Royal Institution of Great Britain, 433 



resistances were as their densities, then the recoil would prevent any 

 certainty of striking the point or mark against which the cannon is 

 directed ; contrary to the effect proved by firing from triangles, Mr. 

 Perkins's experiments, and the practice of every sportsman. The recoil 

 too takes place, whether the firing be with blank or ball cartridge ; 

 if the recoil be greater with a ball, it arises merely from the resist- 

 ance which this offers to the discharge, allowing time for the more 

 complete ignition of the gunpowder, and the generation of a greater 

 force ; henc6 also the effect of a rifled barrel, and the recoil of a 

 foul gut^.*^*'"-* ^'" '«<»*^'""> •'' '^^^ «^> f.:)?i }*n.| /vom 



The sky-r6dket illustrates also this theory of recoil. To increase the 

 surface of the composition exposed to combustion, the rocket is bored 

 conically nearly to its entire depth, the products of this combustion 

 are met by the atmosphere as they rush from the neck of the rocket, 

 and recoil from the resistance ; as the cone enlarges, the force in- 

 creases, and accelerates the ascent of the rocket, poised and directed 

 as it is by the rod. The difference between the effects of the rockets 

 and the shot is, that in the former the force increases from the gra- 

 dual, but increasing surface in combustion ; in the latter, the force 

 is at once generated, and the aid to the force which separates the 

 shot from the mandrel is greatest at first, and though gradually les- 

 sening, always adds something to the force of the discharge, until 

 the air within the calibre is equalized with the atmosphere. 



The father of the late Sir Wm. Congreve tried some experiments 

 with shot fired from a mandrel ; but as he bored the mandrel into 

 which the discharge was put, and did not put the magazine in the 

 chamber of the shot — they failed. 



As the expense of trying experiments with Mr. Sieviere's engines 

 is too great for an individual to incur, the probability of its becoming 

 a most destructive engine in warfare ought to recommend it to the 

 serious attention of government. The advantages of the lightness 

 of the mandrel and the unlimited weight of the projectile are im- 

 mense. When the experiment was made with the 25-pound shot, an 

 invalid watchman carried the cannon shot and ammunition upon his 

 head to Primrose Hill, before breakfast ; and the safety of the engine 

 to those employed in its use may be shown in the fact, that the shot 

 which burst did no injury to the gunner ; and no mischief -could 

 happen : for if the shot burst without advancing from the mandrel, 

 the fragments dispersed at right angles, and if with any projection, 

 in lines resulting from the united forces, leaving the gunner in safety. 

 The recoil of the mandrel is very small, and arises only at the mo- 

 ment of separation from the pressure of the gases, which, escaping 



