Manchester Memoirs, Vol. I. (1906), No. 1. 29 



Hence we should get a table as follows, knowing that the 

 first column of Table I. is 1 +cosa. 



The ratio in the last column, increased by unity, indicates 

 the inverse power of the distance at which tiie density falls otf, 

 and we see that the power is much higher than before. 



Table II. 



We now come to consider 



Case II. When 2a - R^r'^R the integral becomes 



where 



jY^^ f sin Md 



s'^^{a-Rf-{r-a)'^. 



