REPORT OF THE SECRETARY 



109 



With it and with a new optical arrangement designed by the 

 writer, and largely constructed by him, very interesting results were 

 obtained. The spectra of 10 stars, including the sim, as cast by a 

 60° flint-glass prism, were measured successfully. As the sun's energy 

 spectrum is well known, it was possible to eliminate by comparison 

 with it all of the chief instrumental and atmospheric losses. Thus 

 the results appear as stellar energy curves outside our atmosphere, 

 expressed on the normal or wave-length scale. As the deflections 

 observed were fairh/ large, no less than 50 millimeters at maximum 

 in the spectrum of Betelgeuse, for example, the curves are of very 

 fair accuracy over most of their extent. It was possible to improve 

 them in the shorter wave-length region where they were inaccurate 

 by employing visual and photographic results of German observers. 

 Thus the whole of the intense part of the spectrum of the yellow 

 and red stars and a large part of that of the white and blue ones 

 were well delineated. From these results good estimates could be 

 made of the star temperatures on the " black-body " basis. Further- 

 more, estimates of the diameters necessary in "black bodies" to pro- 

 duce at those temperatures the observed amounts of energy were 

 made. It is gratifying to find these results on stellar diameters as 

 accordant as could be expected with those of Pease made by means 

 of Michelson's method of the interferometer. A summary follows: 



Stellar temperatures, radiation, and diameters 



star 



Sun 



P Orionis 



a Lyrae 



a Canis Majoris. 

 a Canis Minoris. 



X Aurigae 



a Tauri... 



^ Pegasi 



a Ononis 



a Herculis 



Absolute 

 tempera- 

 ture C. 



Degrees 

 6,000 

 16, 000 

 14, 000 

 11,000 

 8,000 

 5,800 

 3,000 

 2, 850 

 2,600 



2,500 



Unit= 

 10-11 



3.20 

 6.10 

 6.60 

 1.24 

 2.20 

 2.54 

 1.11 

 7.90 



3.60 



Paral- 

 lax 



0.007 

 .130 

 .370 

 .315 

 .071 

 .053 

 .026 

 .017 

 .007 

 .013 



Diameter 0=1^ 



I 



Radiom- Intcrfer- 



eter orneter 



20 

 2 



1.2 



1.1 



13 



70 



94 



510 



900 



480 



82 

 280 



Russell 



230. 



1 N=ratio of stellar to solar radiation outside earth's atmosphere. 



2 To express In kilometers, multiply by 1.42 X 10 ». To express in miles, multiply by 0.865 X 10«. 



SUMMARY 



The year has been notable for the establishment of daily tele- 

 graphic solar-constant intelligence from Montezuma, Chile, and 

 Harqua Hala, Ariz., through the interest and generosity of Mr. John 

 A. Roebling. Also, due to the same support, experimental tempera- 

 ture forecasts for New York City, based on these daily reports of 



