592 



SCIENCE. 



[Vol. II., No. 39. 



spare mirror of 0.40 m. diameter was carried as a 

 reserve, but was not brought into use, as, by great 

 care, the first was kept uninjured, in spite of the fre- 

 quent rains and the moisture of the climate. 



Mr. Janssen gives the following condensed report 

 of his own observations, drawn up immediately after 

 the observations, in accordance with the plan by 

 which all the observers of the party were governed : — 



" My observations were of two classes, — optical 

 and photographic. The optical observations were 

 principally designed to determine whether the coronal 

 spectrum consists of a continuous spectrum as a 

 background with bright lines, or if the Fraunhofer 

 lines exist there generally (an investigation made 

 especially with regard to the question of extra-solar 

 cosmic substances). In 1871 I had announced, that, 

 besides the hydrogen lines, I had established in the 

 spectrum of the corona the presence of the D line 

 and of several others. 



"In the present eclipse I proposed especially to 

 solve this question. By means of the optical arrange- 

 ments above described, I have been able to determine 

 that the basis of the coronal sijectrum is composed 

 of the complete Fraunhofer spectrum. The prin- 

 cipal lines of the solar spectrum, especially J), h, E, 

 etc., were detected so surely that there can be no 

 possible doubt of this fact. I recognized, perhaps, a 

 hundred lines. 



"1 recognized this composition of the spectrum, 

 particularly in the lower or most brilliant portions of 

 the corona, but not to an equal degree at the same 

 distance from the moon's limb. The details of this 

 will be given and discussed at a future time. 



" I studied also the rings of Respighi. The rings 

 did not appear uniform about the moon's limb, but 

 presented peculiarities of structure which will be 

 especially discussed in their relation to the question 

 of the Fraunhofer lines. 



" I studied also polarization, but devoted to it only 

 a few moments, using the excellent biquartz polari- 

 soope of Prazmowski. The polarization was very 

 well defined, and possessed characteristics already 

 recognized. 



"Before the observations, I made a preliminary 

 examination of the corona with the naked eye, and 

 with an excellent telescope by Prazmowski. This 

 examination was for the purpose of guiding me in the 

 subsequent observations. 



" All these studies — study of the shape, spectrum 

 analysis, Eespighi's rings, polarization — were com- 

 bined with the view of solving the question of extra- 

 solar cosmic substances. We think that the discovery 

 of the complete Fraunhofer spectrum in that of the 

 corona considerably advances this question. 



" Photography. — Two great instruments, contain- 

 ing eight cameras, had been prepared for studying the 

 question of intra-mercurial jjlanets, and that of the 

 shape and extension of the corona. With regard to 

 heavenly bodies in the vicinity of the sun, these pho- 

 tographs will require a minute examination ; but, 

 with respect to the corona, it can be said that the great 

 power of several of the lenses used [that of eight 

 inches (0.21m.) and that of six inches (0.16m.)], and 



also the length of exposure, permitted us to prove that 

 the corona has an e.itension very much greater than 

 that shown by optical examination, either with the 

 naked eye or in my telescope. 



"Several of our large pliotographs of the corona 

 have great distinctness. They show important details 

 of structure which ought to be discu.ssed. Tlie shape 

 of the corona was absolutely fixed during the whole 

 duration of totality." 



The reports of Messrs. Tacchini, Palisa, and Trou- 

 velot are not given, but are alluded to in the discus- 

 sion of the results of the observations, wiiich next 

 follows. Mr. Janssen regards it quite improbable that 

 any intra-mercurial planets exist, on account of the 

 negative testimony given by Mr. Palisa, combined 

 with that of Professor Holdeu of the American party. 

 Mr. Trouvelot's conclusion is less decisive, but the 

 observer wished to re-examine the region of the sky 

 before coming to a final conclusion.' The author 

 adds, " When we consider that the bodies discovered 

 by Professor Watson in 1S7S can be identified, within 

 the limits of error to which the method employed by 

 that astronomer is liable, with two stars in Cancer,- 

 we arrive at the conclusion that it is to-day extremely 

 improbable that there exists one or more planetary 

 bodies of any importance between Mercury and the 

 sun. Our photographs, although iiot yet completely 

 examined, seem to lead to the same conclusion." 



The duration of totality was found by Mr. Trouve- 

 lot to be 5m 24».l, by Mr. Tacchini to be 5m 238. 



On the subject of the corona, Mr. Janssen thus 

 writes: — 



" 27(6 corona. — Mr. Tacchini's report shows that 

 this skilful astronomer made remarkable observa- 

 tions at Caroline Island, especially with regard to the 

 analogy between the composition of the spectrum 

 of certain parts of the corona and the spectrum of 

 comets. It was part of my plan to examine this 

 correspondence, as is shown by a note drawn up by 

 me long before the eclipse, and which I read to my 

 colleagues when we compared our respective reports. 

 It is a matter which ought to be verified with the 

 greatest care in future eclipses. However, I leave to 

 Mr. Tacchini the task of developing his observations. 



" It will be seen from my report, that the principal 

 object of my observations was to decide one point of 

 the composition of the spectrum of the corona which 



' Mr. Trouvelot observed, near Iho cloBe of totality, a star 

 wbicli he describes as 'bright, and of a pronounced red color; ' 

 but, by some misunderstanding, its position was not recorded by 

 the special attachments to the circles above described. Its posi- 

 tion, tliereforc, cannot be determined, nor thequestion of itti iden- 

 tilicalion be positively settled. The obscrvcrannounccs(Coni;7(«s 

 rendus, Sept. 17) that he lias re-examined the region, and finds 

 no star of the eorrcsp(in<iiiig magnitude and color in the vicinity 

 of the approximate posilicuL ivliicb he was able to assign to it. 

 " Although, " he adds, " the absence of a red st.ar as bright as 

 that which I observed in the eclipse seems quite natimilly to load 

 to the conclusion that the body in question is no other than an 

 intra-mercnrial planet, yet as the most necessary elements, such 

 as the position and a disk or a sensible phase, are wanting in 

 my observation, I think I ought to suspend, for the present, my 

 conclusions upon the probable nature of the body." 



= First pointed out by Dr. C. II. F. I'etera {.Aslron. nadir., 

 nos. 2263 and 2254). 



