THE APPLICATIONS OF EXPLOSIVES. 



447 



iiAll.iiiiAD TuKPEIXIKS KAS'IKXEll m.\ KaIL. 



slight. At the ISTaval Ordnance Proving Ground, so long ago as 

 1884, repeated charges of dynamite, varying from five pounds to one 

 hundred pounds in weight, 

 were detonated on the face 

 of a vertical target con- 

 sisting of eleven one-inch 

 wrought-iron plates bolted 

 to a twenty-inch oak back- 

 ing, nntil 440 pounds of 

 dynamite had been so deto- 

 nated in contact with it,- 

 and yet the target remained practically uninjured; while at Braam- 

 fontein the accidental explosion of fifty-five tons of blasting gela- 

 tin, which was stored in railway vans, excavated but 30,000 tons of 

 soft earth. This last may seem a terrible effect, but the amount 

 of explosive involved was enormous and the material one of the 

 most energetic that we possess, while if we compare it with the 

 action of explosives when confined its effect becomes quite mod- 

 erate. Thus at Fort Lee, on the Hudson, but two tons of dyna- 

 mite placed in a chamber in the rock and tamped brought down 

 100,000 tons of the rock; at Lamberis, Wales, two tons and a half 

 of gelatin dynamite similarly placed threw out 180,000 tons of 

 rock; and at the Talcen Mawr, in Wales, seven tons of gunpowder, 

 placed in two chambers in the rock, dislodged from 125,000 to 

 200,000 tons of rock. We might cite many such examples, but on 

 comparing these we find that the gunpowder confined in the inte- 

 rior at the Talcen Mawr was over forty-two times as efficient as 



the explosive gelatin on the 

 surface at Braamfontein, 

 while the dynamite at Fort 

 Lee was over ninety times 

 as destructive. 



Considerations similar to 

 these led me, in 1885,* to 

 point out that high explo- 

 sives for use in shells must 

 be strongly confined, and' in 

 the attack on armored ships 

 they should be fired in projectiles that can " either penetrate the 

 armor partially and explode in place or pierce it completely and 

 burst inside the ship " to secure the greatest efficiency. This re- 

 quires that the projectiles shall be fired at higher velocities than 

 can be imparted to them by guns- of the kind just described, and 

 * Van Nostrand's Engineering Magazine, vol. xxxii, pp. 1-9, 1885. 



Steel Disks i pon which Gln ('otton has been 



DETONATED TO TEST THEIR EeSISTANCE TO 



Shock. Midvale steel disks after second fire. 



