1871.] The Eclipse of Last December. 233 



Yet, again, on the question whether the fainter and 

 radiated part of the corona, even to its extremest extent, 

 actually belongs to a solar appendage, the history of former 

 researches speaks very plainly. These radiations have been 

 seen to remain unchanged in position, not only during 

 totality, but for twenty, thirty, even forty seconds afterwards. 

 They have also presented the same figure as seen from 

 distant stations. So that, setting aside, as we justly may, 

 all the accounts of seeming changes in certain radiations 

 (since such changes may so easily be explained, or are, rather, 

 on any theory to be expected), the positive evidences, which 

 there is no misinterpreting, force on us the conclusion that 

 the true solar corona has radiations extending to enormous 

 distances from the sun. 



As respects the spectroscopic evidence, there seemed room 

 for doubt. Lieutenant-Colonel Tennant had in 1868 obtained 

 from the corona a faint continuous spectrum, without either 

 dark lines or bright lines. . The American astronomers in 

 1869 had seen different spectra : in some cases a single 

 bright line on a continuous spectrum, in others a bright 

 line and two fainter ones, while in yet others a continuous 

 spectrum was alone discerned.* 



There was little room for doubt as to the significance of 

 these observations. In the " Quarterly Journal of Science " for 

 October last, I pointed out reasons for believing that all the 

 observations should be accepted, the apparent difference 

 between the results being regarded as due in all probability 

 to a difference in the opening of the slit of the spectroscope. 



This view, — abundantly verified by the observations made 

 during the late eclipse, leaves us a double spectrum to in- 

 terpret, — a continuous spectrum and a spectrum of bright 

 lines. Assuming that the background of the spectrum really 

 is continuous — that is, that no dark lines exist in it — we 

 should infer that the source of light is matter in the solid 

 or liquid form, and incandescent through intensity of heat. 

 It is possible, however, that dark lines exist, but are unseen 

 on account of the faintness of the spectrum ; in which case 



* I may take this opportunity of correcting a mistake which has been made — 

 in these pages and elsewhere — with respect to Professor Young's observations 

 of the coronal spectrum in 1869. He saw, indeed, three lines, but he was not 

 sure that more than one of these — the line 1474 Kirchhoff — belonged to the 

 corona. " I have felt," he writes, " somewhat annoyed by finding the other 

 two lines put on the same footing as 1474." This is a point requiring correction, 

 though surely not calculated to annoy. The mistake arose from the inexact 

 wording of the American reports ; and may be compared to the erroneous 

 account given by the American observers (including Professor Young) in 1869 

 of the observations made by Tennant in 1868 — his continuous coronal spectrum 

 appearing in their accounts as a spectrum showing the solar dark lines. 



VOL. VIII. (O.S.) — VOL. I. (N.S.) 2 H 



