178 ON THE LAWS OF 



If now we expand the value of V deduced from this equa- 

 tion, and then compare it with the formulae (25) of the present 

 article, we shall have generally E (i} 0, and 



except when i = 0, in which case we must take only half the 

 quantity furnished by this expression in order to have the cor- 

 rect value of <7 (0) . Hence whatever u may be, 



} and c<? = - 



7T 



the particular value = being excepted, for in this case we 

 have agreeably to the preceding remark 



n-1 



., 



and then the only remaining exception is that due to the con- 

 stant quantity on the left side of the equation (27). But it will 

 be more simple to avoid considering this last exception here, 

 and to afterwards add to the final result the term which arises 

 from the constant quantity thus neglected. 



The equation (26) of the present article gives by substituting 

 for c[? its value just found, 



2 sin 



n-3 .n-1 n-3.n-l.n-l 



2 sin 



8-M 



