THE ROYAL ARTILLERY INSTITUTION. 
379 
Table 
SHOWING THE PROBABILITY OF A HIT WITH 3-pi% COMMON SHELLS, LOW-ANGLE FIRE. 
Elevation.- 
Mean range. 
Horizontal target, 1st graze. 
Dispersion. 
Vertical target, hits 
per cent, in a target 
35 yds. x 4 yds. 
Length of ground ef¬ 
fectively commanded 
for a 6-2 ft. object. 
Remarks. 
Length. 
Width. 
Max1 ' Mean, 
mum. 
Maxi¬ 
mum. 
Mean. 
O / 
yds. 
yds. yds. 
yds. 
yds. 
No. 
yds. 
1 24 
415 
60-6 11-6 
1-66 
0-91 
91 
62 
Charge 7-4 oz. 
3 47 
830 
54*0 14*1 
4*56 
1-58 
67 
26 
6 21 
1244 
62*2 17-4 
7*47 
2-24 
43 
12 
9 26 
1659 
73-8 21*6 
10-79 
2-90 
20 
8 
13 36 
2074 
90-4 ; 29-9 
. 
14-10 
3-73 
10 
8 
19 1 
2489 
110-3 | 61-4 
17-84 
4-65 
— 
5 
The mean range is the arithmetic mean of a number of ranges obtained under like circum¬ 
stances. 
The maximum dispersion in length is the difference between the greatest and least range of a 
series of rounds fired under like circumstances. 
The mean dispersion in length is the arithmetic mean of the differences between the mean 
range and the actual range. 
The maximum dispersion in width is the difference between the greatest and the least deflection, 
when the deflections in a series of rounds are all to the same side ; or the sum of the greatest 
deflections right and left. 
The mean or parallel deflection is the arithmetic mean of the whole of the deflections in one 
series of rounds, when the deflections are all on the same side. When the deflections are on both 
sides, the mean deflection is obtained by adding the deflections to the right and those to the left 
into two separate sums, subtracting one from the other and dividing the difference by the number 
of rounds. In the first case when the deflections are all to one side, the parallel deflection is 
termed right or left deflection according to the side to which the deflections have occurred. In the 
second case the parallel deflection bears the name of the side to which the greater of the two sums 
appertains. 
The mean dispersion in width is the arithmetic mean of the differences of the mean deflections 
and all the observed deflections of the series of rounds. 
Table 
SHOWING THE PROBABILITY OF A HIT WITH 3-pi\ COMMON SHELLS, HIGH-ANGLE FIRE. 
Elevation. 
© 
§ 
Ph 
1st graze. 
Dispersion. 
, O 
dimen- 
le. 
© 
o 
1 
Length. 
Width. 
II 
© o 
r-rt 
© a 
o o 
.1 
O 
Remarks. 
Maxi¬ 
mum. 
Mean. 
Maxi¬ 
mum. 
Mean. 
PH 
c$ 
:£ 2 
H £ 
1 8 
'§■! 
U) 
4 
O ✓ 
i yds. 
yds. 
yds. 
yds. 
yds. 
66 yds. 
33 yds. 
O 
Charge 3-7 oz. 
3 10 
415 
54-8 
23-2 
2-49 
1-43 
75 
50 
8 20 
830 
63-1 
24-1 
4-98 
0-37 
64 
36 
12 
14 5 
! 1244 
78-0 
25-7 
8-30 
4-18 
44 
30 
20 
18 8 
j 1493 
90-4 
26-5 
11-50 
5-97 
45 
25 
28 
