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instant, so that the grains fired simultaneously inside as well 
as out, the action of the powder would be as quick or 
quicker than the gun cotton. And still further, if besides 
being heated the powder was compressed into a fraction of 
the space it usually occupies, the gases so confined would be 
capable of a still greater pressure. 
Now if the after cartridge were fired and the forward 
cartridge were not ignited by the flash, and considering the 
length and fit of the shot it could hardly have been so ignited, 
then the after shot would be driven forward closing on to 
the forward shot and compressing the powder between until 
the pressure on the forward shot was at least half as great 
as the pressure of the gases behind the after shot, which 
would be between 10 and 20 tons on the square inch. Thus 
the powder would be subjected to a squeeze between the 
two shot such as would result from a blow. It would be 
compressed to a fraction of its former volume. The cubes 
would be crushed into a cake and the work of compression 
would be sufficient to heat the powder far beyond its point 
of ignition. Thus the entire mass of powder would be simul- 
taneously ignited in a highly compressed and heated state. 
The force of such an explosion would be practically unlimi- 
ted and would be located at the very point at which the 
gun burst. Hence in such an action we have ample cause 
for the effect produced. 
But it will be asked why does not the same thing happen 
when a rifle is doubly loaded ? It is said that in that case 
the second cartridge is generally blown out before it ignites, 
and this may be so, for in the rifle the pressure of the gas 
on the shot can never exceed above a twentieth part of what 
it is in the 12-inch gun, and hence in the case of the rifle 
its pressure may well be insufficient to ignite the powder 
between the shot. 
This view of the action resulting from the firing of powder 
by percussion appears to me to be one which it would be 
