16 Chacomac's Solar Theories. 



sphere. At that time lie observed, and has since been con- 

 firmed in the opinion, that at certain points the photosphere 

 seems to melt, and become like ice on the surface of a lake, 

 which, under the influence of a considerable weight, slides 

 obliquely into the liquid. In this way enormous photospheric 

 fragments are engulphed while preserving their form, but 

 losing their brightness as they sink. On the 3rd of December, 

 1858, he observed a luminous avalanche, larger than our earth, 

 engulphed in this manuer. During the interval between these 

 meltings (effondrements) of the photosphere, he has observed 

 a contrary action, like a condensation of the exterior atmo- 

 sphere into luminous masses. This appearance he considers 

 analogous to the formation of the " crystalline clouds," which 

 we name cirrus. 



As a provisional conclusion, M. Chacornac regards the sun 

 as ff a liquid incandescent mass, surrounded by a thick at- 

 mosphere, imperfectly transparent ; and whose ultimate limits 

 extend to great distances beyond the central body." This 

 atmosphere he considers to extend not less than two or three 

 times the length of the solar radius, and to its attracting 

 power is due the difference in tint and splendour of the centre 

 and margin of the disk. This immense atmosphere increases 

 in density in its lower layers, which are near the surface of the 

 liquid ignited mass. " After a series of photometric measures 

 of the light of the penumbra, compared with the most con- 

 siderable extinction of light which the photosphere experiences 

 when it plunges by narrow isthmuses into the depth of the 

 cavities, we come, with the help of depression measured in the 

 penumbra, to the conclusion that the central body is situated 

 at a depth about ten times greater than this depression." The 

 lower layers of the solar atmosphere must acquire an immense 

 temperature through contact with the incandescent mass, and 

 the great pressure they experience ; and from variations in 

 their temperature perpetual movements arise. The liquid 

 surface of the sun must vary in temperature from a variety of 

 causes, such as ascending and descending currents, and varia- 

 tions in the diathermancy, or heat -transmitting power, of dif- 

 ferent portions of the atmosphere. A rapid and constant 

 evaporation goes on from the liquid surface supplying the 

 matter, which is precipitated in a crystalline form. 



" When we examine the sidereal universe with reference to 

 the probabilities which determine the incandescence of stars, 

 we are convinced that the principal cause is the condensation 

 of agglomerated masses of cosmical matter." M. Chacornac 

 points out that, with a given pressure and temperature, vapours 

 will have a density little below that of a liquid ; and it is, 

 therefore, reasonable to suppose that, at a certain distance 



