302 Mr. Mallet on the Physical Conditions 



wholly upon the assumption, that there is no other possible mode 

 of absorbing recoil, except by the crude expedient of mass in the 

 gun ; and loses sight of the many important advantages which 

 lightness can confer, taken in just connexion with all other rela- 

 tions (Note BB) ; nor is it an inevitable consequence of increased 

 strength of material, that in every case the weight shall be reduced 

 in the inverse proportion. 



3". That a given number of rounds produces a greater enlargement of 

 bore, in the ratio of nearly 2:1, than in gun-metal, and hence 

 uncertainty of range, aim, &c. This result, deduced from the 

 utterly insufficient data of one set of experiments with a 6-pounder, 

 is merely a misstatement as to the general fact, as the preceding 

 pages have probably sufficiently proved. 



4^ That from want of hardness in wrought-iron, as compared with 

 cast-iron and gun-metal, a seriously objectionable amount of rifling 

 and ballotage, or pitting, from the passage of the shot, is to be 

 expected, and, therefore, from this and the following cause, a 

 defect of durability. This also is contrary to all the facts of the 

 case. Wrought-iron is much harder than gun-metal in resisting 

 abrasion, as the fact known to every one, that the gun-metal 

 bearings of axles, such as those of railway carriages, wear much 

 faster than the wrought-iron axle proves ; they are for this very 

 reason, made of gun-metal, to save the wear of the axle at their 

 expense. Cavallo's experiments (Nat. Phil. vol. ii. p. 147) also 

 prove this directly. As respects cast-iron, the difference is almost 

 inappreciable between cast-iron best fitted for guns, and wrought- 

 iron, and in favour of the latter in too many instances from the 

 undue softness and friability of the cast-iron employed. 



36. — Particular Conditions of Wear of Guns in Service. 



306. The wear in service of every gun is made up of the riffing out of the 

 whole length of the chase by the passage of the shot, and of the ballotage, or 

 pitting, produced by the stroke of the shot, which, for shot of the same caliber 



