1904.] Yearly Variation of Magnetic Storms and Aurorce. 



91 



It should be expected, then, that if the polar regions of the sun have 

 any action, as above suggested, the effects of the action on the earth 

 should vary according to the positions of the solar poles relative to the 

 earth. 



The actual inclination of the sun's axis being 82 45', and the 

 longitude of the ascending node being 74 25', or the tilt of the axis 

 being in the direction of about 19 hours in right ascension, it follows 

 that, in each year, the south pole of the sun is most turned towards 

 the earth in the beginning of March (about the 6th), and the north 

 pole most towards the earth in the beginning of September (about the 

 5th). At the two intermediate epochs, in June (about 5th) and 

 December (about 6th), neither pole is turned towards or away from 

 the earth, but occupies an intermediate position. Hence we see that 

 the equinoxes occur in the same months as those in which one or other 

 of the solar poles is turned towards the earth, while the neutral 

 positions of the solar poles in relation to the earth occur in the same 

 months as the solstices. 



The accompanying diagram shows graphically the relation between 



JAN I FEB I MAR I APR I MAY I JUN I JUL 



6'- 



-20- 



a'- 



FIG-. 1. Curves showing the relation between the change of declination of the 

 Sun (broken curve) and the positions of the Sun's north and south poles with 

 regard to the earth (continuous curve) throughout a year. 



the two curves representing the variation of the sun's declination and 

 the change of the latitude of the sun's [centre or the variation of the 

 amount of the tilt of the solar poles, in relation to the earth throughout 

 a year. 



It will be seen that the curve representing the tilt of the solar axis 



