54 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 65 



Peppier intended to repeat the work in 1914 at greater altitudes, but 

 we fear this may have been one of the valuable things cut off by war. 

 In figure 10 we give a plot of the pyrheliometer results at various 

 altitudes, as just collected. It seems to us that, with the complete 

 accord now reached between solar constant values obtained by the 

 spectro-bolometric method of Langley, applied nearly 1,000 times in 

 12 years, at four stations ranging from sea level to 4,420 meters, and 



1.9 



1.8 



_&.FreeEMoon. 

 " July II 1914. 



S/.7 



J i_ Peppler,Bzlloon. 

 Oct.l$,t fT3 



^ 



Aiio 



t,Mt.Whitncu. 

 Max. 



3.6 

 .3 



3 IS 



■S ~ 



1.5 



jAbboi.ftf.WllsoM. 

 ^ Mix. 



Max. 



Ocm. H 3 . 



20 



4\0 



60 



310 



Barometer. 



Fig. 10. — Pyrheliometry at Great Altitudes. 



from the Pacific Ocean to the Sahara Desert ; with air-masses rang- 

 ing from 1.1 to 20; with atmospheric humidity ranging from 0.6 to 

 22.6 millimeters of precipitable water; with temperatures ranging 

 from o° to 30 C. ; with sky transparency ranging from the glorious 

 dark blue above Mt. Whitney to the murky whiteness of the volcanic 

 ash filling the sky above Bassour in 19 12, it was superfluous to require 

 additional evidence. 



But new proofs are now shown in figure 10. This gives the results 

 of an independent method of solar constant investigation. In this 



