THE ROYAL ARTILLERY INSTITUTION. 
253 
small-bore (3*3-in.) gun, and consequently with a long cartridge, there 
is every reason to expect that the reverse would be the case; and that 
the tendency of small-grained powder to give a lower velocity with 
relatively large charges, would be aggravated by the increased length 
of the charge—which we must remember is in both guns ignited in the 
rear. But this leads ns to the consideration of another paragraph. 
On the same page (82) the author makes the following remarks :— 
“ For firing reduced charges, such as are used in high-angle practice, 
the 3‘3-in. gun would have the advantage, as the cartridge would be 
longer; and it would perhaps permit the vent being placed 3 ins. from 
the rear end of the bore, and still allow of the residue of the smallest 
cartridge being completely burnt up. This position of the vent would 
also help to give a greater muzzle velocity, as in all probability more of 
the powder would be burnt up.” 
It is, perhaps, scarcely necessary to point out that the difference of 
three-tenths of an inch in the diameter of the bore would have a perfectly 
inappreciable effect upon the dimensions of the reduced charges (4 oz.), 
ordinarily used in high-angle practice with this gun; and that the 
objections to a forward position of vent hold good equally in a 3-in., 
3’3-in., 3‘6-in., or any other field gun. 
These guns are vented in the rear for the double object of ensuring 
safety while firing blank cartridges, and of igniting very reduced charges. 
The author of “ Flat Trajectories ” thinks that a forward position of vent 
in the 3*3-in. gun “ would help to give a greater muzzle velocity, as in 
all probability more of the powder would be burnt up.” Possibly it 
might. 
All the heavy R.M.L. guns are vented forward, and, withR.L .G-. powder, 
a decided increase in velocity is given by igniting the cartridge near its 
centre. Recent experiments, however, have indicated that this result 
may be reversed in the case of lower calibres. 
The muzzle velocity of a 9-lb. shell, fired with If lb. R.L.G. from the 
9-pr. R.M.L. of 8 cwt., is higher when the cartridge is ignited in the 
rear than when it is ignited near the centre. 
Apart, however, from these considerations, and assuming that a for¬ 
ward position of vent would “ help to give a greater muzzle velocity ” in 
a 3‘3-in. gun—-would it not do the same in a 3*6-in. gun ? 
Table II. shows that the muzzle velocity was thus increased by 40 ft. 
It would manifestly have been unfair to vent one gun forward and the 
other gun in rear, and all arguments for or against a change in the position 
of the vent appear to me to apply equally to both guns. 
On the whole, therefore, I think it has been shown that (cceteris paribus) 
the relative velocities of the two guns as given in Table II. would be 
unaffected either by change of powder or alteration of position of vent. 
Let us now examine the next question. The following table, taken 
from “ Extracts from the Quarterly Report of Proceedings of the 
Department of the Director of Artillery,” Yol. IX. pp. 117, 118, gives 
the mean results of the range and accuracy trials with the 3*3-in. and 
3‘6-in* guns. 
