654 PROCEEDINGS OF THE AMERICAN ACADEMr. 



giving for the 



Visible portion, 32 per cent, 



Tnincil-ilo " fiS " 



of the whole. 



Invisible " 68 



Loss OF Heat in Tra"\^rse of the Air. 



Turning, now, from the question of the initial heat for different parts 

 of the spectrum at the time the solar radiation enters the air, we come 

 next to consider the loss the several rays sustain in their traverse 

 of it. 



From Very's curves for the radiation at the confines of the atmosphere 

 at Camp Whitney and at Lone Pine, 18 A = 1.2 /a, we get the amount 

 transmitted at these two stations, employing planimetric measurement 

 as before, and introducing with him the absorption in the red and 

 inira-red Irom the Alleghany measures, which he considers the same 

 at Lone Pine. 



From Very's measures we have, calling the whole heat at the 

 confines of the atmosphere unity, — 



Transmission. 



\ = 0.2 ^-1.2 IX. A = 1.2 ;u.-15 M. 



Outside 50. 50. 



Camp Whitney . . . 31.3 



Lone Pine 24.3 25.1 



To get that for sea-level we shall take Crova's actinometric measures 

 at Montpellier (height 40 m.), made on August 13, 1888, at 12'' 30", 

 under a barometer of 761 mm. Simultaneously with these, other self- 

 registering ones were taken by him on Mt. Ventoux (height 2000 m.). 

 The respective calories he obtained were, — 



Montpellier. Mt. Ventoiuc. 



Aug. 13, 12'' 30™, 1888. 0.975 calories, 1.360 calories, 



bar. 761.1 mm. bar. 613.5 mm. 



We shall reduce these to the same scale as the Lone Pine results, 

 made with the pyrheliometer and used by Very, to wit : 



Lone Pine. 



Aug. 11, 12, 14, 12^-1 2" 30™, 1881. 1.533 calories, bar. 663 mm. 



giving for 



Montpellier. Mt. Ventoux. 



1.180 calories. 1.643 calories. 



