SECRETARY'S REPORT 119 



spectrobolometric observations at the two tunnels, each tunnel operat- 

 ing with independent equipment but observing the sun through the 

 same sky. As a preliminary to various special experiments that are 

 contemplated with the new tunnel, there was in progress at the end 

 of the fiscal year a series of duplicate solar-constant observations 

 taken exactly simultaneously. A study of these simultaneous obser- 

 vations will doubtless furnish interesting information concerning the 

 dependability of the instrumental and observational procedures. 



DIVISION OF RADIATION AND ORGANISMS 

 *' ' (Report prepared by R. B. Withrow) 



The principal activities of the Division of Radiation and Organisms 

 for the first two-thirds of the year were concerned with concluding the 

 reorganization and reconstruction of the laboratory facilities. The 

 division laboratories are now in first-class condition for plant photo- 

 chemical research and include four constant-condition rooms, as 

 follows : 



A 2° C. cold room for chemical isolation and analyses of labile 

 compounds, 



A plant-growing room with one large luminaire for the routine 

 production of plant material and eight small compartments for grow- 

 ing plants under controlled conditions of intensity and wavelength. 



A monochromator room for action spectrum studies. 



A general experimentation room. 



A new type of fluorescent-incandescent luminaire has been devel- 

 oped which involves the use of a special type of lamp holder for the 

 fluorescent lamps, making it possible to put thirty-four 8-foot Slim- 

 line lamps in a unit 4 feet wide and 8 feet long. The separation 

 between the tubes is only yi inch. Behind the lamps is a bank of 

 twelve 60-watt incandescent lamps. These lamps raise the long- 

 wavelength energ}^ level of the unit to permit a better type of growth 

 than is possible with fluorescent lamps alone. The fluorescent lamps 

 operate in series at 450 milliamperes on an 18,000-volt transformer 

 and reactor. This arrangement greatly simplifies wu-ing and makes 

 it possible to remove all auxiliary equipment from the growing room. 

 The luminaire has a glass window and an exhaust system, making it 

 possible to operate with a power input of 4 kilowatts without excessive 

 heating. With this luminaire it is possible to obtain 2,500 foot- 

 candles 2 feet below the unit. This is nearly double the intensity 

 possible with similar luminaires designed around conventional aux- 

 iliaries and standard lamp holders. 



A self-condensing type of water-cooled incandescent lamp luminaire 

 has been developed which condenses the water vapor from the water- 



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