9 
(1) The gun used was the 11", of 1877 pattern ; here weight 
P = 217*7 kilos (530 Russian pounds), 
P = 0*140 m., 
log h<= 4*9010, 
/*=0-53. 
In direct fire the initial velocity ordinarily exceeds 419 m.s. (1374*7 f.s.) 
hence p = *0394. 
We have no immediate experiments for the determination of h, 
therefore we must have resource to the theoretical formula* deduced 
on the supposition that the air resistance is proportional to square of the 
velocity, and the angle S is so small that it is possible to neglect its 
terms of the second order ; here ^ = 7*74. 
Hence (17) gives us y = 50*4, as the maximum pitch for a projectile 
of 2*8 cals, just sufficient for steady flight. 
In the 11" gun, 1877 pattern, the pitch is 45 cals. 
Experiments showed that with this twist the accuracy is wholly 
satisfactory, whilst, with a pitch of 70 cals, with same projectiles of 
2*8 cals., the shooting was bad. 
Keeping to the same weight, (18) gives the pitches corresponding to 
projectiles of different lengths. 
Assuming 77 = 50 and l = 2*8, we get the following table :— 
1 in cals. 
y] pitch in cals. 
2*0 
83*5 
2*5 
59*8 
3*0 
50*4 
3*25 
40*3 
3*5 
36*1 
40 
29*5 
4*5 
24*7 
5*0 
21*1 
6*0 
16*1 
10*0 
7*5 
(2) For the 8 " fougasse steel shell—4*5 cals. 
P = 88*91 kilos (217 Russian pounds), 
P = 0*1016 m., 
log & = 4*9063, 
^ = 0*613. 
N. Majevski’s “The solution of problems of direct and curved fire,” p.p. (>0-67. 
