396 Prof. Schuster : Possible Lffects of Solar Magnetization 



during the synodic revolution, the position of the earth's axis 

 relative to the radius-vector drawn from the sun to the earth 

 is altered. The true periods are those produced by a combi- 

 nation of the annual and synodic periods. 



Lord Kelvin has already discussed the effect produced 

 by a sun magnetized in a direction parallel to his axis of 

 rotation ; and I may therefore, in the first instance, confine 

 myself to the discussion of effects due to a uniform transverse 

 magnetization, neglecting the inclination of the solar equator 

 to the ecliptic. The more general problem will be treated 

 afterwards. 



In no-. 1 let OT be the direction of the radius- vector drawn 



from the sun to the earth, and E the normal to the ecliptic. 

 If the sun rotates in space, the component of magnetic force 

 resolved along T will depend on the angle between that 

 direction and the axis of the sun's magnetization. If n be 

 the mean angular velocity of the earth round the snn and k 

 that of the sun round his axis, the required angle will, 

 neglecting the ellipticity of thp earth's path, increase as (tc — n)t. 

 The component F : of magnetic force resolved along T will 

 therefore be given by 



Fi = 2 cos ({K-n)t- 8) /r*, 



w r here r is the radius-vector and /3/(fc — n) represents the time 

 when the north- repelling pole of the sun crosses the radius- 

 vector. The component along N drawn at right angles to 

 OTis 



F 2 =sin((*-n)*-/3)/r 3 . 



As the earth moves in space its axis P will move relative 

 to T, in such a way that P will describe a circle clockwise 

 round E. The problem consists in finding the components 

 of the vectors F x and F 2 at right angles to and in the plane of 

 the equator. If P is the pole at any time, the magnetic force 



