OF THE HORIZONTAL FORCE. 



27 



Maxima and minima in the columns of ratios are marked with an asterisk. 



The inequality in the mean amount of the horizontal force disturbances in each 

 year, indicates the year 1843-44 as the minimum year. 



From the preceding results, we may assume the month of November, 1843, as 

 the epoch for the minimum of the eleven (ten ?) year inequality, as far as indicated 

 by the differential observations of the horizontal force. 



Further Analysis of t7te Disturbances of the Horizontal 'Force. The distribution 

 of the disturbances in number and mean amount over the several months of the 

 year has been given in Tables IX. and X. From Table IX. we learn that the 

 disturbances are greatest in number in September and March or April, or about the 

 time of the equinoxes, and least in number about January and June, or about the 

 time of the solstices. At the autumnal equinox the numbers exceed those of the 

 vernal equinox ; the same law was found at Toronto ; also the numbers are smaller 

 at the summer solstice than at the winter solstice, in perfect accordance with the 

 result found at Toronto. These results are shown graphically on the annexed dia- 

 gram, which contains also the ratio of the disturbances for the declination in which 

 the same law is apparent. 



(B). DISTRIBUTION OF THB NUMBER OF DISTURBANCES is THE SEVERAL MONTHS OF THE YEAK. 

 Full line for horizontal force. Dotted line for declination. 



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