SECRETARY'S REPORT 47 



3. Previous reports have mentioned the radiation measurements 

 made by the division under contract with the Office of the Quarter- 

 master General in connection with Quartermaster Corps researches 

 to determine the causes for the deterioration of exposed textiles. The 

 work was begun early in 1945 with the preparation of proper equip- 

 ment to measure the total sun and sky radiation received upon the 

 fabrics, both in the open, and under various filters. Actual measure- 

 ments began at Camp Lee, Va., in December 1945 and continued 

 through November 1947. To determine the effect of a moist, sea-level 

 environment, similar exposures and measurements were made at 

 Miami, Fla., during 1948 and 1949. These also included spectrobolo- 

 metric measurements made with equipment formerly used in solar- 

 constant measurements at Tyrone, N. Mex. In 1950-53 similar ex- 

 posures and measurements were made at Montezuma, Chile, a dry, 

 high-altitude station. A summary of all these measurements is given 

 in volume 7 of the Annals, chapter 6. The contract between the Office 

 of the Quartermaster General and the Smithsonian Institution expired 

 September 30, 1953. Subsequent to this a complete inventory of all 

 equipment acquired was prepared. Through the cooperation of the 

 Quartermaster Corps, the Smithsonian Institution was permitted to 

 purchase at reasonable cost the bulk of this equipment for continued 

 use in the Astrophysical Observatory. 



4. In addition to routine calibrations of instruments used in the 

 field, the following calibrations were made for others: 



(a) Mr. Mateer, of the Meteorological Service of Canada, brought 

 silver-disk pyrheliometer S. I. 14 from the University of Toronto to 

 Washington for recalibration. In spite of adverse weather conditions, 

 satisfactory comparisons were made, indicating relatively little change 

 in its constant since the last calibration in 1937. 



(5) One of three modified Angstrom pyrheliometers, purchased 

 in 1951 from the Astrophysical Observatory by the Meteorological 

 Service of the Belgian Congo, was accidentally injured in use. It was 

 returned to us by air in May, rebuilt with new manganin strips and 

 new thermoelements by instrumentmaker J. H. Harrison, recalibrated 

 partly by Mr. Harrison and Mr. xYldrich in Washington and partly 

 in the better skies of Table Mountain, Calif., and finally returned by 

 air to the Belgian Congo. 



(c) With the help of T. H. MacDonald and Norman Foster of the 

 IT. S. Weather Bureau, calibrations were made of a Weather Bureau 

 normal-incidence Eppley pyrheliometer against our substandard pyr- 

 heliometer. In addition, the Weather Bureau staff was interested in 

 attempting to transform their silver-disk pyrheliometer S. I. 78 into 

 an automatically recording instrument. Mr. Harrison of our staff 

 inserted a copper-constantan thermoelement attached to the back of 

 the silver disk of S. I. 78. Mr. Foster devised an automatic shutter 



