in like manner. Short tubes and rings are heated in a reverberatory furnace. FIG. 11. FIG. 12. Top, side, and end of early Armstrong 1 2-pounder. 8 ORDNANCE. 12. Sir William Armstrong has stated that he did not at- tach much importance to giving the tubes and rings successively higher initial tension, but that " they were simply applied with a sufficient difference of diameter to secure effective shrinkage,"" and that a little variation in accuracy of shrinkage does not in- volve very bad results. f This principle of construction will be discussed in a following chapter. 13. BREECH-LOADING. Two forms of loading at the breech J are employed the screw, and the wedge or side breech-loader. The screw, which is used in all the service guns, is generally illustrated by Figs. 9 to 11, and 17 to 21. The rear of the powder- chamber is closed by a movable stopper called the vent-piece, which is held in place by the hollow breech-screw behind it. .When the vent-piece is lifted up, the hollow screw forms a con- tinuation of the bore, through which the charge is inserted from the rear. The breech-screws for the smaller guns are < loader has also been the subject of trial. The particulars of this gun are as follow : ' Weight 18648 Ibs. Calibre 8-5 in. :i|p Length 126-5 " Length from breech to trunnions 49 5 " YJjjm Diameter of bullet-chimbcr 8-52 II IP ::\ v o $ Rifling, eight grooves ; one turn in 55 diameters, or 467*5 in. : solid cast- \ | iron shot, with false conical head, weight 130 Ibs. : extreme length, 15*2 in. : charge, 28 Ibs. : cartridge, 18 in. long: common shell, 173 Ibs.: bursting charge, 12-8 Ibs., or 185*8 Ibs. total : charge, 24 Ibs. 26. A 200-pounder (9*22 in.) gun has been constructed by placing a steel tube in a gun of the exterior dimensions of the 300-pounder (29). 27. A 9 in. muzzle-loading shunt gun, rifled with six grooves, has been completed, but not tested. This is the 100-pounder smooth-bore gun Armstrong 10-J- in. gun. T 7 * in. to 1 ft. HOOPED GUNS. 17 38. A 9fin. 20-ton gun, with a steel barrel, is completed, but not tested. FIG. 23. The first 10|in. gun after bursting. (From a photograph.) 29. The 300-pounder muzzle-loading shunt gun is the 10^ in. gun (Fig. 22), rifled with ten shunt grooves, so as to throw zinc- ribbed elongated shot. Besides the first smooth bore gun (Figs. 22 and 23), which burst after 264 rounds, fourteen others were constructed. Two of these only were rifled. Their particulars are as follow: (32 See also Fig. 25). Weight of gun 26880 Ibs. Preponderance 1142-4 " Length over cascabel 156 in. Length from trunnions to \ tt muzzle. Diameter of bore. 10-5 Length of bore I2 5* Diameter of trunnions 12- Between trunnions 36- Diameter over chamber 38- Thickness of metal at muzzle.. 4-5 Thickness of metal at breech.. 13-75 Ten grooves, one turn in 65 diameters, or 682'5 in. The shot (flat-headed, with false conical head) has ten bearing and ten driving ribs, and ten studs at the base ; is 18*7 in. long, and weighs 230 Ibs. The common shell weighs 278-6 Ibs., and holds a 21*75 Ibs. bursting charge 300-35 Ibs. total. The steel solid shot, 300 Ibs., is 13-56 in. long. The service charge intended was 45 Ibs. (20 in. long), but has been reduced to 35 Ibs. 2 18 ORDNANCE. 3O. The 600-pounder* muzzle-loader (Fig. 24), is a gun con- structed similarly to the 300-pounder, of the following dimen- sions : Weight of gun 51296^5. Weight of breech-piece (for- ging) 19040 " Preponderance 952 " Weight of charge 70 " Weight of fhell 601 " Burfting charge of common fhell 45t47 " Burfting charge (fteel fhell) 24 " Burfting charge (fegmental fhell, 510 fegments) 15 " Length of fhell 3' a 5 m - Length of charge 23 " Number of grooves 10 Depth of grooves (muzzle) 08 in. Twift of rifling (turn in cali- bres) i in 65 " Length over all Length behind centre of trunnions Length of bore 12" Diameter of bore Diameter over breech Diam. over trunnion-hoop Diameter of muzzle Width over trunnions Thicknefs of trunnion-hoop Width of trunnion hoop... Length of breech-piece Diameter of breech-piece... Spctional area breech-piece Sectional area of coils alfo "v receiving longitudinal > ftrain .. ... J 6 2-5 < 12" 1-25 13-3 4" 3*5 4 " 5*5 i " 9-5 6 " 2-5 6 1 6-5 6 8-25 2 " 6-3 458 fq. . 125 " The bore extends throughout the length of the gun, and is closed at the breech by a wrought-iron plug fitted into the bore, behind which there is a wrought-iron plug, faced with a steel disc, and screwed into the breech-piece. The trunnion-ring is shrunk on the 6th course of cylinders. The outer coil was made from a bar 5x4 in. and 125 feet long, weighing 71 cwt. The gun was turned after adding the respective cylinders, up to the 5th course ; the 3 other cylinders, having been turned to proper sizes before- hand, were put on without removing the gun from the contract- ing pit. Its cost was $19000. The brass studs on the shot are of "85 in. diameter flattened to *65 in. and are stamped into holes undercut in the projectile, and placed in 10 rows, 5 or 6 in a row. 31. The above-mentioned guns are all rifles. Several muz- zle-loading Armstrong smooth-bores, of 9 -22 in. bore, to carry a 100 Ib. spherical shot, were made with 106 in. length of bore, and 12544 Ibs. weight.f A new lot, of 10 ft. length and 13514 Ibs. * This gun was fired sixteen rounds for range (see chapter on " Rifling and Projec- tiles") on November 19, 1863. f Journal of Royal U. Service Inst., 1862. HOOPED GUNS. 19 20 ORDNANCE. FIG. 25. / op J gun. Arsenal construction. weight, has been constructed. The range and test of one of them is given farther on. It is stated that fifty more of these guns, to weigh 118 cwt., and to have inner steel tubes, have been ordered. 3. The 150-pounder, smooth-bore (Fig. 22) is the " 300-pounder " without rifling. Of the fifteen guns of this size constructed, only two were rifled (29). Two of the four constructed at Woolwich had internal tubes with closed ends, and were not rifled. The difference between the Arsenal and Elswick plans, for constructing these guns will be un- derstood by comparing Figs. 25 and 22. In the former, the closed inner tube is a complete gun in itself; in the hitter, the breech-plug, which is disconnected from the inner tube, forms the bottom of the barrel. The steel spherical shot for these guns weighs 167 Ibs. ; diameter, 1O435 in. ; charge, 50 Ibs. ; car- tridge, 22 in. long. The cast-iron shot weighs 152 Ibs., and is 10435 in. diameter. The cast-iron shell weighs 114*3 Ibs. ; bursting charge, 5'25 Ibs. ; thickness of wall of shell, 1'T in. ; charge, 30 Ibs. 33. Several guns, constructed upon the Armstrong plan in most particulars, but modified chiefly in' the rifling, have been fabricated at Woolwich. One of them, the Whitworth 120-pounder (44), which threw shells through the Warrior target, weighs 16660 Ibs., and is rifled on Mr. Whitworth's plan, the bore being 7 in. across the corners, and 6*4 across the flats. 34. A 9-in. gun of 35840 Ibs. weight, with a solid wrought-iron inner tube, closed at HOOPED GUNS. 21 the end, was rifled on Mr. Lynall Thomas's plan, with three projections to fit corresponding grooves in the shot. This gun has fired bolts as heavy as 330 Ibs. weight, with 50 Ibs. of powder, at armor plates. 3o. STEEL TUBES HARDENED IN OIL. The substitution of a solid-forged steel barrel for the Armstrong coiled tube* has often been attempted by Mr. Anderson, although he did not succeed well with steel, until the process of hardening in oil was adopted. The apparatus for this process is very simple. An iron tank, filled with oil, and made deep enough to take in the tube verti- cally, is set within a tank of water, to keep the oil cool. Within the orbit of the crane for lifting the tube is a heating furnace with a wood fire. The temperature of the oil is raised to 280 by a 110-pounder inner tube. The effects of hardening in tfil will be farther considered under the head of steel. 36. One 110-pounder, and two or three guns to be used for testing vent-pieces, have been constructed on this principle; and four 7 in. guns, thus fabricated, and rifled respectively on Scott's, Lancaster's, Britten's, and the French system, are nearly ready for trial. f 37. COST. The process by which the Armstrong gun is con- structed involves so much labor and such an extensive plant, that, however closely managed, it must be very costly. In addition to this, the manufacture has been carried on in a government establishment (which, as a rule, is not an eco- nomical system of production), and in a private establishment guaranteed against loss by the Government. In fact, the Report of the Select Committee of 1863 indicates that $1200000 might have been saved on an expenditure of about $3000000, had all the ordnance required for the navy been supplied from Wool- wich instead of Elswick. * The inner tube of the earliest successful gun (18-pounder) was made of steel (Sir "Wm. Armstrong, "Construction of Artillery," Inst. Civil Engineers, 1860), but the particular kind used was perhaps too brittle for the purpose. f It is stated that the fifty muzzle-loading guns of 9-inch bore, weight 118 cwt., ordered in the autumn of 1863, are to have inner tubes hardened in oil. They will fire a 100 Ib. round ball. ORDNANCE. TABLE IV. RETURN showing the amount of money expended on PLANT at Woolwich, for the manufacture of ARMSTRONG GUNS, and for other purposes, from the com- mencement of the manufacture, in March, 1859, to the 31st March, 1862, from the Report of the Select Committee on Ordnance, 1862. Date. Buildings. Machinery. Total. Remarks. 1 8 Co 60 6. d. 1 1 342 . d. 68 c c ^ 7 7 A d. 7080? 7 7 The whole of this iS6o-C: IQ7O .. 664?-: c 8 6842-2 c 8 plant has been used in 1861-62. lOOAI I 2 22781 I 2 the manufacture of Armstrong Guns. Total 16152 SC c N > CO o ^-o I "Is I t~ X 14 C 11 f r) 551 ' KJ 00 rn TJ h r M H : : ft 1) ^J | J^ M * " J r v < I Si f 1 5 ^* *-* S. -o ii u rt tj s 'g. 8 e | I "Tr " s" l coils and tubes (contract pr and breech-screws (contract h wr> (contract nrirp^ ^ I C S 1 2. -a -1 g * ^ c w I fi ^ J T3 4) c "9 "fl 1 -8 -S = s 'S 0, C co O CL, Q u CU U U rt D X5 O fl 5 c 5 3 = n^ "O CU co ^ ^j iT ') J H -g || J> u 6 S 7 s g > g, | | expenses, including indirect rs, miscellaneous labor, offic veiling, poftage, telegrams irs, gas, water, police, hors er cent.... s g z 111 III | '] c/ 1 .- -^ " c S > .S .S c "S **-. j .2 i " ^ "o -2 .2 .2 " 'I 1 ^ c - tS 22 2 ^^S S. a H _G ^ S 2 11 s i ; g > - l g" "i s ^ I i S i s Q [Signed] (?Mn Factories, March, 1862. J. ANDERSON, Assistant Superintendent, R. G. 'F. HOOPED GUNS. 25 TABLE VI. RETURN showing the PRICES of the ARMSTRONG- GUNS manufactured by the ELSWICK ORDNANCE COMPANY^ from the commencement of the manufacture up to the 31st March, 1862. (From the Report of the Sekct Committee on Ordnance, 1862.) Nature of Gun. Original price. Subsequent prices. Remarks. 12-pounder... 20 do 40 do loo do $ 850 (170) 1 1 00 (220) 175 (35) ?coo (700] $ $ Complete with two vent- pieces and fights. ! Complete with two vent- pieces, but without fights. 1640 (328) 72CO (6to) 1425 (285) as Sir William Armstrong puts it,* "burst explosively." This feature, obviously due to the ductility of the metal, and the num- ber of the concentric tubes, is of great importance, especially in the case of turret or casemate guns. 41. The New British Gun. Early in 1863, the fabrication of Armstrong service guns was entirely suspended both at Wool- wich and at Elswick. The small amount of work done at the Royal Gun Factories was upon repairs and experimental guns. Towards the close of the year, the results of experimental steel tubes hardened in oil had been so favorable, that fifty 7-ton muzzle loaders of 9-in.f bore, and fifty 7-ton 9 cwt. T-in. guns, resem- bling Fig. 27 in exterior size and form, were ordered. The Arm- strong coiled outer hoops and rings and the forged breech-piece- are to be retained; but the coiled, welded, soft wrought-iron. inner barrel, with an open breech end, is replaced by a solid! homogeneous forging of steel, forming a complete gun in itself. The rifling of these guns had not been determined upon. " The safety of the principle I consider has been established by the fact that out of nearly 3000 guns made on this principle, no one gun has burst explosively, and, in fact, no one gun has failed, under the most trying tests, excepting by a grad- ual process, which has given timely notice of the approaching destruction of the gun, and has prevented any possibility of a dangerous accident." Evidence of Sir William Armstrong: Report of Sekct Committee on Ordnance, 1863. t The original 100-pounder muzzle-loader had 9-22 in. bore, and weighed 6 tons. 26 ORDNANCE. *J |i aS OO OO Tj- O ON r-- t-~ g Cl NO 11 10 CO ON C CO OO !* t^ t*^ CO CO ^ O M O co ON ON rl ^- Tj- ON co co u-> M Ig fj 5 ^ co ^ *$- O ON to co O co O l-^ ON OO rj- <*} 000000 VOt^W M Depreciation on Buildinirs and Machinery, and Interest on Capital. ^5 cow; w r^oooo g r^ .^vo^ONU^r^ H i " *-wkt ^^ T 7 i^ 00 tx Cost per Gun. O O t"^. ^o M co ^O t-i oo co O co oo ; ^- ^ O co ^- O to Cf| t^ t^ NO ^O l^> 1-1 ON IH M CO Total Cost of Guns. B '>* MONtO ^ t^toON OOOON H IH O ^- ON vn co ON M 'i-MCO woort co oo ON ij- oo H t^ ""w^ * 2^^^. i^ 1 - Uvo < ~ i J^ 1 ^ 2 s S S 2 t^ ^*- ON |j COQty, U CN cocooo C-ON^W Q-co W) CO O CO CO j 4* -* HI ^ : i : ^ 2 M 2" r^ O c* to oo ON oo Cost of Labor. ^ COONON ONtor^ N w> T$- w w VO VO OO oo cl O ON t^ OO O 1-1 v/i M O "i t- "- 1 e^ OOc< oooot-^ ^J- H co oo ^^ t^ t^ to 111 M a 3 O : I : : : 5 1 U 1 U lit) o -a -o O 1-1 "O & 'E S S oo 3-0-0 oo 3'0-aoooo 3 MO w O M -M 6 DM & &H vo c? O ON c3 O O 6J ^ ^ |! w -^: S 5 3 ^ & c2 HOOPED GUNS. 27 The principal features of the Armstrong system of ordnance would thus appeaf to be going out of use. The hooping of a steel barrel with wrought iron was patented by Captain Blakely, before Sir "William Armstrong's practice commenced. (See Appendix.) And since wrought iron, even when placed over a steel barrel, has shown some tendency to fail, on account of its greater duc- tility and softness, while the effects of vibration are much more serious upon separate layers of metal than upon solid masses, the opinion is gaining ground in England that coiled wrought-iron tubes will be entirely abandoned, and that a smaller number of solid steel tubes will be employed. The recent and most satis- factory development of the steel manufacture in Sheffield (see chapter on Cannon Metals), and the excellent endurance of the steel guns lately tested at Woolwich, also favor this conclusion. 4S. II. The Wliitworth ro o 1 o S =2 S- I I of a !? I O "" d pj fl *" "~ O) 5 a 5 '"> ^ " ^H O cfi ,O ^ 'o o t- a 5 ^ I ~ O d ^-i co .d t ( (M CC CO O UJ -4 3 3 J 3 00 4 v. n NO O ^ <- K> 10 >l II > s = 00 V M (. f\ L 2 w ? I 2 VO ^ -4 >-< H ^ 00 X5 OO ^ I (J 3N * t 2 g a o I? g 1 rt \ 3- C* S-' ** ^ ~ n ^ n i?'~ J " Si ^"* rt rr" ON w^ r - f t 5 5' P !J* 3 3 1 " 1 13 P- ( 5 CO ^ M g. ? 2. "3 k* , 2.- n 3 5 '' CO M ? J Lri OO S' r|- |3. 2. 3 |>^ > F ON o On B 3 K> 1 8 1 | i 3 - s* r CO J 0- Ln r J r-r O t> w M ^ w j &> c ** 1 <* ^ >* OO -1 ^ 5 3 3.3 * T 3 3 W >-K s N OO i 3 (JQ I 3 o* i -t II II 1 ^ -| k {j M ' ^ ^4 ON o OQ j^ 4 Vj 3 ^J i 3 O 00 -< OO ^ 4^ O 4 OO vO NJ 3 M H M ^> -f 1 - v> 00 Os Lrt OO ^ 5 '* Ln ONVJ 5 >O J ON ON M j ! ON > J 38 ORDXANCE. stated "before the Ordnance Select Committee, in 1863, that lie had made over 400 guns in England for foreign governments; half the number were of steel, and half of cast-iron strengthened with steel. 57. STRUCTURE. Xo wrought iron is used in the fabrication HOOPED GUNS. 39 of these guns,* on account of its liability to become permanently stretched. The simplest form of hooping is a series of narrow steel rings (Fig. 32 B) shrunk over the chamber of a cast-iron gun. FIG. 32 B. Blakely 74- in. rifle, captured at Shipping Point, 1862. Scale, T 7 5 in. to 1 ft. The engraving shows the 7^ in. rifle captured at Shipping Point. It has a reinforce 17^ in. long and If in. thick, composed of three steel rings ; length of bore, lOOf in. 58. A larger use of steel is shown in Fig. 32 C a low-steel barrel hooped by a tube of higher steel, outside of which is a cast- iron jacket carrying the trunnions. This gun a 9 in. rifle (the engraving, Fig. 32 C, is made from drawings of Fawcett, Preston & Co.'s Nos. 195 and 196) has an inner low-steel tube of 15 in. diameter, embraced by a higher steel tube of 22f in. diameter, over which there is a cast-iron jacket of 38 in. maximum diame- ter. Length of gun, 12ft.; length of bore, 131^ in. ; weight, 11J tons. 59. This gun combines the two principles of initial tension and varying elasticity, f The two inner tubes are stretched un- equally by the pressure of the powder. If both tubes are of the same metal, their resistance to the elastic pressure is inversely as the squares of their diameters, so that to do equal work, the outer one must be previously stretched (287). But if the outer tube is of a metal that does as much work in stretching a little as the inner tube does in stretching more if the capacity of the metal to stretch is proportioned to the amount of elongation which it must * The first gun made by Captain Blakely for the Confederates (73) was hooped with wrought iron. f This method of construction has recently been patented by Captain Blakely in the United States. 40 ORDNANCE. FIG. 32 C. actually undergo, no initial tension is required (320). Now, 1st, it is difficult to give metal hoops the exact tension re- quired, especially by shrink- ing them, and they are likely to become relaxed under maintained high tension; 2d, the elasticity of metals does not vary exactly as required. But if the layers of a gun. are arranged with the best degree of varying elasticity that can be attained, a little initial tension will put the metal into the condition of greatest resistance, and the principal disadvantages of both systems will be avoided. GO. The inner tube of the gun (Fig. 32 C) is made of a low steel having consider- able, but not quite enough elasticity. The next tube, of a high steel with less elas- ticity, is shrunk upon the first with just sufficient ten- sion to compensate for the insufficient difference of elas- ticity between the two tubes. And the outer cast-iron jacket, which is least elastic of all, is put on with only Blakely's 9-inch rifle. Low steel bore, hooped by high steel and cast iron. Scale, T 7 F in. to 1 ft. the shrinkage attainable by warming it over a fire. In- deed, the cast-iron could not be highly heated without perma- nently stretching and warping. HOOPED GUNS. 41 61. The construction of the heavier all-steel guns is illustrated by Fig. 32 D. The hoops and tubes are, if possible, all put together at one heat. The ob- ject is to lessen their liability to fracture, by giving them better surface contact. If both the surfaces are hot and soft, they will both yield to each others' irregularities ; but a cold mass not only will not yield itself, but chills the surface of the hoop placed over it. Besides the guns enu- erated in Table X. (of which except the 12 in. gun have een produced entirely of steel), 4 number of the following classes of guns have been fabri- ckted: The all-steel 5 '8 in. rifle (Tig. 33) has 97 in. length, 82 iri length of bore, 10'875 in. dikmeter of inner tube, and 18 in. maximum diameter. 63. The following are the particulars of the Blakely S T \ in. guii (Fig. 32 A) in the Exhibi- tionlof 1862. The barrel of the gunl was an Armstrong cast- iron Iblock (91), having a cylin- drical breech 50J in. long, and of a smaller diameter than the chasel This was hooped by Fawcett, Preston & Co., with a steel jacket hooking over tie breech end of the cast- 42 ORDNANCE. iron, and extending forward under and beyond the trunnion-ring. Over this steel jacket were seven steel hoops. In front of the trunnion-ring three steel hoops were shrunk over the cast-iron. Length of caft-iron barrel, without cafcabel I22-| inches. Diameter do. at the breech 16^ " Diameter do. in front of trunnions 20^- " Diameter do. at rear of muzzle fwell i6|- ** Length of fteel jacket over the caft-iron 50^ " Outer diameter'do 23! " Length of 7 hoops behind trunnions (4|- inches each) 33^ " Outer diameter do 29! " Length of 3 hoops in front of trunnions 18 " Thicknefsdo if FIG. 33. Blakely 5-8 inch steel rifle. Scale, T 7 g in. to 1 ft. 64. A 9 in. cast-iron gun, hooped with steel rings, is of the following dimensions : Length of bore lift. 3 in. Length of gun 12 " 6.}" Diameter of cylindrical caft-iron part under the rings 26 " Diameter over rings 36 " Diameter in front of trunnion ring 2,yi" u Diameter of muzzle 19 * Weight ii tons. The rings extend from the trunnion-hoop to the end of the breech, in one tier. The vent enters the chamber from behind the rings. The Blakely guns made for the State of Massachusetts* are eight 9 in. guns and four 11 in. guns, constructed of Naylor, * A 7 in. gun substantially on this plan has been constructed for the United States Navy Department. HOOPED GUNS. 43 Tickers & Co.'s steel. Of the 9 in. guns, the inner barrel is IS in. diameter, forged solid. This is reinforced by a jacket forged hollow, of 27 in. diameter, hooking over the barrel at the breech, and extending forward under the trunnion-ring, which is of cast-iron. In front of this jacket there is a course of rolled hoops (68). Behind the trunnion-ring, and over the jacket, are two courses of rolled hoops, breaking joints, and making a total diameter of 38 in. The bore is 11 ft. long ; the rifling is that of the 9 in. gun (67). The charge for these guns is 30 Ibs. of powder and a 248-lb. bolt. The proof was 45 Ibs. of powder and a 375-lb. bolt. The 11 in. gun lias a solid forged steel barrel of 22 in. diameter. This is reinforced by a steel jacket of 33 in. diameter, cast hollow, but not hammered. The other hooping and the rifling are the same as those of the 9 in. gun, the maximum diameter being 48 in. The service charge is 37-J Ibs. of powder and a 375 Ib. shot. This gun has fired 525-lb. shots, with 52-J Ibs. of powder, through 45 feet of earth. 60. The following are particulars of the 11 in. guns (Fig. 35) furnished by Captain Blakely to the Russian Government. The guns are of cast-iron, hooped with steel, and rifled on the shunt plan with eighteen grooves. The trunnion-rings are of wrought iron. Total length of gun 17 ft. ... in:. Length of caft-iron barrel 16 " I Length of bore 15 " ... Length of fteel hooping 6" 9 Maximum diameter of caft-iron barrel 33 Diameter of hooping, over chamber 47-J- Diameter of trunnion hoop 53 Diameter of bore , 1 1 Diameter of muzzle 19 6G. The largest guns at present fabricated under Captain Blakely's specifications are the 12 j- in. rifles, called 900-pounders (Fig. 34), made by Messrs. George Forrester & Co., Yauxhall Foundry, Liverpool, and sent to Charleston. The guns have cast-iron barrels hooped with cast-iron, put on with slight ten- 44 ORDNANCE. FIG. 34. FIG. 35. FIG. 34. Blakely 900-pdr. (12f in.) rifle, sent to Charleston. Scale, ^ in. to 1 ft. FIG. 35. Blakely 11-in. rifled gun for Russia, T 7 S in. to 1 ft. HOOPED GUNS. 45 sion. There is an outer steel hoop over the powder-chamber. A bronze air-chamber, of 6 Jin. bore, is placed in the breech, as shown. Total length of gun... 16 ft. 2 in. Total length of bore to bronze chamber.. ... ; 12 " 7 Total length of bore to bottom of chamber 15 " 4 Maximum diameter of caft-iron 44 Diameter of caft-iron muzzle 24 Diameter over fteel hoop 51 Diameter of bore iz\ Diameter of air chamber 6_ Weight 27 tons. The guns were intended for shell firing ; the charge is stated to be 50 Ibs., with a 700 Ibs. shell. The first of these guns burst at Charleston with 40 Ibs. of powder and a 700 Ibs. shell ; but this is attributed by Captain Blakely to filling the air-chamber with powder, thus leaving an air space between the charge and the projectile, instead of behind the charge, as intended. 67. The rifling of the 9 in. gun is shown full size by Fig. 36. A copper disc at the rear of the projectile is forced into the FIG. 36. ^^**~ ^^^m^- Rifling of 9-inch Blakeiy gun, full size. grooves by the explosion of the powder. (See chapter on Rifling and Projectiles.) 68. TREATMENT OF THE STEEL. The steel employed is usually that of Messrs. Naylor, Tickers & Co., Sheffield. Krupp's, Bes- semer's, and Firth's steels are also used. The short rings are rolled without a weld from circular ingots by Messrs. UTaylor, Vickers & Co. This is done in a machine similar to the ordinary railway-tire rolling-machine.* The process is simply illustrated by Fig. 37. A circular ingot is squeezed between a pair of short rolls until its section is reduced, and its diameter increased. The * Steel railway-tires are made in the same machine. 46 ORDNANCE. metal is also condensed, and an endless grain is developed in the direction of the circumference. 69. The steel tubes or jackets are cast hollow, and hammered over steel mandrels, under a steam hammer. During this process FlG 37 they are elongated 130 per cent. Much difficulty was at first expe- rienced in preventing the sticking of the mandrels, but the manufac- ture has been so far developed, that Machine for rolling hoops from solid tlie tubes Can be drawn aild con ' cast-steel rings. densed like a solid ingot, with the great advantage over piled or coiled iron, of no weld. The steel jackets sometimes extend over the breech of the inner barrel; the mandrel is withdrawn when the solid end of such a jacket is ham- mered. In some cases the jackets are not hammered, but are simply annealed, bored, and turned as they come from the mould. Messrs. Naylor, Yickers & Co. are perhaps more skilled than any other steel makers, except the Bochum Company in Prussia, in the art of casting large masses of all shapes, such as tubes, bells, wheels, &c., sound and uniform throughout. It is considered, however, that the increase of strength by hammering will always warrant the expense of the hammering in gun work. 70. All the steel parts are annealed. This process makes the crystallization finer, and increases the specific gravity, the result of which is less absolute tenacity, but far greater ductility. (See chapter on Cannon Metals.) 71. The results of the Blakely gun are not very generally known, for several reasons. First, the greater part of those in actual use are in the Confederate service, so that detailed facts will only be made public after the war. Second, the Continental governments that have bought these guns, keep their artillery practice very secret. Third, although repeatedly urged, the British Government has made no experiments with the late Blakely ordnance.* The fact that Sir William Armstrong was * A 11 in. Blakely gun has recently been the subject of experiments at Woolwich (at the maker's expense), but the results have not been officially reported. HOOPED GUNS. 47 Engineer for Rifled Ordnance, and that Captain Blakely's patent covered Sir William Armstrong's first gun and circumscribed 'his manufacture, may have had some influence in this direction.* The first gun sent to the Confederates (73) is stated to have fired above 3000 rounds. 7*2. CAPTAIN BLAKELY'S EARLY EXPERIMENTS WITH HOOPED GUNS. " Captain Blakely's first gun was an 18-pounder (Fig. 38), FIG. 38. Blakety experimental 18-pounder. consisting of one series of wrought-iron rings, shrunk on a cast- iron cylinder, 5-J- in. inside diameter, and If in. thick. The wrought-iron rings were from 2 in. thick downwards. The total thickness of the breech was 3f in., that of the ordinary 18-pounder service gun being 5 j- in. This gun was fired frequently, and stood well. It was then bored out as a 24-pounder, but not being truly bored, the cast-iron was reduced, on one side, to only -J in. thick. In this state it sustained, without injury, several hours' firing, with charges varying from one shot and 4 Ibs. of powder to one shot, two wads, and 8 Ibs. of powder. At the third round, with this latter charge, it burst. This gun had a thickness of only 2J in. round the charges, as compared with a service 24:- pounder, of 6 in. in thickness." f * Captain Blakely stated before the Select Committee on Ordnance (1863) that he had offered to lend the Government, for trial, free of charge, a 12 in. 10-ton gun, to fire 700 Ib. shot and 70 Ibs. of powder, and a 9 in. gun; but as a condition was that he should submit the plans to a committee embracing Sir William Armstrong, he refused; also, that he offered to lend the Government a 200-pounder (8 in.) that would pierce iron-plated ships, but that they refused to test it. The author saw at Woolwich, in September, 1862, several bursted cast-iron hooped guns, resembling the Armstrong cast-iron gun (91), but distinctly marked "Blakely" with paint. Upon questioning Captain Blakely in the matter, the fact was elicited that the Government never had any of his guns. Captain Blakely now attributes this singular proceeding to a mistake on the part of some under-official. f "Construction of Artillery." List. C. R, 1860. 48 ORDNANCE. TABLE X. PARTICULARS OF ALL-STEEL BLAKELY ORDNANCE AND AMMUNITION. FURNISHED BY THE BLAKELY ORDNANCE COMPANY. NAME OF Gim. Weight. Diame- ter of bore. Length of bore. No. of grooves. Twist of rifling. Weight of pro- jectile. Charge. Market price, October, 1863. loo-pounder Ibs. 8000 in. 6-4 in. 96 8 1 turn in calibres. 48 Ibs. IOO Ibs. IO $5000 0600 7 IOO 8 4-8 I 20 12 6000 200- pounder j 7000 8 ( 144 to) 12 48 2OO 2O IOOOO 25o-pounder 5 co-pounder 24000 2OOOO 9 10 1 156 / do do 12 I C 48 48 250 3CO 2 5 5 C 11250 17500 7 COOO 1 1 do I 2 l6 C CO r c 27 COO 7OO-pounder 40000 12 do 12 16 700 7O 7 COOO FIG. 39. Blakely experimental 9-pounder. FIG. 40. Captain Blakely's next gun* was a 9-pounder (Fig. 39) of 4 in. bore, turned down from the trunnions to the breech to 10^ in. diameter. This he hooped with a tube of T fo m - less than 10J in. bore, and tapering outside from the breech end. The tube was made of wrought iron, and, for con- venience, in three pieces. This gun was fired at Shoeburyness, in 1855-6, round for round with a cast-iron service gun of the same size Mr. Dundas' wrought and weight, and with a gun (Fig. 40) made by Mr. Dundas of wrought-iron staves hooped iron gun. * "A cheap and simple method of manufacturing strong cannon." 1858. HOOPED Guxs. 49 together, and with a brass service gun. Table XL* gives the result : TABLE XI. TRIAL OP BLAKELY HOOPED O-POUNDER, WITH SERVICE CAST-IRON AND BRASS 9-POUXDERS. No. of shot Blakely. Charge of powder. No. of Shot. No. of rounds fired. No. of shot fired from Service Gun. Blakely's. Service. Lbs. 4 8 2 * 2 4 86 3 I 86 86 86 26 4 i 26 26 26 5 5 I 5 5 5 10 5 2 5 5 10 636 6 2 318 no Burft 22C 3 6 3 i ... 4 6 4 i ... ... 5 6 5 i ... 6 6 , 6 i ... 7 6 7 i ... ... 8 6 8 i ... ... 9 6 9 i ... ... 1580 6 10 158 ... 2389 607 234 351 I Thus it appears that Captain Blakely's gun stood 607 rounds, and the government service gun only 234 rounds the number of shot thrown being 2389 and 351 respectively, or nearly as 7 to 1. Mr. Dundas's gun burst at the third round with 6 Ibs. of powder and two shot. The brass gun became unserviceable after 174 rounds. * " Construolion of Artillery." Inst. C. K. 1860. Also, "Report of Select Com- mittee on Ordnance," 1863. 50 ORDNANCE. FIG. 41. Blakely's 132-pounder of 1857. Scale, -ft in. to 1 ft. The class of guns fabricated by Captain Blakely after these experi- ments is illustrated by Fig. 41. (See, also, table X.) 73. The following are particu- lars of the first gun sent by Captain Blakely to the Confederates, ob- tained from a drawing dated May 15, 1860. The gun, made by Faw- cett, Preston & Co., was of cast-iron, reinforced by a solid wrought-iron hoop made thin at the edges. Total length of gun 84 in. Length of bore 73'5" Diameter of bore 3 '5 " Diameter of caft-iron under hoop 9 I " Maximum diameter of hoop 12-1 " Length of do 22-2" Diameter of muzzle 6-0 " 74. IV. Tlie Parrott Gun. FABRICATION. This artillery is fabri- cated exclusively by Captain R. P. Parrott, at the West Point Foundry, Cold Spring, K Y., a private estab- lishment* of great celebrity. A * Captain Parrott, who had long made cast- iron ordnance for the Government, started the manufacture of rifled guns in I860. (See table of cost of guns.) The British Government has spent on Ordnance and Plant since 1859 over twelve millions of dollars, and although it lias acquired a gun capable of higher charges for a few hundred rounds, and what is more valuable, the experience which will enable it to fabricate the best steel cannon without further risk, it is still without a trustworthy naval gun, or gun of position, HOOPED GUNS. 51 FIG. 43. FIG. 42. cast-iron gun of the ordinary shape, except a little lighter at the breech, is reinforced over the chamber with a wrought-iron hoop made from a coil substan- tially like the Armstrong coil in proportion and manufacture. The 100-pdr. and the 8-in. and 10-in. guns are now cast hollow on Captain Rodman's plan, the advantages of which will be further considered. (373.) The bar of iron from \vhich the coil is made is rectangular in section when straight, but becomes wedge-shaped (Fig. 42), when bent into a coil, thus leaving a space for cinder to be squeezed out when the coil is upset. This feature is directly contrary to, and an evident im- provement upon, the Armstrong plan. 7o. The hoops are shrunk on without taper, the difference in diameters being T L in. in 1 ft. They are fastened to the cast-iron only by the adhesion due to their tension, and have never been loosened during test or in action. "When a hoop is to be adjusted, it is heated and slipped over the breech, the gun being slightly depressed. A stream of cold water is then run into the bore, not for the purpose of cooling the hoop from the interior, but to prevent the expansion of the cast-iron. 76. The length of the reinforce, which in the 100-pounder is but 27 in., is believed by Captain Parrott to be sufficient to take the first and severest pressure of the powder in starting the projectile. A short reinforce is not loosened, as a lone: tube would be. bvlon- Parrott G-4 inch "100- ., -,. -, T ' . J pounder " rifle, ^ in. gitudmal shrinking when first put on. to l ft. 52 ORDNANCE. 1 HOOPED GUNS. 53 77. Great care is taken in the selection of the material. The cast-iron part of a 100-pounder that was fired 1000 consecutive rounds without injury even to the rifle-grooves, was composed of Greenwood Iron, No. i 4480 Ibs. Greenwood Iron, No. 2 3360 " Salifbury Iron ,., 2352 " Scotch Iron 336 " Gun Heads 2240 12768 BAB. Denfity 7 -375 Tenfile ftrength 2 9^97 Ibs. HEAD. Denfity 7-2848 Tenfile ftrength ..... 36975 Ibs. The metal was 2J hours in fusion. The reinforce was made from a bar 76 ft. long and 4x4 in. in section. It measured, finished, 27 in. long and 3 -2 in. thick, and weighed 1725 Ibs. 78. All Parrott guns are rifles.* The sole object of the reinforce is to enable a cast-iron gun to stand a rifled projectile with the service charge that would be employed for a spherical shot ; for instance, to enable a 6*4 in. gun to carry a 100 Ib. shot, instead of a 32 Ib. shot, with 10 Ibs. of powder. The gun is cheap, and has proved very serviceable, although not as formida- ble as much of the experimental artillery that promises to become standard. It is intended, not to exhaust the capabilities of the system of initial tension,f but to utilize that system as far as pos- sible without greatly increasing the cost of the standard ordnance, and without serious risk of damage by exposure and maltreat- ment in the hands of green artillerists. * The system of rifling and projectiles is described in the following chapter on that subject. f In attempting to exhaust the capabilities of that system, Sir William Armstrong and others have carried it so far, that the proper initial tension is soon impaired by the vibration and stretching of the metal (335). 54 ORDNANCE. For land service, several sizes of small guns are in extensive use. (See table XII.) Tlie larger guns, suited to naval war- fare, are shown by Figs. 43, 44, and 45. The 100-pounder is largely employed in both the Army and the Navy. The 8 in., called a " 200-pounder," a gun of more recent date, already used in turrets alongside the 11 in., 13 in., and 15 in. smooth-bores, is a favorite gun in the Navy. Several 10 in. guns, called " 300- pounders," are in service. One of them is understood to have done most of the work in breaching Fort Sumter. Since the commencement of the war, up to April 1st, 1864, about two thousand Parrott guns had been fabricated at this establishment, viz. : lo-pounders 336 20 do 507 30 do 572 60 do. . 10 I oo-pounders 444 200 do 112 300 do 4 79. The 8 in. rifled gun has thrown spherical smooth shell, filled with earth to weigh 52^ Ibs., with papier-mache sabot's, at the initial velocity of 1809 feet per second; charge, 16 Ibs. the same charge that fires the 152 Ib. elongated shot at 1200 feet. With a charge of 25 Ibs., the gun fires a 68 Ib. to TO Ib. cast- iron or steel spherical shot at above 1800 feet per second, with about the same strain, and no less safety. This gun may, there- fore, be pronounced the most formidable service gun extant. Neither the English 68-pouuder (8 in.), nor the French Naval gun (6*5 in.), nor the IT. S. cast-iron 8 in., 9 in., and 10 in. guns can endure such charges; the Armstrong 110-pounder (Tin.) can- not fire spherical shot, and the U. S. Navy 10 in., and the new English steel-lined T in. and 9 in. guns are not yet service guns. Capability of throwing spherical shot is of course chiefly due to the form of rifling, and will be further considered. 80. ENDURANCE. A 100-pounder, before mentioned, and to be further referred to under the head of "Rifling," stood 1000 consecutive rounds, with service charge of 10 Ibs. of Dupont's No. T grain powder, and projectiles averaging 100 Ibs.* The gun * This gun was the 100-pounder exhibited at the New York fair for the Sanitary Commission. HOOPED GUNS. 55 O.L. OOOO O O 1 1| i 1 1 1 i ~ C 3 S 3 3 3 3 e- Q- D- a. a. a. n n n n ( '.Iff . . i : : M M HI M M 4* ON O t - fl ON O vo O on 00 Length of Bore. O 00 ON en 4* 4* CO co t/ 1 4= en 4* co t to ON vi S II a 4* CO tO fc> M M H-( M Ot><-ni-iOOOO-|i. >-> c \O co co co ca co w o U HI M ONONVOCaco^ki-i g cncovicocnto vi oo g O O O ON en O en SO OOOOOO O O 1 ^ = ,0 ^ ^ ^ W f! cf" 1 cfl C4"" cj" 1 c^" o|" ol" 5" Kf 11 0> t^ HI M HI HI M Ocooocn t O ON 5' k Twist of Rifling. (Increasing.) | M M t" 1 cnONOONCO t nig' O ! (0 HI C/3 CO CO CO co co vi cr cr tr cr ono t {LojL^f 1 O O O rt- ^* ** ^ H M M M M .H, Cn VI O <-n CO OO\O VO O O en O en O *^t- iHtaH Weight of Projectile. b OO OO ^^ sf! 56 ORDNANCE. remained in good condition, the greatest enlargement by the star-gauge being -023 in., near the seat of the brass ring on the base of the projectile, and opposite the forward end of the reinforce. Another 100-ponnder has endured 1400 rounds in action ; a 30-pounder has been fired 4606 times with service charges, and at the very high elevation of forty degrees; the second 300-pounder sent to Charleston has fired 600 service rounds. All these guns are still in service, and apparently in perfect condition. The bursting of a shell within the chase of the first 300- pounder, at the siege of Charleston, broke off the muzzle ; but the gun was repaired and in action within forty-eight hours. In fact, the principal source of injury to the Parrott guns has been the premature explosion of loaded shells within the bore, thus blowing off the muzzles, or destroying the cast-iron in some other part forward of the reinforce. Much has recently been done to- wards remedying this difficulty. Yery few of the guns have burst through the reinforce.:): 81. V. ]flicellaiieoiis Hooped Guns.* Spaiiisli Gun. Cast-iron guns hooped with steel are extensively fabricated and highly approved by the Spanish Government. Commander Scott says on this subject :f " Spain has also followed the example of France in hooping her heavy ordnance, havjng previously ascer- tained that the unhooped cast-iron guns rapidly deteriorated, and ultimately burst at less than 200 rounds, but that the hooped guns, when properly fitted, which was arrived at by careful ex- periment, always stood more than 1000 successive discharges." 83. The following extracts from " a series of reports from Spanish officers to their Minister of War" were read by Cap- tain Blakely before the Select Committee on Ordnance, 1863. On the 2d of January, 1860, they say : " Cast-iron by itself, as is clearly proved to us by the bursting of the guns we fired, is not strong enough to resolve the question of rifled cannon of large calibre, unless the charge of powder be much reduced, * See Tf 127, also Appendix. f Journal Royal U. Service Inst., April, 1862. \ See note in Appendix. HOOPED GUNS. 57 FIG. 46. Spanish steel hooped gun. Scale, & in. to 1 foot. and even then it must remain subject to the distrust of the gunners; besides the difficulty of obtaining sound large masses of forged iron, that metal has not the necessary hardness for the bore of the gun. The path we must follow, then, is clearly indicated: cast-iron guns hooped, a most simple manufacture, which, once estab- lished, only requires great care in bringing the hoops to the exact diameter. The difference between the diameters of the hoops and of the cast-iron part must be determined by calculation aided by exper- iment." Another report, signed Gabriel Pellicer, First Commandant and Director, is as fol- lows : " The proof of the rifled cannon of 6j- in. bore, and weighing 62 cwt.,* has been continued with a charge of 6 Ibs. 9 oz. of powder, a wad, and an elongated projec- tile. It has now completed 1000 rounds with the same charge. At the 967th round a steel vent-plug was inserted. The state of the gun is perfect, except a few scratches observed in the end of the bore close to the vent, and caused without any doubt by the premature destruction of the vent- plug." 83. The Spanish 6-4 in. gun (Fig. 46) is stated by Captain Blakelyf to have stood 1366 rounds, with an average charge of 7 Ibs. of powder and a 61 Ib. projectile, before bursting. The Ordnance Select * This gun was cast-iron, hooped with steel. f Journal of the TJ. Service Inst., March, 1862. 58 ORDNANCE. Committee of Spain say in their report: "Although the 1366 rounds fired with the above charge of powder and an elongated shot of 61 Ibs. are sufficient proof of the satisfactory resistance of the gun, the following observations will render still more ap- parent its excellence, and consequently that of the hooping sys- tem. During the first days of proof, 100 rounds were fired with intervals of only from one to one minute and a half. This made the gun so hot that it could not be touched with the hand. The following days 50 rounds were fired in the morning and 50 in the evening, with the same rapidity." 84. French Onus. The " Canon de 30," which is the stand- ard French rifled navy gun, is represented by Fig. 47. It is of cast-iron, hooped with seven separate steel rings 4-4 in. thick, forming a reinforce from the rear of the breech nearly to the trun- nions. In the later naval guns, the rear of the breech is a little longer than shown in the engraving ; the rear of the reinforce is rounded, and the muzzle swell is omitted. The following are the dimensions :* Total length of gun < (3 <2 5 ) 127-985 in. Length of bore (2-75 ) 108-295 " Length of cafcabel ( -260 ) 10-239 " Length, rear of cafcabel to rear of fteel reinforce ( .375 ) 14-767 " Length of fteel reinforce ( -975) 38-395 " Length, front of fteel reinforce to centre of trunnions (-105) 4-135*' Diftance of trunnion below axis of bore ( -090 ) 3-544 " Diftance between rimbaftes ( -560 ) 22-053 " Length of trunrtfons ( -170) 6-695 " Diameter of trunnions...., ( -180) 7-088 " Diftance of vent (vertical), forward of rear of chamber ( -065 ) 2-560 " Diameter of bore ( -1647) 6-489 " Diameter of caft-iron under hoop ( -488 ) 19-217 " Diameter of fteel reinforce ( -6 ) 23-628 " Diameter of caft-iron in front of fteel reinforce ( -580 ) 22-840 " Diameter of muzzle ( -310) 12-208 " Weight (3737 M 8239 Ibs. Preponderance ( 230 k.) 506 " 85. The rifled siege guns and guns of position are of the same calibre, but are mostly of cast-iron without hoops. * Official drawings, dated 1863. HOOPED GUNS. 59 86. Many of the rifled navy guns are said to be the old 30- pounders ~No. 1, weighing about 56 cwt.* An efficient breech-loading apparatus has been applied to many of the French guns. It will be described in another chapter. 87. The rifling consists of three grooves (Fig. 48) with in- creasing pitch, commencing at and ending at 1 turn in 30 diameters. The cast-iron conical-headed shot, of two calibers length, weighs about GO Ibs.* Projectiles of lOOlbs. weight are employed, and flat-headed steel bolts are fired at armor. The projectile has three studs, faced with zinc, by which it centres itself in the grooves of the gun. The results of this method of rotating the shot are very satisfactory, and will be considered in a following chapter. 88. The usual charge is stated to be from Tibs, to 8 Ibs. ; but higher charges are known to be used. Captain Blakely states* that 27 Ibs. to 28 Ibs. of powder are used in firing 92 Ibs. to 100 Ibs. shot at armor-plates, and that in the experiments of August 9th, 1861, 99 Ibs. steel flat-fronted shot were fired with 27^- Ibs. of powder, at 1089 yards range, through a 4Jin. plate with 18 in. wood backing and 1 in. skin. 89. Captain Blakely also states that some of these guns have endured 2000 rounds. 90. It will be observed that the gun is not weakened longitu- dinally by cutting away the cast-iron under the hoops, as in the British guns (Table XIII.) The use of steel hoops instead of iron, and the very careful adjustment of the hoops, must account for the very satisfactory strength and endurance of these guns.f * Evidence before the Select Committee on Ordnance, 1862. f The French guns of large calibre are 10-inch bronze smooth-bores, but their charges are small. The question is naturally asked Why is France content with a G - 5 inch naval gun, whatever its endurance? The probable reason is, that the Emperor, being unable to produce suitable steel in France, will not import it, knowing that England would then adopt steel, and, by developing her own manufactures, place the produc- tion of an indefinitely large steel armament under her own control. So long as England has nothing better than wrought-iron coils and complex breech-loading, France feels safe with a gun that is simple, cheap, and trustworthy if it is small 60 ORDNANCE. FIG. 47 French hooped 6 - 5 in. 100-pounder. (Ca- non de 30 ) 91.* Armstrong Hooped Cast-Iron Naval On 11. Several 68-pounder blocks, shaped at the breech as shown by Fig. 49, were hooped on a plan proposed by Sir William Armstrong. The hoops were shrunk on without reference to their tension, and the thickness of the cast- iron under them was suddenly reduced by five inches. The result of their test is detailed in Table XIII., and was so unsatisfactory that the plan was abandoned. Captain Blakely said before the Select Committee on Ordnance, in 1863, that the French had made a long series of similar experiments, which had similarly failed. FIG. 48. llifle groove and stud of Canon de 30. Full Another plan of hooping tried at Wool- wich (Fig. 50) is mentioned in Table XIII. The ring, of wrought-iron, was so thin and ductile, that in one instance the cast-iron burst without fracturing it. The Ordnance Select Committee, in. the re- port on the competitive trials of rifled guns in 1861, say, with reference to these English until some better system is developed at some one else's expense, or until France can produce steel. It is understood that great efforts are making to this end. Since the above note was written, England has begun to adopt steel and muzzle- loading, and France has begun to order 300-prs. from England. * For recent orders to hoop old guns in the U. S., see Appendix. HOOPED GUNS. 61 00 GO S H ^h O No. of round vO v< 5 w vo rl 4_ vo c^ 3 VO ro O T$- m M 2 r f 2 'a v *' *" 05 1 lii-T ^ 1^00 ^o ' 000 J"3 1 ' 000 , & ^ | ON o ^ xO 52 5 O O O c* O *-s" ^ o o o o o o o O cl Z '? t/fc * l-t ^ N w si U <* o !l'~ ^ *" jSy* c *OO OOOOOO tr>vr>O vnO 4 i O VO VO VO VO VD VO ro VO 00 ^ Cl MUM M |* M M M ONO O O "-> OOC vo va j oooo oooooo oooooooooo 0) -3 r ^ T r .< ~ ~? ~ > >> S* 5* _ oc oo-r! M -?!cL.a 1 ^ ^ r ^ ^> r^ 10 ir 6 Ooo oooooo i^.t-~-vO VO VO c O M Hif i : 3 "- o : j li -C < * T3 -o -o g i g : JS ^ i j 1 c H - fa -o 2 bs e g .a "^ s S. " c 'S. - .s g s i -T3 l 2.*! _y >> o- o , ^ 3 j= > _> e CL, e n ^ 2 J ^oo c -o w . C '2 v, C O 1 & V >-, 4J - 3^2 Pi '^jg ."3 *^ 3 C< c W) *^ a- 4j rt flj J2 a; -* ^-* .Si c~ ^j 2 C "^ -o <-S* oT cr ? . <^- M c o 1 3 r " 1 U u , ^ C hpffei u g ^ -G o -o c -o -9 "2 " c o 03 J^ || j *J?S Z s A c *n ^ - c -1 c i 2 ii i ^- *' J5 "0 C*^ H T - C -. O J^ _0 u r2 1 1 if ^ O C * f ^ '--i^ j j- ja -C "^ -^ j2 ^ fS * c _S ci *E C* "^ S qj ^ -^ ^ ** u' u' c ^ fc ^ e 4J u o 2 4J O o 2 o rf "^3 -C3 flT *-* V -o 1lllisllli^lil1 '7 '5 f* ?* S 'c O ^ S '& * ?"f^ O OOOO JHO G "^00 wvOvO <D 00 00 00 oo oo "O ^J _ a 1 fcQ h i "3 ' M i o ba 3 c "o be VO O oo ""f~ O - 00 o^ *o to d "-I *< M b c o O O V3 rt O o O O *H *-* be to to rt M O O to CO o ^ G O O O O vo J 10 o rt rt VO VO O vo bo M m _^ 5 w % vo vn vo VO VO \J t-- t- to f > vo % to vo rt c! 1 vo VOVO vo vo vo VO vo vo 1 al tube of wrought ping, ftrengthened cL u -0 i i 111 5 if g :| ^ I rt 2 'J? a : -* PQ : n , is-pounder cali- ng from trunnions 8 i o ; il -C 60 I c >% u 1 ^0 c 'c ased by the weight < ard, cutting oflf vent e c II S -^ i 4 't j_ Mi ^* 4> rt '- g 0- ." ^: ,-~ S j3 > rt III A ^ |l C be 2^? Cu to C rt M 3 C e ^ rt Hi o u ~ ^? u |? ^J i- ? tJ3 rt S'c u rt -o -3.fi S 1 c "S ^ i O o 1 K i c 3 C 1 5 WJ J5 C *-> AJ ISg 6"^ "SI -3 '= PQ^ u " o' C-. "c u 'u ca M block, proved i afterwards turnc ji = S rt "2 'i Is -C -C T3 C fg 6 2 ^ ^ ^5 o i 3 -s w C oT A I xperiment the cy li 8 Ibs. charge an 84th. s increased by ha h S Ibs. charirc an 133d. <4th round, inner !i ~ i F w cT *- "^ f -C o 5 u 73^-^3 C W C 3 - D * fsjr J-* s QJ '-C D T3 1 a. ?T i 02 rt J3 e ^ Idl It .s-s 1^ T3 If rt ""* i>i All * -t- -H- 1 ? ^ J 5^- >. s d u 60 do Ditto Ditto external diameter i 5 -r do. 80 Ditto ditto i ~'^ do Ditto Burft 6 7 2 do. 2 coils of wire -fa inch Ditto, one end loofe yu 9 IOO No effect. Bulged at loofe end. g Bulged to i^i / u No effect IO do Ditto ... I IO Ditto 1 1 do. Ditto I 20 Ditto. One end of wire came loofe 12 do. Same cylinder, with one -| coil of - { V wire J 100 c Burft, the end of the wire being I 3 5" 2 coils of '>~a wire IOO No effect 14 do. Ditto 1 20 Ditto. I r do Ditto 1 10 Ditto 16 6 4 coils -jW wire 1 20 Ditto 17 do. Ditto I TO Ditto 18 do Ditto . I4O Ditto 10 do Ditto I ?O Ditto. 20 do. 1 60 Ditto. 21 do Ditto . 1 70 Ditto 22 do Ditto 180 Ditto. do Ditto Ditto *3 HOOPED GUNS. 67 9*4 tons per square inch. Assuming the law, as above, the ulti- mate pressure, supposing the cylinder to have been full, could not exceed 9 '4 X ! or 13 tons per square inch. " The enormous strain to which these cylinders were subjected is evidenced by the effects upon the gun-metal balls, which were more or less cut away by the gases, where they touched the cylinders. 96. " These experiments, made on the 17th May, 1855, were so satisfactory, that the author proceeded to one on a larger scale. This consisted of a brass cylinder, of nearly the same internal dimensions as a 3 Ib. mountain gun, say 3 inches diameter and about 36 inches long. The drawing of this cylinder has unfor- tunately been lost, but it is approximately represented in Fig. 52, FIG. 52. Mr. Longridge's experimental wire-wound 3-pounder. from which it will be seen that the thickness of the brass was i inch. At the breech end it was covered with six coils of steel wire, square in section, and of K"o. 16 wire gauge, or ^th of an inch. These coils extended about 15 inches along the cylinder, and were gradually reduced to two coils only, towards the muzzle. Consequently the thickness of the cylinder was as follows : At the breech, J in. brass + f in. iron f in. At the muzzle, J in. " + in. " = f in, " The thickness of the 3-pounder gun, with which it may be compared, being At the breech, 2'37in. At the muzzle, 0*75 in. " It will be seen that this cylinder was not mounted as a gun. It had no trunnions. It was cleaded with wood ; and the object 68 ORDNANCE. of the deep steel ring, which was screwed on the muzzle, was simply to cover the ends of the cleading. The cleading had nothing to do with the principle involved, and was only used to screen the construction from general observation. " This cylinder was proved w T ith repeated charges, varying from \ Ib. of powder and one round shot to 1^ Ib. of powder and two shots. The cylinder was simply laid on the ground with a slight elevation, its breech abutting against a massive stone wall, so as to prevent recoil. It stood the proof without injury, and the author, on the 19th June, 1855, addressed a letter to Lord Pan- mure, then Secretary of War, describing the experiments and the results, and offering the invention to the country." Mr. Longridge then describes its journey through the circumlo- cution office. It was finally tested in the absence of Mr. Long- ridge, and the following is the report of the Ordnance Select Committee : 97. "The gun was clamped on a block of o&k with iron clamps, and allowed to recoil on a wooden platform. Two rounds were fired, the first with a charge of 1 Ib. powder, 1 shot (fixed to wood bottom), and one wad over the shot : the recoil was 7 feet ; the gun was found to have slightly shifted its position on the block ; a trifling expansion of the wire had also taken place at the breech. " At the second round the gun was fired with 2 Ibs. of powder, 1 shot, and 1 wad, and burst : the separation took place about two inches in front of the base ring ; the breech was completely separated from the rest of the gun, and was blown 90 yards directly to the rear. The wire was unravelled to the length of three or four feet ; the brass cylinder burst in a peculiar manner, turning its ends upwards and outwards. It also opened slightly at the centre of the gun ; but the wire did not give way at that point. " The ordinary proof charge for a gun of this diameter would be IJlb., 1 shot, and 1 wad. " In order to try more particularly the effect of the wire in giving strength to the cylinder, this gun was, after bursting, sawn HOOPED GUNS. 69 in two at the centre, and one end of each portion was plugged with a brass plug, which was secured in its place by iron bands and several coils of wire : these guns were then secured to slides of wood as in the former instance ; they were placed opposite the proof butt, and that made from the breech end was loaded with \ Ib. powder and shot. It burst, the breech being blown out and the wire uncoiling to a considerable extent. " The muzzle portion was then loaded with a similar charge ; it did not burst, but was much shaken by the discharge, and por- tions of the iron bands gave way. It was then loaded with a charge of 1 Ib. of powder and 1 shot, which on discharge burst in two places, the breech being completely separated from the gun, and the slide on which it had been fired was rent into sev- eral pieces." Upon examination of the method of mounting the cylinder, Mr. Longridge found that the recoil was resisted by the ring around the muzzle ; in other words, that the gun was hung up by the muzzle-ring, and that the cylinder had not burst at all, but was torn asunder endwise by the recoil. The second " burstings" were merely the blowing out of the plugs. 98. This was enough for the Department, however, and Mr. Longridge, after repeated endeavors, could get no further trials. He then obtained possession of the fragments of his cylinder, and made the following experiments upon them. " A piece of the cylinder, about two feet long, was stripped of the wire, with the exception of two coils. It was then a brass tube 2 ft. long and J in. thick, with two coils of square steel wire, each T \ in. thick, making together J inch of brass, and 1 inch of wire. "In the middle of this he put l^lb. of Government cannon powder, and the ends were filled up with close-fitting wood plugs, fixed tightly with iron wedges. A trench 3 feet deep was then dug in stiff clay, and the cylinder was laid (it the bottom. At each end a railway sleeper was driven firmly into the clay, and the trench was then filled in with clay, well pounded with a heavy beater. The powder was then fired by means of a patent fuze. The wood plugs and sleepers were thrown out with great 70 ORDNANCE. violence, and a large mass of clay at each end was blown out; but the cylinder was uninjured. Determined, if possible, to burst it, the author next put in two pounds of powder, filled up the ends with close-fitting iron plugs, and bound the whole together with an iron strap of a sectional area of 5 square inches. The powder was then fired, and the iron strap was torn asunder, but the cylinder was uninjured, except at the ends, where, from the wire being imperfectly fastened, it uncoiled, and the cylinder was torn open. If the tensile force of the iron strap be taken at 18 tons per square inch, the force of the powder must have been above 13 tons per square inch, and yet this was resisted by J inch of brass and | inch of steel wire. The diametral strain must have been 39 tons, and taking the brass at 10 tons per square inch, it leaves 34 tons for the steel wire, which, divided over the two sides, or J inch, would give, for the ultimate resisting strength of the wire so employed, not less than 136 tons per square inch of section. This wire, it should be observed, was of the finest quality." Mr. Longridge then describes his second series of experiments made in March, 1856. Two sets of cylinders were prepared, for the following reasons ; 1st : 99. "Many of those to whom he had described the experi- ments above recorded, whilst admitting the great increase of strength obtained, were yet of opinion that it would be only prac- ticable to apply the wire, in combination with a metal of a soft, yielding nature, such as yellow brass, or pure copper. It was maintained, that it would be impossible to use the wire in combi- nation with cast-iron, owing to the assumed brittleness of that material, and it was objected that the soft brass, or copper, would soon be worn out by the action of the shot, and the guns be ren- dered useless." His views were different : " He looked on the inner shell simply as a means of confining the gases, and of transmitting the inter- nal pressure to the wire ; and knowing that cast iron would resist a crushing force of 40 tons, he was not afraid of subjecting it to a strain in a normal direction, which, at the outside, could not ex- HOOPED GUNS. 71 ceed the strength of powder, or 17 tons per square inch. But he was quite aware that no reasoning would suffice. Therefore, in his second series of experiments, he resolved to use cast iron alone, in its hardest form, as produced in a thin casting." 1OO. " As it might be desirable, for practical reasons, to sepa- rate the gun itself from the mass of material intended to absorb the recoil, Mr. Longridge wished to ascertain how far it was prac- ticable to transmit the force through a thin breech or diaphragm of a hard brittle substance, like cast iron, to a soft yielding mate- rial, like lead, and through it to the absorbing mass behind the breech. He did not expect to diminish the amount of recoil ma- terially, but to avoid those vibrations, which are so destructive between two hard metals in contact, and which always shake loose any system of bolting, or riveting, however perfect ori- ginally." " The first set of cylinders was intended to try the possibility of transmitting pressure, as just stated, through a thin diaphragm. The cylinders were of the dimensions shown in Fig. 53, in which FIG. 53. A is the powder-chamber ; B B, cast-iron plugs which were bound together by a heavy strap and key ; and C, the space filled up with a soft material, between the bottom of the powder-chamber and the plug B. The object was to ascertain whether the diaphragm at E would be shattered by the force of the explosion. Six cyl- inders were thus prepared, and loaded, and fired, with charges varying from 50 to 250 grains of Government cannon powder, the total contents of the cylinders being 310 grains. Table 15 gives the results. 72 ORDNANCE. TABLE XV. RESULTS OF EXPERIMENTS WITH WIRE-WOUND CYLINDERS. Cylinder. Wire. Charge. Kesults. Material behind the diaphragm. No. o. 2 coils. Grains. CO No effect Lead. CO Ditto. Ditto IOO Ditto Ditto. 12,0 Ditto Ditto I CO Burft Ditto " I. 4 coils I CO No effect Ditto. I go Ditto " 7 6 coils 180 No effect Ditto 200 Ditto Ditto. 220 Ditto Ditto 24.O Flange burft . Ditto " 6, 8 coils 24.O Ditto Ditto. " 8 8 coils No effect Gutta-percha 2 2O Burft Gutta-percha, softened by " No effect heat. Lead y- 2CO Flange burft " Iron wire, No. 21 wire gauge, or ^j inch diameter, was used. Its breaking strain was 60 Ibs. In no case was the bottom of the cylinder injured, except in the second experiment with cylinder No. 8, when the gutta-percha was softened by the heat of the first explosion." The lead transmitted the force perfectly in every case ; show- ing conclusively that there is no practical difficulty in transmit- ting the force through even so thin a diaphragm as T V of an inch, even when of so brittle a material as cast iron. After these ex- HOOPED GUNS. 73 FIG. 54. periments, Mr. Longridge states that he "needed no others to satisfy himself of the suitability of even very hard cast iron to transmit the force of gunpowder to wire, or any other absorbing material." As, however, other cylinders had been prepared, he proceeded to try their strength. 1O1. These cylinders are shown in Fig. 54. " They each contained 305 grains, when full to the plug. The plugs were made to fit accurately, and the powder was fired through a small vent, or touch-hole, not larger than a small pin. The results are given in Table 16. " In these experiments iron wire, No. 21 wire gauge, or ^V inch diameter, was used. Its breaking strain was 60 Ibs., consequently the actual strength of the material in the cylinder per lineal inch was: No. o. Caft iron o-io x 2 x tons = 1-76 tons. Nil. above 1-76 " ( Caft iron as ab ( Wire 4 x 28 x 2 x ^ j Caft iron ( Wire 8 x 28 > Same as No. 7 Same as No. 2. j Caft iron ( Wire 10 x 28 x 2 x 6-00 1.76 12-00 1-76 15 -oo I -76 tons. 7.76 13.76 13.76 7.76 16.76 "The enormous force of the expansive gases, in these experi- ments, was shown by their action on the plugs, which, although accurately fitted and of hard iron, were chiselled and grooved out in an extraordinary manner, as may be seen in one specimen ex- hibited. The vents, too, were rapidly enlarged." 1 02. The results, as regards strength, were so conclusive, that Mr. Longridge proceeded to construct a small gun (Fig. 55). This gun was 2'96 inches bore and 36 inches long in the clear ; it had on it twelve coils of No. 16 W. G. iron wire, at the breech, decreas- 74 ORDNANCE. TABLE XYI. RESULTS OF EXPERIMENTS WITH WIRE-WOUND CYLINDERS. No. of Cylinder. Wire. Charge. Results. Remarks. Grains. No. o. None. 40 No effea. Ditto. 5 Ditto. Ditto. 60 Ditto. Ditto. 70 Ditto. Ditto. 80 Burft. 2. 4 coils. 130 No effea. Ditto. 150 Flange burft. " 7- 8 coils. 200 No effea. A wrought-iron flange, in., contraaed on flange. Ditto. 220 Ditto. Ditto. 240 Ditto. Ditto. 250 Ditto. Ditto. 260 Ditto. Ditto. 270 Ditto. Ditto. 280 Ditto. Ditto. 2 9 Ditto. Hoop on flange fhifted " 5- 8 coils. 200 No effed. Ditto. 22O Ditto. Ditto. 2 3 Ditto. Ditto. ^.AO Flange cracked. " 4- 4 coils. *4*j 200 No effea. Ditto. 2CO Flange cracked. " 10. 10 coils. ^y 310 No effea. HOOPED GUNS. 75 FIG. 55. ing to four coils at the muzzle. The thickness of cast iron was | of an inch at the breech and \ inch at the muzzle. The gun was cast hollow, and a recess was left in the thick part of the breech, in which an india-rubber washer, inch thick, was placed. The trunnions formed no part of the gun, but consisted of a strap passing round the breech, with two side rods ex- tending about one-third of the length of the gun, and terminating in the trunnions themselves. Thus, the whole force of the recoil was transmitted through the heavy mass at the breech, then through the india- rubber, and along the side rods to the trunnions. The whole was then mounted on a wood carriage, on four roller wheels, about 8 inches diameter. The weight of the gun and w r rought-iron trunnion strap w r as 3 cwt., and the carriage 2 cwt. q. 15 Ibs., making a total of 5 cwt. q. 15 Ibs. The shot were cast as nearly the size of the bore as possible, so as to move freely, but with very little windage. The spheri- cal shot weighed 3f Ibs., and the conical shot from 6 to T| Ibs. Table 17 gives the results with 7 elevation, the powder used being Government cannon powder. 1OSI. These trials were only intended to be preliminary, but an accident similar in nature to that which destroyed Krupp's steel gun the breaking and wedging of the shot tore the gun asunder endwise, throwing the muzzle 15 yards forward, with the shot in it. But the wire, although uncoiled, was not broken. No farther experi- ments have been made with wire-wound guns. Longridge's experimental 2'96-in. wire-wound gun. 76 ORDNANCE. TABLE XYII. EXPERIMENTS WITH LONGRIDGE'S 2-96-ra. GUN, FIRING ON CAMBOIS SANDS, JUNE 4, 1856. No. Description of Shot. Weight. Charge of Powder. Bange to First Graze. 9 Round. Ibs. 3l 7 oz. II 1400 yards. 4 Elongated. H 7 II 1200 yards. 5 Ditto. 6 7 8 1 220 yards. 6 Ditto. 7* 7 ii 1542 yards. 8 Ditto. 7 7 ii Loft beyond 1500 yards. 8 Ditto. 7 7 16 Loft beyond 1800 yards. 10 Ditto. 61 7 16 1500 yards. ii Ditto. 61 7 16 Loft beyond 1800 yards. 1O4. Brooke' Hooped Gum. Figs. 56 and 57 represent the 7-in. cast-iron gun, hooped with wrought-iron rings, as fabri- cated by Mr. John M. Brooke, "Lt. C. S. Navy," at the Tredegar Works, Richmond, Virginia.* The other calibres are similar in design. The excellent quality of the cast-iron guns formerly made for the U. S. Government at the Tredegar Works, renders it probable that these guns, although slightly hooped, are capable of a considerable endurance. This class of gun is used with 14 Ibs. of powder and 80 Ib. shell. One gun is stated to have fired double charges without injury. The following are the particulars of the 7-in. guns : Total length 146-05 inches. Length of bore 119 -9 " Length of wrought-iron reinforce 30- " Length, muzzle to centre of trunnions 80-5 '* Length, centre of trunnions to forward end of reinforce 10-9 Diameter of bore 7- " Diameter of muzzle H'55 " Diameter of cylindrical part of cafting under reinforce 27-2 Diameter over reinforce 31 -2 1O5. The rifling consists of 7 grooves (Fig. 58) T V in. deep, very * The engravings were reduced, by the author, from official drawings in London. HOOPED GUNS. 77 FIG. 58. u FIG. 57. FIG. 56. Rifling of Brooke's 7 -in. gun. slightly rounded at the corners, with 1 turn in 40 feet. The grooves vanish as they approach the chamber. 1O6. A ttick's Bronze Rein- force. The present rifled gun of the Stevens gunboat Nauga- tuck* was fabricated by the Ames Manufacturing Co., Chicopee, Mass., and is shown by Fig. 59. It is an old cast-iron 42-pounder with a " composition" hoop forced on by hydrostatic pressure. The exact material of the hoop is not made public. The inventors have since made a bronze said to have a tensile strength of 80,000 Ibs. per square inch. This gun has been tried with 100 Ib. projectiles (James's) and 16 Ib. charges. The The Naugatuck is illustrated in another chapter. 78 ORDNANCE. service charge is 14 Ibs. No test of the gun has been made, and the vessel has not been in action since receiving it; but its endurance can hardly be assured from the results of similar experiments in Eng- land. (See Table 13.)* 107. Atwatcr' Ouii. A 5*85-in. (80-pounder) hooped gun, experimented with at the Washington Navy Yard, is rather remarkable in its ri- fling, which will be farther mentioned. It is a cast-iron gun, 21 in. diameter at the breech, with a tier of 6 wrought- iron hoops 6 x 2 in. each, shrunk on, and a second tier of 5 simi- lar hoops over the first tier. Length of bore, 12 ft. ; weight, 11,625 Ibs. 108. The 13-Inch Bum- ford Gun. A somewhat cele- brated gun cast at South Boston in 1846, and thus designated from the name of its designer, is illustrated by Fig. 60. It is a 12-in. smooth-bore of 134 in. total length, 116*2 in. length of bore and chamber, 88*2 in. diameter over the chamber, and 25,510 Ibs. weight. Before it was hooped, the greatest en- largement of the chamber with 20, 25, and 28 Ibs. powder and * Since the above was written, this gun burst after a short service. HOOPED GUNS. 79 80 ORDNANCE. a 150 Ib. shell, after 93 fires, was '005 in., and the greatest en- largement at the lodgment of the shell, '074 in. The maximum range in ricochet fire, with 181 Ib. shell and 28 Ibs. powder, was 5800 yards. This gun was hooped in 1862 with wrought-iron rings, about 1 inch wide each, making a reinforce 31f in. long, 4 in. thick, and 46 in. in total diameter. The gun has not been put into service. 1O9. JlallelN Wrought-iron 36-Inch Mortar. The mon- ster mortar, Fig. 61, consists of wrought-iron hoops shrunk FIG. 6L Mallet's 36-inch wrought-iron mortar. together with definite initial tension. It is made in 6 sections (so as to be transportable), which are fitted gas-tight, with rab- beted joints, and bound together by 6 staves. The chase is 2-J calibres long. The chamber is a solid forging, set in a cast-iron base of 11 tons weight. The total weight of the piece is 113533 Ibs., or about 52 tons. Its cost is stated at 14000. It was completed in 1857, and is now mounted at the Woolwich Arsenal. The chamber and barrel are in good condition, although one of the bolts connecting the muzzle with the base is broken, after limited practice;* the mortar is generally considered a failure. * Mr. Mallet has stated that this could be repaired for 30. WROUGHT IRON GUNS. 81 The practice with 36-in. shells will be given in another chapter. The mortar has fired shells of 2481 Ibs. weight, holding a 480 Ib. bursting charge, above 2 miles, with 80 Ibs. of powder. SECTION II. SOLID WKOUGHT-!RON GUNS. HO. I. The Mersey Steel and Iron o.' Oun. THE HOKSFALL GUN. The most remarkable piece of this manufacture is the "Horsfall Gun" (Figs. 62, 63), fabricated in 1856, and recently made famous in target practice at Shoeburyness. FABRICATION. This gun is a solid forging of wrought iron, bored out. The trunnions are forged upon a separate ring, which is held in place by a key, as shown in the engraving. 111. The s dimensions of the gun are : Length, 15 feet 10 in. ; diameter over chamber, 3 feet T in. ; length of bore, 13 feet 4 in. ; diameter of bore,* 13-014 in. The weight* is 53846 Ibs. 2'21 oz. The usual windage is *2 in. The gun is not rifled. 1 1 2. The mass of forged iron in the rough, was a rude conic frustum, about 17 feet in length, rather more than 4 feet in diameter at the breech end, and above 3 feet at the other. " Puddled rough bars were made from the best selected Scotch and North Wales pig-iron, and were worked as little as possible before being sent to the forging department. The puddle balls were hammered, then rolled into No. 1 bar iron, and that was cut up, piled, and again rolled into No. 2 bars. * * * A core, formed of a fagot of square bars, was first welded up and rounded to about 15 in. diameter. Upon this, three several coats or piles of Y-shaped or voussoir bars were laid on, and welded in succession ; so that the fagots might finally be supposed to have a section something like that shown in Fig. 64. The extreme diameter of the breech end was produced by welding slabs over these again, where the mass exceeded 32 inches in diameter. "f The forging was done under a " 15-ton" hammer, and the heating in a rever- * Report of Ordnance Select Committee, Feb. 5, 1857. \ "On the coefficients of elasticity and rupture in massive forgings." MALLET. Insl Civil Engineers, March, 1859. 6 82 ORDNANCE. FIG. 62. WROUGHT IRON GUNS. 83 C4. Section of pile of Horsfall gun. beratory furnace. Fifty tons of iron were used, and the process occupied seven weeks. 113. ENDURANCE. Above 8000 Ibs. of powder, and 60000 Ibs. of 282 Ib. solid shot have been fired from this gun at various rounds; among others, there have been 90 rounds with 50 Ibs. of powder, 21 rounds with 40 Ibs., and 6 rounds with 50 Ibs., at Shoe- buryness; 2 rounds with 80 Ibs., at Liverpool; 13 rounds with 20 to 45 Ibs., and 40 rounds with 30 Ibs. With 45 Ibs. of powder, a number of shell were fired loaded with lead to weigh 310 and 318 Ibs. The unequal shrinkage of the solid breech of this gun, during its fabrication, caused a crack, which was afterwards covered with a breech-plug or false bottom in the chamber, to prevent the lodg- ment of any burning material. The defects of the gun, before the experiments of 1862, were stated as follows, in the report of the Inspector of Artillery :* " A plug (8'4 in. diameter) is inserted in the bottom of the bore (driven back '05 in. after the experiment of the 16th of Septem- ber, 1862). "Right. A hole, 1*8 in. long, "65 in. wide, and 13*75 in. deep, extends from the edge of the plug; another, 1*5 in. from the edge of the plug, is '55 in. long, *25 in. wide, and '2 in. deep. "Left. A hole from the edge of the plug, *5 in. long, '5 in. wide, and 3'75 in. deep; another, 1-5 in. from the edge of the plug, *8 in. long, '3 in. wide, and 5*75 in. deep. (Dimensions of this flaw, after the experiments of 16th of September, '65 in. long, 35 in. wide, and 6'5 in. deep.) "Left of Down. One hole at the end of the bore '5 in. long, 15 in. wide, and *1 in. deep. * British Artillery Records, 1862. 84 ORDNANCE. " In the bottom of the bore a flaw commences at the edge of the plug, about -2 in. wide and '2 in. deep at the largest part, and ex- tends 25 inches along the bore (this flaw has slightly increased in size). " In addition to these flaws, small longitudinal fissures, such as are usually found in wrought-iron ordnance, are visible all round the bore at 35 inches from the breech." 114. After the gun had endured these tests, and had been pre- sented to the British Government by the makers, it was left un- protected on the beach at Portsmouth. By renewed exertions, the Mersey Company at last obtained permission to fire it at the Warrior target. It was found nearly buried with shingle and much injured by rust. Having been taken to Shoeburyness, it fired several rounds of 282 Ib. shot with 74 Ibs. of powder, with terrific effect at short range. (Tables 28 and 31.) The cost of such guns, in England, would be about $12500. 115. The Prince Alfred Gun,* Fig. 65, shown in the Great Exhibition of 1862, was forged hollow, on a plan patented by Lt.-Col. Clay, of the Mersey Iron Works, and intended principally to overcome the defect of unequal shrinkage and initial strain and rupture (429). Broad plates, bent to the proper curve, were laid and welded upon a barrel made of rolled staves. 116. Its dimensions are : length (without cascable), 151 in. ; length of bore, 137 in. ; diameter over chamber, 31f in. ; diame- ter at muzzle, 14]- in. ; diameter of bore, 10 in. ; weight, 24094 Ibs. The gun is rifled on a plan intended to be Commander Scott's, with 3 grooves J in. deep, but cut the wrong way, so that the pro- jectile would be rotated by the inclined instead of the radial sur- face of the grooves. It will therefore have to be bored out to 10 J in., and will then carry a 156 Ib. spherical shot. 117. This gun has been fired but twice, and then as a smooth- bore ; 1st, wifti a 140 Ib. shot and 20 Ibs. of powder, and 2d, with the same shot and 30 Ibs. of powder. The test proposed by the makers is 1 round with 1 shot and 100 Ibs. of powder. The price of this gun is $5000 in England. * The Prince Alfred Gun has recently been purchased by Captain Blakely. WROUGHT IRON GUNS. 85 FIG. G5. Fm. 66. The "Prince Alfred" 10-in. wrought-iron hollow-forged gun. Scale, -ft in. to 1 ft. The Mersey 12-inch gun in the Brooklyn Navy Yard. Scale, -fr in. to 1 ft. 86 ORDNANCE. 118. Brooklyn Navy Yard Gun. The 12-in. wrought-iron gun, in the Brooklyn Navy Yard, Fig. 66, was forged like the Horsfall gun, by the Mersey Iron Works, in 1845, to replace the Stockton gun. Its dimensions are : total length, 14 feet 1 in. ; diameter over the chamber, 28 in. ; length of bore, 12 feet ; diam- eter of bore, 12 in. ; weight, 16700 Ibs. It was received after the bursting of the Stockton gun, of which it is a copy, in shape, and has never been mounted for service. It has been fired once with two 224 Ib. shot and 45 Ibs. of powder. 119. A 6-lNCH WROUGHT-IRON SMOOTH-BORE GUN, made at these works for the Russian Government, stood a 300 Ib. elongated projectile and 16 Ibs. of powder. The metal of the chamber was compressed, but no other damage was done. 120. The Mersey Works have also constructed several experi- mental wrought-iron guns by the rolling process. One of these, 2 inches bore, was fired with 22 balls and a cylinder projecting 12 inches from the muzzle ; charge, l Ibs.* 121. THE BRITISH GOVERNMENT has ordered several guns of 6 inches bore, to be forged hollow, like the Alfred gun. One of these, weighing 9282 Ibs., was fired 10 rounds with a 68 Ib. 10 oz. shot ; 10 rounds with a 136 Ib. 8 oz. shot ; 10 with a 204 Ib. shot ; 10 with a 273 Ib. shot; 10 with 340 Ib. 8 oz. shot; 10 with 410 Ib. shot ; and 10 with a 476 Ib. shot. At the 70th round the gun burst into eight pieces. Subsequent experiments on the metal gave a tensile strength of 45359 Ibs. per sq. inch. 122. Another block, forged to the shape of the Armstrong 12- pounder, and rifled and fitted as a 12-pounder, was subjected to the usual proof, but exhibited in the chamber " holes and dents to an extent which, if taking place in an Armstrong gun, would not be passed for service, "f A 40-pounder block, forged from the same iron, and finished like the Armstrong 40-pounder, was " fired 100 rounds with the service charge of 5 Ibs., and cylinders increas- ing in weight from 40 Ibs. to 400 Ibs ; also 17 rounds with the * Col. Clay. Construction of Artillery, Inst. C. E., 1860. f Report of Select Committee on Ordnance, 1863. WROUGHT IRON GUNS. 87 double service charge, viz., 10 Ibs., and with, the 40-pounder ser- vice shot; total, 117 rounds. The result is, that the bore is deeply fissured all round, from 75 in. from the muzzle to the breech end of the powder chamber. The powder and shot cham- bers are also expanded."* This expansion was '068 in. maxi- mum, in diameter, at the powder-chamber, and '374 in. maximum at the shot-chamber. 123. The committee, however, say, that "both these guns have shown an endurance, if not fully equal to guns made on the coil system, yet at least ample for the requirements of the service, if it is accompanied by the power of resisting a very great number of service charges ;" and in a subsequent report, that by the em- ployment of the Mersey blocks instead of the Armstrong coil, " a saving in the cost of manufacture will be effected to the extent of about 74 ($370) per 40-pounder gun, and 15 ($75) per 12- pounder gun."* 124. II. The Stockton Guns. Three 12-inch wrought-iron guns were made some years since, under the direction of Commo- dore Stockton, for the U. S. Government. They are all illustra- ted by Fig. 66. 1 25. The first, called the " Oregon" gun, was forged in Eng- land. After considerable use with charges of 20 to 30 Ibs. of powder and 216-lb. balls, it cracked through the reinforce, but was hooped and fired afterwards without injury. This gun is now in the Navy Yard at Philadelphia. 126. The "Peacemaker" was forged in the United States, by Messrs. Ward & Co. The greater part of the iron was in 4-in. bars, 8-J ft. long. Of these, 30 were laid up in a fagot, welded, and rounded into a shaft 20 to 21 in. in diameter. Iron in the form of segments, varying in weight from 200 to 800 Ibs., and usually large enough to reach round the gun, was welded on, there being two strata of segments over the breech. The hammer used weighed 15000 Ibs. The time occupied in the forging, during which the iron was kept more or less highly heated, was * Report of Select Committee on Ordnance, 1863. 88 ORDNANCE. FIG. 67. 45 J days. This gun burst on board the U. S. steamer Princeton, after a few discharges.* The third Stockton wrought-iron gun is the Mersey Iron Works' gun, already described. (118.) 127. III. ?Ii*ccll;meous Solid Wrought-iron Guns. LYNALL THOMAS'S 7-iNCH GUN. Although there are many field- pieces composed of wrought iron piled and treated in various ways, no heavy ordnance than that described above has been fabricated, excepting Mr. Lynall Thomas's 7-inch gun, which recently burst at Shoeburyness. This gun was rolled, by Messrs. Morrison and Co., Newcastle, into a tube, from a plate of inch iron, as illustrated by Fig. 67. There were 14 or 15 layers of plate forged into a mass over an internal cast steel tube. Over the breech were two hoops, 13 inches long by 3 inches thick. Length of gun, 11 ft. 6 in. ; total diameter, 26 in. It was rilled with 3 projecting ribs, 1^ in. wide each, the diameters of the bore being 7 and 6-6 in. The gun Lynall Thomas's 7-inch gun mode of , . . . , , T , . fabrication burst in tiring at the Inglis tar- get, on Dec. 29, 1862, at the second round, with a 27^-lb. charge and a 138-lb. shot.f THE NEW ERICSSON GUN. Two 13-inch guns, designed by Mr. Ericsson;); as a part of the armament of the iron-clads Puritan and Dictator, are nearly completed. The gun is a solid wrought- iron barrel, forged from a very superior iron (specially tested for * An abstract of the report of the Committee of the Franklin Institute on the con- dition of this gun will be found in a following chapter. (426.) f This process of manufacture will be further described under the head of " Wrought Iron. ; ' (430.) \ Capt. Ericsson "is to receive nothing for these guns, unless they burn over 50 Ibs. of powder. * * * He is confident of being able to burn 100 Ibs." Army and Navy Journal, Sept. 26, 1863. WROUGHT-lRON GUNS. 89 the purpose), at Bridgewater, Mass., and reinforced with, a series of thin washers, forced on with accurately determined tension by hydrostatic pressure. Upon the end of the breech is forged a solid flange, against which the washers abut. The washers are cut out of f-in. boiler plate, and extend forward to the middle of the chase, where a nut, embracing and screwed upon the chase, presses them against the solid flange, and into close contact with each other. The following are the particulars of this gun : Ft. Ins. Length, total ........................................................................ ^ ......... 12, 8 Length of reinforce of wafhers ........................................... ................ 8 Length of maximum diameter .............................................................. 3 6 Diameter, maximum ......................................................................... 3 II Diameter of muzzle ......................... ............................................ I 10 Diameter of bore .............................. ............................................. I I Diameter of barrel under reinforce ......................................................... a 4^ Thicknefs of hoops or wafhers .............................................................. f Thicknefs of walls of barrel ................................................................. yf- Total thicknefs of wall of gun .............................................................. I 5 Weight .................................................................................... 47000 Ibs. . AMES'S WROUGHT-!RON GUN. Mr. Horatio Ames, of Salis- bury, Conn., has forged several experimental cannon of 6 in. bore, out of the celebrated Salisbury iron, by a new process of his own. A slab 10 in. square and six inches thick, piled and hammered in the usual way, and rounded and turned to form a short cylinder, receives a 3-in. hole in the middle, and a welded ring, 6 x 6 in. in section, is shrunk upon the outside. The disk thus made is welded to a mass of iron, forged on the end of the staff by a hori- zontal steam-hammer equivalent to an ordinary 6-ton hammer. Other disks are thus welded to the first, till the requisite length is> attained. The gun is also hammered by an upright 6-ton steam- hammer. A pin is driven through the hole in each disk, after it is welded on, into the corresponding hole in the next disk, to open and preserve the line of the bore. The forcing is upset to two- thirds of its original length, and increased in diameter two inches. The shape of the gun is that of the Dahlgren 50-pounder (Fig. 68). The trunnions are put on with Dahlgren's breech-strap (305). 90 ORDNANCE. 129. One of these guns was fired 1630 times with a 37-lb. rifle shot and 3J Ibs. of powder the service charge. Another FIG. 68. Ames's wrought-iron 50-pounder. Scale, -fc in. to 1 ft. gun of the same dimensions was bored out to 8-in. calibre, and fired 438 times with the 80-pounder service charge a 67-lb. rifle shot and 5 Ibs. of powder without bursting. Other guns have been subjected to very severe tests at the works. The chambers of these guns show some stretching at the welds, but it is not cer- tain that there are serious flaws. The manufacture is, of course, not fully developed.* SECTION III. SOLID STEEL Guxs.f 130. Krupp' Ouii. The mild steel made by Mr. Fried. Krupp, at Essen, Prussia, is probably more remarkable than any other product of this nature, chiefly on account of the immense size of the solid masses produced. Mr. Krupp- s cannon are, indeed, the only solid steel guns that have acquired a special celebrity, although it is probable that some of the Sheffield manufacturers make an equally good material, and will soon produce ingots of equal size. The first of Mr. Krupp's guns was the one in the Great Exhibition of 1851. Mr. Krupp patented this application of steel to ordnance in England, on Dec. 17, 1861. 131. MANUFACTURE. The great feature of the manufacture is * It is stated that Mr. Ames is now forging fifteen guns of 15-inch calibre for the United States Government. f The nature and manufacture of steel by different processes will be considered under the head of " Cannon Metals." STEEL GUNS. 91 92 ORDNANCE. the forging of large masses from single homogeneous ingots, without seams or welds. An ingot of 21 tons weight, and 44 in. diameter, was shown at the Great Exhibition of 1862. Similar castings are forged every day into shafts, cannon, etc. The head of Krupp's heaviest hammer is said to weigh 40 tons.* 132. Figs. 69 and 70 represent the 9-inch gun shown in the Exhibition of 1862. It was at that time the largest cannon forged at this establishment, and by far the largest gun ever forged with- out welds. It was intended for a Krupp breech-loader, but is adapted to other plans of breech-loading or to conversion into a muzzle-loader by the simple insertion of a breech-plug. It is a smooth-bore, and was intended for a 200-pounder to 250-pounder rifle. Its dimensions are : total length, 13 ft. 8-J- in. ; diameter over chamber, 27f in. ; diameter at muzzle, 15J in. ; diameter of bore, 9 in. ; weight, 18000 Ibs. ; price, $10125. 133. The other large Krupp guns in the exhibition were an 8'12-in. gun, weighing 8365 Ibs., and a 7-in. gun, weighing 7709 Ibs. Artillery of smaller calibres, especially for field-service, has been made at this establishment, in great quantities, for the Prus- sian, French, Belgian, Austrian, Russian, Egyptian, Swiss, Dutch, Bavarian, Norwegian, and other governments, all of which has given entire satisfaction. 134. Mr. Krupp is now making a large number of solid-steel guns for Russia ;f among them fifty 9-in. guns (Fig. 71), of 18480 Ibs. weight and 15 ft. length of bore, and a larger number of 8-in. guns, of 16800 Ibs. weight and 13 ft. 2 in. length of bore, and of 6-in. guns of 8900 Ibs. weight and 10 ft. 8 in. length of bore. * In a circular dated January, 1861, Mr. Krupp says that the capabilities of the works admit of a daily production of 18 blocks (not bored), suitable for guns of 3'00-in. bore, or 12 " " " " 3-50 " or 8 " " " " 4-50 " or 4 " " " " 5-75 " or 2 " " " " 8-00 " or half these numbers of finished guns, turned, bored, and rifled. f In addition to these, the Kussian government has made extensive preparations, at enormous cost, to produce steel guns in Russia, and has ordered a large number of steel and other hooped guns from Captain Blakely. STEEL GUNS. They are all muzzle-loaders, of the form shown by Fig. 71, and rifled on the shunt plan.* Mr. Krupp is also mak- ing for Russia several 11-in. guns, fitted with his own plan of breech-loading ap- paratus, which will be described in an- other chapter ; and, it is stated, though not officially, several 15-in. guns, at a cost of 87 cents per pound, f The experiments on armor-plates, with the 9-in. steel guns, at St. Peters- burg, will be referred to tinder that head. 135. ENDURANCE. The British Government has also experimented with Krupp's guns of various calibres. The most severe test to which the metal has been subjected, occurred at Woolwich, in 1862-3. Three guns were furnished by Mr. Krupp, upon his own system of breech-loading, and at his own expense, viz., a 20-pounder, a 40-pound- er, and a 110-pounder, of 3*75, 4*75, and 7 inches bore, respectively. They were all rifled upon the Armstrong multi- groove system, with 4-i, 56, and 76 grooves respectively, and fired with Armstrong compressing projectiles, which is a rather severe test in itself. The proof is recorded in Tables 19, 20, and 21. * The rifling of the 9-inch guns, a number of which were delivered in the autumn of 186.'], will be illustrated in another chapter. f The following circular has been issued by Mr. Krupp : (See next four pages.) 93 94 ORDNANCE. 136. The first of the 9-iii. guns supplied to the Russian gov- ernment* is reported to have fired TO rounds of 300-lb. shells with 50 Ibs. of powder, up to the close of the armor-plate experiments of October 17, 1863, and to have even fired several shots through 5^-in. plates without exhibiting any deterioration. Meanwhile, CAST-STEEL WORKS, NEAK ESSEN, KUENISII PKUSSIA, January, 1861. On distributing the enclosed Price List for Cast-Steel Guns, I beg to furnish the following extract from a pamphlet by Dr. H. Scheffler, entitled " Elastic Proportions of Barrels, Tubes, etc." (Kreidel and Niedner, Wiesbaden, 1859), particularly referring to guns, and the rules laid down therein; directing, also, to my works for reply to questions relative thereto. FRIEDR. KRUPP. The author (Dr. Scheffler) confirms the rule of Lame as being correct for calculating the thickness of metals for cylindrical tubes Stating by b the thickness of metal ; r the interior radius of the tube; p the interior pressure of the gun per square inch; f the absolute resistance of the metal; n the coefficient of safety; 1 f = s, the greatest tension to which the material can be strained at the most dangerous part, viz., the interior surface of the gun, and neglecting the pressure acting upon the gun from the exterior, which will not be sensibly felt on guns, hydraulic cylinders, etc., where the exterior atmospheric pres- sure, compared with that in the interior, is so slight; thus Lame's Formula furnishes a corresponding proportion of the thickness of metal and interior radius of the tube the value: = r r=i~ : V -i if-P The tube will therefore burst from the pressure p, as soon as s = f (and of course n=l). This formula contains this most important result for practice, that there exists for every material a highest amount of interior pressure, which cannot be exceeded; and this highest amount of pressure, at which the gun will burst, however great may be its thick- ness of metal, is p = f, that is, equal to the absolute resistance of the metal. Supposing, then, the absolute resistance of f to be of cast iron 19000 Ibs. per square inch, " bronze metal 34000 " " " " cast steel 120000 " " " * The statement in the English journals of November, that the first 9-in. gun had burst, is contradicted by Mr. Krupp's agent, in the Times of November 30, 18C3. STEEL GUNS. 95 the 7-in. wrought-iron gun, built on the Armstrong plan, and rifled on the Whitworth plan, which has also thrown shells through armor, requires repairs, from the indentation of the bore, after less than 30 rounds. and calculating the pressure of one atmosphere = 15 Ibs. per square inch, a gun will certainly burst when the interior pressure becomes greater than: with cast iron = 1266 atmospheres 15 bronze = 2266 15 cast steel 12QOO = 8000 15 Following Lame's rule, supposing the thickness of metal to be given as b, or the oportion , it results for the greatest tension s, per s has to sustain under the interior pressure, the expression proportion , it results for the greatest tension s, per square inch, which the metal - 1 from which, the absolute resistance of cast steel being about six times as great as that of cast iron, and three and a half times as that of bronze metal, it results, that with the same diameter and thickness of metal, and with the same interior pressure, a CAST- STEEL GUN warrants a safety against bursting of six times greater than a cast-iron gun, and three and a half times greater than a bronze metal gun. If, for instance, the gun shall be subjected to an interior pressure of 1000 atmo- spheres, that is, p = 15000 pounds per square inch, it results: for b ER RIFLE. BORE 4-75 IN. WOOLWICH, FEB., 1863. No. of rounds. Weight of charge. Weight of shot. Remarks. I 6 Ibs. 12 oz. 40 Ibs. " Developing round." 2, 10 Ibs. 40 " Proof rounds." 4 6 Ibs. 12 oz, 40 "Developing rounds." 10 5 Ibs. 40 ' 10 5 Ibs. 80 10 5 Ibs. 120 " 10 5 Ibs. 1 60 " 100 rounds "Destructive proof.'* 10 10 10 5 Ibs. 5 Ibs. 5 Ibs. 200 " 240 " 280 " The projectiles were cylinders with a > leaded base to take the rifling. Length of cylinder, last 10 rounds, 7 ft. 7 in. 10 5 Ibs. 3 20 10 5 Ibs. 360 " 10 5 Ibs. 400 " The gun was not injured in the above proof. to fire 20 charges of 3t (G'G Ibs.) with 2 balls. The piece resisted very well the first three fires, showing no wear nor the least fissure that could indicate an approaching rupture ; but at the fourth fire it burst into a great number of pieces, several of which were thrown to a distance of 150 metres (500 feet), and nearly all were found. Two other guns of the same (121 millimetres, or 4'84 in.) calibre were delivered rough forged, and finished at Strasburg, to the interior and exterior dimensions of a 12-pounder. The star-gauge showed a variation in the bore of only ^ of a millimetre. "The weight of the pieces was about the same 551 k (1212'2 Ibs.) for one, and 550 k (1210 Ibs.) for the other." EXPERIMENTS. First Series. " The two pieces, placed on light 1 2-pounder carriages with strengthened cheeks, were put in battery at 600 metres (1968 feet) from the tar- get. They were aimed point-blank, and fired each 3000 times with I k 400 (3 Ibs.) of powder. The weight of the charges was verified, as well as the mean range of the powder, which was 225 metres (737 feet). The trials were made twice each day; and at each trial each piece was fired fifty times. After each trial, the pieces being sponged and cleaned as well as possible, an examination was made of the state of the vents, that of the pieces, and the damage sustained by the carriages. " The pieces suffered a considerable recoil, which was limited by means of fascines placed in the direction of the recoil. There was also a great pounding of the breech STEEL GUNS. 101 upon the sighting-screw ; and to this may be ascribed the breakage of several screws, which had to be replaced during the trials. This pounding was due to the too slight preponderance of the breech relative to the 12-lb. balls which were fired. After 200 discharges of each piece they were examined anew by means of the star-gauge, and each examination showed that the bore had not suffered any injury. The state of the vents was also perfect. The carriages did not begin to fail until after 500 discharges. That of No. 1 having had its trail broken, it was removed, and replaced by one nearly new. The firing was continued during the following trials without any result requir- ing particular notice. Eacli piece was examined after each series of 200 discharges ; and each examination showed an absolute resistance of the steel ; for it was impos- sible to discover the least alteration, either with the naked eye or with the aid of the star-gauge ; the bore remained always polished, and resumed its brightness when sufficiently cleaned. * * * * In this way 1400 rounds were fired with the same powder without producing the least alteration in the pieces. * * * In the following trials there were no injuries except to the carriages, some of which were so great as to put these carriages out of service, and it was necessary to replace them. * * * The firing was continued to the end without producing the least alteration in the in- terior or exterior of the two pieces. When they had been fired 3000 times each, they were examined by the star-gauge. A comparison of the interior diameters found by this test with the measures taken before the trials, showed but an inappreciable differ- ence; the calibre remained 121 millimetres (4*84 inches) through the whole length of the bore ; and the difference detected by the instrument, - 2 of a millimetre at most, is so small that it may be said, without error, that after the firing the bores of the two pieces were identically the same as they were before its commencement. " This first series of tests is therefore altogether favorable to cast steel, and demon- strates its absolute resistance to the diverse causes of degradation of the bore in ordi- nary firing. "Second Series. This series was for the purpose of ascertaining if cast steel would resist the enemy's shot as well as bronze does. The gun No. 2 was fired at by a 12- pounder field-gun with the ordinary service charge. It was placed horizontally upon blocks at a distance of about 100 metres (328 feet), with its muzzle turned towards the gun which was to fire at it, the axes of the two pieces being in the same vertical plane. * * * The first shot struck on the muzzle, knocking off a piece about a quarter of the circumference, and battering inward a burr to the extent of nearly an inch, which would prevent the insertion of a ball. The effect would have been the same on a bronze gun. The second ball hit exactly in the same place, increasing the effect of the first, and, in addition, producing deep irregular fissures all around the muzzle, ex- tending to the neck. The piece was then placed so that the trunnions were vertical; one of them was struck fairly and knocked off by the ball. It would have been the same with a bronze trunnion. The shot having struck fairly, the shock caused the muzzle to fall off, the fissures having nearly detached it. "The gun was then placed across the line of fire, and re- FIG. 72. ceived five balls in its broadside. These balls all struck fairly, and produced indentations of about a third of the diameter of the ball in depth (Fig. 72), and ragged projections inside the bore. * * * On examining closely the fragments, it was seen that the fracture presented everywhere a fine grain, quite homogeneous, and of a regular brilliant and saccharoid crys- tallization. In the open air the fractured surfaces oxydized. but much more slowly than the surfaces of wrought or cast (See page 103.) 102 ORDNANCE. FIG. 74. Krupp's gun (Fia. 73) after fracture. 138. Fig. 73 represents an 8-in. gun. designed for a 68- pounder, and mounted in a cast-iron jacket. The jacket did not touch the chamber nor impart any strength to it, but was added for weight. The walls were from 4 to 4v} in. thick. The gun was burst at Woolwich, with 25 Ibs. of pow- der and a 259-lb. shot. Fig. 74: explains the cause of the disaster. The shot had a wrought-iron ring, V-shaped in section, fitted upon its end. When the explosion of the powder took place, this ring was broken, and was forced along the body of the shot, cutting up the cast iron to the extent of from 6 to 8 inches. The pieces of the shot thus cut STEEL GUNS. 103 off, together with the broken ring, completely wedged the shot into the gun at the point shown. The shot was not forced out of the gun, but was carried, with the muzzle, to the proof-butt, and was here jerked out of the broken end and thrown some distance forward.* The steel was afterwards found to have a tensile strength of 72000 Ibs. per square inch. 1^9. A 12-pounder, sent by Mr. Krupp to Woolwich for test, was filled to the muzzle with powder, shot, and broken shells, but could not be burst, and was returned with the cascable knocked off, the gun having been thrown high in the air by the force of the explosion, f 14O. Mr. Krupp expresses his readiness to fabricate 13 or 15- inch guns, and states that there are now no mechanical difficulties in iron. * * * This second series therefore proves that cast steel is neither better nor worse than bronze, but is much better than cast iron to withstand the effect of shot. " Tliird Series. To find the extreme limit of resistance of cast-steel cannon, No. 1 was tested with extra charges, in the following progression: 20 rounds with 3k ( 6-6 Ibs.) powder and 2 balls. 10 " " 3k ( 6-6 " ) " "3 " 5 " " 6k (13-2 " ) "6 " and it was intended to continue the firing until it bursted, using 12 k (26'4 Ibs.) pow- der, and as many balls as the barrel would admit. "After each fire the state of the bore and of the exterior surface were examined: the test with the star-gauge after the 20 fires showed that the bore was uninjured. In the next trial, 10 rounds with 3 balls, the gun resisted perfectly; only a slight en- largement of the vent was observed. Finally, 5 rounds with 6 balls were fired ; the powder occupying 80 centimetres (32 in.) of the bore, and the balls occupying 70 cen- timetres (28 in.), so that the bore was filled within 30 centimetres (12 in.) with pow- der and balls. The explosion produced by these fires was enormous; the balls broke against each other in a thousand pieces; and the recoil of the gun was arrested only by the gabionade constructed in the rear; and the gun was buried in the ground so deeply that great labor was required to get it out, and replace it on the timbers after each fire. The gun was again examined after the five shots, and found to have resisted perfectly, the bore not having suffered the least deterioration. "Preparations were made to fire with 12 k (26'41bs.) powder and as many balls as possible, when an order was received to stop the test, and not to burst the gun: it would, in fact, have been a misfortune t j destroy a piece that had so well borne these severe tests." The report concludes by recommending a substitution of cast steel for bronze, espe- cially for rifled cannon. * A similar accident occurred to one of Mr. Longridge's wire-bound guns, known to be excessively strong. (103.) f "Construction of Artillery, " Inst. C. E., 1860. 104 ORDNANCE. the way. The breech of muzzle-loaders of any size would be left solid, as the gun would be forged in the shape of a cylinder, and bored out. It may be remarked, that the weight of forged masses of a given quality has been increased nearly 10 times within a de- cade. Mr. Krupp sent a 5000-lb. block to the Exhibition of 1851, and one of above 44000 Ibs. to the Exhibition of 1862. 141. Bessemer Steel Guns. The Bessemer process of making steel direct from the ore, or from pig-iron, promises to ameliorate the whole subject of Ordnance and engineering construction in general, both as to quality and cost. This product has not yet been used for guns to any great extent, although Mr. Krupp, the leading steel maker, has introduced it. Captain Blakely and Mr. Whitworth have also experimented with it, and expressed their faith in its ultimate adoption. Messrs. John Brown & Co., Sheffield, have made over 100 gun-forgings, some of them weighing above 3 tons, from solid ingots of this steel. During the present year, their production of Bessemer steel will exceed 400 tons per week. With the two new converting vessels then in operation, solid ingots of 20 tons weight can be fabricated. A large establishment about to be started in London, with a 50-ton hammer, and a capacity to pour 30-ton ingots, will afford the best possible facilities for the development of this process. 142. The pig-iron is run into a converting vessel, where it receives a blast of air for 15 or 20 minutes, to burn out the car- bon and silicium. It is then cast into an ingot, which is heated / O ' and forged into a gun.* 143. The piece shown at Fig. 75 was made for the Belgian Government, quite early in Mr. Bessemer's practice. Its dimen- sions were: length of bore, 7 feet; diameter of bore, 4'75 in.; maximum diameter, 9'5 in.; thickness of walls, 2*37 in.; weight, 1070 Ibs. a very light gun. The test was 3 rounds with 2 spheri- cal shot, 3 rounds with 3 shot, 3 rounds with 4 shot, 3 rounds with 5 shot, 3 rounds with 6 shot, 3 rounds with 7 shot, and 2 rounds with 8 shot, the powder being 2*2 Ibs. in each case, when the gun * See chapter on ''Cannon Metals Steel." STEEL GUNS. 105 broke in the chase, 39 inches from the muzzle, from FI G. V; the wedging of the shot. There was no alteration in the chamber. 143. Among the Bessemer forgings in the Great Exhibition of 1862, was " a 21-pounder steel gun in the rough, with the trunnions formed upon it. This gun is the 92d made by Messrs. Henry Bessemer & Co. ;"* also, " a 24-pounder steel gun, bored and finished by Messrs. Fawcett, Preston, & Co., of Liver- pool, for. whom a dozen of the same size are in the course of being forged."* 144. The present English prices for Bessemer gun-steel are, for a plain 1-ton forging, 9 cents per Ib. ; for the same, with trunnions forged on, 1 1 cents ; for a 3 to 5-ton ingot, forged into a cylinder, 11 to 13 cents. 145. Naylor, Tickers, & Co.'s Steel Ouii- Forgings. At the establishment of Messrs. Naylor, Tickers, & Co., Sheffield, low steel of a very superior quality is made in ingots as heavy as 5 tons weight. In new works, to be in operation in 1861, ingots and forgings weighing 10 tons will be produced. 146. The following is from the official account of the trial of a 20-pounder (3'75 in.) gun of 1832 Ibs. weight, rifled with 44 grooves, made from a forging of this steel : " The Committee have the honor to report that the cast-steel block ordered from Messrs. Kay lor & Tickers, of Sheffield, in December, 1859, but not delivered till July, 1862, has been duly converted into a 20- pounder Armstrong gun in the Royal Gun Factory, and has resisted 100 rounds fired with the service charge of 2-J Ibs., and cylinders increasing in weight every 10th round from 20 Ibs. to 200 Ibs. The last 10 cylinders of 200 Ibs. were 71.5 inches long, or only 14r'125 inches less than the length of the bore. The block Bessemer steel gun. London Engineer, May 2, 1862. 1 06 ORDNANCE. having been delivered without trunnions, a trunnion-coil was shrunk on in the Royal Gun Factories, and confined by a wrought-iron coil 14.5 inches long in front, corresponding to the 3 B coil of an ordinary gun, to which, in other respects, it corre- sponded in dimensions. " The gun is still serviceable, and not perceptibly affected by the firing. It required rebouching at the 40th round, and there was at different periods of the proof a very considerable escape of gas, arising from the wear of the copper rings on the gun and on the vent-pieces.* " The Committee have to report that the 20-pounder Armstrong gun (exptl.), made in a block of cast steel supplied by Messrs. Naylor & Tickers, has completed the second series of proof rounds, and is still entire. This series consisted of 10 rounds with double charge and service shot, and 27 rounds with double charge, and cylinders increasing every third round from the weight of 2 shot up to 10 shot total, 37 rounds, or, including the trial previously reported, 137 rounds ; the only effect upon the gun itself is, that the powder and shot chambers have expanded a little (about 0-008 inch). The bore is free from flaws."f 147'. MUSHET AND CLARE'S 20-PouNDER. This gun, con- structed and rifled like the above, was subjected to extreme proof, but did not endure the 100 rounds. 148. MERSEY PUDDLED-&TEEL GUN. An 8-in. gun of 7 tons weight was forged at the Mersey Works, from puddled steel, for Mr. Lynall Thomas. It burst after a few rounds, with a 145-lb. shot and a 25-lb. charge. SECTION IY. CAST-!RON GUNS.J 149. Rodman and Dalilgren Gnois. Although the United States Government has made little progress in the adaptation of * Report of the Ordnance Select Committee, Dec. 10, 1862. f Report of the Ordnance Select Committee, May 13, 1863. \ Some facts about the endurance of cast-iron guns are given in a note under the head of cast iron (357). A 12-inch gun, cast for Commodore Stockton after the failure of the Princeton's wrought-iron gun (426), burst after a few fires, with 25 Ibs. of powder. CAST-IRON GUNS. 107 wrought iron and steel to cannon-mak- Fl - ing, it has certainly attained to a remark- able degree of perfection in the figure, material, and fabrication of its cast-iron guns. While constructors in Europe have carefully preserved the traditional shapes and ornamentation of early times shapes that once had a significance, but are now only sources of weakness the aim in America has been to ascertain the exact amount and locality of strain, and to pro- portion the parts with this reference, to the entire abandonment of whatever is merely fanciful and traditional.* The consequent saving of weight with a given strength at the point of maximum strain, is well illustrated by placing a sec- tion of the British 8-in. gun (68-pounder) over that of the United States army 8-inch columbiad, Fig. 76. 150. Equal attention has been paid to the selection and treatment of the mate- rial. The best American iron is admitted by English authorities to be superior to the best English : a good quality of iron for cannon is certainly the more abundant in America (355). 151. Major Hodman's process of cast- ing guns hollow and cooling them from within (373), for the purpose of modifying the initial strains, when added to the ad- vantages of good proportion and strong material, produces nearly or quite the best result attainable with simple cast iron. But the tension of this material at its elastic limit is so low (352), that it will not alone endure the pressure necessary to give the * See foot note under 236. Section of British 8-in. (68 T pdr.) laid over section of U. S. 8-in. Columbiad Scale, i 7 tj in. to 1 ft. 108 ORDNANCE. highest velocities to the heavy projectiles demanded by iron-clad warfare. 152. Considering, however, the failure of such a large propor- tion of the heavy wrought iron guns (425, 426, 444 to 446), both built-up and solid, and the present scarcity and enormous cost of steel masses of the proper quality, it is by no means certain that the cast-iron barrel lined with steel, or as so largely and success- fully used in America, France, and Spain, strengthened by hoops, is not the best temporary resort. 1 53. Hollow casting, the most obvious means of improvement, is not deemed important for heavy ordnance alone. The 4-2-inch rifled United States siege-gun is cast hollow and cooled from with- in. Indeed, the advantages of the process can be better realized in the 8 or 10-inch barrel cast for hooping, than in the 15-inch columbiad. 154. Hollow-Cat Gnus. All United States army guns down to 4'2 in. bore are hollow-cast. The 20 inch, 15-inch, and the suc- cessful 13-inch navy guns have been cast hollow. Recently, many of the chief officers of this department have strongly recommended hollow casting for all navy guns, and have begun to practise it in the construction of 10 and 11-inch guns. The following abstract of official reports* will explain the con- duct and results of the hollow-casting process. Its merits and possible improvements are discussed in a succeeding chapterf (373). On the 4th of August, 1849, two 8-inch columbiads were cast at the Fort Pitt Works, from the same iron. No. 1 was cast solid, in * "Reports of Experiments on Metals for Cannon," 1856. f It is officially stated that the experimental solid-cast 13-in. guns for the navy have all burst at proof. The test prescribed was 500 rounds with service charges. One of the hollow-cast 13-in. guns fired 700 rounds. The Scientific American gives the following account of the test of one of the liollow- cast 13-in. guns: "The test applied was 30 Ibs. of powder for the first 10 rounds, 40 Ibs. for the second 10 rounds, and 50 Ibs. for the remaining 158 rounds. The powder employed was much finer than is used in the service, and, of course, its ex- plosive power was proportionately greater The gun burst at the 178th round." The weight of the shot was 280 Ibs. Of two British 13-in. mortars, one cast hollow stood 2000 rounds without bursting, while one cast solid burst at the 533d round. CAST-IRON GUNS. 109 110 ORDNANCE. the usual manner ; No. 2 was FIG. 80. cast on a hollow core, through which a stream of water passed while the metal was cooling. The iron for both castings was melted at the same time in two air furnaces, each containing 14000 Ibs. After melting, the liquid iron remained in the fur ^ naces, exposed to a high heat, for one hour ; it was then dis- charged into a common reser- voir, whence it issued in a sin- gle stream, which, after pro- ceeding a few feet, separated into two branches, one leading to each mould. I ">">. The solid casting was cooled as usual, in an open pit. " The hollow casting was cooled, in the interior, by passing a stream of water through the core, for a period of 40 hours, when the core was withdrawn ; after which the water passed through the interior cavity formed by the core, for 20 hours. The average quantity gie '^ e . g ca iej of water passed through during iV in - to ] ft - the whole period was 1-66 cubic feet per minute, or 100 feet per hour; making in all GOOO cubic feet, weighing 187 tons. The temperature of the water was increased 20 during the first hour ; 13 during the 20th hour ; 8 during the 40th hour ; and 3 during the 60th and last hour. The weight of the water passed through is 30 times the weight of the casting ; and the heat imparted by the casting to the water, and carried off by the U. S. Army lu-in. Colum- biad. Scale, -fa in. to 1 ft. CAST-IRON GUNS. Ill 81. FIG. 82. U. S. Navy 15-in. gun. Scale, in. to 1 ft. IF. S. Navy 11 -in. Dahlpren gun. Scale, -fa in. to 1 ft. latter, is equal to 10 on the whole quantity of water used. The mould for this casting was placed in a covered pit, which had 112 ORDNANCE. been previously heated to about 400 ; and this heat was kept up as long as the stream of water was supplied. Both columbiads FlG - 83 - were completed and inspected Septem- ber 6th, and were found to be accurate and uniform in their dimensions and weights." 156. The charges used in testing the guns were as follows : PROOF CHARGES. 1st fire, 12, Ibs. powder, i ball, and i wad. ad fire, 15 Ibs. powder, i shell, and I sabot. SERVICE CHARGES. lo Ibs. powder, i ball, and i sabot. Mean weight of balls used, 63^ Ibs. Mean weight of shells used, 49 Ibs. Mean proof range of powder used, 298 yards. The guns were fired alternately, up to the 85th fire, at which columbiad No. 1, cast solid, burst. Then the proof pro- ceeded with No. 2, which burst at the 251st fire, having endured nearly 3 times as much service as the other. 157. On the 30th of July, 1851, two more 8-inch columbiads were cast at the same foundry, and under similar circum- stances ; the one was cast solid, and the other hollow r . The iron for both (Green- wood) remained in fusion 2J hours, ex- posed to a high heat. Dahlgren 7 fin. rifle. Scale, T 3 * in. to 1 ft. 158. The core for the hollow gun was formed upon a water- tight cast-iron tube closed at the lower end. The water descended to the bottom of this tube by a central tube open at the lower end, and ascended through the annular space between the tubes. " The CAST-IRON GUNS. 113 FIG. 84. water passed through the core at the rate of 2| cubic feet per minute, or 150 feet per hour. At 25 hours after casting, the core was withdrawn, and the water thereafter circulated through the interior cavity form- ed by the core, at the same rate for 40 hours; making 65 hours in all. The whole quantity of water passed through the casting was nearly 10000 cubic feet, weighing about 300 tons, or about 50 times the weight of the casting. The heat im- parted by the casting to the water, and car- ried off by the latter, is equal to 6 on the whole quantity of water used. Cross-section Dahlgren H-in. rifle. Scale, -f 6 in. to 1 ft. FiG. 86. Dahlgren breech strap for 7|-in. rifle. Scale, -fa in. to 1 ft. " A fire was kindled in the bottom of the pit directly after cast- ing, and was continued 60 hours. The pit was covered, and the iron case containing the gun-mould was kept at as high a temper- ature as it would safely bear, being nearly to a red heat, all the time." 8 114 ORDNANCE. 1O. Shortly afterwards (August 21st) two 10-inch columbiads were cast, of the same iron, the one solid, and the other hollow. Both moulds were placed in the same pit, and all the space in the pit, outside of the moulds, was filled with moulding-sand and rammed. " This was done because the iron cases of the moulds were not large enough to admit the usual thickness of clay in the walls of the mould. It was apprehended that the heat of the great mass of iron within, would penetrate through the thin mould, and heat the iron cases so much as to cause them to yield and let the iron run out of the mould." The external cooling of the 10-inch hollow gun, by the contact of the flask with green sand, was therefore much more rapid than that of the 8-inch hol- low gun. 1 6O. " Water was passed through the core at the rate of about 4 cubic feet per minute, or 240 feet per hour, for 94 hours; amounting in all to 22560 feet, weighing about TOO tons, or 70 times the weight of the casting. The mean elevation of the tem- perature of all the water passed through the core in 94 hours, was about 3^. At the end of this period an attempt was made to withdraw the core from the casting, which proved unsuccessful. The contraction of the iron around it held it so firmly, that the upper part of it broke off, leaving the remainder imbedded in the casting. The stream of water was then diminished to about 2 feet per minute, which continued to circulate through the core for 48 hours. The supply of water allotted to and circulated through both the 8-inch and 10-inch guns was equal, in weight, to the weight of each casting, in about 1 hour and 20 minutes." 161. The proof of the 8-inch guns commenced August 28th; that of the 10-inch guns, October 7th. "Eighty fires per day were easily made with 7 men, in 5 hours, from the 8-inch gun ; and with 9 men, 60 fires were made in the same time from the 10-inch gun. * * * Fifteen fires were sometimes made from the 8-inch gun in 30 minutes. * * * The two guns making the pair to be compared were fired alternately, one discharge from each, in regular succession, until one of them burst, when the firing of the survivor was continued by itself alone. The powder of the CAST-IRON GUNS. 115 cartridges of each pair was of the same proof range, and taken from the same cask." PROOF CHARGES. ,, . , f ist fire, 12 Ibs. powder, i ball and sabot, and i wad. \ 2d fire, 15 Ibs. powder, I shell with sabot. . k / Ist fi re > 20 Ibs. powder, i ball and sabot, and i wad. I ad fire, 24 Ibs. powder, i shell with sabot. SERVICE CHARGES. 8-inch 10 Ibs. powder, i ball with sabot, lo-inch 1 8 Ibs. powder, i ball with sabot. Weight of 8-inch balls, 63^- Ibs. ; of shells, 48^ Ibs. Weight of io-5nch balls, 124 Ibs. 5 of shells, 91 Ibs. " The number of fires made from each gun, including proof charges, was as folio ws:- 8-inch gun, No. 3, cast solid, 73 fires. 8-inch gun, No. 4, cast hollow, 1500 fires, lo-inch gun, No. 5, cast solid, 20 fires, lo-inch gun, No. 6, cast hollow, 249 fires. " Each of them, excepting the 8-inch gun ISTo. 4, cast hollow, burst at the last fire ; and that remains unbroken, and apparently capable of much further service. " On comparing the enlargements of the bores (made by an equal number of fires) of the guns cast solid with those cast hol- low, it will be seen that, in both pairs of guns, the enlargement is least in those cast hollow. * * * 162. "The less endurance of the 10-inch hollow gun than that of the 8-inch hollow one, is accounted for by the fact that the 10- inch gun had no fire on the exterior of the flask while cooling, it having been rammed up in the pit, where it was supposed, at the time of casting, the heat of the gun would have been retained by the sand until the interior should have been cooled by the circu- lation of water through the core-barrel. This supposition was found to be erroneous on digging out the sand, as its temperature was found to be much lower than had been expected." 116 ORDNANCE. 1 63. TEST OF NEW ORDNANCE. The proposals for army guns, 1863, specify that the iron is to have a tenacity of not less than 30000 Ibs., and that a trial-gun is to endure 1000 rounds with ser- vice charges, 200 rounds to be with solid shot, and 800 rounds with shells. In the Navy Department the test is as follows : The maker is required to provide sufficient iron of uniform make and quality to execute the entire order. Five guns are cast, and the iron is tested. The strength of that which is nearest the average of the five specimens is prescribed as the standard of strength. This should be about 30000 Ibs. per square inch. A variation of 2500 Ibs. each way, that is, from 27500 Ibs. to 32500 Ibs., is allowed. A similar rule is observed with regard to the specific gravity, which should be about 7*23. The proof for the smaller guns is, that one gun out of the whole order shall endure 1000 rounds with service charges. For guns of 13-in. bore and upwards, 500 rounds are required.* One of the 15-inch navy guns was fired 900 times at ele- vations from to 5. The charge commenced at 35 Ibs. It was then increased to 50 Ibs. With 60 Ibs. 220 rounds were fired. The gun at length burst with 70 Ibs. The shot in all cases was 440 Ibs. After the first 300 rounds, the chamber (Fig. 81) was bored out to a nearly parabolic form, and the chase was turned down 3 inches, so as to fit the port designed for the 13-in. gun. 1 64. COLTJMBIADS. " The columbiads are a species of sea- coast cannon, which combine certain qualities of the gun, how- itzer, and mortar; in other words, they are long, chambered pieces, capable of projecting solid shot and shells, with heavy charges of powder, at high angles of elevation, and are therefore * "No gun has been accepted as a standard, which has not been subjected to the ordeal of 1000 rounds of service charges. With this standard thus established, all the guns of a contract must coincide in their composite elements. The only exception to the rule has been in the case of the 15-inch guns cast upon the plan of Major Rodman, of the United States Army. Time did not admit of this proof being applied, and the guns were necessarily accepted and put into service, after having endured, however, somewhat more than the tests prescribed by the army regulations." From the Report of the Chief of Ordnance, U. S. Navy Department, Oct. 20, 18G3. CAST-IRON GUNS. 117 equally suited to the defence of narrow channels and distant roadsteads. " The columbiad was invented by the late Colonel Bumford, and used in the war of 1812 for firing solid shot. In 1844 the model was changed, by lengthening the bore and increasing the weight of metal, to enable it to endure the increased charge of powder, or of the weight of the solid shot. Six years after this, it was discovered that the pieces thus altered did not always possess the requisite strength. In 1858 they were degraded to the rank of shell guns, to be fired with diminished charges of powder^ and their places supplied with pieces of improved model. 1 65. " The changes made in forming the new model, consisted in giving greater thickness of metal in the prolongation of the axis of the bore, which was done by diminishing the length of the bore itself; in substituting a hemispherical bottom to the bore and removing the cylindrical chamber ; in removing the swell of the muzzle and base ring; and in rounding off the corner of the breech."* The present model, as illustrated, was proposed by Captain Rodman, in 1860. 166. New Gun 2O-Iucli Guns. In addition to the heavy ordnance illustrated in the accompanying engravings, the Navy Department has introduced a superior gun of 10-inch calibre, called a 125-pounder. The exterior dimensions are nearly the same as those of the 11-inch gun, except that the maximum diameter of the reinforce is continued farther forward (3 calibres). The first of these guns was cast solid, and endured 47 Ibs. of powder and 125-lb. balls for some hundred rounds. The new 10-inch gun is cast hollow; charge, 40 Ibs. ; shot, 125 Ibs. Its dimensions are given in Table 23. The chambers of the navy 13 and 15-in. guns, as shown in the engravings, have recently been changed to a shape nearly parabolic. The Navy Department has four 12-in. rifles, cast hollow, of about the exterior dimensions of the 15-inch gun. It is believed * "Ordnance and Gunnery," Benton, 1862. 118 ORDNANCE. that they will have satisfactory endurance with 50-lb. charges and 600-lb. bolts. Twenty-inch guns for the army and navy have recently been cast at Pittsburg. The following are the particulars of the metal and the fabrication of the first 20-inch (army) gun : The iron was high No. 2, warm blast (200) hematite, from Blair county, Pennsylvania. The smelted pigs were remelted and cast into pigs, which were again melted in three air- furnaces. The weight of iron was 172000 Ibs. ; the time of melting, 7J hours; the time of casting, 23 minutes. Water, run through the core at the rate of 30 gallons per minute, during the first hour was heated from 36 to 92 ; during the second hour, at the rate of 60 gallons per minute, water emerged at 61. From the loth to the 20th hour after casting, the water was heated 21*5. After the 26th hour the core-barrel was removed, and air was forced into the bore at the rate of 2000 cubic feet per minute. The metal was considered too high to be cooled by the direct contact of water. At the 50th hour after casting, the air emerging from the gun was 130 seconds in rising 60 to 212. The gun was cast on the llth of February, 1864. On the 17th, the difference in the temperature of the entering and emerging air was 100 ; on the 20th it was 33. Air circulated through the bore till the 24th. The mould, 5 to 6 inches in thickness, was made in a two-part iron flask, 1^ in. thick. On the 23d the upper part of the mould was removed ; on the 24th the lower part was removed ; on the 25th the gun was removed from the pit. The density of the metal taken from the casting was 7'3028. The tenacity was 28737 Ibs. per square inch. XOTE. "The only establishments in the country, which were prepared for the work of founding heavy cannon when the rebellion took place, were at the South Boston, Fort Pitt, and West Point foundries. * * * In addition to the above-named foundries, the bureau has now, as sources of supply, the establishment at Providence, R. I., known as the Builders' Iron Foundry; the foundries of Messrs. Hinkley, Wil- liams & Co., of Boston, and the Portland Co. of Portland, Maine; and at Reading. Pa., the Scott Foundry of Messrs. Seyfert, McManus & Co." From Report of the Chief of Ordnance, U. S. Navy Department, Oct. 20, 1863. At the Fort Pitt foundry, over 2000 cannon, among them 108 fifteen-inch guns, have been cast since the outbreak of the rebellion (Sept. 1864.) CAST-IRON GUNS. 119 ft S I o 3 5 Q 5 I M M p g I pa I ^3 PH 52 P W H Remarks. i 1! I :| *o . o "3 4J a J5 5 ^ U Ooocvo co Bursting charge. Shell. * l^ l^ CO M & ** .a ; i Service charge. c ' ""* !c J '*' vo O **" ^ - j ,9 bti O O ro vo vo vo tf M (V O * * vo ON rt vo oo ro i-i rj- CO M o ro 00 Maximum diameter. C ^- 00 w A^ v*0 vo Length of bore. G O vo vo vo O O ~ VO VO O "1 C< vo bi> K * vo C5 CO O t-~ VO CO CO "i TJ- ON r-- ro rt co VO I I ' ' **< fc) o j : '* vg : 3 M O - * . i ME d d <+ d S w> i^3-OT3 T3S.i 1 CJ ^' 1 ^^1 -^0 OJJCJ3-CJ3J3 ^vo C 3 O 1 S S .S S .2 '7 ^2 ._. ._. ._. ._. ._, ^^ O vo ro O OO ^ e i CO 120 ORDNANCE. CO i! ,9 *; .C u N-> O -5 s S, E 15 .u S i .S is S ^ c j E.SO So G J2,j ,j - w ~ > g w "3 "o C C^S ^5 1 ^' S a ^ J J 1 . i ' J III -C rt rt V3 U U 3 S *J U U I s *. . 0^ jj- 0000 co o t^ O o ! 8 11 ^ : co c It M 1-1 rt 2 r o e O O J 2 * * O 'o co o r^ c Os IO t-^ 2 2 o |1 c CO CO o t S . II i \ & \ S 'S T : ; i s i 8 1 ^ CO 2. o rt O O 10 \f) j= 3 JB > Q OJ g* goo JO O O O 8 8 8 VO CO 3 ^ O H VO d ON vo NO NO ON * rt E u H 51 S * - J MHO tl ON r> co co r r^ co O H J- CO T fi* 5 r*0 Hl . co O O C ON 1-- tv ^* NO o 1,1 c ' NO CO CO co M O 4- ro CO JT ; : : : : ; C ^ i *" i : " ; X> p O pq D o d c 4 4 4 'o C C NO^ 1 1 13 o x j: j= j: -c jc M O c H CL, 2 c2 J .1 J c c c 2 1 8 10 to ON -o S S s rt cu *? - 5 S c 03 1 l.P~3 M!Ui ^ .s^fl- ft o-2i*2 S feg' r-" -TrxA^i a, U?-S" 5 .5 =?->* i spi d 2*c=^- 92. sion ; the result is, a gradual disturbance of particles and rapid deterioration, until at length the mortar opens and generally splits in two pieces, much as if chopped down by some instrument. An inspection, however, of the remains of the mortars will afford convincing proof that some cause was at work to produce such very similar results, and will show how little our mortars are to be relied on for continuous bom- bardment." The cast-iron mortar of 24-inch bore, and 17904 Ibs. weight, made at Liege for the siege of Antwerp, in 1832, burst after a few rounds British 13-m. mortar burst at Sweaborg. Several 18-inch mortars were cast hollow on 14-inch cores, by Messrs. Forrester & Co., for the British government. They have not been in service. Nearly twenty years ago, Messrs. Walker, of the Gospel Oak Foundry, cast a 20- in. mortar for Egypt. 126 ORDNANCE. M Windage. SO VO ^ c) ^ to JC VO o o o o o o o o O O O Service charge. t rJ rt O vo T$- o o oo 00 vo rj- Proof charge. A O 00 O 00 vo O g ft M tn ti * ft VO * OO VO Diameter of trun- nions. vo vo H rt H vo t^ r^ oo oo oo t^- vo VO VO VO VO VO vo Length of trun- nions. .s *? *r V VO VO VO VO VO Diameter of cham- ber at rear. H H e* ON jj V> VO M W W 00 r^ r^ oo oo oo vo ON 00 ON oo VO vo vo vo VO Diameter of bore. a o o ? ? ? ? i-l M OO OO OO OO oo oo ro ON oo O oo vo VO VO 00 VO VO Length of bore. 0^ 0^ ^ ^ Z To el t* o OO O Diameter over rear of chamber. vO vb rl VO rt ^ vo vo t-^ VO vo c< a s 3 vo H Preponderance. T*- VO VO vo oo r^> t+> ? ? ^ T T ,? u ON 00 00 t>s oo vo ON VO VO ^ VO oo H o vo VO O ON Weight. ^ l-^ T^- ro vo t~. vo 00 00 i-l ON 00 VO 3 Jo ON vo OO ri b O fc \ : : j j d i j| ^ * * * h2 58 * s -1 I * c c - B- 33 3 O O w u O ^ ^ ^ rj - C C C r. ri 6 55 cT 3 o cT O c o' c 3 O -o G o' 3 O CO N O 00 00 o d t oo OO vo ^ Ox vo .0 g f-. Ox ON 5- to to to 00 ^ 00 00 rj- VO to VO to vo to Ox to 00 M ON to cJ oo vo vo VO VO vo vo vo 10 vo vo vo VO VO vo vo VO * vo vS vo vo t--- vo vo ON vo ic jc ic VO to r) vo VO VO ^0 * vo si si vo VO VO VO VO vo VO vo vo vo vo vo to vo vo VO VO vo vo vo vo vi VO vo vo VO VO VO VO to r-. ? vo t> VO vO oo o CO VO vo CO 1-4 Ox O O O OO Ox OO O Ox Ox vo K VO 00 ^ to oo 2 CO to VO oo ^ VO co 5. VO T*- to to o vo ^- vo to vO VO vo vo vo rt to A to j. vo IN vo VO 00 M Ox 00 o vo ri vo M VO M 11 11 ' : j j MM! i to e 1 1 cS o' * c 3 O to 3 O o' o # -i- -*H- C* tO Tj- VO $ | I ^ I 'Sx c" c" c" c c 33333 O O cT 3 o cT 3 O U c 3 O | C 3 O s g e 3 O C 3 O 1 u o c 3 O OH 1 -o c 3 O a. V c 1 73 T3 T3 -T3 T3 C C C C C 33333 8. i ! 1. & T3 c 3 O Oi u -o C 3 O CU U -o 1 1 c 1 1 1 ongreve's * * * to to to to to to to to to to to U 128 ORDNANCE. Windage. to M M M M ON ON t^. t^. tt. "ON O O O O so ON O so ON O so 0000 0000 O ^ 00 Service charge. as oo a s M M 1 Diameter of trun- to ,2 O to d OO to to d d d d ON Os to to H so d vo to so to to Length of trun- nions. a d d ON T- -4- N r< 1C 1C to to co co H r> CO to to to Diameter of cham- fl **"> 00 00 00 H H M SO SO so SO so Diameter of bore. a* ^ CO d 00 co co rt rt oo oo rt rt co r t^- t^ d M M M SO CO H VO to 1 ^' * vo t^ t^. t^ rt so T- co ^- vr oo t< N d r tl Length of bore. 00 o O t^ O 00 M M ON w rt r- i-^ so o SO M VO 0^ oo SO so J JT IH ^ ON ON to oo co r to so ON rt vo oo SO g of chamber. - s ON ON 00 t^ t^ vo vo CO VO so so VO 1 3 Preponderance. r vo vo vo JT so vo vo vo w vo ON vo d so VO 5 1 to T*- to to to tO d M tO to d -- Weight. 1 Q oo to M oo d o ro ON ! : i ill! i i * * i . : : : : | j C 3 O j : : : ! : ! : : O h o ft V C 3 O to o a. 3 d 55 rt p M i j| | | * H -M- M C| ** ' M d d d d K & Z, Z d d 55 to d 55 4 d 55 m 9-pdr. of 25 cwt. 1 3 O c c (T c 3333 O O O O G G G G 3333 O O G O G O G 0, 3 -1 V g bo c 1 <* 1111 1111 rt- ^ OO OO 3333 f. f. i. 1 oo oo oo H 1 1 d G 1 1 1 * rt H cJ CAST-IRON GUNS. 129 M rt * 2 ^2 2 vo . OO SO vo vo c< IH CO CO OO M vo o vo O o o o o o o o : O O O O N O 00 N O 00 vo 8 OO s 8 00 s o i CO i ja ON ON ON 00 VO VO vo H rj- VO H4 CO ON oo VO *$ CO N 00 .0 IH M 00 00 00 VO VO VO M VO H rl cl vo vo vo oo M IH 00 s C o ON $ vo ON vo vo vo ON VO IH * *|-<+mmmt-.^ * "* CO CO CO CO CO CO 00 00 00 VO IH C co 'co' 3 n vo vo ^ v2 vo ON vo c) 00 00 00 vo vo vo vo C* d c vo VO vo vo * vo ON CO VO vO H o oo oo oo r cJ rt vo vo vo O o ^" ^* ^- CO CO CO M OO OO VO cJ vo vo ON VO vo VO 00 VO vo vo vo VO CO oo vo ON vo oo vo vo r) t~- M co ^ t-^ ON vo ON H ^- ON OO O ^J- vo t^- VO ^r^vooooovo vor^ oo t~ ON CO vo CO VO CO OO t^- O >H VO vo O O vo CO ON ^- co vo CO CO CO CO H co vo ON co vo ON A vo CO ON VO vo oo vo VO CO rt VO vo cJ O ON VO ON co M vo 00 ON rj- vo t-v. CO rj- OO OO CO C vo CO VO CO vo t-^. vo VO rt M H M r r vo t-^ vo CO VO ? vo ' H SV *5 S 8 * 3- 8, CJ CO CJ - i I i ! i : ! : i i : : : : : : i : i : : ' : ": j M M i i i i i ; I [: ]- ! f ! 1 f i : : : : : N ci co 4- J tl co : ! : : : : i r 6 d o o' o 6 I '. SR fc ; fc. fc fc fc j j QJ aj c c c c c e S awitzet J c u o N fc 1 I -0 1 -a -o C C 2 (4 c o 1-1 o w I 3 O 333333.-.- oooooo | | * i 3 3 3 d 3 o 3 c 1 ON CCCCCCrj,- 033333uu 8. 8. 8. 1. g. 8. J ; J i i i i i i i 7 ONONONVOVONO OOO T3 c 1 r> Coehorn ] 58-pounde T3 e 1* rl 1 1 e c 3 3 o o 0. CL. 4- oo e 1 V -o I vo 130 ORDNANCE. I PQ En O O o > X M Windage. a 7 VO 6 NO 6 VO 6 vo vO o 6 Service charge. 8 ; o > rt 00 ON ON * * rt * 00 Proof charge. g ~ 1 8 00 ON ON * * - a ^ 00 Diameter of trun- nions. u-> a . oo ON W) r VO NO T '* 00 A Length of trun- nions. m .2 "^ VO r H r Diam. of chamber, rear of taper. a . 1C - r 00 r H <* r 7 Diameter of cham- ber. Front. a *? r m 2 r H NO u-i Length of chamber. a 7 00 VO ^ 00 00 '0 00 oo oo vo VO Diameter of bore. a ra oo oo r H NO Length of bore. "" ON w> T 8 vrt VO T*- Os Diameter at muzzle. a . * oo NO M 00 rt O NO VO ^" tn oo Diameter over chamber. a <* m ON NO ? NO 8 O NO NO o VO 00 s Length. .2 *? *-/"! NO NO ON M OO ? r si 2 7 Weight. 1 8 ^ CO P 00 00 ON " H M i h o f 1 4> > 1 i-service Mortar 1-service Mortar .-service Mortar .-service Mortar l-service Mortar -service Mortar ortar Mortar H B c/3 u c en u c 'S e c e 6 c c 6 c 05 C 00 c n e 00 c 1 a 1 CAST-IRON GUNS. 131 TABLE XXVIL COST OF GUNS. NAME OF GUN. Material. Bore. Weight Cost per pound. Total cost. Armstrong io^-in. gun Wrought-iron coils in hoops in. 10 c Ibs. 26880 cts. . 6 $ $9000 oo Armstrong i lo-pdr. gun Wrought-iron coils in 7 0184 21 * O 2IQC . 7 c Horsfall gun WVought iron forged solid 1 1 c?846 27 .2 1 2500 oo Alfred gun \Vrought iron forged hollow JO 24004 ao-7 5000.00 Krupp's I5~in. gun*... Krupp's 9-in. gun Cast steel forged solid.. Cast steel forged solid.. Cast steel forged solid. IS' 9' 7 to 8 33600 18000 1 1 200 87-5 56.2 I 7 O 29400 oo IOI2500 1466 -oo Blakely 12-in gun Cast steel hooped with steel 12 40000 87. c 3 COOO -OO Blakely ii-in. gun. . .. Cast steel hooped with steel 1 1 J COOO 78.? 27 COO -OO Blakely lo-in gun Cast steel hooped with / .) steel IO 30000 <8.7 I 7 COO -OO Blakely I2o-pdr. gun.. Cast steel hooped with steel 7 0600 62 c 6000 oo Whitworth i2O-pdr. ... Cast steel hooped with steel 7 1 1440 77 .2 COOO *OO Parrott loo-pdr. gun... Cast iron hooped with wrought iron 6-4 0700 12-4 I 2OO-OO Parrott 8-in gun Cast iron hooped with wrought iron 8. 16300 H. i 2300 oo Parrott lo-in. gun Cast iron hooped with IO 26500 17 O 4COO 'OO Rodman I5~in. gun Rodman jo-in. gun Rodman 8-in. gun Cast iron cast hollow... Cast iron cast hollow... Cast iron cast hollow... 15' I0 8. 49100 15059 8465 13-2 9*75 9-75 6500*00 1468*00 825-00 * This is the weight and price unofficially reported. The price is, probably, not far wrong. The Armstrong 600-pr. (13-3-in.) cost $19000, or 37 cents per pound. 132 ORDNANCE. CHAPTER II. THE REQUIREMENTS OP GUNS ARMOR. SECTION I. THE WORK TO BE DONE. 171. If the introduction of 11-in. shell-guns had not ren- dered wooden walls, and even iron hulls without armor, impracti- cable for war- vessels, the American experiments with 15-in. guns, and the promise of larger calibres, plainly indicated that the great accuracy, long range, and enormous bursting charges of mod- ern shells would add to the power of ordnance, more than high speed by steam would add to the power of ships. A moving object was indeed an uncertain mark, but one 15-inch projectile, rightly planted, was likely to destroy or seriously cripple any vessel.* More recently, the penetration and shattering of masonry by rifle projectiles at long range, demonstrated the fatal weakness of the present forts. From these causes, a new and additional feature of defence be- came indispensable. The cuirass of ancient times was restored, but instead of defending the breasts of single warriors from hostile spears, it was expanded over whole frigates and fortifications their armament, men, and machinery and thickened to resist shells and even solid shot of ordinary power. So rapidly have these changes occurred, and so much absorbed are engineers in the improvement of the rival systems offen- sive and defensive that the fundamental and comprehensive character of this revolution in warfare is hardly appreciated. The experimental fight of the armored batteries at Kinburn, so late as 1855, was neglected by the profession at large, and the subsequent commencement of iron-clad vessels in France and England was * One 15-in. projectile destroyed the iron-clad Atlanta. (181 B.), and another shattered the side of the iron- clad Tennessee. REQUIREMENTS OF GUNS ARMOR 133 hardly acknowledged by its authors to be a revolutionary proceed- ing. Nor was it the actual beginning of the new system. The three years of the great rebellion in America, and the contempo- rary and comprehensive experiments of the British Government upon the resistance and fabrication of armor, have witnessed its real inauguration, and pointed out the direction and settled many of the fundamental principles of its further improvement. Whether new weapons of offence will again overcome the armor- carry ing power of practicable ships, as gunpowder overcame that of men, so that fortresses which, being fixed, can carry armor enough to resist any conceivable projectile, will be relied on for ultimate defence ; or whether the embarrassments that beset the gumnaker will so rapidly increase and multiply that practicable ships can always carry armor enough to resist projectiles, is not an essential feature of the present discussion. 1 72. The present duty demanded of guns, is to penetrate or remove, in such a way as to cripple the enemy within it, the armor now used on ships, and. the armor that in the present state of the art is likely to be fabricated and to be supported by sea- worthy vessels. The importance of carrying some purely shell-guns of large calibre, to destroy transports or vessels that may not be iron- clad, and to operate against towns, temporary works, and troops on shore, is not to be questioned. Such guns are comparatively perfect."* At least, the means of improving horizontal shell-firing are well understood. The great problem remains unsolved. Indeed, engineers are looking for its solution in diverse or opposite directions. See- ing that the results of experiments, and especially of warfare, in testing guns against armor are developing new features of strength and weakness every day ; that these results are still somewhat un- certain, and that time enough has not elapsed to enable the profes- sion at large to collect and digest what facts there are, few if any first principles are universally recognized. This is still more the * Since the above was written, the power of the U. S. 11-in. guns against wooden walls has been illustrated in the destruction of the Alabama by the Kearsarge. 134 ORDNANCE. i case since, from, motives of gain, pride, or official conservatism, many persons have taken advantage of the limited knowledge on the subject to establish their own schemes, by arranging experi- ments to show their favorable side and to conceal the other, or by publishing one class of facts and ignoring those of a conflicting character.* Or sometimes reticence and a show of mystery are maintained, ostensibly to withhold information from foreign gov- ernments, when it is very well known that governments find means of acquainting themselves with each other's practice. The real loser is the government that, in concealing the truth, withholds it from its own people from the great mass of ingenious and skilful men in civil life who would turn it to good account. The somewhat chaotic state of professional opinion on the ques- tion of the best gun to destroy armored ships, may perhaps be narrowed down to two general theories, the strength of the gun being the common starting-point : 17*1. Two SYSTEMS OF DESTROYING IRON-CLADS. First. It is contended that the most feasible method of attack is to waste no power in racking the whole side of the ship, but to devote the power exclusively to punching the armor with shells if possible. 174. Second. It is contended that the better method is to waste no power in punching mere holes, but to so increase the weight of the shot (a given strain being imposed upon the gun by means of reducing the velocity), that the entire blow shall be expended in straining, loosening, and dislocating the armor, and breaking its fastenings, thus tearing it off, after which the vessel will be easily destroyed by shells ; and at the same time racking and breaking the ribs and side of the vessel, and thus rendering her unseaworthy. 175. Both the theory and the practice appear to indicate, 1st, that these two distinct results -punching, and what we will call racking can be respectively produced by excessive velocities and excessive weights of projectiles the power, which is limited by the respective strains imposed upon the gun-metal, being the * The readers of British scientific journals, for instance, will observe the number and general fairness of these complaints. REQUIREMENTS OF GUNS ARMOR. 135 same in both instances ; and 2d, that in case of a given projec- tile, whatever power is employed in racking the side of the ves- sel, does nothing towards penetration, and vice verm. These effects may be roughly illustrated by throwing a 32-lb. ball and firing a bullet at a light board or piece of thin sheet- iron, supported at the corners. The ball will split the board or break it across the grain, or both; or it will double up the sheet-iron and tear it away from its supports, without showing any signs of penetration. The bullet will make a clean hole, with- out splitting, bulging, or loosening either the board or the iron. 1 76. A simple way of explaining these phenomena is as fol- lows: In the case of the high velocity, the effect was w T holly local, because the surrounding material had no time to propagate the vibrations throughout the mass. In other words, the cohesion of the material was not sufficient, in the time allowed, to overcome the inertia of the surrounding mass. The distribution of the effect, in the other case, was due to the low velocity.* In both cases, the work done might have been the same. 177. The following extract from a paper by Captain Noble, R. A., contains important facts and illustrations upon this subject : " The work done may be stated to be as WV 9 , "W being the weight of the shot, and Y its velocity at the moment of impact. " The work done at 200 yards distance by the 110-pounder Armstrong rifled gun, with 14 Ibs. charge, when "W=lll Ibs. and V=1178 ft., and the 68-pounder smooth-bore gun, with 16 Ibs. * As these phenomena of local and distributed effect of punching and racking armor by different sorts of cannon-shot, are represented to be somewhat mysterious and uncertain by unprofessional people (all men are critics of warfare), various other experiments will show the correctness and distinctness of the two principles involved. A board set on its edge unstably, so that a pistol-ball thrown by the hand will over- turn it, may be riddled with pistol-balls fired at short range with high charges, with- out being overturned. A small table-cloth may be jerked from under the dishes without perceptibly stirring them. It is hardly necessary to state what would be the result of pulling the cloth off slowly. The card snapped from under a coin balanced on the finger ; the punching of clean, small holes in roofing-slate, by a rapid stroke, when a lighter and slower stroke would smash the whole mass ; and many other every-day experiments and processes illustrate the fact, that the element of time essen- tially modifies the effects of moving forces. 136 ORDNANCE. charge, when W=66 Ibs. and Y=1422 ft., is in favor of the for- mer gun in the proportion of 11*5 to 10, nearly; but we find that the penetration is in favor of the smooth-bore 68-pounder. Again, at the same distance, the 110-pounder forcing a bolt of 200 Ibs. with a charge of 10 Ibs., when W=200 Ibs. and V=780-ft., in comparison with the 68-pounder, as before, will be as 10 to 11, nearly, the 68-pounder thus having a slight advantage ; yet the penetration of the 68-pounder is far greater, that of the 200 Ibs. bolt being almost nothing. "How comes it, then, that although the work done by each shot varies so little, the penetrations show such a marked difference ? I think that the following explanations will throw a light on the subject : 177 A. " The actual work done by each shot is, as we have seen, nearly the same ; but one does its work in much less time than the other. This explains the whole matter. " The 200-lb. bolt, with a low velocity, strikes a heavy blow on a spot in the target ; but it takes a certain length of time to accom- plish that blow ; so that, during this interval, all the surrounding particles of iron have ample time to sustain the point struck ; the force of the blow is thus spread over a large surface of the target, and the cohesion of the particles is undisturbed, as each particle is enabled to contribute the force of its attraction towards uniting the whole. " The 68-pounder, on the contrary, strikes the target with a high velocity, and the surrounding particles have not time to sustain one another before the work is accomplished, so as to support the point struck ; the consequence is, that the penetration is greater at the point struck, although the actual amount of work done may be the same. " Lest this language should appear too figurative, I will express it in other words, thus: Let us suppose the matter of which any body is composed, to be comprised of an indefinite number of atoms or particles united together by a certain force. " Call one of these atoms A, and the contiguous atoms B and C ; these last have also contiguous atoms, D and E, and so on. Sup- REQUIREMENTS OF GUNS ARMOR. 137 pose the atom A receives a blow, it instantly endeavors to trans- mit some of the effects of this blow to B and C, which again in o o o o o their turn transmit to E and D ; thus a sort of war of E C A B D motion takes place between the particles, and each atom bears some of the effect of the blow. But a certain time must have transpired before the wave communicates its effect to E and D. If there is sufficient time to enable B, C, D, E, to take up some of the effect, A will, in a corresponding degree, be relieved ; but if there is not sufficient time, A will have a greater force to contend with than it is able to resist, consequently it must yield to that force, and alter its position with regard to the contiguous particles." * * * 177 B. " The mean penetration of the 68-pounder (in the War- rior target) was 2.46 in. ; that of the 110-pounder Armstrong, with a shot of 111 Ibs. and 14 Ibs. charge, 1*6 in. ; while the penetration of the 200-lb. bolt was almost inappreciable. What was the pene- tration of the ' shunt' gun, with a shot of 140 Ibs. and 20 Ibs. of powder? Not much more than the 68-pounder, although the work done was nearly as 17 to 10. But the time of doing this work was longer in one case than the other/' * * * 177 C. "The champions of the 'heavyweights' say that the heavy shot at low velocities will shake the plate off and break all the bolts ; and no doubt such results would be most effective rf they took place. However, up to the present date, these results have not taken place ; the plates in the most obstinate manner refuse to be shaken off, even when fired at directly."* 177 D. The popular notion is, that the future gun must accomplish two things: 1st. It must smash a hole in the enemy's ship. But even the 7-in. Whitworth shot made only a clean, small hole through the Warrior target, and the gun now requires repairs after some 30 heavy charges. And the 13-in. Horsfall gun, which made a ragged hole through the same target and other^ wise injured it, represents the utmost power of the present experi- mental ordnance. The target, at the same time, by no means rep- * It is obvious that the author had not studied the . racking effect of very heavy projectiles. In fact, few had been fired at plates at that time. V 138 ORDNANCE. resents the maximum, resistance of the present armor. 2d. The future gun is popularly expected to shatter and dislocate the whole side of the enemy's ship. Supposing that the same shot could perfect both these results, it must be remembered that all that the best ordnance can do, is to disable the best average armor, by devoting its whole power in one direction, without attempting to inflict two kinds of punishment at a blow. Considering the known results of iron- clad warfare, and the known facilities for improving armor as compared with those for improving ordnance, the obviously safe course is to perfect one method of attack or the other before at- tempting to combine both in the same weapon. The consideration of guns for iron-clad warfare, therefore, involves the two extreme systems, viz., Punching, and the com- bined operations (174) which we have grouped under the head of Hacking. It is proposed to compare the results and the probable efficiency of these systems, with reference to obvious improve- ments in armor, for the purpose of getting at least an approximate idea of which will inflict the greater damage upon an enemy's ships, and how far the two may be successfully combined. SECTION II. HEAVY SHOT AT Low VELOCITIES. 178. EXPERIMENTS. Only a few very heavy shots have been fired at targets. In no cases have the target and the circum- stances been of such & character as to afford complete data for comparing results. So that, as far as experiments are concerned, the racking system requires farther demonstration. Much may be learned, however, from what has been done.* It should also be borne in mind that this is not strictly a compari- son between large and small projectiles, but between high and low velocities. Obviously, the smaller projectile can receive the higher velocity with a given strain upon the gun. But a 13-inch ball fired with 90 Ibs. of powder, at 1760 feet velocity (181 D), or a 13-inch ball fired with 74*4 Ibs. of powder, at 1631 ft. velocity (183), or a * A complete official account of the more important experiments here mentioned, will be given in a following chapter. REQUIREMENTS OF GUNS ARMOR. 139 15-inch ball fired with 60 Ibs. of powder, at 1480 feet velocity (181 A) velocities which rather penetrated than racked the tar- gets at which they were fired are not proper illustrations of the system under consideration. They devoted so much of their power to local effect, that they reserved little for distributed work for the general smashing and dislocation of the ship's sides. And therefore their destructive results may be attributed chiefly to their high velocities. 179. 15-lNCH BALL; 10-INCH TARGET, 20-lNCH OAK BACK- ING. In the spring of 1863, at the Washington Navy Yard, a 15-in. spherical shot, weighing 400 Ibs., was fired at 200 yards range, FIG. 93. FIG. 94. f-H Q a 9 a = o g \ n rn -e- o -? ^.o * /> v 52- 'Cj^ 1 O 9 O c 4. j^v i "i~ j.' Section of 10-in. target and backing. by a slight additional vibration. Scale> ^ in t g o l foot 18O. 11 -INCH BALL; 10- INCH TARGET. Shortly afterwards, an 11-in. spherical cast-iron 140 ORDNANCE. 169-lb. shot was fired at another similar plate (C, Fig. 94) in the same target, at the same range, with 30 Ibs. of powder. A disk was broken out of the 4J-in. plate, leaving an indentation 3^ in. deep (Fig. 96), and about half the bolts were broken and some of them were thrown out. 181. 11-lNCH BALL ; 14- INCH TARGET. About the same time, an 11-in. 169-lb. spherical cast-iron shot was fired at about 50 yards range, with 30 Ibs. of powder, at a target (Fig. 97) 14 in. thick and about 7 ft. square, composed, where the shot struck it, of six 1-in. plates, one 4-in. plate, and four 1-in. plates, without wood backing. The target was planted against a heavy timber framework which abutted against the cap-stones of a sea-wall. FIG. 97. FIG. 96. 11-in. shot on 10 -in. target. 6" X4."*4"-> Ericsson 14-in. target. The blow of the shot produced a small local effect. The in- dentation was about 5 in. ; the outer 1-in. plate was cracked across, and the back plates were bulged 2 or 3 in. But the whole target and framework, and the earth and sea-wall behind it, were shoved bodily backwards several inches. Nearly all the through-bolts, some 40 in number, were loosened, and many of them were broken off in the thread of the screw at the rear. 181 A. 15-lNCH AND 11-lNCH BALLS AND PARROTT 150-LB. BOLT; VARIOUS PLATES; LATE EXPERIMENTS. Some important experiments with the above projectiles have very recently been made at the Washington Navy Yard. The Department has determined not to make public the details of these experiments at present. The general results are as follows : REQUIREMENTS OF GUNS ARMOR. 141 A target composed of 30-in. oak backing and a solid 6-in. French plate, made by Messrs. Petin, Gaudet & Co., was cracked, smashed, and completely penetrated by a 15-in. 400-lb. cast-iron ball, fired at about 50 yards range, with 60 Ibs. of powder, at an initial velocity of 1480 feet per second. A target composed of six 1-in. plates, backed by 10 x 10-in. iron beams, was torn in two and thrown down by similar projectiles. Laminated targets, composed of 1-in. plates, up to 13 inches aggregate thickness, and backed by 24 to 30 inches of oak, have been ruptured and shattered through and through, though not completely penetrated, by the same shot and charges. The 15-in. ball has also knocked down, displaced, and shattered various targets of considerable thickness but not of large size, and therefore not exactly repre- senting the mass and continuity of a ship's side. The 15-in. gun has not been fired at the Warrior target or at any 4-in. target. The 11 -in. gun has recently been fired at various targets with 30-lb. charges and 169-lb. cast-iron balls. At 50 to 100 yards range, this gun penetrates 4-in. solid plates of ordinary quality, but does not make a clean breach through the best plates (215). The Parrott 8-in. rifle, with 150-lb. bolts and 16 Ibs. of pow- der, breaks through but does not punch the best 4^-inch plates, and does not seriously injure the backing. These late experiments have also shown that the convex target, representing the Monitor turret, offers very much greater resistance to both punching and racking than the flat target, composed of the same materials. 181 B. 15-lNdi BALL; IRON-CLAD ATLANTA, 4rJ-LsrcH ARMOR AND 2^-FEET PINE BACKING. In 1863, a 15-in. ball from the " Monitor" Weehawken smashed in, at about 300 yards range, the armor of the Confederate iron-clad Atlanta (Fig. 97 A), and com- pletely disabled her. An 11-in. 169-lb. ball, with 20 Ibs. of pow- der, did not break through the same armor. The casemate of the Atlanta was inclined 35 from the horizon, and was composed of laminated armor of the aggregate thickness of 4^ inches, backed by 2, Professor Pole stated what is generally considered in Englan 1 to be the true office and value of wood backing. It does not add any appreciable strength or resistance to the armor-plate, but, 1st, It distributes the blow ; 156 ORDNANCE. FIG. 103. 5 in. of iron behind the front 4^ in. of the Hawkshaw target ; and it is well known that a good 4-in. plate backed with 18 in. of teak, is neither punched nor much fractured by the 110-pounder or the 68-pounder at 200 yards (177 B). 3OO. But certain American ex- periments are more conclusive on this subject. At the Washington Navy Yard, in the spring of 1863, a 10-in. 130-lb. cast-iron spherical shot was fired with 43 Ibs. of powder range, 200 yards through a target (Fig. 103) composed of six plates making an aggregate thickness of 6^ in., backed by 18 in. of oak. The target was about 15 ft. square, and was the same as that used in the ex- periment with the 15-in. shot (179), except that the outer 4^-in. plate was removed (Fig. 104). The shot made a clean breach, as shown by Fig. 103, and passed some 100 yards to the rear. SOI. One only of two lOJ-in. 150- Ib. balls fired with 50 Ibs. of powder, and therefore more powerful than the 130-lb. ball last mentioned, was able Section of 6.^ in. laminated target. to penetrate the Warrior target at Shoeburyness a 4-J-in. plate backed with 18 in. of teak and a f-in. skin. And two 150-lb. balls fired with 40 Ibs. of powder did not get through the back- ing of the Warrior target. 2O2. The reason why laminated armor is more easily pierced 2d, It is a soft cushion to deaden the vibration and save the fastenings ; 3d, It catches the splinters; and 4th, It still holds the large disks that may be broken out of a plate, firmly enough to resist shells (203). REQUIREMENTS OF GUNS ARMOR. 157 than solid armor, i* thus explained : In a punching machine, the resistance of a plate to punching is directly as the fractured area, FIG. 104. o o- o Side and front of 6^-in. laminated target. that is to say, directly as the thickness of the plate, for a given diameter of hole. But the resistance of a plate to punching-sAetf is found to be about as the square of its thickness. Now, in a machine there is a die under the plate, which prevents the metal around the punch from breaking down. Under an armor-plate there is no such die ; the metal under the punch carries the adja- cent metal with it, and the hole at the back is very much larger than the hole at the front.* So that, while in a machine the frac- tured area (Fig. 106) would be a c, under the blow of a ball it would be a from splinters. Mr. Scott Russell's armor (Fig. 107) is a vast improvement on the Warrior's (Fig. 108) in this regard. The plates would have to be broken into small pieces before they could be thrown out by the vibra- tions of the ship's side. The elastic bolt (Fig. 109) will obviously relieve the effects of heavy shot. 205. Smashing Ship' Sides by Heavy Shot Considered. The more remediless but difficult work expected of heavy shot is to smash the side of the ship to cripple the armor, tear open the skin, break the ribs, and shake the whole structure so violently as to oause either serious leaks or an impaired resistance to farther blows. 206. The resistance of a ship's side to this kind of assault can- not be truly ascertained by firing at small targets. The large REQUIREMENTS OF GUNS ARMOR. 159 mass lias the greater inertia and presents the greater resistance to fracture when the blow is slow enough to allow the surrounding elasticity and tenacity to be called into service. It is possible that the 10~iii. target (179) was so well braced and had so much inertia (it was about 15 feet square, but only half its face was plated), that greater size would not have added to its strength. But it was neither overturned by the 15-in. shot, nor violently shattered ex- cept in the fastenings of the plates. The Inglis target (185) and the T^-in. target (186) were assaulted with excessive violence, and FIG. 108. Section of the Warrior's armor. were certainly racked and crippled ; but they held their ground, and the plates were not thrown FIG. 109. off. Although the straining and breaking of the ribs would prob- ably have caused leakage, it by no Wire-rope bolt for armor, means follows that the buoyancy of a ship with many compart- ments would have been seriously impaired. 160 ORDNANCE. The 14-in. target (181) was so rigid that the 11-in. shot produced less local and more distributed effect. The whole mass, with its framing and the sea-wall behind it, was moved bodily. But it was a small target. The fact that it moved is evidence that greater size the continuity and elasticity of a ship's side would have modified the result. Mr. Scott Russell's target (Figs. 99 and 100) was a heavy structure, but not heavier in proportion to the power of the shot than the 14-in. target ; and it w^as shoved bodily to the rear a quarter of an inch, because, 1st, the shot could not penetrate it, and 2d, it had not the continuity of a ship's side. The targets at which the 15-inch shot were lately fired (181 A) were too small to illustrate the dislocating effects of such pro- jectiles on a casemate incorporated with the whole structure of the ship. The 13-inch Armstrong ball, with 90 Ibs. of powder (181 D), did not overturn nor remove a plate of only 41x24 inches face. (See note on page 187.) But while experimenters may deceive themselves with small targets, they may also deceive themselves with flat targets. The curved sides of the Monitor turrets have been found to resist both smashing and punching better than a flat target of the same thickness.* 3O7. POPULAR THEORY OF DESTROYING ARMOR BY SHOT or MEDIUM WEIGHTS AND VELOCITIES : ITS ERROR. Before proceeding farther in this consideration, it is important to notice a popular error regarding the work demanded of guns. Indeed, some of the practice in the adaptation of naval guns appears to contemplate the destruc- tion of armor by heavy, although not the heaviest shot, at medium velocities. The aim is not to perfect both means of attack rack- ing and punching by trying to get double the power out of one gun, but, with the same power the same charge of powder to barely punch the armor, and to devote the residue of the power to shattering and straining the surrounding structure. If the projec- tile is too heavy to receive quite a punching velocity, it is cer- tainly heavy enough to do some pretty formidable racking. If * This fact is proved by several recent American experiments, the details of which the Government declines to make public. REQUIREMENTS OF GUNS ARMOR. 161 the range happens to be short, and the armor thin, it makes a large hole, while a small shot, at say double the velocity, would make its little hole not only so suddenly that the surrounding parts would not be shattered, but with a small portion of its power, the remainder being lost, or at least not expended on the armor. This theory is to be carried out, not by the small projectiles at high velocities, nor heavy projectiles at low velocities, but by a happy intermediate system of ordnance, that will " waste no power" in any case, but inflict the maximum damage upon the enemy, when the circumstances are favorable. SO 8. LOCAL EFFECT PREVENTS DISTRIBUTED EFFECT, AND YICE YERSA. A very important element has obviously been omitted in this calculation. The same power that indents a plate cannot dis- locate it. "Whatever effort is added to the one kind of destructive effect, is subtracted from the other. The probability of penetra- tion has been reduced by making the shot large, and hence slow. If it does not actually penetrate, a large part of its power has been employed in the fruitless local work of partial penetration, and only the residue of it can be utilized in racking the structure else- where. Or, in other words, the probability of racking and strain- ing the whole structure of serious distributed effect has been reduced by making the shot light and fast enough to devote much of its power to a local effort that is useless, because it is incom- plete. Had, for instance, the 150-lb. Armstrong spherical shot, in all the cases in Table 28, been either much lighter or much heavier, it would have employed the whole force of the powder in one way or the other. Its local effect was certainly tremendous, but it neither shook off the plates nor went through any strong target. The same may be said of all the shots from similar guns. Indeed, the whole table is full of instruction on this point. Notwith- standing the tremendous assault upon the 13-in. and the 7^-in. tar- gets, they were neither punched nor shaken down. The projec- tiles were just heavy enough to prevent the first effect, and just light enough to avoid the other. But it is seriously argued that if a shot does not go entirely through a plate, its velocity is so reduced while passing into the 11 162 ORDNANCE. Ill CO o rt OO OO 00 . CO 5 S ^ ^ 12 u ^ ** JH 55 M ^ ^ rt o 2 J2 1 ^ 4 s . c 13 || g *H< . 'C vn w> J2 S C C e .S S M 1 CJ tf cu M ^'o J> & ; x iPb ."2 fi T-T c T^ C aJ ^" > "o a> tUQ ~ ^s-is ._ O CL, S rt " 1 00 * ? "S .~ -a 3 ^ co' c 2 S 2 ^ O U 8 ^ . e ^ *^ - 1 xS ^ s B *l'| Is . ^1 SU S ^ ? M -S w -a w c Sx M C/5 S B O 1 4-1 c^T3 8 OO g vD V to o _^ C ^ o 1 w w 04 O ^ J _ r -r 5- ^ r : II bo C M SO bo c 'c 'c 'c *c S3 JN 'C -n M 13 .* > *-" *" ^ v ' C/} C/3 C/} Charge. 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JZ 1 _o 0, M en 6 u 3 O U 1 1 to u i 1 bO c N 1 M -0 C -o g S.i <*-, 1 CO t>- c *-o ^ *a O W) C ^ c c CO en f X OS 8 c T C r 4J U rt C w -o u eu" 2 C -^ 'C .2 c jO 00 VO 3 i I ^ 1 T3 C J bO C -q c " O 3 c-^ A M a u cT *r o u 4-t -< D z "c I c 1 1 gi "S< E w -o U 1 C '^2 u In ^ J3 1 u ^ S Js M< 3 S " "On CL, 8 o B- CU i! -Q "* c 3 u ** *^ en *T *% M M fcfl i *7 M U *"* c u t>^ CO U "o. C HOI O c OT u JB'C i. C 2 C t^, (*, Ja 3 -a c o 4;"c g '^ S* T3 s * O 4-* C t Ju 2" J2 H, 1 t ji ii T3 C C C rt 1 ts "2 Hs 3 ^^ g c -o M C ^ j to c oo 2 1 g M c it *l '7 U-) -a c 15 1-1 1 s" 11 1 u '&. Q .rv X u shots, smashed inden eked. ^ ;j y ^en li shots, cracked y-in a 'i c | S 5 "H-, 8 c c 2, u s>. M J3 oT rt !.! w I! 18 11 -C 4J w " J3 - bO > o c C 1 1 C oo c CD c a" shot, struck junction < a vertical rib broken shots, smashed a piec j 2 bolts broken. H 2 vr> g ts o m^ M C CO M rt -3 u u V << imler. Ibs. Ibs. feet. tons. 8 7 1600 I '0 I -0 5-0 Ibs. Ibs. Ibs. 7 118 54 390 47 93 2253 2 64 1-87 9 35 8 '35 176 446 7 140 1964 3 c2 2- 4 6 12 3^ 9 152 198 502 IOO 202 1/34 3-40 3-13 15-65 10 1 68 220 555 '3 1 273 1565 3'75 3 82 19 10 ii 185 242 611 174 3 66 1422 *;.j 4 65 3J 12,34567 8 9 10 In exhibiting this table before the Royal United Service Institution (Jour. R. U. S. I., June, 1862), Mr. Michael Scott said: "Column 1 gives the bore of the gun in inches ; column 2 gives the weight of the shot which may be fired with a velocity of 2000 feet per second; column 3 gives the weight of the shot which may be fired at the velocity of 1750 feet per second; and column 4 gives the weight of the shot which may be fired at the velocity of 1100 feet per second. The next column gives the weight of a sphere of the diameter stated in the first column ; the next is the weight of an elongated shot of two diameters' length, but not solid, hollow behind ; the next gives the velocity of that elongated shot ; and the next gives the force of the 1 76 ORDNANCE. 222. ADVANTAGE OF SINGLE HEAVY SHOT OVER SALVOS OF LIGHT SHOT. In so far as it is intended, not to punch armor, but to shatter it in the highest degree, one heavy shot is more effective than a very much greater weight of light shot. Commander Scott says* on this subject : " The size of the gun is of vast importance, more than is generally assigned to it, and for this reason 20 guns, each a 1-pounder, are fired at a target of iron 1-J-in. thick, and produce no effect ; one gun, a 20-pounder, is fired and smashes it, the velocity in both cases being equal in both cases the same amount of metal is used, and on this principle an ofiicial record of experiments at Portsmouth states that one 6 8 -pounder produced more destruction than five 32-pounders. Arguing from this, it appears that one 150-pounder is more effective than ten 68-pound- ers, one 330-pounder is equal to seven 150-pounders, and a broad- side of three 330-pounders is more destructive than 10J Warriors.' 1 ' 1 On this principle, Commander Scott constructs Table 30. 223. The effect of a salvo, however, is very much greater than that of the same shots fired consecutively. And while the con- struction and convenient mounting of 300-pounders, for instance, present some serious difficulties, the effects of their shot may be approximately realized by taking more pains to concentrate a simultaneous fire from such guns as w r e have. blow, that of the 68-pounder ball, taken at 70 pounds in round numbers, moving at 1600 feet per second, being taken as one. " The principle upon which this table is calculated is very simple; but it involves a great number of figures. I have stated publicly on previous occasions, and I do not know that it has ever been disputed I do not know that it can be disputed, because there does not seem to be any dispute whatever with respect to the theory, namely that the power of the shot is the vis viva of the shot, the living energy, the weight multiplied by the square of the velocity. If that be so, then the only other element is the diameter of the gun. The force of the blow (column 8) and it is somewhat important varies very considerably. The argument is this : assuming wrought-iron, in the first place, and assuming that wrought-iron is three times as strong as cast- iron, that without straining the metal of the gun more than the metal of an ordinary G8-pounder is strained by firing a 70-lb. shot at 1600 feet per second, this is the effect. These numbers represent the force of the blow, or the effect produced by the shot from these varieties of gun. * * * It is quite irrespective of charge. The question has nothing to do with the quantity of powder It is a relative question riot an absolute." * Jour. Royal United Service Inst. June, 1863. REQUIREMENTS OF GUNS ARMOR. 177 to O - compared with a small detached plate of iron resting on short sticks of backing with- FIG. 122 D. Horizontal section of the 'Warrior's armor. out lateral or vertical support, and without a convex and continuous structure of ribs, bulkheads, and decks, in the rear. * A writer in the Edinburgh Revieiu (April, 1864), who is obviously not prejudiced in favor of English Ordnance, expresses what is certainly the common although not the universal sentiment of England with regard to American Ordnance. After the Dahl- gren and Rodman 11 and 15-inch guns and the Parrott 100-pounder have endured the thousand test rounds, and in view of the unprecedented scientific accuracy with which the figure, material, and fabrication (hollow casting, and cooling from within), of the Rodman and Dahlgren guns have been perfected, the writer referred to re- marks as follows: "The Americans appear to have a natural predilection for what is big, and they have applied themselves to the production of huge guns, made on every variety of pattern, with very little scientific uniformity and direction. If we are correctly informed, none of these guns have shown that durability which is essential to perma- nent service, nor have their effects corresponded to the cost and labor bestowed on them." f The ordinary projectile of the Parrott 10-in. gun weighs 250 Ibs. REQUIREMENTS OF GUNS ARMOR. 189 cent, of the penetrating effect of the lOJ-in. Armstrong ball with 50 Ibs. of powder, this effect being, according to all authorities, as the weight multiplied into the square of the velocity. Inasmuch as a spherical shot always breaks a hole larger than its own diame- ter, the resistance to all these shots would not very materially differ on account of their small differences in sectional area. The greater part of the work is undoubtedly done before the ball gets half way through the plate. The 11-in. shot has been fired through a number of 4^-in. plates backed like those of the Warrior but the quality of the iron was in some cases very inferior for plates. The target (200), compared with the English plates (212 to 216), is a sufficient illustration of this fact. High steel is certainly an invaluable material for many uses, but it makes the worst possible armor. Hard iron of high tensile strength resembles steel in this particular. The plates struck by the 11-in. shot exhibited their unfitness by cracking all over, and they sometimes actually crumbled into small pieces where they were struck.* Other American 4^-in. plates, of better quality, have not been completely punched by the 11-in. shot and 30 Ibs. of powder (214). Quite recently, the 15-in. gun has been found capable of en- during 60-lb. charges, which give a velocity of nearly 1500 feet to its spherical projectiles, enabling them to completely punch targets much thicker than the sides of the Warrior. The follow- ing are extracts from the United States Navy Ordnance Instruc- tions for 15-in. guns : " /Solid shot should always be used against iron-clads, and with 50-lb. charges, but never fired on any other occasion. "At close quarters say 50 to 150 yards 60 Ibs. may be used for 20 rounds of solid shot. " Cannon-powder only should be used, as 35 Ibs. of this kind * This defect in American thick plates is admitted, and can be remedied. The pro- longed and costly experiments by which hard iron was proved inadequate in England, ought not to be repeated in America. At the suggestion of the author, Admiral Dahlgren some time since sent for a number of English sample-plates, for target prac- tice, that he might more accurately compare his own with foreign guns. 190 ORDNANCE. O IP o 00 oo ft! - . i ! 00 00 PH c 14* ^-rr- c H Jt.s.s S c J" >c|ao."S J ^'o 5 ^ ^ a J2 "^ . u "H " e ae.s M "H. _, g rt "^* C O M 03 g "a. In *J ^ -~ -cL ^^5 "a. ^ .2 ^ <4 A *H a 1 .S ^' a 4 j C5 '"" C bo _C g < ' O 1 .2 u "2 1 S,.s Warrior tai i i i s "* OO 1-+N M w"^ "^ 4* c ^ ~elS "15 o 4^c " *: 3 e i e' & to 2: S bo- u *- C3 U c (B 2 ) * s .s bO . -0 -*M fS ti I | c VO oo >-^ s^ 'ri! s i = P tri Q 15 II I'Jili ^ i &< 1, ti S *? ^o, I 'A 1 f I 1 eo oo ^ ^ oo O ! f + 4-1 1 jl 1 '5 1* bO bO C C 15 15 bO e bO C 15 .S " "< 'c ~ i ' 'S T^ ^" r4 H fl "c \ J5 U bo O < t. j . i l . "S, rt u ^ ID ti !i V "w V ="J bo C | ^ "1 ja to JS rt -^ "M w bO 2 s,| 60 ^ I i i .H o r^ 1 3 i 5 5 5 If "5-s 3 ^ li i o rt I a a-S 4J N* bo bO bo bO O 0) OT II o S C O M 1 ."2 c c -3 .2 e8 W 1 n 6 Q a* 3 ,<3 C i ||5 o 3- i? oo 0^ & M M 00 O oo ro c< to J I Range in yards. 1 o o 8 & 8 i 5 8 1 1 * : : 1 : oo a 1 J g o> 1 i2 J3 A c B 4 1 2 Qt 2 J5 .2 42 RARACTER OF Gl Rodman smoot Armstrong rifle Horsfall smoot bo bO ^ C 2 ' 4_t o Q G e o 2 1 5 i u 'C -C S H y t C ^ ^ > I c B c C "7 Q i 15 u- m m o' E N4 M M |^ o ^ . 4 ft ON o REQUIREMENTS OF GUNS ARMOR. 191 i S C 13 C 13 a C/3 1 J ^ f .2 o 1 | I 1 13 <3 c ^ "S> .2 g X > .^ S (4 M 9 " J IS Jss '-i S* 4J i i ca - i 1 | G CL & -q ^ c U if i M "S, c -3 ** " js a H r ^^ i* *U -o n T3 C rt .S U) 3 O M 60 ^_ 2 OT w o "S "S c- .. R S "o 2 'c' " -a > ^ C 3 o OJ M X _Q C O "* . i g 15 T3 Q 5 C* S *' rt O OJ s - vt g> rt -* ja 'S T3 c i 5 g ^ . g | O S 3 ^ ! c rt r ." ^ .. ^ ^ a" 1 1 '>-'' u 15 r - s> 2 J c 1 4J u .2 2 ^T T 4) N o oo ^ *5 "o ** 2* .2 ^ "3 c 5 "2 iT * 1 . 11 it 'i 15 "^ 1 N * 8 1 I c rt ill "E'i J _c f ^ *f rt O 1 ^ 1 1 1 i s I 03 3 T ! ^ 43 a. G' jq x !'.-2 'S, .^ "cL J3 S 00 - 3 *W) * J V* *^ j2 O- *^_ oo 3 i 3 g a ? ^ II iiijii ^ v^j c 5 7' 1 i i 2 * j r** .v 3 | * 1 SJ c 4- JO ^ c w _M "^ ^C i u y W) ~"* .4J -7 C X u C u SJ u I* ** ^ -7 ^,, g 2 J J a c 3 2 M r | M fl CO * ^VO ^00 O\ M r) M 192 ORDNANCE. gives a greater range than 50 Ibs. mammoth powder; and this charge of the latter cannot be burnt in the gun." 297. Conditions of Greatest Effect. The measure of the penetrating force is stated by all the authorities to be the weight of the shot multiplied by the square of the velocity at the moment of impact.* Referring to table (31), it will be ob- served that the 288-lb. Armstrong shell fired with 45 Ibs. powder, at 1318 feet striking velocity, went through a 5-J-in. plate ; while the 150-lb. spherical ball, fired with 50 Ibs. of powder from a simi- lar gun with, say, 1600 feet striking velocity, only went through a 4rJ in. plate and its backing. But it must be remembered that the gun was very much less strained by the latter shot. (239.) To produce a strain upon it equal to that of a 288-lb. shot with 45 Ibs of powder, the lOJ-in. Armstrong gun first made was fired with a 150-lb. shot and 90 Ibs. of powder, giving a velocity of 2010 ft. The work done by the 150-lb. ball at 2010 ft., as com- pared with that of the 288-lb. shot at 1318 ft., would be about as 6 to 5. While the 288-lb. shot, at 1318 ft. velocity, only penetra- ted a 5J-in. plate, the 275-lb. Horsfall shot, at only about 200 feet more velocity per second, smashed a 2-ft. hole through a 4^-in. plate and its backing. 238. CONDITIONS OF HIGH TELOCITY. MERITS AND DEFECTS OF SPHERICAL AND RIFLE SHOT. To insure a high velocity, the shot must be light. According to Professor Tread well, the strain produced by heavy and light projectiles, with a given charge, is as the cube roots of their respective weights, f and their velocities are inversely as the cube roots of their weights. * Commander Scott states (Journal Royal United Service Institution, April, 1862), that " a very high velocity seems to produce an effect far beyond what the formula velocity 2 x weight gives." f Mr. Michael Scott says, on this subject, in his pamphlet " On Projectiles and Guns," 1862: "Without at present attempting any investigation as to the pressure of the gas formed by the explosion of gunpowder, or the rate at which that pressure diminishes as the gas expands, it may be affirmed that the pressure required to pro- duce, in a given length of gun, a certain velocity, will vary as the square of the velocity, as is the case when a constant force acts; and, if the pressure be given, the weight to be thrown will be inversely as the square of the velocity. (P being the pres- P V 2 1 sure, M the mass, S the space, then = r 5 or P d V 2 if M be given, M a if REQUIREMENTS OF GUNS ARMOR. 193 239. The spherical shot presents the greatest area of any prac- ticable solid shot to the powder, for a given weight, and hence receives the higher velocity. P be given.) Therefore, if a shot of 140 Ibs. be fired from a 7 -in. gun, with a velocity of 1100 ft. per second, the weight which can be fired with the same strain upon the gun with a velocity of 1600 feet per second, is only 140 x o2 = 66 Ibs. Sir "William Armstrong said, in a discussion before the Royal United Service Inst. (Jour. R. U. S. Inst, June, 1862): "I will now endeavor to explain why it is that a rifled gun must be heavier than a smooth-bore, and, for this purpose, I will direct your attention to the longitudinal dia- gram which I have drawn (Fig. 123), showing the bore of a gun of 9 hi. in diameter, with a cartridge containing 35 Ibs. of powder, and measuring in length 17 inches, and FiG. 123. having a round shot placed before it weighing 100 Ibs. Now, if I were to rifle that same gun, and substitute for the round shot a rifled shot of twice the weight, then it must be clear that, the powder having a greater mass to move, the gas will meet with a greater resistance, and will get up a greater pressure behind the shot, and it will be necessary to add additional strength to resist that extra strain upon the gun. * * * " But, it may be said, why not keep the weight of the shot the same, and reduce the bore, so as to enable the same proportions to be retained ? Now, we will try that alternative ; and here we have it represented. I have in this case taken the bore at 7| in., which, I believe, is approximately correct for a round shot of 50 Ibs. (See Fig. 124.) In this case, by making the projectile of the same proportion as in the other case, we make its weight 100 Ibs., or the same as the sphere in the other case. Now, to apply the same cartridge the same quantity of powder because that is the con- dition, the area of the bore being only one-half what it was before, it is necessary to make the cartridge twice the length, as represented here. Hence, therefore, although the circumferential area exposed to the pressure of the powder is diminished in the proportion of 7-J- to 9, yet the longitudinal surface is increased in the proportion of two to one ; and, consequently, we have a far greater surface exposed to the pressure of the gas at the first instant of ignition in the one case than we have in the other. The strength of the gun must therefore be continued farther forward. But not only that, after the shot of the smaller bore has travelled through once the length of its FiO. 124 3 4 Ibs .jf 501Ls J cartridge, the length of bore filled by the gas will be twice 34 inches, or 63 inches; whereas, when the other has travelled through once the length of the cartridge, so as 13 194 ORDNANCE. 34O. The strain on the Parrott 6'4-in. gun, as measured by- Captain Hodman's instrument, at West Point, was about 86400 Ibs. TABLE XXXII. VELOCITIES OF PARROTT (6-4-lNCH) 100-PouNDER BY BENTON'S ELECTRO-BALLISTIC PENDULUM, MAY 1, 1862. Elevation. Charge, Ibs. Projectile. Initial velocity. (Dupont 7) Weight, Ibs. Feet per second. 4-r 10 loo-lb. shell 1254 4* 10 loo-lb shell 1244 4i 10 8o-lb. shot 1374 41 JO 8o-lb. shot 1381 4i II 8o-lb. shot 1405 4i 10 3a-lb spherical shot papier- mache sabot 1819 T 10 Ditto 1829 4^ JO Ditto 1799 to give double capacity for the powder behind, it will only have travelled 34 inches ; and therefore we must bring forward the corresponding strength of the gun in the one case to 68 inches, and only to 34 inches in the other case. It is clear, therefore, that we gain nothing by reducing the bore, but rather the contrary." In the discussion last referred to, Mr. Bashley Britten gave the following illustra- tion on this subject: EFFECT OP EQUAL CHARGES IN LARGE AND SMALL BORES. (A.) ARMSTRONG 40-PotmDER. -12 inches.- Charge 5 Ibs. I Bore 4' Pressure on shot, 163 tons I Area 12'5 Ditto on gun 1964" , }- I Initial velocity. . . .1200 Shot, 40 Ibs. (B.) BRITTEN'S 50-PouNDER. ElFLED 32-PoUNDER SERVICE. Charge 5 Ibs. Bore 6-375 Pressure on shot Tons. 415 81-9 1204 i 45 \ 1209 2 Shot 50 Ibs t M ) Pressure assumed, 13 tons per inch. REQUIREMENTS OF GUNS ARMOR. 195 for the 100-lb. bolt, with the same quantity and kind of powder that gave 28000 Ibs. pressure for the 32-lb. spherical shot. So that the pressures were nearly as the weights. The velocities, as measured, were nearly with equal charges, inversely as the cube roots of the weights of the shots. 241. Captain Fishbourne, in discussing the merits of rifled and smooth-bore guns,* mentions the low velocity of the rifle-shot and its greater strain upon the gun as serious defects, and then refers to the merits and possible improvements in the smooth- bore, as follows : " Now I only propose that the causes of the errors in round shot shall be directly removed. These are: an 'undue amount of windage, imperfect sphericity, and absence of homogeneity. Table 33 shows the effect of the reduction of windage : TABLE XXXIII. EFFECT OF REDUCING WINDAGE. Weight of 1 Hevation NATURE OF GUN, Length. Windage. powder 1 2 5 ft. in. Ibs. parts of inches. yds. ^22-pounder, c6 cwt Q 6 10 233 700 1 1 30 1064. 8 o 6 I 7 C 731 32-pounder l( 17 C #71 r 56-pounder, Monk, 97 cwt II 16 175 t93 34 2200 Nil * From Aide Memoire to the Military Sciences. t Hand-book for Field Service. $ Height above plane, 15 feet Height above plane, 8 feet. j From Royal Naval Official Eanges. Table 34 shows the ranges and particulars of Horsf all's 280- pounder; this table shows the point-blank range as compared * Jour Royal United Service Inst., June, 1862. 196 ORDNANCE. VO 00 >^ s, 3 v2 [li r i .Si -a > u . 53 a J* "w u r" ffi O ^0 3- < J; -a ^ ^ ?! ifS J5 a c S) J3 W Jj "c u ."2 o o O VO 2 v S u "c o c o ^ "a. ?* S 2*2 u -o c o O "n o o b JB a s a "c c -a S" 1 ro g ' O n o C*3 o < o S2 'c o fc a s x 53 M QQ X ' 5 SI 00 ijj ^ t! <*; o o M < 1 1 ta. W qj M H g M H C3 tq g g 3 >3 8 o g K g Sft. w !S . o r REQUIREMENTS OF GUNS ARMOR. 197 with those of the service 68-pounders and Armstrong 110-pounder. The 68-pounder appears to a disadvantage ; its range was taken at a height of only 8 ft. ; the other two, Sir William Armstrong's at 17 ft., and Horsfall's at 20 ft. This would make a considerable difference in their range against that of the 68-pounder. The time of flight of Horsfall's smooth-bore is about half that of the other, and shows, abundantly, to what perfection smooth-bore guns may be brought. The windage in the 68-pounder is '198, that in Horsfall's is only *08. 242. " In the field it is admitted that the difficulty of judging distances, and other disturbing circumstances, are such as to con- fine the ranges of projectiles for military purposes to 2000 yards ; afloat, the disturbing causes, which are constant, are greater, from which the various movements in rifle-sights become causes of error ; therefore the most useful ranges cannot be greater than those obtained by Mr. Horsfall's gun at little above point-blank, and with powder only one-sixth the weight of shot, while the elevation of rifle-guns is considerable for the same distances. Then, as the angles of descent are great, the chances of striking an object are scarcely worth the powder used. The smashing effect of this gun would be three times that of the 150-pounder. " The former conclusion Sir H. Douglas arrived at some time since, for he says f The main principle which should govern our choice of naval guns is, to prefer those which, with equal calibre, possess the greatest point-blank range.' This was the correct view to have taken before the introduction of iron-coated ships ; since that, we have no choice, as no other guns will be completely effec- tive against iron plates, if against other ships either 243. " Imperfect sphericity, another cause of error in round shot, may be removed in working scrap-iron into wrought-iron shot, made requisite by the introduction of iron-plated ships ; a nearer approach to homogeneity will at the same time be made, while the expense of such will still be far below the cost of any of the elongated shot. " Since this paper was written, I have seen a pamphlet on this subject, in which the value of smooth-bore guns and improved 198 ORDNANCE. shot are set forth. It is by Mr. M. Scott, C. E., and shows the turn which the public mind is taking. 244. " To the extent that we have adopted rifle-guns, to the exclusion of smooth-bores, for the navy, we have given up the sub- stantial advantages of low trajectories, straight ricochet, smashing force, simplicity, and economy, for the very occasional advantages of long range. Therefore, for efficiency, no less than for economy, we must revert to the smooth-bore in principle, and invest talent and money to develop its merits. 24o. " But rifle-guns and elongated shells, especially of small and medium calibre, have decided advantages, because of the greater quantity of powder these shells are capable of containing, and long range is also sometimes very important for the support of troops and for breaching purposes ; we should therefore endeavor, if possible, to combine the advantages of the round-shot with those of the elongated, in one description of gun; but even for the simplicity which this would bring with it, no sacrifice of initial velocity is admissible. So that, unless a mode of rifling can be found that will not involve undue windage, we must have both descriptions of gun, in numbers proportionate to the relative im- portance of each : little windage, then, must be the ruling qualifi- cation in the selection. Such is that proposed by Captain Scott, R. N. ; such is that used by the French in their rifle-gun that admits of the use of round balls. It should be a muzzle-loader, simple of construction, strong, and as little liable to get out of order as possible ; for neither ships nor fleets can take factories to sea with them." 246. The spherical shot, Fig. 125, as com- pared with the flat-fronted shot, Fig. 126, is EractiirTTTspherioal m re Hke V tO WaSte P W6r in ^elf-destruction. shot upon striking When it strikes a plate, the mass c is directly arrested and supported ; but the overhanging mass a a, having no support, often breaks away, and having failed to impart its momentum to pact. Ordnance, and Gunnery. Benton. 1862. f This subject is more fully considered in the chapter on Rifling and Projectiles. 200 ORDNANCE. TABLE XXXV. EXPERIMENTS AT WEST POINT WITH LEAD SHOT AGAINST ARMOR UNDER THE SUPERINTENDENCE OF CAPTAIN BENET. (From Official Reports.) I. JULY 29, 1862. A lead shot, in form a right cylinder weighing 32 Ibs., with an india-rubber sabot ; charge, 8 Ibs. mortar powder ; fired at a solid wrought-iron plate 46 in. long x 23 in. wide, 4.^ in. thick, inclined 4^ from a vertical. Distance from the muzzle of the gun, 92 ft. The plate was strongly supported by timbers. The lead shot struck the plate in the centre, penetrating i in., the indentation being 8 in. diameter. The plate was bent, and dished, and cracked in the rear clear across, and nearly through its entire thickness, besides short radial cracks. The back of the plate was bulged 2 in. to 3 in. The plate was overturned and thrown 10 ft. to the rear. II. AUG. 14. A 4o-lb. lead shot, a right cylinder in form, 5^ in. long x 5 in. diam- eter, with an india-rubber sabot 4 in. long charge, 8 Ibs. mortar powder was fired at a vertical target 5 feet square, made of 4 wrought-iron plates, each an inch thick (total 4 in.), bolted to oak timbers 6 in. thick, all propped by heavy logs, and situated 108 ft. from the muzzle. The shot went through the target and backing, and was found in the earth 10 ft. in its rear. The shot was reduced by its passage from 40 Ibs, to 22 Ibs. weight, preserving to a great degree its cylindrical form. The orifice was 5^ in. diameter. Pieces of the plates, cut off by the shot, were found beyond the target. III. AUG. 21. A cylindrical lead shot, of 40^ Ibs. weight, with india-rubber sabot 6 in. long, charge 10 Ibs., was fired at a vertical target 18 x 20 in., made of 12 half-inch plates (total 6 in. wrought iron), and bolted on 20 in. of oak by 16 bolts. The whole was backed by timbers and a stone of 3 or 4 tons* weight. Range, 103 ft. The shot struck in the centre, broke one plate, cracked the second slightly, broke 10 bolts, dished the target considerably, and made a total indentation of 3! in. deep x 8^ in. wide. The shot was flattened to the diameter of 9 and 1 1 in. Target and backing knocked out of place. IV. Lead shot, 40 Ibs.; 4-in. india-rubber sabot; charge, 9 Ibs.; fired at 109 ft- range, at 4^-in. solid plate, No. I., with about the same results. The target had been made immovable. Indentation, 6^ in. wide x l| deep. V. Cylindrical steel shot 50 Ibs., and 3~in. india-rubber sabot ; charge, 9 Ibs. mortar powder; fired at 4i~in. solid plate, No. I., at 109 ft. range. The plate broke square across. Indentation, i in. deep x 6 in. diameter. 68-lb. 8-in. ball. The initial velocity attained by 68-lb. bolts from the 110-pounder, with 16 Ibs. of powder, is 1433 ft. ; that of the 111-lb. bolt being 1307 ft. 249. A very short rifle-bolt is unfit for long range ; but this is not required in iron-clad warfare. (See Rifling.) (254.) A valid objection against short bolts is their large cross-sectional area in proportion to their weight, i. e., loss of velocity. In fact, they possess no advantage over the round steel ball, except greater accuracy, which is hardly necessary at very short range ; their dis- REQUIREMENTS OF GUNS ARMOR. 201 advantages are, greater friction in and strain upon the gun. Hol- lowing out the rear of the shot is the method usually proposed to lighten it. This renders it more liable to fracture upon striking, if it is not made of some extremely dense and tough material. And if the balls are thin enough to reduce the weight much, they are liable to be sprung open by the powder, thus increasing the friction and strain on the gun. Hollowing out a 7-in. 100-lb. bolt through | of its length, so as to reduce its weight one-half, would leave the walls only about f in. thick. The sub-calibre system, Fig. 127, which has been adopted by Mr. Stafford (see chapter on FIG. 127. Stafford's sub-calibre shot. Rifling and Projectiles), and modified by others, appears to be the proper system of firing the best punches at the highest velocities ; for while the area pressed by the powder may be as large as that of the spherical shot, the area that strikes the plate may be smaller than that of a full-calibre rifle-bolt, the weights being the same in each case. But the sub-calibre system will not allow the use of the most effective shells; and this modification of it does not reduce the area of the shot to the air, as well as to the target. The wooden covering of the shot is only torn off when the shot enters the armor. 2oO. An elongated shot, in the present state of the art, must be fired from a rifle, in order to go end on and accurately.* Rota- ting the shot takes power, especially with the Armstrong system of rifling, but need not greatly reduce the velocity. * See chapter on Rifling and Projectiles. 202 ORDNANCE. The Armstrong and Whitworth guns were rifled for two rea- sons: First. To carry punching-shells. Since a solid sphere will break upon striking armor (246), the thin walls of a shell and its greater overhanging weight would insure its being smashed. Shells must, therefore, be elongated ; and being elongated, must be revolved about their major axes, in order to be kept end on, at least at long range. Hence the necessity of rifled guns. It is also held by Mr. Whitworth and others, that the spinning motion of an elongated bolt is necessary to keep it end on while passing through armor. 25 1 Second. The Armstrong and Whitworth guns were rifled for long-range fighting. The advantages of the spherical shot, considered above, refer to short ranges. The proceedings of the Defence Commissions, and the discussions on this subject in Eng- land generally, indicate a belief that iron-clad warfare will be conducted chiefly at long ranges, say 3000 yards. As far as this is the case, the rifle- bolt will have the advantage ; its velocity de- creases much less rapidly than that of the sphere, because it pre- sents but about half the area (as ordinarily proportioned) to the resistance of the atmosphere for a given weight. By experiment, the 68-lb. 8-in. ball loses 25'7 ft. at 30 yards' distance from the gun, 91 ft. at 100 yards, 157 ft. at 200 yards, and 581 ft. at 1000 yards, the initial velocity being 1579 ft. The Armstrong 111-lb. 7-in. bolt, with an initial velocity of only 1125 ft., has, at 1000 yards, the same velocity as the 68-lb. ball, viz., 981 feet. (See Table of Yelocities.) 252. Sir William Armstrong said, before the Defence Com- mission :* " I am now making a gun (30) adapted for a shot twice the weight [of the 10^-inch]. If we used that gun with the same relative charge, it would be fired with 100 Ibs. of powder ; the round-shot for that gun would weigh 300 Ibs. With such a gun in the smooth-bore state, we may expect to produce, at 1300 yards, as great an effect as was obtained against the Warrior target, in * Report of the Defence Commissioners, 1862. REQUIREMENTS OF GUNS ARMOR. 203 the late experiment, at 200 yards (227). The rifle-shot for the same gun will weigh not less than 600 Ibs., and would produce, at 3000 yards, the same effect as the round-shot at 1300 yards. I calcu- late the velocity of impact to be 1200 feet per second for the 300-lb. round-shot, at 1300 yards, and 850 feet per second for the 600-lb. rifle-shot, at 3000 yards." 2o3. RANGE IN IRON-CLAD WARFARE. Effective iron-clad fighting will undoubtedly be done at short range. There are, cer- tainly, many arguments to the contrary, of which the following, by Captain Noble, R. A., is an example: "But by what right is it assumed that naval actions are to be fought at short distances for the future ? Is it because it suits the smooth-bore guns ? No doubt it would have suited the Macedo- nian much better if she had fought her action with the United States at short distance rather than at long ; but the American would not follow suit, and by keeping at a distance, and taking advantage of his long-range guns, he gained the day. Exactly the same thing occurred in the action between i\\Q Essex and the Phoebe, except that in this case the British captain took advantage of his long-range 18-pounders, chose the distance that suited his guns, and in a very short time compelled his enemy to surrender. In this action, the 32-pounder carronades, which formed the armament of the Essex, would have been very formidable at short ranges, but they were almost u-seless at the distance at which the action was fought." 254. But it is evident, First, that sufficient velocity to punch armor cannot be obtained at long range, even from rifles. Only the comparatively thin Warrior and Minotaur targets have as yet been punched, by the best guns, at short range. Second. Sufficient accuracy of aim* to hit small turrets, the low sides of Monitors, or even the high sides of casemated frigates, when these objects are rapidly changing position and direction by steam, can hardly be expected, especially when with low veloci- ties, high elevations, and curved trajectories, shot can only drop upon the object aimed at (242). * "Out of the entire programme," firing at 1000 yards at the Warrior target "with the 13'3-in.-gun and the 10-5 in.-gun, only 1 shot struck the 14 ft. target, the others grazing the target, or missing altogether. And yet the guns were laid by the most experienced Shoeburyness gunners, and the target was moored in smooth water." The Dock-yards, Ship-yards, and Marine of France. Barry, 1864. 204 ORDNANCE. Besides, opposing vessels will be trying to ram one another. The Monitor and the Merrimack were hardly a dozen yards apart daring the greater portion of their fight, and were several times in contact. The old sailing-vessels were so embarrassed by sluggish locomo- tion and vulnerable sides, that the victory was simply a question of the longest arms. But it is hardly to be expected that steam- rams, clad in modern armor, will do either one of three things : 1st, they will not stand still to be shot at ; 2d, they will not waste time by firing at a distance at which their shots will make no impres- sion on the enemy, while they have the power and appliances for other manoeuvres ; 3d, they will not lose the opportunity of smash- ing the enemy's side in with their prows. One or the other vessel can do this ; whichever attempts it, makes the battle hand to hand. So that, irrespective of the calculations of artillerists, their missiles will not have far to go ; and they will not be likely to go far after striking, if much power is wasted on projecting heavy masses and spinning them at high velocities. *!. At very short ranges, it is probable that well-balanced elongated shells and light elongated shot would go end-foremost, with sufficient accuracy. (See chapter on Rifling.) For mere punching, such ranges would give the spherical shot nearly every advantage. Hence a large number of rifle-guns are not required for mere iron-clad warfare. Still, there may always be some work to be done camps, earthworks, and towns to be shelled, and ma- sonry to be penetrated, at 3 to 5 miles' range and still more work at 300 to 1000 yards. So that some rifle-guns for ordinary shells, for light punching-bolts, such as Stafford's sub-calibre shot (249), and for armor-punching shells, should form a part of every ship's armament. 256. Where the number of guns is limited, as it must be in small turrets and casemates (room for guns must be limited in well-protected ships of practicable size), it is important to utilize all guns for all purposes. This would be accomplished by a sys- tem of rifling and rifle projectiles that would neither weaken the gun nor impair its efficiency for spherical-ball firing. REQUIREMENTS OF GUNS ARMOR. 205 If the bore for smashing and racking purposes were of consider- able diameter, it would involve the use of a full-calibre rifle-shot of large diameter. This shot would have to be very short, in order to bring a safe strain upon the gun, and would then be unfit for very long ranges. Its diameter would also be too great to punch thick armor. So that the sub-calibre system (249) would seem to be indispensable to the perfect utilization of one very large- bore gun for both spherical and elongated projectiles. TABLE XXXVI. WORK DONE BY DIFFERENT GUNS, THE 68-PouNDEE BEING TAKEN AT UNITY. NATURE OF GUN. Charge. Weight of solid shot. Work done at 1000 yards. Work done at 1000 yds. by 150-pdr. rifle in comparison with 63-pdr and 150-pdr. smooth- bore at 200 yards. Ibs. Ibs. yds. 68-pounder, smooth-bore ... 16 66 I -OO I io-pounder. Armstrong 12 ill I 6q Ditto. H in I. 9 8 I5O-pounder, smooth-bore. ... 40 150 3' 2 4 4-O I ^O 5. 24 68-pounder, smooth-bore... 16 66 I oo at aoo yards. I co-pounder, rifle 40 I CO 2-50 at 1000 yards. I5O-pounder, smooth-bore 40 150 I -oo at aoo yards. 150-pounder, rifle 40 15 0-88 at 1000 yards. 257. SHOT OF LARGE DIAMETER. A large diameter of punch- ing projectile is desirable for several reasons : 1st. To punch a large hole, thus driving a great volume of splin- ters into the ship, or making a dangerous leak, if the shot is at the water-line. 2d. To allow shells of practicable length to carry high bursting charges, and still have thick, strong walls. 3d. A spherical shot of large diameter has a greater weight, in proportion to its cross-sectional area, than a small spherical shot ; in. other words, the weight increases as the cube of the diameter. 206 ORDNANCE. while the resistance opposed by air increases as the square of the diameter, and that opposed "by iron as the diameter. So that the large shot has the greater range, penetration, and accuracy. 258. RANGES OF LARGE BALLS. Mr. Clay says, as to the range of the 13-in. Horsfall gun :* " Up to 12 of elevation, the monster gun has the most decided advantage, more especially in shorter ranges ; after 12 the rifled gun takes the lead. * * * At point-blank, the 68-pounder (smooth-bore) ranged about 310 yards, the Armstrong (110-pounder rifle) about 350 yards, and the monster gun about 600 yards. At 1 elevation, the 68-pounder ranges 730 yards, the Armstrong to 670, and the Horsfall gun reaches 1030. At 3 elevation, the 68-pounder ranges 1470 ; the Armstrong, 1330 ; and the 300-pounder gun, 1800 yards. At 5 elevation, the 68-pounder ranges 2000 yards ; the Armstrong gun, 1990 yards; and the 13-in. gun, 2430. At 7 elevation, the 68- pounder ranges 2440 yards; the Armstrong then reaches a dis- tance beyond the 68-pounder, and ranges 2570 yards ; the 13-in. gun ranges 2980 yards. At 10 elevation, the 68-pounder ranges 2930 yards; the Armstrong, 3470; and the 13-in. gun, 3530. At 12 elevation, the 68-pounder ranges 3200 yards. The Armstrong gun then takes the lead by a considerable distance, and ranges 4040 yards; and the 13-in. gun ranges 3870 or 3880. * * * The time of flight for the Armstrong 100-pounder, at point-blank, is T 8 o second, and for the monster gun, 1 minute and 1 second ; at 10 elevation, the Armstrong takes 12fV seconds; and the monster gun 12 T V seconds; the monster gun ranging slightly farther in T 2 o of a second less time ; therefore the average velocity of that shot must have been slightly superior to the Armstrong. * The 13-in. gun shows great superiority in this comparison (the proportionate weight of powder and shot). In the 68-pounder, I think the charge was 16 Ibs. of powder to 66 Ibs. of shot about -J- ; and the proportion of powder to the shot in the 13-in. gun was 50 Ibs. of powder to 282 Ibs. of shot about f" The practice with the 15-in. Rodman gun shows the following * Report of Defence Commission, 1862. See also Table 34. REQUIREMENTS OF GUNS ARMOR. 207 results : "In firing for accuracy, with the minimum charges men- tioned (35 Ibs.), at a target 2000 yards distant, with 6 elevation, the shot (328 Ibs.) struck the ground about 8 feet below the level of the gun, at (5 trials) 2017, 1937, 1902, 1892, 1873 yards. The lateral deviations were 1, 3, f , 5 yards to the right and 5 yards to the left, showing at this range of 1} miles a very great accuracy as regards horizontal deviations, to test which the firings were made. The vertical deviations were probably due to varying initial velocities, or perhaps to some difference in the weight of the shells fired. Had the shot been intercepted at the target by a vertical plane, they would have been found included in a verti- cal extent of about 6 yards, not much over the height of a three- decker. " The ranges with maximum elevation of 28 35' shells of 334 Ibs. and 50 Ibs. of Rodman's perforated cake-powder were as fol- lows : 5298, 4950, 5375 yards. "With 40 Ibs. large-grained powder they were 5435, 5062, 5730 yards, and the time of flight about 37 seconds. With 10 elevation and 40 Ibs. large-grained powder, they were 2700, 2900, 2754, 2760 yards. These ranges do not exhibit any decided advantage of those obtained from the 10-in. gun up to 10 elevation. Beyond that elevation the gain is considerable, and may be estimated at about 600 yards for the elevation of 28 35 '. With 39 elevation, and a charge of 40 Ibs. of large-grained powder, it is probable a range considerably beyond 4 miles might be obtained."* The ranges of the 15-in. spherical shell, according to late experi- ments with the navy gun, are as follows : Charge. 1 2 3 4 5 6 7 yds yds. yds. yds. yds. yds. yds. 35 Ibs. (cannon) 620 920 1200 1470 1700 1900 2100 50 Ibs. ( do. ) 1300 1920 2180 2420 The great range and accuracy of the 9*22-in. Armstrong smooth- bore (Table 37), as compared with the smaller smooth-bore is attributed partly to the greater proportionate weight of the shot to the resistance, and partly to the reduction of windage. * "Notes on Sea-Coast Defence." Gen. Barnard. 1861. 208 ORDNANCE. TABLE XXXVII. RANGES, &c., ARMSTRONG MUZZLE-LOADING SMOOTH-BORE 9-22- INCH 100-PouNDER. LENGTH, 10 FEET; WEIGHT, 13514 LBS.; CHARGE, 33 LBS.; WINDAGE, 0*065; MUZZLE, 17 '5 FEET ABOVE PLANE No of Elevation as to RANGES. Mean dif- Mean ob- Mean re- rounds. point of im- pact. time of flight. Min. Max. Mean. ference of range. served deflection. duced de- flection. / sec. yds. yds. yds. yds. yds. yds. 5 I 20 2.36 919 1024 980 38-0 !l 1.4 20 2 14 3.18 1306 1598 I 43 61.5 5-8 5' 1 20 5 8 7-75 2314 2584 2409 26.7 15-2 7-4 20 10 6 i3-4i 334 3 6 95 35H 88-5 3 2 '3 23.8 9 22 4 24-1 2 C -4. 4748 4923 4833 C2C3 62.2 122-4 85-2 -" y *5 *r D- 6 :) 5 The gun was perfect after these rounds. The greater accuracy of the large gun as compared with the 32-pdr., with proportional charge, is attributed to the greater weight of the large shot for a given resisting area, and to the reduced windage, viz., 0-014 of the area of the bore, that of the 32-pdr. being O'OGl of the area of the bore. . STRAIN OF LARGE BALLS UPON THE GUN.- On the other hand, the large spherical shot presents the smaller area to the powder for a given weight, and thus receives a lower velocity. A velocity that would insure its penetration, would also increase the strain upon the gun. As to the whole subject of strain upon the gun, by large and small shot, Professor Treadwell says :* " It is perfectly well known that, if we have a pipe or hollow cylinder of say two inches in diameter, with walls an inch thick, and if this cylinder will bear a pressure from within of 1000 pounds per inch, another cylinder, of the same material, of 10 inches in diameter, will bear the same number of pounds to the inch if we increase the walls in the same proportion, or make them live inches thick. A cross-section of these cylinders will present an area proportional to the squares of * "The Practicability of Constructing Cannon of Great Calibre," &c. 1856. REQUIREMENTS OF GUNS ARMOR. 209 their diameters ; and if the pressure be produced by the weight of plungers or pistons, as in the hydrostatic press, the weight required in the pistons will be as the squares of the diameters, or as 4 to 100. " Now carry this to two cannon of different calibres, and take an extreme case. Suppose the calibre of one to be 2 inches in diameter and the other 10 inches, and that the sides of each gun equal in thickness the diameter of its calibre. Then, to develop the same force, per inch, from the powder of each gun, the inertia of the balls should be as the squares of the diameters of the cali- bres, respectively ; that is, one should be 25 times as great as the other. But the balls, being one 2 and the other 10 inches in diameter, will weigh 1 pound and 125 pounds respectively ; the weights being as the cubes of the calibres. Hence, each inch of powder in the large gun will be opposed by 5 times as much in- ertia as is found in the small gun. This produces a state of things precisely similar to that of loading the small gun with 5 balls in- stead of 1 ; and although the strain thrown upon the gun by 5 balls is by no means 5 times as great as that by 1 ball, there can be, I think, no doubt that the strain produced by different weights of ball is in a ratio as high as that of the cube roots of the respective weights.* This would give, in the example before us, an increase of from 1 to 1*71, or the stress upon the walls of the 10-inch gun would be 71 per cent, greater than upon those of the 2-inch gun. " The foregoing statement and comparison, however, do not * " Hutton inferred that the velocities of balls of different weights with the same charges of powder, were inversely as the square roots of the weights; and Captain Mor- decai, in his excellent book of experiments, makes the same inference. This would give no increase to the force of the powder, and must be impossible ; and T find, from com- paring their experiments, and computing the forces developed by the same charges of powder with shot of different weights, that the forces are almost exactly as the cube- roots of the shot. Thus Button's experiments with balls of 1*2 Ib. and 2*9 lb. r veloci- ties 973 and 749, give forces almost exactly proportional to the cube roots of 1-2 and 2-9. Captain Mordecai's experiments with balls of 4/42 Ib., 9'28 Ib., and 21 Ib.,. veloci- ties 2696, 2150. and 1520, all furnish, by computation, forces very nearly proportional to the cube roots of the respective weights of the balls. Every one knows that a small increase in the weight of the shot in a fowling-piece increases in. a sensible degree the recoil, and the stress upon the gun. This is so universally received as true by ordnance officers, that it is a common practice to use two or more balls, instead of an increased charge, in proving guns." 14 210 ORDNANCE. present the whole case ; for they are made upon the supposition that the charge of powder, in each instance, is as the square of the diameter of the shot, or that the cartridges of the 2 and the 10-inch guns are of the same length. This, if we take the charge of the small gun at -J- of a pound, would give but S-J pounds for the large, or T V of the weight of the shot. The velocity obtained from this charge would produce neither range nor practical effect, and to obtain these results, that is, 1600 feet a second, we must either in- crease the force through the whole length of the gun to 5 times that required for the small gun, or, the force remaining the same, we must provide for its acting through 5 times the space. Neither of these conditions can be practically accomplished. However, by an increase of both the charge and the length of the bore, the result may, in the limits under consideration, be attained. Thus, taking the large bore, if we double its length and make the car- tridge 5 times as long, increasing the weight from SJ to 41 f pounds, or perhaps, having an advantage from the comparative diminution of windage and the better preservation of the heat, with a charge of from 30 to 35 pounds, we may obtain the full velocity of 1600 feet a second. But this, again, increases enor- mously the strain upon the gun. " It does not appear obvious, at a first view, how an increase in the charge should increase the tension of the fluid produced from it, if the cavity enclosing it be proportionably enlarged. If a steam-pipe a foot long will sustain the pressure of a given quantity of steam, of a given temperature, a pipe two feet long, of the same thickness and diameter, will sustain the pressure produced by a double weight of steam from the same boiler. Why, then, should the pressure upon a cannon be increased by a double length of cartridge ? The difference seems to be this : with the steam, the pressure is as in a closed cavity ; with the powder, the tension depends upon the movement of the shot while the fluid is forming. Now, whether the charge be large or small, the motion of the shot commences while the pressure is the same in both cases, and before the charge is fully burned, and with the same velocity in both cases ; but with the large charge the fluid is formed faster REQUIREMENTS OF GUNS ARMOR. 211 than with the small, while the enlargement of the cavity by the movement of the shot is nearly the same in both cases. This destroys the proportion between the sizes of the two cavities, and the tension must increase faster, and become greater, from the larger charge. The law of this increase cannot, from the compli- cate nature of the problem, be stated with any reliable exact- ness ; but we may, I think, conclude, from the increased velocity of the shot, and many other effects, that the stress thrown upon the gun by different charges of powder, within ordinary limits, will not vary essentially from the square roots of those charges.* If, then, we increase, in the example under consideration, from a charge of 8-*- pounds to one of 32 pounds, the stress upon the gun, being as the square roots of these numbers, is raised from 2*88 to 5*65, or from '1 to 1*96. Having already increased the stress upon the gun, by the shot, from 1 to I'll, if we multiply these together, we have a total increase of from 1 to 3*35. That is to say, if, under the conditions here stated, we load a gun of 2 inches calibre with 1 shot and 1 of a pound of powder, and a gun of 10 inches calibre with 1 shot and 32 pounds of powder, the stress upon each square inch of the bores will be 3'35 times greater with the large than w r ith the small gun ; when at the same time, if the walls of both have a thickness proportional to the diameters of the calibres in each, the large gun will be incapable of sustaining a greater pressure per inch than the small one. Even with a charge of 12 pounds of powder, the stress upon the large gun must be more than double that upon the small gun when charged with one-third the weight of its ball. * "Hutton gives the velocities of the balls as the square roots of the charges, and the experiments of Captain Mordecai, although giving the velocities of the larger charges somewhat below this ratio, do not wholly contradict it. This assigns to the charges an effect, or power, that is, pressure multiplied by the space, which is directly as the charge. Now this result cannot be produced, with the larger charges, wholly by the continuance of the pressure during the last part of the passage of the ball through the bore, although a large portion of it may be derived from that source; but there must be a great increase of the tension in the fluid during the first part of the ball's motion, and an equal increase of the strain upon the gun. It appears to me that the hypothesis stated above, and the ratio of force there assigned to different charges, are in perfect accordance with these and other experiments." 212 ORDNANCE. " The preceding examination does not, I think, present the dif- ficulties to be overcome in increasing the size of cannon as greater than they really are ; and although the results that I have arrived at are from extreme cases, and may be said to be mere deductions, yet they are deductions legitimately drawn from the most reliable experiments that have been made." (See also 221 and 238.) 260. One other consideration is involved in determining the diameter of projectiles. It has been stated that projectiles much less in diameter than the thickness of the iron target, are not likely to penetrate it, with the highest velocities at present attained ; so that the size of guns and projectiles can hardly be decreased below the present class of what we may call armor- punching guns the Wlritworth T-in., the Parrott S-in., and the Armstrong, Dahlgren, and Parrott 9 to lOJ-in. guns. 261. Merits and Defects of the System. The obvious dis- advantages of the " racking" system, by means of heavy projectiles at low velocities, are loss of power and loss of time. The veloci- ties of light shot, with a given strain upon the gun, are so high, that little power is wasted in distributed effect. When such a shot goes through a plate, it shears out a piece of the plate, in sub- stantially the same manner that a hand-punch shears a disk out of a sheet of iron laid on a wooden block. The block prevents the sheet of iron from being bulged, distorted, and racked bodily ; the inertia of the surrounding ship's side, as w r ell as the backing, prevent the plate struck by a projectile from being acted upon bodily. The hole is punched before there is time to bring the elasticity and ductility of the target into service. Whatever power the gun is able to stand, is concentrated upon the smallest possible area, and therefore meets with the smallest possible resist- ance, instead of being distributed to the crippling of a large sur- face and the vibration of the whole ship's side. Supposing heavy shot at low velocities to shake off a portion of the enemy's armor, leaving his skin bare, or to so smash and rack his side as to cause dan- gerous weakness and leakage : time perhaps hours may elapse before the fatal shell can be planted in the one case, or the fatal battering be inflicted in the other. Meanwhile, the enemy's fleet REQUIREMENTS OF GUNS ARMOR. 213 lias at least a chance to manoeuvre to its final advantage, or to fight its way to within shelling distance of a city. But the pene- trating shot accomplishes its whole work at a blow, if at all ; and since its whole work is concentrated upon the smallest area, that blow represents the maximum destroying power of the gun. If the velocity of a shot were infinitely fast, it would waste no power at all; if it were infinitely slow, and the shot infinitely heavy, it would utilize none ; it would simply push the ship bodily. Suppose, however, that the range is so great or the armor so resisting, that the strongest gun will not penetrate it. Racking is then the only resort; and since the small shot, intended to punch, wastes much of its power in fruitless local effect, it has little left for distributed effect. In such a case, the importance of a heavier and slower battering shot, in connection with the others, is obvious (267). 262. EFFECT OF PUNCHING-SHOT IN TURRETS. It is a common mistake to attach little importance to the effect of small solid shot, even if they do punch the armor of a ship. It is said, truly enough, that mere shot, passing in at one side of a vessel without armor, and out at the other, were not considered formidable in comparison with shells. Of course, the few men that happened to be in the line of a shot, were killed ; but that did not put the ship out of action. Besides, small holes are easily plugged. A distin- guished British naval officer, in expressing Jack's contempt for all sorts of pounders, from 18's to 68's, when firing solid shot, added, u but, for God's sake, keep out the shells !" This is the text of many discourses on the subject. What may be true of a vessel without armor, is not necessarily true of a vessel covered with plates ; and the case of a whole ship, with men and machinery distributed throughout its length, is essentially different from that of a small turret or casemate, into which the vitality of the ship is crowded. It is the thin line in- stead of the close column. The armor, it is true, is only punched by a swift shot ; but the part punched out is generally broken to pieces, and the shot is broken to pieces, and the backing and skin are torn into splinters, every one of which is a missile of sufficient 214 ORDNANCE. power to put men, if not machinery, hors de combat. This was actually the case in the thinly-clad Galena (Fig. 128), when pierced FIG. 128. Section of the armor of the Galena (built of wood). size. by the fire of Fort Darling, on the James River. The debris of the armor spread on all sides of the line of the shot, in the form of a cone. Although the shot-hole may be little larger than the projectile, in the front of the plate, it is invariably much larger in the rear (202). A 68-lb. ball drove a hole that measured 8| in. diameter in front and 20 in. at the back, through one of the earlier 4J-in. plates.'* This increased diameter of the part driven out of the plate is equivalent, if it passes through the backing and skin (as it did in several cases mentioned in Table 31), to a projectile of this diameter lired into the ship. Again, the shot that penetrates merely the wooden or iron skin of a ship without armor, loses, in so doing, so little of its velocity, that the inertia of the parts surrounding that immediately struck holds them together. But after passing through armor, the velo- city of a shot is so much reduced that its remaining power and the power of all the new projectiles that it makes out of the pieces of the armor, have time to be communicated to the surrounding parts, and thus to drive in an expanding column of splinters. Sir Howard Douglass says, on the subject :f " In close action, shot discharged from large guns with the full quantity of powder, tear off fewer splinters than balls fired from the same nature of guns with reduced charges. * * * In firing into masses of timber, or any solid substance, that velocity which, can but * London " Engineer." f "Naval Gunnery." 1860. REQUIREMENTS OF GUNS ARMOR. 215 just penetrate will occasion the greatest shake, and tear off the greatest number and largest splinters. * * * This is particularly the case with respect to the impact of shot on plates of iron." 263. The necessity of reducing the exposed length of the armored portion of a vessel for the purpose of making it thicker, with a given buoyancy, is now very generally admitted. The men and the machinery for working the guns the vital fighting parts are thus crowded into a small space. E"ow if one shot, of say 7 to 10 in. diameter, can be made to just penetrate this narrow case- mate or turret, the splinters can hardly fail to be driven all over it. A backing behind the main armor-plate, of several elastic and ductile inch plates, as in the turret of the Dictator, would, of course, modify the result. A laminated target may be torn and bulged, but it is not separated into fragments like a solid plate. But the Dictator turret has also laminated armor on the outside of the main armor-plate, so that it offers no advantage to the heavy shot at low velocities. (194.) 264. It has been objected to the racking system (218), that a class of guns adapted to certain conditions, would be ineffective under different circumstances. The same objection cannot be urged against punching-guns. If their shot go too fast through the armor to make many splinters, they have all the more power left to break the guns, carriages, and other vital parts within the armor. Still, the effect of solid shot within the armor of existing European iron-clads, which are, for the most part, casemated from end to end, is not all that could be desired by opposing artillerists. The Galena, a United States vessel of the same class, was not driven out of action by being punched some 30 times in the action at Fort Darling. Without employing her locomotive powers in such a way as to render herself an uncertain mark, she fought an earthwork, situated upon a high bluff, for several hours. Had her antagonist been an iron-clad vessel of equal offensive and defen- sive power, there would have been an opportunity for one or the other to have settled the matter by manoeuvring instead of brute force. It is not desirable to give an enemy, within gunshot of a 216 . ORDNANCE. town or navy yard, for instance, a chance to manoeuvre, if there can be any means devised to silence or cripple him at once. 265. PUNCHING BELOW WATER. The most formidable work of bolts, at high velocities, is the punching of a vessel below the water-line, or below her armor. The admission of water may, indeed, be stopped, since the holes will be necessarily small. But a shot in a boiler is a most serious calamity. It not only destroys the locomotive power of the vessel, leaving her without the means of manoeuvring, or escaping from rams, or stranding, but it is likely to cause great destruction of life. Several converted vessels and transports with exposed boilers, several light-draught Western iron-clads with boilers necessarily above water, and one or two gunboats of which the draught could not be made to accommodate the height of a certain patented boiler, have been thus pierced by shot during the present war. Mr. Whitworth stated, before the Defence Commissioners,* that he had fired, from a 24-lb. brass howitzer that was rifled, a flat-pointed 32-lb. shot, with 2-J Ibs. of powder, through 30 feet of water and 8 inches of oak situated 3 feet below the surface, and that flat-pointed projectiles will go straight through water. Then, of course, a similarly shaped projectile, fired with 25 to 50 Ibs. of powder, from the present Whitworth, Armstrong, or Parrott guns, would, at a range short enough to give the neces- sary depression, penetrate the skin of a vessel, if it was not pro- tected by heavy side armor or by a very sharply rising floor; or it might penetrate the side-armor of a vessel, if made, as is usual in England, thinner below than above the water-line. Precautions have been taken against both these results in some of the new American designs. Should the accelerating gun (See Appendix) give as good results on a larger scale as it has given on a small scale, tapping the boilers, or breaking the engines of the present iron-clads, at least, would be comparatively easy work. The posi- tion of the boilers may generally be inferred by the enemy from the position of the chimney. * "Report of the Defence Commissioners," 1862. REQUIREMENTS OF GUNS ARMOR. 217 The spherical shot and the slow shot, of any form, will do very little mischief under water. The former loses velocity rapidly, because its area is so great in proportion to its weight, while water is practically non-elastic, and must be displaced instead of compressed. 266. AKMOK-PUNCHING SHELLS. Finally, it appears from the experiments (231 to 235), that shells' can be thrown through armor nearly as well as shot. In the Whitworth experiments of Sept. 25, 1862, a 129-lb. solid steel shot, with 23 Ibs. of powder, did not penetrate the inner skin of the Warrior target, while a 130-lb. steel shell, with 25 Ibs. of powder and 3 Ibs. 8 oz. bursting charge, made a ragged hole in the skin and backing at the same range. In the experiments of Nov. 13th, the shot punched a clean hole through the target ; but the shell, with an equal charge, did con- siderable damage inside the ship, by bursting in the backing. In the experiments of March 17, 1863, no solid shot were fired at the 5^-in. plate; but the 10^-in. 288-lb. Armstrong steel shell, as well as the Whitworth steel shell, penetrated the plate and backing. (See Table 31.) Comparing the 150-lb. spherical shot and the 288-lb. shell from the same gun (10J-in.), the 150 Tb. shot obviously made a wider breach and drove a greater volume of splinters through the War- rior target than if it had been fired with 90 Ibs. of powder and 2010 feet of velocity, so as to fully utilize the strength of the gun. The shell went through a 5^-in. plate that had one-third greater resistance (as the square of the thickness) than the Warrior 4-J-in. plate ; and it is obvious that if its subsequent explosion had not been resisted by an unusually thick skin, instead of the f -in. War- rior skin, the damage inside of a small turret or casemate would have been excessive. The bursting charge of the 288-lb. shell was 11 Ibs. ; that of the 15-in. columbiad shell is but 17 Ibs., and that of the 13-in. mortar shell 7 Ibs. But the shell that has been fired through armor is so shattered, that its bursting charge has less resistance, and conse- quently does less damage. The defect of the Whitworth armor- piercing shells was their inadequate size. 1. The cavity in the 218 ORDNANCE. rear was too small to hold an adequate bursting charge. 2. The cavity was large enough to weaken the walls of the shell, so that the bursting charge was fired as much backward as forward into the ship. But the Armstrong lOJ-in. shell, with a 11-lb. bursting charge, remedied the defect in a great degree, and showed what might be expected from higher velocities. (See Gun Cotton- Appendix. SECTION IY. THE Two SYSTEMS COMBINED. 367. The maximum utilization of power and time, and the consequent infliction of the maximum damage upon an enemy's iron-clad fleet, appear to demand projectiles of moderate weight, so that they may have high velocity with a given strength of gun. At the same time, there may be circumstances under which the heavy shot, at a low velocity, will be the more formidable missile. What has been said in the preceding pages refers to the exclu- sive use of one system or the other. But it will appear that two forces may prepare the way for each other, so as to produce a more formidable result than when they are independently exercised. The defect of the light-shot system, when the range is very long or the armor very thick, and of the heavy-shot system when the range is even very short, and the armor is laminated or so con- structed as to suffer little from racking and shaking, is the waste of power in producing local effect that is fruitless, because it is incomplete. Another defect of the heavy-shot system is its waste of power in overcoming only the elasticity and ductility of ma- terials, without straining it to the point of rupture. Nor is the punching system all that could be desired in its destructiveness of the fighting and manoeuvring powers of an enemy's ship. Wearing out the resistance of a ship's armor, or the seaworthiness of her frame, and projecting small columns of splinters into her vitals by means of small shot and weak shells, take too much time and involve too much risk 368. Light, fast shot may riddle armor without dislocating it as a whole; but if it is not previously weakened, heavy shot cannot smash it in. What is more obvious than the combina- REQUIREMENTS OP GUNS ARMOR. 219 tion weakening the armor by the loss of substance, tenacity, and continuity, until the heavy shot can carry in a large section of it bodily ? At the same time the general straining and crack- ing of plates produced by the heavy shot makes punching all the easier. Meanwhile, the light shots that do penetrate are doing good work upon the enemy within, without reference to the weak- ening of his shield. There have been no experiments made with any direct reference to this method of fighting iron-clads. But the case is so simple, that the result can be pretty confidently predicted. When a bar is to be broken, it is nicked, bored, or otherwise weakened at the point of the intended fracture, either by the loss of material or the reduction of its cohesion, or both. The thick targets (Table 28) were not torn down, because they had so much continuity of substance and support. If the plates could have been previously fractured, or punched, or partially punched, and the bolts broken, and the backing splintered, and the ribs cracked in different places around the part intended to be carried away, the tenacity and elasticity of so much of the structure would have been overcome, and fractures would have been already started in the rest. As a part of this system, the very shots which do least damage by themselves, contribute most usefully to the general result. Nearly punching a small hole does no damage to the enemy, and affords no aid to the next small shot that may strike quite near it, for the local strength of the particular spot it strikes is what the swift shot has to overcome. Any amount of elasticity and tena- city, or weakness and fracture, five or six feet away from it, does not lighten its labor any. A very heavy and slow shot may be fired at laminated armor without materially reducing the work to be done by those that are to follow. The strain is so widely dis- tributed and absorbed by the elasticity and ductility of the fabric, that it produces no essential damage at any one spot. But even nearly punching a small hole almost entirely destroys the strength of some part of the square yard or square rod of a ship's side that resists the racking blow of the heavy shot. 220 ORDNANCE. After a time, tlie remaining continuity of strength is insufficient to resist the smashing blow, and a section of the iron wall is driven in, crushing men and machinery, and opening the enemy's side to the sea and to every projectile which can be thrown with tolerable accuracy bullets, grape, and the enormous shells of these very battering guns. 269. It will be objected that this process is wasteful of time, and that each great gun occupies the room and buoyancy of two lighter or punching guns. This objection would not be well founded. The present improvements in armor, and the obvious means of increasing its resistance to all kinds of strains, may yet place artillerists in the following position : a fight must indeed be brief, or the enemy will manoeuvre himself into shelling range of a city or navy yard. During a brief action they cannot batter and shake down his side with heavy shot, and they cannot punch it with light shot. The only thing that they can do is to weaken his armor so much in detail that they can at last smash it in. No one class of projectiles can do this. There must be two classes. Besides, if guns are all of small calibre, no matter how much powder they will stand, they cannot throw the most formi- dable shells at vessels without armor, or at fortifications, and troops, and buildings, on shore. The usefulness of some heavy guns in fighting the present class of European iron-clads peeling them is obvious from the experiments already detailed. S7O. General Conclusions. The work demanded of guns for iron-clad warfare, is not the mutilation of armor, but the disa- bling of the active enemy men, guns, and machinery within it. "With a given strength of gun-metal, first, attempting by means of very heavy shot, at velocities necessarily very low, to shake off the enemy's armor, for the purpose of shelling him afterwards, gives the elasticity and ductility of the material time to absorb much of the power of the shot. Second. Attempting to render an enemy's vessel untenable and unseaworthy by smashing his sides with shot too heavy and too slow to actually punch them, wastes the greater part of the power in local effect that is fruitless, because it is incomplete (207). REQUIREMENTS OF GUNS ARMOR. 221 Third. Both these processes involve dangerous delays, during which the enemy may fight or manoeuvre himself into shelling range of towns and navy yards. Fourth. Punching-shot of moderate diameter, and light enough to receive a high velocity, meet with the least resistance and waste the least power in uselessly mutilating and vibrating the armor ; they strike the enemy at once. Fifth. The destructive effects of shot, after passing through armor, are very serious, especially when men and machinery are (as they must be) crowded together in small turrets or casemates. Sixth. Some rifled guns are required to throw shells through armor, and for other purposes, at long range. Seventh. To utilize space and buoyancy, a system of rifling is required that will not impair the efficiency of the gun as a smooth- bore. Eighth. Flat-fronted bolts, at high velocities, can be fired through vessels below water. Ninth. Shells can be thrown through armor with nearly as much facility as solid shot. Tenth. The combination of the two systems heavy racking and smashing shot, and smaller punching-shot utilizes both. The latter, without losing its independent usefulness, renders the heavy shot effective. Eleventh. Some guns of large calibre are also necessary to shell towns, earthworks, and vessels without armor, most effectively. 271. In the present state of the art of gun-making, a 10 to 12-in. gun, rifled so as to carry spheres without injury, to fire steel and cast-iron balls at short range, and light sub-calibre punching- bolts and shells at high velocities, and long, heavy shells, with large bursting charges and small propelling charges, at long range, would appear to be the greatest concentration of offensive power (339)- _ But if two kinds of naval guns are to be used and this would appear to be the better system a smaller gun would stand higher relative charges, and thus give higher velocities to punching-shot, and a larger gun perhaps a greater calibre than 20 inches would 222 ORDNANCE. most promptly and effectually smash in a ship's side, throw off her armor, and impair her sea-going as well as her defensive quali- ties, especially when her armor was riddled, or shattered and weakened at different points, by smaller and swifter projectiles. SECTION Y. BREACHING MASONRY. . In addition to destroying iron-clads, modern cannon will be expected to destroy masonry. The relative merits of rifles and smooth-bores, for this purpose, have been well settled by careful experiments in England, as well as by actual warfare in America. The following facts render an extended discussion of the subject quite unnecessary : 7 J$. Abstract of the Report of the Ordnance Select Com- mittee, January 25, 1S61, on Breaching Experiments against Ulartel lo Towers The towers were of brick, 40 ft. diameter at the top, 46 ft. at the bottom, and 32 ft. high. Least thickness at the foot, 7 ft. 3 in. ; at the springing on the vault, 5 ft. 6 in. The object of the experiments was to compare the effect of spherical with that of rifled projectiles. TABLE XXXVIII. GUNS AND CHARGES USED is BREACHING MARTELLO TOWERS. SMOOTH-BORES AGAINST TOWER No. 49. 68-pounders, of 95 cwt. Charge, 16 Ibs. Shell, 49.} Ibs. Burster, ^^ Ibs. 32-pounders, of 58 cwt. Charge, 10 " Shell, aai " Burster, I Ib. RIFLED GUNS AGAINST TOWER No. 71. 6-in. 8o-pdr Armstrong gun. Charge, 10 Ibs. Shot, 82, Ibs 6-in. 8o-pdr. Armstrong gun. Charge, 9 " Shell, 77 " Burster, 5 Ibs. 8 oz. 7-in. Armstrong howitzer. Charge, 9 " Shell, 100" Burster, 8 " 4o-pdr. Armstrong gun. Charge, 5 " j "jj^' j 41 Ibs. Burster, a 8 The range was, in both cases, 1032 yards. With Spherical Shot. "Expenditure of ammunition, 271 rounds ; of which took effect as follows. (Tower No. 49). REQUIREMENTS OF GUNS ARMOR. TABLE XXXIX. 223 NATURE OF GUN. Round shot. Blind shells. Live shells. Total. 68-pounder, smooth-bore 4.0 II 44 QC 24 3 C 68 Total .... 64. ao 70 163 " Corresponding generally to the undermentioned detail of Arm- strong projectiles which took effect against Tower No. 71 : TABLE XL. NATURE OF GUN. Solid shot. Blind shells. Live shells. Total. 8o-pounder gun, rifled. IQ g ?6 6-1 7-inch howitzer, rifled o 2 2q 11 j 4.1 64, T-J Total 30 1 1 108 Tfg Witli Smooth-Bore Guns, "the surface of the tower was erally demolished, but unequally. The superficial area of one face or semicircle of the tower is about 2020 square feet ; effect was visible over 1072 square feet of this surface; and the depth of masonry penetrated having been very carefully measured over the whole surface, by Lieut. -Col. Lennox, K. E., the following is the result : TABLE XLI. MASONRY DISPLACED TO A DEPTH OF Less than i foot on 240 square feet. Between I foot and 2 feet on 367 Between 2 and 3 feet on aao Between 3 and 4 feet on ua Between 4 and 5 feet on 33 Over 5 feet on 56 1028 224 ORDNANCE. " The average depth of broken surface was found to be 1*91 feet, and the cubic quantity of masonry removed, 2168-8 feet. * * * " Taking no account, at present, of the shells which burst near the muzzle of the gun, the above effect was produced by the ex- penditure of 9684: Ibs. of iron, in shot and shell, and 3720 Ibs. of gunpowder, of which 245 Ibs. in bursters ; or, counting only those rounds in which the tower was struck, by 7192 Ibs. of iron, and 2500 Ibs. of gunpowder, of which 134 Ibs. in bursters." 274. With Anntrong Rifled Guns the expenditure up to the 41st round, when the entire side from course 60 (answering to 54 on this [No. 49] tower) had fallen away, making an open breach of 20 feet wide, was 2593 Ibs. of iron and 511 Ibs. of pow- der. Before, however, a strict comparison can be made, it is necessary to take account of the comparative breaching power of the several projectiles, as measured by the product of their weight into the square of the velocity of the shot or shell at the moment of impact. This velocity may be assumed, for the present pur- pose, to be the same as the mean velocity of the same projectile for a range of 2 x 1032=2064 yards, because such mean velocity represents very nearly the actual velocity of the projectile at the middle point of its trajectory, and will be sensibly the same for the same projectile in striking any object at that distance, although in a slightly different trajectory. As the initial velocity of the larger Armstrong projectiles has not yet been ascertained, and there are neither practical nor theoretical data for calculating the remaining velocity at given ranges, this mode of proceeding is the only one open. In Table 42 are data given by observation of times of flight : " Taking the effect of the 68-pounder solid shot as unity, the foregoing data give the following as the order and relative value of the several projectiles under comparison, which we will call "W : " These numbers, multiplied by the number of projectiles of each nature fired, will represent, approximately, the work done upon each tower, and are as follows : " By which it appears that, irrespectively of the superior con- centration of the fire of the rifled guns, and its consequently greater REQUIREMENTS OF GUNS ARMOR. TABLE XLII. 225 NATUBE OF GUN. Charge. Range observed. Elevation. Observed time of flight. Mean velo- city due to time. Nature and weight of projectile. Ibs. yds. / sec. 7 . go feet. 807 Ibs. IO iuyy e 17 7 -OO O27 Armstrong 4O-pdr. gun 5 16 **5J 2100 21 1 2 j */ 5 5 577 6-85 7 IO 920 812 shot 68 Service 68-pdr gun 16 2008 r AT 7 .7 c 872 shell 51^ Service 32-pdr gun IO 2l84 C IO 8-17 784 shot 32 IO IQ82 6 20 7-87 74-3. shell 23^ TABLE XLIII. PRO.IECTILK. Relative value. W. Bursting charge of shell. 8o-pounder solid shot (elongated) I C2 5 Ibs 8 oz loo-pounder shell (elongated) I -4-2 8 o 2 8 0-78 2 4- 72-pounder solid shot (spherical). O A3 72-pounder naval shell (spherical) 0-28 I O effect, they actually performed half as much work again as the smooth-bored guns, with the diminished expenditure of iron and gunpowder noticed in a previous paragraph." " The Metz experiments of 1834, gave for 1000 metres (1094 yards) a mean penetration of 18*2 in. into good rubble masonry, to be increased three-fourths for brick-work. This would give 1 ft. 9-2 in. for brick-work, with a projectile of 36 Ibs., charge, 12 Ibs. The increased penetration of the rifled projectiles is in a far higher 15 226 ORDNANCE. TABLE XLIY. TOWER 71. ARMSTRONG GUNS. TOWER 49. SMOOTH-BORES. Nature of Projectile. Took effect N. Work NxW. Nature of Projectile. Took effect N. Work NxW. 8o-pdr shot J 9 44 3 1 20 44 28-88 66-88 44.02 15-29 33-44 68-pdr shot 40 57 ^4 44 165 40 -oo 44.46 10.32 12.32 107 10 8o-pdr. shell 68-pdr. shell y-in. howitzer shell.. 12-pdr shell AO-pdr shell . 158 188.51 TABLE XLV. APPROXIMATE TABLE OP THE COMPARATIVE PENETRATIONS OP ARM- STRONG AND SPHERICAL PROJECTILES, RESPECTIVELY, INTO BRICK-WORK OF THE BEST QUALITY, AT 1032 YARDS: ARMSTRONG. SMOOTH-BORES. Nature of Projectile. Weight. Charge. Penetra- tion. Nature of Projectile. Weight. Charge. Penetra- tion. j-'in. shell Ibs. IOO Ibs. ft. in. 3 8 68-pdr. shot Ibs. 68 Ibs. 16 ft. in. i 8 82 JO 7 6 68-pdr. shell ri 16 i 9 6-in shell 77 4 T, 32-pdr. shot -32 10 i 4 fshot ) 4-P dr -j shell}" 41 5 4 i 32-pdr. shell ^3 4- 10 i 4 ratio than theory could assign to them. It is plain, therefore, that we must look for some other cause than their superior vis viva, and this is furnished by their rotation on their longer axis. The 6-in. projectile leaves the muzzle of the gun spinning at the rate of about 63 turns per second. It is not probable that this rate diminishes as fast as the motion of translation. It will be very little reduced in 3 or 4 seconds, or at 1032 yards, and must mate- rially aid penetration. 1 ' REQUIREMENTS OF GUNS ARMOR. 227 375. Breaching of Fort Pulaki, Georgia, April, 1861. -The following is compiled from the official report of General Gill more : Fort Pnlaski is a brick work of five sides, casemated on all sides ; walls 7^ ft. thick and 25 ft. high, with one tier of guns in embrasures and one tier en barbette. At the time of the siege, it contained 48 guns, 20 of which bore on the attacking batteries, viz., five 10-in. and five 8-in. columbiads, and four 32-poimders, all smooth-bores, one 24-pounder Blakely rifle, and two 12-in. and three 10-in. sea-coast mortars. The work was breached in 3 half- days, and surrendered on the second day. TABLE XLVI. NUMBER, CHARACTER, AND RANGE OF SHOTS FIRED IN THE BREACHING OF FORT PDLASKI. NAME OF BATTERY. Dis- tance in Projectiles, yards. Charge. Burst- ing charge. No. of shots. Ibs. Ibs. Battery Stanton.... 3400 13-in. Mortar shells. Hi 7 2 55 Battery Grant 32.00 Ditto. IJ* 7 282 Battery Burnside.. 2750 Ditto. i 7 '55 Battery Sherman.. 2650 Ditto. 10 7 232 Battery Halleck... 2400 Ditto. ii 8 220 Battery Totten 1650 lo-in. Mortar shells. 4-V 3 588 Battery Lyon 3100 lo-in. Columbiad shells. 17 3 321 " M Battery Scott....... 1740 ( lo-in. Columbiad shot. \ 8-in. Columbiad shot. 20 10 } 5' u j3 Battery Lincoln... Battery McClellan 345 1650 8-in. Columbiad shells. {84-lb. James shot and shells. 64 " do. do. do. 10 8 6 ii 4 28 } 793 *<3 'a -o o "w Battery Sigel...... 1670 f 48-lb. James shot and shells. I 30 " Parrott do. do. 3* |i 5 oo u 1 _c Of the breaching guns, the two 84-pounders, the two 64-pound- ers, and the 48-pounder, were, respectively, old unhooped 42, 32, 228 ORDNANCE. and 24-pounders, rifled with broad flat grooves. There were 5 Parrott 30-pounders. TABLE XLVII. PENETRATIONS IN BRICK-WORK. KIND OF GUN. Eange. Projectile. Elevation. Charge. Penetra- tion. yds. Ibs. in. Old 42-pdr. rifled.. 1650 James 84-lb. shot. 4i 8 26 Old 32-pdr. rifled.. 1650 James 64-lb. shot. 4 6 20 Old 24-pdr. rifled.. Parrott lo-pdr 1670 1670 James 48-lb. shot. Parrott go-lb. shot. 4* ? 4-J-" 5 ^ '9 18 lo-in. smooth-bore 1740 iz8-lb. solid shot. 5 20 3 8-in. smooth-bore 1740 68-lb. solid shot. 5 10 ii The following deductions must be made, to estimate the amount of metal expended, viz. : " First. For the shots expended upon the barbette guns of the fort in silencing their fire. "Second. For 10 per cent, of Parrott's projectiles which upset, from some defect which, I know from personal observation, has been entirely removed by the recent improvements of the manu- facturer. " Third. For nearly 50 per cent, of the 64-lb. James shot, due to the fact that one of the two pieces from which they were thrown had, by some unaccountable oversight, been bored nearly J in. too large in diameter, and gave no good firing whatever. " Making these deductions, it results that 110643 Ibs. of metal were fired at the breach." Fifty-eight per cent, of the metal was fired from rifled guns. The weight of metal thrown per lineal foot of breach w r as 2458 Ibs. Two casemates were fully opened, say 30 feet in aggregate width, the scarp wall was battered down in front of 3 casemate piers, and the wall of the fort was badly shattered for 25 or 30 feet on each side of the breach. REQUIREMENTS OF GUNS ARMOR. 229 Lieutenant Porter, Chief of Ordnance and Artillery, states, in his report, that the 8-in. and 10-in. columbiads, throwing solid- shot at 1740 yards, " performed their part admirably in the demolition of the masonry ;" and that it was after the rifles had perforated the walls, " that the columbiads performed their true office in crushing out the immense masses of masonry." 2TG. General Gillmore concludes that "First. Within 700 yards, heavy smooth-bores may be advan- tageously used for breaching, either alone or in combination with rifles. "Second. Within the same distance, light smooth-bores will breach with certainty, but rifles of the same weight are much better. " Third. Beyond 700 yards, rifled guns, exclusively, are much superior for breaching purposes to any combination of rifles and heavy or light smooth-bores. " Fourth. Beyond 1000 yards, a due regard to economy in the expenditure of manual labor and ammunition, requires that smooth-bores, no matter how heavy they may be, should be scru- pulously excluded from breaching batteries.' "Fifth. In all cases when rifled guns are used exclusively against brick walls, at least one-half of them should fire percussion shells. Against stone walls shell would be ineffective." The mortars did very little damage to the work. Their fire was inaccurate. Not one-tenth of the 13-in. shells dropped inside the fort. A few struck the terrepleiii over the casemate arches, but without producing any serious results. 276 A. Breaching of Fort Slimier, South Carolina, Augut, 1863.* This was a brick work, similar in construction to Fort Pulaski, before described, except that it had another tier * General Gillmore has kindly allowed the author to copy the following statements from his official report, in advance of its publication. They form a complete summary of the facts in the case that strictly belong to the subject under consideration, although in a military and an engineering point of view, General Gillmore's narrative of the conduct of the siege and the transportation of 100 to 300-pounder rifles over swamps and open sands, in the face of the enemy, will be found singularly important and interesting. 230 ORDNANCE. of casemates. These, however, were not armed. The capacity of the fort was 135 guns; how many guns were mounted it is impossible to state, as the Federal forces are not yet in possession of the ruins. TABLE XLVIL A. RANGES AND NATURE OF BATTERIES EMPLOYED IN BREACHING FOET SUMTER. Name of Battery. Nature of Guns. Ilarige in yds. Two 8-in Parrott Rifles Three loo-pdr. Parrott Rifles 35 10 Battery Meade Two loo-pdr. Parrott Rifles... j^H-/ 3A2.8 f Two 8o-pdr. Whitworth Rifles (Two 8-in. Parrott Rifles 3938 Battery Hays f One 8-in. Parrott Rifle .... 1 (Two ioo-pdr Parrott Rifles 4272 Battery Stevens Two ioo-pdr Parrott Rifles 4.278 One lo-in Parrott Rifle Number of guns, 17. Average range, 3881-3 yards. The whole number of projectiles thrown was 5009. Weight of projectiles thrown, 552683 Ibs. Number of projectiles that struck the masonry, 2479. Number of projectiles that struck the gorge wall and helped to form the breach, 1668. Weight of metal that formed the breach, 289986 Ibs. Firing opened Aug. 17, 1863; closed August 23, 1863. The precise effect of these projectiles cannot, of course, be stated; but it is certain that about one-third of the face of the gorge wall, for about one-third of its depth, fell down, mostly outward, forming a practicable breach from 70 to 80 yards long, and from 10 to 13 feet deep. 276 B. Breaching Fort Wagner. Sand Armor. During this siege, the bomb-proof of a rebel work occupying the entire REQUIREMENTS OF GUNS ARMOR. 231 breadth of Morris Island, and mostly constructed of sand, was, with great difficulty, breached by similar rifled projectiles. The four breaching batteries were located at 1330, 1460, 1830, and 1920 yards range respectively. Upon the capture of this work, it was ascertained by careful measurement that 165 cubic yards of sand had been removed by 54rJ tons of projectiles, which is equal to 1 Ib. of metal for the removal of every 3.27 Ibs. of sand. The slope was quite flat, and the greater part of the sand knocked away fell back in place again. 232 WROUGHT IRON. RESISTANCE TO ELASTIC PRESSURE. 283 CHAPTER III. THE STRAINS AND STRUCTURE OF GUNS. SECTION I. RESISTANCE TO ELASTIC PRESSURE. 977. The strains to which cannon are subjected by the pressure of the powder are thus stated by Captain Ben ton:* "1. The tangential strain, which acts to split the piece open longitudinally. * * * 2. The longitudinal strain, which acts to pull the piece apart in the direction of its length. 3. A strain of compression, which acts from the axis outward, to crush the truncated wedges of which a unit of length of the piece may be supposed to consist. * * * 4. A transverse strain, which acts to break transversely, by bending outward the staves of which the piece may be supposed to consist. * * * " If p be the pressure on a unit of surface of the bore, and s the tensile strength of the metal, it can be shown by analysis that the tendency to rupture, or the pressure on a unit of length of bore, divided by the resistance which the sides are capable of offering to rupture, for a piece of one calibre thickness of metal, will be as follows : Tangential, jg; or, rupture will take place when three times the pressure is greater than twice the tensile strength. Longitudinal, ^; or, rupture will take place in the direction of the length, when the pressure is greater than twice the tensile strength. Transverse, |^; * "Ordnance and Gunnery," 1862. 234 ORDNANCE. or, rupture will take place when twice the pressure is greater than three times the tensile strength. "From the above it appears that the tendency to rupture is greater from the action of the tangential force than from any other ; and for lengths above two, or perhaps three calibres, the tangen- tial resistance may be said to act alone, as the aid derived from the transverse resistance will be but trifling for greater lengths of bore or stave." 278. I. Increasing the thickness of the walls. The most obvious means of enabling any vessel to sustain a greater elastic pressure, such as the gas of exploded gunpowder, is to simply thicken its sides, thus increasing the area of substance to be torn asunder. This rule is founded upon the practical facts of every-day engineering, which usually deal with comparatively low pressures and thin walls. Even in case of guns of small calibre, it has proved tolerably safe. But when these conditions are greatly changed when the problem is, for instance, to throw projectiles of 13 to 15 inches' diameter at the rate of 1500 to 1800 feet per second, and the gun is proportionally thickened to stand the excessive strain due to both the increased pressure per square inch and the increased number of square inches pressed upon, another law, unobserved in ordinary practice, assumes a very serious importance. This law is thus clearly explained by Cap- tain Blakely :* 279. "To obtain much greater strength by casting guns heavier is impossible, because in cast guns (whether of iron, brass, or other metal) the outside helps but very little in restraining the explosive force of the powder tending to burst the gun, the strain not being communicated to it by the intervening metal. The consequence is, that, in large guns, the inside is split, while the outside is scarcely strained. This split rapidly increases, and the gun ultimately bursts. " This will be more easily understood by considering the case of a much more elastic tube ; for instance, an India-rubber cylin- * "A Cheap and Simple Method of Manufacturing Cannon," 1858. RESISTANCE TO ELASTIC PRESSURE. 235 FIG. 129. FIG. 130. der 10 inches in internal diameter and 10 inches thick, therefore 30 inches in external diameter. Such a cylin- der might be strained by pressure from within till the inside stretched to double its original circumference. The diameter would, of course, also be doubled, and would be 20 inches in- stead of 10. "Now it is evident that the outside circum- ference and diameter cannot be doubled at the same time, or else the latter must become twice 30 or 60 inches, which would give a thickness of 20 inches, quadrupling the mass of material, which is impossible. A moment's reflection shows that the thickness must diminish as the circumference is increased by pressure from within ; for, if the thickness remain 10 inches when the internal diameter has become 20, the external diameter must be 20 plus twice 10, or 40 inches. This could not be, unless we imagine what seems impossible, viz., that the bulk of the material is con- siderably enlarged, as each inch in length of the cylinder would now contain 1200 cylindrical inches (the difference between the squares of 40 and 20, the external and internal diameters), whereas originally it only contained 800 inches, the difference between the squares of 30 and 10. "Yet, even if the thickness could remain the same, notwith- standing the increase of circumference, the outside layer could only be strained one-third as much as the inside one, because three times as long. The same elongation, which w r ould cause a strain of one ounce or one pound in the longer circumference, would cause a strain of three ounces or three pounds in the shorter one, and the elongation which would but moderately strain the one would break the other. " This reasoning is equally applicable to the minute extension of iron ; the increase of T V of an inch in the outer circumference of a 10-inch gun being possible without fracturing that part, 236 ORDNANCE. being an elongation of but 1 in 940 ; whereas the same extension must crack the inside, as no iron could stand an elongation of T ^ in 31i, or 1 in 314. " Even on this showing, then, the outside of a thick tube cannot do its share of work; a closer examination, however, must con- vince us that this is an over-estimate of it, for the thickness of material must diminish as the circumference is increased. When the inner diameter of the 10-inch cylinder becomes 20 inches, the thickness must diminish from 10 to 7*32 inches, the cross-section of the cylinder remaining the same. This cross-section was originally 800 circular inches, 800 being the difference between the squares of 30 inches, the outer diameter, and 10 inches, the inner, or 900 minus 100. When stretched, the area of the cross-section must continue to be 800 round inches. Now a thickness of 7'32 inches gives us an external diameter of twice 7-32 or 14-64 added to 20, the internal diam- eter, in all 34-64 inches, the square of which is 1200. Subtract- ing 400, the square of 20, leaves 800 round inches as before. In this case the outside of the cylinder is stretched but 4'64 in 30, about one in seven, when the inside is stretched to double its original size. If the inner diameter be only stretched to 11 inches, the thickness must be diminished from 10 to 9*674 inches, the outer diameter becoming 30-348 inches, the cross-section remaining 800 round inches, as before, the difference between the squares 30-348 and 11. Here the outer layer is elon- gated -348 in 30, or 1 in 86; whereas the inner is extended 1 in 10, showing a strain or an exertion of power 8 J times greater. " In the minute extension of metals the dis- proportion is still more striking. Thus in cast-iron the 10-inch inner diameter may become 10 T i , which would extend the outer diameter only from 30 to 30^ Jo, the cross-section remaining 800 inches, and the thickness diminishing from 10 inches to 9f f . Here RESISTANCE TO ELASTIC PRESSURE. 237 FIG. 133. FIG. 134. the outside would only be stretched 3^ in 30, or 1 in 9000, the inside being stretched T in 10, or 1 in 1000, exert- ing, therefore, nine times as much power as the outside. It is evident that a slight increase of pressure from within would break the inside, while the outside could help but little in re- straining the disruptive force. S8O. "If we make equidistant circular marks on the end of an India-rubber cylinder (Fig. 134), and stretch it, we can see plainly how much more the inside is strained than the outside or even the intermediate parts. The spaces between the marks will become thinner, each space becoming less thin than that inside of it, but the inner space much thinner than the others (see Fig. 135), showing that when the inside is strained almost to breaking, the intermediate parts are doing much less work, and those far removed almost none. 381. LAW OF STRENGTH OF CYLINDERS. " In the first volume of the l Transactions ' of the Institute of Civil Engineers, p. 133, there is a paper by Professor Peter Barlow, F.R.S., on the Strength of Cylinders. The law he deduces is, that i in cylinders of metal the power exerted l>y different parts varies inversely as the squares of the dis- tances of the parts from the axis.' Thus, in a 10-inch gun, when the inside, which is 5 inches from the axis, is fully strained, the metal 2 inches from the inside, or 7 inches from the axis, can only exert a force |f, or little more than half as much; 3 inches further, 10 inches from the axis, the force exerted diminishes to fW, or but a quarter of that exerted by the inside; and if the gun be 12 inches thick, the outside, India-rubber cylinder, with equidistant concentric marks. FIG. 135. The same cylinder, stretched by internal pressure; the concentric marks show the inferior stretch of the exterior. 238 ORDNANCE. which is 17 inches from the axis, can exert ~but 2 2 /9 5 or dLout T V as much power as the inside. Of course, casting the gun still thicker would add but very little to its strength ; we cannot, therefore, be astonished that it has been found in practice that cylinders for hydraulic presses, with a thickness equal to about J the diameter of the piston, are very nearly as strong as if ten times as thick. 383. "In 1855, Dr. Hart, of Trinity College, Dublin, inves- tigated the problem. His calculations (see note "W, p. 259 of Mr. R. Mallet's work on the Construction of Artillery) give greater strength to the inner parts, but still less to the outer, than those of Professor Barlow. Both these gentlemen, as well as General Morin, and Dr. Robinson the astronomer, who have also studied the question, agree that no possible thickness can enable a cylinder to hear a pressure from within greater on each square inch than the tensile strength of a square inch lar of the material; that is to say, if the tensile strength of cast iron be 6 tons per inch, a cylinder of that metal, however thick, cannot bear a pressure from within of 6 tons per inch." 383. The report of experiments made by the United States Government in bursting hollow cylinders by internal pressure states that "the general range of the re- FIG. 136. suits appears to sustain Mr. Barlow s hypothesis." * 384. In further proof of the foregoing facts, Capt. Blakely cites the actual frac- ture of some cylinders (Fig. 13G) made by Mr. Longridge, of iron wound with wire. The cracks were "much more open at the inside, and some not extending to the Cylinder burst by internal outside." 385. The law of diminution in the power of resistance is also illustrated by Professor Treadwell, who states it as follows :f " Suppose such a cylinder to be made up of a great number of thin rings or hoops, placed one within another. * Reports of Experiments on Metals for Cannon, 1856. f "The Practicability of Constructing Cannon of Great Calibre, etc.," 1856. RESISTANCE TO ELASTIC PRESSURE. 239 Then the resistance of these rings, compared one with another, to any distending force, will be inversely as the squares of their diameters. If we make a cylinder of 41 concentric hoops of equal thickness, disposed one within another, and exactly fitting, so that the particles of each hoop shall be in equilibrium with each other, the diameter of the largest being 5 times that of the smallest, then the force of each, beginning with the innermost, to resist distension, will be represented by the following numbers : 1000 250 in 62 826 225 104 59 694 207 98 56 59 1 l8 9 9* 54 51 174 87 51 444 l6 82 49 39 1 J 48 77 47 346 i37 73 45 309 128 69 43 277 "9 6 5 4i 40 "An inspection of these numbers must, I think, impress any- one with the fact that it is impossible to increase essentially the strength of cannon by a simple increase of thickness." 38 S. The weakness of a homogeneous cylinder, and the remedy, (which will be considered in the following article), have been mathematically investigated, with great care, by Dr. Hart, of Trinity College, Dublin, and Mr. C. H. Brooks, from whose cal- culations it has been illustrated and made the subject of a paper by Mr. James Atkinson Longridge, followed by an important discussion before the Institution of Civil Engineers. Mr. Longridge says:* "If, in Fig. 137, A B C D represent a portion of a section of an 8-inch gun, of which A G B is the inner, and D F C the outer circumference, the state of tension of any particle between G and F may be denoted by ordinates drawn at the points in question, those above G F representing tension and those below compression. " If now the gun be of any homogeneous material, such as cast * "Construction of Artillery," Inst. C. E. ? 1860. 240 ORDNANCE. iron, the state of tension at the time of explosion, and when the gun is about to burst, will be denoted by a curve H I, or H t, FIG. 137. Illustration of strain on a homogeneous gun. the former calculated according to Professor Hart, and the latter according to Professor Barlow's formula. Then, supposing the tensile force of the material to be 12 tons per square inch, and the thickness of the gun 6 inches, when the strain at G is G H, or 12 tons, at F it is 1? 1 = 3 tons, or F i = If tons, according as the one or other formula is adopted. The areas of these curves give the total strengths of the gun at the bursting point, and are found to be 36*72 tons and 30*871 tons respectively, instead of 78 tons, which it would have been if uniformly strained at 12 tons per square inch." 987. II. Hoops with initial tension to resist elastic pres- sure. This system consists in making a gun of concentric tubes, by putting on each successive layer, proceeding outward from the centre, with an initial tension exceeding that of those below it, or so that each hoop or tube shall compress what is within it. The RESISTANCE TO ELASTIC PRESSURE. 241 inner layer is thus, in its normal state, in compression, while the outer layer is in the highest tension. Then, by the law illustrated in the foregoing paragraph, the inner layer, being in compression, is able to sustain the first and greatest stretch, and the outer layer, although stretched less by the explosion of the powder, has already been stretched into high tension, and thus has to do an equal amount of work. The intermediate layers bear the same relations to the initial strain and the strain of the powder, so that, in short, all the layers contribute equally of their tensile strength to resist the strain of the explosion. 288. PROFESSOR TREADWELL'S PLAN. Professor Treadwell, who was one of the first to propose this method of constructing cannon,* thus specifies his proposed gun and its strength.f " I propose to form a bocjy for the gun, containing the calibre and breech as now formed of cast iron, but with walls of only about half the thickness of the diameter of the bore. Upon this body I place rings or hoops of wrought iron, in one, two, or more layers. Every hoop is formed with a screw or thread upon its inside, to fit to a corresponding screw or thread formed upon the body of the gun first, and afterwards upon each layer that is embraced by another layer. These hoops are made a little, say T oV oth part of their diameters, less upon their insides, than the parts that they enclose. They are then expanded by heat, and being turned on to their places, suffered to cool, when they shrink and compress, first, the body of the gun, and, afterwards, each successive layer all that it encloses. This compression must be made such, that, when the gun is subjected to the greatest forcey the body of the gun and the several layers of rings will be dis- tended to the fracturing point at the same time, and thus all take a portion of the strain up to its bearing capacity. "There may, at the first view, seem to be a great practical difficulty in making the hoops of the exact size required to produce the necessary compression. This would be true if the * The claims of Professor Treadwell, Capt. Blakely, Mr. Longridge, and others, as to priority in this invention, will be stated in the Appendix. f "On the Practicability of Constructing Cannon of Great Calibre," Dec., 1856. 16 242 ORDNANCE. hoops were made of cast iron, or any body which fractures when extended in the least degree beyond the limit of its elasticity. But wrought iron and all malleable bodies are capable of being extended, without fracture, much beyond their power of elasticity. They may, therefore, be greatly elongated without being weak- ened. Hence we have only to form the hoops small In excess, and they will accommodate themselves under the strain without the least injury. It will be found best in practice, therefore, to make the difference between the diameters of the hoops and the parts which they surround, considerably more than T oVoth part of a diameter. The fixing the hoops in their places by the screw, or some equivalent, is absolutely necessary, not merely to reinforce the body against cross fracture, but to prevent them from start- ing with every shock of the recoil. I know, by experiment, that the screw-thread will fix them effectually. The trunnions must, of course, be welded upon one of the hoops, and this hoop must be splined, to prevent its turning by the recoil. Small splines should likewise be inserted under every hoop. It will, moreover, be advantageous to make the threads of the female screws sensibly finer than those of the male, to draw, by the shrink, the inner rings together endwise. * * S89. "With these facts, principles, and laws, thus stated, I proceed to give some calculations to show the strength of a cannon constructed in the way that I have pointed out, as compared with one made in the usual manner. Take a cannon of 14 inches 1 calibre, which will carry a spherical solid ball of 374 pounds, with sides 14 inches thick, made up of 7 inches of cast iron, and two hoops or rings, 3^ inches each, of wrought iron. The external layer of cast iron will, from its position, as before explained, pos- sess but one-fourth of the strength of the inner layer, or whole strength of the iron, and the mean strength of the whole will be reduced one-half. Take cast iron at 30000 pounds to the inch area, and we have 30000 x |- 15000 pounds to the inch. The thickness of both sides is 14 inches, and 15000x14210000 pounds for the strength of the casting, to each inch of its length. The first hoop has its strength reduced from 1 to a mean of *8. RESISTANCE TO ELASTIC PRESSURE. 243 Take the strength of wrought iron at 60000 pounds to the inch, and we have 60000 x -8=48000 pounds to the inch. The thick- ness of both sides is 7 inches, and 48000 x 7 336000 pounds. The outside ring must be reduced in strength by the same rule, for its mean, from 1 to '832, which gives it 49920 pounds per inch, and for the 7 inches 349440 pounds. We have then, for each inch in length, Caft-iron body of the gun 210000 pounds. Inner wrought-iron hoop 336000 Outer wrought-iron hoop 34944 " 895440 " The diameter of the bore being 14 inches, we have -"-iijji = 63960 pounds, as the resistance to oppose to each square inch of the fluid from the powder. The gun will bear, then, a pressure of 4264 atmospheres. "The resistance to cross fracture at the part nearest to the breech will be, from the cast iron, 28 2 14 a =784 196 circular inches, equal to 460 square inches. Cohesive force, unreduced, 30000 pounds, and 30000x460=13800000 pounds, the whole strength. The bore contains 153 square inches, and J-ajuyyuuL 90196 pounds to resist each square inch more than is provided to resist longitudinal fracture ; and this excess w^ill be further rein- forced by the wrought-iron rings, which, being screwed upon the casting, and the outer layer breaking joint over the inner, will add to the resistance to a great amount, which, however, need not be computed. "Let us now examine a gun made of a single casting, of the dimensions given above that is, of 14 inches bore and 14 inches thick. Taking the normal strength of cast iron, as before, at 30000 pounds per inch, we must reduce it according to the laws before explained (see the preceding article), to -J-, or a mean of 10000 pounds per inch; and the thickness of both sides being 28 inches, we have 10000x28 = 280000 pounds for the whole strength, and **- o JLH. 20000 pounds to each* inch of the fluid pressure, or 1333 atmospheres, or f , or less than -J of the first 244 ORDNANCE. example. Against a cross fracture, the cast gun will possess a great excess of strength, which I do not like to call useless, although I do not perceive how it can be of any essential practical advantage. * * * " The following columns show the stress that the several kinds of guns, as mentioned, will bear, by calculation, and the pressure required to give the velocity of 1600 feet a second. The third column shows the proportion between the required and the actual strength : Atmospheres. Atmospheres. Hooped cannon for 14-inch fhot will bear 4266; required 2133 100 : 200 Caft-iron gun, 14-inch mot, will bear I 333> " 2I 33 io ' 62 Caft-iron 32-pounder cannon, 6 inches thick, will bear J 333j " 9^o loo : 142 Hooped cannon, 30 in. diameter, 3670 Ib. mot 4266; " 4266 100 : 100 " By this it appears that a common cast-iron 32-pounder, hav- ing but 42 per cent, more strength than is required, is less reliable than a hooped gun of 14 inches It will be recollected that the numbers given above, in the second column, as showing the required strength, represent the utmost force ever exerted by a charge intended to produce a velocity of 1000 feet a second." 29 O. ANOTHER USE OF HOOPS. Commander Scott, R. "N., mentions another service rendered by hoops.* "Many experiments have shown the destructive effects on cast-iron ordnance from continuous firing, as also the increased strength resulting from long rest ; and, by allowing two or three months or more to intervene between the series of discharges, a very much greater number of rounds may be safely attained than in case of almost daily practice with the same gun. At page 218 of the work on ' The Useful Metals,' published in 1857, it is stated that ' pieces cast some years before testing stood several times the quantity of firing of other pieces cast but a few months previously.' The tensile properties of the metal did not explain the difference ; and the form, dimensions, weight, method of casting and cooling, and the manner of proving, were the same in all the pieces tried. * Journal Royal United Service Inst., April, 1862. RESISTANCE TO ELASTIC PRESSURE. 245 * * * All guns properly cast are sufficiently strong to resist a few rounds of heavy charges ; but by using them, the particles of iron would be disturbed, and then would not rearrange or resettle themselves, unless a period of long rest were given. The object, therefore, to be arrived at is, to prevent the disturbance of the particles, and the consequent deterioration of the piece ; and this is what the hooping does effect, when the gun is fired with the charges which the hoops are calculated to withstand." 291. Defects of the Hooping System Remedies. Each hoop or tube, taken by itself, has the element of weakness considered in a foregoing paragraph its inner circumference is more stretched and strained than its outer circumference. Absolute perfection would necessitate infinitely thin hoops; and practically, the thinner the layers, the greater the strength (313) provided the mechanical difficulties in constructing, and more especially in applying, a great number of thin strata, with the proper tension, do not outweigh their advantages. This subject has also been mathematically illustrated by Mr. Longridge, in the paper before referred to. Some years since, Mr. Longridge con- structed a number of guns and other cylinders to be subjected to pressure, by winding square steel wire upon homogeneous metallic cylinders, the successive layers of wire having an increased initial tension, and corresponding in their functions to a great number of very thin hoops similarly applied (93). He compares the wire reinforce with the thick hoops used by Captain Blakely and others, in two particulars, the actual strength for a given thick- ness of metal, and the practicability of construction.* 292. WANT OF CONTINUITY, f u ln the first place, then, there is an objection to the use of hoops from the want of continuity." (Here follows an explanation of the weakness of a homogeneous cylinder, previously given.) "Now the object sought to be at- tained in the method of construction under consideration, is that each particle, such as K (Fig. 138), shall, when explosion takes * The results of Mr. Longridge's experiments have been given in Chap. I. f "Construction of Artillery," Inst Civil Engineers, 1860. 246 ORDNANCE. place, be equally strained with G. In order that this may be so, the initial state of the tension must be such as is represented by FIG. 138. Strain due to want of continuity of hoops. the curve L N M, those between G and N" being in compression, whilst those between !N" and M are in tension. * * * What took place where the explosion occurred might be thus described: L was raised to H, and every point from G to F was raised up to the tension denoted by its projection on the line II O. The total strength was represented by the area L II O M N L, which was equal to the rectangle G II O F. That was the way to get, theo- retically, the strongest gun. * * * " If now it be attempted to accomplish this by means of hoops, it will be found impossible, inasmuch as each hoop is a homogeneous cylinder, and follows the same law throughout its thickness, as is represented by the curve H I. Figs. 139, 140, and 141 represent the successive state of stress of four rings, put on so that when the explosion takes place, they shall all be equally strained at their inner circumferences. RESISTANCE TO ELASTIC PRESSURE. 247 " The figures denote the strains in tons per square inch. "From this it will be seen that when the four rings are put on, FIG. 139. FIG. 140. Shows two rings on. Shows three rings on. instead of the curve L ]S" M of Fig. 138, there are a series of abrupt changes, the two inner rings being in compression, and the two FIG. 141. Shows four rings on. outer in tension. "When the explosion takes place, the state of maximum strain is represented by the next diagram, Fig. 142. The area between the dotted and full lines shows the work done 248 ORDNANCE. by the explosion, and taking the total thickness of the gun, it amounts to lO'l tons per inch of thickness; whereas, had the con- FIG. 142. struction been of very thin rings, or of small wire, it would have been represented by the area between the dotted line L N M O H (Fig. 138), and would have been = 12 tons per inch of thickness, showing a superiority of about 20 per cent, in favor of the wire over the hoops. This is upon the supposition that the workmanship of the hoops is perfect, which in practice cannot be attained." The objection, which amounts to this that when the number of hoops is small enough to make a cheap gun, an extra weight of material is required to secure the requisite strength can hardly be considered a serious defect in the armament of forts and iron- clad vessels. The subject of weight will be further referred to. 293. THEORETICAL ACCURACY OF TENSION. Mr. Longridge then discusses the practicability of constructing hooped guns with the accuracy necessary to impart proper strength. "To afford some idea of the accuracy required, the radii of the several rings, shown in the above diagram, are given in Table XLYIII. RESISTANCE TO ELASTIC PRESSURE. 249 TABLE XLVIII. RADII OF RINGS FOR HOOPING GUNS. No. of King. Inner Radius. Outer Radius. Thickness. Differences. I 4-0000 5.3222 I 3222 R!~ p 2 = -0031 2 S'3'9 1 7-2928 1-9737 R 2 P3='35 3 7.2893 9.4633 2-1740 R:J P 4 =-35 4 9.4598 11-8247 2-3649 " Thus, it appears, that in order to give the requisite amount of initial stress, the external radius of the first ring must be T oVo oths of an inch, or about ^oth of an inch larger than the internal radius of the second: the external radii of the second and third T^Vo^ths of an inch greater than the internal radii of the rings next to them. Therefore, whilst the whole effect depends upon so small a quantity as about g^th of an inch, it is evident that a very small error in workmanship will materially affect the result, and may tend to the most serious deviations from the proper initial strains." Mr. Longridge concludes that if the outer ring of the gun (Fig. 142) is made yoth of an inch too small ''before explosion, the maximum compression of the inner ring is increased from 10'086 tons to 11*244 tons, and the maximum tension of the outer ring from 5'778 tons to 7'823 tons per square inch; whilst at the time of maximum strain, during explosion, the tension of the same ring is only 2'268 tons, although the outer ring is strained to 12 tons, its assumed ultimate strength. The absolute strength of the gun is thus reduced from an average of 10*5 tons to 6*0 tons per inch of thickness, or about 40 per cent., by an error of only j th of an inch, in a ring of about 17 inches diameter." 294. This extreme accuracy is not deemed of practical impor- tance by Captain Blakely, Sir William Armstrong, and other makers of hooped guns. Perhaps this is the reason why their guns do not often come up to the theoretical standard of strength. Referring to the ordinary use of wrought iron, under strain, and 250 ORDNANCE. to its known ductility, or capacity of receiving a permanent change of figure under strain, this nicety is pronounced absurd by practitians. On the other hand, the want of regard for mathe- matical nicety is the great cause of failure in mechanical experi- ment and construction. The hooped guns of Mr. Whitworth, who is noted for the "truth" of his workmanship, and who acknowledges the greatest care and the most accurate processes in the application of the hoops, are stronger to resist statical pressure than some others of similar construction and material. 293. FORCING ON HOOPS. Supposing this nicety in the ten- sion of the layers of a gun to be important, Mr. Longridge fails to prove it more difficult of accomplishment with hoops than with wire. Mr. "Whitworth forces on the rings by hydrostatic pressure. Captain Blakely also advocates the same method.* As to which Mr. Longridge says: "Here again occurs the practical difficulty of the attainment of extreme accuracy of workmanship, involving the highest class of skilled labor, and the greatest vigilance of supervision." On the contrary, the forcing of a slightly conical ring over a correspondingly conical tube, obviates the necessity of great accuracy in the diameter of either piece. The truth of the cone depends upon the correctness of the lathe, and may be removed from the interference of the workman. The truth of the surfaces is also a question of good tools. The tension of the ring depends on the distance to which it is forced upon the coni- cal tube, and this may be regulated to a pound, by the weight upon the safety-valve of the hydrostatic press. With special tools, which are economical in any extensive establishment, such as a Government gun-factory, or even with the common machine tools, modified and set permanently for a given duty, the most inexpert workman could hardly fail to make a good job (300). The adjustment of Mr. Long'ridge's Prony brake, to give the proper tension to each coil of wire, is certainly simple and ade- quate, but it is not automatic, like the safety-valve of a hydro- static press. * "Construction of Artillery," Inst. C. E., 1860. RESISTANCE TO ELASTIC PRESSURE. 251 296. SHRINKING ON HOOPS. UNEQUAL SHRINKAGE OF METAL. If hoops are put on by shrinking, two embarrassments arise. 1. As Mr. Longridge says: " Hoops must be accurately bored, and after each layer is put on, the gun must be placed in the lathe, and the hoops be turned on the outside. Great accuracy of workmanship is indispensable, and not only is the amount of labor much greater, but it must be of a far higher, and, conse- quently, of a more expensive class." 2. " The process of shrinking on is not to be depended^upon. ~Not only is there a difficulty in insuring the exact temperature required, but scarcely any two pieces of iron will shrink identically. ? '* The fitting of hoops, with the nicety of adjustment theoretically necessary, would be difficult ; practically, it would not be done. But the chief embarrassment, even when there is less accuracy sought, is the unequal effect of heat. This subject may be con- sidered under three heads : 297. First. Heating the hoops over a fire to expand them, subjects one part to more heat than another part; the tempera- tures of the surface and the interior are unequal, thus causing irregular strains. This may be remedied by boiling the hoops in water under pressure, if a greater expansion than 212 will give is required ; or in oil they may be boiled at a temperature of 600, until all parts of all the hoops are uniformly heated. The oil would toughen as well as expand the hoops. Second. The Armstrong hoops are often heated to redness, so that they scale freely when exposed to the air. Even at a black heat, a considerable oxidation occurs. Thus the internal di- ameter of th* 1 hoop is increased, and scale is left between some parts, and not between others, thus sensibly deranging the accu- racy prescribed by theory (293). Third. Cast iron and steel sensibly and permanently enlarge, in proportion to the carbon they contain, when, subjected to heat. * Lt.-Col. Clay, of the Mersey Iron Works, specially refers ("Construction of Artil- lery," Inst. C. E., 1860) to this defect. "He knew that iron and steel differed much in their expansion and contraction, and he thought it would be the case with iron generally, according as the crystallized or fibrous structure predominated." 252 ORDNANCE. The same cause would contribute to the minute inaccuracy deprecated by Mr. Longridge, even in case of the low steel em- ployed for guns. 298. A recent series of experiments on the change of figure of metals by heating and cooling, is so remarkable in its results, that many of the failures of guns hooped at high temperature may, perhaps, be traced to this cause. An abstract of the experi- ments is certainly appropriate in this connection, especially as the hoops of the Armstrong and other guns are cooled so as to pro- duce, in some degree, the effects described. "ON THE CHANGE OF FORM ASSUMED BY WROUGHT IRON AND OTHER METALS WHEN HEATED AND THEN COOLED BY PARTIAL IMMERSION IN WATER."* " The experiments were made on cylin- ders of wrought iron, of different dimensions, both hollow and solid, immersed, some to one-half of the depth, others to two thirds; also on similar cylinders of cast iron, steel, zinc, tin, and gun metal. The specimens experimented on were all accurately turned in a lathe to the required dimensions, which were carefully noted ; they were then heated to a red heat in a wood furnace, used for heating the tires of wheels. As soon as they had acquired the proper heat, they were taken out and immersed in water to one-half or two-thirds their depth. The temperature of the water ranged from 60 to 70 Fahr. The specimens were allowed to remain in the water about two minutes, at which time the portion in the air had lost all redness, and that in the water had become sufficiently cool to handle. These alternate heatings and coolings were repeated till the metal showed signs of cracking or giving way." Fig. 143 is one of the illustrations given by Lt.-Col. Clerk. It represents a 12-in. wrought-iron cylinder, ^ in. thick and 9 in. deep, after being heated to redness, and cooled by immersing its lower half in cold water these operations having been repeated 20 times. The upper edge of the cylinder (in the air) did not alter ; the lower edge (in the water) contracted *6 in. in the * Lt.-Col. H. Clerk, R. A., F. R. S. "Proceedings of the Royal Society." RESISTANCE TO ELASTIC PRESSURE. 253 circumference, and at about 1 in. above the water-line the circum- ference was reduced 5*5 in. The general effects mentioned in the paper are "a maximum contraction of the metal about . 1 in. above the water-line; and this is the same whether the metal be immersed one-half or two-thirds its depth, or whether it be 9, 6, or 3 in. deep. With wrought iron, the heatings and coolings could be repeated from 15 to 20 times before the metal showed any signs of separation; but with cast iron, after the fifth Wrought-iron cylinder, after twenty testing, the metal was cracked, and the hollow cylinder separated all round just below the water- line after the second heating. Cast steel stood 20 heatings, but was very much cracked all over its surface. "As respects the change of form of cast iron and steel, the result was similar to that in wrought iron, but not nearly so large in amount. Tin showed no change of form, there being appa- rently no intermediate state between the melting point and abso- lute solidity. Brass, gun metal, and zinc showed the effect slightly; but instead of a contraction just above the water-line, there was an expansion or bulging. " The specimens of wrought iron were submitted by Mr. Abel (chemist to the War Department) to chemical analysis, and he informs me that he found nothing noteworthy in the composition of the metal, nor was there any appreciable difference in the spe- cific gravity of the metal taken from different parts of the speci- men. It appears, therefore, to be simply a movement of the particles whilst the metal is in a soft or semifluid state." 21)9. WANT OF CONTINUITY OF SUBSTANCE. During the last two years the grand defect of many hoops many parts in a gun has been developed in the fracturing and shaking loose of the Armstrong hoops, under the tremendous vibration due to firing 254 ORDNANCE. large charges (335). This subject will be further referred to, in order, and some of the facts will be stated under the head of Wrought Iron.* It is but just to say that the result was predicted in the discus- sion on artillery (1860) already quoted. Mr. Longridge says: " Hoops must always possess the defect of want of continuity of substance. However perfect the workmanship at first, in large guns, the concussion of repeated firing would ere long shake them loose. Those who have had to do with heavy machinery subject to violent jars, such as in rolling mills and forge hammers, know well how impossible it is to keep iron and iron, however well fitted, working together for any length of time without shaking loose. The only remedy is, to separate the pieces of iron from each other by a packing of elastic material, so as to take off the jar. Now the concussions in such machinery are insignificant as com- pared with those in a large piece of ordnance, and therefore the use of hoops for large guns cannot prove satisfactory." Sir Charles Fox, in the same discussion, considers that this objection would " destroy all the advantages of so expensive a mode of con- struction," if the separate parts were not united by soldering or welding. Professor Treadwell anticipated and provided against it to some extent, by screwing the hoops together. The defect "want of strength and solidity in the union of the different parts " is also mentioned by Captain Benton.f 3OO. PERMANENT ENLARGEMENT OF HOOPS UNDER STRAIN. The experience with hooped guns having initial tension is too limited to warrant the conclusion that vibration would not loosen hoops, of a very elastic metal not strained beyond the limit of its elasticity. Still, the loosening of the hoops by the permanent stretching of a metal like wrought iron, would appear to be the * The official report of the experiments, at Southport, with the Whitworth 80-pdr., says that the gun was made of homogeneous metal, and strengthened throughout its whole length by wrought-iron rings, and that "we observed, at the close of the prac- tice, an oily substance oozing out at the junctions of the rings which strengthen the gun on the chase; and also at the face of the piece where the outer and inner cylin- ders meet." f "Ordnance and Gunnery," 1862. RESISTANCE TO ELASTIC PRESSURE. 255 beginning of this kind of failure. The permanent enlargement of hoops under strain not only destroys the original accuracy of tension by reason of its inequality, but actually prevents their hugging the inner barrel after long use. Sir Charles Fox, among others, presented this view of the case in the discussion referred to before the Institution of Civil Engineers. Dr. Hart (286) also expresses the same opinion.* This defect may be remedied in the case of conical rings, which can be tested and set up if required, from time to time, without dismounting the gun, by a comparatively light hydrostatic press that can be transported from fort to fort, or aboard ship. Practically, perfect elasticity would remedy the defect, and this is undoubtedly attainable by the use of steel rings. Hence the practice is changing from iron to steel. Mr. Whit worth and Captain Blakely use steel, and consider wrought iron unfit. Indeed, one manufacturer of guns compares iron hoops, in this particular, to leather. The excellent wrought iron used by Cap- tain Parrott for hoops is nearly as elastic and strong as low steel, so that the embarrassment under consideration has not been experienced with his guns. A high, elastic steel, however, is likely to burst without warning if at all ; while soft wrought iron, especially in the form of concen- tric tubes, will indicate coming failure by stretching, and will, in fact, fail altogether without doing serious damage. In various instances, the outer rings of the Armstrong guns have broken without dangerously reducing the resistance of the gun to burst- ing (445). The first 10- in. gun was fired several times after the bursting of an outer hoop, before the gun failed, and then it failed by the blowing out of the breech, after the strain of a 90-lb. charge. . 3O1. A strong wrought-iron tube, placed loosely outside the steel hooping, would prevent, or at least modify, the disastrous character of an explosion the killing and demoralization of men, and the disabling of adjacent machinery by flying fragments. * Letter to the author, Sept. 8, 1862. 256 ORDNANCE. Sir William Armstrong's assertion, before the Select Committee on Ordnance (1863), that none of the 3000 guns manufactured had "burst explosively" is important in this connection. The low elasticity of the wrought iron caused many failures ; but its high ductility prevented many disasters. It may be practicable to realize the advantages of both these qualities by loosely hooping a steel gun with iron. The additional mass of the hoops would be of farther use in checking the vibration of the barrel. 302. The range of elasticity in the respective tubes, with reference to their distance from the centre of the gun, has an im- portant bearing on the durability of the gun. Supposing the inner tube to have a low range, and the outer tube a high range of elasticity. The inner metal, which is required by the pressure of the powder to stretch most (280), can only stretch least ; and the outer tube, required to stretch least, can elongate far beyond the demand without injury. The result is that the outer tube must be put and kept under an initial tension nearly up to its working load, in order that the " work done " by its minute elon- gation may be equal to that of the inner tube. This severe and permanent strain on the outer tube obviously tends to relax it. On the other hand, if the inner tube can stretch very much with- out injury, and the outer tube can only stretch a little, the initial and permanent stress upon all parts of the gun, in order that it may be uniformly strained under fire, will be very slight, and the tendency to relaxation very limited. (59.) Cast iron, hooped with wrought iron, or with a low steel having a great range of elasticity, is therefore likely to lose its correct ini- tial tension (91). Cast-steel inner tubes, hooped with wrought iron the new Armstrong guns have the same defect. 303. But if a wrought iron or steel tube be placed within a cast-iron casing, and then strained beyond the limit of its elasti- city, or, in other words, permanently stretched, this change of figure will strengthen rather than weaken the gun, as it will place the outer casing in a state of initial tension. This principle of construction will be further considered (320). 304. LONGITUDINAL STRENGTH. The longitudinal strain that RESISTANCE TO ELASTIC PRESSURE. 257 would be imposed upon a gun by statical pressure would occur between the trunnions and the chamber, since, as the internal pressure would tend to carry the shot forward and the chamber backward, the chamber would be prevented from going to the rear only by the tension of that part of the tube which connects it with the trunnions. If the trunnions were behind the chamber, or if the recoil was resisted at the cascable, the longitudinal strain would be due only: 1. To the tendency of the shot to carry for- ward, by friction, the part of the gun in contact with it. 2. To the inertia of the part of the gun in front of the shot. Under the sudden pressure of powder, this inertia of course imposes a con- siderable strain. The theoretical resistance of a cylinder under internal pressure, to cross fracture, is four times as great as its resistance to splitting longitudinally, if the tenacity of the metal is the same in all direc- tions, and if the resistance of the cylinder to bursting is not aided by the strength of the ends or heads of the cylinder. *SO<>. Longitudinal weakness may obviously be modified by placing the trunnions at the rear, at the expense of some complex- ity in the carriage or machinery for elevating the gun. But the same result is attained without this complexity without disturb- ing the usual and convenient preponderance by a strap connect- ing the breech with a separate trunnion-ring. A very strong and cheap breech- strap of this kind is applied by Admiral Dahlgren to all the U. S. Navy cast-iron rifled guns, except the Parrott guns. It is made of bronze, and cast in two pieces; one piece constituting the strap, half the trunnion-ring and the greater part of the trunnions ; the other constituting the opposite half of the trunnion-ring and the remainder of the trunnions. The two parts are riveted together at the trunnions, as shown by Figs. 144 and 145. This breech-strap was designed to remedy another and greater- defect of cast-iron guns than longitudinal weakness the unsound- ness of the casting around the trunnions (390). Mr. C. W. Siemens proposes the following construction, resem- bling Professor TreadwelPs (288) in principle, to meet this defect. 17 258 ORDNANCE. " The longitudinal strength of the gun might be much increased, if, instead of winding wire upon it, it was bound with corrugated bands of steel, put on spirally. He estimated that two-thirds of FIG. 144. FIG. 145. Dahlgren's breech-strap plan. Dahlgren's breech-strap elevation. FIG. 146. the whole tensile strength of these bands would thus be made available for longitudinal strength. He proposed that the core of the gun should be turned with spiral grooves, extending back- ward beyond the bore, and fitting the longitudinal ribs or corrugation of the strips. The strips should be put on under varying tension, while the gun rotated in a bath of solder, in order to unite the several layers."* Breech-screw of Whitworth gun. 3O6. The longitudinal strength of Mr. Whitworth's hooped gun (Fig. 146) is made * "Construction of Artillery," Inst. Civil Engineering, 1860. RESISTANCE TO ELASTIC PRESSURE. 259 ample much greater than that possible in a wire- wound tube, or a tube hooped by plain cylinders, by screwing the breech-plug not only into the central tube, but into one or more of the hoops (44), which, being conical, must be burst, or at least stretched, before they can be drawn backward. 307. Captain Blakely says on this subject:* "Care must be taken to have sufficient longitudinal strength. For this purpose some circumferential strength may well be sacrificed, by casting one part the length of the entire gun, and of adequate thickness. For various reasons it seems better that this single large piece should be the inside, cast iron being admirably suited for the bore of a gun, whereas wrought iron generally has some defect in the welding, which would certainly be penetrated by the gas of the powder. In some cases, for instance in breech-loading guns, it may, however, be preferable to have the longitudinal strength outside. The latter construction has the advantage of giving greater circumferential strength ; for (strange though it may seem) an ordinary cast gun, whether of iron or brass, would be strengthened at the breech by removing one-quarter of the thick- ness from the inside, and replacing the metal with even lead or pewter. The reason of this apparently paradoxical increase of strength is, that each remaining portion could do more work without any part giving way in the proportion of 3 8 to 2 2 or 9 to 4, when the inner part (which must yield first) is larger than as at present in the ratio of 3 to 2. The gain of power by thus per- mitting the outside to exert more of its force is greater than the loss by removing the inner parts, which must have cracked before the outer could be moderately strained. A brass lining near the breech of a gun would evidently add much to its strength. This would also be a convenient way of strengthening mortars already cast." 308. In his pamphlet on tubes with varying elasticity (324), Mr. Parsons says: "In guns on the compound system, made of cast iron, with the breech and reinforce turned down and * "A Cheap and Simple Method of Manufacturing Strong Cannon, 1858." 260 ORDNANCE. wrought-iron or steel hoops shrunk or forced on it, one of two things must be the result, viz. : either the cast iron must be turned down to an extent which would render the gun too weak longi- tudinally, in order to allow it to be compressed sufficiently to obtain any additional transverse strength from the hoops, or, if enough of the cast iron is retained, to provide the requisite longi- tudinal strength, all the wrought-iron rings that can be put on outside will add but little to the transverse strength ; for, unless the cast iron is compressed very considerably, the wrought-iron rings will not come into play before the interior is overstrained or ruptured : on the well-known law, that the amount of exten- sion of any lamina of metal at the interior is to that of the exterior, inversely as the squares of their respective diameters, and when it is remembered that the reinforce, although turned down smaller to receive the rings, is supported by the solid part of the breech at one end, and part of the reinforce remaining its original size at the other end, it is easy to understand that the wrought-iron rings would make but little impression in compress- ing the cast iron, if left of sufficient size to provide the requisite longitudinal strength; however, the best proof of the fallacy of this system will be found in the number of burst guns, embodying this principle in an almost endless variety of form, lying for inspection in Woolwich Arsenal." 3O9. Mr. Lancaster, whose name is well known in connection with the Lancaster gun, states some important experiments with reference to the longitudinal weakness of cast-iron guns as hooped at "Woolwich, and a plan for remedying the defect. It must be re- marked, however, that some, at least, of the guns referred to, were turned down very small before the hoops were applied. Commander Scott says of them :* " Instead, however, of hooping the existing ordnance on a plan which had proved successful, a new pattern weapon, which was thick in front of the trunnions and very thin at the breech, was applied. But as the hooping a a (Fig. 147) did not unite the cast iron to the wrought-iron bands, the weapons had * Journal Royal United Service Institution, April, 1862. RESISTANCE TO ELASTIC PRESSURE. 261 so little longitudinal strength, and were so weak at b J, where the thickness of cast iron was suddenly reduced to two or three inches, that the guns proved unsafe." Mr. Lancas- ter* says: From time to time many FIG. 147. experiments have taken place at Woolwich, and I believe in the course of the experiments some 10000 of public money was expended to see if it was possible to produce a strength- ened cast-iron gun. * * If you leave the end of the gun in its normal state, and merely depend on the tensile strength of so many inches of cast iron, of course it is no use strengthening it on the periphery of the gun, and that gun will burst as near as pos- sible in the same time as if it were wholly of cast iron. That was the result of these ex- periments, and so much so, that, in the results at the proof-butt at Woolwich arsenal, guns burst after 51 rounds of destructive proof. * "A gun was prepared in which the rear end of the gun was turned down over an inch and a half on the posterior quarter, and a longitudinal truss was fitted over it, in this way enveloping the ends an inch and a half, and completely embracing the gun, the wrought-iron hoops being then shrunk on over the longitudinal truss. A very remark- able result was given by this experiment. The gun immediately went up in the scale of strength, under the same condition of 10 pounds of powder, the unit of projectile of a 32-pounder, and so on, increasing every 10 rounds 1 unit; it went up to 81 rounds instead of 51." Mr. Lan- caster therefore proposes the wrought-iron casing (Fig. 148) sup- Armstrong hooped cast- iron naval gun. Scale, in. to 1 ft. * Journal Royal United Service Institution, June, 1862. 262 ORDNANCE. porting the whole rear of the gun. Another plan of hoop- ing, patented by Mr. Lancas- ter, and designed to give great longitudinal strength, is shown by Fig. 149. Cap- tain Blakely also uses a jacket, similar to Fig. 148, in some of his later guns. 31O. If such a casing could be made strong at a feasible cost, and put on tight, it would obviously overcome the difficulty of longitudinal i weakness, arid provide the other advantage resistance to bursting of a long hoop. Steel is already cast solidly into these forms. Messrs. Naylor, Tickers & Co. cast tubes with closed ends, sound enough to be used for hydro- static presses without ham- mering. The Bochum Com- pany (Prussia) have cast bells of 20000 Ibs. weight, from steel very like Krupp's, and made from the same mate- rials, and by substantially the same process hence the best materials for guns. These castings can be farther com- pressed by rolling, or, if cast solid, by forging. But it' would be impracticable to turn and bore the parts with accuracy enough to secure the proper RESISTANCE TO ELASTIC PRESSURE. 263 tension, if they were tapered and forced on by hydrostatic pres- sure ; the contact of the end of the tube with the bottom of the FIG. 149. Lancaster's hooping, to give longitudinal strength. casing would prevent any adjustment of the tension. If the chamber was shrunk on, it would be likely to shrink unequally, on account of the difference of mass at the two ends. But it would be drawn very tightly over the end of the tube by shrink- ing longitudinally, if it was first cooled at the trunnion end so as to nip the tube at that point. This method has been practised at Woolwich, in shrinking together some of the recent experimental guns. 311. The Parrott gun is not weakened longitudinally, like the gun referred to by Mr. Lancaster, because the full diameter of the cast-iron breech is preserved. The increased diameter of the hoop requires certain modifications in the carriage ; but this is not a serious objection. (See note in Appendix.) The longitudinal strength of the Armstrong gun is secured: 1. By making the breech-piece a thick, solid forging with longitudinal grain (9). 2. By notching the trunnion-ring (Fig. 150) over the tubes within it. And 3, by flanging the outer ring over the rear of the breech- piece. (See Fig. 25.) FIG. 150. Armstrong tiuimion-riiiir. 312. LENGTH OF HOOPS. Hoops of considerable length are desirable, to add to the frictional surface, thus giving longitudinal strength to the gun. But length, or continuity, is chiefly desi- 264 ORDNANCE. FIG. 151. Gun burst under a seam in the hooping. FIG. 152. rable to transfer the strain upon one point to a large resisting area. Several guns, reinforced as shown in Fig. 151, were burst at Woolwich. The fracture occurred in the direct line of the joint between the hoops. The long tube (Fig. 152), made from a coil, like the hoops of the Parrott and Arm- strong guns, is for this reason proposed by Commander Scott, for reinforcing old guns, instead of the short hoops used upon the early JBlakely ordnance, each one of which opposes to a strain at any given point only the strength of its own sectional area, without aid from the rest.* 313. An obvious disadvantage of a large number of hoops is that the trans- verse strength of the gun (277) is reduced. The resistance of the staves of a gun to pressure is like that of beams, as the squares of their depths, and their stiffness is as the cubes of their depths. 314. Wire-wound Tubes. Mr. Longridge's plan of winding square steel wire upon a tube with the proper tension, has already been referred to (93). The method of fabrication was u to coil a quantity of wire on a drum, fixed with its axis parallel to that of a lathe on which the gun was placed. On the axis of this drum there was another drum, to which was applied a brake, similar in 68-pounder, hooped as pro- posed by Commander Scott. principle to Prony's dynamometric brake, * Hooped guns will be further referred to in connection with the strains imposed by unequal expansion, due to the heat of firing. RESISTANCE TO ELASTIC PRESSURE. 265 so adjusted as to give the exact tension required for each succes- sive coil of the wire. The whole apparatus was extremely simple, and the wire was laid on with great regularity. Indeed, it is evident the apparatus might be so arranged, as that the process would proceed with the same ease and regularity as winding thread on to a bobbin, and at the same time with the greatest accuracy as regards the initial tension." 315. The first advantage of wire, then, is that it may be cheaply put on with the exact strain theoretically required. A second advantage is that there is less waste material due to want of continuity (292). Another advantage is the superior strength of the material. A piece of iron which will bear a tensile force of 20 tons per square inch in the bar, will bear 40 tons per square inch when made into small wire; and steel wire has borne 120 to 130 tons per square inch. Mr. Bramwell states that in No. 22 music-gauge steel wire the strength ran as high as 142 tons (318080 Ibs.) per square inch.* 316. Although advocating hoops, Captain Blakely recognizes the advantages of wire, and in the discussion referred to,* " fully agreed that greater strength could be obtained by the use of wire than in any other manner. Indeed, if monster cannon were wanted mortars to throw shells of several tons' weight, to a distance of several miles, for example recourse must be had to wire. He believed that such guns could be made by that system ; but he doubted if they could be manufactured in any other way." 317. The first great defect of wire is want of longitudinal strength. This must be supplied by the inner barrel or by some additional outer material ; it cannot, as in the case of hoops, depend on the material that reinforces the barrel. When it is considered that the breech of the 10| inch Armstrong gun (446) was blown out by a strain intended for ordinary practice, pulling apart in the direction of the fibre, a tube of wrought iron 28 in. in diameter with walls nearly 6 in. thick, the necessity of avoiding longitudinal weakness becomes evident. Mr. Longridge proposes * "Construction of Artillery," Inst. C. E., 1860. 266 ORDNANCE. to supply this strength by material outside of the gnn proper. Indeed, he considers this plan better for all built-up guns. 318. The second defect of wire is the uncertainty of fastening it in such a manner as to prevent its uncoiling.* This diffi- culty becomes serious if the gun is hit by an enemy's shot, and dislocated or broken at various places. To avoid it, an exposed gun must be heavily jacketed, which adds to its weight all that would be saved by the superior strength and more accurate ten- sion of the wire. Mr. Longridge fastened the wire in his experi- mental guns by solder, and secured the ends by placing them in a hole drilled into the casting. 319. If the inability of the Armstrong gun to resist the destructive effects of vibration is due mainly to its great number of layers to its want of homogeneity irrespective of the low elasticity of the wrought iron of which it is made, then the wire- wound gun is certain to fail from this cause. But as far as a high degree of elasticity can remedy the defect, steel wire is obvi- ously the best material. The practice is thus far too limited to warrant very positive conclusions on this subject. The experi- mental wire guns already described (96 ; 102) did not show any remarkable weakness in this direction ; but they were very small guns. A method of placing the laminae of a solid gun under the proper initial strains, realized to some extent by Captain Rodman in his hollow-cast guns, will be considered under the head of Cast Iron. 320. III. Hoop \v i Hi varying elasticity. Let us now suppose the hoops or tubes forming a gun to be 'fitted together accurately, but without tension. If the inner hoop is very elastic, and the next less elastic, and so on throughout the series, the outer hoop being least elastic, and the degree of elasticity exactly proportioned to the degree of elongation by internal pressure, all the hoops will be equally strained by the powder, and none of their strength will be wasted. Supposing the inner hoop to be * This objection was specially mentioned by Mr. Gregory, Y. P., and Mr. John Anderson, in the discussion referred to. RESISTANCE TO ELASTIC PRESSURE. 267 stretched by the pressure ^o inch, and the outer hoop T 7 inch (280), the material of the inner hoop should have such elasticity that it would be no nearer its breaking point when stretched T V inch, than the less elastic outer hoop when stretched T 7 inch. Both hoops would then be equally strained by the powder, and oppose an equal resistance to it. The distinction between regularly increasing elasticity, c.s de- scribed, and uniform elasticity, should be clearly made. Supposing both hoops to be capable of safely stretching T V inch, the outer hoop is, in actual practice, stretched only T ^ inch, and hence brings but T V of its strength into action when the inner hoop is stretched to the limit of safety. If the elasticity regularly in- creases from the centre outward, the outer hoop is stretched still less when the inner hoop is at the point of bursting. 321. The-re are, at present, no proper materials haying the respective ranges of elasticity necessary to perfectly carry out this principle. But if the inner tube of a gun were made of a very elastic steel, and the outer tube of cast iron, the relative strain and stretch would be approximately correct, and a small weight of steel within the cast iron would be much better employed than a greater weight outside of it. In the first case, the heat of the burning powder would, by expanding the steel, and so putting the cast iron into tension, compensate for any want of elasticity in the steel, thus realizing, to a certain extent, the advantages of hoops with initial tension. In the other case, the heat would stretch the steel reinforce beyond its proper tension (that having already been adjusted), and unequally strain the thick cast-iron barrel by expanding its inner layers. 322. In case of the steel lining, the trunnions could be cast with the reinforce, and the total thickness of the gun could be adjusted to the strain at all points, without re-entering angles, by preserving, approximately, the Dahlgren shape. In the other case, the trunnions (if the reinforce was long, as the English gun- makers prefer it) would have to be forged upon a separate ring, and secured at a considerable cost, and the exterior of the gun would be a series of sharp angles and short curves. 268 ORDNANCE. The steel lining could be applied to old guns without changing their appointments.* Applying a steel reinforce to an old gun would increase its preponderance to an inconvenient or impracti- cable degree, or else require new trunnions, and it would necessi- tate alterations in the carriage, f * Such a lining in a gun is likely to prevent explosive bursting the flying of pieces in case the cast-iron or steel shell fractures. Captain Palliser states that he has burst the outer cast-iron gun without bursting the inner wrought-iron tube (on account of its greater ductility), and that the cast-iron pieces did not fly. It has been lately proposed, by Mr. J. K. Fisher, of New York, to secure the necessary difference in elastic range, by hardening the inner part of a solid steel gun in oil, or by otherwise tempering a solid gun, so that the ranges of elasticity in the different layers would be proportioned to their required elongation. f The author deems it just to state that the above was written before the publica- tion of Captain William Palliser's patent for this improvement, dated Nov. 11, 1862, and of Mr. M. P. Parsons's patent, dated June 5, 1862 a patent in which Mr. Parsons described a structure by which he now proposes to carry out the improvement, but in which he did not specify the principle of varying elasticity. Upon further investigation, it appears: 1. That Captain Palliser cast guns over wrought-iron tubes as early as September, 1854. In a letter to the Time*, written Oc". 1, 1863, he says: "Having, during the years 1833 and 1854, been engaged in experimenting with elongated shot designed for smooth-bored cannon, I soon found that it was dangerous to fire such heavy projectiles from cast-iron guns with full service charges; and thus it happened that my attention was directed, at such an early date, to strengthening those guns. I had, some time previously, witnessed the manufacture of wrought-iron twist barrels at the forge of Messrs. Truelock and Harris, gunmakers, of Dublin, and at the same time was informed of the great strength that was acquired by this mode of manufacture. I commenced my first experiments in September, 1854, by casting some small cast-iron guns over tubes of wrought iron similarly constructed. I found that guns made in this manner were enormously strong, and, in fact, that they could not be burst by any fair means. After I had concluded these experiments, I constructed a model gun, which I have still in my possession, and which was completed on the 10th of November, 1854, as the accompanying letter will show: " '15 GATE STKKET, LINCOLN'S- INN-FIELDS, Sept. 23. " ' Sir, On referring to our books, we find that we finished turning a model cannon for you on the 10th of November, 1854; the cannon was of cast iron, cast over an internal tube of wrought iron. " 'We are, Sir, yours faithfully, " ' CLARK & CO., Engineers. "'CAPTAIN PALLISEE.' "Now, this model was completed before any patent had been taken out for strengthen- ing or constructing guns on any method in the least degree similar." Still, casting a gun over a wrought-iron tube, although it involves the principle of varying elasticity, involves also such mechanical difficulties and objections, that it has not been practised, even by Captain Palliser. RESISTANCE TO ELASTIC PRESSURE. 269 333. In I860, a cast-iron 68-pounder gun (Fig. 153) was bored out and shrunk over a wrought-iron tube, at Woolwich. The endurance 71 rounds with increasing charges was very satis- factory, seeing that the cast iron was necessarily warped and strained by the heating. In 1862, a 32-pounder was similarly treated, and stood 74 rounds with increasing charges. The details of the experiment are given in Table XIII. 324. MR. PARSONS'S METHOD. The principle of variable elasticity is thus stated by Mr. Parsons :* "Wrought iron may be extended about '0015 of its length 2. It farther appears that Captain Blakely proposed, not very fully, but quite dis- tinctly, to strengthen guns by inner tubes of a more elastic material, in a pamphlet entitled "A Few Remarks on the Science of Gunnery," published in 1857. After proposing to construct guns upon the theory of definite initial tension, as already explained, and specifying several ways of doing it, Captain Blakely says, "or, a more elastic material may lie put into a less elastic one, with no initial strain, or very little" 3. Captain Blakely also specifies the improvement very fully in an addition, dated April 4, 1860, to his French patent of June 28, 1855. 4. In January, 1863, Captain Palliser issued, for private circulation, a pamphlet with drawings, explaining, in considerable detail, the principle and the means of carry- ing it out. A 68-pounder cast-iron gun (332) has since been strengthened on Ms plan, at "Woolwich, and tested with great success. 5. In the autumn of 1863, Mr. Parsons issued an illustrated pamphlet entitled "G-uns versus Armor Plates," explaining the principle and his plan (patented before Captain Palliser's) of adapting it to service. The three publications last named will be farther referred to and quoted. The foregoing facts are not intended as an exhaustive history of the invention. Great credit is due to Captain Palliser for obtaining an official trial, and for achieving so much success in strengthening old cast-iron ordnance. The following singular arrangement of metals is described in Simpson's "Ordnance and Naval Gunnery," ]862: "Mr. J. C. Babcock, of Chicago, suggests another way of arranging the metal for the spirals, wrapped around the cast-iron core, founded on the different expansive properties of metals. He recommends that the core be of cast iron; on this shrink a layer of wrought-iron rings; these, with the cylinder, should form about one-half of the thickness of the gun. Bands .of steel should now be wound spirally, in alternate layers, to the required thickness, reversing the winding of each layer, so as to break joints. "The arrangement of the materials in the order of their expansive properties gives more work to the exterior of the gun, for cast iron is doubly more expansive than wrought iron, and wrought iron even doubly more expansive than steel. All parts of the wall of the gun would thus bear a strain at the same time, and there could be no bursting by successive layers, as has been shown, in an earlier portion of this work, is the case with a cast-iron gun where the expansive capacity of the wall is constant throughout the entire thickness." * "Guns versus Armor Plates, etc.," 1863. 270 ORDNANCE. without injury to its elasticity, and it requires a strain of about 14 tons per square inch, or about f of its ultimate breaking weight to effect this. " Cast iron is permanently injured if stretched from about '0004 FIG. 153. 68-pounder shrunk over wrought-iron tube, at Woolwich, I860. to '0005 of its length, which is effected by a strain of about ^ of its ultimate breaking weight, or from 2^V tons to 4 tons per square inch. Therefore, wrought iron may be stretched three times as much as cast iron, and will offer from three and a half to six times the resistance to the force applied, within the limits of elas- ticity. " Now the strain on a gun is greatest on the metal at the rein- force immediately surrounding the bore, and gradually decreases towards the exterior where it is least, the strain on any particular circumference or layer being inversely as the square of its diame- ter. It is therefore evident that if the wrought iron is placed inside, and the cast iron out, they will each be arranged in the best position to sustain the strain without injury, and an investi- gation of the relative extensions of both under strain, will show, that in this position the two metals will, if properly proportioned as to size, work together, and each sustain its proper tensile strain, without being subjected to any initial tension, and conse- quently without the risk and uncertainty of the correct amount being applied." 325. This method proposed by Mr. Parsons of strengthening a 68-pounder cast-iron gun, is illustrated by Fig. 154. He says : RESISTANCE TO ELASTIC PRESSURE. 271 Fia. 154. " A conical recess of the form shown is bored out of the breech end of the gun, and a tube of wrought iron is turned and fitted into the recess,, and secured in its place by the breech-plug. In guns of this size, I recom- mend the lining tube to be made up of an inner tube, surrounded by hoops or tubes, shrunk, forced, or screwed on, arid then turned to the proper size. The lining tube has a breech-plug of its own, which is for the pur- pose of preventing the explosive gases getting between the end of the lining tube and the breech-screw, and by acting on its larger area endangering its security. It is not requisite for the lining tube to be forced into the recess made in the reinforce of the gun, in order to produce an initial strain on it and the cast iron (as will be shown by the calculations of its strength), all that is necessary is to make it a fair and easy fit, but its length is so adjusted, that by screwing up the breech-screw it may be compressed longitudinally between it and the shoulder of the recess by which the entire longitudinal strength of the cast iron is im- parted to it. * * * Again, the strain is considerably greater at the breech end of the bore than on any other portion of its length, the pressure of the explosive gases being but about one-fourth when the projectile has reached a distance of about 4 times that occu- pied by the powder of the charge, so that it will be only necessary for the lining tube to extend about this distance." 326. It would appear safer, however, in view of the known weakness of breech -load- ing guns, to allow the lining tube to extend the whole length of the gun. Unnecessary strength at the muzzle is better than want 68-pounder, strength- ened by Parsons's in- ternal tube. Scale, 7 in. to 1 ft. 272 ORDNANCE. of continuity and homogeneity at the seat of the maximum pressure. An objection to extending the tube to the muzzle of the gun is, that the cast iron would there, being bored out to a mere shell, possess little resistance to the enemy's shot. But in turrets and modern casemates, a gun is little exposed. Indeed, the greater part of the cast-iron chase might be removed entirely without weakening the gun, thus allowing the use of smaller embrasures. Captain Palliser, it will be observed (329), allowed the internal tube to project beyond the old cast-iron muz- zle, thus securing the additional advantage of greater length of bore. 327. Mr. Parsons makes the following calculation of the strength of an ordinary cast-iron 68-pounder, and of the same gun strengthened as shown in Fig. 154 : TABLE XLIX. "CALCULATION OF THE STRENGTH OF AN ORDINARY SERVICE 68-PouNDER CAST-IRON GUN. Transverse Strength at Reinforce. Diameter of bore 8 inches. Outfide diameter 26 inches. " Supposed to be divided into 9 rings or layers each 1 inch thick. The first ring being strained to the full amount of its elastic limit, taking a unit in length of 1 inch, we have : Tons. 8-00 I ft Layer Inch. Sides. I x 2 - Sq.i = 2 8 8 8 8 8 8 8 n. Tons. x 4 = I0 2 I2 2 i6 2 i8 2 20 2 22 2 2d Layer as Inversely. 8 2 7d do. 8 2 4th do 8 2 5th do 8 2 6th do. 8 2 yth do g 2 8th do 8 2 qth do. .. 8 2 12 5 6 2-61 2-00 I. 5 8 1-28 I- 06 89 Tranfverfe ftrength of a unit in length of i inch Tons 26-10 Tons. 26-10 and r= 3 -26 Tons = Tranfverfe ftrength per each fquare inch of the bore. 8 in. diameter of bore. RESISTANCE TO ELASTIC PRESSURE. 273 Longitudinal Strength. Area of 26 inches (outfide diameter) area of 8 inches (diameter of bore) Sq. in. Sq. in. Sq. in. Tons. = 530 50 = 480 x 4 =1920 Tons, and 1920 =38-4 Tons = longitudinal ftrength per each fquare fq. in. 50 area of bore inch of the area of the bore." TABLE L. "CALCULATION OP THE STRENGTH OF THE SAME 68-PouNDER CAST-IRON GUN, STRENGTHENED BY A WROUGHT-lRON LINING TUBE. "In putting together the lining tube of the strengthened 68-pounder gun, the outer rings are shrunk on to the inner tube, and their sizes so adjusted, that, by contraction of the outer rings in cooling, there will be an initial tensile strain equal to about half the elastic limit of the metal, which will produce a nearly corresponding amount of compression on the inner ring, so that when the inner surface of the inner ring is strained to the full extent of its elasticity, the inner surface of the outer ring will be equally strained. " Following, then, the same method of calculation, and dividing the gun into imaginary layers 1 inch thick, as before, we have : Lining Tube Transverse Strength. First ring Inch. Sides. Sq.in. Tons. Tons. ift Layer 1x2 = 2x14=: 28-00 Tons. 2d Layer as 8 2 : 28 : : io 2 : 17.92 Second ring Inch. Sides. Sq.in. Tons. Tons. ift Layer I x 2 = 2 x 14 = 28-00 Tons. 2d Layer as I2 2 : 28 : : 14" : 20-57 Tranfverfe ftrength of a unit in length of I inch of lining tube Tons.-94-49 18 274 ORDNANCE. "Cast- Iron Casing. " When the interior of the lining tube is strained to its elastic limit, which will extend it about -0015 of its length, the relative extension of any layer being inversely as the square of its diameter, it follows that the extension of the outer surface of the lining tube at the same time will be inversely, as 8 2 : '0015 : : 16 a : '00038, or nearly '0004, and the lining tube being inserted into the breech a fair fit, without any material initial strain being put on either it, or the cast iron encasing it, the extension of the interior surface of the cast iron will be the same, or nearly the same, as the exte- rior of the lining tube. "Now, with an extension of about '00042, cast iron is strained to about the full limit of its elasticity ; or, taking the same coeffi- cient as before, to about 4 tons per square inch, and continuing the calculations of the cast-iron cylinder of the reinforce on the same system, we have: Transverse Strength. Ins. Sides. Sq.in. Tons. Tons, ift Layer i x 2 = 2 x 4 = 8-00 Tons. 2d Layer as i6 2 : 8 : : i8 2 : 6-32 jd do i6 2 : 8 : : zo 2 : 5-12 4th do i6 2 : 8 : : 22 2 : 4-23 5th do i6 2 : 8 : : 24 2 : 3-56 Tons zy -23 Add ftrength of lining tube 94'49 Tranfverfe ftrength of a unit in length of i inch Tons. ..121 -72 Tons. Tons. 121 -72 and = 15-21 = Tranfverfe ftrength per each fquare inch of the bore. Longitudinal Strength. "The longitudinal strength, taking the section through the weakest part of the cast-iron shell, will be: RESISTANCE TO ELASTIC PRESSURE. 275 Ins. Ins. Sq. ins. Sq. ins. Sq. ins. Area of 23 area of 12 = 415 113 = 302 Sq. ins. Tons. Tons. Tons. 1208 and 302 x 4 = 1208 and - - = 24-16 Tons fq. ins. 50 area of bore = longitudinal ftrength per each fquare inch in the area of the bore. " This is not taking credit for any longitudinal strength derived from the lining tube ; so that the strengthened gun shows a strength nearly live times as great as the same gun in its ordinary state. u To effect this, about 13^ cwt. of wrought iron, made into a coiled tube and rings, and about 6 cwt. of cast iron will be required." 328. CAPTAIN PALLISER'S METHOD. In his patent dated No- vember 11, 1862, Captain Palliser thus states the principle of varying elasticity : " My general principle for the construction of ordnance consists in forming the barrel of concentric tubes of dif- ferent metals or of the same metal differently treated, so that, as nearly as possible, owing to their respective ranges of elasticity, when one tube is on the point of yielding all the tubes may be on the point of yielding. It thus differs essentially from the method hitherto prevalent of equalizing strains on concentric tubes by placing an initial or permanent strain on the exterior ones. Since the power of any substance to resist an impulsive strain is meas- ured by the product of the resistance it offers while stretching into the distance through which it can stretch ; and since the interior surface of a gun stretches most, it will follow that an extensible substance at the interior of a gun will offer the greatest resistance to the impulsive pressure of the discharge, while it will evoke the greatest amount of assistance from the exterior portions of the gun ; I therefore make the interior of the barrel of a tube of the most ductile wrought iron coiled round a mandrel, so that the grain or fibres of the iron may run circumferentially or spirally." There appears to be some confusion of terms in this specifica- tion. A wrought-iron tube does not accomplish the purpose spe- 276 ORDNANCE. cified because it is very ductile, but because it has a high range of elasticity , i. , and continue to vibrate, but, owing 298 ORDNANCE. to atmospheric resistance and imperfect elasticity, it will finally be brought to rest at P 1 ', the point of statical equilibrium. So that, the more slowly a force is applied, the less the resisting body will be strained by being moved beyond the position of statical equilibrium. Referring to this illustration, Captain Rodman says :* " The excess of strain due to the rate of application of any force, above that due to its statical equilibrium, is caused by the momentum or living force developed in both the straining and resisting bodies, up to the time when they attain their position of statical equilib- rium, or by the momentum at which they arrive at that position. To illustrate : suppose the sum of the masses of the resisting body a b and of the weight P to become infinitely small as compared with that assigned them in the discussion above referred to ; and the force of gravity to be so increased as to cause their weight to remain constant, and the resisting power of a b to remain the same. "These hypotheses would not change the position of statical equilibrium, and the moving and resisting bodies would reach that position with the same velocity as before ; but their mass being, by hypothesis, infinitely small, their momentum at that position would also be infinitely small, as compared with its value under the former hypothesis, and they would consequently be carried by that momentum only an infinitely small distance beyond the posi- tion of statical equilibrium. The ultimate strain would, conse- quently, under this hypothesis, be independent of the rate of ap- plication of the straining force. " The statical pressure exerted upon that portion of the surface of the bore, around the seat of the charge, in firing a 10-inch gun with service charges and solid shot, cannot be less than 50000 Ibs. per square inch. The weight of a body that would produce this amount of statical pressure per square inch, on the area of a cross-section of the bore of that gun, would =78-54 x 50000= 3927000 Ibs. This would be the weight of the moving or strain- * " Experiments on Metals for Cannon and Cannon Powder," 1861. ELASTICITY AND DUCTILITY. 299 ing mass necessary to render the remarks, in the discussion above referred to, applicable to a 10-inch gun ; whereas, in the discharge of cannon, the charge of powder is the moving mass, and that portion of the gun around the seat of the charge is the resisting mass. " The extensibility of gun-iron is, at the highest estimate, not over '004 in. per inch in length. The increase in diameter of the bore of a 10-inch gun would therefore be, at the moment of interior rupture, =-04: in., and the extent of radial motion of the surface of the bore would ='02 in. The surface of the bore would have a greater extent of motion than any other part ; and if there were no other resistance to motion than the inertia of the mass of the metal around the seat of the charge, the velocity developed in that mass, in passing over a space of "02 in., would be very trifling indeed, and the momentum correspondingly small. " The sum of the moving and resisting masses in the case of a 10-inch gun, as compared with that of a body whose weight = 3927000 Ibs., would be very small ; nor can the radial velocity of the charge, at the moment when the bore attains the diameter due to the statical pressure exerted upon it, be so great as to ren- der its momentum of any considerable magnitude ; from which it follows that, in firing cannon, the excess in strain upon the gun, above that due to statical pressure, caused by the most rapid rate of application or development of that pressure, is a very small percentage of the total strain. " This reasoning, and the conclusion to which it leads, must not, however, be construed into a disregard of the rate of combustion of the charge, for this is of primary importance ; but from causes entirely different from that discussed above." * * * " It is well known and understood, in architecture and practical mechanics, that a given beam of wood or bar of iron will sustain, for a limited time, a weight w T hich would be certain, ultimate- ly, to break it ; and, in general terms, that the rupturing force is a decreasing function of the time required for it to produce rupture. 300 ORDNANCE. "It is believed, however, that we have not heretofore properly appreciated the effect of time on the resistance which a body can offer, where the absolute difference in the times of action is small, but where the ratio of the maximum to the minimum time of action is very great. For example : the time required to rupture a tensile specimen of cast iron on the testing machine is, say, five minutes. This is a small absolute space of time, and the differ- ence between this and any smaller space must be still less ; but as compared with the length of time during which the maximum pressure is exerted upon the bore of a gun at a single discharge it becomes very great ; probably as great as the ratio of the time of existence of any known structure of either wood or iron to that required to test the strength of a single specimen of either material. And if so, why should not the resistance of a gun or shell, to a single discharge, be as much greater than indi- cated by the test specimen, as the permanent architectural load required of any material is less than that indicated by the test specimen ? " The results of different experiments which I have made, indi- cate that such is the fact. For example : in bursting cylinders with powder (see page 192, Report of 1860), set No. 1, with a thickness of metal of *5 inches, gave a bursting pressure per square inch =37842 Ibs., and requiring a tensile strength of iron =75684 Ibs. per square inch, while the tensile strength of the iron by the testing machine was only 26866 Ibs. And in set No. 4 (same page and report), with 2 inches thickness of metal, the bursting pressure was 80229 Ibs. per square inch, while the most that it could have been by the testing machine would be twice the ten- sile strength, or 53732 Ibs. " These same results, as well as others, show the important dif- ferences in resistance due to differences in time of action, when the greatest duration was so small as to be entirely inappreciable to the senses. Take, for example, sets Nos. 1 and 2 of the same cylinders just referred to. These sets w^ere both of the same inte- rior capacity, same metal, near as could be, and were burst by equal charges of powder of the same quality. Set No. 1 was '5 ELASTICITY AND DUCTILITY. 301 inch thick, and set No. 2 was 1 inch thick. The mean bursting pressure of set 'No. 1 was 37842 Ibs. per square inch, while set No. 2 was only 38313 Ibs. One cylinder of set No. 2 required two charges to burst it, the indication of pressure being something less for the second than for the first charge.* Now the only true explanation of these results is believed to be, that 38,313 Ibs. was the pressure due to the combustion of the charge of powder used, in the space in which it was burned ; that it did not greatly exceed the resisting power of the cylinder of set No. 2, and required a greater, though still uriappreciable length of time, to produce rupture (as is indicated by the fact of one cylinder forcing the whole products of combustion of one charge out through a hole one-tenth of an inch in diameter, without bursting), while it greatly exceeded the resisting power of set No. 1, and consequently burst that set in much less time, but not before almost the full pressure due to the charge of powder used had been developed. * * * " Now the difference in the times of action of the forces in all these examples was entirely inappreciable to the senses, yet the ratio of the greatest to the least must have been very considerable. And in the ordinary discharge of cannon the gun is subjected, at each discharge, to a force which would inevitably burst it, if permitted to act for any appreciable length of time ; so that it may be said that cannon do not burst because they have not time to do so before the bursting pressure is relieved." 148. The apparent increase of strength by stretching may be otherwise accounted for. Mr. Colburn says: ' ; Mr. Thomas Lloyd, Engineer to the Admiralty, made a like series of experiments, a few years ago, on 10 bars of SO Crown iron, If inch diameter and 4|- feet long. The mean breaking weight at the first breakage was 23*94 tons per square inch. At the second breakage, with pieces 3 feet long, the mean strength was 25 '86 tons per square inch; at the third breakage, with pieces 2 feet long, 2T'06 tons per * The pressures were determined by Captain Rodman's indenting apparatus. 302 ORDNANCE. square inch ; and at the fourth breakage, with 15-inch lengths, 29-2 tons per square inch. Mr. Lloyd's experiments have been held to show that iron was actually strengthened by stretching it ; or, in other words, that by destroying the cohesion at one point, the cohesion was everywhere else increased. A more obvious ex- planation is, that the bars first broke at the weakest part, then again at the next weakest part, and so on. A variation of from 23*94 tons to 29*2 tons in the strength of the same bar is undoubtedly large, the greater strength being 22 per cent, more than the lesser ; a difference which appeared to exist in each of the 10 bars tried. It is well known, however, that hardly any two bars of iron have exactly the same strength, and Mr. William Roberts, manager of Messrs. Brown, Lenox, & Co.'s extensive chain-cable works at Millwall, has cast a 12-ft. bar of iron into 2-ft. lengths, and found, on testing, that there was a difference of strength of 20 per cent, between the strongest and the weakest of these pieces. In the experiments of the Eailway Iron Com- mission upon the extension of cast iron, the strength of Low-Moor cast bars was 7*325 tons per square inch at the first, and 8*152 tons at the second breaking. Blaenavon iron broke with 6'551 tons per square inch at the first, and 6*738 tons at the second breakage. Gartsherrie broke with 7*567 tons per square inch at the first, and 8*475 tons at the second breakage. Other cast-iron bars of a certain mixture broke with 6*6125 tons per square inch at the first, and 6*777 tons at the second breakage, the latter being at an unsound place. Upon these results the commissioners remarked, that ' it would appear that iron repeatedly broken be- comes more tenacious than it was originally. This erroneous conclusion may be obviated by considering that it would be very difficult, if not impracticable, to obtain cast-iron bars perfectly sound and 50 feet long. Fractures may be supposed to take place the first time at the largest defect, and subsequently at those smaller, until finally none remain.' r The permanent stretching of the interior layers of a gun with- out initial strains would tend to put them into compression, and the exterior layers into tension, which is a condition of strength (405) ELASTICITY AND DUCTILITY. 303 349. SAFETY OF DUCTILITY. WORK DONE IN STRETCHING. Mr. Mallet considers soft wrought iron the proper cannon metal for another reason : the work done in greatly stretching a bar of soft wrought iron beyond its elastic limit to the breaking point, considerably exceeds the work done in slightly stretching a less ductile but very much more tenacious metal, such as high cast steel, to the breaking point (352), (466). Mr. Mallet does not pro- pose to load wrought iron above its elastic limit, but advocates its use because there is such a large margin of safety between the elastic limit and the breaking strain. If the former is accident- ally, or through defects in the metal or the fabrication, exceeded, the gun will still be far from the bursting point, and may consid- erably stretch and give ample warning. But when the elastic limit of high steel and other slightly ductile metals is reached, and it is at any time likely to be, through defective material or fabrication, fracture occurs almost immediately. Very little " work done" is then required to reach the breaking point. Mr. Mallet admits, however, that high steel is perfectly safe, if this margin of work done is provided for by an excessive quantity of material. In other words, there must be provision for the expen- diture of a great power between the working strain and the ulti- mate tenacity. Wrought iron provides this by its ductility. High steel and cast iron, and all less ductile metals, provide it only by excessive quantity, so that the working strain shall never exceed the limit of elasticity. 350. But if wrought iron changes figure under the strain of gunpowder, although it may have a higher tenacity, it ultimately loses its ductility by stretching, and thus gradually approaches the position assigned by Mr. Mallet to high steel and cast iron without a ma/rgin of safety. If any of the material is bad (it may even have been fractured in some unseen part), or if accidental over- pressure occurs, there is then very little " work done" required to reach the breaking point. !N"or is this the only defect of stretched wrought iron. As compared with steel, it has very little elasti- city, which still more reduces the above margin of safety. 304 ORDNANCE. Thus, although the rupture of wrought iron may at first require of any force in motion vastly more effort than the rupture of steel, it would appear that if the wrought iron is stretched by gunpow- der beyond its elastic limit, it gradually assumes the very defect ascribed by Mr. Mallet to steel, although it may gain in ultimate tenacity by stretching. So that a wrought-iron gun must origin- ally have a greater excess of material a greater thickness of wall than steel, because the strain required to reach its limit of elas- ticity is less ; or else, it must deteriorate with use, while steel will never deteriorate if the strains imposed upon it do not perma- nently change its figure. 3T1. So long as the pressure in a light wrought-iron gun is kept below the limit of elasticity, it may be as safe as a heavy steel gun. But the demand is for the highest possible pressure upon the shot, and hence upon the gun. The strain required to reach the limit of elasticity is much greater for steel than for iron, so that steel can endure the greater pressure, and propel a given shot with the higher velocity, without a permanent change of figure. 352. Mr. Mallet's reasoning and conclusions are as follows :* " From these tables (51, 52, and 53) the succeeding diagram (Fig. 160) has been produced, in which the quadratures of the four curves indicate the values of Te (foot-pounds in reaching the elas- tic limit of tension), and Tr (foot-pounds to produce rupture by tension, for cast steel, harsh strong iron, soft strong iron, and wrought iron of extreme ductility but of moderate strength). From d' the origin, d' y is the ordinate of strain in kilogrammes, and d! z the abscissa of extension in millimetres. The curve d' A, nearly a right line, is that for the extension of cast steel ; the curve d' B, that for harsh, strong wrought iron ; d' C the curve for soft strong iron ; and d r D that for extremely ductile but not very strong iron. " On the known principles of vis viva, the c work done 7 in each case in producing these extensions will be equal to one-half the * "On the Construction of Artillery," 1856. ELASTICITY AND DUCTILITY. 305 quadrature of each respective curve. It is obvious, then, to the eye, that although the strength of cast steel (its ultimate cohesion) is enormously greater than that of the very ductile iron, still, from FIG. 160. 50 60 10 1OO HO 120 ISO the greater range of extension of the latter, in the abscissa d! z, the ' work done' in producing its extension to final rupture, or even its extension within the elastic limit,* is enormously in excess of that required to bring the cast steel up to the point of rupture. In fact, in round numbers, it will require of any force in motion above 50 times the effort to rupture a given section and length of ductile wrought iron, that will rupture the best and toughest cast steel ; while again, for the very ductile wrought iron, its value for Tr is nearly 650 times that for Te, so great is the range or limit of work to be done between the elastic (safe) limit and that of rupture. " Hence it follows, that a gun formed of cast steel or of harsh, strong wrought iron, provided it have an enormous surplus of * The statement as to the work done in producing the extension of iron and steel w'tlnn the elastic limit should be compared with Mr. Mallet's tables (353). 20 306 ORDNANCE. strength above the highest strain to which it is to be exposed, will be very safe ; but if its proportions be reduced within a narrower limit of balancing the final resistances with the bursting strain, or if the latter be brought up, accidentally or otherwise, so as to approach such balance, the cast steel or the harsh wrought iron will be the most unsafe gun possible, while in all cases the gun of ductile iron will be the safest. This might be popularly illustrated by saying that the former gun approximates to one of enormous strength, but made of glass ; while the latter approximates to a gun made of sufficient strength, if conceivable, of leather or india-rubber, or to the silt-wrapped guns of the Chinese. " The highest possible ultimate cohesion is, no doubt, most de- sirable ; but this quality alone will not answer for ordnance (or for any other purpose in which impulsive strains are concerned) ; it must be united with the largest possible amount of ductility within the elastic range* to give security ; or, otherwise, security must be purchased by the accumulation of an immense overplus of material." 353. Mr. Mallet's conclusions about the superiority of wrought iron to steel, when the amount of material used is proportioned to the ultimate cohesion of the respective metals, are obviously cor- rect and useful. But he appears to have been so absorbed in his crusade against steel, that he allowed himself to found another theory against it, on an obvious inconsistency in his own tables, find in the table on page 73 of his work, the following : Nature of Metal, and Authority. Elongation at limit of elasti- city Length of bar =1U Correspond- ing strain, in pounds per square inch. Eatio to the ultimate co- hesion. Value of coeffi- cient of elasti- city, in Ibs. per square inch. Caft fteel (Englifh), blue temper Ditto (MorinX mean 002.2,2, 93,866 o -67 42,6667 CO * Mr. Mallet's Tr = foot-pounds to give rupture by tension, the value of which does not appear, if "ductility within the elastic range" is all that must be united with the highest ultimate cohesion to produce a good cannon metal. ELASTICITY AND DUCTILITY. In the table on page 79 we find the following: 307 No. Metal. i Extension per unit of length up to elastic limit. Strain per unit of section at elastic limit. P Strain in tons. Te = i Pi Value for unit of length and section. Coefficient of elasticity for unit of section. Lbs. Dynams. Lbs. I Caft fteel (Englifti), blue temper OOO22 4.704.0 21 -O 5*171 4.26667 co 3 Wrought-iron bar (maximum du&ility) 00090 17024 7-6 7.660 25000000 No. 1, from Morin's experiments on flexure of dynamometric springs. It is obviously an error to say that of two steels described as the same, and having the same coefficient of elasticity, one should elongate within its elastic limit -00222, with a strain of 93866 Ibs., while the other should elongate within its elastic limit '00022, with a strain of 47040 Ibs. Referring to the latter table, Mr. Mallet remarks : " In the case of tempered cast steel, although the resistance to a passive strain is taken as high as 21 tons per square inch, yet from the extremely small range of extension, the ' work done' to bring it to the limit of its safe load is found to be less than that required for the soft ductile wrought iron, that will only bear a passive load of about one-third as much as the steel, in the ratio of 5'175 : 7'660." Now, instead of 5'175, the u value for a unit of length and section" will be 52*214, if the elongation at limit of elasticity is taken at '00222 instead of '00022. And if, instead of taking the strain at elastic limit per unit of section at 47040 Ibs., we take it at 93866 Ibs., the value for unit of length and section will be 104'19, which compares rather more favorably and fairly with iron at 7-660. It is proposed to consider the various properties of cast iron, wrought iron, steel, and bronze, and the effects of the various pro- cesses by which they are made into cannon, with reference to the conditions of greatest effect. 308 ORDNANCE. The relations of elasticity and ductility to the endurance of strain have already been considered. Since the ultimate tenacity of metals approximately indicates their safe working strain, the^ir tensile strength will be compared in some detail. SECTION II. CAST IKON. 354. WEAKNESS A SERIOUS OBJECTION. The chief argument against cast iron as a material for an entire gun made without regu- lated initial tension, is its comparative weakness. The first resort for strengthening a gun thus fabricated from a weak material, is to make it thicker. But it has been shown that mere increase of thickness, beyond a point nearly or quite attained in practice, does not practically strengthen a gun. No possible thickness will ena- ble a cylinder to permanently bear an internal pressure greater per square inch than the tensile strength of a square inch of the material (282). Mr. Longridge says,* with reference to this law, assuming the pressure of powder to be more than 8 tons per square inch (he assumes 17 tons), and the strength of iron to be 8 tons : " It does seem strange that the use of this material should be persisted in, and that experiment after experiment should be made in search of that which is as impossible to be found as the philosopher's stone, viz., a means to make cast iron alone endure more than its ultimate strength." The diagram (Fig. 161) shows the advantage of using strong metal, and making guns (if homogeneous) and rings for hooping guns of moderate thickness, rather than to use weak metal, and attempt to compensate by quantity for its defect in quality. The inner circle represents the calibre of a gun ; the outer arcs represent tubes for two, three, and four calibres in diameter. The full tensile strength of the metal being represented by the square A, its strength in a cylinder is represented by the areas B, C, D : and the weight of guns of one, two, and three calibres in diam- eter, is represented by the numbers 3, 8, and 15 : and the addi- * "Construction of Artillery," Inst. C. E., 186(1 CAST IRON. 309 tional weight to give the additional strength corresponding to the area C, is represented by the middle part of a ring 5 ; and the additional weight to give the slight additional strength represented by the area D is represented by the outer part of a ring 7. The only other resort, then, if the principles of construction are not radically changed, is to add what strength can be got out of a bet- ter process of founding. 3o*>. COMPARATIVE STRENGTH. An American cast iron, having a ten- sile strength of 49496 Ibs. per square inch, has been quite recently applied to cannon-founding/- Assuming a sufficient supply of such iron of uniform quality, and that its contraction when cooling and its elastic limit are favorable for cannon-making, it is still a weak material when compared with steel at 100000 to 150000 Ibs. twice to three times as much. But cast iron does not average 50000 nor even 40000 Ibs. tensile strength. The average of five samples of the highest quality, mentioned by Captain Rodman,f is 31000 Ibs. The system of inspection of gun-iron since 1841, is also stated to have resulted in an improve- ment of the quality of gun-iron used, from 23638 Ibs. to 37774 Ibs.J The highest tensile strength of the various gun-iron tested during a series of years, is stated by Major Wade to be 45970 Ibs., and the average of the highest and the lowest is 27485 Ibs. 356. Mr. Longridge gives the strength of English gun-iron at less than 20000 Ibs., and states that in the Blue Book of 1858, * From the notes of Colonel Delafleld (in charge of the defences of New York), it appears that this iron was taken from a G-pounder of 1000 Ibs. weight, cast by Mr. J. Johnson, Malleable Iron "Works, Spuyten Duyvel, N. Y. The tensile strength varied from 30420 to 49496 Ibs., as follows: 39364, 37340, 33590, 42660, 45575, 42660, 30420, 48672, 45044, 45044, 45044, 42336, 39040, 49496, 35520. 40090, 45632, 46078, 42748. The average of 19 specimens was 41913 Ibs. f "Experiments on Metals for Cannon, etc.," 1861, pp. 137-138. \ "Reports of Experiments on Metals for Cannon," 1856. "Construction of Artillery," Inst. Civil Engineers, 1860. 310 ORDNANCE. containing the Woolwich experiments : " The maximum strength of cast iron there tried was 15 tons (33600 Ibs.), the minimum strength 4J tons (10080 Ibs.), and the average strength 10 tons (22400 Ibs.) Those experiments were made upon irons prepared and sent specially by the makers, and doubtless considered by them as the best for the purpose. The result of Mr. Hodgkin- son's experiments, recorded in his edition of ' Tredgold,' showed an average tensile strength of 7 to T-J- tons (15680 to 16800 Ibs.) per square inch; Low Moor iron being 6J tons (14560 Ibs.), and Carron iron 6 to 7 tons. From the report of the ' Commission- ers on the use of Iron in Railway Structures' (1849), it appeared that the tensile strength of Bowling iron was 6 to 6f tons (13440 to 15120 Ibs.), and that of Low-Moor, 7 tons (15680 Ibs.) per square inch." Mr. John Anderson (superintendent of the Hoyal Gun Factory at Woolwich) states,* that " from several hundred experiments made with the higher qualities of cast iron, which were collected with a view to obtain the strongest iron for cast-iron guns, the ultimate tenacity was found to range from 10886 Ibs. up to 31480 Ibs., or an average of 211 73 Ibs. per square inch. This is consid- erably above the strength of the greater proportion of the cast iron of commerce. The average of the Nova Scotia iron, speci- mens of which have recently been tested, gave only 15821 Ibs., and some of the Scotch pig-iron, selected at random, only gave 12912 Ibs." In the discussion on Artillery, before the Institution of Civil Engineers, before referred to, Mr. Bramwell said " he had a sam- ple (of cast iron) which was broken at the testing machine at Woolwich, that bore 19 tons (43680 Ibs.) to the square inch of section before it gave way." Mr. Longridge replied that, " on in- quiry, he found that in that instance Acadian charcoal iron was used. But in the same page of the pamphlet from which this high result was quoted, there were instances in which the tensile strength of the same iron was not quite 8 tons." * Journal Royal United Service Inst., August, 1862. CAST IRON. 311 357. The construction from unstrengthened cast iron, of rifled guns, which require much greater strength than smooth-bores, has been generally abandoned on account of the weakness of the material. Mr. Wiard states* that work on a number of Y^ inch cast-iron rifled guns (Fig. 83) was stopped because " various trials, at the West Point Foundry and elsewhere, demonstrated these guns to be entirely unreliable." He also states that the 80-pound- ers were equally unsuccessful, and that the liability of the 50- pounders to failure has induced the Department to withdraw them pretty generally from service. The shape of these guns was cer- tainly good, but the material was not trustworthy. English ex- periments on the rifling of old and new cast-iron guns will be detailed under the head of Rifling and Projectiles.f 308. GREATER SHRINKAGE OF STRONG IRONS. It is farther * "Great Guns," 1863. f Colonel Eardley Wilmot, in the discussion on the Construction of Artillery, before the Institution of Civil Engineers, in 1860, gave the following facts abeut the endu- rance of certain cast-iron guns: "At the present moment experiments were being made in Woolwich Arsenal, with a gun which had stood the following discharges: 10 rounds with a cylinder weighing 68 Ibs. ; 10 rounds with a cylinder weighing twice 68 Ibs. ; 10 rounds with a cylinder weighing three times 68 Ibs.; and so on to four times, five times, six times, and seven times, so that the weight of the cylinder with the last 10 rounds was 476 Ibs., the charge of powder being in all cases 16 Ibs.; yet the gun was uninjured. Five rounds had since been fired, with the same charge of powder, and a cylinder weighing 544 Ibs., which had the effect of destroying the carriage of the gun. This was repaired, and another round was fired of the same proportions of charge and weight of cylinder, when the gun burst. " He had been furnished with the results of experiments made with a Spanish cast metal 32-pounder, 8 feet 9 inches long, and weighing 45 cwt. That gun was fired, first with 21 Ibs. of powder, 2 shots, and 2 wads; then with 9 Ibs. of powder, 2 shots, and 3 wads, at an elevation of 10 degrees. He need hardly say, that as the elevation was increased, the strain upon the gun became greater. It was then fired 827 times without injury, with 9 Ibs. of powder, 2 shots, and 3 wads ; next with 9 Ibs. of powder, 3 shots, and 2 wads; then with 9 Ibs. of powder, 4 shots, and 2 wads; continuing with the same charge of powder, and the same number of wads, up to 11 and 12 shots, when the gun was full to the muzzle. Subsequently, it was tried with 12 Ibs. of pow- der and 10 shots; 15 Ibs. of powder and 9 shots; 18 Ibs. of powder and 8 shots; 21 Ibs. of powder and 7 shots; 24 Ibs. of powder and 6 shots; 27 Ibs. of powder and 5 shots, when the gun was again filled to the muzzle, and then it burst. It thus took to burst that gun an aggregate of 3 tons 13 cwt. of powder, 25 tons 8 cwt. of shot, and 2 tons 19 cwt. of wads. 312 ORDNANCE. proved that the strongest iron does not always make the most en- during gun. Several examples mentioned by Captain Rodman* illustrate the general experience in this direction. " The very low endurance of the first pair (8-inch) of experi- "An American shell-gun, 9 feet long, 9 inches diameter, and weighing had been fired with the results given in Table 55. TABLE LV. cwt., Number of Charge of Number of Shot! Weight of Shot Rounds. Powder. and Shell. and Shell. 2 Lbs. 15 1 Phot 90 1500 10 1 shell 72 5 15 1 shot 90 5 15 2 shot 180 2 15 8 shot 270 3 15 4 shell 288 1 20 j 3 shot ) 1 1 shell f 842 1 20 j 2 shot 1 1 4 shell f 468 1 20 j 2 shot | J 6 shell j 612 1 20 7 shot 630 1 20 S shot 720 1 20 9 shot 810 1 20 10 shot 900 When the gun burst. " He might also mention that a British 32-pounder was known to have fired, at the siege of Sevastopol, three thousand rounds ; and though the vent was much enlarged, the bore was perfectly smooth, sound, and serviceable. " It is stated, on the authority of Sir Richard Dacres, who commanded the artillery in the Crimea, that some 68-pounders, lent to the French, endured two thousand rounds. " Colonel Wilford states that some of the siege-mortars, fired with 20 Ibs. of powder, have stood two thousand rounds. Jour. Royal U. Service Inst., June, 1862. "In the Great Exhibition of 1851 were several cast-iron guns, produced at the Liege Foundry, Belgium, which were certified to have withstood the following num- ber of rounds respectively : Size. Weight Ibs. Rounds. 80-pounder 6055 2000 24-pounder, short 1985 3649 6-pounder 1954 6002 6-inch howitzer 1147 2118 ''Several of the siege-guns 24-pounders used at St. Sebastian in 1813, are stated to have been fired six thousand rounds." MALLET. "On the Construction of Artillery,' 1 1856. * "Experiments on Metals for Cannon, etc.." 1861, pp. 137-138. CAST IRON. 313 mental guns which were cast in that year (1849), was attributed to the inferior quality of the iron of which they were made. Two years were spent in searching after a better quality of iron, which was undoubtedly found ; and in 1851 another pair of 8-inch guns were cast. The iron in this pair of guns had a tenacity of near 38000 Ibs. ; while that of the iron in the first pair was only between 27000 arid 28000 Ibs. The solid-cast gun of the first pair burst at the 85th fire, and that of the second pair at the 73d fire ; the superior iron giving the inferior solid-cast gun. These results, however, did not destroy the confidence in strong iron for solid- cast guns, and the first pair of 10-inch guns were made from the same lot of iron; and with a tenacity of 37000 Ibs., the solid-cast gun burst at the 20th fire. This result weakened confidence in very strong iron, and the tenacity was reduced. "In 1857, after guns of good tenacity had failed at the Fort Pitt, South Boston, and West Point foundries, four out of seven guns offered for inspection at the last-named foundry having burst in proof, Mr. Parrott, proprietor of the West Point Foundry, one of our most experienced gun-founders, cast his trial contract guns of iron having a tenacity of 30000 to 32000 Ibs. One of these guns has endured 1000 service charges of 14 Ibs. powder (800 rounds with shell, and 200 with shot)." An 8-inch gun cast in 1844, of iron giving a tensile strength of 26376 Ibs., stood 671 fires, while two guns of the same pattern, cast in 1851, from iron of 37814 Ibs., gave a mean endurance of 46 fires.* 359. This inferiority of the strongest iron for guns is attribu- ted to its greater contraction in cooling, the effect of which will be further considered. Of the last guns mentioned, the best is stated to have been made of low, soft, gray iron, of moderate tena- city and small shrinkage. The poorest was made of high, hard, close-grained strong iron, having the greater contraction of *10 to 15 inch more in the diameter of a gun than lower irons. It was all melted and run into pigs once, and a part of it remelted before * "Reports of Experiments on Metals for Cannon," 1856, p. 198. 314 ORDNANCE. being melted for casting the guns. The reduction of the carbon by this process appears to account for its greater shrinkage, as well as its greater strength. 360. Cast iron has perhaps reached its maximum strength. At least, as cast iron, without the aid of other ingredients or pro- cesses, it has only been improved by the discovery of better ores and better mixtures. Indeed, one authority* states that " the quality of our pig-iron has deteriorated within the last half cen- tury. In an English gun, imported into America in 1845, the cast iron was of a density of 7*04, and tensile strength 18145 Ibs. to the square inch ; while other English guns, imported about thirty years previously, contained metal of a density of 7 '202, and tensile strength corresponding to 28067 Ibs. to the square inch." But the strength of steel and the size of the masses produced are increased every year. 361. WANT OF UNIFORMITY. Cast iron is not uniform. Cap- tain Rodman says:f "We do not knmo, for example, what quali- ties of iron are necessary to make the best gun ; nor, if we did, do we know how, from any of its ores, constantly to produce iron which shall possess those qualities ?" From the fact that high, strong iron makes a weaker gun than lower iron, there w r ould ap- pear to be some uniformity, at least, in the variation of iron. But other facts mentioned by Captain Rodman warrant the conclusion that " we are at present far from possessing a practical knowledge of the properties of cast iron in its application to gun-founding." A gun made by Captain Parrott having failed at the 169th fire, the iron, having a tenacity of 30000 to 32000 Ibs., was condemned by him as too high having too much contraction for heavy guns. From this rejected iron two 10-inch guns were made, " which have been fired 2452 rounds each, the least charges being 14 Ibs. of powder and one solid shot ; and neither gun broke. These guns have since been fired 1000 rounds each, with 18 Ibs. powder and solid shot, and neither gun yet broken." The same iron is generally supposed to be uniform in contrac- * "The Useful Metals," p. 213. f " Reports of Experiments on Metals for Cannon, etc.," 1861. CAST IRON. 315 tion. A striking instance to the contrary is the attempt at Wool- wich to shrink a gun over a wrought-iron tube (Fig. 153). Two guns were broken in the process, and the metal of the third shrunk so unequally, that the endurance was limited compared with that of a tube put without initial strain into a cast-iron gun (Table XIII. and 332). In five specimens of the best American iron mentioned above, there was a maximum variation of 11000 Ibs. per square inch a variation equal to the total strength of other qualities. The difference in the strength of the highest and lowest American gun- iron, tested during a series of years, is stated at 36970 Ibs.* The difference in the strength of the lowest English iron mentioned by Mr. Anderson, and the highest American reported by Colonel Delafield, is 40000 Ibs. per square inch a number given by Haswell for the highest cast iron of commerce. 362. This want of uniformity must always be risked, because it cannot be remedied. Long experiment indeed enables founders to mix ores with some degree of certainty as to the intended pro- duct, but no two charges in the smelting furnace, nor pigs broken for remeltiiig, are substantially alike. But steel and the more refined metals are, and obviously should be, more uniform. Cast iron is made from materials the number and proportion of which we do not know. Steel is made from materials the number and proportion of which are much more definitely known beforehand. This was unintentionally admitted by Mr. Abel, chemist to the British War Department, in the following statement :f " The chemical examination of a large number of samples of cast iron, from different sources, either as obtained from the blast furnace, or after repeated remeltings, had led him to the conclusion that the uniformity of this material was to a great extent under con- trol. He had examined specimens obtained from some of the best iron-works, and on comparing with them samples made, at inter- vals of two or three years, at the same works, he found them, from * "Reports of Experiments on Metals for Cannon," 1856, p. 274. f "Construction of Artillery," Inst. Civil Engineers, 1860. 316 ORDNANCE. a chemical point of view, almost identical in their nature. There might be a variation in the density, and other physical properties, resulting from the temperature at which the metal was cast, and from other circumstances, but the regulation of such differences was under the control of founders and engineers. If, therefore, it was found that cast iron might, with proper attention to its manu- facture, be made almost perfectly uniform, some faith ought to be placed in that material. At the same time, the important results obtained by the further treatment of cast iron should not be lost sight of. By progressive decarbonization, it might be made to approach to perfect steel in its nature, or to acquire the character- istics of malleable iron. Such conversions could, a few years ago, only be carried out upon a small scale, or by most laborious pro- cess ; now they could be effected upon a very large scale, so that masses of the products, of great size, could be produced. Amongst others, Mr. Bessemer had obtained results which should not be passed over. He thought they might prove most important, par- ticularly when it was remembered what had already been done in this direction by Mr. Krupp, in Prussia." That is to say, there may be a variation in density and other physical properties of cast iron, but it promises great results when improvements amounting to a new manufacture are introduced, especially a new manufacture of steel. To this Mr. Longridge replied : " Many striking instances might be given to show, that identity of chemical composition might coexist with great variation of physical properties. For example, phosphorus was a deadly poison, and ignited with the least friction in its ordinary state ; yet in another state, without any change chemically, it might be swallowed without causing any injury, and did not ignite by friction. He believed there were certain compounds, such as one of chlorine and naphthaline, which existed in the gaseous, the liquid, and the solid form, and yet no chemical difference could be detected. Therefore he did not think that chemical identity had much to do with the mechanical properties of iron. He was supported in that opinion by the Report of a Committee of Chemists appointed in the United CAST IRON. 317 States, in 1849, to investigate this question. In 1851 their first report was made, which was of a hopeful character. In 1852, it was reported that a decided relation, it was believed, had been observed between the amount of uncombined carbon and the tensile strength of the metal. But in the final report, in 1855, all the former reports were withdrawn, and it was stated, that ' though at first largely appreciating the extent of our labors, the completion of them sensibly diminished that estimate of their usefulness.' Therefore, he thought, however desirable it might be to ascertain the chemical qualities of iron, practical men were yet very far from being in a Dosition to accept them as indices of its tensile strength." Mr. Bidder, President of the Institution, said in the same dis- cussion : " Cast-iron guns had no doubt occasionally exhibited wonderful results. They had withstood an immense amount of firing and strain ; but there was not any certainty of uniform results being obtained. In one case a cast-iron gun had sustained 1500 or 2000 rounds, whilst another gun, stated to have been cast from the same metal and under precisely the same conditions, had not resisted for a single day." Mr. John Anderson, in a paper on materials for cannon,* says : " There are many instances on record of cast iron having shown an amazing amount of strength, toughness, and general endurance, both as guns and in other constructions ; still, at the best, it is un- certain, and, as will be seen hereafter, it is not strong, and is pro- verbially treacherous to depend upon, as it gives no warning before rupture ; and hence the time has arrived when, for ordnance espe- cially, it seems about to give place to a better material, either wrought iron or steel, or perhaps a combination of both." 363. It is indeed stated, that the endurance of cast-iron guns can be pretty certainly predicted upon an examination of the mi- nute cracks and other appearances in the bore after a certain num- ber of rounds ; and that, in a general way, experience has settled the number of fires that a gun will stand. Without questioning * Journal Royal United Service Inst., August, 1862. 318 ORDNANCE. these statements, it is only necessary to consider that this informa- tion has not been, perhaps because it could not be, so far utilized as to prevent very serious losses of life, treasure, and discipline, from the bursting of cast-iron guns. And what is worse, it has failed to remove that constant looking for of disaster which pro- hibits high charges, high velocities, and the sharp and decisive war- fare which a more trustworthy gun-metal of no greater strength would render safe and practicable. Cast and wrought iron will be further compared in this respect. 364. DEFECTS IN FOUNDING. The actual strength of the inte- rior of a thick casting is far less than that of the same iron in a small bar. The outside cools and contracts first, squeezing some part of the liquid or pasty iron within up into the riser-head. Taking the case of a solid cylinder : when the outside is firmly set, the inside begins to cool, and in contracting tends to do three things : 1st. It tends to pull the outside into a smaller diameter, but with only the weaker or tensile force reduced by heat, while the out- side opposes the stronger or compressive resistance, in the best form to maintain it the arch.* The outside is then a little com- pressed. 2d. The contracting interior tend? to break loose from the exterior ; but as the metal is cooler and the section greater towards the periphery than at the centre, the iron is but little strained in this direction. 3d. As the inside meets with these two resistances in trying to get into a cylinder of less diameter, its last tendency is to separate in radial cracks. In every large casting this result would actually occur ; otherwise the inside would be left in high tension. " The extent of contraction in a 10-inch gun, cooled as above supposed, with a maximum difference of tempera- ture (2700), would be about two inches in length and a half an inch in diameter, and -f of the latter would be in a direction from the centre towards the exterior, tending to split open the gun. The * The American solid cast guns ;ire slightly oval in section, so that the effects of an unyielding arch are modified. The Dahlgren guns are also cast much larger than the finished size, so that the metal can adjust itself to the strains, in some degree, when it is turned. Several of the 11-in. solid-cast guns have endured 1500 to 2000 rounds. CAST IRON. 319 above supposes an extreme case, in which a maximum difference of temperature between the exterior and interior occurs, a condi- tion which never exists in practice. But it serves, however, to explain the law which governs the contraction of iron."* In any case, the interior is not compact and dense. 165. If, as some authorities state, the contraction of cast iron is greater when cooled rapidly than when cooled slowly, the greater contraction of the outer part of the gun would to that ex- tent relieve the difficulty specified ; but if the reverse is true and upon this theory Captain Rodman proposes to put the exterior of a gun cooled from the inside into tension the strains described above would be aggravated. 364>. The sources of failure, then, are as follows: when the gun is cool, a considerable part of the tensile strength of the inside is already employed in preventing the inside from contracting, thus leaving only >the residue to resist the powder, while the out- side, being in compression, can at first oppose no resistance at all to the powder ; on the contrary, its first tendency is to help the powder open the gun. But this does not fully state the case. The outer layer of any tube is but slightly stretched by elastic in- ternal pressure, while the inner layer is greatly stretched the amount being inversely as the squares of their diameters. Hence, if the outer layer is initially compressed, it may be so slightly elongated by the powder as never to come into tension until the inside is actually burst. 367. The tendency of the core of the gun to contract away from the outer portion, is compared by Mr. Conybearef to build- ing up a gun of a number of concentric wrought-iron rings, by heating the second ring and placing it within the exterior ring already shrunk ; and, when the ring had cooled, repeating the operation with a third red-hot ring. Such a gun would be en- tirely destitute of coherence and strength ; yet this " was precisely the mode of proceeding adopted in the construction of cast-iron ordnance cast solid and cooled from the exterior." / * Major Wade. "Reports of Experiments on Metals for Cannon," 1856. f Discussion on the "Construction of Artillery," Inst. Civil Engineers, 1860. 320 ORDNANCE. 368. The existence of strains from unequal cooling is proved by the superior endurance of guns that have been kept a long time after casting, thus giving the metal time to recover a condi- tion of repose. Mr. BramwelP thus refers to the American ex- periments: "A gun which had been so kept for six years, endured eight hundred discharges before it burst ; while another gun en- dured two thousand five hundred and eighty-two discharges, and did not burst. Guns of the same description, tried thirty days after casting, burst, one at the eighty-fourth, and the other at the seventy-second discharge. This result showed it was not impossi- ble that the superior manner in which guns cast some years ago, but recently used, had stood their work, as compared with those of modern make, was not due, as was commonly supposed, to the better quality of metal in those days, as compared with the pres- ent, but to their having been cast a long time ; and to the strains that existed in them, from unequal contraction, when originally cast, having ceased, while the strains in the new castings were still exerting a prejudicial effect. It was proved, in the case of the two guns to which he had alluded, that the gun which burst after eight hundred discharges had a tensile strength of 23000 Ibs., and that which endured upwards of two thousand five hun- dred discharges without bursting, had a tensile strength of 29000 Ibs. to the square inch. Of the guns which were tested thirty days after being cast, the one had a tensile strength of 27000 Ibs., and the other a tensile strength of 37000 Ibs. per square inch of section. Both these recently cast guns endured a less number of rounds than those which had been cast some years, although the metal of these latter was much weaker than that of the former." 369. The expansion of the inner layer of metal by the heat of firing is, in the case of guns cast solid, a direct and unqualified advantage. If carried far enough, it not only relieves the tension of the interior and the compression of the exterior, but reverses these strains, placing the various layers in the condition to be equally strained at the instant of the maximum elastic pressure. But this advantage can never be depended upon in practice. A * "Construction of Artillery," Inst. C. E., 1860. CAST IRON. 321 gun may never attain the exact state of strain required ; and if it does, it instantly goes beyond it. 370. The next source of weakness due to casting guns solid is, the reduction of the tensile strength of the material. A bar of cast iron 1 inch square was cut out of a bar 3 inches square, and tested wdth a bar originally cast 1 inch square. The reduction in the resistance of the former bar to crushing was 43 per cent., and to transverse strain, 42 per cent.* Mr. Longridge is of the opinionf that " in a mass of metal such as was required in a 68-pounder gun, the loss of strength would be at least 50 per cent." In a solid gun mentioned by Captain Rodman, a sample cut out near the trunnion showed a tensile strength of 44000 Ibs. for the out- side and 31000 Ibs. for the inside. So that a gun unequally cooled not only offers the resistance of but a part of its strength to the strain of the powder, but has less total strength than a gun uni- formly cooled. These facts are fully competent to account for the weakness of solid cast-iron guns. 371. The want of density in the metal of guns thus cast is the source of another species of failure. Mr. Mallet thus describes its condition :^ " In a casting of 2 or 3 feet or more in diameter, it is not unusual (with a founder's best care) to find a central por- tion of from 6 to 8 inches in diameter, consisting of a spongy mass of scarcely coherent crystals of cast iron, usually in arborescent masses, made up of octohedral crystals ; the whole so loose, that upon a newly cut section dark cavities can be seen by the naked eye in all directions, out of which, often, single or grouped crys- tals can be picked with the hand, and so soft that a sharp pointed chisel of steel may be easily driven into the mass some inches, as if into lead or soft stone." The poorest part of this core is bored out in the chase, but the chamber, where the greatest strain comes, is the worst part of the casting. Hardness and density of bore are necessary to prevent enlargement both from concussion and friction, especially in the case of rifled guns. Commander * "Report of Commission on Railway Structures," 1849. f "Construction of Artillery," 1860. \ "On the Physical Conditions involved in the Construction of Artillery," 1856. 21 322 ORDNANCE. Scott states,* that " from being cast solid, guns were made with a degree of hardness which was injurious to tenacity, in order that the centre of the gun might not be worn away by the rubbing of the shot." He instances certain guns cast at Woolwich. 373. EFFECT OF AGE ON ENDURANCE. The metal of a gun, thus placed by unequal cooling in an unnatural condition, tends to assume a natural position of repose. Three 8-inch columbiads of the same form and dimensions, and cast in the same way, from the same iron, were tried as follows : One fired immediately after casting, failed at the 72d round ; after 6 years, the others were fired ; one of them stood 800 rounds, and the other 2582 (368). 373. IMPROVEMENT IN FOUNDING.-)- CAPTAIN RODMAN'S PRO- CESS. The principal improvement in the fabrication of cast-iron guns, is Captain Rodman's process of cooling them as far as possi- ble from the interior, and, for this purpose, casting them hollow. The fabrication and test of these guns have been described in a preceding chapter (154). The design is to remedy the various defects of the old process ; principally to obviate the tendency of solid castings to be burst by their own initial strains, by reversing the process of cooling and shrinking described above. Since there would then be no force opposed to the contraction of the inner layers of metal, except the trifling cohesion of the liquid or pasty mass that they shrunk away from, 1st, they would not be left in tension, and therefore, 2d, they could not exert any power to pull the exterior layers into compression. 374. But it is not proposed to leave the metal in a condition * "Construction of Artillery," Inst. Civil Engineers, 1860. f The Dahlgren guns, up to 11-in. calibre, some of which have endured above 2000 rounds, were cast solid, but considerably larger in diameter than the finished size. The heavy Navy guns are now cast hollow. All the rifles are cast without trunnions. In a discussion on guns, before the Franklin Institute (1862), Chief-Engineer Wood said that "Captain Dahlgren's method to obviate the evil (of strain due to unequal shrinkage) consisted in casting the gun more nearly in the form of a cylinder, then turning off the additional metal on the exterior which had caused the strain in unequal shrinkage, by having been first cooled in the mould. His guns were cast solid; then the interior part, supposed to be the weakest, is bored out." Scientific American, Nov. 15, 1862. CAST IRON. 323 of repose. The attempt is to remedy by the same process the defective strength of a hollow cylinder, already considered, viz., that the inside is more stretched than the outside by internal pres- sure. Captain Rodman quotes this law from Professor Barlow, and says, as to the greater endurance of his hollow-cast gun :* " The object of my improvement was in part, if not fully attained, viz., to throw the gun upon a strain, such that under the action of the law of strain, as stated above, each one of the infinitely thin cylinders composing the thickness of the gun, shall be brought to the breaking strain at the same instant" 975. The process of cooling would then have to occur as fol- lows : Taking any two of the infinitely thin cylinders referred to, the exterior of the inner one having set at a diameter of say 2 feet, the interior of the outer one would have to contract to a diameter somewhat less than two feet. In other words, a given length of metal would have to contract more in one cylinder than in the other, by the abstraction of a given amount of heat. Now if all parts of the iron were alike in their composition and struc- ture, the cooling of all parts in a given time would of course leave the whole mass in repose. But certain experiments are said to show that " the contraction of the same iron is greater or less, ac- cording to the greater or less rapidity with which it is cooled. That which cools most rapidly contracts most."f If this is true, when a gun is cooled from within, the inside is not only cooled first, but most rapidly, since the heat has a shorter distance to travel. Hence the outside contracts less than the inside, and the outer infinitely thin cylinder, in the case we have supposed, instead of shrinking to a diameter less than 2 feet, so as to compress the one within it, would tend to stretch it into a state of tension, and, in stretching it, to be itself compressed ; and so on throughout the mass, which is just the opposite state of strain to that required. These results would be very minute, but Mr. Longridge has demonstrated that a deviation from the proper tension of T fa inch * "Reports of Experiments on Metals for Cannon," 1856, p. 212. f Ibid., p. 195. 324 ORDNANCE. in a diameter of 17 inches, reduces the strength of a cylinder 40 per cent. 376. Other experiments indicate that a large mass of metal cooling last, will contract upon a smaller mass which, being thin- ner, cools first. Mr. Wiard cast a heavy ring with a thin bar ex- tending across its diameter. The ring contracted upon the bar so tightly that it could not easily be broken out. When broken out, the bar was considerably longer than the space it had filled. The results are at least so irregular, that it would be almost im- possible to produce theoretically exact strains by this method. 377. Another source of error arises from the partial cooling of the outside of the casting, while the intermediate portions are still liquid. Major Wade's report on this subject states that* "the fracture of the 10-inch gun, cast hollow, developed cavities or fis- sures in the face of the fractured surface, near the front of the chase. The fissures are irregular, presenting in some parts an open chasm, half an inch wide and 4 or 5 inches in length and depth ; in other parts the metal has a sponge-like appearance ; they are from 10 to 14 inches below the neck or narrowest part of the casting,f where the iron, in cooling, soonest becomes solid entirely through a cross-section of the gun. The position of the fissures marks the place where the iron remained longest liquid, in this section of the casting ; for it is evident that they were formed by the liquid iron in this part descending, to supply the vacancies made by the shrinkage beneath. The mass of the metal below being greater, a portion of it continued liquid a longer period of time, and until after a cross-section at the neck had become solid ; and this solid intercepting the descent of liquid metal from the sinking-head above, the shrinkage below could be replaced from no other part than that where the fissures are found, viz., directly beneath the cross-section at the neck, where the metal first becomes solid throughout." " The area of that part of the cross-section which is outside of * "Reports of Experiments on Metals for Cannon," 1856, p. 198. f The gun was of the old pattern ; the place referred to is in the rear of the long muzzle-swell. CAST IRON. 325 the fissure, is T 7 ^ of the area of the whole section ; and the part within the fissures is fV of the whole. This indicates that T 7 o of the heat contained in the liquid metal escaped by passing out- ward, through the exterior surface, to the mould, by which it was conducted off; the remaining T 3 F of the heat passed inward to the core, and was carried off by the water." 378. The strains would then be as follows: The intermediate rnetal, still hot, after the exterior and interior had set, and after the surrounding parts had become so pasty that it could receive no supply of metal from the sinking-head, or elsewhere, would still continue to contract, thus pulling the parts within it into tension, and the parts outside of it into compression, and itself into ex- treme tension, or, in large castings, pulling itself apart. These strains in all parts of the 16-J-in. walls of a 15-in. gun, would be about equal to the strains in a solid-cast gun 16^ in. in external diameter, or about the size of the rifled siege-gun, Fig. 80, al- though very much less than in a solid-cast gun of equal size. 379. Some of the strains, then, in a hollow-cast gun, are in the opposite direction to that required by Professor Barlow's formula. And supposing that the layers of a gun will be drawn tightly over each other, proceeding outward from the centre, if the heat is ab- stracted exclusively from within, the absolute condition of such a result is, that the mould shall be kept at the temperature of molten iron (2700) until the extreme outer layer of the gun begins to fall below that point by the abstraction of heat from within. When this occurs, the temperature of the mould must be made to fall with the same rapidity ; for if it falls faster, the gun will begin to cool from the outside, and if it falls slower, the stress on the different layers of the gun will become irregular. Surrounding the mould with a mass of molten iron thicker than the walls of the gun, so as to be always hotter than the gun, would obviously prevent cooling from without. The unequal contrac- tion of the same mass of iron, by reason of its chemical differ- ences, would in any case disturb the desired uniformity of strain. 380. So that, while the defect of rupturing strains in solid cast- ings may be entirely avoided by means of a mould that can be 326 ORDNANCE. heated to 2700 before the iron is poured, it appears impracticable to put the outer layers of metal into tension regulated with theo- retical nicety, by Captain Rodman's process. Even if this tension was attained, the gun would lose much of it in time, for it is well known that castings lose their other initial strains by age (368,- 372). The results certainly show a vast improvement over solid- cast guns, but neither the endurance of the hollow-cast guns, nor the charges they are allowed to carry, warrant the belief that the iron in them can be "brought to the breaking strain at the same instant." In fact, the above extract from Major Wade's report, shows that j\ of the hollow casting, being cooled from without, was in the opposite condition of strain. 381. The expansion of the interior of the gun by the heat of firing, would of course disturb the initial strains, but no more than in the case of the hooped gun. If the tension of the exterior was insufficient, the first few rounds would increase it, and strengthen either gun. The intermediate spongy place in the wall of a gun cast hollow and cooled from both surfaces, would allow the inner layers of metal to expand more without straining the outer layer, than if the metal were solid throughout. But the longitudinal strain of expansion by the heat of firing, produces no compensa- ting results. This strain is in a great degree avoided by strong steel guns, because the walls may be thin ; and by hooped guns, because the inner tube may slide within the hoops ; but the thick cast-iron wall must endure its greatest force. Even if hooped with steel, cast iron must be quite thick to have the necessary longitu- dinal strength. (304.) 383. The other defects of solid-cast guns, are partially or en- tirely remedied by Captain Rodman's process. The surface of the bore is the hardest and densest part of the casting, and best calcu- lated to resist pressure and abrasion. The tensile strength of the metal that receives the first shock of the exploding powder, is uninjured, because it is not drawn like the interior of a solid-cast gun. The intermediate metal is stronger or weaker, as the cool- ing is more or less carried on from the interior. 383. MR. WIARD'S PLAN. Mr. Norman Wiard, whose ingeni- CAST IRON. 327 FIG. 162. ous and important speculations on the bursting of guns by the heat of the firing have been re- ferred to in the foregoing chap- ter, has received a large order for heavy cannon, based upon the en- durance of either one of two test- guns. The engravings illustrate the general features of his plan, but not the exact proportions; these are the subject of extended experiments and calculations not yet perfected. The gun is to have the same diameter and length of bore as the Navy l5-in.'gun, and about 9 in. greater external diameter, and is to weigh 43000 Ibs. The interior parts may be cooled uniformly by water passing through the cores between the ribs and in the bore, upon Captain Rodman's plan. The exterior part or reinforce, being thicker than the other parts, will cool last after casting, and is by this means intended to com- press the barrel with such force as to bring all parts of the metal into equal strain at the instant of firing, according to Professor Barlow's formula. The ribs are curved in both directions, from front to rear, and from the inner barrel to the outer hoop or reinforce, so that they can spring enough to allow the inner barrel to expand both longitudinally, and the intention is, radially, by the heat of firing, without seriously straining the structure. The ribs also yield during the process of "Wiard's cast-iron gun. 328 ORDNANCE. FIG. 163. Longitudinal section of Wiard's cast- iron gun. FIG. 164 Cross-section of TViard's cast-iron gun. casting, under unequal contraction due either to unequal cooling or to chemical differences in the metal. They are proposed to be stiff enough to resist the pressure of the powder, and sufficiently flexible to bend under the greater force of expansion a force limited only by the ultimate strength of the metal. The elasticity of the whole structure would be greater than that of guns without ribs. 384. First. This gun will un- doubtedly cool without serious initial rupturing strains. The whole practice in founding, espe- cially in founding car-wheels (which a cross-section of the gun resembles), warrants this conclu- sion. A plain disk wheel, not an- nealed,* can only be stretched or compressed, and so broken or greatly strained, in cooling, and therefore goes to pieces under service. A gun when so corruga- ted as to bend in cooling at some thin part intended to be bent, in- stead of breaking or being severely strained at some part that cannot be bent, endures more hard ser- vice than would be ordinarily ex- pected of cast-iron. * Messrs. A. Whitney & Sons, of Phila- delphia, the most extensive car-wheel man- ufacturers in the world, cast plain disk wheels, which are afterwards annealed for CAST-IRON. 329 385. Second. For the foregoing reasons, the strongest iron may be employed. It has already been shown that a pure, high iron of great tenacity, shrinks too much to make a safe casting by other plans. But car-wheels are cast as sound from the highest and strongest iron as from a weaker iron, because ample provis- ion is made for it to change its figure more or less, as required, without strain. 386. Third. Upon the proper tension and strength of the reinforce as modified by its large diameter, the heat of firing, and the elasticity of the parts within it, depends, after all, the chief strength of the gun. Comparing the reinforce with an equal thickness of metal on the exterior of Captain Rodman's gun, the former is cooled on all sides to prevent, as far as possible, unequal shrinkage, and is curved in two directions to prevent unequal and injurious strain due to what unequal shrinkage there may be. The latter is cooled (in prac- tice) only from the outside, so that its interior surface is strained and weakened. It appears, then, that the former would be in a better condition to stand the tension. In which can the tension be the better regulated ? The official report already quoted (375) is evidence that the outer part of the Rodman gun is drawn into compression by the subsequent shrinkage of the intermediate metal. It cannot be put into the desired tension except by cooling the gun exclusively from within ; and this can only be done by keeping the mould at a temperature of 2700 a process so difficult that it has not been realized in practice. But there is nothing to draw the cor- responding part of the Wiard gun the reinforce into compres- sion. All the parts enclosed by it have already cooled and set. In other words, the part that cools last, regulates the strain of the rest. The interior and the exterior parts of the walls of the Rod- man gun cool independently, and without any great strain. Then the intermediate metal cools, and puts strains into them which are just opposite to those required. But the reinforce of the Wiard some hours under the highest temperature that will not draw the chill of the tread. The strains which would otherwise destroy the wheels are thus removed. 330 ORDNANCE. gun cools last, and, if it shrinks most, must compress the inner tube, and be itself drawn into tension the required condition. 387. As to the strain due to expansion by the heat of firing: Suppose the reinforce and the barrel to be put under such respective initial tension and compression that the force of the powder would strain them equally, and as much as they would safely bear in service ; if the ribs yield under the pressure of the powder, the barrel may be stretched to the breaking point before the reinforce is stretched to the same point. If the ribs do not yield under the pressure of the powder, then they will not yield under an equal pressure from the expansion of the barrel by heat. So that the expansion of the barrel by heat, up to a pressure equal to the pressure of the powder, will act directly to stretch the rein- force which had already been stretched as much as it will bear. Up to this point, the case is similar to that of a solid gun ; beyond a pressure equal to that of the powder, the ribs may yield to the pressure by heat without straining the reinforce as much as it would be strained in a solid gun. But the barrel will not be heated as much as the corresponding part of a solid gun, because it is exposed to the air on both sides, and presents a large radiating surface. Besides, the longitudinal expansion of the barrel is the source of the greatest strain, and this, in the Wiard gun, is provided for by the longitudinal corru- gation of the ribs. 388. The larger diameter of the reinforce is a source of com- parative weakness. 38O. On the whole, it is probable that the barrel and ribs of Mr. "Wiard's gun can be cast without serious strains ; that the reinforce can be shrunk upon them with some degree of tension ; that the strongest iron can be used ; arid that the gun will not be seriously strained by heat. The failure of the first guns, if they should fail, ought to be attributed to the improper carrying out of the princi- ples ; for the present knowledge on the subject of cast-iron, however imperfect it may be, defines these principles with much clearness.* * Since the above was written, Mr. Wiard's first gun having been cast upon cores which it was difficult or impossible to remove, has not been bored or tested. His second gun burst at trial. CAST IRON. 331 39O. SHAPE. With reference to sudden changes in the dimen- sions of a gun, Mr. Mallet's theory is, that the principal axes of the crystals arrange themselves in the direction of the flow of heat outwards, and that whenever re-entering angles or sudden changes of dimensions occur, planes of weakness are thereby produced.* Mr. Longridge is of the opinion f that this explanation depends too much upon what appear to be arbitrary assumptions, to enable him to place much confidence in it. " He has examined carefully many cases of fracture of cast iron, but in no instance has he been able to satisfy himself that the crystals have that definite direction which would justify him in determining thereby a plane ol weak- ness. They have always appeared to be a confused mass of more, or less, defined crystals, but certainly not so arranged that he could ascertain any uniform direction of what Mr. Mallet calls their prin- cipal axes." Mr. Longridge thinks, "that without having recourse to this theory, the law of cooling alone will fully account for the source of weakness in the cases in question. Whenever a varia- tion in thickness occurs, a difference in the rate of cooling must also take place. This alone must give rise to a state of varied stress amongst the particles of the metal, which, without doubt, diminishes its efficiency as a resisting substance. * * * Take, for instance, the accompanying sketch of a gun (Fig. 165) distorted in its proportions for the sake of illustration, and suppose it to have cooled down after casting. Although in the present state of knowledge on the subject, it would be impossible to determine the absolute position of the isothermal lines at any period of cooling, yet it is certain they must approximate to $ie dotted lines shown in the sketch ; and following these lines according to some definite law, would be the lines of equal stress of the particles of the gun when cold. * ' Whenever a change of dimensions occurs, the cooling will give rise to varying strains, which may account for fracture taking place at those particular places." The shaping of guns so that each part shall bear only the * "On the Physical Conditions involved in the Construction of Artillery," 1856. f "Construction of Artillery," Inst. Civil Engineers, I860. 332 ORDNANCE. strain imposed upon it without waste of material, has been well considered by American designers (149). That it adds nothing to FIG. 165. Gun distorted to show the effects of irregular cooling. the cost of a cast gun, h an obvious advantage of cast iron and bronze over wrought iron and steel. 511)1. RESISTANCE TO CONCUSSION AND WEAK. The hardness of cast iron as compared with wrought iron and bronze, enables it to better resist change of shape by pressure and abrasion. The chambers of wrought-iron guns almost invariably enlarge under high charges, and rifled projectiles often cut away their rifling. The Parrott cast-iron 100-pounder has fired 1000 expanding (brass ring) projectiles without injurious enlargement or wear. 392. WEIGHT. The great weight of cast-iron guns for a given strength, is not, in all cases, a serious objection. As far as pre- venting excessive recoil h concerned, the recent improvements in compressors will allow much of the present weight to be dispensed CAST IRON. 333 with. On the other hand, the very light steel guns of Mr. Krupp have been set in heavy cast-iron jackets which add no strength, simply to relieve the recoil. This is chiefly a question of situation and cost. In a fort, a few thousand pounds increased weight at a few thousand dollars reduced cost per gun, would be desirable if the question could be considered independently of strength. On the other hand, an armament of 11-inch guns is said to impair the sea-going qualities of some of our lighter-gunboats and cruisers. Nor can such guns be handled on small vessels, in rough weather. 393. COST. The principal argument in favor of cast iron as a material for guns is its cheapness, compared with wrought iron or steel. To convert and shape the latter, at a great expenditure of fuel and labor, wear of machinery, and loss of material, costs in England, where prices are lowest, from 20 to 40 cents per pound ; the cost of large guns increasing faster than their weight. Melting cast iron, preparing the moulds, and dressing the surfaces already shaped, can be done for from 7 to 13 cents per pound, which is about half the cost of wrought iron for a given calibre (Table 27). But calibre is not always a measure of work. If cast- iroii guns will not stand the necessary powder, they are a waste of money, however cheap. But if a fixed sum to be invested in guns will not purchase enough of the best to defend every availa- ble point, it is undoubtedly better to have a part of them cheap, at the risk of their being weak. But it does not follow that they should all be weak because weak guns are cheap. Cast iron may be utilized, however, without making weak guns. When reinforced with wrought iron or steel, and especially when lined with steel on the plans described, it is both cheap and strong. On the other hand, nothing but the best, at any price, should be placed in the better class of iron-clad ships, since here they not only are in a position to do the best work, but should make up in efficiency what they lack in numbers. 334 ORDNANCE. SECTION III. WROUGHT IRON. SO4. STRENGTH. Cast iron is in such a crude state that the number and proportion of its deteriorating ingredients are irregu- lar, and in practice imperfectly known, while wrought iron, being comparatively refined, is not necessarily so various in quality, and it is very much stronger. " The conversion of cast into wrought iron by the removal of carbon and silicium completely changes the characteristics of the material. It has lost the brittle property ; it now yields and stretches before it breaks ; the permanent yield- ing point is now higher than the former breaking point, and the breaking point is double that of the yielding point."* 3O*5. The average tensile strength of the best qualities of wrought iron, is about 60000 Ibs. per square inch, or about double that of the best qualities of cast gun-iron. The range of good brands, according to Nystrom,f is from 56000 to 650^0 Ibs. ; ac- cording to Haswell,} 60000 to 72000 Ibs. ; according to Temple- ton, 64000 Ibs. for American, and 55872 Ibs. for English. Whil- din|| gives the table (56) of tensile strength : TABLE LVI. TENSILE STRENGTH OF WROUGHT IRON. f Salifbury, Conn 66000 Bellefonte, Pa 58000 Englifh 56000 Pittsfield, Mafs 47000 43000 53000 Maramec, Mo -J Franklin Inftitutc. Maj. Wade. According to Mr. Kirkaldy, the highest mean for English rolled bars is Lowest Highest. Mean. Govan B. Beft, in. round 61864 66553 64795 * Mr. Anderson (Superintendent Royal Gun Factory), Journal Royal United Service Inst., August, 1862. f "Nystrom's Mechanics," 18G2. j " Engineers and Mechanics' Pocket-Book," 1860. "Engineers and Mechanics' Pocket Companion," 1854. J "Experiments on Wrought Iron and Steel," 1862. WROUGHT IRON. The lowest mean for English rolled bars is Lowest. Highest. Yftalyfera puddled, x i in. flat 36979 4977 335 Mean. 38526 TABLE LVII. SUMMARY OF RESULTS OF KIRKALDY'S EXPERIMENTS* FOR BRITISH HAMMERED IRON. Lowest. Highest. Mean. Scrap iron, forged down Bufhelled iron, do do. . . *)iUU^ C7 Cl6 i $<*^ c 1-878 Crank fhaft, fcrap iron, cut out, length. .. 4.64-sO 4.0671 >5/* 4.7 rg 2 do. do. do. do 4. 34.20 4.4. r 6 1 4-77 ?0 4^1C78 do. do. do do TTT$3 72c8i 784.87 Armor plate, do. do. do j&^OJ, 36646 38868 do. do. do. do 74.6l4. 7Q2I 1 76824. Mr. Kirkaldy says: "The breaking strain per square inch of wrought iron is generally stated to be about 25 tons for bars, and 20 tons for plates. This corresponds very nearly with the results of the writer's experiments." According to Mr. D. K. Clark,f the best Yorkshire boiler plates averaged 25 tons (56000 Ibs.) ; the best Staffordshire, 20 tons (44800) ; the best American, 70000 Ibs. ; and ordinary American, 60000 Ibs. Mr. Clark's authority as to the American plates is Mr. Zerah Colburn. Mr. Anderson states^ that the average strength of the coils of the Armstrong gun, in the direction of their circumference, is 55500 Ibs. The specification to the makers of the iron prescribes a tenacity not to exceed 65000, nor to fall below 56000 Ibs. The foregoing figures are intended merely to give a general * "Experiments on Wrought Iron and Steel," 1862. f "Recent Practice" in the Locomotive Engine, 1860. \ "Journal of the Royal United Service Institution," August, 1862. 336 ORDNANCE. view of the tenacity of wrought iron. Its elasticity and ductility under various treatment, and the qualities adapting it to particu- lar uses, are not measured exclusively by tensile strength, and have been referred to. 896. UNIFORMITY. Although there is a wide range of strength between the highest and lowest specimens of wrought iron, it is practically much more uniform than cast iron, that is to say, the iron for a given service can be selected with much more certainty. The armor-plate iron tested by Mr. Kirkaldy indeed averaged but about 37000 Ibs. ; but it has been found that softness and ductility are better indices of fitness for this particular service. The low strength of both the armor-plate and the crank-shaft (45670 Ibs.) were in some measure due to the process of manufacture forging a large mass solid. This, however, is an argument against the process only, if it can be shown that any other process can utilize the full strength of the material. On the other hand, it appears, from Mr. Longridge's statement (356), that the cast iron sent to Woolwich for test each maker undoubtedly supposing his own the best for guns varied in strength all the way from 10080 to 33600 Ibs. The mere fracture of wrought iron (including puddled steel, which is in this particu- lar the same) affords such evidences of its quality, that, by this test, the most uniform products such as Low-Moor tires, and Krupp's and Tickers' steels are compounded. Mr. Anderson says* on this point: Wrought iron "is never high, nor never low; on the contrary, wrought iron from any particular maker, who is careful in the manufacture, is found to be nearly uniform, and, being possessed of great toughness, and being without brittleness, it is exceedingly reliable so far as its strength will permit." This, indeed, is a second advantage of a refined metal over a crude one. At each stage in its progress its character is better understood. Another source of embarrassment in the use of cast iron the unfitness of the finest and strongest varieties for guns (358) * "Journal of the Royal United Service Institution,' August, 1S62. WROUGHT IRON. 337 applies only in a limited degree to wrought iron, and arises from other causes. In fact, the wide range of defects in founding, though riot all serious defects in fabrication, are avoided by the use of wrought iron and steel. 397. What has been said of the average deterioration of cast iron, during the last half-century, appears to be true of wrought iron. Mr. Hughes remarks,* that " writers on the strength of materials in the last century seldom assigned to bar-iron a less tensile strength than 30 tons per square inch as the weight which would tear asunder a bar of ordinary wrought iron 1 inch square. Thus, Emerson gives the tensile strength of bar-iron at 3-i tons; Telford, 29'29; Drewry, 27 tons; while at the present day Tem- pleton gives 25 tons; Beardmore, 26'8; Brown, 25 tons; and Eaton Hodgkinson, probably from more careful experiments than any other, at 23'817. The iron manufacture of this country (Great Britain) has attained an enormous development, which, unfortu- nately, has not been accompanied by a corresponding increase of quality. On the contrary, all the early experimenters on iron found a greater strength than is now possessed even by the best qualities." 398. This deterioration is attributed to various causes, such as " cunning chemical secrets," which enable manufacturers to work up inferior iron, and the "spirit of speculation," which in some measure account for it. But so long as processes smelting, pud- dling, piling, &G. deal with ore and iron as if they were always uniform, irrespective of chemical differences, just as certain sys- tems of medicine deal with human bodies, irrespective of consti- tutional and intellectual diversities, the means and opportunities of general improvement will be wanting, and any relaxation of care and faithfulness will necessarily lead to the deterioration of the product. The selection, compounding, and elimination of materials on account of their chemical relations to the desired result, is the new system of treatment, as yet but approximately developed in the Bessemer process, but destined to lead to much * "The Artisan," February, 1858. 22 338 ORDNANCE. greater uniformity and certainty in the adaptation of iron to its various service. 399. DETECTION OF WEAKNESS. Unmistakable evidence of failure, when it approaches, is obviously the function of gun-metal next in importance. As a matter of professional experiment, the detection of the coming fracture of cast-iron guns may undoubt- edly be determined from minute cracks and other delicate tests. But from the fact that cast iron breaks in the testing machine at the instant of perceptible elongation, these evidences must be vague to the professional observer, and quite obscure to the per- sons throughout the fleets and fortresses of a country, who are in a position to decide the matter, however faithfully they may be looked after. Wrought iron and low steel continue to stretch after the point of permanent elongation. Mr. Anderson states* that "from sev- eral hundred experiments that have been made with wrought iron cut from bars intended for the manufacture of Armstrong guns, the following result has been obtained : The point of yielding per- manently, gives an average resistance of 28000 Ibs. per square inch, while the point of ultimate rupture gives an average of 57120 Ibs., or rather more than double that of the point where perma- nent elongation commences ; the margin that lies between these two amounts is of great importance as a condition of safety." In heavy forgings, the yielding and breaking points, although both lower, were found to be in about the same proportion. Mr. An- derson says that " the average point of yielding permanently was 23760 Ibs. average point of ultimate fracture being 48160 Ibs. The forgings from which the specimens were cut were all of high quality." The fact that out of some 3000 Armstrong wrought-iron guns, not one has burst explosively, or without giving warning, is com- pletely satisfactory evidence on this point, f The bursting of sev- eral solid wrought-iron guns without warning the Princeton's * "Journal of the Royal United Service Institution," August, 1862. f Two 40-pounders are said to have burst into small pieces under the extraordinary service of proving vent-pieces. WROUGHT IKOX. 339 gun (426), for instance is known to have been due to the degra- dation of the iron in the process of fabrication. The Committee of the Franklin Institute found by experiment that the iron of this gun had deteriorated 50 per cent, during its fabrication, from over-heating. 400. This refers to a gun made wholly of wrought iron. The authorities do not agree as to the use of wrought-iron hoops on cast-iron guns. Captain Blakely and others in England say that its limit of elasticity is too low to allow the necessary tension. If this limit is exceeded, or if, under constantly recurring strains, the particles readjust themselves, and acquire a new limit of elas- ticity, the rings will, after a time, cease to compress what is within them. Captain Parrott uses better iron, undoubtedly, and finds no sensible change of figure in a wrought-iron reinforce after the gun has been fired 1000 rounds. This, however, is under low pressures compared with those that will be required for punching modern armor. 401. RESISTANCE TO COMPRESSION AND WEAK. One of the desiderata for gun- metal is thus specified by Mr. Anderson in the paper before quoted: "That the material shall be sufficiently hard, so that the surface of the interior of the bore shall not in any way be indented or bruised, or otherwise acted upon by the powder or projectile, or even by the premature fracture or explo- sion of a cast-iron shell within the bore." He then gives the details of a series of important experiments made at Woolwich to determine the relative fitness of gun-rnetals in this particular. It is remarkable, that in resistance to compression, cast iron, wrought iron, and steel, are more nearly alike than in any of their other properties. "The pressure per square inch which is required in either metal to produce a permanent, sensible indentation or shortening, about equal to To 3 inch in measurement, ranges from 30500 to 40700 Ibs." " Ten specimens, parts of guns of the highest quality, but which have been severally burst, gave 35000 Ibs. per square inch ; pro- ducing an average compression of r ^ of an inch ; the softest being 30000 Ibs., the hardest 40300 Ibs." 340 ORDNANCE. " Ten specimens of rolled wrought-iron bars, made specially for guns, the specimens being selected at random and reduced from bars 3 inches square, all of the highest quality and suitable for guns, gave an average of 33000 Ibs. per square inch, with an aver- age compression of y^W inch ; the softest requiring 31000 Ibs., the hardest 35000 Ibs." " Ten specimens of wrought iron, cut from large forgings of superior quality, gave an average of 26900 Ibs., producing an average compression of T /o o of an inch ; the softest being 22800 Ibs., the hardest 31000 Ibs." " Ten specimens of soft cast steel of the finest quality, and that either withstood the proof-rounds, or which failed before the 7 proof-rounds were completed, gave an average of 35500 Ibs. per square inch, with an average compression of y^W inch ; the soft- est being 25000 Ibs., the hardest 46000 Ibs." " Ten specimens of cast steel more highly converted than the former, and in quality almost fit for cutting-instruments, but which broke first round at proof, gave an average of 76000 Ibs. per square inch, with an average compression of r^W inch." " A specimen of cast steel, cut from a gun made by Mr. Krupp, of Essen, cut from a gun which failed at first proof,* gave 25300 Ibs. per square inch, with a compression of yo'W inch." " Four specimens of steel and iron, welded together like layers of sandwiches, gave in the direction of the fibre, that is, pressing the steel and iron upon the edge of the sandwich, an average of 26000 Ibs. per square inch, with an average compression of y/or inch." " Four specimens upon the flat of the sandwich, thus pressing the two metals closer together, gave an average of 25400 Ibs. per square inch, with an average compression of T 3 F o- inch." " It will thus be seen, according to these experiments, which were all made on carefully prepared specimens, exactly 1 inch in length and ^ inch in diameter, that the average resistance to T^TF inch compression, or shortening, was as follows :" * From causes (138) that Mr. Anderson does not mention. WROUGHT IRON. 341 TABLE LVIII. RESISTANCE OF IRON AND STEEL TO COMPRESSION. I. Caft fteel 355 2,. Caft iron 35 3. Wrought-iron bar.. 33000 4. Wrought-iron forgings 2,6900 5. Sandwich fteel and iron on edge 26000 6. Sandwich fteel and iron on flat 25400 7. Krupp's caft fteel 25300 The low resistance of Krupp's steel to compression, is the test of a single specimen. The fact that the star-gauge showed no compression in a gun of this steel, after 3000 rounds and an unu- sually severe additional test (137), is evidence of at least sufficient hardness. '1O2. The chambers of wrought-iron guns have been perma- nently indented by the powder-gas. In the paper last quoted, Mr. Anderson says : " In wrought-iron guns, which have resisted proof successfully, minor defects will sometimes appear after a number of ordinary service rounds ; such defects have required a repetition of charges to bring them out into view for examination, each successive round acting like the blow of an enormous sledge- hammer, and gradually producing an alteration of form in the bore or in other parts of the structure." Mr. Anderson, testified before the Defence Commission,* speak- ing of the Armstrong wrought-iron gun, that "the effect produced with high charges is very considerable in compressing the iron, altering the dimensions of it. * * * In the larger guns that have yet been tried, there is more effect produced than in the smaller ones. * * * "We find the larger guns are affected to a small ex- tent ; they seldom come back from the proof the same size that they went away." In answer to various inquiries, Mr. Anderson stated that the 100-pounder was considerably enlarged in diameter by the first few rounds, and that the smaller guns also gave way to some extent. 4O3. On another occasionf Mr. Anderson said that he wished * " Report of the Defence Commissioners," 1862. f "Report of the Select Committee on Ordnance," 1862. 342 ORDNANCE. to use a hard wrought iron to avoid indentation, but that " the harder we get it, so the greater is the liability to non-welding ; now, the chances are, when the iron is hard, that some portion is un welded, and then the powder acts upon that part of it, and very soon makes it appear worse, and renders it necessary to with- draw the interior of the gun, and put in another lining." He also said that u the material which Sir William Armstrong is inclined to trust in is wrought iron, which has many defects, one of its greatest defects being its softness, or a liability to be in- dented ; we are now using wrought iron with a capacity of resist- ing a pressure of 33000 Ibs. on a square inch, but that is much too soft; the capacity of resisting pressure should be very nearly 50000 Ibs. to the square inch, to produce a sensible compression ; still wrought iron is very defective, for when the gun comes to be put together, if we make it of hard material, an effect which is pro- duced from having carbon, which leads to blistering and to defects in the welding, so that when the gun comes to be proved the bore may be defective, and has to be taken out and another put in. In commencing the manufacture, we applied to seven or eight of the first houses for the kind of material which we required, but none of the iron we obtained was fit for our purpose ; it was full of blisters, and did not weld properly, the consequence being that many of the guns had to be half made over again. By and by some of the makers having greater aptitude than others in seeing what we wanted, we obtained better iron, and our iron is now tolerably good, with a power of 33000 Ibs. to the square inch of resisting compression inside, and an ultimate tenacity represented by 57120 Ibs., as the strength of the iron in the outward direction, but the strength of the iron coils in the lateral direction are dif- ferent." Sir William Armstrong said before the Defence Commission, with reference to his own gun : "With a long shot and such a charge as would give a high velocity there would be risk of injuring the gun. The gun would also have to be inconveniently long. If you fire a long shot with a very heavy charge, you attain a point at which the material begins to crush : the metal in the chamber yields to the WROUGHT IRON. 343 pressure, and is displaced ; the gun begins to lose its form, and therefore it is desirable to keep your velocity moderately low." 4O4. Table LIX. shows the permanent enlargement of a 40- pounder (4'75 in.) gun made by the Mersey Co., under 117 rounds with increasing charges. The celebrated Horsfall gun is enlarged at the seat of the charge. Instances of the failure of Armstrong guns from this cause, are mentioned under another head. (See 444 and Table 64). TABLE LIX. EXPANSION OP 40-PouNDER RIFLE MADE BY THE MERSEY STEEL AND IRON COMPANY. (From the Report of the Select Committee on Ordnance, 1863.) Position of Enlargement. Vertical Expansion. Horizontal Expansion. From Breech- end. Increase in Diameter. From Breech- end. Increase in Diameter. Ins. Ins. Ins. Ins. [ 2 .031 2 025 In powder-chamber, original diameter, 4 96 in. ameter and 8 ft. long, were forged for two o 6-inch mor- tars which Mr. Mallet was constructing for the British Government. They were slightly tapered, and at one end there was a collar pro- jecting about 6 inches all round, and about 12 inches wide in the line of the axis, presenting laterally the general form shown in Fig. 166. The masses were forged from puddled slabs of manageable size, c by slabbing up two or more large flat pieces (Fig. 167), laying these upon each other, and welding them together into a rude sort of square prism, which was afterwards partially rounded down, at the corners, under the hammer. These pieces were welded together, appa- rently, perfectly sound ; but after they had become cold, they were invariably found, upon borings being made into the centre, to have large rents internally, with jagged, crystalline, irregular surfaces. * * * At first it seemed probable that the rents due to cooling, now to be described, were formed in the direction of the broad planes of the slabs; but more careful and exact examination proved that in more than one case, at least, these rents had undoubtedly been formed across, or at right angles to those planes. * * * The opposite faces of the rents were counterparts, and presented dis- * "The Coefficients of Elasticity and Rupture in Massive Forgings,-" Inst. Civil Engineers, March, 1859. 23 Fia. 167. Pile for mortar-chamber. 354 ORDNANCE. tiiict evidence of having been torn asunder by contraction, from the centre towards the circumference, as the mass cooled." Two of these rents are shown by Figs. 168 and 169. "The limits of FIG. 168. FIG. 169. Rents in forged masses from cooling. the fractures, as seen perpendicularly to their plane, were found to be generally as shown by Fig. 170. The ascertainable extent FIG. 170. Section of rent from cooling in mortar-chamber. was from two to three feet along the axis, and usually rather more than half the external diameter of the mass in breadth, measured across the large end. The cracks were from -J to |- inch open at the widest part, in the centre, and passed off, at each extremity, WROUGHT IRON. 355 to an indefinitely thin wedge. In no case was there a trace of bad welding or of defective workmanship. They were clean fissures, presenting opposite surfaces of solid, sound metal, though rough by being torn asunder. In this conclusion Mr. Clay coin- cided. On consideration, it appeared that the phenomenon was simply due to contraction on cooling." 421. Mr. Mallet reasons that this defect must occur in solid cylinders or conic frustra, " whenever the dimensions are such that the total amount of the contraction of the metal, in any one di- ameter, from its highest temperature down to that of the atmo- sphere, as fixed by the circumference of rigidity due to the outer cold shell, exceeds the limit of extension of the iron at rupture, due to the length of the diameter of the interior core, which cools last. This is the theoretic limit of the size of forging, beyond which internal rents must occur. " If it were possible that a cylindrical mass of forged iron could be increased sufficiently in diameter so as to bring it into evi- dence, there can be no doubt that the following would be the phenomena resulting from the conjoint reactions of its originally soft condition and uniformly high temperature, its external cool- ing, contraction, and assumption of rigidity, and the final cooling, contraction, and rigidity of the internal portions: the external surface would rupture in several places, parallel to the axis, and directed to the centre, in the first instance. These fissures would afterwards all close, and the opposite and abutting surfaces would press against each other, like the voussoirs of a circular arch. The internal diametric fissure, or fissures, would then be rent; the external form of the mass would change from a circle to an oval, the minor axis being in the plane of the internal rent ; and the whole mass would at length assume stable equilibrium as respects its molecular forces. The change to the oval figure would probably be accompanied with a reopening of some of the external fissures situated towards the ends of the major axis of the oval section." One great cause of the low measure of strength of material in heavy forgings is, obviously, the drawing asunder of all the par- 356 ORDNANCE. tides in both a tangential and a radial direction. Hence, as the foregoing authority expresses it, "increased distance in both direc- tions between the integrant crystalline faces is produced, and diminished cohesive strength ; the proof of this is to be found in the fact that the specific gravity of the material of these great forgings is lower than that of the iron from which they are formed, or than that of small portions of the same fagoted mass." 422. During the discussion of Mr. Mallet's paper, some attempt having been made to rebut the author's " assumptions," by a state- ment that large forgings were, after all, pretty sound and trust- worthy, he produced a statement from the manager of the Penin- sular and Oriental Steam Navigation Company, to the following effect : During ten years, an average of more than one serious accident had occurred from the breaking of large forgings, prin- cipally paddle and screw shafts, every three months, to one or the other of 41 ships. During the last five and a half years (down to 1859), there were 37 such accidents, or nearly one every two months, on the same number of ships. It was assumed that the cost of these accidents, due to the unsoundness of large forgings, would average $10000 each. 423. The comparative strength of heavy and light forgings, according to the experiments of Mr. Kirkaldy,* is as follows (Table 60): TABLE LX. STRENGTH OF HEAVY AND LIGHT FORCINGS. Lbs. pc-r sq. inch. Englifh rolled bars, higheft mean 64795 Scrap-iron, forged down, mean 53420 Crank-flialft, fcrap, cut length wife, mean 47 5 8 2, do. do do. do 43759 do. do. cut croffwife, do .' 44578 do. do. do. do 38487 Armor-plate, fcrap, mean 38868 do. do. do 36824 According to Mr. Mallet's experimentsf the tensile strength was as follows (Table 61): * " Experiments on "Wrought Iron and Steel," 1862. f " The Coefficients of Elasticity and Rupture in Massive Forgings." WROUGHT IRON. 357 TABLE LXI. STRENGTH OF HEAVY FORCINGS. Tons. Hammered flab or bar, 12x4 inches 24-063 Fagoted forged flab, 48 x 48 x 12 inches 18-594 Horsfall 13-inch gun, original fagot bars 19-688 do. do. longitudinal cut from gun 18-839 do. do. circumferential do , 16-561 do. do. tranfverfe do 16-56* do. do. charcoal-rolled bar, from borings of gun 22-321 424. On the other hand, the solid-forging process overcomes a grave objection to the plan of hooping the fracture and relaxa- tion of parts due to want of mass and continuity (299, 335). 425. Only a few large guns have been fabricated by the solid- forging process. Several of these have burst on trial. A wrought- iron 8-inch gun forged at the Gospel Iron Works, and proved at Woolwich on the 17th July, 1855, burst into several pieces at the first discharge, with 28 Ibs-. powder and 2 spherical shot. The gun is stated to have been of very nearly the same dimensions as the established cast-iron guns of the same calibre. The thickness at the breech end was therefore about 9 inches. The metal appeared to the eye to be sound and perfect without and within.* 436. The most memorable case is that of the 12-inch solid- forged gun, Fig. 171, called the "Peacemaker," that burst on board the United States steamer Princeton. The gun was built by Messrs. Ward & Co., under the direction of Commodore Stockton. The 12-inch gun, Fig. 66, now in the Brooklyn navy yard, almost an exact copy, was built by the Mersey Steel and Iron Co., to re- place it. A committee of the Franklin Institute, of Philadelphia, made a detailed examination into the character of the " Peacemaker" gun ; from their reportf the following facts are compiled : The greater part of the iron of which the gun was composed, was in the shape of bars 4 in. square and about 8-J- ft. long. Of these, 30 were laid up in a fagot, welded, and rounded up into a shaft 20 to 21 * "On the Construction of Artillery," Mallet. Appendix, f "Journal of the Franklin Institute," Yol. 3, p. 206 (1844). 358 ORDNANCE. FIG. 171. The Peacemaker" 12-inch wrought-iron gun. in. in diameter. Iron in the form of segments, varying in weight from 200 to 800 Ibs., and usually large enough to reach -J round the gun, were then welded on, there being two strata of segments over the breech. The hammer used weighed 15000 Ibs. The time occupied in the forging, during which the iron was kept more or less heated, was 45J days. The gun was broken across nnder the trunnion-bands, the chase remaining entire. The breech split into 3 principal pieces, the largest of which, 5 ft. long and embracing half the circumference of the gun, is shown at Fig. 172. A part of the fracture showed large crys- tals lying in various planes. Traces of the original bars were observable; also spots covered with scale. The relative size of one of these (10 x 3 in.) is shown at a. "Besides the spots indicating a want of continuity in the metal in the plane of the fracture, the edges of many others, in different places, were observed; also a wide solution of continuity was seen through- out a cylindrical surface, con- WROUGHT IRON. 359 centric with the bore, and extending, in one place at .east, entirely around the fragment. This was evident from the FIG. 172. Fragment of the "Peacemaker." fact that oil, poured in at the upper side, came out at a, after passing through a distance, within the fragment, of about 3 feet. Another opening in the prolongation of the cylindrical sur- face is shown at c. The sides of this were separated to a distance of a quarter of an inch, and, by inspecting these, it was evident that they had never been welded ; into this opening a wire was thrust to a depth of 10 inches." Several other considerable fis- sures were observed. TABLE LXII. STRENGTH OP IRON IN THE "PEACEMAKER" GUN. The mean tensile strength per square inch of the original bar was 1st bar 46086 Ibs. 2d " 38595 " 3 d " 5*521 " Other experiments made from the same iron gave the following results : I. The average tensile force with which the specimens from the interior of the gun broke, when strained in the direction of the fibre, is less than... 32100 Ibs. a. The specimen from the interior, strained in a direction across the fibre, gave a3700 3. The specimens from the outside of the gun, across the fibre, gave an aver- age of less than , 45333 *' 360 ORDNANCE. 4. Annealed specimens from the interior, strained lengthwise of the fibre, gave an average of 36067 " 5. The average of all the specimens from the gun, not hammered, is 33300 " 6. The average of the specimens, worked down under the hammer, is 63475 " The general conclusions, from these results, are the same as those from the experiments made by the Committee in Boston, so far as the two series can be compared. 1. The average strength of the iron, as it existed in the gun, from both series, is 335^6 Ibs. 2. The average strength of the iron from the gun, after being drawn down with the hammer, from both series, is 59824 " 3. The average strength of the original bar from the experiments of the first series, is 46950 " Consequently, taking the original strength as 100, that of the average of the iron, as existing in the gun, was 72, showing a deterioration of 28 per cent. ; and if the tensile force of the inte- rior be taken, when strained in a direction across the fibres, that being the actual direction of the strain in the gun, the proportion to the original bar is as 50 to 100, or a deterioration of 50 per cent. The Committee state, in conclusion, their "opinion, that, in the present state of the arts (in 1844), the use of wrought-iron guns of large calibre, made on the same plan as the gun now under examination, ought to be abandoned, for the following reasons : 1. The practical difficulty, if not impossibility, of welding such a large mass of iron, so as to insure a perfect soundness and uni- formity throughout. 2. The uncertainty, that will always pre- vail, in regard to imperfections in the welding ; and 3. From the fact that iron decreases very much in strength from the long exposure to the intense heat necessary in making a gun of this size, without a possibility, with the hammers at present in use in this country, of restoring the fibre by hammering." Experiments were made to determine the tensile strength, 1st, of the original bar ; 2d, of a bar cut from the interior of the gun ; 3d, of a bar made from a portion of the gun reworked under the hammer. The mean strength of two large forgings steamship crank- shafts was found by Mr. Kirkaldy to be 45670 Ibs. in the direc- WROUGHT IRON. 361 tion of the grain. Among his " concluding observations" are the following which bear on the subject : " Inferior qualities show a much greater variation in the breaking strain than superior. " Greater differences exist between small and large bars in coarse than in fine varieties." From which it may be concluded that large forgings are not only weaker than smaller bars, but less uniform and trustworthy. 427. Speaking of wrought-iron guns, Mr. Mallett says :* "The facts (which he has previously stated) are worthy of notice, as in- dicating the absolute uncertainty that ever must exist as to the trustworthiness of wrought-iron guns, forged in one great mass, although executed without regard to cost, and by parties anxious faithfully to produce a result of the highest excellence. Some of the evils incident to this gun might have been avoided by greater experience and judgment ; but the main evil is inherent, and in- separable from every huge forging, and most so where the weld- ings are most numerous."f On the other hand, Mr. Clay, of the Mersey Iron Works, differs from Mr. Mallet, and very justly observes, that " the several fail ures in the manufacture of wrought-iron guns should not be a mat- ter of surprise ; for it is hardly reasonable to expect immediate success in any new fabrication." 428. Mr. Clay gives an account;}: of experiments to determine the tensile strength of the iron from which the monster gun (no.) * "On the Construction of Artillery," 1856. f Mr. Anderson says on this subject: "A few years ago it was believed that the proper gun would be obtained by forging. In 1854, when Mr. Nasmyth was at work, the country expected great results. The end of that gun might be said to have been a national disappointment. Since then, there had been the Liverpool guns a monster mortar, which was referred to in the paper. It was a magnificent forging the finest he had ever seen yet it was not a perfect gun. The bore of that gun; would never have passed the proof of the artillerist. There were defects in it, and that would always be more or less the case in the heart of all such large structures when forged. At the present moment there were at Woolwich some apparently very fine forgings, which were defective, owing to fissures at the core, and more especially in the chamber at the breech. Therefore he did not think the good gun which all were aiming at would be obtained by the system of forging." "Construction of Artil- lery," Inst. Civil Engineers,- 1860. "Orr's Circle of the Industrial Arts." 362 ORDNANCE. was made, and of the same iron, after manufacture into the gun. The results were as follow (Table 63) : Taking the average of the first two experiments, and comparing it with that of the following three, there is a decrease of strength of about 13 per cent. ; whilst on the other hand, as compared with the 6th, 7th, and 8th, there is a gain of 2 per cent. Mr. Longridge is of the opinion* that these experiments are not very conclusive, because " the iron was cut from the muzzle of the gun, and not from the interior at the breech, where the thickness is greatest and the deterioration is necessarily the most." He sums up the question by saying that " the manufacture of large forged wrought-iron guns is an operation of great difficulty, ex- pense, and uncertainty ; and however the difficulty and expense* may be decreased, the uncertainty must still remain. Moreover, TABLE LXIII. STRENGTH OP IRON IN THE HORSFALL GUN. Experi- ment. No. Description of Iron. Breaking strain in Ibs. per sq. in. Average. Sample bars 4 in. long. Elonga- ted in. I 2 3 4 5 6 7 8 9 10 ii Original Ditto Cut acre Ditto Ditto Cut wit Ditto Ditto Borings Ditto Borings iron of which the gun was made., ditto 4 8 3 8 4 | 50624] 41644] 43904 L 50624] 48384] 50624 i 5 286 4 J 6o 5 8 4 | 62824) 76584 49504 43390 50624 61704 76584 * i t 1 1 1 I i i i ft ss the grain from muzzle of gun... ditto ditto . i the grain from muzzle of gun ditto ditto from gun reworked with coal...... ditto from gun reworked with charcoal.. 12 Swedish iron as imported, inch square 60584 60584 1 "Construction of Artillery," Inst. Civil Eng., 1860. WROUGHT IRON. 363 at the best, it is but substituting for cast iron a material of a higher tensile strength ; the radical defect of a homogeneous mass still remaining, viz., the unequal distribution of the strain, from the inner to the outer circumference." 429. Hollow-Forging and Rolling. The Alfred gun (115) was forged hollow a process which, according to Mr. Clay, the maker of this and of the Horsfall gun, overcomes several defects of the system last discussed. He says :* " We forge our guns hol- low, which gets over a difficulty which we had experienced, namely, the tendency to contraction in the breech of the gun, where the metal is exposed to the cooling influence of the air on three sides instead of merely on the two sides, and where, the out- side crust getting cool first, a contraction takes place. By forging them hollow, and leaving the breech screwed in, similar to the Armstrong 10^-inch gun, and similar to our Prince Alfred gun in the Exhibition, we get over the difficulty." This process also gives the superfluous cinder more chance of escape, and may be conducted so as to make the heat more uni- form throughout the mass. Still, the fundamental defects of the solid-forging process remain the multiplication of welds between badly-fitted parts, and their liability, from various causes, to be unsound ; overheating ; the wrong direction of the seams and of the fibre ; and the comparatively small reduction and purification of the mass after it is aggregated. A number of field-guns, now in service, were rolled hollow at the Phoenix Iron Works of Pennsylvania, on the plan of Mr. Grif- fin. Rolled staves in. x in. x 4^ ft. long, were laid up in the form of a barrel, on an arbor which was placed in a lathe. A long bar 4 x 4rJ in. a rhomboid in section was wound spirally upon the barrel by the revolution of the lathe. Another bar was wound upon the first, the spirals running in an opposite direc- tion, and so on until five layers had been applied. A thin layer of staves was then bound upon the outside, and a plug driven into the breech, to close it, and to form the cascable. The vrhole -. "Report of the Defence Commissioners." 1862. 364 ORDNANCE. was then heated to welding and upset endways two inches in a press, after which it was drawn out between the rolls from 4J to 7 feet in length. The trunnions were then welded on, without removing the gun from the reverberatory furnace ; the bore was dressed out, and the chase reduced to the proper size by turning, the mass being cylindrical when it left the rolls. These guns are well spoken of by Captain Benton,* and appear to have been suc- cessful on a small scale. 4SJO. But the Phoenix Iron Company have now abandoned this process, and substituted another, which produces a cheaper and sounder gun, and promises well for larger ordnance.f A * "Ordnance and Gunnery," 1862. f The following is an abstract of the specification of Mr. D. T. Yeakel, of Lafayette, Indiana, for British patent, dated April 16, 1862: "One of the improved modes of constructing cannon and other ordnance, which forms the subject of the present invention, consists in rolling or winding a plate, or sheet of iron or steel, or several (if more than one is required), around a central man- drel of wrought iron or steel ; the whole mass is to be welded together as it is rolled up, or, after it is rolled up, the welding to be done by the pressure of rollers, or the impact of a hammer or hammers at welding heat. The mandrel should be of less diameter than the desired bore of the gun-barrel or shaft-cylinder, if the latter is intended to be hollow, so that the boring may remove all of the mandrel. "Another mode of carrying out the invention consists in using a cold mandrel of wrought or cast metal, and rolling the sheets or plates of iron or steel around it till the desired size is produced. Sheets or plates are to be rolled around the mandrel at a welding heat and welded together as rolled, then removing the mandrel, and boring, reaming, and turning in the manner now pursued with cast guns or hollow shafts. "Another mode consists in rolling up the sheets or plates in the same form, but without the mandrel, then inserting the mandrel and welding the whole mass together. The mandrel should always be less than the bore or hollow to be produced, if the mandrel is to be bored out or otherwise removed. The plate or sheet used should be of sufficient length, when used in one piece, to produce, when rolled and welded, the barrel or cylinder of the desired thickness or diameter before turning, and of a breadth several inches wider than the desired length of the barrel or cylinder. The sheet or plate of iron or steel may be used of a uniform thickness, or it may be tapered from one edge of its breadth to the other, so as to produce, when rolled or welded, the- approximate shape of a barrel before turning; if used of a uniform thickness, the rolling must be continued till a sufficient diameter at the breech is obtained. "By the improved process of making cannon or shafting, the most carefully con- solidated plates of iron or steel are welded together in one continuous length, thereby producing a quality, viz., uniform consolidation of metal, aad a form of barrel com- posed of concentric welded folds, capable of offering a resistance to the explosive force of gunpowder, which cannot be obtained in any other way." WROUGHT IRON. 365 FIG. 173. sheet of iron is rolled around a mandrel into a cylinder, and drawn down into a tube with solid walls. The bore may be made entirely within the mandrel, which may be of steel. The seams in this case would not weaken the gun indeed, the mere sticking of the iron together would prevent its un- coiling under fire. And the iron may be refined before it is made into a gun. But with all these advantages, the 7-inch gun made on this plan for Mr. Lynall Thomas, at Newcastle, burst at the second round (127), although the field-guns of the Phoenix Iron Companv stand * J Gun made from a sheet of iron. very well. 431. Mr. Ames's wrought-iron gun, of which the fabrication and test were mentioned (128), is forged hollow by welding a series of short, thick rings to the end of a bar, thus building out the gun from the breech to the muzzle. The rings are separately hooped before welding ; any initial tension they may have is destroyed in the subsequent heating and hammering, and the gun is left without the desirable initial strains. At the same time, it is left without rupturing initial strains the inetal is substantially in a state of repose. As the rings are forged solid, no well- defined grain is developed in the direction of its circumference, as in the Armstrong or Phoenix Iron Company's guns. But there are no longitudinal yields. The principal strain of the powder is resisted by the unbroken strength of the solid ring. Overheating and the bad effects of imperfectly fitting pieces, welding in cin- der, and light hammering, are more likely to be avoided, and the advantages of cooling the mass, to some extent, from within, are secured. The process appears to be in many respects an improve- ment on the plan of building upon the end of a bar with rough pieces and multiform welds. 366 ORDNANCE. 432. The Armstrong Gun. The process by which this gun is fabricated, and its charges, have been described in the first chapter. The gun consists of several hoops (Fig. 174), welded up from FIG. 174. FIG. 175. coils (Fig. 175), and shrunk together (Fig. 176). The breech- piece is forged so that its grain shall run longitudinally. 433. LEADING FEATURES OF THE SYSTEM. These are First. Placing the grain of the iron in the direction of the greatest strain, and opposing the tension of the welds to the least strain. That is to say 1st, the grain and the welds in the body of the gun run in the direction of its circumference. 2d. The grain of a suffi- cient portion of the breech to resist the longitudinal strain runs parallel with the bore. Second. Placing the outer hoops in initial tension, so that all parts may be equally strained at the instant of firing (287). Sir William Armstrong has publicly stated* that he did not carry out this plan with the nicety prescribed by Mr. Longridge (293), but that the rings were simply applied with a sufficient difference of diameter to secure effective shrinkage. Indeed, Sir William con- sidersf the important principle of his gun to be, not merely build- ing up a barrel, nor the placing of it under regulated initial strains, but welding coiled tubes end to end, and shrinking them together. Third. The breech-loading, and, Fourth. The system of rifling and projectiles, are the other leading features of the Armstrong Ordnance, and will be consid- ered under their respective heads. Both tend, directly or indi- * "Construction of Artillery," Inst. Civil Engineers, 1860. f Select Committee on Ordnance, 1863. WROUGHT IRON. 36 FIG. 176. rectly, to weaken the gun, and are either modified or abandoned in the heavier guns. 434. ADVANTAGES OF THE SYSTEM. The first grand advantage of wrought- iron tubes having the grain in the di- rection of the greatest, and the welds in the direction of the least strain, and having such initial strain that all the iron will do equal work at the instant of firing, is, obviously, great strength to resist internal pressure. The prac- tice, also, warrants this conclusion. Besides the wrong direction of welds . and fibres, and possible flaws, and the want of proper initial tension, other defects of the solid-forged gun are modified or avoided in the Armstrong gun ; among them, unequal shrinkage (420), and the various bad effects of light hammering (419). Although the iron of the Armstrong gun is refined before welding (414), and although the pressure in welding the coil into a tube is not as uniform as it should be, the heat is so uniform, and the surfaces to be joined are so plain, that the union of the parts can be more certainly relied on than in case of the solid-forged gun. The iron is refined; in the other case, it may be crude after the forging is done. Burning the iron may be avoided, but there is enough over-heating: to o o weaken the material. Mr. Anderson says :* " When rolled bars of the best * "Journal Royal United Service Inst.," August, 1862. 368 ORDNANCE. quality are wound into coils, and then welded into cylinders for gun manufacture, the iron, as a general rule, is found to suffer to about 3481 Ibs. per square inch on the average. The follow- ing shows the average results both in regard to yielding and breaking : Yielding point. / Ir n in ba r.-; 3o \ " cylinder 27852 Rupture point. r"; \ ' cylinder 555 " The loss is due to the necessary heating being greater in pro- portion than the working." 43o. Another advantage of this system of fabrication, is thus stated by Mr. Anderson : " In building up guns of cylinders, this high tenacity afforded by the coil system circumferentially, and the opportunity which it gives of knowing the soundness of the gun in every part, and from the fact that every part of the gun is put under the full exercise of its duty from the commencement this arrangement of building up guns will always have an im- mense advantage over guns made of a single solid forging, in point of strength and security against bursting of the whole structure ; and even when the coiled cylinder is considered as a means of obtaining the inner lining or bore of a rifled gun, a purpose for which it is by no means so perfect, yet, even in that respect, it is superior to the bore which is formed within the heart of an im- mense forging, of dimensions suitable for a large gun, such a mass of forging being always more or less defective, even under the best and most careful workmanship." 436. The comparative strength of the coil system and the solid-forging system, has been tested as follows : A 6^-in. wrought- iron guri, weighing 9282 Ibs., made from a block forged at the Mersey Iron Works, was tested as follows, in 186*2. Charge, 16 Ibs. ; 10 rounds with 68-lb. 10-oz. shot, 10 with 136-lb. 8-oz. shot, 10 with 204-lb. shot, 10 with 273-lb. shot, 10 with 340-lb. 8-oz. shot, 10 with 410-lb. shot, and 10 with 476-lb. shot. At the 70th round, the gun burst into eight pieces. Subsequent experi- WROUGHT IRON. 369 ments on the metal showed it to possess a tensile strength of 45359 Ibs. A 6^-in. Armstrong wrought-iron gun was tested in comparison with the above. The inner barrel was made from a solid forging ; weight, 9474 Ibs. The gun fired 100 rounds; charge, 16 Ibs. The projectiles were cylinders, beginning at 68-lbs. 10-oz. weight, and increasing, every 10 rounds, the last rounds being 672 Ibs. At the 60th round a cavity was found in the chamber, which grad- ually increased to 2'75 in. deep, with small fissures. Afterwards, however, a 40-pounder and a 12-pounder Mersey solid-forged gun were tested (122), and the committee reported* that "both these guns have shown an endurance, if not fully equal to guns made on the coil system, yet at least ample for the requirements of the service, if it is accompanied by the power of resisting a very great number of service charges." 437. The following is an official account of the " endurance, under testing, of a 100-pounder Armstrong breech-loading gun :f " My Lords Commissioners of the Admiralty desire that the fol- lowing particulars as to the testing for endurance of an Armstrong 100-pounder breech-loading gun be communicated for the infor- mation of the officers and crews of Her Majesty's ships. " The proof of this gun, which was conducted in the usual man- ner, was commenced on the 20th June last, and was carried on until 100 rounds had been completed on the 10th September last. The charge of powder used was the service charge of the gun for shot of 100 Ibs. as originally proposed by Sir William Armstrong, viz., 14 Ibs. ; which will not be exceeded for shot of 110 Ibs. For the first 10 rounds, cylinders of 100 Ibs. were employed ; for the next 10, cylinders of 200 Ibs. ; and so on, up to the last 10, for which cylinders of no less than 1000 Ibs. were employed. These last were 8 ft. 8 in. long, and projected 2 feet beyond the muzzle. The gun was found to be uninjured. The powder-chamber and shot-chamber were found slightly seamed in the direction of the grain of the iron. The breech-screw worked freely throughout the * "Report of the Select Committee on Ordnance," 1863. f From an admiralty circular. 24 370 ORDNANCE. experiment. Two steel vent-pieces were broken in the course of this experiment, viz., at the 28th and 31st round respectively ; one wrought-iron vent-piece, after being used from the 32d to the 81st round, was found so much worn on the face as to injure the cups ; and a second wrought-iron vent-piece was used from the 82d to the 100th round. This vent-piece was observed, at the 91st round, to exhibit a number of fine cracks, which extended considerably in the course of the remaining 9 rounds; it broke at the 4th round of a subsequent experiment, with proof-charges of 27-J Ibs. and a single proof-shot of 110 Ibs. The breech-copper required refacing at the 30th round ; after every 35th round it was removed and replaced. At the 85th round the new copper was refaced, and replaced after the 63d round ; the copper then put in received no repairs during the rest of the experiments. Lubricating wads of the service pattern were used for the first 10 rounds, afterwards those of Captain Lyon's pattern. The powder-chamber was washed out after each round, to allow the expansion of the breech-copper to be measured. Gups of strong tinned plate were used for the first 35 rounds, but were too weak to resist the pressure exerted by the gas, with the cylinders of the weight then in use, and were replaced by copper cups, which answered well for the remainder of the trial, being seldom broken. The recoil, as the experiments advanced, became very violent ; the suspending-rods, ultimately, were removed, and the gun was placed on a species of carriage, which recoiled up a steep inclined plane, checked by sand. It is stated, however, by the Inspector of Artillery, that great difficulty was found in completing the experiment even with this arrange- ment. The gun used in these experiments was of Elswick manufacture, made entirely on the coil principle, and weighed 81 cwt. 3 qrs. 16 Ibs., and was of the usual external dimensions. The remarkable strength exhibited by this gun is very satisfactory, and would appear to leave nothing in that respect to be desired, except some improvement in the vent-pieces, which every endeavor is being made to effect." 438. It should be remarked, with reference to this experi- ment, as was suggested by Commander Scott before the Select WROUGHT IRON. 371 Committee on Ordnance (1863), 1st, that the great length of time occupied by the experiments prevented the possibility of heating the gun ; 2d, that the lead was turned down off the cylinders, and did not close the bore of the gun ; 3d, that the velocity of the heavy cylinders being lower than that of the service-shot, the destructive effect of jamming the shot through the rifling was modified ; and 4th, that the gun was kept perfectly clean. 439. Sir William Armstrong stated, before the Select Com- mittee on Ordnance (1863), that "with guns which had been previously fired 100 rounds with shot rising up to 100 Ibs., one gun had stood 319 proof rounds, another 274 proof rounds, another 357 proof rounds, another 261 proof rounds, another 313 proof rounds, another 119 proof rounds, and one only 27 proof rounds." He also stated that one, previously cracked, stood 15 proof rounds, which showed the high ultimate strength of the gun. As to the endurance of some of the 12-pounders, he says: "!N"o. 7 has been fired 3263 rounds, and is perfectly good and service- able. I have here another 12-pounder which has been fired 1453 rounds, another which has been fired 1515 rounds, another which has been fired 1911 rounds, and another which has been fired 1146 rounds, which may be taken as instances of the very great endurance possessed by these guns." 440. Table 64 gives a list of all the guns returned to Woolwich for repairs up to June 3, 1863.* Sir William Arm- strong makes the following statement! with reference to the guns mentioned in Table 65 : " Out of 66 9-pounders issued, only one had to be returned for repairs; of the 12-pounders, out of 392 land service and 178 sea service issued, 13 had to be returned. This is exclusive of 20 broken vent-pieces and 22 broken breech- screws. These guns had fired some 50000 rounds. Of the 40-pounders, 641 were issued and 9 returned. Of the 110-pounders, 799 were issued and 9 returned." * We have no means of knowing how many, if any, guns requiring repairs have not been returned; but we know (443) that many costly repairs are required before the guns are issued. f "Report of Select Committee on Ordnance," 1863. 372 ORDNANCE. CO CO CO co Slfi -w '3 JC , , . CO 00 <* . O\ o . CO i! 0\ | : ' M M VO : ? vn : O .S So bO -0 c g .S 3 o 1 3 S be shortened S 3 be converted u erviceable. be converted i OH T3 IB u 3 I "B. .S '> (2 o F- _o s^ C/2 (2 X L 3 OH o u -a . 13 u o '> "3 Jj . f JU 5 a U d JS OH U c PS 3 u OH E rt u u T3 u _O U ho pj C W c OH U -5 s 13 u c n 13 S U Unservi o 5 o Unservi f g S c D Unservi P (I) i U P< (U S u c G ji ^ "o 3 3 jQ i 1 . s u 1 "O >N b ii "N M .S -o C c 3 3 "N 1 "8 a C 'i u ji u B w o 3 g ^ *o u IS ^0 3 c ON CO C bo 3 C imber a u u "s <*-! w c <-t to ~ o C JQ 03 i d _ ij o v 5 C rt c M c c u 8 u w u 1 O u 4-1 c 3 C 1 15 3 13 C J 1 C u u J T3 W ~* bo 1 EH C 'On Exterior Exterior 3 rt O Coil beh ho C '5 JI *O u C C 1 C C C S bO C 'c bo C S '5L !s to c 'c I 13* -a a 4J J o g cT cl CO -- o i *. ON o OH * 1 rt rt e H ON * U M CO M fc i 1 l< : : : j 3 4 i OH -a O- "Sn OH -o OH "H. B OH OH i OH "On 13 OH 1 "S i ON ' r ', A tf u C/3 'o 2 2 c Used for proving vent-pieces. o -5 e/J .-* 4^ 4-t 4-J r? B ^ o _c a U | o* - T3 1 2 y i J5 o SB -o c ^ s B 2 3 3 Repaired wit 'o i . fiuo 1 -o i 3 Repaired, an Repaired wit 3 3 U C O i PS Cu u C "3 o 3 o 3 1 E s '5 2 3 c 7^ U) I V C 1 u 1 PS u .s .s >, s 1 fe S S 15 c s c JJ u ? 1*4 .9 c $ 6 . .2 C i*, o tr c :hamber. runnions s J: T3 "u chamber. 2 u chamber. 'der-cham chamber. II I *Cu chamber. Ij jjj 4-J 4J PS ^ u o "c 2 'J 3 PS E -> i o u I o " tJ c 3 'J u 1 L c PS 1 .S 3 TJ u PS C U | 4-1 U C C bo PS Ij c ^ 3 TJ 1 C J2 fi 5 "o JS, TS 1 1 e ^ o c 1 1 .S 1 -G C 5. Hence it appears that, although in the general practice, welds are treated as weak points, and a still further allowance is made, especially in large forgings for actual seams or flaws, there is no physical law against sound welding, if iron and iron are brought together at the proper heat, and under the proper pres- sure. A certain amount of cinder is necessary to the process, but this already exists in the iron, or may be artificially supplied. The risk, as far as cinder is concerned, is, that too much of it will be enclosed by joining the edges of the iron, and thus preventing a union at the centre (Fig. 179). To remedy this defect, it has long since been proposed to shape the parts so that the centre or one edge will be first joined, thus allowing the superfluous cinder WROUGHT IRON. 383 to be squeezed out at one or both edges, as the parts are brought together. (Figs. 180 and 181.) This improvement, which special Fig. 179. Fig. 180. Fig. 181. provision is made to avoid in the Armstrong gun, by bringing the coils (slightly upset on their edges by the coiling process) flatly together (Fig. 179), is adopted in the welding of the reinforce of the Parrott gun, by bringing the edges together first (Fig. 181). 456. The next condition of a perfect weld is, that no substance that will impair it shall be interposed between the parts. Oxide of iron, in the form of scales, which form very rapidly when a heated bar is exposed to the air, undoubtedly prevents a perfect union. The blacksmith joins his two bars in the fire, or as quickly as possible after they are removed ; or, if much time is lost, he brushes away the scale, and then instantly closes up the joint by heavy blows ; and so makes a good weld. But several minutes must elapse before large parts can be brought together. Mean- while, thick scales are forming in places where they cannot be removed. The rapidity with which iron at a welding heat becomes oxydized is strikingly illustrated in the operation of "patting" the Armstrong tubes after they are welded end to end (8). The scales that form on the inside of the tube are jarred off at every stroke of the hammer upon the outside, thus exposing fresh surfaces to oxidation. At the end of the process, the scales form a pile in the tube several inches in depth. 4o7. To upset the Armstrong coil (432), it must be taken from the furnace by a crane, swung round to the hammer, and located on the anvil. By the time this is done, a thick scale, which can- not be got at and removed, has covered the entire surface to be welded. The first few blows of the hammer jar off this scale, exposing fresh surfaces to oxidation, before the seam is sufficiently closed to exclude air. If the surfaces were bevelled so as to close up at one edge, or in the centre, first, the outflowing cinder might 384 ORDNANCE. carry off some of the scale. As they are, both cinder and scale must be shut in. This would appear to explain the reason whv Mr. Anderson gets only the highest average tenacity of 32140 Ibs. at the welds between bars having 55500 Ibs. 458. Since oxidation cannot be prevented by any practicable rapidity of operation, the only remedy appears to be the exclusion of oxygen, that is to say, making the weld in an atmosphere which contains no oxygen, or, at most, but a trace of oxygen. The gas- eous products of combustion constitute such an atmosphere. The parts are already in it when raised to the welding heat, and require only proper contact before they are removed from it, to avoid the interposition of scale. Gas-welding was long since proposed by Mr. W. Bridges Adams, of London, and referred to by him during the discussion on " The Construction of Artillery," already quoted,* as follows : " As regarded the question between built guns and solid forgings, the present practical condition of the art of forging made the former mode preferable ; but it was probable that ultimately a mode of welding by jets of intense gas-flame, instead of by fur- nace-heat, would enable the manufacturer to pile any mass of iron together in perfect welds, without any oxidation of the surfaces internally " 459. This system has been applied to the construction of steam-boilers with great success, considering the crudity of the machinery and processes employed, by Mr. William Bertram, of Woolwich. f The edges to be welded are placed in contact between jets of flame issuing from two furnaces attached to cranes or cars, one on each side, after which the furnaces are removed, and the compression is done (not much is required when the sur- faces are clean and fit well) by hand-hammers or steam-hammers, so fixed to the same or other cranes or cars that they can be instantly brought into service. Government experiments at Woolwich show the following percentage of strength, that of the plate being 100 : *" Construction of Artillery," Inst. Civil Engineers, 1860. f Patent, Dec. 21, 1854. No. 2692. WROUGHT IRON. 385 Flush % |pH joint, -| in. plate 82^- Do. do. -fa-in. do 101 Do. do. -f-in. do IO 5*7 Bertram's process is successfully employed by the Butterly Iron Company in the manufacture of heavy beams. The sul- phur in coal is another cause of imperfect welds. The bad effects of this mineral are so formidable, that Mr. Bessemer melts the pig-iron, for conversion by his process, in a rever- beratory furnace, rather than to risk its 'contact with sulphur in a cupola. Adequate heat and pressure are the remaining obvious condi- tions of sound w elding. Although little pressure may be required, an excessive amount can do no harm, but, on the contrary, im- proves the iron. 46O. HITCHCOCK'S SYSTEM. To carry out, in the fabrication of large cannon, the principles of sound welding considered above, Mr. Alonzo Hitchcock, of New York, proposes the system illustrated by Fig. 182. The iron is heated in a reverberatory furnace, to avoid its contact with sulphur and other impurities of coal. The gun is formed of rings of wrought iron, or low steel made without welds (68), and upset or butted together, as by Ames's process (128). The rings are so formed as to be united first in the centre (455), that the superfluous cinder may be squeezed out. The anvil (&) is seated on the piston of a hydro- static press (V), so as to be lowered as the successive rings (a) are added. The furnace (/") is situated between the anvil and the steam-hammer (h\ and so arranged that the rings project into it from below, and the hammer drops into it from above. The ring to form the muzzle of the gun is laid upon the movable anvil and projected sufficiently into the furnace to allow the flame to raise it to the welding heat. Meanwhile, in another part of the furnace, the rings (k) are heated to welding in the same time, by proportioning the heat; by means of dampers, to the relative bulks of the two parts. Without removing the parts from an atmosphere in which there is very little if any oxygen, they are laid together and instantly welded by a few strokes of 25 386 ORDNANCE, Fig. 182. Hitchcock's system of forging cannon. WROUGHT IRON. 387 the steam-hammer. The anvil is then lowered by the thickness of another ring, and the same process is repeated. Although the gun may be of any size, the parts actually united at one operation may be made so light by reducing their thickness, that the pressure of a hammer of moderate weight will be adequate. And when the whole operation of upsetting is confined to one joint, exactly the requisite pressure for that joint can be applied; and there is no fear of injuring other parts by setting it up soundly, because the mass of the gun below it is cold, and forms a rigid pillar practically a continuation of the anvil. 461. The blows upon the end of the Armstrong coil (Fig. 183) have to weld a great number of joints ; those next the anvil and those that, from bad fitting, require the most pressure, are not always set up until other parts of the tube, which is a long column softened by heat, are bulged and disfigured. To avoid destroy- ing the tubes in this way, they are made in short lengths, which have to be joined by a subsequent process, at a considerable cost. Even these are bulged, and have to be restored to the cylindrical shape by " patting" (8). 462. It would appear that all the conditions of sound welding may thus be attained, if the process can be practically carried out. The objection raised by some iron- workers, that the single ring will be burned before the larger mass is heated to welding, is not well founded. Certainly the heat in what are substantially, or may be actually, two different furnaces, can be regulated with the utmost nicety. Besides, the mass is already hot before the ring to be added to it is put into the flame. Locating an anvil upon water is simply a question of the strength of what holds the water. A screw would answer the purpose, and would not be liable to derangement, since an accurate fit is not important, and the ad- justment does not take place at the instant of the blow. Or, the screw might be employed simply to elevate and depress the anvil the force of the blow being received by blocks of varying thick- ness, placed between the anvil and its bed. 388 ORDNANCE. 463. The mechanical difficulties do not appear to be serious ; and a considerable cost of apparatus is warranted by. the certainty of sound work. The expense of dressing the ends of short tubes by the Armstrong process, and of making colossal furnaces and hammers to heat and condense a 30 or 40-ton forging to the core, is dispensed with. Indeed, the furnace may be little larger than that employed for gas-welding the Armstrong tubes (8). 464. Mr. Hitchcock's process was intended especially for fabri- cating guns of low steel the rings to be made without welds, by being originally cast in the form of small thick rings, and then rolled, in a modification of the tire-rolling machine, to a larger diameter and a smaller section. This treatment would develop an endless grain in the rings, in the direction of the circumference (68). 465. Wrought iron may be formed into rings without seams parallel to the bore, by Ames's process (128) flattening a mass under the hammer, and then punching or boring a hole in it. Rings (tires) are made without welds, by Mr. Krupp, by boring holes in the ends of a bar (Fig. 184:), slotting between these holes, arid then opening out the sides. Mr. Bessemer has patented* a plan of making hoops flattening low steel masses into large washers, and then boring or punching them. The material thus treated would be very sound, and the grain would run both radially and circumferential^ ; that is to say, the crystals would be upset into laminae instead of being drawn into fibres. Or Mr. Ames's rings Krupp s me- thod of ma- could be rolled in the tire-machine so as to develop an rings. endless circular grain. Again, very short Armstrong coils could be welded together by Hitchcock's pro- cess, thus avoiding the embarrassments of Armstrong's present process. SECTION IY. STEEL. 466. HIGH AND Low STEEL. By high steel is meant that which contains a large amount of carbon, and a consequently low * Jan. 26, 1861. STEEL. 389 specific gravity. Its distinguishing properties are extreme ulti- mate tenacity, hardness, and capability of extension without per- manent change of figure ; but its extensibility beyond the elastic limit is small, and it is therefore brittle under concussion. It will harden when heated and immersed in water ; it is with difficulty welded, because it deteriorates under high heat, and because its welding heat is so very near its melting point ; and it is melted at a low temperature as compared with wrought iron. Its obvious defect for guns is its brittleness ; but if so large a mass is used that its elastic limit will never be exceeded, or if it is jacketed with a less extensible metal (320), this defect is remedied or modified. Low steely however, is a more suitable metal for cannon, according to present tests. Low steel, also called " mild steel," " soft steel," " homogeneous metal," and " homogeneous iron," contains less carbon, and has a higher specific gravity ; it can be welded without difficulty, although overheating deteriorates it, and it more nearly resembles wrought iron in all its properties, although it has much greater hardness and ultimate tenacity, and a lower range of ductility, depending on its proportion of carbon. It has less extensibility within the elastic limit than high steel, but greater extensibility beyond it ; that is to say, greater ductility. The grand advantage of low steel over wrought iron, for nearly all purposes, is, that it can be melted at a practicable heat and run into large masses; thus avoiding the serious defect of wrought iron in large masses want of soundness and homogeneity. Its other important advantages for cannon are, greater elasticity, tenacity, and hardness. 467. ELASTICITY AND DUCTILITY. Mr. Anderson, Sir Wil- liam Armstrong, Mr. Mallet, and others, complain, in various public statements, that most of the steel they have experimented with for guns is too brittle that it gives way under sudden strains, which wrought iron will stand. Hence steel, especially high steel, has been condemned as a cannon-metal. In answering this objection, let us briefly review what has been said under the head of " Ductility" (344). Suppose two thin tubes 390 ORDNANCE. of equal size, one of high steel, and the other of wrought iron, to be subjected to the violent and sudden strains of gunpowder. The elastic limit of the steel is overcome, and it soon breaks, because it has but a small reserve of ductility to draw upon, to eke out its integrity. The elastic limit of the wrought-iron tube is overcome much sooner, but it has an immense capital of ductility to expend, and so it stretches and stretches for a long time without fracture. ]STow suppose the quantity thickness of steel to be increased just so much that the pressure proof charges, for instance will never overcome its elastic limit, that is to say, so that its particles will return to their original position after the pressure ceases. Its original resistance to the nexfc strain is then unimpaired, and there is no evidence that it will ever become impaired ; for elasticity is simply the antagonism between two tireless and changeless forces repulsion by heat, and the attraction of cohesion. But in order to bear the same pressure (and the demand is for the highest possible pressure of powder), the iron, equally increased in quantity, will stretch beyond its elastic limit, and therefore must depend upon a new arrangement of particles and a new limit of elasticity, for continued cohesion. Its great ductility allows this rearrangement to continue for some time ; but although it may stretch to a less distance at each renewed application of the pres- sure, its ability to stretch and its range of elasticity are constantly diminishing, until it at last arrives at a point where it can stretch no further without fracture. It has exhausted its reserved duc- tility. If it were not so, iron would never be broken at all by stretching. In addition to this, although a given area of stretched iron may sustain more than the same area of the original metal, the total area is constantly diminishing. It is, to a great extent, a substitution of a little strong iron for much weak iron. In order to endure as long as the steel, the iron must be still greater in quantity, because the " work done" to raise it to its limit of elas- ticity is less than that required to raise steel to its limit of elas- ticity (349, 352, 353). 468. This explains the failure, after short service, of thin tubes made of the moderately high steel heretofore used, while thin STEEL. 391 iron tubes appear to be unimpaired by elongation, although they certainly are impaired from another cause compression. It is simply a question of excess of rnetal and, practically, endless endu- rance, on the one hand, and ultimate failure on the other hand. The serious mistake in the use of the steel heretofore obtained, for extreme charges of powder, appears to have arisen from the neglect of the whole subject of the elastic and the ductile limits. Because the ultimate strength of steel was higher than that of iron, the quantity of the material has been proportionately reduced, when its quantity should have been proportioned to the work done in overcoming its resistance to extension. If steel, or any metal requiring the highest attainable effort of force in motion to stretch it within its elastic limit, could also be made to have a great range of ductility beyond it, the safest and most perfect cannon-metal would be obtained. But unfortunately, as the one property increases, the other decreases. (Table 69.) Low steel, the amounts of metal being the same in each case, would stand more pressure than iron within the elastic range, and would stand sudden strains longer than high steel ; but its elastic limit once exceeded, from any cause, it would fail sooner than wrought iron. As a compromise between high steel and wrought iron, it has this advantage : that a small increase of weight of ma- terial will bear a considerable increase of pressure, within the limits of safety. 469. But according to Mr. Kirkaldy's experiments,* the lower steels have a considerable degree of extensibility before fracture, (Table 66), and so much tenacity that the work done in stretch- ing them to rupture actually exceeds that required to rupture the best wrought iron. In the table, several of the best specimens of both iron and steel mentioned by Mr. ELirkaldy, are compared in this regard. The average of the steel not specially treated, is higher than that of the iron. * It is to be regretted that Mr. Kirkaldy has not given the limit of elasticity ; so that we cannot form a diagram like that given by Mr. Mallet (Fig. 160), to show where the elasticity ends and the ductility begins. Were this done, both the iron and the steel would show much more work done before rupture. The result would probably be slightly favorable to the iron, as far as ductility is concerned. 392 ORDNANCE. TABLE LXYI. THE "WORK DONE" IN STRETCHING TO RUPTURE, SEVERAL OP THE BEST SPECIMENS OF IRON AND STEEL, AS TESTED BY KIRKALDY. Names of Makers or Works. Condition and Treatment. Breaking. Work done in Ibs. lift- ed 1 foot in stretching o rupture a bar 1 foot on g and 1 in. square. Ext'n Strain. IRON. Bar .249 1645 1379 1571 .033 18 07 10 22 .1673 1964 60364 62544 55546 58534 215400 112750 121711 125978 86166 94838 79937 7315 " 5*44 3830 4098 , 3554 10147 4260 6298 9038 7933 7850 . Average 5076 - 7056 Farnley Plate Do Bradley Do CAST STEEL. Highly heated and ) cooled in oil J Low heat, cooled in ~) tallow / do do Cooled in ashes do. do Cooled slowly Shortridge & Howell's Ho- mogeneous Metal Highly heated, cooled ~l slowly J Krupp'sBolt Steel Moss & Gamble Soft Plates, soft 47O. Mr. Anderson concludes, from experiments upon Krupp's steel, as follows :* " This material is so soft as to admit of being flattened down to any extent ; indeed, the same remark applies to most of the good qualities of steel which are under 40000 Ibs. ; they continually yield more and more by the increase of pressure, and the structure of the steel shows a wonderful adaptation for keeping together without cracking at the edges, unlike almost any of the other descriptions of material. This property is greatly in its favor, both for guns and armor-plates ; and if it could be made to resist * Jour. Royal U. Service Institution, Aug., 1862. STEEL. 393 a sudden shock as well as it does the effect of mere pressure, it would be exceedingly valuable." 471. It will, however, be said that steel armor-plates do not practically resist shot as well as iron armor-plates, and that " work done," as computed in this table, and in the tables of Mr. Mallet, is not a correct measure of the effect of a sudden blow (346). To which it may be answered : First. Steel plates are cer- tainly cracked and fractured for some distance around the point of impact, by shot that only locally bulge, indent, and mutilate iron plates. But this does not prove a difference in the work done. The tenacity of the steel is sufficient to distribute the blow to overcome the inertia of the surrounding parts and its hard- ness prevents much expenditure of power in local indentation. The iron yields very much more at the point struck, because it is not hard enough to resist indentation, nor tenacious enough to overcome the inertia of the surrounding metal. The damage. to the steel, considered as an armor-plate, however, is much the greater, because it is rendered more liable to be thrown off. The iron, considered as an armor-plate, is not materially injured, if it is not actually punched. Second. There is no evidence that the armor-plates tried had the same relation of tenacity and ductility as the steel and iron speci- mens tested by Mr. Kirkaldy. It is known, on the contrary, that the Bessemer and other plates tried, were not sufficiently worked. The Mersey puddled steel plates failed ; but Table 68 shows them to have much less ductility than iron. Third. The pressure in a cannon is not exerted upon one point, but over the whole inner surface of a cylinder. Fourth. The blow of a cannon-shot is obviously very different from the blow of a perfectly elastic gas, lighter than air. Fifth. The actual extension of some of the steel specimens was greater than that of some of the iron specimens, not to speak of the greater resistance to that extension. So that the rule of " work done" is equally applicable to steel and to iron. 472. Mr. Mallet, in one of his tables,* gives " Tr. value for * " On the Construction of Artillery." Table on page Y9. 394 ORDNANCE. unit of length and section" for "cast-steel (German), soft," at 103-500, and for " wrought-iron bar (maximum ductility)," at 96-000. The ductility of Messrs. Naylor, Tickers & Go's, steel, and of low steel as compared with high steel, is shown by Tables 68 and 69. The extreme ductility of the Bessemer low steel was shown by various specimens in the Great Exhibition of 1862. The London Engineer* says of one them a rail that it was " twisted cold into a spiral like a ribbon, and does not show a single flaw after this severe treatment. All idea of the c brittleness of steel' van- ishes with the inspection of this example." The same authority says of other specimens : " There are also some close bends of rails, one of which is deserving special notice. Mr. Kamsbottom, the able engineer of the railway works at Crewe, had this piece taken up while covered with sharp frost and placed under the large steam-hammer, when it stood the blows necessary to double both ends together, without showing the smallest indication of fracture. * * * There are also some extraordinary examples of the toughness of the Bessemer steel, made from British coke pig-iron, among which may be enumerated two deep vessels of 1 foot in diameter, with flattened bottoms and vertical sides. At the top edge, one of them is | in. and the other \ in. in thickness. * * * A 4-in. square bar has been so twisted, while hot, that its angles have approached within less than half an inch of each other, so that what was originally 1 ft. length of surface, has now become 26 feet, while the central portion of the bar still preserves its original length of 1 foot."f 473. STEEL HOOPS. Elasticity is an indispensable quality in hoops, especially when the inner barrel is of cast iron or a slightly ductile metal. If hoops change their figure permanently, their * May 2, 1862. f The author is aware, from personal inspection and measurement, that the speci- mens are correctly described, although he did not see them put into these shapes. From tests that he has seen and made, however, at Mr. Bessemer's works in Sheffield, he does not believe that the excellence of the steel is overstated by the editor of the Engineer. STEEL. 395 usefulness is in a great degree destroyed. With the high charges necessary to punch the best armor, wrought iron is likely to fail in this particular (445). For a given elongation without perma- nent change of figure, high steel requires more " work done" than any other metal (Fig. 160). But the substitution of very low steel for wrought iron involves another important principle. The want of homogeneity the numerous strata of impurities and planes of weakness introduced into wrought iron, especially in large masses, all the way from the puddle-ball to the finished gun, have already been explained (413 to 416). Its grand defect, by the present processes of manufacture, is imperfect welds. The casting of low steel into masses of any size overcomes this whole difficulty. 474. COST ; WEIGHT ; QUALITY. By the present processes, excepting Bessemer's (486), although the number of operations is reduced, by casting steel in large masses, its cost, as compared with that of wrought iron, is somewhat increased. (Table 27.) Still, it compares favorably, considering its greater strength. The present causes of the costliness of steel are principally these : Melting the metal is expensive. Such a high temperature is required, that the pots for very low steel only stand one or two meltings. The subsequent heating of immense ingots (one of Krupp's, in the Great Exhibition, was 44 inches in diameter and 8 feet long) requires time and skill ; drawing them under ordinary hammers, not to speak of its injurious effects (419, 421), is a very long operation. The careful preparation and selection of the ma- terial adds considerably to the cost. Again, the business is now monopolized by a few manufacturers. Standard qualities of low steel bring a price much more dispro- portionate than that of wrought iron, to the cost of production. Some of the processes are secret others are covered by patents ; but the chief difficulty is, that very few establishments, out of the whole number, have undertaken the manufacture. The remedy is fast developing itself, especially in England. Many of the large British establishments have introduced the Bessemer process. In this country, several iron-masters, to-day, pronounce this process a 396 ORDNANCE. failure, and propose to stick to puddling and piling. At the same time, others are doing all they can to develop this and similar improvements (490), but are indifferently encouraged. There is no doubt, however, that within a few years low steel will be produced at a cheap rate all over the world. The great increase in the use of Kmpp's, and of the Bochum Prussian steel, and of Nay lor, Yickers & Go's, equally good cast steel, and of the steel of Firth, Howell, and other English makers, and, above all, the wonderful success and spread of the Bessemer process, in Eng- land, France, Prussia, Belgium, Sweden, and even in India all within three or four years, prove that great talent and capital are already concentrated on this subject, and promise the most favor- able results. The processes are certainly dissimilar ; but that only shows the determination to find the right way, and indicates the increasing demand for the right product. It has already been remarked that the advantage of steel over iron in its more crude forms is, that the number and quantity of its ingredients are better known at each stage of its refinement. Then, the growing improvements in treating steel, after it is produced, promise further reduction in the cost of manufactured articles. In an establishment about to be erected in London, and another in Staffordshire, for the production of Bessemer metal, 50-ton hammers will be used. Messrs. John Brown & Co., of Sheffield, have recently erected a 40-ton hammer and two 10-ton Bessemer converting-vessels, for the manufacture of steel cannon ; and it is said that Mr. Krupp's 40-ton hammer is to be rivalled in his own works. In some of the larger establishments, hydraulic presses are to be substituted for hammers; and other heavy machinery, for working large masses, is rapidly coming into use. The largest cast-steel ingot ever made, up to 1851, was sent by Mr. Krupp to the Great Exhibition of that year; it weighed 4500 Ibs. One of his ingots, in the Exhi- bition of 1862, weighed 44800 Ibs. about ten times as much. Meanwhile, wrought iron must be puddled and piled. The means of improving and cheapening its manufacture do not seem to be capable of much further development. STEEL. 397 The secret of the whole matter is this : The New Treatment of iron is based on chemical laws. The old treatment was a matter of tradition, trial, failure, and guess-work. The Bessemer process is a chemical process suggested by the study of chemical laws, conducted on chemical principles, and prosecuted, modified, and improved, according to the results of chemical analyses. The old process was suggested by accident, is liable to be disorganized by accidental and unexpected causes, and has been brought to the present, which is perhaps the ultimate degree of perfection, after generations of groping in the dark. Instead of first finding the right course, and then pursuing it, every course has been taken, or an old and wrong course has been persisted in. There is noth- ing but blundering into truth in its whole history, if we except the part of Henry Cort. Now that this method of proceeding is likely to be superseded, we may look for rapid improvement. v 47o. But it is said that the new products are not always uni- form and trustworthy. Mr. Anderson remarks :* " Cast steel is the most expensive of all cannon-metals, yet, from its soundness in the bore, if it could be made as trustworthy as wrought iron, and if, at the same time, it could be depended upon for the certain possession of toughness, it would be perfec- tion, notwithstanding the cost ; but the uncertainty of manufac- ture which now exists must first be completely removed before it can be compared with wrought iron as an instrument for men to fire and stand alongside with perfect assurance of safety ; and, as wrought iron is so reliable and the cost moderate, there is no par- ticular want felt for steel to constitute the entire body of the gun." It is, however, due to Mr. Anderson and to the subject to say, that in his more recent practice at Woolwich, steel hardened in oil has quite superseded wrought iron, especially coils, as a material for the inner barrels of guns. Indeed, Mr. Anderson admits in the same lecture, speaking of the 8-inch Krupp gun tested at Woolwich (138), that u such a mass of homogeneous steel, after having been cast into an ingot, all its impurities floated to * Journal of the United Service Institution, August, 1862. 398 ORDNANCE. the surface, then well worked under the hammer, and afterwards properly annealed, has a degree of perfection in the bore, in regard to entire freedom from specks, seams, or flaws, superior to any wrought-iron structure, coiled or forged ; and some remarkably fine guns have been constructed with such steel linings, having the main structure of the gun built up with wrought-iron hoops, to give the requisite strength to the steel lining. Such a combi- nation gives the perfect bore and the strong gun, but there is not yet sufficient experience to enable me to assert positively, that the steel will not give way under long-continued firing." The failure of steel, as used in guns, has already been accounted for, and the remedy specified (467 and 468). Other authorities* do not entertain so high an opinion of the trustworthiness of wrought iron as not to particularly want something better. Of course, new things will be avoided as long as possible, by old practition- ers, as a rule. The steam-engine, the war-steamer, the rifled can- non, the iron-clad all had to fight their way into notice and adoption. But, even when men are willing to adopt an improve- ment, they are apt to be over-cautious and too easily frightened. *In the discussion before referred to, in the Institution of Civil Engineers, on "The National Defences," 1861, after Sir William Armstrong and others had talked pretty freely against steel (which is now adopted in all the new Armstrong guns for inner tubes, because wrought iron fails), Mr. Bidder, president, said: "Sir William had expressed an entire want of confidence in homogeneous iron. The president could not concur in that view ; he did not think that, at present, they would be justified in saying that homogeneous iron had ever yet had a fair trial and had been found wanting. He had received a letter from Mr. Krupp, of Essen, accom- panied by a communication from Colonel Petiet, of the Artillery Commission of France, stating, as the results of his experience with 12-pouuder guns, constructed of homo- geneous iron, that they had been completely successful. Mr. Krupp stated that, in Prussia, they had made guns of 8-inches bore, which had successfully resisted all the proofs to which they had been submitted. There could be no doubt that, in this country, there had been some disappointment attending the manufacture of guns of large calibre, of homogeneous iron. This, however, might be fairly attributed to the mode of manufacture. The machinery for working the iron in the large masses neces- sary for guns, was not suitable for the purpose ; and, until hammers of thirty or forty tons were applied, it would not be fair to pronounce the condemnation of homoge- neous iron as a material for artillery; indeed, they were not justified in rejecting homo- geneous iron for guns, until the same experience had been gained, and the same attention had been bestowed upon that metal, as had been given, under Sir William Armstrong's superintendence, to his own peculiar mode of construction." STEEL. 399 If they would devote the same energy in trying to perfect and develop steel, for instance, that they now expended in trying to get more out of wrought iron than there is in it, there would be less cause of complaint. Besides, a perfect result cannot be at once expected from a new manufacture, however well founded its principles may be. 476, STRENGTH. (See Tables 67, 68, and 69). The strength of the low steel, adapted to gun-making, averages about 90000 Ibs., or three times that of. cast gun-iron, and 50 per cent, more than that of the best wrought iron. Kirkaldy's summary of results for the lower steels will be found in Table 67. The strength of Krupp's steel, according to the report of the Prussian Minister of War, as quoted by Mallet, is 107516 to 117212 Ibs. In Mr. Krupp's gun-circular (134 note), it is taken at 120000 Ibs. The strength of the lowest and softest Bessemer steel is 72000 Ibs. per square inch. That of the highest Bessemer tool-steel (remelted in crucibles and drawn under the hammer) is 170000 Ibs. That of the average metal is about 90000 Ibs. Plates tested at Woolwich are said to have endured 68314 to 73166 Ibs. Messrs. Comings & Winslow's (American) puddled steel, of the highest quality, averages about 90000 Ibs. tensile strength. High steel, hardened in oil, was found by Mr. Kirkaldy to have a tenacity of 215400 Ibs. 477. UNIFORMITY. Want of uniformity is, in one sense, fairly urged against steel, when certain qualities, supposed to be uni- form, are less so than certain qualities of wrought iron. But, to condemn steel, as some authorities seriously do, because it ranges all the way from 50000 to 200000 Ibs. tensile strength, is as absurd as it would be to condemn timber, because it ranges all 7 O the way from 6000 Ibs. (cypress) to 23000 (lancewood), tensile strength. The causes of improvement already considered pro- ceeding in accordance with chemical laws, instead of groping among traditions and expedients, liable at any time to acci- dental confusion are certain to lead also to uniformity in the product. 400 ORDNANCE. TABLE LXVII. TENSILE STRENGTH OF Low STEEL. KIRKALDY. Names of the Makers, or "Works. Condition. Breaking weight per square inch of original area. Lowest. Highest Mean. Krupp's Steel for Bolts Bars. Rolled. Rolled. Forged. Forged. Rolled. Forged. ' Forged. Plates Lengthwise. In. thick, A * ft and ft ft and ft i * 86054 82218 84794 67065 55006 42564 45931 85650 76772 67977 92676 95946 67184 96208 99570 94752 75304 57U4 71501 734i 108900 87972 81588 108906 1061 10 86908 92015 90647 89724 71486 70168 6 5 2 55 62769 96280 81719 75594 101450 102593 77046 Shortridge & Co.'s Homogeneous Metal Ditto ditto Mersey Co 's Puddled Steel Bloc h aim ditto Ditto ditto Shortridge & Co.'s Cast Steel Naylor, Vickers & Co 's ditto Morse & Ganables's ditto Mersey Co.'s Puddled Ditto ditto Hard Ditto ditto Mild But, according to Mr. Kirkaldy's late experiments,* steel com- pares very favorably with iron, as to uniformity of strength, and of ultimate elongation. The table (68) is compiled from the tables of Mr. Kirkaldy. 478. SHAPE. What has been said, under this head, of wrought iron (409), applies also to steel. 4:79. TEMPER. The specific gravity of steel has been found to affect the qualities we have considered tenacity, elasticity, * "Experiments on Wrought Iron and Steel," 1862. STEEL. 401 TABLE LXYIII. THE UNIFORMITY AND EXTENSIBILITY OF WROUGHT IRON AND STEEL COMPARED. Names of the Makers, or Works. Description. Breaking weight per square inch of original area. Percentage of Elongation before fracture. Highest. Lowest. Highest. Lowest. IBON BAKS. tolled I in. square. Rolled i in. round. Rolled i in. and f- in. round. Rolled f to i-J-in. round. Plates lengthwise). Bars. Armor- Plate and crank shaft. Bars Bars. Rolled and forged bars Plates (lengthwise) Do. Do. Do. Highly heat- ed and | 6z6 35 J, 65701 [63604 j 59820 1 64544 62429 U45 6 ' 148229 99570 }-7S"4 J953 6 87972 81588 108900 I82i66 108906 106110 86908 106394 58228 58687 54575 53266 5'54i 45611 32528 112224 82218 4593 1 92858 81588 67977 85650 24.9 26-0 30-2 23-8 14-5 II 'I 20-5 7-1 18-0 "3 * 9 .6 4 17-32 19-82 8-93 22 00 20.5 24.4 22-2 17-3 10-85 6-3 6.4 5.2 ii. 9 9-1 5'7i 17.50 19-64 8.61 \ Bowling < J. Bradley & Co J Govan Ex B. Best -1 Dundyvan (Common) Heavy Forgings < STEEL. Turton's and Jowitt's Cast Steel ~) for Tools / Krupp's Steel for Bolts, and 1 Howell's Homogeneous Metal.. / Blochairn Puddled -< Turton's Cast Steel < Naylor, Vickers & Co.'s Cast Steel- Moss & Gamble's Cast Steel Shortridge, Howell & Co.'s Homo- \ Ditto ditto -J Mersey Puddled (Ship Plates) Ditto " Hard" 92676 95946 67184 93327 Do. Average. 2-79 4.86 6-16 3.60 Ditto "Mild" Do. Blochairn ditto 26 * Average, crosswise and lengthwise. 402 ORDNANCE. and ductility very materially. It may be stated, generally, as follows : 1. High steel has a low specific gravity. 2. Low steel has a high specific gravity. 3. Decreasing specific gravity increases tenacity. 4. Decreasing specific gravity increases the capability of elon- gation within the elastic limit. 5. Decreasing specific gravity diminishes the capability of elon- gation between the limit of elasticity and the point of rupture. The 1st, 2d, 3d, and 5th propositions, are proved by the experi- ments of Mr. T. E. Vickers (of Naylor, Tickers & Co., Sheffield). The soft, mild steel (Table 69), which stood 17 blows of the drop, and bent 58}f inches, endured but 30f tons tensile pull, and had a specific gravity of 7*871. The high, hard steel, which stood but 10 blows, and bent only 6}| inches, endured 69 tons tensile pull, and had a specific gravity of 7*823. Table 70, compiled from Mr. Kirkaldy's experiments, shows the remarkable gain in ultimate tenacity by decreasing the spe- cific gravity of steel in another way hardening in oil.* At the same time, the "work done" in overcoming this tenacity, is less than for the same steel cooled slowly, because its elongation before rupture is so much less. * The process of hardening steel In oil, as practised at "Woolwich, has been de- scribed (35). The following is the provisional specification of Mr. George "W. Rendel (one of the Elswick Ordnance Co.), dated November 13th, 1863, which sufficiently describes the very simple process : " I, GrEORGE WiGHTWiCK RENDEL, Newcastle-on-Tyne, in the County of Nor- thumberland, Civil Engineer, do hereby declare the nature of the said invention for 1 An Improved Method of Strengthening and Hardening Cannon made wholly or par- tially of Carbonized Iron or Steel, or the Barrels, or other parts thereof,' to be as follows: " I bring the cannon or parts of cannon to a suitable heat in an oven, or any con- venient furnace, and I then plunge them into a bath of oil or other liquid ; or instead of plunging the cannon or parts of cannon, I pour the liquid over them and to keep down the temperature of the liquid, which is raised in the act of cooling the cannon or parts thereof, I employ pipes winding through the liquid, in which pipes a current of cold water circulates, or the liquid may be cooled by any other suitable arrange- ment ; but any arrangement for cooling is not essential to the process of strengthen- ing, being only a matter of convenience, as having the effect of reducing the volume of liquid necessary for cooling large masses of metal" STEEL. 403 TABLE LXIX. SHOWING THAT DECREASING THE SPECIFIC GRAVITY OP STEEL IN- CREASES ITS ULTIMATE TENACITY, AND DIMINISHES ITS DUCTILITY. (Compiled from the Experiments of T. E. Vickers, Esq.) NOTE. The material, in the form of an axle of 3f| in. diameter, was laid on bear- ings 3 feet apart, and subjected to the blows of a drop weighing 1547 Ibs., falling 1, 2, 3, 4, 5, 7, 10, 12|, 15, 20, 25, 30, and 36 feet, up to the 13th blow, and 36 feet at the remaining blows. The material subjected to tensile test was a bar 14 in. long and 1- in. m diameter Specific Gravity. No. of Blows endured. Total Bend under Blows. Elongation before breaking. Ultimate Tenacity per square in. Ins. Ins. Tons. 7.871 17 5811 If 3t 7-867 18 56-iV 'I 34 7.855 18 53i% li 37i 7-855 15 35^6 4 4* 7.852 16 38ii II 44 7.848* 18 46 I 45 7.847 16 4A H 45i 7-840 10 61% i 55 7.836 8 4ft i 60 7.823 10 6|f 1 69 *This is considered the proper temper for cannon. Neither of these experimenters has determined the amount of elongation within the elastic limit, nor the " work done" to reach it ; but we know from experiments, and practice generally, that the higher the steel, the greater the safe elongation, and the greater the power required to produce that elongation. Hardening steel in water or in oil, or by cold hammering, de- creases its specific gravity, by combining the free carbon chemi- cally, and so fixes the crystals of steel in their expanded state. Annealing steel increases its specific gravity ; a part of the carbon is set free, and the crystals are allowed to assume their closest and natural form. 404 ORDNANCE. TABLE LXX. SHOWING THE EFFECTS OP TREATMENT ON STEEL. Names of the Maker or Works. How treated. Breaking weight )er square inch. Elongation per cent. ' Jowitt's Cast Steeel for Chisels, Highly heated and cooled "1 in oil, / 215400 3-3 r Do. do. do. Do. do. cooled in "I water, / 90094 Do. do. do. Do. do. cooled in ") ashes, slowly, / 121716 7 o K f Bessemer's do. Tools, 1 * [_ Do. do. do. Heated and cooled in oil, Do. do. slowly, 211072 123165 I 5-9 r Shortridge & Howell's Homoge- Ineous Metal, Highly heated, cooled in oil, 130237 2-5 5 - Do. do. do. Do. do. do. water, 66953 oo Do. do. do. Do. do. do. slowly, 82166 22-O The proper temper of steel for guns may be generally deter- mined on these principles, although more careful and comprehen- sive experiments and analyses are of the highest importance, and should be undertaken by governments, if not by steel and gun makers, for the purpose of avoiding uncertainty and occa- sional or partial failure. 48 O. RESISTANCE TO COMPRESSION AND WEAR. The superi- ority of steel in this regard hardness is too evident to require comment. Mr. Anderson, and authorities generally, pronounce even the low steels to be quite satisfactory. Considering the fric- tion of rifled projectiles, and the enormous pressure that modern guns are required to stand, this is by no means an unimportant quality. The permanent indentation of the chambers of the Armstrong and other wrought-iron guns, by the pressure of the powder-gas, is admitted by Sir William Armstrong and Mr. An- derson (402. Tables 71 and 72). 481. In another particular steel has a great advantage over wrought iron. A piece of cast steel, that has been immersed for a time in acid, will be found to present a smooth surface. A thin STEEL. 405 TABLE LXXI. HARDNESS OP CANNON-METALS. Major Wade. 1856. Metal. Hardness. f Least 4. r7 Cast Iron (^ Greatest I'). CI f Least IO-AC \Vrought Iron 1 Greatest 14 14. ("Least 4-57 ( Greatest r .04, TABLE LXXII. YAEIODS QUALITIES OP CANNON-METAL. (Compiled from the Tables of Mr. Mallet" Construction of Artillery.") Metal. Ultimate tenacity. Relative hardness. Relative resistance to abrasion. Te.-Value for amt. of length and section. Dynams. Tr.-Value for amt. of length and section. Bronze, mean C (ft 5. .joS Cast Iron . 5 \ { ) 10 (ft * w *3 305 93*5 Z 5 Wrought Iron, Maxi- mum Ductility 9341 643*3 10 {() o29. The wrought-iron Lancaster gun, recently making at Woolwich for trial, wdth other 7-inch guns rifled on different plans, has a major axis of 7'6 and a minor axis of 7 inches. J&O. HADDAN. Mr. Haddan's plan of centering against the bore is illustrated by Figs. 212 to 214. The rifling consists of 3 large and shallow ellipti- cal grooves, which in the earlier forms were about j in. deep and took away nearly two-thirds of the surface of the bore. In the competitive trials of 1861, Mr. Haddan's grooves were 0*15 in. deep, and 3 '4 in. wide. The twist was 1 turn in 25 feet. The projectile is rotated by 3 wings formed upon the front of the shot, straight with its axis. In the earlier projectiles (Fig. 214) the rear tapered, and had a shoulder for the ring-wad a a to stop the windage. The later projectiles have merely a wooden sabot. As the wings are on the front part of the projectile, the rifling is carried only to within one calibre of the powder-chamber, and hence is not a source of weakness at that point. The projectile (Fig. 213) for a 32-pounder bore, as used in the trial of 1861, was 11*95 in. long, and 6'20 in. in diameter; w r eight, 51 Ibs. ; diameter of powder-chamber, 4 in. ; bursting charge, 3 Ibs. 6 oz. ; charge, 7 Ibs. from a cast-iron gun (592). o31. WIIITWOKTII. Mr. Whitworth's system of rifling (Figs. 215 to 219) is known, in the smaller ordnance, as the hexagonal system. A larger number of sides have been experimented with in various ways (664). Fig. 219 is a full-sized section of part of a Haddan's rifling. RIFLING AND PROJECTILES. 443 Whitworth bore and 70-pounder projectile, showing that what is called a "flat" of the gun is not a plane surface, but a double FIG. 213. Haddan's projectile. incline with the apex inward. This formation facilitates loading, but its principal and very important use is to give the shot so much FIG. 214. Haddan's projectile for wood sabot. bearing that it will not cut into the gun. A hexagonal bolt re- volved on its axis within a slightly larger hexagonal orifice, would not bear upon its sides, but only upon its six corners. The points of contact would be mere lines. The bore must be slightly larger than the projectile, to allow easy loading when the gun is 444 ORDNANCE. FIG. 215. foul.* In Fig. 219, while the face a e of the shot is flat, the face d e of the gun is so inclined that the shot, in coming out, will bear upon the whole of it, as shown. If the face a e of the bore was also plain, the shot would bear only on the corners 6, J, &c. The gaining twist is obviously im- practicable with this form of rifling. *>&. The projectile is first turned truly cylindrical ; its flats are then planed by a special ma- chine-tool, at the cost, for the 12- prs., of 10 cents per dozen ; this is to be reduced to 6 cents.f For range, Mr. "Whitworth uses a projectile 3 calibres in di- ameter ; for punching, a shorter shot, to save weight, and thus secure a high velocity. FIG. 216. "Whitworth's rifling. Whitworth' s short round-fronted shot. The cartridge for the breech-loader is made of tinned iron, shaped to fit the rifled bore ; the powder is retained in it by the * In his patent of April 23, 1855, for projectiles, Mr. Whitworth specifies that they are cut so as to exactly fit the bore of the gun. f The value of the self-acting machinery for shaping the rifled-cannon projectiles, would be about 500, to enable a workman to produce the shot at such a rate, as that the cost should not exceed one penny per shot, for wages only. Mr. Whitworth, " Construction of Artillery" Inst, Civil Engineers, 1860. RIFLING AND PROJECTILES. 445 FIG. 217. Whit worth's long round- fronted shot. lubricating wad, which is placed in the open end. This wad is composed of wax and tallow, and when the explosion takes place it is melted and driven through the gun, lubricating the bore so thoroughly that, with a good quality of powder, the gun may be fired for a long time without sponging. 533. The Whitworth shell, fired with 25 Ibs. powder through the Warrior target at 800 yards, Sept. 25, 1862, was 17 inches long, 6'tt in. across the flats, and 7 in. across the corners. It weighed 130 Ibs. and held a bursting charge of 3 Ibs. 8 oz. The shell fired with 27 Ibs. of powder, through the Minotaur 5^-inch plate, and burst in the backing of the target, at 800 yards range, Nov. 13th, 1862, was 20^ in. long, 6*4 in. across the flats, and 7 in. across the corners. It weighed 151 Ibs. and held a 5-lb. bursting charge. The 70-lb. FIG. 219. FIG. 218. Whitworth's flat-fronted projectile. Full-sized section of Whitworth's 70-lb. shot and rifling. cast-iron shell is 15f in. long, 5 in. in diameter in the middle, 4 in. at the rear, and If in. at the front. Its thickness, in the middle, is 1 in. The powder-chamber is 12 in. long, and 3 in. in diameter. 446 ORDNANCE. TABLE LXXVII. EXPERIMENTAL PRACTICE. WHITWORTH BREECH-LOADING BO-POUNDER. SOUTHPORT, JULY 25 AND 26, 1860. Weight of gun 80 cwt 20 Ibs. Length io feet. Diameter of bore 5 in. and 5 4in. No. of grooves 6. Twist .... I turn in 8 ft. 4 in Charge ia Ibs. Axis of gun above plane 3 ft. Gun mounted on heavy ship-car- riage} platform partly horizon- tal and partly inclined I in 6. No difficulty in loading. No escape of gas perceptible. No. of rounds fired. Eleva- tion. Recoil, average. Projectile. Greatest time of flight. Least time of flight. Mean range, 1st graze. Mean deflection. Left. Mean deflection. Right. Nature. Weight. degrees. in. Ibs. seconds. seconds. yards. feet. feet. 5 I 101 shot 70 ft- i-6 760 2-6 5 I 104-6 shell 55 2-25 1.9 967 2 3 5 2 133-5 shot 70 3-75 3' 1297 I I S 2 116-4 shell 55 3*75 3' 1494 5 4.2 5 3 IIO-2 shot 70 4-6 4- 1786 2-4 3-4 TABLE LXXVIII. RANGES or WHITWORTH RIFLED GUNS.* Weight of pro- jectile. Diam. across the flats. Length of barrel. Twist 1 turn in inches. Charge of powder. Initial velocity. Number of revolutions per second. Elevation. Actual range. Parabolic range. Ibs. in. in. ft. per sec. degrees. feet. feet. 3 4707 555 JO 12567 18300 3 i.i 7Z 40 8 oz. 1300 400 - 20 20970 34500 35 28740 49200 [ 2 375 6 3780 12 Si 93 60 28 oz. 1300 260 -j 5 6960 9210 1 10 -739 18300 f 5 7722 9200 80 5 118 100 12 Ibs. 1300 .56 -j 7 10476 12900 [ 10 13665 18300 Construction of Artillery," Inst. Civil Engineers, 1860. RIFLING AND PROJECTILES. 447 534. The particulars and charges of the Whitworth guns and projectiles have been given in Table 8. The practice for range and accuracy is given in Tables 77, 78, and 81. A competitive trial of Armstrong and Whitworth 12-pounders and 70-pounders is now in progress. In Mr. Whit worth's guns for this trial, the outer bear- ing edges of the rifling have been so modified as to more nearly resemble 6 rounded grooves.* 535. SCOTT. The " centrical" system of Commander Scott, FIG. 220. FiO. 221. Scott's rifling. illustrated by Figs. 220 to 223, was laid before the British War Department in 1849. " The rifling is called ' centrical' from the * No official report has been made as to the trials lately in progress, at Shoeburyness, of the 12-pounder and 70-pounder Whitworth muzzle-loading guns, and the Armstrong breech-loading and shunt 12-pounder and 70-pounder guns. The Army and Navy Gazette of April 9th, 1864, states that up to 900 yards range the Whitworth 12-pounder had a slight advantage in range, and that it put every shot into a bull's eye one foot in diameter, at 300 yards. At 1300 yards the Whitworth still had a slight advantage. The breech-loading Armstrong gun was inferior in all respects to the other guns. The Engineer of April 22d, 1864, says that each gun had fired 600 of the 3000 rounds assigned, and that at 1600 yards the Whitworth gun fired 10 shots with a lateral deviation of only 5 inches, but that the shots fell short or went over a wall 8|- feet high at 1100 yards. The Armstrong projectiles were more accu- rate in this particular. " The Armstrong shell shows a superiority in cutting up abat- tis or earthworks." All the guns are constructed of mild steel. The Whitworth rifling has been considerably altered from the original hexagonal form. The Armstrong shunt rifling has also been changed, and now resembles the French. The rifling of both these guns is thus on the centering system. The 70-pounders are ready for trial, but their test had not commenced. 448 ORDNANCE. peculiar mode of centering its simple iron projectile, which, in- stead of inclining towards the bottom of the bore in its' passage Fig. 222. Full-sized section Scott's rifling; projectile leaving the gun. out, is centered on its rounded bearings, without jar by the first pressure of the elastic fluid. This is effected by the peculiar curves of the shoulders of the 3 grooves (Fig. 223), which incline towards the centre of the bore, and thus form 3 rails for the projectiles to slide out upon without being compressed or strained." 586. In case of large calibres with heavy projectiles, a shallow shoulder (Figs. 221 and 222) is taken out for the Scott's groove and rib. shot to turn against in loading. 537. The following are the particulars of the rifling and shell (Fig. 224) used in a 32-pounder cast-iron gun, with 5*5 Ibs. and 6 Ibs. of powder, in the trials of 1861 : Twist, 1 in 48 ft. ; num- ber of grooves, 3 ; width 1*7 in. ; depth, O20 in. ; weight of shell 39 Ibs. ; length, 11-88 in. ; diameter, 6'28 in. ; diameter of powder- chamber, 4'42 in. ; bursting charge, 4 Ibs. 13 oz. (592.) 538. LYNALL THOMAS. Mr. Thomas's first system resembled the Hotchkiss expansion system (566). His present rifling con- sists merely in leaving three or more very narrow lands and the same number of very wide grooves in the gun. Projections are planed in the shot to correspond with the lands. At first sight, the system closely resembles Commander Scott's (535), ex- RIFLING AND PROJECTILES. 449 cept that the grooves are made in the shot and the projections in the gun. But it will be observed that Commander Scott's grooves are so rounded as to gradually lift the shot and hold it in the 224 Scott's shell. centre of the bore, and that spherical shot cannot be fired from Mr. Thomas's gun without injuring the three narrow lands, and without some very strong and cumbrous arrangement to stop the excessive windage. The lands are also in the way of loading the powder easily and rapidly. 539. A 9-in. gun, fabricated on the Armstrong plan, was tried at Shoeburyness on the 20th of November, 1863, with results given in Table Y9. Mr. Thomas attributes the comparative inaccuracy of the firing* to the stripping of the zinc bearings with which the grooves of the shot were surfaced. 04O. SAWYER. The Sawyer projectile, considerably used in the United States Army (Figs. 225 and 226), is cast with projec- tions corresponding with and slightly smaller than the grooves in the gun. Instead of being dressed, like Scott's and Whitworth's, to bear upon the lands, the whole cylindrical part of the projec- * Letter to Army and Navy Gazette, Dec. 5th, 1863. 29 450 ORDNANCE. TABLE LXXIX. RANGE AND DEFLECTION OF LYNALL THOMAS'S 9-lNCH GUN. SHOEBURYNESS, Nov. 20, 1863. Weight of shot (3 calibres), 300 Ibs. ; Charge, 40 Ibs. ; Windage, -fa in. Round. Elevation. 1st graze, yds. Deflection, yds. Eound. Elavation. 1st graze, yds. Deflection, yds. Left. Eight. Left. Eight. 2 3 4 5 6 7 8 9 10 ii 12 '3 H 15 2 H ft (( (( u 5 948 928 955 1029 999 958 928 939 971 1092 2107 1883 2073 1958 2082 1.6 . 16 17 II 19 20 21 22 2 3 24 2 5 26 2 7 28 2 9 30 5 (i a 10 s the 70-pounders now in process of conversion from breech- loaders are finished." 454 ORDNANCE. 548. The practice with the Armstrong 110-pounder rifle gives the following averages : Elevation 10 Charge 12 Ibs. Mean range (yards) 3387 Mean difference of range 61-48 Mean deflection 4-18 With 1 6 Ibs. charge, at 10, the range averages 4139 yards. 549. The projectile (Figs. 236 to 239) is of cast iron, coated with lead alloyed with tin, to harden it. This soft metal cov- ering was formerly kept in place by grooves, encircling the shot (Fig. 237). It is now soldered to the cylindrical part of the shot, which is turned smooth, by a zinc solder, invented by Mr. Bashley Britten (581). The steel shot, however, requires under- cutting; the heat of the zinc would draw its temper. In the earlier shot there was an opening, or score, near the centre, for the lead to strip into, the surfaces of the lead being otherwise nearly straight ; but, lately, tjie soft metal has been reduced in front, and the score made nearer the base ; which is now the largest part of the shot (Fig. 237). RIFLING AND PROJECTILES. 455 5oO. The segmental shell (Figs. 238 and 239) is intended to answer the purposes of the common shell, the canister-shot, and, Fia. 237. Armstrong lead-coated shot if the fuse is adjusted so as to prevent the ignition of the bursting charge, of the solid shot ; thus preventing the risk of running short of either kind of ammunition.* (717.) FIG. 238. FIG. 239. Armstrong segmental shell. . The cartridges for the Armstrong 110-pounder are shown by Figs. 240 to 242. As the cartridge must fill the powder-cham- * This shell was first patented by a Mr. Holland, in 1854. 456 ORDNANCE. RIFLING AND PROJECTILES. 457 O H tl C M I ft fi s B M M M o * Area expressing Error. OO OO NO O OO O ^ 11 C< t-. to to NO > a o3 1 M ON OO to VO c f^ o X X X X X X ^ 11 O f- M o ON NO t-^ ON oo oo co ^- *$ OO co vo TJ- NO O OO w cl OO M CO CO H I 1 *4 Area expressing Error. OQ ^ i ^ t-. o ^ M e* M ,1 TJ- oo t J o 1 T$- OO O i ^- l^- M C* CO c> in VO ,2 X X X X X X t*> OO ^ c vo fv. w oo ft ON oo ON H O ^ NO ON O OO Tf- OO CO u~i OO M WHITWORTH'S 12-pdr. B. L. No. 1. cwt. qrs. Ibs. Weight 9 8 Length 8 ft 8 in. Mean Time of Flight. o vo -^- GN O NO O to co vo ^ cj co Deflection. As referred to Mean Direction. w- oo c< <* m rt to t^ O t^ ^O OO ON ** O M n O O c As observed. OO O O ON O O co 10 T>- t~~- O ON >> M M H, M CO VO Mean diffi, of Range ,g ON oo ON t--- oo >o I Mean. OO O oo w co O * ON ON ^O t~- r O Max. i f 1 1 1 1 i Min. ^ ON O rt 10 t^. oo ^ IT JT o" ^ ^T co ARMSTRONG'S 12-pdr. B. L. No. 6. cwt. qrs. Ibs. Weight 8 2 11 Length 7 feet. Mean Time of Flight. ^ rt rt oo oo O Deflection. As referred to Mean Direction. rj- oo oo O ^- t^ * O <* ^* oo n >i ^* M M M O Cl NO As observed. i : : ti i i Mean diff. of Range f, 2 ^ S -2 3" S i Mean. O VO NO O 00 00 CO tO T- NO NO O M f< 11 CO 10 ON >*> M HI f< cl CO CO Max. O l^ to ON t^. 11 J vo O NO ON ON NO w co M co vo ON M w r cl co co Min. OO VO OO i c< NO ^ O C^ c^ co n VO ^ >i ci n co >o oo Elevation. " 3 ^ S 2 - Charge. O o o to o >n No. of Rounds. m 3 3 3 S 2 8| It m ill -S ^ 8- . u t> A 60 bO N 2 S M - to to 4) t 458 ORDNANCE. TABLE LXXXI. EXPERIMENTAL PRACTICE. ARMSTRONG BREECH-LOADING 12-PouNDER. SHOEBURYNESS, APRIL 2, 1861. Height of axis of Gun above plane, 3i feet. 'Nature, ARMSTRONG'S B. L. 12-Pdr. Gun, No. 6. cwt qrs. Ibs. Weight 8 2 11 Ordnance . Length .............. 71 feet. Diameter of Bore ____ 3 inches. Barometer, 29 '7. Wind, South 3. Direction ) of Wind, f Spiral, if rifled, 1 turn in 38 calibres. Grooves, Number 38. Width. 0'15 inches. Depth, 0'05 inches. Nature and object of the Experiment To ascertain the Eange, &c., of Armstrong's Breech-loading 12-Pdr. Iron Gun, in comparison with Whitworth's Breech-loading 12-Pdr. Programme received, 28th March. Stores received, 2d April, 1861. Minute No. 3625. No. of Eound. I a Elevation. j Projectile. Weight and Mean Weight. Times and Mean Time of Flight. Eange, 1st graze. Mean Eange, 1st graze. Deflection. Remarks. d 5 Ibs. deg. feet. Ibs. seconds. yds. yds. yds. yds. mean. I '75 2 8-0 12 3'5 1239 ... 4* ... 3d April. 2 ... 7-10 ... 3-7 1271 ... 6* ... 3 ... 8-0 ... 3-6 1238 ... 6 4 ... ... 8-0 ... 3'7 1307 ... 4 5 ... ... 8.0 ... 3.6 1226 1256 41 !.! 6 I 'S ... 7.0 ... 3.4 1 1 08 ... S* ... 7 ... 7-0 ... 3-4 1133 ... 5 ... 8 ... 7.0 ... 3-6 1150 4* ... 9 ... 7-0 ... 3-4 I 121 3 ... 10 ... 7.0 ... 3-3 1137 1130 3* ... ii $ 5 6.9 ... 6-8 2134 ii ... 2d April. 12 6-8 ... 6-9 2165 ... 9 ... 13 ... ... 6-6 ... 6-6 2157 ... ... J 4 6-6 6-8 2146 ... 10^ 15 6-6 6-8 2128 2146 7 tt 16 '75 7-9 7.2 ^357 ... ... Wind increased to 4. 17 ... 8-0 ... 7-3 2331 it* ... 18 ... ... 7-10 ... 7.2 2356 ... II ... 19 ... ... 8-0 ... 7.4 2351 Il ... ao ... 8-0 ... 7-3 2 399 2360 II 21 1 -5 10 4-6 12 I22 35 12 12 Wind changed and in- 22 4.8 12-4 3576 II creased. Squally. 2 3 ... 4.6 ... 3593 17 ... 24 ... 4.6 12.4 3597 ... 12 ... Wind increased to 6, 2 5 ... ... 4-5 ... I22 35 6 3 3568 II ... and continued squally. 26 i-75 ... 5-0 ... 12-8 3943 ... 8 ... 28 5.0 ... I 3 .0 3961 !!! 14 29 5 * * I 3 .0 3866 JQ ... 30 ... 5" I 3 .0 3873 3908 21 ... Elevation throughout by Quadrant. The Gun was mounted on a Travelling Carriage, and placed on one of Lieut -Colonel Clerk's Platforms, on the level. Wads, choked in the Cartridge, were used throughout the Practice. The Secretary, (Signed) A. J. TAYLOR, Colonel E. A., Ordnance Select Committee. Commandant and Superintendent. RIFLING AND PROJECTILES. 459 TABLE LXXXII. EXPERIMENTAL PRACTICE. WHITWORTH BREECH-LOADING 12-PouNDER. SHOEBURYNESS, APRIL 2, 186L Height of axis of Gun above plane, 3 feet. Nature, WIIITWORTII'S B. L. 12-Pdr. Gun, No. 1. cwt. qrs. Ibs. Weight 930 Ordnance . Length 8 8-12 feet. Diameter of Bore, Major axis 3 in., Minor, 2'75 in. Spiral, if Elfled, 1 turn in 55 inches. Grooves, No. . Width, . Depth, . Barometer, 29 -7. Wind, South 3. Direction ) of Wind, f Nature and object of the Experiment To ascertain the Eange, &c., of Whitworth's Breech-loading 12-Pdr. Iron Gun, in comparison with Armstrong's Breech-loading 12-Pdr. Programme received, 28th March. Stores received, 2d April. Minute No. 3625. No. of Eounds. j Elevation. 3 ft !! Times and Mean Time of Flight. Eange, 1st graze. Mean Eange 1st graze. Deflection. Eemarks. 1 Ibs. deg. feet. Ibs. seconds. yds. yds. yds. yds. mean. I 1.75 2 7.0 12-094 3-5 1266 ... i 3d April. 2 7-3 3.6 1344 ... 3 3 ... 7.6 ... 3-4 1250 ... 2 4 ... ... 7-3 ... 3-4 1280 ... I 5 ... ... 7-6 ... 3-4 1306 1290 ... Ii 6 i-.S ... 6-6 ... 3-6 1223 ... a i 7 ... 6-6 3-6 I2II ... J i 8 ... 6-6 3'4 1x88 2 9 6-6 3'5 1209 ... 10 ... 6-6 3'4 "59 1198 *i f '5 5 6-0 7-2 2442 ... "if ... 2d April. 12 6-0 6-2 2072 ... ... 2 ... 6-0 ... 6-8 2389 ... i 4 ... ... 5-10 ... 7-2 2449 ... 2 Js ... ... 6-0 ... 7-2 2486 2368 i 16 i .75 ... 7-0 ... 7-0 2475 ... 2i Wind increased to 4. 17 7.0 ... 7-2 2644 ... i 18 6.9 6-9 ^335 ... 2 '9 7.0 7-0 2370 ... ii ... 20 7-0 7-2 2 533 2471 2i ... 21 1.75 10 6-9 13-2 4409 4 ... Wind changed and 22 ... ... 6-8 ... 13-0 4348 ... JO ... increased. Squally. 23 ... ... 6-8 ... 12-8 4387 7| ... 2 4 ... ... 6-9 ... 13-0 4405 H Wind increased to 25 ... ... 6-9 ... 13*4 4449 4400 4 6, and continued 26 !i-5 ... 5-0 12-6 4137 ... 4 squally. 27 5-6 12-9 4299 ... 3 ... 28 ... 5-0 I '0 4139 ... a i ... 29 ... ... 5-0 ... 12-8 4318 ... 31 ... 13 ... 5-0 ... 12-8 4220 4223 2 ... Elevation throughout by Quadrant. The Gun was mounted on a Travelling Carriage, and placed on one of Lieut. -Colonel Clerk's Platforms, on the level. The Powder and Wad were contained in the usual Tin Cases. The rounds marked * were fired with Tin Cases that had been used previously, there being no more in store, and they were simply well cleaned, and answered quite as well as when new. The Wad weighs about 2 oz. 4 drs., and the empty Tin Case about S oz. S drs. The Secretary, Ordnance Select Committee. (Signed) A. J. TAYLOR, Colonel E. A., Commandant and Superintendent. 460 ORDNANCE. ber, whatever the amount of powder, the necessary reduction of powder-space is made by placing a paper cylinder inside the car- tridge, as in the 10-lb. charge (Fig. 242). The lubricator consists of a hollow disk, of thin copper, filled with tallow, and resting upon a paper sabot and felt, in layers. The whole is secured by a wooden screw, to a wooden plug, tied into the mouth of the cartridge-bag. TABLE LXXXIII. RANGE AND ACCURACY OF LONG AND SHORT ARMSTRONG 12- POUNDERS. H. M. SHIP "EXCELLENT," MAY 22, 1861. Charge, i Ib. 8 oz. j Projectile, 10-75 Ibs. ; Elevation, 7 5'; fired at target, 2550 yards distant and 14 feet square. Length Diameti Weight Lo: of bore :r " ?G 12-POUNDER, 84.* 1 2 ? in Length Diamete Weight SHO of bore r " RT 12 -POUNDER. - " ? " 8 rwf *. nrs 8 rwf No. of rounds. Actual range, yds. Beyond or short of target, yds. Deflection, yds. No. of rounds. Actual range, yds. Beyond or short of target, yds. Deflection, yds. I 2580 30 beyond I right. I 2570 20 beyond 3 left. 2 2550 " I " 2 2565 15 3 " 3 2570 20 Through. 3 2570 20 " Direct. 4 2570 20 " 4 2570 20 " Through. 5 2550 " I left. 5 2 545 5 short I right. 6 *575 2 5 I right 6 *545 5 " 5 left. 7 2580 3 I " 7 2550 o Direct. 8 2565 15 Through. 8 2 545 5 " tt 9 2570 20 " Direct. 9 2550 " Through. 10 2558 8 " I right. NOTE. The discrepancy is attributed, in the official report, to error in laying the gun. . SHUNT. The Armstrong shunt rifling, for muzzle-loaders, combines both the centering and compressing systems. As the RIFLING AND PROJECTILES. 461 TABLE LXXXIV. RANGE AND DEFLECTION. ARMSTRONG SIDE BREECH-LOADING AND SERVICE 40-POUNDERS. (Ordnance Select Committee's Report, Oct. 17, 1862.) Elevation. Mean range. Mean difference of range. yds. yds. Side Breech-Loader, 4o-pounder -j 5 10 2147 3688 25.0 45-3 Land Service 4o-pounder 5 10 2150 3660 26.5 25.0 TABLE LXXXV. RANGE AND DEFLECTION OF THE ARMSTRONG SIDE BREECH-LOAD- ING 70-POUNDER. Height of Gun, above plane, 20 feet ; Shells, filled, 25 IBs. ; Charge, 9 Ibs. ; Burster, 5 Ibs. 5 Tin Cup ; Boxer's Lubricators. (Ordnance Select Committee's Seport, Jan. 13, 1862.) d r3 a SM 11 Eanges. I h \4 1 (3 E A o \\ II 11 1| *S X c ^ 3 o, 1 < a. a. i:.*! i *j bo u w o o c g * 3 fc ss Velocity at 120 ft. O *^O H s^5 u-> u-i u-> ^j- ; Time of flight. v 00 ON ^ = i 2 . u^ 0-1 Recoil. 00 ON ON O 00 ON ON ON ff Left. fl 1-1 :*:: : |-2 Right : : | : : | S i .1 Elevation. 3 - 3 = ^ ^ - 1 Mean. --- M ro *- "\ r -\ f -\ Actual. O ^\ O oo ^ O oo oc oo^ vO ^- -oo Q S S> Charge, in Ibs. O I*. s 3 s 3 3 Form. < : = ^ 2 ^ S 3 S3 Weight 1 1 1 O O *O vr r-^ 10 vo ON f^> rl vo VO ON IH M M M V) t/^ IO ^O *-O *-O <-O cj Diameter. to i " 3 ^ ^ 2 ^' 2 ^ ^ M Length. r) 1 'o | .',......, . . . vo t^ oo O"\ RIFLING AND PROJECTILES. 463 .i 1 * ^ * &v ' s 2 *" 1 11 -SS'8 S J8 ^ ^iiT 1 .1 ill S rt .J 1 to jf ^r CO tl_ J-pounder shot fired with b 2 '?r u -C c 3 1 m 1 i vo D u *2 E b c ?!!!* M <4H w 10 v> O M ro C^ H t^ 00 00 CX> 00 M VO * rt g j i i i 2 * S i : M -o 1 1 | x (U 1 ar certaine c rt 1 # 9 * to C 1 g C T3 -5 oo O\ : 5 ? I u 1 C PJ CO U 8 u Q-, CC *n O ^O t~~~ O oo O oo r^- oo oo ON *o O w w oo oo ON d OJ v/i 1 ta hH VO 1 &?*&*'* ^ 1 <*-, I 1 C 3 S ^5 , , U , ^ co I 2 c .2 t-^ -2 1 2 "TJ 1 VO *J^ lr ^ M M f> c* tJ t< oo to to t^- 3 S '1 -^ '1 1 S 1 | 1 I O to r^ vo M ON rj- w M O ON O ON O TS U T3 > 'o o S w -a c M 1 '53 u P 1 % 1 f S 3 2 5 3 ^ r^ HH i S s S o * J5 1 S 1 d u rt *j 1 0) 1 relative k -5 < c^ ^* o "5 -o .^ 1 revented 1^ JJ -C~ T3 ^ 3 O m ^ 1 | s 3 1 w 5 - ^ - - a c c c 2 A *~? ^T i S .*-;. * S ^ 5 S U U ^ & C/3 I| a 4J *J < O O .1 OJ D-, OJ syj In publishing a p OH OJ -o to c >&. The development of one of the grooves is shown by Fig. 246 ; a section at the muz- zle, with the shot going in, by Fig. 244; and the same sec- tion, with the shot coming out, by Fig. 245. The grooves at the muzzle are slightly wider than they are lower down, and are stepped, or have two levels, the lower level corresponding in width with the entire rib, and the higher level being narrower, so that the projectile will only enter by the low level, or deeper portion of the groove. The high level runs into the muzzle, par- allel, for eight inches (in the 'T-in. gun), where an incline com- mences running off to the low-level 14 inches lower down the Shunt; section at muzzle; shot going in. RIFLING AND PROJECTILES. 465 FIG. 245. bore. Supposing the spiral direction of the groove to be such that the shot, in going down, would hug the right side of the groove, as viewed from the muzzle, then, in coming out, it would hug the left side, because the rotation would be in a contrary direction. As the shot goes down, on the right side, it runs against a curve, or switch, which de- flects it to the side upon which the high level is situ- ated. But, at this point, the high level has become ex- tinct, so that the shot runs easily, without compression, Shunt; gection at muzzle; ghot coming out all the way down. In coming out, the shot is regularly revolved by the straight side of the groove, but slides along the bottom of the bore until it reaches the incline, when the compression, commencing gradually, squeezes it up into the middle of the bore, so that it leaves cen- tered and tightly nipped.* 554. The Armstrong shunt shot (Fig. 247), fired with 5'5 Ibs. powder, from a cast-iron 32-pounder, in the trials of 1861 (592), was, in total length, 15'22 in. ; diameter, 6'32 in. ; weight, 5O5 Ibs. ; diameter of powder-chamber, 4*8 in. ; bursting- charge, 5 Ibs. 13 oz. ; twist of rifling, 1 in 28 in. ; number of grooves, 3 ; width of grooves, 1'25 in. ; depth of grooves, 0'18 in. 555. Brass studs, in rows, and a greater number of rows, are now generally used instead of zinc strips. The particulars of the 10^-in., 13-in., and other shunt guns and projectiles, have been given in a foregoing chapter (22 to 30). Upon some of the heavier * "The modification of the shunt system, consisting in reversing the grooves and projections by making the former in the shot and placing the latter upon the bore, was unsuccessful, one of the ribs of a wrought-iron gun giving way after about 100 rounds." Commander Scott. Jour. Royal U. Service Inst., Dec., 1861. 30 466 ORDNANCE. shunt shots there are three kinds of projections for three different purposes. A circular row of studs on the base guides the shot as it enters ; a shorter row rests on the bottoms of the grooves, and allows the shot to run home easily, without damaging the grooves ; a row of long strips bears against the sides of the grooves to rotate the shot. RIFLING AND PROJECTILES. 467 TABLE LXXXVIL RANGE AND DEFLECTION OP THE ARMSTRONG TO-POUNDER MUZZLE-LOADING G-GROOVED SHUNT-GUN. Diameter of Bore 64 in. Length of Bore 109 in. Weight 60 cwt. Mean weight of Projectile 71 -7 Ibs. Bursting Charge 5 Ibs. 6 oz. Charge n Ibs. No, of Grooves 6 Width of do '94 in. Depth of do 0*15 in. Twist, I turn in 45 cals. Gun 17^ feet above plane. Result from 119 rounds. (Abstract of Report of Ordnance Select Committee, Feb. 6, 1863.) Elevation. Mean range. Mean difference of range. Mean deflection. yds. yds. yds. 2 1138 37-97 0-95 5 2316 40.92 2.50 10 3959 60. 3''5 556. Table 86 is an account of the practice with the 13'3-in. gun or 600-pounder,* at Shoeburyness, November 19, 1863. The gun is served by 1 officer and 20 men. The shot is placed in a cradle hooked on to the muzzle, and provided with grooves corresponding with the grooves of the gun. One man lifted up the cartridge and four men lifted the shot. When sponging out dry, 4 men rammed home the cartridge after washing, 6 men. Four men rammed the shot home. The gun was mounted on a garrison carriage of 54 cwt., with a platform of 75 cwt., having an incline of 3^. The gun was traversed on a raised iron 'racer with a treble and double block-tackle, by 6 men on a side. The shot ricocheted straight. The time between the shots was toward the end of the firing, 10 minutes. 557. The shunt rifling adopted in Russia, as used in the 9-in. steel gun (134), is illustrated by Figs. 248 to 251. The projectiles * A minute description of this gun and its rifling has been given in Chapter I. (30.) See also note in Appendix. 468 ORDNANCE. TABLE LXXXVIII. RANGE AND DEVIATION OP VO-POTTNDER SIDE BREECH-LOAD- ING ARMSTRONG GUN. Calibre, 6 -4 in. ; length, no in.; weight, 6903 Ibs.; 70 grooves, I turn in 45 calibres. Gun 17 feet above plane. No. of rounds. Elevation as to point of impact. be 3 M 5 111 til 3 *"' Mean reduced time of flight. Eanges. Mean difference of range. Mean observed deflection. Mean reduced deflection. Min. Max. Mean. Ibs. Ibs. sec. yds. yds. yds. yds. yds. yds. 10 l 28' 9 77-875 seg. shell. 2-25 682 728 710 14.1 0-98 0-38 10 2 18' 10 79-812 3-47 1105 1176 1134 20-7 1-24 0.68 solid shot. 10 2 18' 9 68.562 3.40 1068 mi 1096 7.7 0-94 0.68 com. shell 10 5 9' 10 79-81* 6.90 2132 2266 2183 3"5 2-98 3.22 solid shot. 10 5 9' 9 68-562 7-01 2016 2236 2156 51-1 3.42 0-88 com. shell 10 10 6' 9 77-875 12-13 3448 3710 3578 79-8 5-24 I -96 seg. shell. 10 5' 9 68.562 12-63 3586 3760 374 30.9 15-60 a. 80 com. shell are fitted with " composition-metal" rectangular studs. Most of the projectiles are 2J diameters long, so that the 9-in. gun fires a shell 22^ in. in length. Figs. 252 and 253 show the different forms of steel shells recently used in experiments against armor (235). 558. The following are the dimensions of the rifling in the steel 24r-pounder (6*03) and the 8-in. guns : The rifling is from left to right, looking from behind. It commences 6 in. from end of bore. The bore must be cylindrical, and the difference between the diameter at different sections should not be greater than O'Ol in. The bore must be between 6*03 in. and 6*05 in. The diam- eter of discharging-grooves should be from 6 -29 in. to 6*31 in. at the muzzle, and at 36 in. from muzzle, from 6 -31 to 6*32 in. Diameter of loading-grooves from 6*38 in. to 040 in. Breadth B.IFUNQ AND PROJECTILES. 469 470 ORDNANCE. TABLE LXXXIX. PRACTICE WITH ARMSTRONG'S T-INCH SHUNT-EIFLED MORTAR. SHELLS WITH COPPER AND ZINC KIBS. 1 g No. of Hounds. Charge, Ibs Elevation. Weight of Shell, Ibs. Mean reduced time of flight, Mean range, Yards. ii |.l C < 1 Seconds. 1^ p 10 I 42 87-812 jo.6 601 21-7 2.7 2 10 1-25 ii. 8 765 24.5 3-7 5 2 45 87-562 17.1 1332 78.2 ii. 8 I 5 3 " 21-7 2028 108- 7-2 2 5 3'5 " " 23.0 2072 145. 13.8 4 5 4- " 23.9 2268 124- 37 .o 4 5 5- " " 26.2 2627 43-2 4. Burfting charge, 6*625 ^s. of discharging-grooves, from a point 6 ft. 9 in. from end of cham- ber to muzzle, and from a point 3 ft. 9 in. from end of chamber to breech, from O'TO to 0'72 in. ; and discharging-grooves from a point 6 ft. 9 in. from end of chamber to muzzle, from O'TT to 0*83 in. >>9. The Il\i>tiii*ion System. This system is carried out on the most extensive scale in the United States ; in England it is experimental, and has not been adopted in the service. On the Continent it is hardly recognized. 56O. The plan of rifling almost universally adopted in America (Fig. 254), is lands and grooves of the same or nearly equal width, viz. : | to in. wide and V to y^ in. deep in the smaller guns, and to 1J in. wide and T V in. deep in the larger guns. 561. As all the standard Army and Navy projectiles (except Sawyer's, Figs. 225 and 226), viz., James's, Hotchkiss's, Schenkl's, Parrott's, and Stafford's, are expanding projectiles ; they may all be used in any gun of proper calibre, irrespective of the width or depth of the grooves. 2. The ranges of these projectiles from Held guns (bore from RIFLING AND PROJECTILES. 471 2-9 to 3-80 in.), with 12 or 13 elevation (the greatest elevation the carriages will admit of), is from 3000 to 3500 yards, or about If to 2 miles. With higher elevations 6000 yards are easily attained. FiG. 248. PIG. 249. FIG. 250. FIG. 251. FiGS. 2i8 to 251. Shunt rifling of Russian 9-in. gun. Scale, 1| in. to 1 ft. Fig. 248 ......................................................... Section at muzzle. 2,49 ........................................................... 36 in. from muzzle. " 250 ......................................................... 92 in. from muzzle. " 251 ........................................................... 124 in. from muzzle. oO3. The gaming twist is not employed to any considerable extent except in the Parrott guns; and Parrott's projectile (573) is particularly adapted to this twist, by having a very short bear- ing. The long bearing of the Armstrong shot (459) would evi- dently be stripped by lands with increasing pitch. 564. JAMES. The James (American) projectile is illustrated by Figs. 255 to 258, and is cast with 8 or 10 longitudinal recesses or slits 472 ORDNANCE. leading from the periphery to a central orifice in the base. These are filled with soft metal, which is pressed out into the grooves of the gun by the powder-gas acting through the orifice e y Fig. 255. Fig. 257 is a section through one of these recesses, d ; m in are the entrances to other recesses, from the central cavity. The projec- tile retains its full diameter for \ in. of its length at each end of the cylindrical part The intermediate space is -J in. less in diam- FlG. 252. FIG. 253. Russian shunt steel shells. FIG. 254. Rifling of 4.2-in. United States siege gun. Full size. eter, forming a recess, in which is wrapped a plate of tin, covered by a piece of canvas, secured to the tin by being folded under it and cross sewed. The space inside of the tin wrapper is filled with melted lead, which adheres to the tin and prevents its revolving on the shot. The outer canvas wrapper is well greased, to insure an easy entrance, and to clean and lubricate the gun. 565. The average weight of the projectile for a 42-pr. (old) gun is, if solid, 81} Ibs. ; if a shell, 64} Ibs. Its length is 13 in., of which 6 in. is cylindrical. The James projectiles used in the breaching of Fort Pulaski were fired from 42, 32, and 24-pounder guns, and weighed, respectively, 84, 64, and 48 Ibs. The charges were, respectively, 8, 6, and 5 Ibs. of powder. 566. HOTCHKISS. The Hotchkiss (American) projectile (Fig. 259) consists of a cast-iron body, which may be a shot or a shell, with a cylindrical base of diminished diameter, over which a cast- iron cap is fitted. These parts are slightly less in diameter than RIFLING AND PROJECTILES. 473 the bore of the gun. The groove between the body and the cap is cast full of lead, so that the first power of the powder, before the FIG. 255. FIG. 256. James shot. James shot, without packing. inertia of the whole projectile is overcome, is devoted to driving the cap farther upon the body, thus squeezing out the intermediate FIG. 257. FIG. 258. Section of James shell. New James shelL lead into the grooves of the gun, and at the same time holding the lead, as in a vice, so that it cannot revolve on the projectile. As in the James shot, the lead is covered by a greased canvas band. The lengths and weights of projectiles of different calibres are varied according to circumstances.* 567. THOMAS. Mr. Lynall Thomas's (English) projectile (Fig. 260), as used with little success in the competitive trials of 1861, > * In a letter to the Army and Nary Journal, of Nov. 14, 1863, Mr. Hotchkiss states that he is furnishing his projectiles to the U. S. Government at the rate of 3000 per day; and that he has made, since the rebellion commenced, over 1600000 projectiles. 474 ORDNANCE. closely resembles the Hotclikiss projectile. The lead is forced into the grooves by a sliding ring instead of a cap. The particulars of the rifling and projectile are as follows : Pitch of rifling, 1 turn in 18 feet ; No. of grooves (flat, square-cornered), 7 ; width of grooves, FIG. 259. Section of the Hotchkiss shell 1*8 in. ; depth of grooves, O'l in. ; weight of shell, 55 Ibs. ; length, 10'2 in. ; diameter, 6*3 in. ; diameter of powder-chamber, 3*2 in. ; bursting charge, 1 Ib. 5^ oz. ; charge, 7 Ibs. 568. With a 7-in., 7-grooved, puddled-steel gun, of 7 tons Fro 200. Lynall Thomas's early projectile. weight, forged solid at the Mersey Iron works, and a 175-lb. shot, charge, 27 Ibs., elevation, 35, Mr. Thomas has obtained the longest range on record 10070 yards, or nearly 6 miles. The gun burst after a few discharges. RIFLING AND PROJECTILES. 475 The rifling lately adopted by Mr. Thomas has been described under the centering system. 569. SCHENKL. The Schenkl (American) projectile (Figs. 261 and 262) is a casting, having its greatest diameter a little more FIG. 261 FIG. 262. Schenkl projectile, without patch. Schenkl projectile, with papier mache patch. than ^ of its length from the forward end ; from which point, to the rear end, it presents the form of a truncated cone, with' straight projections cast upon it. Around this rear portion is placed a ring of papier mdcke, the interior of which is made conical and grooved to fit the projections on the casting, so that there shall be no lateral slipping : the exterior is cylindrical, and slightly smaller than the bore, so as to run home easily. The powder-gas drives the papier-maclie packing forward upon the cone, whence it is jammed into the grooves of the gun, and made so compact as to rotate the projectile without stripping. Upon leaving the gun, the papier mdche flies off in the shape of a harmless powder. The weights and lengths are varied for different service. 57O. REED. The Reed (American) system (Fig. 263) is not largely adopted in the form shown, but illustrates the principle of several projectiles extensively used in both the Northern and Southern States. In the latter, the projectiles are usually of Eng- 476 ORDNANCE. lish make, and have a brass disk, or a brass cup, bolted to the base of the shot. Fig. 263 shows a corrugated ring of wrought iron FIG. 263. The Reed projectile. cast into the base of the shot. The pressure of the powder ex- pands and mashes the ring into the grooves of the gun. 5T1. BLAKELY. The projectile manufactured by the Blakely Ordnance Co., and elsewhere in England, to be used with the Blakely guns and Brooke's guns, is illustrated by Fig. 264. The FIG. 264. / \'^'^ Captain Blakely's projectile, expanding copper cup c is secured to the base of the shot, what- ever its size, by a single tap-bolt, and is prevented from revolving on the shot by being compressed by the powder-gas against pro- jections cast (or in case of steel shot, planed) on the base of the shot. The space e is filled with tallow, to lubricate the gun. The small soft metal studs a are greater in number than the grooves of the gun ; so that however the shot is put in, some of the studs will bear upon the lands, and hold up or centre the point of the shot. The engraving shows a 21-lb. shot for an " 18-pounder," J size. 572. The rifling of Captain Blakely's 9-in. gun is shown by Fig. 265, and of Brooke's (Confederate) T-in. gun by Fig. 266 (104). The groove of Captain Blakely's 12f in., or 900-pomider gu'i (66), RIFLING AND PROJECTILES. 477 is shown by Fig. 267. The grooves are 4 in number, and are used with a modification of Commander Scott's projectile (535). Fia. 265. Rifling of Blakely 9-in. gun. Full size. 573. PARROTT. The Parrott projectile (Figs. 268 and 269) consists of a cast-iron body, recessed around the corner of the base to receive a brass ring from 1 in. to about 1 FIG. 266. in. in width, and in. in maximum depth, which is mashed into the grooves of the gun by the explosion of the powder. The recess in which the brass ring is cast, is provided with numerous projections, parallel to its length, like the teeth of gearing, by which the ring is prevented from revolving on the shot. The diameter of the recess is greatest at the extreme rear of the shot, so that the brass ring cannot fly off without breaking. The entire shot is slightly smaller than the bore, so as to be easily rammed home. 574. The weight of the 6'4-in. (32-pounder) Parrott shot and shell is from 70 to 100 Ibs. The 8-in. projectile weighs from 132 to 175 Ibs., and the 10-in. averages about 250 Ibs. The Parrott projectiles used in the breaching of Fort Pulaski were 30-pounders charge, 3| Ibs. In the rifling of the Parrott guns, the grooves and lands are of equal width, and T V in. deep. The bottom corners of the grooves Rifling of Brooke's 7-in. gun. 478 ORDNANCE. * CO ~ X oo c CM 811 REMARKS. 2 ii . y 8J! < & Pressure per sq.in., as indicated oy Rodman's pres- sure-gauge. OOOOOOOOOO 000000000*0 ro O O ^ O O O ^ I"*" *2 QQ i/*, o vO t~*~ ^t* ^ ^-O vO ON ^ "cnrJ-OOOO H Wt 4* 1^ ^T fl M ro Drift to Right. in vr> u-> u-i o O Time of Flight, r^N H ^: : : : : :mt.oo wio rt t^-tl ONW O I s * ^? O Mrtronrooot^ootxsro ^ M HHrtHrttnpococom N VO ^O m 4 1 -* 0\ i fi l J 1 CO ^ Powder. (4 . I S 3 T - 3 in ^ t^ s f 11 f I 8. g i 8. 3 3 U 3 j S Q K M Q Q S M Doremus cake, Hazard, 2,... Elevation. ^--553 0^355 - Number. M H tn^^vo r-oo o\O M RIFLING AND PROJECTILES 479 - o o o o o o vo o r-*- H to o OdOOOOOOOOOO vO ONOOQVO ^ ^- c COHVO ^~ vo vo u-,ov7-,0o OOOOOO 0^ rf- O H f j* Ss Ib IT ? 5 1 R s- R s ? a 1 1 1 1 1 I c/3 OT c/i c/j v) V) M d" ^ g" z *r ^ - 3 a* *r ^^^^^^^| w^ 333 "S 1 O N Q a 8 a : 3 331^33 vo 3 . . I - i 1 i i 1 f s r 1 1 W S3 Q ro TJ- vo vo t^ oo ONO^^^^-vovor^ooosO 480 ORDNANCE. REMABKS HI 5-.-0 ^W> *5 t3 *+ '1 * 'i . 3 U) rt 2 *i^ U 00 C > -d Pressure per sq.in., as indicated Dy Rodman's pres- sure-gauge. M r rf< rt rort rorooooo t^OO O Range, in yards. ,00 rtrr^ooO'-'OOOO S+ M M M M _* c22|c22|c22^c22| I -^ijllJ^lJ^lJ ^coco^loco^coco^coco 1 f 1 1 1 1 a s- a Q K n Q K Elevation. g 3 5 8 2 2 2 V - - 5 5 Number. a a 8 * B * ft % * 4 8 T O M RIFLING AND PROJECTILES. 481 o o o o rj- ON ON O 0000 1-1 r> oo ON O O ON O O\ ON ON ON w oo oo O <* O O 00 00 00 s . a if 00 00 =f o" *S .5 i M 31 482 ORDNANCE. FIG. 267. are rounded. The twist of the grooves in the 100-pounder com- mences at and ends at 1 revolution in 18 feet. The bore is 130 in. long. The 8-in. rifle has 11 grooves ; the twist com- mences at 0, and ends at 1 turn in 23 feet. The bore is 136 in. long. The 10-in. rifle has 15 grooves ; the twist commences at 0, and ends at 1 turn in 30 feet. The bore is 144 in. long. 575. Figs. 270 and 271 show the accuracy of the Parrott 100- pounder shells in practice which was much like service, having Groove of Blakely 12|-in. gun. Full size. FIG. 268. Parrott's hollow shot. FIG. 269. Parrott 100-pounder shell. RIFLING AND PROJECTILES. 483 TABLE XCI. TRIAL OP PARROTT 6'4-lNCH 100-PouNDER RIFLE, BY FIRING IT 1000 TIMES WITH 100-LB. PROJECTILE AND 10 LBS. CHARGE. WEST POINT, JULY 1 TO JULY 19, 1862. GUN, FOUNDRY, No. 339; CAST MAY 22, 1862. Ibs. Greenwood Iron, No. 1 4480 Greenwood do., No. 2 3360 Salisbury do 2 35 2 Scotch do 336 Gun-Heads do , 2240 12768 The metal was 2^ hours in fusion. DENSITY. TENSILE STRENGTH. BAB. 7.3750 29897 HEAD. 7.2848 34975 Wrought-iron reinforce, 27 in. long and 3*2 in. thick, was made from a bar 4 x 4 in. and 76 ft. long, and weighed, finished, 1725 Ibs. DIMENSIONS. Inches. Length, extreme 154*25 Do. Bore 130 Do. Trunnions 5 Diameter of Bore 6-4 Do. Trunnions 8- Do. at Muzzle 13.038 Grooves square, with rounded corners. Increasing twist commenced at o, and ended at muzzle with I revolution in 1 8 ft. Inches. Diameter reinforce 2 5'9 Length from face to end of Grooves 124 Width of Grooves 0.711 Depth do o-i Weight 9812 Ibs. Preponderance - ao " Copper bushing in vent, - in. diameter ; vent vertical, entering the bore, at 3-75 in. from the bottom. The powder was furnished by the Navy Department, and consisted of Dupont's No. 7 grain. Initial velocity, mean of 3 fires, 1151 ft.; pressure per sq. in., 8226 Ibs. The cartridges were 5.7 in. diameter. The gun was fired by a friction tube. 484 ORDNANCE. PAKROTT'S PROJECTILE, WITH BRASS RINGS AT THE BASE. Shot flat-headed, averaging 98^ Ibs. Shells loaded with sand, averaging IOI^ Ibs. The projectiles used averaged loo Ibs. The gun is yet in good condition. The elevations varied from 3^ to 15, the majority being at 4^ and 5. Four were fired at 10, 34 at icvj- , 6 at 14, and 18 at 15. Of the projectiles, 927 took the grooves perfectly and performed well. Of the remain- der- Wobbled, range good 12 Do. do. bad 8 Ring broken, good 48 Do. do. bad 2 Sound angular, good 2 Unloaded shell, broken I 73 9*7 At the 3OOth round 3 incipient cracks appeared round the vent-piece, but were not much increased by constant firing. The effect of firing on the grooves was only to polish them. Their edges were sharp and well defined, and the accuracy of firing was not diminished at the end of the trial. STAR-GAUGE. The bore was gauged at the termination of every 25 rounds. The greatest enlargement was -023 inches, near the seat of the brass ring, and opposite where the reinforce terminates. The gun often became very much heated from the rapid firing as fast as one round in less than two minutes and the consequent expansion of the metal gave large results. The temperature of the gun, when heated by firing, was 130; when cold, 81. EXPERIMENTS AGAINST ARMOR. 485 TABLE XCII. TRIAL OF PARROTT 8-lNCH 200-PouNDER RIFLE. WEST POINT: COMMENCED MAY 28, AND ENDED APRIL 2, 1862. Bore, 8 in.; weight, 16000 Ibs.; rifled with n grooves; increasing twist, 23 ft. at muz- zle; specific gravity of metal, 7 3025 ; tenacity, 34059. Projectiles, prepared with brass rings, !-- in. wide. Hollow shot, truncated ., 15 in. long. Solid shot, truncated 15 " " Short shell, conoidal i?| " " Long shell, truncated 19 " " Weight 150 Ibs. Weight 176 " Weight 155 " Weight 200 " The cartridges fitted the bore with just windage enough to render loading easy. No. of Hounds. Powder. Jl Q Projectile. I Elevation. 12 Ibs. I c Hollow shot. Ibs. I CO ri 16 u * J 15 Short shell. * j 155 J4 Si to Si 8 u 16 u 155 5 2 I 7 Dupont No 7 . . 16 j e Long shell. Short shell. 200 T r c 5 tO C-i- * 5 2 * j 16 Solid shot. 55 177 LU 57 2 u 15 Short shell. ISS 10 2 u 15 M J 55 15 2 " 15 U 155 20 5 Smith & Rand's, No. 5 IS u 150 to 155 5 to 6 4 u 15 Solid shot. 176 to 186 6 to 6f 18 16 Shell and shot. 155 to 176 5 f to 6 i " 15 Short shell. 155 15 6 U Hazard, No 2 .... 15 16 Solid shot. Shell and shot. 177 i *\ c to 176 20 4 16 Long shell. 200 51 2 u 15 Short shell. 155 'S 486 ORDNANCE. TABLE XCIL (CONTINUED.) 100 shot fired into a bank 2100 yards distant. Time of flight, 6^ to 6J seconds. Accuracy very great. Of the first 26, 20 struck within 10 sq. ft. Drift not to exceed 5 feet. All the projectiles took the grooves without failure, which was remarkable, as the gun had not been fired before, and was the first gun made of this calibre. The greatest en- largement was 12 in. from the bottom of the bore, at the position of the expanding brass rings, and was : At 9Oth round -004 in. At looth " -006 JUNE a. Initial velocity of the same gun by means of Benton's Electric Ballistic Pen- dulum : 1 I 1 1 Powder. Projectile. SI o o 1 s* 1 C 1 & 1 1 w '3 Ibs. Ibs. ft. I Bennington, No. 5... 16 Shell. 152 41 1197 2 " 16 152 4l 1215 Dupont No c 16 M 4t 12 5 4^ 34 4 Hazard, No. 5 16 " 152 41 1197 5 Bennington, No. 5... 16 H 155 5 1182 6 Hazard, No. I 16 " 152 4 1244 7 Dupont, No. I 16 H '55 5 1179 J Hazard, No. 7 \ 16 {Spherical shell filled with earth l8oq t Dupont, No. loj Papier mache sabot... * u 7 9 Bennington, No. 5... 16 Shot. 75 5* 1161 RIFLING AND PROJECTILES. 487 been made at the 501st and 601st rounds, respectively, while firing the gun 1000 rounds. The targets were made of boiler-plate, and set at 2000 yards from the gun. The smaller target, 8 ft. 11 in. by 4 ft. 2 in., was hit, as shown, 6 times in 14 consecutive rounds. The other target, 10 ft. square, was hit 9 times in IT consecutive rounds. 576. STAFFORD. The projectile shown by Fig. 272 has re- cently been introduced in the United States Army. A brass cup is forced upon the conical base of the shot (590). 577. BUCKLE. The projectile, Fig. 273, has also been re- cently employed in the United States Army. The cup of lead at the base of the shot is held in place by a thin brass sleeve which is forced into the grooves of the gun. 578. JEFFEKY. Mr. Jeffery's projectile and rifling are illus- trated by Figs. 274 and 275. The lead is affixed to the rear of the projectile by dovetails, into which it is cast ; a hollow, resem- FIG. 271. ~u~~ O -\JU- FIG. 270. O % o O * d o QD to 1 bling that of the Minie bullet, is left at the bottom, for the pur- pose of causing the lead to be driven into the rifling. A wad or covering, consisting of flannel coated with soft soap, is wrapped around the rear of the projectile, to facilitate loading, decrease windage, and lubricate the bore. 57O. The following are the particulars of the rifling and pro jectile (Fig. 274) used in the competitive trial of 1861, with a 5|- 488 ORDNANCE. S ^ bo J ^ B ^ ^ I <^l r) O rt CO a ^ 1 I .5 1 u M ,2 - 1 2 J4 """ "O ON CO 1 5 ^ 1 -o c 1 1 e ^ s ^ -2 ^ s 3 bo 1 3 s 1 g C ^ *ii ^J 8 .fc u Sow" rt 1 ! 1 J 1 1 "8 bo g* *o ^ > I .S 1 c a V 1 "S, I 1 I 1 i 1 -o o 11 j i j i x - 1 y <"> 1 M A _* ^ 1 C .2n a 3 u H M O s O * vo * M, u-i O vo O ^ s M3 u 8 I ffi 490 ORDNANCE. Ib. charge in a 32-pounder cast-iron gun : Pitch of rifling, 1 turn in 64 feet ; No. of grooves, 7 ; depth of grooves, 0*12 in. ; width ot grooves, 1'65 in. ; weight of shot, 45 Ibs. ; length, 9'68 in. ; diam- FIG. 272. FIG. 273. Stafford's new projectile. Buckle's projectile. eter, 6'2 in. ; diameter of powder-chamber, 4'6 in. ; bursting charge, 2 Ibs. 8 oz. The range of the Jeffery, as compared with the Armstrong 100-pounder projectiles, is shown by table 108. 58O. BRITTEN. The system of Mr. Bashley Britten, shown Fra. 274 Jeffery's shell by Figs. 276 and 277, is at present in considerable favor in Eng- land, and resembles the American system, both in the shape of the grooves and in the expanding lead base. The groove shown by Eig. 278 has been employed by Captain Blakely for this pro- RIFLING AND PROJECTILES. 491 FIG. 275. Jeffery's rifling. jectile, and is largely used by the Confederates for other expand- ing projectiles. 581. The most novel and valuable part of Mr. Britten's in- vention is the fastening of a lead ring to an iron shot, by zinc solder, so firmly that the explosion will not strip it off. This process is now used for coating the Armstrong projectiles (549). The process, as practised at Woolwich, is as follows : The iron projectile is heated to a dull-red heat, dipped in sal-ammoniac, which tho- roughly cleans the surface, held for about 2 minutes in a bath of melted zinc alloyed with antimony, and then placed in a bath of melted lead, hard- ened with zinc or tin, for 3 or 4 minutes. It is finally placed in an iron mould, and lead from the last bath is poured around it. The projectile, thus coated, is squeezed out of the mould by a screw. A wooden plug, usually screwed to the bottom of Britten's projectile, is driven against the lead, and causes it to expand into the grooves. The amount of projection on the ring //, Fig. 279, as the projectile was formerly con- structed, regulated the press- ure of the lead against the bore, and was adjusted so as FIG. 276. Britten's rifling. 492 ORDNANCE. to just stop the windage without wasting power or straining the gun. 582. The following are the particulars of the rifling and pro- FIG. 277. FIG. 278. Britten's projectile. jectile used in the trials of 1861, with 5 Ibs. of powder, and a cast- iron 32-pounder gun : Twist, 1 in 48 feet ; No. of grooves, 5 ; width of grooves, 2 in. ; depth of grooves, O10 in. ; weight of shot, 47 Ibs. ; length, 1O7 in. ; diameter, 6*25 in. ; diameter of powder-chamber, 4'7 in. ; bursting charge, 3 Ibs. 7 oz. (592). 583. The ranges of the Britten 100-lb. projectile at 10 eleva- tion, charge 10 Ibs., are from 3400 to 3500 yards. 584. Armor-Punching Projectiles. Whitworth's armor- punching shells,* lately fired through the Warrior target (231)^ is thus described by the inventor in his patent specification :f * Speaking of armor-punching shells, the Ordnance Select Committee say (Novem- ber, 1862,) that " there is great reason to expect similar results from the guns of the service when the same material (for shells) is employed. To Mr. "Whitworth, however, will always be due the great distinction of having first effected it." Report of the Select Committee on Ordnance, 1863. f No. 1665. June 2d, 1862. RIFLING AND PROJECTILES. 493 FIG. 279. " Now it has been found, that one cause of the inefficiency of shells heretofore employed against armor-plates has been, that the concussion, on a shell striking armor- plates of any considerable thickness, and with velocity sufficient to pene- trate, generates so much heat as to explode the bursting charge in the shell, thus fracturing it before it has had time to pass through the armor- plating. Another cause of the ineffi- ciency of shells heretofore employed against armor-plates has been, that the shells have been so weak that the force of the blow has been sufficient to fracture them mechanically; this weakness has arisen usually from the material of which shells have been formed being soft, or brittle, or both, and in many cases also from the form given to the shell. According to my invention, shells are made of metal Britten's early projectile. FIG. 280. FIG. 281. FlG. 282. FIG. 283. Whitworth's armor-punching projectiles. properly hardened. They are solid for a sufficient length in front of the internal cavity to give the requisite strength for penetra- tion. 494 ORDNANCE. " The fuse usually employed for igniting the bursting charge is dispensed with, as the heat generated by the impact of the shell is sufficient to ignite the bursting charge. To prevent the heat generated by impact from acting prematurely, and to regulate the time of ignition, the bursting charge is surrounded with a proper thickness of flannel, or other material which is a non-conductor of heat." 585. Mr. Whitworth then states that he converts or highly carbonizes a forged bar of homogeneous iron (or very mild, lowly- carbonized steel), i to -J in. deep, which then, being dressed and bored, is put into the ordinary case-hardening material, heated to redness, and cooled by jets of water or brine. He then tempers it by placing its base on a block of metal heated to a dull-red heat, until a straw-color at the point and a blue color at the base indicate that it is properly tempered. The front plug, Z>, also hardened and tempered, is sometimes used to enable the shell to be more thoroughly hardened. 586. The time of bursting is regulated by the thickness of the flannel layers, x x. "I. have found practically/' the specification continues, "that a shell, such as shown, having a maximum diameter of 7 inches, and propelled by 27 Ibs. of powder, will, at a range of 800 yards, pene- trate with facility a 5-in. wrought-iron plate supported by a heavy backing of timber and iron skin."* 587. Mr. Whitworth uses the flat front for punching armor, because, as it is generally impossible to make a shot strike at exactly the right angle, a round end will glance. The shot is made largest in the middle, because the hole made by the head is always larger than the head, thus leaving room for the body to * "In the year 1824, Captain Norton completed an elongated rifle-shot and shell, and in 1826, we find him using them at Dublin, "Woolwich, Addiscombe, and Sand- herst, as well as at various other places, with complete success. * * * In 1832, we find Captain Norton at Windsor, firing a. flat-fronted steel punch-formed rifle-shot from an air-gun through a Life Guard's cuirass, and exploding powder placed on the other side. This steel punch-fronted rifle-shot was tested at Woolwich, in 1828, and Captain Norton stated that it might ' also be converted into a shell, by drilling a hollow tube into its front.'" Cor. Mechanics' Magazine, Jan. 30, 18G3. RIFLING AND PROJECTILES. 49o pass through without much resistance and better flight. The best compromise results in the form shown. 588. The shell proposed by Commander Scott for punching armor, with a percussion fuse in the rear, is shown by Fig. 284. FIG. 284. FIG. 285. Scott's steel shell. 589. Captain Parrott's shot for iron-clad fighting (Fig. 285) is entirely of cast iron, but is reduced and chilled at the end, which prevents its mashing like strong soft cast iron.* 09 O. The sub-calibre shot and shell proposed by Mr. Stafford (249) for punching armor, are shown by Figs. 286 and 287. The steel projectile, covered with wood, simply to centre it, is attached in the rear to a piston the full size of the bore, so that its weight is very small compared with the full- calibre projectile of equal length, while the area upon which the powder acts is the same for both. The projectile is rotated by a brass disk attached to the rear a modification of the Reed system (570). 59O A. The sub-calibre projectile of Messrs. Bates & Macy, of New York, is illustrated by Figs. 287 A to 287 E. The following considerations and facts are quoted from the inventor's circular : " The engraving shows the shaft projectile (p) before and after Parrott's shot, with chilled end. * Cast-iron spherical shot have been more recently cast with a chill in England, by Captain Palliser. 496 ORDNANCE. loading. It occupies about one-eighth of the space in the bore of the piece, and is of equal weight with a ball (B) of the calibre of FIG. 286. Stafford's sub-calibre punching shot. the gun. It may be, however, of greater or lesser weight, and of greater diameter when adapted for a shell. The form of the FIG. 287. Stafford's sub- calibre punching-shell. end of the head may be square, for perforating iron armor, or conical, for entering masonry or earthworks, or for piercing ships under water. By a proper device in the breech of the gun, this projectile can be rotated during its discharge, but the true direction of its flight does not depend upon rotation. The prin- ciple of its projection is the same as that of the arrow. The centre of gravity is placed forward of the centre of bulk and lateral resistance, whilst the impulse of the discharge is communicated to the shoulder of the head, by an annular disk (i>), at a point before the centre of gravity ; the tail being guided in the minor bore of the breech. A right line motion is thus secured in the direction of the axis of the projectile, and any tendency towards tumbling is entirely prevented. " The force of a projectile, or its impact, may be expressed by multiplying its weight by the square of its velocity ; but projec- tiles of equal weight and velocity, but of unequal resistant areas, RIFLING AND PROJECTILES. 497 will differ in penetrative powers, as the square root of the ratio of resistant areas, in favor of the one of least area. Hence the im- portance of a high degree of velocity, and the great advantage of reducing the section of penetration. * * * " The force of the gas being exerted in every direction, the long, 32 498 ORDNANCE. narrow charge acts with proportionate power against the sides of the gun, thereby straining it far more than the shorter charge in a bore of commensurate diameter. In the latter, the projectile absorbs a given force more rapidly, and the piece is the sooner relieved of strain. Influenced by these facts, a large diameter of cartridge has been deemed essential in the system under con- sideration. The charge is contained in an annular cartridge (c). Through the space in the middle the tail of the projectile passes in loading. " The force is applied to the base of the head of the projectile by means of the disk (D), as shown in the engraving. It fits loosely on the tail, and occupies the bore when loaded, and guides the head in passing from the gun. The windage is stopped by a leaden flange inserted in the rear edge. "When freed from the gun, the disk is stripped from the projectile, and comes to the ground within range at command. This is done by the resistance of- the atmosphere, being about eight times greater on the large surface of the disk than on the head of the projectile. The disk may be fitted with a vent for discharging the piece, thus dispens- ing with the usual vent in the gun, and thereby increasing its durability. " The invention described requires a muzzle-loading, smooth- bore piece, fitted with a small bore through the breech for the insertion of the tail of the shaft projectile ; or the piece may be adapted to contain the entire projectile, in which case it must have a differential bore ; or a jacket can be fitted to cover the pro- truding tail of the shaft, in pieces which are fitted in the manner shown in the engraving, should it prove desirable. " The advantage of the rifle motion can be gained without the expensive and weakening process of grooving the bore of the gun, by means of a rifle-box inserted in the breech, which shall act upon the rifled tail of the projectile. This arrangement leaves the gun smooth-bored for the discharge of round shot or shell. It is effected by stopping the bore in the breech with a close-fitting bolt, which is secured in place with a screw. " This ordnance will fire the following classes of projectiles : RIFLING AND PROJECTILES. 499 1st. Round shot and shell, or other smooth-bore missiles. 2d. Shaft shot and shell with smooth-bore motion. 3d. Shaft shot and shell with rifle motion. The easy application of this improvement to ordnance already in service is an advantage which is very great. All smooth-bore cannon can be fitted readily according to this system, thus vastly improving their efficiency. * * * " The shaft projectile will strike with its END, no matter at what elevation it may be fired, or to what distance it reaches. Along the entire path of its flight its axis is maintained in a tangent to the trajectory. * * * It will not ricochet or glance like a round ball or rifle-shot, but will pursue the original direction, as in the air. Whether it be discharged into the water from above or below the surface, its motion is governed by the same principle. This theory has been proved in practice. " The first trial of this system of shooting was made with a model cannon about sixteen inches in length and of two-inch bore. The bore of the breech was half an inch in diameter. The projectile weighed seventeen ounces, and was fired with three ounces of powder. The target was a white-oak butt, twelve inches thick. Round balls were fired first ; their penetration was about three and a half inches the shaft projectiles went entirely through. " The second trials were with a larger piece. A 12-pounder cast-iron gun was fitted by boring the breech for the tail of the projectile. The length of the bore was 40 inches ; diameter, 4'62 inches. The length of projectile was 52 inches ; diameter of the head, one inch and five-eighths of the tail, nine-eighths. The chief object was to discover the proper proportions in the distri- bution of weight and form. The projectiles differed in weight from 14 to 16-J- Ibs. ; some of them were rotated in their flight, and others were not but when fired they all served to prove the the- ory of the system, and to show its entire feasibility in practice. The charge was from 1-J- to 2 Ibs. of powder the disks weighed from 2 J to 3 Ibs. "At a distance of 250 yards from the gun, the fired projectile can plainly be seen sailing like an arrow through the air. The 500 ORDNANCE. disk invariably comes to the ground before the projectile ; follow- ing it at an ever-increasing distance, it makes a trajectory of less elevation. " These experiments have been regarded as valuable chiefly for preliminary objects, and to test any seeming objections which might arise to the theory and practice of the system." 591. hells for Molten Metal. Figs. 288 and 289 showLan- FIG. 288. PIG. 289. Lancaster shell for molten metal. Scott's shell for molten metal. caster's and Scott's shells for firing molten iron. They are lined with loam, to prevent the excessive escape of heat from either expanding the shell and sticking it fast in the gun, or from igni- ting the charge, in case of delay in firing. Lead-coated projectiles would, of course, be destroyed by the heat of molten metal. 592. Competitive Trial of Rifled Oun. In 1861, a com- prehensive experiment on six different systems of rifling and pro- jectiles was made by the British Government. The whole of the guns were new Lowmoor 32-pounders, of 58 cwt. The mean of 42 samples of the iron gave a tensile strength of 28501 Ibs. per square inch. The systems were as follow : RIFLING AND PROJECTILES. 501 Britten's. (The projectile used on this occasion is shown by Fig. 277.) Expanding projectile ; lead attached by zinc ; weight, 47 Ibs. Five grooves, 2 in. wide and -062 in. deep ; one turn in 48 feet. Thomas's (Fig. 260). Expanding projectile ; lead mechanically attached; weight, 55 Ibs. Seven grooves, 1*8 in. wide and *1 in. deep ; one turn in 18 feet. Jeifery's (Fig. 274). Expanding projectile ; lead mechanically attached; weight, 45 Ibs. Seven circular grooves, 1*65 in. wide and '12 in. deep ; one turn in 64 feet. Haddan's (Fig. 213). Centering system ; projections cast on the shot ; weight, 51 Ibs. An expanding wad or a wooden sabot were used. Three circular grooves, 3*4 in. wide and "15 in. deep ; one turn in 25 feet. Lancaster's (Fig. 211). Centering system ; oval bore, with *6 in. difference of axis. Projectile planed to fit the twist of the rifling ; weight, 45f Ibs. ; one turn in 20 feet. Scott's (Fig. 224). Centering system ; wings set to the angle of the rifling, cast on the projectile ; edges planed, and faced with zinc ; weight, 38f Ibs. Three grooves, l'S75 in. wide and '225 in. deep ; one turn in 48 feet. 593. The estimated cost per thousand of these projectiles was Scott 40 Ibs $922-25 Haddan 47^ Ibs 967-25 Lancaster 49^ Ibs 971 Jeffery 49 Ibs 1476-25 Britten 47^ Ibs 1527- Thomas. 54^ Ibs 2420-50 Smooth-bore, 32-lb. shell 22 Ibs 438*50 Do. do. shot 32 Ibs 429-25 The estimated cost of the rifling was $1.87 to $2.50 per gun. 594. In order to perfect the various systems for final trial, some preliminary experiments were undertaken during 1859 to 1861, the order of merit being as follows: Haddan, Britten, Jeffery, Scott, Lancaster, Thomas. The results are shown by Table 100. 502 ORDNANCE. 195. In the subsequent trial, the following systems were also introduced; weight and character of guns the same. The French plan (Fig. 197) ; centering system, 3 studs faced with zinc ; weight, 59*5 Ibs. Three grooves, 1*919 in. wide, and 2363 in. deep ; increasing pitch from to 4*652 in 88*548 calibres. Armstrong's shunt (Fig. 247) ; centering and compressing sys- tem ; zinc ribs ; weight, 50*5 Ibs. Three grooves, 1/25 in. wide and *18 in. deep; 1 turn in 28 calibres; and The smooth bore 32-pounder. The results of this trial are given in Table 102. To obtain a direct comparison of range, it was then determined to make a new trial of the best systems, with equal relative charges of ^ the weight of the shot. The Armstrong 40-pounder was here introduced. Weight of shot, 41*06 Ibs. ; compression system; 56 grooves; one turn in 36 calibres. The results are shown in Table 99. The velocities of the various projectiles are given in Table 101. 59 O. ENDURANCE. The endurance of the guns is shown in Table 94. TABLE XCIV. ENDURANCE OP COMPETITIVE RIFLED GUNS. GUN. No. of rounds in experiment. No. of rounds fired at proof butt. Charge, Ibs. oz. Weight of projectile. Total endurance. Britten 363 1123 5 o 50- 1486* Jeffery "3 250 5 8 47' 363 Lancaster ... 200 1800 6 o 50- 2000* Haddan *s 9 7 o 54.12 215 Scott 1OQ :oo Shunt 3*7 3^7 French 107 107 * Not burst. RIFLING AND PROJECTILES. 503 The Committee report that Mr. Britten's system obviously strains the gun least, and that the high endurance of some of the others was out of all proportion to the strain imposed, and may be ac- counted for, especially in Mr. Lancaster's case, by the accidental superiority of the iron. The following mechanical considerations favor this view of the case, but the Committee's opinion is chiefly based on the great endurance of several other guns rifled on Mr. Britten's system, as shown in Table 95. 597. The Committee believe that the liability of the projectiles to jam in the bore, is in the following order : Lancaster (most liable), Scott,* Haddan, French, Shunt, Thomas, Jeffery, Britten. 598. The Committee believe that the liability of the gun to be burst, from the direct strain of rotating the shot, is as the sine of the angle of the rifling, which for the guns mentioned is shown in Table 96. 599. The cup at the base of Mr. Jeflery's shot, and the sliding ring at the base of Mr. Lynall Thomas's, appeared to upset the lead with unnecessary friction. It was assumed that the French shot got through the bore with the least friction. GOO. The driving side of the grooves, especially of Mr. Brit- ten's gun, was somewhat worn by the lead. The grooves of Commander Scott's gun were not perceptibly worn by the projectile. 60 1 . ACCURACY. The order of accuracy in the two trials was as follows : First Trial. Second Trial. Haddan, French, Britten, Shunt, Jeffery, Jeffery, Scott, Haddan, Lancaster, Britten, Thomas. Lancaster. * Reference to Commander Scott's rifling (535) will justify a difference of opinion. The inertia of the shot simply tends to rotate the gun in the opposite direction ; not to open it by the radial strain, due to wedging in the bore, as in the case of "Whitworth, Lancaster, and Haddan (See experiments at Woolwich 644). 504 ORDNANCE. TABLE XCV. ENDURANCE OF CAST-IRON GUNS RIFLED ON MR. BRITTEN'S SYSTEM. GUNS. Charge. Shot No. of Bounds. Eemarks. 56 cwt. 3i-pdr No. 24 Ibs. C . C Ibs. 48 IO tt it 72 JO it Q6 IO i< c< it lie IO (C ( tt 1 4.0 IO 161; 4 /Burst at 55th round, 56 cwt. 32-pdr. No. 1339 ti tt 48 IO IO \ March, i86a. tt tt 06 IO <{ tt yu I 2O IO <( tt it 144 I 6l 10 ("Burst at 58th round, 95 cwt. 68-pdr. No. 6095 7-5 M 1U 3 90 1 2 c IO IO \ June, 1862. < 180 IO M ( IO tt ( **5 IO 95 cwt. 68-pdr. No. 6439 68-pdr No 8282 .. M 7-5 315 Same order 8? 10 60 f Burst at 6ist round, \ April, 1862 Not burst. 68-pdr bored to 32-pdr 5 JV-"J I IO Not burst The Committee state that the comparative inaccuracy of Com- mander Scott's system was attributed by him to bad boring and rifling. The superior straightness of ricochet on land and water, also claimed for this projectile, the Committee do not consider of much importance. RIFLING AND PROJECTILES. 505 TABLE XCVI. PARTICULARS OF RIFLING OF COMPETITIVE GUNS. Name of system. One turn in calibres. Angle. Sine of angle. Bearing. Approximate area of Bearing surface. Guiding edges. Teffery .. 120 90 90 . / I 30 a 2 at muzzle \ * 53J 0262 .0349 .0349 Lead Zinc M sq. in. 26-2 2O- 19.5 4-7 sq. in. 2' I I 3-9 0.6 Britten Scott French . I Lancaster ... 56 3 13 0561 Iron 3-75 0- Haddan 47 3 49 0666 g 4 i Thomas Shunt 3 2 28 5 '7 6 24 0921 1115 Lead Zinc 34-6 7-7 1.9 2-4 602. ADAPTATION FOE KOTJND SHOT. That rifling which left the largest part of the original bore untouched, was most effective with, and least injured by, round shot. Lancaster's system was most inaccurate ; beyond 1000 yards it was impracticable. The 4 rifled gun, with shallow grooves and broad lands, fired sphe- rical shot more accurately than the smooth-bored gun,* as shown by Table 103. 603. The windage added by the grooving, in the various sys- tems, is shown in Table 97. 60 1. Commander Scott's system has the advantage in this par- ticular. But windage is not necessarily a disadvantage. It may be stopped by a sabot, or the charge may be increased without increasing the strain on the gun (649 note). 6O5. EFFICIENCY OF PROJECTILE. This involves initial velo- city and capacity for bursting charge. Mr. Britten's shot had the highest initial velocity of those tried with T ^ charges. The velo- * The round shot, especially when fired with a sabot, undoubtedly received a spin- ning motion from the rifling. 50G ORDNANCE. TABLE XCVII. WINDAGE OF COMPETITIVE RIFLED GUNS. Lancaster 2 '955 square inch Haddan 1-37 " French 1-36 " Thomas... 1-26 " Jeffery 1-14 square inch. Britten I oo " Shunt 0-67 " Scott 0> 53 " city of Commander Scott's projectile was not ascertained, but its superior powder capacity, for a given weight,* is shown by Table 98. TABLE XCVIII. BURSTING CHARGES OF SHELLS. TRIAL OF 1861. Name of system. Weight of shell empty. Bursting charge. Relative weight of bursting charge of shell. Scott Ibs. 78.8 Ibs. 4" oz. I "? o 1 24. Shunt CO C 5' I \ O I I C rn .A O -OQO 4.5 -8 7 o -076 Britten 46 Q 7 O O7'J Haddan r T . I 6 o o6c Tefferv 3 X 4.r .4. 2 8 O CK C Thomas r r . i I O O2C 606. LIABILITY TO INJURY. In this particular, Commander Scott's and Mr. Haddan's projectiles have a very great advantage over those coated or studded with soft metal. The former have the further merit of a shape easy to handle and to pile. A fall, or any rough handling, would obviously mutilate the lead cup of Mr. Jeffery 's shot. 607. CONCLUSIONS OF THE COMMITTEE. Mr, Lynall Thomas's system, of which the disadvantages are obvious, from the fore- *It should be observed that the ribs on Commander Scott's shell strengthen it ma- terially, and allow the use of somewhat thinner walls and a higher bursting charge. RIFLING AND PROJECTILES. 507 going tables, is not even mentioned in the Committee's conclu- sions.* Indeed, Mr. Lynall Thomas has subsequently adopted the centering system (538). The first place is awarded to Mr. Bashley Britten, on account of the small strain upon his gun, with high initial velocities. Mr. Jefiery's plan is rejected, because several guns thus rifled have showed a low endurance ; and because the lead on the pro- jectile is greater in quantity, more easily injured, less simply attached, and productive of greater friction, as compared with Mr. Britten's. Mr. Iladdan's system was rejected on account of the weight of the projectile, and the heavy wood sabot (1 Ib. 5 oz.) placed behind it. His rifling was also calculated to burst the gun. Commander Scott's system was rejected on account of inferior practice, and the low endurance of the gun. But this rejection was qualified by the explanations already mentioned. Mr. Lancaster's system was rejected for irregular practice, with elongated as well as spherical shot. Finally, the committee avow a considerable distrust of cast iron, of the quality turned out by English foundries, as a material for rifled cannon, except with such restrictions as to charge as would limit them to the use of howitzers. The systems of Commander Scott, Mr. Lancaster, and Messrs. Britten and JefFery (the two latter in one gun, with Britten's grooving), also the French system, are to be tried again, on a larger scale, and with the improvements suggested by previous practice. The guns (7-inch bore and 7-J- tons weight) are in pro- cess of completion at Woolwich. The inner tube is cast steel, hardened in oil. In other particulars, the guns are similar in construction to the Armstrong muzzle-loading 110-pounder, and in capacity to the "Whitworth 7-inch rifle.f * Mr. Thomas declined firing the eighty-two remaining rounds allotted to him. f Since the above was written, the trial of these guns has commenced. See Ap- pendix. 508 ORDNANCE. PH g^ 3 Q rt Mean reduced VO C< Will COOO COilOO deflection. w CO VO H CO d M VO ^~ tfean observed deflection. ^ -* M ~ OOVOCOOOO^ClON vorit^-<4-cvort w M r Mean ? ? ? oo vOThvOcJ^OOrJ-^ difference of range. CO M.^ONVOTj-w rJ-VO Tj- cl d c4 vo co O vo 1 i? 1 ^ f*> l-l M CO CO tovoooMcivorJON r\O >-i ONOO O voo H rf-O ONd ONt~^M S 1 H OB f- VO VO go ON ro f*> M tH CO c) ONHvo vo'i-^-oo >o HVoOO^J-ONOOrt rt co 1-1 c> co t-t co d 9 . VO M H vo co rt P ON oo rl M CO to oo O vovovooOVO t-^OO t^. ^H TJ-VOONCOI-I ro Tj- ON ON 00 00 VO O !tlean reduced time of flight. O ** oo rj- rt co CO VO >H oo CO Tj-^Tj-rJ-rJOOOO rJ-voONi-iVO t^t^-r^- VOMC> a ^_ ^ ~ ~ ~T3 * ~ > * 1 * * 3 ^, a RjFLING AND PROJECTILES. 509 ; VO co ON T$- f* COM t^ <$ ;cMOOMOHicocJ co ^ vo * I s s vo ^ 7 ^clHiclcooovjHicoc* k ; OO c< r O vo t-^ oo & O HI ^J- vo rl ONt-^^J-OO t^. ^" co cJ co HI d co vo O co d cJ O HI QS ^- i-* f$ Os OA co co t^ vo co t^ d O d O O O c* oo oo d t^ co o HIMcJCO i_irO MCI ; t^t-^'tl-ONt~>.oo o HI o oo o\vo o t^O t^-vovo ; o o 'i-ONoo cor^coHi M M co HI co MM ; t-~M cocl t-scocovo O VOVOMCHICOVOOOf>. ; C?\ONMOOOO c*vo M r^ HI CO M CO MM : *'*OOVO O t^O C<00 : o * * * ooo cooo co vo HI ^ vo d d vo oo ____^ HH , IH p>clvoOcJvoOc T^- to to to CO CO to oo to t- 6 vo co oo vo CO 6 00 ON O 00 to c O t^ vo ON Tj- oo to vo vo O VO to to I "* 00 HI 00 HI O H " HI CO HI CO tJ CO ON HI O W CO d <* to ON ON CO" f ! 1 M OO VO ON t^ CO HI HI ON vo co d O ON M ON rt HI co " HI CO HI CO Cl CO CO Cj CO O t< rt H CO tJ ; to 5- CO oo o VO CO c to ^ vo to O t^> ^ t-^ OO t^ ON ON HI O r^ Tj* 00 VO VO oo ON ON ON CO to to VO 00 to o VO HI Mean reduced ~"*~~. co O oo t-- N 00 '~*~I M CO oo _ time of flight. ^ o ~ ? T^T CO VO M VO HI VO HI C to vo Elevation. to O to O to O to O to to to Mean weight of projectile. ^ ^ ^ ^ M t^ CO HI VO vo O i s i 3 VO VO to ^ 3 B 44- 2.- ,v VO VO 3 t-- 3 3 No. of Eounds. co ON OO to O ^* tl . M M M (1 M s o s to to Direction and force of wind. to ^ ^4B C*l 3 1 ^^ ^^- t^ CO "5 t\ CO -l 3 Thomas.. .... 3 3 GO O fc CO 1. d RIFLING AND PROJECTILES. 511 1. gl S^' O O O O 000000 ; VO vo 00 CO ?l t.&MMM 1-1 d d H ; M M rt d d d d 1 vo d i-~ ^ t t^ oo ^. ^ aj O 1 5 CO W CO ON t~^OOd CO OO I Cwood TJ- i-x^-t^;ONOO ; ; 1-1 O 00 vo O O 3 * 3 f ! r* vO M M vo CO oo * f ONCOI^ vo voONOO It^.r-^ *iOVOt~- ^h ONVOt-^ON' 'ONd ddd d coovo::i-id : * 1 ll t*^ ON ^f* ^J" ON t*^ vo O co t^> d vo 's a dONCOl--. rl- Tj-d"-icot^ooOON ON vo vo co oo vo vo vo t^ vo ON >H l-ldd d COOWVOONONHld vo oo f- VO -< *" "S f" ~N VO VO T}- <3-vo ONOO d vovo dvovovo vovo vo vo a cS S i VO vo VO VO VO vo VO VO vo vo VO ^* ^~ * * 1" OH O f~- M VO vo co co d vo vo I 1 coQd ONVOdMi-cThmO S6oo4- M vOr}-vo iivo^-vo vo vovovoj^ ^ ^ *^ T ^0 13 13 _0 "S C/3 C/3 C/3 C/3 55 1 * 1 NQooO O OooooOdt-.OO ^vovot^ vo l^.vovoOcodvovo T*- VO No. Rounds. vovovo vo vovovOOvovovovo VO VO . | | & -Q T3 G h 4* ^ s - 1 .. fe M e a 111 Jill j-i aj i_2 c3 7^ (_i _C N ^ CQ ) , ffi i-J Hfea>co <3 512 ORDNANCE. 00 I tyi co Q Area of rectangle. < ON vo vo CO vo ONCOM w vo t^-OOO M vo oo coo O rt ^* ^ vo ONW c> VOM --l ONONt--VONOO COO H ONOO coQ i-ivo ONM VOM MCOwdCO ClCOM * 1 M ^^t^^-oovo cooo COM JOVOOOVO M COVO ON^r-~vo OO^MrtvoodvOM ^i-irtcowpicoi-ieJcoM d ,00 VOOOVO M T*-C< <-> t*~ & co cl vo co vo H ^i" H t^ ON " Mean reduced time of flight. OO O voONTj-ONt^.^-vo c< Elevation. dvoortvoOd.voOrt Mean weight t^ vo vo vo of projectile. "~~ O t-~ ^t- co Charge. vo vo vo f^ vo VOVOM voincl vo^-H ON I VO vOvOVOVOVOVOvovoVOvo 00000000000000000000 c4 covocl covod covoH bjbbjbbobbbjbbbbbbjbbbbjo 3333333333 NAME OF SYSTEM. C 2 -* >,*"* ""*:^ aj -. -T-) 1 ^ (8 i * S M RIFLING AND PROJECTILES. 513 00 M HI CO CO VO VO 00 Tt- M c< cl ft ^. *st c) ^J- O Os co CO VO HI CO H vo OO f Os vo 00 HI VO ^. ^. ^- cJ VO *^- OS vo * * VO ^ ^ 00 H vo 00 o VO 00 VO A VO H HI M A CO j^ d vo co rj- co c< c* ON vo Os 00 c* M VO VO HI l^ VO Cl VO vo vo t-- Os o VO VO l^s VO OO VO CO VO CO HI HI H. M HI Tj- CO 00 oo t-. HI HI CJ C CO CO e oo CO VO VO CO VO vo 00 M VO VO OO cJ d f* Cl vo VO Os OS 00 M HI C< CO CO CO l^ Os O O co oo oo M vo t~^ vo O O 8O\ CO HI HI CO CO oo oo HI rfr- CO oo oo <4- O f^ VO M 00 CO 00 HI oo oo CO CO VO vo c? HI It <* vo vo vo - oo Os VO ^. vo 3 a VO vo VO VO vo vo ON r^ *D * oo VO <-** * ~ CO ^ - ^ - oo oo HI l-< W U VO vo oo oo HI HI - vcT - tC 4J 4J VO oo M HI VO oo vo 4J - CO CO CO CO co CO : c ! i) - o """"" JS y ~" g c 9 _ o -^ Z 3 ?l% 1 I | i a -% 3 i c % $ fig 5 48 j I I i g 1 l H! 5 l ~ I 45 g S % t> 3 |}l "E <=i 03 ^3 3 1 i 1 1 33 514 ORDNANCE. Area of rectangle. O 10VOOO ON rt COON ^- vo vo M Tj-vovo ON K! vo ON O doo ON >-< tf M tf VO OO ON M vo ON vo co O Mean reduced deflection.:}: ^ to vo 10 M c Tj-w M Mean observed deflection.t co ON ONCOOO O n ONCOOO 'O ^- OO vo c* VO ON CO Cj c< O oo Mean difference of range.* ONt^O rt vo vo ONC ^OO w ONTt-VOTj-VoVO P*H VOCOcJ T^OO t< W O ^ co oo VO CO rj- t * 1 r--O ONOOVOoo ONON l-s CO d F- fl T^- VO ON ON 1 5 A M ONrOrdONVOT- t--OO T>-OO t>i-i O t^ t^OOoot--OOON ^ M CO CO M CO M O ^ c c< c i ^-ONOOOO rt-ci t^oo ^vo Tj-oovooo ^-M ON ^vo ONOO t^-vot-^ONOo r< co CO 00 00 00 Mean reduced M OvH(4 ON H COM O ONQOOOO O ONON rt co of flight. vOQi-icJvowrtrt VO vo Elevation. o voQO CO C/5 CO a a- a. u u w CO C/3 CO i 1 a i 3 rt o ^ 8 -C u C/3 (73 3 .2 P ^ 516 ORDNANCE. TABLE GUI. SHOWING THAT THE RIFLE is MORE ACCURATE THAN THE SMOOTH- BORE, WITH SPHERICAL SHOT. GUN. No. of rounds. 1 s Time of flight. RANGES. Mean dif. of range. Mean obs. de- flection. Mean reduced deflec- tion. Min. Max. Mean. // yds. yds. yds. yds. yds. yds. Smooth - bored 32- pounder r (. 20 2 5 3.40 not obs. 1027 1823 1329 2222 1 146 1994 5"7 70-8 8-1 9.8 2-6 8.9 32-pounder rifled on C 20 2 3'59 1063 I26o 1172 32-6 7.8 2-7 Britten's plan } i shallow Grooves... I 20 5 6.59 1821 I 9 88 1882 24-9 5-8 5.8 Charge, in all cases, 10 Ibs. ; shot, 32 Ibs. DUTY OF RIFLED GUNS. 6O8. The possibility of making very long ranges useful in land service, where the gun-platform is fixed ; the immense superiority of rifled projectiles for breaching masonry* (273) ; the advantage of * "An account of some experiments carried on in this country, to test the respective powers of rifled and smooth-bored guns, in breaching masonry at a long range, viz., 1032 yards, is given in the Proceedings of the Royal Artillery Institution (27 2). With regard to these experiments, the Ordnance Select Committee made, in their Report, the following remarks : ' It appears that, irrespectively of the superior concentration of the fire of the rifled guns, and its consequently greater effect, they actually per- formed half as much work again as the smooth-bored guns, with the diminished expenditure of iron and gunpowder noticed in a previous paragraph.' Again : 'The precision with which the guns could be directed upon any point it was intended to strike, gave them advantages with which no smooth-bored ordnance, firing from such a distance, could compete ; and the same circumstances would have rendered it almost impossible to retrench or defend the breach, for the fire might have been continued, with perfect safety to the assaulting columns, until they were within a very few yards of it, sweeping away all obstacles as fast as they could be laid, and without the slightest interruption from the musketry of the defenders, the battery being quite out of their range.' "An abstract of the Prussian experiments at Julich, in 1860, is given in the 'Pro- fessional Papers' of the corps of Royal Engineers. The conclusions drawn from these experiments were : ' That rifled ordnance can be employed advantageously for firing at a covered object, not visible from the battery, at longer ranges than smooth- bored pieces ; that reduced charges may be used successfully with projectiles from rifled guns ; that the effect of the shells from these pieces is so great that no other RIFLING AND PROJECTILES. 517 rifled guns on shipboard, for supporting troops and shelling* dis- tant worksf and encampments, and their occasional excellence in operating against armor (250), warrant every effort that can be made to improve this new and (considering both land and sea service) most useful branch of ordnance.:f kinds of ordnance are required for breaching ; that 13-lb. shells, fired from rifled guns, are sufficient to breach quickly a good wall, of moderate strength; that 27-lb. shells, from the same pieces, can destroy, in a short time, embrasures in the strongest masonry; and that 57-lb. shells, from rifled guns, can breach, with a comparatively small expenditure of ammunition, the strongest masonry.' " Maj. C. H. Owen, Jour. Royal U. Service Inst., Aug., 1862. *The bursting charge of the 110-pounder Armstrong 7-in. shell is 8 Ibs. ; that of the 68-pounder 8-in. shell is only 2 Ibs. f " The practical object of attaining exceedingly long ranges must be for attacking any fortified place, or for bombarding a naval arsenal, so as to be able to fire all day and night, still keeping out of the reach of the enemy ; and to drop shots and shells with impunity into apparently inaccessible places, so as to cause, if not absolute ruin, at least very considerable annoyance, to any naval arsenal or maritime estab- lishment. It was a very material element to be able to lower the elevation, as, by that means, the accuracy of the firing was increased, or a longer range with the same elevation. Thus, for instance, with 2 of elevation, the range, with a velocity of 1000 feet per second, would be 730 yards; with 1300 feet per second, it would be 1230 yards; with 1500 feet per second, it would be 1620 yards : the latter velocity giving the same accuracy, at double the range, which the initial velocity of 1000 feet could command." Mr. Bidder, Prest., "Construction of Artillery " Inst. Civil Engineers, 1860. "A 32-lb. shot, fired from an Armstrong gun, at 33 of elevation, ranged 9153 yards. "A 3-lb. shot, fired from a Whitworth gun, at 35 of elevation, ranged 9688 yards. "A 175-lb. shot, fired from a gun of Mr. L. Thomas, at 37 of elevation, ranged 10075 yards. "All these ranges being obtained at very high angles over 30 the 'angles of descent' of the projectiles must have been very great, so that the chance of striking an object in this manner would not certainly be worth the powder expended. The difficulty of judging the distance, of laying a gun upon an object at a long range, and of observing the effect of the fire, also the disturbing influence of the wind, during a long time of flight, will confine the ranges of projectiles used for military purposes within 2000 yards; or, perhaps, in special cases, when firing at masses of troops, ships, buildings, etc., to 3000 yards." Maj. Owen, Jour. Royal U. Service Inst, Aug., 1862. ^ Mr. Benjamin Robins made the following often-quoted prediction, one hundred years ago : " I shall, therefore, close this paper with predicting, that whatever state shall thor- oughly comprehend the nature of rifled-barrelled pieces, and, having facilitated and completed their construction, shall introduce into their armies their general use, with a dexterity in the management of them, they will by this means acquire a superiority which will almost equal any thing that has been done at any tune by the particular 518 ORDNANCE. While certain conditions of success are common to all rifled ordnance, the kinds of work to be done are so various, that some special provisions would appear to be required for each. It is proposed to consider briefly the principles of rifling, the require- ments of each service, and especially the features of the most generally useful rifled gun and projectiles for small casemates and turrets, where the armament will certainly be limited, if the pro- tection is adequate.* As far as iron-clad warfare is concerned, velocity is obviously the most important consideration ; 1st, because the penetration (smashing is better done by spherical balls. (See 193) is as the weight of the shot into the square of the velocity ; 2d, because, at the necessarily short ranges of iron-clad warfare (253), the small increase of accuracy due to improved balance of shot can hardly compensate for the inaccuracy due to an unstable plat- form; 3d, because a high velocity gives a low trajectory (640). 609. OBJECT OF RIFLING. The object of rifling is to diminish, as far as possible, the deviations of ordinary shot, due to the follow- ing causes : 1st. Want of uniformity in figure and weight around the longi- tudinal axis of the shot passing through the centre of gravity. 2d. Position of the centre of gravity before or behind the centre of figure. 3d. Resistance of the air. excellence of any one kind of arms ; and will fall but little short of the wonderfu effects which histories relate to have been formerly produced by the first inventors of fire-arms." * Commander Scott specifies the following requirements of naval guns (Jour. Royal U. Service Inst., Dec., 1861): " A naval gun then should, 1st. Be simple in its construction. 2d. Be not liable to injury from blows or weather. 3d. Fire a shot of large diameter (from 8 to 10 inches or more). 4th. Be able to use the smashing round ball at close quarters. 5th. Give a flat trajectory. 6th. Have projectiles which deflect little, and ricochet straight and evenly. 7th. Fire elongated molten iron shells. 8th. Fire elongated powder shells, near or across ships, &c., with safety. 9th. Fire shrapnell or built-up shells over boats with safety. 10th. Fire canister." RIFLING AND PROJECTILES. 519 In addition to these causes of inaccuracy, the following are common to all projectiles, and cannot be modified by rifling : The action of wind, the rotation of the earth, and the want of horizontally of the axis of the trunnions.* 010. I. By rotating the projectile around its longitudinal axis, the direction of these deviations is so rapidly shifted from side to side, that the shot has no time to go far out of its course either way. 11. As an elongated bolt can be steadied by this rotation, a given weight of projectile can be put into such a form as to oppose the least practicable cross-sectional area to the air, and thus to receive the least practicable retardation of velocity. The cross- sectional area of a 100-lb. spherical shot is 67*1 ; that of the Par- rott or Armstrong 100-lb. rifled projectile is from 32 to 38*5 square inches. 611. The resistance of the air is assumed to be as the squares of the diameters of the projectiles,f or, in this case, nearly as 4 * " We have no levels for adjusting the trunnions, and therefore, when a piece is elevated for a long range, there is no certainty that the axis is in the vertical plane of the point aimed at. " Our sights for cannon are of the most clumsy construction. There is no difficulty in applying a telescope and quadrant to our guns, intended for a long range, with such adjustments for collimation, that at the distance of 4 or 5 miles the chance would be in favor of hitting a target of 50 feet square every time. If any one will look at the impression made by the shot from Parrott guns on the Crow's Nest, the only opinion he will have will be, that the sighting for the direction in altitude is better than that for azimuth. Telescopes for this purpose should have semi-object glasses and lenses." G.W. Blunt. \ " If an elongated shot and a ball of equal weight be fired with the same initial velocity and angle of elevation, the former will be less retarded, and will consequently range farther than the ball, for the diameter of the elongated projectile being smaller than that of the ball, the elongated shot will not oppose so great a surface to the resistance of the air as the ball. For instance, if a 12-lb. Armstrong projectile and a 12-lb. ball be moving with the same velocity, the resistance of the air being assumed to vary as the squares of their diameters, The diameter of the 12-lb. Armstrong shot=3 inches. " " ball=4. 5 inches. Therefore the resistances will be as 9 : 20-25, or I ' 2-25. From which it appears, that the resistance opposed to the ball is more than twice that which acts against the Armstrong projectile ; and this comparison, though rough (for 520 ORDNANCE. to 1. At a velocity of 1200 feet a second, which is about the initial velocity of rifled cannon projectiles, An Armstrong loo-lb. shot will be resisted by a force of 432 Ibs. " 40-lb. " 203 Ibs. " ao-lb. " i ay Ibs. " 12-lb. " 79 Ibs. Therefore range as well as accuracy are greatly promoted by rifling. 612. Accuracy.* The specific effect of rotating the shot is thus stated by Mr. Longridge :f 613. WANT OF SYMMETRY. "If the material of the shot be not homogeneous, or its form be not symmetrical, the resistance of the air causes the projectile to deviate from the true line of flight. Again, if the centre of gravity be behind the centre of the figure, the shot will turn over. Lastly, if the shot leaves the gun with a rotation arising from striking or rubbing against the inside of the chase, and is not determined by any specific direc- tion, it will fly off to one side, or the other, according to the acci- dental circumstances under which it leaves the gun. "In Fig. 290, let A B be a shot projected in the direction of the arrow. Now, if the front end be not symmetrical, but be formed as shown at B C, it is evident that the resistance of the FIG. 290. FIG. 291. r ^ air will cause the shot to deflect in the direction D E (Fig. 291), and that its path, as projected on a horizontal plane, would be a curve to the left of D G. If, however, the shot rotates on its the obliquity of the axis and the form of the point of the elongated shot are not con- sidered), is sufficiently accurate to account for the results obtained in practice. "- Maj. Owen, Prof, of Artillery, Woolwich. Jour. Royal U. Service Inst., Aug., 1862. * See also Competitive Trials of 1861 (592). f Appendix to "Construction of Artillery." Ins^. Civil Engineers, 1860. RIFLING AND PROJECTILES. 521 axis, the extent of lateral deviation is limited, and the shot is brought back from E towards the axis D G. Now, it is generally stated and believed, that this retrograde motion goes on, until the shot reaches a point F, as far to the right of D G as E was to. the left, and that, in fact, the shot travels in a spiral around the axis D G, its greatest deviation, at any part of its path, being the dis- tance E e or F f. This, however, is not the case. The path of the projectile is of a much more complex form, and results in a deviation, increasing uniformly with the distance from the gun, and depending as to its direction on the direction of the deflecting force, at the moment of its first application. If A be the gun (Fig. 292) seen projected on a horizontal plane, and the deflecting force acts on the shot as it leaves the muzzle, in f a vertical direc- tion downwards, the general projection of the line of flight will be a line A B, deviating to the right, or to the left of A C, according as the twist is left, or right handed. If the deflecting force acts in the opposite direction, the shot will be deflected to the right of A C, and whatever be the direction of the deflecting force at the first exit of the shot, the deviation will be a uniformly increasing one at right angles to it. But the line A B is not absolutely a straight line ; it is a curve of double curvature, and if projected on a vertical plane at right angles to the axis A C, would consist of a series of cycloidal curves (Fig. 293), increasing the distance -c of the shot from A C by the length A a of one of these cycloidal curves at each revolution. The length of each of these cycloidal curves depends upon the amount of the deflecting force, and the number of them is equal to the number of revolutions made by the shot in its flight. The formula for calculating these curves is given in the note before referred to, and Table 104 gives the results as calculated for the several guns therein mentioned, and the aggregate deviation from the line of axis of the gun, at a distance 522 ORDNANCE. of 1000 yards, and for a deflecting force, which would have given a deviation of 10 yards to a non-rifled shot, projected under the same circumstances." TABLE CIV. TWIST AND DEVIATION. Name of Gun. Amount of Twist. Number of Turns in 1000 yards. Breadth of Cycloid. Length of Cycloid. Total Deviation in 1000 yards. Haddan I in co ft. 60 -j.lj.th of an inch Armstrong i in 10 ft. 7OO gglg-^th of an inch y^Tjth of an inch 600 614. "The aggregate amount of deviation, even with the very slow twist of Mr. Haddan's gun, is very small, and this teaches, that as far as the correction of the deviation, due to want of sym- metry, is concerned, the more rapid twists of Mr. Whitworth's and Sir W. Armstrong's are unnecessary. " It is, however, necessary that the rotative momentum be suf- ficient to keep up the spinning motion to the end of the flight of the shot, and this may require a greater degree of twist than would be required simply for the purpose of correcting the deviation due to the deflecting force. Experiments are wanting, to show the decrease of rotation due to the friction of the projectile in the air. In Mr. Haddan's projectile, with an initial velocity of 1300 feet per second, the number of revolutions would be twenty-six per second ; and it does not appear likely that this would be much reduced in the few seconds of the projectile's flight, even to its most distant range. Therefore, in this respect also, the rapid twist adopted by Mr. Whit worth and Sir W. Armstrong appears unne- cessary (619). 61o. CENTRE OF GRAVITY. " The next point for consideration is the influence of the position of the centre of gravity before or behind the centre of figure of the shot.* The gyroscope affords * " It was also found, in the experiments tried by the French Commission, that when the centre of gravity of an elongated projectile was near the front, the point of RIFLING AND PROJECTILES. 523 an excellent means of illustrating this. If a weight be attached to the axis of this instrument, when in rotation, the axis will deviate in the same direction as the rotation, if the weight be behind the revolving disk, and vice versa. " The velocity of this horizontal deviation of the axis is smaller as the rotative velocity is greater. If, then, in a rifled shot, the centre of gravity be behind the centre of the figure, the shot will deviate to the right, with a right-handed twist. If, on the other hand, the centre of gravity be forward, the deviation will be to the left ; and these deviations will be greater as the velocity of rota- tion is less ; that is to say, as the twist is slower. Here, then, the advantages of a rapid twist are manifest, but it must be borne in mind that the deviation here sought to be counteracted is solely due to the centre of gravity being placed before or behind the centre of the figure ; and if these centres coincide, no tendency to deviate exists (243). 616. FRICTION AGAINST THE AIR. "The next cause of devia- tion is from the friction of the shot against the air. If a body be revolving rapidly in any fluid pressing equally against it in every direction, it is obvious that; the only effect of the fluid is to dimin- ish, and finally to destroy the velocity, without changing the posi- tion of the axis A (Fig. 294). But if the fluid press with a greater force on the side B, for instance, than on C, the axis will move in the direction D. PIG. 294. Again, if the velocity of motion be greater at F than at G, the tendency is to move the axis in the direction 'A C. 617. Now in the case of an elongated rifled shot both these actions take place. The pressure of the air is always greatest such projectile drooped below the trajectory, in its flight ; that when the centre of gravity was near the rear, the tail drooped ; but that when the centre of gravity was in the centre of the length of the projectile, the axis of such projectile remained coin- cident with the line of trajectory throughout its flight. It was obvious that the resist- ance of the air would be at a minimum in the last case, and this explained the im- provement that was effected in the range of the Whitworth projectiles, by tapering them in the rear as well as in the front." Mr. Conybeare, " Construction of Artillery" Inst. C. R, 1860. 524 ORDNANCE. on the under side, and consequently the axis is moved in the direc- tion of the twist. Moreover, the side F is always meeting the air, with the velocity due to the sum of the velocity of rotation and the falling velocity of the shot ; whereas the opposite side is meeting the air, with the velocity due to the difference of these two ; con- sequently, the effect is to roll the shot upwards, in the direction F II, and sideways in the direction B K ; the actual result being a deviation in some intermediate direction A M. 618. "The deviation above considered, which is unavoid- able in all rifled shot, is greater as the twist is greater, and may possibly vary as the square of the velocity of rotation. i. c., as the square of the rate of twist. It will probably, also, be a good deal affected by the nature of the rifling, being, of course, greatest with a rough rifled surface. " The deviation due to the friction, as last described, is always in the direction of the twist. It may therefore be, to some extent, counteracted by the gyroscopic deviation of the shot, if the centre of gravity be placed in advance of the centre of the figure. This gives a deviation to the side opposite to the direction of twist, so that the actual deviation is, in one case, the sum, and in the other, the difference of the two deviations." 619. As to the rate of twist, Captain Blakely says:* " Many experiments have been made, with a view to determine the exact length of bullet each degree of twist can steady. Amongst others, I may mention those of Mr. Dove, of Glasgow, who had a set of steel barrels rifled, of precisely the same length, weight, diameter of bore, and shape of groove ; the only difference being in degree of twist. He found that, with one turn in 50 diameters, he could fire a bullet three-and-a-quarter diameters in length; with one turn in 60 diameters he could use a bullet 2f diameters in length ; with one turn in 75 calibres the bullet might be a little more than If diameters in length. 620. " The Swiss Government about the same time made simi- lar experiments, and determined on the use of a military rifle, * Journal Royal United Service Inst., March, 1861. RIFLING AND PROJECTILES. 525 T 4 oV in. in bore, throwing a bullet 2 '44 calibres long, with only one turn in 80 calibres. The apparent discrepancy of these results is explained by the very great charge of gunpowder used by the Swiss. Their bullets weighing less than half as much as the En- field or Mr. Whitworth's bullets, a man can use a charge of pow- der which would disable him if he attempted to use it with a heavier bullet ; he consequently obtains much greater initial velocity. 65J 1 . " General Jacob made, perhaps, the most extensive series of experiments ever undertaken by an individual. He found that a bullet 2-J calibres in length could be kept point foremost by firing it from a barrel with a twist of one in 57 calibres, even when the point was lighter than the base. While General Jacob and Mr. Dove were making experiments at their own expense, Mr. Whit- worth was making some at that of the country. As he has taken out patents for any improvements he has made, they can be accu- rately ascertained from his published specifications, so I need only briefly refer to them. The bullet he wishes to introduce into the military service of this country is 3 calibres in length, and weighs 520 grains. With 80 grains of powder he can project this bullet from a rifle-barrel, having one turn in 46 diameters, to a distance of upwards of a mile with astonishing accuracy. The initial velocity is, however, not great, and the rifle is very expen- sive, depending for its accuracy on workmanship only, not on the development of any new principle. We may fairly consider it proved by General Jacob, by Mr. Dove, and by Mr. Whitworth, that, with a moderate initial velocity of bullet, one turn in 45 or 50 calibres is ample to give rotation to the longest rifle bullet required. We may also accept the theory acted upon by the Swiss, viz., that with greater initial velocity less turn will suffice, and the converse as proved by the Sardinians, who use a small charge of gunpowder, but the extremely short twist of one turn in 26 calibres. All the bullets I have referred to were solid, and some tapering at both ends."* * "As regarded the rate of twist, measured in terms of the calibre, according to Major Ooquillet of the Belgian artillery, the turn of the grooves should be to each other, in all 526 ORDNANCE. 622. With reference to the rates of twist to length of bore, Mr. Whit worth mentions the following facts :* "The rifle-twist in the 80-pounder gun was one turn in 100 inches ; in the 12-pounder it was one turn in 60 inches ; and in the small 3-pounder, it was one turn in 40 inches. With respect to the degree of rifling adopted in the Whitworth guns, enabling the powder to be consumed more effectually, the following experi- ment was mentioned : Two barrels, alike in diameter and bore, were prepared ; all the conditions were identical, except the dif- rifled arms, as their calibres, provided the projectiles were similar. Colonel Theroux, of the French artillery, gave a similar formula, for determining the proper twist of grooves, for firing elongated balls. H (the helix or twist) 56 8 D; D being the diameter or calibre. This rate of twist was also found to be the best in General Jacob's experiments, and was adopted in his pattern rifle. The ratio of twist to calibre, ranged from 1 turn in 20 calibres to 1 turn in 136 calibres. In the case of each par- ticular gun, or rifle, all four ratios, weight of powder to that of projectile weight of projectile to cross-section rate of twist and length of bore must be considered, together, and in connection with each other. For there were different means for effecting the same ends ; and in many cases a deficiency in one of the four ratios might be made up by an excess in another. Thus, in the case of the twist, its object was to give a certain amount of rotation to the ball, as it left the muzzle. This requi- site amount of rotation might be obtained either by means of a rapid twist com- bined with a low initial velocity, or by a slower twist, combined with a high initial velocity. The first mode was adopted in the Sardinia Bersaglierin rifle, where, with a projectile 0'65 in diameter, not a diameter and a half in length, and -weighing 530 grains, the charge was only 54 grains, or little more than one-tenth. The initial velocity was, consequently, exceptionally low and a very rapid twist was required to establish the necessary rotation in the balls. The twist was, accordingly, 1 turn in 17 inches, or in 26 calibres. The second method was adopted in the Swiss Federation rifle. In this, instead of one-tenth, the charge of powder was one-fourth the weight of the ball. This produced so high an initial velocity, that 1 turn in 77 calibres suf- ficed to establish the requisite amount of rotation in the ball. Each of these two methods would secure equal accuracy, in firing at a mark, at a known distance ; but the Sardinian rifle-ball would have a much higher trajectory, and much less penetra- tion, than the Swiss. Rapid rotation could not be combined, beyond a certain extent, with a high initial velocity, unless the projectile was made with projections to fit the grooves. Without such projections, at high initial velocities, the ball would ' strip,' or be driven out without taking the rifling. Hence, those experimenters who, like General Jacob and Mr. Whitworth, had obtained the greatest results, by discerning clearly the advantage of combining the accuracy of rapid rotation with high initial velocity, and its consequence, a flat trajectory and great penetration, had adopted pro- jectiles made with projections to fit the grooves; and he believed such projectiles were destined to supersede those which were forced into the guns by the explosion of the powder." Mr. Conybeare, " Construction of Artillery." List. Civil Engineers, 1860. * "Construction of Artillery." Inst. Civil Engineers, 1860. RIFLING AND PROJECTILES. 527 ference of twist in the rifling. One barrel had two turns, and the other had four turns. It was found, on placing them both at an elevation of 1 20', and firing them with 50 grains of powder, that they each carried the shot to about the same height on the target. Mr. Whitworth then fired them with an increased charge of pow- der, and the barrel with two turns sent the shot considerably higher upon the target, while the barrel with four turns sent its shot but very little higher than with the small charge. A length* of 10 inches was then cut off the latter barrel, leaving only three turns, and it was fired again with the increased charge. The result was, that, the elevation remaining the same, it threw its shot higher on the target than the other barrel. This showed that rotation must bear a due proportion to the length of the barrel. It was desirable to have as much rotation as possible, taking into consideration the length of the gun. With a very long gun it was not advisable to have very rapid rotation, as the quick turn of the projectile was most felt at the muzzle." 623. The greater the specific gravity of a shot, the less velocity of rotation it will require, for this velocity will be less diminished during flight by the friction of the air. The inaccuracies of weight and figure are also likely to be less in proportion to the mass. The extraordinary accuracy of the 13'3-in. (600-pounder) Armstrong shot (556), is undoubtedly due, in some degree to its great size and weight. 624. Since elongated projectiles tend to turn over in the air to rotate round their shortest axis from the greater pressure of the air below than above their points, in proportion to their lengths, the velocity of rotation should increase with the length of the projectile. To accomplish this, the twist of the rifling must be increased. 62o. CHARACTER OF PROJECTILE ITS INFLUENCE ON ACCURACY. In order to secure accuracy of fire, it is essential that the axis of the projectile should correspond with that of the bore of the piece, for otherwise the axis of rotation will be variable, and the deflec- tion of the projectile uncertain. Major Owen, Professor of Artil- 528 ORDNANCE. lery at Woolwich, says upon this subject :* " Should the axis of the shot on leaving the bore be unsteady, the projectile will have the 'wabbling' motion so frequently observed in experimental practice. It is therefore indispensable that the bearings of the projectile should extend along the cylindrical part, or should be very near the centre of the shot, for if they be either too far for- ward or behind, unsteady motion must result from the axis of the projectile being inclined to that of the bore. 626. " When the whole length of the cylindrical part of the shot bears against the grooves, the projectile fitting the bore tightly, as is the case with almost all rifled small arms having leaden bullets, with breech-loading ordnance, like the Armstrong or Prussian guns, or with the Armstrong < shunt' gun, L. Thomas's rifled gun, &c., the axis of the bore and shot must coincide. "When there is any windage, as in the case of all muzzle- loading ruled pieces with hard projectiles having projections or buttons, there must be a slightly oblique movement of the axis of the projectile ; but still, if the bearings are over the centre of the shot, or there are two sets, one round the fore part, and the other round the hind part, as in the French elongated shot, the axis of the projectile will, no doubt, on leaving the bore, be tolerably steady. With the Whitworth rifled cannon, the projectile being made to fit the bore so accurately, and there being such a very trifling amount of windage, the axis of the shot is practically stable on leaving the bore. " Other cases might be stated, and the results of practice shown, to prove that the above principle is correct, and that a violation of it, by placing the bearings at random and in the wrong posi- tion, only results in giving an unsteady motion to the shot, thereby causing inaccurate shooting." 627. Commander Scott says upon'this subject,f with reference to expanding shot : " The difficulty experienced in the expansion plans is that of keeping the axis of the projectile coincident with the long axis of the piece. At low elevations, the friction along * Journal Royal United Service Inst, August, 1862. f Jour. Royal United Service Inst., December, 1861. RIFLING AND PROJECTILES. 529 the bore tends to raise the rear of the shot, and facilitate the equal expansion of the lead ; but, if the lead at the rear expands equally, it is clear that the iron forepart of the shot, having noth- ing to raise it, must continue to rub along the bottom of the bore. At high elevations, however, the shell keeps more fairly along the bottom of the bore, the lead on its upper surface expanding the most. An illustration of this is found in the greater accuracy obtained at high as compared with that obtained at low elevation- with the same gun." 638. The compressed lead-coated shot is also likely to be thrown out of line by the greater compression of the lead at one point than at another. 629. A further disadvantage of the expanding-shot is, the position of the centre of gravity behind the centre of figure (6 1 5). Commander Scott says* that " the Southern Confederacy has pur- chased very many of its heavy guns from England, which, with few exceptions, fire lead-coated shell. At the cannonading against Fort Pickens, these leaded projectiles struck on their base, which was heavier than the front, and did not explode." He also instances the followingf : " In breaching tfce tower at East- bourne, at 1032 yards, it was observed that, while some of the rifle projectiles penetrated from 7 to 8 feet into the brickwork, others did not pass through more than from 1|- to 2 feet. This difference was probably owing to some of the shot striking less fairly than the others. A familiar illustration of a somewhat similar effect is afforded by the difference between hitting a straight and a bent nail ; for, while the former easily penetrates hardwood, the latter will make but comparatively small impression." The James shot, however, which are particularly heavy at the base, were found to have struck point foremost, in the breaching; of Fort Pulaski4 But these projectiles were comparatively short.. 630. The stripping of soft-coated projectiles, with high charges, is another source of inaccuracy (691). * Jour. Koyal United Service Inst., April, 1862. f Jour. Eoyal United Service Inst., December, 1861. j Report of General Gillmore. 34 530 ORDNANCE. 631. The lateral motion of a rifle shot due to the resistance of the atmosphere (616) depends upon the smoothness of its surface. The projections formed on the shot to fit the rifling, act like the floats of a paddle-wheel ; and these must be most numerous and deep, in a lead-coated shot, in case of a high rotation, to prevent stripping. And these numerous ridges not only increase drift, but rapidly decrease the rate of rotation. So that the mechanically fitted shot with few grooves would appear to be indispensable to the highest accuracy at long range. Commander Scott thus refers to this subject.* In making his shot (535), he "had endeavored to obtain the form for permitting the greatest velocity through the air, and at the same time for keeping up the rotation as perfectly as possible. His shot were cast so as to bear on three grooves in the gun, and were so shaped as to carry round little or no air. In this respect they had a great advantage over polygo- nal and lead-coated shot, with which a large quantity of air must be carried round in rotating. This defect he had endeavored to avoid by deviating as little as possible from a cylindrical form. When that or a circular form was not adopted, as, for example, if the shot was polygonal, a greater amount of initial rotation was required than if the shot were of a figure adapted to keep up the rotatory movement. Hence, those who had tried the polygonal form, or who had fired a lead-coated shot out of a many-grooved gun, had been obliged to give a greater amount of rotation to the shot than would have been necessary with fewer projections." 63^. Raaige. Long range is due, 1st, to a high initial velo- city ; and, 2d, to a great weight of projectile in proportion to the resistance of the atmosphere in other words, to great length and small cross-sectional area. At the same time, the large area in proportion to the weight, presented by the long projectile to the air below it, prolongs the time of its elevation, and in this way also contributes to long range, f * "Construction of Artillery." Inst. Civil Eng., 18GO. f As to " the question of diameter of bore, it would be seen, that although a solid cylinder of small diameter, had a decided advantage, as regarded penetration of the air, over a hollow cylinder of large diameter, yet the hollow cylinder had the advan- tage in notation, and the consequence was, that the difference in range was not RIFLING AND PROJECTILES. 531 633. But, 1st, to insure steadiness, such a projectile must have a high velocity of rotation by means of a rapid twist, which brings a considerable strain upon the gun in addition to that due to the mere translation of the shot. 2d, the greater the proportion of weight to cross-sectional area of shot, the greater the pressure imposed upon the gun for a given velocity of translation. And the friction of a very long projectile in a foul gun is very great. So that the length Qf the projectile cannot be excessively in- creased. The length of about 3 calibres has been found to give the best ranges.* 634:. In the discussion of this subject before the Institution of Civil Engineers, Mr. Britten " considered there was a great deal of misconception, as to the advantages to be obtained by the employment of small bore guns and projectiles of great length. At very high elevations, such projectiles undoubtedly had longer range, because from their greater weight and smaller area of transverse section, they were less impeded by the air, and main- tained their velocity during a longer time of flight. But it was a mistake to suppose, that at low elevations they had any advantage, in point of range, over the larger projectiles which he had fired from rifled service guns. In order that this important point should be fully understood, he had prepared a Table (105), giving the results of his experiments, and he had added the results, as published in the newspapers, obtained with the Armstrong and the Whitworth guns : 635. " It would be seen from these figures, that up to about 10 elevation, the rifled cast-iron guns had at least as long a range as the wrought-iron breech-loaders with equal charges ; and that at less than 5 elevation, the rifled service guns had a positive nearly so considerable as might otherwise be supposed." Sir W. Armstrong, " Con- struction of Artillery.' 1 '' List. C. E., 1860. * "By increasing the twist it became practicable to increase the elongation of the projectile to the extent of 7 diameters if such a projectile was similarly grooved. But the elongation of the projectile was limited by other considerations ; and it was now established that from 2 to 3 diameters would be the utmost amount ot elonga- tion adopted, save in exceptional cases." Mr. Conybeare, " Construction of ArtiUery." Inst. Civil Engineers, 1860. 532 ORDNANCE. TABLE OY. RANGES OF LARGE AND SMALL RIFLED PROJECTILES. GUN. Bore. Charge of Powder. Projectile. Eleva- tion. Range. Mean Velocity per second. Diam. Area. Weight. Capac'y. In. In. Ibs. Ibs. Ibs. Degrees. Yards. Feet. Rifled g-pounder Service Gun, Cast Iron, 17 cwt };: 13.1 if ii 14 6 oz. 5 10 2000 7200 1 Notob- J served. j f6. 4 i 32-2 6 49 3f 3 j 1600 1122 Rifled 32-pounder Ser- M 4i 2100 1016 vice Gun, Cast Iron, . c6 cwt " " " '* " 8i 3100 930 a " M " M 10 3600 900 Similar Gun 6-C7 31 -9 41 solid* C( 3700 740 Rifled 68-pounder Ser- vice Gun, Cast Iron, QC CWt ... ' u J / ": 51.7 61 8 T^* 10 j / Is 6O / T w 8 5 Q2O Rifled 32-pounder, Cast Iron, 95 cwt - 1 .5.37 31.9 7 56 2 M J J 3700 y 955 Rifled i8-pounder, Cast Iron c8 cwt ' , h-9 22 34 3900 948 '8-12 51-7 16 68 solid -3 0/ 340 2040 Smooth-Bore 68-pound- i 640 1280 der Service Gun, Cast Iron, 95 cwt M < M 5 1960 939 . 14 3480 7H f3 7 i -6oz. 12 foz. 3 1200 923 Armstrong Breech- loader, Field-Gunf... : ... 5 1820 900 I" " " " ... JO 30 3 826 Ditto, Large Gun 6 28-2 9 80 solid 10 3900 ... [3 7 if 12 solid 2 I25O - Whitworth Breech- , loader, Field-Gun ' t ii 5 10 2300 3780 Initial velocity about p* 21 12 80 " 5 2600 " 1300 feet per Ditto, Large Gun, Weight, 80 cwt ' (t " " " " 7 349 second. I" M " 10 4400 * Service round shot, prepared by Mr. Britten to suit rifled guns, t Kange Tables in Horse Guards Manual, published by authority. RIFLING AND PROJECTILES. 533 superiority in tliis respect. Nor was this all. The velocity with which the rifled service guns projected their shot, even with smaller charges of powder, was much greater than was the case with the breech-loaders. In the official reports of Mr. Britten's experiments, the time of flight of each shot was carefully recorded, so that there was no difficulty in ascertaining the mean velocities at the different ranges. The mean velocity of his 49-lb. shells, fired from the 32-pounder rifled service gun, was thus shown to be 1120 feet per second, in a range of 1600 yards ; the 56-lb. shell, with 7 Ibs. of powder, had a mean velocity of 955 feet per second, in a range of 3700 yards ; and the 90-lb. shell, of 8 inches diameter, with only 8 Ibs. of powder, or T \th the weight of the projectile, had a mean velocity of 920 feet per second, in a range of 3560 yards. When, therefore, it was stated, that the velocity of the Armstrong projectiles, on leaving the gun, with charges of }th the weight of the shot, was only 1080 feet per second, and that of the Whitworth shot, with a charge of th, was under 1300 feet per second, he thought it might safely be asserted, that the muzzle-loaders did more work with the power applied than the breech-loaders. " In order to show the great effect of the resistance of the air in diminishing the velocity of large bodies during flight, the mean velocities, at different ranges, of the 68-pounder service solid shot, with full service charges, were given in the table. These figures were officially determined, from practice on board the < Excellent' gunnery ship. It would be seen, that at 340 yards, the mean velocity of the service solid 68-pounder shot was 2040 feet per second; but this mean speed fell off to 714 feet per second at the range of 3480 yards. The same gun, when rifled, threw a 90-lb. shell, 3560 yards, with a mean velocity of 920 feet ; it was therefore probable, that the initial velocity, in this case, must be very much more than was obtained by the breech- loaders. This was remarkable, when it was remembered, that the 8-inch shells had the resistance of the air upon 51 square inches, the sectional area of the shell ; while the Armstrong and the Whitworth projectiles had a sectional area of only 28 and 21 534 ORDNANCE. square inches respectively, and were fired with much heavier charges. From these facts he inferred, that for horizontal fire up to 2000 yards range, which was the service most required, his large-bore guns were in no respect inferior to the new small bores, while in many points they were far more serviceable." 636. The shape of the projectile has an important influence upon its remaining velocity and range. But as the shapes required for range and for armor punching are different (7 1 3), and as iron- clad fighting must be done at so short a range that little velocity will be lost whatever the shape of the projectile, this consideration is of limited importance in the present inquiry.* The following tables and diagrams, f however, are of special interest. 637. EFFECT OF FOKM UPON RANGE. " The retardation of a projectile is influenced by the form of both its fore and hind part, but especially by the shape of the former. The following table J (106) of resistances to bodies of different forms, moving with low velocities of 10 feet per second, is constructed from the results of Dr. Hutton's experiments with the ' whirling machine' invented by Robins. " The experimental resistances to 2 and 3 are about the same, * "As to practical results, Mr. Whitworth did not now propose to carry out the comparison. But something ought to be said as to range, which he was surprised to hear undervalued. Without attaching too great importance to mere range, it must be admitted to be a very good measure of what the gun could do. If at an elevation of 7, the range of the fluted gun was 2495 yards, and the range of the hexagonal gun was 3107 yards, the trajectory of the latter was flatter, and the errors in judging dis- tance were of less importance, as during a greater portion of its flight the hexagonal projectile was nearer the ground. This perhaps would appear more plainly, by com- paring the range of the fluted 12-pounder gun at 9, which was stated on good authority to be 3000 yards and upwards, with the range of the hexagonal 12-pounder at 7, which was 3100 yards and upwards; now considering the ranges as about equal at these different elevations, the advantage of firing the hexagonal gun at 7, as com- pared with another gun, which to attain a like range required to be elevated to 9, was obvious. The gun which had the longer range and the flatter trajectory was more likely to hit a distant object, than another gun which had one-fifth less range, for the same elevation." " Construction of Artillery" Inst., G. E., 1860. f Major C. H. Owen, R. A. Jour. Royal U. Service Inst., Aug., 1862. \ Extracted from Capt. (now Lieut.-Col.) Boxer's Treatise on Artillery, page 152, art. 299. RIFLING AND PROJECTILES. 535 TABLE CVI. RESISTANCE OP BODIES TO THE ATMOSPHERE. FOKM OP THE BODIES. Experimental Resistance. Theoretical Resistance. 32P- > ) I Hemisphere, convex side foremost 124. 144 1AA ^> > 1 ^"^5 3 Cone, angle with the axis 25 42' 126 sa>' > 4. Disk..., 28 c 53 288 ^g, > / r Hemisphere flat side foremost 288 288 288 zyi notwithstanding the sharp point of the latter. The resistances to the three last, which theoretically ought to be double of the two first resistances, are experimentally much more, in fact 2^- times as much.* " The next table (107) is taken from Piobert's < Cours d'Artil- lerie,' and contains the results of experiments made by Borda in the last century, with velocities of 3 to 25 feet a second. 638. " From this table it appears that the ogival form expe- rienced the least resistance. With high velocities the results might perhaps differ considerably from the above, and experiments care- fully executed can alone enable us to determine the form of pro- jectile which will attain the greatest range with a given initial velocity. " One of three different forms is generally employed for the head of an elongated projectile. The figures represent sections of these three forms. Fig. 305 is the section of a " cone." Fig. 306 is the section of a " conoid," or a figure generated by the revolu- tion of a conic section about its axis. Fig. 307 is the section of a * Dr. Hutton's remarks on these experiments will be found in his 36th Tract, page 190, voL iii 536 ORDNANCE. TABLE CVII. RESISTANCE OF BODIES TO THE ATMOSPHERE. FORM OP THE BASE OF'PBISMS. Experimental Resistance. Theoretical Resistance. , Triangle, apex foremost 52, kf Demi-ellipse -. . *5 i 4 Ogival JQ 4.1 L pointed arch, which is termed by the French " ogival." The last is most probably the best form, as the one which experiences the FIGS. 305. 306. 307. FlG. 308. least resistance from the air. Sir Isaac Newton in his Principia gives a form of body (Fig. 308) which would, in passing through a fluid, experience less resistance than a body of any other shape. This form, it will be seen, is very similar to the ogival. Pio- bert says that the form Fig. 309 will experi- ence the least resistance from the air. Its length is five times its greatest diameter, and its largest section is placed at f of the length from the hind part. The shape of some of Mr. Whitworth's projectiles approach more nearly to this form than those of any elongated projectiles hitherto used." 639. Velocity. Although the elongated bolt, with 400 to 500 feet less velocity at starting, overtakes the round shot at 800 to 1000 yards, yet the necessity of a high initial velocity is obvious. RIFLING AND PROJECTILES. 537 It is absolutely necessary to penetration, even at short range, when, for instance, the rifled gun is called upon to send shells through FIG. 309. armor. It is necessary to accuracy at long range, for reasons already considered ; and without extraordinary provisions for ac- curacy, long range is of little advantage. 640. Captain Fishbourne, R. N., says upon this subject :* " Greater accuracy with the same guns, &c., at known distances, with heavier charges, arising from the greater velocity of pro- jectile, is so well known and admitted, as not to need proof or ex- planation ; but, great as are the other advantages of high charges, they are small as compared with those of a flat trajectory, where the distances are unknown." Supposing two trajectories, " one, that of a ball with such a velocity that it travels the distance in one second, and subject only to the fall of 16 feet ; the other, of a ball that requires two seconds, therefore subject to a fall by gravity of 04 feet. If no disturbing cause arises, a ship that is but 12 feet high, and there are few so low, will be struck at any point in the trajectory of the ball, with high velocity ; whereas a ship 48 feet high or more, will be passed over by the ball having the lower velocity, and only within narrow limits of distance would a ship 30 feet high be struck by it in its trajectory." 641. The first condition of high velocity is a light projectile. This does not necessarily mean a short projectile ; the proper length for the greatest stability may be preserved by hollowing the pro- jectile in such a way as not to displace the centre of gravity, or better, by some modification of the principle adopted by Mr. Stafford (590 and 590 A). The second condition of high velocity is that the least * Journal Royal United Service Inst., June, 1862. 538 ORDNANCE. possible power shall be expended in overcoming friction and changing the figure of the shot, while getting it out of the gun. Power thus wasted is worse than lost, because it strains the gun so much as to require reduced charges, thus decreasing the velocity in another way. The service charge of the Armstrong 110-pounder has been reduced from 14 to 12 Ibs., for this reason.* So much power is expended in planing 76 grooves in a hardened lead-coated projectile, that even 14 Ibs. of powder pressing on the 7-in. 111-lb. Armstrong shot, gives less velocity than 10 Ibs. of powder pressing on the Parrott 6'4-in. 100-lb. shot. The initial velocities are, respectively, 1211 and 1244 feet, and the areas of the shot pressed by the powder are, 38 '5 and 32'1 sq. in. The range of an Armstrong 7-in. 110-lb. shot with 12 Ibs. of powder, was 3387 yards against 3981 yards for the Jeffrey 100-lb. shot- same bore, charge, and elevation. (See Table 108.) 643. Sir "William Armstrong attempted to justify this retar- dation of his projectile in the gun as follows : " By holding back the projectile until the powder is thoroughly converted into gas, you will get a higher pressure upon the projectile, and impress a greater quantity of work upon it. * * * Experiments have been made with lead-coated shot, having the lead considerably reduced in diameter so as to facilitate the passage of shot through the bore ; and it was found that, instead of reduced friction in- creasing the initial velocity, the result was rather the contrary."f G44. It by no means follows that a shot moves more slowly because the impediments in its way are removed. The reduction of the lead covering might have so increased the windage that the full pressure of the powder was not exercised upon the shot. * "The pressure of forcing a 25-lb. Armstrong shot slowly through the bore, by mechanical means, is said to have exceeded forty tons." Capt. Flshbourne, Journal Boyal U. Service Inst., May, 1864. " Another evil arising from rifling is, in case of lead-covered projectiles of one class, such as are used with the Armstrong gun, that the rifle-grooves have to be cut by the explosive force of the powder, and this is done with immense velocity, and in the space of a few inches, the power required must be very great. The leading of the gun and the stripping of the shot show how great this strain must be, and in order to meet the difficulty and prevent such effects, recourse has been had to slow burning powder, and as a consequence a low initial velocity has been obtained." Mr. Michael Scott, on Projectiles and Rifled Guns. f Jour. Royal United Service Inst., June, 1862. RIFLING AND PROJECTILES. 539 TABLE CVIII. COMPARATIVE RANGES OP JEFFERY AND ARMSTRONG PROJECTILES. JEFFERY. Average range, with 12 Ibs. of powder, 3981. Average range, with 1 6 Ibs. of powder, 4139. Charge. Elevation. Weight. Eange. 1st graze. Deviation. Eight, yards. Ibs. Degrees. Ibs. 12 10 100 4050 26 12 10 100 4001 22 16 10 100 4032 II 12 10 100 3988 4-2 12 10 100 3949 '9 16 10 100 4185 14 12 IO 100 3998 14 12 10 IOO 3942 30.4 12 io c 100 3974 ii. 6 12 10 IOO 3953 7 16 IO IOO 4259 20 16 10 IOO 4083 II-2 ARMSTRONG. 12 10 no 3400 3* 12 10 no 3411 21 12 10 no 3434 24 12 10 no 3328 2 3 12 10 IIO 33*4 29-4 12 10 IIO 3368 33 12 10 IIO 33 6 4 23 12 10 IIO 349 6 22 12 10 IIO 335 22 12 10 IIO 3395 26 Average range, with 12 Ibs. of powder, 3387. NOTE. Only 2 rounds, with this proportionate charge and elevation, were fired from Mr. Britten's gun. The ranges were 3500 and 3400 yards. Guns of the same calibre, length, and weight. Jeffery's gun was rifled with 1 5 grooves -^ inch deep. The base of the projectiles was coated with lead hardened by tin. 540 ORDNANCE. And if it is important to increase the pressure upon a shot, the use of more powder would appear to be a simpler and safer means than straining and abrading the gun by jamming a hard wedge through it. Besides, continuing to retard the shot by the friction of many grooves, and by an additional nip at the muzzle, after the pressure of the gas has been reduced by expansion, simply wastes power and reduces velocity without any compensation. If the shot must be retarded, it would be better, as Mr. Whit- worth has suggested,* to expend the power in increasing its rotation. This must be done in the gun ; grooving the shot may be done elsewhere. 645. A mechanical fit offers the least friction and retardation to the shot. There would not appear to be much difficulty in obtaining all the pressure that a rifled gun can stand, by the use of plenty of powder, however smoothly the projectile may fit. It is, however, a defect of the Armstrong gun, that the length of cartridge and projectile must always be the same ; if longer, they will not enter the chamber ; if shorter, an air space is left in the powder-chamber (551). 640. This subject is thus referred to by the Ordnance Select Committee, July 30, 1862 :f "Under strictly comparable condi- tions, that is to say, equal weight of shot, equal charge, and equal length of gun, the Whit worth 12-pounder appears to give an initial velocity below that of the Armstrong gun. This is prob- ably due to the retardation experienced by the Armstrong shot in passing through the contracted part of the bore immediately in front of it, which permits a steady accumulation of pressure behind it, and is instantly followed by a decrease of friction when the shot emerges into the wider part of the bore. The friction of the Whitworth shot, arising from the very rapid twist of the rifling, concurs to produce the same relative effect. In the Armstrong 12-pounder the angle of rifling is 4 44', and in the Whitworth 12-pounder is 8 55V But the Committee dis- cuss neither the retardation of the Whitworth shot by its wedging * " Construction of Artillery." Inst. Civil Engineers, 1860. f Report of the Select Committee on Ordnance, 1863. RIFLING AND PROJECTILES. 541 in the grooves, nor the philosophy of increasing the pressure (as in the Armstrong gun) at the very place where large guns fail, even when slow powder and accelerating charges are applied to reduce the initial pressure. 04:7. WINDAGE. Windage is the principal objection raised against mechanically fitted projectiles. Supposing it impracti- cable to prevent windage, Mr. Whitworth's experiments show that it is not disadvantageous. He fired, " from the same gun, an iron shot, rifled on his plan (in which a small amount of windage was purposely allowed), and leaden shot of the same shape and size. The leaden shot was necessarily expanded by the explosion, until it filled the bore; and was propelled without there being any windage at all. But, although its specific gravity was greater than that of the iron shot, and it had no windage, its range was not nearly so good as that of the iron shot."* 648. The entire stoppage of windage appears ,to prevent the certain action of time-fuzes, as they have to be lighted after the shell leaves the gun ; and in case of the Armstrong gun this has led to costly and nearly fruitless experiments with percussion- fuzes. The rush of the gas past the projectile also tends to re- lieve fouling to blow out the dirt that would otherwise accu- mulate. 649. The windage may be stopped in any required degree by the use of wads. Mr. Whitworth and Commander Scott have used them without inconvenience, but what is more important, have abandoned them (at least for the purpose of stopping wind- age), without impairing range or velocity. In fact, increasing the charge with windage, strains the gun less for a given velocity, than reducing the charge and the windage. More time is allowed the powder to overcome the inertia of the shot.f (652). * " Construction of Artillery," Inst. Civil Engineers, 1860. f The following statement of French experiments and practice regarding windage is compiled from an article entitled "Rifled Ordnance in England and France," in the Edinburgh Review, April, 186-4: "The result of the more recent experience of the French artillerists proves that the suppression of windage diminishes the accuracy of fire. * * * When the projectile is driven forwards to the muzzle of the piece, by the expansion of gas generated by the explosion, the point of time at which it 542 ORDNANCE. 65O. Mr. Whitworth's lubricating wad* lias other advantages, and is thus described by him :f " The metallic cartridge was made of tin plate, and had a rifled shape to fit the bore. When it was inserted in the gun, it formed leaves the gun decides its direction, and the slightest variation of pressure from within or without at that instant causes deviation in its subsequent flight. The ab- sence of windage is now thought by the French to increase the probability of some such accidental variation of pressure ; but when a portion of the gas generated by the explosion is allowed to escape by windage, as this gas travels four or five times faster than the projectile, it serves as it were to prepare the atmosphere for the ball, and to launch it on the straight line to its trajectory. * * * "A heavy gun of fifty French measure (corresponding to our 70-pounder), which had already fired 280 shots at iron plates 4^ inches thick, and pierced them at a dis- tance of 1093 yards, was treated in the following manner: The gun was bored, like a flute, with 36 holes, each of 6 centimetres in diameter. In that state it was again fired, and it turned out that the initial velocity of the projectile was diminished scarcely 2 per cent. But on the other hand, the accuracy of fire of the piece was greatly augmented, and the recoil, which had averaged about seven metres before the operation, was reduced to 1 metre 40'. It is, therefore, now asserted by some of the highest French authorities, that windage, without really diminishing the power of guns, improves their accuracy, and greatly reduces the stress of the explosion on the piece. * * * " Provided the projectile leaves the gun with its axis in line with that of the piece, the inaccuracy caused by windage ceases; and this is precisely what is obtained both in the French and in the "Whitworth guns." Another advantage of windage that the gun can be fired rapidly and often without sponging is thus illustrated by the same writer: "At the battle of Solferino, when the corps of General Benedek, having driven in the Piedmontese army for a distance of two or three miles, threatened to turn the left of the French position, it was for- tunate for the French army that they had guns not requiring to be sponged out after every round ; for it was the extraordinary rapidity of the fire of the rifled batteries of the French Guards which arrested the Austrian advance at a range which then appeared incredibly great, and enabled the Piedmontese to recover their ground. * * * " On a recent occasion at Rennes, the experiment has been tried on the new French artillery in a still more striking manner. A gun, taken at random from one of the batteries of troops quartered in that town, was fired consecutively 1000 times without being washed or sponged out, and without even once washing, clearing, or scraping the touch-hole. After this extraordinary trial, we learn from the report of the officers in command, that the gun had lost only 7 L 5 of a degree of precision required by the regulations of the French service. It is proper to add, that this experiment was made with compressed gunpowder ; but the result is mainly due to the windage of the piece, which is now freely admitted by French artillerists to be not only no evil, but an essential condition of accurate and rapid firing." * "Mr. Whitworth, in his specification, claimed the original arrangement of a tallow-box in front of the powder. Sir William Armstrong, after experience of the disadvantages of washing out the gun, enclosed the tallow in a ball of hemp." Mr. W. B. Adams, " Construction of Artillery," Inst. C. E., 18 GO. f " Construction of Artillery," Inst. C. E., 1860. RIFLING AND PROJECTILES. 543 a lining within which the charge was fired. The powder, there- fore, instead of acting against the sides of the gun, acted against the inside of the cartridge. This saved the gun ; and moreover, when the cartridge was withdrawn after the discharge, it brought away with it the fouling deposit. A small hole was made in the rear of the cartridge case, through which the fire from the friction fuze was flashed to the powder. The case was filled with powder to within about half an inch of the open end. It was then closed by a wad, of lubricating material, which, when the charge was fired, was distributed over the interior of the gun. This obviated the necessity of sponging out, which had always been a great inconvenience in working guns. He believed this plan of obviating the necessity of sponging, by the use of the wad of lubricating material, had not been used previously to his adopt- ing it." 651. Projectiles are retarded and their velocity is reduced by other causes, which also strain the gun, viz. : rapid twist of the rifling, the wedging of the projectile due to a bad form of rifling (656), sudden starting and compression of the shot, and fouling due to lead coating. These causes are further considered in the follow- ing paragraphs. The shape of the projectile also affects the main- tenance of its velocity (637) ; but cleaving the air and punching armor require different shapes, and since the latter must be done at short range, little velocity will be lost, whatever the shape of the projectile. 652. Mr. J. B. Atwater, of Chicago, has arrived at some sin- gular results, by largely increasing the windage of the gun after the shot has started. The experiments are not yet complete enough, however, to warrant an extended inquiry. A 5 '85-inch (80-pounder) cast-iron hooped gun, constructed after preliminary experiments, for this rifling, has 12 grooves T ^ inch deep, and 12 lands of equal width at the breech (Fig. 310). At 12 calibres from the bottom of the chamber the lands are cut away in alter- nate pairs to -J inch below the bottom of the original grooves (Fig. 311). Other conditions remaining the same, the range of projec- tiles from this bore is considerably increased. This result is 544 ORDNANCE. ascribed to various causes. Decrease of friction would be better promoted by cutting off the chase altogether. The more perfect Fia. 310. FIG. 311. Atwater's rifling. combustion of the powder by the air entering at the side of the shot would also follow, leaving an air space in the chamber of the gun ; in fact, to the sudden and perfect combustion thus promoted some authorities attribute the bursting of guns. Mr. Atwater reasons from the experiments of Captain Rodman, that the air pressure in front of the shot is greater than the gas pressure behind it, at the point where he cuts the lands away. (649, note.) 653. Strain. The failure of unstrengthened cast-iron guns generally, even of the Dahlgren T^-inch rifles, with all their ad- vantages of superior iron, figures and founding, is evidence of the increased strains due to rifling. Mr. Bashley Britten has certainly obtained very good range and accuracy, and tolerable endurance from old unstrengthened cast iron guns, rifled. But the charges were reduced from 10 Ibs. for a 32-lb. ball to 6 Ibs. for a 50-lb. shell fired from the same gun, and the grooves, only 5 in number and T V inch deep, had a very low twist (1 turn in 48 feet), all of which is unsuitable for the heavy projectiles and high velocities required in iron-clad warfare. The strains imposed upon a gun in firing an elongated rifle- shot, in addition to the strain due to the mere translation of the shot are various.* * "The argument that the smallness of the recoil of rifle-guns, establishes that RIFLING AND PROJECTILES. 545 G*Vl. WEIGHT OF PROJECTILE. First, the pressure on a gun is nearly in proportion to the weights of the projectiles (240). A rifled shot, to be accurate, to be conveniently laid hold of by the rifling, and to range farther than the round ball, must be some- what elongated : it is therefore two or three times the weight of the round ball, unless it can be hollowed without disturbing the cen- tre of gravity, or arranged on the sub-calibre principle (590), without otherwise impairing its efficiency. The heavy shot is displaced more slowly, and the pressure behind it is greatly in- creased. This source of strain has nothing to do with the groov- ing, or with the method of taking the grooves. 655. TWIST OF KIFLING. The next source of strain is the twist of the rifling, irrespective of the bursting strain due to the wedging of the projectile in such grooves as Whitworth's and Lancaster's. The inertia of the shot tends to tear away the land or to split the gun along the groove, which is the thinnest and weakest place. The Ordnance Committee, in their report on the experiments of 1861 (598), are of the opinion that the liability of the gun to be burst from this cause is directly as the sine of the angle of the rifling, although, by calculation, Mr. Longridge finds* that " even with the rapid twist employed by Mr. Whitworth (1 in 5), the amount of force expended on the rifling scarcely exceeds 2 per cent, of the total force of the powder. Taking Mr. Whit- worth's large gun (80-pounder), the following will be, approxi mately, the forces required to give translation and rotation, when the shot weighs 80 Ibs.. and the velocity on leaving the gun is 1300 feet per second : there is little friction, and therefore little tension on the gun, is a fallacy, for it is the intensity of the friction that prevents the gun from recoiling ; so great is it, that it could not fail, with higher charges than those used for them now, in time to disinte- grate such guns, by separating the chase from the breech, or more properly the inner cylinder from the outer; indeed, I believe this has already, in many cases, taken place." Captain Fishbourne. Jour. Royal U. Service Inst., June, 1862. * "Construction of Artillery," Inst. Civil Engineers, 1860. Mr. Longridge's obvi- ous meaning having been misapprehended, he afterwards explained, in some remarks at the United Service Institution (Journal, March, 1861), that the wedging of the Whitworth shot was a source of great strain, but that the friction necessary to give rotation was as stated above. 35 546 ORDNANCE. Mean force, to give translation Force, to give rotation 37^4 Friction of shot in grooves, taken at ^th pressure 3012 Total force Or taking the total force at 100, the force to give rotation is z-i6." Iba, 306900 6796 313696 656. WEDGING or THE PROJECTILE. Another most serious, although remediable, source of strain from rifling is due to the wedging of the projectile in all grooves of which the bearing sides do not lie in the plane of the diameter of the gun. For instance : the inertia of a projectile rotated by the groove C D, Fig. 314, FIG. 312. FIG. 313. FIG. 314. Illustrating the strain of rifling. tends only to rotate the gun in the opposite direction ; but the greater part of the pressure imposed by the shot in Fig. 313, assists the powder in enlarging the diameter of the gun. 657. In addition to this direct rupturing strain, the friction of the projectile is increased by the same cause. The accompanying illustrations are given by Captain Blakely, who remarks :* If, in Fig. 312 " the shot is meant to revolve in the direction G Z, all the pressure on the half-side C D w T ill assist this motion, all on the half-side C A will resist it and cause enormous friction and waste of power. * * * Mr. Whitworth, after the bursting of his second gun, in 185T, abandoned this idea of a mechanical fit, and, while retaining an almost hexagonal form for his bullet, planed away that part of the bore whose pressure would be mischievous. The * Jour. Royal United Service Inst., March, 1861. RIFLING AND PROJECTILES. 547 bore of his latest gun is 24-sided in section, six of these sides only being bearing surfaces (Fig. 313). If from R, the centre of one of these bearing surfaces, a line, R 8, be drawn perpendicular to the surface, it will represent the force tending to make the shot rotate. A glance will show how much less force would effect the same object if applied at P in a parallel direction. * * * The worst of all conditions would be the mechanical fit (Fig. 312), where not only part of the pressure J K would prevent the bullet from rotating, but where the force which we may suppose to act at _Z?, and to be represented by B E, would be so disadvan- tageously applied that, if we resolve it into two forces, B O and B F, the former, which can only cause useless friction, will be found four times as great as the latter, which alone is useful. * In the very common form shown at C D (Fig. 314), one of the surfaces, (J or D must be useless, and it surely simplifies the form to cut off the shoulder as at E F. The bearing surfaces must be truly radial. The slightest inclination causes increased friction, as at G) where the pressure, acting in the line G H, can be resolved into two forces, G 7, useful, and G K, the reverse. The form of groove adopted by the French, L MNP, Fig. 314, has all the dis- advantages of the hexagonal bore, for the force is applied to the bullet by the surface M N in the direction 12 $, whereas motion is intended to be given in the direction R T. All curled grooves, as at V X TF, have the same defect ; force is applied in a direction X Y, quite different from that X Z, in which it should be given." 658. The Lancaster oval shot is obviously calculated to jam in the bore.* Mr. Bashley Britten makes the following important statement :f " The repeated failures of the Lancaster gun, involv- ing sacrifice of the enormous sums of public money which were lavished on that system, induced the belief that cast-iron guns were not strong enough to be rifled ; but the fact that whenever the Lancaster guns burst, it was always in front of the trunnions, * In October, 1862, the Ordnance Select Committee reported against Mr. Lancas- ter's system, but in December they thought it might be so improved as to utilize the old brass guns for field use. f Journal Royal U. Service Inst, March, 1861. 548 ORDNANCE. while guns which burst under proof charges always go in rear of them, was a clear proof to my mind that the cause of bursting was not the charge of powder, or the weight of the projectile, but was connected with the method of rifling, and the employment of a rigid shot, at any time liable to get jammed in the gun." " 659. The Government Report on Rifled Cannon in 1858, states that " three out of eight Lancaster guns employed against Sebastopol burst, all, however, of the lighter natures ; they were nearly all 8-in. guns of 65 cwt. bored up. Two also of the heavy Lancaster guns, bored up from the 68-pounder gun of 95 cwt., have burst at Shoeburyness. These accidents have led to some doubt whether they can be used with safety with full charges, viz. : 8 Ibs. and 12 Ibs." The report also states that there are " remarka- ble irregularities in the ranges, which it is difficult at present to explain, but which, however accurate the gun may prove in direc- tion, are a most serious evil." To the increasing twist formerly used in these guns, however, in connection with the long bearing of the projectile, much of the extraordinary strain is attributed. 660. The testimony before the Select Committee on Ordnance, 1863, was rather more favorable on the whole, to the Armstrong, than to the Whitworth system of rifling and projectiles. 661. The friction of the Whitworth projectile* in comparison with that of the shunt shot is shown by their relative velocities. The Whitworth 68 Ib. 9 oz. shot from a YO-po under, charge, 9 Ibs., had a velocity of 1132*5 feet. The Armstrong 3-grooved shunt shot of 68 Ibs. 6-J oz. weight, charge 9 Ibs., had a velocity of 1283-8 feet. The Whitworth 68 Ib. 9 oz. shot, charge 10 Ibs., had a velocity of 1199'4 feet. The Armstrong 6-grooved shunt * Mr "Whitworth was informed by General Peel in December, 1858, "that as all three of his cast-iron polygonally bored guns had burst at an early stage of the ex- periments, he had decided on discontinuing experiments with this form of rifled cannon." Kepori of the Select Committee on Ordnance, 1863. Captain Blakely said before the above Committee, that the "Whitworth gun had been tried and rejected in France; that at 5, out of 10 shots, some went 570 yards further than others ; that the gun was also tried without success at Copenhagen, and that one tested at St. Petersburg, burst at the 149th round with 5 Ibs. of powder and a 35-lb. shot RIFLING AND PROJECTILES. 549 shots of 74 Ibs. 6-J oz. and 76 Ibs. 8 oz., had a mean velocity of 1314-3 feet. The same result followed all trials of the two sys- tems of rifling. 662. In July, 1861, the Ordnance Select Committee reported unfavorably upon Mr. Whitworth's system of rifling, for the fol- lowing reasons : 1. If the projectiles are accurately fitted, they are likely to rust, and give trouble in loading without frequent painting and cleaning. If not accurately fitted, the gun forfeits one of its principal claims to superiority. 2. The comparatively small calibre and long projectile greatly increase the strain on the gun, and the shape of the projectile is unfavorable for shrapnel, although favorable for the penetration of solid shot. 3. The rapid pitcli of the rifling, although necessary to the accuracy of long projectiles, is another source of strain upon the gun. 4. The Committee think the finish and fitting of the Armstrong guns and projectiles to be equal to those of the Whit worth guns and projectiles, and that these features would not in any case render the polygonal system preferable to other systems. 663. The following experiments, recently made at "Woolwich, to test the strain due to various forms of rifling, are obviously decisive as far as bursting pressure is concerned. But they do not show the additional weakness of the Lancaster and Whitworth systems due to increased friction, because the experimental shot were not moved longitudinally in the rifling, but only revolved. And although the sides of the grooves in the 10-grooved shunt gun are not quite in the plane of the diameter, its superior en- durance is obviously due only to the larger number of grooves and the greater amount of metal thus called into service. 664. RESULTS OF EXPERIMENTS MADE TO TEST THE STRAIN ON THE GUN DUE TO VARIOUS FORMS OF RIFLING, BY MR. JOHN ANDERSON.* " The power required to give the rotatory motion to the projectile, through the agency of ribs or grooves in * The following is quoted from British Artillery records. ' 550 ORDNANCE. the gun, must necessarily cause an opposite straining in the gun tending to open it, or else to break the metal without actually splitting. We can easily perceive that an inclined surface is more apt to split the structure than a flat or perpendicular sur- face, but there were no precise data in regard to the position in which diiferent plans stood with respect to each other. " In order to ascertain this point, experiments have been made in the Royal Gun Factories, by preparing cylinders of cast-iron, all of equal strength and area ; these cylinders were bored and rifled on the several plans shown on the accompanying table, and to prevent the risk of error from any exceptional defect of any description, several of each sort have been experimented with. " Into these rifled cylinders there were correctly fitted corre- sponding plugs of steel representing the projectile ; these plugs were made to fit the part representing the gun, and being of steel, which is a stronger metal than the cast-iron cylinders, it was resolved to continue the experiments until a form of rifling was arrived at, in which the steel plug would be broken before the cylinder was split open. " The experiment consisted in fixing one end of the plug repre- senting the projectile in a frame which was immovable, its other end being within the cylinder. The cylinder was fixed in the centre of a lever fulcrum, and capable of having a torsional motion given to it, by the application of weights on the extremity of a lever. The accompanying table shows the weight required to produce fracture on the several plans of rifling, and the diagrams will explain the exact form of the arrangement of rifling in the several systems." (See Table 109.) O6<5. CHARACTER OF THE GROOVES. The depth of the grooves has an obvious influence upon the strain brought upon the gun. Mr. Britten attributes his success in rifling old cast-iron guns, in part, to shallow grooves* (5 grooves r V m - deep, for the old 32- pounder). But Mr. Britten uses a very low twist (1 turn in 48 feet in the competitive experiments of 1861), and therefore requires but * " Construction of Artillery," Inst. of Civil Engineers, 1860. RIFLING AND PROJECTILES. 551 TABLE CIX. STRAIN DUE TO VARIOUS KINDS OF RIFLING. No. of Figure. KIND OF EIFLING. Nature of rifling. Breaking weight in tons at circumference. 3 I C Oval 7 O2 7l6 Decagon 27 2Q J 1U 717 Armstrong's .. .... Three-grooved shunt 2C ' 6estructivenes of Shells. Incapacity for bursting charge, Commander Scott's shell was found superior to all the others, in the competitive trial of 1861. (592.) Expand- ing projectiles are inferior to those mechanically fitted, in this regard; 1st, because the lead or other soft metal occupies so much space that the shell must be increased in weight and length (thus decreasing range and stability), to hold a given bursting charge ; 2d, because the centre of gravity is thrown back, causing still more instability. The advantage of the centering shell Scott's, 570 ORDNANCE. the shunt, and the French shells is obvious. In the Parrott shell, however, the expanding brass ring is so small that it adds little weight and practically occupies no space wanted for the bursting charge. The same is true of the shell used by Captain Blakely (571), and of other shells rotated by brass disks or rings. In projectiles having much lead or soft metal on the base, the bursting charge is mostly in the front, instead of being in the rear, where it would allow a strong thick head for punching, and then throw the fragments forward. 717. The advantages claimed for the Armstrong segmental shell (550) ; which is a common shell filled with one or more con- centric layers of small iron segments, are as follows : 1st, upon the explosion of the bursting charge, the segments, as well as the fragments of the shell are scattered in every direction ; 2d, one kind of ammunition answers the purpose of solid shot, shell and shrapnel. It is stated, however, that the segments sometimes rust together and produce little more effect than common shells ; and it is obvious that a shot already in pieces will be inefficient against armor or masonry. For field purposes, however, the seg- mental shell is, on the whole, successful. 718. There is no doubt that gun-cotton (see Appendix) will be exclusively employed for bursting charges ; 1st, because it is so much stronger than powder, for a given weight and bulk ; 2d, and chiefly, because the stronger the wall of the shell the greater the resistance opposed to the bursting charge, the more violent the explosion, and the greater the number of fragments. Hence the tenacity that enables a steel shell to penetrate armor, is the very quality that makes the shell destructive when it explodes. 719. Elongated Shot from Smooth- Bore*. Upon this sub- ject Mr. Michael Scott says* that the chase near the muzzle de- termines the direction of the shot, that this may be made perfectly straight, and that the projectile may be made to fit the gun per- fectly, and without any difficulty in case of breech-loading, but * "On Projectiles and Guns," 1862. RIFLING AND PROJECTILES. 571 that "the real difficulties consist in adjusting the centre of gravity, and correcting the want of symmetry in the shot." The first defect Mr. Scott proposes to overcome by making the shot in two or three unbalanced parts united by a longitudinal through-bolt upon which they are turned round till the whole is in balance. Longi- tudinally, the centre of gravity is to be adjusted by simply placing it in advance of the centre of figure. The form of the shot is to be made symmetrical in the lathe. 72O. It is probable that short shot fired from smooth-bored guns could be prevented from turning over by these means within the short ranges required for effective iron-clad warfare, and that the weakening of the gun by rifle-grooves and the strain due to rotating the projectile could thus be avoided. Such projectiles, however, if effective, would not require a special armament. Either the ordinary smooth-bore or a rifle adapted to firing round shot would fire these balanced projectiles; and the rifle would have the same advantage that it has over the smooth-bore in firing round balls the friction of the wad or sabot (which must take the grooves), against the shot, would give the latter a little rotation and proportionately increase its accuracy. 7S1. Yarious schemes have been devised for rotating smooth projectiles. When this is done by wings, or their equivalents, acting against the air after the shot leaves the gun, the velocity of rotation has been found insufficient ; more than this, the accuracy of such projectiles has appeared to be more impaired by the resist- ance of the air than that of ordinary projectiles which received their spinning motion before leaving the gun. 7S3. But it is possible that projectiles may be made to spin with sufficient velocity to insure accuracy by the action if the powder-gas, 'before they leave the gun; if such projectiles are centred, they should move with as much accuracy as others of similar shape after leaving it. 723. Among the plans proposed for this purpose, Mr. Besse- mer's is illustrated by Figs. 336 and 337. Channels, w, formed in the exterior of the projectile, conduct the powder-gas to the front, 1). The forward end of these channels is sharply inclined so 572 ORDNANCE. that the gas escapes nearly at right angles with the bore, and thus causes the shot to recoil in an opposite direction. No adequate test has been made of this plan ; in some preliminary experiments, Mr. Bessemer found that an elongated shot fired from a 12-pounder smooth-bore did not turn over in going 900 yards, and that its accuracy was much greater than that of spherical shot from the same gun. The shot made 2-J revolutions in the gun (8 feet length of bore), charge, 2 Ibs. 724. The Mackay projectile operates on a similar principle. The inventor's patent specification states that " the improvements consist in the application and use of diagonal grooves formed in the interior surface of the gun at a greater angle than hitherto FIG. 336. FIG. 337. Bessemer's shot for smooth-bores. employed, which are to act as windage grooves, so that the powder and gas passing down such grooves encircling the projectile shall have a longer distance to travel than the projectile, and also cause the projectile to revolve round its longest axis at a high rotation as it passes down the gun. The projectiles are not allowed to enter or fit these grooves as in rifles, but simply to pass down the smooth surface in which the grooves are formed." The inventor also specifies means of balancing the projectile. This system has some notoriety in England, and is understood to have given good results. 725. Conclusions. Guns for naval and sea-coast warfare are required to punch and smash armor, to breach masonry, often at long ranges, to shell distant works and encampments, and ves- sels that are not iron-clad. But since vessels having practicable size and draught, and adequate protection, can only carry a limited number of the large, strong guns required for these purposes, each RIFLING AND PROJECTILES. 573 gun, or the greater part of a ship's guns, should be capable of every kind of service. Therefore, 1st, the rifling should leave so much of the original bore untouched, that it will not be injured by spherical shot ; 2d, it should have a tolerably rapid twist for the purpose of sustain- ing and giving accuracy to long projectiles ; 3d, it should oppose the least possible resistance of wedging and friction to the pro- jectile, so that the highest possible velocity may be attained. The rifling decides, to a certain extent, the character of the pro- jectile. A small number of grooves (to fire spherical shot well) and a rapid twist, are likely to strip both the compressed projec- tile, for that must be soft-coated, and the expanded projectile, for the part of that which takes the rifling must be tolerably soft and quite short. But the centering system admits of a hard-metal bearing, as well as a soft-metal bearing, in cases when the latter is at hand or is from any cause desirable. So that as far as the number and the twist of the grooves are concerned, the centering system would appear to be the best. Wedging and friction due to the shape of the grooves may be equally well avoided in all the systems. But the best kind of projectile is to be further determined by other considerations, independent of the rifling. The compressing system has three principal defects : 1st. It unduly strains the gun by suddenly stopping the windage, by foul- ing, and by forcing the shot into a bore of smaller diameter. 2d. It reduces the velocity of the shot by the compression and the fouling. 3d. The increasing twist is impracticable, from the great length of the soft-metal coating. 4th. The soft-coated projectile is liable to. injury in handling and in store. 5th. The windage is entirely stopped, thus increasing strain, possibly decreasing accuracy, and rendering the use of time-fuzes uncer- tain. 6th. Soft coatings are likely to be so much loosened by the heat of molten metal that shells could not be charged with it. 7th. The compressed shot must be fired from a breech-loading gun. The advantage of the compressing system over the expanding 574 ORDNANCE. system, but not over the centring system, is, that it holds both ends of the shot in the centre of the bore during its passage. If a soft-bearing surface saves the bore, it is equally applicable to the expanding and the centering systems. The chief defects of the expanding system are : 1st. The centre of gravity is almost necessarily behind the centre of figure ; and, 2d, the bearing of the projectile is behind the centre of gravity ; both of which features tend to cause inaccuracy. 3d. The sudden stopping of the windage unduly strains the gun. 4th. Fouling and the violent wedging out of the soft metal to fill the grooves, are obvious sources of strain. 5th. The shot is liable to injury, and the disadvantages in firing time-shells and shells filled with molten metal, are the same as in the case of compressed projectiles. The expanding system allows the use of brass or copper bear- ings which will take the increasing twist very well with moderate charges, and which appear to injure the grooves less than pure or hardened lead. The centering system, as practised by Mr. Whitworth, Mr. Lancaster, and others, who use grooves that the shot can wedge in, strains the gun unduly, and decreases the velocity of the projectile. But the French system, and particularly the system of Com- mander Scott, bring the minimum wedging strain and friction upon the gun, place and hold the projectile in the centre of the bore without shock, allow its centre of gravity to be in the centre of figure, and support the projectile at or on both sides of its centre of gravity, thus promoting velocity and accuracy. The centering system may further decrease the strain upon the gun by allowing windage and the increasing twist. The hard pro- jectile is not liable to injury in transportation or in store, and it can carry molten metal with safety and light time-fuzes with certainty. For field-guns, various expanding projectiles are successful, and for heavy guns, the Parrott projectiles and those used by Captain Blakely have done good service. But the obvious mechanical advantages of the centering system, as well as the good results of the shunt guns, the guns rifled upon Commander Scott's plan, and especially the results of the French guns, indicate that this system RIFLING AND PROJECTILES. 575 will be adopted for heavy ordnance. The best results, including the firing of spherical shot, that have been attained with heavy rifles, are those of the 10'5 in. and 13*3 in. guns constructed on this plan. In these guns the projectile is centred by brass studs substantially on the French plan. The distinctive feature of the Armstrong shunt system compressing the shot at the muzzle is being gradually abandoned. 576 ORDNANCE. *C fl ^"* *;' S v2i ^ ^ ^, 1 | 1 1 1 i 1 8 o 8 -a ? ' is ^ ^o . O O v^ O O O oo v^ oo oo oo 5 5 r^ k M * * r< O oo O v/ ^ IT; vo O rt t^* oo , M M T$- rl t~- ^- O i 00 t-- 00 t-^ ^ vo rt ^O rt ^ 2 ^ II 1 i M oo co O t-^ O O oo ^O co O m CO w o M O O vn w> to co co ^ S'S CO M M M M M M M i 3 V -o 6 O c u 1 t 1 sill -C -^ T3 T3 S o c : c - S- -o c c CUV -. 2 2 3 3 3 2 i N .2 W T3 T3 -3 -o c c 4! i C 6 -o 3 Jll i g M !s 5 ; * * * * c< r. H rt H S , t*- O * C - 13 . ro ^ I? . : : Il r d 5 . o * VO "Si 3 i oo ^, s s . JVO vri . s c - 00 - SH 1 "^ c i i al O O WOO vO ro 1 S, 23232 M c i & bO bfl fcJO -C c e C *^ 2 8 2 1 E E E 15 I RIFLING AND PROJECTILES. 577 .. .~ . o o -~ o - Q o -~ " O "^ o f"> O IT o IT o IT 8 ( f> ( O 4^ *j t^> -! j-i rj- O w ^S 8 IS o- vg^ -- - ,: ^ rt M oo w .2 .2 M ro " M Ox CN H< *- 4- *I3 *J ."H ."2 J^~ | ON ^ .^ .. ^ 8 _ o _ ^ 8 is is is is .S .S 15 *-. oo 2 'S . w 'S *j r^ ^ 'c . _, :|1 |"8 :|1 5 , ? S Tj- 00 'c vo .S w '"* "2 ^ " 1 r *^" o" vo 1 IT ON ON O f") >, CJ >.M VO >, 00 OS M M M O VO VO O OO O H oo to l- M HI M IH M M jp c n _g T3 I 3 CO 1 Ji 1 * .* J ^ U .. ** 2 ** ** U3 *J w *S CO JS c 3 3 * 1 1 CO .1 1 o 0- co H vo \ r> o ^ ? 8 M 11 2 "" M * 00 jj 2 S ^o o 13 o ro ? H VO >,M II * t CO ro VO ON r X 4- 4- oo vo o^ . 5- oo M 2 i 0^ iT 8 ON o ro ro ^- rt 2 1 bi) -o 1 u 0. C 'u S cu jrf CO 1 g a o u I?* 1 3 1 1 1 i o V o o u -o _^ .2 1 H3 c 3 O -o a -o -0 C u *u J5 T3 i u J Oi C JQ P5 c "rt c 0, ** 1 -0 c U '5 U -o c 0) rt 8 U 1 E c* *s . VO u a| Teg | ^ ^ vo ON "-1 H J o o * T*- vo t^ E vo $5 . * 1 1u "o vo -o r^ M ^> M C " c U ro ^ s .S ^ N t^* x OO vO 5 r ^ c5 ^ VO O p to ro ^. ^. H 5 o M HI * vo vo J "S | * * 50 .5 vo - vo * 4- 2 ro iT* J* 1 ro d VO il f! ' ^ oo ? ^* T . vO t) oo " 1-4 3 00 3* 1 ~ rt * l-l ^^ $d ^ 5 vo J^- oo W-l VO o" 00 U - oo CO * - C s- C O ,_ 3 S ' c C c M M ^ c 3 i i c i J3 C^ J j u a3 1* cS j rf b O d i a 6 . u< t^ &H ^ r^ (X s i M t f c^ PQ c vo e '7 O C C to | Whitworl | i < 1 M ^ I < Rodman n 2 Horsfall i RIFLING AND PROJECTILES. 579 ^of 8 i, 8 rt M O .~ ^. ^ O "PJ ayo at I no t T o 2 -1 .13 1 _^ i vo '3 ** 1 1 1 I'TJ o o o o !5 '.5 c 00 loo C w 5 C 10 c w o o o o c c c -IT ;I "S M 5 c o7 ^ ON rt ON ""** Q .S cT w "" vS " TN 00 00 M M M 2 ^0 -0 O c* >-. n in M CO * ? w M ON CO oo CO fT oo 00 M VO VO VO NO VO VO ^ so Wl 1 I O 13 ^ O ^ S 13 s CO "w o "OT "^ "j3 s. "(3 *pj o "73 - > a ' '^ * "3 TS 13 O y S3 C u a 13 c u n 'n S3 Cu co CO CL, '5 co* H-, OH CO CO CL, CO ex co | 00 00 rt v^ VO v) VO VO vo vo ro oo ? 00 rf- U-. 00 oo <* s. 00 00 O 00 j . ' 5 " 5 oo oo 2 ON o\ ON ON r^ i>- M o oo -* S 2 \ xj-) O O *r o OS 00 --< oo oo H ON r ON M M 1) :z : -a e 3 : : c : 3 a 2 13 I o -3 3 O c i 6 vo B 3 3 c 6 00 8 ? 1 00 ^3 i w ^ . - s y 2 ^ O - to C 6 u oo e 3 ^ 1 <* r> c 1 i CO' ."i Q A C co' < z> M < CQ 3 580 ORDNANCE. CHAPTER VI. BREECH-LOADING. 726. Advantage and I>efect of the System. This subject can hardly be considered of the most immediate and paramount importance, for various reasons : 727. First, the practice : No efficient breech-loading cannon of large calibre has been introduced into any service. In the United States there is not even breech-loading field-artillery in service, and no experiments have been made in this direction with heavy guns, either for the army or for the navy. In Russia, the solid-steel and the hooped guns constructing for naval, garrison, and siege purposes, are exclusively muzzle-loaders, as were the old cast-iron guns which they are intended to replace. 728. In France, one of the best systems of breech -loading has been applied to naval ordnance, but not to calibres exceeding 6*5 inches; and these guns can hardly be called formidable when compared with the British steel-lined 9-inch and 10'5-inch guns, the American hollow-cast 10-inch Parrotts, and 10, 11, and 15 inch Rodmans and Dahlgrens, or the 8, 9, and 11 inch Russian steel cannon, all of which are muzzle-loaders. 729. In England, the largest service breech-loader is the 110- pounder Armstrong, a 7-inch gun which burns only 12 Ibs. of powder, which cannot fire round shot, and whicli is far inferior, when measured by penetration in armor, to the old cast-iron 68- pounder. The 110-pounder is no longer considered by the Arm- strong party as a proper gun for iron-clad warfare. No service breech-loading guns are constructing in England, either for the army or for the navy. 730. The practice in other countries than those mentioned is of less importance, for obvious reasons. In England and in America, the subject of ordnance has received more aid from BREECH-LOADING. 581 mechanical engineers, and from ample appropriations, than in all other countries; and neither in England nor in America has breech-loading been attempted with the heaviest ordnance. In one or two European States the "Wahrendorff and Cavalli breech- loading guns are employed to some extent ; but these are generally cast-iron guns of limited power. Mr. Krupp has made a few very good steel breech-loaders on his own plan (767) for European governments. The guns furnished to these, and to other govern- ments, by Captain Blakely, and the larger hooped guns generally, as in Spain, for instance, are muzzle-loaders. Breech-loaders are almost exclusively field-guns. So that the best practice is clearly unfavorable to the system. 731. The opinion of those who have had the most experience, although it must be admitted that the experience was chiefly with a very troublesome apparatus, is thus expressed by the Select Committee on Ordnance, in 1863 : " The preponderance of opinion seems to be against any breech-loading system for the larger guns." 732. Second. The grand defect of the best breech-loading guns has been inadequate material. Although Mr. Krupp's steel breech-loaders up to 7 inches calibre have shown extraordinary endurance, it by no means follows that this best material would stand proportionate charges in guns having twice the calibre, and burning four times the powder. And even if the material were adequate, the cost of a durable breech-loading apparatus would buy another muzzle-loading gun of the same material. To add as much strength to the reinforce as a transverse mortise would take away ; to construct and fit up interchangeable hollow screws or sliding stoppers ; to fit and renew gas-checks ; to apply open- ing and closing apparatus, which cannot be very simple, but which must be very strong and durable ; to fabricate, keep clean, and maintain all these parts on such a plan that two or three men can manipulate them with ease and certainty, and without unusual risk of disaster from excitement or carelessness, and of such size and strength that projectiles of 300 to 500 Ibs. weight can be fired with 50 to 70 pounds of powder, must necessarily 582 ORDNANCE. involve an outlay which is only to be justified by greatly increased efficiency, if, indeed, it can be accomplished at all with the present materials. 733. Third. An objection to very rapid firing from large guns is straining the gun from the heat of the inflamed gases. (336.) " The tendency of all guns to absorb the heat developed during explosion puts a limit to all extreme rapidity of fire. During the late Russian war, at Sweaborg, it was found necessary to allow an interval of five minutes between each discharge of a mortar, and yet the whole of them burst after an average of 120 shots."* It is practicable to cool the gun after each discharge by a large quantity of water injected by machinery (748). But the same machinery that injects water may ram home the ammunition, however bulky, in less time than that required to adjust the sim- plest breech-loading apparatus Ijy hand. 734. Other objections, which may not be serious in all cases, and which do not outweigli any substantial advantages, are as follows: There are more parts to be damaged. Captain Coles said before the Select Committee on Ordnance, in 1863: "In muzzle-loading there is the simple chance of bursting ; whereas, in the Armstrong there are five different parts, upon any one of which getting out of order, your gun is Jiors de combat" The accumulation of dirt, and the necessity of constant lubrication, are at least embarrassments in action. The increased weight of the breech-loader is thus mentioned by Sir William Armstrong himself :f " Breech-loading guns of any given power would be heavier than muzzle-loading guns ; and now that we are so limited for weight, in order to get the necessary power to produce the required effect upon armor-plates, its increase of weight becomes a very formidable objection." Want of safety is very fairly urged against breech-loaders, of which the vent-pieces and other parts blow out in service ; but it cannot be fairly urged against the system. * "Ordnance and Naval Gunnery," Simpson, 1862. f " Report of the Select Committee on Ordnance," 1863. BREECH-LOADING. 583 735. Fourth. The grand advantage claimed for the breech- loader is, that it fires faster. More shots can, undoubtedly, be got out of it. But in cases where the aim is of any importance, it is not the loading, but the sighting of the gun that takes time.* All guns used in iron-clad warfare, afloat or ashore, and all naval guns, must fire either from an unstable platform, or at a moving object, or both, which requires a readjustment of the line, or the elevation at every round. There are, indeed, likely to be cases of a siege-gun recoiling on a chassis so firm that its position would not require alteration, or an iron-clad battle at such close quarters that all projectiles would strike the enemy. In such cases, every thing might depend on mere rapidity of fire. 736. But there is neither practice nor experiment to prove that very heavy guns can be loaded by hand, more quickly from the breech than from the muzzle. Even in the smaller pieces, the breech-loader is admitted to possess.no practical advantage in this regard. Before the Select Committee on Ordnance, in 1862, Mr. Whitworth said that he was not a partisan of the breech- loader, " the muzzle-loading gun being so much more simple, and equally rapid for loading." Sir William Armstrong said before the same Committee in 1862, and said again in 1863, that " a rifled gun loaded at the breech may be more rapidly fired than a rifled gun loaded at the muzzle, because the fouling of the bore presents no impediment to the insertion of the bullet when introduced from behind ; but as compared with smooth-bored ordnance, of the ordinary description, there is probably nothing to gain in point of quickness of firing." The practice with nearly all the rifled projectiles used in the present war, and with many experimental projectiles abroad, would indicate that Sir William's objection to muzzle-loading rifles is unfounded. The advantages of smooth-bores for iron-clad warfare have been considered ; as to * "The facility of loading, and rapidity with which a breech-loading piece can be fired, are spoken of as advantages of great importance, but these amount to nothing ; for the gun, after every discharge, must be relayed in order to obtain accuracy of aim, and it is the pointing of a gun, not the loading, that consumes time." "Ordnance and Naval Gunnery" Simpson, 1862. 584 ORDNANCE. smooth-bores, Sir William thinks nothing is to be gained by breech-loading. 737. Two batteries of 9-pounder Armstrong breech-loaders, of the most approved form, fired 100 rounds per gun in about 100 minutes, in experiments at Dublin. This included the time occupied in moving the batteries six times and in putting up the targets twice. On one occasion 17 consecutive rounds were fired in 8-J- minutes, or at the rate of 2 rounds per minute. On another occasion, at Southsea, with old Armstrong breech-loading 9- pounders, and old ammunition, 123 rounds were fired in 138 minutes, including 30 minutes' delay, or at the rate of 1 round in 87 minutes. Another 9-pounder was fired 40 rounds in 31 minutes, or at the rate of 1 round in "77 minutes.* 738. Muzzle-loading field-cannon are fired more rapidly. "Field-cannon can be discharged, with careful aim, about twice per minute ; in case of emergency, when closely pressed by the enemy, canister-shot may be discharged about 4 times per minute. The 12-pounder boat-howitzer of the navy, with experienced gun- ners, can be discharged at the rate of 16 times per minute."f 739. The most rapid firing that is recorded, from the heaviest breech-loader, is 50 rounds from a 110-pounder wedge-gun (760), which is obviously more quickly manipulated than the service 110-pounder, in 21 minutes, or at the rate of 1 round in '42 minutes. The heaviest service ordnance in the world, the U. S. 15- inch columbiad, is loaded and fired by hand when mounted on the wrought-iron barbette carriage, in 1 minute 10 seconds. Traversing the chassis 45 requires an equal amount of time. The Monitor 15-inch guns have been fired, mounted as they are in small turrets, with but 30 inches space between the muzzle and the muzzle-box, in 3 minutes. The 400 to 425 Ib. balls had to be raised by a fall, and the rammer was jointed and run out through a hole in the port-stopper. Training and aiming the * "Report of Select Committee on Ordnance," 1863. f " Ordnance and Grunnery," Benton. 1862. BREECH-LOADING. 585 Monitor guns is a much longer operation. The 600-pounder Armstrong was fired during the first experiments, once in 10 minutes; the 8-in. Colurnbiad, experimentally, once in 2 minutes. 740. It is probable that a very heavy gun can be the more quickly loaded from the muzzle for various reasons. In either case the ammunition must be lifted to the height of the bore ; in either case it must be inserted into the bore. So far, the slight advantage of the breech-loader is that the ammunition has to be moved laterally but two or three feet, while the muzzle-loaded ammunition has to be moved the whole length of the bore. But in manual operations especially, it is not so much the continuance of effort already commenced, as it is changing the direction and means of effort, that consumes time. Hamming a charge a few feet farther, when the apparatus is adjusted, is not a serious disad- vantage of the muzzle-loading system. Again, the gun would be almost constantly elevated, so that gravity would help the move- ment of the muzzle-loaded ammunition, and retard that of the other. Were the gun depressed, or were the ship rolling, the breech-loaded spherical shot, at least, would also require a wad to be loaded from the muzzle. Fixed ammunition, with a sabot tight enough to retain the projectile in its place, would be too heavy and too tight for hand-loading. Again, a breech-loading gun, in a small turret or a narrow-waisted vessel or casement, would have to be run partially out to be loaded, while the recoil drives the muzzle-loader to the proper position for loading. 741. But the grand disadvantage of the breech-loader is yet to be mentioned. There is always a hole open in the muzzle- loader, for the insertion of the charge. 'No time is wasted in taking the gun apart and putting it together again, for that pur- pose. But the removal and insertion, or even the double move- ment of vent-pieces, screws, or wedges, which are at least as heavy as the ammunition, and which will occasionally stick fast for many minutes, is just so much labor in addition to raising and inserting the charge. When all the parts are so light that few enough men to keep out of each other's way, can handle them as fast as they would naturally move their arms, the case is entirely changed. o86 ORDNANCE. 745J. Fifth. As to the convenience of loading from the breech in narrow turrets and casements : the Monitor guns recoil but four feet, bringing the muzzle but 30 inches out of the muzzle- box. Although the operation of loading and firing has been ex- perimentally performed in three minutes, by means of a jointed ramrod run but of a hole in the port stopper, the two men who have room to work it, can hardly be expected to send the 50-lb. cartridge and 400-lb. shot home at that rate, throughout an action, especially if there is any rolling. The breech-loader offers no better facilities for hoisting and entering the ammunition, and saves but little time in the ramming home (740) when the muzzle does not project through the port, as in the Monitors. When the gun is run out of the port, ample room is of course left behind it, but the muzzle is then exposed to the enemy's fire. In casemates only as wide as the length of the gun, the piece may be loaded at the breech, but obviously cannot be loaded at the muzzle. And there is perhaps greater safety in loading at the breech. This whole subject, however, is relieved by the use of machinery for working heavy guns, and will be further referred to. Captain Coles, who is certainly an advocate of whatever will advance the turret system, uses muzzle-loaders in his vessels, and testified before the Select Committee on Ordnance in 186.3, that he pre- ferred and had asked for muzzle-loaders to arm the Royal Sovereign. Captain Ericsson has recently constructed muzzle- loaders (127) for his best turret-ships the Puritan and the Dictator. 743. On the whole, the heavy breech-loader cannot answer, it should seem, the grand purpose of the small breech-loading arm- rapidity of fire. Its other advantage convenience of loading in close quarters, may not be of great importance. But its grand, and in the present state of the art, remediless defect weakness is likely to outweigh all its advantages. 744. It will be suggested that machinery be applied to the movement of heavy breech-loading apparatus and to the ammu- nition. But less machinery will produce the same result in the case of the muzzle-loader, for there, the ammunition only, has to BREECH-LOADING. 58' be moved. And if the machinery to load the muzzle-loader is disabled, the gun can still be loaded by hand, while-if the breech- loading machinery is disabled the chances are that the breech cannot be made tight again certainly not without clearing away the wreck and adjusting new parts. 74*5. EAPID FIRING BY MACHINERY. The advantages of rapid firing are too obvious to require explanation. The gun-carrying parts of manageable ships must be small in extent if they are thick FIG. 337 A. French iron-clad two-decker, Solftrino. enough to be invulnerable ; so that a few guns must do the work of a broadside. The inadequate offensive power of such vessels in which the guns -are worked by hand, in the Monitors for instance, is not due to a small number of guns but to a small number of projectiles fired. If a ship carrying six 20-ton guns can fire each piece once a minute, while a ship of the same size and dis- 588 ORDNANCE. placement, carrying thirty similar guns, can only fire each piece once in five minutes, then, other things being equal, the latter ship must have 480 tons less armor over five times the area to be protected. 746. The practice in some quarters would seem to indicate that a greater number of guns is the only consideration in naval warfare. The French, for instance, have sacrificed armor-carrying power, increased top- weight, enlarged the space to be fired at and otherwise impaired the defensive qualities of their recent frigates, all for the purpose of piling up two stories of little 30-pounders. These 30-pounders, fired in rapid salvos, are not indeed to be de- spised, especially by ships that can fire but two guns in a quarter of an hour. But it is strange that when so many millions have been spent in the widest departures from the old systems of ship- building, ordnance and projectiles, not a single adequate experi- ment has been attempted, for the purpose of increasing the rapidity of fire from heavy guns, and thus vastly increasing the protection of vessels without decreasing their offensive qualities. Doubling the rate of discharge, other things being equal, would quadruple the resistance of armor, because it would reduce the number of guns and the length of battery one-half, thus doubling the thick- ness of the remainder ; and the resistance of armor is as the square of its thickness. 747'. But the heating of the gun, urged against breech-loading, on the supposition that breech-loading would increase the rapidity of firing, may be as well urged against any means of promoting the rapid discharge of cannon. Indeed, this is the only serious objection, for it has been admitted that accurate aim, which takes more time than hand-loading even, is of small importance at very close quarters ; and the faster of two opposing vessels has the power to make the fighting as close as possible. 748. The heating of a gun, however, can be prevented by the most certain means the introduction of water by machinery. So long as it is done by machinery, any necessary quantity of water can be injected ; and flooding the gun at the instant the charge has left it, must, of course, abstract the heat before it has pene- trated much beyond the interior surface. Thus the proper initial BREECH-LOADING. 589 strains of the gun will not be disturbed, and the bore will be thor- oughly cleaned. 749. Mr. Edwin A. Stevens, of Hoboken, has devised a very simple arrangement for cooling guns with water, to be applied in connection with his steam-loading apparatus.* This will be fur- ther referred to. 750. Loading by steam with great rapidity, has been actually practised by Mr. Stevens. The apparatus was rudely constructed, but this only shows that delicate parts and nice adjustment are unnecessary. Fig. 338 illustrates the machinery as designed for the 15-in. guns of the Stevens Battery. The experimental apparatus (to be further considered) consisted of the same parts, excepting the water-cylin- der and the steam-cylinder, 7?, for hoisting the ammunition. The muzzle, (7, of the gun being depressed to receive the charge, the cartridge, P, and the ball, D, connected together by the wooden sabot, E (which also prevents the ammunition slipping back) are rolled (not lifted) upon the scoop, T, when the latter is in the posi- tion U. The scoop is then raised to the position shown, by means of the lever, S, and the steam-cylinder, R. By moving the handle, H, steam is then admitted to the long inclined cylinder of which the piston-rod, /", is the ramrod of the gun ; the charge is thus shoved out of the scoop into the gun, and home. N and are the steam and exhaust pipes leading to a boiler and to a condenser or into the atmosphere. The gun is then elevated (by machinery, in the design for the battery), fired, and depressed. The cock, A", is then turned so as to admit water from any convenient vessel into the pump, of which L is the hollow plunger. The rammer, J/^ also a swab, is then run into the gun by moving the handle, ZT, carry- ing up with it the pump-piston, Z. As the rammer is withdrawn, the pump-full of water is forced, by the automatic operation of the common pump-valves, through the pipe Z, and out of numerous orifices in the rammer-head, Jf, upon the whole surface of the bore, * It is proper to state that, although the steam-loading was devised and the cooling by water suggested by Mr. Stevens, the details of the plan as shown, were proposed by the author. 590, ORDNANCE. DQ BREECH-LOADING. 591 from tlie chamber to the muzzle. This operation may be repeated in a few seconds, or a limited quantity of water may be let in by adjusting the valve TF", as the case may require. The valve K is then shut, the ammunition having, in the mean time, been rolled upon the scoop 7, and the loading proceeds as before. The whole operation of sponging, cooling, and loading, may be performed as quickly as a man can make eight passes with levers within his reach. The water from the gun will not injure cartridges in metallic cases, and may be conducted to any convenient place of discharge. The whole apparatus, if disabled, may be removed by knocking out a few keys, thus leaving the gun free for hand-loading. 751 . The gun used by Mr. Stevens was mounted on a fixed car- riage (Fig. 339) like the NaugatucKs (Fig. 339 A), the trunnion- slide, A^ being simply backed with eighteen 8-in. disks of India- rubber 1-in. thick each, to take up the recoil. In front of the trunnions, half the thickness of rubber took up the counter recoil ; the gun almost instantly stopped in the position from which it started. The Naugatuctfs gun, shown by Fig. 339, was a Parrott 1 00- pound er. The gun is trained with great precision by turning the vessel (Figs. 339 A and B) on her keel, by means of twin screws. The gun is loaded from below deck, by apparatus resembling that shown in Fig. 338, except that it is operated by hand. The ves- sel is lowered, in action, to the deck, by filling the compartments m m with water. 7*>!2. But the gun is not necessarily depressed for loading. In a casemate, afloat or ashore, the gun may be wheeled round and steam-loaded horizontally. A patented plan for doing this in a small space is shown by Fig. 339 C,* and another by Fig. 339 D.f A turret may be turned, after each discharge, to a small shot- proof loading-house on deck. Rough machinery, situated within armor or below water, to revolve a gun or its carriage, is as * James Hyde, patented Dec. 23, 1862. f C. F. Brown, patented June 19, 1862. 592 ORDNANCE. I BREECH-LOADING. 593 FIG. 339 B. practicable as the delicate and complex mechanism of a frigate's steam-engine. A gun recoiling to various distances by the old. apparatus, may be readily placed, by machinery, at the proper distance for loading; and Mr. Stevens's experiments have shown that the axis of the gun need not be exactly coincident with that of the loading cylinder, nor the gun always placed for loading at a fixed distance from the cylinder. 753. Mr. Stevens's experiments are thus described in the official report:* Experiments of January 4th, 1862. " A 10-inch gun, procured from the Navy Department, weighing 9883 Ibs., Cross section of the Naugatuck. FIG. 339 C. FIG. 339 D. was mounted with India-rubber buffers behind the trunnions. This gun was loaded with the full service charge of 11 Ibs. of powder, and a solid spherical ball weighing 124 Ibs. * * * This gun was loaded by steam power, the muzzle being depressed so as to bring the bore parallel with a steam cylinder situated below a platform made to represent the deck of the battery. The piston-rod of this steam cylinder was the ramrod of the gun. Upon the upper end of this ramrod was a swab which also answered the purpose of a rammer. The cartridge and ball were "The Stevens Battery Memorial to Congress," 1862. 38 594 ORDNANCE. attached to a sabot and placed on a scoop arranged so as to lift the ball to its proper position between the rammer and the muz- zle of the gun, when steam being admitted to the cylinder, the ball was forced home. The gun was then elevated and fired." Experiments of January llth, 1862. "The 10-inch gun, mounted as before described, was loaded by steam with 11 Ibs. of powder and a 124-lb. ball, and fired four times with the same charge. The entire time occupied by the four shots being 139 con- secutive seconds, and the average time being 34f seconds. The quickest time was 25 seconds. The average was increased by the failure of a friction-primer to go off. A 225-pound elongated shot was afterward fired with 4 Ibs. of powder, having been loaded with the same rapidity as the 124-pound shots, and the recoil being less." It should also be recollected that the ammunition was raised to the muzzle, and that the gun was elevated and depressed by hand. 754:. Mr. Eads, of St. Louis, builder of most of the Western iron-clads, has put in operation a plan (the idea having been also suggested by Mr. Stevens and others) of raising the gun and carriage bodily by steam from below the water-level, at the moment of firing, and then dropping it for loading and for safety when not in actual use. Steam-loading is obviously practicable and convenient in case of guns thus mounted either in vessels or forts. Mr. Cunningham, the inventor of the reefing apparatus bearing his name and extensively used on every sea, has introduced a very simple method of running guns in and out by steam power. Mr. Norman Scott Russell has devised a practicable plan of moving heavy guns and taking up their recoil, by hydraulic machinery. Mr. Mallet has invented hydraulic machinery for the elevation, running out, and training of heavy guns. Various other schemes for performing one or all of these opera- tions by steam-power have been put forward. Many of them are obviously practicable and applicable to steain-loading. In fact, working heavy guns better by steam than by hand labor is not a BREECH-LOADING. 595 very difficult problem. Of course, the subject demands, arid is worthy of the highest engineering talent. 755. Standard Breech-Loaders described. ARMSTRONG. Two forms of loading at the breech are employed in the Arm- strong guns the screw and the wedge or side breech-loader. The screw, which is used in most of the service guns, is generally illustrated by Figs. 340 to 346. The breech-piece D, Fig. 344, which forms a continuation of the second tube J, receives in its rear a hollow screw, A, of about the diameter of the inner tube, so that the bore of the screw forms a continuation of the bore of the gun, except that it is a little larger in diameter to allow of the easy insertion of the projectile. At the forward end of this screw, a vertical mortise, G, is cut in the breech-piece for the movable vent-piece E. The vent-piece, when inserted, forms the bottom of the bore, and when removed, opens the bore from end to end of the gun. To hold the vent-piece firmly during the explosion, the hollow screw is turned hard against it. The explosion of the powder reacts through the vent-piece upon the forward end of the screw, and through the screw-threads upon the breech-piece, w r hence it is transferred by the tenacity of the longitudinal fibres of the breech-piece and. the friction of the rings which embrace it, to the trunnions. To load the gun, the revolving hammer B attached to handles at the rear of the gun, is struck upon projections on the screw, (C, Fig. 345), thus starting it back, when it is easily unscrewed enough to allow the vent-piece to be lifted out. The bore of the gun is then open from end to end and may be sponged* and loaded from the rear. 75G. The breech-screws for the smaller guns are solid forgings of steel. For the 40-pounders, 70-pounders and 110-pounders,f they * The army gun is always not sponged, but is cleaned by a greased wad. See " Rifling and Projectiles." | It is worthy of remark that, in 1862, some steel forgings for 110-pounder vent-pieces were returned from Woolwich to the makers as being unsound and unfit for use. These forgings were afterwards put to the most severe tests, displayed in the Great Exhibition of 1862, and noticed by experts as very fine specimens of tough steel 596 ORDNANCE. BREECH-LOADING. 597 are of wro light-iron, with steel ends to bear against the vent- pieces. 757. The vent-pieces have been made of wrought iron, hard steel* and sandwiched iron and steel, which respectively mashed, cracked, and split. Steel toughened in oil is now employed. 758. The gas-check for the smaller guns consists simply of a ring of copper let into the face of the vent-piece and jammed against the end of the powder-chamber (Fig. 16, page 9) by the screw. A bushing of iron is sometimes employed in the larger guns. In the 110-pounder, it has been found necessary to attach a tin cup, similar in position to the steel cup in Krupp's gun (Fig. 348), to the face of the vent-piece ; this cup projects into the powder- chamber, and forms, by its expansion, a tolerably good gas-check, although it stands but one round. But with this form of gas- check, the screw and the vent-piece are unnecessary. The required accuracy of workmanship and liability to derangement may how- ever be inferred from the following instructions taken from British Artillery records : " The allowance between the nose of the vent- piece and powder-chamber should be exactly j-/^ of an inch or T o*o o- difference in diameter. If less than this is allowed, any burr or upsetting of the vent-piece nose will cause it to jam in the gun, and if a greater allowance is given, the edges of the cup will be split open and blown by the gas into the space, and the faces will be destroyed." 75O. Sir William Armstrong stated in his evidence before the Select Committee on Ordnance, 1863, that 300 rounds was a very good endurance for a vent-piece, theoretically ; and that practically, but 117 had failed during the firing of 30,000 rounds. This would give 256 rounds as the average endurance. The vent is made in the vent-piece so that it can be readily re- newed in case of undue enlargement. f * It is stated that 484 vent-pieoes of unsuitably tempered steel were made at "Wool, wich at the cost of 10,000 to 12,000, and then abandoned without trial. f "The present 110-pounder service rifled gun has a movable breech-piece, which requires two primings that is, the lower part of the vent-piece is first primed, and when this vent-piece is placed in the gun a tube has to be put in on its top, and thus on discharge the gun hangs fire from two ignitions, and the shot is afterwards detained 598 ORDNANCE. 76O. Another method of closing the breech has been considerably employed in the later experimental Armstrong ordnance. It is called FIG. 345. Breech of 40-pounder. From a photograph. the side or wedge breech-loader, and may be generally described as a cross-piece or sliding-block inserted in a horizontal mortise which inter- sects the bore at right angles. This block is fitted with a sliding ham- mer, and has on its face, which forms the bottom of the bore, a thin iron or tin cup (similar to volving the latter through halt a circle. 767. KRTJPP. This is generally pronounced in England the most simple, strong, and trustworthy breech-loader that has been subjected to extreme proof. It consists of a block, sliding in a * ""We understand that the farther manufacture of 100-lb. lead-coated shot for the Armstrong breech-loaders has been stopped, as it is in contemplation to convert the guns into muzzle-loaders, firing non-leaded shot, so soon as the 70-pounders now in process of conversion from breech-loaders are finished." Army and Navy Gazette. August 13, 1864. BREECH-LOADING. 603 horizontal mortise crossing the bore of the gun. The gas-check is a steel ring L- shaped in cross-section. Fig. 348 is a horizontal section of the breech, copied from Mr. Krupp's English patent, of Oct. 29, 1862 : ISTo. 2910. The bore af is continued throughout the length of the gun. The sliding- block 5 is lightened by the removal of metal at e and d (see also Fig. 352), and is started out by the lever m, secured to the hinge o y and bearing against the piece n, which may be renewed. The FiG. 348. Horizontal section of Krupp's breech-loader, steel ring , is withdrawn with it, and may be inspected or renewed during the loading. This -form is employed in the guns put to extreme test at Woolwich ; the breech of the 110-pounder is shown, with the sliding-block in place, by Fig. 350, and with the block re- 604 ORDNANCE. FIG. 349. moved, by Fig. 351. Fig. 352 shows the sliding-block in per- spective. In loading, after the block is started out by the lever, it is easily drawn out, being guided by proper grooves, until the charge will pass through the opening d, Fig. 348, into the chamber. Other metals than steel may be used for stopping the gas. Cups of pasteboard, even, were used in the first 6-pounder tried at Woolwich. One of them stood 7 rounds. 769. In 1862, three of Mr. Krupp's breech-loading steel guns were tested at Woolwich a 20-pounder, a 40-pounder, and a 110-pounder, of 3'75-in., 4'75-in., and 7-in. bore respectively, rifled upon the Armstrong plan with 44, 56, and 76 grooves respectively. The projectiles were lead-coated. The 20-pounder fired one round with 3 Ibs. 10 oz. charge ; 2 with 5 Ibs. charge; 3 with 3 Ibs. 10 oz. charge; 100 with 2 Ibs. (service) charge, and a projectile in- creased by the weight of 1 shot every 10 rounds, from 20 to 200 Ibs. ; and 30 rounds with 5 Ibs. charge, and projectiles increased by the weight of one shot every 3 rounds from 20 to 200 Ibs. During the first 100 rounds, three gas-rings were used. One of these was spoiled by the blowing out of the sliding-block at the 73d round, with a 140- Ib. projectile. The 40-pounder fired 7 "de- veloping" and " proof" rounds, and 100 rounds with projectiles increasing in weight from 40 to 400 Ibs. The 110-pounder fired 7 "devel- oping" and " proof" rounds, and 100 rounds with projectiles increasing in weight from 100 to 1000 Ibs. The 1000-lb. projectile was 7 in. in diameter, and 8 ft. 9^ in. long. (See Tables 19 to 21, pages 98 to 100.) The sliding-blocks of these guns worked with ease throughout BREECH-LOADING. 605 these experiments. A block was occasionally blown out under the enormous pressure, and the gas-checks were occasionally renewed, without delay. The guns are apparently as serviceable as ever. 77O. BBOADWELL. Another form of gas-check, patented in FIG. 350. Breech of Krupp 110-pounder. England by Mr. Broadwell, is shown by Fig. 353. As in Krupp's gun, the sliding-block is started out by the lever a, and a steel ring is placed in the end of the bore. But an undercut copper FIG. 351. Breech of Krupp 110-pounder, with sliding-block removed. ring is also placed in a recess in the sliding-block, and the two rings are forced together by the gases. 771. STOEM. The gas-check, and the means of fastening it, 600 ORDNANCE. used by Mr. Storm, of New York, are illustrated by Figs. 354 and 355. Substantially the same arrangement has been applied, with great success, to small arms, both here and in England. FIG. 352. Sliding-block of Krupp 110-pounder. The engravings are thus described in the patent specification : " The main object of this part of the invention is the applica- tion of the gas-check, or valve, which consists of a loose tubular lining, which fits into the barrel of the weapon, and covers the junction between the barrel proper and the breech-piece ; and FIG. 353. BroadwelPs breech-loader. being capable of an endway movement, by reason of the expan- sive force of the ignited powder, will completely seal the joint between the breech and barrel. * * * BREECH-LOADING. GO' " A is a barrel of the cannon, provided at its inner or rear end with a screw-thread, which takes into a hollow screw tapped in the breech-frame B. This hollow screw or ring carries the trun- nions, and forms the forward end of the breech-frame. On the under side of the trunnion ring two lugs are formed to receive a transverse axle a, which passes through a similar lug formed on a hinge-piece C, attached to the movable breech D. Keyed to this axle is a weighted lever &, which serves to counterbalance the breech, and thereby facilitates the working of the gun. The rear FiGS. 354 and 355. Storm's breech-loader. end of the breech-frame B is tapped to receive a quick screw E, which is operated by a winch handle F, and enters a hole bored in the rear end of the breech, for the purpose of securing it in position when the cannon has been charged. A recess is made in the breech-chamber to receive the gas-check or valve G, the front 608 ORDNANCE. end of which projects into the barrel. The vent c, for firing the cannon, is carried through the breech-frame to give access for priming, so that if by any chance it is attempted to fire the charge before the breech is brought "home," or to its proper position, the vent will be closed by the hole in the breech-frame not being in coincidence with that of the breech. To charge the cannon, withdraw the screw-bolt E, by means of the winch handle F, and let the breech fall into the dotted position, when the valve G will come away with it. In the breech-chamber, contracted by the insertion of the valve G, which forms a lining thereto, the cartridge is placed, and the shot or shell is inserted in the barrel of the cannon through the now open rear end; then, by means of the weighted lever 5, raise the breech into position, as shown at Fig. 2, and secure it there by the screw-bolt E. The cannon is then ready for firing. For adjusting the cannon to the proper angle for firing, the elevating screw, or analogous device, is provided in advance of the trunnions, instead of in rear thereof, as heretofore. 775J. " It will be understood that the barrel of the cannon may have a smooth bore, or be rifled, as thought most desirable, and that shots or shells of any suitable construction may be employed therewith. The part of the gas-check or valve G, which overlaps the rear end of the barrel, is, by preference, formed with a curved face, the curve being struck from the axis of the supporting hinge." 773. FRENCH. This is adapted from an American plan illus- trated by Figs. 356 and 357.* Six of these guns were fabricated at Boston for the British Government in 1855, but owing to the clumsiness with which the principle was carried out they have never been mounted for service. A screw is cut in the enlarged end of the bore at ~b. A corresponding screw is cut upon the breech-plug a. Three longitudinal grooves are then planed out of the screw cut in the bore, and similar grooves are planed across the threads of the breech-piece. In other words, the screw- threads are " stripped" at three places in the gun and at three * A plan similar to this was patented in the United States, by John P. Schenkl and Adolph S. Saroni, August 16, 1853. BREECH-LOADING. 609 places in the plug. The plug may then be slipped into the gun, the threads of the former entering the grooves of the latter. By turning the plug one-sixth of a revolution the sections of threads left on the plug enter those left in the gun, and hold the two together just as if they had been screwed in. Or the threads may form independent circular ridges instead of being helical, the object being to save the time necessary to screw in the plug, which would require 20 or 30 revolutions. The plug a turns in the collar and shell split and broke up into innumerable splinters, which caused great havoc. This experiment was continued with 32-pounders, 68-pounders, 8-in. and 10-in. hollow shot, the same year ; the f-in. iron being backed between the ribs with oak and fir planking of different thicknesses, with ribs on the inside similar to the Simoom' the iron, wood, ribs, and all, were of course easily torn away, and the effect of splinters, of both shot and iron, were very destructive. 797. 2 -inch Plates. " This was followed by experiments, also by the Navy, at Portsmouth, in 1854. Here there was a target; composed of 4^-in. best scrap wrought-iron plates backed with 4 inches of fir planking, the whole bolted by heavy iron screw-bolts to a strong timber frame- work, well braced and strutted. Ten 32-pounder shot from a 58-cwt. gun, charge 10 Ibs., at 360 yards, * "The Application of Iron to Defensive Works." K. E. Papers, 1862. 40 626 ORDNANCE. struck the plates ; a single shot indented 2 inches ; two in nearly the same spot, indented 2J inches, and slightly cracked a plate ; four shot cracked a plate in four places, and bulged it 3J inches ; all the shot broke up. Two 68-pounder shot, charge 16 Ibs., at 1250 yards, indented about 1^ inches, and cracked the plate, and were supposed to break up. Ten from same gun, charge 13 Ibs., at 400 yards, struck the plates indentation caused by one shot, 2^ inches ; each shot more or less cracked the plates, and several near the same spot injured them very much. Subsequently, 68-pounder shot, charge 16 Ibs., at 400 yards, nearly destroyed the target and backing. 798. " About the same time, plates of , , and -in. thick- nesses were fired at, and it was found that solid and hollow shot would pass through 1 and f-in. iron, without breaking; that hollow shot break up in passing through -in. iron, and that both solid and hollow break up in passing through fth iron." 799. Gcn.Totten' Experiments " From 1853 to 1855 Gen- eral Totten, of the United States Army, carried on some interest- ing experiments in some degree involving the question of iron defences. In his first target, containing six embrasures, a variety of materials was tried, namely, granite, hydraulic cement con- crete, asphaltic concrete, and lead concrete, arid brickwork. In one of these embrasures the throat was composed of wrought-iron, 8 in. thick, made up of sixteen |-in. thicknesses, set partly in cement concrete and partly in brickwork. In one lead and cement concrete was notched, and protected by wrought-iron plates 2 in. thick and 6 in. wide. And in one these two plans were combined with asphaltic cement. His second target contained three embrasures. One had its throat or jambs com- posed of wrought iron, 4 in. thick, 10 in. wide, made up of eight thicknesses of boiler-plates riveted (rivets countersunk and flush) together, backed by a small mass of tough cast iron. This embrasure was built of granite, and had shutters in two leaves of three thicknesses of -in. boiler plate. I believe there was thin sheet lead between the wrought and cast iron. Another embrasure in the second target was of similar construe- EXPERIMENTS AGAINST ARMOR. 627 .tion to the last, only in brickwork instead of granite; there were no shutters, but a projecting portion of brickwork was protected by -in. wrought plate. The last embrasure was of similar form to the other two, but of cement concrete ; it had the 8-in. wrought-iron throat used in the former target, and a projection covered by |-in. plate. The general result of the experiments was, so far as iron is concerned, that grape-shot passed through, or entirely carried away -in. boiler-plate, but that canister shot produced no injurious effects ; that shutters, l in. thick, of boiler-plate stopped grape-shot, but were bent by it, and were quite disabled by heavier shot; that the 2-in. offset plates of wrought iron did not stand against a 42-pounder ; that throat- plates of 4 in. wrought iron, in -in. thicknesses, backed by cast iron, being struck two or three times by a 68-pounder solid shot, were carried away, the cast-iron backing being cracked and broken ; and that 8-in. wrought gorge plates, in sixteen thick- nesses, were bent and finally torn from their fastenings by 42-lb. solid shot, and even were considerably injured when struck seve- ral times by a 24-pounder at 95 yards. The great advantage of a single mass of wrought iron over one composed of several thin- ner plates was noticed ; that the brittleness of cast iron unfits it for use as a means of directly resisting heavy shot ; and that a cast-iron block, protected by a 4-in. compound plate, was always broken up, splintered, and badly cracked. It is almost unneces- sary here to notice the performance of the other materials ; but it is interesting to remember that, next to wrought iron, lead con- crete proved the best material. It is of course less resisting and more costly than wrought iron, but it will not crack and splinter. Heavy shot at high velocities mould for themselves a symmetrical bed in which they are found crushed ; in fact, the effect is quite local, and even shells exploding in it produced no cracks." 8OO. Floating Batleric. In 1855 floating batteries, covered with 4^-in. plates, 3 ft. long x 20 in. wide, secured to the wooden hull by 1^-in. screw-bolts, received the fire of the Russian batte- ries at Kin burn. The following particulars are from Commander Dahlgren's Account of the action : " The French floating batte- 628 ORDNANCE. ries Devastation, Lave and Tonnante steamed in to make their first essay, anchoring some 600 or 700 yards off the S. E. bastion of Fort Kinburn. * * * The Russians could only reply with 81 cannon and mortars, and no guns of heavier calibre than 32- pounders, while many were lower. * * * This was the sole occa- sion in which the floating batteries had an opportunity of proving their endurance. * * * They were hulled repeatedly by shot ; one of them (the Devastation), it is said, 67 times, without any other effect on the stout iron plates than to dent them, at the most, li in. still there were 10 men killed and wounded in this battery by shot and shell which entered the ports." 801 . In March, 1856, the Messrs. Stevens made the following experiment at Hoboken. The target (vertical), 3 ft. 2 in. x 4 ft. 4 in. face was composed of four 1-in. plates, two -in. plates, one f-in. plate, and lastly two -in. plates, in all 6f inches of wrought iron. The bolts, 48 in number, were in 8 vertical and 6 horizon- tal rows. The target was set up against, but not fastened to, a mass of pine timber. A 125-lb. (10-in.) ball with 10 Ibs. of powder, range 24 feet, cracked the three first plates around the bolt holes, a disk being nearly broken out of the outer one. No other plates were cracked. The back was indented about three inches. 802. " In the middle of 1856,* Sir John Burgoyne collected what little had been done in the matter of applying iron to para- pets of batteries, both floating and on shore, and moved the Government to consider the important question of giving better cover to guns, and by the use of iron to reduce the external open- ings of embrasures. Several high authorities were consulted, and some good opinions given. From what had then been done, it appeared that 4-in. wrought iron on a ship's side was penetrated to a depth of 2 in., by a 68-lb. shot, at 400 yards; that 4 in. of wrought iron completely protected a ship's side against 68-pounders, at 1200 yards ; that they gave considerable protec- tion against the same gun, at 600 yards, and but little, at 400 yards ; that they gave considerable protection against 32-pound- * Captain Inglis's account continued. EXPERIMENTS AGAINST ARMOR. 629 ers solid, and 8-in. 56-lb. hollow shot, at 400 yards ; a 32- pounder shot penetrated only l or If in., and the hollow shot only one in. ; but three or four shot of the same kind striking near together will break up the plates. " From some experiments in France, iron plates, 3-94 in. in thickness, were found to resist about fourteen shots per square metre (lOf square feet, English) from a French 30-pounder (Eng- lish 32-4: Ibs.), at 300 metres distance ; and 5^-in. plates gave a resistance of eighteen shots per square metre." 8O3. Cat-lron Blocks.* "Many suggestions were made, and amongst them, that cast-iron blocks should be tried ; and in con- sequence, in 1857, experiments were carried on at Woolwich against large 8-ton cast-iron blocks, 8 feet by 2 feet, 2i feet thick, tongued and grooved together, and partially backed by heavy blocks of granite. They were first fired at with a 68-pounder, 95-cwt. gun, at 4:00 yards, charge 16 Ibs., solid cast-iron shot ; these shot made indentations of from 1-3 in. to 1-6 in., and cracked, displaced, and broke up the blocks very much. Some wronght-iron shot (the same gun) indented from 1-6 in. to 1-9 in., and broke off large fragments and scattered the iron in pieces of from 10 Ibs. to 80 Ibs. Subsequently a cast-iron block, 6 ft. x 4 ft. and 2 ft. thick, weighing 9 tons 13 cwt., was fired at with the same gun, at same range, with wrought and cast shot, by which it was cracked all through. Cast-iron shot broke * A correspondent of the London Engineer gives the following account of ex- periments against cast iron in Russia, 1863: "Another interesting experiment was tried with cast-iron armor-plates, proposed for forts, in blocks 4 ft. thick, 2 ft. high. This block was fired at with round-shot from 68-pounders, at 700 ft. distance. The first shot took off a mass of 100 Ibs. weight from the lower corner; the second shot struck low, and only carried away a few pounds; the third shot struck fair, and cracked the plate every way; the fourth and fifth shots hit fair, and shivered the whole mass. "The reason for trying cast iron was simply this it can be produced in Russia. At present armor-plates come from abroad. General Todtleben, who was present, suggested trying combined cast and wrought iron around the embrasure wrought iron, and between them filled up with cast iron; and targets are now being constructed of this description for the purpose of testing the principle. ' The result on cast iron alone where, as in this experiment, the block was 4 ft. thick was, that a few round shots, at point-blank distance, destroyed the mass." 630 ORDNANCE. up ; wrought-irori shot recoiled considerably, and were much flattened." 804. 4-Inch Iron. Steel.* " After this, in 1856, wrought plates, furnished by different makers, 4 in. thick, backed by 2 feet of woodwork, were fired at by 68-pounders, at Woolwich. The cast-iron shot, at 600 yards, indented from 1 in. to 2*3 and 3 in., and cracked and bent the plates ; wro light-iron shot, at 600 yards, indented from 2*2 to 2*8 in., and carried away pieces; cast-iron shot, at 400 yards, indented 2'2 in., and cracked the plates, drove in bolts, and shattered bulkhead ; wrought-iron shot, at 400 yards, indented 3 in., and went right through a plate without cracking it. This large bulkhead, weigh- ing more than 30 tons, was driven back by the blows it received, 3 or 4 feet. 805. "After this, in 1857, more wrought plates by different makers, 4 in. thick, and steel 2 in. thick, secured by bolts to 2 feet of oak, were fired at with 68-pounders, at 600 and 400 yards at Woolwich, the general result of which was that wrought- iron shot at 600 yards passed through, and cast-iron shot at 600 yards were resisted, but they crushed the iron, and by a repetition of blows would ultimately destroy the plates. At 400 yards, the plates were quite broken up by both cast and wrought shot. Mr. Begbie's 2-in. steel did not stand." 806. Firing Through Water. In December, 1857, Mr. Whitworth's 24-pounder howitzer, 4 and4rjin. bore ; twist, 1 turn in 40 inches ; charge, 2 Ibs. ; shell, flat headed, of 24 Ibs. weight, was fired through water at various angles, at a 4-in. (8-in. after the 3d round) oak butt. The gun was 15 feet above a horizontal * A correspondent of the London Engineer thus mentions late Russian experiments against steel armor. "The plates of Petin, Gaudet, and Co., the Thames Company, John Brown and Co., the Parkgate Company, have all been tried, with results similar to those obtained in England. One hammered steel armor-plate, 4| in. thick, was fired at by the ordinary 68-lb. naval gun, and the plate was hit in three places, on a line about the centre of the width, and at pretty equal distance. The penetration was not quite so deep as in the iron; but, on removing the plate from the target, it was found that the back of the .plate, behind where the shots struck, was broken into fragments, and the plate was cracked its whole length." EXPERIMENTS AGAINST ARMOR. 631 TABLE CXIII. PENETRATION OP WATER AND WOOD. WHITWORTH 24-PouNDER RIFLED HOWITZER. H. M. S. "Excellent," December 22, 1857. J |j ll d, c o Remarks. &4 ^ 9) * * _^^2 ft c. *0 g 5 s ? *H * T3 fe 1 ft Q "5 "ft H ll S | I < / ft. in. ft. in. ft. in. fl. I 7 o 4 2 2 21 7 21 4 in. fir and 3 in. oak, and grazed timber. 4 7 o 4 o 2 21 7 22 4 in. fir and 3 in. oak. 3 7 3 4 o 3 4 21 7 21 4 in. fir and 3 in. oak. Dropped in hold. 4 7 30 4 o c o 21 ... 22 Grazed angular side I in. deep. 5 7 30 4 o 3 6 21 4 21 Penetrated to rib and dropped in the mud. 6 7 3 4 o 4 o 21 3 22 Penetrated to rib. Side very angular. 8O7. omparioii of 6-Poimders and 32-Pounders. "In 1858,* the effect of 68-pounders and 32-pounders, at 100 yards, against iron plates, was compared at Portsmouth, when one 68-lb. shot was found to do as much damage to a plate and more to the woodwork frame of a ship than 5 32-pounders striking close together, and at 20 yards some 4-in. wrought plates on a ship's side were not penetrated by a 68-pounder cast- shot with full service charge ; but a wrought shot, of 72 Ibs. from * Captain Inglis's account continued. EXPERIMENTS AGAINST ARMOR. 633 TABLE CXV. PENETRATION OP WATER AND WOOD. WHITWORTH 24-PouNDER RIFLED HOWITZER. From Mooring Lighter at " Serpent" Brig, March 16, 1858. fe| |g | A No. of Round, I ft P 1 .u < W Height of wa above part st Shell entered- distant from i Penetration i wood. Remarks.* / ft. in. ft. in. ft. in. The first 8 shots were above water. 9 515 6 6 ... 28 Did not hit the vessel. 10 11 3 o 28 ... Hit sternpost, knocking off a piece 3 in. thick. u 3 9 28 i Fell into the mud. 12 3 3 28 i Grazed and fell into the mud. 13 M 7 3 28 i Buried in mud. H 4 15 M 3 3 15 $ Grazed and buried in mud. to 4 3 15 6 30 3 6 22 i Ditto ditto. 16 U 22 ' I* Grazed and buried 6 feet in mud. 17 6 o " i 6 18 4 Also passed through a rib, tearing off f ths of it. 18 6 30 3 o 22 ii Buried 4^ ft. in mud. 19 M 3 3 22 4i Lodged between 4-in. side and lining. 20 6 o " 2 6 18 4 Lodged in side. 21 5 3 M I 13 4 Knocked away part of bulkhead of mag- azine, glanced up knocking away 5 in. combing, and fell overboard 20 yards beyond. 22 5 45 2 16 2 Fell in mud. 2 3 5 3 i 8 13 I 3 Through side and a rib, and lodged in store-room. * Percussion fuzes were used in the shells, but did not burst ; the plugs having acted, but the fire being put out by the water. 634 ORDNANCE. same gun, did just penetrate them. Also, it was found, that hollow shot, red-hot shot, and shell, made little impression on 4-in. plates at either 200 or 400 yards ; that, at 200 yards, the effects were much increased. At 100 yards 2 or 3 hollow shot, red-hot shot, and shell, striking at same spot, would penetrate a 4-in. plate, but a single 32-pounder cast shot at that range would sink deep into a 4-in. plate, but not get through. At 20 yards, cast shot did very little more damage than at 100 yards. It was also important to observe that if a shot does get through iron it does far more damage than if it had only gone through timber. 808. Whitworth 6S-Pouiider 4-Inch Plates. " In the autumn of 1858, a Whitworth 68-pounder fired solid cast and wrought shot against 4-in. wrought plates on ship's side at Ports- mouth, at ranges from 350 and 450 yards. A cast shot, at 350 yards, dented a plate in., bulged it If in., cracked it, and started 12 bolts, and at 400 yards much the same. A wrought shot at 450 yards went right through 4-in. plate and 7-in. of oak in ship's side. After this the gun burst." The details of this ex- periment are given in Table 116. 809. 4-Inch Plate ; 6 and 32- Pounders. " In November, 1858,* the Erebus and Meteor floating batteries were fired at at Portsmouth. The former ship's side had a inside skin on iron ribs, outside this 5 or 6-in. oak plank, and 4-in. wrought plates outside all. The Meteor's side was made up of an inner planking of oak from 4 to 9 in. thick, then 10-in. oak timbers 4 in. apart, then 6-in. outside oak planking with wrought 4-in. plates outside all. 32 and 68-pounders at 400 yards did no serious damage in- board to the Meteor, but 68-pounders penetrated the Erebus, and did as much damage as a volley of grape-shot. The Meteor also resisted a wrought 68 shot at 400 yards, and sustained only trifling injury in-board at 300 yards. A 68-pounder shell, with weight of sand=to bursting charge, indented a plate f in., but did not crack it. 810. -Inch Plate; 68-Pounders. " In 1858, a large * Captain Inglis's account continued. EXPERIMENTS AGAINST ARMOR. 635 TABLE CXVI. WHITWORTH 68-Poum>ER AGAINST 4-lNCH PLATES. H. M. S. " EXCELLENT," OCT. 8, 1858. GUN. 68-Pounder Block; Diameter of Bore, 5 in. and 5^ in. j Rifling, I turn in loo inches. PROJECTILES. Weight, 68 Ibs. ; Cast Iron, 12-7 in. long; Wrought Iron, 11*7 in. long. Some of these were hardened. TARGET. Plates 13 ft. long x i ft. 9 in. high x 4 in. thick; Target, 13 x 10 ft., fastened to the side of the Alfred frigate. *G C I Projectile. 1 i 1 I B Eemarks. Ibs. yds. in. I Cast I. 10 350 i Hit obliquely; 12 bolts started out ^ to if- in. j a cracks, I across the plate 7^ ft. to R. of indent; woodwork on lower deck slightly shaken and a few treenails started ; shot broke up. 2 Wt. I. IO 35 ... D d not strike the plates. 3 Wt. I. 10 350 ... Shot jammed in loading ; i^ hours spent in clearing the gun. 4 Cast I. 10 400 j Hit obliquely at lower edge of a plate j 4 bolts started out ^ in. ; crack 8 in. R. of indent 7 in. long. 5 Wt. I. 12 45 ... Through plate and ship's side; 6-in. hole; pieces of plate (badly welded) through ship's side ; shot passed through 4-in. iron and 7-in. oak. 6 Cast I. 12 400 i* Hit end on ; 4 bolts started out $ in. ; 4 cracks, 2 across the plate 2 ft. I in. R. and 2 ft. 4 in. L. of indent; no injury in board; shot broke up. 7 Cast I. ... ... ... Gun burst cutting away fore and mainmasts ; greater part blown overboard. wrought plate 6 ft. x 6 ft. and 8 in. thick, weighing 5 tons, lean- ing back about 10, and supported by large fragments of cast iron used in some former experiments, these again backed with heavy blocks of granite, were fired at with 68-pounders, solid, cast, and wrought shot, at Woolwich, at 600 and 400 yards, charge, 16 Ibs. At 600 yards, a cast shot indented 1*25 in., cracked the plate slightly on its face, bulged it in with a wide crack behind, which was afterwards increased. At 400 yards, a cast shot indented 1*4 in., and extended the cracks very much. At 600 yards, a 636 ORDNANCE. wrought shot broke off large fragments, and in fact quite broke it up. The report adds that when this plate began to break up its destruction was as rapid as that of the cast blocks in 185 T. 811. a l-l mli Thorneyeroft Shield. "In 1859, Messrs. Thorneycroft, of Wolverhampton, proposed to Captain "Wrottesley the use of rolled iron tongued and grooved bars in horizontal lay- ers, as an inexpensive method of applying iron to resist heavy shot. The great advantage offered was that of producing a mass of wrought iron at about 15 per ton, whereas in other forms it had not been previously put together under thrice that cost. Sir John Burgoyne strongly advocated the principle, and a shield measuring 10 ft. x 4 ft. 6 in. high and 14 in. thick, with an embrasure opening in it, was tried at Portsmouth. On the first day's trial seven 68-pounders shot at 400 yards range, striking fairly, made a very trifling impression, except in those parts where large vertical bolts passing through the heart of the bars had weakened them. This iron mantelet showed such powers of resistance on this occasion, that subsequently it under- went further trial with a 68-pounder at 400 yards ; 6 cast-iron shot struck the target, were of course broken up, but indented 1 in. and cracked it slightly ; one of these shot on an old shot mark, carried away a piece of the target. 8 wrought-iron shot struck it, 1 chipped off a piece, 2 carried away parts of the top sill of port, 5 indented and cracked slightly. Greatest depth of indent, 2 inches. Altogether, except for an error in construction, the result was considered very favorable to rolled-iron bars in layers, and further trials hereafter described were soon determined upon. 812. Special Committee ; l|-Iiieli, 2-Inch, 21-Iiicli, 3-Inch Plates. " During 1859, a Special Committee carried on a series of experiments* on iron plates of various thickness of which the * Captain Dyer, R. A., says as to the experiments made by this Committee (" Re- marks on Iron Defences," R. A. Inst.), that "the result, arrived at, was, that a good wrought-iron plate 4| in. in thickness, backed with 18 in. of teak, is considered for all practical purposes proof against any ordnance not exceeding the 68-pounder or 100-pounder Armstrong, at a range of 400 yards. EXPERIMENTS AGAINST ARMOR. 637 following is ari outline: "They commenced upon plates respec- tively 1J, 2, 2-J, 3 in. in thickness, bolted to a timber target representing the side of a 50-gun frigate, of oak from 18 in. to 24 in. thick. A shell weighing 78 Ibs. when filled with sand, charge, 10 Ibs., thickened at the head, fired from one of Sir "W. Armstrong's guns at 400 yards, passed readily through the 1^ and 2-in. plates, and of 4 shells fired against 3-in. plates, 2 were resisted, although they injured the plate and timber a good deal, and 2 passed through the plates, but not through the timber. An 8-in. shell (68-pounder) 16 Ibs. charge, made a circular crack in a 2-J plate, but did not drive any of the plate into the timber. All these shells were of course broken. Puddled steel and cast- iron solid shot from Sir W. Armstrong's 80-pounder (11 Ibs. charge) passed through the 2^ and 3-in. plates and timber, the steel entire, the cast iron in fragments, doing much damage by splinters. 813. "Truty," 4-Inch Plate. " The < Trusty' was next fired at ; her side consisted of wrought 4-in. plates on 2 feet 1 in. solid oak. At 400 yards, 72 Ibs. cast flat-headed shot from Sir "W. Armstrong's 80-pounder gun, broke the plates but did not pierce ; shot broke up of course. The puddled steel shot broke in a large portion of a plate. A homogeneous iron fairly pene- trated both plate and timber. At 200 yards the cast-iron conical- headed shot 100 Ibs. did a good deal of injury but did not pene- " During these experiments it was found that although, except in rare cases, ships of this construction were impenetrable, still, that penetration was at last obtained coupled with most terrible destruction if struck several times with heavy projectiles near the same spot. The shot on impact is broken in pieces, and carried through with the fragments of the iron and wood ; the plate in this case not only not affording any protection, but materially increasing the destructive effect of the shot ; on one occasion the number of pieces produced by a single shot were carefully collected, and it was found that there were over 700 pieces of wood and iron each of sufficient size to be formidable. The possibility of such destructive and alarming effects have led many to question the advantages of iron defences ; but I think few except those whose sympathies are wedded to the romantic notion of ' the wooden walls of Eng- land,' would hesitate to prefer defence capable of resisting all missiles under ordinary circumstances, defective only in the improbable event of several shot striking the same spot, to being exposed to the fire of Armstrong 100-pounder shell with 8| Ibs. of power, or Martin's liquid iron shell." 638 ORDNANCE. trate. A homogeneous iron 78-lb. shot punched a hole through plate and penetrated 10 in. into the timber, and a homogeneous shot of 100 Ibs. at a lower velocity, did not punch a hole, but made a large fracture ; oblique shots at an angle of 50 to the a 373. The floating battery Trusty. side of the vessel, caused less injury than direct shots. The bolts holding the Trusty's plates rarely yielded except when directly hit. 814. I Bin h Plates. After this the same Committee fired at some 4 rolled plates from Messrs. Palmer's and some 2-in. plates from the Mersey Company, bolted to a section of a 50-gun frigate, with homogenous iron bolts double nutted. The 2-in. plates could not resist Sir "W. Armstrong's 80-pounder shell at 400 ; the shell broke up, but always passed through the plate. A 68-pounder shell at same range, 16 Ibs! charge, broke the 2-in. plate, but did not penetrate deep into timber. The 4-J plates had EXPERIMENTS AGAINST ARMOR. 639 a hole punched in them by a homogeneous flat-headed shot, and the plate was forced 3 in. into timber, and several shot striking together, some of the plate was driven in 20 in. Altogether these 4J-in. plates were considered to stand well. 815. "Some experiments were also about the same time carried on at Portsmouth, tending to show that three 68-lb. shot, striking close to the same point, will, at 200 yards, break up and drive in 4rJ-in. wrought-iron plates attached to a timber ship's side. This Committee came to the conclusion that although thin wrought plates will break up cast-iron shell, little advantage will be gained by the use of iron, unless it be strong enough to resist both the fragments of shell and of cast-iron shot ; that ships with 4-J in. of rolled plates were invulnerable by any projectile then in use, and that plates should be strongly backed and secured by strong wrought-iron bolts with double nuts. 816. Jones's Inclined Target. "In August, 1860, Jones's (miscalled) angular butt was tried at Portsmouth. It consisted of a series of ribs of i-in. iron plates, 21 in. deep, spaced 14 in. apart, connected together at outside and top and bottom with -J-in. iron pieces, screwed and nutted to the ribs, outside this was laid 13J in. of stout fir planking, and outside this the armor-plates, the whole structure measuring 39 in. through, and being placed at an angle of 52 with the perpendicular. The armor-plates were 4^-in. and 3-J-in. steel, and 4rJ~in. wrought- iron from the Mersey Works, and 4J-in. of Derbyshire iron. The butt, with a strong and solid foundation, and well supported by stanchions, was placed on the upper deck of an old vessel and fired at by a 68-pounder solid cast-iron shot, 16 Ibs. charge, range 200 yards. The result of 35 rounds was reported to be that the penetration was less than half that on perpendicular plates, and that the effect on the woodwork backing w^as very slight, com- pared with that when the plates are on a ship's side. The Derby- shire wrought iron was extremely brittle ; that by Mersey Com- pany was far better; the steel plates useless. One 4^ Mersey wrought-iron plate, 7 ft. x 3 ft., took 17 blows in an area of 13 square feet before any part of it was removed, and then, 640 ORDNANCE. TABLE CXYII. EXPERIMENTS AGAINST JONES'S INCLINED TARGET. AUG. 21, 1861. The numbers in brackets (Fig. 374) show the numbers of these rounds. GUN. Armstrong loo-pdr. of 81 cwt. SHOT. Elongated solid cast iron, with spherical head. Charge, I4lbs. RANGE 200 yards. TARGET. The plates Nos. I and 2 were 4^ in. ; Nos. 3 and 4 were 5^ in. thick, and each one 7x3 feet, showing a vertical height of 4^ ft. They were secured to I ft. square balks of pine by screw-bolts with conical countersunk heads, i$-in. bolts. These plates rested on plates 15 in. wide by if- in. thick let into the backing of timber. Angle of in- clination, 50 53' from the perpendicular. No. of Round. Diameter of Indent. Depth of Indent. Remarks. in. in. I 6 I No fracture j 2 bolts broken, and 3 shaken. 2 ... ... Missed. 4 ... ... Struck wood framing. 5 6 I Plate slightly bulged and started up f in. j crack, 7 in. long. 6 6 t 3 bolts broken out. 7 6 A Plate bulged \ in. 8 6 I 9 ... Missed. 10 ... Ii Bolt driven in \\ in. ii 6 1* 4 cracks 5 to 8 in. long. 12 6 1 Crack 1 1 in. long x I in. deep to edge of plate. 13 6 i H 6 Ii , S ... ... Broke a piece of plate out 8 x 6 in. ; 5 shot now in space 12 x 21 in. ; upper edge of No. 2 plate started up I to 2 in. 16 ... ... Missed. 17 6 f 18 6 H Crack 7 in. long, and 4 small cracks. 9 ... ... Missed. 20 6 i 21 6 i 22 ... ... Six shot now in a space 12 x 21 in. ; breaking out 2 ft. x I ft. 4 in. of No. 2 plate, and bulging framework to a depth of 4 in. ; pul- verizing the wood. All the shot appeared to "break, upon striking, into numerous fragments, which generally fell be- tween 500 and 1500 yards beyond. .EXPERIMENTS AGAINST ARMOR. 641 41 642 ORDNANCE. TABLE CXVIII. EXPERIMENTS AGAINST JONES'S TARGET PLACED VERTICALLY. SEPT. 18, 1861. The plates had not been disturbed since the experiments recorded in the foregoing table. The target was merely raised to a vertical position and secured by heavy balks of timber. GUN. Armstrong ioo-Pounderj Charge, 14 Ibs.j Shot, cast iron, conical headed ; Range, 200 yards. The numbers in diamonds (Fig. 374) show the nnmbers of these rounds. No. of .Round. Diam. of Indent. Depth of Indent Remarks. in. in. I 6 i-f and if 4 securing bolts broken and a number of bolts started. 2 ... ... Securing bolts all broken 5 plate fell to the deck. 3 6 i Shot broke up j bulge, -f in. ; crack, 8 in. long j upper started from backing if in. j plate badly welded. edge 4 7 ii Crack 14 in. long, and 2 short cracks. 5 7 if a bolts broken and several started. 6 ... ... Drove fragment of plate 18 x 20 in. into backing 12 in 7 7 ii 2 bolts broken and more started. 8 6 H i small crack ; bulge, i in. ; outer edge started 2 to from backing. 3 in- 9 6 i 10 Drove piece of plate 17 x 24 in. into backing 10 in. ; I 14 in. long. crack ii ... ... Drove piece of plate 12x9 into backing 8 in. 12 ... ... Drove piece of plate 17x7 into backing 7 in. j opened former cracks 5 plate ready to fall, and secured by a rope. 13 Plate detached, and fell overboard. even, the iron was not penetrated nor the woodwork much injured." The official account of these experiments is given in Tables 117 and 118. 817. Comparison of Elongated and Spherical Projec- tiles.* " A general comparison was also made about this time * Captain Inglis's account continued. EXPERIMENTS AGAINST ARMOR. 643 between the effects of elongated and spherical shot upon iron plates at 200 yards, which went to show that an elongated shot pene- trated more than a spherical one, striking with the same momen- tum, but the blow of the elongated was less spread and the smashing effect less. Also, that a flat-headed elongated shot penetrated deeper than a spherical, because the latter spreads out on striking, and thus has a larger surface opposed, while the elongated shot punches a hole out for itself. 818. Thorneycroft lO-Inch Shield.* " In the autumn of * Captain Dyer, in his paper before quoted (" Remarks on Iron Defences"), thus refers to the history and objects of the " Thorney croft" bars: "As it was considered desirable that some further experiments should be carried on to determine the best quality of iron for defensive purposes, a committee was formed at the beginning of last year to ascertain whether it might not be possible, by some improvement in the manufacture of armor-plates, to lessen the thickness of 4 in., and also to devise some mode of attachment that would obviate the necessity of bolt-holes, and the tongue and groove. The question of employing iron for land defences was also submitted for their consideration, as the Defence Commission had some idea of employing iron very largely in constructing the works at Spithead, Portland, &c. This idea gave rise to the experiments that were carried on with the Thorneycroft bars. As greater resist- ance to shot was obtained by these bars than by any other means, and as they are now being employed in the defences of Antwerp, the following history of their origin may be interesting : " In the early stage of the inquiry relative to iron defences, it was found exceed- ingly difficult and expensive to obtain large forgings sufficiently sound to resist shot, until Mr. Hartley, of the Shrubbery Iron Works, "VYolverhampton, proposed to try the effect of rolled bars of iron tongued and grooved together ; this proposal was agreed to, and Mr. Hartley was desired to prepare a target with as little outlay as possible ; he therefore adapted a pair of rolls he had in stock, and produced bars with a sec- tional area of 15 x 5 in., the size of the rolls, or rather the chance selection of the pair used, determined the size of the first bars, which obtained the name of Thorneycroft's bars, simply because they were made at the Shrubbery Iron "Works, which were for- merly more generally known by the name of Thorneycroft's. A target formed of these bars, secured together (in addition to the tongue and groove) by a bolt passing through them, was found to offer such resistance to shot as to warrant the belief that if reduced to 10x4in., the defence would still be found sufficient. An embrasure was therefore constructed of bars 10 x 4f in., having several feet of masonry above them ; on this occasion, the bolt used in the former experiment to secure the bars together was dispensed with, as it was considered that sufficient solidity would be obtained by the weight of the masonry above. This embrasure stood the most severe tests without showing any signs of weakness ; salvos from 68, 80, 40, and 32-pounder guns were fired against it, apparently without damaging the structure, and it was, with reason, thought that an embrasure of this construction was invulnerable. Indeed, so confident were all in this method of applying iron for defence, that it was proposed still further to reduce the sectional area of the bars, and to substitute wrought-iron supports for the masonry. Two embrasures were therefore constructed for experi- 644 ORDNANCE. 1860, a further trial was made at Shoeburyness, of the Thorney- croft principle, on a shield 12 ft. x 5 ft. 4 in., with an embrasure opening of 23 in. x 39 in., composed of rolled bars 10 in. wide and 4 in. thick, with tongues and grooves. There were thus 6 long bars and 10 short bars ; the shield was applied to the front of a masonry casemate, and a 68-pounder gun was mounted in the casemate, on a traversing platform. It will thus be seen that this shield was but 10 in. thick, or 4 in. less than that tried at Portsmouth, and before described. The principal points in which it differed from the Portsmouth shield was, that instead of the several bars being held down by bolts passing through them, they were in this case clamped together by strong vertical tie-bolts at their back at each end, and these passed through bonding-irons at the top and bottom ; the whole was well bedded in the masonry, and tied through the whole thickness of the parapet by strong tie- rods ; the shield was, moreover, backed by masonry over its whole surface. This shield was first fired at with grape and segment ment; one of bars 10x4$- in., supported by wrought-iron uprights 2 ft. apart, and every fourth bar secured by a dovetail at the back to the upright. The other embra- sure was composed of bars 8 x 3f in., supported at the ends by masonry, and in the centre by wrought-iron uprights 2-J- ft. apart, similar to the other. At this experi- ment, Sir "W. Armstrong's 120-pounder shunt gun was used, and the effect of this formidable piece of ordnance against the embrasures was such as to put an end at once to all idea of their impenetrability and the strength anticipated by the wrought- iron supports. It was found that the tongue on the bars was readily stripped off, and the uprights broken in the vicinity of the blow, leaving, as it were, each bar singly to resist the impact of the shot without deriving any support from the others. In the bars used at this experiment sufficient care had not been taken in the ' piling' to obtain the greatest amount of strength ; but independently of this defect in manufac- ture, the very small comparative resistance offered to the shot caused all idea of using these bars to be most reluctantly abandoned. Bars of this description possess many advantages over wrought-iron plates, if it were possible to hold them- securely together, and make each one derive its proper share of support from the others. The advantages alluded to are as follows : " 1. The rapidity with which they can be manufactured. " 2. The facility of transporting them from the forge to the work. "3. The great thickness of metal obtained sound, at a comparatively small cost per ton, for it must be remembered that the price per ton of wrought iron increases very rapidly in proportion to the weight. For example: while 19 per ton was paid for Thorneycroft's bars, with a prospect of a very considerable reduction, the armor- plates were costing from 32 to 40 per ton, and the stern-port of the ' Warrior' cost no less than 150 per ton." EXPERIMENTS AGAINST ARMOR. 645 Armstrong shell, at 400 and 600 yards, from 68-pounder, 32- pounder, and a 25-pounder Armstrong gun, and, from the dimin- ished size of the embrasure, the effect upon the inside of the casemate was favorable. After this, a number of rounds (about 21), with wrought and cast shot, were fired from 68-pounder, and 80-pounder, and 40-pounder Armstrong guns, at 600 yards, and without any serious injury. in. in. The 68-pounder indented about l^- to l-J- " 8o-pounder " I " 4o-pounder " " " grape " The masonry of the parapet was struck several times and fearfully injured." 819. lO-Inch Thorneycroft Shield without Backing. " After this, another experiment was made upon the same shield, without masonry backing, the masonry only giving it sup- port at its two ends. In this trial it received 29 blows from 68- pounder, and 80-pounder, and 40-pounder, at 600 yards, with wrought and cast shot, and stood very nearly as well as with the stone backing. It will thus be seen that the shield received 50 shots in all. One bar had a piece knocked out of it ; one or two slid laterally a few inches ; a few had cracks in them ; but alto- gether the shield was but little injured. ~No indentation exceeded 14 inch."* 8SO. Iron Embrasure Flaring Cheeks. "Together with the trial of this 10-inch Thorneycroft embrasure, a trial of another wrought-iron embrasure of special construction was made. This consisted of four massive pieces, two cheeks or side-pieces about 8 inches thick, set splayed, to allow a lateral traverse of 60, with a sill and head-piece 4 inches thick ; the whole was very firmly bolted and dovetailed together, and proved very strong ; but the defect of * " EFFECT OF SOUND. A short time after this, an opinion gained ground that the effect of the sound arising from heavy guns, fired out of an iron embrasure of this con- struction, would be an obstacle to its use ; and, to test this, a number of shots were fired from a 68-pounder, at every possible degree of lateral range, and no incon- venience whatever was felt by any person in the casemate." Captain Inglis. 646 ORDNANCE. the flaring cheeks was so apparent, in comparison with the small opening of the Thorneycroft embrasure, and the effect of the splinters and grape let in by these sloping cheeks so destructive upon the interior of the casemate, that the principle, although possessing some advantage as to strength, was soon given up. It is right, perhaps, that I should here mention that, on a subsequent occasion, the 10-inch Thorneycroft shield (which I have been describing as about proof against an 80-lb. shot) was found to be unequal to a blow from a 120-lb. shot thrown from Sir W. Arm- stron's shunt muzzle-loading gun. 831. Special Iron Committee, 1861. " Early in 1861, the special committee on iron was appointed, and during- the whole of the past year (1861) they have been fully occupied with a vast number of very important investigations. The more important and immediate and difficult object of inquiry of this committee, has been that of giving the most effective armor to our navy ; but the question of iron, as used for defence generally, has also occu- pied much of their attention, and the greater part of their experi- ments are as useful and instructive to the designers of fortification as to naval architects. 829. Thorneycroft lO-Iiicli and S-Inch Shields. " The 10-in. Thorneycroft shield, fired at by the Ordnance Iron Committee, having given great promise of success, and the principle appear- ing to give greater strength for the same money than by any other plan, it was determined to prosecute the inquiry further, and to erect two new shields.* The 10-in. shield was made on the * Captain Inglis says, in the same paper: "I think that a false step was taken in fixing the thickness of these two shields. When the original Portsmouth 14-inch shield had been tried, and, except for a certain defect in construction, found very good, instead of cautiously taking off little by little, so as to find a safe minimum, 4 in. in thickness, or 28 per cent., was taken off at one step, just at the time when projectiles were getting larger and flying faster, and a 10-in. shield tried at Shoebury. This proved, as I have said, equal to a certain gun, but quite unequal to resist the heavier projectiles coming into the service. "Instead, therefore, of putting on some strength, such as making up 12 inches in thickness, another 10-in. shield of much larger dimensions, and under considerably less advantageous circumstances, and of very questionable and ill-contrived construc- tion, was brought out ; and, to make matters worse, another shield of only 8 inches EXPERIMENTS AGAINST ARMOR. 647 / independent principle that is to say, it was to be self-supporting, without any aid from the rest of the fort, or other work of which it might form an embrasure. It presented a front of 12 ft. x 8 ft., with an opening or port for gun. It consisted of bars in section, 10 in. x 4-J in., tongued and grooved as before, but five of the bars, viz., 1st, 8th, 12th, 19th, and 21st, had dovetails on the whole length of their back, on which upright backing pieces fitted, which were intended to bind the mass from top to bottom ; the shield was supported at the back by massive rolled-iron struts footed down into sill-pieces of the same material. The 8-in. shield was composed of bars 8 in. x 3f in., with similar backing pieces, but supported at either end by masonry piers to which it was bolted. On the first day's firing at the 10-in. shield, the backing pieces gave way at the dovetails, and the mass not being tied together, the bars got displaced and broken, and ultimately, the whole shield being driven off its solid bed, it fell over and buried its face in the sand. On the second day, strong vertical iron shackles had been prepared in order, as a temporary measure, to supply the place of the backing pieces that had failed ; these made the shield offer considerably greater resistance, but when they ultimately gave way, the shield could not stand against the 120 or 1 00-pounder guns. The 8-in. shield could not even stand two 68-pounder shot, striking near the same spot, and the 100-pounder destroyed the target ; shackles, as before, were afterwards added, but, although they had some effect, the shield was quite unequal to the gun brought against it." Table 119 is the official report of the firing against these targets. Figs. 375 and 376 represent, respectively, the front and end of the 8-in. target, and Fig. 377 is a section of the 8-in. bar. RESULTS. THORNEYCROFT lO-I^cn TARGET. The 2d shot (Table 119) hit the right face just at the mouth of the embrasure on the 1th bar above the sill ; made an indent 7 in. in diameter. Three was ordered. The trial of these two against such blows as the 100-pounder service and 120-lb. shunt gun can give, at 400 yards, led to what might have been easily fore- seen, and the two targets completely broke down." 648 ORDNANCE. of the bars driven back 3 in., two more bars 2 in. The tongues of the bars where struck sheared off. 3. Passed through the embrasure. 4. Struck the lower bar on its lower edge ; scooped out a hemi- FlG. 375. FIG. 376. FIG. 377. Thorneycroft 8-in. target. spherical piece 2J in. in depth, 7 in. in diameter ; tore away some of the wooden foundation. 5. Struck 20 in. to the left of the last round. Exactly the same effect. 6. Hit the left top of the target on the 7th and 8th bar from the top ; diameter of indent, 9 in. ; depth, l in. The back of the 8th bar which, owing to the dovetail on the back was 12-J- in. thick- ness, was cracked. The bars did not appear to be displaced. 7. Through the embrasure. 8. To the right and 13 in. from the mouth of the embrasure EXPERIMENTS AGAINST ARMOR. 649 TABLE CXIX. EXPERIMENTS AGAINST THE THORNEYCROFT 8-lNCH AND 10-INCH TARGETS. JUNE 6, 1861. The 1st. target was formed of Thorneycroft bars, secured by dovetails to the iron up- rights j the dovetails were rolled on the back of the ist, 8th, 12, I9th, and 2ist bars. The bars were 10 in. by 4 in., and 12 ft. long j the iron uprights were 2^- ft. apart. The 2d target was formed of similar bars, 8 in. by 3^ in., supported in a similar man- ner with iron uprights, the end ones being supported by masonry. Nos. 14-20 give the results of experiments against the Thorneycroft lo-in. target. 1 No. of Round. Nature of Ordnance. Charge, Ibs. Weight of Projectile, Ibs. Nature of Projectile. Range, yds. I j 2 68-pdr 16 661 Cast-iron round shot. 4.00 10 95 cwt. vv/j- T 3 M * " " M II ... 4 ii II 5 M " " " M ... 6 II M " ... 7 II ii M M ... 8 II M ... 9 loo-pdr. Armstrong .4 no Cast-iron solid shot, hemispherical head. 4OO 30' 6' R 10 " 11 M ii 38' ... ii M H ii 46' ... * 12 M " " " M M ... 17 I2o-pdr.. 18 126 Cast-iron solid shot, 4.OO 7 7' J shunt gun, muzzle- hemispherical head. *r w JO loader. 68-pdr 16 661 Cast solid. 4.OO -1. 15 T T M 16 ii ... 17 loo-pdr 14 I IO Cast solid. 4.6' 6' R / 18 "r II it T u '9 ii II 6' R 20 l2O-pdr -.. . .. 18 126 Cast solid. M || 650 ORDNANCE. TABLE CXIX. (CONTINUED.) The experiments continued against the Independent Shield of Thorneycroft bars, lO-in. by 4-in., and against the Embrasure formed of Thorneycroft bars, 8 in. by 3f in., were resumed June 13, 1861. Range, 400 yards$ cast-iron solid shot. Both the bars were secured by strong iron braces, and strongly supported by Umber beams, but no backing was used. Nos. 27-30 give the results of experiments against the 8-in. target. No. of Round. Nature of Ordnance. 1 of I 6 Weight of Shot, in Ibs. Elevation. j 21 zoo-pdr 14 I IO 4.7' i r R 22 14 I2?4- AO' 2' L 21 I2O-pdr . . . . 18 I2C4 c' R *3 24 loo-pdr 14 I IOi yvr 4.7/ :> JN - r' R C 14- I2Ci 4.2' :> ^ 2 r L "6 I 2o-pdr 18 I2C-V c ' R 27 zoo-pdr . .. I IO J* 5 rv c ' R 28 I2o-pdr breech-loading shunt gun 14 I 25^ A->/ 3 JX 2' R 14. I2C-J- 4.2' 2 ' R 2 9 I loo-odr I IO 2' R C i 2O-odr I2Cl -' R i2O-pdr ... ll 1 *:>2 I2c4 ll' 3 rs - j' L 30 \ \ loo-pdr 14 >w I IO J 1 4.7' j * c' R 68 odr o< cwt 16 67 ;> * "2" on the 13th and 14th bars ; diameter of indent, 9 in.; depth, 1.64 inch. 9. Through the embrasure. 10. Hit the foot of the second upright below the bars ; broke away 3 feet of the bar, tore away the part that formed the dove- tail between 19th and 21st bars, and drove the top of the target 6 in. forward. EXPERIMENTS AGAINST ARMOR. 651 11. Struck the 5th bar from the top; diameter of indent 8J in., depth 1*68 in. ; cracked the bar. 12. Hit the 10th bar from the top ; opened a crack right through the bar one inch wide. The left upright was cracked right through at the second dovetail from the top. The tongue of the bar where struck was sheared off for several inches. Indent, 2-12 in. 13. Hit the 3d bar from the top ; broke away 2 ft. 9 in. of the bar, and drove it ten yards to the rear of the target ; opened the three top bars 1^- in. each, stripped off the top part of the first dovetail on the second upright ; opened the crack on the first up- right 2J in. wide. Indent, 2*20 in. The target fell on its face. THORNEYCROFT 8-lNce TARGET. 14. Hit on the 3d and 4th bar below the sill of the embrasure ; drove a piece 7-J- by 4J by 2 in. from the back of the 3d bar ; diameter of indent on the face, 9 in. ; depth, 2 in. 15. Hit on the left of the embrasure on 17th, 18th, and 19th bars ; made an indent 9 in. in diameter, 1^ in. deep, and cracked the bar. 16. Hit almost exactly on the same spot as No. 2, made a crack across all three of the bars 2 in. wide ; the bars were driven 2f in. into the mouth of the embrasure. The masonry was much shaken. 17. Hit just over one of the iron upright supports, which it drove away, breaking it into three pieces and tearing away the slots made to receive the dovetails on the back of the bars ; cracked the bar where it struck ; crack, 2 in. wide. Indent, 2*8 in. 18. Drove a piece of the bar, 80 Ibs. in weight, thirty yards to the rear of the target ; hit just below on the next bar to No. 4 ; opened a crack 8 in. wide through both bars ; drove the ends of the bars 5-J in. across the mouth of embrasure ; knocked down the four top bars and cracked the masonry. Indent, 3.1 in. 19. Hit the bar which formed the top of the mouth of the em- brasure at its extreme end, just over the wood backing, which it crushed in, made a small indent, and brought down six more bars. 652 ORDNANCE. THORNEYCROFT 10-INCH TARGET. The 8-in. target was now so destroyed that the firing was discontinued, and the 120-pounder shunt gun was laid on the old 10-in. Thorneycroft embrasure. 20. Hit to the right and below the mouth of the embrasure ; cracked three bars through in five places, opened the bars \\ in. ; the bars were much bulged and distorted in rear. Indent, 3 '3 in. 21. Hit the top bar of the mouth of the embrasure, and passed through, scooping out a very small piece. 22. Breech-loading shunt gun. Hit on the 7th and 8th bars ; depth of the indent, 1/65 in. ; diameter of indent, 9^-in. The bar slightly bent behind.: the tongue of the 6th bar sheared. The bars were separated \ in. in rear. 23. The muzzle-loading shunt gun. Hit on the 18th and 19th bars ; depth of indent, 1*9 in. No crack or bulge in rear ; the bars did not separate ; the upper dovetail on the left upright started iin. 24. Hit on the 18th and 19th bars ; depth of indent, 1-3 in. No bulge behind, damage being slight indeed in rear. 25. Hit on the 10th bar ; opened a crack 1 in. wide, broke off 13 in. of the bar and drove the bar 3 in. to the rear; sheared off the tongue. Struck over the 3d upright from the left ; knocked it off, tearing off the dovetails, broke the upright into two pieces ; opened the bars, bulged them 3 in. to the rear, cracked the 13th bar length- ways. 26. Struck over the left brace which was If in. in thickness ; cut it in two ; started the dovetail at the back of the left upright to 1| in. ; broke the upright ; cracked the bar across the back. THORNEYCROFT 8-lNCH TARGET. 27. Hit on the 6th and 7th bars ; drove them 2 in. to the rear, cracked them through and drove away the two uprights ; broke one into two pieces ; tore away the dovetails from each. 28. Hit on right wood support; passed through 6 in. of wood, indented iron 1*75 in. ; broke iron upright in rear in two places. 29. Tore away 4 feet of 4 bars ; sheared off tongues ; made a hole 4 ft. x 2^ ft. x 1| ft. beside embrasure ; drove several EXPERIMENTS AGAINST ARMOR. 653 pieces to rear. These 2 shots hit at the same time and struck near together. 30. These 4 guns were fired together; the 68-pounder passed through embrasure, and the 100-pounder struck the masonry. The 7th and 8th bars cracked through ; broke 6th, 8th, and 9th bars across in two places, and bulged them all inwards. The two shots that struck the embrasure were 5^ feet apart. 823. Different Qualftie of Iron and Steel.* " At the commencement of their proceedings the Iron Committee, besides consulting all practical and scientific men of experience in the manufacture of iron in this and in other countries, invited all the principal manufacturers to send in plates for experiment, f The plates were tried at Shoebury, fixed vertically without backing against strong timber frames. " Plates of homogeneous iron, of hammered and rolled iron of various qualities and make, steel, and steel and iron combined, and even copper have been tried. The plates of more than twelve different firms underwent trial and test of every possible descrip- * Captain Inglis's account continued. f Captain Dyer remarks in the paper before quoted : " The Committee appointed at the beginning of last year to continue the inquiry on the subject of iron defences, ob- tained the opinion of most of the principal iron manufacturers in the country as to the best quality and manufacture of iron to resist shot. The great diversity of opinion among so many practical men could only be accounted for by the fact that none of these gentlemen had ever had an opportunity of witnessing the effect of a shot on an iron plate, and this in some measure explains the very small progress that had, up to a recent period, been made in their manufacture. In consequence, plates of various qualities and manufactures were ordered for experiment, and the makers were re- quested either to be present themselves at the experiment, or to send some one in whom they placed confidence. They all most gladly availed themselves of this per- mission, and at the conclusion of the experiment they expressed themselves confident of being able to overcome all difficulties of manufacture, and of producing plates capable of resisting shot. Practical knowledge of great value was by this means afforded to those manufacturers who proposed to devote themselves to this branch of the iron trade ; and a spirit of emulation raised among the different iron-masters which cannot fail to have a most beneficial effect in bringing the question (as far as qualities and manufacture are concerned) to a satisfactory solution. " The advantage of having allowed the iron manufacturers to be present at the different experiments is already becoming apparent in the improvement of the plates supplied for trial; and the time is not far distant when the more general use of mechanical means, to move the large masses while being forged, will reduce the price per ton to more reasonable limits." 654 ORDNANCE. tion, from the very rough and ready and most unerring one of artillery practice, to the delicate and less conclusive test of the chemical analysis, and all the laborious mechanical tests and ex- amination as to specific gravity, tensile strength, resistance to compression, punching, shearing, torsion, &c. " A breech-loading wall piece, throwing a 5^-oz. ball, with initial velocity of about 1100 feet, was used upon plates up to one in. thick, at range 25 yards ; roughly speaking, a steel, lead-coat- ed, cylindrical flat- headed bullet punched a clean hole through the -in. rolled, hammered, or homogeneous plates, but did not always get through f-in. plates, and stuck in an inch plate, making a hole about J in. deep. " A 6-pounder Armstrong gun, throwing solid cylindrical cast- iron shot, with hemispherical head, at 1125 in velocity, range, 50 yards, did not get through 1-J-in. plates; a 12-pounder Armstrong, throwing cast-iron shot, in velocity 1150, at 100 yards, did not get through 2-in. plates ; and a 25-pounder Arm- strong cast-iron shot, at 100 yards, did not get through 2^-in. plates ; a 40-pounder Armstrong, at 100, did not get through a 3-in. plate. " The wall piece, at 25 yards, did not get through 3-in. copper. The 6-pounder Armstrong, did not get through 3-in. copper, but the 12-pounder Armstrong did." 8S4. Armor on Brickwork. " In May, 1861, a very interesting experiment was instituted to ascertain what protection would be afforded to brickwork by iron plates of 2-in., 2^-in., 3-in. and 3^-in. thicknesses. The plates were of rolled iron 2 ft. 6 in. wide, and 4 ft. 6 in. arid 5 ft. 6 in. long. Each plate was secured by six 2-in. bolts, with countersunk heads; an existing wall about 8 feet thick was used for the trial, and its face was first taken down to a depth of 4 feet ; at that depth rolled iron bars were placed vertically in the work (the common railway rail was used for cheapness and expedition), their lower ends being firmly driven down into the foundations, their upper ends held back by a horizontal bar, which was secured at intervals of about two feet bv bolts to the rear of the work. The bolts were EXPERIMENTS AGAINST ARMOR. 655 bolted to the vertical bars and secured by double nuts, and the brickwork built up solid in cement around them. * * * The result of this experiment may be set down in a few words viz. : that a brick wall covered by 3^ in. of iron in this manner would be quite proof against the battering guns at present in the service, but that if it has to resist guns about equal to our 100-pounders, it should be covered with about 5 in. of ar- mor, and that the mode of securing in this experiment was satis- factory." The following is the official account of these experiments : MASONRY PROTECTED BY IRON, MAY OTH, 1861. The object of the experiment was to ascertain what protection would be afforded to masonry by iron plates, 2, 2i, 3, and 3i in. in thickness. The experiment was commenced by firing a 12-pounder Arm- strong cast-iron solid shot at a range of 600 yards. The projectile did not penetrate any of the plates nor cause any damage to the brickwork. The 25-pounder land service Armstrong gun was next used, with cast-iron solid shot, at the same range. The projectile from the gun penetrated the 2-in. plates, but caused little damage to the other plates, and none to the masonry behind. The 40-pounder Armstrong was next used, with cast-iron solid shot. The projectile penetrated all the plates, with the exception of the 3-in. plate, on which it had hardly any effect at all ; even when it penetrated the plates it did but very little damage to the masonry behind. A 68-pounder 95-cwt. gun was next used, with a charge of 16 Ibs. and cast-iron solid shot, at a range of 500 yards. The shot pene- trated all the plates and damaged them a great deal ; still the plates were not displaced, neither were the bolts started ; it was remarkable that the bolts stood exceedingly well and pre- vented the plates buckling ; the bolt-holes were evidently a cause of weakness, as cracks almost invariably commenced there. The number of shot of different rounds fired at these plates is as follows : 656 ORDNANCE. 12-pdr. Armstrong 25-P dr - " ........................................................ 16 4o-pdr. " ........................................................ ii 68-pdr. " ........................................................ 10 Total But the plates are still firm and in good order ; and the wall is in as complete a state for defensive purposes as before the firing commenced. MAY 16xH. The experiment was continued with a 100-pounder Armstrong gun, firing for the first 10 rounds shells filled with sand': weight, empty, 95i Ibs. ; full, 104 Ibs. ; charge, 12 Ibs. ; then 4 rounds solid cast-iron shot from 68-pounder 95 cwt., with a charge of 16 Ibs .; then 21 rounds, alternately 8-in. shell and 100-pounder Armstrong shell. With the 8-in. shell Pittman's naval fuze was used ; with the Armstrong shell, the Pillar fuze. Every shell burst on striking. Range, 400 yards. The 100-pounder shell filled with sand penetrated all the plates, except the 3^-in. The first shell that struck this plate did appa- rently no damage at all ; it broke up, making a small indent on the plate ; another, however, on striking near the same place, broke half the plate away and exposed the masonry. After 10 rounds of 100-pounder blind shell" and 4 rounds solid 68-pounder shot had been fired, the plates were so damaged that live shell were used. The live shell did very little damage when they struck the iron plate, not nearly as much as the blind shell, owing probably to its bursting before the whole of its force was expended on the plate ; but when the live shell struck where the masonry was exposed they caused great damage, and soon brought the wall and surrounding masonry to such a state that a few more shell would entirely have destroyed it and the casemate next to it. This experiment shows that masonry covered with 2-in. iron plates will effectually resist a 12-pounder Armstrong shot at 600 yards. Covered with 2-in. plates it will effectually resist a 25-pounder Armstrong shot at 600 yards. EXPERIMENTS AGAINST ARMOR. 657 Covered with 3-in. plates it will effectually resist a 40-pounder Armstrong shot at 600 yards. But the 3i-in. plates are not sufficient to resist the heavier nature of projectiles. The iron plates were manufactured of rolled iron by Messrs. Brown, Hughes & Co., Newport. 5 feet 6 inches by a feet 6 inches, ) , . , . , . . 4 feet 6 inches by a feet 6 inches^ } *' **' 3 ' 3 * mcheS m thlckness Each plate was secured to the masonry by six 2-in. bolts which passed through the plate and were secured by double nuts to railway bars buried vertically four feet in the masonry ; the tops of these bars were again secured by bolts to the rear of the work. (See Table 120.) RESULTS. MASONRY PROTECTED BY IKON. (TABLE 120.) 1. Hit right-hand corner of masonry ; buried itself in the brickwork. 2. Hit centre of 2|-iii. plate ; very slight indent ; no cracks ; shot broke. 3. Missed. 4. Hit left-hand top corner of 3-in. plate just over the bolt ; one very small crack from the bolt-hole ; indent, very small ; plate not hurt. 5. Hit centre of 3-in. plate; very small indent; plate not damaged. 6. Short arid ricochet. Hit 3-in. plate to left of left-centre bolt, half on plate, half on masonry ; bolt slightly drawn out ; plate bent a little but no damage done. 7. Short and ricochet. Hit 2-in. plate with side of shot, just leaving the mark of its shape on the plate. 8. Struck on the edge of the 3-in. plate near right-centre bolt ; made a circular crack through bolt-hole; diameter of the cracked part, 7 inches. 9. Hit close to No. S ; very small indent ; no cracks. 10. Hit 3i-in. plate near the centre ; no damage to plate: 11. Hit 4 in. from top of lower 2i-in. plate ; no damage done. 42 658 ORDNANCE. TABLE CXX. EXPERIMENTS AGAINST MASONRY PROTECTED BY IRON. MAY 9, 1861. . Projectile. 5 to T3 >> Effects. I 1 I 6 ft Nature of Ordnance. ! 1 Charge in Ib Elevation. Kange in ya: 1 1 "B 1 Depth of In- dent in ins. Area of In- dent in ins. | Ibs. oz. / ' I I2-pdr. shot.. ii. 9 ... i i 4 600 4 R ... i ... ... 2 ... u I 2 u 2 R i ... ... M n u I O II 2 L 4 cc ... It I M 2 L ... i ... ... 5 M ... u o 57 " 2 R i ... ... 6 25-pdr. shot.. Mtt ... 3/6 o 56 " 2 R 1 ... ... 7 M u I O H R T* 1 *^ / 8 ... " o 58 II 6 R ... i ... ... 9 u o 56 " 8 R ... 1 ... ... 10 M " o 57 II 8 R ... i ... ... ii " ... u o 57 " 8 R ... i ... ... 12 4O-pdr. shot.. 40 ... 5 o 58 U 4 R ... 1 ... ... '3 ... it o 58 (I 4R ... 6 ... ... 14 M u o 58 H 4 R *T 15 25~pdr. shot.. HH 3ft o 57 - T ix 8 R ... i ... ... 16 " ... " o 57 8 R ... I ... ... 17 " ... o 57 " 8 R ... i ... ... 18 M u ... II ... ... i ... ... 19 ... ... II ... n ... ... 20 " ... It ... " ... *iV ... ... 21 u ... ... 2 ... ... 22 ... u ... ... 3 ... ... 21 u M (1 o 58 II 8 R J 2 4 " " ... u " * 3. EXPERIMENTS AGAINST ARMOR. TABLK CXX. (CONTINUED.) 659 Projectile. d t> Effects. fed "3 ; *G iS es ^ B ,0 ^3 Nature of - d P HH C 00 ^ T* o .5 ^* o a C^'a UWM .S' O d Ordnance. s 1 | O I 1 I '3 11 g-s O *" |S Ibs. o / ' *s 4-, c ! Deflection. 5 c 3 13 Effects. tl 3 tr s If M t I 1 Depth of In- dent in ins. | ?._2 45 - Ibs. > / / 49 loo-pdr. shell 104 12 400 Filled CQ M u with 8| Ibs of sand. ci u tl c,2 ft It 11 68-pdr. shot.. 68 s* 16 4- 400 ICC7 CA 68 M 16 ir 400 c c 68 16 x 4.00 c6 4OO 57 loo-pdr. shell 104 A. 12 4 8' 400 V R ... ... ... H ,58 68-pdr. shell 49-^ Sc. 16 r 400 1746 ... .... H 59 loo-pdr. shell 104 A. 12 4S> 400 8' R 84 60 68-pdr. shell 494 Sc. 16 | 400 ... 1746 .... .... a 61 loo-pdr. shell 104 A. 12 48' 400 9 'R ... .... .... 84 62 68-pdr. shell 49^ Sc. '6 1 400 1746 .... .... H 63 loo-pdr. shell 104 A. 12 48' 400 9 'R ... .... .... 84 64 68-pdr. shell 494 Sc. 16 1 400 ... 1746 .... .... i4 6c lOO-pdr. shell IDA A. 12 48' AOO Q' R 8i 66 68-pdr. shell 49* Sc. 16 4 4 00 1746 .... i4 67 loo-pdr. shell 104 A. 12 48' 400 9'R ... .... .... 84 68 68-pdr. shell 49 -V Sc. 16 r 400 ... 1746 .... .... '4 6g loo-pdr. shell 104 A. 12 48' AOO Q' R 84 70 68-pdr. shell 491 Sc. 16 r 4 00 1746 .... .... i4 ?i loo-pdr. shell 104 A. ia 4 8/ 400 9 'R 84 * S. denotes Spherical; A., Armstrong; Sc., Spherical common. EXPERIMENTS AGAINST ARMOR. TABLE CXX. (CONTINUED.) 661 'C Projectile. 4 | $ Effects. ii Nature of ,0 C5 C >> j 1 ^ 5d , 3 1 a Ordnance. 1 O be O 'S a I 3 ?l 1 II r n 9 r** G ^~" S -f-> -*- ci -^ 5 GQ 6 1 6 1 c3 1 3 fl-l |i M Ibs. / ' 72 68-pdr. shell 49i Sc.* 16 1 400 ... 1746 .... .... I* 73 loo-pdr. shell 104 A. 12 48' 400 9 'R ... .... .... 8i 74 68-pdr. shell 49^ Sc. 16 r 400 ... 1746 .... .... ii 75 loo-pdr. shell 104 A. 12 4 8' 400 9 'R .... .... H 76 68-pdr. shell 49? S. 16 r 400 ... 1746 .... .... i 77 loo-pdr. shell 104 A. 12 48' 400 9/R ... .... .... si * S. denotes Spherical; A., Armstrong; Sc., Spherical common. 12. Hit at the joint of the 3-in. plates; the left bolt slightly drawn, and the plate bent | in., but not damaged. 13. Hit left top corner of the lower 2-in. plate ; broke the plate; a piece 8 in. by 8 in. driven 6 in. into masonry; the bolts were not drawn, nor the plate shaken nor cracked. 14. Hit at junction of 2-in. and 2^-iu. plates ; a piece 6 in. by 7 in. nearly broken out, driven 4 in. into masonry ; the edge of 2-in. plate slightly bulged. 15. Hit centre of 3i-in. plate ; no damage. 16. Hit centre of 2i-in. plate ; no damage done. IT. Hit near centre of 3i-in. plate ; no damage. 18. Hit at junction of 2^-iii. and 3i-in. plates ; 2-in. plate driven in in. 19. Hit centre of 2^-in. plate ; no damage done. 20. Hit lower 2-in. plate ; made a large circular crack round the indent. 21. Hit lower 2-in. plate near bolt-hole ; two large cracks, one on each side of bolt-hole, extending from it 6 in. 22. Large crack passing through the bolt-hole near the indent 662 ORDNANCE. and extending round it in diameter 12 in., plate much bent ; the bolt-hole evidently weakened the plate. 23. Hit top of granite. 24. Hit 2i-in. plate 4 in. from the edge ; the plate much cracked within and round the indent, in area 8 by 10 in. 25. Miss, short, and ricochet on to bottom of plate. 26. Hit lower left plate (2^-in.) near left-centre bolt, bulged the plate into masonry in area 6 in. by 7 in. ; two cracks from the bolt-hole. 27. Hit close to No. 25 at bottom of 3-in. plate, 2 in. from a bolt ; drove a piece 12 in. by 5 in. into the masonry 4 in. deep. 28. Struck 300 yds. short and over target. 29. Miss; short. 30. 31, 32. Hit lower 3|-in. plate ; damage very slight. 33. Struck 300 yds. short ; hit top of 2-in. plate over top right- hand bolt ; diameter of indent, 9 in. ; the corner of the plate buckled up 1 in. ; masonry started and cracked a little. 34. Hit at junction of 2-in. and 3-in. plates ; depth of indent, 8 in. ; area, 7 in. by 11 in. ; started masonry J in. and cracked the granite block on the top; a crack from the bolt-hole of 3-in. plate. 35. Missed the target and hit Thorneycroft's embrasure close to its left edge, on the 5th bar from top ; broke the bar and drove it 5 in. into the opening of the embrasure. 36. Hit 2-J-in. plate, crack extending from a bolt-hole ; a piece of the plate 20 in. by 9 in. driven into the masonry, which was much shaken. 37. Hit at junction of 2^-in. and 2-in. plates, which separated iin. 38. Hit top of lower 3^-in. plate ; crack through left upper bolt- hole ; it struck over No 11. 39. Hit top of stonework. 40. Hit at the junction of the two 3|~in. plates ; the plates sep- arated f in., crack extending from bolt-hole to No. 32 shot-hole ; the bolts not a bit started. 41. Hit corner of the granite and brought down a large piece. EXPERIMENTS AGAINST ARMOR. 663 42. Hit lower edge of 2-in. plate ; shot broke up and remained in the hole 5 in. in masonry. MAY 16, 1861. 43. Struck bottom corner of 2-in. plate on the top of the bolt, broke away a piece 15 in. by 9 in., and drove it, broken up with the pieces of the shell, 2 ft. into masonry ; struck over No. 42. 44. Struck at the joint of 2^-in. plates, broke away an irregular hole 14 in. by 11 in., and forced the pieces with the shell 1 ft. into masonry ; lower bolt very much damaged and bolt bent. 45. Hit junction of 2-in. plates ; shell broke up and driven into the masonry about 15 in. deep; broke away the left corner of lower 2^-in. plate near last round; broke off 5 in. of the bolt where hit. 46. Struck joint of 3-in. plates ; hole, 9 in. by 12 in. ; drove pieces, with pieces of shell, 10 in. into masonry ; plate not cracked, very slightly bent ; the plates slightly separated. 47. Struck 2-J~iii. plate near left edge over No. 24, broke away a piece 2 ft. by 9 in., and drove it in pieces, with pieces of shell, 1 ft. into masonry ; plate much bent, no cracks. 48. Hit joint of 3|-in. plates over the 68-pounder No. 38 ; two large cracks extending through bolt-holes in a circular direction right across the plate ; another circular crack on lower plate through the port-hole ; did not penetrate. 49. Hit centre of lower 3^-in. plate ; started a bolt 1 in ; plate very slightly bent ; depth of indent very small indeed ; plate not damaged at all ; a great deal of masonry shaken down from top. 50. Hit near the same place ; plate a very little buckled, and cracked across ; the bolts stood well, the plate being forced back on them ; the crack passed through a bolt-hole. 51. Hit centre of 3-in. plate ; depth, 3J in. ; large circular crack round indent ; diameter of crack, 14 in. 52. Struck lower 3-J-in. plate, broke away the upper half of the lower plate, except a small corner near left top bolt ; right top bolt broken ; the piece cracked through, and much buckled. 53. Hit on the exposed part of masonry, on the place where the 664 ORDNANCE. piece of plate fell off. Penetration 2^ ft. to shot ; masonry much broken ; shot not broken. 54. Hit just at edge of hole made by No. 5 ; shot broke up ; increased the hole by a circle 9 in. in diameter. 55. Hit 3^-in. plate at edge of hole made by No. 5, increasing hole by a circular hole 9 in. in diameter ; plates much separated ; brickwork powdered to a depth of 14 in. ; bolts near a little bent. 56. Hit Thorneycroft embrasure; depth of indent, If in.; no damage done; diameter of indent, 9 in. ; no cracks at all visible. 57. Hit near No. 3 ; passed through the plate, and burst behind the plate, breaking away a large piece, making 3 and 2 into one hole ; masonry much damaged behind. 58. Shell struck near top of 3^-in. plate ; broke away a piece 9 in. in diameter. 59. Hit at junction of 2-in. and 2^-in. plates between Nos. 2 and 3, and near No. 15 ; damaged the masonry very much ; the effect on the plate could not be seen, as it was so damaged by pre- vious shot. 60. Struck where the 3^-in. plate was broken away ; broke off one bolt, and crumbled away the brickwork to a depth of 3 ft. 61. Hit lower 3-in. plate about the middle ; blew away half the plate, starting and bending all the bolts near, and undermining the whole centre of the plates. 62. Hit at top of 2^-in. plate ; broke away a large piece ; under- mined the plate. 63. Hit in the hole made by the destruction of the upper part of 2-J-iu. and 3|-in. lower plates ; increased the depth of the hole in the masonry ; the plates were so damaged round here that the effect could not be ascertained. 64. Hit nearly in the same place as last, increasing the breach in the masonry to a depth of 4 ft. ; broke and bent the bolts all around. 65. Hit nearly in the same place as the former shot ; the plates and masonry were so damaged that the effects cannot be recorded. 66. Hit left lower corner of upper 3-in. plate ; bulged in the piece 2-J- in. ; plate started forward J in. EXPERIMENTS AGAINST ARMOR. 665 67. Hit centre of target; broke away a piece of plate 2 ft. square, with a bolt 4 ft. long attached to it ; increased the hole in brickwork. 68. Hit the granite to the left ; split the granite block, but did little other damage. 69. Hit 3-in. plate, upper, near the centre; broke away the lower half, leaving the piece supported by one bolt ; broke away and started the masonry round, and started the plates and brought down some more masonry. 70. Hit the same place as last shot ; increased the hole ; cracked the masonry behind. 71. Hit centre of 2-in. plate; knocked the whole iron face to pieces ; the few pieces of plates remaining were merely hanging by the bolts ; the railway bars and masonry behind them perfectly secure. 72. Hit the left on the granite ; did not do much damage. 73. Hit bottom of 2-in. plate ; passed through it and 1 ft. 8 in. into the masonry. 71. Hit at the bottom among the debris of the masonry, and did not much increase the damage. 75. Hit near centre of target ; broke away some more masonry. 76. Short 20 yds. ; hit 3-in. lower plate ; broke away a piece 9 in. by 11 in. 77. Hit against the railway bars, broke one of them, and broke through the masonry, driving out a solid piece of brickwork 2 ft. square ; the masonry much shaken and cracked behind ; the arch of embrasure cracked nearly across in two places ; some of the bricks driven 20 yds. in rear ; the upper part of masonry cracked and started. 8^5. Inclined Plate.* "About this time the question of the relative increase of resistance given to iron plates, when inclined at various angles, was again brought up ; and in apparent contra- diction to the experiments at Portsmouth, on Jones's butt, in I860, there was found*to be no apparent difference in the powers * Captain Inglis's account, continued. 666 ORDNANCE. of resistance of f-in., 1^-in., and 3-in. plates, whether they were placed at angles of 30, 45, 60, or vertical. The plates were without backing, merely held on to a skeleton framework of wood. They were fired at by the wall piece, 6-pounder Arm- strong, 12-pounder, and 40-pounder, at ranges of 25, 50, and 100 yards ; the bullets of wall piece were of steel, flat-headed cylin- drical, and the other shot of wrought and cast iron. " Subsequently, in continuation of this experiment, two plates of wrought iron, placed respectively in a vertical position, and at an angle of 45, were tried, each having a 12-inch oak backing, and there being in them equal weight of iron for the same verti- cal height The inclined one was 3^-inch thick. The vertical 4^-inch thick. " They were fired at by a 40-pounder, at 100 yards, and there was scarcely any difference ; in each case a dent of about j\ inch was caused. "Afterwards, a 100-pounder, at 200 yards, sent a hemispherical- headed shot through the inclined plate, but it did not get through the vertical ; and a square-headed 100-lb. shot did not penetrate the inclined plate so much as the hemispherical-headed shot ; and, altogether, the vertical plate may be said to have stood best. Whether the apparent discrepancies between these results, and those at Portsmouth are to be accounted for by spherical shot having been used in one case and elongated in another, or whether they may not be reconciled in some other way, I am not prepared to say ; but, at any rate, the effects are worth considering, and I think the experiments should be carried further, until the differ- ences are accounted for. 826. Plates of 6| and 4* Inclie. " In July, 1861, two plates of T ft. x 3 ft., of hammered scrap, unbacked, respectively 6 \ and 4|- inches thick, standing vertical, were fired at, at 400 yards range. A cast-iron shot, 126 Ibs., from Armstrong's muzzle-load- ing shunt gun, struck a 6-J-in. plate, made an indent of 1-9-in., and cracks were shown behind ; and another shot of same kind EXPERIMENTS AGAINST ARMOR. 667 struck a 4^-in. plate, and cracked and bulged it very much; another of them, and two 110-lb. cast-iron shots, quite destroyed this 4J plate ; while the 6 J-in. plate, after receiving three fair shots from the 126-pounder, was also broken up." 8SJ7. Roberts's Target. In 1861, a target of special con- struction, provided by a Mr. Roberts, was tried. " This consisted of a mass of timber and T-plates, protected by armor-plates 3 and 4 inches thick, of malleable scrap-iron, about 2 feet wide, ham- mered and rolled to such form as to present a series of angular projections, ridges, and furrows ; the apices of the angles were pointed with steel. " It was altogether of too complicated and costly construction ; and, although the armor-plates were of very good iron, it was sep- arated and opened out, and the fittings damaged, and ultimately all destroyed by a few 68-pounder and 100-pounder shot."* 828. Fairbairii's 1st Target. "Another target, of a con- struction proposed by Mr. Fairbairn, was tried about this time. It consisted of rolled plates 5 in. thick, attached by a number of If-in. screws to a J-in. sheathing, supported by wrought-iron built- up ribs of -J-in. plate, 12 in. deep and 18 in. apart ; the screws were 7^ in. apart, and tapped for a depth of 2 in. only into the back of the plate. The plates themselves stood remarkably well, but the tap-screws broke off so easily that the armor became completely separated from the rest of the target, and so became useless ; 4-in. elm on face decreased effect." 829. Captain Coles's Cupola. The revolving cupola tried at Sheerness, in 1S61, was a truncated cone in form, and was com- posed of "massive timber, about 18 in. thick, covered with armor- plates 4^- in. thick ; the internal diameter of the cupola is about 12 feet, and the height about 8 feet, inside ; the sides are inclined to the horizon at an angle of 40. The gun is mounted on a spe- cial carriage, and extends some feet outside the port ; the chase of the gun just in front of the trunnions rests on the sill of the * Two 68-pounders cracked the plate and broke two bolts. A salvo of three 10CT- pounders made a hole 18x9 in., and cracked the plate across. 668 ORDNANCE. port. The whole cupola revolves by means of winches on a sort of turntable, so that the training of the gun is effected by turning the whole apparatus ; and the porthole, therefore, is only a nar- row slot long enough to permit the gun to be elevated and depressed. " On the day of trial, the cupola, as erected on the ' Trusty,' was subjected to very severe tests, not only to try its endurance under fire, but also to test the working of the machinery under all circumstances ; and it was proved that, even after heavy battering, and with the vessel heeled over several degrees, there was no diffi- culty or obstacle whatever in working the apparatus ; on the con- trary, it afforded very great facilities for rapid and accurate firing, and for keeping a moving object in sight, and this with a very small complement of men. A great number of shot (nearly 100) were fired from the 40-pounder Armstrong gun in it, and then it received a few shots from a 40-pounder, and a great many blows (26) from a 100-pounder at 200 yards. " Four 100-pounder shot, striking very near the same spot, broke through into the cupola, but the machinery worked as well as before. " The muzzle of a cast-iron gun, mounted in the cupola, was struck by a shot ; the gun broke off a short distance in front of the trunnion, and a portion went overboard. " After this, a 68-pounder was laid upon it, at 200 yards, and had much the same effect as the 100-pounder, but the cupola was never thrown out of gear ; there was no difficulty from smoke, and only a little from concussion and altogether, its performance was considered highly satisfactory. 83O. Various Backings to Iron Plates. " After this, in order to test the various effects of different sorts of backing, some 2J-in. wrought-iron plates were fastened respectively to blocks of cast iron 3 feet thick, to solid granite, to a mass of oak made up of timbers 10 in. by 10 in., and to a mass made of alternate layers of fir and cork and bitumen cork. " The results proved the immense superiority of a massive rigid over an elastic backing, both as regards the plates themselves EXPERIMENTS AGAINST ARMOR. 669 and also as regards the fastenings.* The 40-pounder service shot, at 200 yards, did little or no damage to the plates backed by FIG. 378. Section of the Warrior's side. granite and cast iron, bnt went clean through the plates backed by oak and fir, and did great damage to it. " A 100-pounder cracked a plate backed by cast iron, and the cast iron also, but did lit- tle damage." 831. Warrior Target. " Later in the year (1861), a target, representing a piece of the ' Warriors' side, was fired at by 68-pounder, 100- pounder, and 120-pounder. It measured 20 feet by 10 feet, and had a porthole in the centre, and was struck by 13 solid shot, besides 6 experi- mental 200-lb. shot, thrown with, a reduced charge from a 100-pounder gun, and by 10 shells. Section of the Warrior target. * In this experiment there were four plates, 4 x 2 ft. x 2^ in. The backing of the first was cork and kamptulicon. The plate was smashed like glass. The backing of the second plate was oak. The plate was badly broken, and the shot lodged in the oak. The third plate was backed by granite. The indentation of the shot was in., and the plate was not cracked. The fourth plate was backed by a block of cast iron, and no injury was done by the shot, except a small indentation. The other advantages of wood backing, for naval purposes especially, have been mentioned. (199, note.) 670 ORDNANCE. " The result was, that although, the armor-plates were more or less cracked and indented, and deflected especially where 12 shots (of which one was a steel 100-lb. shot) struck a plate within an area of 4rJ square feet, the back of the target, agreeing with the ribs and sheathing of the ship, were not at all injured." (Table 121.) Table 121 is the official account of this experiment. The target was "exactly similar" to a midship section of the Warrior : length, 20 ft. ; height, 10 ft. ; with a porthole in the centre. This target was strongly supported by timber, at the same angle as the side of the ship, and was fired at with the following guns. Range, 200 yards : One izo-pdr. muzzle-loading shunt gun. I One 68-pdr. 95 cwt. gun. Three loo-pdr. breech-loading Armstrong guns. | One 68-pdr. na cwt. gun. The following shot and shell struck the target : From 120-pounder gun, Solid shot 25 weight, 140 Ibs. each. From 100-pounder guns, Solid shot 65 weight, no Ibs. each. I Solid shot 6j weight, soo Ibs. each. Shell 6; weight, 104 Ibs. each. | Solid shot i j steel. From 68-pounder guns, Solid shot 4; weight, 66 Ibs. each. | Shells 45 weight, 49^ Ibs. each. RESULTS. WARRIOR TARGET. (Table 121.) 1. Hit on upper plate; made very slight indent; opened the plate | in. 2, 3. Hit close together on the centre left plate ; made a small crack 5 in. in length. 4. Hit on upper plate, 7 in. from the edge ; opened the plates J in., and started two bolts very slightly. 5. Hit centre of left-middle plate, 3-J ft. from port, 7 in. from a bolt, which it drew J in. ; broke the two bolts close to the port, and buckled the plate f in. 6. Hit on junction of lower and centre plate ; did no damage. EXPERIMENTS AGAINST ARMOR. 671 TABLE CXXI. EXPERIMENTS AGAINST THE "WARRIOR" TARGET. OCT. 21, 1861. No. of Kound. Nature of Ordnance. Charge, Ibs. Nature of Projectile. Weight, Ibs. Indent in ins. I loo-pounder 12 shell filled with sand. 104 2 K u u ... 3 " " " ... 16 el 49^ I -C 5 tt ~y 2 j tt 6 12 shell filled with powder. 104 7 u ... 8 M " ... g 68-pounder 16 M 494- i8 7 10 X A ... II i 20 pounder 20 solid cast-iron shot. 140 j i 12 i oo-pounder 14. no j J 3 * T t< 1-9 '4 M (C M " 1.3 1C 68-pounder 16 661 2 . 7 -) 16 JO 4< 200 17. M M ... 18 H M iC ... 19 " If " ... 20 M " ... 21 -i/~l f*/-\-v*\7' 1~\n /Vlyii-fc r* \ I 12-pounder " -6 " Ditto, through. 40-pounder 3-inch. 40-pounder Armstrong, 100 yards, not through. 3-inch. Two 78-pounder shell filled with sand, at 400 yards, passed through. 3 inch. Two 78-pounder shell filled with sand, at 400 yards, just resisted. 3 -inch (brick backing). 40-pounder Armstrong, 600 yards, passed through. Ditto. 68-pounder, penetrated. Ditto. 100-pounder shell, at 600 yards, penetrated. 3^-inch (brick backing). 40-pounder Armstrong, at 600 yards, no effect. 3-94-inch. Kesisted 14 shots of 30 Ibs. (English 32'4 Ibs.), at 300 metres in a square metre, or lOf square feet English. 4-inch. 68-pourider, did not penetrate. 4-inch. 72-lb. shot, just penetrated. 4-inch. Hollow and red hot shot, little impression. 4-inch. 32-pounder, at 100 yards, sunk deep, but not through. 4-inch, on Alfred. Whitworth 68-pounder, at 350 to 450 yards, indent, f in. ; bulge, If in. Ditto. Same gun, wrought-iron shot, through, and penetrated 7 in. in oak. 676 ORDNANCE. 4-inch ( + 6 inches oak and f iron, Erebus). 68-pounder, at 400 yards, penetrated, and did great execution inboard. 4-inch (on oak ship Meteor). 32-pounder and 68-pounder, at 400 .yards and 300 yards, no damage inboard. 4-irich (24 } (at 600 ) indented with cast-iron 8 ' inches oak), > yardS) y, to 2 . 3 shot Ditto, " 2-2" to 2-8" " wrought do. Ditto, " 400 " 2-2" " cast do. Ditto, " 3" " wrought do. Ditto, " 600 " would ultimately destroy. One 68-pounder does as much damage as five 32-pounders. 4-inch (2 feet 1 inch oak, Trusty). 72-pounder cast-iron shot, at 400 yards, broke plate but not scantling. Ditto. 72-pounder, homogeneous iron, fairly through. Ditto. 100-pounder cast-iron shot, at 200 yards, did not pene- trate. Ditto. 78-pounder homogeneous shot, through, and 10 in. oak. Ditto. 100-pounder homogeneous shot, at lower velocity, large fracture. 4rJ-inch ) 32-pounder, at 360 yards ; indent, 2 in. -f f 68-pounder, at 1250 yards ; indent, 1 in. 4-in. fir ) " " 400 yards; indent, 2f in. Several shot together injured the plates very much. 4^-inch, on timber. 80-pounder homogeneous flat-headed shot punched a hole, and 3 in. into timber. 4J-inch, on timber. Three 68-pounder shot close together, broke up a plate. 4^-inch, Jones's angular butt. Took 17 blows from a 68- pounder, at 200 yards, and then the iron was not penetrated. 4^-inch. 126-pounder, at 400 yards, cracked and bulged much. 4J-inch. Two 110 Ib. cast-iron and two 126 lb., at 400 yards, quite destroyed. 4J-inch, on Warrior. More or less cracked by 68, 100, and 120-pounders, but ribs and inner skin uninjured. EXPERIMENTS AGAINST ARMOR. 677 68-pounder, indented 1*5 i-g 100 " 1-3 to 1-9 120 " " 3-1 4|-inch, on timber. Considered protection against 68-pounders, at 1200 yards ; but 68-pounders, at 400 yards, indented 2'75 in. Ditto. Considered protection against 32-pounders and 8-in. hollow shot, at 400 yards ; 32-pounder indented 1J to If in. Ditto. Three 32-pounders striking near each other will break it up. 5-inch plate, "] 68-pounder shell, at 200 yards, indented 1*25. on iron 68-pounder shot, " " 2-00. sheathing & [100 " 1-T5. ribs. j 120 " " " 2-25. 5J-inch. Kesisted 18 shot of 30 pounds (English, 32-4) in a square metre (10j feet square), at 300 metres range. 6-J-inch. 126-pounder cast-iron shot, at 400 yards, indented 1*9. " " " a few shots broke it up. 8-inch, supported by "1 68-pr. cast-iron shot, at 600yds., indented 1*25 cast-iron " " " 400 " " 1-4 and granite. J " wrought-iron shot 600 " broke it up. " As, without knowing the velocity of the several shot here mentioned at the time of impact, it will be impossible to make a comparison of the resistance offered in these experiments, I have drawn up a brief abstract of the initial velocities of all the guns in the service.* 8S5. " Now I do not know whether it is possible to draw from all this any universal rules. I have not done so myself, but others may ; but, at any rate, some general practical laws may be laid down from them, such as : " 1st. Good tough wrought iron of high elasticity, but not necessarily of the highest ultimate tensile strength, is the best material for use in iron defences. * See Table 112, of initial velocities, which embraces the one given by Captain Inglis. 678 ORDNANCE. " 2d. Rolled iron, although not perhaps equal in resistance to the best hammered iron, has such great advantages as to cost, if used in simple forms, as to justify its use where lightness is not of extreme importance. u 3d. Cast iron and steel, as at present manufactured, are too brittle ; the former can only be thought of as backing, or where weight is wanted. " 4th. In plates or bars of ordinary dimensions the resistances to cannon-shot vary in a proportion approximating that of the squares of the thicknesses of the plates or bars. " 5th. Rigid backing is immensely superior to elastic backing, so far as the endurance of the front facing is concerned, but the elastic backing deadens the effect of a blow upon any structure behind. " 6th. The larger the masses and the fewer the joints the stronger the structure, so long as the limits of uniform and perfect manufacture are observed. " The slight advantages gained by inclining the surfaces do not compensate for the extra difficulty and expense in construction involved, except in a few instances. " 7th. That revolving iron shields are practicable and safe." 836. Captain Dyer, in his paper before quoted, thus sums up the same experiments. " These preliminary experiments determined the following points : " 1. That steely iron, commonly known as homogeneous iron, puddled steel, &c., when in large masses, is inapplicable for de- fensive purposes ; although in the thinner plates this metal offered great comparative resistance, it became brittle when in large masses, and readily cracked when struck by a shot. " 2. That plates of a hard crystalline structure are inferior to those of a soft fibrous nature. "3. That the great fault and primary cause of weakness in all forged plates is unsoundness in welding the different piles of which the plate is composed. This defect was invariable in all (except the homogeneous iron plates) ; it was more apparent in EXPERIMENTS AGAINST ARMOR. 679 the rolled than in the hammered plates, but this was compensated for by the hammered plates being harder and more crystalline than those forged under the rolls ; and this led to the conclusion that there is but little choice between the two processes, if both are properly worked out with efficient machinery. " 4. That the qualities necessary in an armor-plate are softness combined with toughness, or better expressed by the word duc- tility. Apparently, the purer and better the iron is, the more this quality is perceptible; any impurity or alloy appears to harden the metal and produce brittleness. The presence of either sulphur or phosphorus in the fuel is specially to be guarded against, as productive of red shortness and cold shortness in the iron. The presence of more than 0*2 per cent, of carbon in armor-plates also appears highly prejudicial." 837. Stevens's Inclined Laminated Armor. On the 4th of January, 1862, Mr. Stevens, of Hoboken, fired at a section of the armor at that time proposed for the Stevens Battery. The follow- ing is the official report of the experiment : "A 10-in. gun, procured from the Navy Department, weighing 9883 Ibs., was mounted with India-rubber buffers behind the trunnions. The gun was loaded with a full service charge, 11 Ibs. of powder, and a solid spherical ball weighing 124 Ibs., and was fired at a target exactly representing a section of the armor of the Battery r , and anchored in the river, 220 yards from the gun. "The target was composed of layers of plate-iron, from f to 2 in. thick, making 6f in. in all. It was 4 ft. broad, 8 ft. long, and set at an angle of 27^ with the horizon. The iron was backed with two layers of locust timber 7 in. thick each. In the lower layer were imbedded wrought-iron beams 6 in. high, 4 ft. apart and 2 ft. apart, weighing 46 Ibs. to the yard. Beneath the wood was a |-in. iron plate ; making the entire thickness 21J in.* The upper and lower plates were fastened to the wood by wood screws 15 in. apart, and the side edges of the upper plates were battened by iron 1 in. thick and 3 in. wide, and riveted together. This * This backing somewhat resembles that of the Chalmers and Bellerophon targets the best English backing. 680 ORDNANCE. target rested on a raft, so as to have no support except at the edges ; the lower part of it was 18 in. under water. " After a few experimental shots the gun was pointed at the target, and the 1st shot struck it 21 in. above the water and within 9 in. of the right edge of the target. Its effect was to make an indentation and depression, which together were 1} in. deep in the deepest place, and which ran out to the surface or diminished to nothing in a distance of 13 in., measured on the line of flight, without cracking any of the plates. The 2d shot passed to the right of the target, and the 3d went over it. The 4th shot struck the target on the left side, 13 in. from the edge and 11 in. above the water, with the same effect as that of the 1st shot, except that the depression was If in. deep. The figure of this indentation was similar to that of the first. The recoil of the gun was TJ in., and did no injury to the carriage or buffers.* "A Parrott rifled gun, having a 6*4: in. bore, and weighing about 9300 Ibs., was then fired at the target, with 10 Ibs. of pow- der, and an elongated shot weighing 100 Ibs. Several of these shots were fired, and one struck the target 4 ft. 6 in. from the water, and 6 in. from the right side, making a depression 1 in. deep, and running out to the surface at a distance of 8 in., with- out doing other injury to the plates. This shot grazed the edge of the batten, upsetting the corner to the depth of ^ in." 838. Experiments agaiiit the " Committee Target," mareh 4, 1862. (See Tables 122 and 124.) This target (20 x 10 ft.) was composed of two plates 20 ft. x 3 ft. 4 in. x 4^ in., and two plates of 9 ft. x 3 ft. 4 in. x 4rJ in., the upper and lower of which * " This gun was loaded by steam power, the muzzle being depressed so as to bring the bore parallel with a steam-cylinder situated below a platform made to represent the deck of the Battery. The platform was composed of white-pine planks 2 in. thick, resting on pine beams 5 in. square and 2 ft. apart, from centre to centre, and calked and pitched in the usual manner. The piston-rod of this steam-cylinder was the ram- rod of the gun. Upon the upper end of this ramrod was a swab, which also an- swered the purpose of a rammer. The cartridge and ball were attached to a sabot and placed on a scoop arranged so as to lift the ball up to its proper position between the rammer and the muzzle of the gun, when, steam being admitted to the cylinder, the ball was forced home. The gun was then elevated and fired." (See chapter on "Breech-Loading.") EXPERIMENTS AGAINST ARMOR. 681 were secured by fifteen 2-in. bolts, and the two centre by eight 2-in. bolts each. The plates were fastened to 1-in. plates, which latter formed the skin of the ship, which was supported by ribs 18 in. deep and 18 in. apart, made of |-in. plates, secured by angle-irons 4 in. x 4 in. x f in. ; the backs of the ribs were secured by four strips of plate 12 in. x i in. ; strips 10 ft. x 9 in. x f in. were placed behind the skin along each line of bolts. The plates were rolled by Messrs. John Brown & Co., Sheffield. The object of the experiment was to determine whether wooden backing can be dispensed with. The " Committee target" was, therefore, constructed with the view of comparison with the Warrior target. . "Committee target:" area, 200 square feet; weight, 31 tons. " Warrior target :" area, 200 square feet ; weight, 32 tons 9 cwt. 3 qrs, The guns used were the same as against the Warrior target, viz. : One lao-pdr. muzzle-loading shunt gun. Three loo-pdr. breech-loading Armstrong guns. One 68-pdr. 95 cwt. gun. One 68-pdr. 112 cwt. gun. Range, 200 yards. The following shot and shell struck the target : From 120-pounder gun, Solid shot ij weight, 140 Ibs From 100-pounder guns, Solid shot 3; weight, no Ibs. each. | Shell 6; weight, 1 04 Ibs. each. Solid shot 35 weight, 200 Ibs. each. From 68-pounder guns, Solid shot ij weight, 66 Ibs. each. | Shell 4; weight, 49! Ibs. each RESULTS. "COMMITTEE TAKGET." (Table 122.) 1. Hit centre plate to the left of porthole, about 9 in. from bottom of the plate ; very slight indent. Diameter of bulge, 5 in. 2. Hit left-centre plate 18 in. from bottom and about 5 ft. from left ; indent very slight. 3. Hit left-centre plate about 12 in. from top ; slight indent. Diameter of bulge, 3 in. 682 ORDNANCE. TABLE CXXII. EXPERIMENTS AGAINST THE "COMMITTEE TARGET." MARCH 4, 1862. T3 g 1 1 1 pS 'c Nature of Ordnance. f Nature of Projectile. } a "q 1 P 1 I loo-pounder. . I 2 shell filled with sand. 2 H < ... 3 C| ... 4" 68-pounder 16 M , 5 H M H 6 i oo-pounder 12 shell filled with, powder I 04. ... 7 " " " " ... g 68-pounder 16 H I 14. s 10 M M u A 1 *^. 1-26 1 i no-pounder . .. 2O solid castiron shot. 12 ioo-pounder 14. I IO 13 u ^* u M .'", I c 68-pounder 16 66 i -8 j 16 I oo-pounder 10 H 200 o -4 u 0-5 18 " " " " 0.7 4. Struck left-centre plate IT in. from bottom, and close to No. 2 round. Diameter of bulge, 8 in. 5. Hit left-centre plate about 18 in. from bottom, and close to the 4th round. Diameter of bulge, 9J in. At the conclusion of the 5th round, the target was inspected. The left-centre plate had buckled f of an in. ; two bolts in bottom plate, and two in centre plate, and one in top plate, started. Eight EXPERIMENTS AGAINST ARMOR. 683 bolt-heads were broken off; one rib broken through, and two rivets of angle-irons knocked out. Two angle-irons broken. The bolts were slackened after this round. 6. Struck on junction of middle and upper plate, 2 ft. 2 in. from left edge of target. The middle plate started forward. 7. Struck 2 ft. 5 in. from left edge of target, making an indent 7 in. in diameter. 8. Struck about 6 in. from top edge of the target near the bolt over porthole. 9. Struck middle plate on left of port, and 2 ft. from it. Diam- eter of indent, 10 in. Bolt just above indent started. 10. Struck on junction of middle and upper plate, 16 in. from port. Diameter of indent, 9 . The target was carefully examined after the 10th round, and it was found that all the bolts in the middle plate on the left of the target were broken, except the two nearest the port. The buck- ling was 1-7 in. at the left edge of the plate. The top plate had also started forward 0'4 in. at edge of target. At the back, the inner angle-iron by port on left side and one rib were broken, two rivets driven out, and several started. The skin bulged. No cracks visible on any of the indents. 11. Struck junction of right-centre plate with top plate, at about 3 ft. 10 in. from port. 12. Struck the bottom of upper plate close to No. 11 round. 13. Struck centre of right-centre plate. 14. Hit target close to 12 and 13 shots, and went clean through the target, carrying a large piece of the plate, part of the rib (on which the shot struck), and pieces of angle-iron 10 or 12 yards to the rear. The fracture measured in front of the target 1 ft. by 7 in. on the middle plate, and 5 in. by 3 in. on the upper plate. There was also a curved crack, 14 in. long, round the edge of the bulge, and through a bolt-hole. 15. This shot struck within 5 in. (from centre to centre of indent) of the 13th round. The middle plate was bent back 1-6 in. at its lower edge. One bolt was knocked oat and two started. Middle plate started forward at right edge of target 0'65 in., and 684 ORDNANCE. the upper plate similarly O2 in. At the back of the target seven bolt-heads broken and one rivet. Two ribs broken through, and several rivets of angle-irons started. 16, 17, 18. These three shot struck the left-middle plate of target in a line, measuring only 16 in. from centre to centre of outside indents. The shot nearest to the port was 8 in., and the one furthest from, 15 in. from the lower edge of plate ; the former 2 ft. 4 in. from port, and the latter only about 4 in. (centre to centre) from No. 4 round. The plate bent back 1*2 in. at its lower edge, at a point 2 ft. 9 in. from the port, and had started forward at left edge 6 in. from skin. Another angle-iron broken, and only three bolt-heads remain- ing on left side. At the conclusion of this round, the target was considered so much injured that the experiment was ordered to cease. 839. Experiments against the Warrior and Committee Targets, April 18, 162; Range, 2OO Yards. Alterations made on Committee target since the experiments of March 4th, 1862. UPPER PLATE. On the left half of this plate, rivets having conical heads, had been substituted for bolts, and vulcanized india-rubber washers inserted behind the bolt-heads on the right half of the plate ; there being no intervening substance between the plate and the skin. This part of the target therefore remained as iron on iron. LOWER PLATE. One quarter in. thickness of felt, dipped in tar, had been inserted between the skin and half the length of the plate on the left side, the fastenings being rivets. On the right half of the plate, J in. thickness of vulcanized india-rubber had been inserted between the skin and plato ; bolts having nuts and india-rubber washers were used for fastenings. A few of the bolts had spun-yarn instead of india-rubber washers. CENTRE PLATES.^-These plates had suffered most from the firing at the late experiment, and had been refastened with bolts having four washers (three of lead and one of iron) under the bolt- heads ; they were not fired at on the present occasion. EXPERIMENTS AGAINST ARMOR. 685 TABLE CXXIII. EXPERIMENTS AGAINST THE "WARRIOR" TARGET. APRIL 18, 1862. No. of Round. Nature of Ordnance. 1 Nature of Projectile. io4 in Smooth-bore 4.0 ico-lb spherical cast iron 2 jo-i in. Smooth-bore 4.0 ico-lb. spherical cast iron. CO lo^-- in Smooth-bore CO ico-lb spherical cast iron EFFECTS. (Table 123.) 1. FRONT. Hit on the junction of the lower and centre plates to the left of the porthole. Smashed in the plates, making a hole 1 ft. high x 14 in. The bulge was 3 ft. 1 in. long x 1 ft. 8 in. high. A crack 2 ft. 7 in. long across top of the bulge, and a huge zigzag crack across the plate and through its thickness. The tongue and groove broken only at the actual hole. BACK. Inner skin fractured and bulged in; strong iron ribs broken in two ; two nuts of bolts broken off. 2. FRONT. Hit the target a little to the right of the previous shot ; 3 ft. 2 in. of the plate smashed, and the wood exposed. A piece of the plate 2 ft. 3 in. x 11 in. broken away. BACK. Skin broken up; a second rib broken. The former broken rib driven clean out and bent back at a considerable angle and smashed. Portions of shot, wooden backing, &c., driven right through. Large irregular hole. The square timbers form- ing the backing to the plates were shattered, and the fibre of the wood seemed to be drawn through the entire length of the beams, by the passage of the shot at the place of fracture and penetration. 3. FRONT. Struck the lower plate on the right side of the port- hole. Made a clean hole 11 in. diameter. Centre of the hole 1 ft. 3 in. from the bottom of the plate. Two cracks extended to the bottom of the plate, but independent of the shot-hole. BACK. Nothing perceptible but a few splinters of wood raised 7 686 ORDNANCE. up from the foot of the target, and a few nuts loosened. One broken off. 4. FRONT. Hit the top plate in the centre of the right side. Made a hole 11/5 in. diameter, and the shot broke up in it. Depth of hole, 13 in. BACK. Struck where the inside skin was supported at top by two beams, with a total of about 2 ft. square solid timber, which was cracked through. The heavy beams also giving sup- port (at right angles to the target) were started, and the solid granite blocks in the rear were shaken. Upon taking the target to pieces, it was found that the inside skin was cracked, and that the shot had penetrated 13 in. into the wood backing, leaving 5 in. of wood into which no fragment of the shot had penetrated. EFFECTS. (Table 124.) 1. FRONT. Struck on junction of middle and lower plates 4 ft. 4 in. from the left side of the target, half the indent being on each plate. Depth of indent, 1/8 in. ; diameter, 10 in. BACK (see below *). 2. FRONT. Struck the target 2 ft. 3*75 in. from the left side, and 2 ft. 5 in. from the bottom of the lower plate. Made a slight indent. A bolt started. BACK (see below *). 3. FRONT. Hit lower plate 3 ft. 11 in. from the left side, and 2 ft. 7 in. from the bottom, making a slight indent. BACK (see below *). Struck on the centre plate. 4. FRONT. Hit on the lower edge of the porthole 7 in. from the left side. A piece of the plate 9*5 in. long and 2 in. wide broken off, and a crack 6 in. long extended from a bolt-hole in the lower plate. Indent, 1*7 in.; diameter, 9*5 in. BACK (see below *). * At the back, a few small rivets, merely uniting the angle-iron to the skin of the ship, were broken off. A very slight crack on one of the angle-irons, where it joined one of the iron supporting ribs. Some of the lead washers of the through-bolts (in the neighborhood of the blows) drawn thinner and worked loose ; india-rubber washer much compressed. EXPERIMENTS AGAINST ARMOR. 687 TABLE CXXIV. EXPERIMENTS AGAINST THE "COMMITTEE TARGET." APRIL 18, 1862. Five rounds were fired at the left side of the lower plate. 1 8 1 Nature of Ordnance. Charge, in Ibs. Nature of Projectile. J 68-pounder ... . 16 Shell filled with sand a Ilo-pounder 12 3 (I 4 M " r 68-pounder. . 16 tt 6* 1 1 o-pounder I 2 Shell filled with powder. 7 16 u 8 12 ft 9 10 6 8 -pounder 16 u Solid shot. 12 16 a 1 1 o-pounder .". u H M I e 20 iAO-lb shot 16 iio-pounder .. Flat-headed bolt, 200 Ibs. r .9 u u ll 2 M 60 I ai " u " r 22 1 20- pounder 20 140-lb. shot. Solid shot. J [I u M j? H " " 26 16 " The following rounds were fired at tho right side of the lower plate. 688 ORDNANCE. TABLE CXXIV. (CONTINUED.) Nature of Ordnance. Nature of Projectile. 27 68-pounder 16 r * 8 M 30 iio-oounder 14 c/j 31 3* ^ 33 iao-pounder ao 34 uo-pounder 14 35 o" 37 68-pounder 16 38 ^ 39 izo-pounder. Solid shot. 140-lb. shot. Solid shot. I40-lb. shot. 6. Struck the centre plate. 7. FRONT. Hit on the junction of centre and lower plates, and 1 ft. 5 in. from the port. Depth of indent, 1'2 in. ; diameter on lower plate, 4 in. 8. FRONT. Hit the plate T in. from the top, and 2 ft. from the port. Slight indent. 9. FRONT. Hit the plate 14 in. from the top, and 1 ft. 7 in. from the right side of the target. Slight indent. 10. FRONT. Hit the plate 8'5 in. from the top, and 1 ft. 9'5 in. from the right side. The 2d and 3d bolts from the right in the top row started, the latter 5 in. Indent, 1*25 in. ; diameter, 9 in. BACK. After rounds 6 to 10 inclusive. Two bolt-heads broken EXPERIMENTS AGAINST ARMOR. 689 off, but none gone in the bottom plate, where a sheet of vulcanized india-rubber intervenes. No other trace of injury. 11. FRONT. Hit the lower plate on the right side 1 ft. 11*5 in. from the port, and 8*5 in. from the top. Indent, 2 '05 in. A crack 16 in. long across the centre of the bulge. 12. FRONT. Hit the plate 3 in. from the top, and 2 ft. 11 in. from the port. Indent, 2*3 in. ; diameter, 8 in. A crack 10*25 in. long across the bulge. 13. Struck the centre plate. M. FRONT. Hit the plate 9 in. from the top, and 3 ft. 5 in. from the port on the top of a bolt which had previously been started. The bolt was drawn. Indent, 2'55 in. ; diameter, 6*5 in. A crack 7 '5 in. long extended from the bulge. 15. FRONT. Hit the plate 1 ft. 5 in. from the top, and 1 ft. 11 in. from the right side. Indent, 2'9 in.; diameter, 8 in. Slight crack across the centre of the bulge. BACK. After rounds 11 to 15 inclusive. Two ribs broken clean through. Five angle-irons broken. Skin fractured and forced out in pieces behind, along with parts of the india-rubber sheeting. One of the through-bolts had the head broken off. 16. FRONT. Did no apparent damage. BACK. Slight bulging of skin merely. 19, 20, 21. FRONT. Fired at left side of lower plate. Did no apparent damage. BACK. Did not fire together. Had no visible effect. 22, 23. FRONT. Hit left side of lower plate 1 ft. 9'5 in. from the bottom, and 3 ft. 10'5 in. from the left side. Depth of in- dent, 2'25 in.; diameter, 7 in. A crack across the bulge. One 110-pounder of this number struck the centre plate. 24, 25, 26. FRONT. These shot made a hole (triangular) with a base 1 ft. 7 in. long, and sides 1 ft. 10 in. long, on left side of lower plate. A wide crack extended from the bottom of the hole through some old shot marks to the bottom of the plate. 27. FRONT. Hit just below the hole made as above. Indent, 2 in. ; diameter, 9 in. 44 690 ORDNANCE. BACK. After rounds 22 to 27 inclusive. Huge fracture with hole. A large piece of solid plate driven through with other debris. Two ribs broken across. Skin bulged out, torn and bent up nearly at right angles. A through-bolt driven out with the rest. Solid timber support at foot of target cracked through. 28. FRONT. Hit on a rivet which was forced out. Indent, 2*3 in. ; diameter, in* 29. FRONT. Hit the plate 1 ft. 4 in. from the top, and 5 ft, 1 in. from the left side. Indent, 2*1 in. ; diameter, 9 in. 30. FRONT. Hit 6 in. from the top. Indent, 2.35 in. A crack extended from a bolt-hole to the top of the target. 31. FRONT. Hit 1 ft. 3 in. from the top. Indent, 2.05 in. 32. FRONT. Hit 1 ft. 8 in. from the top. Indent, 1-8. Two cracks across the bulge. 33. Missed the plate. BACK. After rounds 28 to 33 inclusive. One rivet was driven out but not broken. 14 in. of the backing of the skin broken off. One bolt with spun -yarn washer driven back and part of the washer destroyed, but the bolt apparently uninjured. Fired at right half of top plate. 34. FRONT. Made an indent 2'5 in. 35. 36, 37, 38. FRONT. Two shot struck on a rivet 6 in. from the bottom and drove it out. A huge crack extended to the bottom of the plate. 39. FRONT. Hit 1 ft. 5 in. from the bottom of the plate. Made an indent 2*1 in. ; diameter, 7 in. Huge crack across the butee. ' ? O O The lower plate had now buckled 1 in. on the right side, but the bolts were uninjured. The left side was buckled 1'25 in., but the rivets were uninjured. BACK. After rounds 34 to 39 inclusive. 18 in. of the backing of the skin was destroyed. One rib broken across, and 2 angle- irons. 84O. Experiments against 2-Ineli, 2'35-Iiirli, 3-Inch, and 4'5-Iiich Plates with 12-Pounder and 4O-Pounder, and against Ittr. Scott Russell's and Ulr Saimida's Targets with 4O-Pouiider, lOO-Pounder, and 15O-Pouiider, June 26, 162. (See Table 125.) EXPERIMENTS AGAINST ARMOR. 691 Plate A, 4 ft. 6 in. x 2 ft. 6 in. x 2 in. (Inferior iron badly rolled.) " B, 5 ft. x 3 ft. x a- 35 in. " C, 5 ft. 5 in. x 3 ft. x 3 in (Badly rolled.) " D, 6 ft. xs ft. X45 in. The plates rested against strong upright timbers, with sloping supports to the rear. Four powerful rivets, bolted through to the upright timbers, overlapped the edge of each plate. The plates were with- out backing of any kind. Service charges for the respective guns were used throughout the prac- tice. The 150-pounder was fired with 2A 4 powder. 841. MB. SCOTT RUSSELL'S TAR- GET, Figs. 381, 382 and 383 (29 ft. 10 in. x 9 ft. 9 in.) was composed of four rows of plates of the following widths, viz. : upper row, 1 ft. 1 Of in. ; second row, 1 ft. 9J in. ; third row. 1 ft. 8f in. ; and bottom row, 2 ft. 10i in. The plates (all of hammered iron) 4r in. thick, were supplied by the Admiralty, and had originally been made for the Warrior by the Thames Iron Company. The total thickness of the target was 8| in., made up as follows : a 4|-in. plate, a filling-in piece of 1 in., two 1-in. plates for backing, and two f-in. plates forming the skin. The construction of the target at the rear consisted of two longitudinal O stringers 5 '5 in. deep, one above, and the other below the port ; also two iron water-ways, representing the FIG. 381. Mr. Scott Eussell's target. Front view, in to 1 ft. 692 ORDNANCE. FlG. 382. upper and main decks. The vertical ribs were 10-5 in. deep and 21*25 in. apart; and, in order to represent the mode of construction with iron backing, as proposed by Mr. Scott Rus- sell, a lining of iron in. thick was placed on the upper part of the target (instead of 3 in. of teak lining of the Warrior target), the remainder of the target being left open, in order to allow of the examination of the skin. The object of the original experiment was to test Mr. Scott Russell's system of continuous rivet- ing, combined with iron backing instead of wood. Projecting riveting was used on one-half the target, and flush riveting on the other half. There were neither bolts nor rivets in any of the armor- plates, with the exception of the bottom one on the right side of the target, which had four rivets through its centre. The target had two portholes. 849. Mr. SAMUDA'S TARGET, (20 x 10 ft.), was composed of two plates, 20 x 3 ft. 4 in. x 5 in., and two centre plates, the one to the left of the porthole being 11' ft. 6 in. x 3 ft. 4 in. x 5 in., and the one to the right of the porthole, 6 ft, 8 in. x 3 ft, 4 in. x 5 in. The skin was 1 in. thick, and longitudinal ribs, 2i in. thick, were 383. Section of Mr. Scott Russell's target. Scale, in. to 1 ft. Section of Mr. Scott Russell's armor. placed at the junction of the plates, by which means the whole target was supposed to be of uniform strength. The upper and lower plates were secured by bolts, 14 in. apart, and the middle plates by alternate bolts and rivets. A thin layer of india-rubber was placed between the armor-plate and the skin and leather under the bolt-heads. EXPERIMENTS AGAINST ARMOR. 693 The target was supported by a framework of 14-in. timbers, 3 ft. 6 in. apart, strutted to the rear ; the feet of the struts being secured to timber piles. The total weight of the target (exclusive of the beams of the ship) was 27 tons 19 cwt. The armor-plates were rolled by Messrs. John Brown & Co., of Sheffield. EFFECTS. (Table 125.) 1. Ragged hole through plate, 2'3 in. x 2'5 in. ; diameter at back, 5'5 in. ; large crack 6 in. long in front below hole. Bend of plate 1*8 in. in length of 13 in. ; shot broke up small. 2. Clean hole through diameter, 3'8 in. x 3*6 in. No bend in plate ; shot broke up in large pieces. 3. Indent, *55 in. in length of 6 in. A 4-starred crack at the back. 4:. Ricocheted and hit low broadside. Shot broke up. 5. Indent, *875 in. in length of 11 in. Back starred with cracks and piece in centre of star cracked round. . 6. Hole through diameter, in front, 5'6 in. ; at back, 11 in. Bulge of plate, *45 in. in 1 ft. 7 in. Doubtful whether shot did not hit on old bolt-hole. 7. Struck above a bolt-hole. Indent, 1'6 in. in 1 ft. 6 in. At back, slight bulge and three cracks. 8. Struck top to the right near last shot. 9. Hit target 3 ft. 1 in. from right and 6 in. from top of lower plate. Hole through 12'75 in. in diameter, and plate broken away to the extent of 4 ft. 2*75 in. x 2 ft. 7*5 in. A crack 1 in. wide from top to bottom of plate, also a crack from a bolt-hole 1 ft. 8 in. from point struck, 2 ft. of rivet (or uniting railway iron) broken off. The plate abov* the one struck cracked right through. At the back, 1 vertical rib broken through ; pieces of skin driven into wooden hulk 38 in. to the rear; horizontal stringer also bent out 1/1 in. and cracked through. The shot fell back 5 yds. from the target. The " work done" upon the shot itself was considerable. The sphere was altered in figure so that the front and hind hemi- spheres were flattened (so to speak), and "set up" together, form- ing a sharp circular flange or rim. 694 ORDNANCE. TABLE CXXV. EXPERIMENTS AGAINST 2 -IN., 2'35-iN., 3 WITH 12-POUNDEB AND 40-POUNDER, AND AGAINST ME. AND MB. SAMUDA'S TARGET. JUNE 26, 1862. IN., AND 4'5-iN. PLATES SCOTT EUSSELL'S TARGET Projectile. CO 1 Nature of g CC 1 G g ^ a ^j (^ r ~^ >> _0 2 ^j "3 Target. || 2 3 | M c ff "cS 1 B i o to i . J 1 6 i M 1 1 1 Ibs. oz. in. / in. i A 2-in I2-pdr. rast- iron. ii 9 7 Service. i ? 200 nil. 10 R 2 M a steel. I 3 2 / 6-5 u * j a u i. ... 3 B. 2'35-in u cast iron. ii 9 7 u a a a 55 4 " " steel. I 3 2 6.5 a a a a it ... 5 wt. iron. 12 9 6.5 flat head. a a 3 tt 875 6 C -3-in 4O-pdr. cast iron. 41 8 I O 2 C ti c u O IO a 7 D 4 c-in... T W r ul c 4O-pdr. a T-A ** *J tf Service. j a a ?R 1.6 8 ^ r steel. 45 4 a round u 11 o 13 / ** loR headed. 9 Scott Russell's io^-in. wt. iron 162 8 10.372 sphere. 50 it nil. nil. ... Sm.-br. sphere. 10 [~* *9 in AO-pdr steel. AC 4 IO 2 C round c tt O IO <;R *r ^"-A* TO T 3 head. J j ** ii " a wt. iron. 43 o 9-25 flat head. a a tt a 5'75 I 2, C. vin... u cast iron. 4.1 8 io*ac Service. it ti tt a 8.5 13 B 2.35 12-pdr. *r ii 9 A W ^^ 7 a 1.8 400 o 30 I2R J 7.0 14 wt. iron. 12 9 6.5 flatheaded ti ti o 32 loR 1-05 '5 " a a a " a a o 33 i8R ... 16 T~) A r in 40-pdr. cast iron. 41 8 10.25 Service. 5 tt o 38 loR ... 17 a " " a " a o 35 3R ... 18 it steel. " 9.25 flatheaded tt a o 38 9 R 19 cc tt a M a a tt o 39 i R ... 20 U a 45 4 10-25 round a U 35 3R 1.85 headed. 21 " a a 43 o 9-25 flatheaded ' ; a o 38 1-15 22 Samuda's it steel. 45 4 10-25 round " 600 I 4 R 2.2 head. 23 it cast iron. 41 8 " Service. a U 1 3 8R .65 EXPERIMENTS AGAINST ARMOR. 695 TABLE CXXV. (CONTINUED.) | No. of Round. Nature of Target Nature of Ordnance. Projectile. 1 JS Q aj T3 a >> r he 1 Elevation. Deflection. +3 1 Nature. j f ,4 f 3 Samuda's 40-pdr. steel. Ibs. oz. 45 4 in. 10-25 round headed. 5 600 i 3 I2R in. 2.45 2 5 11 wt. iron. 43 9.25 flat headed u u u 65 26 Scott Russell's no-pr. cast iron. no 8 12-25 Service. H 200 o 24 loR 2-15 27 a u wt. iron. 116 8 11-25 flat headed " I2R 2.3 28 M it cast iron. no 8 12-25 Service. (i 400 o 42 8R ... 29 < u u u u u u u u loR 1-7 3 wt. iron. 117 I 11-25 flat headed a " o 44 i 3 R 2 3 H u cast iron. no 8 12-25 Service. " 600 i 6 8R ... 3* M a u a I0'25 a *r> 00 00 f-. VO Deflection. : : : : ^ s Elevation. : : : : ^ = ^ ? Thickness of Plate. " * : : : i 4 Eange in yards. rrnri I * 5 S ^ X 8 0^ Turn of Rifling. .S ^ s s ^ g * - M " " Windage on going in half sides. o cT , s ^ From angle to an gl e - ""to r> s 5 S S 42 H : : 00 , w 1? Weight rf M a oo o | 2 2 2 ! S ^o o -! : - M r^ O ON O S B o "2 J5 "o c/3 1 1 "** S 6 S o J3 6 ^r sS 2 C/} 1 1 1 | -3 *S cJ 1 " ' 1 1 5 T : C< ^^ O rl ^^ 3 S No. of Bound. o - M rt T^ ^- vr> EXPERIMENTS AGAINST ARMOR. 707 Bnrst after passing through backing. Plate 5 ft. 6 in. x 2 ft. 6 in. x 2 in., and 12 in. backing. "No. 1. (70-pounder). This gun was fired at a box-target made of 4 in. wood, with a 4-in. armor-plate (made at the Thames Iron Works) in front, backed by 9 in. of wood, and a 2-in. armor-plate in the rear (made at Portsmouth Dockyard) as a guard-plate, the interior space of the box being 36 x 40 in. One round with solid cast-iron shot was fired, in order to get the range ; it passed through a thin wooden target, and struck a damaged 5*5 in. plate (one be- longing to the Minotaur target) arid broke it in two. The first shell fired penetrated into the box-target, making a hole in the 4- in. armor-plate 5*6 x 5 -4 in., and exploded on the rear plate, blowing out the sides of the box, and forcing the front and rear plates outwards. The rear plate was deeply indented (viz. : 2-6 in.), but not penetrated. The shell broke into large pieces. No. 1, 2, 3. (120-pounder). SEPT. 25. Trial shot for range at wood-target 9 x 9 ft., indicating great precision in No. 1 and 2. No. 4. Fired at the Warrior target ; struck the centre plate 2*5 ft. from the left, and 1*5 ft. from the top; made a clean hole in the plate 8 in. x 8'5 in., the edge of the hole being 1 ft. 8 in. from the one made by the first shot from the Horsfall gun ; a narrow crack from one hole to the other ; the shot remained in the hole, having struck on a rib, the depth of the hole to the bot- tem of the shot being 13*5 in. ; no bulge on the plate ; one bolt in the centre plate started *4 in., and 2 bolts started in the upper plate. The centre plate had started out '3 in. at the top, and *1 in. at the bottom on the left side. At the back, one rib, which had been cracked by a shot from the Horsfall gun, was broken through, bulged out. and a length of 1 ft. 6 in. of it nearly de- tached ; the \vood backing splintered and broken ; the skin opened about 1/5 in. at the joint, and some additional bolt-heads broken off. No. 5. (120-pounder). Struck the centre plate 1 ft. from the bottom, and 1 ft. 4/5 in. from the right side; penetrated the target, making a hole 8*5 in. x 7*5 in. in the plate, and burst in passing through the backing ; two cracks on the plate, viz. : one 708 ORDNANCE. from the bottom of the hole to the bottom of the plate, and the other from a bolt-hole (1 ft. from impact) to the bottom of the plate ; two bolts in the centre plate started *5 in., and one in the lower plate '2 in. At the back, the diameter of the hole was 13 in., and portions of the shell, and the piece of iron punched out of the plate, were picked up inside the target ; some old oakum on the ground was on fire ; three bolt-heads and one rivet-head broken off just above the hole; the skin not injured except where penetrated ; the outer rib was broken through for a length of 4' 5 in. The timber backing much shattered, and driven out at the side 7 in. The shell burst into about 14 pieces. 846. Experiment with the Whitworth 12O-Po under, and 7O-Pounder, against 4i and 5-Ineh Plates, and the 12- Pounder against v> In< h Plates, November 13, 1862. A box-target measuring 12 ft. x 9 ft. 6 in., and having an interior space of 10 x 6 ft., was constructed for the experiment, and was composed of 3 armor-plates ; the upper one, which was 4'5 in. thick, had been used in the original Warrior target, and the centre one and lower one (each 5 in. thick) were taken from Mr. Samuda's target. The thickness of the backing and skin was the same as in the Warrior target. KESULTS. (Table 128.) No. 1. (120-pounder steel shell). Struck the middle plate 4 ft. 4-5 in. from the right side and 5'5 in. from the bottom, punched a hole in the plate 7'5 in. x 6 in. ; started 3 bolts in the lower row 1 in. each, and narrow cracks extended from 2 of these bolt-holes- to the bottom of the plate ; one bolt in the top row of the lower plate was also slightly started. The plate was driven in below the hole in. for a length of 12 in. At the top of the target, 3 of th filling-in pieces were blown out. The damage on the inside was as follows, viz. : a large irregular hole, inner diameter 10 in. ; skin of ship bent out with ragged rent, sticking out 10 in. ; general bulge, distributed over a surface of 3 ft. 5 in. x 3 ft. 5 in. The shell evidently burst between the front plate and the skin EXPERIMENTS AGAINST ARMOR. 709 Velocity at 780 yards. o OO ; O O t^ i -^ o t- ^ OO vo Length Cartridge. = 3 S a * - a * : i : 1 i Diam.of Indent. .2 : : r- : : : vo : vo : : : : : 1 Depth of Indent. vo w> a J *** I : : : ; vn oo to ; ; ; H M Deflection. J .-a .... Range in yards. O O O -oOSSS^O^SS 0^355 Elevation. v ^- vn ror-, ON^OOOONOO Bursting Charge of Shells. go oe fi o *d to ' "* ^ . sf . - * * SB ' ' " " XJ "J c"> w pQ pQ i Charge, Ibs. 53 "^ rt 11 oooo a ac acsffiK g BE Nature of Ordnance. JiJ x: N N vo r-~ EXPERIMENTS AGAINST ARMOR. 721 EFFECTS (Table 129.) No 1 (Whitworth 7-in. rifle). Struck 3 and 4 planks, 3 ft. 4 in. from the bottom ; 2 in. of indent was on plank No 3 ; the bulge on plank No. 3 measured 1*3 in. in depth, but the depth of indent on No. 4 could not be taken, as part of the shot remained in the indent; the edge of plank No. 3 was cracked in the bulge for a length of 1*5 in. ; a narrow crack on plank No. 4, at 1 ft. 5 in. from the point of impact, extending from a bolt-hole to the edge of the plank. At the back, slight bulge of 4 in. of horizontal plank at seat of blow; lead sheeting at left side of embrasure pressed out ; plank below the one struck gaping '5 in. from front plank at side of embrasure ; vertical frame-piece, to left of embra- sure, slightly curved back. No. 2 (100-pounder smooth-bore). Struck at 2 ft. 2 in. from bottom of target, and 5*5 in. from the side of the plank ; a bolt 8*5 in. from the point of impact started '3 in. ; the edge of No. 4 plank was bulged 2 in. x 1*5 in., and the edge of the plank was cracked on the bulge for a length of 5 in. At the back, the second through-bolt from the top of the left row, distant about 3 ft. from the point of impact, was broken ; the lead washers of No. 4 through-bolt, from the top of the same row, squeezed and broken, and angle-iron bulged out '5 in.; the lower horizontal plank, about 1 ft. beneath the blow, was cracked through vertically ; the left vertical frame-piece was slightly curved, and angle-iron at top set back from it. Major diameter of shot after firing 12'2 in. No 3 (300-pounder rifle). Struck No. 3 plank, 1 ft. 9 in. from the bottom ; the plank was cracked across its width through the indent ; the crack made by round No. 1 extended to a bolt-hole,, and the plank was cracked completely through its width and: thickness at 1 ft. 5-5 in. from the top, the crack being '4 in. wide on the front, and having extended from an old crack 4 in. long made by the previous day's firing; the plank was driven in 1*8 in. for 3 ft. 6 in. from the bottom ; the bottom bolt of the plank started -2 in. and the two bolts next above were driven in *2 in. and *4 in. At the back, a through-bolt, just below embrasure, 46 722 ORDNANCE. broken off; vertical frame-piece, or u upright of frame," bent con- siderably at seat of blow ; gaping of horizontal planks from front planks at left side of embrasure, increased now to an inch ; hori- zontal frame -piece or cross-stay, at bottom curved back considera- bly ; a through-bolt (mashed by the above frame-piece) broken, and its head brought up pressing against the frame-piece ; washers of No. 2 through-bolt from the top of right row squeezed up ; bottom through-bolt, right side, loose, being broken in front ; vertical frame-piece, right of all, slightly curved ; and a partial crack (former day's practice) now continued through the thickness of iron. No. 4 (T-in. rifle). Struck No. 1 plank, 4 ft. 7 in. from the bot- tom, and 5 in. from the side; plank driven in 1/8 in. at point of impact, and the edge of plank No. 2 bulged 1 in. in a length of 10 in. ; the plank cracked diagonally across its width through a bolt- hole at 1 ft. 2 in. above the point of impact ; also from a bolt-hole to right side of the plank at 1 ft. 5*5 in. below the point of impact; a crack 15 in. long also extended from the left side of the plank at 2 ft. 7 in. below the point of impact. The shot set up 6*5 in. No. 5 (Whitworth 7-in. rifle). Struck the plate below embra- sure, 1 ft. 8 in. from the top, and 10 in. from the left side, which was driven in -8 in. on the right side, and 1*1 in. on left side ; the shot broke up and a portion remained in indent, the depth of which could therefore not be taken ; the bottom bolt started 1 in., and a crack, made by previous firing on plank No. 2, opened to 3 in. At the back, a through-bolt 2 ft. 6 in. from the point of impact, driven out; whole of bottom of embrasure set back, opening between front and rear planks *5 in. ; a slight irregular- starred crack on lower horizontal plank ; lower horizontal frame- piece rather more bulged back. No. 6 (300-pounder rifle). Struck at the junction of planks 3 and 4, 3 ft. 2 in. from the top of the target ; a portion of the shot remained in plank 3 ; the cracks at the top and bottom of this plank made by round No. 3 much enlarged, and now measure *6 in. and -9 in. in width. At the back, a through-bolt (second from the top of tli third row from the left) broken ; through-bolt, top EXPERIMENTS AGAINST ARMOR. 723 of second row from left, much squeezed up ; vertical frame-piece considerably bulged (now 1*2 in.) ; horizontal planks 2, 3, and 4 from top also bulged ; 3 and 4 horizontal planks opening out from front planks 1 in. at left side of embrasure. No. 7 (L. Thomas's 7-in. rifle). The gun burst and the shot did not strike the target. 854:. Experiments on Millboard a a Backing to Armor- Plates. Sept. 8, 1S62. A piece of millboard 1 ft. 3 in. x 1 ft. 8 -5 in. x 8 in., was secured in rear of an iron plate *9 thick, the millboard resting against a 2|- in. plate backed by granite. The gun used was a 6-pounder Armstrong rifled gun, with solid cast-iron shot and service charge, at 50 yards range. No. 1 Round. Struck the '9-in. plate at a spot above where it was backed by the millboard, made a clean hole 2 -9 in. diame- ter through the plate, and the shot broke up. No. 2 Round. Struck the plate where backed ; shot penetrated 3-9 in., and remained in the hole unbroken. The millboard was slightly forced out at the side, owing to its small area. No. 3 Round. Hit the plate at a spot 1 in. below the top of the millboard; 2 in. of the rear of the shot broken off, the re- mainder stuck in the hole, having penetrated 2-5 in. into the mill- board. (A piece of teak 7'9 in. thick was now put in rear of the '9-in. plate just above the millboard, and resting against the 2-J-in. plate and granite backing. The 6-pounder Armstrong gun was used at the same range.) No. 4 Round. The shot struck fair on the plate and wood, passed clean through both and remained whole in the wood, which was split in half. The shot penetrated to the 2-J-in. plate. The penetration into the millboard of a flat-fronted shot, weigh- ing 5^ oz., fired from a wall-piece at 25 yards, with a charge of 10 drs., was 2*76 in. Nov. 14. A block of millboard* measuring 4 ft. *75 in. x 3 ft. * This block of millboard was supplied by Mr. Morris, of Glasgow, on his own pro- posal, but was not at all suited for the purpose intended, consisting merely of sheets 724 ORDNANCE. 1-5 in. x 1 ft. 2-5 in., and weighing 6 cwt, 12| Ibs., was tested in comparison with teak of the same weight, and measuring 4 ft. 75 in. x 3 ft. 1'25 in. x 1 ft. 2 in. Each block was faced with a 1-in. iron plate, the whole being secured at the sides ; by means of clamps, to avoid through-bolting. The guns used were : One 6-pounder Armstrong gun at 50 yards. One 12-pounder do. at 100 yards. No. 1 Round. 6-pounder solid shot at millboard. Struck 1 ft. 4 in. from the top, and 1 ft. 6 in. from the side; penetrated 3 in. into the millboard, the shot remaining unbroken. The plate buckled *95 in. over a space measuring 17 in. x 6 in. No. 2 Round. 6-pounder solid shot at teak Struck 1 ft. 3 in. from the top. Shot penetrated completely and broke up. The balk of timber on which it struck was cracked through its thick- ness ; very slight buckle of plate. No. 3 Round. 12-pounder solid shot at millboard. Struck the plate at 1 ft. 2 in. from the top, and penetrated to a depth of 1 ft. 7 in., being 3 in. into some wood in rear. Left a clean hole through the millboard of 3'1 in. No. 4 Round. 12-pounder solid shot at teak. Struck at 1 ft. 3 in. from the top of the plate, made a hole 3*3 in. diameter, and penetrated the wood, which it split through its thickness at the top ; the hole closed up. No. 5 Round. 6-pounder solid shot at millboard. Struck at 6*5 in. from the top, and penetrated the millboard to a depth of 2*65 in., the fore-part of the shot remained in the hole, the re- mainder being broken off. The plate buckled '9 in. for a space of 14 in. x 12 in. No. 6 Round. 6-pounder solid shot at teak. Struck at 1 ft, from the top, and penetrated 6 in. into the teak. The wood was split through as in previous rounds ; very slight buckling of plate. The shot did not break up. 855. Experiments against Hodge's Wire- Target, May 7, of brown paper laid together and bound by hoops of iron, and when these latter were removed, the sheets of paper were found to be quite disconnected. EXPERIMENTS AGAINST ARMOR. 725 1862. (See Table 130.) " The front of the target consists of three thicknesses of ^-in. plate iron ; then comes a tissue of wire ropes 14 in. thick. Tl^e target is mounted on timber 9 in. thick, con- FiG. 386. FlG. 385. Section of wire target. Front of wire target after two 11 -in. shot. sisting, 1st, of two 1-in. boards (one horizontal and one vertical), and then of two layers of timber 3^ in. thick, disposed vertically and horizontally. TABLE CXXX. EXPERIMENTS AGAINST WIRE TARGET. 1 | 1 c a O 1 a 00 l c cf 3 1 1 a| o *r 'o j Q % f m 1 jg |l X & o q 1 P P II. M. 10 I 1$ 156 106 7 II 28 83 102 7.OO 15 165 10! 6 ii 39 83 " Dimensions of target : Length, 67^ in. ; width, 50^ in. ; iron, thickness, 15 J in. ; timber, 9 in. 726 ORDNANCE. "Gun, 11 in., No. 214, C. A. & Co., mounted on a wooden pivot-carriage, in front of battery. Charges: cannon powder, 1862. Projectiles : 1st, one wrought-iron, and 2d, one cast-iron solid shot. Friction primers. " 1st shot hit direct, passing clean through the target into the bank ; penetration not determined. " 2d shot hit direct, passing clean through the plates, and pene- trating the bank a distance of 9 ft. 6 in."* 856. Experiments agaiiit Laminated Iron inclined 15' from Line of Fire and backed by India-Rubber and Timber, Sept. 4, 1862. (See Table 131.) " This target was made of two FIG. 387. Front of laminated target, after two 11-in. shot. thicknesses of -J-in. boiler-iron put on in 4 plates, backed by 1 in. rubber and 7 in. yellow pine and 3 beams, running lengthwise of * Official: From Scientific American, Dec. 19, 1863. EXPERIMENTS AGAINST ARMOR. 727 the target. The rubber was placed between the plates and timber ; all bolted together with eighteen 1J in. bolts, and the target set up firmly against a bank of clay, at an angle of 15. FIG. 388 Back view of Fig. 387. " Dimensions of target : Iron plates, 8 ft. long, 6 ft. 8 in. wide, and 1 in. thick ; rubber, 1 in. thick ; timber, 7 in. thick ; beams, 1 ft. square. Gun 11 in., No. 214. Charges of camion powder, 1862. Projectiles, Cloverdale cast-iron solid shot. Primers, fric- tion tubes. " The 1st shot struck the plates 3 ft. 3 in. from the right-hand edge, and 12 in. from the lower edge, tearing through the plates, rubber, and timber, making a hole 3 ft. 8 in. long, and mean width 8f in. ; the shot passed off and penetrated the bank 11J ft. from the outer surface. Angle of shot after leaving the target was 9. The plate is indented at the right edge of shot-hole, in. ; at left edge, 1 in. ; at top edge, f in. ; at lower edge, 1 in. 728 ORDNANCE. TABLE CXXXI. EXPERIMENTS AGAINST LAMINATED TARGET. "c d 1 i 00 I 5j| a O ^ !* c J 1 * 2 &> ft" 1 = - a "S f fc 1 6 V 3 01 1 | H. M. 149 i 3 o 1 68 106 Taut breeching. 74 3 I S I 5 i 3 o 169 106 74 3 3 1 " The 2d shot struck the plates on the crack between the plates and 2J- feet from the right edge, tearing through the plates, rub- ber, timber, and a portion of the beam, making a hole 4 ft. long, and mean width 10 in. This shot forced the lower plates from the upper ones 3 in. on the left edge, and over 1J in. on the right edge of the shot-hole. The shot passed off and penetrated the bank 15 ft. Angle of shot, after leaving the target, 9. The plate is indented on the right edge of the hole 1^ in. ; on the left edge, 1 in. ; on the top edge, j- in. ; on the lower edge, If in. The plates are cracked from the lower edge of the shot-hole ~No. 2 to the lower edge of shot-hole "No. 1. The bolts appear to be in good condition on the face of the target, but it is impossible to ascertain if any are broken in the rear until the target is taken down.* 857. Experiments agaiiit Laminated Iron inclined 15 from Line of Fire and baeked by India-Rubber and Pine, Sept. 16, 1862. (See Table 132.) " This target was made of two thicknesses of 1-in. wrought-iron plates, backed by If in. of rubber, 7 in. of yellow pine, and 3 beams, 12 in. square, running lengthwise of the target. The outer layer of plate consisted of three plates placed horizontally, and the inner layer of two plates placed perpendicularly. The rubber was placed between the plates and timber. It not being as large as the plates, a margin of about 1 ft. was left which was filled in with pine planks, the Official: From Scientific American, Dec. 26, 1863. EXPERIMENTS AGAINST ARMOR. 729 whole being joined together with thirty-two IJ-in. bolts. The target was placed against a solid bank of clay, with planks in its rear to keep the clay clear of the timber. Angle of inci- dence, 15. " Dimensions : Plates, 8 ft. long, 6 ft. 8 in. wide, 2 in. thick. Eubber, If in. thick. Timber, 7 in. Beams, 12 in. square. Gun, 11 in., No. 214. Charges of cannon powder, 1862. Projectiles, Oloverdale cast-iron solid shot. Primers, friction tubes. TABLE CXXXII. EXPERIMENTS AGAINST INCLINED IRON AND RUBBER TARGET. 1 $ f 1 1 Jon, inches. _- l ^2 a-r alp o 3 4 1 J S I* fe to Q F S 1 P ft 54 i 3 169 107 Taut breeching. H. M. 3 74 "/The shot struck the target 24 in. from the right edge of centre plate, tearing through the plate and rubber, and breaking the timber and beam, making a hole 2 ft. 8-| in. in length, and 7-J- in. mean width. Extreme depth of hole, 9 in. The shot passed off and penetrated the bank 15 ft. Angle of shot, after leaving the target, 9. The plates are indented at top edge of shot-hole 4 in. ; at lower edge, 3 in. ; at right-hand edge, If in. ; at left-hand edge, 1^ in. The shot has a small piece broken out."* 858. Experiments against Laminated Iron inclined 15 from Line of Fire and backed by India- Rubber and Pine, Nov. 5, 1862. (See Table 133)." The target was made of two 1-in. plates (wrought-iron), backed by two 1-in. plates of rubber, 7 in. of yellow pine, and 3 beams running lengthwise the target. The rubber was placed between the plates and timber, and the whole joined together with ten IJ-in. bolts. The target was placed against a solid bank of clay, with timbers in its rear to keep the earth clear of the target. Angle of incidence, 15. * Official: From Scientific American, Jan. 9, 1864. 30 ORDNANCE. " Dimensions : Plates, 8 ft. long, 4 ft. wide, 2 in. thick. Rub- ber, 2 in. thick. Beams, 12 in. square. Timber, 7 in. thick. Gun, 11 in., No. 214. Charges of cannon-powder, 1862. Pro- jectile, solid Cloverdale cast-iron shot. TABLE CXXXIII. EXPERIMENTS AGAINST INCLINED IRON AND EUBBER TARGET. g , d J | fi H >> ! . 1 c 3 g C3 *& -1 o c^ 2 *"* & 3 tf f 8"" 1 S) ^ . cS ' OD s " fc fe a s p s II. M. 55 i 3 o 164 107 II 9 5 1 74.9 I 5 6 a 3 168 ... Taut breeching. 10 12 74-9 " The first shot struck the target 11 in. from lower edge and 30 in. from top edge of plates, tearing through the plates, rubber, and timber, and breaking the lower beam, making a hole 28 in. long and 6-8 in. mean width. Shot passed off and penetrated the bank 16 ft. Angle of shot, after leaving the target, 10. The plate is indented at top edge of shot-hole, f in. ; at lower edge, 1^ in. ; at right edge, If in. ; at left edge, 1 J in. The shot broke into pieces, one of which was found in the bank (weight, 52 Ibs.) u The second shot struck the target on the right edge of the plates, and 12 in. from the top, tearing through the plates, rub- ber, and timber, making a hole 31 -J in. in length and 10*7 in. mean width. The shot passed off and penetrated the bank 18 ft. Angle of shot after leaving the target, 15. The plates are very much bent on the right-hand side, and the timber badly shattered. The cause of this shot striking the edge was occasioned bj an error being made in sighting the gun from a point on the timber and not allowing 4 in. for thickness of plates and rubber.""* 85O. Experiments against 4V-Iiic'h Solid Plate backed by Iiidia-Rubber and Oak, July 26, 1862 (See Table 134.) " This target was made in the Washington Navy Yard, of scrap- * Official: From Scientific American, Jan. 9, 1864. EXPERIMENTS AGAINST ARMOK. 731 iron, 4^ in. thick, backed by 1 in. rubber, 20 in. oak, and a 1-in. wrought-iron plate, all joined together by six IJ-in. bolts, and clamped on the top and bottom with wrought-iron clamps, and set up firmly against a clay-bank, with timber in the rear to pre- vent it from being forced into the bank. " Dimensions of plates : 8 ft. 3 in. long, 4 ft. 2 in. wide, 4^- in. thick. Gun, 11 in. ; charges, cannon powder, 1862. Projectiles, Cloverdale cast-iron solid shot. Primers, friction tubes. TABLE CXXXIV". EXPERIMENTS AGAINST SOLED 4^-lNOH PLATE WITH RUBBER AND OAK BACKING. d rf d 3 1 1 1 o % 1 a 1 Is i O X .cl ' ' +3 j* a ^ vl 1 i I O to S I 8 1 _g 5 1 II. M. 9 i 3 I6 7 ... 3 88. 3 ii 45 140 2 3 1 68 " i 23 " First shot at plate struck the plate 20 in. from the left side of the target, and 18 in. from the right side, throwing the target for- ward on its face. After a delay of about 1J hours, the target was placed in its former position. The ball entered the plate and passed through the rubber, and lies embedded in the plate and first course of timber, with its rear level with the outer surface of the plate. The plate is indented on the right side of the hole, 1J in. ; on the left edge, f - in. ; top edge, 1-J- in. ; lower edge, 1 J in. ; The plate is not bent on the right edge of the target ; on left edge, J in. The plate is not cracked excepting directly around the shot-hole, which is cracked very slightly. The bolts are all broken in the rear of the target, but on the face of the plate they appear to be good. The last two courses of timber are broken at the centre from right to left edges of the target, and have sprung back from the first course 3 in. on the right edge and 2^ in. on the left edge. The first course of timber is somewhat shattered and thrown out on both sides of the target : right side, 2 J in. ; left side, 5 in. Diameter of shot-hole, 12 in. 732 ORDNANCE. " The 2d shot struck the plate 17^ in. from right and left edges, and 10^ in. from shot-hole No. 1. The shot threw the plate on its face as before, which occasioned a delay of two hours before it was placed in its proper position. The shot broke into pieces, which fell out when the target was thrown down, excepting a small portion which remained in the hole. This shot passed through the plate, rubber, and first course of timber, and entered the second course, making a hole 16 x 30J in. in diameter. The extreme depth of hole is 14 in. The plate is indented on the right edge of the hole, 1 in. ; on the left edge, f in. ; on the top edge, 1 in. ; on the lower edge, 1 in. The plate is bent on the right side of the target, -J in. ; on the left side, in. Opposite the centre of the shot-hole No. 2, the timber (first course) has sprung out on the right side 5 in. ; on the left side, G in. The back plate is forced back from the timber 3 in. at the centre. The top clamp was broken in two places. No cracks are visible about the plate, excepting those already mentioned. The rubber- plate was furnished by Mr. Bennett, of New York, last May, for trial, as above. Dimensions, as follows : 8 ft. long, 4 ft. wide, 1 in. thick." 86O. CONTINUATION OF EXPERIMENTS AGAINST 4^-lNCH PLATE BACKED WITH B-UBBER AND TlMBER, JULY 28, 1862. SAME GuN AND CHARGE. " Third shot at target struck the plate 18f in. from right side of target, and 1QJ- in. from the left side, and 5^ in. from lower edge of shot-hole No. 1, passing through the plate, rubber, and first course of timber. The shot broke into pieces, several of which were thrown in the rear of the battery, and several were lying in front of the target. The main body of the shot remains in the hole, with its rear 9| in. from the outer surface of the plate. The plate is indented on the top edge of the shot-hole, in. ; on the lower edge, -J in. ; on the right edge, f in. ; on the left edge, f in. The plate is bent on the right side 1^ in. ; on the left side, If in. In the right side of the shot-hole No. 2, the plate is cracked froi i the edge of the hole, 13 in. ; on the left side there is also one, extending 10 in. from the edge of the hole. Between the shot- holes No. 1 and No. 2, there is a crack from edge to edge of the EXPERIMENTS AGAINST ARMOR. 733 Fia. 389. holes ; and between shot-holes No. 1 and No. 3, there is a piece broken out measuring 2f in. at the top and 5f- in. at the bottom. On the right edge of the plate is also a small crack. The lower clamp is broken. The first course of timber is completely broken up and thrown out at the sides ; the second course is somewhat broken. The target was forced out 7 in. from its position ; it being secured by a rope, leading from a tree in the rear, prevented its falling on its face as before."* 861. Experiments against 8-Inch Plate and Target of Bars ; Parrott lO-Inch Rifle, Feb. 9, 1863. In this experi- ment, conducted at the "West Point Foundry, the plate was made of soft hammered scrap- iron, 6 ft. 4 in. long, 2 ft. 6J in. wide, and 8 in. thick, well sup- ported at the rear, but without backing. At 100 yards range, a 232-lb. cast-iron shot, with chilled head (589), fired with 28 Ibs. of powder, broke the plate as shown at Fig. 389, and indented it 1 in., and bulged it 1 in., as shown at Fig. 390. 86S. The same gun was then fired at a target 5^ ft. 8-in. solid plate Parrott 10-in. rifle. square (Fig. 391), composed of 3 layers of bars, T-& in. in aggregate thickness, backed and bolted to 15J in. of oak. Weight of shot, 232 Ibs. ; charge, 28 Ibs. ; range, 100 yards. The result is shown by Fig. * Official: From Scientific American, Dec. 26, 1863. 734 ORDNANCE. 392. Of the 25 bolts, 23 were broken out. The indentation was llf in. 863. Iron-Clad Atlanta; 15-Inch Ball. In 1863, a 15 in. ball from the " Monitor" Weehawken smashed in, at about 300 yards range, the armor of the Confederate iron-clad Atlanta (Fig. 393), and completely disabled her. An 11-in. 169-lb. ball, with 20 Ibs. of powder, did not break through the same armor. The casemate of the Atlanta was inclined 35 from the horizon, and was composed of laminated armor of the aggregate thickness of 4J in., backed by 2-J ft. of yellow pine, as shown. 864. Experiments against lO-Inch Solid and Laminated Target; 15 and 11-Inch Guns, 1863. In the Spring of 1863, 1/ttlitr Section of Fig. 389 at point of impact. at the Washington Navy Yard, a 15-in. spherical shot, weighing 4:00 Ibs., was fired, at 200 yards range, with 40 Ibs. of powder, at a target (Figs. 394, 395, and 396), composed of a 4^-in. plate 3 ft wide, and 15 ft. high, backed with 5 in. of I'l-in. plates (10 in. of iron in all), and 20 in. of oak. A disk was broken out of the 4rJ-in. plate (&, Fig. 395), and the thin plates were indented, but not broken. The wood was a little crushed; but the shock was so great that nearly all the bolts were jerked out or broken, and the plate was ready to be dislodged and thrown off by a slight additional vibration. 865. In 1863, an 11-in. spherical cast-iron 169-lb. shot was fired at the foregoing target, at 200 yards range, with 30 Ibs. of powder. A disk (Fig. 397) was broken out of the 4^-m. plate (c, Fig. 395), leaving an indentation 3^ in. deep ; and about half the bolts were broken, and some of them were thrown out. 866. Experiments against 14-Inch Target; 11-Inch Gun, EXPERIMENTS AGAINST ARMOR. 735 1863. Early in 1863, an 11-in. 169-lb. spherical cast-iron shot was fired, at about 50 yards range, with 30 Ibs. of powder, at a target (Fig. 398) 14 in. thick, and about 7 ft. square, composed, where the shot struck it, of six 1-in. plates, one 4-in. plate, and four 1-in. plates without wood backing. The target was planted against a heavy timber frame- work, which abutted against the cap-stones of a sea-wall. FIG. 391. Target of bars. Parrott 10-in. rifle. Section of Fig. 391 after firing. The blow of the shot produced a small local effect. The inden- tation was about 5 in. ; the outer 1-in. plate w^as cracked across, and the back plates were bulged 2 or 3 in. ; but the whole target and frame-work, and the earth and the sea-wall behind it, were shoved bodily backwards several inches. Nearly all the through-bolts, some 40 in number, were loosened, and some of them were broken off in the thread of the screw at the rear. 736 ORDNANCE. 867. Experiments against Laminated Armor; lO-Inch Oun, 1863. At the Washington Navy Yard, in the spring of FIG. 393. Cross-section of the Confederate iron-clad Atlanta. 1863, a 10-in. 130-lb. cast-iron spherical shot was fired with 43 Ibs. of powder ; range, 200 yards ; through a target composed of 6 plates, making an aggregate thickness of 6J in., backed by 18 in. of oak. The target was the same as that used with the 15-in. shot FIG. 394. FIG. 395. o -o- D O Side of 10-in. target for 15-in. gun. Scale, j'g in to 1 ft. Front of 10-in. target. (864), except that the outer 4^-in. plate was removed. The shot made a clean breach (Fig. 399), and passed some 100 yards to the rear. 868. Experiments against 41-Inch Pato, 1863. A 4- in. plate 9SJ in. long, and 48 in. wide, backed with 20 in. of white- oak, and a 1-in. skin, was set against a bank of earth, and knocked to pieces (as shown Fig. 400) by the following shot, viz. : 1 cored cast-iron spherical 11-in. 163-lb. shot, 30 Ibs. powder. EXPERIMENTS AGAINST ARMOR. 737 PiG. 396. 1 steel flat-fronted 40'7-lb. shot, 8 Ibs. powder. 1 spherical wrought-iron 53-lb. shot, 17 Ibs. powder. 1 solid cast-iron spherical 11-in. 169-lb. shot, 30 Ibs. powder. 869. Experiments against Nashua 4i-Inch Plate ; 11-Ineh aims, 1863. The Nashua Iron Works forged plate (Fig. 401), upon which this experiment was made, was 40 in. wide, 4|- in. thick, and 16 ft. long. It was backed with 20 in. of oak, and a 1-in. iron skin. At the range of 30 yards, three 11-in. 169-lb. spherical cast-iron balls, and three 186-lb. wrought-iron balls were fired in the order marked on the engraving, with 30 Ibs. of powder. The plate was considerably bulged and cracked, and was broken to pieces at one end by the 5th shot. No breach was Section of 10-m. target. made through the entire target. 870. Experiments on 51, 6i, and 74-Inch Plates Rolled by Messrs. John Brown & Co., March 17, 1863. The plates were of the following dimensions and weights : No. 1. 13 ft. 4 in. x 3 ft. 6f in. x 5J in. No. 2. 12 ft. 2J in. x 3 ft. 7f in. x 6J in. No. 3. 11 ft. 9J in. x 3 ft. 8f in. x 7| in. FIG. 397. cwt. 93 103 116 qrs. 1 2 2 Ibs. 6 10 FIG. 398. 14-in. target 11-in. ball. 738 ORDNANCE. FIG. 399. They were secured by 2J in. conical-headed bolts, with double nuts, to the frame of Mr. Samuda's target (2J- in. thick), and were backed by timber for one-half their length. The 5f-in. plate by 9 in., the 6-J-in. plate by 8 in., and the T^-in. plate by 7 in., so that the front of the target presented a plane surface ; India- rubber washers were placed under the bolt-heads. The plates were divided into com- partments by seven vertical lines numbered from 1 to 7, and by three horizontal lines ; the backed portion of the plate extending from 1 to 4, and the unbacked portion from 4to 7. The guns used in the experiment were : One 300-pounder Armstrong muz- zle-loading shunt gun. One Lynall Thomas's 9-in. gun. One Whit worth 130-pounder muz- zle-loading rifled gun. One 110-pounder Armstrong breech-loading rifled gun. One 68-pounder smooth-bore, 95 cwt. EEMABKS. (See Table 135.) No. 1 (68-pounder). Struck the 5'5-in. plate, 9 in. to the right of 3 vertical and 11 in. below 2 horizon tal ; the plate driven in at the bot- tom '4: in. in a length of 2 ft. No. 2 (68-pounder). Struck the 7'5-in. plate, 3 in. to the left of 5 vertical and 8 in. below 2 horizontal. No. 3 (68-pounder). Struck the 6'5-in. plate, 6 in. to the left of 4 vertical and 3 in. below 2 horizontal. At the back, after these three rounds, one nut-head off the top right of target, and the lead and India-rubber washers of two through-bolts squeezed up. Section of G^-in. laminated target. EXPERIMENTS AGAINST ARMOR. 739 No. 4 (110-pounder). Struck the 5'5-in. plate, 4 in. to the right of 6 vertical and 3 '5 in. above 2 horizontal ; a bolt, 14 in. from impact, started '3 in., and a narrow crack, 8 in. long, on indent. No. 5 (110-pounder). Struck the 6*5-in. plate, 3 in. to the right of 6 vertical and 5 in. above 2 horizontal. No. 6 (110-pounder). Struck the 7*5-in. plate, 6 in. to the left of 6 vertical and 8 in. above 2 horizontal. At the back, after FIG. 400. 4^-in. Dahlgren target. No. 5. rounds 4, 5, and 6, two rivet-heads off; a bulge and lateral crack across it on the 5'5-in plate; the backs of the 6'5-in. and 7'5-in. plates, where struck, could not be seen. No. 7 (300-pounder). Struck the 7'5-in. plate, 8 in. to the left of 4 vertical and 7'5 in. above 2 horizontal, on a rib ; the top of the plate was driven in 1-3 in. in a length of 7 ft. ; bolt above 740 ORDNANCE. I I i CO t k N M M Remaining Velo- city. : : : : : : *"> : : : : : : ON M M l-l Diameter of Indent in inches. ON T" x ^ <* . ^ OS ^ ON oo X ON H : U^ M 00 Depth of Indent in inches. M ^ ~- ON O NO rt Deflection. ns fc ON <*- Range in yards. 8 3 , s s s - Elevation. ^rt"*"" w **.*< N Charge in Ibs. --, 3 ' = * ' Bursting charge of Shells. M Length. i i : ; i : * o I 1 S-s & u s " 1) U ^ 1 1 J1 Weight O M 1 NO" A - " - O 00 NO CO H "S fe ."2 S cT 1 o S V3 w O _C *^ *OJ C/5 C/3 d a O 3 1 1 00 NO ij f v" ir" ;V l ' :"" 8 No. of Round. M H ro ^. ^ NO t, oo EXPERIMENTS AGAINST ARMOR. 741 %$- VO "*3 00 ^ 1* ^ S ON o S ^2 : : oo to <^ * - o 1 8 , 5 , = ? */"> O O O p ta vrt o O -. ui ! 2 : . . . M M M OO M I S H "S 5i 1 . -o- r fe - * ^ ^ - a S 2 S -1 I! S 1 . -i;S .S -^ -5 p .a '-3 g. . e rt 1 & j[ ^- c* rC ~S J S) c d 8 8 2 a * 6 ^ IH M ft H P. M. 167 I 3 1 68 IO S Taut breech. 90-2 4-8 ing off of many rivets and through-bolts, and the breaking through of the plates when struck on their edges. A 150-lb. shot, with 50 Ibs. powder, from the 10-J-in. gun, and a 300-lb. live steel shell, loaded with 15 Ibs. bursting charge, and fired with 35 Ibs. of pow- der, went entirely through and beyond the thickest part of the target. 876. Experiment against I'-Im-h Solid Plate faced \viili 12 Inches of Oak and backed wit It 2O Inches of Oak, Hay 28, 163. " This target was made of one 4^-in. scrap-iron pliate,, backed by 20 in. of solid oak, and faced with 12 in. oak, on the plan of Mr. Heaton. The plate was joined to the rear timber with four wood screw-bolts, and the facing timber was secured to the rear timbers with six square-headed bolts with nuts. The target was placed against a bank of solid clay. " Dimensions of target : Plate, 4 ft. long, 4 ft. wide, 4 in. thick. Rear timber, 20 in. ; facing timber, 12 in. thick. Gun, No. 214, 48 754 ORDNANCE. A. F. Charges, cannon powder. Projectiles, solid cast-iron shot | Cloverdale iron and ^ Hopkins's iron. " Shot struck 16 in. from top edge, 17 in. from lower edge, and 16 J in. from right and left edges of target, passing clear through the facing timber, plate, and rear timber, and embedding itself 3 ft. 6 in. in the bank in rear of target. Diameter of hole in iron, in. FIG. 404. Front of 4-in. plate, with 12-in. oak facing, after one 11-inch shot. " The top and middle courses of facing timber were completely shattered, and the whole top course and a portion of the middle course carried away ; the bottom course was somewhat fractured ; two of the timbers were thrown forward, and fell 30 ft. in front of target. One piece of iron plate was found 102 ft. in front of target. " One bolt on the top left side of target had its head broken off, and the top right bolt had its nut broken off in rear and was forced out in front. None of the wood screw-bolts were broken nor started from the surface of the plate. Indentation of plate on top edge of shot-hole, % in. ; on lower edge, J in. ; on right edge, EXPERIMENTS AGAINST ARMOR. 755 FIG. 405. f in. ; and on left edge, in. The shot was considerably frac- tured and flattened on its forward face, but retained its spherical form until it was taken from the bank."* 877. Experiments against Target of Sandwiched Iron and Rubber as compared with same Plates of Sandwiched Iron without Rubber, Oct. 3, 1863. "This target was made of four 1-in. wrought-iron plates and four sheets of rubber 1 in. thick, backed by 20 in. of solid oak and joined with six IJ-in. wrought-iron bolts and nuts. The plates, rubber, and bolts were furnished by Mr. G-. L. Jones, of St. Louis, Mo. The first 4 in. nearest the tim- ber were composed of alter- nate layers of rubber and iron, and then two sheets of 1-in. rubber and two 1-in. wrought- iron plates, the latter being on the outer surface of the target. The target was placed against a bank of solid clay. " Dimensions of target : Length, 96 in. ; width, 42 in. ; thickness of rubber and plates, 8 in.; thickness of timber, 20 in. Gun, 11 in. No. 214 C. A. & Co., mounted Section of Fig. 404. . . . on wooden pivot carriage in front of the battery. Charge, cannon-powder ; projectiles, Clover- dale cast iron ; primers, friction." Hange, 84 ft. ; weight of ball, 169 Ibs. ; charge, 30 Ibs. " This shot struck 20 in. from the right edge, and 28 in. from the lower edge of the target, passing entirely through the plates, * Official : Scientific American, Jan. 30, 1864. 756 ORDNANCE. rubber, and timber, and penetrating the bank a distance of 12 ft. Diameter of shot-hole, 11J in. The timber in rear of the target, around the shot-hole, is much broken. The plates are sprung out- ward directly around the shot-hole 1 in. All the bolts were slightly started, but none broken." " On the 6th inst., the target having been placed on its longest edge, at an angle of 45 with the line of fire, another shot was fired at it from the same gun, and under the same conditions, and with results as follows: This shot struck 15 in. from the top and bottom edges and 37 in. from the left edge of the target, passing entirely through plates, rubber, and timber, and penetrating the bank a distance of 6 ft. The shot appears to have been broken in its passage through the target, as several small pieces were taken out of the shot-hole, and one small piece was found in the rear of the target on the bank. Horizontal diameter of shot-hole, 18J in. ; vertical, 12 J in. The plates were sprung inward on the right edge of the shot-hole, in. ; and on the left edge, f in. The plates have sprung forward on the right and left edges of the target ^ in. The timber in the rear of the target is completely shattered. ~No bolts were broken, but all were more or less started from the surface of the plates." 878. LAMINATED TARGET WITHOUT RUBBER IN COMPARISON WITH THE ABOVE. u This target was made of four 1-in. wrought-iron plates (Abbott's) backed by 20 in. of solid oak and joined toge- ther with ten wood screw-bolts. The target was placed against a bank of solid clay. " Dimensions of target : Length, 96 in. ; width, 48 in. ; thick- ness of plates, 4 in. ; thickness of timber, 20 in. Gun 11 in., No. 214 C. A. & Co., mounted on wooden pivot carriage in front of battery ; charges of cannon powder ; projectiles of Cloverdale cast-iron solid shot ; primers, friction." Range, 84 ft. ; weight of ball, 168 Ibs. ; charge, 30 Ibs. " This shot struck 23 in. from the right edge and 21 in. from the lower edge of the target, passing entirely through plates and timber, and penetrating the bank a distance of 5 ft. Diameter of shot-hole, 12x14 in. The plate is sprung inward on the left EXPERIMENTS AGAINST ARMOR. 757 edge of the shot-hole l in. The timber in the rear around the shot-hole is much broken. One bolt was started forward If in. and five others slightly started, but none were broken. " On the 6th inst., the target having been placed on its longest edge at an angle of 45 with the line of fire, another shot was fired at it from the same gun, under the same conditions, with re- sults as follows : The shot struck 19 in. from the top, 14J in. from the lower edge, and 56 in. from the left edge of target, tearing through the plates, and the shot breaking into pieces, part of which glanced off at an angle of 45 and penetrated the bank on the right of the target ; the remaining portion (43 Ibs.) remained in the shot-hole. Horizontal diameter of shot-hole, 16 in. ; ver- tical, 14f in. The plate is sprung inward on the right edge of the shot-hole, 3 in. ; top edge, 2J- in. ; lower edge, 2^ in. The plates have sprung forward on the top edge 2^ in. One bolt was started forward f in. None are broken excepting the one in the centre of the shot-hole. The plates are cracked around the shot- hole, one crack extending 8 in. The timber is all completely shattered. 879. "The experiment with this target was for comparison with Mr. J". L. Jones's target (composed of four 1-in. iron plates and four 1-in. sheets of india-rubber), to obtain the relative resist- ance. The conditions of the two experiments were identical. The penetration of the projectile fired at this target was five feet from the face, while the penetration of that fired at the iron and India-rubber targets was 12 feet. In the second experiment, oblique firing, 45, the shot at this target did not penetrate en- tirely through, and 126 Ibs. of it were thrown out, at an angle of about 45, into the bank of earth, while the corresponding shot at the iron rubber target passed entirely through it and penetrated the bank of earth a total distance of 6 ft. from its face.* 8 8O. Exporimoiit* at the Warrior Target with 9-Inch Stool Shell, at St. Petersburg, Oct. IT, 1863. " The object in view was to see the effect on a target representing nearly a section of Official: Scientific American, Jan. 23, 1864. 758 ORDNANCE. the Warrior comparatively with steel and with cast iron. Two 4rJ-in. plates from Messrs. John Brown & Co.'s works were fixed on the teak. That portion of the plate hit by the shells is shown on the drawing (Fig. 406) ; the holes are numbered in the order in which the shots were fired. The steel shells were of two FIG. 406. _( 3^ () t ^\2) o o (7\. Q y . Warrior target 9 -in. shells. qualities, one from Krupp, cast and hammered, the other made by Povteeloff, in Finland, from small ingots, and welded together. All the shots weighed about the same, 270 Ibs., and were charged either with 8 Ibs. sand or powder, and were all fired at 700 ft. distance with 50 Ibs. of powder. "Now, although it was evident that the resisting powers of 4J-in. plates were not equal to such shells, still one object was answered in respect to the plates by the experiment. It showed that when the plates were made of really good material, the con- centration of fire, even on so small a surface, will not break up the plates, but merely punch holes, which may easily be plugged in action. "The shell numbered Nos. 1, 2, and 3 made each a hole 10 in. x 9 in., or thereabouts. No. 1 had a flat nose 4 in. diameter, and Nos. 2 and 3, 6^ in. These three shells Krupp classified, Nos. 1 and 3 as hard, and No. 2 as mild steel. All three, how- ever, although only charged with sand, went to pieces on passing through the plates, proving that, had the plate been 5^ or 6 in. thick, they would have been harmless as respects penetration. EXPERIMENTS AGAINST ARMOR. 759 The shells Nos. 4 and 5 were those from Povteeloff, of puddled steel, hit very close together. No. 4, however, made a larger hole than the preceding three, and showed its penetrating power, by not only destroying a large portion of the teak backing, but by passing through another target of teak behind the other. It was found to be only slightly bulged up, without any cracks, not a single piece being taken out of it. The next shell, also of Povtee- loff 's, not having met with full resistance on the plate, went off through a second target standing behind the one fired at, some two miles, quite uninjured. " The Russians present were highly delighted with the favorable results of these latter shots their own production and Mr. Pov- teeloff engaged to produce better when the works were fully in operation. In. fact, unless Krupp brings forward a better quality every way than those yet tried, the Russians will drive him out of their market. The general opinion was that the penetrative power of the Povteeloff shot, compared with Krupp's, was as 5 to 3. "Shells Nos. 6 and 7 were Krupp's, and were charged with powder^ The result on the plate was a slightly larger hole. JSTo. 7 burst in the plate, but did not injure it. " A cast-iron shell was then fired, and went through the plate similarly to Krupp's shells being crushed by the concussion. The conclusion arrived at was, that the cast-iron shell was, as against armor-plates, equal to Krupp's steel shells in penetrative power, but not equal to Povteeloff 's cost being one-fourth. "Further trials will be made on thicker plates, when other shells of Russian make will be tried. We may remark, in pass- ing, that these shells were of steel, made by Povteeloff, from Fin- nish lake ore, and the shells used were made from small 2-lb. ingots, welded up, bored, and turned. With proper apparatus, now nearly ready, the shots will be cast in proper-sized ingots, and be hammered near to form, and be much better in every respect."* * Correspondence of the London Engineer. The London Times has the following account of these experiments: 760 ORDNANCE. 881. Experiment* against the Bellerophon Target, Dec. 8, 1863. "This target has been constructed to represent as FIG. 407. The Betterophon target. Scale, i in. to 1 ft. nearly as possible a portion of the proposed side of the Jtettero- phon iron-cased frigate, ordered to be built at Chatham Yard. "First, a series of cast-iron shells, SCO Ibs. each, were fired at different ranges, and then shells made by Krupp were fired at the 4^-inch armor-plates. The first shell, of hard cast steel, was 22 in. long (two and a half diameters), with a flat end 4 in. in diameter. Fired with 50 Ibs. of powder, at 700 ft. distance, it passed through the plate, oak and teak backing, and broke into many pieces, although filled with sand only. The second and third shells were also of Krtipp's steel, the same length, but with 6i-in. ends. These shells pierced plates, wood, etc., and also went to pieces, although only filled with sand. The fourth shell was made by M. Povteeloff, of pud- dled steel, on Aboukoff's system, the same dimensions as the second and third, and went through iron, teak, etc., but was only bulged up from 9 in. to 12 in., and the end flattened, not a single crack being visible in the shell. The fifth shell, the same as the fourth, passed through iron, teak, and the second target, and went at least a mile beyond. The sixth and seventh were from Krupp, and were charged with pow- der; they were quite flat-ended, 9 in. diameter. One exploded in the plate, the other in the wood. The eighth and ninth shells were of cast iron, and. although they passed through the plates, were of course destroyed. Evening prevented further trials, which will yet be made on the same plate. "The results on the plate were highly satisfactory. In a space of 4 ft. 6 in. by 3 ft. 6 in. eight holes were made without any crack of the slightest description." EXPERIMENTS AGAINST ARMOR. 761 The part of the ship which is to be tested by the target is that situated between the main and lower decks, and not in the line of ports, the object being to test the strength of the general side of the ship. " Special arrangements will be made to strengthen the side in the vicinity of the ports, which will be few in number, as the Bellerf/phon is to carry a small number of very large guns. These few ports can be strengthened by the introduction of addi- tional iron to an extent which would not be practicable if the number of ports were large. "Each frame of the target is made of an angle-iron 10" x 3|-" x -^", and two angle irons 3J" x 3|-" x f", riveted together thus (Fig. 408). To the double angle-irons of this frame the skin, which is composed of two thicknesses of f " plating, making together 1-J", with a layer of painted canvas between, is riveted. " On the outside of the skin plating four horizontal angle-iron stringers are attached, two under the upper armor-plate, 9-J" x 3-J" x -J", the broad flange being square to the skin, and not reaching out to the armor by half an inch. The other two are placed behind the lower plate, 10" x 3" x i". The breadth of the broader flange being the same as the thickness of the backing, it reaches out to, and comes in contact with, the armor. "Wood backing, 10" thick, is worked longitudinally on the skin plating, and between the angle-iron stringers, bolted with nut and screw-bolts through the skin plating. " The armor consists of two rolled plates, 6 in. thick, weighing upwards of 9 tons each. The upper armor-plate is bolted with bolts 2ij" diameter, and the lower plate with bolts 2J-" diameter. In one-half of the target, divided vertically, the armor-bolts have elastic washers, and are clenched on single nuts. In the other half the bolts have common washers with double nuts, and the bolts not clenched. "In constructing this target, the mere capability of resisting shot and shell has not alone been considered ; regard has also been had in arranging its details, to the satisfactory and econom- 762 ORDNANCE. ical construction of an actual ship upon the same plan. In erect- ing the target, care has been taken to support it behind with beam ends, etc., so that the actual condition of the proposed ship's side may be approximated to as closely as possible. "All the portions of this target have been carefully weighed, and the weight, as reported by the Admiralty Overseer, is 389 Ibs. per square foot.""* 88S. The range was in all cases 200 yards. The 1st shot, a 66-lb. cast-iron ball from the 68-pounder; charge, 16 Ibs.; struck the top plate, 9 in. from the upper edge, and midway between the fourth and fifth bolts. The indentation was 1*5 in. deep. About half the bolts in the plate were just perceptibly started, but not strained. The 2d, a 66J-lb. cast-iron shot, with a false, hemispherical, hollow head, fired from the 110-pounder Armstrong gun, with 16 Ibs. of powder, struck between the next two bolts, 9 in. from the top of the plate, over a rib; indent, 1*45 in. deep. The bolts were hardly more started by this shot. The next round was a salvo of four 66^-lb. shot, fired at the top plate, two from the 68-pounder, and two from the 110-pounder ; charges as above. A third 110-pounder was fired, but missed. One 66^-lb. ball struck 8 in. from the bottom of the plate, par- tially on the fourth bolt from the right; indent, 1/75 in; bulge, 2*1 in. One rifle-bolt struck partially on the same bolt, a little to the right; indent, 1*25 in.; bulge, 1*45 in. The bolt was started out '4 in. The other ball struck 1 ft. 9 in. below the top of the plate, and 6 ft. from the right edge; indent, 1'75 in.; bulge, 1'85 in. The other rifle-shot hit the top edge of the plate, chipping out a piece. The condition of the other bolts was not changed. Up to this time the inner skin of the target showed no evidences whatever of the firing. The 7th shot, weighing 66 Ibs., circumstances as above, struck the lower plate 12 in. from the top, and 10 in. to the left of the fifth bolt from the right; the bolt started Jin.; indent, 1*8 in.; * Admiralty circular. EXPERIMENTS AGAINST ARMOR. 763 bulge, 1*95 in. A small backing bolt-head was broken off inside the skin, and nine through bolts were slightly started, but not strained. , The 8th, a 70-lb. steel shell bursting charge 2 Ibs. 6 oz. was fired, with 21 Ibs. of powder, from the Whitworth 70-pounder, and struck 5 ft. from the right edge and 8 in. from the top of the bottom plate, par- tially on the third bolt from the right. Indent, 1*3 in. ; narrow crack on the face of indent; the bolt was driven in -J- in., and afterwards screwed up tight. The plate was bulged J- in. below the edge of the upper plate. The shell broke up. The ends of the plates had not buckled out- wards at this time. The 9th, a 117-lb. steel shell bursting charge 2 Ibs. fired from the 7'1-in. "Committee" modified shunt gun with a 16-lb. charge, struck the lower plate 13 in. from the bottom and 7 in. from the right of the fourth bolt from the right. Indent, 1 in. A general bulge of the plate left the bolt nearest to the indent protruding ^ in., and the next (fifth) in. The plate started out j in. at the right end. The greater part of the shell was thrown back over 200 yards, and buried in the earth in the rear of the guns. The local effect of this shot was less than that of the preceding shots, and its distributed effect much greater. The 10th, a 150-lb. cast-iron ball, fired with 35 Ibs. of powder, from the 10^-in. shunt rifle, struck the third bolt from the i left, in the upper plate; indent, 3'52 in.; crack 5 in. to right of impact, 10 in. long; crack 9 in. long on face 764 ORDNANCE. of indent; no other cracks; plate driven in 3^ in. at bottom, in a length of 3 ft. The left top end of the plate was thrown out -f in., and the backing j and J in. The backing was also driven out slightly endways. Inside, the skin was bulged slightly, and the bolt struck was driven in 2 in. No injury was done. The llth, a hammered cast-steel ball from the same gun charge 35 Ibs. struck exactly at the joint of the upper and lower plates, 3 ft. to the right of the preceding shot, with a velocity of 1520 ft. It punched a 11 '5 x 11'2-in. hole in the 6-in. plate, em- bedded itself to 1 in. below the face of the target, and stuck in the hole, much cracked and considerably flattened on its striking side. On the inside, the rib over which the shot struck was broken and bulged 2 in. ; the next rib was bent 1 in. ; the skin was bulged 2 in., and had a small crack 8 in. long. Two through bolt-heads and two backing bolt-heads were broken oif. The bulge of the target was not perceptibly increased, because the power of the shot had been employed locally. The 12th was a 300-lb. cast-iron solid shot, with a false hemi- spherical head; charge, 35 Ibs. It struck exactly on the third bolt from the right of the lower row in the lower plate, 10 in. from the bottom ; the indent was only 2*8 in., but the distributed effect was more than that of the preceding shot, viz., the plate was driven in at the bottom 2'1 in. in a length of 5 ft. ; a crack 1 ft. 6 in. long was made through a bolt-hole 2 ft. from the point of impact; the top of the plate was started out *4 in. for 2 ft. at the right, and the backing was a little split and driven out -endways. At the back the skin was slightly bulged; the through-bolt struck (which was driven in 1 in. beyond the bottom of the indent) was driven out 2 in. at the back, and two backing bolts w r ere broken. The 13th, a 151-lb. steel shell bursting charge, 5 Ibs. fired with 27 Ibs. of powder, from the 7-in. Whitworth gun, penetrated the lower plate equally distant from the top, bottom, and left end. The rear of the shell was fired outwards, and the head lodged in the front of the backing. The inner-skin plate was bulged a little at a joint, and one through-bolt and two backing bolts were broken. The skin was practically uninjured. EXPERIMENTS AGAINST ARMO$. 765 The cast-iron shots and the steel ball were of excellent quality. The plates were also very tough. The target, considered as the side of a ship, was, at the close of the experiments, practically uninjured. 883. 13-Inch 61O-lb. Steel Shell; li-Iiicli Plate; l-Inch Backing.* On December 11, 1863, a 610-lb. steel shell was fired from the Armstrong 13-in. gun, with 70 Ibs. of powder, at the War- rior target (Fig. 98) ; range, 1000 yards. This projectile smashed a 20 by 24-in. hole entirely through the target, splintering the backing and supports, starting all the plates, breaking nearly all the bolts, and sluing round the entire structure. The shell con- tained a 24-lb. bursting charge, and exploded at the instant of its passage through the plate. This, however, should be considered a punching rather than a racking shot, so great was the disparity between the power of the projectile and the resistance of the target. 884. 13-Ineh 344|-lfo. Steel Shot; 11-Inch Plate. On the 10th of March, 1864, a 344|--lb. spherical steel ball was fired from the same gun with 90 Ibs. of powder striking velocity, 1680 feet per second ; range, 200 yards at an 11-in. plate 3 ft. 5 in. x 2 ft. face, supported at the rear by two 12-in. oak posts. The ball struck the centre of the plate, breaking it in two, indenting it 4*9 in., and dislodging and splintering the supports. But the shot was flattened to 15 '2 in. maximum and 10 in. minimum diameter, and thrown back towards the gun. 885. 13-Inch 603-lb. Bolt; 6^-Inch Plate; 18-Inch Back- ing; IOOO Yards Range.* In July, 1864, the Armstrong 13-in. gun was fired, at 200 yards range, with 40 Ibs. of powder and 860 ft. initial velocity. This charge was calculated to give the striking- velocity (840 ft.) which the ordinary 70-lb. charge would give at 4000 yards. The target, resembling the Bellerophon target (88 1), was composed of a 6 -inch plate, 18 in. of teak backing supported by horizontal stringers, IJ-in. double skin, and heavy iron ribs. The shot smashed entirely through the plate and backing. * The account of these experiments was not obtained from official sources. 766 ORDNANCE. 886. 15-Inch and 11-Inch Balls and Parrott 15O-lb. Bolt; Various Plates ; Late Experiments. Some important experi- ments with the above projectiles have very recently been made at the Washington j^avy Yard. The Department has determined not to make public the details of these experiments at present. The general results are as follows : A target composed of 30-in. oak backing and a solid 6-in. French plate, made by Messrs. Petin, Gaudet & Co., was cracked, smashed, and completely penetrated by a 15-in. 400-lb. cast-iron ball, fired at about 50 yards range, with 60 Ibs. of powder, at an initial velocity of 1480 feet per second. A target composed of six 1-in. plates, backed by 10 x 10-in. iron beams, was torn in two and thrown down by similar projectiles. Laminated targets, composed of 1-in. plates, up to 13 in. aggregate thickness, and backed by 24 to 30 in. of oak, have been ruptured and shattered through and through, though not completely penetrated, by the same shot and charges. The 15-in. ball has also knocked down, displaced, and shattered various targets of considerable thickness but not of large size, and therefore not exactly representing the mass and conti- nuity of a ship's side. The 15-in. gun has not been fired at the Warrior target or at any 4J-in. target. The 11-in. gun has recently been fired at various targets with 30-lb. charges and 169-lb. cast-iron balls. At 50 to 100 yards range, this gun completely penetrates 4rJ-in. solid plates of ordinary qual- ity, but does not make a clean breach through the best plates (2 1 5). The Parrott 8-in. rifle, with 150-lb. bolts, and 16 Ibs. of pow- der, breaks through but does not punch the best 4^-in. plates, and does not seriously injure the backing. These late experiments have also shown that the convex target representing the Monitor turret, offers very much greater resist- ance to both punching and racking than the flat target, composed of the same materials. 887. Experiments with Steel Shot against Armor.* The * The author has not yet had access to the official reports of the later experiments in this direction ; therefore only an abstract of the results will be attempted at pres- ent. The authorities are the London Time*, and Army and Navy Gazette. EXPERIMENTS AGAINST ARMOR. 767 experiments with Mr. Whitworth's steel shells, recorded in foregoing tables, demonstrated the first important improvement in the mate- rial of projectiles, although the United States Navy Department had previously made a remarkably tough mixture of cast iron for balls, and had demonstrated its superiority to wrought iron.* But the improvement in the material of projectiles did not assume a revolutionary character it had hardly been imagined that steel would so soon be acknowledged as the only proper shot- material for effective iron-clad warfare, until early in 1864, when spherical steel balls were fired through the Warrior class of armor by guns and charges which would neither punch nor crack it when the balls were of cast iron. 888. In January, 1864, the 4^-in. plates of the Warrior target were broken through by steel balls from the 68-pounder gun with 16-lb. charges. The average penetration of the cast-iron ball, gun and charge the same, is 2-J- in., and the best plates are not cracked. 889. Shortly afterwards, at Portsmouth, the 9'22-in. "100- pounder" smooth-bore fired a 113-lb. and a 114-lb. Bessemer steel ball, with 25 Ibs. of powder at 200 yards range, entirely through the Minotaur target of 5^-in. plates and 9 in. of teak backing, smashing a 2-ft. hole in the rear and driving fragments all over the ship and into the opposite timbers. A third shot, conditions the same, passed entirely through the centre of the plate, making a 10-in. hole through the face, drjving large masses of the back of the plate into the wood backing, and smashing the ship's tim- bers (the wooden target-ship Monarch) over a space of 2 x 4 ft., and bulging them 12 in. The 4th shot of Firth's steel, struck over a wooden knee ; it did not shatter inside of the ship, although it penetrated the plate. 8OO. Speaking of similar experiments against the America target ship, the Army and Navy Gazette of March 12, 1864, says : " This old ship received, in two days' firing, 78 heavy knocks against her sides from heavy iron shots. She was none the worse, but floated quietly at her moorings. Not so after one steel * Captain Palliser has recently increased the effectiveness of cast-iron shot, in a great degree, by chilling the exterior of the metal when it is cast. 768 ORDNANCE. shot was brought to bear against her. This penetrated the armor- plate, which vainly strove to keep the subtle and destructive missile outside ; and gradually, but surely, did the strongly-built craft fill with water, and settle down on the mud." 891. On the 24th of March, 1864, at Shoeburyness, the 110- pourider Armstrong gun was fired at various 5J-in. plates without backing. The average penetration in backed 4rJ-in. plates of 111- Ib. cast-iron shot from this gun, with 14-lb. charges, is 1*6 in. The plates are not usually cracked, but the projectiles are com- pletely smashed. In this experiment, two Bessemer steel projec- tiles, made at the Atlas Works, and fired with 12-lb. charges, passed entirely through the plates. Other steel projectiles in- dented the plates from 2 to 4 in. In all cases the rear of the plates were bulged and cracked, and in several cases pieces of iron were knocked out. 892. About the same time, two steel 100-lb. balls were fired from the Armstrong 9'22-in. smooth bore at a 6-in. solid Millwall plate, bolted to the side of a target ship at Portsmouth ; charge, 30 Ibs. ; range, 200 yards. Both balls were buried partly in the plate and partly in the ship's side. The whole inner part of the plate about the shot-holes was broken up. A section of the ship's side, 4x16 feet, was bulged inwards from 4 to 7 in., and the whole was violently shaken. Two other steel balls, from the same gun, just broke through two other similar plates and lodged at the front of the backing, without injuring the interior of the ship. 893. In May, 1864, experiments with steel shot were made against 5-J-in. plates, bolted to the sides of the America, wooden target ship at Portsmouth. The guns were the 9'22-in. smooth- bore and a 7-in. shunt-rifled gun ; charges, 30 and 25 Ibs. respec- tively ; range, 200 yards. All the shot broke through the plates ; one of them passed through the ship's side ; and in all cases the ship's side was more or less shattered. A 6-in. plate was also broken through by both the 115-lb. ball and the 98-lb. bolt ; the debris of the plate was driven into the backing. The projectiles used in these experiments were prepared at EXPERIMENTS AGAINST ARMOR. 769 Woolwich ; they were all considerably flattened and mutilated upon striking the plates. 894. In June, 1864, the following experiment was made at Shoeburyness : The target represented the side of the Lord Warden iron-clad (building), and consisted of 12|-in. oak frame timbers, supported by deck beams and iron knees, and connected by 6-in. x IJ-in. diagonal iron braces ; the inner 8-in. planking ; a casing of 1-J-in. iron plate; 10 in. of oak ; and, finally, the 4^-in. armor-plate, held by 2-in. bolts in all, 30 in. of oak and 6 in. of iron. The target presented a 20 x 9 ft. face. Range, 200 yards. A 9'22-in. rifle, made for a lOJ-in. " 300-pounder," fired a 220- Ib. steel bolt, with 44 Ibs. of powder, at 1460 ft. striking velocity, entirely through the target and the bank beyond and a mile out to sea. The splinters of the backing and an iron knee were hurled to the rear in every direction. Two steel 120-lb. shells bursting charge, 7 Ibs. fired with 20-lb. charges from a 6^-ton 9'22-in. rifle, passed through the armor-plate and burst in the backing. The second shell tore the back of the target into splinters, which were thrown violently to the rear. A 300-lb. bolt, from the 10^-in. gun, was then fired entirely through the target, with a 45-lb. charge. The plate, although pierced by every shot, was not cracked. 8945. Several experiments have also lately been tried in St. Petersburg with round steel shot and ordinary cast-iron shot, both 9 in. in diameter. The round steel shot are also the production of Mr. Povteeloff. The steel is made from Finnish lake ore puddled, and made into octagonal blooms, which are then again heated, and gradually hammered into a globular form, in swages, under the steam-hammer ; and when fired from the ordinary naval gun, at 4^-in. plates, the penetration of the steel shot was found to be nearly double that of the cast iron, and the injury done to the plates much greater. Round steel shot have also been tried from Germany. 896. The following experiments, partly with steel shot, also show the quality of the standard British armor-plates : 49 770 ORDNANCE. EXPERIMENTS OF FEB. 24 AND 25, 1864.* " The plates were bolted to the side of the target-ship America, and were fired at on the 24th from the 68-pounder smooth-bore gun, with the service charge of 16 Ibs. of powder ; and on the 25th with spherical cast-steel and wrought-iron case-hardened shot from the 100-pounder Armstrong, with 25 Ibs. of powder. The range of both occasions was 200 yards." The following is the list of the plates selected for test (Table 140): " Lord Warden, 5-in. plate ( J. Brown & Co.) Eleven shots were fired at this plate, three overlapping each other. Diameter, 9 in. ; depth of indentation, l T 7 o in. With the exception of the third and eighth shot, which showed a minute separation of the TABLE CXL. COMPETITIVE TEST OF ARMOR-PLATES. PORTSMOUTH, FEB., 18C4. Manufacturers 1 Names. Ship. Descriptions. Admiralty Order of Merit. John Brown & Co Lord ff^arden. ri-in. rolled. A i. 4i-in. A i. H Royal Alfred. 4|-in. " A i. ft Prince j4lbert y cupola ship. 5-J-in. bent plate. A 2. Mersey Co. A-pincoitrt, C^-in. liummcred A infer 3> u 5^-in. rolled. A i Charles Cammell & Co... Lord Clyde. 5i-in. A i. Millwall Co Bellcropkon. 6-in. " A i " 3- Beale & Co . Pallas. dA-in " B i. T2 1M> surface layer of the metal within the indent, there were no cracks upon this plate, and it was reported upon as being ' remarkably good.' Injury to backing, nil. u Lord Warden, 4^ in. (J. Brown & Co.) Fourteen shots were * This account is quoted from the correspondence of the Army and Navy Gazette of March 12, 1864. EXPERIMENTS AGAINST ARMOR. 771 fired at this plate, several overlapping each other. Plate was started J in. from backing. After twelve shots were fired from the 68-pounder gun, with 16-lb. charge, producing only slight in- dentations varying from 2*9 to 2*1 in., two shots were fired from the 100-pounder gun with 25-lb. charge. The first was made of cast iron at Woolwich laboratory. It broke up after penetrating the plate 6 in. The second was made of Dr. Price's crucible iron. The shot was again destroyed after a penetration of f of its diam- eter into the plate. Backing sound. Royal Alfred, 4J in. thick (J. Brown & Co.) This plate re- ceived five severe blows near its edge from the 68-pounder cast- iron shot without showing material injury. A wrought-iron shot, case-hardened, was subsequently fired at it, producing an indent 2J in. deep and 9 in. diameter. A Bessemer cast-steel shot fol- lowed, embedding itself nearly half its diameter in the plate. No cracks appeared around the part struck. Another cast-steel (crucible) shot was then fired, and struck 4 in. distant from the preceding one, shaking it out of its place. This shot stuck in the plate, projecting 3*7 in. above the plate's outer surface. Although the shot preserved its spherical form, it was much broken up. Injury to backing, nil. " Prince Albert, 5-J in. thick (J. Brown & Co.) This plate was 6 ft. long and had been reheated and bent. It was severely tried on the lower edge by three overlapping shot which made two cracks downwards. It received a fourth shot near the centre without showing any crack. " Agincourt, 5-J-in. hammered plate (Mersey Company). The first two blows from the 68-pounder inflicted no apparent injury upon this plate. The third brought out a crack 2 ft. in length. The fourth shot cracked the plate through to within an inch of the surface. Shot 6 broke out a piece 2 ft. 6 in. x 12 in. It re- ceived seven shots in all. " Agincourt, 5-J-in. rolled plate (Mersey Company) was an ex- cellent plate. The indentations were slight ; and, though some of the shots touched each other, no cracks were apparent except in the 5th indent. It received nine shots. ORDNANCE. " Lord Clyde, 5-J-in. rolled plate (Cammell & Co.) First shot showed a crack 4 in. long. Another shot, striking near the for- mer, broke out a piece of plate 19 in. x 8 in. The plate subse- quently received eight additional blows without material injury. It was also fired at with two Bessemer steel shot which embedded themselves in the plate. " Belleroplion, 6-in. rolled plate (Millwall Company), received four shots in two pairs, shots slightly overlapping. JSTo cracks. The fifth and sixth shots opened the lamina of the plate, and the seventh and eighth manifested a large number of severe cracks in and about the indentations. It received two steel shots from the 100-pounder, with 25-lb. charge, and showed considerable resist- ance. The backing was somewhat injured. " Pallas, 4 75 P er cent, in the cotton. Silicic acid, soluble 0-53 " " Lime 0-27 " " Alkalies ~ 0-30 " " Magnesia j Oxide of iron V traces. Sulphuric acid J The ash was determined for comparison in a specimen of cotton obtained from the Austrian Works which had been submitted to the preparatory purifying processes (treatment with carbonate of potassa and long-continued washing). The results obtained fur- nished a mean of 0*63 per cent, of ash, which consisted principally of lime and magnesia, and contained a small proportion of insolu- ble matter (clay and sand), traces of soluble silicic acid, and of alkalies. The above determinations and analyses of the ash in the gun- cotton and in the unconverted cotton show that no result of the slightest practical importance, in the direction supposed to be aimed at, is obtained by the treatment with solution of soluble glass, to which the purified gun-cotton is submitted, according to the Austrian system of manufacture. It is evident that, by the washing in running water for five or six hours, and subsequent rinsing of each skein, after the treat- ment with silicate of soda, the proportion of the latter which had in the first instance been introduced into the cotton is again ex- tracted, only traces being retained by the cotton, besides a very small proportion of silica in the form of pulverulent silicate of lime, resulting from the decomposition of the soluble glass by the lime-salts in the spring or river water. It will be observed that, in specimen (J) of gun-cotton, the proportion of non-volatile con- stituents is actually even less than that found in the purified but unconverted cotton a fact which is evidently due to the solvent action of the acids upon portions of the mineral matter in the GUN-COTTON. 803 cotton. In the place of the comparatively large proportions of lime and magnesia in the original cotton, the product which, after separation from the acids by very long-continued washing, &c., has been submitted to treatment with soluble glass and again washed, contains some small quantities (necessarily variable in a product of manufacture) of impurities (clay and sand) derived from the water used, and of silicic acid in combination with lime and also with soda, minute quantities of the soluble glass having escaped removal or decomposition in the final washing process. Supposing that the maximum proportion of silicates (1 per cent.) found in the above determinations existed entirely in the form of soluble glass in the finished gun-cotton, a piece of twist 12 ft. 10 in. in length, and of the size used for artillery purposes (-J- inch thick), would contain only one grain of soluble glass. It is evi- dent, therefore, that no protective effect nor retardation in the explosion of the gun-cotton can result from the treatment with soluble glass to which it is submitted. Experiments on tlie Hygroscopic Properties of the Austrian Gun-Cotton. (8) It has already been stated that the proportion of moisture contained, under normal conditions, in the specimens of Austrian gun-cotton was found to be very uniform, the main proportion being fixed at 2 per cent, by the results of several experiments. Some gun-cotton prepared from ordinary cotton- wool, and having the same composition as the Austrian samples but not having been submitted to the preparatory or subsequent treat- ment with alkali, nor to the very long-continued washing was examined with regard to its hygroscopic properties in comparison with the Austrian gun-cotton. The proportion of moisture exist- ing in the former, under ordinary conditions, was found to be almost identical with the average proportion in the Austrian samples. Some experiments were instituted to ascertain the rate at which the Austrian gun-cotton would absorb moisture on exposure to a damp atmosphere. The specimens experimented with were first thoroughly dried 804 ORDNANCE. APPENDIX. in vacuo over sulphuric acid, and then exposed for successive periods, together with a shallow vessel containing water, under a capacious bell-jar placed in a moderately warm room. The fol- lowing results were obtained : Period of exposure to a damp atmosphere. Specimen. lhr 2 hrg> 4 hrs 20 hr8 _ 30 hrs 72 hrs No. i 1-35 ... ... 3-15 ... 3-87 " 2 1 -60 ... ... 3-21 ... 3-65 " 3 " 8 9 a-i5 ... 3.55 " 4 i-73 2 ' - 3- 2 i " 5 1 '77 2 ' 21 3-9 These results show that the rate of absorption of moisture by the gun-cotton is uniformly rapid up to the point where 2 per cent, (the normal proportion of hygroscopic moisture) have been ab- sorbed, and that, when this point has been attained, the absorp- tion of further moisture proceeds comparatively very slowly.* Several experiments were made to determine, as far as possible, the maximum amount of moisture which the gun-cotton would absorb from a damp confined atmosphere. The great rapidity with which the specimens operated upon parted with the water absorbed, on exposure to the ordinary atmosphere, after the ex- periments had been proceeded with for some days, rendered the attainment of accurate numbers very difficult. The results, how- ever, showed very definitely that no important increase in the amount of water absorbed took place when it had reached from 5-5 to 6 per cent. "When these specimens had ceased to absorb moisture, they were, after the last weighing, exposed to the at- mosphere at the ordinary temperature for one hour, and again weighed, when they were found to have parted with very nearly one-half of the total proportion of water absorbed. After further exposure to air for about four hours, the proportion of moisture retained had fallen to the average normal percentage (2 per cent.), and afterwards evinced no further tendency to decrease. * Several determinations of the moisture in cotton rovings, both before and after treatment with alkali (and repeated washing), show that the proportion of hygrosco- pic moisture in the cotton amounts to between 6 and 7 per cent., this amount being reabsorbed by the dried cotton, within twenty-four hours, on exposure to air. GUN-COTTON. 805 Two specimens were kept confined as described, together with a vessel of water, for several weeks in a moderately warm room. The water had then condensed, in numerous minute globules, up- on the projecting filaments of the gun-cotton ; the specimens were therefore very highly charged with moisture. In this condition they were exposed to the air at the ordinary temperature ; within one hour and a half they contained only about 4*5 per cent, of mois- ture. After the lapse of a second similar period, the moisture had decreased to about 3 per cent (3*16 in one specimen and 2' 78 in the other). When again weighed, after a lapse of about four hours, the percentage of water had fallen, in both, to the average proportion. Experiments corresponding to the above were made with the specimen of gun-cotton referred to above as having been prepared from common cotton-wool. The rate of absorption of moisture of this specimen was found to be decidedly more rapid than that of the Austrian gun-cotton ; but they very closely resembled each other as regarded the rapidity with which they again part- ed, spontaneously, with the moisture absorbed from a damp at- mosphere, and the average proportion ultimately retained. The differences noted in the rate of absorption of moisture between the two varieties of gun-cotton, is most probably due to the dif- ference in their mechanical condition. Some of the specimens of Austrian gun-cotton used in these experiments were picked asun- der, as loosely as possible, instead of being exposed in the form of twists ; the difference thus established in the mechanical con- dition of the specimens did not affect, to any great extent, their relative hygroscopic properties. It was found impracticable, however, to reduce the gun-cotton rovings to the same mechan- ical condition as the gun-cotton prepared from finely carded wool. 922. It appears from the results above described, that (a) The proportion of moisture absorbed and retained, under ordinary circumstances, by the gun-cotton is about double that contained under similar conditions in good gunpowder (which averages one per cent.). 806 ORDNANCE. APPENDIX. (5) Gun-cotton possesses no tendency to absorb moisture beyond that proportion, unless in very damp situations ; and even, under those circumstances the proportion of moisture absorbed is limit- ed. Moreover its capacity for retaining water (beyond the normal proportion) is so feeble that, however highly it may have acci- dentally become impregnated with moisture, it will return spon- taneously to its original condition of dryness by simple exposure to the open air for a few hours. In these respects it possesses important advantages over gunpowder; for although the latter contains, under normal conditions, less moisture than gun-cotton, it exhibits great tendency to absorb water from a moist atmos- phere, which it continues to exert until it actually becomes pasty. Moreover gunpowder, when once damp, cannot be restored to a serviceable condition without being again submitted to the incor- porating and subsequent processes. * * * 923. IV. Information given by Baron Lcnk 011 June 22 and July 14, 1863. 1. What weight of gun-cotton and gunpow- der give equal effects f In accordance with experience, gun-cotton produces the same effect as three times its weight of gunpowder ; which proportion, under certain circumstances, may be increased to six times its weight of gunpowder ; for the effect of gun-cotton in proportion to gunpowder is the greater the more resistance is offered to the charge by the sides which enclose it, and the less gas can escape at the beginning of the explosion. 924. 2. What ~bulks of each give equal effect f The space required for a gun-cotton cartridge, to produce an equal effect, is scarcely half as large as that of a gunpowder cartridge ; and it is only made equally large or slightly larger, if secondary circum- stances should demand it. 923. 3. Is the effect more constant with gun-cotton or with gunpowder f The effect of small fire-arms and of artillery in general is considerably more uniform and constant with the use of gun-cotton than with gunpowder, provided the proper charge and cartridge has been taken. That superiority gun-cotton partly owes to the chemical pro- cess by which I have produced it, and partly to the uniform forma- GUN-COTTON. 807 tion of the cartridge, which can only be attained by its regular texture, using it in the shape of cotton-yarn. 926. 4. Which admits of more precise aim ? On account of the more constant effect of gun-cotton, and because its use prevents fouling of the gun, which further admits to reduce the space be- tween shot and barrel, and on account of less heating of the gun. as well as by the uniform position of the cartridge, there must be a more precise aim of shot with gun-cotton which, moreover, has been fully proved by experience. 927. 5. Which occasions least recoil f Chiefly on account of the smaller space of time the projectile requires to pass through the barrel of a gun to attain a certain initial velocity, the recoil of the gun is less than with the use of gunpowder. It may be stated that, by the official trials of the Commissioners in the year 1860, the recoil of the gun with gun-cotton was found to be 0*68 of that with gunpowder. 928. 6. What is the relative effect as to fouling f Except an extremely small residuum of carbon, there is no deposit with the use of gun-cotton. The barrel of a gun requires no cleaning out ; there is no chemical effect upon cast and wrought iron, steel, or bronze barrels by using gun-cotton cartridges. 929. 7. Is gun-cotton liable to decay when stored f Gun- cotton has been stored like gunpowder for twelve years, usually packed in wooden boxes : and no trace of alteration has been dis- covered. My own experiments go back as far as 1846, and have given most favorable results in this respect. 9SO. 8. How is it affected by water or damp f Gun-cotton placed under water is unalterable. By the transformation of or- dinary cotton into gun-cotton, it loses the greater part of its hy- groscopic property, so that gun-cotton, properly manufactured, resists the influence of damp much better than gunpowder : and moreover it cannot, like gunpowder, get permanently spoiled thereby. Gun-cotton, if dried in the open air, contains 2 per cent, moisture ; ordinary cotton, about 6 per cent. Gun-cotton, placed in a room completely saturated with moisture, after thirty-three days of exposure contained 8 per cent, moisture., whilst under the 808 ORDNANCE. APPENDIX. same circumstances gunpowder was saturated with 79*9 per cent, of water ; some weeks afterwards the whole saltpetre of the gun- powder was converted into a concentrated solution of saltpetre, whilst gun-cotton took no more than 8 per cent, of water as a maximum saturation. 931. 9. Which admits of most rapid firing f The gun being heated considerably less by using cotton cartridges, the absence of a noteworthy residuum and smoke admits of a more easy manipulation and sighting of the gun, and thereby secures a more continuous and rapid fire. It may be stated that 100 rounds with gun-cotton were fired in thirty-four minutes, and the barrel was heated to fifty degrees Cent. ; whilst 100 rounds with gunpowder cartridge in 100 min- utes heated the gun so much that water dropped on the barrel immediately evaporated with noise, though three times as much time was required with the powder charges. The Commissioners continued the trials with gun-cotton up to 180 rounds without any danger from heating being apprehended, whilst the Commission- ers thought it advisable, for the sake of safety, not to continue firing with powder charges under the above circumstances. 932. 10. What effect has gun-cotton on the coolness and clean- ness of the gun f It has been already mentioned that, with the use of gun-cotton, fire-arms remain considerably cooler than with gunpowder : and the slight residuum has no influence upon the effect of the gun. 933. 11. How far is it adapted for Creech-loading f There being no fouling of the gun, it follows that with the use of breech- loaders the construction of the breech may be kept quite tight. 934. 12. How is it for precision of aim f Under all cir- cumstances the aim is not disturbed or interrupted, there being no smoke attending the discharge of the gun. 93*>. 13. Has it any special advantages in forts, skips, and casemates? From many experiments, but especially from the official trials made in the casemates of the fortress of Comorn in the year 1853, it results that under circumstances which would render the firing with powder difficult, or even impossible, there GUN-COTTON. 800 was no trouble or molestation in any way to those serving the guns with the use of gun-cotton cartridges. The trials in the fortress of Comorii were made in casemates, ventilation being intentionally obviated. After fifteen rounds with powder cartridges, further sighting of the gun was impossi- ble ; after forty-six rounds, one of the men serving the gun fell into convulsions of suffocation ; a second man being ordered in the place of the first disabled man, got immediately sick on enter- ing the casemate ; the rest of the men were more or less stupefied ; it was necessary to stop firing after fifty rounds given in eighty minutes. By using gun-cotton cartridges, on the contrary, after fifty rounds the men serving the gun felt not the least molestation, and the aim was always clearly visible. 936. 1-i. How is it adapted for mining f The more accel- erated effect of gun-cotton, and the possibility of enclosing in the same space more than double the quantity of gases, especially direct us to employ gun-cotton where it is desired to attain an energetic effect for mining purposes, for example, to secure har- bors by means of sea-mines. 937. 15. What is the relative danger of manufacture f In the manufacture of gun-cotton every manipulation, up to its final accomplishment, is without any danger whatever, whilst with the manufacture of gunpowder danger of explosion exists from the beginning of the operation. 938. 16. What is the comparative risk in conveyance? The smaller weight of gun-cotton, as well as the smaller volume of it for an equal effect, favors the conveyance of gun-cotton consider- ably ; and it may be taken moreover into consideration that the dangerous " getting to dust" of powder cannot take place with gun-cotton. The transport of gun-cotton to the most distant parts of the empire of Austria under intentionally difficult circumstances, has always been effected without difficulty. 939. IT. How is it adapted for shells f Shells filled with gun-cotton hold a considerably larger quantity of material for the production of gases ; at the same time, it is in the nature of both 810 ORDNANCE. APPENDIX. compounds that gun-cotton develops far quicker the gases of combustion than gunpowder; for this reason, shells filled with gun-cotton burst into at least double the number of pieces. 940. 18. Is it liable to spontaneous explosion f From the last Report, dated June, 1863, of the Professors of Chemistry appointed by the Minister for War to report on that subject, and to give their opinion, and which is submitted to you, the appre- hension of self-explosion has in no way any foundation whatever. Without direct ignition, gun-cotton may detonate between iron and iron if a heavy blow be struck ; but it is known that only that part explodes which was hit, without communicating igni- tion to the surrounding particles. If, however, even with an iron hammer, gun-cotton be struck a heavy blow upon bronze or other soft metals, or upon stone, no detonation can take place. In every report of the Austrian Empire Commissioners, that subject was considered and disposed of as not impairing the safety of manipulation. 941. 19. How far is it possible to regulate its explosive power f It has been established by experience that it is possible to moderate the force of gun-cotton within very extensive limits, and thereby to suit it to the different purposes without having ground for apprehension that variable effects would be the consequence ; that valuable property of gun-cotton, however, requires that the trials be made under the superintendence of an expert, which will secure the desired effects to a certainty. 942. 20. What is its cost of manufacture f Supposing quan- tities which would produce equal effects, then its cost is consider- ably less than that of gunpowder ; under ordinary circumstances and normal prices of cotton, the cost of manufacture of gun-cotton is under fourteen pence per pound, but at the present high price of raw cotton its cost will be under twenty pence per pound weight.* {i3. 21. Give us what, in your opinion, are the essential points in the manufacture of gun-cotton f a. Cotton. Any sort of cotton may be used for the production * Baron Lenk subsequently reduced this estimate. GUN-COTTON. 811 of gun-cotton, provided it be tolerably free from seed-capsules and oleaginous matter. Absence of the latter is indeed imperative ; hence factory cotton, as ordinarily obtained, must be digested in a weak alkaline solution, as is usual in such cases. Other forms of lignine can be substituted for cotton to produce an explosive material viz., flax, hemp, bog-grass, maize, straw, rags, sawdust, &c. I have given rules so as to meet the case of either of these ; however, it is only in some extraordinary cases that any of these materials are to be preferred to cotton ; further, ulterior applications of the explosive material are much facilitated by the device of spinning into threads. O44:. b. Nitric Acid. The nitric acid employed must be in the highest possible degree of concentration ; and here the remark should be made, that an impurity of hyponitric acid imparted to the acid by concentration, and which is difficult to eliminate, does not prejudice the acid for this special application. O4o. c. Suiphwric Acid. The ordinary commercial sulphuric acid of spec. grav. 1'84 answers perfectly. 946 d. Mixture of the Acids. This consists of one part ly weight of nitric acid, and three parts (weight) sulphuric acid, assuming the nitric acid employed to possess an average specific gravity of 1-485. If, however, the specific gravity should differ from the above, then cognizance of the amount of anhydrous acid supplies the data necessary for regulating the mixture. The mixture is effected by means of an apparatus represented by Fig. 1.* The vessel C is filled with the predetermined quan- tity (equivalent to the required weight) of nitric acid; B and D with sulphuric acid. This being done, the acids from the three vessels are allowed to run very slowly into F, in which is an agitator T, set in motion by the handle L. As soon as a portion of the two acids has been mingled in this manner, the mixture is allowed to run from F to G, and the operation resumed as before. The reservoir G being completely filled, its contents must be set aside in closed vessels. It is advantageous to preserve the * This refers to a drawing exhibited at the time. 812 ORDNANCE. APPENDIX. mixed acids a considerable time in the above vessels ; in no case must the mixture be used until it has become quite cold. 947. e. Process of Steeping. Cotton-wool ordinarily absorbs about 6 per cent, of atmospheric moisture, which must be dissi- pated in a drying-room heated to 95 F. previous to dipping the cotton. Steeping is effected in an apparatus represented by Figs. 2, 2a, and 2J.* The apparatus, during the process, is kept cool by a con- stant change of cold water poured into the vessel F. The cham- ber A contains a store of acid, B sixty pounds of the acid mixture, D represents the vessel in which the cotton is stored after dipping is accomplished. Two skeins (about three ounces) of dried cotton are dipped at one operation in the mixture contained in B, the spatula G being used to effect, by pressure, complete incorpora- tion between acid and cotton ; in the next place, the cotton is to be removed from the bath, laid upon the rack C, and pressed to such extent that the amount of mixed acids left absorbed by the cotton be in the ratio of 10^- Ibs. of the former to 1 Ib. of the latter. The cotton being now lifted into the vessel D, this is to be filled with mixed acids, and the portion of acid absorbed made good by means of the tarred spoon E, in such manner that the surface in B may always maintain the same level for every additional por- tion of cotton dipped. The vessel D filled in the manner prescribed, is at length set aside, the due proportion of its contents being regulated, if neces- sary : the regulation is easily accomplished after a little practice, but it is seldom requisite. The cotton is next compressed by the handle H in such manner that it is wholly covered by acid, to the further action of which it is left exposed for the space of forty- eight hours; it must be cooled during that exposure, thus guarding against the violent action of the acids resulting in de- composition. 948. f. Removal of Acid from the Gun-Cotton. This is per- formed by means of a centrifugal machine, the drum of which is * This refers to a drawing exhibited at the time. GUN-COTTON. 813 of copper, a material which lasts a considerable time ; after this manipulation, there still remain 3 Ibs. of acid in the gun-cotton manufactured from 1 Ib. of ordinary cotton. This must be got rid of by rapid water affusion applied in some convenient manner. Mere affusion, however, does not suffice to get rid of all the adherent acid, hence the cotton must remain for a yet longer period in a stream of water, natural or artificial. 949. g. Impregnation of Gun-Cotton with soluble Glass. The object of this process is to close the pores of the gun-cotton fibre by silica precipated within them, by which the velocity of explosion of gun-cotton is hereafter retarded; moreover any lingering traces of acid that may remain are neutralized by com- bination with soda liberated from the soluble glass. This opera- tion is performed by means of a centrifugal machine, into which a central tube passes for supplying the glass solution. By this arrangement the liquid is driven in very minute division through the gun-cotton ; the glass solution employed has a density of 12 Baume. The material having been treated as described, has next to be dried by atmospheric exposure : as drying proceeds, decom- position of the soluble glass goes on. Atmospheric carbonic acid uniting with soda, forms carbonate of soda, whilst silica is pre- cipitated. The carbonate of soda thus produced being soluble in water, can be got rid of hereafter by washing, whereas the precipitated silicic acid not being soluble, remains attached to the cotton fibres, protecting them from decomposition under atmospheric influences, however high the temperature may be. 9oO. h. Treatment with Soap. For many purposes it is desi- rable to retain the fibres of gun-cotton soft, in order to guard against the contingency of explosion from very violent friction, gun-cotton being somewhat harsh to the touch. This is readily effected by dipping the material, already treated with soluble glass and washed, previous to final drying, into a soap ley, the excess of which is to be hereafter squeezed out, and the gun-cotton finally dried. 95 1 . 22. Have you any special information to give the Com- mittee respecting the practical applications of gun-cotton f 814 ORDNANCE. APPENDIX. a. In general. The proper utilization of gun-cotton presup- poses a thorough knowledge of the nature of its energy and the bearing of its mechanical advantages, in order that the object proposed may be gained through a favorable choice of circum- stances. These influences are more perceptible with gun-cotton than with gunpowder, inasmuch as gun-cotton admits of variation from a point of inefficiency to one of highest energy. Ignited in an open space (i. c. not under pressure), the explosive effect of gun-cotton is trifling, very much less than that of gun- powder. Ignited in spaces more or less closed, then in proportion as the closure is perfect does the explosion assimilate itself to that of gunpowder, the force of which under certain circumstances it considerably surpasses; i. presented by Fig. 416. VII. i 9 " " 17-0 1402 J GUN-COTTON. 815 powder should be nearly equalled by a charge of gun-cotton only one-third of its weight. The available power of one part of gun- cotton by weight, may, under certain circumstances, be raised to the effect of six parts by weight of gunpowder. 952. b. Application of Gun- Cotton as a charge for Smooth- bore Guns. The standard of reference was furnished by experi- ments conducted with a 12-pounder bronze field-piece, which gave results as follows : The weight of shot, solid round, used was 12 Ibs. Diameter of shot 4*5 inches. (English weight and measure.) Diameter of bore for gun-cotton 4*56 inches. Diameter of bore for gunpowder 4*67 inches. The normal performance of ordinary powder-guns gives result I., as compared with gun-cotton. With gun-cotton, when com- pressed charges were used, each of 13*6 oz., result II., gun 2 ; the gun was not injured; while with 14'8 oz. of charge, after a few rounds, a considerable enlargement of the bore, where the shot lies, took place. A similar result happened to a sec- ond gun, No. 3, even with a charge of 13*6 oz., after the first few shots. When one of the enlarged cartridges, represented at Figs. 416 and 417 was used, occupying 1*1 of the powder-space, the gun's endur- ance was perfect, and no loss of effect was sustained, and its practice remained good, as proved by results set forth at III. and Y., since equal charges in very different spaces (i. ., in the ratio of 5 to 8) still produced equal results. In proportion as the tube is shorter, an increased charge is required (shown by results Y., YL, VII.) ; yet the effect of a normal powder-gun and charge may be attained by a tube short- ened from 13^ to 9 calibres : it follows that guns to be used with gun-cotton may be constructed much shorter than if intended to be charged with gunpowder*. With the largest charge used, i. r. Redtcnbacher, Dr. Schrotter, and Dr. Schneider, TO His EXCELLENCY FIELD-MARSHAL JOHANN FREIHERR KEMPEN VON FICHTENSTAMM, PRESIDENT OF THE ROYAL IMPERIAL COMMISSION ON GUN-COTTON, JUNE, 1863. (1) " Differ- ence between the French Gun-Cotton and Baron Lentfs. Accord- ing to the method pursued by the French Commission, the raw cotton was immersed in the acid mixture for one hour. Baron Lenk leaves his cotton forty-eight hours in the acid bath. The French cotton was afterwards dipped in running water for an hour or an hour and a half. Baron Lenk's gun-cotton lies four, six, or eight weeks in a stream. The French cotton had, after washing, so much free acid left, that wood-ash lye (a solution of carbonate of potash, therefore) was neutralized by contact with it, and after long use became sour. Baron Lenk's cotton is so freed from acid by long immersion, that a two per cent, solution of potash, in which two cwt. of gun-cotton had been boiled, has lost none of its alkaline properties that is to say, that the cotton was completely free from acids, as experiments wholly accordant with those of the Imperial (Austrian) Engineers' Committee fully demonstrated. The French gun-cotton having been prepared in a manner so different, it must necessarily have had a different composition to that of Baron Lenk's ; hence it is clear that the French experimental results cannot, without considerable reserve, be accepted as precedents." 958. "If this analysis (Tables 143 and 144) differs somewhat from the theoretical formula of the trinitro-cellulose, the circum- stance must be remembered that cotton is not pure cellulose, but that it consists of long-extended vegetable cellules, in which there is always a little albuminous substance containing over 50 per cent, carbon, and 7 per cent, hydrogen, the presence of which even in such quantities easily increases the percentage of carbon and hydrogen. The treatment of soluble glass has no influence on Baron Lenk's gun-cotton, it being previously free from acids. GUN-COTTON. 823 TABLE CXLIII. ANALYSIS OP AUSTRIAN GUN-COTTON. LABORATORY OF EN- GINEERS' COMMITTEE, 1861. In 100 parts. Trinitro-cellulose, calculated. No. 4. Carbon 24.. -j 1C I 2.-1 *5 3*O UNIVERSITY LABORATORY, 1863. In 100 parts. No. 3. 1856. No. 6. 1860. No. 14. 1862. Dinitro- cellulose, calculated. 1. 2. 1. 2. 1. I 2. 3. Carbon 24.4 *? 24.5 24-6 24.2 23.6 23.9 24-1 1 28-6 3. a y i Gun-cotton is always put into comparison as an explosive com- pound with gunpowder ; but it must be remembered that one of the component parts of gunpowder (charcoal) is most irregular in quality, especially where the primitive method of preparing it is followed. Still, in theoretical disquisitions upon gunpowder, charcoal is taken into account as pure carbon." 959. (3) " In the magazines of gun-cotton at the Neustadter Haide, there are stores of various years. In the laboratory of the University there are samples of Hirtenberg gun-cotton of three several years, which have been examined by the above- named artillery officers, and they have been found not to differ materially in their composition from trinitro-cellulose. (See Table 144.) 9OO. " If these results (Table 144) are compared with each other, there can be no right to say that Hirtenberg gun-cotton alters by keeping. They agree as far with each other as analyses of the same material usually do. It is to be regretted, on this as on many other accounts, that during the last twelve years such analyses were not frequently repeated. If the opponents of gun- 824 ORDNANCE. APPENDIX. TABLE CXLIV. ANALYSIS OF GUN-COTTON OF VARIOUS YEARS. NO. a No. 6. No. 14. In 100 parts. Trinltro cellulose, calculated. 1856. 1860. 1862. 1862. 1. 24.4 a. 7 2. 1. 2. 1. 2. 3. Carbon . 24.3 2.3 24.5 2-8 24.6 2-6 24. i a. 7 23.6 2-6 *3'9 2.4 24-1 2-4 cotton, in performing an adverse experiment, lieat the substance in a test-tube up to 100 C., and holding litmus-paper over it, deduce from redness of the latter that gun-cotton changes after long keeping, they merely prove thereby that gun-cotton changes at 100 C. Of an explosive compound, it can only be required that it shall not deteriorate within certain limits of temperature, a requisition amply fulfilled l>y Lentts gun-cotton. " Some varieties of gun-cotton, if enclosed together with litmus paper in a tube, often manifest an acid reaction at ordinary tem- perature. This may arise from various causes. There may exist, for example, free acids. These acids may be the result of nitro- gen partially oxidized, and may result from imperfectly worked cotton. This assumption granted, the phenomenon is explained, and the cause easily avoided. It may arise from decomposition of the gun-cotton, atmospheric dampness having brought about a partial reconstitution of the cellulose." OO1. (4) "But some specimens of Lenk's cotton do not even yield traces of decomposition. A parcel of Hirtenberg cotton was laid for six weeks in a pond, and not subsequently treated with potash. It was then deposited in a running stream, after- wards exposed for one month to the air, being subjected to all the various influences of dew, rain, and sun, day and night contin- uously. It retains all its original explosive qualities, and fails to redden litmus-paper, even though the latter be wrapped in a mass of this cotton and allowed to remain for many days. The results of an analysis of this cotton were almost identical with the cal- GUN-COTTON. 825 ciliated elements of trinitro-cellulose, as the following table makes apparent: Calculated. Found. Carbon 24-2 24-4 Hydrogen 2-3 2'8 9G2. (5) "Temperature at which Gun-Cotton ignites. The rejection of gun-cotton, in consequence of the changeable nature, or explosive quality of the material at low temperatures, is so thoroughly and decidedly contradicted in the Report of Baron von Ebner, that it would be superfluous to go any further into this question the lowest explosive temperature of the Hirtenberg gun-cotton being therein fixed at 136 C., a temperature which, practically, cannot raise any doubts against the use of gun-cotton." 963. (6) "Experimental Proofs demonstrate that Lentis Gun- Cotton is not spontaneously combustible. The history of gun-cotton, as chronicled by chemists and artillerists, short though the history be, is so full of records of explosion under unexpected circum- stances, that an unbiased mind can hardly fail to be impressed with the belief that, amongst the ordinary conditions of military practice, there may be some competent to induce the spontaneous combustion of this material. Nevertheless, the experience of Baron Lenk, acquired during a period extending over more than ten years, is more pregnant with reliable testimony than can be found in the entire remaining history of this material. "The manufacture of gun-cotton in Hirtenlterg consists of a num- ber of perfectly harmless operations / and it is remarkable that, contrary to what happens with gunpowder, if fire be not actually applied, explosion is impossible. All operations are so arranged that the material acted upon is in a moist or wet condition hence not explosive. Drying takes place in a capacious building, on every side open to the air. The last process of drying is car- ried out in the drying-chamber, where it is effected by a stove situated on the outside, distributing its heat to the building by earthenware pipes drying being thus insured through a gentle warmth. The gun-cotton next goes either into a magazine to be packed away in chests, or is at once prepared for ammunition. 826 ORDNANCE. APPENDIX. In this magazine, Hirtenberg cotton has been stored for a period of twelve years, and not a single instance of explosion has taken place. How many powder-mills have exploded in that time ? In Prussia, however, a drying-chamber has lately blown up. Your Excellency has officially been informed, that in Prussia they have worked for eight years with gun-cotton, and not a single explosion has occurred except the last-named. In the Prussian drying-chamber referred to, a stove with iron smoke-pipe was used a sufficient explanation of the misfortune. " During twelve years we have prepared gun-cotton at Hirten- berg for ammunition that is, for yarns, spun ropes, and threads twisted and woven. One single case of explosion has occurred in the course of Baron Lenk's manufacture, the result of improper speed of working the spinning machinery. Now, the circum- stance hardly need be insisted on, that gunpowder as well as gun- cotton can be exploded by friction. Gun-cotton has been used for military purposes now more than twelve years ; it has also been employed for mining and blasting. It has been subjected to every variety of transport. Packed in black wooden chests, it has been exposed to sunshine for months together all this with- out one single accident. In the face of such testimony, it cannot be said that gun-cotton manifests any tendency to explode spon- taneously." 964. (7) " Lieutenant von Karolyi's analysis of the gases of combustion of Lenk's gun-cotton, which he made in the Chemical Laboratory of the Engineers' Corps Committee, may be seen in the 'Report of the Imperial Academy of Science,' vol. xlvii., Mathematical and Physical Part, p. 59, and is given in Table 145, in which the gases of combustion of powder according to Bunsen (vide Poggendorff, 4th series, vol xii., p. 131) are cited in comparison with those of gun-cotton. " If we compare the gases of gunpowder with those of gun- cotton, we easily see that the chemical action of the product of combustion of gun-cotton on the sides of the barrel, if there exists any action at all, must be smaller than with the use of gunpowder, because they are less oxidizing gases than those of gunpowder. GUN-COTTON. 827 TABLE GXLV. ANALYSIS OP THE GASES OF GUNPOWDER AND GUN-COTTON. Gases of Combustion. Volume per cent. Bunsen. Karolyi. Sporting powder. Eifle powder. Ordnance powder Gun-cotton. Nitrogen Carbonic acid Carbonic oxide Hydrogen Sulphuretted hydrogen Oxygen Light carburetted hydrog N 41.1 52-7 3-9 I 2 0-6 O C2 35-3 48.9 5 -a 6.9 67 37.6 42.7 IO2 5-9 0.86 12 20 *9 3 Carbon I Water 25 7 7 .8 o a 8 37 a C0 2 ... CO H HS o en 3 .oa a . 7 Should, therefore, bronze barrels be ' burnt out' by the use of gun-cotton, cast steel may be then used instead of bronze, which, in fact, has been successfully done. Moreover, bronze gun-barrels have withstood a sufficient number of rounds by using an adequate charge of gun-cotton with elongated cartridges. In this way no alteration of the bore prejudicial to the correctness of aim has taken place. From the steel barrel of a rifle, forty rounds have been fired with gun-cotton cartridges, which have hit the target 300 yards distant in an unexceptionable manner. After the said number of rounds, the barrel was internally as clean and polished as a mirror. It appears, then, that this problem is solved in a, general and satisfactory manner." 9 60. (8) " Application of Gun-cotton to Mining War/erne. Gun-cotton is also used for mining purposes and mining warfare. On this subject nothing but what is favorable has been reported by the Imperial Engineers (vide Communications of the R. I. Engineers' Committee, 1861, vol. i., by Moritz Baron von Ebner, Colonel of the Engineers). However, it is said that the gases of gun-cotton were more poisonous in mines than those of gunpowder, and therefore the use of gun-cotton for mining warfare is not to be recommended. If we compare the result of Lieutenant Karolyi's 828 ORDNANCE. APPENDIX. analysis of the combustion-gases of gun-cotton with those of gun- powder as above given, we observe that both of them contain irrespirable gases ; further, that they contain qualitatively the same sort of irrespirable gases ; and although.the relative quanti- ties of some of the gases from powder and gun-cotton are different, the effect of those gases leads to the same practical result, viz., that, after blowing up a mine, one cannot without danger ap- proach the spot of the explosion before renewing the air by venti- lation. In this respect, we may say that the gases of gun-cotton will be more quickly removed by ventilation than those of gun- powder, because the first-named contain a greater quantity of gases easily dissipated, since 100 pounds of gunpowder contains 08 pounds of fixed solid matter, which alone suffices to make respiration almost impossible. It is not probable that an explo- sive compound will be found which will produce any other but irrespirable gases. * It is one and the same in practice, whether a cellar contains 40 per cent, of carbonic acid and 10 per cent, carbonic oxide, or 30 per cent, carbonic oxide and 20 per cent, carbonic acid, inasmuch as no one could, without danger of suffocation, enter such a cellar. Both the gases of gun-cotton and of gunpowder, according to Karolyi, may be ignited by a match." 966. Gun-Colt on Manufacture and Experiments in Eng- land. Soon after the meeting of the British Association, in 1863, where the facts embodied in the foregoing report were first made public, the manufacture of gun-cotton was commenced at Stowmarket by Messrs. Prentiss, under the direction of Mr. Revy, the partner of General Lenk. The first order for gun-cotton was given to Messrs. Prentiss by the author, on behalf of the United States Navy Department, which has long been aware of the value of this material, and anxious to make a thorough test of its qualities. The trial of this gun-cotton has not yet been completed. 967. The first gun-cotton made at Stowmarket was subjected (Feb. 19, 1864) to the following trial, which was witnessed by the writer ; its results were not made public at the time : GUN-COTTON. 829 A palisade was formed of 12 piles of green English poplar, set in a trench 3 ft. deep, and rammed up with earth. The piles were 18 to 20 in. diameter, and averaged 7 ft. high. A 12-in. elm log, 14 ft. long, was. laid at the foot of the palisade, and a 21-in. poplar log, of the same length, was laid against the elm log. A 12-in. cylinder, made of i--in. wrought-iron, with flat heads, bolted on, and containing 24 Ibs. of gun-cotton, was laid on the elm log, 3 in. removed from the largest (20-in.) pile, and 30 in. from the ground. A gun-cotton fuze (a gun-cotton yarn, enclosed in a rubber tube), was laid over the snow, from the box 'to a ditch 150 yards off, arid lighted. There was no smoke, and no visible sign of work, except the disappearance of the central portion of the pali- sade ; but the report was like that of a heavy rifled gun. FIG. 423. Palisade opened by 25 Ibs. of gun-cotton. From a photograph. The opening made in the palisade was 3 ft. 2 in. at the bottom, and 4 ft. 11 in. at the top. The 20-in. pile was not torn down nor broken down, nor shattered from end to end ; the central portion of it disappeared altogether ; the top end was thrown twenty feet to the rear; the stump was bent back to an angle of 45. The part of the elm log upon which the box lay also disappeared. The ends were moved a few feet ; the inner ends looked as if they had been chewed off. The 21-in. horizontal log was thrown 25 ft. forward, and appeared to have been gnawed half in two in the 830 ORDNANCE. APPENDIX. middle. The earth was broken and driven down for 6 feet around the point of the explosion. The piles next to the one carried away were shattered and bent back and sideways to an angle of about 20. 968. The peculiar action of gun-cotton, as illustrated by this experiment, is: 1st. The intensity of its local effect. 2d. The small range of its action. Another well-established fact is, that the stronger the chamber in which it is confined, the more violent is its local effect. The box of iV m - iron, with flat heads, offered such a slight resistance to increase of volume, that the effect on the palisade, complete as it was, afforded no measure of the actual expansive force of the material. 969. On July 23, a similar experiment was made at Newcas- tle-on-Tyne, in presence of many military men and other specta- tors. The results are shown by a comparison of Figs. 424 and FIG. 424. Palisade before the explosion oi'a 2o-lb. box of guti-cotton. From a photograph. 425. The stockade was constructed of a double row of timber, the first consisting of 6 balks, each 10 ft. long by 12 to 14 in. square ; the timber backing being formed of 5 balks, 9 to 10 in. square. These balks were sunk about 4 ft. into the ground and firmly bedded. Two logs, 7 ft. long and 14 in. square, were laid in front of the stockade. The timber was the best Memel. The box, or shell, was 16 in. long and 12 in. in diameter, made of j-in. iron, and containing 25 Ibs. of gun-cotton. The shell was lighted by electricity. The four upright timbers nearest it were blown GUN-COTTON. 831 I 832 ORDNANCE. APPENDIX. away nearly level with the ground, one fragment having been thrown 130 yards. One of the horizontal timbers was torn to pieces ; the other was thrown about 40 yards. The ground under the shell was sunk about 6 inches. The fence of the adjacent railway was broken, but no part of it was removed ; a few win- dows in a building 500 to 600 yards off were broken. 970. Gun-cotton is now regularly employed in England for mining purposes, and is largely ordered by various governments. 971. Nature and Mechanical Application of Gun-Cotton. In a recent paper before the Royal Institution, Mr. Scott Russell thus clearly set forth the nature and action of gun-cotton, under various treatment, and the manner of adapting it to experimental and to mining uses, and to ordnance: # # * a r h Q -ft rs t f orm which General Lenk bestowed on gun- cotton was that of a continuous yarn or spun thread. Gunpow- der is carefully made into round grains of a specific size. Gun- cotton is simply a long thread of cotton fibre, systematically spun into a yarn of given weight per yard, of given tension, of given specific weight. A hank of a given length is reeled, just like a hank of cotton yarn to be made into cloth, and in this state gun- cotton yarn is bought and sold like any other article of commerce. 972. "This cotton yarn, converted into gun-cotton, may be called, therefore, the raw material of commerce. In this form it is not at all explosive, in the common sense of the word. You may set fire to a hank of it, and it will burn rapidly, with a large flame ; but if you yourself keep out of reach of the flame, and keep other combustibles beyond reach, no harm will happen, and no explosion or concussion will result. If you lay a long thread of it round your garden walk at night, disposing it in a waving line, with large balls of gun-cotton thread at intervals, and light one end of the thread, it will form a beautiful firework, the slow lambent flame creeping along with a will-o'-th'-wisp-looking light, only with a measured speed of 6 in. per second, or 30 ft. a minute ; the wind hastening or retarding it, as it blows with or against the line of the thread. This is the best way to commence an acquaint- ance with this interesting agent. * * * GUN-COTTON. 833 973. " The second form of gun-cotton is an arrangement compounded out of tlie elementary yarn. It resembles the plaited cover of a riding- whip : it is plaited round a core or centre, which is hollow. In this form it is match-line, and, although formed merely of the yarn plaited into a round hollow cord, this mechanical arrangement has at once conferred on it the quality of speed. Instead of travelling as before only 6 inches a second, it now travels 6 feet a second. 974. " The third step in mechanical arrangement is to en- close this cord in a close outer skin or coating, made generally of India-rubber cloth, and in this shape it forms a kind of match- line, that will carry fire at a speed of from 20 to 30 feet per second. * * * 974 A. " The cartridge of a common rifle in gun-cotton is noth- ing more than a piece of match-line in the second form, enclosed in a stout paper tube, to prevent it being rammed down like pow- der. The ramming down, which is essential to the effective ac- tion of gunpowder, is fatal to that of gun-cotton. To get useful work out of a gun-cotton rifle, the shot must on no account be rammed down, but simply transferred to its place. Air left in a gunpowder barrel is often supposed to burst the gun ; in a gun- cotton barrel it only mitigates the effect of the charge. The object of enclosing the gun-cotton charge in a hard strong paste- board cartridge is to keep the cotton from compression and give it room to do its work. 975. " It is a fourth discovery of General Lenk, that to ena- ble gun-cottom to perform its work in artillery practice, the one thing to be done it to ' give it room.' Don't press it together don't cram it into small bulk ! Give it as least as much room as^ gunpowder in the gun, even though there be only one-third cr- one-fourth of the quantity (measured by weight). One pound of' gun-cotton will carry a shot as far as 3 or 4 pounds of gunpow- der ; but that pound should have at least a space of 160 1 cubic inches in which to work. " This law rules the practical application of gun-cotton to ar- tillery. A cartridge must not be compact, it must be spread out 53 834 ORDNANCE. APPENDIX. or expanded to the full room it requires. For this purpose, a hollow space is preserved in the centre of the cartridge by some means or other. The best means is to use a hollow thin wooden tube to form a core ; this tube should be as long as to leave a suf- ficient space behind the shot for the gun-cotton. On this long core the simple cotton yarn is wound round like thread on a bob- bin, and sufficiently thick to fill the chamber of the gun ; indeed, a lady's bobbin of cotton thread is the innocent type of the most destructive power of modern times only the wood in the bobbin must be small in quantity in proportion to the gun-cotton in charge. There is no other precaution requisite except to close the whole in the usual flannel bag. " The artillerist who uses gun-cotton has therefore a tolerably simple task to perform if he merely wants gun-cotton to do the duty of gunpowder. He has only to occupy the same space as the gunpowder with one-fourth of the weight of gun-cotton made up in the bobbin as described, and he will fire the same shot at the same speed. This is speaking in a general way, for it may require in some guns as much as one-third of the weight of gun- powder and eleven-tenths the bulk of charge to do the same work ; a little experience will set the exact point, and greater experience may enable the gun-cotton to exceed the performance of the gun- powder in every way. 976. " The fifth principle in the use of gun-cotton is that in- volved in its application to bursting uses. The miner wants the stratum of coal torn from its bed, or the fragment of ore riven from its lair ; the civil engineer wishes to remove a mountain of stone out of the way of a locomotive engine ; and the military engineer to drive his way into the fortress of an enemy, or to destroy the obstacles purposely laid in his way. This is a new phase of duty for gun-cotton it is the work of direct destruction. In artillery you do not want to destroy directly, but indirectly. You don't want to burst your gun, nor even to injure it : and, we have seen, in order to secure this, you have only to give it room. " The fifth principle, therefore, is, to make it destructive to cause it to shatter every thing to pieces which it touches, and for GUN-COTTON. 835 this purpose you have only to deprive it of room. Give it room, and it is obedient ; imprison it and it rebels. Shut up without room, there is nothing tough enough or strong enough to stand against it. " To carry this into effect, the densest kind of gun-cotton must be used. It must no longer consist of fine threads or hollow tex- tures wound on roomy cores. All you have to do is to make it dense, solid, hard. Twist it, squeeze it, ram it, compress it : and insert this hard, dense cotton rope or cylinder or cake in a hole in a rock, or the drift of a tunnel, or the bore of a mine ; close it up and it will shatter it to pieces. In a recent experiment, 6 oz. of this material, set to work in a tunnel, not only brought down masses which powder had failed to work, but shook the ground under the feet of the engineers in a way never done by the heavi- est charges of powder. * * * " To carry out this principle successfully, you have to carry it even to the extreme. Ask gun-cotton to separate a rock already half-separated, it will refuse to comply with your request. Give it a light burden of earth and open rock to lift, it will fail. If you want it to do the work, you must invent a ruse you must make believe that the work is hard, and it will be done. Invent a difficulty and put it between the cotton and its too easy work, and it will do it. The device is amazingly successful. If the cotton have work to do that is light and easy, you provide it with a strong box, which is hard to burst, a box of iron for example ; enclose a small charge, that would be harmless, in a little iron box, and then place the box in the hole where formerly the charge exploded harmless, and in the effort it makes to burst that box, the whole of the light work will disappear before it. * * * 977. "It is, therefore, the nature of gun-cotton to rise to the occasion and to exert force exactly in proportion to the obstacle it encounters. For destructive shells this quality is of the high- est value. You can make your shell so strong that nothing can resist its entrance, and when arrived at its destination no shell can prevent its gun-cotton charge from shivering it to fragments. 978. Mr. Scott Russell's Theory of the Explosion of 836 ORDNANCE. APPENDIX. Guii-Cotton. " In conclusion, I may be asked to say as a me- chanic what I think can be the nature and source of this amazing power of gun-cotton. In reply let me ask, who shall say what takes place in that pregnant instant of time when a spark of fire enters the charge, and one hundredth part of a second of time suffices to set millions of material atoms loose from fast ties of former affinity, and leaves them free every one to elect his mate, and uniting in a new bond of affinity, to come out of that cham- ber a series of new-born substances ? Who shall tell me all that happens then ? I will not dare to describe the phenomena of that pregnant instant. But I will say this, that it is an instant of in- tense heat one of its new-born children is a large volume of steam and water. When that intense heat and that red-hot steam were united in the chamber of that gun and that mine, two pow- ers were met, whose union no matter yet contrived has been strong enough to compress and confine. When I say that a gun-cotton gun is a steam-gun, and when I say that at that instant of intense heat the atoms of water and the atoms of fire are in contact, atom to atom, it is hard to believe that it should not give rise to an explosion infinitely stronger than any case of the generation of steam by filtering the heat leisurely through the metal skins of any high-pressure boiler." 979. The same subject was thus referred to by Mr. Scott Kussell before the British Association in 1863 : " How was it that in gun- powder and in gun-cotton where there were equal quantities of gas put in, the gas in the case of gunpowder was raised to an enormously high temperature, and came out at an enormously high pressure, showing that they had gas enormously expanded by heat ; whereas in the case of gun-cotton the gas came out quite cool, so that you might put your hand upon it, and the gun itself was quite cool ? He (Mr. Kussell) had a theory. Steam was a gas, and steam expanded just by the same laws as other gases did. A great deal of the gas of gun-cotton happened to be steam. Let them conceive 100 Ibs. of gun-cotton shut up in a chamber that just held it. They had got there all the gases that had been spoken of, but they had also got 25 Ibs. of solid water about one- HOOPED GUNS. 837 third of a cubic foot of water in that chamber. What did they do with it ? They put fuel, they put fire to it. They heated the whole remaining pounds of patent fuel. If, then, they considered the gun-cotton gun as the steam-gun, they got rid of two difficul- ties. They would have, first, the enormous elasticity of steam ; and secondly, they would get the coolness of it. They all knew that if they put their hand to expanded high-pressure steam, it had swallowed up all the heat and came out quite cool. He believed that the gun-cotton gun was neither more nor less than Perkins's old steam-gun with only this difference, that you bottled up the fuel and water, and let them fight it out with each other. They did their work and came out quite cool. He hoped, how- ever, that it was understood that he did not dogmatize. He put all he had said with a note of interrogation upon it." GUNS HOOPED WITH INITIAL TENSION. THIERY, 1834. TRANSLATION OF PAGES 153 TO 163, PUBLISHED IN 1834.* 98O. " Cannons of Cast Iron, with Envelope of Wrought Iron. What we haye called to mind, shows sufficiently how satisfactory the employment of cannons of cast iron would be for the service of land artillery, if in addition to the considerable economy which would result from it, and the ' extreme resistance which these pieces of ordnance would offer to the blows of bullets, one could render them perfectly sure in firing. " But as long as this last condition shall not be fulfilled ; as long as cannons of cast iron shall be subject to burst unexpectedly into fragments, considerations of humanity joined to military considerations, impose the law of rejecting from our materiel engines exposing the life of our own soldiers to constant dangers, * "Application of Iron to Artillery Constructions," by A. Thiery, Chief of Squadron. Paris, 1834 and 1840. 838 ORDNANCE. APPENDIX. and the explosions of which, at the decisive moments of combats, would compromise the success of our arms. " However, the insufficiency of the duration of bronze cannons for the service of the attack and defence of places, demands equally artillery to seek, by all means possible, to put itself in possession of pieces of ordnance less imperfect than those which it is reduced to make use of. " To attain the solution of this problem, we have thought that the combination of wrought iron, and cast iron, which has con- tributed so much to the power of steam-engines, could also present happy results in the construction of cannon. 981. "It is in this view that we have proposed the trial of a cannon of cast iron, with envelope of wrought iron, adding to the resistance of the piece of ordnance, and preserving in ex- plosions from the danger of fragments. " We have seen that the opinion of Monge was pronounced in favor of wrought iron, and that the difficulty of execution was in the eyes of this celebrated scholar the only cause which should cause the rejection of the employment of this metal in the manu- facture of ordnance. The progress made since the time of Monge, in the art of forging iron, has, without doubt, diminished these difficulties, but they are not sufficiently removed by any practice in this kind of construction. Nevertheless, while admitting the possibility of success, one should bear in nu*nd that cannons of wrought iron, superior in tenacity to those in bronze, would, in respect of durability, be very inferior to cannons of cast iron, much more costly, and much more subject than these last to be damaged by oxidation and the blows of bullets. " Since cast iron is perfectly satisfactory against the blows of projectiles; against the effects of oxidation; and that it has, in addition, the advantage of being easily produced, and at a cheap rate, in all the forms desirable, it is natural to form of it the bore of cannons, and to make this metal enter into the composition of pieces of ordnance in as great a proportion as can comport with security in firing. . " A peremptory reason imposes, on another account, the HOOPED GUNS. 839 necessity of forming of cast iron the greater part of the thickness of a piece of ordnance of which it constitutes the interior. This metal having but very little elasticity, resists the explosion of the powder principally by virtue of its resistance to extension ; this resistance once overcome, the cast iron would not evidently find any assistance against rupture in a surrounding body more elastic, and which yields beyond the limit at which its cohesion is de- stroyed. All that one can hope for from an elastic envelope com- pressing the cast iron, is that it augments by the compression the resistance to extension of this hard, rigid, brittle metal, but not that it should cause it to participate in elastic properties which are not in its nature. " These considerations appear to us to have been lost from view in the trial, made in 1829, of the cannon of bronze with a body of cast iron. The body of cast iron consisted of a sleeve of a thick- ness so small that one could not expect from it any resistance against the expansive force of the powder. It should then have been necessary, to sustain the stress of firing, that this frail tube of cast iron should receive from the surrounding bronze an extra- ordinary power, and one does not see how this phenomenon would possibly have been effected, as the cast iron, immerged in the melted bronze, should have followed the expansion (by heat) ; and that the operation of cooling should annul the effect of the com- pression which should have resulted from the difference in the contractions of these two metals.* " Thus it was not necessary to wait long for the rupture of these tubes of cast iron. After some shots, they split, and did not per- mit further firing without danger. 983. " By employing for the envelope, wrought iron, in place of bronze, the chances of success are altogether otherwise ; not only because the wrought iron has a tenacity double that of * " The linear dilatation of cast iron, wrought iron, and copper, for an interval of 100 degrees, follows the following progression: Cast iron 0-00112 Wrought iron 0*00122 Red copper 0-00171 840 ORDNANCE. APPENDIX. bronze, but because the hooping of wrought iron can be effected mechanically in such manner as to consolidate the system much more than the causing of the metals to adhere only by the opera- tion of fusion. 984. " The means which naturally first offer for hooping a cannon of cast iron with wrought iron, would be to cover it with a series of hoops placed upon it while hot, side by side, and which would thus adhere to this piece of ordnance with the whole force of the contraction a force which might become excessive by carrying the temperature of the hoop of WTO ugh t iron to a very high degree. But on the one part, this process would not permit the clothing of the cannon at the space of the trunnions; and on the other, would not secure completely against the dangers of fragments, even in the hooped parts. 985. " The examination of a great number of fragments of guns of cast iron burst in the proof at the Koyal Foundry at Nevers, has convinced us that these guns could explode in the whole ex- tent of their bore, and that a series of hoops placed side by side, which were not bound to each other by any thing, would only present incomplete pledges of security in firing. " The greater portion of guns break at the position of the charge. In this case, the rupture takes place generally following two or three planes, passing through the vent, forming with the axis an angle approaching a right angle. The fragments, then, are composed of the breech, projected behind to the right or to the left according to the inclination of the planes of rupture, and of some fragments of the first reinforce thrown out laterally. " In this circumstance, it is evident that hoops placed side by side would be of little preservative effect. The breech, torn off from the body of the cannon, would not the less be projected in the rear, and the hoops, detached by reason of this violent rup- ture, would add probably to the number of fragments. " Although the ruptures generally take place at the position of" the charge, there are not the less examples of their being seen to take effect upon every other part of the bore chamber. The suc- cessive burning of the powder carries the most violent explosion of HOOPED GUNS. 841 the charge in advance of the bottom of the bore. The adhesion of the projectiles to the sides of the bore, an adhesion which can occur from the distortion of these projectiles or the presence of a foreign body in fine, the defects of manufacture, are causes which explain sufficiently the possibility of these ruptures. "After these facts, it has appeared to us that in order that an envelope of wrought iron should accomplish efficaciously the end which we principally propose, that of becoming a preservative against fragments, it is necessary that it shall extend throughout the entire length of the pieces of ordnance, that it shall adhere perfectly to them, and shall itself form but a single and one body, all the parts of which become solid from the resistance. 986. " In consequence,* we have conceived the idea of com- posing our envelope of wrought iron immediately upon an arma- ture of longitudinal bars of the length of the cannon, and having spaces between them of about twenty centimetres. It is in this armature that we have cast the truncated cone of cast iron in which the bore has been bored. " By previously raising the temperature of the armature of wrought iron, and by means of some very simple arrangements for executing the matter, the operation of casting the cast iron within the longitudinal bars of wrought iron, has been accomplished with- out any difficulty. The truncated cone of cast and wrought iron which resulted from it, has not shown any blow holes ; the bars, kept in place by some hoops of wrought iron, have been immerged in the cast iron ; the fusible portions contained in these bars have become united to the cast iron, and the welding has been inti- mately effected between all the parts constituting this base of the cannon of wrought and cast iron. " The bars of wrought iron have become steeled at their sur- faces, but have preserved their fibre in the interior. The cast iron compressed in the wrought iron is solidified into fine compact "homogeneous grains, presenting the appearance of the hard rolls cast in chills. We hope that its resistance has been increased. 987. " It is upon this truncated cone of cast and wrought iron * See Fig. 426. 842 ORDNANCE. APPENDIX. that we have effected the hooping by hoops placed over it at a welding red. Nicks made at various distances in the longitudinal bars, and in the cast iron, have secured the connection of the system. " The hoop carrying the trunnions has been formed of two parts, in each of which the trunnions have been previously raised. This piece has been executed at an ordinary forge, without presenting great difficulties. The trunnions were turned before placing the hoop. In a manufacture on a large scale, the ring carrying the trunnions would not require a costly labor. It can- iiot be considered an obstacle to the production of a complete envelope of wrought iron. " The hoop of the trunnions having been put in place, the hoop- ing of the chase has been continued, taking care to bind the hoops always to the longitudinal bars by the nicks. " By means of these arrangements, one should believe there should be no more danger of dreading fragments of such a gun when exploding. O88. "In fact, if it be at the position of the charge that the rupture takes place, in order that the breech may be projected in the rear it is necessary that the bars forming the longitudinal armature should break all at a time, or should be torn from the cast iron in which they are welded and maintained by the pressure of the series of hoops placed when hot. " In order that the gun should open at any part of the bore, it would be necessary, first, that many rings should be broken ; and in order that fragments should be projected through the opening, it would be necessary for the longitudinal bars to break at the same time. " The effort necessary to produce, suddenly, similar tearings away of the wrought iron at the same time as the explosion of the cast-iron, is beyond calculation.* There is no doubt that long * "In our 8-pound cannon there are twelve longitudinal bars of 50-15 millimetres, (about two in.) the combined resistance of which may be estimated at 300000 kilo- grammes (about 600000 pounds). The rings are 3G in number, of 50-30 millimetres, (about two in.). Reducing, by reason of the welding, their resistance to 20 kilo- grammes per square millimetre of transverse section, one finds for each of them a power of 30000 kilogrammes (about 60000 pounds)." HOOPED GUNS. 843 before this effect should be produced, the distension of the hoops would precede the explosion. " We would, in addition, remark that everywhere where the fracture should seek to take effect, whether longitudinally or transversely, it would always meet with the wrought iron opposing its resistance in the direction of its length. " With such a combination, it is difficult for one to be exposed to projections of fragments by reason of an explosion. It is prob- able that the portion of the cast iron happening to burst, the envelope of wrought iron would contain its fragments, would let them issue forward, and would hinder their dispersion in the enclosure of the battery. 989. "We have, up to the present time, considered the envelope of wrought iron as the sole preservative against frag- ments ; we look forward to more from it. The examples which we have stated of the extraordinary resistance acquired by pieces of cast iron compressed in wrought iron, permit us to hope for a similar result from the series of hoops placed while hot upon the truncated cone of cast or wrought iron in which the bore is bored. The strong compression, exerted by the hoops adhering with the whole force of the contraction upon this portion of cast iron, should of necessity increase its resistance to extension. "It is in conformity with this increase of strength that the thicknesses of the body of cast iron and the envelope of wrought iron should be regulated, and that all the rules for the construc- tion of pieces of ordnance of wrought and cast iron should pro- ceed. Experience alone can guide one to the estimation of these thicknesses, but the specific gravities of bronze and cast iron being in the ratio of 7'SO to 7*20, one would believe that one will be able to construct cannon of wrought and cast iron of the same length within the weights of bronze cannon of large calibres. 990. " We have not pretended to fulfil this condition in our first trial. The fear of not succeeding and of incurring uselessly heavy expenditures, has compelled us to make choice of an eight- pound cannon. " To keep within the weight of a field-piece of this calibre, we 844 ORDNANCE. APPENDIX. would have to reduce the cast iron and the wrought iron to pro- portions so low, that, giving way in the firing, one would not be able to come to any conclusion as to the application to large cali- bres which it is, above all, necessary to improve. " If the proofs made upon our eight-pound cannon, having the thickness of bronze in cast iron and overlaid with wrought iron, succeed, one could conclude upon the possibility of manufacturing in this way without a notable increase of weight, cannons of large calibres having the same dimensions and length as those of bronze. OO1. "If, after a prolonged firing, one should recognize in this eight-pound cannon an excess of strength, it should be bored to a 12-po.under, and if it resisted sufficiently after this reduc- tion of weight, the system would be applicable to field artillery. *' The piece for the trunnions, of wrought iron, should not, we repeat, be the subject of an objection to the adoption of cannon of cast iron with an envelope of wrought iron, because nothing hinders the limitation of this envelope to the first reinforce, leav- ing the trunnions and f>r .\\ird part, in which explosions are rare and less formidable, of cast iron ; this forward portion might, on the other hand, be equally hooped. 992. " This system would be to our eyes less complete, and it appears to us that the difficulty of manufacturing the trunnions of wrought iron being once removed, the adoption of a ring carry- ing these trunions presents a very positive advantage. "With this ring, the existence of the piece of ordnance is no longer depend- ent upon the feeblest part of it; a trunnion of wrought iron would probably never break ; but admitting that it should be broken, one could replace it with another by detaching the hoops of the chase. 993. " The manufacture of pieces of ordnance of cast iron, with an envelope of wrought iron, although less economical than that of cannons of cast iron, would be infinitely less costly than that of guns of bronze. One could estimate that in a manufac- ture on a large scale they would amount to one-fourth of the value of these last. HOOPED GUNS. 845 " The production of these cannons would be at the same time easy and rapid, because it would reduce 'the moulding to some very simple operations." THIERY. 994. Cannons of Cat Iron witli Envelope of Wrought Iron. (Pages 137 to 146, published in 1840.) After mentioning the armament needed for France, M. Thiery says : " If the experi- ments which we have stated, should have for their consequence the rejection of cannons of cast iron from all the services, one perceives to what enormous sacrifices the treasury would be con- demned, since the expense of the wanting (21136176) would be increased from the difference between the price of bronze and that of cast iron, for all the pieces of ordnance which we have thus far permitted to be of iron. " But, as we have proposed, we think that we should not yet despair of the solution of the question of cannons of iron, and that this solution would be easily obtained, if, in place of limiting our- selves to the exclusive employment of cast iron, we should have recourse to the combination of cast iron and wrought iron. 99*5. " Already we have constructed in 1833, with complete success as to execution, a trial cannon upon the basis of this proposition. " Putting to a profitable use the rigidity of cast iron to constitute the bore of the piece of ordnance, the elasticity of wrought iron to surround it with an envelope as a preservative against explosions, we have cast the interior of the gun of cast iron immediately within a longitudinal armature of wrought iron, binding together all the parts in the direction of the length ; then we have afterwards hooped it transversely with hoops of wrought iron, put in place while hot, and adhering by the contraction. " We have set forth in the FIRST PART of the APPLICATIONS OF IRON TO THE CONSTRUCTION OF ARTILLERY, the facts of experience 846 ORDNANCE. APPENDIX. which brought us to test this trial ; we will here mention some of them : 99 O. " Some pipes for carrying water, put up in the foundry of Fourchambault, not having borne the receiving proof at the hydraulic press, they conceived the idea, in order to make them useful, of hooping them with hoops of wrought iron placed while hot over their fissures and compressing them by the contraction. The results surpassed their expectations. These pipes showed a resistance to every proof, and when they wished to destroy them in order to remelt them, the means used in parallel cases were not sufficiently powerful ; they had to have recourse to powerful sledge-hammers, and the rings of wrought iron adhered so strongly to the cast iron, that it was necessary to break them to withdraw the metal from them. " A hoop of cast iron, constructed for iron wheels, having been covered with a hoop of wrought iron, placed while hot and adhering by the contraction, showed an analogous resistance. Before this juncture, a few blows of hammers were sufficient to cause the hoop of cast iron to fly into fragments ; compressed in the hoop of wrought iron, it was necessary to make long exertions with a heavy sledge-hammer ; the two hoops changed shape together before the cast iron broke, and the fragments of cast iron remained contained in the envelope of wrought iron. 997. " These examples, and some others which it would take too long to enumerate, conducted us to seeking whether a hoop- ing of wrought iron would not add to the resistance of cylinders of cast iron against the explosion of powder ; we consequently covered with hoops of a thickness of ten millimetres, (about T \ of an inch), wheel-boxes, the sides of which had been thinned an equal amount. ' The boxes which burst into fragments before this operation under a charge of K. *75 (1*65 pounds), showed themselves, with the assistance of the hooping of wrought iron, inexplodable under the strongest charges which they could con- tain, 1 K. '35 (2*97 pounds), and whatever was the mode of wadding employed to effect their rupture. 998. "We will add to these facts the one, not the less stri- HOOPED GUNS. 847 king, of the body of cast iron hooped with wrought iron, adopted recently in the ballistic pendulum at Metz. The bodies made simply of cast iron broke under the first blows ; those of bronze cost 10000 francs ; they conceived the idea of hooping with wrought iron, bodies of cast iron, and they showed themselves indestructible against the repeated shocks of bullet fired with the strongest charges. 999. " Finally, in Belgium, the mortars of O ra .60 (24= inches), designed to project bombs weighing 500 kil. (about 1100 pounds), having exploded after a small number of shots, before thick- ening their walls and thus augmenting beyond measure their already very considerable weight, they tried if they could not consolidate them sufficiently by enveloping them with some hoops of wrought iron ; the success was so complete that three hoops sufficed; they limited themselves to placing one at the muzzle, the other at the middle, and the third at the position of the charge. 1000. "Upon examining the circumstances which had ac- companied the bursting of cannons proved in 1837 at Lafere, we perceived, as we had already done while studying the fragments of a great number of guns burst at the naval foundry at Severs, that the rupture commonly takes place following planes passing through the vent, and that the fragments are projected in the rear and laterally, following the inclination of these planes with respect to the axis of the piece of ordnance. " Hoops of wrought iron placed transversely upon the reinforce would prevent lateral explosions ; but it happens sufficiently often that the rupture taking effect through many planes, cutting through the vent, the breech is found separated and projected in the rear. " In this case it should be feared that the transverse hoops, torn away with the breech, would be dispersed, and would add themselves to the number of fragments. 1001. "In order to obviate this defect, in order that under all (-ircumstances the fragments of the burst gun should remain together and contained in the envelope of wrought iron, it is 848 ORDNANCE. APPENDIX. FlG. 426. evidently necessary that all the parts of this envelope should be bound together with sufficient strength to resist rupture in the longitudinal direction. In consequence, we have conceived the plan of composing the wrought-iron envelope : u 1st. Of a longitudinal armature extend- ing from the platband of the breech to O m .12 centimetres (about 4/8 inches), be- yond the trunnions. " 2d. Of transverse hoops, placed side by side, from the trunnions to the platband of the breech formed by the last of them. 1OO2. "1st. Longitudinal Armature. Plate YI. This armature is composed of twelve bars of wrought iron A, A, A, etc. (Fig. 1), having O ra .66 (almost 1-2 inches) in breadth O m .03 (about 1/2 inches) in thickness.* " The bars have the length necessary to extend from the extremity of the breech to 12 centimetres (about 4/8 inches) beyond the trunnions, with the exception of the two bars placed below the trunnions, which are shortened in such manner as to permit the cast iron to pass which should form them. " The bars are arranged parallel to each other O m .06 (about 2*4 in.) apart, in such manner as to form the bars of a cylinder, presenting at its exterior surface as many solid parts as spaces, and having for the Thiery's hooped gun. 1833. 24-pound^ cannon O m .48 (about 9-2 in.) exterior diameter. The exterior part of the bars is rounded, so as to coincide with the exterior surface of the cylinder of which they make part. The bars are secured in their * Fig. 426 is reduced from one of M. Thiery's drawings, and sufficiently illustrates his plan. HOOPED GUNS. 849 position by means of straps B B, B' B', B" B", B'" B'", B"" B"", spaced apart O m .25 (about 10 in.). The bars are held against the straps by draw-screws c, c, c, etc. (Fig. 2). u These arrangements being made, the apertures of the cylinder at the openings presented by the longitudinal armature, are closed by means of bars of wood and wax, in such manner as to have at the exterior a solid surface, and the cylinder thus obtained serves itself as the pattern for the lower part of the cannon. This pattern is placed in the flask designed to contain it ; the sand is rammed around it ; then the wax is melted by means of a chafing- dish ; the bars are removed. The longitudinal armature thus remains placed in the mould, in order to form one body with the cast iron. " The other parts of the cannon are moulded by the ordinary processes, and when we are ready to cast it, we lower chafing- dishes into the mould so as to raise as much as possible the tem- perature of the bars of wrought iron which are to be immersed in the cast iron, and to avoid thereby the blow-holes which would result from the contact of these bars at the ordinary temperature with the iron in a melted state.* By means of these precautions, we have obtained, in 1833, in the foundry of Fourchambault, a cylinder of wrought iron and cast iron perfectly well formed. The bars sustained by the wrought-iron straps, a, have been fitted into the cast iron, their exterior portions entering into fusion, have effected a welding, uniting intimately together all the parts con- stituting the exterior surface of the cylinder. Upon cutting one extremity of the cylinder, we have perceived that the bars of wrought iron were steeled at their surfaces, but for a depth which did not exceed one millimetre. " At the interior the iron was altered in no respect ; it had; preserved all its fibre and its quality. A bar extricated from the: * " The process of founding, the muzzle below and the breech above, described^ in the first part of the Applications of Iron to Construction of Artillery, p. 149 and following, would be applied with advantage to this system of pieces of ordnance ; by casting in this manner the piece of ordnance, the longitudinal armature would be raised to the necessary temperature to weld itself to the cast iron" 54 850 ORDNANCE. APPENDIX. cast iron, then submitted to rupture, has not shown a sensible diminution of its resistance to extension. 1OO3. "2d. Envelope of Transverse Hoop. Plate YT. (Fig. 3).* The 24-pounder cannon cast in the longitudinal arma- ture, presents, from the breech to the trunnions, a cylindrical portion having O m .48 (about 9 in.) in diameter. " It is upon this portion that we have placed the series of hoops placed side by side, represented at Fig. 3.* " These hoops have O m .10 (about 4 in., breadth) ; their thick- ness is variable in such manner as to give the lower part of the cannon the truncated conical form which pieces of ordnance should present. The hoop against the trunnions presents O .05 (about 2 in.) for the minimum thickness ; that forming the platband of the breech has one of O .10 (about 4 in.) ; the last but one, placed upon the vent, O .08 (about 3*2 in.). Before placing the hoops, nicks are made from distance to distance upon the exterior sur- face of the cannon, to cause the hoops, which are placed after- wards after having heated them to the temperature found to be necessary to obtain a suitable dilatation, to adhere strongly to it. The hoops, in cooling, exert, by the contraction upon the cannon, a powerful compression, which cannot fail to add to the strength of resistance of the cast iron, and guarantees the connection of the system of the envelope of wrought iron. Afterwards, a hoop of wrought iron, having likewise, O m .10 (about 4 in.) of breadth, by O m .05 (about 2 in.) of thickness, was introduced from the side of the chase and which rests in front against the trunnions, to secure O the longitudinal bars which extend up to this point, and upon which one must be careful to make nicks to bind to them the hoop which is heated in order to obtain a strong contraction. " A last hoop, designed to unite the preceding against the trunnions with the chase of cast iron, terminates the envelope of wrought iron. " The cannon is afterwards bored and turned on the exterior by the ordinary processes. All these operations are very simple; * See Fig. 426, which sufficiently illustrates all the drawings mentioned. HOOPED GUNS. 851 we have said that they did not present any difficulty in execution for the trial cannon constructed in 1833 at the foundry of Four- chambault with very imperfect means. 1OO4. " We strongly regret not having been able to obtain the proof of the rupture of this cannon, and of having, in addition, in place of the results of experience, only conjectures to present in support of our system. " However, if, notwithstanding the facts cited, one may still call in question, until new proofs, the increase in resistance which we claim to give to cast iron by means of the hooping of wrought iron, one should not the less contest its effectiveness for containing the fragments in case of rupture, and for preventing the disper- sion of the fragments. " In fact, the envelope of wrought iron, such as we there pro- pose, has some analogy to the pieces of ordnance of wrought iron constructed at the origin of artillery, and by means of which they fired the enormous bullets of which history makes mention. These gigantic culverins were composed of longitudinal bars of wrought iron placed in the manner of staves, and secured together by transverse hoops of wrought iron. " Since this system sufficed to constitute, by itself, pieces of ordnance, it will evidently satisfy, without difficulty, the auxiliary part which we impose upon it here. Experience will give the limit of the resistance necessary to contain the fragments in all directions ; we think that it will be shown below smaller dimen- sions than those we have proposed."* * " The resistance of wrought iron to rupture in the direction of the fibres, is estimated at 40 kil. (about 48 Ibs.) for the square millimetre (about T yo of an inch square, or 71, ou of a square inch), of the transverse section; let us reduce it to 20 (44 Ibs., about), on account of the welding of the hoops and of the immersion of the longitudinal armature in the cast iron. In order to burst at the same time the, twelve bars composing this latter, an effort of 432,000 kil. (950400 Ibs.), time would be necessary; but the resistance of cast iron being only 13 kil. (about 28'6 Ibs.) for each square millimetre of section, the trunnions of a 24-lb. cannon would break under an effort of 250000 kil. (about 550000 Ibs.). The rupture of the trunnions will then always precede the complete tearing away of our armature, and we have seen, by the preceding proofs, that the trunnions have uniformly withstood." 852 ORDNANCE. APPENDIX. CHAMBERS, 1849. 1005. Benjamin Chambers's Specification of United States Patent, dated Jnly 31t, 149.* " Be it known that I, Benjamin Chambers, of the city and county of Washington, in the District of Columbia, have invented a new and useful Improved Cannon, and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, which make part of this specifica- tion. " My improvements have reference as well to the construction as to the mode of using cannon, the object being to produce such an improvement in fire-arms as will secure all the strength neces- sary, together with suitable weight of metal, and a prompt, safe, and easy mode of charging and discharging the piece. " The material of my cannon is wrought iron. I am aware that this material has been already employed in various ways for the purpose of constructing heavy ordnance ; that staves of iron and hoops of the same material have been put together in alter- nate layers until a cylindrical or conical mass of suitable magni- tude had been produced ; that solid masses have been forged and subsequently bored out to the required interior size ; that series of rings have been piled up and held together with bolts passing through them lengthwise of the gun, and fastened at each end by screw-nuts, or with straps running fore and aft on the outside ; also, that flat rings have been made separately and welded to- gether into a pile of sufficient height to constitute the length of the gun. " I am aware that serious objections have in practice been found to exist against all these modes of forming wrought-iron cannon, and I have devised the following, which I consider decidedly preferable to any hitherto in use. 1006. " To obviate the danger of crystallizing the iron by *Fig. 427, reduced from the patentee's drawings, sufficiently explains all that part of the specification referring to the mode of construction under consideration. The description of the breech-loading has been omitted. HOOPED GUNS. 853 welding it in large masses, I form my cannon of pieces of a moderate thickness only, commencing with the tube #, a, as seen in section at Fig. 427, the interior of which tube is the bore of the gun, and the outside is turned to receive a series of rings a' ', a' ', etc., which have an interior diameter, such that they will not, when cold, pass on to the tube , but, when heated, will readily slip on, and come to the required position. I avoid too great a heat, for the purpose of preventing oxidation of the rings, and determine the diameter of the interior of the rings, as com- pared with that of the exterior of the tube, on the principle of the law of expansion of wrought iron, which I compute at about seven-millionths parts of its dimensions for every degree Fahren- heit to which it is heated above the freezing point of water. FIG. 427. T Chambers'** hooped gun, patented in 1849, 1007. " Having shrunk the rings a', a! , upon the barrel a, I place in a similar manner, by heating and shrinking on, the rings a" ', a" , so as to break joints with the rings a' ', a', and when a greater number of courses of rings is necessary, they are placed on the preceding series in the same manner as the second series is placed upon the first, that is, so as to break joints with each other. The rings may all be prepared separately and finished ready to be put together, or when one set has been placed upon the barrel , throughout its length, the piece thus formed may be placed in a lathe, and the exteriors of the rings turned all together, so as to receive the next tier of rings. 1008. "Instead of turning the barrel a of a cylindrical 854 ORDNANCE. APPENDIX. form, and shrinking on the rings a 1 ', #", etc., with so much tension as to make them adhere firmly by the mere friction thereby created, I shall, in some cases, either in whole or in part, turn the barrel a, having alternately elevated and de- pressed portions. To fit these elevations and depressions, the rings #', a', will be formed on their inner sides with reverse depressions and elevations answering to the ridges and cavities turned on a. The edge of the ring a', is of such interior diam- eter that it will not, when cold, pass over the ridge on the barrel a; but when heated to the proper temperature, it will come into place, and then the contraction of metal brings the ridges into firm contact with the depressions, leaving the barrel at all parts firmly griped by the rings, but not so straining the latter as to diminish essentially the tenacity of the ring when cold. In deciding how high the elevations may be made consistently with ease in getting on the rings, and with due adhesion after they are cooled, I calculate the expansion at the temperature used in putting on the rings, and ascertain and give to the diameters of the ridges the same relations as the ring a! will have at the edges, in its hot and its cold state respectively. But in turning the rings #', I leave their inte- rior diameters in the respective parts, slightly less than that of the barrel at the parts on which they are severally to be set. This is for the purpose of having every part of the ring, when cold, brought into a moderate tension, but not over- strained. 1OO9. " By means of the rate above stated for the expansion of iron by heat, and assuming the temperature of 1000 degrees above the freezing point at which the rings might be able to pass on to the barrel, I find that if the ring have at its edge a diameter of 6 in. when cold, its larger diameter (as well as that of the barrel), may be made T o o o o 7. "The gun, however, is usually broken through the breech the strongest part of the gun and beyond the range of the pressure, which is, of course, limited to the bottom of the bore or chamber. The diagram (Fig. 437) in Captain Rodman's book, p. 43, exhibiting the various kinds of strain to which a gun is subjected at each discharge, considers the gun as if made up of staves, and really exhibits only the strain from the expansive force 878 ORDNANCE. APPENDIX. or direct pressure of the powder, bending the staves outward; and page 47 of the same hook, by diagram (Fig. 438), the direc- tion of fracture due to such strain, not through the breech, but running at an angle to the plane of the bore. FIG. 437. 1O58. " To show that it is improbable that the direct pres- sure of the powder should be the cause of fracture, as exhibited by the gun actually broken by firing, prepare three plates of metal, say 4 inches thick, 12 inches wide, and 60 inches long, with plane surfaces ; the middle one, on being heated to 1600, will be found expanded one-sixtieth part of its length, or will be 61 inches long. On placing it between the other two (Fig. 439), a part of its heat is immediately communicated to their con- tiguous surfaces only. The expansion of one surface of the out- , FiG. 438. FIG. 439. side plates, while the other surfaces remain cold, warps the latter to the form of a segment of a circle. Now, supposing them placed upon the diagram of a burst gun (Fig. 440), the centre metal of which has been heated by the combustion of powder, it is evident that the fracture in the particular direction exhibited must have resulted from the unequal expansion of the gun by heat, and a diagram exhibiting these curves, the result of this expan- sion, will be exactly the opposite of the curves on the diagram by Rodman, and will account for the breaking of the gun through the breech, beyond the range of the pressure made by the powder (Fig. 441). How GUNS BURST. 879 " The following diagrams (Figs. 442 and 443) exhibit the effects of expansion of the inner metal by wedges, the drawing exhibits a section of the metal of a gun, with dovetail notches cut along the surface of the bore. Upon driving wedges into FIG. 440. the notches the muzzle would be expanded, as shown by the dotted lines. If a band were put upon the muzzle, the fracture nearest the muzzle and the one through the cascabel would be most likely to occur first. If the band were placed over the first- FiG. 441. =4. mentioned fracture, and the wedges along the reinforce and at the bottom of the bore driven most, as the heat is most intense at the bottom of the bore, cross fractures of the reinforce would be the result, as shown in the diagram. As the heat expands FIG. 442. the metal in the direction of the diameter also, its effect in this direction also must be considered* The expansion of length, however, is of most consequence in considering the probable direction of fracture. 1O.79. " That the fracture almost always intersects the vent- has been heretofore referred to tho weakness resulting from 880 ORDNANCE. APPENDIX. drilling away part of the metal, but on page 355, Major Wade's Reports on Metals for Guns, we find that after a gun had been put to extreme proof, and exhibited signs of fracture, a hole was FIG. 443. drilled one inch forward of the base-ring, and four inches from the line of the vent, to a depth of four inches, and of the dia- meter of one and a quarter inches. The gun was then fired with double charges of powder, and with a bore full of balls and wads, eleven times, to bursting. Although the piece burst into FIG. 444. FIG. 445. more than twelve fragments, one of the fractures intersecting the vent, it did not split through the large hole, showing that the gun had strength to resist the pressure of the powder, faut burst, notwithstanding the drilling away of so large a part of the metal, from the communication of heat. The true cause, probably, of the intersection of the vent by the fracture, was the communica- tion of heat to the surface of the vent, thereby expanding a column of metal about it, for it should be recollected that the passage of a large quantity of gases through the vent would communicate more heat to its surface than would be com- municated if there were no current, but the capacity of the vent How GUNS BURST. 881 only filled ; in that case not much heat would be supplied to the surface, because the quantity contained within the vent would be small. 1OOO. "But in this example, as in all others, as is well known to ordnance inspectors, the fracture began to exhibit itself on the interior surface of the bore. This would seem to prove that guns burst by pressure rather than by expansion of the inner metal as if the inner metal were expanded by the communication of heat before the outer metal gave way a strain of compression resisted by the strength of the outer metal would rest upon the inner metal of the gun that would prevent fracture ; and, undoubtedly, if it ever occurred to an ordnance officer to inquire whether the communication of heat to the inner metal of guns was the cause of their failure, the beginning of fracture on the inside would appear to him an argument against the theory. This I consider a critical point, but one directly favoring the theory. * * * The accompanying diagram (Fig. 446) exhibits a cross-section of a gun at the point of greatest pressure, and, consequently, highest temperature; the surface of the bore is supposed, in this example, to be contin- uously exposed to the high temperature evolved from the combus- tion of powder when its expansive force is resisted by the inertia of a heavy projectile, or, as if a fire were constantly burning within the gun. The space between the curved lines represents the place and quantity of heat thus communicated to the metal, showing the greatest expansion immediately at the surface of the bore.* But we are to recollect that, in the most rapid firing, the surface of the bore is exposed to this high tempera- ture only about one-hundredth part of the time, while during the other ninety-nine-hundredths the heat of the surface of the bore * "To represent a reduction of temperature by lines converging toward each other I know is not philosophical, although as no conventional lines have been adopted to represent intensity of heat by their direction, and as I have confidence, my meaning will be understood. I have chosen to use them in this manner." 56 882 ORDNANCE. APPENDIX. is radiating away. If the diagram represented a gun of six inches diameter of bore, and eight inches thickness of metal about the bore, the range to which the heat would penetrate the metal at the first discharge would be about four inches ; for heat enters metal with a velocity depending on the difference in temperature of the source from which it flows and the metal into which it is flowing. The heat is communicated to the small surface of the bore, while it is radiated from the large outside surface of the gun ; from this cause, if from no other, the tem- perature would be much higher within the mass than on the outside. " The penetration from the first discharge being four inches, it might be supposed that the range of the heat from the next discharge would be greater; but heat having been communi- cated by the first discharge, the range of the second is less, from the reduced difference of temperature. Although, of course, the heat flows onward, its motion is very slow. If, then, the penetration be four inches, at the distance of four inches from the surface of the bore the temperature will be comparatively low, but little higher than that of the metal at four and a half inches from the surface of the bore. The heat, therefore, is conducted from the point of four to that of four and a half inches slowly ; more slowly from that of four and a half to five, and with a continually reduced and very slow rate of motion to the out- side. As the heat is communicated from one inner stratum to the stratum surrounding it, for each inch of the increasing distance it travels, the mass of which the temperature has to be raised is greater in circumference also ; this is another cause of the retardation to its motion outward. Although for ninety- nine hundredth^ of the whole time the heat is radiating from the surface of the bore, the velocity with which it leaves is much less than the velocity with which it is received, because the difference in the temperature of the gun and the atmosphere occupying the bore is much less than the difference of tempera- ture between the metal of the gun and the gases ejecting the shot by their pressure. The atmosphere occupying the bore How GUNS BURST. 883 receives the heat by radiation, in the intervals between firing quickly, from the immediate surface, and less quickly a little distance beyond; and so again the heat flows from the metal of the gun with reduced velocity as the distance increases from the bore, leaving the point of highest temperature in the mass of metal, but not far from the surface of the bore. (See Fig. 447.) Its effect towards causing rupture may be illustrated by taking a cylinder of pine wood a few inches in length and a cross- section like the diagram, and providing a wedge similar in form to a bayonet (Fig. 448), but truly tapered to a point from a FiG. 447. FIG. 449. FIG. 448. cross-section at the head, the same as the lines representing the place and quantity of heat on the diagram, showing its effects by interrnittent communication of heat. (Fig. 447.) If the point of this wedge be set upon the end of the wooden cylinder at the point supposed to be the point of greatest heat, according to the theory above, and by a blow driven into the end-wood, it will penetrate so as to make an impression like the inner line of the diagram. A second blow, driving it further into the wood, penetrating as if to the second line of the diagram, and expanding the wood, will cause a fracture inward toward the surface of the bore Jirst a third or fourth blow will split it to the 884 ORDNANCE. APPENDIX. outside. And thus guns burst, the first fracture occurring on the inside, and afterward opening to the outer surface. IOCS. "It is often noticed as a curious phenomenon when large guns burst, that notwithstanding the chase or forward part of the gun, several feet in length, may be thrown many feet end over end, the shot passes through the chase the length of the bore without being diverted from the direction of its aim. This fact corroborates the theory under consideration, as it is evident that the shot is not projected by the same force that bursts the gun the communication of heat to the inner metal of the gun requiring a longer interval of time, and gun metals being comparatively non-conductors of heat. In Hodman, Plate II., Fig. 2, is shown the interior line of fracture of a 10-inch Columbiad. (Fig. 450.) Here a thin bit of metal, indicated by FIG. 450. the line marked JSP*, is shown, which seems nearly to envelop the bore. Nearly one-half the reinforce was broken off this gun in the same manner as chips break off a stone door-cap when a building is burning, but in this example the outside of the stone is first heated while the inside remains colder. The outward pressure of the powder at the time of this fracture would surely have carried away so thin a piece of metal ; but it remains standing to show that the pressure had been reduced before the gun broke a remarkable evidence of the true cause of the bursting of the gun." * * * LYMAN'S ACCELERATING GUN. 885 LYMAN'S ACCELERATING GUN. 1 04>2. Extract from the patent specification of Azel S. Lyman, New York, for accelerating fire-arms (No. 16568), Feb. 3, 1857 : " As soon as the gun has been fired and the ball has passed the chamber, d (Fig. 451), the fire in the bore, , ignites the charges FIG. 451. Ly man's accelerating gun. (From the patent.) in the chambers, d, thereby giving the ball additional force. Before the gun is to be fired, the muzzle is to be covered with some elastic material, *', and the air to be exhausted by applying an air-pump to the opening, e. * * * Claim. The employment of the accelerators or additional charge-chambers in the manner and for the purpose substantially as described. I also claim covering the muzzle and exhausting the air through an appropriate aperture, whereby the atmospheric resistance is removed from the front of the projectile while passing along the bore, as set forth." 1O63. A small gun on this plan, tested at New York and else- where, was composed of three heavy -J-in. rifle-barrels screwed into chambers so as to form a continuous tube about 9 feet long. At the breech, there was a small chamber holding 50 grains of pow- der to start the projectile. Around this was an annular chamber containing 400 grains ; 34 in. farther forward there was a cham- ber containing 900 grains ; and 34 in. farther another containing 750 grains ; the muzzle was 37 in. beyond this last chamber. 886 ORDNANCE. APPENDIX. This gun fired a sharp-pointed steel bolt 8 in. long and -J in. in diameter weight, 6^ oz. entirely through 4 in. of J-in. plates, with the above charge 4^ oz. The average penetration in lami- nated armor composed of -J-in. boiler plates, was 4 T V in. ; and 4J in. in solid iron. A gun on this system, with a 2 T 7 -in. bore, rifled with one turn in 36 in., has been recently constructed. But the system has not been adequately tested, and government officers have objected to it as dangerous. ENDUEANCE OF PARROTT AND WHIT- WORTH GUNS AT CHARLESTON. 1064. As to the endurance of the Parrott guns at the siege of Fort Sumter (276 A), General Gillmore states that one 20-pounder was fired 4606 times at an elevation of 40, without bursting. The shells were fired nearly five miles from the Federal works into the city of Charleston, which accounts for the great elevation of the piece. General Gillmore also states, that out of six 200-pounders and seventeen 100-pouiiders, which were expended by bursting, on Morris Island, four of the former and two of the latter broke, after great service, square off under the wrought-iron hoop. One 200- pounder and seven 100-povmders burst by blowing out just in front of the hoop. As a rule, the guns had sufficient resistance to bursting, only three of the hoops having split one into three pieces and the other into two. The obvious defects of the gun are, therefore, insufficient length of hoop and insufficient longitudinal strength. Both are easily remedied. The resistance to bursting appears to be adequate to the charges. 1065. General Gillmore states, that at the siege of Fort Sum- ter (276 A) two 80-pounder (called 70-pounder in England) Whit- worth guns had less mean endurance than the Parrott guns, but HOOPING OLD CAST-IRON GUNS. 887 that their failure was due to the slipping to the rear of the inner tubes, thus closing the vent. Reference to Fig. 28 will explain the cause of this failure, and Fig. 25 will illustrate Mr. Anderson's means of preventing it hooking the tubes over one another so that they cannot slip. HOOPING OLD UNITED STATES CAST- IRON GUNS. 1O66. In September, 1863, it was recommended by the United States Army Ordnance Board, that " in order to make the 24, 32, and 42-pounders of the old pattern reliable rifled guns, the 42- pounder guns be banded, bushed, and rifled ; and as experiments* show that the 32 and 24-pounder guns are reliable when rifled, up to at least 500 rounds, it is recommended that they be rifled and bushed for immediate service." This work was then ordered to proceed at once by the Secretary of War, and an oflicer was instructed to inspect all such guns in certain forts and batteries, the examination being specially directed to the following points : " 1st. To ascertain, from the records of the post, or other data, how many times each gun has been flred with service charges. " 2d. To see if the bore is a true cylinder. " 3d. To see if the vent is unduly enlarged. "4th. To see if there are any other defects which will unfit them for the service required. "All the guns which have been fired over 500 rounds ; all those in which the variations in the bore from a true cylinder are *05 or more ; all in which the greatest internal diameter of the vent is *Y in., or in which there are other radical defects, which, in your judgment, unfit them for the service required, will be laid aside and specially reported on."f * These experiments were chiefly conducted at the West Point Foundry, with old guns hooped by Captain Parrott. f Ordnance Memoranda, No. 5. 888 ORDNANCE. APPENDIX. ENDURANCE AND ACCUEACY OF THE AEMSTRONG 600-POUNDER. 1O67. " The 600-pounder has now fired about 50 rounds alto- gether, with charges from 60 to 70 Ibs., and one charge of 40 and one of 90 Ibs., which last was used with a steel round ball, weigh- ing 340 Ibs. The weight of the cast-iron shot fired for range is about 510 Ibs., and the initial velocity obtained with TO Ibs. of powder is 1250 feet per second. With 610 Ibs. steel projectiles of which few have been fired, the velocity has been nearly 100 feet less. The accuracy of this powerful weapon has been very good, its mean lateral diameter deviations being only 1| yds. at 1500 yds., 8 T V (?) yds. at 2300 yds., and 3 yds. at 4000 yds. range. With an elevation of 23 9' the gun ranged Y300 yds., and the time of night of the shot was 26 seconds. " After firing, the gun was carefully examined and found to have suffered most in the upper side of the powder-chamber, which was covered with small cracks or openings, but, as far as could be ascertained, there is no flaw of any magnitude. The gun is expected to stand at least 100 discharges (!) and may go on to 300 or even 500 before rupturing. It is generally supposed that, had the inner tube been of soft steel instead of coiled iron, it would have withstood the action of the powder gases better."* * * * " Beyond all doubt, however, the coils may be said to be gradually opening, and it is only a question whether or not the inner coil will stand a large number of rounds before it gives way. Once the inner coil yields, all the others on the outside become useless until the place of the defective coil is supplied with a tube of steel, as all the modern Armstrongs are now built with." f * Army and Navy Gazette, July 23d, 1864. f London Times, quoted by the Engineer^ July 22d, 1864. COMPETITIVE TRIALS WITH T-!NCH GUNS. 889 COMPETITIVE TRIALS WITH 7-INCH GUNS. 1O68. The trials of these guns (607, last paragraph) is not yet completed. The Army and Navy Gazette of July 23d, 1864, says : " As far as the trial has yet gone, the contest seems to lie between the Scott and Lancaster guns, the lead coating of the Jeffery and Britten projectiles having proved unequal to with- stand the 25-lb. charges. This quantity of powder appears also to have blown off portions of the studs upon the French shot, and to have considerably increased the difficulty of loading the Lan- caster gun. The loading of the French gun has been generally easy, that of the Scott gun, invariably so. The accuracy of the Lancaster with 25-lb. charges was very good at 10 of elevation, the mean difference in the range of the shot being about 27 yards, with a mean deviation of 7 yards ; Scott, 30, with a mean deviation of 9 yards. But, on the other hand, Scott's range was nearly 4800 yards to Lancaster's 4600 yards. At 2 of elevation, Scott's range of 1600 yards was 20 yards more than Lancaster's, and his mean difference of range and deflection, 16 arid \\ yards to Lancaster's 29 and 2 yards respectively." 890 ORDNANCE. APPENDIX. TABLE CXLVI. COMPARISON OP PRESSURES AND VELOCITIES WITH LOOSE AND COMPRESSED POWDER. (DOREMUS AND BUDD'S COMPRESSED POWDER.) WEST POINT, AUG. 29, 1861. Cartridges cylindrical, and fitted the chamber accurately. Diameter, -fa in. less than the calibre. Weight, i Ibs. The usual charge. Powder No. I, compressed to 10 tons on the entire surface of the specimens. Powder No. 7, compressed to 30 tons on the entire surface of the specimens. Powder Nos. 3 and 6, to intermediate pressure. Powder. Initial Velocity. Pressure per sq. in. on Chamber. Range, yards. Hazard B Loose ft. 14-7 7 Ibs. 4.27 7O yds. 768 I I4QQ 68OOO 4.C2 " 7-.. I CI4 7OOOO 716 " 6 I CO7 7OOOO 77O " 7 14-77 C7I 7O 27Q " 7. Loose ... 1274. IQ4.QO 287 i i4<;2 68090 707 " 3... I42C 5OOOO 2C2 "6 .... 1782 4-COOO 2O4. Dupont P, Loose I4.C2 coooo 281 " i 1482 68090 2QQ " 3 1480 50000 284 . 6 I 7Q7 40000 267 " Glazed Shel-lac I4Q2 67800 7.68 " Not Glazed I4OQ 67800 4O7 The initial velocity and pressure on the chamber of the compressed powder were greater than that of the loose in every case but one; and they increased with the amount of com- pression to a certain point, and then decreased as the pressure increased, so that, with a LOOSE AND COMPRESSED POWDER. 891 certain pressure, the cake and the loose powder are alike in results. The only advantages of the cake powder seem to be as follows : 1. Dispensing with the cartridge-bag, and accidents from fire remaining in the gun 2. Reducing the bulk of ammunition to three-fourths the size. 3. Preventing dusting in transportation. 4. Rendering the powder impervious to moisture. The glazed and unglazed cartridges were nearly alike in results. It having been suggested by Captain Benet, of the Ordnance Department, to make the cartridges smaller than the bore, so as to give greater space for the gases to expand, and lessen the first shock on the gun, this was tried, November 30, 1861, with the following results : Powder. No. of Bounds. Initial Velocity. Pressure. ft. Ibs. 2 1344 13500 Hazard No 7 Powder... , ..- 3 1348 13500 4 '357 13500 Hazard No 7 Powder in Grains 5 '359 1274. 13500 xy^j-yw The cakes, therefore, gave an initial velocity greater by 78 feet, or -j- 7 -, and a pressure on the bore less by 6000 Ibs., or ^ j /. e. y a greater initial velocity with a diminished strain on the gun. Comparing these results with Hazard's No. 7, tried in 1860: Hazard No. 7 grain, Initial Velocity r 473 feet. Pressure 5553 Ibs. Cakes, average Initial Velocity I 35 Z " Pressure 13500 " That is, the initial velocity of cakes is less by 121 feet, but the pressure is less by 41830 Ibs., or three-fourths. Hazard powder is now made less quick than formerly, which ac- counts for the discrepancy in the above results. 892 ORDNANCE. APPENDIX. ^,2 ^ c ' H* 10 O VO ON .5 j^'3 ^^ M u-> (^ M.S a CO VO . 9 9 9 9 gl "o o o o 6 3 bo EH o o Ml Ml o o *o oo O vO 00 fi . 'O ON O oo s -2 *3 2 M 6 6 Sj a a Q 8. OO f^i t*> * r* i | ON 5 c ON ON ON O M M J 02 i i 2) o 1 OO ON 10 ON oo 1 -2 s '^- 1 3 H b VO 00 VO 00 B 3 S 1 H oo 4 * O 00 i i fa r^ t^ r 3 3 *s g O 1*** r-- 5 J *' O ro 10 10 -0 A O M ^ oo a II ON O VO H "^ s ja H rj- 3 I 1 1! a 1 ^ 00 M ON 00 ON ON 3 ^ n vo * JS 1 .2? 8 |l |R ON * H 00 MI ON 00 vo 10 - & W 3 ? ^ m 10 rt r^ 5 1 9 1 3-s | ON Jo VO vo vo VO vo NO H & ^ VO O vo ON v "*"" =s "S ro rh O rt ~o c ^o ^ VO H \O vO vo ro vo vo 1 ro M Ml i c< m ^ '^ . 4 | 2 PH 1 "o t S c 1 ON fJ 10 VO 1 'I > m Jj o"< J j J^ I J i D E [The References are to the Paragraphs.] ACCELERATING Gtm, LYMAN'S, 1062, 1063. Alloys for gun-metal, see Bronze, 506. Aluminium bronze, 503. Ames's wrought-iron guns, 128, 129, 431. Anderson, John, Esq., on Armstrong system. 452. On elasticity and ductility of cannon inetals, see Elasticity; Ductility. On qualities of guns, 271. On welds, 449. On wrought iron, 396, 401, 427. Annealing steel, see Steel. Armor, see Chapter II. and Part II. American systems (see Armor Experiments, American), 191, 195, 204, 256. 262, 263. British systems (see Armor Experiments, British), 191, 192, 195, 834. Backing, 199 note. 830, 854, 856-859. Best quality, 202, 212-216, 226, 236, 262, 834. Combined, 204, 263. Convex surface stronger, 181 A. Destruction of, not the aim, 210. Ductility, 203, '211, 212-216, 286. Effect of shot going through, 262, 264. Fastenings, 192, 194, 204. Gun to operate against, see Guns. Light targets, 206, 235 B. Laminated, 191, 194, 197. 198. Easily punched, 181 A, 195, 196-202. Advantages, 194, 263. Strengthens the ship, 194, 204. Projectiles for punching. 887; material for, see Rifling and Projectiles. Resistance to projectiles, see Telocity of Projectiles; Armor, Solid; Armor, Lami- nated. Shells fired through (see Failing and Projec- tiles), 226, 231-235, Table XXXI. Solid, weakens the ship, 194. Punching, 202. Advantages, 202, 203, 220. Steel, 213, 236, 471. Why necessary. 171, 210. Work of, compared with cannon, 471. Experiments against Floating batteries, 800. Eussian, 380. American, Chapter II., also Part II., Ta- bles XX VIII. and XXXI.; sub-cali- bre shot, 844; 15-in. ball, 179, 181 A, 181 B, 863, 864, 886; 11-in. ball, 179, 180, 181 B, 214, 235 B, 855-859, 864, 866-869, 871, 876, 877, 886; 10 in. ball, 200. SOI, 837; Parrott 10-in. bolt, 181 A, 861, 862; Parrott 8-in., 886 ; Parrott 100-pounder, 837, 844; lead shot, Ta- ble XXXV; 14-in. iron, 181, 866; 10- in. iron, 179, 180, 200, 864; 8-in. iron, 861 ; 6-in. iron, 181 A, 844, 8S6; 6J-in. iron, 867; 4$-in. iron, 181 A. 214, 235 B,859, 868, 869, 871, 876, 886; 4-in. iron, 844; early experiments, 790; Stevens's, 790, 794, 801, 837 ; mason- ry protected by iron, 799 ; wire tar- get, 855; inclined armor, 856-858; backing, 856-859; rubber, 856-859, 871, 877; target of bars, 862; Atlan- ta, 863; oak facing, 876; Hog's-hair target, 898. British, see Tables XXVIII. and XXXI., Part II., and Chapter II.; early experiments, 792, 795, 796, 798, 802 ; masonry protected by iron, 190, 792, 820, 824; Warrior target, 183, 184, 201, 227,229, 231, 232, 831, 833, 839, 845, 847 ; backing, 830, 854; Cole's cu- pola, 829; Fairbairn's target, 828; Roberts'a target, 827 ; inclined plates, 816, 825; different qualities of iron, 823; Special Committee, 1861, 821; cast-iron blocks, 803; steel armor, 804, 823; firing through water, 265, 806, 849; thin plates, 795, 812, 840, 846; Trusty, SIS; conclusions up to 1862, 834; " Committee" target, 838, 839; Scott Russeirs target, 187, 840; Samuda's target, S40; Minotaur tar- get, 188, 223, 843; Inglis's target, 185, 850-853; Chalmers target, 189, 230, 873 ; Clark's target, 875 ; Bellerophon target, 189 A, 831, 8S2; compressed wool armor, 897 ; mantelets for em- brasures, Table CXLI. ; La, Fiandre target, 900 ; 4-in. plates, 804, 807-809, 813; 838, 839 ; 4*-in. plates, 797, 814, 815, 826, 831, 833, 838, 839, 845-847, 883, 888 ; 5^-in. plates, 233, 843, 846, 870; 6 in. targets, 832, 881, SS2; 6- in. plates, 826, 870, 885; 7i-in. plate, 186, 870; 8-in. targets, 810, 822; 10- in. targets, 818, 819, 822, 832 ; 11-in. plate, 181 D, 8S5; 14-in. target, 811 ; 68-pounders and 32-pounders com- pared, 807-309; Whitworth projec- tiles, 183, 185, 231, 232, 234, 806, 845, 846, 852, 853, 870, 881 ; elongated and spherical shot compared, Sit ; 10|-in. Armstrong gun, 18^, 185-188, 189 A, 201, 227, 228, 230, 233, 839, 840, 843, 853, 870, 874. 875, 881, 900 ; 13-in. gun, 181 C and D, 182, 183, 229, 847, 883-896; Thomas's 9-in. gun, 870; steel shot, 887-896. Armstrong gun. Where and by whom made, 1, Table III., Table III. A. Discontinuance of manufacture causes, 2, 3, 41. Number made, 1, Table III. Improvements probable, 3, 41. See Arm- strong Gun, Defects. Workmanship, facilities for, 3. 894 INDEX, Armstrong gun. Material, quality, make (see also Steel), 4, 6, 403. History and originality, 1, 2, 5,85; 1029- 1043. Principle of construction, 44, 433, 434, 452. Description, Tables, I., III. A, 5-34, 44, 432, 433. Fabrication, 5-12, 33, 44, 432. See Welds. Strength and endurance (see also Armstrong Gun, Detects, Welds), 9, 10, 39-41, 309, 811, 434-439, 444-447, 1067. Proof, 16. Safety, 40.301. Advantages of system, 434, 435, 442. Defects of gun and system, 2, 39, 402, 403, 440-457, 1067. See also Rifling and Pro- jectiles. Breech-loading, see Breech-loading. Rifling and projectiles, see Rifling and Projectiles. Ammunition, Table II., 545, 551. Initial tension, 12. Cast-iron gun hooped, 91, 309 Cost, see Cost of Guns. Plant for manufacture, Table IV., 453. New British gun, 41. 110-pounder, 21, 38, 36; Tables V., TIL See also Rifling and Projectiles. 150-poundcr smooth-bore, 29, 82,444, 446. 300-pounder rifle, 29, 32. 600-pounder rifle, 30, 252, 1067. 7-inch gun for Mi-. Whitworth, 33, 44, 441, 444. 9-inch gun for Mr. Thomas, 34, 444. Armstrong, Sir William. Position under Government, 1. On strains in guns, 238. On guns for long range warfare, 252. On strength of his guns, 440, 441. On rifling and projectiles, 632, 643, 683. Atlanta, iron-clad, disabled by 15-in, ball, 181 B. Attick's bronze hoop, 106. Atwater gun, 107. Rifling, 652. BACKING, see Armor, 199 note. Barlow, Peter, Esq., on strength of cylinders, 281. Bertram's gas welding, 4r>!. Bessemer steel, 68, 898, 474, 486. Guns, 141-144. Process, 142, 4S6. In the Exhibition of 1862, 143, 487. Bidder, Mr., on rifled guns, 608. Blakely gun, 55. Principles, 55, 59, 61. Patent, 1024. Early experiments, 72, Table XL Number made and makers, 5G. Structure, 57-73, Table X. Fabrication, 60, 61, 68-70. Varying elasticity, 59, 60. See Varying Elasticity. Initial tension, 59, 60. Material, 59-62, 68. Steels and cast iron combined, 58, 60. Endurance, 66,71. Rifling, 67, Table X. See Rifling and Pro- jectiles. Ammunition, 67, Table X. Prices, Tables X., XXVII. Guns for Massachusetts, 64. Guns for Confederates, 56, 58, 66, 73. 12J-in. rifle, 66. Blakely, Captain T. A. Connection with improved ordnance, 55, 1029-1039. Blakely, Captain T. A. Treatment by British Government, 71, 1029-1039. On strains in large guns, 221. On strength of guns and cylinders, 279. On longitudinal strength of guns, 307. On wire-wound guns, 316. On elasticity, see Varying Elasticity. On rifling and projectiles, 619, 657. On the originality of the Armstrong gun, 1029-1039'. Blunt, G. W., Esq., on rifled guns, 609. Breaching, see Masonry. Breech-loading, Chapter VI. Advantages and defects of the system, 726- The practice against it for heavy guns, 727-731. Opinions of Select Committee on Ord- nance, 731. Material inadequate, 732. Fast firing, 735-741. Convenience in turrets, etc., 742. Standard forms described, 755. Krupp, 767-769. Endurance, 769. Broadwell, 770. Storm, 771. Alger, 766. Armstrong, 13, 25, 737, 739, 755-764. Vent-pieces, 755, 758, 759. Side breech-loader, 7GO-762. Rapidity of fire, 735-741, 763. Conclusions, 764. French, 773. American origin, 773. I'srd in England, 775, Blakely, 778. Nasmyth, 779. Whitworth, 52, 781. Cavalli, 784. Clay, 7s& Wahrendorf, 785. Prussian, 786. Adams. 7^7. Rapid firing by machinery, 745-754. Cooling guns by machinery, 74S. 749, 753. Loading by steam. 750-753. Gas-checks, 75\ 7CO, 767, 768, 770, 771, 789. Screw breech-loaders, 755, 700, 773, 778, 779, 783. Wedge breech-loaders, 760. 767, 770, 784-786. Cap breech-loaders, 771, 781. Breech-plug, 32. 44, 50. Breech-screw, Armstrong, see Rifling and Pro- jectiles. Breech-strap, Dahlgren, 305. British gun, new, 41. See Armstrong Gun, Cast- iron Guns. Britten, Bashley. Esq. On rifled cannon, see Rifling and Projectiles. On strains in guns. '1'-'^. On rifling and projectiles, 634. Bronze, 496. Properties, 496. Want of uniformity, 497. Strength, 496. Difficulties of manufacture, 496, 497. Resistance to compression and wear, 499. Resistance to heat, 498. Cost, 496. Ames Manufacturing Company's, 106. Phosphorus and copper, 502. Aluminium, 503. Sterro-metal, 504. New alloys proposed, 506. Hoops for guns, 106. 501, Table XIII. Linings for guns, 500. Conclusions, 507, 508. INDEX. 895 Brooke's hooped guns, 104, 105. Bumford 12-in. gun, 108. CAST IRON, 854. See also Cast-iron Guns. Weakness a serious defect, 354. Strength of, 77, 355, 356. Quality, 150, 164, 355, 356, 360-362. Deterioration, 360. Fatigue of, 290. Elasticity, see Elasticity, Ductility, see Ductility. Eesistance to compression and wear, 371, 391. Want of uniformity, 361, 362. Detection of weakness, 363. Shrinkage of strong irons, the greatest, 358, 359. For Parrott guns, 77. Transmitting strain by, 99. Solid cast guns, 364. American, 364 note, 873 note. Unequal contraction, 364. Initial strains, 364, 368. Loss of tensile strength, 370, Density of metal, 371. Weakness to resist pressure, 366. Fast and slow cooling, 365. Heat of firing, 369. Shape, effect of, 390. Hollow-cast guns, see Hollow-cast Guns. Conclusions, 508. Cast-iron guns, 91, 92, 149, Tables XIII. and XXII. to XXVI. See also Cast Iron, Initial Tension, Hooped Guns. Solid cast, see Cast Iron. Hollow cast, see Hollow-cast Guns. Eodnian's and Dahlgren's shapes, 149, 890, Quality of iron, 150, 163, 355-363. Endurance, 163, 857 note, 372, 891. Lined, see Varying Elasticity. Eifled, 357, 391, 592. See Eifling and Pro- jectiles. French, 85. Eussian, 169. British, 167. Endurance, 168, Table XXIV. Particulars and charges, Table XXV. United States, 149-166: Tables XX11. XXIII. Columbiads, 164, 165. New, 164-166; test of, 163. Shape, 149, 165, 890. Dahlgren, 373 note, 236. guality of iron, 150, 163. ollow casting, see Hollow-cast Guns. 10-inch navy, 166. 11-inch navy, 166. 15-inch navy, 163. 20-inch navy, 166. Chambers^ hooped gun, 1005. Charges, Tables XXVIII., XXXII. See Spanish Gun; French Gun. Armstrong gun, 25, 29, 32, Table II. Whitworth, Table VIII. Blakely, Table X. Parrott, Table XII. 0. S. cast-iron, Tables XXII., XXIII. British cast-iron, Table XXV. Clark, Edwin, Esq.. 341. Clay, Lieutenant-Colonel, on the shrinkage of hoops, 269 note. On forcings and wrought-iron guns, 416- 419, 429. Clerk, Lieutenant-Colonel, on change of figure due to heating and cooling metals. 298. Coils, Armstrong (see Armstrong Gun), 7, 449, 450, 455, 457; Parrott, 74, 455. Colburn, Zerah, Esq., on the elasticity of metals 841, 342. Columbiads, 164. Competitive trials of rifled guns, see Eifling and Projectiles. Confederate guns, 56, 58, 64, 66, 73, 104. See also Blakely Gun. Conybeare, Mr., on rifling and projectiles, 615, 622, 633, 668. Cooling guns from within, see Hollow-cast Guns. Cooling guns by machinery, see Breech-loading. Cost of guns, 37, 38. 74. 393, 412, 453, 474, Tables IV., V.', VI., VII., XXVII. Cylinders, strains by internal pressure, see Strains in Guns. Conclusions, 270, 339, 508, 725, 789. DAHLGREX GUNS, see Cast-iron Guns. Ductility of metals, 844, 467, Tables LI. to LIII. LXIX. Wrought iron, 343, 349-352, 399. Steel, 344, 349-352, 399, 467, 472, 479, Tables LI. to LIII., LXVI., LXVIIL, LXIX. Comparison with iron, 469, 479. Bessemer, 472. Safety of, in guns, 349-352. Gain of strength by stretching, 844, 845, Mallet on, 341, 349, 352, 353. Anderson on, 343, 344, 399. Metal for hoops of guns, see Initial Tension. Duty of guns, see Guns, and Eifling and Projec- tiles. ELASTICITY OF METALS, 340, 467. Limit of, 841, 342. 346, Table LIII. Should not be exceeded in guns, 346, 347, 350, 351. Eelation to extension in metals, Tables LI. to LIII. Principles of Varying, see Varying Elas- ticity. Hoops, of, see Initial Tension. Coefficients of, Tables LI. to LIV. Mallet on, 342, 849, 352, 353. Clark, Edwin, on, 341. Colburn on, 341, 342. Wrought iron, 341-343. Steel, 467, 479, Table LII. Ericsson, 13-in. guns, 127. Experiments against targets, see Armor. FAIRBAIRN, MR., experiments on armor-punching projectiles, 713. Firttf s steel, 45, 68. Fishbourne, Captain, on spherical shot for naval warfare, 239. On Armstrong gun, 450. On rifling and" projectiles, 653, 670, 691, 693. Force, effect of, in guns, see Strains in Guns. Eftect of different rates of application, 347, 697. Forging, see Wrought Iron, and Welds and Weld- ing. Forts, see Masonry. French guns, 84-90. Material and calibre, reason of, 90, note. Canon de 30, 84. Unhooped guns, 85. Charges, 88. Strength and endurance. 89, 90. Eifling, see Eifling and Projectiles. Breech-loading, see Breech-loading. 896 INDEX. GALENA, armor of the, 262, 265. Guns. Description of, Chapter I. Requirements of, Chapter II., 270. Work to be done by, Chapter II., 270. Strains and structure, Chapter III., 339. Materials and processes of fabrication. Chapter IV., 508. Cast iron, see Cast-iron Guns and Cast Iron. "Wrought iron, see Wrought Iron Guns and Wrought Iron. Steel, see Steel Guns and Steel. Bronze, see Bronze. " Work done" by different, Table XXXYI. Shell, uses of, 174. See Rifling and Projec- tiles. For breaching masonry, 273-276 B, Ta- bles LXV. and LXVII. Working by machinery, see Breech-load- ing. Hooped, see Hooped Guns and Initial Ten- sion. Vary ing elasticity, principle for, see Varying Elasticity. To operate against armor, Chapter II. and Tart II. Unsettled state of the question, 175. Best class, 271. Two classes Important, 267-269, 271. Popular notions, 186, 207-210. Two systems, 176, 191, 193 (see Velo- city of Projectiles) ; illustrations, 179, 183 ; combination of systems by same gun, 178, 187, 207-210 ; combination of systems by different puns, 267; one helps the other, 268; objections, 269; advantages, 267-269. Armor smashing and dislocating, Table XXVIII., 177, 181, 191-193, 205-209, 211, 212; not illustrated by light targets, 206, 235 C ; defects of the system. 185, 193 A, 208-211, 221, 225, 261, 267, 26S; great distributed and small local effect, 193, 206, 208-211 ; advantage of large balls, 198, 222, 242; difficulty df adapting the system, 218; time wasted, 219; recapitula- tion, 224, 225. Armor- punch ing. Table XXXI., 176, 178, 181, 193, "200. 202, 207, 226, 236, 244, 252, 265; defects of the system, 261, 267; advantages of the system, 193 A, 211. 218, 261-266; American guns for, 236 ; larare diameter of shot wanted, 257, 253, 260; below water, 265. Conclusions, 270, 271, 339. Gun-Cotton, 901. Report on, British Association, 901. Chemical considerations, 902, 918-922, 957- 965. Mechanical considerations, 903, 923-957, 971-979. Practical applications, 904-914, 923-957, Palisades destroyed by, 912, 967, 969. Bridges destroyed by, 918. Ships destroyed by, 914. Manufacture in Austria, 915. Composition, 918-920. Properties, 918-922, 971-979. Information given by Baron Lenk on all features of gun-cotton, 923-957. Report of Austrian chemists, 957-965 Safety, 957-965. Manufacture and experiments in England, 966-970. Mr. Scott Russell on, 971-979. Theory of explosion, 978, 979. HARDENING IN OIL, 35. See Steel. Hart, Dr., on the strength of guns, 282, 800. Heating and cooling effect on metals, 298. Heat of firing effect on guns, 336. See Cast Iron. Theory, 336, 1052-1061. Remedy, 338. See Breech-loading. Danger in iron- clad warfare, 337. Heavy shot at low velocities, Table XXVIII. Hitchcock's process of forging guns, 460-464. Hollow-cast guns, 151. 153, 373, 482. Rodman's plan. 373. Fabricat'on. 154-162, 166. Test, 154, 159-163. Object, 373. Cooling. 155, 160, 166, 376-378. Condition and strength of the metal, 882. Regulated initial tension, 874-380; state of strains, 375, 376, 378 ; error from ex- terior cooling, 377, 378; requirements for, 379 ; removed by age, 3bO : heat of firing, effect on, 381. Wiard's plan, 383. Object and structure. 383. Probable result, 3S4, 388. Strongest iron may be used, 385. Effect of heat of tiring, 387. Homogeneous metal, see Steel. Hoops, see Initial Tension by Hoops and Descrip- tion of Guns, Chapter I. Wrought iron, 91, 92, 300-302, 400, 445, Table XI II. Steel, 48, 6S, 310, 465. 473. 482, 494. Bronze, 106, 501, Table XIII. With varying elasticity, see Varying Elas- ticity. Strength, Initial Tension ^ Ho l )8 - Size, Hooped Guns (see Initial Tension, Armstrong Gun, Whitworth Gun, Blakely Gun. Parrott Gun, Spanish Gun, French Gun), Table XIII., 91, 92, 104, 109, 127. 152, 980-1051. Defects, see Initial Tension by Hoops. British cast-iron experimental, Table XIII. Shape, effect on strength, 410. History, 980-1051. Horsfall wrousrht-iron gun, 110, 111. Fabrication, 110, 112. Endurance, condition, material, 113, 42a Cost, 114. Table XXVII. History, 114. Experiments on armor, Tables XXVIII., XXXI. Hydraulic forging machinery, 493. INITIAL TENSION BY HOOPS, 287. See Chapters I. and III. ; Hollow-cast Guns, Wire-wound Tubes. History of, 9SO-1051. Combined with Varying Elasticity, see Varying Elasticity. Object of,' 287, 290, 292. Law of. 2S9, 293. 307. Illustration of effects, 292. Theoretical accuracy of, 293-298. Professor Treadwell's plan, 2SS, 2S9, 1012- 1016. Safety of ductile outer hoop, 301. Forcing on hoops, 44, 50, 295. Shrinking on hoops, 11, 60, 61, 75, 296, 297. Want of continuity, 291, 292, 299, 300. Vibration, 299, 319", 335, 445, 448. Elasticity of metal. 300. 302. Ductility of metal, 91. 300-303, 445. Loosening of hoops, 76, 91, 300, 302, 445. INDEX. 897 Initial tension by hoops. Dimensions of hoops, 76, 92, 312. Jackets, 310. Transverse strength diminished, 313. Conclusions, 339. Initial strains, see Strains on Guns. Iron-clads, systems of destroying, see Guns, and Chapter II. KIRKALDY on the strength of wrought iron and steel, 395, 408, 417, 423. 469, 476, 479. Krupp's steel guns, see Steel. History, 130, 140. Principle of construction, 134 note. Description, 133-134. Fabrication. 131, 140. Markets for. 133, 134. Amount produced, 131 note. Cost, 134 note, Table XXVII. Weight, 134 note. 9-in., in Exhibition of 1862, 132. For Russia, 134, 136. Endurance, 185-189, 401, 475, 485, Tables XIX., XX., XXI. LANCASTER GUNS, 309. Rifling see Rilling and Projectiles. Lancaster, Charles. Esq., on Rifling and Projec- tiles, 689. On the longitudinal strength of guns, 309. Lead shot, Table XXXV Lined guns, see Varying Elasticity. Loading guns by machinery, see Breech-loading. Longitudinal strength of guns, 9, 10, 32, 90, 91, 227, 304-311. Remedies for weakness. 305-310. Dahlgren breech-strap, 305. Longridge, Mr. J. A., experiments on wire-wound guns, see Wire-wound Guns. On unequal strain in the layers of a cylin- der, 286. On hooping guns, 292-296, 299. On cast iron as a cannon metal, 354, 370. On rifling and projectiles, 312. Lyman's accelerating gun, 1062. MALLET, ROBERT, ESQ., on the effect of heat in guns, 337. On the elasticity of metals for cannon, 341, 349, 352. On the ductility of metals for cannon, 341, 349, 352, 353. On cast iron as a cannon metal, 371. On heavy forgings, 418, 420, 42 J, 427. 86-in. mortar by, 109. Mantelets for embrasures, Table CXLI. Martello towers, breaching, see Masonry. Masonry, breaching, 171, 272-276 B. Martello towers by rifles and smooth-bores, 273, 274, Tables XXXVIII. to XLV. Fort Pulaski, 275, 276, Tables XLVL, Fort Sumter, 276 A, Table XLVII. A. Fort Wagner, 276 B. Protected by iron, see Armor. Metals for cannon, see Chapter IV. Conclusions, 508. Mersey Steel and Iron Co.'s guns (see Horsfall Gun, Prince Alfred Gun), 118-120, 429. Test of, 121-123. Miscellaneous hooped guns, 81-92. Mortars, 109, 170. Mallet's 36-inch, 109. British, 170, Table XXVI. United States, 170. Armstrong rifled, Table LXXXIX. 57 NAITGATITOK, STEAMER, 751. Naval warfare. Chapter II., 219, 255, 261. New, 171, 172. Range of actions, 242, 251-254. Naylor, Vickers & Co/s 20-pounder gun, 146, 482. ' Steel, 68, 69, 145, 310. New British gun, 41. Noble, Captain, on long range warfare, 253. On effect of velocities of projectiles, 177. OIL, hardening in, see Hardening in Oil. Oregon gun, 125. Owen, Major C. H., on rifling and projectiles, 608, 611 PALLISER, CAPTAIN WILLIAM, on guns with vary- ing elasticity, see Varying Elasticity. On the gain of strength in wrought iron by stretching, 344. Parrott gun, 74. Patents, 1044-1051. Description, 74, 78, Table XII. Fabrication. 74, 75, 455. Material, 74, 77. Principles, 76, 78. Strength and endurance, 79, 80, 311, 1064 Cost, Tables XII., XXVII. Ammunition, Table XII. Rifling and projectiles, see Rifling and Pro- jectiles. 100-pounder, 78, ) 8-inch, 78, 79, J- Table XII. 10-inch, 78, } Parsons, P. W., Esq., on guns with varying elas- ticity, see Varying Elasticity. On the longitudinal strength of guns, 308. Peacemaker, 126, 426. Phosphorus in copper, for guns. 502. Plant in manufacture of Armstrong guns, 37, Table IV. Pressure in guns, see Strains in Guns. Prince Alfred gun, 115-117. Projectiles, see Rifling and Projectiles; Velocity of Projectiles; Armor. Armor-punching (see Part II.), 231, 246, 247, 887. Experiments, see Armor; Guns. Whitworth, 584-587 ; manufacture, 584- 586; bursting, 586. Stafford, 249, 590 Scott, 588. Parrott, 589. Bates & Macy, 590. Material, 697-712, 887-899. Shape, 713-715. Rifling necessary to, 250. Results considered, 266. Light, 248, 249, 256. 641. Breaching masonry, for, 274-276 B, Tables' XLV. to XLVII. A. Steel (see Rifling and Projectiles), 697-711^ Tables XX VI II.. XXXIII., 887-396, Lead, Table XXXV. Wrought iron (see Rifling and Projectiles); 697-711. Spherical : Higher initial velocity, 239, 241. Loss of velocity, 251. Large, advantages of, 222, 224, 257-260, 293. Firing from rifled guns, see Rifling and Projectiles. Defects and remedies, 241-245, 248. Self-destruction against armor, 246, 247. Rifled, see Rifling and Projectiles, Chapter 898 INDEX. Projectiles, rifled. Effect of, after punching armor, 262, ! 263, 2C,f>. Pnlaski, Fort, breaching of, 275. Punching armor, see Guns and Projectiles. RAM, 211, 254. Ranscs, see Rifling and Projectiles. Rapid firing, 785-741. 745-754. Requirements of suns, see Guns, Chapter II. Rifled guns, see Rifling and Projectiles; Armstrong Gun; Whitworth Gun; Blakely Gun ; Parrott Gun. Uses of, 245, 250, 251, 255, 273. Competitive trial in ls61. ,V.i2. Rifling and projectiles, 509. See Projectiles, Chap- ter V. Early, 509, 512, 543. Germe of present systems, 512. Competitive trials of east-iron rifled guns. 1861, 592. Guns, 592-595. Cost of projectiles, 593. Endurance, 596. Accuracy. CHI. Adaptation for round shot. 602. Efficiency of projectile, 005, Liability to injury, 606. Conclusion, 607. Steel projectiles, see Projectiles, Armor- IIIHI ub-c nchii;: Sub-calibre projectiles, see Projectiles. Ar- mor-punching. Light, 24S. '249. '256, 641. Masonry breaching projectiles, see. Projec- tiles. Shell* for molten metal. 591. Windase, 617-652. <;76-078. Increasing twist. 672. Elongated shot from smooth- bores, 719-724. Spherical shot from rilled guns, 79, 245, 246, Table CHI., 6!)2. Liability of projectile to injury, 636. Capacity and destructivcncss of shells, 716- 71-,. ' Russian. 5d9. 522, 557, 558. ('aval I i. 510. Wahreiidorf. 511. Timmerhaus, 511. Austrian. 5'Jl ; for gun-cotton, 521. Continental. 526. Brooke's. 105. Atwatcr's. 652. Centering system, 510, 513, 514, 625-631, 665- 696. Scott. 5;!:,-;,:;7. 5-,-. 592; trial, 1861, 537, 106S; advantages. 6ii'.). Lancaster. 527-52H. 592. 106s ; in the Crimea. 527: trials, W.I. 52->; defects. 65-v 659. Haddan, 530. 592. Thomas. 53& 5*.. French. >4. >7. 515-520. 592. 1063; Ens- lish experiments with, 516, 592; 30- poundcr. 5!x windage, see Windage; field-sun. 5->3-_>: cartridges, 532; projectile, 533, 584-5S7; practice, 534; defects, 656. 661. 60;!, G64. Sawyer. 540. Patt'ison. 541. Compressing system, 511, 543, 625-631, 665- 669. Early Prussian, 544. Rifling and projectiles, compressing system. Armstrong, 14-16, 25, 29, 80, Table I., 545; defects, C.25-G31, 642-644; particu- lars. 546, 549; practice, 547. Tables LXXX. to LXXXIX.; segmented shell, 550; cartridges. 551; mortar. Table LXXXIX. ; shunt, 14. 552, 592 particulars, 553-555; Russian, 557, 558. Expanding system, 511, 559, 625-631, 665- 669. Thomas, 567, 568, 592. Blakely. 67. 571. Jeffery, 57>. :?., r,D2. lor.s. Britten, 5s-5^!, 5!2. KM'.S; /.inc attach- ment, 5S1. American, 560; James. 564. 565; notch- kiss, 566; Sclienkl. 569; Keed, 57( ; Parrott, 79. 573, 574, 5>9. Tables X 1 1.. XC. to XCIII. ; accuracy. 575; Staf- ford, 576. ;,!)(); Buckle, 5*7. Object of rifling, 609-011. Duty of rifled guns, 60S. Range and causes affecting, 2il. 25--. 6ns. Cf',-2. Table XX XIV. See Armstn.nir. Whttworth, I'arrott, Comju-titive Trials of iMi], under Ki'liiiL: and Proiectiles. Mr. Britten's conclusions. 634, (t:5. Effect of form. C,:i7. 6:^. Of iron -clad warfare, see Naval War- fare. Of large ball Accuracy and causes affect in-, 241. 612. Want of symmetry in shot. 61;!. Velocity of rotation, 614. Centre Of gravity, 615. 6i!>-6-23. Friction against the air. 616. Character of project ile, C.-.-5-''; 1 ,!. Velocity and causes atVectin-. (>!9. 28&- 249, see Velocity of Prnjeetiles; Tables, XXVIIL, x.\ xii.. cxii. Importance of high velocity. 639, 640. Conditions of high velocity.' 641-652. Windage. 647. Strain and causes affecting. 65;j. \Veiirht of projectil Twist of rifling, 666. WcdL'ini: of jn-oji-ctile, 650. Experiments on. 6IJ4. Character of grooves. 065. Increasing twist. 672. Character of projectile, 672. Conclusions, 725. Robins. Benjamin, on rifled cannon. 60S. Rodman guns, see Cast-iron Guns; Hollow-cast (inns. Rolma. Captain, on the effects of different rates of applying force, 347 Russian iruns. Blakely, 65. Wroaght-iron, 119. Krupp's, 134. 136. Cast-iron. 169. Armor plate experiments, 235. SALVOS, 222. 223. Scott, Commander, on hooping sruns. 290, 312. On the Armstrong sun. 43S 44!. 451. On riflinsr and projectiles, COS. 627. 629, 631, 6>. 691. 692.' Sebastopol. British suns at, 1C.S. Table XXIV. Scott, Michael. Esq., on strains in suns, 221. ?',*. Shape of guns. 149, 165, 170. 390. 410. Shot. | see Proiectiles, and Rifling and Projec- Shells. \ tiles. Shrinking tubes together, 8ee Initial Tension. Shrinkage of guns in cooling, see Hollow-cast Guns. INDEX. 899 Smashing armor, see Guns. Spanish hooped guns, 81. Endurance, 81-83. Stevens's, steam-loading and cooling guns, see Breech-loading. Statical pressure, resistance to, 277. Steel, 466. See Bessemer Steel; Krupp's Steel Guns; Naylor, Vickers & Co.'s Steel. Bochnm, 310. Puddled, 148. 483. Mushet & Clare's, 147. Eussian, 134, 488. Crucible, 484. American, 490. French, 489, 487. High and low, 466. Strength of. 476. Specific gravity, test by, 479. Elasticity, see Elasticity. Ductility, see Ductility. Safety of, for cannon, 350, 351, 467, 469. Failure of, in guns explained, 468, 475. Refinement compared with iron, advan- tages, 362, 39-i, 474. Eesistance to compression, 401, 480, 481. Uniformity, 477, 4l?l. Cost, 474, Table XXVII. Weight, 474. Manufacture and improvements, 474, 483. Annealing, 46, 69, 70. 479. Hardening in oil, 35, 36, 41, 479. Armstrwng gun. 13, 41, 403. Blakely gun, 62, 68. Whitworth gun, see Whitworth Gun. Wire-wound guns, see Wire-wound Guns. Combined with cast iron, 58, 60. Anderson on, 470. 475. Initial tension on solid guns, 482. Hoops, see Initial Tension. Shells and shot (see Projectiles; Armor), 887. Armor. 213. Systems of fabrication, Hollow forging, 69, 310, 492. Solid forging, 69, 491, 482. Rollins hoops of. 68, 494. Solid casting, 495. Temper, (results, 35. 46, 48, 68-70, Treatment, j 479. Conclusions, 339. Steel guns, see Steel; Whitworth Gun ; Blakely Gun; Krupp'sGun; Bessemer Guns; Naylor, Vickers & Co.'s Guns. Endurance, Table XIX., XX., XXI., 185- 148, 475, 4S5. Fabrication, 491. Sterro-metal, 504. Stockton guns, see Wrought-iron Guns. Strains in guns, see Initial Tension; see Chapter III. Initial, 151. See Cast iron and Hollow-cast Guns. Four kinds, 134, 277. 313. Eelations of, 277. Greater in large, 221, 238, 259. Velocity of shot, effect of, 238, 240. Weight of shot, effect of, 237, 259. Increased charges, effect of, 259. Sudden, effect of, 346. Different rate of applying, effect of, 347. Unequal stretching and strain, by iuternal pressure, 278-286. Illustrations. 279, 280, 286. Law of, 279. '2s 1, 2s2, 2S5, 286. Experiments, 283, 284, 240. Thickness of walls, influence tipon, 278-286. Hoops with initial tension, influence upon, see Initial Tension. Strains in guns. Hoops with varying elasticity, influence upon, see Varying Elasticity. Sub-calibre shot, see Hilling and Projectiles. TARGETS, guns against, see Armor. Tension, initial, of hoops, see Initial Tension. Tensile strength, see Cast Iron; Wrought Iron: Steel ; Bronze. Not a true indication of safe load, 340. Thiery's hooped gun, 980. Thomas's, Lynall, guns. 34, 127. Time, effect of, on strain of guns, 347. " on cast-iron guns, 3S6, 372. Tredegar Works, Va., 1(14. Treadwell, Prof. Daniel, on strains in guns, 259, 285. On hooping guns, 288, 289. 1012. Patent for hooped guns, 1012. On the originality of the Armstrong gun. 1040. Early wrought-iron gun, 1041. Turrets, effect of shot in, 262, 263. Eesistance to shot due to shape, 181 A. UNITED STATES, guns of, 74-80, 149-166, Tables XII., XXII., XXIIL VARYING ELASTICITY, principle of, for guns, 59, 320. Theory, 320, 324, 327, 328, 333. Materials, 321, 324, 500. Safety, 322 note. Advantages, 322. Histcry, 322 note. Combined with initial tension, 59, 60, 302, 329, 330, 334. In solid guns, 322 note. Experiments. 823, 332. Blakely's plan, 322 note, 59, 60. 333, 334. Parsons'a plan, 322 note, 324-327. Palliser's plan, 322 note, 328-332. Experiments, 332. Babcock's plan, 322 note. Conclusions, 839. Velocity of projectiles (see Eifling and Projec- tiles), 259 note, Tables XXVIII., XXXI.. XXXII., CXII. Loss of, 251, Table CXII. Work done by, 181, Table XXXVI. Large balls, 259. Effect on armor (see Armor). Tables XXVIII., XXXII., 181, 193, 202, 206- 211, 237, 261. Illustration of effect, 179, 183, 261. Cause of phenomena, 180, 182, 207, 20-1 Vibration, effect on hooped guns, 299, 319, 38">. 445, 448, 450. WEIGHT OF GUNS, 354, 329, 411. Tables I., VIII., X., XII., XVIII., XXII., XXIII., XXV. to XXVII. Welds and welding, 408, 413-416, 454-463. Armstrong coils and tubes, 7, 8, 434, 419. 455^57, 461. Hitchcock's process. 460-464. Bertram's process, 459. West Point Foundry, 74 Whitworth s Publications. Gunnery Instructions. Simplified for the Volunteer Officers of the U. S. Navy, with hints to Executive and other Officers. By Lieut. -Commander EDWARD BARRETT, U. S. N., Instructor in Gunnery, Navy Yard, Brook- lyn. Third edition, revised and enlarged. 1 vol. 12mo, cloth. $1 25. "It is a thorough work, treating plainly on its subject, and contains also some valuable hints to executive officers. No officer in the volunteer navy should be without a copy." Boston Evening Traveller. "This work contains detailed and specific instructions on all points connected with the use and management of guns of every kind in the naval service. It has full illustrations, and many of these of the most elementary character, especially designed for the use of volunteers in the navy. The duties of executive officers and of the division officers are so clearly set forth, that ' he who runs may read' and understand. The manual exercise is explicit, and rendered simple by dia- grams. Forms of watch and quarter hills are given; and at the close there is a table of ranges according to the kind and calibre of gun, the weight of the ball, and the charge of powder. A valuable little hand-book." Philadelphia In- qwrer. " I have looked through Lieut. Barrett's book, and think it will be very valu- able to the volunteer officers who are now in the naval service. "C. R. P. EODGEES, Commanding U. S. Steam Frigate Wabaah." The " C. S. A." and the Battle of Bull Run. (A Letter to an English Friend.) By J. G. BARNARD, Major of Engi- neers, U. S. A., Brigadier-General, and Chief Engineer, Army of the Potomac. "With five maps. 1 vol. 8vo, cloth. $2 00. " This book was begun by the author as a letter to a friend in England, but as he proceeded and his MSS. increased in magnitude, he changed Iris original plan, and the book is the result General Barnard gives by far the best, most compre- hensible and complete account of the Battle of Bull Run we have seen. It is il- lustrated by some beautifully drawn maps, prepared for the War Department by the topographical engineers. He demonstrates to a certainty that but for the causeless panic the day might not have been lost. The author writes with vigor and earnestness, and has contributed one of the most valuable records yet pub- lished of the history of the war." Boston Commercial Bulletin. Models of Fortifications. Vauban's First System One Front and two Bastions ; Scale, 20 yards to an inch. The Modern System One Front; Scale, 20 yards to an inch. Field- Works The Square Redoubt ; Scale, 5 yards to an inch. Mr. Kimber's three volumes, viz. : Taliban's First System, The Modern System, and Field- Works, will accompany the Models. Price for the Set of Three, with books, $100. D. Van Nostranfrs Publications. Siege of Bomarfund (1854). Journals of Operations of the Artillery and Engineers. Published by permission of the Minister of War. Illustrated by maps and plans. Translated from the French by an Army Officer. 1 vol. 12mo, cloth. $1.00 "To military men this little volume is of special interest. It contains a translation by an officer of the United States Army, of the journal of operations by the artillery and engineers at the siege of Bomarsund in 1854, published by permission of the French Minister of War in the Journal des Armees speciales et c/e VEtat Major. The account of the same successful attack, given by Sir Howard Douglas in the new edition of his work on Gunnery, is appended; and the narrative is illustrated by elaborate maps and plans." New York Paper. Lefsons and Practical Notes on Steam, The Steam-Engino, Propellers, &c., &c., for Young Marine Engi- neers, Students, and others. By the late W. R. KING, U. S. N. Revised by Chief-Engineer J. W KING, U. S. Navy. Fifth, edition, enlarged. 8vo, cloth. $2.00 "This is the second edition of a valuable work of the late W. E. KING, U. S. N. It contains lessons and practical notes on Steam and the Steain- Engine, Propellers, &c. It is calculated to be of great use to young marine en- gineers, students, and others. The text is illustrated and explained by numerous diagrams and representations of machinery. This new edition has been revised and enlarged by Chief Engineer J. W. KING, U. S. N., brother to the deceased author of the work." Boston Daily Advertiser. " This is one of the best, because eminently plain and practical, treatises on the Steam-Engine ever published." Philadelphia Press. " Its re-publication at this time, when so many young men are entering the service as naval engineers, is most opportune. Each of them ought to have a copy.'" 1 Philadelphia Evening Bulletin. Manual of Internal Rules and Reg- ulations for Men-of-War. By Commodore U. P. LEVY, U. S. N., late Flag-officer command- ing U. S. Naval Force in the Mediterranean, &c. Flexible bine cloth. Second edition, revised and enlarged. 50 cents. "Among the professional publications for which we are indebted to the war, we willingly give a prominent place to this useful little Manual of Rules and Regulations to be observed on board of ships of war. Its authorship is a suffi- cient guarantee for its accuracy and practical value ; and as a guide to young officers in providing for the discipline, police, and sanitary government of the vessels under their command, we know of nothing superior." A. Y. Herald. " Should be in the hands of every Naval officer, of whatever grade, and will not come amiss to any intelligent mariner." Boston Traveller. " A work which will prove of great utility, ir. both the Naval service and the mercantile marine." Baltimore American. D. Van Nostrand^s Publications. Notes on Sea-Coaft Defence : Consisting of Sea-Coast Fortification ; the Fifteen-Inch Gun ; and Casemate Embrasures. By Gen. J. G. BARNARD, Corps of Engineers, U. S. Army. 1 vol. 8vo, cloth, plates. $2 00. "This small volume bv one of the most accomplished officers in the United States service is especially valuable at this time. Concisely and thoroughly Major Barnard discusses thf> subjects included in this volume, and gives infor- mation that will be read with great profit by military men, and by all interested in the art of war as a defensive force," New York Commercial. "It is no light compliment when we say that Major Barnard's book does no discredit to the corps to which he belongs. He writes concisely, and with a thorough knowledge of hia bubject. 1 ' Ru#selFa Army and Navy Gatette. Infractions for Naval Light Artillery, Afloat and Ashore. By Lieut. S. B. LUCE, U. S. N. 1 TO!. 8vo, with 22 lithographic plates. Cloth. $3.00, Steam for the Million. A Popular Treatise on Steam and its Application to the Useful Arts, especially to Navigation. By J. H. WARD, Commander U. S. Navy. New and revised edition. 1 vol. 8vo, cloth. $1. "A most excellent work for the young engineer and general reader. Many facts relating to the management of'the boiler and engine are set forth with a simplicity of language, and perfection of detail, that brings the subject home to the reader. Mr. Ward is alt> > peculiarly happy in his illustrations. American Engineer. Screw Propulfion. Notes on Screw Propulsion, its Rise and History. By Capt. W. H. WALKER, U. S. Navy. 1 voL 8vo., cloth. 75 cents. "Some interesting notes on screw propulsion, its rise and progress, have just been issued by Commander W. H. WALKER. U. S. N., from which all that is likely to be desired on the subject may be readily acquired. * * * * After thoroughly demonstrating the efficiency of the screw, Mr. Walker proceeds to point out the various other points to be attended to in order to secure an effi- cient man-of-war, and eulogizes throughout the readiness of the British Admi- ralty to test every novelty calculated to give satisfactory results. _ * Commander Walker's book contains an Immense amount of concise practical data, and every item of information recorded fully proved that the various points bearing upon it have been well considered previously to expressing an opinion." London Mining Journal. " Every engineer ehould have it in his library." American Engineer. D. Van Nostranfrs Publications. Evolutions of Field Batteries of Artillery. Translated from the French, and arranged for the Army and Militia of the United States. By Gen. ROBERT ANDERSON, U. S. Army. Published by order of the War Department. 1 vol. cloth, 32 plates. $1. WAE DEPARTMENT, Nov. 2rf, 1859. The System of "Evolutions of Field Batteries," translated from the French, and arranged for the service of the United States, by Major Robert Anderson, of the 1st liegiment of Artillery, having been approved by the President, is published for the information and government of the army. All Evolutions of Field Batteries not embraced in this system are prohibited, and those herein prescribed will be strictly observed. J. B. FLOYD, Secretary of War. "This system having been adopted by the "War Department, is to the artil- lerist what Hardens Tactics is to the infantry soldier ; the want of a work like this has been seriously felt, and will be eagerly welcomed." Louisville Journal. Hiftory of the United States Naval Academy With Biographical Sketches, and the names of all the Superintendents, Professors and Graduates, to which is added a Record of some of the earliest Votes by Congress, of Thanks, Medals and Swords to Naval Officers. By EDWARD CHAUNCEY MARSHALL, A. M., formerly Instructor in Captain Kinsley's Military School at West Point, Assistant Professor in the N. Y. University, etc. $1. Ordnance and Gunnery. A Course of Instruction in Ordnance and Gunnery. Compiled for the Use of the Cadets of the United States Military Academy. By Captain J. G. BENTON, Ordnance Department U. S. A., late Instructor of Ordnance and the Science of Gunnery, U. S. Mili- tary Academy, West Point, and First Assistant to the Chief of Ordnance, U. S. A. Second edition, revised and enlarged. 1 vol. 8vo, half morocco, $5. Capt. Benton has carefully revised and corrected this valuable work on Ord- nance and Gunnery, the first edition of which was published only about a year ago. The many important improvements introduced in this branch of the service have rendered such a revision necessary. The present edition will be invalua- ble, not only to the student, but as a standard book of reference on the subject D. Van Nostrand^s Publications. Scott's Military Dictionary. Comprising Technical Definitions ; Information on Raising and Keeping Troops ; Actual Service, including makeshifts and improved materiel, and Law, Government, Regulation, and Administration relating to Land Forces. By Colonel H. L. SCOTT, Inspector-General U. S. A. 1 vol., large octavo, fully illustrated, half morocco. $6. " It is a complete Encyclopaedia of Military Science." Philadelphia Even- ing Bulletin. 44 We cannot speak too much in legitimate praise of this work." National Intelligencer. 44 It should be made a Text-book for the study of every Volunteer." Har- per's Magazine. "We cordially commend it to public favor." Washington Globe. 4 'T' is comprehensive and skilfully prepared work supplies a want that has long been felt, and will be peculiarly valuable at this time as a book of refer- ence." Soxton Commercial Bulletin. 44 The Military Dictionary is splendidly got up in every way, and reflects credit on the publisher. The officers of every company in the service should possess it" .& Y. Tablet. 44 The work is more properly a Military Encyclopaedia, and is profusely illus- trated with engravings. It appears to contain every thing that can be wanted In the shape of information by officers of ail grades." Philadelphia North American. "This book is really an Encyclopaedia, both elementary and technical, and as such occupies a gap in military literature which has long been most incon- veniently vacant. This book meets a present popular want, and will be secured not only by those embarking in the profession but by a great number of civilians, who are determined to follow the descriptions and to understand the philoso- phy of the various movements of the campaign. Indeed, no tolerably good library would be complete without the work." New York Times. 44 The work has evidently been compiled from a careful consultation of the best authorities, enriched with the results of the experience and personal knowledge of the author."^". Y Daily Tribune. " Works like the present are invaluable. The officers of our Volunteer ser- vice would all do well to possess themselves of the volume." JV. Y. Herald. New Bayonet Exercise. A New Manual of the Bayonet, for the Army and Militia of the United States. By Colonel J. C. KELTON, U. S. A. With thirty beautifully-engraved plates. Red cloth. $2.00 This Manual was prepared for the use of the Corps of Cadets, and has been introduced at the Military Academy with satisfactory results. It is simply the theory of the attack and defence of the sword applied to the bayonet, on the authority of men skilled in the use of arms. The Manual contains practical lessons in Fencing, and prescribes the de- fence against Cavalry and the manner of conducting a contest with a Swords- man. " This work merits a favorable reception at the hands of all military men. It contains all the instruction necessary to enable an officer to drill his men in the use of this weapon. The introduction of the Sabre Bayonet in our Army renders f, knowledge of tho exercise more imperative." -New York Times, D. Van N^ostrand^s Publications. Hand- Book of Artillery, For the Service of the United States Army and Militia. New and revised edition. By Maj. JOSEPH ROBERTS, U. S. A. 1 vol. 18ino, cloth, New and enlarged edition. $1 25. " A complete catechism of gun practice, covering the whole ground of this branch of military science, and adapted to militia and volunteer drill, as well as to the regular army. It has the merit of precise detail, even to the technical names of all parts of a gun, and how the smallest operations connected with its use can be best performed. It has evidently been prepared \\ith great care, and with strict scientific accuracy. By the recommendation of a committee appointed bv the commanding officer of the Artillery School at Fort Monroe, Va., it has been substituted for ' Burns 1 Questions and Answers,' an English work winch has heretofore been the text-book of instruction in this country." New York Century, New Infantry Tactics, For the Instruction, Exercise, and Manoeuvres of the Soldier, a Com- pany, Line of Skirmishers, Battalion, Brigade, or Corps d'Armee. By Brig.-Gen. SILAS CASEY, U. S. A. 3 vols. 24mo. Half roan, lithographed plates. $2.50. VOL. I. School of the Soldier ; School of the Company ; In- struction for Skirmishers. VOL. 1L School of the Battalion. VOL. IIL Evolutions of a Brigade; Evolutions of a Corps d'Armee. The manuscript of this new system of Infantry Tactics was carefully ex- amined by General MCCLET.LAN, and met with his unqualified approval, which he has since manifested by authorizing General CASEY to adopt it for his entire division. The author has retained much that is valuable contained in the sys- tems of SCOTT and HAKDEE, but has made many important changes and addi- tions which experience and the exigencies of the service require. General CASEY'S reputation as an accomplished soldier and skilful tactician is a guar- antee that the work he has undertaken has been thoroughly performed. "These volumes are based on the French ordonnances of 1831 and 1845 for the manoeuvres of heavy infantry and chaxxeurs d pied ; both of these systems have been in use in our service for some years, the former having been trans- lated by Gen. Scott, and the latter by Col. Hardee. After the introduction of the latter drill in our service, in connection with Gen. Scott's Tactics, there arose the necessity of a uniform system for the manoauvres of all the infantry arm of the service. These volumes are the result of the author's endeavor to communicate the instruction, now used and adopted in the army, to achieve this result." Boston Journal. " Based on the best precedents, adapted to the novel requirements of the art of war, and very full in its instructions, Casey's Tactics will be received as the most useful and most comprehensive work of its kind in our language. From the drill and discipline of the individual soldier, or through all the various combinations, to the manoeuvres of a brigade and the evolutions of a Corps D'Armee, the student is advanced by a clear method and steady progress. Nu- merous cuts, plans, and diagrams illustrate positions and movements, and de- monstrate to the eye the exact working out of the individual position, brigading, order of battle, &c., &c. The work is a model of publishing success, being in three neat pocket volumes." Jfew Yurfcer. D. Van Nostranfrs Publications. A Treatife on Ordnance and Naval Gunnery. Compiled and arranged as a Text-Book for the IT. S. Naval Acad- emy, by Lieutenant EDWARD SIMPSON, U. S. N. Second edi- tion, revised and enlarged. 1 vol. 8vo, plates and cuts, half morocco. $5. " As the compiler has charge of the instruction in Naval Gunnery at the Naval Academy, his work, in the compilation of which he has consulted a large number of eminent authorities, is probably well suited for the purpose designed by it namely, the circulation of information which many officers, owing to constant service afloat, may not have been able to collect. In simple and plain language it gives instruction as to cannon, gun carriages, gun powder, projectiles, fuzes, locks, and primers; the theory of pointing guns, rifles, the practice of gunnery, and a great variety of other similar matters, interesting to fighting men on sea and land," Wa/iington Daily Globe. "A vast amount of information is conveyed in a readable and familiar form. The illustrations are excellent, and many of them unique, being colored or bronzed so as to represent various military arms, &c., with more than photo- graphic literalness." Washington Star. "It is scarcely necessary for ns to say that a work prepared by a writer so practically conversant with all the subjects of which he treats, and who has such a reputation for scientific ability, cannot fail to take at once a high place among the text-books of our naval service. It has been approved by the Secretary of the Navy, and will henceforth be one of the standard authorities on all matters connected with Naval Gunnery." New York Herald. " The book itself is admirably arranged, characterized by great simplicity and clearness, and certainly at this time will be a most valuable one to officers of the Navy." .Boston, Commercial Bulletin. u Originally designed as a text-book, it is now enlarged, and so far modified in its plan as to make it an invaluable hand-book for the naval officer. It is comprehensive preserving the cream of many of the best books on ordnance and naval gunnery, and is printed and illustrated in the most admirable man- ner." New York World. Elementary Inftruction in Naval Ordnance and Gunnery. By JAMES H. WARD, Commander U. S. Navy, Author of " Naval Tactics," and "Steam for the Million." New edition, revised and enlarged. 8vo. Cloth, $2. " It conveys an amount of information in the same space to be found no- where else, and given with a clearness which renders it useful as well to the general as the professional inquirer." N. Y. Evening Post. "This volume is a standard treatise upon the subject to which it is devoted. It abounds in valuable information upon all the points bearing upon Naval Gunnery." N. Y. Commercial Advertiser. "The work is an exceedingly valuable one, and is opportunely issued." Boston Journal, y RETURN TO: CIRCULATION DEPARTMENT 198 Main Stacks LOAN PERIOD 1 Home Use 2 3 4 5 6 ALL BOOKS MAY BE RECALLED AFTER 7 DAYS. Renewals and Recharges may be made 4 days prior to the due date. Books may be renewed by calling 642-3405. DUE AS STAMPED BELOW. AUG 2 20 SENT ON ILL Jill 8 2005 U.C. BERKELEY FORM NO. 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