BRITISH ASSOCIATION. 43 



The reports of the Austrian OommissioDers are all based on trials with ordnance, 

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

 trails with small fire arms have been comparatively few, and not reported on. 

 The trials for blasting and mining purposes were a^.so made on a large scale by 

 the Imperial Engineers' Committee, and several reports have been printed on the 

 subject. 



Sia W. 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 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 velo- 

 city 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, con- 

 ceive 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 gun- 

 powder, 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 of 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 gunpowder. Because if 

 they got any velocity, or an equal velocity with the shorter gun, it must be con- 

 cluded that it was done by virtue of a greater initial pressure and an earlier 

 action upon the shot. That necessarily implied a greater strain upon the gun at 

 the first explosion, and that would necessitate the employment of stronger guns. 

 He should have expected a smaller velocity by a shorter gun, for the action of 

 the gas was necessarily shorter than in a longer gun. The heat question, 

 however, was to him the greatest puzzle of all. How they could have the propel- 

 ling power without heat in the gas, and if they heated the gas, how they escaped 

 heating the gun, he could not understand. — Prof. Pole said he was quite unable 

 to give any explanation of the difference of recoil. If the shot left the gun with 

 the same velocity as when fired with gunpowder, it was natural to suppose that 

 there must be the same quantity of recoil. — Mr. Siemens having briefly spoken oa 

 the dynamical question involved in the matter, suggested that the greater heat 

 imparted to the gun in the case of gunpowder might be owing to the greater 

 amount of solid matter, which taking up the great heat of the gases under a 

 pressure of some 400 atmospheres imparted a portion of the same by radiation to 

 the side of the gan, while in the case of gun-cotton gases only were produced, 

 which could only impart heat to the gun by the slower process of conduction, and 

 left a larger margin of heat to be developed in force by expansion. — Admiral Sir 



