20 



THE ROYAL SOCIETY OF CANADA 



Table II. — Fourier Co-efficients for Diurnal Inequalities of H at Agin- 

 couRT, 1902-1912. 75th M.T. 



The amplitudes of the different Fourier waves of H do not show 

 the same striking differences with the season as was evident in the 

 D values, in which there were very striking maximum and minimum 

 values. Equinoctial values appear to be the prominent ones in the 

 first three waves and summer values in the fourth, with minimum 

 values in the winter in all waves. 



The phase angles exhibit a much more regular progression with 

 the season. The earliest time of occurrence of maximum in any 

 wave being in midsummer and the latest in midwinter. In the 24 

 hour term the occurrence in June was 73°, or 4 hr. 52 m. earlier than 

 in January. In the 12 hour term the August maximum was 53° 

 or 1 hr. 46 m. earlier than the January maximum. 



In the 8 hour term the August maximum was 57°, or 1 hr. 16 m. 

 earlier than the January maximum; but the progression from season to 

 season is less regular than in the first two terms. In the 6 hour term 

 the progression is still less regular than in the longer period terms 

 but the August maximum was 73°, or 1 hr. 13 m. earlier than the 

 January maximum. 



On account of the limited number of years from which these re- 

 sults have been obtained the seasonal variations are perhaps better 

 shewn by grouping the months into the different seasons, taking for 

 winter the months January, February, November and December, for 

 equinox the months March, April, September and October, and for 

 summer the months May, June, July and August. 



