346 M. F. Zollner on the Temperature and 



the abstract of a communication to the Paris Academy *, as fol- 

 lows : — 



"1. The regions of the faculse and spots are the richest in 

 protuberances. 



" 2. There are two sorts of protuberances : — one faint and 

 light, spread like the light cirri in our atmosphere; the other 

 denser, more compact, sharper, having a fibrous structure and 

 peculiar optical characters." 



That the more lively eruptions, which with greater velocity 

 penetrate through the lower and more vaporous layers of the 

 atmosphere, may drag portions of it upward above the lower 

 limit of the chromosphere and exhibit its constituents spectro- 

 scopically by bright lines, if the eruption be sufficiently vehe- 

 ment, is a phenomenon to be expected. Corresponding to this, 

 Father Secchi finds in the spectrum of the striking and intense 

 protuberances above mentioned numerous lines of incandescent 

 metals. He designates them on this account briefly as of me- 

 tallic character, and (/. c.) sets forth their connexion with the 

 spots in the following definite terms : — 



" I then observed carefully all the eruptions having this cha- 

 racter, which, for shortness, I will name metallic ; and I found 

 that every time one of these eruptions was observed at the eastern 

 margin of the sun, a spot was visible on the following day. The 

 connexion is so real that, during the last months, I have been 

 able to predict the appearance of a spot by the mere inspection 

 of the quality of the spectrum and the eruption. The five rota- 

 tions of which I give the summary have themselves furnished 

 twenty-four instances." 



Father Secchi (/. c.p. 253) holds himself justified, on the ground 

 of this connexion in space between the two phenomena, to draw a 

 conclusion respecting the nature of their causal connexion : — 



"The conclusion from all we have just said is manifest. The 

 spots are produced by the eruption, from the interior to the ex- 

 terior, of masses of the metallic vapours I have indicated." 



Why the converse of the conclusion here denominated " mani- 

 fest " could not also satisfy the observations (" the eruptions 

 are produced by the spots ") — that is, why the spot cannot, as 

 an occasioning cause precede the formation of the eruptive pro- 

 tuberances, I have vainly sought in Father Secchi* s works for a 

 reason at all solid ; for the reason of the fact above noticed, that 

 at the eastern edge of the sun the upper portions of the protu- 

 berances first become visible, and on the following day, when the 

 rotation of the sun has proceeded further, the till then concealed 

 spot first comes into view, lies in relations so simple that it can- 



* Comptes Rendus, vol. lxxvi. pp. 250-257 (Feb. 3, 1863). 



