164 



MR. S. S. HOUGH ON THE APPLICATION OF HARMONIC 

 III. DEPTH 29,040 feet (%/4a> 2 a 2 = -^, p /a- = 0-18093). 



IV. DEPTH 58,080 feet (Jig/tora* = |, p/<r = Q'18093). 



The approximate roots here given have been evaluated by the method of 7, 

 except in the case of the roots of the second class for n = I, s = 1, where, instead 

 of replacing the continued fraction involved in the period-equation by its first con- 

 vergent, I have made use of the second convergent, so that the approximate form of 

 the period-equation from which this root is determined is 



or 



Mi 



or, what is equivalent, Li 0. 



Ni =0 ' 



fr = . 



