APPENDIX 8 

 EEPORT ON THE ASTEOPHYSICAL OBSERVATORY 



Sir : I have the honor to submit the following report on the opera- 

 tions of the Astrophysical Observatory for the fiscal year ended June 

 30, 1947 : 



The Observatory has two divisions: (1) The original Division of 

 Astrophysical Research, engaged primarily in a study of solar radia- 

 tion, and (2) the more recently established Division of Radiation and 

 Organisms, engaged in a study of the effects of radiation on organisms. 



Both divisions of the Observatory helped to celebrate the one- 

 hundredth anniversary of the founding of the Smithsonian Institution 

 by participating in a special exhibit illustrating the activities of the 

 Institution. Mechanical working models were displayed showing 

 typical instruments as used by the Observatory at Camp Lee, Va., and 

 also showing types of research in the Division of Radiation and Organ- 

 isms, with emphasis placed on the role of light in the growth and de- 

 velopment of plants. 



(1) DIVISION OF ASTROPHYSICAL RESEARCH 



IVork in Washington. — As in the past, our first concern has been to 

 appraise the solar-constant values received from our field stations and 

 to plan and develop improvements in instrumental equipment and 

 methods. Our plans have seemed unduly slow in fulfillment, but by 

 way of anticipation we may state that in the near future at one of our 

 field stations we expect to try several innovations. These include an 

 improved vacuum bolometer, a fused quartz prism, and aluminized 

 mirrors in the optical path in place of stellite. The resulting large 

 increase in ultraviolet deflections should permit a more accurate study 

 of the day-to-day changes in this important region. 



Our second concern has been the work at Camp Lee, Va., under con- 

 tract with the Office of the Quartermaster General, described in last 

 year's report. The records of the Camp Lee measurements of sun and 

 sky radiation have been compiled and prepared for publication in a 

 series of 11 reports to the Quartermaster General. The maintenance 

 of the equipment and observations at Camp Lee, and the preparation 

 of the reports have all been under the direction of William H. Hoover. 

 With the close of the fiscal year we have completed 18 months of con- 



118 



