166 
MINUTES OE PROCEEDINGS OE 
II. 
Table giving the value of the Ballistic coefficient C for rifled Projectiles. 
Nature 
of 
Ordnance. 
Projectile. 
Value 
of G 
in feet. 
Nature. 
Mean 
weight. 
Mean 
dia¬ 
meter. 
Remarks. 
Armstrong 110-pr. 
Shot 
Ibs. 
111-60 
ins. 
7-00 
18938-4 
The values of C have been calculated 
Shell 
103-80 
» 
17614-8 
from the formula 
c=L_P- 
2 g AnlP’ 
„ 40-pr. 
Shot 
41-50 
4-75 
15293-9 
g= 32-1908, 
A=0-0003425, 
tt=3-1415926, 
„ 20 „ 
55 
21-20 
3-75 
12535-7 
2R=diameter of shot, 
P=weight of shot. 
If projectiles differ much in weight 
„ 12 „ 
S. Shell 
11-75 
3-00 
10856-0 
from the weights given in the Table, it 
will be sufficient to multiply C by the 
ratio of the weights. 
„ 9 „ 
9-25 
3-00 
8546-2 
p/ 
c'=c£. 
If the diameters differ in the inverse 
» e„ 
Shot 
6-25 
2-50 
8315-3 
ratio of the squares, 
C'=C — • 
B' 2 
31. Supposing the targets to have been 120 ft. apart, and the distance 
from the muzzle to the first target 30 ft., the point x will be situated at 
90 feet from the muzzle. 
In the example chosen, the velocity at this point will be 1120*4 ft., the 
gun being the 110-pr. Armstrong. 
Looking in the Table for the value of C } it is found, viz. 18938*4, which 
multiplied by 2, equals 37876*8. 
The equation then becomes 
1 + 
1 + 
1427 
1120-4 
90 
37876-8 : 
1427 
1120-4 
2-27365 = 
(•♦T) 
0-002376, 
(>+¥) 
90 
e 37876-8 
g0-002376. 
e 0-002376. 
The value of e 0 * 002376 is obtained by developing the series, 
rvJ nJ 3 
^= 1 + I + T¥ + T72T3 + &c - 
<,0.002376 = 1 + ™02376 + 0-0023768 + Q-Q023763 + &<j> 
1 1.2 1.2.3 
= 1 + 0-002376 + 0-000002823 + 0-000000002 + &c. 
The fourth term of the series may be safely neglected, and we find 
e o.oo2376 = 1 .0023788, 
2-27365 = 1-0023788, 
