NO. 3 



SOLAR VARIATION AND WEATHER — ABBOT 



Fig. 1. — Water-flow standard pyrheliometer of 1913. 



Mt. Whitney to the murky whiteness of the volcanic ash filling the sky above 

 Bassour in 1912, it was superfluous to require additional evidence. 



But new proofs are now shown in figure 10 [fig. 7, p. 10, of present paper]. 

 This gives the results of an independent method of solar constant investigation. 

 In this method the observer, starting from sea level, measures the solar radia- 

 tion at highest sun under the most favorable circumstances, and advances 

 from one level to another, until he stands on the highest practicable mountain 

 peak. Thence he ascends in a balloon to the highest level at which a man may 

 live. Finally he commits his instrument to a free balloon, and launches it to 

 record automatically the solar radiation as high as balloons may rise, and where 

 the atmospheric pressure is reduced to the twenty-fifth part of its sea level 

 value. All these observations have been made. They verify the former con- 



FiG. 2.— Double water-flow electrical compensation pyrheliometer. 



