SUN'S HEAT — ABBOT. 161 



the observations in the new station in Arizona. He is succeeded 

 as director in South America by Mr. L. H. Abbot. 



ARIZONA STATION. 



The remainder of Mr. Roebling's gift was available to transfer 

 the solar radiation outfit hitherto at Mount Wilson to a new locality 

 chosen with regard to its cloudlessness on Mount Harqua Hala, 

 Arizona. The choice of the station resulted from an investigation 

 undertaken by the Weather Bureau through its local chief of opera- 

 tions at Phoenix, Arizona, Mr. Fletcher. This officer made an inves- 

 tigation of many proposed sites in California, Nevada, and Ari- 

 zona, and at length the choice narrowed down to the vicinity of 

 Bagdad and Cima, towns in California, and to the vicinity of Wen- 

 den, Arizona. Special cloud observations were undertaken by 

 observers in these localities, which after six months of observing 

 indicated a preference for the region of Wenden, Arizona. Accord- 

 ingly, the writer, on the way to Mount Wilson, in June, 1920, let 

 contracts in Wenclen for the construction of a building on Mount 

 Harqua Hala. situated about 12 miles to the east of Wenden at an 

 altitude of 5,600 feet. The building, with walls a foot thick of 

 adobe, and having the lower story, partly underground, reserved for 

 the apparatus while the upper was designed for observers' quarters 

 and the computing room, was completed by the end of August and 

 occupied late in September. 



The " solar constant " apparatus, which had been employed on 

 Mount Wilson from 1905 to 1920, was then removed and set up for 

 use on Mount Harqua Hala. The first observations were made on 

 October 2, and it is proposed to continue them for several years on 

 every favorable occasion. 



The weather on Mount Harqua Hala has hitherto proved more 

 favorable than was expected, so that in the first 65 days of occupa- 

 tion more than 70 per cent proved favorable for observing. Little 

 difference in the transparency between morning and afternoon has 

 been noted, which is a great improvement over the condition upon 

 Mount Wilson, where the change of the wind from land to ocean 

 breezes brings up a mass of haze from the humidity, dust and smoke 

 of the cities of Pasadena and Los Angeles. 



The conditions of living on a desert mountain remote from any 

 town are, to be sure, rather remarkable. Mount Harqua Hala has 

 no trees, but only shrubs and plants. There is no water at the top 

 except what falls in the slight rainfall of from 5 to 10 inches which 

 prevails there, mostly in the months of January and July. Com- 

 munication with the town of Wenden is made by using the Morse 

 code with a strong light at night or with sunlight by day, and 

 42803°— 22 11 



