28 



DISCUSSION OF THE DISTURBANCES 



Table X. shows that, in reference to the average magnitude of the disturb- 

 ances, the same law holds good, viz: the greatest relative magnitude occurring 

 about the time of the equinoxes ; the greatest amount corresponding to the autumnal 

 equinox, and the least to about the time of the solstices, the smaller amount occur- 

 ring near the summer solstice. The average magnitude of the disturbances of tin 1 

 declination was found subject to the same law. 



If we separate the disturbances which increase the force from those which decrease 

 it, we may form the two following tallies of tin 1 distribution of the disturbances in 

 number and average amount over the several months of the years. 



In each year the number of disturbances increasing the force is less than the 

 number which decreases it; the numbers of increase are to the numbers of decrease 

 as 1: l.s. The numbers of the monthly ratio for the increasing disturbances exhibit 

 the same law as found in Table IX.: with respect to the numbers for the 

 decreasing force the law is apparently less distinctly marked; the maximum seems 

 tn occur about two months later (before the winter solstice), at a time when the 

 number for increasing force is apparently at its minimum. This indistinctness in 

 the law may possibly be due to an irregular distribution in reference to the hours 

 of the day, and could only disappear through a longer series of observations. 



