THE ROYAL ARTILLERY INSTITUTION. 
117 
The velocities (in feet per second) are also given, as they were necessary 
to the calculations, and it is as well to record them. 
Gun. 
Weight 
of 
gun. 
Weight 
shot. 
Charge. 
| Initial 
j velocity. 
At 200 yds. 
At 1000 yds. 
At 2000 yds. 
Velocity. 
j Vis 
1 viva. 
Velocity. 
Vis 
viva. 
Velocity 
Vis 
viva. 
lbs. 
lbs. 
ft. 
ft. 
ft. 
68*pr. S.B. gun ... 
95 cwt. 
66 
16 
1580 
1380 
878 
986 
445 
717 
235 
7" B.L., B.S. 
82 » 
90 
11 
1165 
1118 
771 
962 
577 
820 
412! 
7" M.L. R, gun... 
6 \ tons 
115 
22 
1430 
1360 
1505 
1199 
1146 
1034 
862; 
9" „ 
12 „ 
250 
43 
1340 
1330 
3069 
1175 
2394 
1046 
1896' 
10" 
18 ,/ 
400 
60 
1290 
1265 
4438 
1168 
3784 
1068 
3163 
12" 
23 „ 
600 
70 
1240; 
1217 
6161 
1133 
5336 
1042 
4520 
American 15" S.B. 
20 „ 
450 
100*1543: 
1454 
6597 
1182 
4359 
958 
2863 
// 20" „ 
50 » 
1100 
200*1370 
1316 
13210 
1136 
9843 
971 
7191 
The initial velocity is taken principally from Captain Noble’s abstract, O.S. Committee Extracts, 
Vol. V. pp. 168-71. 
The calculations for the 12" M.L. rifled gun and for the 20" American are taken from the 
“Army and Navy Gazette,” 11/4/68. A few of the numbers having been verified. 
However the next table which is immediately deduced from the foregoing 
will perhaps be more popular, as it shows at a glance the relative powers of 
the guns, by giving their specific vis vivd 3 taking that of the familiar 68-pr, 
as unity. 
Nature. 
Weight 
Weight 
Charge. 
Specific vis viva, of each gun. 
of 
gun. 
of 
shot. 
At 200 yds. 
At 1000 yds. 
At 2000 yds. 
68-pr. S.B. gun ... 
7" B.L., B.S.R.... 
95 cwt. 
lbs. 
66 
lbs. 
16 
1 
1 
1 
82 „ 
90 
11 
•86 
1*3 
1*7 
7" M.L. R. gun... 
6| tons. 
115 
22 
1-7 
2-6 
3-6 
9" 
12 n 
250 
43 
3-5 
5-4 
8-0 
10" 
18 » 
400 
60 
5-0 
8*5 
13-5 
12" 
23 « 
600 
70 
7-0 
12-0 
19-2 
American 15" S.B. 
20 „ 
450 
100 
7-5 
9-8 
12-2 
if 20" „ 
50 „ 
1100 
200 
15-0 
22-1 
30-6 
Thus we see, for example, that the 12" gun can deliver a blow, on 
masonry say, at 1000 yards, twelve times as severe as the 68-pr, can. For 
the relative power of perforating armour plates we must divide by the 
respective diameters of their projectiles, or for simplicity by the calibres of 
the guns (which practically amounts to the same thing), and in this case we 
find that the 12" gun is eight times as powerful as the 68-pr, 
* American powder and alleged charges. The Americans have as yet (June ’68) only four 20" 
guns, two of which (“ Beelzebub ” and “ Puritan ”) were cast in May ’66, and their 15" guns are 
not very numerous. 
[vol. VI.] 
16 
