80 
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 two maxima — 
one in May, and another in August ; and two minima — one 
in June, and another in December. 
In order to project the gradual rise and fall of solar 
radiation for each month, I have adopted the form of table 
presented by Mr. Vernon in his reductions of similar 
observations. Thus, if we take the differences between 
one month and the succeeding one, we find the following 
values : — - 
o 
January to February + 2 , 80 
February to March .....+ 2 # 98 
March to April + 3-16 
April to May + 1*14 
May to June ........... 0*80 
June to July + 0*38 
July to August + Oh 6 
August to September - 1 '48 
September to October - 5*28 
October to November - 2*26 
November to December - 3-06 
December to January + l - 86 
The foregoing table shows a very regular though rapid 
increase of the amount of solar radiation from J anuary till 
April, which is only slightly exceeded in May. We have 
then a slight decrease, and afterwards another maximum in 
August. Then follows a very rapid decrease to October, 
which continues, though not so rapidly, to the end of the 
year. This table shows that the observations at Eccles 
have a projection very similar to the one presented by Mr. 
Baxendell on page 38, vol. VII. of the “Proceedings;” and 
I have no doubt that if the observations had extended over 
a longer period, the similarity would have been more 
striking. 
