Section III., 1915 



[17] 



Trans. R.S.C. 



On the Diurnal Changes in the Magnetic Horizontal Force at Agincourt, 



1902-1912. 



By W. E. W. Jackson, M.A., 



Presented by R. F. Stupart, F. R.S.C. 

 (Read May Meeting, 1915). 



In a paper presented to The Royal Society of Canada at its last 

 meeting, some results of an harmonic analysis of the diurnal inequality 

 of the Magnetic Declination for the years 1902-1912 inclusive were 

 given. In the present paper the results of a similar analysis of the 

 Agincourt Horizontal Force data is given. The mean diurnal in- 

 equality of H for each month of the year for the eleven years 1902-1912 

 including all days was obtained similarly to that for D. The value 

 for any particular hour is the arithmetic mean of the values of the di- 

 urnal inequality for that hour for the eleven years. The results are 

 tabulated in Table I. Distinct maxima and minima are in heavy 

 type and the ranges and average departure from the mean are given 

 below. The values are expressed in millionths of a dyne or 7/IO. 



Table I. 



Diurnal Inequality of Horizontal Magnetic Force at Agincourt. 

 All Days 1902-1912. 



Jan. 



Mar. April. 



May 



June. July 



Aug. Sept. Oct. Nov. Dec 



Hour 



9... . 

 10. . . . 



11 



Noon. 



13 



14. .. . 

 IS... . 

 16.... 

 17... . 



18 



19 



20.... 

 21... . 



22 



23 



24 



T/10 



17 

 19 

 24 

 34 

 49 

 66 

 67 

 55 

 21 



- 57 

 -151 

 -183 

 -137 



- 76 



- 15 

 34 

 52 

 48 

 39 

 32 

 20 

 17 



6 

 19 



T/10 



17 

 20 

 25 

 29 

 36 

 66 

 65 

 50 

 3 



- 74 

 -144 

 -165 

 -145 



- 75 



- 14 

 36 

 56 

 53 

 49 

 42 

 21 

 17 

 15 

 20 



T/10 



16 

 31 

 36 

 53 

 56 

 71 

 60 

 16 



- 72 

 -152 

 -215 

 -203 

 -135 



- 52 

 29 

 82 

 98 

 90 

 57 

 48 

 39 

 23 

 10 

 12 



T/10 



12 



7 



19 

 30 

 44 

 48 

 26 



- 24 

 -118 

 -207 

 -229 

 -181 



- 93 



2 



79 



119 



120 



104 



62 



51 



39 



40 



32 



19 



T/10 



4 



- 2 



- 5 

 1 



11 



27 



1 



- 62 

 -146 

 -220 

 -199 

 -111 



- 22 

 78 



134 

 159 

 139 

 101 

 61 

 35 

 16 

 14 



- 4 

 2 



T/10 





 4 

 2 



- 4 

 9 



19 

 2 



- 59 

 -140 

 -199 

 -195 

 -122 



- 28 

 74 



135 

 149 

 130 

 99 

 56 

 42 

 21 

 6 



- 6 



- 3 



T/10 



1 



2 



11 



28 



6 



- 55 

 -139 

 -214 

 -215 

 -137 



- 31 

 64 



126 



153 



136 



99 



64 



44 



23 



17 



4 



3 



T/10 



35 

 13 

 29 

 14 

 13 

 34 



- 14 



- 82 

 -199 

 -282 

 -260 

 -165 



- 38 

 65 



137 

 156 

 143 

 109 

 66 

 57 

 48 

 55 

 45 

 23 



T/10 



33 

 46 

 40 

 44 

 42 

 53 



- 2 

 -101 

 -195 

 -261 

 -271 

 -177 



- 53 

 45 



110 

 153 

 126 

 99 

 78 

 61 

 55 

 51 

 31 

 22 



T/10 



22 

 22 

 38 

 50 

 68 

 84 

 53 



- 23 

 -119 

 -200 

 -228 

 -191 

 -102 



- 12 

 32 

 71 

 74 

 78 

 67 

 67 

 52 

 52 

 26 

 24 



T/10 



22 

 23 

 24 

 38 

 52 

 81 

 61 



- 4 



- 86 

 -169 

 -196 

 -179 

 -106 



- 29 

 30 

 68 

 65 

 66 

 58 

 50 

 39 

 32 

 27 

 32 



T/10 



19 

 35 

 47 

 62 

 63 

 37 



- 18 



- 88 

 -152 

 -162 

 -107 



- 39 

 13 

 51 

 52 

 55 

 37 

 25 

 17 

 20 

 11 



Range 249; 231 



379 



348 



368 



424 



277 



225 



Average departure from 

 mean 



Sec. III. 1915—2 



