NA TURE 



H5 



THURSDAY, JUNE 14. 1883 



THE ECLIPSE OBSERVATIONS 



THE following telegrams have been received touching 

 the observations of the total eclipse of the sun on 

 the 6th ult. :— 



To the Secretary, Science and Art Department 



San Francisco, June 12, 8.16 a.m. 



Double grating on equatorial indifferent ; dense prism 

 on 6-inch equatorial good; integrating Hilger good ; red 

 end slit good, red end prismatic camera indifferent, first 

 order blue Rowland bad, second order blue Rowland bad, 

 4-inch photoheliograph indifferent, small photoheliograph 

 good. Lines obtained mostly hydrogen, prominences 

 almost absent. 



Through Renter's Agency 



San Francisco, June 12 



The solar eclipse on the 6th ult. was very successfully 

 observed by the English, American, and Continental 

 astronomers stationed on Caroline Island, the sky being 

 beautifully clear at the time. The corona extended over 

 a distance of two diameters from the sun. The light 

 during the middle of totality was equal to that of the full 

 mocn. Successful observations were made by Dr. Janssen, 

 as well as by Prof. Tacchini, the intra-Mercurial planet 

 Vulcan was not seen by M. Palisa. The D line of the 

 spectrum was seen dark in the corona by Dr. C. S. 

 Hastings. Good photographs of the corona were obtained 

 by the English observers as well as by Dr. Janssen. The 

 English observers were also successful in obtaining 

 photographs of the flash. Good photographs were taken 

 of the coronal spectrum in the blue end. The health of 

 Messrs. Lawrence and Woods, the English observers, is 

 excellent. 



Putting these two telegrams together, there is every 

 reason to be contented with the work which has been 

 done by the polyglot band of observers on Caroline 

 Island, for, as is to be gathered from the telegrams, this 

 and not Flint Island was the one selected for the site of 

 the observatories. Certainly the photographic attack has 

 been stronger than it has ever been before ; more novelties 

 have been attempted, and more have been successfully 

 achieved, whilst the scale on which the work has been 

 done leaves nothing to be desired. Taking, for instance, 

 the photographs of the corona, although we do not know 

 the precise size to which Dr. Janssen limited himself, we 

 may be certain that among his attempts would be in- 

 cluded one to take pictures, giving a dark moon of at 

 least six inches in diameter. That by means of the 

 clockwork-driven photographic plate, the flash, by 

 which term is meant that instantaneous appearance 

 of bright lines at the moment of commencement and 

 end of totality, has been secured, shows us that we 

 have now a method of recording eclipse phenomena 

 which is not likely to be neglected on a future 

 occasion. We may hope in a few days' time to get some 

 further information touching the eye-observations made 

 by Prof. Tacchini and the American observers. Reuter's 

 telegram is strangely silent about them at present, and 

 there is little doubt that they have something far more 

 Vol. xxviii.— No. 711 



important to tell us than that the dark line D was seen in 

 the spectrum of the corona, for that was observed as long 

 ago as 1871 by Dr. Jannsen. It would be much to be 

 regretted if observations of the lines visible before 

 and after totality were not attempted, especially as we 

 learn that the photographs are limited to a greater or less 

 extent to the lines of hydrogen. 



The following general remarks have already appeared 

 in the Times with regard to the results of the observa- 

 tions, and we cannot do better than reproduce them : — 



" News from the eclipse party has at length arrived. 

 As we stated in our article, published on the 4th of May, 

 the American ship of war, instead of returning to Callao 

 as was at first anticipated, proceeded to the Sandwich 

 Islands, and there is little doubt that the English party made 

 the voyage thence in one of the Pacific mail steamers. 



'' A telegram coming through Reuter's Agency informs 

 us generally of the success of the observations. The 

 weather seems to have been everything that could be 

 desired, and although the observations were necessarily 

 made from the lowest possible level, the extension of the 

 corona was quite as great as was expected at this period 

 of maximum solar activity. Further, we learn that the 

 light during totality was quite equal in intensity to that of 

 the full moon. This is another indication of the ex- 

 ceptional brightness of the corona, because in this eclipse, 

 which was one of exceptional duration — and that is why 

 such strenuous efforts were made to observe it— the lower 

 and more brilliantly illuminated portions of the sun's at- 

 mosphere being more than usually veiled by the dark 

 body of the moon during the middle of totality, the 

 illumination of the air by these portions of the sun was 

 less than is ordinarily the case. Unfortunately, the tele- 

 gram may be read both ways touching the intra-Mercu- 

 rial planet observations. We take it, however, to mean 

 that no intra-Mercurial planet was seen by M. Palisa, who 

 would probably give his chief attention to that point. It 

 is satisfactory to learn that good photographs of the 

 corona were obtained both by Dr. Janssen and the Eng- 

 lish observers. We may expect that the French photo- 

 graphs of the corona will surpass in beauty and detail 

 anything which has yet been secured during eclipse ob- 

 servation. It is good news, too, to learn that for the first 

 time in the 1 istory of eclipses the momentary flash of 

 bright lines seen just before the beginning and immedi- 

 ately after the end of totality has been photographed. Re- 

 verting for a moment to our previous article, we would 

 remind our readers that this end has been attained by 

 the use of a slowly descending plate actuated by clock- 

 work, which, since the flash has actually been photo- 

 graphed, will give its complete history, and enable us to 

 determine the exact order in which the lines appeared and 

 reappeared before and after totality. 



"The telegram sent by the English observers, Messrs. 

 Lawrence and Woods, to the Science and Art Depart- 

 ment, supplies further particulars as to the results of the 

 various attempts at recording the history of the eclipse. 

 The first instrument on the official list is a Rutherford 

 grating with 17,000 lines to the inch, which was used in 

 conjunction with an equatorial telescope of six inches 

 aperture. The grating was so arranged that the photo- 

 graphs of the green part of the first order spectrum on 

 the one side and the same part of the second order spec- 

 trum on the other side should be attempted. This would 

 give the region near F, one of the chief solar lines in the 

 blue-green parts of the spectrum ; but although the photo- 

 graphs were actually obtained, the observers do not 

 seem to be very proud of them. 



"The next instrument is a dense prism of 60°, 

 mounted on a six-inch equatorial of very short focus. 

 The object in view in employing a short focus was to 



