VELOCITY AND PEESSUBE iNSTBUMENTS. 
o(37 
Number of 
round 
from gun. 
Charge. 
Vent. 
Observed velocity. 
oS 
O 
g 
Instrument 
No. 78. 
Instrument 
No. 79. 
P 
40 . 
lbs. 
4 
Hear 
ft. 
1278 
ft. 
1280 
2 
41 . 
n 
n 
1280 
1282 
2 
42 . 
n 
/; 
1280 
1278 
2 
43 .. 
3 
/; 
1160 
1159 
1 
44 . 
n 
H 
1170 
1169 
1 
45 . 
n 
n 
1163 
1161 
2 
46 ... 
5 
// 
1314 
1310 
4 
47 . 
ii 
n 
1309 
1308 
1 
48 . 
n 
„ 
1330 
1330 
0 
49 .. 
3 
Forward 
1156 
1157 
1 
50 . 
„ 
1160 
1162 
2 
51 . 
„ 
;/ 
1146 
1148 
2 
52 . 
4 
/; 
1297 
1297 
0 
53 . 
a 
n 
1301 
1303 
2 
54 . 
a 
n 
1310 
1309 
1 
55 . 
5 
a 
1400 
1401 
1 
56 . 
„ 
n 
1410 
1409 
1 
57 .. 
n 
a 
1413 
1412 
1 
The mean difference between these two instruments for the above eighteen 
rounds is only 1*4 ft., representing a maximum error of about toV^ 11 part 
of the recorded velocity. 
As a further evidence of the absolute accuracy of the different instruments 
employed for measuring velocities, I append a trial of these two Le Boulenge 
instruments in comparison with the small Bashforth gravity chronograph, in 
use at the Royal Laboratory Small-Arm Range, and an electric chronograph 
invented by Lieut. H. Watkin, R.A. The Bashforth instrument is described 
at p. 161, Yol. Y., of these “ Proceedings,” and Watkin's invention at 
p. 14, Yol. IX. 
Velocities of Martini-Henry Ballets fired with Various Charges , observed with 
several Instruments . 
Le Boulenge; 
-m 
cj 
Watkin. 
Instrument 
Instrument 
cm 
m 
Eight 
Left 
No. 78. 
No. 79. 
pq 
cylinder. 
cylinder. 
1167 
1163 
1163 
1155 
1157 
1141 
1140 
1143 
1137 
1136 
1140 
1138 
1138 
1129 
1132 
1136 
1133 
1141 
1138 
1139 
1147 
1145 
1142 
1140 
1140 
Means of 7 ,,. Q 
5 rounds j 1146 
1144 
1146 
1140 
1141 
1272 
1275 
1269 
1259 
1259 
1268 
1264 
1269 
1267 
1267 
1270 
1271 
1277 
1270 
1268 
1277 
1279 
1287 
1272 
1272 
1285 
1287 
1290 
1287 
1285 
1290 
1294 
1280 
1284 
1284 
1264 
1267 
1263 
1264 
1264 
1287 
1289 
1291 
1285 
1284 
Means of) 19 *w 
8 rounds J 1277 
1278 
1276 
1274 
1273 
48 
