324 Mr. F. J. BramweU. [Feb. 27, 



In fact it must be made as shown in Diagram (18). This would have 

 the result of adding 12 tons to the weight of the gun, or in other 

 words to provide against an extremely remote probability — a proba- 

 bility which, small as it is, can be diminished, as the Committee 

 pointed out, by a simple appliance, until the probability comes to the 

 verge of an impossibility — it is suggested that the 38-ton gun should 

 be made into a 50-ton gun, while only retaining the efficiency of a 

 38-ton gun. 



These considerations have I trust convinced you of the practical 

 impossibility of attempting to make a 88-ton gun fit to carry two 

 charges placed in the position which they would occupy when the 

 gun is double-loaded, even assuming that the forward charge in that 

 position exploded with no more effect than it would have produced if 

 placed at the base of the barrel, and fired in the ordinary manner. But 

 everything points to the conclusion that the forward one of the two 

 charges when fired explodes with a violence far in excess of anything 

 that would result from its being fired as a single charge. 



Assuming, as is most probable, that the ignition takes place from 

 the flash of the hinder charge, and from that alone, this flash would 

 certainly proceed along every one of the rifle grooves, so that in nine 

 equal spaces round about the circumference and for the whole length 

 of the cartridge would ignition take place, instead of its occui'ring at 

 one point only, that of the firing tube of the ordinary charge, and 

 further when the powder was thus fired it would be highly compressed 

 by the forward movement of the hinder projectile. 



The specific gravity of gunpowder without any air space whatever 

 may be taken at IJ times that of water, or 16 cubic inches to the lb. 

 The space allowed for its combastion is 30 inches to the lb., but by 

 the time the cartridges are rammed home this is perhaps contracted 

 to 27f inches, or in other words the space then allowed for a given 

 weight of powder is thus just equal to that which would be required 

 to contain an equal weight of water. 



Captain Noble on one occasion exploded in a close vessel, powder, 

 when the space it occupied was such as to represent the density of 

 li times that of water. The result was the raising of the pressure from 

 43 tons, which such powder had when fired in a close vessel giving a 

 space of 80 inches per lb., to 59 tons, so that the diminution of space 

 from that which occurs with the gravity of -925 to that which occurs 

 with the gravity of 1 * 2 was sufficient to make an increase in pressure 

 of 37 per cent. 



But one knows that the front charge of powder when acted upon 

 by the rear shot urged forward by a pressure of some 2500 tons would 

 be so driven together as to obliterate practically all air space, and 

 thus to bring the powder up to its full specific gravity of 1 j times 

 that of water. The result of an explosion from powder thus com- 

 pressed I do not pretend to off'er you in tons, but looking at what 

 happened from the firing of powder of 1} times the density of water, 

 it is clear the pressure must be enormous. In a small gun the 



