62 



REPORT 187] . 



Table II, Ordinates of Curve of Spot frequency. 



We may regard the various maxima of the spot-curve as indicative :— First, 

 of a greater number of observations during the intervals which furnish the 

 maxima. It is true the column of observations may countenance this view ; 

 but it does not hold in all cases, neither are the greater number of observa- 

 tions so pronounced as the maxima of the curve. Second, of a clearer state 

 of the earth's atmosphere than usual, enabling us to see more spots than 

 when it is ordinarily translucent. This may to some extent explain the 

 occurrence of maxima separated by several intervals, and probably those in- 

 stances where we have a larger number of spots with a smaller number of 

 observations. Third, of an actual increase of visibility of the spots them- 

 selves at different and widely separated epochs, the observations of such 

 increased visibility falling at those intervals at which the maxima were re- 

 corded. The following are the epochs at which the greatest number of spots 

 were observed corresponding with the maxima of the curve :— 



First maximum. Interval 2. 1870, Jan. 10, 12 spots, 15 for the whole 

 interval, from 7 observations. 



