[173
173] on laplace’s method for the attraction of ellipsoids.
65
b 2 + c 2 )
1
FTcO
the third line of which is
d 2
d 2
d 2 \
1 O' + 1) ( a 2 ^ + /3- + 7 2 — 4 ( a- ^ ¿p + 7 2 ^ ¿+i >
dò 2
dc 2 )
d
d
d
da.
d(3 ' dy
by a foregoing equation, and the assumed equation of difference thus leads to
d , _ d d^
[ i—f - bp u +C7 -T-
da db dcj
+ (« + 8)(^ + ^ + yg^
(a 2 + 6 2 + c 2 ) Z i+2 + (4 i +7)(aa‘*-+b(3^ + cy £) K i+l
+ ( 2i+ 3) ( a + /3 +7 ) K{ + 1 — 0,
which is the assumed equation, writing i+ 1 instead of i. The equation, if true for i,
is therefore true for ¿ + 1, and it is easily seen to be true for ¿ = 0; hence it is true
generally, or the value
K; =
da 2
d 2
d 2 \
^ db 2 + ^ deV J{a 2 + b 2 + c 2 )
satisfies the equation obtained by Laplace’s method, and gives, moreover, the proper
value for K 0 . We have thus the value of ; and remembering that
V — \/(a + 6) (/3 + 6) (7 + 6) v,
and observing that the symbol A may be replaced by
A= ^ a+ ^£ + ^ +e) m +(r)+0) 3?’
the value pf V is
7 - T V( “ + 0Hf3 + B) (7 + 6) 8i « (2C.2...J.7...2,- + 3 A ‘VOMTO)) ;
which is in fact the value which I have found by a much more simple method in
the Cambridge Mathematical Journal, t. III. p. 69 [2].
C. III.
9