428 Mr. Mallet on the Physical Conditions 



SECTIONS. 



PAGE. 



98 Coefficients of expansion of cast-iron and gun-metal, . . .^ . 185 



99 Calculation of the extent of flexure producible in a gun of given length, caliber, 



and material, 186 



CHAPTER XV Numerical Example. 



100 A 32-pounder may bend nearly half an inch 187 



CHAPTER XVI. Relation as to Distortion of Gun-Metal and of Iron Guns. 



101 Why drooping at the muzzle is only noticed in bronze guns; six conditions of 



greater distortion in these than in cast-iron, 187 



102 Baudrimont's researches as to the relation between cohesion and temperature in 



copper and iron, applicable to bronze; an uniformly heated cast-iron gun is 



stronger than a cold one, • 188 



103, 104 Investigation of the relative losses of heat by cooling of bronze and of cast-iron 



guns, 189 



105 Exclusive of the heat carried off by evection, a cast-iron gun cools nearly three 



times as fast as one of bronze, 190 



106, 107 M. Ardent's results as to the ultimate resistance of bronze; distortion of the 



French howitzer in St. James's Park, referred to in example, 190 



CHAPTER XVII. — Effects of Rigidity and repeated Discharge in Iron Guns; 

 Limit to the Number of Rounds. 



108 Nature of the molecular distortions induced by repeated discharge; chiefly affect 



cast-iron guns, 191 



109 Limiting number of fle.xures producing fracture; Hodgkinson's experiments, . . 191 



110 Limit to the number of rounds in a gun, when the value of i is given, .... 192 



111 Limit in relation to wrought-iron, 192 



112 Examples of number of rounds sustained by particular guns; the four general 



conditions upon which the number of rounds that any gun can sustain is 

 dependent, • • '9^ 



113 Uncertainty of statements made on this point arises from neglect of these conditions, 



and especially of the value of r,; misdirection of official researches in looking 

 for gun-metal with great ultimate cohesion, and the neglect of a high coeffi- 

 cient of extension, ' 93 



CHAPTER XVIII General Relations of Elasticity to the Construction of Guns. 



1 1 i General relations of cubic and linear elasticity ; change of volume; change of form, 194 



115 Poisson's relation between linear and cubic extension or compression, .... 195 



1 16 Relation between expansion or contraction by change of temperature, and the pre- 



ceding, due to mechanical force, .190 



117 Expression for extension or compression of the bar L, for unit of length; elastic 



resistance balances the force P; modulus of cohesion, of elasticity, of elastic 

 limit, 196 



118 Proportion of the crippling force to the whole resistance; relation of both to rate 



and time of application ; Vicat's and Franklin Institute's experiments anterior 



to Fairbairn's '97 



119 Poncelet's coefficients, r, and r„ ^ 198 



120 The work done in producing a given extension or compression, 198 



121 The work done if the force be suddenly applied, 198 



