406 IF. A. Xorton — Physical Constitution of the Sun. 



heights imply either a greater initial velocity than 120 rnile,^ 

 per second, or that the full energy of the solar attraction doe? 

 not take effect on the eruptive masses of hydrogen, in tlie re- 

 above the photosphere. From our theoretical point ot 

 we perceive that the latter supposition should be true : 

 ...-„„ the solar repulsion should be in operation above the 

 hydrogen envelope, or the chromosphere, diminishing the 

 gravitating tendency. . . 



The metallic vapors set free in the region of dissociation, 

 should rise to heights varying with their atomic weights 

 Some of them, especially the lighter ones (sodium, magne- 

 sium, calcium, kc), may acquire velocities suflacient to linri.^ 

 them above the chromosphere. In fact the spectrosco] 

 detected besides hydrogen, magnesium, sodium, iron, an m 

 mium, in the solar protuberances. Lockyer states that 

 invariably found that in solar storms, the chromospheru- 

 are thrown up in the order of vapor density. He regaiv- 

 chromosphere as built up of the following layers, which are m 

 the order of vapor density in the case of known elements: a 

 new element giving the green coronal line in the spectroscope, 

 hydrogen, another new element, magnesium, sodium, banm 

 iron. He remarks that " all the heavier vapors are at or mm 

 the level of the photosphere itself"* ,, 



The green coronal line was traced in the late eclipse by rio i^ 

 Young and Winlock as far as 16' or 425,000 miles from tue 

 sun's limb. From our present theoretical stand-point, we na^^ 

 rally infer, as Lockyer has already done from his observatio ^ 

 that the element present in the solar corona which gives tms i ' 

 is much lighter than hydrogen. We see also that an elemei ^ 

 several times hghter than hydrogen might be subject to a st . 

 repulsion that would predominate over the atti-action ot gra 

 tation at all distances, and urge the subtil vapor i^cl^linw 

 away from the sun. Since the same line is seen m the bgw 

 terrestrial auroras, we must conclude that the same substance 

 present in our upper atmosphere ;-either in a permanent upp^ 

 layer, or derived^ from the sun (as I have elsewhere mamte 

 ed). We must infer also that it is magnetic, which apparem.^ 

 cannot be the case unless it takes on the condition ot coiup , 

 molecules. Such compound molecules might become disp^_ ^^ 

 in the upper atmosphere of the earth, or in t^e P^^^^l^eat : 

 the sunf by electric discharges or sudden evolutions otn^^ 

 and then the separate atoms repelled off, ^^.^^^^^^'^1110 

 ers of the corona and aurora, illuminated either by 



* It is admitted by Ajigstrom, and Zollner, that the absence of ?g^5the^e 

 dications of oxygen and nitrogen in the sun, is no sufficient evi 

 gases are really wanting in the sun's atmosphere. 



