150 Mountin() of Naval Ordnance: 



Now, as soon as the momentum of the gun and carriage, in 

 the action of recoil, is overcome by the tension of the breech- 

 ing, applied at a point D, above the centre of the fore axle- 

 tree, its reacting force, in the direction DB, pulls the mass 

 not only tovrards the ship's side, but also gives it a rotatory 

 motion round the point K, or the fore-axle of the carriage ; 

 and if W = the weight of the gun and carriage, v = velocity 

 of recoil, and y = the line KP, drawn from the point K, 

 {Perpendicularly to the direction DB of the breeching when 

 tight, we have the effort to produce I'otation expressed by 

 yWv. But the stability of the system, With regard to the 

 saliie point K (putting KM = a), is expressed by aW : 

 hence, it depends on the relations which the two quantities 

 1/Wd, and aW, bear to one another, as to the effect the breech- 

 ing Will produce when the recoil is stopped. The tendency 

 ih the case before us, to turn about the fore-axle, can only 

 Vatiish when y or KP = o, or when the direction of the 

 breeching passes through the centre of the fore- axle. If, 

 however, the velocity of recoil be known, the breeching tnay 

 be so adjusted as to make the effort to turn about the fore- 

 axle just equivalent to the stability of the gun and carriage. 

 For example, if a 32-pound shot be fired with an initial 

 t'elocity of 1600 feet per second, from a long gUn, weighing 

 55cwt., mounted on a common carriage, weighing 8cwt. more, 

 it will appear, by making 2/Wi' = aW, and supposing that 

 the ship is Upright, that the quantity y, or the line KP, 

 should be between ^ and i of a, or the line KM, when the 

 effort to produce rotation about the fore-axle is just equi- 

 valent to the stability of the gun and carriage. But although 

 the bi-eeching then ceases to turn the system about the fore- 

 axle, it may, by its direction, exert a lifting force on the 

 fote-part of the carriage, if it be elevated above a parallel 

 to the plane of recoil ; and thus exert an effort to produce 

 rotatory motion about the rear axle : it may, therefore, be 

 generally adopted as a maxim, that to divest the breeching 

 of these mischievous effects in the reCoil, it should never lead 

 thtbugh a point in the carriage more thani of KM above the 

 dentre of the fore-axletree, and be carried to the ship's side, 

 Sb that its direction may be parallel to the deck. The best 

 -way, perhaps, of applying the breeching, according to this 



hence, these short guns require, with regard to the hind truck L, nearly, if not 

 quite, as long a carriage as the longest guns of the same calibre. 



It is also equally evident, that when the deck becomes inclined, and the gun is 

 on the lee-side, that the vertical line GW will still more approach the point K ; 

 and, consequently, the stability of the carriage, with respect to this point, be pro- 

 portionably diminished. On tiie contrary, in a weather gun, it will in like manner 

 De increased. 



