SECRETARY'S REPORT 123 



surface and as received upon the exposed tapes which are mounted at 

 an angle of 45° facing north. After a predetermined quantity of 

 solar radiation has fallen upon the tapes they are returned to the 

 Philadelphia Quartermaster Depot for a study of the amount of de- 

 terioration of the textiles due to humidity and to the amount of radi- 

 ation received. 



Seismographic records have been maintained for some years at 

 Montezuma for the United States Coast and Geodetic Survey. The 

 Survey recently sent to Montezuma a new modem seismometer, with 

 accessories, which is now being installed. It is expected that greatly 

 improved earthquake records will result. 



At Table Mountain, Calif., Hoover and Froiland obtained a very 

 complete series of comparisons between the Smithsonian double-tube, 

 water-flow, standard pyrheliometer and substandard silver-disk 

 pyrheliometer S. I. 5. These comparisons confirm the results of three 

 previous determinations made at Mount Wilson in the years 1932, 

 1934, and 1947. This confirmation of the permanence of the constants 

 of the instruments is very gratifying since the 1962 comparisons are 

 entirely independent, being made at a different station and by different 

 observers. 



The filter form of pyranometer, mentioned in last year's report as 

 sent to Table Mountain for testing, proved to have a troublesome drift 

 under field conditions. It was returned to Washington for altera- 

 tions. At the close of the year a new series of tests was in progress at 

 Table Mountain. 



The instrument installed last year by Mr. Hoover to measure the 

 optical quality of the sky continues to serve as an independent means 

 for judging the steadiness of the sky during observations. It has now 

 been altered to register through a Beckman photopen recorder, thus 

 eliminating the process of daily removing and developing a photo- 

 graphic record. 



Owing to a temporary shortage of personnel, progress in the ozone 

 studies referred to in last year's report was somewhat delayed. This 

 project is being resumed as rapidly as possible. 



DIVISION OF RADIATION AND ORGANISMS 

 (Report prepared by Dr. R. B. Withkow, cMef of the division) 



The research of the Division has been concerned chiefly with in- 

 vestigations of the physiological and biochemical processes by which 

 light regulates plant growth and the mechanisms of the action of the 

 auxin-type gi'owth hormones. While most of the sunlight absorbed 

 by plants is used in the production of food materials through the 

 process of photosynthesis, a small part of the light energy is required 

 for the production of chlorophyll and in the initiation of photochemi- 



