148 



Mounting of Naval Ordnance. 



From this description of the principle, it plainly appears 

 that the crutch not only becomes the axis of revolution in 

 elevating or depressing the gun when run out^ but also sup- 

 ports the muzzle and prevents it from dropping at the instant 

 the recoil is stopped by the breeching, which mischievous 

 tendency is very strongly developed in the old construction 

 of carriage, and more especially so from the bad manner in 

 which the breeching is applied. Much erroneous discussion 

 has been put forward on this disturbance in the recoil of a 

 ship's gun. Sir W. Congreve, in his ^' Elementary Treatise 

 on the Mounting of Naval Ordnance," attempts to account 

 for it by the breeching being led so as to make two sides AD, 

 DB, of a triangle, of which the third side, AB, is the right 

 line drawn from the loop at the breech of the gun to the ring- 

 bolt B, in the side of the ship ; — thus, he says, exerting a 



lifti?ig force, varying as the line DC ^, on the rear of the 

 carriage, and throwing the muzzle downwards. He thence 

 deduces, that when DC vanishes, or the breeching is a right 

 line from A to B, or any other point on the ship's side, this 

 lifting force will disappear, and the recoil be smooth. These 

 conclusions are evidently derived from insufficient and unsound 

 mechanical reasoning ; for whether the breeching be fastened 

 to the ring D in the side of the carriage, or passes through 

 it to the loop A, at the moment the recoil is stopped the 

 effect will be the same: that is, the action on the carriage is 

 not dependent on that portion of the breeching between the 

 ring D and the loop A ; but depends entirely on the direc- 

 tion and position of that part between the ring D, and the 

 ring-bolt B, in the side of the ship f- 



* We are not told how the line DC is drawn, but imagine that it is intended to 

 be perpendicular to AB. 



f This will immediately be admitted, if we conceive the gun and carriage to fall 

 from the ship's side and to be sustained in its fall by the breeching, in which case 

 B would be the point of suspension, and D the point where the rope ADB is 

 applied-to the mass, whether it termiuates at D, or passes tlirough to A. 



