Recent Observations upon Solar Physics, 449 



from their arrangement in the field of view, the intervals between 

 them, their colour, and general aspect"*. To bring this into 

 harmony with the preceding determinations in which measures 

 were made, we must suppose that M. Rayef s B and E were in 

 reality C and b. It is to be observed that the intervals between 

 B and C, and between E and b } are the two smallest of the in- 

 tervals between lines lettered by Fraunhofer, and therefore that 

 these rays are the most liable to be confounded in such eye-esti- 

 mates as M. Rayet made. The details of M. Janssen's obser- 

 vations have not reached Europe ; but he describes hydrogen as 

 detected in the principal protuberance ; and therefore his report 

 also inclines in favour of C. On the whole, then, we may with 

 most safety conclude that the lines seen were probably C, D, b, 

 F, the hydrogen line near G-, and four other very faint lines. 

 Those which seem to be identified are the principal lines of hy- 

 drogen, sodium, and magnesium — the three gases in the solar 

 atmosphere which, as I have elsewhere shown \, project far beyond 

 all other known constituents. 



99. The most probable account to be given of this great pro- 

 minence would appear to be that which I ventured to advance in 

 a paper which was presented a year and a half ago to the Royal 

 Society (see Proceedings of the Royal Society, vol. xvii.). [For 

 convenience of reference the paragraphs of this paper are num- 

 bered in succession after those of the paper in the Proceedings of 

 the Royal Society.] There is a low-lying shell of attenuated clouds 

 outside the photosphere, at a distance from it of somewhat more 

 than one semidiameter of the earth. Now, in the memoir already 

 referred to, I have shown (§ 68) that if a disturbance in the 

 lower parts of the outer atmosphere heave a part of this shell of 

 cloud above, its natural level into a cooler region, it will, from 

 its continuing to be exposed to the unmitigated glare of the 

 photosphere, import an enormous amount of heat into its new 

 neighbourhood, which will have the effect of so heating the air 

 through which the mist is dispersed, that the entire mass of 

 cloudy particles and interposed gases will commence a violent 

 ascent, and thus both produce a cyclone over the photosphere 

 which may result in a spot, and give rise above to such great 

 columnar ilames as the one which has been found to give out 

 these blight lines. When writing my paper I did not overlook 

 the circumstance that the intermingled gases would emit bright 

 lines ; but I was under the impression that all such lines would 

 be extinguished by the absorption of the surrounding colder parts 

 of the atmosphere through which they should make their way 



* Comptes Rendus, October 12, 1868, p. 75S. 



t See memoir on the " Physical Constitution of the Sun and Stars," 

 passim, Proceedings of the Roval Society, vol. xvii. 



Phil. Mag. S. 4. Vol. 36. No. 245. Bee. 1868. 2 G 



