512 



PROFESSOR W. E. AYRTON, Mil. T. MATHER AND MR. F. E. SMITH: 



The mean (arithmetical) dimensions chosen for calculating the values of M e , M Si , 

 and M e> respectively, were those of the left suspended coil and the lower helices on 

 the left fixed coils, and are given in Tahle VIII. 



TABLE VIII. 



2A = 33'0016 9 centims., 2a = 20'3583 3 centims. 

 From these we get 



A + a = 26-68001, log (A + a) = 1-4261860, 



A-a = 6-32167 4 , log (A-a) = 0'8008325, 



c 2 = 0-9438574, log c 2 = 1-9749064, 



c = 0-9715233, log c = T'9874532, 



c' a = 0-0561426, log c' 2 = 27492925, 



c' = 0-2369443, log c' = I '3746462. 



These quantities are required for the three values of M to be calculated. The 

 remaining quantities differ according to the axial length of the helix taken, and are 



tabulated below. 



TABLK IX. Calculation of Mutual Induction. 



