110 
ROTATION OF PROJECTILES. 
and see how much it differs from the value obtained by the approximate 
formula given above. 
c 3 — a 2 
In this case. c = 3 a, 0 , . 0 = *8, 
■ c 3 + a z 
aK'=- 0725, a s (C - J) = - -2246, 
« 3 ^=-2971, a s (C+2J)= *6667, 
a = -80385, 
y = -12201, 
aTU ] P __1_ 
o- 10-4 X 816 
NOW, 
fl + P . _ 
= » 1 2 j ^er 
c 3 + or 
1 
= iff, 3 0 — _ 1 _X __\ 
1 \ 10-9 X 816 -8 X -6667 - '2246/ 
= m 2 X -99991823. 
Hence 
Tt^kJ ^ 
4a 3 ^1 + 5 7 j k{~ X -99991823 X £ (a — y) 
2L _ 
?z 3 
1 + P a 
1 + r 7 
(T 
X 
•99991823 
•80385 
= + 10*9 x 81 6 1 
-1220" -99991823 
+ 10*9 x 816 
1-00009038 w 1 
~ 1-00001372 X "99991823 
== 1 very nearly. 
Thus we see that the approximate formula given for the value of n is, 
for all practical purposes, the same as the exact formula, when dealing 
with projectiles made of material possessing considerable density. 
