418 
MINUTES OF PROCEEDINGS OF 
It is not surprising that Eobins should have failed to detect all the points 
of a most difficult question on which long experience alone has succeeded in 
shedding but even yet a faint light. The wonder is that, living in the time 
he did, he should have discovered so much. When he took up the question, 
gunnery was not a science, but was very much in the state in which Newton 
found astronomy. The subject had to some extent been treated in a rude 
practical way, and wild speculations had been made as to the nature of the 
forces at play, but the matter had never once been scientifically approached. 
The fact, too, that all his results, obtained with the aid of small-arms, have 
in the main been found to extend to the biggest guns without the discovery 
of any new law, must always make ,Eobins occupy the first place in the 
estimation of every artilleryman. 
The question of the instantaneous explosion -of gunpowder is one of 
extreme importance; for, independently of the increase of the actual amount 
of pressure which it would cause in a gun, it has another bearing on the 
subject of almost equal importance. In a paper read here last year, I have 
given a rigid mathematical demonstration which shows that a sudden 
pressure has twice the destructive action on a gun that the same pressure 
would have if slowly applied. Mr. Mallet* also has illustrated this point 
very clearly, by showing that a weight would bend a support twice as much 
when suddenly applied as it would when slowly applied. Anyone can test it 
with a spring balance. 
Long experience has shown that it lies in our power to vary the rate of 
combustion of gunpowder, and in this gunpowder differs very much from 
gun-cotton. In gun-cotton the instability which renders explosion possible 
is brought about by chemical action, so that atom finds atom in closest 
proximity ready for immediate recombination if only sufficient temperature 
be attained. In gunpowder, on the contrary, the instability is produced by 
mechanical mixture, and, on a minute scale, the particles of charcoal are 
burned like coals in a fire. With gunpowder in its rude state, the .difficulty 
w r as to get the particles close enough together to make the combustion 
sufficiently rapid, and it was not till the importance of thorough incorporation 
was understood that any real progress was made in rendering it a destructive 
agent. Even with thorough incorporation, it was necessary to provide for 
the rapid ignition of the various particles, for the combustion could not 
travel with sufficient rapidity through the entire mass. To make the action 
energetic enough, it was necessary, as it were, to light the fire in a great 
many places. Granulation effects this by allowing the flame from one point 
of ignition to spread throughout the charge and ignite all the grains very 
nearly simultaneously. It also has the good effect of preventing any separa¬ 
tion of the ingredients when once thoroughly incorporated. Thus the action 
depends on the rapidity of ignition of the grains, and the rate of combustion 
of each grain. The rapidity of ignition of the grains depends on the size of 
the spaces between the grains, and the rapidity of combustion on the small¬ 
ness of the grains themselves; but as- these are opposed to one another, we 
can readily see that with some size of grain which is most favourable to 
both requirements the combustion of the whole charge will be the most 
rapid. Small grains will burn rapidly, but the spaces between them being 
^ “ Construction of Artillery.” 
