PARTIAL RADIATORS. 



J 43 



E 



5 6 7 8 9/0// /2/t 



Fig. ioi. Emissioa of complete radiator (a) and (6); Emission of quartz (computed). 



for a column of air no meters in length, containing 1.2 mm. precipitable 

 water, 1 and is due to Langley (loc. cit.). A thick layer would shift the 

 maximum at 8 ft toward 8.3 ft found in the moon's radiation curve. In 

 fig. 103, curves a, c, and d show some of Langley's observed lunar radia- 



5 6 7 6 9 10 II I2jU 



Fig. 102. Emission of quartz (curves a and b); transmission of air (Langley). 



tion curves, and as a whole there is a close parallelism between the theo- 

 retical curve b, from fig. 102, and the observed curves, at 10.7 ft, where we 

 have to consider only atmospheric absorption. From & to g ft, however, 



1 Apparently water-vapor is more transparent than a film of the liquid, for a film of even 

 one-tenth this thickness is opaque to heat rays beyond 5 /*. 



