IRoebUnG 3Fun& 



OBSERVING THE SUN AT 19,300 FEET ALTITUDE, 



MOUNT AUNCONQUILCHA. CHILE 



By C. p. butler. 



If solar ol).servations could be tnade on the moon, the readings of 

 a silver-disk pyrhelionieter alone would give us the solar constant. 

 Since this is impossible, we may approximate the solar constant by 

 making radiation measurements at different altitudes. The highest 

 observations made heretofore with the silver-disk pyrhelionieter were 

 those taken by Dr. C. G. Abbot on Mount Whitney, 14,500 feet. 



I was invited by the International High Altitude Expedition to join 

 them at their highest station for the purpose of making solar observa- 

 tions. Their object was to measure the effects of extreme high alti- 

 tudes on the human body mainly through the analysis of blood taken 

 from the men at different altitudes. All the experiments were made 

 in northern Chile, culminating on Mount Aunconquilcha. 



Ollague is a small town on the frontier between Chile and Bolivia, 

 situated on a great level altoplano stretching many miles from the 

 sulfur peaks. The terrain is broken into rough hummocks of salt 

 incrustations, with here and there small salt-water marshes. It was 

 here that the expedition kept the four railway cars which housed their 

 heavier instruments. 



" I stayed the first night in one of the sleeping cars in Ollague, and 

 the next morning I left by motor truck for the Quilcha Camp where 

 most of the men were stationed. The truck was filled with a hetero- 

 geneous load of bundles, trunks, beds and bedding, and tools, and its 

 passengers included 12 miners and 2 women. On top of the load 

 were precariously perched the pyrheliometers and the theodolite, with 

 the assurance of one of the men that he would look after it. With 

 the load nearly double the truck's capacity and the bad curves in the 

 road, it seemed to me that every sway would pitch some boxes off. 

 However, nothing happened to the instruments — just to my nerves. 



The Quilcha Camp is located at an altitude of 17,400 feet and is 

 said to be the highest permanent human settlement in the world. The 

 word " permanent " must not be taken too seriously, however, be- 

 cause the men and women who live here suffer from diseases peculiar 



Smithsonian Miscellaneous Collections, Vol. 95, No. 1 



