Tension and Complex Molecules. 

 the i mutual potential energy of the two is, 



379 





«y) 



But 8x = l cos 6, $y = l sin 6, if (9 is the angle between the 

 axes of the doublets, and accordingly 



W = ^(cos6>~ +sm6^Y 



For our purposes in the present theory, it is only necessary 

 to consider parallel doublets, for which = 0, so that we may 

 write 



The force acting on the second doublet, parallel to the axis 

 of a, is X where 



and that on the doublet at the origin is equal and opposite 

 to this, or 



*& - 5) = v- 2 (5^-3^)= ^(2^-3f, 



The extremities of opposite sign being adjacent, the force is 

 au attraction. 



Fig. 1 shows two doublets whose distance apart has two 



Fig.l. 



-e e mc [ 



components md, nd, where m and n are integers. We can 

 regard d as the average distance apart, in an assemblage 

 arranged in regular order, of two adjacent doublets. 



