1862.] and Military Applications of Explosions. 443 



the simultaneous ignition of numerous charges of gunpowder by 

 electricity of high tension : by means of one of them, recently dis- 

 covered, many mines may be simultaneously discharged, even by the 

 employment of small magneto-electric machines ; the necessity for 

 the employment of voltaic arrangements in mining operations being 

 thus entirely dispensed with. 



One of the most highly explosive mixtures at present known, 

 consisting of chlorate of potassa and amorphous phosphorus, has been 

 most ingeniously applied by Sir William Armstrong to the ignition of 

 his time-fuzes, and to the production of concussion and percussion- 

 fuzes, remarkable for the great ease with which they are exploded. 

 The above mixture may be ignited by the application of a gentle heat, 

 or by submission to moderate pressure ; if it is made up into a hard 

 mass by mixture with a little shellac-varnish, the friction resulting 

 from the rapid insertion of a pin's point into the material suffices 

 to ignite it, even when it is well covered with varnish. Thus, in 

 Armstrong's time-fuze, which, when fixed in its place in the head 

 of the shell, cannot, like ordinary fuzes employed in smooth-bore 

 guns, be ignited by the flame of the exploding charge of powder (as 

 the shell accurately fits the bore of the gun), the fuze-composition is 

 inflamed, immediately upon the firing of the gun, in the following 

 manner : — A small quantity of the phosphorus-mixture is deposited at 

 the bottom of a cylindrical cavity in the centre of the fuze, and over it 

 is fixed a small plug of metal, with a pin*s point projecting from its 

 lower end. This plug is held in its place by a pin of soft metal, which 

 by reason of the vis inertice of the plug, is broken when the gun is 

 fired, and the pin then instantly pierces the pellet of detonating mix- 

 ture, which, by its ignition, sets into action the time-fuze. The dis- 

 tance between the pin's point and the phosphorus-mixture, before the 

 explosion, is only one-tenth of an inch. This arrangement exemplifies 

 in a striking manner the delicacy of action which may be obtained by 

 a judicious combination of simple mechanical arrangements and highly 

 explosive materials. 



The variety of work accomplished by the explosion of a charge of 

 powder in an Armstrong gun loaded with a shell — no less than five 

 distinct and important operations being thereby effected before the 

 shell leaves the gun — affords a most interesting illustration of the pro- 

 gress made in the application of explosives, and of the comparatively 

 great control which may be exercised over the operations of those 

 destructive agents. 



[F. A. A.] 



