LXXII THE ROYAL SOCIETY OF CANADA 



determined by absolute observations, taken bi-weekly for Declination 

 and Vertical Force, and bi-monthly for Horizontal Force. 



The westerly declination has changed from 6 22-4' in March 1914 

 to 6 27-2' in March 1915, an increase of 4-8'. The Horizontal Force 

 has decreased from 0-161007 dynes to 0-160387, and the inclination 

 has increased from 74 41 • 7' to 74 43 • 3/ In March 1915 the Vertical 

 Force was 0-586729 dynes. 



Magnetic disturbances were of infrequent occurrence during the 

 early part of the year; but commencing in June there were very few 

 days in which some disturbing forces were not in operation. The 

 greatest variation in declination occurred during the magnetic storm 

 of the 20th and 21st of March, 1915. amounting to 53-4'. In Hori- 

 zontal Force however, the greatest range occurred during the storm 

 of the 27th and 28th of September, 1914, the variation amounting 

 to 0-00340 dynes. 



The mean diurnal range from the hourly ordinates of declination 

 varied from a maximum of 13-2' in August, 1914, to a minimum of 

 5-3' in November, 1914, whilst that of Horizontal Force varied from 

 a maximum of 0-00042 dynes in August 1914 to a minimum of 0-00020 

 dynes in February 1915. The ranges in Vertical Force for January, 

 February and March 1915 have been 0-00007 dynes, 0-00008 dynes 

 and 0-00014 dynes. 



During the year the compass attachments to 191 surveyors' 

 transits were adjusted and compared with the Agincourt Standard 

 Declinometer and the index corrections were determined and sup- 

 plied to the Surveyor General. Assistance was given to Mr. Purser 

 and Mr. Wright of the Department of the Interior in standardizing 

 their magnetic instruments both before and after their field work. 



Assistance was also given to Mr. French of the Dominion Ob- 

 servatory in comparing his instruments with the Agincourt standards, 

 both before and after his field work. 



The computing and compiling of magnetic data from the Ob- 

 servatory records since 1872 are being carried on by Mr. W. E. W. 

 Jackson. 



Respectfully submitted. 



R. F. Stupart, 



Director. 



