rapid changes of form and position which are observed in the 

 spots themselves. 



9. There are often seen, in the neighborhood of the spots, jets 

 curved backward upon the solar disk in forms which are sensi- 

 bly parabolic. 



10. The immense jets and erupted masses near the spots ex- 

 pand and vanish away more rapidly than in any other region. 



11. On the area of the spots neither the photosphere nor 

 the edge of the sun's disk shows any perceptible irregularity, 

 that is, neither any perceptible prominence nor depression.* 



From these results obtained by spectroscopic observations of 

 the border of the sun and of the protuberances. Prof. Eespighi 

 is led to certain conclusions relative to the physical constitu- 

 tion of the sun, among which the following may be mentioned. 



In the first place, the photosphere would appear to be the sur- 

 face of an incandescent liquid mass or stratum, of suitable speci- 

 fic gravity, by the weight of which various gases, and especiaJJY 

 hydrogen, are confined and compressed in the interior of the 

 sun, lit an elevated temperature, under an enormous tension, ana 

 with a density diff-ering but little from that of the superincum- 

 bent liquid stratum.! , 



These gaseous masses in the interior of the sun, not yet hav- 

 ing been brought to a condition of stable equilibrium, migM in 

 some portions be less condensed, and hence from hjrdrostati 



t^rPQ«nrP wnnlrl rioA fnwarri tbp snrffl.ne with STCat veloClty, UnOl, 



pressure would rise toward the surface with great velocity, 

 overcoming by their enormous expansive force the resi.^^- . 

 of the liquid statum, they would burst through it with a ve- 

 locity greater or less according to the depth from which tie 

 emerged, and the degree of tension in which they ongim^^^ 

 were, and would thus develop those jets or eruptions wnici 

 constitute the protuberances. , ^ -^ 



The masses thus erupted, then, would not be detemm^ 

 in their movement solely by their initial velocity and tne _ 

 tion of gravitation, but would generally be subjected to 

 operation of other forces which would concur in their eieva^o , 

 their diffusion, and their ramification into t^^se extraoroiu^^ 

 forms which the protuberances present. According to J^ 

 pothesis, the hydrogen issuing from the body of the ^Jf "^ ^^ 

 serve as aliment to the chromosphere, repairing thus tn^ K 

 losses of the latter, by its not improbable combination ynm 

 substances of the photosphere ; and it does not ^VV^^^\-^.^^. 

 Kespighi absurd to suppose that this immense stratum o . 

 descent hydrogen, that is, the chromosphere, may be the pi 

 pal source of the heat radiated from the sun. 



* See foot note on next page. ,. ^ „f the B".^*' 



t See the article of Prof. Zf.llner, trannlated from the Proceedmgj^^ philosopW- 

 and thoroughly 



