REPORT OF COMMITTEE ON OBSERVATORIES 39 



the fact that, while there is permanently located in the southern 

 hemisphere only one telescope which is used for this purpose, and 

 provision made for the use of another during three years, there are 

 employed in this service in the northern hemisphere at least six 

 large telescopes, each more powerful than any telescope installed at 

 a permanent observatory in the southern hemisphere. The disparity 

 in resources here presented is marked, and the call for a remedy 

 seems to be imperative. 



It would therefore seem to be very desirable that the Carnegie 

 Institution should enter this field and provide for use in the south- 

 ern hemisphere the most powerful reflecting telescope that would 

 be sanctioned by experience and the dictates of common prudence. 

 The use of this in the measurement of radial velocities of southern 

 stars should be provided for during six years at least. There would 

 be needed a staff of two skilled observers and a half dozen meas- 

 urers and computers. 



The additional argument in favor of the provision of a large re- 

 flector to be used in the southern hemisphere will be found later, 

 under (7), in this enumeration of proposed works. 



The observations specified under the four preceding heads are 

 closely related to each other, and logically they are branches of a 

 single enterprise — an endeavor to make a strong forward movement 

 in the solution of the sidereal problem. We consider it extremely 

 desirable that provision for all the works enumerated by us should 

 be made in the proposed Southern Observatory, but in the event of 

 necessary curtailment which does not extend to the entire program, 

 it is to be hoped that such curtailment may not apply to either of 

 the four projects thus far mentioned. 



(5) Observations of Double Stars. — A Large Refractor. 



The measurement of double stars has been in active progress for 

 more than a century. For the past seventy years work in this line 

 has absorbed a very large proportion of the energies devoted to 

 astronomical investigation. Certainly the class of facts developed 

 by these investigations have remarkable interest, and they have 

 exerted a deep influence upon the thoughts of man as to his place 

 in nature. That the law of gravitation apparently extends through- 

 out the universe ; that suns revolve about suns ; that the orbits are 

 usually elliptical, like those of the periodic comets ; that many of 

 these bodies are larger and more splendid than our sun — these and 



