10 



ANALYSIS OF THE 



Table X. — Aggregate amount and number of Disturbances in each 

 Year (July to July) arranged for Disturbances Increasing and 

 Disturbances Decreasing the Force, with Ratios of Sums. 





Sun., 





Sum. 



Ratio. 



Tear. 



+ 



n 





+ 



- 



1841—1842 

 1842—1843 

 1843—1844 

 1844—1845 



.45299 

 .25347 

 .19228 

 .13870 



313 

 180 

 158 

 103 



.33537 

 .26310 

 .13570 

 .06629 



245 



199 



114 



53 



1.75 

 0.98 

 0.74 

 0.53 



1.67 

 1.32 

 0.68 

 0.33 



The inequality of tlie eleven year period is equally well marked for disturbances 

 increasing and for disturbances decreasing the total force. 



The sum of the positive values is 1.03744, and of the negative values 0.80046 ; 

 increasing disturbances are therefore preponderating in the ratio of 1.3 to 1. In 

 the year 1842-1843, hovi^ever, decreasing disturbances were in excess over increas- 

 ing ones, and at Toronto between 1844 and 1848, the general effect of the larger 

 disturbances of the force was to decrease the total magnetic force more than to 

 increase it. The excess in the different years appears to be rather irregular. 



The following tables exhibit the diurnal inequality of the disturbances, the 

 whole series (beginning with February, 1841) is employed. The sums, numbers, 

 and ratios given apply to an epoch 20 minutes later than indicated by the tables. 



Table XI. — Aggregate amount and number of Disturbances of the 



Total Force, distributed over the even Hours op the Day, and 



Ratio showing the Diurnal Inequality of the Sum. 



Hoav. 



Sam. 



n 



Ratio. 







.19733 



150 



1.19 



2 













.20046 



148 



1.22 



4 













.20018 



148 



1.21 



6 













.17163 



121 



1.04 



8 













.13858 



106 



0.84 



10 













.13691 



105 



0.83 



Noon 













.15058 



115 



0.92 



14 













.19949 



144 



1.21 



16 













.14958 



116 



0.91 



18 













.13974 



103 



0.85 



211 













.13176 



97 



O.SO 



22 













.16077 



117 



0.98 



The hourly disturbances exhibit a regular double progression with a principal 

 maximum at 2 A. M., and a principal minimum at 8 P. M., also a secondary maxi- 

 mum about 2 P. M., and a secondary minimum abut 10 A. M. At Toronto these 

 hours were respectively 3 A.M., 11 A.M., and 5 P.M., 9 P.M., showing an ex- 

 change of the hours of the principal and secondary minimum ; the disturbance at 

 the hour of maximum is about eleven times greater than at the minimum hour, 

 whereas this proportion is but one and a half to one at Philadelphia. 



