183 ELEMENTARY PRINCIPLES OF GUNNERY. 



be continuously exerted, so that a large charge of powder 

 exploded, with a light bullet in front of it, will exert less 

 force upon the breech end of the gun, than a smaller charge 

 of powder used to move a larger and heavier ball. So, also, 

 the recoil varies with the same charge when the barrel is 

 held horizontally, and when the muzzle is raised or depressed, 

 being increased in the former position and diminished in 

 the latter, in accordance with the laws of gravity. In shoot- 

 ing from the shoulder, the recoil is apparently increased still 

 more than is really the case when the muzzle is pointed 

 directly upwards, because the body cannot yield as it can do 

 when the butt of the gun is held against the muscles of the 

 chest and arm in a horizontal position. Again, in propor- 

 tion to the weight of the whole piece will the recoil be 

 affected, because a force which will move a body six pounds 

 in weight readily enough will not have the same effect on 

 one of nine pounds or more, having, in the language of 

 science, to overcome a greater degree of vis inertice. Hold a 

 heavy piece of wood or iron in the hand and a severe blow 

 on it will not be felt, while the same, or even a much less 

 force on a much lighter piece would occasion considerable 

 punishment. This fact is well known to all those who have 

 had any experience with guns ; and hence it has been con- 

 sidered necessary, independently of the question of safety, to 

 have all guns made of sufficient weight to give the vis inertice 

 required. It will be found that in proportion to the resis- 

 tance offered by the shot or ball, and to the weight of the 

 whole gun, and more especially at the breech, will be the recoil, 

 but the former is not to be measured by its weight alone, being 

 affected by the friction between it and the barrel. A highly 

 polished surface has a tendency to diminish it, and, on the 

 contrary, a rough one increases it. So, also, if the charge 

 has to be driven through a smaller opening, as in barrels 

 opened behind, the resistance is increased. Again, an ounce 

 of lead causes a much greater amount of friction in propor- 

 tion to the number of pellets into which it is divided, a single 

 spherical ball producing the least, and dust-shot the most 

 friction of all. On this subject I cannot do better than to 

 give in extenso, as far as this point is concerned, a most 

 interesting letter, by Mr. Boucher, which appeared in the 



