438 THE CHEMISTRY OF THE SUN. [CHAP. 



through it will be volatilised before it can reach the photosphere. 

 The best chance that descending particles have then to form 

 spots, is, if they fall from points in lower latitudes. The final 

 period, therefore, of the sun-spot curve must be restricted to a 

 very large extent to latitudes very near the equator, and this is 

 the fact also, as is well known. 



If the reasoning so far be accepted, I should like to add that 

 in my own mind the constant appearance of spots at the 

 beginning of a cycle in lat. 35-30, and the reduction in 

 the spotted area when latitude 10 is reached, indicate that in 

 those regions there is some sudden change in the physics and 

 construction of the atmosphere. In (9) we saw why, if my 

 hypothesis be true, there should be fewer spots at the poles 

 and equator, assuming only an increasing height of atmosphere 

 at the equator, but the hypothesis says nothing as to why 

 latitudes 35-30 are chosen. Now are there any facts to help us 

 here ? 1 think there are, but here again we are in a region 

 of great uncertainty ; we have not enough information. 



If we study the records secured during eclipses observed when 

 the sun is least disturbed, there is evidence to show that the 

 condensing and condensed materials brought towards the equator 

 by the outward polar current, probably extend as solar meteoric 

 masses far beyond the limits of the true atmosphere, and form 

 a ring, the section of which widens towards the sun, and 

 the base of which lies well within the boundary of the 

 atmosphere. 



There is further evidence indicating that the equatorial 

 extension shown on the photographs may only after all have 

 been a part of a much more extended phenomenon, one going 

 to an almost incredible distance considering it as a solar 

 appendage from the sun itself. 



During the eclipse of 1878, one observer took extreme 

 precautions to guard his eyes from being fatigued by the light 

 of the inner corona, which sometimes is so bright that observers 



