118 AJSTNUAL REPORT SMITHSONIAN INSTITUTION, 1951 



funds had not been provided. Clark Mountain, near the Nevada 

 border in southern California, a region whose annual precipitation 

 averages about 3 inches, has been chosen as the best available location 

 in North America for this proposed station. 



W. H. Hoover, chief of the division, conducted special studies at 

 the Table Mountain station during October and November 1950. He 

 returned to the station at the close of the fiscal year to continue these 

 studies. 



Dr. W. E. Forsythe, of Cleveland, Ohio, who during the past 2^/^ 

 years has prepared the ninth revised edition of the Smithsonian Physi- 

 cal Tables, submitted his completed manuscript on June 1, 1951. 



Work in Washington. — As in previous years, the monthly solar- 

 constant records from the two field stations have been checked, com- 

 puted when necessary, and final corrections applied. 



Four reports have been submitted to the Office of the Quartermaster 

 General summarizing the radiation observations made at Montezuma, 

 Chile, during the year. These observations, a part of the textile- 

 exposure work under contract with the Quartermaster Department 

 and referred to in previous reports, were completed May 10. The 

 Quartermaster Department has indicated a desire to start a new series 

 of studies at Montezuma and also at the proposed Clark Mountain 

 station. 



Some years ago the Observatory developed an instrument, called 

 the melikeron, to measure outgoing radiation from the earth to space. 

 Several of these instruments have been used with fair success by the 

 United States Weather Bureau and others, and it has been the hope 

 to improve the melikeron and make it a more sensitive recording 

 instrument. Inasmuch as the Meteorological Division, Chemical 

 Corps, Camp Detrick, Md., is interested in the same general problem, 

 it was arranged to work cooperatively. At the close of the year a new 

 instrument was being assembled and undergoing preliminary tests 

 and calibration at Camp Detrick. 



During the year two silver-disk pyrheliometers were built, cali- 

 brated, and sold at cost as follows : 



S. I. No. 83 to the Government of Israel, Jerusalem. 

 S. I. No. 85 to the Air Force, Cambridge Research Laboratories, Cam- 

 bridge, Mass. 



A third pyrheliometer was lent to the Radiological Defense Labora- 

 tory, San Francisco, Calif., and three new orders were received. It is 

 a satisfaction to note the continued demand for Smithsonian pyrheli- 

 ometers. Since Dr. Abbot designed the silver-disk instrument 40 years 

 ago, over 100 have been built. Eighty-four have been sold to interested 

 institutions : 34 are in various parts of Europe, 19 in North America, 

 10 in South America, 14 in Asia and Australia, and 7 in Africa. In 



