PROCEEDINGS FOR 1913 XXIX 



the scientific world. We would beg to be allowed, however, to direct 

 your attention especially to the Astrophysical Division, which, with 

 the smallest telescope employed regularly in this work, has obtained 

 surprising and valuable results in the measurement of the velocities of 

 stars in the line of sight, and in the determination of the orbits of binary 

 systems. 



The standing already obtained abroad by our National Observatory 

 has been very distinctly shown by the appointment of a member of its 

 staff, Mr. Plaskett, on three important international committees in 

 company with the most distinguished astronomers in the world. These 

 committees are, a Committee on the Classification of Stellar Spectra, a 

 Committee on the Spectroscopic Determination of the Solar Rotation 

 and a Committee on Co-operation in the Measurement of Stellar Radial 

 Velocities. The last mentioned, composed of Directors of the leading 

 observatories in England, Germany and America, has under considera- 

 tion a plan for co-operation in obtaining the radial velocities of all stars 

 brighter than the sixth magnitude. On this work, which is probably 

 the most important and most urgent in modern astronomical research, 

 will finally depend our knowledge of the structure, constitution and 

 motions of the Universe. Unfortunately, however, only two observa- 

 tories, and these only to a limited extent are able to undertake this 

 work which is of sufficient magnitude to require many years' observa- 

 tions at several institutions. 



In order that this research may be successfully undertaken a large 

 telescope, one of four or five times the aperture of the small one at pres- 

 ent in use, will be needed. A reflecting telescope possesses many ad- 

 vantages for investigating radial velocities and has the further impor- 

 tant advantage of costing less than a quarter the amount required for a 

 refractor of the same aperture. For a comparatively moderate outlay 

 therefore, a reflecting telescope can be constructed and installed com- 

 plete. Canada would then have the largest telescope in existence and 

 would be able to take probably the greatest share in the important work 

 already referred to. There need be no fear of results when the record 

 already achieved by the present staff with their very modest equipment 

 is considered and the addition of one or two observers would enable them 

 to keep the new instrument in active and efficient operation. 



The Royal Society of Canada, after careful consideration of the 

 matter, would respectfully beg leave to recommend the installation of a 

 large reflecting telescope for carrying on this important and timely 

 work at the Dominion Observatory or at some branch thereof to be 

 established should climatic and other conditions warrant. The pos- 

 session of such an instrument would enable our country to take a prom- 

 inent part in this co-operation between the observatories of which 



