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SUNSPOTS AND EARTH TEMPERATURES. 
By J. R. Sutton. 
Table I gives the results of a comparison between the six-foot earth 
temperatures observed at Kenilworth (Kimberley) for the nineteen years 
1900 to 1918, and the Wolfer's observed sunspot numbers as published in 
the ' Monthly Weather Review. 1 The comparison has been made by taking 
the mean earth temperature of any month and the sunspot number of the 
previous month : this in order to allow something for the lagging of the 
earth temperature wave with depth.* The means have then been grouped 
according to spot numbers below or above thirty. The work was begun more 
out of curiosity than with the expectation of getting any tangible result ; 
and the direct comparison of curves was not very encouraging. The 
grouping, on the contrary, shows a somewhat higher temperature for a lower 
spot number, and that most definitely in the summer half of the year. If 
the one could be regarded as the direct result of the other this would 
indicate more intense radiation when the sun is free from spots than at other 
times. Direct observations of the solar radiation, however, are interpreted to 
mean less intensity when the sun is free from spots. t 
The 1 '7-metre earth temperatures observed at Cordoba for the fourteen 
years 1887 to 1900 have also been compared with the spot numbers in the same 
way. The results appear in Table II. They are of the same tendency, i. e. 
higher temperatures with fewer spots, though much more pronounced. So 
also the summer half is the more definite. 
Table III refers to the five-foot earth temperatures observed at Adelaide 
during the thirty years 1878 to 1907. Proximity to the sea may have 
influenced the temperatures. Only in the summer months is any difference 
of temperature shown, though that is in the same direction as it is at the 
other stations. 
In all three cases the results, so far as they go, are in agreement with 
previous ones. 
* But no allowance has been made for the lagging in the annual values at the 
foot of the Table. 
t " It seems likely that increased values of the solar constant attend increased 
sunspot numbers." McAdie, e The Principles of Aerography/ 1917, p. 276. 
