No. 1.] ARMSTRONG — LAST SOLAR ECLIPSE. 13 



Upon questions liaviug reference to tlic Prominences and other 

 immediate surroundings of the Sun — phenomena which can be as 

 well, if not more easily investigated at other times — it is not our 

 intention now to offer any remarks. 



It may be said, then, that until the latter part of the year, 

 ISTO, the spectroscope had failed to disclose the typical spectrum 

 of that absorbing envelope, now call the cliromatosphcre.. But at 

 the close of that year, Professor Young was successful in identi- 

 fying it during the December Eclipse. It was known to be vapor- 

 ous from its absorptive action, and might, therefore, be expected 

 to yield a discontinuous sjyect mm of hvi^^ht lines, corresponding to 

 the dark lines in that of ordinary sun-light. It was suspected also, 

 by Secchi and others, to be shallow in comparison of its associated 

 envelopes. Then again, owing to the amount of diffused light 

 present and the extremely small angle such an object as it was 

 supposed to be would subtend at the earth's surface (noti more 

 than fu:o or three seconds), it was seen to be almost impracticable 

 to obtain any spectroscopic view of it during ordinary daylight. 

 In addition to this, the attention of observers during the preced- 

 ing Eclipses of the series had been turned to the investigation 

 of what were then more important matters. Hence it was that 

 the spectrum of this member of the Solar surroundings remained 

 undetected until Professor Young, of Dartmouth — of whom, as 

 well as of the other American observers, it is only right to say 

 that the work done by them has universally borne the impress 

 of unfailing care and thoroughness, — succeeded, when observing 

 in Sicily, in obtaining its unassociated spectrum. 



This discovery was thus reported by one of his fellow observers,. 

 Professor Langley : — '' With the slit of the spectroscope placed 

 '• longtitudinally at the moment of observation, and for one or 

 ^' two seconds later, the field of the instrument w^as filled with 

 '• bright lines. As far as could be kidded during' this brief 

 '^ interval every non-atmospheric line of the Solar Spectrum 

 '' showed bright." He adds, " w^e seem to be justified in 

 " assuming the probable existence of an envelope (^the chromatos- 

 '- phere) surrounding the Photosphere, and beneath the Chromo- 

 ^' sphere, usually so called, whose thickness must be limited to 

 '' two or three seconds of arc, (from nine to fourteen hundred 

 '' miles), and which gives a discontinuous spectrum consisting of 

 '- all, or nearly all, the Fraiinhofer lines, showing them, that is, 

 '• bright on a dark ground.*' 



