LXXX THE ROYAL SOCIETY OF CANADA 



Mr. Jackson appeared in the January 1917 number of the Journal 

 of the Royal Astronomical Society. 



The mean diurnal range obtained from the hourly measures 

 varied in Declination from a maximum of 14' -8 in August 1916, to 

 a minimum of 5' -9 in December 1916, in Horizontal Force from a 

 maximum of 61 gammas in August 1916 to a minimum of 29 gammas 

 in December 1916, and in Vertical Force from a maximum of 30 

 gammas in September 1916, to a minimum of 8 gammas in 

 February 1917. 



During the year the index corrections for 100 magnets attached 

 to surveyors transits were determined and supplied to the Surveyor 

 General, and assistance was given to four surveyors from this De- 

 partment in standardizing their Total Force instruments both be- 

 fore and after their season's field work. 



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

 servatory in comparing his field instruments with the Agincourt 

 Standards both before and after his field work. 



A magnetic observatory for the recording of changes in Decli- 

 nation was established at Meanook, Alberta, in July by Mr. Jackson 

 and instructions were given to Mr. H. E. Cook who was appointed 

 as observer. 



The observing Pier was determined to be in Latitude 54° 36' -9 

 North and Longitude 113° 20' -5 West. 



The first photographic trace was obtained on July 12th and 

 13th, and since then the instrument has been kept in operation with very 

 little loss of trace. Some difficulty was experienced in keeping the 

 clocks in operation during the extreme cold weather, but a small 

 heater will be provided before the coming winter which it is hoped 

 will overcome this trouble. The instrument base is of wood and 

 warping has caused some creeping of the base line value, and it is pro- 

 posed to replace this base in the near future by one of slate. 



The mean monthly value of the Declination has changed from 

 27°48'-6 East in August 1916, to 27°46'-3 in March 1917. 



The accompanying table gives the mean daily range as obtained 

 from the hourly measures and from the means of the extremes and 

 also the absolute range during each month. 



