52 ANNUAL OF SCIENTIFIC DISCOVERT. 



only be must know its nature. In a bag it is harmless ; exploded in a 

 box it will shatter the gates to atoms. Against the palisades of a for- 

 tification : a small square box containing twenty-five pounds, merely flung 

 down close to it, will open a passage for troops ; in actual experience 

 on palisades a foot diameter and eight feet high, piled in the ground, 

 backed by a second row of eight inches diameter, a box of twenty-five 

 pounds cut a clean opening nine feet wide. To this three times the 

 weight of gunpowder produced no etfect whatever, except to blacken 

 the piles. Against bridges : a strong bridge of oak, twenty-four feet span, 

 was shattered to atoms by a small box of twenty-five pounds laid on its 

 centre ; the bridge was not broken, it was shivered. As to its effects un- 

 der water : in the case of two tiers of piles, in water thirteen feet deep, 

 ten inches apart, with stones between them, a barrel of one hundred 

 pounds gun-cotton, placed three feet from the face and eight feet under 

 water, made a clean sweep through a radius of fifteen feet, and raised 

 the water two hundred feet. In Venice, a barrel of four hundred pounds 

 placed near a sloop in ten feet water, at eighteen feet distance, threw it in 

 atoms to a height of four hundred feet. All experiments made by the 

 Austrian Artillery Committee were conducted on a grand scale, 

 thirty-six batteries, six and twelve pounders (gun-cotton) having been 

 constructed, and practised with that material. The reports of the Aus- 

 trian Commissioners are all based on trials with ordnance, from six- 

 pounders to forty-eight-pounders, smooth bore and rifled cannon. The 

 trials with small fire-arms have been comparatively few, and are not re- 

 ported on. The trials for blasting and mining purposes were also made 

 ,on a large scale by the Imperial Engineers' Committee. 



Sir William Armstrong said it was impossible to listen to the report 

 which had been read without being very much impressed with the great 

 promise there was of gun-cotton's becoming a substitute for gunpowder ; 

 but at the same time there were certain peculiar anomalies about it 

 which he certainly should like to have cleared up, and until they were, 

 they could not feel that perfect confidence in the results that they 

 wished to do. In the first place, with regard to the heat evolved, they 

 were told that, with such a quantity of gun-cotton as would produce a 

 given quantity of gas, a certain initial velocity was imparted to the 

 projectile, and that the heating effect upon the gun was much less than 

 when a similar -velocity was produced by an equivalent quantity of 

 gunpowder. The absence of heat in the gun implied an absence of 

 heat in the gas. Where was the projectile force to come from, if there 

 was no heat in the gas ? He could not, for his part, conceive how it 

 was possible of explanation. The next point that occurred to him was 

 with regard to the recoil. It was stated that the recoil was very much 

 less. That was ascribed to the absence of solid inert matter in the 

 charge, which, in gun-cotton, was next to nothing. If the recoil was 

 only two-thirds that of gunpowder, it would require, in order to account 

 for that difference, a much larger quantity of solid matter than there 

 really was in the case of gunpowder. The report stated that the use 

 of gun-cotton enabled them to reduce the length erf the gun. It was 

 quite certain, however, that with a short gun they could not get an 

 equal initial velocity as with a long gun. If the initial velocity were 

 increased, there was more danger of bursting the gun than with gun- 

 powder. Because, if they got any velocity, or an equal velocity with 



