12 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 32 



Astrophysical Ohservatory. — Volume V of the annals of the ob- 

 servatory was published during the year. This volume covers the 

 work of the period 1920 to 1930, including descriptions of the sta- 

 tions and instruments, discussions of sources of error, methods of 

 observation, tables of daily observations, 10-day and monthly means, 

 and a discussion of the results of the several observing stations dur- 

 ing the 10-year period. New instruments were designed and con- 

 structed for solar researches, those completed being a new 2-chamber 

 water-flow pyrheliometer, a doubly dispersing spectroscope designed 

 to observe the extreme infra-red solar spectrum between wave lengths 

 10 and 30 microns, and the periodometer, an instrument for investi- 

 gation of periodicities in solar and terrestrial phenomena. Daily 

 observations of the solar constant of radiation were continued at 

 Montezuma, Chile, and Table Mountain, Calif. The station at 

 Mount Brukkaros was closed. A volcanic eruption in Chile during 

 the year made the atmosphere at Montezuma so hazy that satisfac- 

 tory measurements of the solar constant could not be made there 

 after April, 1932. In the search for a desirable observatory site in 

 Africa, A. F. Moore found Mount Saint Katherine in the Sinai 

 Peninsula in Egypt to be the most promising of those investigated. 



Division of Radiation and Organisms.'^ — The carbon dioxide as- 

 similated by wheat has been measured for light intensities varying 

 from 78 to 1,900 foot-candles and for carbon dioxide concentrations 

 varying from 0.004 to 0.500 per cent. A set of individual plant- 

 growth chambers has been completed, permitting comparative ob- 

 servations on the effects of different wave-length distributions of 

 light; a first experiment indicates that an excessive intensity in the 

 less refrangible end of the spectrum, that is, the infra-red and 

 extreme red, is accountable for much of the abnormal appearance 

 of plants grown in artificial light. An interesting set of experi- 

 ments has been conducted on the lethal effects of the ultra-violet 

 rays upon unicellular algae. Phototropic investigations have been 

 carried further into the blue end of the spectrum. Ultra-violet 

 measurements of the mercury arc with the double monochromator 

 have been carried to the point where absolute intensities can be de- 

 termined with reasonable certainty. Cooperative work with the 

 Department of Agriculture includes a study of the effects of light 

 upon noncompetitive crop plants. 



Internatio-nal Catalogue of Scientific Literature. — In addition to 

 the routine work of the bureau, letters were sent by the Secretary 

 of the Institution to all of the former regional bureaus asking 

 whether they would again cooperate in the publication of the cata- 

 logue by supplying references to the scientific literature of their 



2 The Division of Radiation and Organisms is supported almost wholly by annual grants 

 from private sources. 



