Prof. W. A. Norton on the Physical Constitution of the Sun. 03 



above the solid or liquid body of the sun, and from the surface- 

 molecules of this central mass, except in so far as these im- 

 pulses may be intercepted in their passage; and that it is op- 

 posed to the force of gravitation, which is due to a virtual 

 attraction of the sun's entire mass, so that the effective force 

 soliciting any gaseous molecule is the difference between these 

 two forces (attractive and repulsive) by which it is urged. 



2. That the force of solar repulsion, since it consists of im- 

 pulses propagated in sethereal waves, is comparatively more 

 effective in proportion as the atomic weight of the solar vapour 

 is less, it being assumed that the quantity of matter in any 

 atom is proportional to its volume. 



3. That in a hypothetical condition of equilibrium of the 

 sun's atmosphere the elastic force of each of its vaporous consti- 

 tuents at any depth will consist in the intensity of the effec- 

 tive heat-impulses tending to urge its molecules outward, which 

 will be counteracted by the weight of the superincumbent por- 

 tion of the atmosphere. Now let us assume, for the moment, 

 that at some anterior epoch in the sun's history all the present 

 vaporous constituents of the sun's atmosphere were diffused 

 throughout a space exterior to the central body of the sun, and 

 limited by the spherical surface (A) at which the molecules of 

 the vapour of greatest atomic weight are in equilibrium under 

 the action of their own weight and of the heat-repulsion urging 

 them upward. This hypothetical state of things could not con- 

 tinue, since the atoms of each of the other solar vapours would 

 be urged upward by an effective force. If we conceive a small 

 quantity of each of them to escape from all points of this sur- 

 face, the rising vapours will ascend to greater heights in propor- 

 tion as their atomic weights are less, and finally, when the 

 equilibrium is attained, form a series of spherical envelopes 

 wholly detached from each other, and arranged in the order of 

 atomic weights — beginning with the heavier metallic vapours and 

 terminating with the lighter (potassium, sodium, &c.) and the 

 permanent gases, with hydrogen outermost. If other small 

 portions of each of the vapours were to rise from the surface A, 

 they would serve to augment the thickness of the envelopes 

 already formed; and the same would be true for each succes- 

 sive discharge. The final result would be the same if the dis- 

 charge were continuous during a certain interval of time, as 

 would naturally happen. After a certain amount of the solar 

 vapours have escaped, contiguous envelopes might interpenetrate 

 each other more or less. What it is especially important to 

 observe is, that throughout the whole depth intercepted between 

 each envelope and the outer limiting surface A of the vapour of, 

 greatest atomic weighty every atom of the substance of which the 



