THE SITN-SPOT PERIOD. 



143 



Fig*. 1 is a o-raphical representation of the results contained in the 

 table. Ordinates of the curve of temperatures are taken directly from 

 the column headed "Deviations," and plotted in the usual way, while 

 the ordinates of the curve of sun spots are plotted with decreasing 

 values toward the top of the sheet, so as to give a figure apparently 

 the inverse of the sun-spot f requeue}". 



It will be seen at once that the two curves run in a general way 



parallel. 



Temperature ricpartnres. 



Fig. 1.— Comparison of sun spots and mean temperatures. 



The following more careful discussion goes to show' that their simi- 

 larity extends even to minor details: 



1. If we consider the dates of maxima and minima of temperature 

 and sun spots, respectivel}', as found in the two curves, we may express 

 the results in the form of a table as follows: 



Table II. — Maxima and minima of sun spots and temperatures. 



This comparison shows that the agreement between the times of 

 minima of temperature and maxima of sun spots on the one hand 

 and between maxima of temperature and minima of sun spots on the 

 other is very satisfactoiy. 



2. It is well known that the interval between a minimum of sun 

 spots and the succeeding maximum is usually shorter than the inter- 

 val between a maximum and the following mininmm. The 2i sun-spot 



