24 



DISCrSSION OF THE VERTICAL FORCE 



Table XII. — Contains the ni mbeh of Disturbances distributed over the 

 Hours of the Day, separated into those which Increase ( + ) and those 

 WHICH Decrease ( — ) the Vertical Force. 





K umber of disturbances. 



Ratios. 



+ 



- 



+ ' - 



0" 



2 



4 



6 



8 

 10 

 Noon 

 14 

 Itj 

 18 

 20 

 22 



93 

 73 



69 

 62 

 59 

 53 

 61 

 96 

 69 

 72 

 67 

 76 



75 

 86 

 87 

 71 

 58 

 62 

 70 

 67 

 58 

 44 

 43 

 47 



1.3 

 1.0 

 1.0 

 0.9 

 0.8 

 0.8 

 0.9 

 1.3 

 1.0 

 1.0 

 0.9 

 1.1 



1.2 

 1.3 

 1.4 

 1.1 

 0.9 

 1.0 

 1.1 

 1.0 

 0.9 

 0.7 

 0.7 

 0.7 



Mean 



71 



64 





The laws which regulate the diurnal occurrence of the number of disturbances, 

 increasing and decreasing the vertical force, are evidently not the same, yet they 

 are by no means the converse of one another as has been found to be the case in 

 the disturbances of the declination and the horizontal force. At Toronto also, 

 where the horizontal force and declination curves were exactly opposed, that of the 

 vertical force is not so, and at Philadelphia rather favors an agreement between the 

 increasing and decreasing disturbances than an opposition. 



Principal maximum of increasing disturbances 2 P.M., principal minimum 9 A.]\I. 

 (at Toronto 5 P. M. and 5 A. M. respectively). Secondary maximum at midnight ; 

 this may possibly be the principal maximum ; secondary minimum at 8 P. M. 



Principal maximum of decreasing disturbances 4 A. M., principal minimum 8 

 P. M. (at Toronto 3 A. M. and 6 P. M. respectively). The secondary maximum at 

 noon is less distinctly marked ; secondary minimum at 8 A. M. 



Thus the epochs of the curves for increasing and decreasing force seem to be 12 

 hours apart. 



Diurnal Inequality in the Magnitude of the Dinturhances. 



Table XIII.— C 



ontains the aggregate amount of Disturbances and 



their average Magnitude, the latter found by means op Table 



XI. All expressed in Scale Divisions. 





AgRvegale amount. 



n 



Mean amount. 



0" 



7049 



1C.8 



42 



2 



6876 



159 



43 



4 



6480 



156 



42 



6 



5418 



133 



41 



8 



5022 



117 



43 



10 



5096 



115 



44 



Noon 



5526 



131 



42 



14 



7101 



163 



44 



16 



5591 



127 



44 



18 



5571 



116 



48 



20 



4773 



110 



43 



21. 



5246 



123 



43 



