Vol. IV, No, 4.]  Reczprocal Relations of Qurves and Surfaces, 245 
[N.S.] 

In other words, OP?.0Q? = R* 
Ie. OP.0Q = R*. 
The equations (A) and (B) of Art. 6 reduce in this case to 
,_ We _ Fr 
ne a+ yf ve git y’? 
and 
»_ Wy . 
Y= B+yi I pty 
Analogous results, of a hold for the sphere and can be 
deduced from those of Art 
NN emer tt eet 
