54 



DISCUSSION OF THE VERTICAL COMPONENT 



(G). Diurnal Range of the Vertical Force. 

 (In parts of the force.) 















1100 - 







y 



•^\ 







1000 







/ 



\ 







0900 







/ 



i 





0800 





1 









0700 





/ 







•1 



0600 '/ \ 1 / 







\ 





0500 



1 \' 







\ 



,/ 



0400 - 









V II 



0.000300 



























< IB O S Q 



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. 



Table IX. — Principal Epochs of Mean Vertical Force. 



A.M. 



P.M. 



January 

 February 

 March . 

 April 

 May 

 June 

 July . 

 August . 

 September 

 October . 

 November 

 December 



8i>58" 



7 42 



8 27 

 6 15 



5 55 



6 36 



8 11 



8 27 



31,470 



5 16 

 4 53 



6 13 

 6 21 

 6,04 

 6 10 

 6 04 

 6 28 

 4 19 

 4 49 

 3 39 



Summer 

 Winter . 

 Year 



6 43 



7 52 



7 06 



6 13 



4 29 



5 33 



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. 



