APPENDIX E CXIX 



the original corrector wer-^' investigated. This paper was published in 

 the Astrophysical Journal for March, 1908. 



2 " The Orbits o.f Stellar Systems, "' by W. E. Harper, gave an ac- 

 count of some of the work done at the Observatory in obtaining the 

 orbits of spectroscopic binaries. A short account of the different methods 

 employed in treating the velocity ol^servations to obtain the elements of 

 the orbit was folloAved as an example by the velocity curve and orbit of 



a Draconis. 



3. " The Geometry of Orbits, " by W. F. King. An entirely new and 

 wholly graphical method of obtaining the elements of a spectroscopic 

 binary orbit was developed. Besides being entirely original, this method, 

 especially for stars whose spectrum does not permit of very accurate 

 measurement, effects a considerable saving of labour. This paper was 

 published in the Astrophysical Journal for March, 1908. 



4. "Methods of Predicting Occultations,'' by E. M. Motherwell. The 

 principal methods employed for predicting occultations of stars by the 

 moon at any given place, with special application to the Observatory at 

 Ottawa, were treated. Graphical methods were fully discussed and ex- 

 plained on account of the labour saved. 



5. " Earthquakes and the Interior of the Earth, " by Otto Klotz, 

 gave a concise summary of the state of our knowledge concerning the 

 interior of the earth. The application of various indirect methods, 

 especially the new one of seismology, led to the conclusion that the in- 

 terior of the earth was not a fluid molten mass as originally pi;pposed, but 

 must be solid and rigid as steel. Published in the Journal of the Eoyal 

 Astronomical Society of Canada, March — April, 1908. 



6. "The Determination of Azimuth," by F. A. McDiarmid. The 

 principles employed and the formuhe used in obtaining accurate deter- 

 minations of Azimuth were developed. The errors to be guarded against 

 and the precautions to be used Avere fully discussed, and examples from 

 the Azimuth work in the Yukon showing the accuracy attainable v/ere 

 given. 



7. "Errors of Transit Observations, "' by K. M. Stewart. This paper 

 was a conclusion of the one given last year and gave the results of a 

 valuable investigation into improved methods of obsen'ation and of 

 arrangement of the stars in a time set in the determination of time and 

 longitude with a portable transit instrument. This paper will shortly be 

 published. 



' 8. "The Spectrograph for Eadial Telocity Work, " by J. S. Plaskett, 

 although not given at the time of writing, will contain a summary of the 

 principles involved in designing tjie most efficient type of spectrograph. 



