256 F. A. P. Barnard on the Explosive Force of Gunpowder. 
much less rapid than in the first; and observers who have wit- 
nessed the firing of the fifteen inch guns state that the mammoth 
owder grains are visible in full combustion after leaving the 
arger a of sulphuric acid, and a smaller of carbonic. 
Sull, a 
observed velocities correspond to the less windage. And itis 
observed that the effect on velocity of difference of windage 
seems to increase with the charge. It is thus rendered exper 
mentally evident, that it is a great error to make the correction 
for loss of velocity by windage a constant for all charges in the 
same gun. That this is an error was indeed a priori probable. 
It is somewhat remarkable that it should have been so long pel’ 
mitted to stand unquestioned. 
Washington, July, 1863, 
