(' 5% ) 



chromosphere speotnim. \\\\\\ //, A. //,; and some iron liiio!? it is 

 C'onspicnoiis that llic .iluKtrnial raiiitiicss roLiards mainlv the i)road 

 dark shadings of the lines, i. c. those parts, whose darkness in the 

 noi'nial s|»e('trnin we attriliuled not to aWsorption. luit to dispersion. 

 Moreovei-, the dark itand due to tlie s[)ol has nearly disapj)eared. This 

 means tliat waves, wliicli in normal circunistanees are wantini;; in 

 the spot specti'iim on accoinit of thcMr stroiiu' dispersion, at the time 

 of the distui-liance had l)een .uatiiered au'ain into the heain reaching 

 the instrument. 



'How all this may lia|)pen will hecoine evident as >oon as we sliall 

 he able to estai)lisli a |)hiiisii)le eanse, hy which, within an angulai- 

 space great enough to iiichuk' a considei-ahle part of tlie >ohir disk, 

 t li e strcmgiy «1 i s per sed rays might i>e gathered again. 



It is not Jiecessary to inti"o(hice a new hypothesis for tlie jturpose. 

 The same idea aliout the Suns constitution'' which enabletl us to 

 explain the ]>r()perties of the chromosphere and the pi-<uuiuences, 

 furnishes us once more with the re([uired data. 



Ijideed, if (according to Schmidt's theoi'v) the Sun is an unlimited 

 mass of gas, surfaces of di>conlinuity must exist sinular lo those, 

 Avhose general feature^ has heen detei-niiiKMl hy K>ti)i':N "j foi- a shar[)l\ 

 outlined radiating and rotating sun. rhe>e surfaces iniist extend unto 

 the remotest paiMs ol" the gaseous ImkIv — a concdusio)! in excellent 

 hai'mony with the \isihle stiaiclure of the coi-ona. h'oi' alonii' the 

 siirfai-es of disconliuuily wa\es ami w liirN ai'c loriued; the core-lijies 

 of the x'ortices nearly coincide with the generatrices of these surfaces 

 of revolution, and iu these cores the density is a minimum. This 

 ma\ account for the streaky appeai'ance, shown uiore or less dis- 

 tinctly in all good photourajihs and <lrawin,Lis of the coi'ona. 



This particidar ap[)earance may ha\e an(»thei' cause, though ; for 

 what follows, however, this is imuiaterial. We oidy assume that the 

 density of the coi-onal matter varies in such a way, as to cori-espond 

 to the striped structure visible at the time of a total etdipse of the Sun. 



A coronal streamer which, at a gixen moment, rujis exactly in the 

 direction of the Earth may Ite very roughly comj)ared, then, to a 

 inindle of glass tubes through which we are looking lengthw ise. Such 

 a structure will gather and conduct i-ays of various directions, ente- 

 ring it at one end. This takes place also if the parts with the greater 

 and those with the smaller optical density do not alternate abruptly, 

 like glass and air. but gradually. 



1) Proc, Roy. Acad. Amst. IV, j.. Ur2. 



~) R. Emken. Reitiagf' ziir Sonnentlieorie, Aun. d. Pliys. L^], 7, p. 17G — 197. 



