SHORT NOTES ON PROFESSIONAL SUBJECTS. 
149 
fired for observation of pressure—ten with 85 lbs. pebble and five with 67 lbs. 
R.L.G. powder. The mean velocities and pressures were as follow, the projectile 
weighing 600 lbs. :— 
No. of 
rounds. 
Muzzle 
velocity. 
Pressure by crusher gauge at 
A. 
JB. 
Base of 
shot. 
f.s. 
tons. 
tons. 
tons. 
R.L.G-., 67 lbs. 
5 
1168 
21*9 
17-8 
19-0 
Pebble, 85 lbs. 
10 
1297 
18-0 
16-8 
15-0 
It will be observed that the pressure indicated by the battering charge of R.L.G. 
in the above gun is considerably lower than that given by the battering charge in 
the other heavy M.L.R. guns; this is probably owing to the relative smallness of 
the charge as compared with the weight of the shot and the calibre of the gun. 
(K) Practice from Service Rifled Guns. 
The following table contains an abstract of the velocities obtained with various 
charges of pebble and R.L.G. powder from service guns at Shoeburyness. The 
muzzle velocity of the 10-inch service gun is only 1364 ft. as compared with 
1383 ft. and 1423 ft. with the two kinds of pebble powder fired from the experi¬ 
mental rifled gun. This difference may be accounted for by the latter having only 
•02 in. windage instead of *08 in., and only two grooves instead of seven, in addition 
to any other variations in the state of the bore. In the practice with the 7-inch gun 
there was found to be a difference of 30 ft. per second between the velocities given 
by an old gun much scored in the bore and a new one, when pebble powder was 
used, and 70 ft. when R.L.G. powder was used:— 
Guns. 
Pebble powder. 
R.L.G. powder. 
Normal 
muzzle 
velocity. 
i 
| Charge. 
1 
Mean 
muzzle 
velocity. 
| Charge. 
1 
Mean 
muzzle 
velocity.. 
lbs. 
f.s. 
lbs. 
f.s. 
f.s. 
85 
1300 
67 
1161 
12-inch M.L.R. of 25 tons; 600lbs. projectile ... < 
80 
1255 
67 
1168 
> 1180 
75 
1235 
-— 
— 
3 
j 10-inch M.L.R. of 18tons; 400lbs. 
„ 
70 
1364 
-60 
1280* 
1298 
. 
( 
50 
1420 
43 
1338 
J 
j 9-inch M.L.R. of 12 tons; 250 lbs. 
/; ...■] 
48 
1386 
43 
1316 
> 1336 
1 
48 
1362 
43 
1381* 
3 
‘ 
f 
35 
1413 
30 
1330* 
8-inch M.L.R. of 9tons; 180lbs. 
35 
1384 
30 
1314 
[ 1363 
30 
1361 
— 
HH&4I 
3 
7-inch (oH tons; length of bore, 
10ft. 6 ins.... 
25 
1465 
— 
— 
c 
28 
1447 
22 
1315 
0 
lisibs. 
9 ft. 3 ms. < 
30 
1493 
22 
1366* 
> 1430 
projectile, V. // u n 
(new) . 
30 
1525 
22 
1435* 
l 
3 
* lte-worked from Pigou and Wilks L.G. 
f Muck scored; previously fired 1729 rounds. 
