HOW GUN-BARRELS ARE MADE. 20J 



arrangement are worth noticing. Both barrels being 

 subject to the same line of sight, it follows that, as they 

 are placed horizontally, the bore of each barrel must 

 incline inwards. The extent of this inclination is such 

 that in guns of good quality the shot from both barrels, 

 supposing both barrels to be discharged simultaneously, 

 would cross each other at the distance of about forty 

 yards. It will be observed in all guns that the thick- 

 ness of the barrels is much greater at the breech than 

 at the muzzle ; and in order to conform the inclination 

 of the bore to the line of sight, it becomes necessary 

 to so adjust the breech ends of the barrels that the 

 proper convergence of each charge shall be secured. 

 This result is secured by reducing the thickness 

 of the breech of each barrel at the point of con- 

 tact. The extent of the reduction is about one half 

 the thickness of the breech of each barrel, leaving be- 

 tween the two bores of the barrels, when placed side 

 by side, the thickness of the breech of one barrel. 

 On account of this reduction of the thickness of the 

 barrels at the breech, it is undesirable, to say the least, 

 to discharge the two barrels simultaneously. In any 

 gun the recoil would be unpleasant, while in the 

 cheaper class of weapons the great strain of the simul- 

 taneous explosion is likely to be greater than the bar- 

 rels can stand. 



The materials of which the higher qualities of 

 gun-barrels are made are worth knowing; and as I 

 cannot be expected to add anything of value on this 

 subject to the published statements of Mr. William 

 Greener, in his various treatises on the science of 



