140 MR. Q. V. VERNON 



month and the succeeding one^ we find the following 

 values : — 



o 



January to February 4-2*02 



February to March +4*64 



March to April 4-4'o6 



April to May +1*67 



May to June —0*09 



June to July +0*56 



July to August ~~^*39 



August to September — 207 



September to October , —3*46 



October to November —3*21 



November to December — 1*32 



December to January +o'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 agree with those deduced from the Oxford 

 observations by Mr. Baxendell, but they very clearly con- 

 firm the fact that a large amount of solar heat is dispersed 

 in some way, and without a corresponding eff'ect upon the 

 thermometer, or the difference between the maximum in 

 the sun and the maximum in the shade would show a large 

 increase in the months of maximum temperature. 



The greatest effect of solar radiation, therefore, appears 

 to occur in the spring, and this is in accordance with the 

 very rapid growth of vegetation we often see suddenly 

 take place in early spring. 



