126 Mr. H. Jeffreys on Periodic 



Then a typical value of U is given by 



tt ^ f ~" ( v 9~~ 7 2 ) + iy~k{v 2 — \ 2 ) ,. 



+ £ *—J 1 (\r)e % y t (e- Xz —e- m *). . . (8) 



■+■- — JofAr)**^*-**— e" 81 *). . . (9) 

 L must now be found from the condition that 



^ + ^ + ^ =S=MyY (10) 



Now |H + |? = l|. (rD ) (ii) 



das oy r dr K 



We find then the equation 



hg\ 2 (v — m) biy(mv—X 2 ) X 2 gc 



{v 2 -\ 2 ){ty-k{v 2 -X 2 )} v 2 -X 2 2mcy 



-*yc+^(m-\) = 0. . (12) 



i^This is converted into equation (17) o£ the case of infinite 

 parallel strips by simply writing ir(l for \. 



Case 1. Large island or continent. X is small compared 

 with v and m. In the case of a daily period, this splits up 

 at once into two sub-cases, according as the radius is large 

 or small compared with 1000 kilometres. If it be small, as 



