54 



DISCUSSION OF THE VERTICAL COMPONENT 



(Q). DIURNAL RANGE OF THE VERTICAL FOKCK 

 (In parts of the force.) 



Table IX contains the times when the mean value of the vertical force is reached 

 each day arranged for monthly averages. In some months the average daily value 

 is attained four times, but generally only twice. The table contains the two prin- 

 cipal epochs (one A. M. the other P. M.) ; those produced by the secondary wave 

 can easily be made out by means of the preceding diagrams. 



The next table contains the computed diurnal variation of the vertical force, 

 expressed in absolute measure ; compared with Table IV, it shows the differences 

 between the observed and computed values. 



