47 
ing of the Physical Section, read a paper on this subject 
showing some peculiarities of the distribution of Solar 
Radiation throughout the year, I have at his suggestion 
reduced and tabulated my observations bearing upon this 
point down to the end of 1866, making eleven years in all. 
Unfortunately the month of August is deficient in six years 
out of the eleven. The observations were made with 
Negretti and Zambras patent maximum thermometers, 
neither thermometer having any index error, but reading 
correctly with the standard throughout the scale. 
Taking the differences between the mean maximum 
black bulb reading in the sun, and the mean maximum 
reading in the shade for each month, we find a minimum in 
December and a maximum in July. The maximum occurs 
in the warmest month, but the minimum appears to occur 
some time before the coldest month arrives, viz. : January. 
If we take the differences between one month and the suc- 
ceeding one we find the following values : 
January to February 2 '02 
February to March -J- 4*64 
March to April + 4 ’06 
April to May + 1*67 
May to June — 04)9 
June to July + 0*56 
July to August — 2*39 
August to September — 2 4)7 
September to October — 3*46 
October to November — 3 ’21 
November to December — 1 ’32 
December to January -f 0*59 
From my observations the greatest increase in the amount 
of solar radiation appears to take place in March, and nearly 
as much in April, afterwards, up to July, the warmest 
month, the increase is remarkably small, and in June shows 
a slight amount of decrease. These figures do not quite 
