SHORT NOTES ON PROFESSIONAL SUBJECTS. 
145 
The 8-inch. Experimental Gun No. 288, is unchambered, and the pressures 
indicated at A in this gun are not relatively so high as those indicated at the 
same point in the 10-inch gun. 
On the whole, the Committee are disposed to look upon the pressure at A as 
intensely local, and as not representing the actual or average pressure over the 
entire bottom of the bore. 
They think, however, that the pressures at B and G give a very fair measure of 
the pressure in the powder-chamber. 
When firing battering charges of pebble powder in M.L.R. guns up to and 
including the 12-inch of 25 tons, this intense local action at A disappears, and 
the pressure over the whole of the powder-chamber seems to be uniform. 
The experiments carried out with the 10-inch gun before being rifled may be 
summarised thus, including 6 rounds (4 with pebble and 2 with R.L;G.) fired for 
velocity before the fittings of the gun were completed :— 
Powder. 
Charge. 
Number of 
rounds. 
I 
-Amount of 
powder. 
lbs. 
lbs. 
R.L.G. 
60 
30 
1800 
L.Gr. 
60 
6 
360 
Pebble . j 
70 
60 
43 
2 
} 3190 
v 
( 
70 
6 
J 
Pellet .■) 
65 
1 
f- 1829 
64 
21 
) 
70 
1 
Prismatic.< 
68 
1 
£ 870 
l 
61 
12 
) 
Total. 
... 
123 
8049 
(B.) 10 -inch Experimental Gun } No. 375 , Rifled. 
In rifling this gun, the number of grooves had to be restricted to two, in order 
to avoid interference with the numerous plugs fitted into it. The rotary motion of 
the shot on its own axis has consequently to be imparted by only two driving 
surfaces instead of seven, and the result is that the edges of the grooves have a 
tendency to become slightly burred and set up. This sometimes interferes with 
the loading, as the windage is very small; but no other inconvenience or difficulty 
has been experienced since the rifling was introduced. 
29 rounds have been fired from the gun in its rifled state—viz., 17 of R.L.G., 
charge 60 lbs., and 12 of pebble, charge 70 lbs. The mean velocities and pressures 
were as follow:— 
r Curtis & Harvey ... densitv 1-675! 1325 
K.L.G., 60 lbs. ) Abbe J'„..••••• 
i Ditto, re-worked from Pigou and ) 
L Wilks L.Gr.J 
Pebble, 70 lbs., Waltham Abbey £ I)ate > ^ 
1-743 
Muzzle 
j velocity. 
Pressure by 
crusher gauge at 
A. 
B. 
a 
f.s. 
tons. 
tons. 
tons. 
1325 
534 
32 
26 
1312 
37i 
30| 
264 
1337 
434 
29| 
274 
1423 
21 | 
204 
204 
1383 
204 
20 
20 
