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MINUTES OF PROCEEDINGS OF 
Lead coating is the only method that has been used in our service 
with breech-loading guns, but it is not a necessary consequence ; for 
we find that on the continent, where breech-loading prevails, though 
the Russians, Prussians, and Austrians use lead coating, the French do 
not. In deciding between these two systems, it is a point of great 
importance to know what is the maximum initial pressure of gunpowder 
in the bore. One of the chief dangers, in using lead-coated projectiles 
with very heavy guns, will be the stripping of the lead. It can hardly 
be doubted that the moment of first starting is that at which this is 
most likely to take place, when the shot begins to take the grooves, 
and when the pressure is the greatest. Not only does the pressure per 
square inch increase with the size of the gun, but another law acts 
adversely; for the mass rotated increases as the cube of the calibre, 
while the lead-coated surface which produces rotation increases only as 
the square of the calibre. We know, however, that lead coating is safe 
with a 7-inch gun and our present gunpowder. If the initial pressure 
can be reduced to one-half, a 15-inch gun could be made as safe in this 
respect as a 7-inch gun at present is. A committee is now sitting on 
the question of gunpowder, and has already issued a preliminary report 
showing that, by a modification of the size and shape of the grain, the 
initial pressure can be reduced to about one-half. This is for smooth¬ 
bore guns and windage. It would be very useful to know whether the 
same results hold good with lead-coated projectiles where there is 
rifling and no windage. The gun I propose would be a useful means of 
determining this; for, as designed for service, it will fire out its breech 
at the rate of 15 miles an hour. By reducing the size of the breech to 
one-fourth, it could be made to retire along a railway at the rate of 
60 miles an hour; and, while it retired, a record could be obtained 
from it on a revolving cylinder, which would give a curve, continuous 
throughout, from which the spaces described in given times could be 
measured, and so the velocities and pressures deduced.* 
Before adopting rifling by lead coating with a very heavy breech¬ 
loading gun, it would be necessary to know what is the initial pressure 
under the exact circumstances to be used. The initial pressure should 
be as much reduced as is consistent with the maintenance of initial 
velocity. In itself, however, lead coating has the effect of increasing 
the initial pressure; for it gives no relief by windage, and the com¬ 
pression and friction of the lead coating give considerable retardation, 
so as still further to increase the pressure. There is also to be added 
the resistance which is produced by the necessity of having an uniform 
twist. All these causes act, not only in a degree which can be mathe¬ 
matically calculated, but also, in an uncertain degree, by affecting the 
explosion of the gunpowder, so that nothing but experiment can be 
depended on. 
Lead coating has one very great advantage. It is the best method 
of preventing windage; and, as windage has the effect of scoring the 
* This was suggested to me three years ago by the Rev. F. Bashforth, Professor of Mathematics 
to the Advanced Class of Artillery Officers at Woolwich. 
