390 SCIENTIFIC RECORD FOR 1883. 



The author adds, " When we eonsider that the bodies discovered by 

 Professor Watson in 1878 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 im- 

 probable that there exists one or more planetary bodies of any impor- 

 tance between Mercury and the sun. Our photographs, although not 

 yet completely examined, seem to lead to the same conclusion." 



The duration of totality was found by Mr. Trouvelot to be 5 m 24A1, 

 by Mr. Tacchini to be 5 m 23 B . 



On the subject of the corona, Mr. Janssen thus writes : 



" The corona. — Mr. Tacchini's report shows that this skillful astronomer 

 made remarkable observations 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 obser- 

 vations was to decide one point of the composition of the spectrum of 

 the corona which has always seemed to me very important, viz, whether 

 the light of the corona contains an important proportion of solar light. 

 The result surpassed my expectation in this matter. The Frauenhofer 

 spectrum, so complete as I witnessed it at Caroline Island, proves that, 

 without denying that a certain part is due to diffraction, there exists in 

 the corona, and especially in certain parts of the corona, an enormous 

 quantity of refracted light ; and as we know, besides, that the coronal 

 atmosphere is very thin, it must be that in these regions cosmic matter 

 exists in the condition of solid corpuscles, in order to explain this abun- 

 dance of reflected solar light. 



" The more we advance, the more we perceive the complex nature of 

 the regions in the immediate vicinity of the sun ; and it is only by per- 

 sistent and very varied observations and an exhaustive discussion of 

 these observations that we can arrive at an exact knowledge of these 

 regions. The great eclipse of 1883 has allowed us to take a step for- 

 ward. 



" Photography of the corona. — The result of the studies of the photo- 



in the vicinity of the approximate position which he was ahle to assign to it; "al- 

 though," he adds, "the absence of a red star as bright as that which I observed in 

 the eclipse seems quite naturally to lead to the conclusion that the body in question 

 is no other than an intra-mercurial 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. H. F. Peters, A»t. Nach., 2253 and 2254. 



