146 
SHORT NOTES ON PROFESSIONAL SUBJECTS. 
A comparison of the velocities and pressures before and after rifling is contained 
in the following table, and shows no difference greater than what is liable to exist 
between different series of trials when the conditions are intended to be similar in 
all respects:— 
nj .15 
fcq O 
Pressure by 
crusher gauge at 
d j2 
^ £ 
A. 
B. 
C. 
f.s. 
tons. 
tons. 
tons. 
R.L.G., J 
^ Curtis & Harvey, density 1-675 j 
' Gun, 
smooth... 
rifled 
1322 
1325 
53 
53£ 
27i 
32 
26 
25 
charge 60 lbs. 1 
[.Waltham Abbey, „ 1-724 j 
' ", 
smooth... 
rifled ... 
1330 
1313 
48^ 
37£ 
31 
30^ 
25 
26£ 
| 
r 16. 5.70 'J / 
smooth... 
1443 
21 
21 
20 
Pebble... Date 
29 7. 70 f Waltham Abbey... - 
\ >> 
rifled ... 
1423 
214 
20^ 
20-g- 
Charge 701bs. ' 
smooth... 
1435 
22 
22 
23 
Ll5.*l6. 70 3 1 
s. II 
rifled ... 
1383 
20 
20 
20 
The general results exhibit a slight diminution of velocity, and likewise a slight 
diminution of pressure consequent on the rifling. These results are insufficient to 
form a basis for any general conclusion; they however appear to indicate that 
there is no important difference in either velocity or pressure between the gun in 
its rifled and in its smooth-bore state. 
( C .) 8-inch Experimental Gun 3 No . 288 , Smooth-bore . 
59 rounds have been fired from the 8-inch experimental gun since the Pre¬ 
liminary Eeport of 5 th February 1870 was drawn up; 22 of these were battering 
charges for proof of various kinds of pebble powder; 20 rounds formed a portion 
of the experiments with projectiles of increasing weights, noticed in the Memo¬ 
randum of 7th July, 1870, and 15 were fired with a 69 lb. round shot and various 
kinds of powder, principally to ascertain the pressure exerted in 68-pr. smooth-bored 
guns with service charges of L.G. and E.L.G. powders. Two rounds consisted of 
blank charges of 30 lbs. E.L.G.; with these the pressures indicated at A , B, and 
C were 154, 9f, and 9 tons per square inch respectively. The pressure at A was 
about the same as had been given at the same point in firing a cylinder of 170 lbs. 
weight with 85 lbs. of pebble powder. 
The series of experiments with projectiles of increasing weights is not yet com¬ 
pleted; the trials with a 69 lb. round shot gave the following average results 
t> T r' ion, f Curtis & Harvey.density, 1-675 
R.L.G. ...16lbs. £ Waltham Abbe /. „ 1-732 
r r~\ , oV , ( Curtis & Harvev. // 1-648 
. 16 lbs - l Pigou & Wilks *. „ 1-637 
C 16 lbs. Waltham Abbey, 23. 5. 70. n 1-78 
Pebble ■< 18 lbs. „ « . 
(, 20lbs. n n .. 
Number of 
j rounds. 
ESI .15 
N O 
Pressure by 
crusher gauge at 
d o 
s £ 
A. 
B. 
C. 
f.s. 
tons. 
tons. 
tons. 
3 
1705 
19 
12 
24 
3 
1658 
16| 
11 
16 
3 
1686 
15 
»* 
17f 
3 
1679 
12 
11 
17f 
1 
1410 
4* 
84 
2 
1 
1478 
2* 
3 
1 
1547 
3 
6 
2* 
