268 
REPORT OF THE ANNUAL MEETING 
believe that the committee will agree that Dr. Frank M. Chapman, of the American Museum 
•of Natural History, in view of his memoir, "The Distribution of Bird-life in Colombia, a con- 
tribution to a biological survey of South America," Bulletin of the American Museum of Nat- 
ural History, Volume XXXVI, 1917, pages 7-10 (Roman), 1-729 (Arabic), is entitled to first 
consideration and premiership for the year 1917, as having produced the most earnest single 
work in zoology, the result of six years serious exploration and research, namely, from Decem- 
ber, 1910, until the publication of the volume in December, 1917. 
As chairman of the committee, I respectfully submit this as a substitute report, with the 
approval of my colleagues. 
Fortunately, Doctor Chapman is one of the most distinguished of the many followers of 
Dr. Joel Asaph Allen, and he was also closely associated with Dr. Daniel Giraud Elliot; 
consequently I trust the Committee will regard the award of the medal as eminently 
appropriate. 
Respectfully submitted, 
Henry Fairfield Osborn, Chairman. 
Mount Hamilton, January 19, 1918. 
-Dear Dr. Day: 
I have just sent you'the following night letter: 
"I herewith certify nomination of Walter S. Adams, Mount Wilson Observatory, 
for his investigations in astrophysics, by Draper Committee for award of Draper 
Gold Medal. I hope Council can make award practicable at this year's meeting." 
Dr. Walter Sidney Adams has discovered and developed a method of determining the 
distances of the stars, by means of the spectrograph, which the Henry Draper Committee 
believes is one of the great advances in modern Astronomy. Like most methods of high 
value, its fundamentals are exceedingly simple. The basic fact is that certain lines are en- 
hanced in the spectra of stars of high absolute luminosity, and certain other lines are en- 
hanced in the spectra of stars of low absolute luminosity; in other words, the intensities of 
certain lines increase continuously with increasing absolute luminosities, and the intensities 
of certain other linds increase continuously with decreasing absolute luminosities. The ap- 
proximate distances of a few hundred of the nearer stars, measured by the older methods, 
are known. These distances enable us to compute the absolute magnitudes or luminosities 
of those stars. The correlation of these absolute magnitudes and the estimated relative in- 
tensities of the critical lines in their spectra have given Mr. Adams the power to determine 
the functional relations connecting these elements, and thus to determine the absolute mag- 
nitudes of stars not yet observed for distance. Knowing the magnitude of a star as ob- 
served from the earth, and the absolute magnitude of the same star as determined by the 
spectrograph, the solution of a simple equation yields at once the value of the star's distance. 
Here is a powerful means of extending the list of stars whose distances are known, and the 
Committee confidently expects that the method will be applied successfully to thousands of 
stars which are too distant for successful attack by the earlier methods. The method should 
in due time tell us much concerning the linear scale of the nearer parts of our stellar system. 
The secondary applications of the method to astronomical problems are likewise of great 
promise. 
Mr. Adams has applied the spectrographic method to the determination of the distances 
of more than five hundred stars, of the Harvard spectral classes F to Mb inclusive, and a com- 
parison of his results with those obtained by the older methods, as to rapidity and accuracy, 
is a subject for congratulation. 
The method has not yet been applied satisfactorily to stars of certain spectral classes, but 
it is hoped that the dependence of such spectra upon absolute luminosities or other elements 
may be found in the near future. 
Dr. Adams's contributions to other lines of astronomical research have been many,, exten- 
sive and fruitful. We mention three: 
