142 



either endowed with vegetable life, or subjected to the will of an ani- 

 mated creature. 



3. Within a finite period ol time past the earth must have been, 

 and within a finite period of time to come the earth must again be, 

 unfit for the habitation of man as at present constituted, unless 

 operations have been, or are to be performed, which are impossible 

 under the laws to which the known operations going on at present 

 in the material world are subject. 



3. On Rifle Cannon. By Captain Davidson, Bombay Army. 

 Communicated by Professor C. Piazzi Smyth. 



This paper was written in India as far back as 1839, but many 

 of its suggestions were still untried, and present circumstances seem 

 to urge their importance. 



The I'ecent improvements in the hand-rifle have so greatly in- 

 creased the practical range of that instrument, as to have passed and 

 left far behind, in point of range and precision, the heavy field pieces 

 which heretofore have done accurate execution at distances imprac- 

 ticable to small arms. The large guns therefore imperatively require 

 to undergo the same alteration which, by converting the musket into 

 a rifle, has so greatly increased the directness and accuracy of the 

 flight of its ball. 



Rifling has already been tried on cannon, but not with success ; 

 and Captain Davidson's paper merely professed to give an im- 

 proved method of applying the principle. This he effected by in- 

 serting into the sides of the shot or shell, ribs of wood, to fit into the 

 rifle grooves of the bore. In this way he considered that the neces- 

 sary rotation would be given to the ball, without the usual error of 

 tearing and destroying the figure of the interior of the gun ; the 

 soft wooden ribs, and not the hard cast-iron of the Captain's projec- 

 tiles, alone coming into contact with the bore. 



To this method of rifles he proposed also to join the conical form 

 for the pi'ojectile, fired with the small end first, and to make the 

 shells self-exploding, by a percussion cap on the exti'emity. 



Having entered somewhat into the principle and history of rifle 

 pieces, the Captain gives the concluding portion of the pamphlet on 

 the same subject by Mr Robins, the Newton of gunnery, as valu- 

 able in itself, and strangely unattended to through more than half a 

 century. 



