XXVIIL] AN EQUATORIAL EXTENSION. 



spot minimum. We have a tremendous equatorial extension ; 

 that is the great feature, and it is proved by photographs, 

 and this extension may mean that there is a ring round the 

 sun's equator. 



A similar extension was observed in the previous minimum, 

 in 1867, and the polar phenomena were observed to be identical 

 in both eclipses. At the poles there is an exquisite tracery 

 curved in opposite directions, consisting of plumes or panaches, 

 which bend gently and symmetrically from the axis, getting 

 more and more inclined to it, so that those in latitudes 80 

 to 70 start nearly at right angles to the axis, and their 

 upper portions droop gracefully, and curve over into lower 

 latitudes. 



Although indications of the existence of this ring have not 

 been recorded during eclipses which have happened at the 

 period of maximum, there was distinct evidence both in the 

 eclipses in 1871 and 1875 of the existence of what I regard as 

 the indications of outward upper polar currents observed at 

 minimum. 



If we assume such a ring under absolutely stable conditions, 

 there will be no disturbance, no fall of material, therefore there 

 will be no spots, and therefore again there will be no promin- 

 ences. Such was the state of things on the southern surface of 

 the ring from December 1877, to April 1879, during which 

 period there was not a single spot observed, the umbra of which 

 was over 15-millionths of the sun's visible hemisphere. 



Assume a disturbance. This, as in the case of the atmosphere 

 without any ring discussed in (2) page 406, may arise from 

 collisions, and these collisions would be most likely to happen 

 among the particles where the surface of the ring is being 

 bombarded by the condensed materials brought by the currents 

 from the poles. These particles will fall, thereby disturbing 

 and arresting the motion of other particles nearer the photo- 

 sphere ; and finally they will descend with a crash on to the 



