334 Sir Andrew Noble [March 23, 



On Fig. II. are placed the results as regards velocity of nine ex- 

 plosives, commencing with the R.L.G 2 powder, which was in use in ' 

 the latter part of the fifties, and terminating with the cordite of the 

 present day. 



The experiments I am now referring to were made in a gun of 

 100 calibres in length, and were so arranged that in a single round the 

 velocities could be measured at 16 points of the bore. The chrono- 

 scope with which these velocities were taken has been already de- 

 scribed, and I will now only say that it is capable of registering 

 time to the millionth of a second with a probable error of between two 

 and three millionths. One curious fact connected with the mode of 

 registration I may mention. In the early experiments with the old 

 powders, where the velocities did not exceed 1500 or 1600 foot- 

 seconds, the arrangement for causing the projectile to record the time 

 of its passing any particular point was effected by the shot knocking 

 down a small steel knife or trigger which projected slightly into the 

 bore ; but when the much higher velocities, with which 1 subsequently 

 experimented, were employed, this plan was found to be unsatisfactory, 

 the steel trigger, instead of being immediately knocked down by the 

 shot, frequently preferred instead to cut a groove in the shot, some- 

 times nearly its whole length, before it acted. Hence another arrange- 

 ment for cutting the primary wires had to be adopted. 



The diagram I am now showing you is, however, both interesting 

 and instructive. The intention, among other points, was to ascertain 

 for various calibres in length in a 6-inch gun the velocities and 

 energies that could be obtained, the maximum pressures, whether 

 mean or wave, not exceeding about 20 tons on the square inch. The 

 horizontal line or axis of abscissae represents the travel of the shot in 

 feet, the ordinates or perpendiculars from this line to the curve repre- 

 sents the velocity at that point. 



The lowest curve on the diagram gives, under the conditions I 

 have mentioned, the velocities attainable with the powder which was 

 used when rifled guns were first introduced into the service ; and you 

 will note that with this powder the velocity attained with 100 calibres 

 was only 1705 foot-seconds, while with 40 calibres it was 1533 foot- 

 seconds. Next on the diagram comes pebble powder, with a velocity 

 of 2190 foot-seconds ; next comes brown prismatic, with a velocity of 

 2529 foot-seconds. 



The next powder is one of considerable interest, and one which 

 might have arisen to importance had it not been superseded by ex- 

 plosives of a very different nature. It is called Amide powder, and 

 in it ammonium nitrate is substituted for a large portion (about half) 

 of the potassium nitrate, and there is also an absence of sulphur. 

 You will observe the velocity in the 100 calibre gun is very good — 

 2566 foot-seconds. The pressure also was low, and free from wave 

 action. It is naturally not smokeless, but the smoke is much less 

 dense and disperses much more rapidly than does the smoke of 

 ordinary powder. Its great advantage, however, was, that it eroded 



