$00 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 Eraser, 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 of moderate size, and 
may be employed without fear of fracture. 
