14 Turner, Total Solar Eclipses. 



of the distance. Combining, then, for comparison with 

 this observed density the two former contributing causes — 

 greater surface, which goes as the square, and greater 

 velocity, which is as the square-root at most* — we get only 

 23^ instead of 4^ : and our su imposition does not fit the 

 observed facts. Hence, if particles travelling outwards 

 (under repulsive force) exist in the corona, they can only 

 dilute the effect we wish to explain, and we must look 

 for other particles moving in such a way that the index 

 is even greater than 4^, so that it may be reduced to 4j^ 

 on the average : just as when, in climbing a hill of which 

 the average slope is known, if we find an easy gradient 

 for some distance, we know that we shall ultimately find 

 an unusually steep part somewhere. 



Next let us take another supposition of an inverse 

 kind. Matter cannot be travelling continuously outwards. 

 Can it be, perhaps, travelling continually inwards from 

 space? This supposition is worse than the former ; the 

 condensation as we approach the sun being not even so 

 great as before. We still have the "concentration" due 

 to the decrease in surface of concentric spheres, but when 

 we come to the velocity with which a particle crosses any 

 sphere, it is now greater near the sun instead of less, as 

 before. Accordingly our power of the distance is no 

 longer even so large as 2\, but on the supposition of 

 simple falling, it would be only 1^. There is, however, 

 one new consideration which may be taken into account. 

 Is there anything resisting the falling ? We know, for 

 instance, that there is in the Corona a gaseous portion 

 made up of hydrogen, coronium, and perhaps other gases. 

 Do these check the action of the falling particles? When 

 the great eruption of Krakatoa took place twenty years 

 ago, a large amount of dust was flung sky high by the 



* See Note I. 



