THE ROYAL ARTILLERY INSTITUTION. 
355 
It will be noticed that the error of range is considerably less at every 
distance than it is with the field gun, an effect which is due to the lower 
velocity and higher angles of descent. The error of direction is greater, 
but still very moderate considering the small size of the piece. A similar 
uniformity of practice with small charges and comparatively large angles is 
familiar at Shoeburyness. 
20. One of our own brass mountain 3-prs. of cwt. has been recently 
bored up to the calibre of the Trench mountain gun and similarly rifled, 
except that the number of grooves was reduced from 6 to 3, and the weight 
reduced by the process of boring up from 254 lbs. to 225 lbs. The practice, 
which is contained in the following table, is excellent. The recoil was violent 
but easily controlled by lashing the wheels: the loading very easy. 
Table X. 
21. Practice of an English mountain service S-pr. bored up from 2* // 88 to 
3*"406 and rifled with 3 grooves resembling those of the canon de 4 raye de 
June 1865. 
Iba. oz. 
Weight of piece.225 0 
Charge . 0 10 
Weight of shell empty . 7 14 
Bursting charge . 0 9 
Length of bore. 34 in. 
Charge. 
No. of 
rounds. 
Elevation. 
Ranges observed. 
Mean 
difference 
of range. 
Mean 
reduced 
deflection. 
min. 
max. 
mean. 
o z 
o 
yds. 
yds. 
yds. 
yds. 
yds. 
10 
10 
2 
559 
627 
691 
20-6 
0-47 
a 
10 
6 
933 
1100 
989 
48-2 
1-22 
a 
10 
7 
1131 
1362 
1230 
49-6 
2-18 
n 
10 
10 
1509 
1605 
1552 
21*9 
2-62 
Continuation with reduced charges. 
8 
10 
2 
365 
411 
391 
13*0 
0-52 
n 
10 
6 
651 
748 
699 
25-9 
1-28 
n 
10 
7 
800 
937 
882 
34-9 
1-26 
ri 
10 
10 
1194 
1328 
1264 
28*7 
2-1 
II 
5 
18 
1746 
1981 
1854 
69-4 
3-1 
ll 
5 
30 
2188 
2334 
2234 
52-0 
15*0 
6 
10 
10 
881 
1004 
913 
20-1 
1-00 
4 
5 
18* 
952 
1059 
999 
34*0 
1*30 
a 
5 
30 
1200 
1338 
1255 
43-0 
5*52 
2 
10 
30 
677 
779 
739 
25*5 
2-2 
Trench 25-pr. or canon de 12 raye de Campagne, 
22. In addition to the two light pieces described in the preceding pages, 
the Trench as early as 1859 began to rifle some of the 12-pr. Napoleon shell 
guns, the canons obusier of 12 c which were introduced in 1853, and they 
are now a recognised part of their rifled field artillery. They correspond to 
