iron arising from its rotation,. 
407 
phaenomena somewhat analogous take place, but they appear 
to be dependent on the velocity with which the shell is made 
to revolve. 
F f 
On computing the several values of ^y^'from the equation 
(8), I found that if the term 2 cos. I sin. sin. were neglected ; 
that IS, II -rr- were equal to^ — ^ — ■ //; ■ ■ : , its numeri- 
^ 2 j f ^ 3 sin. 2 X sm. (0 — 
cal values, so determined, would agree very nearly with 
each other. I was in consequence led to expect that equa- 
tions from which this value of might arise, would give 
values of 6' — agreeing more nearly with the observations ; 
and the result fully answered my expections. 
2//> 
If 
and 
Tan. 6' = 
Tan. 6^ = 
3 sin. 2 X H . (3 cos. 2 X + I) 
r V 
2 m 
F r 
2/p 
(9). 
. cos. ^ 
3 sin. 2 X ^ . (3 cos. 2 X + 1) 
Fr 
2 ffi 
“f7“ 
cos. S 
then we shall have 
F r 3 cos. 2x4-1 
2 ./> ~ 
sin. (0' 4. 0 ) 
sin. (0' — 0^) 
(10). 
(11). 
3 sin. 2 X 
When the deviation due to rotation vanishes or the 
equations (9) and (10) give 3 cos. 2 x + 1 = o and x = 54° 44 ', 
which agrees perfectly with the observations. 
From the observations in Table A, we have in this case, 
Tan. 90 09' = ^ 
-pT' • ‘^os.70'' 15 
^ 52 very nearly. 
Mri . 2 f p I 2 R^ 
When X = o, . 
whence = 51.9504 
\ 
^ . cos. ^tan. = . 061234; 
and when x = 90, ^ ^ ^'=-057291 : 
so that the mean value of ^ is .059262, or nearly .059. 
