COEFFICIENTS OF SOLENOIDS. 9 



§ 5. The followiDg two examples will serve to illustrate the 

 present method of calculation. 



(1) For ^■' = 0.3420201=.§m 70°, we find by (5) 



^=0.1310618 



Table I gives %o +£)- 0.0003758 

 Direct calculation gives loffio 4 ;r ç-t =1.7754242 



By addition log.o — ^^^^=^ =î.7758000. 

 47T-y/Aa 



which coincides with the value found by Maxwell, who calculated 



it by using Legendre's tables. 



(2) For ^-=0.9975641=8^ 86°, we find by (5) 



^1 = 0.0003048651. 



Or from (5') 



. = 0.000 3041228 



16 



= 0.000 0007399 



4^ =0.000 0000024 

 1024 



</i =0.000 3048051 



which is the same as found by (5) 

 By direct calculation 



Ingn (-^^ = 8.115378 



Table II gives -e'i =0.0000007 



Consequently l-\-Srj^ + z\=l .0024382 



and 1-2^/^ = 0.9993903 



By (4") log ^4^ =0.3139097 



as given by Maxwell. 



It may be remarked that a slight disadvantage of the pre- 

 sent method lies in the fact that Çi must always be calculated 

 with great accuracy, however small it may be. 



