J 4 ■'^î't' 3.— K. Hirayama : 



m' ""^ da^ 2 V da.^ 2 da^^ I 



= (4-3.)(i)V + 2(4-5v)(^)V+3(4-7v)(^)V + 



where '^o=-% and ^=-77- 



which are too small to be considered in our problem. 



The equations (14) represent the motion in the librating 

 region with remarkable simpUcity. This will be shown geometric- 

 ally. 



19. General Case of the First Order, s—s'=l. The principal 

 term of Ec, becomes in this case 



aoEc=—pi''''* e cos d 

 in which ^'" = ^(2^'"'+^o^) 



The three equations of (14) become 



(15) x'=G + 6p,^'^ecosd 



(16) e'=E + -^x 



(17) l_^^^,^_pl^çosd_ 

 no at e 



Suppose the quantities x and e are two rectangular coordinates. 

 The equation (16), then, represents a paraôo/a whose axis is the 



