APPENDIX B LXXIX 



Radiation. The Callendar Sunshine Receiver has been in oper- 

 ation throughout the year and observations were taken with the 

 Angstrom Pyrheliometer whenever the sky was sufficiently clear. 

 A new form of Sunshine Receiver for the Callendar instrument has 

 been constructed and is now being tested. 



Evaporation. Observations on evaporation were made through- 

 out the year, during the summer by measuring the change in the 

 water level from day to day, and in winter by weighing a pan of ice 

 or water. The excessive cost of material and the scarcity of labour 

 made it advisable to postpone the construction of new evaporation 

 stations. 



Terrestrial Magnetism 



During the Year ending March 31st, 1917, the photographic 

 instruments which record the changes in Magnetic Force, at Agin- 

 court near Toronto, were maintained in operation without any 

 material loss. The preliminary results obtained from a first re- 

 duction of these records are published in the Journal of the Royal 

 Astronomical Society of Canada. Beginning with the year 1914, 

 the final reduction and analysis of the results of Magnetic Obser- 

 vations are published under separate cover, instead of being in- 

 cluded in the Annual Meteorological Report as an appendix. The 

 1914 results appeared in 1916, and the 1915 results are now in the 

 hands of the printer. It is expected that these results will be eivail- 

 able for the Magnetic Investigator much sooner than formerly. 



Progress is being made on the computation and compilation 

 of the results of observations for the years 1872 to 1902 inclusive, 

 and these will be published shortly. 



From March 1916 to March 1917 the mean Declination for the 

 month increased from 6°33'-l West to 6° 35' -6 West, the mean 

 Horizontal Force decreased from 0-15989 dyne to 0-15960 dyne, the 

 Mean Vertical Force decreased from 0-58572 dyne to 0-58485 dyne 

 The mean total Force decreased from 0-60715 dyne to 0-60623 dyne, 

 and the mean Inclination increased from 74° 43' -9 to 74° 44' -2. 



Magnetic disturbances were of frequent occurrence during the 

 year, but they were generally of moderate intensity. During the 

 night of August 26th, the largest Magnetic Storm since 1909 was 

 recorded. The Declination ranged from 5° 5' -7 West to 8° 24' -2 

 •West, Horizontal Force from 0-15439 dyne to 0-16328 dyne and 

 Vertical Force from 0-58085 dyne to 0-58749 dyne. The stoim 

 began very suddenly at 14h 43m 75th Meridian Time and was prac- 

 tically instantaneous over the Globe. A paper on this storm by 



