248 
PRINCIPLES OF GUNNERY. 
Examples 
in the solu¬ 
tion of 
problems in 
practical 
gunnery by 
means of 
Tables I. 
and II. 
Example (1).—In what range would the velocity of a projectile fired 
from the 9-in. M.L. gun be reduced from 1420 f.s. to 1240 f.s. ? 
For the 9-in. shell, c/=8‘92 ins., w=250 lbs.; also F=1420, ^ = 1240. 
Substituting in equation (I.), 
rJ2 
10 a _ a cf 
— /j — /jy — oy ; 
W 
°r ^i 240 — ^1420 == 3308-6 - 1251-1, by Table I.; 
or -3183#= 957-5 ft.; 
so that S = 3000 ft. nearly. 
i.e., the velocity would be reduced from 1420 f.s. to 1240 f.s. in about 
3000 ft. 
Example (2).—In what time would the velocity of the same projectile 
be reduced from 1420f.s. to 1240f.s.? 
Substituting in equation (II.), 
J2 
-T=T V -Tv, 
w 
o 1 '^- 5 T=T im -T^ o=l-5285 --8057; 
or *3l83T= *7228 sec.; 
so that T = 2-27 secs. 
i.e., the velocity would be reduced from 1420 f.s. to 1240 f.s. in about 
2*27 secs. 
Example (3).—Find the remaining velocity of the 12‘5-in. M.L. gun 
at 3000 ft. 
In this case, w = 800 lbs., <7=12-42 ins., muzzle velocity (F) = 1420 f.s., 
/S =3000 ft. _ 
Substituting in equation (I.), 
r/2 
w Of _ ry ry 
- O /J y — /J V \ 
w 
0r X 3000 =Sv ~ 'W 
Transposing, 
;I 'T ,: X 30 + ^1420 
= 578-4 + 1251-1 (since ^ 1430 = 1251-1 by Table I.); 
or 8 V = 1829-5 ft.; 
then from Table I. v = 1306-6 f.s. 
i.e., the remaining velocity at the distance of 3000 ft. from the muzzle 
is 1306-6 f.s. 
