330 
PHYSICS: W. W. COBLENTZ 
Proc. N. a. S. 
thereafter considerably overbalance the gravitational pull. This happens 
when the temperature- time coefficient dd/dt is negative. When the latter 
is positive, gravitation and the radiant forces cooperate. It is seen, more- 
over, that the higher exhaustions (a few tenths mm. and less), are (like 
the plenum) favorable to strong radiant forces; whereas in moderate 
exhaustions (a few mihimeters) the radiant forces tend to a minimum, 
so that the night observations become more and more trustworthy. This 
may be inferred from the gradual simplification of the F, R curves between 
Aug. 1 and August 14. In corroboration, the apparatus was again ex- 
hausted on Aug. 14 and tested about 12 hours later on the morning of 
Aug. 15. It is seen that the strong radiant forces have reappeared. 
* Advance note from a report to the Carnegie Institution of Washington, D. C. 
FURTHER MEASUREMENTS OF STELLAR TEMPERATURES 
AND PLANETARY RADIA TION 
By W. W. C0BI.KNTZ 
Bureau of Standards, WAsmNGTON, D. C. 
Communicated September 21, 1922 
1. Introductory Statement. — In a previous communication ^ estimates 
were given of the temperatures of 16 stars as determined from their spectral 
energy distribution which was determined by means of a new spectral 
radiometer, consisting of a series of transmission screens and a Vacuum 
thermocouple. 
By means of these screens, which, either singly or in combination, had 
a uniformly high transmission over a fairly narrow region of the spectrum 
and terminating abruptly to complete opacity in the rest of the spectrum, 
it was possible to obtain the radiation intensity in the complete stellar 
spectrum as transmitted by our atmosphere. 
Not being equipped at that time for making radiometric measurements 
on the Sun, the effective temperature of which is known with some degree 
of accuracy, and hence could be used as a standard, an estimate of the 
effective temperature of a star was obtained by two methods, one of which 
consisted in using a solar type star (a Aurigae, Class G o) as a standard. 
This seemed permissible in view of the fact that the observed temperature 
(6000° K) of a Aurigae was found to be in close agreement with that as- 
signed to the Sun. 
The object of the present communication is to report a verification of 
the above-mentioned stellar radiation measurements, by similar measure- 
