xxviii.] INDICATIONS OF ACTIVITY. 427 



rule of action with a cause behind it. M. Faye's theory of the 

 sun's rotation is that it results from vertical convection-currents 

 always ploughing its mass, bringing up with them from below 

 the smaller linear velocity of the interior, and carrying down the 

 swifter rate of travel belonging to a wider circumference. An 

 interior solar nucleus with accelerated rotation is thus formed, 

 and owing to its considerable polar compression, the currents 

 starting from its surface rise from a greater depth, and hence 

 carry up to the photosphere a slower rate of rotation, the farther 

 they are from the equator. Moreover, the slackening of angular 

 movement thus brought about will vary (as stated in the formula, 

 and confirmed by observation) proportionally to the square of the 

 line of the latitude. 1 It has, however, been shown that in order 

 to produce the requisite amount of flattening in the interior 

 nucleus, its axial revolution should be accomplished in a period 

 of between two and three days, 2 a supposition altogether in- 

 admissible ; and indeed all attempts to account for the sun's 

 rotational pecularities by action from beneath the photosphere 

 encounter insuperable obstacles. 



9. By the hypothesis, the spots should have the greatest indications 

 of activity, and display the greatest amount of energy on their 

 following or western side. 



As the fall from a region of greater radius gives rise as we 

 have seen to a forward movement in the direction of the sun's 

 rotation, so the up-rise of the dissociated gases (produced by the 

 masses which have pierced the photosphere and have exploded 

 or have become dissociated below it), from below the photo- 

 sphere from a region of smaller radius will produce a 

 movement in the opposite direction, they should curve to the 

 westward. 



1 Comptes Rendus, t. Ix. p. 147 ; t. c. p. 595. 

 3 Belopolsky, Astr. Nack., No. 2722, 



