268 A. D. Bache on the Horizontal Component of Magnetic Force 



numbers exceed those of the vernal equinox. The same law 

 was found at Toronto. Also, the numbers are smaller at the 

 Bummer solstice than at the winter solstice, in perfecfaccordance 

 with the result found at Toronto. These results are shown 

 graphically on the accompanying diagram (fig. B), which con- 

 tains also the ratio of the disturbances for the declinatioD, in 

 which the same law is apparent. 



Table No. X shows that, in reference to the average magni- 

 tude of the disturbances, the same law holds good, viz: the 

 greatest relative magnitude occurring about the time of the 

 equinoxes, the greater amount corresponding to the autumnal 

 equinox, and the least to about the time of the solstices, the 

 smaller amount occurring near the summer solstice. The £ 

 age magnitude of the disturbances of the declii 

 subject to the same law. 



If we separate the disturbances which increase the force from 

 those which decrease it, we may foi-m the two following tables 

 of the distribution of the disturbances in number and average 

 amount over the several months of the years. 



Table No. XI— Annual inequality ir 













de 



^east 



igth 



ehor 



zont 



^lf,yr 



ce. 















■ lS41-4-<> 



ySA2.AS , 1^3-44 



1844..40 









uT-^v^ 



J^ 





1^,-Di^ 



l^li^. 



J^^-UTc 



T^^c. 



1^. 





"S- 



("38)! (.5) 



~T 



~lo 





~T^ 



-T 



^ 





— - 



50 



18' 



TT 



'0 







55 











2 



9 













1-0 



Sep^t. 







5 





38 







5 





4 





80 







Oct. 



,8 









3? 









I 



8 









h* 



N,.v. 

 Dec. 



.3 



(38) 

 35 



6 



1 





'5 







i5 





I 



i 



H 



^9 



Mar.' 













17 









? 











£ 



\\ 



S 



1 



]i 



'\ 



i3 







I 



16 



56 



43 



u* 



:i 



S^" 



"4 



3^73 



-wrr^ 



73^ 



~n 



-5T|-48-|7^l5-^ 



J± 





In each year the number of disturbances increasing the for^ 

 is less than the number which decrease it; the numbers of '"*^J*^f> 

 are to the numbers of decrease as 1 : 1-8. The numbers ot tnc 

 monthly ratio for the increasing disturbances exhibit the sam 

 law as found in table No. IX. With respect to the numbers 10^ 

 the decreasing force, the law is apparently less distinctly ^f 7 ' 

 The maximum seems to occur about two months later (betore 

 the winter solstice) at a time when the number for increasing W'^ 

 ■ .um. This indistinctness in the law m^J 

 regular distribution in reference to 

 s of the day, and would probably disappear in a longer ser 

 of observations. 



pparently a 

 sibly be di: 



