70 



DISCUSSION ON THE MAGNETIC VERTICAL FORCE. 



(B.) LUNAR-DIURNAL VARIATION OF THE INCLINATION. 



+ 2". 8 



2.4 



2.0 



1.6 



1 2 



.8 



.4 



.0 



.4 



.8 



1.2 



1.6 



2.0 



2.4 



M 



f 



fc^i. 



I LA 



# I 





v 



a, 

 '3 

 8 



. 

 -3 



U. C. L. C. 



0" 12345 6789 10 11 012345 6 7 89 10 11 12" 



Maxima at 8 h and 20 h (principal), minima at 3 h (principal) and 13| h . 



Total range 3". 6. Probable error of any single hourly representation + 0".7. 



The lunar diurnal variation in the total force is represented by the equation : 



MM M 



$= 1-3 + 8.9 sin (6 + 63) + 6.3 sin (20 + 84) 



an expression not differing much from V& owing to the large dip. The observed 



and computed values of * are shown in the diagram, which nearly resembles that 



<2> 

 of the vertical force. 



(C.) LUNAR-DlURNAL VARIATION OP THE TOTAL FORCE. 



0. C. L. C. 



012345 6 7 89 10 11 01 2345 67 89 10 11 12 



Maxima at | h (principal) and IP; minima at 7| h and 17 h (principal). 

 Total range 0.000026. Probable error of any single hourly representation 

 0.000006. 



