432 Proceedings of the 



wrought and cast iron of different forms, confirmed the fact, that 

 shots discharged with tlie magazine within them were projected with 

 a force greatly exceeding that which the same quantity of gunpow- 

 der applied in the usual way would effect. 



Mr. Brockedon attempted to account for this greater force by sup- 

 posing that the power usually wasted in the recoil of the gun, was 

 added to the force by which the shot and mandrel were separated. 

 He stated, that no recoil in common gunnery took place, until the 

 shot had left the cannon ; and offered the following proofs of this 

 fact. It is a common practice to fire a cannon suspended from 

 triangles": the mark against which it is directed, being hit, if any 

 recoil had taken place before the ball left the cannon, the ball 

 must have struck some other point tangential to the circle which 

 its point of suspension would describe. Mr. Brockedon men- 

 tioned that Mr. Perkins, in the course of some experiments upon 

 recoil, had fastened a loaded rifle barrel to the edge of a horizontal 

 wheel, which moved freely upon a vertical axis ; the rifle was 

 directed, and hit the mark, though the recoil whirled the rifle and 

 wheel round with great velocity. Mr. Brockedon illustrated this 

 further, by supposing a boat on still water, and imagining a plank 

 placed from stem to stern, and a man on it pushing with a pole a 

 bundle of hay from him along the plank, the separation of the hay 

 from the man could not affect the situation of the boat on the water, 

 whilst the hay was on board ; but if the hay were thrust over, the 

 moment it became independent of the boat, the man and boat would 

 separate from the hay with forces proportioned to their densities. 



The space required to contain the products of the combustion of 

 gunpowder, has not been determined by careful experiments, but 

 vaguely stated by some at 500, by others at 1000 times the volume 

 of the powder ; taking the lowest statement, and supposing a car- 

 tridge to be six inches long, and the length of the gun to be five 

 feet, not more than about 3^^°^ of the force generated by combustion 

 operate upon the ball : the remaining l^g^^ths are wasted upon a re- 

 coil, which, overcoming the vis inertiae of the gun with its carriage, 

 (which weighs between three and four tons for a 24-pounder,) will 

 drive it back in garrison service against an inclined plane 18 inches 

 or two feet. The instant the ball leaves the gun the recoil takes 

 place, and the products of combustion, which remain within the gun 

 in a highly condensed and heated state, are opposed in their escape 

 by the vis inertiae of the external air from which the gun recoils. If 

 recoil were attempted to be explained simply upon action and re- 

 action, by the intervention of a force separating two bodies, whose 



