SECRETARY'S REPORT 133 



At the request of the United States Weather Bureau, another special 

 pyranometer was prepared and calibrated for use in standardizing the 

 Weather Bureau's network of Eppley pyrheliometers. A leveling 

 device and automatic shutter control were added to the pyranometer. 



Last year's report mentioned a cooperative arrangement with the 

 Meteorological Division, Chemical Corps, Camp Detrick, Md., to de- 

 velop a new improved type of melikeron, for the measurement of out- 

 going radiation from the earth to space. One of these instruments 

 has been completed and tested at Camp Detrick. A paper describing 

 this development was read by Dr. S. C. Stern of Camp Detrick at the 

 July meeting of the American Meteorological Society. 



Dr. C. G. Abbot, research associate, has continued his studies of 

 relationships between solar and terrestrial phenomena. His results 

 are described in several papers in volume 117 of the Smithsonian 

 Miscellaneous Collections. 



Work in the field. — In May 1952 a new series of tape exposures was 

 started at the Montezuma station, under contract with the Office of 

 the Quartermaster General. These exposures are a continuation of 

 the Quartermaster studies to determine the causes of the deterioration 

 of tentage materials. The tapes include samples of various textiles, 

 and the exposures and radiation measurements are similar to those 

 described in former years. 



At the Table Mountain station, the interesting study discussed in 

 last year's report, to determine the quantity of ozone in the upper 

 atmosphere from our daily bolographic records, continued under the 

 direction of Dr. Oliver K. Wulf, of the U. S. Weather Bureau and 

 the California Institute of Technology. Dr. Wulf has improved the 

 means for obtaining absolute values of the ozone from long-method 

 days. He then uses the long-method results to calibrate the relative 

 values obtained from the short-method observations at air mass 2.5. 



In July 1951 Mr. Hoover tested the double spectroscope set up in 

 the new tunnel at Table Mountain. He reports that, unfortunately, 

 the device is not sufficiently rigid to give satisfactory results. Con- 

 siderable alteration will be necessary. Mr. Hoover also prepared and 

 installed a very satisfactory device for recording the steadiness of 

 the sky during each holograph. It consists of a sensitive thermo- 

 element mounted in the coelostat beam. The resulting galvanometer 

 deflection, recorded upon a rotating drum, is an index of the steadiness 

 of the sun and sky radiation during each holograph. This record 

 has proved helpful in appraising pyrheliometer and pyranometer 

 readings at Table Mountain, where sudden changes in water vapor 

 content and quality of haze occur fairly frequently. 



