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Full text of "A treatise on ordnance and armor: 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 their rifling, projectiles and breech-loading"

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 
<<V1/1/ IxO^Li s l i( l forgings of steel. For the 40-pounders and 

* | 110-pounders, they are iron, with steel ends to 

Thread of Breech- bear against the vent pieces. The threads are 
thus shaped (Fig. 15) to prevent their wedging. 

The vent-pieces have usually turned out to be the weakest 
parts, especially of the larger guns. Steel has long been used 
for the smaller guns ; but until steel toughened in oil was tried, 
C ( and Co Swedish iron was the only material that would stand 
at all in the 110-pounders. Some vent-pieces of sandwiched iron 
and steel were unsuccessful. 

Fig. 16 shows the 12-pounder vent-piece in section. The 
copper ring a is jammed by the screw against the bevelled end 
of the inner tube, to prevent the escape of gas. No copper ring 
is used on the 110-pounder, 70-pounder, or 40-pounder vent- 
pieces. On the 110-pounder, a thin cup of tin is inserted behind 

* Discussion on "Construction of Artillery." Inst. Civil Engineers, 1860. 
f Evidence before Select Committee on Ordnance, 1863. 

| Both these forms and their results will be fully described in the chapter on 
"Breech-loading." 



HOOPED GUNS. 




Armstrong 1 1 0-pounder. 
in. to 1 ft. 



10 ORDNANCE. 

the cartridge, to stop the escape of gas past the vent-piece. This 
cup only stands one round. The vent is made in the vent-piece, 
and can thus be easily renewed. 

14. RIFLING. The rifling of the Armstrong gun is peculiar, 
and will be discussed farther on. The twist of the grooves is a 
regular screw, having one turn in 37 calibres for the 110 pound- 
er, and about the same pitch for the field pieces. Figs. 12 
and 13 show standard forms of Armstrong rifling four times 
enlarged. The depth of the grooves in the 12-pounder is 
045 in. ; their width, '148 in. The number of grooves in the 
110-pounder is 76; in the 12-pounder, 38. The shape and size 
of grooves in all the service guns, from 6-pounders to 110- 
pounders, is nearly the same. 

The object of the multigroove system is to give a large 
bearing for the soft covering (lead hardened with tin) of the 
Armstrong projectiles, so as to prevent their stripping. 

The "shunt" rifling consists of a smaller number of larger 
grooves, arranged to centre and compress the shot as well as ro- 
tate it. The projections on the shot were, at first, cast on and 
faced with zinc. Zinc strips, or brass or other studs, let into 
the shot, are now used. 

15. The bore of the Armstrong breech-loader has several 
different diameters (Fig. 18). The powder-chamber, at the rear, 
is the largest part (in the 110-pounder it is 7*2 in.), and has 
no grooves. The shot-chamber is slightly smaller (in the 110- 
pounder, 7'075 in.) than the powder-chamber, but it is larger 
than the adjacent part of the bore forward (7 in. in the 110- 
pounder), and has, at its front, the commencement of the lands 
of the rifling. Beyond the shot-chamber, the grooves of the 
rifling extend with uniform depth to the muzzle ; but from a 
point a few inches in front of the shot-chamber, to a point a few 
inches in rear of the muzzle, the bore is slightly enlarged, that is 
to say, the tops of the lands are cut down a little. The object is 
to mould the lead covering of the shot at the first instant of 
motion, to give it freedom in traversing the remainder of the 
bore, and to nip it and centre it at the muzzle. 



HOOPED GUNS. 



11 




12 



ORDNANCE. 



The rifling is at present done by a cutter that planes two 
grooves at once. A tool for cutting 76 grooves at once was 
shown in the Great Exhibition, but has not been put into service. 

TABLE I. PARTICULARS OF SERVICE ARMSTRONG GUNS. 



XAMK OF Gux 


Weight 


Diameter 
of bore. 


Length of 
bore. 


No. of 
grooves. 


Twist of 

rifling. 




Ibs. 
0184. 


in. 


in. 


76 


1 turn in 

calibres. 




7640 


47 ? 


1 20 


<6 


i in 364 


4o-pounder, new 


3986 

I7Q2 


4'75 


120 
06 


56 


i in 36^- 


I2-pounder 


12 


/.) 

3' 


yu 

84 I2C 


og 


i in 38 




68o-2C 




62 


-8 




6-pounder ... 


^6 


2 r 


60 ' i c 


j 


i in 30 















TABLE II. SERVICE AMMUNITION OF SERVICE ARMSTRONG GUNS. 



NAME OF GUN. 


Charge 
for shot. 


C"h:irre 
for shell. 


TVeiirht 
of shell 
total 


Bursting 
charge. 


Weight 
segmental 
shell. 


Bursting 
charge 
segmental 
shell. 


No. of 
segments. 

Ill 

ill 

72 
5 6 or 14 
42 or 6 

35 or 6 
12 or 1 8 


I lo-pounder 


Ibs. 
14* 

10 

5 
^ 

*i 
i\ 


Ibs. 
12 

J2 

5 

2} 

-i 

ii 


Ibs. 
106 

106 
4i 
ii 


Ibs. 
8 

8 

-v 


Ibs. 

101 

101 

Ibs. oz. 
39 i 

19 11-23 
10 8-98 
8 15-68 
5 7'4i 


Ibs. 
3 

3 
oz. 

10 

1-23 

58 

68 
4i 


Do. light. 
4o-pounder 


2o-pounder 




o-pounder 


6-pounder 


J 


i 


.... 







1G. PROOF. f The proof of the Armstrong gun was, till 
within about a year, as follows : Two rounds with double service 
charge and one service shot, and five rounds with one shot and 

* This charge has generally been reduced to 12 Ibs. 
f Evidence, Select Committee on Ordnance, 1863. 



HOOPED GUNS. 



13 



a charge of one-sixth the weight of the service shot. The present 
proof is two rounds with service charge and shot, and three 
rounds with service shot and a charge of one-sixth the weight 
of the service shot. 

TABLE III. ARMSTRONG GTJNS ISSUED FOR SERVICE, SHOWING 
WHERE MADE. 

From the Report of the Select Committee on Ordnance, 1863. 



NAME OF GUN. 


No. issued 
Elswick 
Ordnance Co. 


No. issued 
Koyal Gun 
Factory. 


Total 
No. issued. 




I7Q 


620 


7QQ 


AO-pounders 


C 7 C 


106 


64.1 


2O-pounders, land service 




16 


jr 


2O-pounders. sea service 




231 


232 


12-pounders, land service 


7Q 


313 


3Q2 


12-pounders sea service 




178 


178 


o-pounders 




66 


66 






37 


37 










Grand total 


807 















17. GUNS DESCRIBED.* The tables 1 and 2 are compiled from 
the latest British Artillery records. 

* From the testimony of Col. Lefroy, 2d July, 1862, lefore the Select Committee on 
Ordnance : 

" Chairman. Can you inform the Committee what wrought-iron and steel guns 
have been introduced into the service since the beginning of 1858? An Armstrong 
110-pounder gun; another Armstrong 110-pounder gun somewhat heavier, called the 
strengthened pattern ; an Armstrong 40-pounder gun. Another shorter 40-pounder 
Armstrong gun ; two varieties of 20-pounder Armstrong guns. 

" Col Dunne. Are those all rifled? Yes. An Armstrong 12-pounder weighing 
8 cwt. ; another weighing 8 cwt. ; another weighing G cwt. ; of the latter, only a 
few were made for service in China. An Armstrong 9-pounder, weighing 6 cwt. ; 
an Armstrong 6-pounder, 3 cwt. ; those are all the wrought-iron rifled guns which 
have been introduced into the service, and they are all breech-loaders. There are 
other experimental guns which are not yet introduced. I find that in that enumera- 
tion I have omitted one 7 in. howitzer. 

" Sir John Hay. "Will you now mention the experimental guns which have not 
been introduced into the service? A wrought-iron muzzle-loading Armstrong gun 
of 120 Ibs. ; a side breech-loading 110-pounder; an 80-pounder, or 6 in. gun; an 



14 ORDNANCE. 

21. There are two classes of 110-pounders : the light gun, 
weighing 8400 Ibs., of which about 100 only were made, but not 
issued; and the heavy service gun, described in the foregoing 
table. The maximum diameter of the latter is 27 in. ; diameter 
at the muzzle, 13 in. Some 110-pounders, weighing 9632 Ibs., 
have been constructed, but the standard weight is 9181 Ibs. 

Armstrong 70-pounder, with a new breech-loading arrangement; and another, a 
muzzle-loader; an Armstrong 40-pounder, with new breech-loading arrangement; 
the Armstrong 150-pounder, smooth-bored gun, lately tried at Shoeburyness, which, 
if rifled, will be a 300-pounder; and three guns known as the 18-pounder, 24-pounder, 
and 32-pounder, which were produced in the early stage of the inquiry." 

The following extracts are from a "Memorandum by the Director of Ordnance" 
(Major-General Tulloh), on trials of and changes in the Armstrong gun. Report of 
Select Committee on Ordnance, 1SG2 : 

"The G-pounder gun was adopted at the same period as the 12-pounder; a few 
guns of this nature have been made for the naval service, but its use on land being 
limited to mountain service, the manufacture has not proceeded to any great extent. 

"The 12-pounder was recommended for adoption into the service by the Special 
Committee on "Rifled Cannon, in their Report dated the IGth November, 1858. 

"The 25-pounder was adopted into the service in 1859; a gun of nearly similar 
calibre, 3'25 inches (the 25-pounder being 3'75), had been very extensively tried by 
the Rifled Cannon Committee in 1858, for range, accuracy, penetration, and endu- 
rance, the results being most satisfactory. Since 1S59, the rifling of this class of 
gun has been slightly modified, being now one turn in 37 calibres, instead of one ia 
33, as originally. * * * The gun itself has undergone no alteration, further thaa 
that above specified; these experiments have, however, led to the adoption of a 
lighter projectile (viz., about 21 Ibs.) than that originally used, and the designation of 
the gun has been accordingly changed to a 20-pounder. 

" The 40-pounder gun was recommended as a calibre for adoption in the navy by 
the Special Committee on Iron Plates and Rifled Cannon (Colonel St. George, C. B., 
President) on the 24th September, 1859. As in the case of the 20-pounder, the 40- 
pounder class sprang from a model gun which had been tried with success by the 
Rifled Cannon Committee in 1858 (viz., a 32-pounder of 4 in. bore). In October, 
1860, it was deemed desirable to strengthen the 40-pounder by the addition of another 
coil at the breech, more as a matter of precaution than from any symptoms of weak- 
ness in the guns as originally constructed. 

"The 100-pounder maybe said to have originated in the 80-pounder of G3 cwt, 
which was made by Sir "Wm. Armstrong early in 1859, and tried at Shoeburyness. 
The original weight of the 100-pounder, as recommended by the above committee, 
was 65 cwts., but an extra coil was subsequently added at the breech, which 
brought the weight up to 81 cwts. Three hundred 100-pounders were ordered to 
be made in the year 18GO-G1, to supply the very urgent demands of the navy. 

" In the course of subsequent experiments with 100-pounder guns, it was found 
that a solid shot of 110 pounds weight could be fired from them with 14 Ibs. charge, 
without causing any excessive strain upon the gun, or unmanageable recoil ; the 
provisional adoption of this projectile was therefore authorized in July, 18G1, and a 
standard pattern having been subsequently approved, the designation of the gun has 
been changed to 110-pounder." 



HOOPED GUNS. 



15 



TABLE III A. PARTICULARS OP ARMSTRONG GUNS OP THE LATEST ELSWICK 

PATTERNS. 

From Official Drawings. 



NAME OF GTTN. 


Length 
of Gun. 


Length 
of Bore. 


Diam. 
of Bore. 


Diameter 
over powder 
chamber. 


Diam. at 
Muzzle. 


Weight. 


Prepon- 
derance. 


12-pounder Breech Louder... 


ins. 
81 


ins. 

77*C 


ins. 


ins. 

97 ^ 


ins. 

r -7 r 


Ibs. 
918 


Ibs. 


12-pounder Muzzle Loader.. 


76 


6775 


3 


10-9 


5-6 


996 


60 


25-pounder Breech Loader.. 


96 


93 


3'75 


12-75 


6 


1882 


123 


4o-pounder Do. 


121 


106-5 


475 


1 6-4 


775 


3696 


39 2 


yo-pounder Muzzle Loader.. 


126-5 


103-0 


6-4 


2 5'3 


12-4 


9016 


548 


l5O-pounder Do. 
3OO-pounder Do 


129-75 
i<6 


102-25 
124. 


8-5 
10 


3 1 

18-1 


15-4 

IQ 


14896 
26880 


54 


6oo-pounder Do. 


183 


145-25 


'3'3 


5 I- S 


21-5 


51296 


952 



. Two experimental 120-pounder shunt rifles, of 7 in. 
bore, have been constructed ; the one a muzzle-loader, and the 
other a side breech-loader. 

23. A 7-J- ton 7 in. muzzle-loading gun, called the Cupola 
Gun, or New Naval Gun. lias been completed. The inner 
barrel is a solid steel tube. The reinforce is excessively heavy, 
being 38 in. in diameter. The size suddenly decreases in front 
of the trunnions. At the muzzle the diameter is 13 in. The 
length of bore is 108 in. The rifling of this class of ordnance 
will depend upon the results of experiments with trial 7 in. guns 
lately constructing. Some fifty 100-pounders of this general 
construction have been ordered. (41.) 

24. An experimental 6*4 in. gun has been constructed at 
Woolwich, to be rifled and loaded at the breech on Mr. Westley 

NOTES. The old 25-pounder land-service gun was changed to the present service 
20-pounder. 

One 70-pounder muzzle loader has been rifled on the shunt plan with 6 grooves. 

Two 80-pounders of 6-in. bore have been constructed. One was used in the breach- 
ing experiments at Eastbourne. (273.) 



16 



ORDNANCE. 



1 


FIG. 22. 

pSfflffPMWSti 

* 1 

S 


Richards' plans. It is about 18 feet 
long, and will weigh nearly ten tons, 
thus having an enormous margin of 
metal in proportion to its calibre. 
V 25. A 200-pounder side breech- 
> 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 


<l CAQ4.7 14. C 


<l7IOQQ 14- C 






$80760 


$774738 60 


$855498 60 





To analyze these expenses in much detail would hardly be 
important, since the values of labor and materials, and the em- 
ployment of labor-saving machinery in the two countries cannot be 
closely compared, while no probable amount of cost is to be con- 
sidered objectionable, if this or a similar process of construction 
should finally produce the best guns. 

The whole sum expended at Woolwich and Elswick, in plant 
and in producing about 3000 Armstrong guns, with the necessary 
carriages and ammunition, up to the time of the Select Commit- 
tee's Report, in 1863, was $12697739.41.* 

38. According to Mr. Anderson, the average cost of the 110- 
pouiider, for materials and labor, during 1860 and 1861, was 

* "1. The sum of 965117 9s, 7d. has been paid to the Elswick Ordnance Com- 
pany for articles supplied. 

" 2. After giving credit for the value of plant and stores received from the com- 
pany, a sum of 65534 4s. has been paid to the Elswick Ordnance Co. as compensa- 
tion for terminating the contract. 

" 3. The outstanding liabilities of the War Office to the Elswick Ordnance Co., 
for articles ordered, amounted on the 7th of May last to the sum of 37143 2s. lOd. 

"The whole of these payments and liabilities amounts to the sum of 1067794 
16s. 5d. 

"4. The sum of 1471753 Is. 3d. has been expended in the three manufacturing 
departments at Woolwich on the Armstrong guns, ammunition, and carriages, making 
altogether a grand total of 2539547 17s. Sd." Report of Select Committee on Ord- 
nance, 1863. 



HOOPED GUNS. 23 

$1575 (315) per gun; but including contingent expenses, it was 
$2000, while for the depreciation of plant and buildings, $200 
more should be added, making a total of $2200 per gun. During 
1862-3, the cost would be $2195.75 (439 3s.), not including rent 
and profits. The Woolwich establishment could turn out thirty 
such guns per week.* 

The cost of the 150-pounder smooth-bores (10-J- in. gun) and 
of the 300-pounder rifles (the same 10^ in. gun, rifled) is about 
$9000 each. The 200-pounder breech-loader costs about $6000. 

The cost of the larger Armstrong guns is from 24 cts. to 34 cts. 
per pound. (See table of cost of guns.) 

39. ENDURANCE. The strength and endurance of the Arm- 
strong gun w r ill be considered more in order, after the discussion 
of cannon metals, in a following chapter. (443.) 

In general terms, the gun is very strong to resist bursting 
strains acting in the direction of the radii, but it is not propor- 
tionately strong longitudinally. 

The wrought iron permanently changes its figure, under high 
charges, both in the chamber of the gun and in the rings. With 
wrought iron, certainly, the "built-up" principle seems to have 
been carried too far; the guns want homogeneity and mass to 
resist the destructive effects of relaxation and vibration. 

Both the enormous pressure and strain due to forcing the shot 
through the multigroove rifling, and the shock due to the center- 
ing and nipping of the shot in the shunt rifling, aggravate these 
effects. 

The least trustworthy part of the gun is the breech-loading 
apparatus. The muzzle-loaders of moderate bore, perhaps up to 
9'22 in., are likely to prove very formidable, although they cannot 
be relied on for long service, without frequent repair and readjust- 
ment of tubes and rings that is to say, rebuilding. 

40. But although the Armstrong gun is costly in construction 
and maintenance, it is not likely to burst without warning, or to 
seriously injure the men or things immediately around it when it 
does give way. Not one of the 3000 guns built and tested has, 

* Report of Select Committee on Ordnance, 1862. 



24 



ORDNANCE. 



TABLE Y. COST OF LABOR AND MATERIAL, including all Incidental Expenses, to pro- 
duce One 100-pounder Armstrong Gun, ready for Proof, with Two Yent-Pieces. 
(From the Report of the Select Committee on Ordnance, 1862.) 

[But the repairs of any defects developed at proof would be an extra charge.] 












r*l 
O 




ON-S 


. 


CO* 






r) 




vo ON 











Tj- 




M vn 


H 


09 






n 




=j| 


. 


06 






t~^ 


ro ^ 
t-- C 


s 


s 


<fl 






H H 

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and breech-screws (contract 

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expenses, including indirect 
rs, miscellaneous labor, offic 
veiling, poftage, telegrams 
irs, gas, water, police, hors 
er cent.... 






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111 
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[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^ 


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cocooo C-ON^W Q-co 

W) CO O CO CO 


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4* -* HI 

^ : i : ^ 2 M 2" 

r^ O c* to oo ON oo 


Cost of Labor. 


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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- 
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& 

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 <xun. The inventions of Mr. 
Joseph Whitworth, the distinguished mechanical engineer, with 
reference to Artillery, have consisted chiefly in his system of 
rifling and projectiles, and will be considered under that head. His 
celebrity is now beginning to extend to the manufacture of guns, 
especially to the fabrication of built-up steel guns. Although 
Mr. Whitworth has Yin. and 9 in. cannon of this kind in hand, 
his 5Jin. (TO-pounder) gun is the largest that has been regularly 
proved and adopted. Above thirty pieces of this calibre have 
been fabricated.* 

43. The 120-pounder (sometimes called 130-pounder and 150- 
pounder) gun (Fig. 27), from which Whitworth projectiles were 
fired through the Warrior target, was fabricated at the Royal Gun 
Factory, Woolwich, on the Armstrong plan, except that the 
inner tube was a solid wrought-iron forging, bored out. This 
gun is a muzzle-loader, of 31 in. maximum diameter, and weighs 
16660 Ibs. 

The 120-pounder of Mr. Whitworth's manufacture (Fig. 26) is 
a much lighter gun, weighing but six tons. 

* Evidence of Mr. Whitworth, Select Committee on Ordnance, 1863. 



28 



ORDNANCE. 



FIG. 2 



Whitworth 7 -in. 120-pdr. 



44. PRINCIPLES. Mr. WMtwortli's 

principle of construction, and the fea- 
tures which distinguish it from the simi- 
lar system of Sir William Armstrong, 
are thus set forth by Mr. Anderson,* 
in his description of the 120-pounder 
proposed by Mr. Whit worth (Fig. 28), 
and the 120-pounder referred to above, 
as actually built at Woolwich (Fig. 27), 
and rifled on Mr. Whitworth's plan : 

"The two guns viz., that which Mr. 
Whitworth would have preferred, and 
that which was constructed in the Royal 
Gun Factory differ in the following 
particulars: first, Mr. Whitworth's gun 
consists of twenty-four distinct parts ; the 
Royal Gun Factory gun, of twelve dis- 
tinct parts. Second, Mr. Whitworth's 
gun was intended and designed for being 
put together by hydraulic pressure ; the 
Royal Gun Factory gun was designed for 
and put together by shrinkage. Third, 
In Mr. Whitworth's gun, the parts that 
had to be united were connected by 
screws ; in the Royal Gun Factory's, the 
parts to be joined were united by the 
process of welding. Fourth, In the one 
gun the inner tube or barrel is open at 
the breech end and closed by a screw ; 
in the Woolwich gun it is solid and 
close, and without any joint. Fifth, 
The first gun is without any part tech- 



* Evidence before the Select Committee on Ordnance, 1863. Mr. Whitworth 
having stated that the gun as well as the rifling were essentially his, and the Arm- 
strong party having denied it, a considerable portion of this committee's labors were 
devoted to ascertaining the facts. 



HOOPED GUNS. 



29 





30 ORDNANCE. 

nically termed the breech-piece; in the other gun, the breech- 
piece is one of the leading characteristics. Sixth, The breech-ping 
of Mr. "Whitworth's gun consists of three screws of different diam- 
eters, formed on one stem, and made to take hold not only of the 
inner tube, but also of the second and third layers of tubes ; the 
breech screw of the Royal Gun Factory gun is of one diameter 
throughout, and is screwed into the breech-piece only, and butting 
hard against the solid end of the inner barrel. Seventh, The second 
tier of tubes in Mr. Whitworth's gun consists of eight parts, all 
screwed together into one long tube, which extends from the 
breech to the muzzle, and is screwed npon the second diameter 
of screw formed upon the breech-plug; the second tier of the 
Royal Gun Factory gun consists of one long tube extending from 
end to end of the gun that at the breech having the iron of 
double thickness, with the fibre placed longitudinally, the re- 
mainder being of coil of lesser thickness, with the fibre running 
circumferentially, which is the great leading feature of this gun. 
Eighth, The third tier of Mr. Whitworth's gun consists of six 
pieces, all screwed together into one piece, and extending to the 
extremity of the breech, and screwed upon the breech-plug; the 
third tier of the Royal Gun Factory gun consists of two pieces, 
and only extends a little beyond the trunnion, the remaining 
space being made np by the greater thickness of the breech-piece, 
which is a part of the second tier. Ninth, The fourth tier of Mr. 
Whitworth's gun consists of four pieces not united ; the fourth 
tier of the Royal Gun Factory gun comprises three pieces not 
united, but witli the last breech-hoop made to hook on to the 
breech-piece, thus giving to the breech-piece increased security. 
Tenth, The fifth tier of Mr. Whitworth's gun consists of three 
plain pieces and one trunnion piece all screwed together into one 
long piece ; the fifth tier of the Royal Gun Factory gun consists 
of two plain pieces and the trunnion piece the last of the plain 
pieces being hooked on the hoop* under it, and which again 
is hooked on the breech-piece, thus tying all three together. 

* The trunnion hoop. 



HOOPED GUNS. 31 

Eleventh, There is no sixth tier upon Mr. Whitworth's gun ; the 
sixth tier of the Royal Gun Factory gun consists of one large 
hoop to strengthen the gun over the powder-chamber. In addi- 
tion to the above, the two guns differ in the distribution of the 
material, and also in the disposition of the materials for resisting 
both lateral and longitudinal strain." * 

O 

45. FABRICATION. The smaller Whitworth guns are forged 
solid, and the principal piece or barrel for the larger guns is 
forged from a single ingot of low steel, also called "homo- 
geneous metal," and made by Messrs. Firth, of Sheffield. f This 
metal is made chiefly from bars of Swedish iron, cut into short 
lengths, melted in crucibles with a very small addition of car- 
bonaceous material, and cast into round ingots. 

46. Mr. Whitworth attaches the greatest importance to an- 
nealing the steel. After the work is roughly finished, it is an- 
nealed from three to four weeks. Mr. Whitworth states that 
he has for some time made musket-barrels so ductile that they 
bulge instead of cracking when the charge is fired with the bullet 
half way home, and that now his Tin. gun barrels are equally 
good, and will stretch instead of breaking under pressure. 

47. The breech, in case of the large guns, is hooped with a 
harder and higher steel than that, used for the barrel. The 70- 
pounder (5-J- in.) gun has one hoop ; the 120-pounder proposed by 
Mr. Whitworth was to have four tiers of hoops. 

48. These hoops are formed by hammering hollow castings 
of steel over a mandrel, or by rolling them in a machine similar 
to a tyre rolling machine (69). The short lengths thus produced 

* It was further shown before this committee, that the gun finally made of 
wrought iron was so strained and indented by the twenty or thirty high charges 
(25 Ibs. to 27 Ibs.) it had fired, as to be in a condition to require extensive 
repairs. 

f Homogeneous metal is said to have been made by Mr. David Mushet over fifty 
years ago. 

\ Sir William Armstrong stated before the Select Committee on Ordnance, 1863, 
that he has no faith in annealing; that it injures the steel. After annealing, the car- 
bon is found, by the microscope, to be deposited between the crystals. (See, also, 
chapter on Cannon Metals.) 

Evidence before the Select Committee on Ordnance, 1863. 



32 ORDNANCE. 

are screwed together end to end, instead of being welded (or 
merely stuck, as the case may be) like the Armstrong hoops. 

49. The principle discussed in a succeeding chapter, of rein- 
forcing a tube with hoops having successively increasing initial 
tension, so that they will all be equally strained at the instant 
of explosion, was not fully utilized in Mr. "Whitworth'a earlier 
practice. He put on his hoops with as great initial tension as 
the iron would bear without injury up to point of permanent 
set so that the force of the explosion altered the condition of 
the gun. The first SO-pounder* cracked from this cause.f The 
principle of initial tension is now well carried out. 

5O. Instead of shrinking; on 
FIG. 29. 

the hoops, Mr. Whitworth ta- 
pers the inner barrel one inch 
in 100 inches (Fig. 20), and 




C! 



\H=1 
forces them on cold by hydro- 
. static; pressure, with great care 
^- j '. and accuracy (295). 

Section of breech of Whitworth The method of closing the 

muzzle-loader. breech of the muzzle-loader 

(Fig. 28) is undoubtedly superior to any plan except solid forging. 
The breech-plug is screwed ncg; only into the inner tube, but into 
the next tube or ring, which cannot be pulled off without being 
also burst, on account of the taper. Or the breech-ping may 
screw into the ends of three or four concentric rings. 

The breech-loading apparatus (Fig. 30) is not now largely 
used. It is operated successfully, though not very rapidly, on 
field-pieces, but was unsuccessful on the larger guns. It consists 
of a cap screwed on externally. This cap works in a hoop which 
is hung by a hinge to the side of the breech. The vent is in the 
centre of the breech-piece. 

51. Of the 70-pounders (muzzle-loading, Fig. 31), one was 
recently the subject of experiment at the Washington Navy Yard. 
Several others, captured from the Confederates, have been in ser- 

* The breech hoops of this gun were made from Clay's puddled steel. 

f Mr. Longridge. Journal of the R U, S. Inst., March, 1861. See note J, page 35. 



HOOPED GUNS. 



33 



FIG. so. 



FIG. si. 




i 1 



V i 



Whitworth breech-loader. 



Whitworth new 70-pdr. 



vice before Charleston and elsewhere, but their adaptation to 
warfare has not been remarkable. The 70-pounder that pierced 
the Warrior plates at Shoeburyness was fabricated at Woolwich. 
The bore of the "Whitworth guns is usually hexagonal (Fig. 32); 
the projectiles are planed by special machine-tools to fit the 
rifling. The twist is very sharp, in order to give a sustaining 
rotation to long projectiles. (See Rifling, and note in Appendix.) 
i 3 



34 ORDNANCE. 

The particulars of the standard guns are given in Table VIII. 



O 



M 







5 



H 

H 



P 



* $ 8 



g O ON 



VO 

w> ro 

o 1 o 



S =2 S- 



I I 



of a 

!? I 

O "" 

d pj 

fl *" 

"~ O) 



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5 

'"> ^ 

" ^H 

O cfi 

,O ^ 

'o o 

t- a 

5 



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d ^-i 

co .d 

t ( (M 



CC CO 
O <D 



S 

b 

I 

'S 

+j 

r . "2 



n3 03 * 



HOOPED GUNS. 



35 



. The proof charge is one-quarter more than the service 



charge, one round, and then the service charge with a 6-caliber 



projectile, one round. 




Full-sized section of Whitworth's 70-pounder shot and rifling. 



53. Mr. Whitworth states* (May, 1863) that the Whitworth 
Ordnance Co. have in hand 100 guns of calibres varying from 1 J 
to 9 inches. Thirty 70-pou riders had been fabricated. 

54. As to the history of Mr. Whitworth's gun,f it was shown 
before the Select Committee on Ordnance, 1863, that his experi- 
ments with muskets were so satisfactory as to elicit a request 
from the Government, in 1856, that he would rifle some brass 
guns on this system. Their trial led to the rifling of several cast- 
iron guns, which, however, did not show sufficient endurance. 
Mr. Whitworth then made some steel guns. The smaller calibres 
were very satisfactory, but the 80-pounder breech-loader cracked.:); 

* Evidence of Mr. Whitworth, Select Committee on Ordnance, 1863. 

f The Select Committee on Ordnance (1862) having reported that "the committee 
possesses an hexagonally bored rifle, dated p]nfield, 1843 ; the more modern and per- 
fect development of the system is known to have originated with the late Mr. Brunei," 
Mr. Whitworth stated before the Committee of 1863 that he claims polygonal rifling 
only in connection with spiral segments forming the gun. He also stated that Mr. 
Westley Richards was requested, in 1852, by Mr. Brunei, to make an octagonally 
bored rifle with an increasing pitch. This he made in 1854. Mr. Richards showed 
it to Mr. Whitworth in 1855. It had sharp corners, and had a pitch of 1 in 90 to 
1 in 30 or 35. Mr. Whitworth's system, patented in 1854, was pronounced different 
from this by Mr. Brunei ; and Mr. Richards took a license from Mr. Whitworth. 

J This was attributed by a committee appointed to examine it, to an air space 
between the shot and the charge. " Story of the Guns." 

As to Mr. Whitworth's early ideas about constructing cannon, his patent of 
December 1st, 1854, specifies a gun made of segments, held together by hoops, and 
states that "the danger of a gun bursting from an overcharge of gunpowder will be 



36 ORDNANCE. 

Meanwhile, the Armstrong gun having been adopted, the Arm- 
strong rifling and projectiles naturally came with it ; and while 
neither the gun nor the rifling of Mr. "Whitworth have been as 
yet adopted by the British Government, his rifling has been ex- 
perimented with at considerable cost,* in guns constructed on the 
Armstrong plan. Mr. Whitworth 's late adaptation of low steel 
to the fabrication of cannon is more likely to become standard 
than his system of rifling. 

55. III. The Blakely Ouii. Captain T. A. Blakely is rec- 
ognized in England as one of the first to invent and the very first 
to demonstrate mathematically and reduce to a working system, 
the reinforcing of guns with hoops placed under initial tension, 
so that each hoop compresses what is within it (287). Captain 
Blakely appears also to have first proposed guns formed of con- 
centric tubes having different degrees of elasticity (320), the inner 
tube being the most elastic because it has to stretch most. Both 
these systems, when perfected, bring the entire metal of the gun 
into equal tension at the instant of firing, and both may be ap- 
plied, in a certain degree, to the same gun, with advantage. 
Upon the combined systems, the modern Blakely guns are con- 
structed. The principles involved will be further considered in 
another chapter. 

56. Most of the earlier Blakely guns were constructed by 
Messrs. Fawcett, Preston & Co., of Liverpool. These and other 
makers in England, and the Blakely Ordnance Co. in London, 
are now fabricating these guns for State governments in the 
United States (64), and for the Confederate Government, as well 
as for Russia and other European Powers. Captain Blakely 



obviated, because the strain will bo distributed throughout the length of the seg- 
ments, and by forcing the hoops or bolts to give way, will cause the joints of the seg- 
ments to open longitudinally, thus acting as safety valves, allowing the gases gener- 
ated by the explosion to escape through the joints so opened." 

* Mr. "Whitworth states that he has received 15885 for "experiments connected 
with rifle barrels, and 4735 for ordnance supplied" the Government, but that his 
company have charged him 10482, which the Government has not returned, for 
experiments of a similar nature. Select Committee on Ordnance, 1863. (For remainder 
of Note, see Table IX.) 



HOOPED GUNS. 



37 



TABLE IX. Return of all sums paid, or Expenses incurred, on account of Experiments 
connected with Mr. Whitworttts Proposals, stating for what particular Service each 
Payment has been made, and distinguishing ORDNANCE from SMALL ARMS. From 
Report of Select Committee on Ordnance, 18G2. 









OO 












00 














ON 


s 5; 


* 


8 


R s 


8 


I 










2 

r-T* 


Tl 

1 

3- 


Coft of conftrudling y-inch muzzle-loading gun 
on Mr. Whitworth's plan, in Royal GUI 


Coftof tefting 8o-pounder breech-loading gun..., 
Coft of experiments with yo-pounder muzzle 
loading gun, authorized, 2,y 3 62, ftill in pro 
erefs.... 


Coft of erefting oak target for experiments a 
Shoeburvnefs ... 


"* O 

i 

M 

n 
5' 

rt 

D- 

I 

O 

c 


Coft of conftrucYmg two yo-pounder muzzle 
loading guns, on Mr. Whitworth's plan, i: 
the Roval Gun Fafttory 
Paid Mr. Whitworth for two fimilar guns, afte 
deducting the value of material of one of them 
which burft 


Paid Mr. Whitworth for 12-pounder breech 
Joadintr eun... 


Paid Mr. Whitworth for 8o-pounder breech 
loading pun... 


Coft of experiments up to 31 December, 185 
(vide House of Commons Sefllonal Paper, 386 

i86oV.. 


Nature of Service or Experiment. 


ORDNANCE. 


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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 



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62 



OEDNANCE. 



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HOOPED GUNS. 63 

FIG. 50. 



FIG. 49. 




Armstrong hooped cast- 
iron naval gun. Scale, 
in. to 1 ft. 



68-pounder, hooped at 



"Woolwich, 
in. to 1 ft. 



Scale, 



experiments on hooping cast iron, as follows: They "have 
very little confidence in proposals to strengthen cast iron by 
external envelopes of steel or wrought iron. The process of 
gradual destruction commences with small fissures around the 
vent; and when these have proceeded to a certain extent, the 



64 



ORDNANCE. 



FIG. 50 A. 



entry of gas at an enormous pres- 
sure tends to rend the metal as if 
by a wedge. No external envelope 
will prevent the action. Its only 
advantage here seems to be to make 
its effect less destructive. The ex- 
ternal envelope adds to the strength 
of a cast-iron gun when there are 
no fissures and no rending action ; 
but this is not the ordinary cause 
of guns bursting. Guns condemned 
as unserviceable are almost inva- 
riably condemned for the state of 
the rnetal around the vent, and 
explosions must be generally at- 
tributed to that cause." 

OJJ. JJIr. Loiigrid^e's Experi- 
ments with Wire-wound Onus 
and Cylinders. Mr. Longridge, 
whose deductions on the subject of 
hooped guns will be further referred 
to (286 & 292), gave the following 
description of his experiments, in a 
paper on the " Construction of Ar- 
tillery," before the Institution of 
Civil Engineers, in 1860. The cyl- 
inders used were prepared according 
Wr r 2 

to the formula t = T , based 

upon Mr. Barlow's investigation. 
The method of conducting the ex- 
periments was as follows : " A num- 
ber of brass cylinders (Fig. 51) were 
prepared exactly of the same di- 
mensions, viz., internal diameter, 

Armstrong cast-iron 70-pounder of 1 860. 1 in - 5 external diameter, 1 T 3 F in. ; 
Scale -& in. to i ft. thickness of brass, % in. 





HOOPED GUNS. 65 

" These cylinders were accurately turned and bored, and had a 
flange J in. in depth and -J in. in thickness at each end. Each 
end was widened out, so as to afford seating to two gun-metal 
balls, which were accurately ground to fit them. 
The total content of each cylinder, with the 
balls in their places, was 300 grains of best 
sporting powder, which was alone used in this 
series of experiments. When the powder was put 
into the cylinder, and the balls were placed at 
each end, the whole was bound together by a very 
strong wrought-iron strap, similar to the strap 
of a connecting rod, with a jib and cotter. The cotter was driven 
tightly home, and the powder was then fired through a small 
touch-hole, left in the side of the seating. The first experiments 
were to ascertain the effect of the powder on the cylinders, with- 
out any wire. They were commenced with charges of powder, 
beginning at 50 grains, and increasing till the cylinder burst. 
After this, cylinders with different thicknesses of iron wire were 
tried in a similar manner. The results are given in Table XIV. : 
94. " The strength of the wire used in these experiments was 
ascertained, by trial, to be as resisting a dead tension 

eV wire . . 23 Ibs. = 120000 Ibs. per square inch. 
. TO Ibs. = 92000 Ibs. " 



95. " If now the expansive force of powder be taken to be 
inversely as the volume, its ultimate strength may be approxi- 
mately arrived at from the last experiment. The powder then 
could not burst the cylinder. Now the strength of the cylinder, 
supposing all the material to be equally strained, could not exceed 
the following per lineal inch of cylinder 

Wire ....... 17920 Ibs. 

Brass ....... 3136 Ibs. 

21056 Ibs., or 9-4 tons. 

And as the internal diameter was exactly 1 in., it shows that the 
ultimate force of the material in Experiment 23, did not exceed 



GO 



ORDNANCE. 



TABLE XIY. EXPERIMENTS ON LONGKRIDGE'S BKASS CYLINDERS. 



No. of 
Experi- 
ment. 


No. of 
Cylin- 
der. 


Condition. 


Charge 
of 
Powder 


Effect. 


l 




^Vithout wire 


Grains. 


Slightly bulged 




do 


Ditto 


;> 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 </) (infinite) s p = 15000 Ibs. per square inch. 
" b = 3r, s = p = HOOO " " " 

" b = 2r, s = 5 p = 18750 " " " 

" b = r, s = 5 p = 25000 " " " 

" b = lr, s = J^p = 390C!) " " " 

" b = lr, s = H 3 p = 113000 " " " 

7 15 

" b = -r, s = p = 128000 " " " 



96 ORDNANCE. 

137. In 1857, two 4*88-in. 12-pounder smooth-bore muzzle-load- 
ers were put to extreme test in Paris ;* it was impossible to burst 
them or to injure them by firing. In a former trial, an experi- 
mental 12-pounder of this manufacture had endured 1400 



While, therefore, a cast-iron gun, strained by an interior pressure of 1000 atmo- 
spheres, even with an infinitely great thickness of metal, warrants only a safety 

- = 1'26 times, but with a thickness of metal b = 3r would already be burst; 
15000 

and while such a gun of bronze metal, with an infinitely great thickness of metal, 

34000 

warrants a safety - = 2 '26 times, with b = 2r a 1-82 times, and with about 
15000 

b = __ r would be burst, a cast- steel gun warrants, with an infinitely great thickness 
8 

of metal, a safety 1????? =8 times, and even with b = 2r 6 -4 times, with b = r 4'3 
15000 

times, and even with b = r still a safety three-fold, and would not be burst with the 

small thickness of metal b r to b = r. 

7 8 

As the interior pressure which a gun has to stand during the firing may often reach 
or surpass 1000 atmospheres, it cannot of course surprise that cast-iron guns, even of 
cast iron of the most superior quality, the resistance of which is greater than 19000 
Ibs. per square inch, very often burst, and that also bronze metal guns are not so often 
burst; while this accident is not to be apprehended with good cast-steel guns, even 
of very small thickness of metal. 

For other apparatus which have to sustain as high pressures as guns (such as, for 
instance, the cylinders for hydraulic presses), Dr. Scheffler observes, in his pamphlet. 
that cast steel is invaluable, as its greater natural resistance cannot be equalled by any 
increase of the thickness of the less resistible metals. (See also Table XVIII.) 

* The following account of the experiment is extracted from the Report of the Sec- 
retary of the Committee of Artillery, dated Paris, July 12, 1857. A similar 12-pounder, 
made by Mr. Krupp, had been previously tested with the following results : It " was 
fired 1400 times with the service charge (about 2 k , or 4-4 Ibs.), 600 times with the 
charge of l k , 500 (3'3 Ibs.), and 1000 times with the charge of l k , 400 (3 Ibs.); in all, 
3000 discharges, which it resisted perfectly. A verification, made by the star-gauge, 
demonstrated that the piece had not suffered the least injury; no alteration was found 
either in the bore or in the external form. It has not been the same with the vent, 
which at first consisted of a simple hole pierced in the metal of the piece : after 500 
discharges the hole was considerably enlarged ; it was strongly crooked, and furrowed 
with longitudinal slits, which were enlarged more and more at each fire. The great- 
est diameter of its exterior orifice was 15 to 16 millimetres (, L 6 in.), instead of 5 mil. 6. 
(-/a in.), its original diameter. A new vent was substituted, pierced in a cylinder of 
cast steel, incased in a cylinder of copper, screwed to the piece ; but this vent did not 
endure better than the first ; it was unserviceable after 600 fires, and replaced by a 

(See page 98.) 



STEEL GUNS. 



97 



(Mr. Krupp's Circular continued.) 



TABLE XVIII. APPROXIMATE PROPORTIONS OF DIMENSIONS, WEIGHTS, AND PRICES 
OF KRUPP'S SOLID CAST-STEEL BLOCKS AND OF GUNS FINISHED AND RIFLED, 
TO BE LOADED FROM THE BREECH OR MUZZLE, ASSUMING THAT THE GENERAL 
CONTOUR OF THE GUNS is CYLINDRICAL, CONICAL, PLAIN, AND WITHOUT MOULD- 
INGS, OR RELIEFS. 

*** In giving orders for finished guns, the special proportions, particularly the number ani form 
of rifle grooves, must be expressly prescribed, as the proprietor of the works is not authorized to 
communicate independently to other governments the various forms and constructions of which he 
has obtained the knowledge through supplying his cast-steel guns. 









APPROXIMATE WEIGHT 


PRICES 


Diameter of 
the bore. 


Thickness of 
metal at the 
powder- 
chamber.* 


Kre? 


Of the block rough- 
ly turned and not 
bored. 


Of the finished gnn, 
turned, bored, and 
rifled without 
breecn-closing 
apparatus. 


Of a pure block, 
roughly turned, not 
bored. 

j s. d. 
33 15 


Of the finished 
gun, turned, bored, 
and rifled, without 
breech -closing 
apparatus 












s. d. 
60 


2-50 


1-75 


50 


450 


315 


2-50 


2-50 


50 


650 


490 


45 15 


76 10 


3 00 
8-00 


2-15 
3-00 


55-70 
55-70 


725-950 
1000-1300 


525-675 
765-975 


) 56 5 
[ to 
| 97 10 


86 5 
135 


3-25 


2-30 | 50-55 


750-825 


555-615 


)56 5 


86 5 


3-25 


2-70 


50-55 


900-1000 


6SO-755 


, 


to 


3-25 


3-25 


50-55 1050-1175 


SOO-S95 


86 5 


120 


3 50 
3 50 


2-50 
3 50 


65-70 
65-70 


1220-1295 
1625-1750 


825-875 
1200-1300 


) 91 10 
V to 
j 131 5 


129 15 
174 


8-75 
3 75 


2-70 
3 75 


80-85 
80-85 


1740-1860 
2350-2475 


1240-1340 
1710-1 825 


1 127 10 
I to 
| 165 


174 15 
217 10 


4-50 


2-70 


90-95 


2200-2300 


1425-1500 


I 150 


210 


4-50 


3-00 


90-95 


2480-2600 


1670-1750 


to 


to 


4-50 


4-50 


90-95 


3775-4000 


2725-2900 


J 277 10 


343 10 


5-00 


3-40 


100 


3400 


2200 


240 


311 5 


5-00 


5-00 


100 


5200 


3825 


367 10 


441 


5-75 


3-60 


100-105 


4180-4325 


2700-2800 


1292 10 


382 10 


5-75 


4-00 


100-105 


4700-4900 


8225-3350 


,0 


to 


5-75 


5-75 


100-105 


6900-7300 


5075-5400 


525 


622 10 


8-00 


6-00 


110 


11300 


8000 


810 


975 















* The corresponding smallest thickness of metal at the muzzle of the gun is presumed to be about 
half this largest thickness. 



Larger guns than 8" bore can be also manufactured from solid cast-steel blocks. 

7 



98 



ORDNANCE. 



with 4-4 Ibs. of powder, 600 with 3'3 Ibs., and 1000 with 3 Ibs., 
without alteration. It afterwards burst at the 4th round, with 2 
balls and 6'6 Ibs. of powder. The two guns referred to were fired 
3000 times each with 3 Ibs. of powder and one ball. One of them 
was then fired at and indented, and finally broken to pieces. The 
other was fired 20 rounds with 6 '6 Ibs. of powder and 2 balls, 10 
rounds with 6'6 Ibs. and 3 balls, and 6 rounds with 13'2 Ibs. and 6 
balls. Neither of the guns was altered in the slightest degree by 
all these rounds ; and it was determined not to burst the one that 
remained whole. 

TABLE XIX. PROOF OF KRUPP'S 110-PouxDER RIFLE. BORE 7 IN. WOOLWICH, 

FEB., 1863. 



No. of 
rounds. 


Weight of charge. 


Weight of shot. 


Remarks. 


I 


1 8 Ibs. 15 oz. 


HO Ibs. 


" Developing round." 


a 


27^ Ibs. 


no " 


" Proof rounds." 


4 


1 8 Ibs. 15 oz. 


no " 


" Developing charge." 


10 


14 Ibs. 


1 10 


" 


IO 


14 Ibs. 


200 " 




IO 


14 Ibs. 


300 " 




10 


14 Ibs. 


400 " 


loo rounds " Destructive proof." 


10 
10 
10 


14 Ibs. 
14 Ibs. 
14 Ibs. 


500 " 
600 " 

700 


The projectiles were cylinders with 
r leaded base to take the rifling. 

Leng'h of cylinder, last IO rounds, 
8 ft. 9.^ in. 


10 


14 Ibs. 


800 " 




10 


14 Ibs. 


900 " 




10 


14 Ibs. 


1000 " 






The gun was not injured in the above proof. 

vent pierced in a cylinder of ordinary copper, like that used for bronze cannon. This 
resisted perfectly until the end of the experiments, and was still fit for service when 
the gun was caused to burst. 

To study the extreme limits of resistance of the cast-steel gun, it was necessary 

(See page 100.) 



STEEL GUNS. 



99 



TABLE XX. PROOF OP KRUPP'S 20-PouNDER RIFLE. BORE 3-75 IN. WOOLWICH, 
SEPT. AND Nov., 1862. 



No. of 
rounds. 


"Weight of charge. 


Weight of shot. 


Eemarks. 


I 


3 Ibs. JO oz. 


20 Ibs. 


** Developing round." 


2 


5 Ibs. 


20 " 


" Proof rounds." 


4 


3 Ibs. IO oz. 


20 " 


'* Developing rounds." 


JO 


2^ Ibs. 


20 " 







10 


2 Ibs. 


40 " 






10 


2| Ibs. 


60 " 






JO 


2| Ibs. 


80 " 






10 


2| Ibs. 


100 " 




100 rounds ** Destructive proof." 


10 
10 


2^ Ibs. 
2| Ibs. 


120 " 
140 " 




The projectiles were wrought-iron 
cylinders with the base leaded to 
take the rifling. 


JO 


2| Ibs. 


1 60 " 






JO 


2 Ibs. 


1 80 






10 


2 Ibs. 


200 " 


. 




3 


5 Ibs. 


20 " 


- 




3 


5 Ibs. 


40 " 






3 


5 Ibs. 


60 " 






3 


5 Ibs. 


80 






3 
3 


5 Ibs. 
5 Ibs. 


IOO " 
120 " 




30 rounds with increasing cylinders 
- and double charges. 


3 


5 Ibs. 


140 






3 


5 Ibs. 


1 60 






3 


5 Ibs. 


180 " 






3 


5 Ibs. 


200 


- 





The gun was not injured in the above proof. The enlargement 
of the chamber was "12 inches. 



100 



ORDNANCE. 



TABLE XXI. PROOF OF KEUPP'S 40-Pouxr>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 



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3 

5 

Q 
5 



I 



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M 



p 
g 

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Remarks. 


i 1! 

I :| 

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a J5 5 

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^ u E-* 


I| 

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00 . CO cl O ^" CO 
^ * CO Cl n 





II 

^ 


O O vo o O r^. oo O 
JO^r>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 

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3 

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1 




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120 



ORDNANCE. 





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51 


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2 


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--- 



CAST-IRON GUNS. 121 

The gun closely resembles the 15-in. gun in figure; the partic- 
ulars are as follows : 

Length of gun 20 ft. 3^ in. 

" bore 17 " 6 " 

" trunnions 6 " 

Diameter, maximum 5 " 4 " 

" muzzle 2 " 10 " 

" bore i " 8 

" trunnions I " 6 " 

Distance over rimbases 5 " 4-2 " 

Weight 115200 Ibs. 

Chamber ellipsoidal, length 15 in. 

The particulars of the 20-inch navy gun are as follows : 

Length of gun - 17 ft- 

" bore 13 " 7 in 

" trunnions 6 " 

Diameter, maximum 5 " 4 

" muzzle 2 " 10 " 

bore i " 8 " 

" trunnions i " 4 " 

Distance over rimbases 5 " 4 " 

Weight (about) 100000 Ibs. 

167. British Cat-Iron Guns.* (See Table 25.) The stan- 
dard cast-iron gun in England in fact, the standard Naval Gun 
is the 95 cwt. 68-pounder of 8 in. diameter and 113-9 in. length 
of bore, and 26 '2 in. diameter over the chamber (Fig. 87). Its 
cost is about $500. 

168. At the siege of Sebastopol, the 68-pounders were, on the 
whole, very satisfactory in their results and endurance. Only two 
of them burst, both at high elevations, and one after having fired 
over 2000 rounds. (See Table 24.) Some of those landed from the 
"Terrible" fired as many as 4000 rounds, usually with 16 Ibs. of 
powder, and very rapidly. Some of them were rebouched twice.f 

The other ordnance used in this siege, 911 pieces in all, con- 
sisted of 24-pounders and 32-pounders, which had little effect on 
masonry 8-in. and 10-in. shell-guns, and 13-in., 10-in., and 8-in. 
mortars. 

* It is stated that 100 new 68-pounders have been recently ordered, on account of 
the failure of the Armstrong gun as a naval weapon. 

f Military Commission to Europe, Major Mordecai, 1860. 



122 



ORDNANCE. 






1 



FIG. 88. 



British 8-in. shell gun. 
Scale, -ft in. to 1 ft. 



CAST-IRON GUNS. 



123 




27 



.2.4 
22" 



"IS" 







...IQl/L. 



124 



ORDNANCE. 



TABLE XXIV. GUNS BURST AT SEBASTOPOL AND SWEABORG. 
These guns were all of cast iron, unstrengthened. 



No. 
burst 


Description and calibre. 


No. of rounds fired. 


Cause of bursting. 


I 


13-inch Mortar, old pattern 


No information. 


No information. 


2 


lo-inch Mortar, old pattern 


No information. 


No information. 


2 
I 


68-pounder, 95 cwt. 
jo-inch Gun, 85 cwt. 


1st, Fired over 2.000 
rounds. 

2d, No information. 
No information. 


I Fired at high elevation. 

Y Enemy's shell burst in 
\ muzzle. 
No information. 


I 


32-pounder, 56 cwt. 


No information.* 


No information. 


2 


24-pounder, 50 cwt. 


No information. 1 }- 


No information. 


3 


Lancaster 8-inch Guns. 


No information. 


No information. 



FIG. 91. 



* The 32-pounders avernped 1500 rounds each. 
t The 24-pounders averaged 950 rounds each. 

1OO. JTIiscellaiieous Cast-Iron Guns* and ITlortar. The 

[Russian 120-pounder shell-gun is illustrated by Fig. 89. Its 
length (to end of reinforce) is 130 in. ; diameter over the chamber, 
26-8 in. ; diameter of bore, 10'75 in. The 56-pounder, illustrated 

by Fig. 90, is intended as both 
a shot and shell gun. The par- 
ticulars of it are : length (to 
end of reinforce) 124 in. ; diam- 
eter over the chamber, 28'7m.; 
diameter of bore, 7 '65 in. ; 
weight, 13700 Ibs. The other 
modern Russian cast-iron guns 
are chiefly of the calibres of 
40-pounders and 9G-pounders.f 
1 7O. Fig. 91 illustrates the 
difference in figure between 

^ British and tl United 

States 13-in. sea-service mor- 




British and U. S. 13-inch sea-service mor- 
tars. Half section of each. Scale, -?$ in. 
to 1 ft. 



* The Wahrendorf and Cavalli breech-loading cast-iron guns will be illustrated 
under the head of Breech-Loading. 

f Military Commission to Europe, Major Mordecai, 1860. 



CAST-IRON GUNS. 



125 



tars.* The particulars and charges of British mortars are given 
in Table 26. The United States 13-in. mortar weighs 17120 Ibs. ; 
length of bore, 2' 7 diameters. It has no preponderance. The 
charge is 20 Ibs. ; projectile, 220 Ibs. The 10-in. and 8-in. mor- 
tars have bores 1 J diameters long, measured from the bottom of 
the projectile, and their weight is about 20 times that of the 
shell. 

* The faulty form of the British mortar is thus referred to by Commander Scott, ia 
a lecture before the Royal United Service Institution : " The effect produced by this 
faulty form was seen in the bombardment of Sweaborg, when nearly the whole of the 
mortars employed either burst, or were rendered unserviceable ; the best, that of the 
Growkr, cast in 1813, standing 355 rounds only. 

"By a reference to Fig. 92, it will be seen that the trunnions prevent the expansion 
of the iron at the places where they unite with the piece ; hence, as the iron warms, 
it expands at the bottom, and the mortar being supported upon its trunnions, a severe 
shock is thrown upon that part which is in the line of least metal, and has been fur- 
ther weakened by expan- p IG> 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| ^ 

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58 * s -1 I * 

c c - B- 

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^ ^ ^ 

rj - C C C r. 


ri 

6 

55 

cT 

3 

o 




cT 
O 




c 



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c 

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vo 


f ! ? f f 1 

O o oo oo oo oo 


c 

oo 


c 
oo 


c 

00 


O 
CL, 

VO 
VO 



CAST-IRON GUNS. 



127 



tf 


H 


^ 


CO 

to 

rt 


s <& <o\ ^ 


00 

Ox 


CO 


to 


CO 


to 


to 
M 


S 














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, *- 
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CO 


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to to to 

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M 
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to 
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vo 


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ic jc ic 


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to 
r) 


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VO 


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to 
r-. 


? 


vo t> VO vO 


oo 

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vo 


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1-4 


Ox 






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Ox 


Ox 


vo 


K 


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00 


^ 


to 


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VO 

oo 


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co 





5. 




VO 


T*- 


to 


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Ox O Ox ON 


o 


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0, 


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ongreve's 


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to to to to to 


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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 


^' 


















<N 




H 


5- 


ON ^> * 
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 


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1 


















3 


Preponderance. 


r vo 


vo 


vo JT so vo 


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w vo ON vo 


d 

so 


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5 


1 




to 


T*- 


to to to 


tO d M tO 


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d 


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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 

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c c (T c 

3333 

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CAST-IRON GUNS. 



129 



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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 


* 






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v 52- 


'Cj^ 




1 


O 9 


O 


c 

<t 9 


a. 

O 





FIG. 95. 



Side of 10-in. target for 15-in. gun. Front of 10-in. target. 

Scale, -fV in. to 1 foot. 

with 40 Ibs. of ordinary cannon-powder, at a target (Figs. 93, 94, 

and 95) composed of a 4^-in. plate, 3J ft. wide and 15 ft. high, 

backed with 5J in. of l*l-in. 

plates (10 in. of iron in all) and 

20 in. of oak. A disk was broken 

out of the 4^-in. plate (a, Fig. 

94), 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 

u v i>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<V feet of yellow pine, as shown.* 

* In the late action off Mobile, a 15-in. ball shattered and splintered the armor of 
the Tennessee 5 in. of iron bars and 2 ft. of oak. No other shot injured it. 



142 



ORDNANCE. 

FIG. 97 A. 




Cross section of the Confederate iron-clad Atlanta. 



181 C.* 13-lNCH 610-LB. STEEL SHELL; 4^-lNCH PLATE; 18- 
INCH BACKING. On December 11, 1863, a 610-lb. steel shell was 
fired from the Armstrong 13-inch gun, with TO Ibs. of powder, at 
the Warrior target (Fig. 98) ; range, 1000 yards. This projectile 
smashed a 20 by 2-1-inch hole entirely through the target, splinter- 
ing the backing and supports, starting all the plates, breaking 
nearly all the bolts, and slewing round the entire structure. The 
shell contained a 24-lb. bursting charge, and exploded at the in- 
stant 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. 

181 D." 13-lNCH 344J-LB. STEEL SHOT, H-!NCH PLATE. On 
the 10th of March, 1864, a 344J-lb. spherical steel ball was fired 
from the same gun with 90 Ibs. of powder initial velocity, 1T60 
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 

* The accounts of these two experiments were not obtained from official sources. 



REQUIREMENTS OF GUNS ARMOR. 



143 



shot was flattened to 15*2 in. maximum and 10 in. minimum 
diameter, and thrown back towards the gun. 

182. 13-lNCH BALL; 4f-lNCH PLATE. At Liverpool, in 1856, 
the Horsfall 13-in. spherical shot of 279'5 Ibs. weight was fired 
with 25 Ibs. of powder, at a plate 4f in. thick, 3 feet 9 in. long, and 
2 feet 9 in. wide, weighing about 2000 Ibs., and supported by 9 
balks of timber, each 6 feet long and 14 in. square, laid together 
with planks, and abutting in a large bank of sand. The range 
was 120 yards. About a third of the plate was broken to pieces, 
and fragments of about 1 cwfo each were thrown in all directions. 
The timbers were driven into the sand, and one of them "sent to 
a distance of 300 yards straight on end in the shore."* 

183. 13-lNCH BALL, AND 131-LB. WHITWOETH RIFLE-SHOT; 
WARRIOR TARGET. A spherical shot was fired (September 25, 
1862) from the same (13-in.) gun at the Warrior target, Fig. 98 
a 4r|-in. plate, 1 8-in. teak backing, and a f -in. skin with T4--4 Ibs. 
of powder, and 1631 ft. initial velocity, but at 

800 yards range. A Whitworth 131-lb. rifle- 
shell was on the same occasion fired with 25 
Ibs. of powder, at the same target, at 600 yards 
range. Although the total power stored up in 
the 13 in. shot at starting was much greater 
than in the rifle-shot, it lost more velocity in a 
given range (since it had a greater cross- 
sectional area in proportion to its weight), and 
had 200 yds. farther to go. In addition to 
this, it struck the ground in front of the target, 
and ricocheted. So that the two shots afford 
an approximate basis for comparing the two 
systems. The 13-in. shot did not penetrate, 
but smashed the iron and the teak, ripped open the inner 
skin, and broke 7 through-bolts and 2 ribs ; its effect was more 
distributed. The rifle-shell made a clean hole, producing only a 
local effect upon the target. But it burst inside the target. 



FIG. 98. 




The Warrior target. 
Scale, i in. to 1 ft. 



* Mr. Clay. " Report of the Defence Commissioners," 1862. 



144 ORDNANCE. 

Another 13-inch ball, on the same occasion, broke off a corner 
of the plate 2 x 1^ ft., starting 2 bolts, shaking the whole target 
violently, and doubling up a rib. The damage extended 5 ft. 
down the target. 

1 84. 10J-INCH BALL ; WARRIOR TARGET. An Armstrong 10J- 
in. 150-lb. spherical shot was fired in April, 1862, at the Warrior 
target, with 40 Ibs. of powder and 1586 ft. striking velocity ; range, 
200 yards. The first shot bulged the plate considerably, made 
cracks in it 18 to 36 in. long, crushed the iron over a surface of 
3 or 4 square feet, smashed the teak, broke 2 ribs, tore the skin, 
broke two bolts, and lodged in the backing. The second shot hit 
near the first, and did similar but greater local damage, smashing 
another rib and covering the ground with splinters. The follow- 
ing shot was fired with 50 Ibs. of powder and made a clean breach, 
with less distributed effect. The fourth shot, fired with 40 Ibs. of 
powder, struck where the target was supported by 2 sq. ft. of solid 
timber, which it could not penetrate, but only crack ; it therefore 
shook the whole target, and the solid masonry behind the abutting 
beams. 

185. 150, 230, AND 307-LB. KIFLE AND 113-LB. ROUND-SHOT; 
12 AND 13-INCH TARGET. On the 3d of March, 1863, some heavy 
shots were fired, at 200 yards range, against Captain Inglis's pro- 
posed armor for forts, a target peculiarly adapted to suffer from 
vibration. A part of the target consisted of a front row of verti- 
cal slabs of wrought iron, 8 ft. high, 20 in. wide, and 8 in. thick, 
backed by horizontal slabs 11 ft. long, 20 in. wide, and 5 in. thick. 
The vertical slabs in another part were 7 in. thick, and backed by 
the same horizontal 5-in. slabs. Behind the slabs were ribs 9 in. 
wide and 5 in. deep. The whole was fastened together by 3-in. 
bolts, with conical heads and nuts. Washers of lead, rubber, iron, 
and plaited wire were respectively placed under some of the nuts. 

The 1st shot from the Whitworth 7-in. rifle was a solid fiat- 
headed 148-lb. steel shot ; charge, 25 Ibs. ; striking velocity, 1240 
ft. ; it struck the 13-in. part of the target, slightly bulging and 
smashing it, cracking two 8-in. plates and bending a frame-piece, 
but not breaking any bolts, nor seriously straining the fastenings. 



REQUIREMENTS OF GUNS ARMOR. 145 

2d. A 113-lb. spherical wrouglit-iron shot from the Armstrong 
9 "22-01. gun was fired, with 25 Ibs. of powder and 1462 feet stri- 
king velocity, at the 13-in. part of the target. It indented 2^ in., 
cracked both the 8-in. and the 5-in. plates, bent the 9x5 frame- 
bar 2 in., broke off one bolt-head (a new bolt was afterward put 
in), and strained the target perceptibly. 

The 3d shot, a 230-lb. conical cast-iron bolt, 19 in. long, was 
fired, with 45 Ibs. of powder and 1400 feet striking velocity, from 
the new 10^-in. muzzle-loading, shunt-rifled Armstrong gun. It 
struck the 12-inch part, cracked both the 7 and the 5-in. plates, 
curved, dislocated, and drove in the slabs and frame-bars, broke 
several bolts, but did not throw off any of the slabs. The indent 
was only 1^ in. 

The 4th shot of wrought iron, weighing 150 Ibs., was fired from 
Lynall Thomas's 7-inch rifle (127), with 25 Ibs. of powder and 1218 
feet striking velocity. The shot was greatly upset, and the target 
was indented 1*8 in., and sprung and cracked, but not very seri- 
ously shaken. 

The 5th was a Whitworth 150-lb. shot, similar to the first. It 
struck a 24 x 21 x 8-in. plate under the embrasure, bent out the 
9x5 in. frame-bar previously started, broke 2 bolts and threw 
out one. The lead washers of other bolts were flattened. The 
plank struck was driven in an inch, and both planks were cracked ; 
effect mostly local. 

The 6th was an Armstrong 307-lb. shot, tired from the 10^-in. 
gun w r ith 45 Ibs. of powder; striking velocity, 1228 ft. It struck 
on a point a few inches above shot ISTo. 1, cracked the 8-in. plate, 
broke one bolt, and bulged and shook the slabs and frame-pieces 
considerably. 

Mr. Lynall Thomas's 7-in. gun was then laid, but burst with. 
27-J Ibs. of powder and a 133-lb. shot. 

186. 300 AND 330-LB. EIFLE-SHOT; 7^-lNcn TARGET. Oh the 
17th of March, 1863, another target of solid plates, rolled by 
Messrs. John Brown & Co., was tested with heavy projectiles at 
200 yds. range. It consisted of a lower horizontal plate 6|- in. 
thick, a middle plate 7-J in. thick, and an upper plate 5J in. 
10 



146 ORDNANCE. 

thick, each about 4 ft. high and 12 ft. long, their faces being 
flush. One side of the target was backed only by vertical iron 
ribs ; the other by 10 in. of teak, a 1-in. plate, a l-J-in. plate and 
vertical ribs. A heavy horizontal girder extended across the back 
of the vertical ribs. The target was held upright by heavy tim- 
bers extending between it and a bank of earth behind. The 
through-bolts were 2^ in. diameter. 

After 3 rounds with 6 8-pounder spherical shot and 3 with 05^-lb. 
steel shot from the Armstrong 7-in. rifle (110-pounder) charge, in 
each case, 16 Ibs. ; indentation, 2 J- to 3 in. ; no perceptible racking 
observed a conical 301-lb. steel shot, iired by 45 Ibs. of powder 
from the lOJ-in. Armstrong gun, struck the centre of the 7|-in. 
backed plate over a rib, with a velocity of 1293 feet; made an 
indentation 13 in. wide by 6'2 in. deep ; bent the plate, throwing 
the ends out nearly an inch, and loosening and breaking one bolt 
and 20 rivets ; cracked and bent the inner skin and ribs ; broke 
and jarred the horizontal girder, and shook the structure violently. 

The 8th and 9th rounds were fired through the 5^-in. plate, and 
burst in the backing. These will be referred to under another 
head. 

The 10th shot w r as from Lynall Thomas's 9-in. rifle, and missed 
the target. 

The llth, a 302-lb. wrought-iron bolt, 18|- in. long, was fired 
from the same gun, with 50 Ibs. of powder, and struck the junc- 
tion of the 7-J and 6-J-in. plates where they were not backed, ma- 
king several cracks and an indentation of 5^ and 6 in. in a length 
of T-J- ft., and bending and vibrating the plates so much as to break 
several rivets and angle-irons and a vertical rib. The shot re- 
bounded 25 yards and w r as much upset. 

The 12th shot, a steel 330-lb. bolt, was fired from the same gun 
with 50 Ibs. of powder, and struck the edge of the 7-J-in. plate, 
where there was no wood backing, at 1220 feet velocity. It 
smashed a piece 21 x 12 in. out of the plate, making an indent 7 
in. deep. One rib was broken and 2 were bent. The girder pre- 
viously started w^as thrown out of place, and 2 bolts were broken. 

The 13th shot was a spherical 163-lb. ball fired at the unbacked 



REQUIREMENTS OF GUNS ARMOR. 



147 



FIG. 99. 



FIG. 100. 



plate from the 10^-in. Armstrong gun, with 45. lbs of 
powder, at a striking velocity of 1627 feet. The effect was of 

course chiefly local. 
The plate was deeply 
indented and torn, 
horizontally and ver- 
tically. The cracks at 
the rear were 2 in. 
wide. 

187. lOj- - INCH 
BALL ; SCOTT RUS- 
SELL'S TARGET. (Figs. 
99 and 100.) On the 
26th of June, 1862, 
a 10^-in. wrought-iron 
ball was iired with 50 
lbs. of powder range 
200 yards at Mr. 
Scott Russell's target. 
This was composed of s * ca * e ' * in - to l ^ 
4 rows of plates 4f in. thick, and 
about 2 feet wide, making a wall 29 
ft. 10 in. x 9 ft. 9 in., with 2 ports or 
embrasures. The backing was com- 
posed of three 1-in. plates and two f- 
in. plates, which represented the skin 
of the ship, making 8 in. of iron in 
all. The construction of the target 
at the rear consisted of 2 longitudinal 
stringers 5-J in. deep, one above and 
the other below the port ; also 2 iron 
water-ways representing the upper 
and main decks. The vertical ribs 
were 10^ in. deep and 21^ in. apart. A lining of half-inch iron 
was placed on the upper part of the target ; the remainder was 
left open to allow the skin to be examined. Between the armor- 





Scott Russell's target. Front. 
Scale, in. to 1 ft. 



148 ORDNANCE. 

plates were T-irons riveted to the iron backing, and upset over the 
edges of the plates to hold them in place, instead of bolts. There 
were 4 rivets through one plate, but no bolt nor other rivets. 

The shot (162-lb. spherical) struck with about 1600 ft. velocity, 
breaking a hole through one armor-plate and cracking another. 
Two feet of the continuous riveting was sheared off. At the back, 
a vertical rib and the skin w r ere broken through, and the whole 
mass was moved back J- inch. The shot, much flattened, was 
thrown 5 yards forward towards the gun. 

188. 10 J-INCH BALL ; MINOTAUR TARGET. On the 7th of July, 
1863, the lOJ-in. Armstrong smooth-bore was tired at the Mino- 
taur target, composed of 3 plates, each 12 ft. 6 in. x 3 ft. 4 in. x 
5^ in. thick, backed by 9 in. of teak and |^-in. skin, supported on 
ships' frames. Range, 200 yards. 

The 1st shot, a 150-lb. cast-iron ball charge, 50 Ibs. knocked 
a 12-in. disk out of the middle plate and 13 in. into the backing. 
The whole plate was driven in about 1 in. ; 9 bolts and 1 1 rivets 
were started in the plate struck, and in the other plates ; 2 ribs 
were broken ; the horizontal girder was carried away ; and the 
target was generally strained and bent. 

The 2d and 3d shots same weight and charge smashed clean 
holes through the target, starting more bolts and somewhat strain- 
ing the target ; but the effect was mostly local. 

The 4th shot, a 162-lb. wrought-iron ball charge, 50 Ibs. 
struck near the 1st, broke through the outer plate, and remained 
in the indent. The plate was much buckled and the backing 
smashed to 6 in. thick. The whole target was tremendously 
shaken ; 2 ribs and the horizontal girder were bent ; the skin was 
bulged but not torn ; 4 bolts were broken. The local effect was 
much less than No. 1, but the shock was distributed over a block 
of masonry in the rear, on which it leaned through intervening 
struts. 

1 8O. 301-LB. HlFLE-SHOT AND 150-LB. BALLS; CHALMERS 

TARGET. On April 27th, 1863, the following heavy shot were fired 
at 200 yards range, at the Chalmers target (Fig. 101). This target 
was composed of 3f-in. armor-plates backed by alternate layers 



REQUIREMENTS OF GUNS ARMOR. 



149 



FIG. 101. 



of timber and iron lOf in. thick, placed horizontally and bolted 

together; then a 2d armor-plate 1J in. thick, with a cushion of 

timber 3|-in. between it and the f-in. skin. The iron plates 

between the 1st and 

2d armor-plates stood 

edgewise, and were f 

in. thick and 5 in. apart. 

The bolts were 2J in. 

diameter, with elastic 

washers. 

After 26 rounds from 
the 68-pounder smooth- 
bore and 110-pounder 

rifle, a 301-lb. solid steel 

shot was fired with 45 

Ibs. powder from the 

Armstrong 10^-in. rifle. 

It struck at the junc- 
tion of two plates and 

made a clean breach 

through the target, 

bulging it considerably, 

smashing one rib, and 

breaking bolts and riv- 
ets. 

The next shot was a 

150-lb. cast-iron sphere 

from the same gun 

charge, 50 Ibs. It 

smashed an indent to a 

depth of 11 in. ; broke 

2 bolts and 5 rivets, 

bulged out 2 ribs and 

the skin, and affected 

the backing over a 

space of 3 x 2 feet. 




The Chalmers target. 



150 



ORDNANCE. 



FIG. 101 A. 



The last shot, the same as the above, smashed to the depth of 
12 in., and broke up ; 2 bolts, 3 rivets, and 1 rib were broken ; the 
corner of the plate struck was detached and forced into the back- 
ing. The skin was slightly cracked. 

This is considered the strongest plan of armor, for a given 
weight, that has been tried in England. 

1 89 A. 150-LB. BALL AND 300-LB. BOLT ; BELLEKOPHON TAR- 
GET. On the 8th of December, 1863, various projectiles were 
fired at a target (Fig. 101 A), consisting of 6 inches of solid iron, 
10 inches of oak, and 1^-in. skin held by heavy ribs ;* range, 200 
yards. A lO^-in. 150-lb. steel ball charge, 35 Ibs. struck the tar- 
get on the joint of two plates, which it punched, imbedding itself 
in the backing, breaking a rib and two bolts, slightly cracking 
the skin, and bulging it 2 in. The effect was wholly local. A cast- 
iron ball from the same 
gun, with the same charge, 
broke through the plate, 
and slightly bulged the 
skin. 

A 300-11). bolt from the 
same gun, with the same 
charge, struck near the 
centre of a plate, and in- 
dented it only 2 -8 in. The 
plate was driven in 2'1 in. 
in a length of 5 feet at 
the bottom, started out *4 
in. in a length of 2 ft. at 
the top, and cracked for 
a length of 18 in. ; but 
no through - bolts were 
broken, and the target, 
considered as the side of a 
ship,was almost uninjured. 




The Bellerophon target. Scale, \ in. to 1 ft. 



* See chapter on Experiments against Armor. 



REQUIREMENTS OF GUNS ARMOR. 151 

1OO. A few of the English experiments with smaller guns, 
throw some light on this question; for instance, those of May 16, 
1861, with the 110-pounder Armstrong rifle against 2-in., 2^-in., 
and 3^-in. x 5^ x 2ift. plates laid upon masonry. The first 6 shots 
struck bolts or former fractures or the corners or junctions of plates, 
and produced wholly local effects. The 7th shot hit the centre of 
the lower 3^-in. plate, started 1 bolt 1 in. ; plate very slightly bent ; 
depth of indent very small indeed ; plate not damaged at all ; a 
</reat deal of masonry shaken down from the top. Nearly all the 
following shots up to the 27th hit upon previously damaged parts. 
The 27th hit the 3d plate, upper, near the centre ; broke away 
the lower half, leaving the piece supported by 1 bolt ; broke away 
and shattered the masonry around, and started the plates and 
brought down some more masonry. 

191. Detaching Armor by Heavy Shot Considered. The 
penetration of plates up to 6 inches thickness by 13-in. and 15-in. 
balls, does not establish the advantages of this particular sys- 
tem of destroying iron-clads. It is, on the contrary, the highest 
result of the punching system. To shatter or to strip the target, 
the powder must propel more weight at a lower velocity, or the 
target must offer so much local resistance that the effect of the 
blow will be distributed over the structure and fastenings. Only 
a few of the foregoing experiments illustrate the system under 
consideration. For instance, the effect of the 15-in. shot upon 
the 10-inch target, clearly indicates the weak point of solid plates 
merely bolted to the ship the Warrior system. The shot cracked 
and broke through the 4J-in. outer plate, backed as it was with 6 
in. of iron, besides 20 in. of oak ; and experiments have clearly 
demonstrated that iron backing saves the plate struck. After break- 
ing through the 4^-in. plate, it still had the 6 in. of iron and 20 in. 
of oak before it, instead of the Warrior's 18 in. of teak and f-in. iron 
skin. On the other hand, the American 4^-in. plate was undoubt-j/ 
edly inferior to the British .4^-in. plate not as iron, but as armor.*/ 



* This subject will be further discussed. Like the early British plates, the Ameri- 
can thick plates are nearly all too hard. 



152 ORDNANCE. 

The former cracked without bending much ; the Warrior plates 
are greatly indented, bent, and upset by shot, before serious frac- 
ture occurs (212). Again, the iron backing of the 10-in. target 
diminished the local effect of the blow. But the less power a shot 
devotes to local effect, the more it reserves for racking the whole 
structure. The 110-pouiider did not shake down the masonry until 
it struck a plate that it could neither penetrate nor greatly indent. 
Hence the 10-in. target was peculiarly adapted to suffer racking, 
while the ductility and the elasticity of the Warrior's side are 
better calculated to resist it. 

192. After all, it is not so much a question of plates as of 
bolts. If the 15-in. shot goes through the Warrior, no matter 
about the fastenings ; if not, the greater the bending of the plates, 
and the elasticity of the structure, the greater the strain upon the 
bolts. And if one plate is thrown off, the ship is at the mercy of 15- 
in. shells. It is thus clear that with the Warrior system of armor, 
up to 6 inches thickness, there is a very unsatisfactory margin of 
safety between penetration on the one hand and displacing the 
armor on the other. While the superior resistance of solid, as 
compared with laminated armor, to punching, has been demon- 
strated at great cost (197), the difficulty of properly fastening it, 
although encountered to some extent, with light shot, has only 
been appreciated after whole British and French iron-clad fleets, 
and several American vessels on the same plan, have been com- 
pleted. It may hardly turn out to be a fatal defect ; it will cer- 
tainly prove to be a serious embarrassment. 

193. As compared with the 10-in. target (179) struck by the 
15-in. shot, the Inglis 12 and 13-in. target (185) was better calculated 
to resist local effect and to suffer distributed racking and vibration. 
Although it was perforated with many large bolt-holes, and the 
slabs were so thick and narrow as to be easily cracked, it was ex- 
cessively rigid. The outer slabs, already thick, had a backing of 
5-in. slabs and 7 x 9-in. beams, which should reduce the punching 
effect of a shot as compared with the 6 flexible 1-in. plates and the 
20 in. of oak behind the outer plate of the 10-in. target. And, 
while the latter backing was both elastic and ductile, so as to yield 



REQUIREMENTS OF GUNS ARMOR. 153 

locally, the solid iron backing of the Inglis target could not yield 
locally, but had to shiver all over when it was hit. Still, the local 
effect the evidence of power locally expended was greater upon 
the Inglis target than upon the 10-in. target, and the distributed 
effect was less, which only shows that the simple 15-in. cast-iron 
ball, at the moderate velocity of 900 feet, is better for racking pur- 
poses than the costly rifle-bolts, which require enormous charges 
and excessively strong guns. Even the heavy and the light rifle- 
bolts produced this effect in a greater or less degree, respectively, 
although the velocity of all of them was too high to exert much 
distributed effort. On the other hand, the bolts of the yielding 
10-in. target and of the comparatively elastic T-J-in. target (186) 
were more likely to be thrown out than those of the rigid Inglis 
armor. 

The 7-J-iii. target was perhaps more likely to be thrown apart 
by vibration than the 10-in. target, because it was best of all the 
three to resist punching, the plates being both thick and large. 
It did suffer rather more from vibration than the Inglis target, but 
less than the 10-in. target, considering that the latter received but 
one shot ; which further proves the superiority of heavy balls for 
this particular w^ork. 

On the whole, the 15-in. ball appears to have been capable of 
doing the greatest damage by vibration to either of the three tar- 
gets (see Table 28), although the bolts were perhaps thrown out 
of the 10-in. target that it did strike, more easily than they would 
have been, by a similar blow, out of the Inglis and the 7-^-in. tar- 
gets, which had elastic washers. This latter defect, however, may 
be remedied (204), so that, 1st, the general straining and weaken- 
ing of a ship's side, and the leakage and the more gradual reduc- 
tion of resistance to shot due to it, are likely to be the principal 
effects of vibration. 2d, the 15-in. ball at 900 ft. velocity is more 
formidable in this regard than the 200 to 300-lb. rifle-bolt at 1100 
to 1300 ft. velocity. And hence it is fair to presume that the 20- 
inch ball, at a still lower velocity, will be the most formidable 
weapon at present known for this kind of attack. 

193 A. A fine illustration of the effects and advantages of 



154 ORDNANCE. 

light shot at high velocities, as compared with heavy shot at low 
velocities, was given in the experiments against the Bdleropkon 
target. A 150-lb. steel ball punched the 6-inch solid iron at the 
junction of two plates, embedding itself in the backing, 'breaking 
a rib and two bolts, and cracking open and bulging the skin. A 
cast-iron ball gun and charge the same also went through into 
the backing and bulged the skin. But a 300-lb. bolt, from the 
same gnn with the sam.e charge, indented the plate 2*8 in. ; started 
the corners of it out less than half an inch and made a crack ; but 
broke no through-bolts. The target, considered as a ship, was 
uninjured. 

The 150-lb. ball struck at the junction of two plates, which un- 
doubtedly increased its penetration ; but it must also be consid- 
ered, 1st, that the 300-lb. bolt wasted less power locally in striking 
the centre of a plate than if it had also struck a joint ; and 2d, that 
it strained the gun very much more than the 150-lb. ball strained 
it. With a 50 or 60-lb. charge, and the same strain upon the gun, 
the 150-lb. ball would obviously have broken through the target. 

ISM. SOLID AND LAMINATED AKMOE. Whatever may be the 
relations of the present guns and the present armor, both are to be 
vastly improved. The fabrication of great guns that will stand 
proportionate charges is beset with formidable difficulties, while 
the particular weakness of ships that great guns discover may be 
remedied by simply improving the fastenings of armor. Lamina- 
ted armor layers of thin plates breaking joints takes hold of a 
large area of the ship's side, and has great continuity and tenacity 
compared with single rigid detached slabs, held each by its own 
fastenings without aid from the rest. In addition to this, lamina- 
ted armor forms a practically continuous girder to resist the other 
strains brought upon the vessel, while detached solid plates are 
loosened by the working of the hull in a sea-way. 

19o. Americans, having great guns and knowing their effects, 
at once selected laminated armor for the purpose of resisting thexe 
effects ; Europeans, having the guns necessary for high velocities, 
adopted solid armor to resist punching. But laminated armor 
can be most easily punched : then the American theory is it 



REQUIREMENTS OF GUNS ARMOR. 



155 



FIG. 102. 



must be made thicker, for a given weight, by being reduced in 
area {n short, the Monitor principle of low 
decks and turrets or short casemates must be 
substituted for the Warrior, or more especially 
the Minotaur system, of thin armor over all. 

196. The inferior resistance of laminated 
armor as compared with solid armor, to can- 
non-shot, has been demonstrated by a number 
of experiments, which will be more fully de- 
scribed in a following chapter. 

197. In 1861, a target proposed by Mr. 
Hawkshaw, composed of a front 1-J-in. plate 
and seven f-in. plates (total thickness, 6 in.), 
fastened together by alternate rivets and 
screw-bolts 8J- in. apart all over the target, 
and without wood backing, was completely 
punched by both the 110-pounder charge, 14 
Ibs., and the 68-pounder charge, 16 Ibs. at 
200 yards. 

198. Another target constructed on the 
same principle, of a 1^-in. plate and thirteen 

The Hawkshaw 10-m. 

f-in. plates (Fig. 102), the measured thickness target. 

being 10 in., and similarly screwed together, without wood 
backing, was broken through at the back and much indented 
by the 110-pounder and the 68-pounder charges and range as 
before. The material in both these targets was the best boiler- 
plate, and, being thin, was of course sound and well worked. 

199. There have been no experiments in England with the 
letter class of 4^-in. solid plates without wood backing ; so that 
the merits of solid and laminated armor cannot be absolutely 
determined from these experiments. But it is absurd to suppose 
that 18 in. of teak backing* is equivalent in any particular to the 

* Backing. In a paper read before the British Association in 186.>, 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 <?, or at least so much larger than the united fractured 
areas of the thin plates forming the laminated armor (Fig. 105) as 
to account for the superior resistance of solid plates. Fig. 104 
represents a 10-in. shot-hole made at the Washington Navy Yard 
through a laminated target. As there was no continuity of sub- 
stance, the plates received no aid from each other. 

2O3. It should be remarked, however, in favor of the solid 
armor, that so long as the shot is not powerful enough to make a 
clean breach through backing and all, the large disk broken out 
of the solid plate remains fixed in the backing, and is still a good 
protection against common shells and light missiles, while the disks 
broken out of laminated plates, are not large enough to remain 



* It is possible to imagine velocities so great that the metal around the shot would 
not have time to be carried away. See also 261 



158 



ORDNANCE. 



FIG. IOG. 





upright and solid in the backing, nor massive enough to stop the 

smallest cannon missiles. 
FIG. 105. 

2O4. The thin armor- 
plates employed to give con- 
tinuity to the side of a ship, 
need not constitute the entire 
protection. The 14-in. armor 
(181) six 1-in. plates, one 
4r-in. plate, and four 1-in. 
plates illustrates the princi- 
ple of the Dictators armor. 
The outer thin plates, break- 
ing joints, may be compared 
to a continuous elastic skin 
which holds the thick resist- 
ing plates in their places. 
The inner thin plates are an 
elastic backing, which gives 
room for the thick plate to 

. . P , , , , yield without breaking the 
Section of shot-hole * ^ Section of shot-hole 

through laminated ar- ribs, and prevents damage through solid armor. 

mor> 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. 



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REQUIREMENTS OF GUNS ARMOR. 



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166 ORDNANCE. 

plate, that tlie surrounding metal will have time to distribute 
the shock. Undoubtedly ; and if the shot were still slower and 
heavier, so that it would indent the plate less, there would be 
more shock to distribute. To drive a shot half way through an 
iron target, or even to considerably indent it, which any conceiva- 
ble cannon-shot however slow must do, certainly absorbs, neutral- 
izes, uses up a certain and no inconsiderable amount of power. 
That power does nothing else, and it is only the fraction of power 
remaining in the shot that inflicts other damage upon the target. 
If all the shot could be expected to strike in the same place, or if 
an iron-clad battle could be expected to last long enough to wear 
out armor by perpetual hammering, this system would be less 
objectionable. 

tJOO. The less a target resists local effect, the more it resists 
distributed effect. The 13-in. shot at 800 yards neither punched 
nor overturned the Warrior 4rJ-in. target nor shook off its plates, 
because the target was simply smashed through within a small 
area. The shield was shattered, but it saved the enemy behind it. 
The 150-lb. ball did not shake the Warrior target and its support- 
ing masonry, until it struck in front of solid timber backing 2 ft. 
square, which it could not penetrate. A salvo from three 110- 
pounders, two 68-pounders, and one 140-pounder, smashed a hole 
entirely through the " Committee target," but did not loosen a sin- 
gle bolt. The effect was wholly local. The 300-pounder bolts 
racked the 7|-in. target very little until the 301-lb. steel bolt 
struck over a rib, so that its indentation was only 6 inches. 
Then a bolt, 20 rivets, and the horizontal girder were broken, the 
plates thrown out at the ends, and the whole target was violently 
jarred. The 150-lb. ball could not get through Mr. Scott Rus- 
sell's target; so it shoved the target bodily to the rear. The 
wrought-iron 162-lb. ball was too soft to penetrate the Minotaur 
target, and therefore shook it more violently than the cast-iron 
shots of the same size which retained their figure until they got 
through. The 13-in. Horsfall shot, at 200 yards range and 1631 ft. 
initial velocity, smashed a 2^-ft. hole through a new Warrior 
target without buckling the plate struck. All the American 



REQUIREMENTS OF GUNS ARMOR. 167 

experiments with heavy shot and very thick targets lead to the 
same conclusion. 

210. The plan of intermediate weights and velocities is found- 
ed, to a certain extent, in another error, viz. : that the object of 
projectiles is to destroy armor. On the contrary, armor is in 
itself harmless ; the active enemy is the guns and the propelling 
machinery behind it. If only the shield is shattered, iron-clad 
defences have accomplished their object. Undoubtedly armor 
could be most completely destroyed by knocking off the corners 
of the plates, and dislocating and upsetting them all over with 
cracks and indentations. But, to disable the enemy, swift pro- 
jectiles must strike him through his shield, or the tremendous 
vibrations of heavy balls must tear his shield away from him. 

211. THE DUCTILITY OF THE AKMOK SAVES THE VESSEL UNDER 
EXCESSIVELY Low VELOCITIES OF SHOT. The opposite extreme is 
to increase the weight of the projectile to the utmost extent, and 
therefore to decrease its velocity (the strength of the gun being the 
limit) in proportion. But it is impossible to avoid expending much 
power in simply local distortion of the armor. A gun capable 
of throwing a hundred-ton ball would not be attempted, in the 
present state of the art, and yet a 7000-ton ram, at the velocity of 
16 miles an hour, or less than 24 feet per second, would not shat- 
ter the whole side of a ship. The principal effect of collisions is 
local. 

The elasticity and ductility of the vessel's side and of the armor 
may neutralize the effect of the projectile, if it is slow enough. 
A very swift shot completes its work before these qualities can be 
called into action. Even a plate of copper or of gold will break 
short instead of being bulged by a rifle-shot. The ductility of 
wrought iron peculiarly fits it for this service. After its limit 
of elasticity is overcome, it will continue to stretch or compress, 
as the case may be, instead of .going instantly to pieces. At the 
same time it is hard enough to oppose great resistance to change 
of figure. Mr. Mallett, in illustrating the safety of soft wrought iron 
for cannon (because so much " work done" is required to stretch 
it through its great range of tenacity), (352), much more clearly 



168 ORDNANCE. 

proves its fitness for armor, because a part of an armor-plate once 
strained beyond the limit of its elasticity may not be liit again, 
while the strains of each fire are repeated upon the same parts of a 
gun. If a shot moves slowly enough to allow the iron to stretch 
even beyond the limit of elasticity, the armor on the side of the 
ship may still absorb its power without even fracture. So that 
this extreme is equally unfavorable to the racking of the ship. 

As to jarring and shaking off the armor, the 7000-ton ram 
at 24 feet per second would be the wrong instrument, even if it 
were blunt pointed. Such a projectile, however, is so excessively 
powerful, as compared with the resistance of a vessel's side, that 
no cannon-ball can be likened to it. Estimating the work done 
to be as the weight multiplied into the square of the velocity, the 
ram would do nearly 28 times as much as a 15-in. shot at 900 ft. 
per second. Estimating it as the weight multiplied into the ve- 
locity, which the advocates of heavy shot believe to be correct, the 
ram would do above 1000 times the work of the shot. 

212. That the ductility of very soft metal is brought into ser- 

vice, even when the velocities of shot are exces- 
sively high, is proved by the bulging of the 
Thames Iron Works plate (Figs. 110 to 113), 
by the blow of a 68-lb. 8-in. wrought-iron 
spherical shot with 22 Ibs. of powder and a 
velocity of above 1800 feet per second, at 50 
yards range, and a cast-iron 68-lb. shot with 16 
Ibs. of powder and a velocity of 1579 feet. 
The flattening of the wrought-iron shot from 8 
Thames iron Works to 9 m di ame t e r across the front of the indenta- 

plate; end view. . .. 

tion, is evidence in the same direction. 

213. Inasmuch as a shot cannot be instantly arrested, the 
grand aim in the construction of armor is to increase this ductility. 
In the earlier practice, " steel-clad" ships were talked of, naturally 
enough, because steel was superior to iron for all engineering pur- 
poses. But, upon experiment, steel was not indeed punched in- 
stantly; it cracked, and crumbled, and thus failed as armor. 
Wrought iron of high tenacity, known in other construction as 




REQUIREMENTS OF GUNS ARMOR. 



169 



the best, also failed in a similar manner, in proportion to its re- 
semblance to steel. On the other hand, excessive ductility is 
accompanied by too much softness ; copper is too easily punched. 



FIG. ill. 



FIG. 112. 



FIG. us. 





Thames plate ; Front. 



Thames plate ; Top. 



Thames plate ; Back. 



But thick plates of wrought iron, however soft, fail by cracking. 
As the velocities of projectiles increase, this tendency will of 
course diminish. 

214. So that the aim of armor-plate makers is to provide 1 
toughness rather than tenacity. The difference between the early 
American plates (the early English plates were equally bad) and 
the better class of American plates, is illustrated by comparing the 
experiments with the 4|-in. Dahlgren target No. 5 (Fig.. 114), and. 
those with the Nashua plate (Figs. 115 and 116). The former tar- 
get, composed of a 4J-in. plate, 98-J 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, by the following shot, 
viz. : 

I cored cast-iron, spherical, u-inch i63-lb. shot 30 IBs. powder. 

I steel, flat-fronted, 40 y-lb. shot 8 Ibs. powder. 

I wrought-iron, spherical, 53~lb. shot 17 Ihs. powder. 

i solid cast-iron, spherical, n-inch i6y-lb. shot 30 Ibs. powder. 



170 



ORDNANCE. 



. The Nashua Iron Works forged plate (Figs. 115 and 116) 
was 40 in. wide, 4^ in. thick, and 16 ft. long. It was backed 
by 20 in. of oak and a 1-in. iron skin. At the range of 30 




yards, three 11-in. 169-lb. 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 made through the entire target. 

216. The better class of modern English plates is shown by 



REQUIREMENTS OF GUNS ARMOR. 



171 



FIG. 115. 




Section of Nashua 
target. 



Figs. 117 and 118. The former plate, backed like the Warrior 
target, with 18 in. of teak and a f~in. skin, received six 68-pounder 
balls with 16 Ibs. of powder, at 200 yards range, in a space 27 in. 
square, without breaking through. Brown's plate, which is by no 
means his best, and is marked "A 3," was 
broken through by 4 balls (charge, backing, 
and range the same), striking within a space 
about 17 x 27 in. 

317. DIFFICULTY OF ADAPTING THE HEAVY 
SHOT SYSTEM. In order to waste no power by 
the heavy shot system in order to produce the 
most destructive racking with the least local 
effect both a medium velocity, and an exces- 
sively low velocity with the weights of shot 
that the respective guns will endure, must be 

avoided ; which does not leave much margin. The former wastes 
too much power in fruitless local effort ; the latter enables the 
elasticity and ductility of the metal to prevent the destruction 
of the vessel ; and if it could be made so excessive as to be com- 
pared to a ram, it would not jar the plates and joints loose. 

318. Now, supposing the weight and velocity of the projectile 
to be adapted to any particular range and armor : a longer or a 
shorter range and a thicker or a thinner armor would obviously 
be equivalent to giving the shot too much or too little velocity. 
The contemplated circumstances of greatest effect might not occur 
once in a whole battle. What is the proper weight and velocity, 
considering the wide diversities of range and resistance ? What 
one gun, or, if it were practicable to multiply varieties, what system 
of guns can be expected to hit this narrow and ever-changing 
mark of maximum effect ? Do we not discover in these inquiries 
the serious incompleteness of the system ? 

If, on the contrary, the highest attainable velocity (modified in 
some degree by other considerations which will be further men- 
tioned) were given to the projectile, it would waste the least 
power on the armor, and reserve the most to devote to the active 
enemy within it the men, guns, and machinery. 



172 



ORDNANCE. 



FIG. 116 




219. OTHER DEFECTS OF THE 
HEAVY SHOT SYSTEM. Supposing 
the heavy shot to accomplish the 
first result aimed at dislocating 
the armor a reasonable supposi- 
tion only in the case of the War- 
rior class of armor. The enemy's 
shield is then torn away from him, 
and, as we have said, he is at the 
mercy of heavy shells with enor- 
mous bursting charges. But the 
shells must be thrown, and must 
be well aimed. There is no ques- 
tion about their result if they can 
be properly placed, and the accu- 
racy of 15-inch spherical projec- 
tiles, not to mention that of mod- 
ern rifle-shells, especially from the 
Armstrong 600-pdr. (see Chapter 
on Projectiles), is remarkable; 
still the work is not done at a 
stroke, and the enemy has time to 
turn away his wounded side, or to 
better his position by some other 
manoeuvre. 

Or, supposing the heavy shot to 
accomplish the second result aimed 
at the racking of the vessel's side, 
or the shattering of a portion of 
her side still the active enemy is 
unharmed. His ship may leak, 
and his shield may be crumbling, 
but his guns and machinery are 
yet in action. The old wooden 
walls were riddled and torn for 



REQUIREMENTS OF GUNS ARMOR. 



173 



ring had to be suspended. It was not until shells blew great 
chasms in their sides, or set them to sinking or to burning, or 
slaughtered their crews, that their power of offence was gone. 



FIG. 117. 




Thames Iron Co.'s plate. " A. 2." 



But the bursting of shells will not destroy armor nor the enemy 
within it, if they do not go through it ; iron ships will not burn ; 



FIG. 118. 




John Brown & Co.'s plate. " Y. Good A. 3. 



nor will ships with many bulkheads, both vertical and horizontal, 
sink, until they are shattered from end to end, below water. The 



174 ORDNANCE. 

Galena (262) was put hors de combat, and the Keokuk was sunk, 
and the Atlanta was disabled, by punching; not by smashing or 
racking. The Merrimac is supposed to have been discomfited by 
11-in. shot at very low velocities, although her leaking is believed 
to have been principally due to the strains she inflicted upon 
herself in trying to run over the Monitor. She was, moreover, a 
weak vessel, hastily covered with the ill-adapted materials at hand. 
This method of attack would probably prolong a battle to such 
an extent that rams, torpedoes, mortars, and various means of dis- 
abling the locomotive power of ships, might decide it after all. 
But the real danger of a prolonged battle is, that the enemy might 
get within shelling distance of cities. 

220. Breaking a disk out of a plate and driving it into the 
backing, is a frequent result of firing heavy shot at the Warrior 
class of armor ; it occurred when the 169-lb. (11-in.) spherical shot 
was fired at the 10-in. target (180). But this disk, although 
detached, still remains between the opposing projectiles and the 
men and machinery within the ship ; and it is amply sufficient to 
keep out ordinary shells (203). v 

221. GREATER STRAINS IN LARGE GUNS. The greater strains 
imposed upon large guns; their greater weight, size, and cost; 
the increased risk of defective material in large masses, and the 
enormous weight (or else limited supply) of heavy projectiles to 
be handled or transported as cargo, are ^serious arguments against 
the heavy-shot system. Of course, spherical shot can be thrown 
at given velocities with less power, as they present a larger area 
to the powder than elongated projectiles of the same weight. 

As to the greater strain upon large calibres, for a given work 
done, Captain Blakely says:* " In the 32-pounder, the shot moves 
from its position just fast enough to enable the gas of the gunpow- 
der to expand as it burns, so as never to press more than about 5 
tons per inch, the combustion being complete when the shot has 
moved about 24 inches. At this period a gas which, if confined 
in a length of the bore but 8 inches long, would give a pressure 

* " A Cheap and Simple Method of Manufacturing Strong Cannon." 1858. 



REQUIREMENTS OF GUNS ARMOR. 



175 



of 3000 atmospheres or 20 tons per inch, having four times so 
much room can only press 750 atmospheres or 5 tons per inch. 
In an 8 or 10-inch gun, the shot moves more slowly from rest, 
while the powder burns more rapidly in proportion, so that for an 
instant the pressure would exceed 5 tons per inch. In much 
larger cannon the shot would move so leisurely that the pressure 
might reach 18 or 19 tons per inch." 

Mr. Michael Scott gives the table (29) as the result of his inves- 
tigations on this subject. His explanations are appended in a 
note. (See also 258 notes and 259.) 



TABLE 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. BY MR. MICHAEL SCOTT. 










a 


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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 


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O -J O <-n 


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a\ 

00 


ON ^n ON UJ 

00 O 00 tO 


Q 


4 


73 ^a -o "o 

CO CO CO CO 


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vo 


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ON 00 4^ w 


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ON to M ^ 
O OO ON <~n Jo 
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w * 


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c 


n n n n 
& jo tO J6 

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73 "0 -n -T3 




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broadside. 


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ON 


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r I 




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12 



178 ORDNANCE. 

Captain Selwyn says* on this subject : " Strange it is, that 
even now, with all the experiments which iron-plate committees 
have tried, they have never, so far as I can learn, tried this (the 
effect of salvos), so that we have still to theorize on the subject. 
I find that four 100-pounder shot fired, not together, but con- 
secutively, broke through into the cupola of Captain Coles ; that 
several shot together, as regards the place of striking, injured the 
plates very much ; that on one occasion when six guns were fired 
as a salvo, the effect was enormously greater, as might have been 
expected, than when the same guns were fired consecutively ; but 
on no occasion can I find that any thing like even a heavy cor- 
vette's broadside was concentrated and fired at an armor-plate. 

"Now, this is the very first expedient or experiment which 
would probably be tried in war ; and till we can say that it has 
been fairly examined into, we really know nothing of the true 
value of armor." 

224. RECAPITULATION. As far as results can be compared, the 
simple 15 in. cast-iron ball at a moderate velocity appears to be 
capable, with much less strain upon the gun, of inflicting much 
more of the kind of damage under consideration, than the more 
powerful and costly rifle-bolts, because it wastes less power in local 
effect. The system of intermediate weights and velocities is least 
damaging, because it neither hits the enemy behind the shield nor 
tears the shield away from him : it spends so much power in 
smashing the place struck, that little is reserved to rack the struc- 
ture. The first result expected from heavy shot dislocating the 
plates by breaking their fastenings may be modified or prevented 
by improving the fastenings on the plan of the Dictator armor 
(204), for instance, and by other tested means. The other result 
shattering the whole ship's side to a dangerous degree is not 
fairly represented by the displacing of small targets by heavy 
shot, and presupposes shot of such excessively low velocities that 
the ductility and elasticity of ordinary armor will enable it to take 
advantage of that grand element in resistance to projectiles time. 

* Jour. Royal United Service Inst. June, 1863. 



REQUIREMENTS OF GUNS ARMOR. 179 

225. The disadvantages of the system* are therefore as fol- 
lows : 

1st. Every change in the quality and distance of the shield to 
be disabled, disturbs the designed relation of shot to armor, thus 
either wasting much power in fruitless local effect, or preventing 
serious damage by allowing the ductility and elasticity of the 
shield to come to the rescue ; in fact, both these results must fol- 
low any moderately heavy and slow cannon-shot. But a fast, 
punching shot, wastes the least possible power in getting through 
the armor ; and w r hat it has left when it gets through, is available 
upon the naked enemy. 

2d. Even supposing the enemy's side to be finally made vulner- 
able or to be dangerously strained and shattered this operation 
wastes valuable time, during which the enemy's fleet may ma- 
noeuvre to his own advantage. 

At the same time, the destructive effect of heavy projectiles at 
low velocities, particularly upon the Warrior class of armor, has 
been seriously underrated, especially in Europe. (177 C.) 



SECTION III. SHOT AT HIGH VELOCITIES.! 

226. EXPERIMENTS.^: British and American experiments have 
well tested the punching capacities of various systems of ordnance 
and the resistance of many kinds of armor. It has already been 
shown that the resistance of plates to punching is as the squares 
of their thickness; for example, that two 2-inch plates laid to- 
gether, are but half as strong as one 4-inch plate (202). It should v 
also be remembered that the hard iron of which the early English j 

* This is, of course, no argument against large shot, provided they certainly punch 
the armor instead of merely mutilating it. 

f Armor-punching projectiles must obviously go faster than projectiles intended to 
distribute their effects over a ship's side ; they must therefore be smaller for a given 
strain upon the gun. So long as a punching velocity is obtained, the larger the hole 
or the shell which enters it the better. The punching theory does not contemplate 
small shot, except in so far as reduction of weight is essential to high velocity. 

\ A more complete account of these experiments, derived from official records, will 
be given in a following chapter. 



180 



ORDNANCE. 



FIG. 119. 



and nearly all the American thick plates have been made, is 
quickly disabled by cracking and crumbling, while soft and duc- 
tile iron is greatly bulged, mashed, and upset before breaking (212 
to 2 1 6) effects which do not harm the enemy behind it, nor the 
plate itself in a very great degree. Until this kind of armor was 
adopted, the 8-in. 68-lb. shot, with 16 Ibs. of powder and about 
1422 feet striking velocity, was more than a match for the 4J-in. 
plate at 200 yards. The Thames Iron Works plates (212), 
although not the best now manufactured, show the quality of the 
better class of armor-iron. During the last year the rolling pro- 
cess, especially at the Atlas Works, Messrs. John Brown & Co., 
Sheffield, and at the Mersey Iron and Steel Works, Liverpool, has 
produced very superior plates. 

337. 10^-lNCH BALL; WARRIOR TARGET. The first memorable 
advance in the power of ordnance was de- 
monstrated (April, 1862) in the effect of the 
Armstrong 10^-in. 150-lb. spherical cast-iron 
shot, with 50 Ibs. of powder and about 1600 
feet striking velocity per second, upon the War- 
rior target at 200 yards (Fig. 119). The tar- 
get weighed above 32 tons (341 Ibs. per square 
foot), and was composed of 3 plates, each 3^ x 
12 ft. and 4 in. thick, bolted one above the 
other against 18-in. teak backing composed of 
timbers 9x9 in. ; the inner tier being laid 
horizontally, and the outer tier vertically. Be- 
hind this were the f-in. iron skin and the 18-in. 
iron ribs of the ship. The whole was sup- 
ported by diagonal braces. There was an embrasure in the centre 
of the target. 

The first and second shots at this target were made with 40 Ibs. 
of powder, and lodged in the backing. The third shot charge, 
50 Ibs. was aimed at a plate that had not been struck before, and 
punched an 11-in. hole through the whole structure. The fourth 
shot struck where it could not penetrate, and therefore shook the 
target violently. 




The Warrior target. 
Scale, i-in. to 1 ft. 



REQUIREMENTS OF GUNS ARMOR. 181 

228. 10J-INCH BALL ; MINOTAUR TARGET. In July following, 
the same gun range 200 yards was fired at the Minotaur tar- 
get, composed of 3 plates, each 12 ft. x 3 ft. 4 in., and 5J in. thick, 
backed by 9 in. of teak and -in. skin. The upper plate was rolled 
by Messrs. John Brown & Co. ; the second was forged at the 
Thames Iron Works ; the lower one was forged by Messrs. Beale 
& Co. Each plate was fastened by 3 rows of 1^ and If-in. bolts. 
One 10-in. and one 16-in. strip, 1-J- in. thick, were attached to the 
back by the same bolts at the junction of the plates. 

The first shot, a 150-lb. cast-iron ball, with 50 Ibs. of powder, 
struck the middle plate, but did not go through the target. The 
second weight and charge the same hit the top plate, and made 
a 12^ x 13-in. hole through the structure. The third shot struck 
the lower plate and punched a 13-in. hole through the target. 
The hole and rent at the back were together 16 x 30 in. The 
fourth shot has been referred to (188). 

229. 13-lNCH BALL ; WARRIOR TARGET. The next formidable 
demonstration was made by the the 13-in. Horsfall gun at 200 
yards, September 16th, 1862, against a new Warrior target, con- 
structed (without an embrasure) of 3 tongued and grooved plates, 
12 ft. 3 in. x 3 ft. 8 in. to 4 ft. 5 in. wide and 4J in. thick. These 
were backed by a layer of 9 x 9-in. teak timber standing vertically, 
another lying horizontally, a f-in. skin and 15-in. vertical ribs 15-in. 
apart. The target " tumbled home" or inclined inward 1 foot in 
8 feet height, and was set up against the old Warrior target. The 
shot was of cast iron not turned ; weight 279*5 Ibs. ; charge, 74*4 
Ibs. of powder; initial velocity, 1631 feet. It struck the centre of 
the target, smashed a 2 ft. 1^-in. x 2 ft. 4 in. ragged hole entirely 
through it, making several cracks, breaking off 2 ribs, and crack- 
ing another ; driving in 3 feet square of the skin, breaking over 
20 bolts, and dislocating the parts of the target. But the plate 
struck was not buckled (209). 

On September 26, the same gun was fired at this target under 
similar circumstances, except that the range was 800 yards. The 
result has already been specified (183); the structure was not 
punched. 



182 



ORDNANCE. 



230. 301-LB. RIFLE-SHOT ; CHALMERS TARGET. On April 27th, 
1863, after 26 rounds with 68 and 110-pounders, a 301-lb. steel 
shot was fired with 45 Ibs. of powder and 1293 ft. striking velocity, 
from the Armstrong lO^-in. rifle range, 200 yards at the Chal- 
mers target (189), which was composed of a 3f in. plate backed by 
f-in. plates on edge, 5 in. apart, with wood between (this entire 
backing was lOf in. thick), the whole resting on a IJ-in. plate 
backed by 3|-in. wood and a f-in. skin. 

The shot struck the junction of the centre and upper plates, and 
smashed a 13 x 14^-in. hole through the front, and a 1 x 2-ft. hole 
through the back of the target, driving to the rear fragments of 
plate and backing. A rib was smashed and driven back 18 in. 

231. 130-LB. STEEL SHELL ; WARRIOR TARGET. The results of 
the Whitworth and Armstrong experiments with rifle-shot and 
shell are specially important. On September 25th, 1862, the 

^Warrior target last described (229) was completely punched at 
600 yards by a Whitworth 130-lb. flat-headed shell. The gun 
(43, 44) was fabricated at Woolwich, of wrought iron, upon the 
Armstrong plan, except that it had a solid-forged internal tube. 

It was rifled on Mr. 
FIGS, 121, 122, 123. ^ rr . , 

Whitworth's plan, the 

bore measuring 6 '4 in. 
across the flats, and 7 
in. across the corners. 
The projectile* (Figs. 
120, 121 and 122), 
was 17 in. long, and 
solid for about J its 
length. It was load- 
ed with a 3-lb. 8-oz. 
bursting charge, fired 
Whitworth's armor-punching steel shells. with 2 5 Ibs. of pow- 

der, and had a velocity of 1268 feet at the distance of 580 
yards from the gun. The shell struck the centre plate, making 






* See description in chapter on Rifling and Projectiles. 



REQUIREMENTS OF GUNS ARMOR. 183 

a 7^ X 8^-in. hole, and burst in passing through the backing. Two 
cracks were made in the plate, and 2 bolts were started. At the 
back of the target the hole was 13 in. in diameter. Portions of 
the shell and the piece of iron punched out of the armor-plate 
were picked up inside the target, in what represented the hull of 
the ship ; some old oakum on the ground was set on fire. One 
rib was broken, and the wood backing was much shattered. The 
shell burst into about 14 pieces. 

This plate (from the Parkhead forge) was afterwards proved by 
the 68-pounder to be of an inferior quality. The indentation of 
the 68-pounder shot in good 4^-in. plates with Warrior backing is 
2-J- in. ; the indentation in this case was 4*05 in., with considerable 
damage in the vicinity of the blow. 

232. 151 AND 130-LB. STEEL SHELLS; 4^ AND 5^-lNCH PLATES; 
WARRIOR BACKING. On the 13th of November, 1862, further ex- 
periments were made of a similar character. The target was con- 
structed for this experiment, of 3 stories of plates, 9-J- ft. high in all, 
and 12 ft. long, secured by 2-in. bolts at the edges, so as to weaken 
the plates as little as possible. The 18-in. backing was composed 
of 12 and 6-in. teak. Behind the f-in. inner skin, a box 10 x 6 ft. 
was formed, to represent the 'tween-decks of a ship. The two 
lower plates, of 5 in. thickness, were rolled at the Atlas Works. 
The upper 4^-in. plate was forged at a Government dock-yard. 

A 151-lb. steel shell, with a bursting charge of 5-lbs., fired with 
27 Ibs. of powder, from the same gun (120-pounder), with a strik- 
ing velocity of 1170 feet at 800 yards, penetrated the middle of 
the centre (5-in.) plate, and burst in the wooden backing into 14 
large and 9 small pieces. The base and some pieces of the shell 
were blown out in front of the target ; other pieces, and fragments 
of the skin and debris, were blown into the ship, but did no serious 
damage. 

The 2d shell charge and weight the same struck 7-J- in. from 
the bottom of the top (4^-in.) plate, nearly in line with one of the 
ribs, penetrating the target and driving out the rib. The shell 
burst while passing through the inner skin, and blackened the 
chamber as well as shattering the skin and the wooden backing. 



184 ORDNANCE. 

The butt of the shell stuck in the hole, but 46 pieces of shell and 
skin were scattered about the 'tween-decks in every direction. 

The 3d shell was cast iron, and broke up, not without consider- 
able distributed effect. The 4th, of steel weight, 130 Ibs. ; charge, 
27 Ibs. ; striking velocity, 1227 feet penetrated the centre (5-in.) 
plate ; hole in front, 7-J x 8 in. ; hole at the back, 14 in. diameter ; 
skin forced out 9 inches. The shell burst as it broke the skin, and 
blackened the chamber ; it broke into 19 pieces, which, together 
with many of their fragments, passed into the ship. 

233. 288-LB. STEEL SHELL; 5^-lNCH PLATE. On the 17th of 
March, 1863, after 6 rounds with the 110-pounder and 68-pounder, 
and a 301-lb. bolt, the lOJ-in. Armstrong rifle was fired at Messrs. 
John Brown & Co.'s target, which consisted of a lower horizontal 
plate 6 in. thick, a middle plate 7-J- inches thick, and an upper 
plate 5^ in. thick, each 4 ft. high and 12 ft. long, their faces being 
flush. One side of the target was backed by vertical iron ribs ; 
the other by 10-in. of teak, a 1-in. plate, a 1^-in. plate, and verti- 
cal ribs. A heavy horizontal girder extended across the back of 
the vertical ribs. The target was held upright by heavy timbers 
extending between it and a bank of earth behind. 

A 288-lb. flat-ended steel shell, 20 in. long, with a thin cast-iron 
hemispherical head bursting charge, 11 Ibs. was fired with 45 Ibs. 
of powder at 1318 ft. striking velocity. It penetrated the 5|--in. 
plate and the backing to a depth of 14 in., and burst in the back- 
ing, the hole being filled with portions of the shell. The plate 
was somewhat cracked and dislocated. The backing at the point 
of the explosion was completely splintered and set on fire. At 
the back a rib was broken, and the skin was rent and bulged. 

234. 148-LB. STEEL SHELL; 5^-lNCH PLATE. On the same 
occasion, a 148-lb. steel shell was fired at the same target from the 
"Whitworth 7-in. rifle with 25 Ibs. of powder bursting charge, 
5*12 Ibs. at a velocity, at 524 ft. distance from the gun, of 1268 
feet. It punched the 5^-in. plate, 5-J-in. (outside to outside) from 
the last hole, and burst in the backing, which was completely 
blown out at the top. The skin at the back was more opened, 
and wooden splinters were driven through. 



REQUIREMENTS OF GUNS ARMOR. 185 

235. 300-LB. STEEL SHELLS ; 4^-lNCH PLATE." On the 17th of 
October, 1862, the following experiments were made at St. Peters- 
burg, with 9-in. cast-iron and steel shells against 4rJ-in. plates 
made for the Russian Government by Messrs. John Brown & Co., 
Sheffield: 

" First, a series of cast-iron shells, 300 Ibs. each, were fired at 
different ranges, and then shells made by Krupp were fired at the 
4i-inch armor-plates. The first shell, of hard cast steel, was 22-J 
inches long (two and a half diameters), with a flat end four inches 
in diameter. Fired with 50 Ibs. of powder at YOO 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 Krupp's steel, the same length, but 
with 6|" ends. These shells pierced plates, wood, &c., and also 
went to pieces, although only filled with sand. The fourth shell 
was made by M. Poteleff, of puddled steel, on AboukofPs system, 
the same dimensions as the second and third, and went through 
iron, teak, &c., but was only bulged up from 9" to 12", 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 shells were from Krupp, and were charged with pow- 
der; they were quite flat-ended, 9" 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." 

335 A. 610-LB. 13-lNCH BOLT; WARRIOR TARGET.* On De- 
cember llth, 1863, a 600-lb. steel shell was fired from the 13-in. 
Armstrong gun, with TO Ibs. of powder, at the Warrior target: 
Range, 1000 yards; initial velocity, about 1200 feet, bursting 
charge of shell, 24 Ibs. The shell burst on entering the target, 
and smashed a 20 x 24-in. hole entirely through it (181 C). 



* The account of these experiments, unlike the others mentioned, is not official, but 
is understood to be trustworthy. 



186 



ORDNANCE. 



B. 15-LsrcH BALL; 6-lNcn PLATE; 30-lNCH BACKING. 
More recently, a 400-lb. cast-iron ball was fired from the 15-in. 
United States navy gun, with 60-lbs. of powder, through a 6-in. 
solid plate and its 30-in. backing. Range, about 50 yards; initial 
velocity, 1480 ft. The target was otherwise smashed and shat- 
tered (181 A). 

235 C.* 11-lNcnBALL; 4f-lNcn SOLID PLATE ; 12-lNcnWooD 
FACING AND 20-lNcn BACKING. On the 28th of May, 1863, this 
target was punched at the Washington Navy Yard (Figs. 122 A, 

FIG. 122 A. 




4 in. plate, with wood backing and facing. 

and 122 B). The shot was a 168-lb. cast-iron 11-in. ball, fired 
with 30 Ibs. of powder ; range, 90'2 ft. The target was a 4J-in. 
solid plate, only 4 feet square, forged from scrap, and having 
upon its outer surface 12 inches of oak fastened with 6 bolts, and 
upon its inner surface 20 in. of oak backing, resting against a solid 
bank of clay. The shot struck 16 in. from the top of the target, 
and 16^ in. from its right edge, shattering the top land middle 
course of facing, and tearing off the upper part, throwing two 

* These facts and engravings were published officially in the " Scientific American." 



REQUIREMENTS OF GUNS ARMOR. 



187 



timbers 30 ft. forward and one piece of plate 102 ft. forward. 

Two bolts were broken. FIG. 122 B. 

The indentation around 

the shot-hole was f to 

I inch. The shot was 

fractured and flattened, 

but did not break up. 

It should be remarked 
with reference to this, 
as well as other experi- 
ments with English and 
American targets, that 
a target of this size can- 
not represent the conti- 
nuity and strength of 
a ship's side, or of a 
complete turret or case- 
mate.* It is also well 
settled in England, that 
large area of plate, iron 
box-backing (see Chal- 
mers and BelleropJion ^^- P^te, with wood backing and facing, 
targets) in addition to wood backing, ana great ductility of armor, 
are all essential features of good armor. 

* Figs. 122 C, and 122 D, represent horizontal sections of the Warrior's side at the 
junction of the armor-plated athwart-ship bulkhead with the side armor, and between 

FIG. 122 C. 





Horizontal section of the Warrior's armor. 



188 ORDNANCE. 

236. American Armor-Punching Guns.* The American 
guns that are capable of giving very high velocities to shot of 
large diameters, have not been fired at a Warrior target. But 
their effects may be approximately arrived at from their charges. 

The Parrott 10-in. rifle (78) fires a 300-lb. projectilef with 25 Ibs. 
powder. It may therefore be considered capable of carrying a 
spherical 130-lb. ball with nearly as much effect as the 10^-in. 
Armstrong gun, which made a clean breach through the Warrior 
target. The new 10-in. Dahlgren cast-iron gun fires a 130-lb. 
ball, with 40 to 43 Ibs. of powder, at about 1600 feet velocity. Its 
effect would be nearly that of the 10^-in. Armstrong, at the 
same range. The first gun of this class was cast solid, and burst 
after less than a hundred rounds; but the gun has now been 
remodelled and strengthened, and is cast hollow. The first 10-J-in. 
Armstrong gun burst after 264 rounds. The 11-in. ball, with 
30 Ibs. of powder and 1400 feet velocity, would give about 80 per 

the ports. These illustrations show, at a glance, the probable resistance of a ship a:> 
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. 



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42 


RARACTER OF Gl 


Rodman smoot 


Armstrong rifle 


Horsfall smoot 


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REQUIREMENTS OF GUNS ARMOR. 



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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. 
















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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 <?, strikes a large area of the 

plate, in a salvo of small pieces, with greatly diminished velocity 





REQUIREMENTS OF GUNS ARMOR. 199 

and effect.* A wrought-iron shot wastes power in changing its 
figure (209). 

24:7. This defect may be greatly diminished, or perhaps reme- 
died, by making the ball of steel.f 
In fact, both the rifle and the 
spherical shot should be of a harder 
and tougher material than has yet 
been employed in service. The 
experimental shot recently made 

J Flat-fronted Whitworth projectile. 

of Bessemer steel, and those used 

by Mr. "Whitworth (231), have almost doubled the power upon 
armor of the present guns. Hardness even to brittleness is 
better than softness and ductility. Even cast-iron balls do more 
damage to plates than wrought-iron of given weight and velocity 
in any form (2 1 2). It is true that candles have been fired through 
boards, and that a 40-lb. lead shot was fired through a target 
made of four 1-in. plates. But the resistance in these cases was 
slight compared with the velocity. A 5-in. lead shot, fired at a 
stronger target, was mashed to 11 in. diameter. (See Table 35.) 

248. The spherical shot, in case it does not break up, also pre- 
sents the greater area to the armor. The power required to punch 
plates in a machine, is chiefly as the sheared area. The cross- 
sectional area of a 100-lb. spherical shot is about double that of 
the 100-lb. Parrott bolt. (236.) 

To obviate these defects, an effective elongated projectile must 
be made as light as a spherical projectile. This has already been 
approximately accomplished by Sir William Armstrong. In the 
experiments of March 17th (186), 65J-lb. bolts were fired from the 
110-pounder 7-in. gun, and produced rather more effect than the 



* The particles composing a cone, the base of which is the surface of contact, are 
arrested by the impact ; the remaining particles of the projectile, composing a ring 
surrounding this cone, move on, after impact, by their inertia, until the ring breaks 
into pieces, which fly off from the reflecting surface. The ring generally breaks into 
5 pyramidal pieces, separated by as many meridian planes ; these pieces are thrown 
at various distances, depending on the velocity of the projectile and the surface of im> 
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. <?., because it stretches to a comparatively great dis- 
tance before its ductility is called into action before it reaches 
the limit of its elasticity. Ductility involves the idea of perma- 
nent change of figure ; in fact, the ductility of wrought iron is 
utilized in another way, by Captain Palliser; and his obvious 
meaning is explained by reference to his pamphlet.* 

39. Since, in practice, the elasticity of the wrought-iron inner 
tube is not proportioned to its greater elongation, it has been found 
necessary to supply the deficiency by putting it under slight com- 
pression, so that it can stretch to a greater distance. This com- 
pression is given in the Blakely guns constructed on this principle 
(60, 61) by shrinking the tubes together. Captain Palliser accom- 
plishes it by permanently stretching the wrought-iron tube while 
it is within the cast-iron tube, by means of heavy proof-charges. 
He also proposes tapering the tubes and forcing them together by 
a screw, as shown in the engraving of his gun, Figs. 155 and 156. 

33O. When the elastic limit of wrought iron has been exceed- 
ed, and it has acquired a permanent elongation, it will " set" no 
farther by a repetition of the same strain. This was found to be 
the case by Mr. Edwin Clark, in case of the chains for raising 
heavy weights, and by Captain Palliser, who tested it at follows : 
" I constructed a tube-gun which was 1^ in. diameter of bore, and 
threw a 1|- Ib. cylindro-conoidal shot. The tube was accurately 
fitted into the gun to within 1 inch from the bottom, and was 
screwed home with ease by means of the nut at the muzzle. I 
fired a series of charges increasing in severity from this gun, and 
after each discharge I took out the tube and examined it. After 
the last and most severe discharge, I found that there was some 
power required to unscrew the nut, owing to the tube having be- 
come slightly jammed. I then reinserted the tube and ground it 
back, to its place as before, with fine emery and oil. On using 
the same charge in the gun as that which had previously enlarged 
the tube, I found that it produced 110 farther effect on the latter, 

* "A Treatise on Compound Ordnance," 1863. 



RESISTANCE TO ELASTIC PRESSURE. 



277 



which can be taken out and reinserted with the same ease as at 
first." 

331. Captain Palliser's FIG. 155. 

pamphlet thus describes the 
principles and construction of 
his gun : u The manner in which 
I propose to satisfy the condi- 
tions already enunciated is by 
introducing into the cast-iron 
gun a barrel or hollow cylinder 
of coiled wrought iron, of such 
thickness in proportion to its 
calibre that the residual strain 
borne by this tube shall bear a 
relation to the strain it trans- 
mits to the surrounding cast 
iron which shall be most suit- 
ably proportioned to their re- 
spective elasticities. The precise 
proportions will depend on va- 
rious circumstances; the exces- 
sive expansion of wrought iron 
due to heat, also the greater 
range between the limits of 
elasticity and rupture of this 
metal, and that the cast iron 
will have to do nearly all the 
longitudinal work. I shall pres- 
ently show that by varying the 
thickness of the tube we can 
regulate the transmitted strains 
to the greatest nicety. * * * 

" The mechanical method by 
which I propose to insert the 
tube is by making it very 
slightly taper and placing it in the gun, whose bore is tapered 




End view of 
Fig. 155. 



68-pounder, strength- 
ened by Palliser's in- 
ternal tube. Scale, 
T 7 K in. to 1 ft. 



278 ORDNANCE. 

correspondingly : as soon as the tube comes into contact with 
the gun throughout its length, a screw washer round the 
muzzle will screw it home into its place. Since the amount 
of taper as well as the distance the tube is driven by the washer, 
is known, and that the increment or decrement in cast or 
wrought iron due to any pressure is also known, we shall in this 
manner be able to measure most accurately the strain placed on 
the cast-iron outer gun. 

" This tube may in the larger guns be divided into two or more 
concentric tubes, and these may be forced one over the other in 
such a manner that the work done by each tube may be equal- 
ized ; and a third tube made of some suitable steel for a part of 
its length placed firmly over these. The distance of the inner 
surface of this tube from that of the gun will be fixed by its elas- 
ticity, or, in other words, the thickness of the interior tubes will 
depend on the elasticity of the steel tube. 

" In the very largest guns I should wish the innermost tube to 
be constructed of the softest and most ductile wrought iron, such 
as Bradley (L) charcoal iron ; the next might be of a stronger and 
harsher nature ; and the third of steel for some distance from the 
chamber. These tubes may merely fit each other accurately, and 
the whole tube be fired with a charge equal to any that the gun 
when completed will have to withstand. The tube will, during 
this proof, abut against some substance to prevent the breech 
blowing off. The bore of the inner tube will be found to be very 
slightly enlarged. The tube will now be rebored up to the proper 
size, rifled, and placed in the gun. The tubes will be found to 
have become immovably fixed in each other, and thus a useful 
strain will be placed on each. This strain or set in the inner tube 
will never be increased by an equal charge, even were the tube 
not placed in the gun." 

332. The 68-pounder (8-inch) cast-iron gun first strengthened 
by Captain Palliser (Fig. 155) w r as bored out to 13 in., and received 
a wrought-iron tube (Armstrong coil) of 9 in. bore and 2 in. 
thickness. 

It was tested in the usual way 10 rounds with cylinders of 68 



RESISTANCE TO ELASTIC PRESSURE. 



279 



Ibs. weight and the service-charge of 16 Ibs., 10 rounds with cyl- 
inders of 136 Ibs., &c. It resisted the 100 rounds with cylinders 
increased by the weight of 1 shot every 10 rounds, and afterwards 
burst at the 7th round with double charges and single cylinders. 

Captain Palliser's second gun had an internal steel tube and 
a wrought-iron tube between the steel and the cast-iron shell. 
The wrought iron of course yielded beyond the capacity of the 
steel to stretch, and the gun burst at the first round.* 

Early in the year 1864, a 10 in. cast-iron shell-gun which had 
been rejected as worn out, was strengthened on this plan by the 
introduction of two wrought-iron coiled tubes bore was 6|- in. It 
was tested with increasing charges, and burst at the 81st round 
with a 612 Ib. cylinder and 16 Ibs. of powder. Other guns on 
Captain Palliser's plan are in process of construction at Wool- 
wich. 

333. CAPTAIN BLAKELY'S METHOD. In the addition, dated 









1 


( 






1 


; 


b,,,,,,,,,,,,,,,,,,,,,,, 






1 



" 




Blakely's breech-loading gun, with internal strengthening tube. 

April 4, 1860, to his French Patent of June 28, 1855, Captain 
Blakely thus explains the principle of varying elasticity : 

" I sometimes form the internal tube or part of it of wrought 

* The object of this construction, if it was not to demonstrate the certain failure 
of deviating from the principle laid down by Captain Palliser, can hardly be accounted 
for. In addition to the improper arrangement of the materials with reference to their 
elasticity and ductility, the softness of the wrought iron rendered it perfectly unfit to 
transfer the pressure from the steel to the cast iron. 



280 ORDNANCE. 

iron or steel (by preference in welded spiral coils) or of brass or 
of brass or iron or steel covered with coils of wire and I some- 
times cast on the outer tube after warming the inner, and some- 
times force it on cold, making the exterior of the inner tube 
slightly conical. Sometimes the inner, and sometimes the outer 
tube only extends a short distance from the breech. The outer 
tube, when it forms the principal part of the gun, I prefer to make 
of rolled iron or steel, with the fibres laid longitudinally. 

" Breech-loading cannon I make with the screwed breech-plug 
hollow open to the front and closed behind. It thus adds to the 
circumferential strength of the gun. I prefer to make this plug 
taper towards the front for facility of putting it into its place. 

" The annexed drawing (Fig. 157) shows a section of a gun thus 
built. A is the hollow breech-plug, B B an internal tube which, 
being compressed by the tube C C, w r hich forms nearly the whole 
gun, adds much to its strength. The amount of the compression 
must depend on the kind of metal used and on the thickness of 
the inner tube. I have found by experiment that when the inner 
tube is one-third as thick as the diameter of the bore, its outer 
parts are only strained about one-third so much as its inner parts, 
and when two-thirds as thick as the bore, then the outer parts are 
only strained one-seventh as much as the inner. I therefore try 
how much the material of both tubes can be stretched without 
injury and adjust the size of each tube, so that before the inside 
of the inner one is fully strained the inside of the outer one shall 
be so. If, for example, the inner tube be 6 inches in bore and 2 
inches thick, and made of coils of good steel which will stretch 1 
in 300, then I know that when the inner diameter of the tube is 
stretched to G-V inches, the outside will only be stretched to lO^V 
inches. If now the outer tube be made of the same steel but with 
the fibres laid longitudinally so that it can only stretch say one in 
600, then I make its inner diameter 9 '995, so that when it be- 
comes 10gV it shall be fully strained. D D is a ring bearing the 
trunnions also adding strength to the gun as does the ring E E, to 
which is attached a support for the breech-plug when withdrawn 
from the gun. A hole through the plug will admit of the powder 



THE EFFECTS OF VIBRATION. 281 

being ignited by suitable means. I prefer a needle to strike deto- 
nating powder, as is now much practised for small arms." 

334. The manner in which Captain Blakely at present utilizes 
the varying elasticity of metals, by combining it with the system 
of initial tension, has already been described (59, 60). Fig. 158 is 
a 9 in. gun ; the inner tube is made of a highly elastic steel, the 
second tube of a less elastic steel, and the outer jacket of cast iron 
which is least elastic. The deficiency in elasticity of the inner 
tubes is compensated by shrinking all the tubes together with a 
slight initial tension. 

SECTION II. THE EFFECTS OF YIBEATION. 

335. Both the means above considered, of increasing the 
resistance of a gun to mere pressure, are perfected only in propor- 
tion to the number of separate tubes or layers employed. But 
increasing the number of parts, lessens the resistance of a body to 
another effect of strain, especially of sudden strain. 

If a thick armor-plate, composed of layers placed in close con- 
tact but not fastened nor welded together, is struck by a shot, two 
kinds of motion will be imparted by the shot. The observed 
result will be (supposing for the moment that the figure of the 
parts is not permanently changed), that if the plate is 100 times 
heavier than the shot, and the shot has a velocity of 1000 feet per 
second, the plate will be moved bodily at the rate of 10 feet 
per second. But before this occurs, the whole force of the shot 
will have been communicated through the mass from one layer to 
the other, by a wave moving at about the velocity of sound. The 
layer struck will be for an instant reduced in thickness and ex- 
tended in its other dimensions. When it recovers its original 

o 

figure by its elasticity, it will in turn compress the next layer, and 
so on, until the last layer receives the shock. When this last 
layer is compressed (its inertia tends to hold it in place until it is 
compressed) it is then in the condition of a spring pressing equally 
in both directions, and resisted by a heavy mass on one side, but 
by only its own weight on the other; so that it jumps violently 
to the rear. But if the layers were welded together, this ten- 



282 



ORDNANCE. 



FIG. 158. 



dency to separation would be overcome by the cohesion of the 

metal. 

This phenomenon occurs when a gun is fired. The shock is 

propagated from layer to 
layer, in a wave. If the 
layers are already detached 
tubes, the outer one has 
no help from the rest in 
resisting vibration. Of 
course, the shock on the 
outer layer is not as great 
as the first shock upon 
the interior, because it has 
been distributed over more 
space, and diminished in 
overcoming the ductility 
of the interior. The ob- 
vious method of modify- 
ing the effect of the wave 
of strain upon the outer 
layer, is to give it mass, 
and hence great inertia. 

But in case the outer 
tube is in high initial ten- 
sion, this effect of vibra- 
tion is probably much 
aggravated. The initial 
tension of the outer tube 
certainly increases the re- 
sistance of the whole series 
of tubes to a statical inter- 
nal pressure, but its indi- 
vidual resistance to strain 
is lessened, and it opposes 
only its individual resist- 
ance to the wave of strain. 




Blakely 9-inch high and low steel and cast-iron 
gun. Scale, ^ in. to 1 ft. 



THE EFFECTS OF HEAT. 283 

These facts would appear to account for the failure of many 
outer tubes of the Armstrong guns of the 300-pounder, for 
instance tubes which are understood to be put on with less ten- 
sion, even, than that required by statical pressure alone. 

In addition to this instantaneous wave of strain, other vibra- 
tions, like those of musical strings, undoubtedly take place in the 
pieces of a gun, and these vibrations are unequal, being propor- 
tioned to the size and tension of the parts. It is known in engi- 
neering, that fractures are likely to occur where parts under 
vibration suddenly increase in size ; for instance, where the plates 
of a boiler overlap. 

The character and circumstances of the failure of hooped guns 
are too indefinitely understood, at present, to warrant any very 
positive conclusions on the subject ; but it is certainly reasonable 
to suppose that the building up principle may be carried too far 
that there must be a certain amount of mass and continuity of 
structure to resist waves of force and vibration, as well as a 
certain division of parts to resist statical pressure. 

SECTION III. THE EFFECTS OF HEAT. 

336. The heat of gunpowder when exploded within its original 
volume, is estimated to be about 7000 Fahr. Exactly, or even 
approximately, what the temperature in a gun is, and how long it 
acts on the walls of the gun, has not been ascertained, but in the 
case of rifled guns, especially when the inertia and friction of the 
projectile are great while the area pressed upon is small, there is 
obviously an excessive temperature, arid an appreciable time for 
the reception of heat by the surrounding metal. The heat of the 
exploded gas may be felt outside a thin field-gun immediate! j 
after the first discharge. 

"Whatever heat there may be, expands the interior of the gun, 
and, if the walls are without strain, it puts the interior into com- 
pression, and the exterior into tension, thus strengthening the 
piece, up to a certain point. When a gun is cast or forged solid, 
and therefore left, by the quicker cooling of the exterior, in a 
state of external compression (364), the heating of the interior, by 



284 ORDNANCE. 

the powder gas, strengthens the gun in a still greater degree. 
But when the strains of a hooped gun are once properly adjusted, 
this internal expansion by heat disarranges them, by increasing 
the compression of the interior parts and the tension of the exterior 
parts, thus weakening the gun to an extent which is worthy of 
consideration, when, as Mr. Longridge proves (293), an error of 
T 7 inch in the diameter of a 17-inch hoop decreases its strength 
4:0 per cent. 

At the same time, the interior of the gun is expanded longitu- 
dinally, which also tends to rupture it, if it is solid. But if the 
heated inner tube can slip endways without disturbing those out- 
side of it (the inner tubes of Armstrong guns do slip in this way, 
from various causes), the longitudinal expansion may not be a 
source of direct strain, although the dislocation of the parts would 
injure the gun in other respects.* 

337. The guns in an iron-clad ship must be few in number, 
because turrets and casemates thick enough to resist shot must be 
of small dimensions. It is therefore obvious, especially in view 
of the limited offensive qualities of the Monitors before Charles- 
ton, that effective iron -clad warfare must depend on very rapid 
firing. This rapid increase of heat the intense and maintained 
heat due to heavy charges and elongated projectiles in guns with 
thick walls, would appear to be sufficiently dangerous to warrant 
at least a thorough experimental investigation of the subject. f In 

* Sir "William Armstrong says, in his report of July 14, 1855, on wrought-iron rifled 
field guns, that his gun "was remarkably free from tendency to become heated by 
firing, a fact which can only be explained upon the supposition that the heating of a 
cannon is occasioned, not by the contact of the flame, but by some molecular action 
of the metal, produced by the explosion, and more effectually resisted by wrought iron 
than by cast iron or bronze ; but possibly the compound structure of this gun may also 
operate to deaden vibration, and prevent the evil in question." 

f It is, however, stated, that in the Crimea, some 68-pounders were fired rapidly, 
and endured 2000 rounds; that the cast-iron guns at the siege of San Sebastian stood 
300 rounds a day, and that many of the large British siege-mortars have stood 2000 
rounds with 20 Ib. charges, fired very rapidly. 

Captain Blakely says that a Spanish cast-iron hooped gun, that stood 13GG rounds, 
with a 61 Ib. elongated shot and 7 Ibs. of powder, wt:s fired on the first day 100 rounds, 
at intervals of 1 minute to 1| minutes, which made the gun so hot it could not be 
touched with the hand. On the following days, 50 rounds were fired in the morning, 
and 50 in the evening, with the same rapidity. Jour, Royal U. Service Inst., June, 1862. 



CONCLUSIONS. 285 

the absence of all direct experiment, it is impossible to assign the 
proper importance to this obvious cause of weakness in large ord- 
nance, especially when placed under initial strains. Mr. Norman 
Wiard, of New York, has treated the subject with great ingenu- 
ity ; his views and illustrations will be found in the appendix. 
Other authorities* have referred to the effects of rapid firing upon 
the durability of cannon. Mr. Mallet says : " The expansion of 
the interior of the gun, acting tangentially, exercises against its 
rigidly resisting exterior a powerful splitting strain. The elonga- 
tion of the interior of the chase, from the same cause, drags or 
forces the exterior to elongate along with it."f 

338. Mr. "Wiard proposes to remedy this cause of failure in 
two ways : 1st, by shaping the gun so that it can expand without 
excessive strain. This plan will be referred to under the head of 
cast iron (383). 2d, Mr. Wiard proposes to make the tubes of a 
gun of different metals, arranged with reference to their respec- 
tive elongation by heat. An inner tube of steel, although in 
direct contact with the heated gases, would not expand much 
more than an outer, less exposed tube of bronze; so that the 
initial strain would be little disturbed. 

The most obvious and simple remedy is, to cool the interior of 
the gun with water after each discharge. Automatic machinery 
to do this has been designed. (See Chapter on Breech-Loading.) 

339. CONCLUSIONS. It has been clearly demonstrated that 
merely thickening the walls of a gun, beyond a point nearly if not 
quite reached in practice, adds very little to its resistance to 
internal pressure. A homogeneous gun, in a state of initial 
repose, cannot, however thick, sustain a pressure per square inch 
greater than the tenacity of a square inch of the metal of 
which it is composed. The reason is, that the inner layers of 
metal are more stretched, and hence strained, than the outer 

* "On the Construction of Artillery," 1856. 

j- Mr. Longridge says: ''This is, probably, the cause of guns being more liable to 
burst when they get hot. It is not that the iron is weaker, for Mr. Fairbairn has 
shown that up to 600 the strength of cast iron is not materially diminished; but when 
the gun is heated, the gunpowder gets warmed and burns more rapidly, and the force 
is generated and applied more suddenly." "Construction of Artillery," List. C. E., I860. 



28 G ORDNANCE. 

layers, by an internal pressure, in the inverse proportion of the 
squares of their diameters. Therefore, the layers must be placed 
under such initial strain, or must possess such varying elasticity, 
that all parts of the gun will be equally worked at the instant of 
firing. Both these conditions are perfectly carried out, in propor- 
tion to the number of separate layers or tubes thus treated. 

But the wave of force (in distinction from statical pressure), and 
the effects of unequal vibration, distress a gun in proportion to 
the number of its parts ; so that the building-up principle cannot 
be carried far without depriving the gun of the necessary mass 
and continuity of substance. 

It is probable that, with the present materials, and given 
weights, a gun composed of two tubes, although not as strong to 
resist statical pressure as one composed of five or six tubes, would 
resist a greater number of heavy charges of gunpowder, and prove 
a more trustworthy and valuable weapon. At the same time, it 
would be very much stronger than a single homogeneous tube. 

The system of hoops with initial tension, although theoretically 
perfect, and an acknowledged improvement in the construction of 
ordnance, involves certain practical difficulties. It is difficult to 
obtain, and, with the present materials, difficult to preserve, the 
proper accuracy of tension. When several thicknesses of hoops 
are employed, the maintenance of the proper longitudinal strength 
is an embarrassing problem witness the history of the Armstrong 
gun. The hooping of old cast-iron guns requires either a change 
in the position of the trunnions, or an inconvenient preponder- 
ance,* and a change in the structure of the gun-carriage. 

Lining a cast-iron gun with a tube, elastic in proportion to the 
elongation it receives, strengthens the gun vastly more than it 
could be strengthened by a hoop of the same cost and weight, and 
requires no change in the trunnions and carriage. And, unlike 

* Turning down the reinforce of a cast-iron gun, and making up the original diame- 
ter with wrought iron, instead of hooping outside the original thickness of cast iron, 
for the purpose of maintaining the proper preponderance, or even for the purpose of 
avoiding changes in the gun-carriage (which would appear to be the only excuse for 
the construction adopted by Sir William Armstrong see Fig. 49), is obviously the 
most expensive proceeding possible, for it simply ruins the gun. 



CONCLUSIONS. 287 

the Loop, the lining tube is not under a constant deteriorating 
tension. Such a lining is also likely to prevent explosive bursting. 

But, with the present materials, it would be almost impossible 
to insure uniformly a degree of elasticity in the different layers 
exactly proportional to their respective elongation under fire. 

Therefore, the hooping system, so modified as to avoid some of 
its defects, may be brought to the aid of the system of varying 
elasticity. If the internal tube of a gun cannot stretch to the ex- 
tent required without injury, placing the external tube in slight 
tension will remedy the defect. Then the inner tube will have a 
greater safe range of elongation, and the outer tube will take a 
greater share of the strain. 

The system of varying elasticity is most conveniently and 
cheaply carried out (even in connection with the system of initial 
tension) by placing the finer and more costly metals within, and 
the coarser and cheaper metals without. A heavy mass of cast 
iron, where weight and large size are not a serious embarrassment, 
is, perhaps, the best outer jacket. A mass of steel, cast hollow 
and not hammered, is stronger than cast iron, and but about half 
as expensive as a hollow-forged jacket.* In either case, this ex- 
terior 7Yiass not only performs the work demanded of the outer 
jacket, but overcomes the other grand defect of hooped guns. Its 
great weight and inertia absorb the wave of force (335), which 
would fracture the thin ring under initial tension. 

On the whole, a steel tube, so tempered (probably by hardening 
in oil) as to have the greatest possible elongation within its elastic 
limits, and forced into (or otherwise compressed within) a heavy 
cast-iron jacket of good shape, like the United States 15-in. hollow- 
cast Navy gun, with trumr.ons and cascable cast on for cheapness 
the slight initial compression of the steel being sufficient to com- 
pensate for its want of safe elongation (59) would appear to be 
the best system of fabricating strong, cheap, and trustworthy can- 
non of large calibre. 

* The cost of hollow-cast jackets for 11-inch guns is $350 per ton; that of jackets 
hammered over mandrels, $600. 



288 ORDNANCE. 



CHAPTER IV. 

CANNON METALS AND PROCESSES OP FABRICATION. 



SECTION I. ELASTICITY AND DUCTILITY 

340. laticity. It has long been known that the ultimate 
tenacity of metals is only an approximate indication of their safe 
working load. All metals used for cannon have an appreciable 
elasticity, but the range of this elasticity the extent to which 
they may be elongated by pressure before permanently changing 
their figure is very diverse for different metals, and very indefi- 
nitely determined for all. 

The use of elasticity is, that it allows space for the power to act 
in, without permanently stretching and thus injuring the metal. 
Upon the application of any force, metal having no elasticity 
would either permanently stretch, or else it would instantly break. 

341. ELASTIC LIMIT OF METALS. There is no doubt that iron, 
in all forms, has some positive elasticity that it will resume its 
figure, when strained to a certain extent, so nearly, that for all 
practical purposes its elasticity may be called perfect. Mr. Col- 
burn says on this subject, in his valuable paper before the Society 
of Engineers :* " It is commonly held that within certain limits of 
strain, iron is perfectly elastic. No matter how often it may be 
stretched or deflected up to a certain point, the general belief is 
that it will come back to its original form every time the load is 
taken off. There are high authorities, however, who maintain 
that iron takes a permanent set under even very moderate strains. 
If we are to understand that the sot is exceedingly small, this may 
be true. * * * Mr. Edwin Clark has experimented on a wrought- 
iron bar 10 ft. long and 1 in. square. Under a strain of 3 tons per 
square inch, he gives the permanent set as nearly the 4 oV<r part of 

* "On the relation between the safe load and the ultimate tensile strength of iron," 
March 2, 1863. 



ELASTICITY AND DUCTILITY. 289 

an inch in 10 feet. With 8 tons, the permanent set is given as 
about the y^o of an inch in 10 feet, and it was not until a strain 
of 13 tons per square inch had been applied that a set of -^ inch 
in 10 feet became apparent. With such exceedingly minute meas- 
urements, we may perhaps doubt if there was really any perma- 
nent set at all, with strains under 9 or 10 tons per square inch. 
An increase of temperature in the bar, of perhaps a single degree, 
while the measurements were being made, would more than ac- 
count for some of the reported sets, even under considerable 
strains. Thus, Mr. Edwin Clark gives the permanent set of his bar, 
after a strain of 8 tons per square inch, as the yjaVj F P ar * of its 
length ; and this is almost exactly what the extension of the bar 
would have been had its temperature been raised but a single 
degree between the observations. Iron is heated in the very act 
of straining it, and a sudden breaking strain will generally leave 
the broken ends too hot to be handled. Such a slight apparent 
extension might also have occurred while the shackles by which 
the bar was strained were coming to their bearings. But even if 
such a microscopic permanent set really existed, it is one of which 
no engineer would take the slightest notice, as affecting the 
strength of the bar in which it was observed." 

342. So few experiments have been made to determine the 
elastic limit of different metals, that no general rule has been 
adopted. Mr. Colburn says : " When we come to the question of 
safe working strength, much difference of opinion exists among 
engineers, the permanent supporting power of iron being vari- 
ously estimated at from T V down to T V of its breaking strength. 
What information we have goes to show that there is no- 
settled relation between the elastic limit and the breaking weight 
of iron ; the former is more variable than the latter, and can 
hardly be expressed as an average result, as it ranges from less 
than { to more than f of the breaking weight : or, if the clastic 
limit be taken irrespective of the breaking weight, the instances 
cited show that the power varies from 3J up to 24^ tons per square 
inch in different qualities of iron, although the range in ordinary 
bar iron and plate iron is not nearly as great." 
19 



290 



ORDNANCE. 



Tables (51, 52, and 53) are given by Mr. Mallet in his " Con- 
struction of Artillery.""* 

TABLE LI. RELATION OP ELASTIC LIMIT AND OF EXTENSION TO ULTIMATE CO- 
HESION, ACCORDING TO CONTINENTAL EXPERIMENTS, IN ENGLISH MEASURES. 



Nature of Metal, and Authority. 


Elongation 
at limit of 
Elasticity. 
Length of 
bar 1-0. 


Corre- 
sponding 
Strain in 
pounds per 
sq. inch. 


Ratio to 
the ulti- 
mateCo- 
hesion. 


Value of Co- 
efficient of 
Elasticity in 
Ibs. per sq. in. 




00167 
00062 
00072 
00093 
00084 
00088 

00222 


30000 
17634 
21349 

25600 

21 300 
21300 
93866 


o- 63 
o- 36 
0-40 
0-45 

-33 
o- 50 
0-67 


34133400 
28444500 
29440100 
25591165 
26026718 
24177825 
42666750 


Ditto (Duleau) mean 


Ditto (Lagerhjilm), mean 




Iron \Vire (1-2 mil diam ) hard 


Ditto (Ardant) foft 


Caft Steel, Englifli, blue temper, mean (Morin) 



TABLE LII. RESISTING POWERS OP KRUPP'S CAST STEEL AS COMPARED WITH 
OTHER METALS FOR CONSTRUCTING ORDNANCE. FROM A REPORT BY THE PRUS- 
SIAN MINISTRY OP WAR. 



Metal. 


Ultimate 
Resistance 
to Tension 
per square 
inch. 


Ultimate 
Resistance 
to Torsion. 


Angle of 
Torsion 
before 
Rupture 


Value of Tr 
deduced.t 


Krupp's Caft Steel, No. I (Einkron) 


I I 721 1 


76700 


207 


37 C7OCO 


Do Do 2 


I Idol 


4.014.0 


128 


76C274.O 


Do Do 3 


IO7 C I 6 


7.4.620 


221 


782C CIO 




77118 






4028220 


Caft Iron 


I 0-54.1 


17 C IO 


jAt, 
I 2 


I 05060 


Gun Metal, 10 per cent. Tin 


4.7 c 76 


2OA7O 


4.OO 


408 6OOO 


Do 9 Do 


4.1 4-s4 


208 10 


386 


4.OI 67 7O 


Do ii Do. 


7661 c 


20320 


5 I C 


72OO4.OO 


Do 12 Do. ,.. , 


72774 


18300 


I 7O 


IlSqqoo 













* The elongation of wrought iron and steel at the point of rupture, and the corre- 
sponding pressure, will be further considered. 

t Tr= foot-pounds to produce rupture by tension, after the limit of elasticity has been exceeded. 



ELASTICITY AND DUCTILITY. 



291 



TABLE LIU. RESISTANT Vis VIVA OF ELASTICITY AND OF RUPTURE BY TENSION OF 
THE METALS APPLICABLE TO THE CONSTRUCTION OF ORDNANCE. 



Metal. 


i 

Exten- 
sion per 
unit of 
length up 
to elastic 
limit. 


Strain per 
unit of 
section at 
elastic 
limit. 


P 

Strain 
in 
tons. 


*Te = | Pi 

Value for 
unit of 
length and 
section. 


Tr 
Value for 
unit of 
length and 
section. 


e 
Coefficient 
of elasticity 
for unit of 
section. 






Lbs. 




Dynams. 


Dynams. 


Lbs. 


Caft fteel (Englim), blue temper.. 
Caft fteel (German), foft 


00022-|- 

00096 


47040 
7 C 7Q2 


21 -0 

ic-8 


5 ' Ia 5 
16-988 


39650 
107 coo 


42666750 
28866725 


Wrought-iron bar, maximum 
ducYility 


00090 


I7O24. 


7-6 


7-660 


96000 


25000000 


Wrought-iron bar, ftrong and 


OOOC4- 


2?76o 


1 1 C 


6 .qc f 




284.4.4.^00 


Caft iron, mean 


00085 


141 1 2 


6-7 


5.QQ7 


12287 


17066700 


Gun metal, caft, mean 


00104 


IO7O4. 


4.. 6 


5-708 


Q72C2 


OQCCC7C 


Brafs wire, drawn and foftened.. 
Brafs, caft, mean 


00135 

00076 


21280 

604.4. 


9*5 

3. j 


16-490 

2 670 


31680 
20900 


9173190 

8070000 

















As to the elastic limit of cast and wrought iron, Mr. Colburn 
states that two cast-iron beams, experimented upon by Mr. Hodg- 
kinson, took each a permanent set with weights respectively equal 
to j\ and V of the breaking weight ; and that " in a discussion at 
the Institution of Civil Engineers, a Mr. Dines mentioned that he 
had tested upwards of 8000 cast-iron girders for the late Thomas 
Cubitt, and that he found it hardly possible to apply a weight so 
small as not to produce some permanent set, one-twentieth of the 
breaking weight producing a perceptible set. * * * In seven ex- 
periments by Professor Barlow, on wrought-iron bars 10 feet long, 
2 of them retained their full elasticity under a strain of 11 tons per 
square inch ; 3 bars bore 10 tons without injury, while one bore 
9^ tons, and another, made from old furnace bars, did not retain 
its elasticity beyond a strain of 8| tons per square inch. ***** 



* Te = foot-pounds in reaching elastic limit of tension. 

t In Table 51 Mr. Mallet puts this -00222, which is right according to other experimenters. 



292 ORDNANCE. 

Mr. Edwin Clark, from the results of his experiments, consider* 
that the limit of elasticity of wrought iron is 12 tons per square 
inch." 

343. The following results (Table 54) of Mr. Mallet's experi- 
ments were stated by him to the Institution of Civil Engineers, in 
his paper of March 1, 1859, " On the Coefficients of Elasticity and 
Rupture in Massive Forgings :" 

Mr. Anderson, Superintendent of the Armstrong Gun Factory 
at Woolwich, states* that "from several 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 permanently gives an aver- 
age 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 when permanent elongation com- 
mences." In heavy forgings, " the average point of yielding per- 
manently was 23760 Ibs. average point of ultimate fracture being 
48160 Ibs. The forgings from which the specimens were cut were 
all of high quality." 

311. Ductility (GAIN OF STRENGTH BY STRETCHING). Be- 
yond the limit of elasticity, some metals, especially soft wrought 
iron, may be considerably and permanently stretched without rup- 
ture. After stretching, they appear to assume a new arrange- 
ment of particles and a new limit of elasticity until close to the 
point of rupture, when they lose all elasticity and ductility, but 
gain ultimate cohesion, that is to say, a bar that is a square inch 
in section after stretching, will stand a greater pull than an inch- 
square bar that has not been stretched. Wrought iron increases in 
tenacity when drawn into wire, or cold rolled or cold stretched. 
and especially when stretched after a little heating. Mr. Ander- 
son states,* as a result of many experiments on iron for Armstrong 
guns, that "after the first yielding, by the addition of extra 
weight, the wrought-iron specimen gradually stretches until it lias 
been considerably reduced in diameter; and such parts as have 
been so reduced have a greater tenacity per square inch than 

* Journal of the Royal United Service Institution, Aug., 1862. 



ELASTICITY AND DUCTILITY. 293 

when in the previous normal condition. The iron has to a small 
extent assumed the character of wire, which, from the drawing 
process, is always stronger than the iron out of which the wire 
is made." 

Mr. Colburn states that increasing the strength of iron by draw- 
ing it is probable, from the known results of drawing wire, and 
that " when heated moderately, or to less than a dull red, and then 
stretched, iron is strengthened throughout. This treatment is 
known as thermo-tension, and in an extensive course of experi- 
ments made about twenty years ago, by Professor Walter R. John- 
son, for the United States Government, a total gain of nearly 30 
per cent, in strength and length, taken together, was estimated 
to have been obtained with a variety of irons. * * * Captain 
Blakely has lately proposed the same treatment of iron, and 
his experiments, it is understood, corroborate those of Professor 
Johnson." 

Captain Palliser mentions the following experiment :* " I con- 
structed a tube-gun which was 1J in. diameter of bore, and threw 
a 1 J Ib. cylindro-conoidal shot. This tube is -J in. thick and rifled. 
The tube was accurately fitted into the gun to within one 
inch from the bottom, and was screwed home with ease by means 
of the nut at the muzzle (332). I fired a series of charges, increas- 
ing in severity, from this gun, and after each discharge I took the 
tube out and examined it. After the last and most severe dis- 
charge, I found that there was some power required to unscrew 
the nut, owing to the tube having become slightly jammed. Thus 
this shot sufficed slightly to disturb the equilibrium of the tube. 
I then reinserted the tube and ground it back into its place as 
before, with fine emery and oil. On using the same charge in the 
gun as that which had previously enlarged the tube, I found that 
it produced no further effect on the latter, which can be taken out 
and reinserted with the same ease as at first." 

115. But the addition of strength by stretching is not all 
gain, because, although the tenacity of a given area is increased, 

* "Treatise on Compound Ordnance," 1863. 



294 



ORDNANCE. 



TABLE LIT. PROPERTIES OF LIGHT AND HEAVY WROUGHT-IRON FORGINGS. 

Mallet, Inst. Civil Engineers, March, 1859. 
Unit of Section, 1 square inch x 1 foot in length. 



No. 


CHARACTER OF IRON. 


Form of Fracture. 


I 

2 

3 

4 
5 

6 

7 

8 
9 

10 
ii 

12 

*5 


Fagoted forged flabs, drawn out under fteam hammer 
to 11x2^ in 






The fame, drawn out under hammer 


Fibrous . . 




Rolled flabs of the fame iron as No. i, and fame 
dimenfions 






Rolled bar fame as No. 3 


Fibre and fome cryftal 




Hammered flabs from beft felefted Scotch and North 
Wales pig. Rough bars hammered with flabs, and 
thefe piled and hammered to 5^ ft. fquare x 12 in. 
thick. Bars cut parallel to broad furfaces.. . . 


Cryftal traces of fibre 




Crude pig fame kind as No. 5, puddled, rolled into 
No. i bar iron, whifh was cut up, piled, and rolled 
into No. 2 bars to be piled for central forging of 
Horffall 1 3-inch gun 


Fine cryftal and traces of fibre 

Coarfe cryftal and trace of fibre 
Coarfe cryftal 


Bar cut longitudinally out of exterior of mafs forged 
from pile of fuch bars as No. 6 


Similar bar from fimilar forging to No. 7 


From a hoop (3 ft. diameter), cut out of circumference 
of fimilar forging to No. 7 


Coarfe cryftal and fome 
Coarfe cryftal 


fibre.. 


From a hoop, cut from the mafs that No 7 longitu- 
dinal bar was obtained from 


Bar cut parallel to diameter from muzzle end of gun- 
forging made from bars No. 6 


Fine cryftal 




Bar fagoted in charcoal fire from the heavy " curled 
borings" from interior of gun forged from bars 
No. 6 


j 
Fine fibrous. ... 




Puddled fteel 













ELASTICITY AND DUCTILITY. 



295 



TABLE LIY. CONTINUED. 



s 

</r tn 


Tension at 

elastic 
limit. 


Total ex- 
tension at 
elastic Final value 
limit. ofTe. 


Tension at 
rupture. 


Total ex- 
tension at 
rupture. 


Value of 
Tr. 


Ratio of 
final distor- 
tion at rup- 
ture. 


Ratio of ten- 
sion to ex- 
tension at 
elastic limit. 




Tons. 


Inches. 




Tons. 


Inches. 








75 i8 


15.312 


0-0143 


20-579 


24-062 


2-2166 


4978-1 


100 : 140 


100 : 1071 


7546 


14-219 


o 0240 


31-850 


22-969 


1-6333 


35 01 '4 


100 : 129 


100 : 592 


7457 


10-937 


0-0333 


33-993 


22-969 


1-8290 


3920-9 


100 : 133 


100 : 328 


7537 


10-937 


0-0200 


20-416 


22-969 


2- 1667 


4644-6 


loo : 140 


100 : 547 


7610 


8-750 


0-0156 


22-740 


18-594 


0-0924 


160-4 


100 : 101 


100 : 561 


7649 


12-031 


0-0292 


32-789 


21-875 


0-6600 


347-5 


100 : in 


100 : 412 


7772 


9-844 


o- 0240 


2,2-050 


19-688 


I 0400 


1911-0 


100 : 118 


100 : 410 


7640 


10-937 


O-OIIO 


11-229 


17-900 


o- 5200 


869-4 


100 : 129 


100 : 994 


7632 


6-562 


0-0100 


6- 125 


i 6 406 


0-0772 


118-2 


100 : 101 


loo : 656 


7614 


5-470 


0-0152 


7-758 


16- 716 


o- 1040 


162-4 


100 : 101 


100 : 360 


7673 


3-281 


o - 0040 


1-225 


6-562 


0-0424 


3i-9 


100 : 101 


100 : 820 


7634 


5-470 


0-0800 


40-833 


22- 321 


0-9280 


1928-2 


100 : 116 


100 : 68 


7795 


14-219 


0-0288 


38-220 


42.3 


o- 6700 


2693-1 


i oo : i i 2 


loo : 494 



296 ORDNANCE. 

the total area is diminished. And this property of ductile metals 
is not depended upon in the construction of engineering works. 
On the contrary, a load that will permanently change the figure 
of an iron or steel structure, is deemed unsafe. The importance 
of determining 'the elastic limit of metals, so that it may not be 
exceeded in practice, is just now discussed in Great Britain with 
unusual earnestness. 

Mr. Colburn remarks, after mentioning instances of increased 
tenacity by stretching : " But from what has been said, it is not 
to be supposed that iron is not injured by excessive strains, not- 
withstanding that the metal strained may, when tried immediately 
afterwards, still retain its full breaking strength. The injury will 
appear when a subsequent working strain is long continued ; and 
even without waiting for this, it will be found that strained iron 
has been deprived of a large part, if not the whole, of its natural 
elasticity." The same writer mentions the following experi- 
ments : The late Mr. Yicat, from 1830 to 1833, investigated the 
strains on unannealed iron wire. " One wire was strained to 
its breaking weight, but beyond the elongation which at once 
took place no additional stretching occurred in 33 months. A 
second w r ire was strained to 1 of its breaking weight, and in 33 
months it stretched at the rate of 2f parts in every 1000 parts of 
its length, this stretching being additional to that which took 
place as soon as the weight was applied, but which of itself was 
not sufficient to immediately produce any permanent set. Under 
a strain of of the breaking weight, another wire stretched rather 
more than 4 parts in every 1000 parts of its length. Under a 
strain of of the breaking weight, a fourth wire stretched, in 33 
months, 6 parts in every 1000 parts of its length, and then broke, 
which circumstance terminated the experiment." 

34O. If, then, the limit of elasticity is not exceeded in other 
structures, why should it be in guns ? Are the circumstances un- 
der which wrought iron does appear to gain strength by stretch- 
ing, the same as those of cannon strained by gunpowder ? In one 
particular they are certainly similar. Wire drawing and cold 
rolling involve the application of lateral pressure in addition to 



ELASTICITY AND DUCTILITY. 



297 



mere stretching. Gunpowder upsets or draws the iron as under a 
hammer. The testimony of Sir William Armstrong and Mr. John 
Anderson before the Defence Commissioners is very clear on this 
point (402). But does the suddenness of the strain brought upon 
a gun render its change of figure safe, when that of a uniformly 
loaded beam or chain would be dangerous? Experiments show 
that a sudden jar will cause the fracture of bars that had long 
remained whole under strains greatly exceeding their elastic limit, 
and approaching very near to their ultimate tenacity. In Mr. 
Farbairn's experiments of 1837 to 1842, columns loaded with of 
their breaking weight could only be made to support it for a long 
period of time by preventing all vibration in and about them. In 
the experiments of Mr. Eocbling, engineer of the Niagara Suspen- 
sion Bridge, bars drawn down to f inch square at the centre, and 
having an ultimate tenacity of 33 tons per square inch, bore a 
strain of 20J tons per square inch without visibly stretching, for a 
week, when no jar was given to them. Upon any vibration, they 
immediately took a permanent set. The above specimens, how- 
ever, w 'ere permanently loaded and then jarred. 

347. EFFECT OF DIFFERENT RATES OF APPLICATION OF FOKCE. 
This is illustrated by Fig. 159. 




I P I 



Let the elastic body a I be firmly 

secured in the wall W, and the 

weight P slowly placed upon 

the end &, which will thus be de- 

pressed to P' , the point where 

the resistance w T ill equal the 

weight. But if the weight 

being placed in contact with & but not resting upon it, is suddenly 

let go, the weight will exceed the resistance until P' is reached, 

after which the momentum acquired by the total weight (P and 

1)) will depress I to /*", but with a constantly diminishing velocity, 

because the resistance will then exceed the weight. If the elasti- 

O 

city is perfect, and there is no atmospheric resistance, P" will be 
twice as low as P. From P n ', the elastic force being in excess, 
the weight will again rise to ?>, 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. <f 


6f 


046 


6f 


.044 


I 


i* 


068 


i*| 


064 


In mot-chamber, original diameter, 4.825 in. -I 


W 


095 

374 


Hi 


087 
.314 



The gun was rifled like the Armftrong 4<D-pounder. It fired 100 rounds with the fer- 
vice charge of 5 Ibs., and cylinders increafing in weight from 40 to 400 Ibs.} alfo 17 
double fervice charges of 10 Ibs., and a 4<D-lb. mot. 

The bore is alfo deeply filTured all round from 75 inches from the muzzle to the end of 
the powder-chamber. 



4O5. This is the principal objection raised in England against 
wrought iron. It may become a serious defect under the high 
pressures which future guns will have to endure. 

But this indentation of the iron decreases its thickness and in- 
creases its length, that is, draws it as under a hammer. As far 
as this is done, without reducing its strength, the result, in a solid- 



344 ORDNANCE. 

forged gun, without initial strains, is undoubtedly beneficial, be- 
cause it tends to put the interior metal into compression, and the 
exterior metal into tension, so that both will be more equally 
strained at the instant of firing (287). But if the proper initial 
strains have already been adjusted, as in a hooped gun, the en- 
largement of the interior metal by pressure or heat tends to 
derange them, and to weaken the gun. As to the compression, 
Mr. Anderson says* that after a time the iron becomes set and 
does not farther enlarge, and that " it becomes very hard after a 
little." It therefore becomes more like steel, and is better able to 
resist the wear of the projectile. 

406. The hardness of metals their resistance to abrasion such 
as the wear of projectiles approximates to their resistance to 
compression. The average hardness of steel is highest, and that 
of wrought iron lowest. Cast iron is so well adapted for this pur- 
pose, as to fire 1000 rifle projectiles without sensible injury (80). 
The wearing down of the grooving in wrought-iron guns is not of 
unfrequent occurrence. This result is aggravated by the com- 
parative purity of the material and its greater corrosion by the 
powder-gas. In case of coils, the eifects of this corrosion, and of 
oxidation when the gun is damp, are observed in the form of 
minute grooves running with the grain of the iron. The Arm- 
strong multigroove rifling crosses these nearly at right angles, so 
that the bore, thus acted upon, would present a surface of minute 
ridges and spikes. But steel and cast iron are not grooved or far- 
rowed by corrosion ; they are smoothly and evenly reduced. 

407. WANT OF HOMOGENEITY. The grand defect of wrought 
iron is, that it is not homogeneous. The puddling process by 
which it is produced, the piling process by which large masses are 
aggregated, and the welding process by which all parts, large and 
small, are united, are all the means of interposing strata of impu- 
rities and planes of weakness. 

408. WELDS. Wrought iron cannot be produced from the 
pig-metal in larger masses than puddle-balls weighing from 200 

* "Journal of the Royal United Service Institution," August, 1862. 



WROUGHT IRON. 345 

to 300 Ibs. Before these can be brought together, to be welded 
into a bloom, the surfaces oxidize and prevent a perfect union. 
Large masses are formed by welding small pieces to the end of a 
bar ; the entire surface of each piece being exposed to oxidation. 
It is also difficult to prevent the enclosing of cinder in some points 
instead of squeezing it out. Small welds, made under a hand-ham- 
mer, with a uniform heat, are, of course, much better ; and these are 
weaker than the solid bar. Mr. Anderson* found that two bars 
of the finest quality of iron, properly heated in a fire free from 
impurities, could be welded together in such a manner as to be as 
strong as the solid bar (56000 Ibs.) only by scarfing them, and so 
increasing the surface that the welded area was much larger than 
the fractured area. 

"With all other descriptions of welding," says Mr. Anderson, 
" which I have yet tested, the result is lower than the above, down 
even to 12000 Ibs. per square inch, the same care having been 
observed in every instance. Two pieces of the best quality of iron 
butted together, under the best conditions which I have been able 
to effect up to the present time, have only given an average ulti- 
mate tenacity of 32140 Ibs. per square inch, which is only a little 
over the half of the iron bar. 

" Iron butt welded to steel under the best conditions invariably 
breaks at the weld, and shows only an average tenacity of 26800 
Ibs. But even this depends entirely on the nature of the iron and 
steel ; any increase of hardness, or of the steely property, either in 
the iron or in the steel, affects the strength of the weld in many 
cases down to 10000 Ibs., and even still lower. 

" In the construction of the Armstrong guns, the bar iron is 
first wound into a spiral coil, and then a welding heat is taken 
through the entire mass, and by means of a steam hammer it is 
welded into a homogeneous cylinder. With iron of the very best 
quality which we have as yet been able to obtain, the highest 
average tenacity of the welding of the coil has been 32140 Ibs. 
per square inch, the iron being 55500 Ibs. 

* "Journal of the Royal United Service Institution," August, 1862. 



346 ORDNANCE. 

" With other iron, also of a high quality and of a still greater 
tenacity, the welds have been lower down, even to 10000 Ibs. per 
inch ; hence such iron, however strong, is, from the steely prop- 
erty, unsuitable for being made into coils ; the defect being due 
to the reluctance shown by harder and stronger iron to unite when 
raised to a temperature that will not otherwise injure the quality 
of the material, and cause it to blister." 

Mr. Kirkaldy concludes* that " a great variation exists in the 
strength of iron bars which have been cut and welded ; whilst 
some bear almost as much as the uncut bar, the strength of others 
is reduced fully a third." 

4OO. SHAPE. A solid-forged gun may be turned down to the 
Dahlgreii form (see Ames's gun, 129), so as to have the greatest 
strength with the least weight. The cost of this operation, 
although considerable, is much less than that of turning the rings 
of a built-up gun, without and within. 

41O. The outline of a hooped gun is almost necessarily a series 
of sharp curves and right angles. The weakness already explained, 
of cast-iron guns with re-entering angles, is obviously due to the 
process of casting, and would not apply to a built-up gun. It is 
well known, however, especially in the case of railway axles, that 
a sharp shoulder turned in a bar of iron or steel subjected to con- 
tinuous shocks, is a source of weakness, and the almost certain 
starting point of a fracture. So far as the fracture arises from the 
unequal vibration of the adjacent parts, there would appear to be 
no difference between forming these shoulders by turning a large 
bar down to different diameters, and building a small bar up to 
the same diameters by shrinking on rings. A railway axle is a 
beam, and the staves of which a cannon may be supposed to con- 
sist are beams, and therefore subject to the same sources of weak- 
ness. Still, the practice with wrought-iron guns does not yet 
appear to have demonstrated any particular tendency to fracture 
at the junction of a larger with a smaller cylinder. Perhaps the 
large guns thus constructed have shown a tendency to fail in other 

* " Experiments on Wrought Iron and Steel," 1862. 



WROUGHT IRON. 347 

places before there was time for this source of failure to develop 
itself. The reinforce of the Parrott 100-pounder is 6-4 inches lar- 
ger in diameter than the cast-iron barrel within it, and hence 
vibrates much more slowly under a given shock ; and it joins the 
barrel at a sharp angle. "No fracture occurred at this junction or 
elsewhere, after 1000 rounds with service charges ; and it is stated 
by Captain Parrott, that the few guns of his that have burst did 
not fail at this point. (See note in Appendix.) 

411. WEIGHT. The saving of weight by substituting wrought 
for cast iron, is theoretically about in proportion to the respective 
strength of the two materials. Wrought iron has the greater spe- 
cific gravity ; on the other hand, its tensile strength does not fully 
measure its resistance to internal pressure. Practically, large, 
solid wrought-iron guns are not proportioned by this rule, because 
the strength of a bar cannot be relied on in a gun that is to say, 
the process of welding a strong metal is rather less trustworthy 
than that of casting a weaker one. The 13-inch Horsfall wrought- 
iron gun carries a 279 Ib. shot with 74 Ibs. of powder. The 15-inch 
Rodman cast-iron gun carries a 425 Ib. shot with 60 Ibs. of powder. 
So that the strains on these guns cannot differ in a very great 
degree. The former, with a tensile strength of 50000 Ibs., weighs 
53846 Ibs., while the latter, with a tensile strength of say 30000 
Ibs., only weighs 49100 Ibs. The Alfred 10-in. wrought-iron gun 
weighs 24094 Ibs, and has been fired only with 20 and 30 pounds 
of powder, although it is undoubtedly competent to stand 50 Ib. 
service charges. The new 10 inch cast-iron Dahlgren gun weighs 
less than 20000 Ibs., and for some time stood 47 Ib. service charges. 
The 10-inch Rodman army gun weighs 15059 Ibs., and burns 18 
Ibs. of powder. In the built-up form, wrought iron is more trust- 
worthy, and can be made lighter, although weight is not reduced 
in proportion to tensile strength in the smaller Armstrong guns. 

This source of embarrassment is avoided by the use of cast steel, 
which is not only stronger than wrought iron, but homogeneous 
and without welds. 

41SJ. COST. The cost of large wrought-iron cannon is about 
double that of cast-iron cannon of the same calibre, or of the same 



348 ORDNANCE. 

power, when (because welds cannot be trusted) equal weights of 
material are used in both cases. (See Table 27 of Cost of Guns.) 

In fabricating guns, the first necessity is the production of a 
large mass of material. While melted cast iron and steel run into 
castings of any size by their own gravity, wrought iron is not melted 
at a practicable heat, so that a new process must be resorted to. If 
the gun is forged solid, the process consists in adding a little at a 
time under the hammer, and trimming off a great deal of scrap. 
Seven weeks were occupied in forging the Horsfall gun. If the 
gun is built-up, small pieces are fitted together by tools, at a still 
greater cost. When all this is done, it is not homogeneous. 

Refining and strengthening the material is substantially a sepa- 
rate operation. Steel is drawn and condensed after the mass has 
been formed ; wrought iron, before. The inventions of Bessemer 
and others are constantly reducing the cost of forming steel masses 
from the pig-metal, by substituting chemical processes that require 
very little aid from hands or tools.* 

413. Sytenis of Fabricating Wroiiglit-Iron Oun. SOLID 
FORGING. The defects of this process have been alluded to. The 
first and most serious is the liability to imperfect welds between 
the great number of pieces. Were the pieces fitted to each 
other, uniformly heated, and sufficiently pressed together, the 
welds between raw iron, after a large amount of subsequent com- 
pression would be good. It has been found that large pieces of 
refined iron do not weld soundly by the rolling or forging process. 
Old railway rails of the finest quality when re- rolled into new rails 
without a large admixture of raw iron, are usually very unsound. 
There does not appear to be either cinder or pressure enough to 
insure a thorough union. f The blacksmith makes an artificial 
cinder to unite refined irons, and the compression from the blow 
of his hammer is greater in proportion to the mass, than that of 

* Low steel, formed by carbonizing wrought iron or by decarbonizing pig iron by 
the Bessemer process, is often called wrought iron, because it is not hard like high 
steel. But it much more closely resembles high steel than wrought iron. Low steel 
produced by the puddling process may be more reasonably called high wrought 
iron. 

f "European Railways," Colburn & Ilolley, 1858. 



WROUGHT IRON. 349 

the machinery employed for heavy work. He can also be very 
exact about his heats. Cast iron has the maximum amount of 
cinder ; two pieces of it, heated to welding, that is, to the melting 
point, unite perfectly. Two raw puddle-balls weld soundly, 
although the mass would be weak throughout in the absence of 
farther drawing. 

Mr. Roebling* refers to the same subject, in stating his inge- 
nious theory to account for the weakening of wrought-iron struc- 
tures under vibration viz. : the loosening of the iron threads and 
lammse in their cinder envelopes. 

414. The importance of forming the mass before the iron is 
purified and the cinder expelled, is therefore evident. Puddle- 
balls cannot well be handled if above 300 or 400 Ibs. weight. 
If 100 of these could be forged at once into a mass, and after- 
wards worked into a gun in such a way as to expel the then super- 
fluous cinder, the product would be more homogeneous and trust- 
worthy. 

415. The slabs or bars of which a large gun-forging is com- 
posed, are not fitted beforehand. The flat sides of two slabs may 
be soundly welded, but the irregular edges and ends do not always 
happen to be pressed together hard enough to make sound work ; 
so that there are scarf-welds, butt-welds, and no welds, or, rather, 
seams between parts that either do not touch at all, or are only 
stuck together by cinder (426). The tendency ol the drawing 
process under the hammer or the rolls is to squeeze out cinder. 
But if the edges of a slab happen to be united to the mass before the 
centre, an excess of cinder is shut in and prevents a farther union 
of the metal. Large cavities are sometimes left in such forgings. 
If the forgings are farther drawn, under the hammer or rolls, these 
cavities are not only flattened into long, wide seams, but the seams 
run in the direction of the grain, thus weakening a gun at the 
point most strained by internal pressure. 

416. The welding temperature of various irons is not always 
the same. One part may be burned before another is sufficiently 

* "The Engineer," London, Jan. 25, 1861. 



850 ORDNANCE. 

softened. Or, the small slabs may receive much more heat from 
the fire than the large mass. Mr. Clay, of the Mersey Steel and 
Iron Works, says on this point,* speaking of scrap-iron, that vari- 
ous qualities of iron all have their own special welding points. 
" When worked together, one portion that is less refined is too 
much heated, and consequently deteriorated, before the more 
highly refined portions are at a welding heat, and we are thus 
placed in the awkward dilemma of either burning the one or of 
being unable to weld the other." 

417. By the solid-forging process a great body of iron is kept 
red hot or white hot for weeks. The Committee of the Franklin 
Institute, in a report on the failure of the United States frigate 
Princetons wrought-iron gun (426), mention this as a cause of 
weakness. Mr. Longridge, however, dissents from this view of 
the case,f inasmuch as he does not believe that long exposure to 
heat alone will deteriorate the iron, nor that any amount of ham- 
mering will restore its fibre." Mr. Kirkaldy's conclusion on this 
subject is, that " iron is injured by being brought to a white or 
welding heat, if not at the same time hammered or rolled." 4 * The 
finished part of a large forging is kept at a high heat without be- 
ing again brought under the hammer. 

The defect under consideration is admitted by Mr. Clay, who 
says :f " The change in the structure of a mass of iron, when it 
occurs during the process of heating, is usually produced from the 
furnace being urged to a much greater heat than is necessary for 
welding the iron ; in fact, the outside first, and, if the heat be not 
checked, the whole of the mass is reduced to a pasty or partially 
fluid condition. The structure of the iron is thus entirely changed, 
and in the process of cooling the mass, crystallization takes place 
in the same manner as with other substances which crystallize in 
passing from the fluid to the solid state. Under these circum- 
stances the iron may be injured in other words, it may be burned ; 
but we are not to suppose that such a result is either inevitable or 

* "Experiments on Wrought Iron and Steel." Kirkaldy, 1862. 
f "Construction of Artillery," Inst. Civil Engineers, 1860. 



WROUGHT IRON. 351 

by any means common ; on the contrary, the heat necessary to 
produce the evil is with difficulty obtained in an ordinary furnace, 
under the most favorable circumstances." 

418. The grain of the iron, in a solid-forged gun, runs in the 
wrong direction. The greatest strain acts in a radial direction. 
The greatest strength is in a longitudinal direction. The mean 
breaking strain of six pieces cut lengthways from a heavy crank- 
shaft* was found by Mr. Kirkaldy to be 47582 Ibs. ; from another 
crank-shaft, 43579 Ibs. The breaking strain of six pieces cut cross- 
ways from the first shaft was 44578 Ibs. ; .from the other, 38487 
Ibs. The difference in favor of those cut lengthways was in the 
two shafts respectively, 3004 and 5272 Ibs., or 6*7 and 13'7 per 
cent. Similar results were observed from iron cut lengthways and 
crossways from an armor-plate. 

The experiments of Mr. Mallet on " The Coefficients of Elasticity 
and Rupture in Massive Forgings,"f show that " as regards rela- 
tive resistance to tension in different directions within the same 
large mass of forged iron of cylindrical form, and within the elas- 
tic limits, the resistance end on, or in the line of the axis, is 10^- 
tons, tangential to the circumference, 6 tons, and transverse to the 
axis, or in any diameter, 3J tons per square inch ; while in heavy 
rectangular forged slabs of upward of 12 inches in thickness in 
the plane of the slab, it rises to 8| tons per square inch for equal 
sections." Mr. Mallet attributes the difference in strength to the 
difference in molecular arrangement. " The integral crystals of 
the cylindrical masses are strained, distorted, and partially sepa- 
rated, by the effects of hammering in various directions, and by 
the peculiar constraining forces due to contraction in cooling. 
None of these forces act to the same extent upon rectangular 
masses, which are only hammered in two directions, and the con- 
straining forces of cooling are all parallel to the faces of the paral- 
lelopiped, or in these directions also." 

419. Another defect in the usual process of forging wrought- 

* "Experiments on "Wrought Iron and Steel," 1862. 

f Paper before the Institution of Civil Engineers, March, 1859, 



352 ORDNANCE. 

iron guns is due to the light blows of small hammers, which 
compress only the shell of the mass, and are not felt at its centre. 
Steamboat shafts thus made prove defective; but the results are 
peculiarly bad in the case of guns. 

First. Only the skin of the iron is soundly worked and con- 
densed. It was ascertained by Mr. Kirkaldy* that the difference 
in the breaking strain between specimens cut from the outside of 
a marine crank-shaft, and specimens cut from its centre, was, in 
one case, 3221 Ibs., or 6'5 per cent.; in another case 1141 Ibs., or 
2'6 per cent. 

Second. The outer part of the forging is sometimes expanded 
and thus drawn away from the centre, leaving the interior weak- 
ened, or actually cracked the exact state of a solid-cast gun. 

Third. The inner part of the gun is left in tension while the 
outer part is in compression, which is the opposite state of strain 
to that required. This defect, however, is the result of inadequate 
machinery, and does not necessarily follow the use of wrought 
iron, or even of solid-forged masses of wrought iron. 

Mr. Clay testified as follows before the Defence Commission- 
ers^ in answer to the inquiry if the limit of manufacture was 
not reached: u Certainly not with our present machinery. We 
made that 13-inch gun with machinery as inferior to our present 
machinery as the 68-pourider is less in size than the 13-inch gun. 
We have now machinery five or six times as powerful." 

4!sJO. The initial strains of large cylindrical forgings are to 
some extent deranged by a cause that operates so unfavorably in 
solid cast-iron guns the cooling of the exterior first, and the 
consequent stretching of the interior (364). Mr. Clay acknowl- 
edged this difficulty before the Defence Commissioners, and stated 
that his new process hollow forging overcame it (429). Such 
a result actually occurred in the case of the Horsfall gun (113). 
A breech-plug or false bottom was placed in the chamber, to 
cover a crack arising from this cause. 

* "Experiments on Wrought Iron and Steei," 1862. 
f "Report of the Defence Commissioners," 1862. 



WROUGHT IRON. 



353 



FIG. 166. 




Forging for Mallet's mortar-chamber. 



Mr. Mallet, in the paper before referred to,* gives the following 
facts and illustrations as to 
this cause of failure. Two 
masses, about 2J ft. in di- ^==== < -7-' 0^'- _> 

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. 



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WROUGHT-!RON GUNS. 



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374 



ORDNANCE. 



TABLE LXY. LIST OF ARMSTRONG GUNS RENDERED UNSERVICEABLE BY PROVING 

VENT-PIECES. 

(From the Report of the Select Committee on Ordnance, 1863.) 



Nature. 


Where 
made. 


No. of 
Gun. 


'roof charge =2 service charges. 
Proof rounds fired. 


Remarks. 


6-pdr... 


R. G. F. 


36 


9 




9-pdr... 


" 




None rendered unserviceable. 




12-pdr... 







Ditto ditto. 




20-pdr... 







' Ditto ditto 




4O-pdr... 


E. O. C. 


17 


460 




4o-pdr... 


" 


147 


369 




4o-pdr... 


" 


166 


1050 




40-pdr... 





184 


144 




40-pdr... 
I xo-pdr... 
Iio-pdr... 


it 

R. G. F. 


53 
17 
'35 


135 
'5 
309 


C Cracked, after 200 rounds, 
-< on board her Majesty's ship 
( Hero, and not repaired. 


lio-pdr... 


" 


657 


247 




I lO-pdr... 


" 


663 


357 




HO-pdr... 
IIO-pdr... 
I lO-pdr... 


E. 0. C. 
tt 


683 
28 
143 


261 

313 

27 


C Previously tested with loo 
< rounds for endurance, with 
(shot up to 1000 Ibs. 


uo-pdr.. 


" 


191 


119 





. Sir William Armstrong considers his system very superior 
to other systems* of construction, because inventors of projectiles, 
rifling, etc., who want strong guns, always avail themselves of it 
by applying to have their guns made at Woolwich. The fact is, 
however, that no other system accessible to them has been devel- 
oped. The following evidence of Mr. Whitworth* touches this 
point very fairly : 



* Select Committee on Ordnance, 1863. 



WROUGHT IRON. 375 

Q. " Do you think the system of manufacture under Sir Wil- 
liam Armstrong's principle is right or wrong ?" 

A. "I believe it is utterly wrong." 

Q. " Then why did you avail yourself of it ?" 

A. " Because I was desirous to show that I could and I think 
that I could send a shell through armor-plates, and there was 
no other way in which I could get the gun made with a 7-inch 
bore, weighing 7 tons, except at Woolwich. I am convinced 
that no large gun made of welded iron will stand. I utterly con- 
demn welded iron in a gun at all, either for the inner tube or for 
the coil." 

But the injury of that very gun, in the manner indicated 
by Mr. Whitworth, after less than 30 rounds, is more conclusive 
evidence against the system. The 9-inch gun made on the 
same plan at Woolwich, for Mr. Lynall Thomas (34), has fired 
but very few rounds. The first 10-|-inch Armstrong muzzle- 
loader has burst twice after a short service (446). 

44. It is mentioned, as an advantage of the Armstrong sys- 
tem, that injured guns can be taken apart and repaired in detail 
(see Table LXIY.), without sacrificing the whole structure, as in 
case of solid guns. But this feature only provides a remedy for 
a defect which it induces this very want of integrity creates 
weakness and hastens failure. 

443. DEFECTS OF THE SYSTEM. All the guns mentioned in 
Table 64 failed after they were issued for service. That many 
costly failures occur before the guns are issued, is obvious from the 
facts elicited about the 40-pounders, by the Committee on Ord- 
nance, during the session of 1863. Out of 192 guns, 153 had 
been lapped out and otherwise repaired at the cost of $20270 
(4054); 21 of them were bouched throughout at the cost of 
$3701.25 (7405) ; and 25 were bouched with tubes of various 
lengths. Sir William Armstrong said, indeed, that these "are 
questions of manufacture, and not of repair." 

444. The most obvious defect in the Armstrong gun is in the 
material used its softness and consequent yielding under the 
pressure of the powder-gas. Since no other material but wrought 



376 ORDNANCE. 

iron could be welded up in this way, the defect may be fairly 
urged against the system.* 

The evidence of Mr. Anderson and Sir William Armstrong, 
admitting this defect, has already been quoted (402). Some in- 
stances will illustrate the character of the failure. A 6^-in. 
Armstrong gun, tested in comparison with a Mersey solid-forged 
gun, endured 100 rounds with increasing charges, while the 
Mersey gun burst at the 70th round; but at the 60th round the 
Armstrong gun had a cavity 2 '75 in. deep in the chamber. The 
200-pounder side breech-loader bulged at the 7th round. A 110- 
pounder that had fired 127 rounds with 27-J Ibs. of powder, 
and 48 with 14 Ibs., was indented and cracked in the chamber. 
Subsequently, 133 rounds, with 27^ Ibs., parted it near the trun- 
nions. One 110-pounder is reported to have become fractured in 
the chamber, and destroyed in the rifling, after 57 service rounds. 
The 9-in. gun made for Mr. Lynall Thomas on this plan, as well 
as the 7-in. gun made for Mr. Whitworth, have permanently 
changed figure the latter is unfit for regular service after less 
than 30 rounds. The first 10^-in. gun was indented in the cham- 
ber with a 90-lb. charge (446), and a round 150-lb. ball.f 

All the Armstrong guns are left smaller in the bore than the 
finished size, to allow for expansion in proof and they all expand 
in proof, the 110-pounders in a considerable and irregular degree. 

i 1 .7. The small amount of " work done" in slightly stretching 
wrought iron its great ductility allows the hoops of the Arm- 
strong gun to relax. In several instances the inner tubes have 
failed, while the outer ones have remained whole. 

In view of the facility with which the outer hoops can stretch, 
their fracture, several instances of which are mentioned in the Re- 
port of the Select Committee on Ordnance (1863), must be traced to 
those effects of vibration which are due to want of continuity of 
substance (335). Table (LXIY.) has many examples of both kinds 
of failure. But they are sooner developed in the larger ordnance. 

* According to the evidence of Mr. Anderson (" Report of Committee on Ord- 
nance," 1862), the harder kinds of irons weld badly, so that the coils split. 

f- The chamber of the GOO-pr. became oval, and the inner tube started after " a 
dozen or twenty rounds." Capt. Fishbourne, Jour. R. U. Service Inst, Maij, 1864. 



WROUGHT IRON. 



. 377 



446. The first lOf-in. smooth- 
bore (Fig. 177) burst after firing 264 
spherical shot, with 40-lb. charges, 
in nearly all cases, there were sev- 
eral of 50 Ibs., and as the gun had 
never been proved, one of 70, one 
of 80, and one of 90 Ibs. The lat- 
ter charge was not considered as 
excessive, but only equivalent, with 
a spherical shot, to 50 Ibs. with the 
300-lb. elongated shot that the gun 
was intended to carry when rifled. 
Other guns of this class have fired 
300-lb. shot. At the discharge with 
70 Ibs. of powder, the inner coil 
split in the spiral weld; at the next 
round, with 80 Ibs., this crack closed 
and another opened parallel and 
near to it. The next round, with 
the 90-lbs. charge, made a crack 
parallel to the bore, in the outer 
coil, behind the trunnions. After 
a few rounds more, the breech-piece 
pulled apart, as shown by the dotted 
lines a <?, and blew out. Fig. 178 
shows the condition of the gun after 
fracture. This result was undoubt- 
edly hastened by the gas leaking 
past the movable bottom F of the 
chamber, and the copper disk a a, and 
pressing upon the larger area of the 
screw-plug G* 



* It is worthy of note that the same construc- 
tion was adopted for the new guns made at 
Elswick. Mr. Anderson's were made with a 
solidly-closed inner tube (32). 




378 . ORDNANCE. 

This gun* having been repaired, one of the outer tubes cracked 
again, rendering the gun unserviceable after a few rounds with 



FIG. 178. 




First Armstrong lOi-inch gun, after the breech blew out. From a photograph. 

50 Ibs. of powder and a round ball. And the new lOJ-in. guns 
that have been rifled show such limited endurance that the charge 
with an elongated shot has been reduced from 50 to 45, and then 
to 35 Ibs. One of them was fractured in the chase, at the 8th 
round, by the sudden nipping of the shunt-shot. 

447 The following is the report of the Ordnance Select Com- 
mittee on the failure of the 120-pounder shunt gun :f " The Com- 
mittee have the honor to report, for the information of the 
Secretary of State, that the 120-pounder muzzle-loading shunt 
gun, which they were authorized to fire with shot reduced to 100 
Ibs. weight, and a charge of one-fourth, gave way in the trunnion 

* With regard to the bursting of this gun. Mr. Anderson said, before the Select Com- 
mittee on Ordnance, 1862, that "to provide for any escape of gas that there might be, 
an annular passage around the gun was left, and in the drawing it was shown with 
an opening to the outside. The workman, in making that opening, drilled a hole into 
another part of the gun, and not into the passage, and hence, when the leakage arose, 
the pressure was exerted over a very much larger surface; there being no vent 
through the solid part, hence the pressure came upon nearly a double area." 

f " Report of the Select Committee on Ordnance," 18G3. 



WKOUGHT IRON. 379 

coil at the second round, and is at present unserviceable. The 
actual weight of the shot fired was only 98 Ibs., and the charge 
24 Ibs. The gun having been fired with impunity, by the Iron 
Plate Committee, with shot of 140 Ibs., and a charge of 20 Ibs., 
this accident cannot be attributed to the severity of the charge. 
It has fired, altogether, 103 rounds, and the present failure must 
either be traceable to a weakness originally stated by Sir William 
Armstrong to exist in it, or be the consequence of using the pow- 
der known as 2 A 4. The Committee do not apprehend the latter 
to be the case ; and the reported position of the crack, which is far 
forward, tends to show that a flaw must have existed, because the 
force of the powder would be diminished by expansion to less 
than one-half its original amount before it could operate on that 
part of the structure." 

Perhaps the sudden blow of the shunt-shot as it centred in 
that part of the bore, and the various effects of vibration, would 
account for this failure, since one of the 300-pounders gave way in 
a similar place. 

448. Charges of 25 Ibs. of powder are said to have rapidly 
destroyed 110-pounders. The service charge (for shot) for these 
guns has been reduced from 14 to 12 Ibs. 

The effect of multiplying parts is shown by the failure of 
bouched guns, about which much testimony was taken by the 
Select Committee on Ordnance, during the session of 1863. 

Nearly all the old pattern 12-pounders were found too weak, and 
are being altered by having 12 in. cut off from the muzzle, and a 
heavier and longer coil placed in front of the trunnions. 

The character of these failures a general loosening and shaking 
to pieces of the gun after short service although aggravated by 
the softness and extreme ductility of the metal, must be traced, in 
a great degree, to want of mass and continuity of parts. 

449. Although the welds are in the direction of least strain, 
the splitting of the inner coil is admitted by Mr. Anderson and 
others, in the evidence before the Select Committee on Ordnance 
(1863), to be of frequent occurrence.* 

* In discussing this subject in December, 1861, before the United Service Insti- 



380 ORDNANCE. 

As to the welds, Mr. Anderson says :* "With iron of the very 
best quality which we have as yet been able to obtain, the highest 
average tenacity of the welding of the coil has been 32140 Ibs. 
per square inch, the iron being 55500 Ibs. * * * It will thus 
be seen that the ultimate strength of a coil in the circumferential 
direction, is about 55000 Ibs. per inch, while in that of its length 
it is only 32 140 Ibs. per inch." 

4*5O. The following defect is mentioned by Captain Fish- 
bourne, f " The coils are shrunk on hot ; the metal of Course con- 
tracts in every direction, consequently the joints open ; it were 
impossible they should .be close ; the overlapping pieces at the 
joints indicate the knowledge of this defect. All these are points 
of weakness, and the whole of the great vibration which takes 
place every time the gun is fired, must be thrown in turn on these 
separate parts, and not distributed, owing to the continuity being 
broken, which must lead early to the disintegration of the gun." 

1*71 . Another possible disaster, serious, perhaps, but not very 
likely to occur in case of guns wholly inclosed in turrets or case- 
mates, is damage from the blows of shot or flying pieces of armor. 
' This was shown," says Commander Scott,f " in the experiment 
of firing with a 9-pounder smooth-bore brass field-piece, at a rifled 
12-pounder coiled gun, and also at a 9-pounder brass gun. The 
charges were very much reduced, so as to resemble the effect of 
distant firing." In this trial the 12-pounder was broken to pieces 
in 3 rounds, each blow being alone sufficient to disable it ; while the 

tution, Commander Scott said : " The coils of which the gun is made, though ex- 
ceedingly strong to resist direct internal pressure, often show flaws after firing ; * * 
the coils are also liable to separate. This was shown by the 100-pounder which was 
returned from Shoeburyness, badly cracked in the inner tube of the breech, and in 
another gun, also sent back on account of a similar flaw in a similar part. It was 
also equally apparent in the 12-pounder which failed and became wholly disabled in 
ordinary practice at Shoeburyness. * * * The separation of coils has frequently 
happened 'in proof with both 40 and 100-pounders, and also took place with one 120- 
pounder shunt, and may be expected to happen on service from the concussion and 
friction resulting from the jar before the leaded shot starts, and the strain of driving it 
through a hole of smaller diameter than itself." 

* Jour. Royal U. Service Inst., Aug., 1862. 

f Jour. Royal U. Service Inst., June, 1862. 
. Royal U. Service Inst., Dec., 1861. 



WROUGHT IRON. 381 

9-pounder, after receiving the same number of shots on one side, 
sustained a similar discharge against the other, and remained still 
serviceable for discharging grape, case, or 6-lb. round balls. In 
fact, but for one blow on the thinnest part of the chase, the gun 
could have continued to fire its usual ammunition ; and while the 
broken breech-loader would have perhaps not been worth removal 
from the field of battle, the brass gun could have been made as 
serviceable as ever in a couple of hours." 

452. With reference to the necessity of employing this system 
for very large guns, Mr. Anderson said, before the Defence Com- 
mission in 1862, that " building the gun up with portions of the 
iron one above the other," appeared to be " the only ready way 
of constructing enormous guns, and getting them absolutely per-, 
feet when made ;" and that upon consultation with others, he had 
determined that 24-inch guns could be made, but at a very con- 
siderable expense. He said that the great difficulty of manufac- 
ture was in handling such enormous masses, but that he had been 
devising arrangements "to make men into giants, as it were. 
* * ~ x ~ You want an arrangement that would enable a man or two 
to manipulate those great things readily without going near them." 
1,KI. The success of the system certainly depends upon the 
use of costly machinery; audits development from the beginning 
has been chiefly a matter of money. The difficulties to be over- 
come were numerous and formidable. The proper joining of the 
rings at their ends, the proportioning of the breech-piece to the 
requisite longitudinal strength, the adjustment of the hoops to 
give the necessary initial tension, and the general elasticity of the 
whole structure under fire, involved so much costly experiment, 
that access to the Government purse was an important, if not an 
essential condition, of the final production of the present Arm- 
strong gun. If the still larger sums which have been expended 
on a bad system of rifling, and an unnecessary system of breech- 
loading, had been devoted to the adaptation of low steel, from 
which Mr. Anderson, with all his preferences for iron, evidently 
expects great results the Armstrong gun would probably have 
been far more formidable. 



382 ORDNANCE. 

454. WELDING. The hardest and toughest wrought iron 
such as that used by Captain Parrott for reinforcing cast-iron guns 
may indeed be indented and stretched by the heaviest charges ; 
but its chief defect, when welded into masses of sufficient size to 
avoid the destructive effects of vibration (335), is in the imperfect 
adhesion of necessarily small pieces (415). 

Nor is the objection to welds that is to say, to the uniting of 
parts that once were separate. Indeed, the ultimate atoms of 
matter are not supposed to be in absolute contact with each other. 
They are kept at a certain distance apart by heat, and held from 
further separation by the attraction of cohesion. When they are 
violently separated, beyond the range of cohesion, they cannot be 
again perfectly united until they are brought within their original 
distances from each other. When so brought together, hot or cold, 
the old antagonism of forces will ensue. Heat is only a convenient 
means of restoring the distance between the atoms, because it allows 
them to move among themselves, and to adjust themselves by 
gravity, when a melting heat is reached, and by slight pressure 
when only a softening heat is attained. Cast iron, cast steel, and 
bronze, may be welded at a melting heat ; but although wrought 
iron cannot be melted at a practicable heat, every iron- worker 
knows that it can be treated so as to have as much strength at the 
weld as elsewhere, and sometimes more strength, because the iron 
at this point is better worked. 

4*>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 {() 

o<?) 


39 4 
322 6 


5*997 
7.660 


96-000 


Steel, Soft German ... 


110393 


40 


968-4 


16.988 


103.500 



film of equal thickness will have been dissolved. But a piece of 
puddled iron, similarly treated, will be eaten away in irregular 
furrows. Iron, being more nearly pure, is the more corroded 
by the gases of gunpowder, and is therefore roughened, and thus 
more rapidly worn by the projectile, besides increasing its friction 
and the strain on the gun. 

483. STRAINS ON A HOMOGENEOUS TUBE. A solid steel gun, or 
any solid tube, as left by the forging or annealing process, is ob- 
viously deprived of one element of strength possessed by built-up 
guns the increased tension or the decreased elasticity of its ex- 
ternal layers (287, 320). But this defect becomes less serious as the 
tenacity of the material increases (Fig. 161), and Mr. Krupp con- 
siders that with his material, built-up guns lose more by vibration 



406 ORDNANCE. 

than they gain in resistance to internal pressure. On the other 
hand, Blakely, Whitworth, Anderson, &c., make equally strong 
guns by reinforcing steel tubes with steel in a cheaper form, or 
with a cheaper material than steel. 

There are also various schemes for putting the layers, of which 
a solid gun may be supposed to consist, into the required state of 
initial strain or elasticity. That of Mr. Thomas E. Vickers* 
(Messrs. Naylor, Tickers & Co., Sheffield) is about to be tried, 
and promises the best results. Initial tension obtained on Cap- 
tain Rod man's plan, by casting the gun hollow and cooling it 
from within, would obviously be destroyed by the annealing 
process, which should always follow the casting or forging of a 
steel gun. (See Table 70.) 

483. Methods of producing Steel. PUDDLED STEEL. As 
this product is made in the puddling-furnace, by a modification of 
the puddling process ; and as large solid masses are aggregated only 
by piling and welding, the grand defect of wrought iron want of 



* Extracts from T. E. Ticker's Patent of Dec. 11, 1862- "Improvements in the 
Construction of Ordnance. * * * The object of my invention is to cool the block 
of metal in such a manner as to cause that portion of its section which is nearest to 
the inside of the bore to contract first, the other portions of the section being allowed 
to cool upon it in the order of their respective distances from the axis of the piece. 

"In carrying out my invention, I first roll, hammer, or otherwise form a solid 
block of steel or iron, or other suitable metal or alloy, of the required form, in any 
convenient manner, and I then bore out the solid block of steel, iron, or other suitable 
metal or alloy, to about the required size for the calibre of the piece. "When bored 
out, the block of steel, iron, or other metal or alloy, is to be subjected to heat in a re- 
heating or annealing furnace, and when brought to a heat sufficient to expand the 
crystals in the mass, and while the block of metal is still in the furnace, I introduce 
into the hollow portion of the gun a stream or jet of water, which is continued until 
the gun shall have cooled down entirely. I do not, however, confine myself to the 
use of water alone, but employ other fluids or air, or any material which is capable 
of being passed through the bore of the gun, and which possesses a sufficiently low 
temperature to cool the metal. 

" I also subject to the above process of reheating and cooling from the centre, 
guns that have been cast of steel in a mould made of fire-proof material, and with a 
hollow core. * * * 

" The essential feature of novelty in the present invention, in contradistinction to 
that of cooling molten metal from the inside of the block, as now practised, consists 
in boring, reheating from the inside, metal gun-blocks, made either by casting, rolling, 
or forging the same, or of reheating and cooling from the inside, gun-blocks that have 
been made with a hollow core." 



STEEL. 407 

homogeneity is not avoided. It is, however, a much stronger 
material than wrought iron. The tensile strength of the best 
averages about 90000 Ibs. per square inch, the best iron averag- 
ing about 60000 Ibs. In small masses, it is now produced by 
Messrs. Comings & Winslow, Troy, N. Y., and at the Mersey 
Iron Works, Liverpool, of a very uniform quality, especially in 
its lower or mild form. But it has considerably less ductility than 
the low cast steels. (Table 68.) 

The process of making puddled steel may be described, in a 
general way, as follows: Cast iron contains from 3 to 5 per cent, 
of carbon ; ordinary steel contains from | to 1 per cent, of car- 
bon ; while wrought iron contains but a trace. In changing from 
cast to wrought iron, in a puddling-furnace, the pig-metal passes 
through the state of steel that is to say, it is steel before it is 
wrought iron. Now, making puddled steel is simply stopping 
the common puddling process just at the moment when the 
decarbonizing mass under treatment is in the state of steel. 
Several modifications in furnaces and processes have been pat- 
ented. Usually, a higher heat than that necessary for iron ma- 
king is employed, in what is termed a boiling-furnace. Yarious 
fluxes, especially manganese, are differently used by different 
manufacturers. 

484. Low CRUCIBLE STEEL OR HOMOGENEOUS METAL.* In its 
general features, the process of making low cast steel is the same 
as that employed for making ordinary cast steel. The chief object 
is to obtain, as the name indicates, a homogeneous iron, which can 
only be done by casting it. Since wrought iron, which has but a 
trace of carbon, cannot be melted at a practicable heat, just enough 
carbon is introduced to render it fluid under the highest tempera- 
ture that the crucibles will stand for one melting. The wrought 
iron is broken into small pieces and put in the pots along with 
5 oz. or 6 oz. of charcoal to every 40 Ibs. of metal.f The great 



* The latter name was first introduced because consumers did not believe in any 
thing that went by the name of steel, for guns and large masses, 
f London Engineer, May 2, 1862. 



408 ORDNANCE. 

secret of the manufacture is in the selection and mixture of irons, 
and in the pouring of sound ingots. 

Large castings are made by emptying a sufficient number of 50- 
Ib. crucibles into an immense ladle placed over the mbuld^the ladle 
is then tapped from the bottom. The largest (7 tons) and best 
castings made in England by this process, are produced by Messrs. 
Naylor, Vickers & Co. In their new works, now erecting, they 
will be able to cast ingots of 15 tons weight. These ingots will 
be worked by hydraulic presses as well as by hammers. 

The treatment of the solid and hollow ingots has already been 
described (62, 68, 69). 

4:85. KRUPP'S STEEL. This celebrated material is also pro- 
duced by a modification of the ordinary process of making cast 
steel. It is understood that a superior quality of puddled steel is 
broken up, and pieces of similar fracture are selected for melting. 
Four hundred clay crucibles, holding 100 Prussian pounds each, 
are required to make a 20-ton casting.* Mr. Krupp has recently 
introduced the Bessemer process but to what extent the Bessemer 
metal is used for guns, is not known to the public. It has been 
suggested that it is broken up instead of puddled steel for remelt- 
ing. Considering the character of the Bessemer metal as it is first 
produced, especially under the skilful treatment of Mr. Krupp, 
this process would hardly be necessary. 

It is known that the manganesian iron (Spiegeleisen) of the 
country, resembling the Franklinite of New Jersey, is of especial 
value. Great skill in melting and pouring the metal, and particu- 
larly in heating such masses to the centre without burning them 
on the outside, and heavy hammers to condense them to the core, 
are features of obvious importance. Indeed, to this skill, and the 
proper use of manganese, may be traced, to a great extent, the 
success of the manufacture. 

So long as crucibles are employed, the metal can never be very 
cheaply produced. The adoption of Mr. Bessemer's invention, how- 
ever, would indicate that the process will be gradually changed. 

* Practical Mechanics' Journal, Record of the Great Exhibition, 



STEEL. 409 

Among the specimens of Krupp's steel in the Exhibition of 
1862, were the following : 

A 9-in. gun, weighing, finished, 18000 Ibs., forged from a single 
ingot weighing 50000 Ibs. ; a crank-shaft 15 ft. long and 24 in. 
in diameter, weighing 15 J tons (34720 Ibs.), forged from a 25- ton 
ingot ; a double-crank propeller-shaft, 24 ft. long and 15 in. in 
diameter, weighing 11 tons (24640 Ibs.) ; and a screw propeller 
9 ft. in diameter, weighing only 800 Ibs. A forging of 15 tons 
weight, 30 in. wide and IT in. thick, was broken at four places to 
show its quality. A square ingot 8 ft. long and weighing about 
8 tons, was forged down at one end, and broken longitudinally to 
show the fracture of the cast and the hammered metal. An ingot 
8 ft. long and 44 in. in diameter, weighing 20 tons (44800 Ibs.) 
was cut around in the middle and broken under the 40-ton ham- 
mer, presenting just as it was cast, without hammering, an area of 
above 1500 square inches of uniform, fine-grained, homogeneous 
fracture, without seams or cracks. It is proper to mention here, that 
above 40000 railway tires of this material were at that time in 
service all over the world. Some of them have run above 90000 
miles without requiring to be turned One of the engine tires 
exhibited had run 67000 miles on the Eastern Counties Railway, 
without being turned. It had worn down about A in., equally 
over its whole circumference. The extent to which Mr. Krupp's 
cannon have been employed, and the severe tests of some of them, 
have already been mentioned (135). 

A similar kind of steel is made at the Bochum works, in Prussia. 

486. BESSEMER STEEL.* The great value of the Bessemer 
process is, that it produces steel direct from the ore or from the 
pig-iron, in masses of any size, at about the cost of wrought iron. 

The " converting-vessel" (Fig. 185), when large enough to con- 
vert 5 tons at a heat, is about 11 feet high and 7 feet in diameter. 
It is made of plate-iron, and lined with a silicious stone called 
"ganister." In the bottom of the vessel are about 50 small 



* The following account of the Bessemer process is taken from the Practical Mechanics' 
Journal, 'Record of the Great Exhibition of 1862. 



410 



ORDNANCE. 



FIG. 185. 




tuyeres, communicating, through the trunnions, with a blower. 

Most of the establishments where this process is employed, are 

not connected with 
smelting furnaces ; 
so that pig-iron is 
melted for conver- 
sion in a reverbera- 
tory furnace, instead 
of a cupola, to avoid 
contact with any 
sulphur there may 
be in the coal. The 

Front of Bessemer converting-vessel. j ron or igi na lly must 

be as free as possible from sulphur and especially from phos- 
phorus. 

After the converting-vessel is heated, the melted iron is let into 
it, and the blast turned on at a pressure of about 14 Ibs. per square 
inch. The oxygen thus forced in, first unites with the silicium in 
the iron, forming silicic acid. As this burns away, and the heat 
is increased, the oxygen begins to unite with the carbon in the 
iron, which soon increases the heat and rate of combustion until 
the mass rises in a frothy state, presenting a great surface to the 
contact of the air; then the combustion becomes excessively 
intense, producing a series of harmless explosions, and throws out 
liquid slag and a column of white flame. In Sweden, and at some 
of the British establishments, the process is stopped here the 
required decarbonization being determined by the time of its dura- 
tion. In Sheffield, it is usually continued until from the sudden 
dropping of the flame, the iron is known to be quite decarbonized ; 
after which a small amount of pig-iron of known quality, already 
melted in another compartment of the reverberatory furnace, is 
put into the converting-vessel. In a few seconds more the blast 
is shut off; the whole process lasting from 15 to 20 minutes. 

The vessel is then turned on its trunnions so that the metal will 
run out into the ladle G (Fig. 186), on the lever H, which is 
elevated, lowered, and turned round upon the hydraulic cylinder P. 



STEEL. 



411 



FIG. 186. 



By removing a fire-clay plug in the bottom of the ladle, the 
respective cast-iron moulds (K) ranged around it are filled. To 
pour a heavy ingot, several con- 
verting-vessels are thus emptied 
into one mould. 

The whole of the silicium is not 
burned out. Some 5 to 6 ounces 
of it, per ton, are required in 
all steel, to insure solid casting. 
"While the carbon and silicium are 
uniting with the oxygen, some of 
the iron also unites with it, but is 
not absolutely lost, although the 
product is of little value. In 
working English iron in small 
quantities, from 14 to 18 per cent, 
of the iron is thus lost ; with the 
purer Swedish irons, tapped from 
the blast-furnace, the loss is said 
to be but 8$ per cent. 

After the ingots are heated 
some 15 minutes, to soften the <"* Bessemer converting apparatus. 

outside, which has been chilled by the mould, the inside still 
being pasty, they are hammered into cannon or other shapes. 
This steel does not fly to pieces like some other cast steel, 
under this treatment. The interior of the ingot is certain to 
be thoroughly heated an important feature and much fuel 
is saved. 

487. Among the specimens of Bessemer metal in the Exhi- 
bition of 1862, were a 14-in. octagonal ingot broken at one end 
and turned at the other end, to show that the metal was perfectly 
solid. The turned end looked like forged steel. An 18-inch 
ingot, weighing 3136 Ibs., was the 6410th " direct steel" ingot 
made at the works of Messrs. Henry Bessemer & Co. There were 
also exhibited, a double-headed rail, 40 feet long ; a 24-pounder 
and a 32-pounder cannon ; a 250 H. P. crank-shaft, and several 




412 ORDNANCE. 

tires without welds. The specimens, showing the wonderful duc- 
tility of the metal, have bee,n referred to (472). 

The Bessemer process has been adopted, during the last two or 
three years, since its early embarrassments were overcome, with 
such great success, and by so many leading manufacturers in 
England, France, Sweden, Belgium, and other European states, 
that its general substitution for all processes of making either fine 
wrought iron or cheap low steel is now considered certain. At 
one establishment in Sheffield the Atlas Works, Messrs. John 
Brown & Co. two 3-ton vessels have been at work above two 
years, and a pair of 10-ton vessels are now completed, which will 
make the total product of Bessemer metal at these works alone 
over 400 tons per week. 

Messrs. Winslow & Griswold, of Troy, New York, are now 
erecting apparatus for the production of Bessemer steel, under the 
direction of Mr. Bessemer. 

488. ABOUKOFF'S STEEL. The steel now made for guns at 
several establishments in Russia,* on AboukofPs system, is thus 
described in the patent : 

White cast iron 540 Ibs. 

Magnetic ore 108 " 

Arsenic I u 

649 Ibs. 

* "In Russia (the Ural Works) they are producing about twenty guns per month 
(up to 6-in. bore) of cast steel. Mr. Povteeloff, at his large works in Finland, and in 
his smaller works in Petersburg, is also producing smaller guns rapidly ; and that 
gentleman, associated with Colonel Aboukoff and Mr. Kondraftzoff, have a very 
extensive factory, close to Petersburg, nearly ready for producing solid guns of the 
very largest calibre, of steel, made on Aboukoff's system. This factory Mr. Povteeloff 
hopes to start in November. There will be sufficient crucible furnaces in it to enable 
him to cast a block of 1 5 tons ; and the hammer-power intended to be used for reducing 
these masses to shape is a 35-ton one, ordered from Morrison's, of Newcastle, but 
which, from accidents in castings, &c., will not be delivered till the spring of 1864. 
The Government, therefore, are giving Mr. Povteeloff every assistance in their estab- 
lishment at Colpino, to enable him to produce, by January 1st next, a 25-ton hammer, 
on Nasymth's plan, which, with a 15-ton hammer from England, will enable them to 
make 9-in. guns rapidly. The works are on a very large scale, and calculated, in a 
year or so, to produce ten large guns per week. * * * 

" By June, 1864, the Russian Government will have sunk at least a million and a half 
sterling on this system, or rather quality, of steel guns, that is to say, on home-made 
cast-steel guns." Correspondence of the London Engineer, Nov. 20, 1863. 



STEEL. 413 

In the specification of the patent the manipulation is thus de- 
scribed : First melt in the crucible the pig-iron, then add the 
magnetic ore (previously reduced to the size of peas by crushing), 
arid then the arsenic. If it is desirable to improve the quality of 
the steel, iron chippings are added, and the proportions are varied 
as may be required. Thus hard steel is made : White iron, 14 
Ibs. ; chippings, 18 Ibs. ; magnetic ore, 3 Ibs. ; arsenic, 1 oz. Soft 
steel : White iron, 10 Ibs. ; chippings, 22 Ibs. ; magnetic ore, 3 
Ibs. ; arsenic, 1 oz. 

" Mr. Povteeloff, as also Colonel Aboukoff, no doubt possesses 
some secret beyond what is thus given, for they maintain that 
they can cast a portion of a block of steel, and ten hours after 
pour the remainder into the mould, and have a perfectly united 
mass. Our Sheffield manufacturers would do well to ponder on 
this. The steel produced is really very good ; but whether or not 
the uniformity claimed is to be had in making on a large scale 
remains to be seen."* 

489. In France, the Government is understood to be develop- 
ing, at great expense, another method of producing cheap steel, 
viz., in a reverberatory furnace, resembling a puddling furnace ; 
the wrought iron, or puddled steel, is protected from oxygen, sul- 
phur, and other destructive agents, by a covering or bath of cin- 
der, and thus melted and run into moulds without the aid of 
crucibles and of the costly processes usually employed. 

4:90. AMERICAN CAST STEEL. It has been remarked that Messrs. 
Win slow & Griswold, of Troy, New York, are erecting works for 
the production of Bessemer steel, under the direction of Mr. Bes- 
semer. Other manufacturers in the United States are experi- 
menting with various processes of making steel direct from the 
ore, and of improving and cheapening the manufacture generally. 
Such success has attended many of these latter efforts, that 
they deserve more than a passing notice ; but, inasmuch as large 
masses have not yet been produced, and as the products have not 
yet attained to celebrity as cannon-metals, a further reference to 
them w^ould be outside of the scope of this work. 

* Correspondence of The London Engineer, Nov. 20, 1863. 



414 ORDNANCE. 

It should be remarked, however 1st. That the Government 
and the old established iron-firms, with a very few exceptions, 
have not rendered the encouragement to these improvements 
which is warranted by the notorious success of similar improve- 
ments in Europe, and by the importance of the subject. 2d. That 
the Franklinite ores of New Jersey possess, in the greatest abun- 
dance, and in the most remarkable variety of combination, the 
very materials manganese and zinc upon which the success of 
Bessemer, Krupp, and the European steel-makers, so greatly de- 
pends. 

49 1 . Systems of Fabrication. SOLID FOKGING. The grand 
advantage of steel is, that very large masses may be forged 
without welds, and so left homogeneous throughout. And to 
whatever extent hoops may be employed, the inner barrel, or the 
main piece which gives the gun longitudinal strength, must be a 
large and heavy mass of metal. 

The serious defects of the solid-forging process for wrought iron 
have been specified (413 to 421). With one exception, they apply 
to wrought iron only. The use of light hammers would be more 
injurious to steel than to iron. But this is not a fault of either 
material. Good work necessarily implies good and adequate 
tools. 

The drawing down of a heavy ingot for instance, Krupp's in- 
got in the Exhibition, which was 8 feet long and 44 in. in diameter 
requires, first, a uniform heat throughout the mass. To soften 
the centre of such a casting through 22 inches of solid metal, 
without burning the outside, requires a moderate and steady tem- 
perature, maintained for several days. Second. The effect of the 
hammer must be felt at the centre of the mass, instead of being 
confined to the outside. The vis viva of a light blow is absorbed 
in changing the figure of the surface metal. Nor would a very 
rapid stroke from a light hammer answer the purpose. Its effect 
would be local, because the surrounding metal would not have 
time to distribute it. The " grain" of the metal would also be 
broken and distorted, just as a light cannon-shot at high velocity 
shears a hole for itself, in the side of an iron-clad, while a very 



STEEL. 415 

heavy and slow shot racks and drives in the whole structure. A 
great weight, falling from a moderate height, is resisted by the 
whole mass of the forging below and around the place where it 
strikes. For this reason, Mr. Krupp employs a 40-ton hammer, 
which is said to have a fall of 12 feet. The ascertained defects of 
heavy forgings, due to light hammering, are 1st, the interior of 
the metal is not condensed ; 2d, the outer part of the forging is 
expanded, and thus drawn away from the centre of the mass, 
sometimes cracking and always weakening it ; 3d, the interior of 
a gun thus forged is left in tension, while the exterior is in com- 
pression, which is the opposite state of strain to that required. 

493. FORGING HOLLOW. The manner in which Naylor, 
Tickers & Co.'s steel jackets are forged hollow for Blakely guns 
has been referred to under the latter head (22, 68, 69). 

Mr. Whitworth and his partner, Mr. Hulse, in a subsequent 
patent for constructing steel or homogeneous metal ordnance, thus 
specify the method of hollow forging : They " cast an ingot with 
a hole through it, and afterwards hammer it between an angular- 
shaped anvil-block and a hammer-head of a similar or flat shape. 
A mandrel of a taper form is inserted through the hole cast in the 
ingot, and the operation of hammering or forging proceeds till the 
mandrel becomes too hot from its contact with the heated metal 
of the ingot ; it is then withdrawn, arid a cold mandrel is inserted 
in the place of the heated one, and the hammering or forging is 
continued until it is made of the desired size and shape. If pre- 
ferred, a hollow mandrel may be used and cooled internally. The 
hammered tubular ingot is subsequently annealed. If necessary, 
the interior surface of the tubular ingot may be ' converted' to the 
required depth." 

493. COMPRESSING BY HYDRAULIC MACHINERY. The heaviest 
hammers, however, are found to produce too much local and exte- 
rior, and too little distributed and interior compression upon large 
masses of steel. And heavy hammers are inconvenient, especially 
when the forging is irregular in shape. Therefore steel-makers 
are beginning to use hydraulic presses for drawing and shaping 
their ingots. At the new works of Messrs. Naylor, Yickers & Co., 



416 ORDNANCE. 

now erecting at Sheffield, this machinery will be substituted for 
the heaviest hammers. Mr. Bessemer has also patented some 
alterations especially adapting hydraulic apparatus to the drawing 
of his ingots. 

It is obvious that the slow and uniform pressure of water 
pumped through a small aperture into a large cylinder, will not 
strike a blow, but that it will allow each particle of matter acted 
upon, however thick the mass, time to distribute the pressure to 
the next particle. In the case of ingots compressed while hot 
from the moulds, and, therefore, Softer within than without, the 
interior metal would be better worked and more condensed than 
the exterior metal. 

494. ROLLING AND JOINING HOOPS. Another, perhaps equally 
important advantage due to the casting of steel, is the cheap fab- 
rication of hoops with endless grain. The machinery used is a 
FlG m modification of the ordinary rolling- 

mill ; the rolls are short, overhang- 
ing their journals, so that a ring 
can be slipped over them (Fig. 187). 

A ring of, say, half the diameter 
Machine for rolling hoops. ^ ^^ ^ tWckness of ^ fin . 

ished ring, is cast as any other ingot is cast.* This is put between 
and drawn round by the rolls, which are made to gradually 
approach each other until its diameter is properly increased, and 
a continuous grain is developed in the direction of its circum- 
ference. Messrs. Naylor, Tickers & Co. cast a great many 
ingots in this shape for tires, and for Blakely and other hooped 
guns. 

There would be no difficulty, if the springing of the necessarily 
small inner roll is not serious, in making tubes two or three feet 
long in this way. Long rolls would require support at both ends, 
but one of them might have a movable pillow-block at one end. so 
that a ring could be readily put in or removed. 



* Messrs. Naylor Tickers and Co. cast these ingots on a yielding core, and have 
patented their process. 




STEEL. 417 

Mr. Krupp makes rings with endless grain, by forging an ingot 
into the shape shown at Fig. 188, having holes in its ends, and 
uniting them by a slot, opening it out into a ring, and then roll- 
ing it in the manner described.* With his present ^ 
machinery, he can make hoops of any diameter, but 
not of a width exceeding 6 inches. 

To avoid the necessity of immense hammers and 
furnaces, and the costly experiments, by which alone thod of ma- 



a manufacture like Mr. Krupp's can be established J^| g so11 
in another country, with different materials and 
unskilled workmen, Mr. Hitchcock, of New York, proposes the 
process already discussed and illustrated (460), of fabricating solid 
guns from small masses of low steel or wrought iron. In any 
case, Mr. Hitchcock's process would be valuable for the fabrica- 
tion of long hoops from rings. 

. 495. Solid Cast-Steel Oun. The soundness of steel castings, 
especially those produced by Messrs. Naylor, Yickers & Co., and 
by the Bochum Company, Prussia, have induced Captain Blakely 
to construct parts of some of his guns, such as outer jackets to 
embrace inner tubes, of hollow ingots not forged, but only an- 
nealed ; and there is a growing impression in England that the 
heaviest ordnance will be cast solid from steel. As such guns 
would have about three times the tenacity of cast iron per square 
inch, the walls could be so much thinner, that the defects due to 
unequal cooling (364) would not be very serious. Besides, 
the advantages of hollow casting (373) and cooling from the 
interior could be as well realized in steel as in iron. Oil the other 
hand, it is contended that the gain in strength will always pay 
the cost of hammering steel. 

The outer jackets of built-up guns, upon which must be formed 
or secured the trunnions and cascable, and which, for the sake of 
longitudinal strength, should be solid at the breech end, can only 
be forged at a very great cost. And, if cast hollow, they could 
be so little compressed or drawn by forging, that very little 

* Mr. Krupp's Circular Great Exhibition, 1862. 

27 



418 ORDNANCE. 

strength would be added to them by that process. Therefore the 
simple casting and annealing of such parts, in the manner adopted 
by Captain Blakely, would seem to be a very valuable improve- 
ment in gun-making. 

It has already been remarked that tubes for hydraulic presses, 
railway tires and wheels, cranked axles and bells of every size, 
are cast sound and homogeneous throughout, from low steel, by 
the two establishments mentioned. These castings are always 
annealed, which increases their specific gravity and toughness, 

SECTION Y. BRONZE. 

496. An alloy of about 90 parts of copper and 10 parts of 
tin, commonly known as " gun-metal" in Europe, is popularly 
called " brass" in America, when used for cannon, and named 
" bronze" by recent American writers. A strong cast iron is also 
known in America as " gun-metal." 

Referring to Table 72, it will be observed that the " work done" 
in stretching to the elastic limit and to the point of fracture, is 
less for ordinary bronze than for wrought iron of maximum duc- 
tility, and for low steel. This detect, added to the costliness* of 
bronze, to the various embarrassments experienced in the casting 
of large masses, to its softness, and consequently rapid wear and 
compression, and to its injury by heat, has not warranted its em- 
ployment for large calibres and high charges. The increase of 
cost, with increase of weight, would probably be greater for 
bronze than for cast iron, and much greater than for steel fab- 
ricated by Bessemer's, or wrought iron fabricated by Ames's or 
Hitchcock's process, because bronze must be cast under great pres- 
sure, to be sound and tenacious. So that, were it the proper metal 
in other particulars, an unnecessarily large and actually immense 
non-paying capital would be tied up in a national bronze arma- 
ment. The high value of the old material would not offset this 



* The price of bronze field-pieces, according to Benton's " Ordnance and Gunnery," 
1862, was about 45 cents per pound. 



BRONZE. 



419 



cost to the extent that it does in railway matters, for obvious 
reasons. 

The mean ultimate cohesion of gun-metal, according to Euro- 
pean authorities and the experiments of the United States Govern- 
ment, is about 33000 Ibs. per square inch. In one of his tables, 
Mr. Mallet states it from 32334 Ibs. to 43536 Ibs.* Major "Wade 
states it from 17698 to 56786 Ibs.f 

Captain Ben ton says, J that " the density and tenacity of bronze, 
when cast into the form of cannon, are found to depend upon the 
pressure and mode of cooling. This is exhibited by the means of 
observations made on five guns cast at the Chicopee Foundry, 



DENSITY. 


TENACITY PEE SQTJABE INCH. 


Breech square. 


Gun-head. 


Finished gun. 


Breech square. 


Gun-head. 


8-765 


8-444 


8-740 


46509 


27415 



u The guns were cast in a vertical position, with the breech 
square at the bottom. In consequence of the difference in the 
fusibility of tin and copper, the perfection of the alloy depends 
much on the nature of the furnace and the treatment of the 
melted metal. By these means alone, the tenacity of bronze has 
been carried, at the Washington Navy Yard Foundry, as high as 
60000 Ibs." 

The fabrication of bronze ordnance appears to be far better un- 
derstood in Spain, and more especially in Turkey, than in Amer- 
ica or England. Some bronze guns of 20 tons weight have been 
cast in Spain, but they cannot be rapidly fired. 

497. According to American and British authorities, the 
want of uniformity, even in different parts of the same gun, is 
a striking defect. For instance : " For light pieces, especially for 

* "On the Construction of Artillery," Mallet, 1856, p. 78. 
f "Reports of Experiments on Metals for Cannon," 1856. 
j "Ordnance and Gunnery," 1862. 



420 ORDNANCE. 

field-cannon, bronze is much used, but there are many objections 
even to this alloy. As the tin is much more fusible than the cop- 
per, and must be introduced when the latter is in fusion, it is diffi- 
cult to seize the precise moment when the alloy can be properly 
formed ; part of the tin is frequently burned and converted into 
scoria."* 

Major Wade, after calculating the results of experiments on a 
lot of bronze guns, cast at Chicopee,f says : " The most remark- 
able feature of the above table is the irregular and heterogeneous 
character of the results which it exhibits, in samples taken from 
different parts of the same guns. * * * By an examination 
of the results obtained from the heads of all the guns cast, it will 
appear that the density varies from 8*308 to 8*756, a difference 
equal to 28 Ibs. in the cubic foot ; and that the tenacity varies 
from 23529 to 35484, a difference in the ratio of 2 to 3. These 
differences occur in samples taken from the same part of different 
castings, the gun-head ; the part which, in iron cannon, gives a 
correct measure of the quality of the metal in all parts of the 
gun. * * * The materials used in all these castings were of 
the same quality; they were melted, cast, and cooled in the same 
manner, and were designed to be similarly treated in all respects. 
The causes why such irregular and unequal results were produced, 
when the materials used and the treatment of them were ap- 
parently equal, are yet to be ascertained." Speaking of another 
lot of bronze howitzers, made at the South Boston Foundry, the 
same authority says : " On a general resurvey of the results ob- 
tained from all the samples tested, the most striking feature 
exhibited is that of their great diversity in density and strength, 
and for which no obvious or satisfactory cause is seen or can be 
assigned." 

498. The authorities generally agree that the tin in bronze 
guns is gradually melted by the heat of successive explosions. 
If this is the case with field-guns, the heavy charges and pro- 



* "Ordnance and Naval Gunnery," Simpson, 1862. 

f " Reports of Experiments on Metals for Cannon," 1856. 



BRONZE. 421 

jectiles, and the quick firing demanded in iron-clad warfare, 
would soon destroy this material. Colonel Wilford stated, at a 
meeting of the United Service Institution. * that iron mortars 
were introduced because holes were burned in the chambers of 
bronze mortars by the immense heat of the powder-gas. Heat 
also causes the drooping of the Darts of a bronze gun that over- 
hang the trunnions. 

As to decomposition, Captain Benton says :f " Bronze is but 
slightly corroded by the action of the gases evolved from gun- 
powder, or by atmospheric causes ;" but Captain Simpson remarks J 
that the gases produced by the combustion of gunpowder also 
produce an injurious effect upon this kind of piece, by acting 
chemically on the bronze. 

499. Both abrasion and compression are due to softness. The 
hardness of bronze, as compared with cast and wrought iron, is 
tabulated by Major Wade. (Table 7l.) 

All these defects of bronze for the bore of a gun, irrespective of 
strength, viz., the melting of the tin, the change of figure, the 
conversion, abrasion, and compression obviously aggravate each 
other ; and, when taken in connection with rifling and excessive 
pressures, are conclusive evidence as to the unfitness of the mate- 
rial to meet the conditions of greatest effect under consideration. 

The average ultimate tenacity of bronze is so low in fact, little 
above that of the best average cast gun-iron that the loss of 
strength, due to want of regulated initial tension and compression, 
becomes a very serious defect, when calibres are large and pres- 
sure high. To remedy it by hooping bronze with steel or iron, 
would not avoid the defective surface of the bore, just considered. 

500. The Dutch, however, have lined cast-iron guns with 
bronze, and Captain Blakely has constructed some experimental 
guns in the same way, for another reason : bronze can safely 
elongate more than cast iron, without permanent change of figure ; 

* "Journal of the United Service Institution," June, 1862. 

j- "Ordnance and Gunnery," 1862. 

J "Ordnance and Naval Gunnery," 1862. 

"Reports of Experiments on Metals for Cannon," 1856. 



422 ORDNANCE. 

and when it is put in a position where it must be more elongated 
by internal pressure, the strength of the whole structure is thus 
brought into service the principle of varying elasticity, already 
considered, is approximately realized (320). 

5O1. Bronze hoops upon steel or iron barrels (106) would 
avoid the defect of a soft bore, but it would increase the defect 
just considered, due to the unequal stretching of the layers of a 
tube by internal pressure. A principal advantage of bronze hoops 
mentioned by Mr. Wiard (338) is, that with the little heat they 
would get from the powder, they would expand to the same extent, 
approximately, as the more highly -heated iron barrel, thus redu- 
cing the danger of bursting by rapid firing. 

SECTION VI. OTHEK ALLOYS. 

5O2. PHOSPHORUS is known to improve the strength of copper, 
and to make it cast soundly. Mr. Abel, chemist to the British 
War Department, stated before the Institution of Civil Engineers,* 
that he had made some experiments upon the combinations of 
phosphorus with copper, and " had found that by the introduction 
of a small proportion of that substance, say from 2 to 4 per cent., 
of phosphorus into copper, a metal was produced, remarkable for 
its density and tenacity, and superior in every respect to ordinary 
gun-metal (the alloy of copper and tin known by that name). He 
believed the average strain borne by gun-metal might be repre- 
sented by 31000 Ibs. upon the square inch; whilst the material 
obtained by adding phosphorus to copper bore a strain of from 
48000 to 50000 Ibs. But the increased tenacity was not the only 
beneficial result obtained by this treatment of copper. The mate- 
rial was more uniform throughout, which was scarcely ever the 
case with gun-metrl The experiments alluded to were merely 
preliminary, and had been, to a certain extent, checked by the 
improvements since introduced in the construction of field-guns, 
which had led to a discontinuance of the employment of gun- 

* Construction of Artillery, Inst. Civil Engineers, 1860. t 



BRONZE. 423 

metal." The improvements alluded to were wrought iron and 
steel, arid the Armstrong and Whitworth processes of fabrication. 

5O3. ALUMINIUM is found to add great strength to copper. 
The compound thus formed is called Aluminium Bronze. Mr. 
Anderson, Superintendent of the Royal Gun-Factories, Woolwich, 
has found the tensile strength of an alloy of 90 per cent, of copper 
and 10 per cent, of aluminium, to be 73181 Ibs. per square inch, 
or twice that of gun-metal ; and its resistance to crushing, 132146 
Ibs., that of gun-metal being 120000 Ibs. The aluminium bronze 
did not begin to change figure until the pressure exceeded 20384 
Ibs. In transverse strength or rigidity, it was also found superior 
to gun-metal, in the ratio of 44 to 1. Its tenacity and elas- 
ticity depend on a particular number of meltings: at the first 
melting it is very brittle, a state to which it again returns after 
fusion.* 

" The first melting appears to produce internal mechanical mix- 
ture, rather than chemical combination of the metals ; as, in the 
proportion of 10 of aluminium and 90 of copper, an alloy of a very 
brittle character is produced by the first melting ; but renewed 
opportunity of uniting into a definite chemical compound being 
afforded by repeated melting, a more uniform combination seems 
to take place, and a metal is produced free from brittleness, and 
having about the same hardness as iron. The alloy, containing 
rather less than 10 per cent, of aluminium, is said to possess the 
most uniform composition and the best degree of hardness ; but it 
is not always an easy thing to produce this desirable uniformity 
of texture, as patches of extreme hardness sometimes occur, which: 
resist the tools, and are altogether unamenable to the action of the 

rollers/'t 

Aluminium bronze, composed of 9 parts by weight of copper 
and 1 of aluminium, was found by Mr. Anderson to have a tensile 
strength of about 43 tons (96320 Ibs.) ; but two other specimens, 
which were not quite sound, had only a mean tensile strength of 



* Philosophical Magazine. 
f Newton's Journal of Arts. 



424 



ORDNANCE. 



about 22^ tons* (50400 Ibs.). So that the metal is liable to great 
variations in strength. 

The cost of this alloy, 6s. 6d., or $1.62 per pound, would of 
course prevent its extensive introduction as a cannon-metal. 

5O4. STEKRO-METAL, a recent invention of Baron de Rosthorn, 
of Vienna, is described by a correspondent of the London Times,\ 
in an article that contains so many accurate statements on other 
points, as to merit consideration : " The mechanical properties of 
the alloy have been carefully examined at the Polytechnic Insti- 
tution, Vienna, in the presence of competent observers; and I now 
have before me a duly attested copy of the tabulated results of not 
fewer than 30 experiments, from which I select the following. 
The tensile strength per square inch is estimated in English tons : 



TABLE LXXIIL TENSILE STRENGTH OF STERRO-METAL. EXPERIMENTS OF POLY- 
TECHNIC INSTITUTION, VIENNA. 





Tensile Strength 
in Tons. 


Eeduced to Pounds. 


STEBKO-METAL. 
After simple Fusion 


47 


604.80 


After Forging Red-hot 


34. 


76160 


After Drawn Cold 


^8 


85110 


GUN-METAL BRONZE. 
After Simple Fusion . 


18 


40320 









" The same copper, from Boston, U. S., was used in making 
both the sterro-metal and the gun-metal, and for the latter the 
best English tin was employed. Both alloys were cast under pre- 
cisely similar conditions, and run into the same mould. Similar 
tests were made at the Arsenal, Vienna, and the results are as fol- 
low : 



* Correspondence of the London Times. 

f London Times, Feb. 3d, 1863. Also quoted by the London Engineer, Feb. 6, 1863. 



BRONZE. 



425 



TABLE LXXIV. TENSILE STRENGTH OF STEREO-METAL. EXPERIMENTS AT THE 
ARSENAL, VIENNA. 





Tensile strength in Tons. 


Eeduced to Pounds. 


STEKRO-METAL. 
After Simple Fusion 


a g 


62720 


After Forging Red-hot 


12 


71680 


Drawn Cold and reduced from 100 ") 
to 77 of transverse Sectional Area.. J 


37 


82880 



" The specimens of metal operated on in the preceding experi- 
ments were analyzed at the Austrian mint. The results are as 
under : 

TABLE LXXV. ANALYSIS OF AUSTRIAN STERRO-METAL. 



, 


Polytechnic Metal. 


Arsenal Metal. 




re 04. 


C7 6l 




4.2 36 


4O-22 




I 77 


1-86 


Tin 


o8l 


O- 1 C 










IOO.OO 


99.86 



" Experience lias shown that the proportion of spelter may vary 
from 38 to 42 per cent., without materially affecting the quality 
of the alloy. * * * The specific gravity of the forged metal is 
8'37, and that of the same metal, drawn cold into wire, 8'40. 
But sterro-metal possesses another quality which, in 
reference to its application for guns, is regarded as more impor- 
tant than its high tenacity, viz., great elasticity. It is not per- 
manently elongated until stretched beyond T T of its length. 
* * * Sterro-metal, it should be stated, is from 30 to 40 per 
cent, cheaper than gun-metal. Field-guns, from 4 to 12-pound- 
ers, have been made of single pieces of metal, worked by the 



426 ORDNANCE. 

action of a hydraulic press, whereby expense in forging is 
avoided; but reliable experiments have demonstrated that the 
metal thus treated has precisely the same properties and the 
same tensile strength as bars of it drawn out under the steam- 
hammer. * * * 

" It remains to be seen whether the tremendous concussions 
occasioned by firing will not seriously injure this new alloy, and 
whether the surface of a metal containing so large a proportion 
of spelter will not be seriously corroded." 

EXPERIMENTS AT THE ROYAL GUN-FACTORIES, WOOLWICH, WITH 
STERRO-METAL. The following is the official report of experi- 
ments made by Mr. John Anderson, upon this metal, variously 
compounded and treated : 

" Composition of this alloy, as made in the arsenal at Vienna, 
is copper, 60 *. zinc, 41*88 ; iron, 1*94 ; tin, '156. And, as made 
at the Polytechnic, Vienna, its composition is : copper, 60 ; zinc, 
46*18 ; iron, 1'93 ; tin, '905. 

" Alloys of similar composition to that of the Austrian metal 
have been prepared in the Royal Gun-Factories, from which a 
better result has been obtained than from mixtures of the Aus- 
trian metals, also prepared in the Royal Gun-Factories. The sub- 
joined table shows the results of the experiments with these dif- 
ferent specimens. 

" This alloy is said to be the invention of Baron de Rosthorn, 
of Vienna. It derives its name from a Greek word signifying 
4 firm.' It consists of copper and spelter, with small portions of 
iron and tin ; and to these latter its peculiar properties are attrib- 
uted. 

" It has a brass-yellow color, is close in grain, is free from poros- 
ity, and has considerable hardness, whereby it is well adapted to 
bearing-metal, or other purposes, where resistance to friction is 
needed. 

" Sterro-metal possesses another quality, which, in reference to 
its application for guns, is regarded as more important than its 
high tenacity, namely, great elasticity. 

"The inventor proposes that, in heavy ordnance, the interior 



BRONZE. 



427 



TABLE LXXVI. COMPOSITION AND STRENGTH OP STERRO-METAL, WOOLWICH. 



Composition. 


Treatment 


Strain at per- 
manent elon- 
gation of -002 
per Inch. 


Breaking 
weight. 


Ultimate 
elongation 
per in. 


Austrian 

R. G. F 

copper, 

3 5 tin 

Do. 

copper, 
4J tin 

Do. 
Do. 

Do. 


Mixture. .. . 




As received 


Tons. 
6.75 

II 

'3-75 
17-25 

15^5 

17. 


Tons. 
26-75 

21. 5 

19.25 

24-25 
23.25 
28. 


Inches. 
I 

.05 

.015 
016 

02 
.045 


actories Mixture of"| 
60 j zinc, 39 ; iron, I 
j . ij 


Cast in sand 


Cast in sand . 


do. 
60; zinc, 44; 

j 


of l 

iron, j- 


Cast in iron ........ 


do. 
do. 

do. 


do. 

do. 

do. 


Cast in iron and 1 


Forged red-hot 





should consist of a tube of sterro-metal, and, over this, wrought 
or cast iron should be shrunk, from the breech to beyond the 
trunnions." 

5Oo. An alloy of copper, made by the Ames Manufacturing 
Company, at Chicopee, Mass., is said to have a tensile strength of 
80000 Ibs. per square inch. The particulars of the composition 
are not made public. 

SO6. In the discussion before the Institution of Civil Engi- 
neers, before referred to, * Mr. Charles Fox said that " he believed 
it would eventually be found that the best gun could be con- 
structed with some extremely dense and homogeneous alloy, cast 
and used without being drawn under the hammer. If a gun was 
made of an alloy possessing very great density, the detonating 
force of the powder would be resisted by a greater quantity of the 
metal employed than it could be by making use of one with 
greater elasticity. He thought, therefore, the best guns would be 
made of iron, mixed with some other metals, such as wolfram and 
titanium, so as to insure the greatest strength and density. Mr. 



* " Construction of Artillery," Inst. Civil Engineers, 1860. 



428 ORDNANCE. 

Mushet had obtained great density, by mixing with iron a small 
percentage of wolfram, and great strength by the use of titanium. 
Therefore, he was inclined to believe, that guns cast of the 
densest alloys would have greater effect, in proportion to their 
thickness, than could be obtained by any complicated and expen- 
sive mode of construction." 

3O7. It is obviously impossible, in the absence of further 
experiments, to predict either great success or failure for the 
alloys considered, as compared with steel. The field for discovery 
and improvement is certainly broad and promising but no more 
so than in the case of steel. Although the alloying of copper, 
especially for cannon, has been practised for more than five hun- 
dred years, and should, therefore, be in advance of steel-making, 
which, for the purposes of artillery, is the work of the last decade, 
both metals in fact, all metals are undeveloped, because their 
chemical relations, and especially their elongation, within and 
beyond the elastic limit, and the corresponding pressures, have not 
been properly investigated. 

While certain alloys, of both iron and copper, have one impor- 
tant feature in common homogeneity, due to fusibility, at prac- 
ticable temperatures the alloys of iron have this grand advan- 
tage : iron is everywhere cheap and abundant; and the other 
necessary ingredients and fluxes carbon, manganese, zinc, and 
siliciurn are equally abundant, and. in some localities, already 
mixed, which would appear to be, on the whole, advantageous, 
although the mixtures are not found in proper proportions. 

5O8. Conclusions 1. The fitness of metals for cannon 
depends chiefly on the amount of their elongation within the elas- 
tic limit, and the amount of pressure required to produce this 
elongation ; that is to say, upon their elasticity. 

It also depends, if the least possible weight is to be combined with 
the greatest possible preventive against explosive bursting, upon 
the amount of elongation and the corresponding pressure, beyond 
the elastic limit ; that is to say, upon the ductility of the metal. 

Hardness, to resist compression and wear, is the other most im- 
portant quality. 



CONCLUSIONS. 429 

2. Cast iron has the least ultimate tenacity, elasticity, and duc- 
tility ; but it is harder than bronze and wrought iron, and more 
uniform and trustworthy than wrought iron, because it is homo- 
geneous. 

The unequal cooling of solid castings leaves them under initial 
rupturing strains ; but hollow casting, and cooling from within, 
remedies this defect, arid other minor defects. 

3. Wrought iron has the advantage of a considerable amount 
of elasticity, a high degree of ductility, and a greater ultimate 
tenacity, than cast iron ; but, as large masses must be welded up 
from small pieces, this tenacity cannot be depended upon : this 
defect, however, is more in the process of fabrication than in the 
material, and may be modified by improved processes. Another 
serious defect of wrought iron is its softness, and consequent 
yielding, under pressure and friction. 

4. Low cast steel has the greatest ultimate tenacity and hard- 
ness ; and, what is more important, with an equal degree of duc- 
tility, it has the highest elasticity. 

It has the great advantage over wrought iron, of homogeneity, 
in masses of any size. 

It is, unlike the other metals, capable of great variation in den- 
sity, by the simple processes of hardening and annealing, and, 
therefore, of being adapted to the different degrees of elongation 
that it is subjected to, in either solid or built-up guns. 

5. Bronze has greater ultimate tenacity than cast iron, but it 
has little more elasticity, and less homogeneity; it has a high 
degree of ductility, but it is the softest of cannon-metals, and 
is injuriously affected by the heat of high charges. 

The other alloys of copper are very costly, and their endurance, 
under high charges, is not determined. 

6. In view of the duty demanded of modern guns, simple cast 
iron is too weak, although it can be used to advantage for jackets 
over steel tubes a position where mass, small extensibility, and 
the cheap application of the trunnions and other projections, are 
the chief requirements. And, although cast-iron barrels, hooped 
with the best high wrought iron, and with low steel, cannot fulfil 



430 ORDNANCE. 

all the theoretical conditions of strength, and do not endure the 
highest charges, they have thus far proved trustworthy and 
efficient. 

Wrought iron, in large masses, cannot be trusted, and is, in all 
cases, too soft. 

Bronze is impracticably soft and destructible by heat. 

Low steel is, therefore (possibly in connection with cast 
iron, as stated above), by reason of the associated qualities which 
may be called strength and toughness, the only material from 
which we can hope to maintain resistance to the high pressures 
demanded in modern warfare. 



RIFLING AND PROJECTILES. 



431 



CHAPTER V. 

RIFLING AND PROJECTILES. 



STANDARD FORMS AND PRACTICE DESCRIBED.* 

5O9. THE first comprehensive experiment with rifled cannon 
appears to have been made in Russia, about 1836, and consisted 
in firing 1800 rounds from a 12-pounder, 262 shots in one day 
from an 18-pounder, and 100 shots continuously, on successive 
days, from both an 18-pounder and a 24-pounder, without either 
wads or grease. The gun was the invention of Montigny, of Bel- 
gium, and was rejected by his own Government, and finally by 
the Russian and the British Governments. 

olO. Major (now General) Cavalli, a Sardinian oificer, experi- 
mented, in 1845, with a breech-loading gun (Fig. 189) which was 
rifled with two grooves for a plain iron shot (Fig. 190). In 1847, 

Fig. 189. 




Cavalli rifled breech-loader. 

he obtained good results with an 8-in. gun, until the breech- 
loading apparatus gave way. 

* Many of the following historical and descriptive facts about European projectiles 
are compiled from papers read by Commander R. A. E. Scott, R. N., before the Royal 
United Service Institution. 



432 



ORDNANCE. 



511. In 1846, Baron Wahrendorf, of Sweden, affixed lead to 
the sides of elongated projectiles by means of grooves (Fig. 191). 



FIG. 190. 



FIG. 191, 





Cavalli projectile. 



"Wahrendorf's lead-coating. 



FIG. 192. 



The plan was tried at Berlin in 1851, in a 6-grooved 12-pounder 
with a slow twist ; and afterwards in both Sweden and Prussia ; 
and in 1857 in France, but without remarkable 
success. In 1856, General Timmerhaus, of Bel- 
gium, invented an expanding (Fig. 192) sabot, 
which was forced into the rifling, and thus gave 
rotation to the projectile. His gun had two, 
four, and six grooves, with one turn in 18 feet. 

512. In these plans we find the germs of the 
three leading systems of the present day the 
solid projectile, fitted to enter the grooves of the 
gun ; the compression of a soft covering on the 
shot by the lands of the gun (the Armstrong 
system); and the expansion of the rear of the 
shot by the pressure of the powder, to fill the 
grooves of the gun. 
513. The Centering System. The solid projectile, fitted to 
the rifling of the gun so as to centre itself, lias been improved by 
Commander Scott, R. X., in what he calls the " centrical" sys- 
tem, which will be further mentioned (535). The centering sys- 
tem may embody the compressing or expanding system in any 
required degree. While the shot is rotated by the solid projec- 
tions formed upon it and fitting into the grooves of the gun, the 
exterior of these projections, or of the whole shot (521), may be 
covered with a soft substance, which may, in the case of a breech- 
loader, be larger than the bore, and thus be compressed while 
passing out of the gun ; or which may, like the Sawyer projectile 




Timmerhaus's ex 
panding shot. 



RIFLING AND PROJECTILES. 



433 



FIG. 193. 



(540), "be expanded by the pressure of the powder to fill the 
gun. 

Usually, the hard surface of the projectile is dressed to bear 
directly upon the surface of the bore, leaving a little windage. 
Whitworth's (531) and Scott's (535) projectiles are examples of 
this practice. 

711. Projectiles, having wings fitted for certain grooves, can 
only be used, each with its own bore; while compressed or ex- 
panded shot will adapt themselves to any form of rifling. In a 
gun grooved for winged shot, however, any expanding shot can 
be employed ; while, if the enemy has no guns fitted for winged 
shot, he cannot fire such shot back, when any are captured or 
recovered. 

515. FKENCH. The first successful adoption of rifled cannon 
in warfare was by the French against the Austrians, in 1859.* The 
plan (Fig. 193), brought forward as early as 
1842 by Colonel (now General) Treuille de 
Beaulieu, and twice ignored by the French 
Artillery Committee, was finally appreciated 
by the Emperor, after the before-mentioned 
trials of Wahrendorf's and several other rifled 
projectiles. It consisted of 12 zinc studs, or 
buttons, placed on the shot in pairs, so as to 
project into the 6 rounded grooves of the gun. 
One stud, or projection on the gun, was ar- 
ranged to push the bearings of the shot tight 
against those sides of the groove on which it BeaulieuX or first 
would press in going out, so as to decrease 
jarring and play. 

For larger ordnance, the French commenced by making two shal- 
low elliptical grooves (Fig. 194). The projectiles were of solid iron ; 
those having short studs or bearings were used with the " gaining 
twist," and those having long bearings with the uniform twist. 

* The present French centering system was introduced in Dec., 1860, after Com- 
mander Scott's centering system, which was offered to the British Government in 
August, 1859. 

28 




French service rifle 
shot. 



434 



OllDNANCE. 



But as the projectile could not accurately centre itself on two 
points, three points were provided, and in December, 1860, the 
three-grooved gun (Fig. 195), with the gaining twist, was intro- 



FlG. 194. 



FIG. 195. 





Early French rifling for ordnance. 



French rifling, 1860. 



duced. Studs faced with white metal were cast on the bearing 
side of the projectile (Fig. 196). The ordnance thus treated were 
cast-iron 30-pounders and 50 -pounders, strengthened by hoops 
over the breech. 



FIG. 196. 





French projectile, 1860. 

716. The following are the particulars of the French rifling 
and projectile (Fig. 197) used with a cast-iron 32-pounder gun, 
charge, 5*5 Ites., in the English competitive trials of 1861 : In- 



RIFLING AND PROJECTILES. 



435 



FIG. 197. 



creasing twist, from to 4'652 in 88*548 ; number of grooves, 3 ; 

width, 1-919 in. ; depth, 0*2363 in. ; weight of shot, 59'5 Ibs. ; 

length, 14-05 in. ; diame- 

ter, 6'36 in. ; diameter of 

powder-chamber, 4*66 in. ; 

bursting charge, 5 Ibs. 5 

oz. (592). 

017. The old 6-in. 24 
pounder, of 4400 Ibs. weight, 
is rifled to carry 53-lb. pro- 
jectiles with a 5-lb. 2-oz. 
charge. 

518. The old 30-poun- 
der,* of 6-5-in. bore and 
8239 Ibs. weight, is hooped 
with steel, and rifled to 
carry 99-lb. projectiles, with 
charges of T| Ibs. to 26 Ibs^ 
The rifling and the present 
stud of this gun are shown, 
full size, by Fig. 199. The 
hooped Canon de 30 is the 
standard French naval gun. 

519. It will be observed 
that a considerable windage 
is allowed in French guns. 
The object of this practice, 
which is directly opposed 
to the Armstrong practice, 
will be considered in an- 
other section. (647, note). 




French shell. 



The regular French bronze field-gun, Fig. 198, has the 
calibre of the old 4-pounder 3'4 inches; it weighs 730 Ibs., and 
fires an 8'8-lb. projectile, with a charge of 1 Ib. 3 oz. ; bursting 



* This gun is minutely described in Chapter I. (84.) 



436 



ORDNANCE. 




FIG. 198. 



French field-gun, mounted. (From a photograph.) 



RIFLING AND PROJECTILES. 437 

charge of shell, 7 oz. The mountain howitzer, a shorter gun, use? 
the same ammunition. 

The old 12-pounder, when rifled, is called a gun of reserve. Its 

Fro. 199. 




.// 
f$ 

Present French groove and stud, Canon de 30, full size. 






particulars are : Bore, 4f in. ; weight, 1350 Ibs. ; charge, 2*2 Ibs. ; 
weight of shell, 25 '3 Ibs. 

521. AUSTRIAN. The Austrians, having experimented with 
both the compressive system and the centering system, decided 
on the latter, substantially in the form used by the French. More 
recently they have introduced the system illustrated by Figs. 200 
to 203, as specially adapted to gun-cotton, a material now entirely 
substituted for gunpowder in the Austrian service. (See Appen- 
dix.) Fig. 203 is a cross-section of the 3-in. field-gun. The bore 
is spiral in section, increasing in diameter from the point a. The 
land a c is the bearing side going in, and all the rest of the bore is 
the bearing side which rotates the shot coming out. The cast-iron 
projectile d d, Fig. 200 (longitudinal section), and Fig. 201 (cross- 
section), is covered with the soft metal coating e e, which enters 
the gun freely when the projection h bears against the land a c. 
but which, as the shot comes out, is compressed by the spiral 
bore and shuts off the windage. To prevent the shot jamming 
in the bore, three grooves, Jc m n, are introduced to receive 
corresponding ribs on the shot. But the shot is centred and 
rotated coming out, by the whole circumference of the bore as 
well as by these three grooves. Fig. 202 represents the fuse 
used with the shell. 

522. THE KussiAJfs have adopted the French rifling for heavy 



438 



ORDNANCE. 



FIG. 200. 




FIG. 201. 




FIG. 203. 



FIG. 202. 



I. Ml I J 





Austrian rifling, shell and fuse for gun-cotton. 



RIFLING AND PROJECTILES. 



439 



FIG. 204. 




Russian studded rifle-shell. 



ordnance, and have provided themselves with machinery for 
grooving guns without dismounting them. It is stated that their 
cast-iron 56-pounders and 120- 
pounders are to be hooped and 
rifled with three grooves. "The 
Russians had rifled several of 
their smaller fortress-guns (30- 
pounders and 24-pounders) with 
six grooves, and their field-pieces 
have been mostly rifled in a simi- 
lar manner ; but, instead of placing the studs in pairs, and having 
twelve of them, they use only six placed alternately. Their 
rifling has an equal twist, and the grooves are slightly narrowed 
at the bottom. In the field-piece they are sloped off on one side 
to allow the projectile, the bearings of which are also sloped off, 
to wedge itself tightly ; but these slight modifications, which 
have been also tried in France, possess no advantage over the fit- 
tings adopted for the French service."* 

523. More recently, the Russians have adopted the Armstrong 
shunt system of rifling with their steel ordnance. This will be 



Fia. 205. 



FIG. 206. 





Section of Fig. 204. 



Russian rifle-groove. 



illustrated, as used in England and in Russia, in another section 

(552). 

524. THE SPANIARDS have modified the French system by 
adopting a uniform twist, and placing the studs upon the projec- 
tile in pairs (Figs. 20T and 209). Three grooves are used ; the 



* Com. Scott. Journal Royal U. Service Inst, April, 1862. 



440 



ORDNANCE. 



cast-iron guns are reinforced with hoops having definite initial 
tension. 

525. The failure of the Cavalli and Wahrendorf breech-load- 
ing apparatus for heavy guns, in Sardinia, led to the abandon- 



Fro. 207. 



FIG. 209. 




^ 



Section of Spanish gun. 




Spanish shell. 



ment of the compression system, and the adoption of the French 
rifling and projectiles. A similar failure of the Armstrong breech- 
loader is anticipated, if not quite realized, in England. In that 
event, the compression system, which depends upon loading at 
the rear end of the bore, would of course be abandoned. 

526. In Sweden, Holland, and Portugal in fact, on the Con- 
tinent generally, excepting in Prussia and Belgium, centering the 
projectile, on the French plan, has been adopted for rifled ordnance. 
It has also been adopted in England, with a little modification (see 
shunt-rifling), for the Armstrong 10 J and 13-in. rifles, for experi- 
mental 70 and 12-pounders, and for other experimental guns. 

527. LANCASTER. Another plan of centering the shot is that 
of Mr. Charles Lancaster (Fig. 210), used, with partial success, by 
the English in the Crimea, and since made the subject of many 
costly experiments. The gun is rifled with two rounded grooves, 
each half the circumference in width, so that the cross-section of 
the bore is oval. Only a trace of the original bore is left at its 

i 



RIFLING AND PROJECTILES. 



441 



FIG. 210. 



minor axis. The major axis in the 32-pounder is 6*97 in., and the 
minor axis 6*37 in., so that, considered as a two-grooved rifle, the 
grooves are *3 inch deep at their 
centres. The pitch of the rifling 
is one turn in 30 feet. The ear- 
lier projectiles, viz., those sent to 
the Crimea, were made of wrought 
iron, simply oval, but without 
any rifle-twist upon them; but 
more recently the shot have been 
bent to the shape of the bore ; 
some of these had a wrought-iron 
casing put over a cast-iron projec- 
tile, and this, projecting 4 inches 
to the rear, carried a lubricant 
which the wooden wedges at the 

bottom sent out while expanding the casing so as to fill the bore. 
The weight of this projectile was 44 Ibs., and its capacity for 
bursting charge, 4i Ibs. It was thick in the rear, and thin in the 
front, tapering to a point. 

The Lancaster shell (Fig. 211), fired in the competitive 

FIG. 211. 




Lancaster's rifling. 




Lancaster cast-iron shell 



442 



ORDNANCE. 



FIG. 212. 



trials of 1861, with 6 Ibs. of powder, from a cast-iron 32-pounder, 
was in length, 11-9 in. ; diameter (major), 6*90 in., (minor) 6'32 
in.; weight, 46'5 Ibs. ; diameter of powder-chamber 4'59 in. The 
bursting charge is 4 Ibs. 7 oz. (592). 'The rifling of the earlier guns 
had an increasing pitch. The present guns have a regular twist. 

*>29. 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 


<i 
<( 




K 



2042 . 
2123 

'945 
2161 
2095 

3 6 35 
3768 

3775 
3795 
3921 

4007 

35 6 9 

3863 
3680 

373 1 




3.4 
4-0 
6.4 

I 2 

6-0 
33.0 
18.4 
14-0 
7.8 
19-0 
19-2 
27-0 

21 -0 
13.0 
I 3 .6 


I -2 




I -0 




I. 4 

8 








I 2 

a. a 




2-6 

4-0 

I 'O 

8-0 

I 

9.4 

2-4 

3.0 

















tile is then covered with a composition of lead and tin, cast on. 
The soft metal extends j inch below the base of the cast iron 



Fig. 225. 




Fig. 226. 




The Sawyer Shell. 



BlFLING AND PROJECTILES. 451 

(which is slightly chamfered), so as to be sufficiently compressed 
by the powder-gas to stop the windage. 

This principle of construction is of course applicable to any 
form of rifling, but has only been applied to the standard Ameri- 
can groove (560). 

541. Pattison's projectile (Figs. 227 and 228) has projections 

FIG. 227. FlG. 228. 





Pattison's projectile. Leather band. 

cast upon it to fit the rounded grooves of the gun. The windage 
is stopped by a simple leather band, c c, which is driven upon 
the conical base of the shot by the powder-gas. This projectile 
has been used with some success experimentally, but has not been 
adopted in the service. 

542. The Armstrong " Shunt" rifling is a modification of both 
the centering and the compressing systems, and will be considered 
under the latter head.* 

543. Tlie Compressing System. With this system the 
shot is larger than the bore, and is squeezed or planed to fit 
the bore by the lands of the rifling. The shot must therefore be 
entered at the breech, into a chamber larger than the rest of the 
bore ; and whatever escape of gas there may be around the breech- 
closing apparatus reduces its range and velocity. 

544. This plan was early adopted and perfected by the Prus- 
sians, who obtained great accuracy and range with charges of T ' T 
the weight of the projectile. The rifling consisted of numerous 
shallow rectangular grooves (Fig. 229). The shot was encircled 
by 4 rounded lead bands or hoops (Fig. 230), held in place by 
grooves in the shot. 

* As most recently modified, this is a centering projectile, with little or no com- 
pression. 



452 



ORDNANCE. 



FiG. 229. 



545. AKMSTKONG. The Armstrong system of rifling for breech- 
loaders does not differ in principle from, and was subsequent to, 
the Prussian compression sys- 
tem last mentioned. The rifling 
consists of a great number of 
shallow, narrow grooves (the 
T-in. 110-pounder has 76 see 
tables 1 and 2) the object being 
to give the soft metal covering Ear i y p russ i an rifling, 

of the shot a very large bearing 

on the driving side of the grooyes, and thus prevent stripping, and 
make up for want of depth. The different forms of grooves that 

FIG. 230. 





Early Prussian lead-coated shot. 

have been tried are shown by Figs. 231 to 233. The grooves of 
the 6-pounder and 12-pounder are shown, 4 times enlarged, by 
Figs. 234 and 235. 



FIG. 231. 



FlG. 232. 





Original Armstrong rifling. 



Adopted Armstrong groove. 



in. larger in 



546. The shot-chamber of the gun is about 
diameter than the adjacent part of the bore, so that the shot can 



RIFLING AND PROJECTILES. 



453 



FIG. 233. 



be easily entered from the rear. This is illustrated by Fig. 236. 
The actual diameters for the 110-pounder are opening through 
the breech- screw, 7*12 in. ; powder- 
chamber, 7*2 in. ; shot-chamber, 7*075 
in. ; bore, 7 in. From a point a few 
inches in front of the shot-chamber to 
a point near the muzzle, the bore is 
enlarged to 7'005; the object being, 
1st, to mould the lead covering of the shot at the first instant 
of motion, and to give it freedom in passing through the remain- 
der of the bore ; 2d, to centre the shot as it is leaving the muzzle. 

FIG. 234. 




Armstrong groove of 1861. 




FIGS. 234 and 235. Armstrong 6 and 12-Pr. rifling, 4 times enlarged. 



The particulars of the Armstrong rifling and projectiles 
have been given in Tables 1 and 2, and in the descriptions of dif- 
ferent guns, Chapter I.* The ranges of several guns are given 
in following Tables. 



* For heavy guns, this system of rifling and projectiles seems to be going out of 
use. No new Armstrong guns, with this rifling, have been fabricated since the 
beginning of 1863. The Army and Navy Gazette, of June 4, 1864, speaking of oper- 
ations at Woolwich, says: "In the laboratory, the workmen are preparing button- 
shot (the centering system) for the 70-pounders and 100-lb. projectiles, which are to be 
substituted for those of 110-lb. weight, now in the service. In the gun-factories, the 
men are busily employed in converting the breech-loading coil 70-pounders into muz- 
zle-loaders. * * * They are also preparing solid breech-pieces for the 11 0-pounders, 
which are intended to take the place of the prevent vent-pieces." The 70-pounders 
and the 100-pounders, will thus be converted into muzzle-loaders, which will prevent 
the continuance of the compressing system. 

On the 13th of August, the same authority says: "We understand that the further 
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 f>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 


<B 


- -_ 

ss 


Min. 


Max. 


Mean. 


r 


s's 

g'O 


01 
11 


1 


H 


8 








a 


s 


1 






sec. 


yds. 


yds. 


yds. 


yds. 


yds. 


yds. 


10 


2 


3-5 


1104 


1259 


1168 


39' 1 


1.88 


0-71 


10 


5 


6 -95 


2144 


**55 


2193 


23.9 


4-3 


2'10 


10 


10 


12.38 


3547 


37 2 9 


3594 


68-5 


22-32 


3 .60 



inventor deemed it important to prevent the shot from moving 
laterally, by direct pressure on its sides, instead of by allowing it 
to centre itself, like Commander Scott's (535) ; and, as the expan- 
sion system did not meet his views, his ingenious resort was to 
arrange the rifling so that the shot runs home easily, and is then 
shunted, or switched off, or turned a little in the gun, so that, 
when it comes out, a shallower portion of the groove will nip it, 
and prevent its lateral movement. 

The projectile (Fig. 243, the dotted lines show the outline of 

5 



462 



ORDNANCE. 



" s 

oo 



Remarks. 


Compressor hard over 
except as otherwise 
stated. 


11 

* a -d 

H> 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 
| 


.',......, . . . 




<J 




No. of Round. 


M r) 


m 5}- vr> 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 <q 
















IS 


c 





4 M H 










1 






1 

c 


M 


u 


vO O d "-^ t^> 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 

<u 

h 


CJ 

'? 


.s 
1 

I 

Crt 


The velocity of t 


The velocity of 
service charge of 


In order to ascer 


| 


O M cl to ^ o ^3 












00 




u 




N 






















' 



464 



ORDNANCE. 



the shell) is fitted with three bars of zinc, abutting against and 
projecting above iron ribs cast on the shot. The tops of the 



FIG. 243. 




Elevation of shunt shot. 

zinc bars are sometimes notched, as shown, to facilitate com- 
pression. The outsides of the zinc bars bear against the lands of 
the gun, and rotate the projectile. 

>>&. 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<c4 ; 


fi 








Range, in yards. 


.00 QMOOi-iOO^OrtO 
2r>.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<i/-iu~iVOoo Jtorot^-t^vovO 


00 ON ; : ; 00 


ONOOOo'oOOOt^OOVO ;u-,wt> 






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 r<OO O M C?\vo OO t-^ 




^^OOOO^OOOOOO 




W W M 


Time of Flight. 


v c">f< 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 


<n M 




u 




13 




13 13 13 Ic 


"rt 




I 


-G 
W5 


C/3 CO C/3 


3 


1 










Feet broad. 


g, 


8 


o : *o 


vrt 


gl 










to 

| Feet high. 


i? 


m 


T : ^ 





3 










Range, yards. 


I 


3 


8 


1 




M 




M 


" 


Elevation, deg. 


O 


^ 


ft . ^ 


t 


Shell, Ibs. 


V/" 

M 


M 


** 


I 




s 








1 


1 










g 




A 




i 


1 







^ 


o 


J* 





S T? - 


g 


&H 


c 






g 









C 
u 


g 




3 




*n 


(tf 




(5 




O 


* 


No. of Rounds 
fired. 


o 
II 


to 


o ^- 

P4 


a 



EXPEKIMENTS AGAINST ARMOR. 



489 



I 

f 

B 

O 

M 

I 









C 




I 




0^ 




J 




s 




*-D 














'o 





p 




e 


2 


w 






1 


1 


-rt 


-0 

^u 


^ 


I 


1 

bo 
3 


,fi 

_Q 


u 

M 


i 


'E. 




S 


1 


to 


B 


I 


.a 


u 

J 


i 

CO 




? 


'~t-1 


1 


U 


to 


c 


^ 


a. 




.2 





1 


'u 

to 


1 


CO 

bo 

C 


u 


1 


^ 


T3 


n 


m 
J 


1 


.1 







o 




H 








8 


s 


y 


i 


8 


- 


~ 


^ 


t 


d 


~ 


3 


><"> 





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<VOlHC<VOO 


Elevation. 


H vo O 


M 


voOcJvoOc'voO 

M l-l M 




vo 
O 


00 
CO 


ON vo 


of projectile. 


- 5- 





T$- VO 


} 


i|= - 


00 

ro 



VO 


M 

ON VO 

rt- vo 


No. of Rounds. 


VO VO VO 


uo 


vovovovovovovovo 


Direction 
and force of 
wind. 


J^* 


CO 

<-< 





I 


00 

M 

-J : : 


vo 

oo 

vo 

ti 

3 


S 5 3 5 3 = S 3 


ri 

1 


pq . : 
! : 

o ; 




: : : : : 


h 

o 



6 

! 


4 


e 
>> 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<voO 

VO 00 rj- 10 

VO 6 vo ' - ^ 

VO vo VO co 

^00 Tj- vo 

co t^ vo d 

^O^- VO^^ Hl^^ 

vo vo vo CO 

M vovovovovovovovovo 

VO VO 

VO 

% 

00 JJ 

& I i 

t 

i 



A 3 



* e 

9 C 

3 nl 



510 



ORDNANCE. 



Area of 
rectangle. 


T^ t-^ oo co vo ON TJ- 


M 00 ON 
ON ON * 

00 10 (^ 

to CO 


00 


HI 

ON 

to 


CO 
CO 


to 
to 

CO 


Mean reduced 


M . cl vo O M ON HI 


00 VO CO 


to 


00 


M 


00 


deflection. 


^ cl rh co vo co to 







vo 


CO 


to 


Mean observed 
deflection. 


? H io b M ^ t 

HI co rJ 


to rt- ON 


VO 

o 


oo 


* 

M 


oo 


Mean 
difference of 
range. 


"Ho w t^ to tf vo 

^> 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 

<S 


1 




\ 




ON HI O O 
to vo vo vo 

00 00 00 00 


vg vS 
00 00 


vo 

00 


oo 


vg 
oo 


oo 


.2 

ts 

q 


vo" r . rf t^ 

M HI H Cl 

1 I ' 1; I; 


CO ^ M~ 

a a. 


4 


to 
c* 

-o' 


cf 


CO 

eL 


8 


j j : j -j j j 


: : 




j 


: 




CO 

-Z 




ju | . ;i\. 

1^5 


i | 

* c 

t! - y 

s 

C/3 >-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 -<J- vo M 


Mean reduced 


vo vovooo ONVO O O cl cl 






Mean observed 
deflection.! 


vovo t-^ co oo ON M w t~N co 

^ VOM rt vooo COOO vo H 






difference of 
range.* 


"C vo CO c vo OO M M VO(^ON 

^ t^ t^ vo d co co vo vo vo ** 


S 


OOOVO H ^ O t^COON 
>-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<toOHc 


VO VO 


Mean weight 


Ox rt* vo 

oo- vo - ~ vo-^ ro^ 




ot projectile. 


~ 4- o vo 

VO VO VO 






rf ^ 






" " 




No. of Bounds. 


ONt^vovovOVOt^oO 


vo ON 


Ill 
If 


rfl -S S- S S 3- S- 3 


, s 


O 


oo oo oo oo oo 

M MM MM 

U 
4-1 4-* J-. 4J 4- 

CU CL, CU CL, 
C/3 c/3 S C/5 C/3 


VO 

oo 

0- 


NAME OF SYSTEM. 


! , , , , , J a 

o *-* 

i i 


, , 



o 



RIFLING AND PROJECTILES. 



515 



O 

O 

T 

t-H 

I-H 

O 



H 



O to rj- 

VO VO M 


tO VO W j- T*- 


vo O\ vn 






vo vo ON vo 




T*- tO 


vo to $ 


to vo ON I*** cJ 


" * " 


d ON oo O vo 


00 to VO 


t^ H ^* ^o vo 


vo 00 w 


^J- TJ- M 1-1 tO 


vo to 


t) M VO CO 


to 


O t< O NO oo 


O rt oo 

VO *$ tO 


O to rj- ro H 

rt vo 00 O ON 


M rt O 


^t- to oo t-- oo 


S Jo Z 


M O O O\ oo 
M rl N e< r 


t* f~- to 
w t^ 
rf- to to 


w rt- M VO ON 
M t^, 00 t< t~- 

m M M a 


to to M 


*H rt t^ to ro 


00 00 l-x 


M VO rj- M m 


rl HH c* 


M ON ON oo r^ 


tO tO I-H 


M M M H C* 


ON O vo 

t~^ VO t^ 


5-^225; 


M M tO 
M M 


* ^ ^ 2 M 


O O rt 


vo vo 


- JT 




VO IH 




uo 




o - o 

M 





r- * ^ 


t-^ vo ON t-- vo 


to ^ 3 


^ = ^ - ^ 


vS vS vS 


vS vS vS 


00 00 00 


00 00-00 


VO l~^ ^> 




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 an