THE ROYAL ARTILLERY INSTITUTION. 
201 
to fill before it acts on tlie ball; tliis latter, therefore, when stirred from 
its place, is actuated by a greater pressure than if it were moved by the 
ignition of the portions of the charge immediately next it. (3) There 
is supposed to be less force lost by the vent, but I am unable to see why. 
(4) Actual experiment with a musket in 1817 ( Memor . de I’Artillerie, 
Part IV. p. 244), is said to have shown that with the length of charge 
divided into 18 parts, the greatest velocity was given with the vent at -^th 
from the back end, and the greatest recoil with the vent half-way up the 
charge. 
“ The first of these reasons is the only one that seems entitled to much 
respect; with very heavy elongated shot it is an actual advantage to 
overcome their inertia before a great force of gas comes upon them; 
it reduces the tendency to form dents in the bore, and reduces generally 
the strain on the sides and bottom of the bore. These shot have a much 
lower initial velocity than round shot, there is after all as much, and often 
more time for the combustion and the expansion of the gas by its own 
heat, before they leave the bore, even if they should move sooner, than if 
they were round shot. 
“ Experiments with a musket using Erench powder, of whatever sort it 
might have been, are evidently no guide whatever for the behaviour of a 
charge in a gun of 7 to 13 inches calibre, with 2A 4 powder, or any 
other very large grain, in very long charges, with a very heavy column to 
move, and with the retardation of rifling to overcome. 
“ If these remarks are well founded we may be sure the subject will soon 
be taken up again, and it appears a peculiarly suitable one for the Ordnance 
Select Committee to take the initiative in. 
“ The course I propose is to take a muzzle-loading wrought-iron or bronze 
rifled gun, with charge exactly two calibres long, and shot exactly double 
the weight of the round shot. To divide the length of the charge into 
ten equal parts, and have vents at 0—1—2—4—6—8, &c. so arranged 
that only one shall be open at a time, the rest closed by a screw plug 
down to the bottom; and to fire five rounds with each, of three sorts 
of gunpowder, total 120 rounds, ascertaining the velocity with Navez's 
apparatus. 
iC If there is any law of velocity depending on the position of the vent, 
this will no doubt bring it out, and if it affects one kind of gunpowder 
rather than another, we shall discover it, and have something better than 
prescriptive custom to guide us in fixing the best position of the vent of 
the new family of large guns which are now about to commence their 
career/"’ 
9. Erom experiments made in Erance with small arms about the year 
1828, Colonel Duchemin was led to believe that the best position of the vent 
is at 1 to | the length of the cartridge measured from the bottom of 
the bore* 
Hutton's experiments are detailed in Tract 34, Section 86. 
* Memorial de l’Artillerie, No, 4, p, 233, 
