200 FRAGMENTS OF SCIENCE. 



As regards explosive material, and zealous and accom- 

 plished help in the use of it, the resources of Woolwich 

 Arsenal have been freely placed at the disposal of the Elder 

 Brethren. General Campbell, General Younghusband, 

 Colonel Fraser, Colonel Maitland, and other officers, have 

 taken an active personal part in the investigation, and in 

 most cases have incurred the labor of reducing and report- 

 ing on the observations. Guns of various forms and sizes 

 have been invoked for gunpowder, while gun-cotton has 

 been fired in free air and in the foci of parabolic reflectors. 



On the 22d of February, 1875, a number of small guns, 

 cast specially for the purpose some with plain, some with 

 conical, and some with parabolic muzzles firing 4 oz. of 

 fine grain powder, were pitted against 4 oz. of gun-cotton 

 detonated both in the open and in the focus of a parabolic 

 reflector.* The sound produced by the gun-cotton, rein- 

 forced by the reflector, was unanimously pronounced loud- 

 est of all. With equal unanimity, the gun-cotton detonated 

 in free air was placed second in intensity. Though the 

 same charge was used throughout, the guns differed notably 

 among themselves, but none of them came up to the gun- 

 cotton, either with or without the reflector. A second 

 series, observed from a different distance on the same day, 

 confirmed to the letter the foregoing result. 



As a practical point, however, the comparative cost of 

 gun-cotton and gunpowder has to be taken into account, 

 though considerations of cost ought not to be stretched too far 

 in cases involving the safety of human life. In the earlier 

 experiments, where quantities of equal price were pitted 

 against each other, the results were somewhat fluctuating. 

 Indeed, the perfect manipulation of the gun-cotton re- 

 quired some preliminary discipline promptness, certainty, 

 and effectiveness of firing, augmenting as experience in- 

 creased. As 1 Ib. of gun-cotton costs as much as 3 Ibs. of 

 gunpowder, these quantities were compared together on the 

 22d of February. The guns employed to discharge the 

 gunpowder were a 12-lb. brass howitzer, a 24-lb. cast- 

 iron howitzer, and the long 18-pounder employed at 

 the South Foreland. The result was, that the 24-lb. 

 howitzer, firing 3 Ibs. of gunpowder, had a slight ad- 

 vantage over 1 Ib. of gun-cotton detonated in the open; 



* For charges of this weight the reflector is cf moderate size, and 

 may be employed without fear of fracture. 



