THE DOMINION ASTRONOMICAL OBSERVATORY AND THE 

 BOUNDARY AND GEODETIC SURVEYS. 



The work of the Observatory has followed the same general lines 

 as in previous years. 



Astrophysical Division. — In the Astrophysieal Division the work 

 on spectroscopic binaries has been actively continued. During the 

 year 525 spectrograms have been made, three orbits, of ^ Persei, d Tauri 

 and ^ Coronae Borealis, have been determined , and further observations 

 of d Aquilae, resulting in a good determination of the ratio of the masses 

 of the two components, have been made. Observations of Nova 

 Geminorum and other miscellaneous work have also been carried on. 

 In 6 Persei the orbit has been obtained from the sharp h and k lines 

 only, whose velocity differs from that of the other and difïuse lines of the 

 spectrum. In d Tauri a double spectrum shows an unusually large 

 ratio of the masses about two to one. /? Coronae has only a small range 

 and gives indications that it is a triple system. The decrease in the 

 number of spectrograms made and orbits determined has been in part 

 due to exceptionally bad observing weather but also to the fact that 

 the stars now under observation are fainter and have orbits less easy 

 of determination than previously. It is a great satisfaction to record 

 that the Government has recognized the value of the work done and the 

 need of a larger telescope for carrying it on effectively and extending 

 its scope by authorizing the construction of a large reflector. In this 

 decision it was undoubtedly largely influenced ])y the Memorial pie- 

 sented by The Roj'al Society last year. 



The grating spectrograph mentioned last year was completed and 

 tested and, although not giving as intense a spectrum as was hoped, 

 will undoulitedly be of value when uniform intensity in a spectrum is 

 required and in the violet and ultra violet where it is much superior 

 to prisms. At the same time a Littrow half prism was tested , also giving 

 very promising results. A further fact obtained from the investigation 

 was the great absorption of the prisms in the violet, and a light flint 

 pi'ism, which it is expected will be of great advantage, will be used shortly. 



The work on the Solar Rotation has also been actively pushed. 

 Two additional series of plates were obtained last summer, and, although 

 the lai'ge amount of measurement required is not quite completed, they 

 tend to confirm the results obtained fi'om the 1911 plates. The value 

 of the rotation and of the law of variation with the latitude is practically 

 the same and no systematic difference of velocity for different lines 

 appears to be present. 



Proc. 1913. .7 



