THE EOYAL ARTILLERY INSTITUTION. 
251 
It appears from the last table that the figures 1283 belong to an 
inferior description of powder, marked “Examination 1870,” and that 
good L.G. powder gave a velocity somewhat exceeding that of R.L.G. 
The author of “ Flat Trajectories ” would scarcely have selected these 
figures had he been aware that their publication was the cause of a 
lengthened correspondence between the Departments concerned, in 
the course of which the Superintendent Eoyal Gunpowder Factories 
stated “that the L.G. powder issued to Shoeburyness (marked ‘from 
examination 1870 ; ), cannot be said to represent fairly the present 
service stock of L.G. powder, which has been brought into general use 
for M.L.R. field guns (see § 2087 List of Changes ), as it was obtained 
from broken up cartridges and powders of unknown dates and makers;” 
and the Secretary of the Experimental Branch at Woolwich submitted 
“ that steps should be at once taken— 
“1. To ascertain how such powder came to be issued to Shoeburyness. 
“2. To replace the present store by a portion of the 2000 barrels of 
Pigou & Wilkes L.G. at Purfleet, which has been reserved for re¬ 
working, but not now likely to be required for that purpose. 
“3. To set aside 500 barrels of L.G. at Purfleet for issue to Shoe¬ 
buryness as required.”* 
It is manifest from the above that this particular brand of L.G. 
powder was of an exceptional character, that in some unaccountable 
manner had found its way into the Shoeburyness magazines. 
The foot note to Table III. expressly points out that the powder 
“was from broken up cartridges.” The same table gives results from 
an unexceptional brand of L.G. powder. 
I think, therefore, had the author of “Flat Trajectories” taken 
1359 instead of 1283, he would have selected figures that more correctly 
represent the normal velocity given by 31b. of L.G. powder in the 
3’6-in. gun. 
But, apart from figures, let us consider on theoretical grounds how 
the velocity would be likely to be affected by the size of grain of the 
powder. 
Major Majendie, remarking on the influence of the size of grain, 
says at p. 133 of his “ Treatise on Ammunition” :—- 
“When a charge, of powder is ignited, each grain in its turn becomes 
ignited over the whole surface, and continues burning in concentric 
layers until it is consumed. It is evident, therefore, that as a large grain 
will take a longer time to burn in this way than a small one, so, all other 
conditions being the same, a charge made up of large grains will take 
longer to burn than the same charge made up of smaller grains. But 
the rate at which the grains successively become ignited will also be 
affected by the size of the grains; and here the effect will tend in the 
opposite direction to that just described; for as all the interstices 
through which the gases pass decrease as the size of the grain decreases 
(all other conditions being the same), the velocity of ignition will also 
proportionally decrease, and in a measure counterbalance the effect 
Proceedings, Director of Artillery,” 1871, p. 309. 
