THE ROYAL ARTILLERY INSTITUTION, 
345 
by a shot of the given proportions in the direction of the axis of the 
gun, starting with a velocity equal to V~W cos D cos B during a 
time t. 
But since the tables are calculated for horizontal ranges, we must 
multiply our result by the cosine of the angle of elevation, which 
gives us 
tv n w 
Sc° S V ¥ ; 
and this is the true horizontal range through the air . 
But the air is in motion, and therefore to find the true horizontal 
range over the earth's surface we must add the distance travelled by 
the air during the flight of the shot. This will give 
8 cos B 4- Wt cos D ; 
a* 
which is the required range under the given conditions. 
If the wind be acting against the projectile, we must start with 
V + W cos D cos E, 
w 
and must subtract Wt cos D from 8 cos B . 
cl 2 
For the sake of example, I give a table constructed from some practice 
with the 40-pr. B.M.L. gun. The estimate of the wind's force is made 
by the officer conducting the practice, and is therefore liable to error. 
To register the force and direction of the wind with accuracy, it would 
be necessary to place an anemometer near the range, and to observe it 
during the actual flight of the shot. 
Table taken from Practice with 40 -pr. R.M.L. Gun at Shoeburyness. Sights, ver- 
tical; rifling, 1 turn in 35 cals.; diameter of 'projectile, 4’67"; length, 13'52"; 
capacity, 3‘IS 7 lbs.; weight empty, 35'312 lbs.; brand of powder, R.L.G. 1629. 
Date. 
Nature 
and weight 
of projectile. 
No. of rounds. 
Charge. 
Elevation, 
(corrected) . 
j Observed 
j range. 
Tirneof flight. 
Calculated 
muzzle veloc. j 
Wind. 
Observed de¬ 
flection right. 
Remarks. 
lbs. 
O / 
yds. 
secs. 
f.s. 
yds. 
( 
H3 
Wind light, and 
22. 3. 72 
CD 
10 
7 
5 3 
2317 
6-8 
1274 
See remark. 
4*5 ■< 
all round compass; 
|o 
l 
average about nil. 
h3 
rj 
a 
ci . 
Ti .a 
4 
n 
10 2 
3890 
12-6 
n 
i 
15*0 
5. 4. 72 
CD —< 
rS CO 
r O) 
rZ 
6 
JJ 
n 
3769 
12-4 
n 
A 
1 
6 0° 
\ 
34*8 | 
Wind probably a 
little more than 3. 
a 
o 
32° 
8. 4. 72 
o 
Q 
10 
II 
2 6 
1200 
3*2 
n 
4 
16 { 
Wind probably a 
little less than 4. 
