PROCEEDINGS 
OF THE 
NATIONAL ACADEMY OF SCIENCES 
Volume 5 OCTOBER 15. 1919 Number 10 
SOME PROBLEMS OF SIDEREAL ASTRONOMY'' 
By Henry Norris Russell 
Bulletin of the National Research Council, Number 2 
Communicated to the National Academy of Sciences, June 17, 1917 
The main object of astronomy, as of all science, is not the collection of 
facts, but the development, on the basis of collected facts, of satisfactory 
theories regarding the nature, mutual relations, and probable history 
and evolution of the objects of study. Before the existing data appear 
sufficient to justify the attempt to form such a general theory, two 
policies of investigation may be followed: (1) to collect masses of in- 
formation, as accurate and extensive as possible, by well tested routine 
methods, and leave it to the insight of some fortunate and future investi- 
gator to derive from the accumulated facts the information which they 
contain regarding the general problems of the science; (2) to keep these 
greater problems continually in mind, and to plan the program of ob- 
servation in such a way as to secure as soon as practicable data which 
bear directly upon definite phases of these problems. 
Much valuable and self-sacrificing work has been done by astrono- 
mers, who adopted the former policy. In the opinion of many inves- 
tigators, however, the progress of astronomy would be hastened if fuller 
consideration were given to the second method of attack, especially 
with a view to the widest possible cooperation between different ob- 
servers and institutions. 
In the hope that the committees of the National Research Council 
may be of service in furthering such cooperation, and at the request of 
the Chairman of the Council, the following survey has been attempted 
of the general problems of sidereal astronomy, and of investigations 
which at present promise advances toward their solution. 
* This is issued as the first of a series of research surveys prepared under the auspices of 
the National Research Council. 
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