REPORT OF THE SECRETARY. 85 



year's report, a proposed expedition under the auspices of the Hodg- 

 kins fund to observe the solar radiation in the most cloudless region 

 of Chile was temporarily postponed on account of the entry of the 

 United States into war, and the expedition was diverted for a time to 

 Hump Mountain in western North Carolina. Observations of the 

 solar constant of radiation were made there, when weather permitted, 

 until March, 1918. By that time it had grown to be certain that the 

 site was too cloudy for the work, and, notwithstanding grave difficul- 

 ties brought about by the war, the expedition was sent to Chile as 

 originally proposed. 



Director A. F. Moore and Assistant L. H. Abbot landed at Anto- 

 fagasta, Chile, on June 16, 1918, with a large equipment of apparatus 

 and supplies suitable to the investigation. They were greatly aided 

 by the governor of the Province, the United States consul, and others, 

 and the Chile Exploration Co. generously gave them the use of build- 

 ings and other valuable facilities at their disused mine at Chorillos, 

 near Calama. Calama is a station on the railroad east of the nitrate 

 desert, on the bank of the River Loa, at latitude N. 22° 28', longitude 

 W. 68° 56', altitude 2,250 meters. Manuscript of daily meteorologi- 

 cal records of two years, most kindly copied by Dr. Walter Knoche, 

 former director of the Chilean Meteorological Service, lead us to hope 

 for as many as 300 days per year favorable to solar-constant work 

 there. The experiments are to be continued daily, as far as possible, 

 for several years. They should furnish meteorologists with a firm 

 basis for estimating the effects of the solar variability on the terres- 

 trial climate. 



TOTAL SOLAR ECLIPSE. 



Owing to the pressure of military investigations our preparations 

 for observing the total solar eclipse of June 8, 1918, were not exten- 

 sive. The observations proposed were confined to observing the 

 eclipse phenomena visually, photographing the solar corona, and de- 

 termining the sun and sky radiation during the partial phase, and 

 the " nocturnal " radiation during the total phase by means of the 

 pyranometer. 



Necessary apparatus was prepared at the observatory shop. It 

 comprised parts for two 11-foot focus cameras, each of 3 inches apera- 

 ture with equatorial mounting and driving clockwork, and two pyra- 

 nometers. The observations were in charge of Mr. L. B. Aldrich, 

 who Was assisted by Mr. A. Kramer and by Rev. Clarence Woodman, 

 a volunteer observer who had aided us in 1900. 



The station selected was near Lakin, Kans., not because it was the 

 most favorable, but because the more favorable parts of the eclipse 

 track farther west would be occupied, it was known, by many eclipse 

 parties, so that the chances of having clear weather at some station 



