240 Mr Greenhill, On the rotation of a [Mar. 24, 



b +c ^ ^^ ^ c +a^ ^^ a -\-b ^ ^ ' 



- JT^^ ^F+¥ ^^"32/^ - ^.^^ FT? «3«x^^ 



6' + c^ c' + a' ' ' -^ 

 (We have x — yo}^ + zm^ = 0, 



y — zcOj^ + X(o^ = 0, 

 z -xco^ + yco^ = 0, 

 because ccyz is here taken to denote a point fixed in space.) 

 Therefore 



=* Ic-^T^^"^ -c^TP'^^ +HcM:^i "^ ^K^FTb^J "4 

 + 3/M } + ^M "■. }; 



the terms involving co^w^yz^, (o^co^zoc^, co^co^osy disappearing; and 

 therefore 



+ W{ 1+i^M 1. 



and 



v=m 



= constant — ^^a;^ — ^By^ — ^ Cz^ suppose. 



The surfaces of equal pressure at any instant are therefore the 

 similar ellipsoids 



t"^"^ {c' + aj "^^ W+Wf "^M 



■^r"^ — (^?T6T "'^ (FT?f — ""M^ 



f^, (6^-c^)(36^ + c0 (c^-a^)(o^ + 3gO 1„, 

 r+ (FT?r ' ¥+^' '} 



+ 



= constant. 



