Guns and Projectiles. 119 



dropped into a barrel which it loosely fits, the moment the 

 powder is ignited it " hammers up." That is to say, its nether 

 extremity receives such a rapid thump that the mass has no time 

 to evade its force by getting out of the way, and consequently the 

 projectile is instantly made thicker and shorter. An iron 

 cylinder would, with an ordinary charge of powder, be so 

 slightly acted upon in this manner, that it would not be driven 

 into the grooves, and if it were so driven, the friction would be 

 tremendous in the subsequent attempt to force it through the 

 barrel. Mr. Lancaster proposed elliptical iron shot, and barrels 

 of an elliptical form, with the major axis twisting in a spiral as 

 it descended. This plan achieved considerable success with 

 rifles and leaden projectiles ; but failed when applied to cannon. 

 General Jacob proposed four-grooved cannon, and four pro- 

 jections or wings from the balls. Sir William Armstrong, 

 with great skill, constructed cannon to fire compound projec- 

 tiles — iron for strength and penetration, and lead to take the 

 rifling, as in small arms. 



It is impossible to look at an Armstrong gun without 

 great admiration for the beauty of its manufacture ; and its 

 performance is astounding for accuracy if compared with 

 most other patterns. Independent, however, of the defects 

 of its method of breech-loading, it seemed marked out from 

 the beginning as a provisional weapon only. Projectiles 

 composed of two metals could only be regarded as substi- 

 tutes for the best mode of making and discharging projectiles 

 made entirely of iron or steel. The grooving of the Armstrong 

 gun, although very beautiful, was a recurrence to a plan not 

 found to be the best in small arms. A multiplicity of small 

 sharp grooves with a moderate twist marked the weapon as 

 likely to lose much power by needless friction, and not to be 

 able to attain a maximum of velocity or range. So successful 

 has Mr. Whitworth been in this matter that, as Sir Emerson 

 Tennent states, " The average initial velocity of a sixty-eight 

 pound spherical shot thrown from a smooth bore, with a charge 

 of one quarter its weight of powder, is 1600 feet in a second, 

 and this it very speedily loses. On the other hand, with a shot 

 of the same spherical form, but rifled to fit the gun, Mr. Whit- 

 worth's obtains an initial velocity of 2200 feet in a second." 

 This increase of velocity is obtained by the accurate fit of the 

 projectile, and consequent prevention of the escape and waste 

 of the gases into which gunpowder is resolved. In the Arm- 

 strong pattern the gain would be less, because the friction is 

 so much more. Sir William estimates the force required to 

 squeeze his twelve-pound shot into the grooves of his cannon 

 at several tons, " whereas in the Whitworth gun, the shot being 

 already rifled and fitted to the bore, it may be started and drawn 

 through the barrel with a silken thread/' 



