CLASSIFICATION OF MODERN GUNS AND RIFLES. 169 



let go. The string itself, however, is only the passive agent, 

 the active power residing in the bow. This has an elastic 

 property inherent to it by which it strives to resume its 

 original position when it has been drawn from it. So again 

 in the air-gun, ordinary atmospheric air is compressed by a 

 pump, and its elastic property induces its expansion when 

 the pressure is taken off. In both these cases, then, we have 

 a previous compression of an elastic agent, the release of 

 which causes an impulse to be given to the projectile in front 

 of it. In gunnery, however, the elastic agent is naturally 

 compressed into a small space, and when confined in a 

 chamber open in one direction only, and made to expand by 

 ignition, its elastic power is so great as to give a far greater 

 impulse to any body impeding its expansion, than either the 

 bow or compressed air. In the present century, therefore, 

 advantage is taken of this natural agent, and whether in the 

 shape of gunpowder, guncotton, or any other still more active 

 material, in all cases there is an extraordinary impulse com- 

 municated to some projectile which is placed between one or 

 other of these, and the only passage by which the elastic gas 

 resulting from the explosion can escape. 



The conditions at present essential to our branch of gunnery 

 are, first, the existence of a tube of iron capable of being 

 closed at one end, with the exception of a small opening for 

 firing its contents. Within this and at the closed end is a 

 charge of some explosive matter, which may be either gun- 

 powder or guncotton, or any other agent, provided that it 

 will suddenly expand to a sufficient extent when fired by 

 contact with a burning substance. Between this and the 

 muzzle is the projectile, which may consist of one mass of 

 lead or of many smaller ones (in the latter case being called 

 shot), which by the sudden explosion of the powder or cotton 

 is driven in the direction of the long axis of the tube, with a 

 tendency to fall to the earth as it progresses, in conformity 

 with the law of gravitation. 



CLASSIFICATION OF MODERN GUNS AND RIFLES. 



All guns, therefore, consist of a tube more or less cylindro- 

 conoidal, closed at one end, with the exception of a small 



