AN ELONGATED PROJECTILE. 
591 
therefore log n 2 = 3*1841581, 
log n = 1*5920790, 
n = 39*09. 
Similarly with filled double shell we shall find n— 28, about. 
If the Martini-Henry bullet be considered a solid prolate spheroid 
of lead, of which the length is three diameters, then 
a — y — *68184, 
p __ density of air 
cr density of lead 
Jl 
816 _ 1 
~ 10-9 “ 10*9 x 816 
fc* = i («2 + c *) = 
0 
and therefore 
m2 _ 7T 2 x 10*9 x 816 
U ~ 50 x *68184 ’ 
log 7T 2 = 0*9943018, 
log 10*9 = 1 0374265, 
log 816 = 2-9116902 
= 4*9434185, 
log 50 = 1*6989700, 
log *68184 = 1*8336825, 
= 1*5326525, 
log ^ 2 = 3*4107660, 
log u = 1*7053830, 
n = 50*744. 
In the Martini-Henry rifle the rifling makes one turn in 22 ins.; 
and the calibre being *45 of an inch, the rifling therefore makes one 
turn in ^ = 49 calibres. 
c 
Generally, for a projectile x calibres long, - = x, and therefore 
a 
a%0 = _ 1)1 l0 S‘ (• + ^ - x ) - 
1 
{x 2 — l)f 
loge (x + \/ x 2 — 1) ; 
