NOTE ON MR. CLAYTON'S INVESTIGATIONS OF THE 



RELATIONS OF RADIATION AND TEMPERATURE 



By C. G. abbot 



Nearly forty years ago the late Secretary Langley, at that time 

 Director of the Allegheny Observatory, made the following remark- 

 able statement in his report of the Mt. Whitney Expedition ^ : 



" If the observation of the amount of heat the sun sends the earth 

 is among the most important and difficult in astronomical physics it 

 may also be termed the fundamental problem of meteorology, nearly 

 all whose phenomena would become predictable if we knew both the 

 original quantity and kind of this heat ; how it affects the constituents 

 of the atmosphere on its passage earthward ; how much of it reaches 

 the soil ; how through the aid of the atmosphere it maintains the 

 surface temperature of this planet, and how in diminished quantity 

 and altered kind it is finally returned to outer space." 



Let us set over against this pronouncement of Langley the final 

 conclusion of Mr. Clayton in the paper which follows : " The results 

 of these researches have led me to believe : i . That if there were no 

 variation in solar radiation the atmospheric motions would establish 

 a stable system with exchanges of air between equator and pole and 

 between ocean and land, in which the only variations would be daily 

 and annual changes set in operation by the relative motions of the 

 earth and sun. 2. The existing abnormal changes, which we call 

 weather, have their origins chiefly, if not entirely, in the variations of 

 solar radiation." 



Mr. Clayton's researches have been long, painstaking, and con- 

 scientious. By the correlation method and by the direct method of 

 comparison he has compared all of the solar radiation observations 

 of the Smithsonian Institution made at Mt. Wilson and at Calama, 

 Chile, with the temperatures and rainfall of Argentina. His con- 

 clusion is of a very revolutionary character and deserves the most 

 careful attention of meteorologists and students of solar physics. 



I wish to remark in connection with the subject that as I have been 

 concerned in the collection of all of the data on solar radiation which 

 Mr. Clayton has used, I am free to point out how imperfect it is. In 



^ Professional Papers of the Signal Service, XV, p. 11. 



