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SMITHSONIAN EXPLORATIONS, 1G. 1 2 



establish this point. Hence, it was thought best to return to Algeria 

 in k;i 2 for further data. 



In this expedition Mr. Abbot was assisted in Algeria by Mr. Anders 

 Knutson Angstrom, of L T psala, Sweden. 



The observations made by the Smithsonian party in Algeria in 

 1912 were on the whole very satisfactory. They occupied 64 days, 

 and <m more than 50 of these days Mr. F. E. Fowle made similar 



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ne at M'Sila, Algeria, an oasis 

 Photograph by Abbot. 



if the Sahara. 



observations on Alt. Wilson, in California. Much volcanic dust from 

 the eruption of Alt. Katmai in Alaska, [une '1 and 7, [912, was 

 diffused in the upper atmosphere, and greatly reduced the intensity 

 of solar radiation observed at both stations. Many otherwise ex- 

 cellent days were spoiled by it. I [owever, it did not prove fatal to the 

 success of the expedition. 



The results of the work of [9] 1 and [912 thoroughly establish the 

 supposed variability of the sun. 



