THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



NOVEMBER 1870. 



XLI. On the Temperature and Physical Constitution of the Sun. 

 By Professor F. Zollner*. 



[With a Plate.] 



$.1. 



AMONG the characteristic forms of the protuberances t 

 which the spectroscope used with wide slit now enables 

 every one to examine, a considerable number convince the ob- 

 server at once that we have here to do with enormous eruptions 

 of incandescent hydrogen. 



Without stepping beyond the range of known analogies, and 

 therefore of conditions explanatory of cosmical phenomena, it is 

 scarcely possible to find a cause for these eruptive protuberances 

 other than that of a difference of pressure between the gases in 



* Translated from a separate impression, communicated by the author, 

 from the Proceedings of the Royal Saxon Society of Sciences, June 2, 1870, 

 t The protuberances maybe classedin two characteristic divisions, accord- 

 ing to their shapes, viz. into the vapour- or cloud-forms, and the eruptive 

 forms. The predominance of the one or of the other type appears to de- 

 pend partly upon local conditions of the solar surface and partly upon 

 periodic variation ; so that at one time one type may prevail, whilst at an- 

 other time the other type may be most strongly developed. It is easy to 

 see why the cloudy prominences so closely correspond in form to terrestrial 

 clouds and vapours, when we remember that the forms of our clouds depend 

 not upon the suspended vesicles of water, but upon the mode in which dif- 

 ferent masses of heated and moving air are distributed. The vesicles in 

 terrestrial clouds form only the material by means of which this difference 

 in the masses of air is rendered visible. The clouds of the solar protube- 

 rances are rendered visible by the light emitted by the masses of glowing 

 hydrogen. 

 Phil. Mag. S.4. Vol. 40. No. 268. Nov. 1870. Y 



