involved in the Construction of Artillery. 43 



(J 



SECTIONS. PAGE. 



249 Necessary still to learn the actual time of combustion of both, 271 



250 Relations of force transmission, and of ductility of the material of the gun, to gun- 



cotton explosion ; wrought-iron would make the best field-guns for gun-cotton 



ammunition, 272 



2.51-252 Effects of gun-cotton explosion on cast-iron guns, 271 



CHAPTER XXX. — Material of the Gun in Rel.^tion to the Chemical Action 



OF THE Charge. 



253-255 Products of the combustion of gunpowder and of gun-cotton; their respective 



chemical actions on cast-iron, wrought-iron, and gun-metal, 273 



256 Enlargement of the vent in great part a chemical action ; a true deflagration of the 



carbon and iron copper vents; new vent suggested, 273, 27-J 



CHAPTER XXXI. — Of the Position of the Trunnions upon the Strength of 



THE Gun. 



257 Action of the recoil in stretching the metal of the gun, 274 



258 The longitudinal strain upon the gun by recoil when the breech abuts against a 



fixed point, 275 



259 When the gun is quite free, 275 



26() When fixed rigidly on trunnions, 275 



261 The longitudinal strain of recoil is a minimum when the gun has no trunnions, but 



abuts against the breech, 275 



262 Strains in three directions always act on the gun, two of which increase the distress 



due to the third, 276 



263 Effects of compressive or extending strains normal to the faces of a prismatic bar; 



upon its resistance to tension in lieu of its length; Barlow's, Vicat's researches; 



the least distressful mode of mounting a gun, 276, 277 



CHAPTER XXXn General Comparison of the Constructive Constants of 



THE Materials for Ordnance. 



264 Table XIV General Table of the physical properties of the principal materials of 



construction for ordnance from British data, 277 



Table XV. — Comparison of weight, strength, extensibility, and stiffness, cast-iron 



being unity within practical limits, 278 



Table XVI Molecular properties of the principal materials for the construction 



of ordnance 278 



Table XVII Comparative financial relations of the principal materials for the 



construction of artillery, 277, 278 



265, 266 Discussion of the Tables; general results; wrought-iron superior to all other mate- 

 rials in strength, in durability, in cheapness, in cost of transport in service, 279, 280 



CHAPTER XXXIII. — Op the Proper Construction of <Juns in Wrought-Iron 



OF THE Largest Class. 



267 The difficulties of manufacture in wrought-iron; guns up to 12-pounder3 might 



be rolled, 280 



268 Smaller guns may be forged by hand even ; Pottinger and Mallet's early wrought- 



iron guns; peculiar construction and value in certain circumstances, . . . . 280 

 269, 270 Rolled wrought-iron tubes ; Table XVIII. ; experimental strengths of Birmingham 



Tube Company's tubes; great strength; causes, 281 



