462 



NATURE 



\August 29, 1878 



vious days had strongly shown the advantage of separat- 

 ing the parties as much as possible. We chose a spot to 

 lee\yard of one of the enormous water tanks of the 

 Union Pacific Railway, which form the chief features in 

 the interesting but desolate plains in that region, over 

 which the wind sweeps at times with incredible violence. 

 On reaching our destination we found Prof. Newcomb, 

 whose camp was about a mile away, and it was then 

 agreed that as both he and Prof. Watson were to hunt 

 for the planet they had better be together, so I lost his 

 company during the eclipse. 



Prof. Watson's plan of operation was to sweep south of 

 the sun and observe all the stars in the map, a part of which 

 is here reproduced (Fig. 6), and to refer the position of 

 any new body to the stars, or, if possible, to the sun itself. 

 For this purpose, with the assistance of the Rawlins 

 carpenter, he armed his equatorial with paper circles and 

 brass wire pointers. He commenced operations to the 

 left of the sun and saw the stars marked, but none others. 

 Then sweeping out to the star marked b he noticed on 

 his return another not on the chart, marked a. He then 

 made three marks on his right ascension paper circle, 

 on the spots occupied by the pointer, when the sun, <zand 

 b, were successirely brought into the centre of the field. 

 He next determined the difference of declination in the 

 same way between the sun and a, having the additional 

 help that a was nearly in the same declination as b. He 

 then repeated his R.A. measures, and called Prof. New- 

 comb, but the eclipse was over before anything more could 

 be done. I give this statement from memory only (as I 

 was too busy to make notes at the time), as I heard it 

 soon after the eclipse at the camp, before the telescope 

 was dismounted. It is probable that subsequent careful 

 measures of the circles may alter the place — 

 R.A. 8h. 26m. 

 Dec. + iS" 00' 



I telegraphed to you, somewhat, but the alteration will be 

 small. ^ 



Since arriving here I have learned that Mr. Swift, of 

 Rochester, a well tried observer, also saw the planet. 

 The first account I read of his work was as follows : — 



" This gentleman made a very careful search for 

 Vulcan, scanning the heavens very closely with his 

 splendid comet eye-piece, made by the celebrated Gund- 

 lach, but ho saw nothing of it. He did, however, see, 

 about three degrees from the sun, two stars not down in 

 the charts or star maps, and about as bright as the pole 

 star — they were pointing directly towards the sun. On 

 attempting to re-find them, he was prevented by a little 

 cloud." 



Since then, however, another fuller account of his work 

 has appeared, from which I gather that about one minute 

 after the commencement of totality two stars caught his 

 (Mr. Swift's) eye about three degrees, by estimation, south- 

 west of the sun. He saw them twice, and attempted a 

 third observation, but a small cloud obscured the locality. 

 The stars were both of the fifth magnitude, and but one 

 is on the chart of the heavens. This star he recognised 

 as Theta in Cancer. The two stars were about eight 

 minutes apart. There is no such configuration of stars 

 in the constellation of Cancer. In 1859 the French 



A K*^" Soing to press we receive a letter from Prof. Watson, dated Ann 



,„' ■*-"6"'*t 14. stating that the result of more careful examination gives 



— Washingt n M.T., July 29, sh. i6.ti., R.A, 8h. 26m. 54s., Dec. + 18° 16'. 



astronomer, Lescarbault, claimed that he had seen an 

 intra-Mercurial planet crossing the sun's disc. He re- 

 lated his discovery to Leverrier, who became a firm be- 

 liever in the existence of such a planet. The perturba- 

 tions of Mercury's orbit demand such a planet as Lever- 

 rier named Vulcan. The star Mr. Swift saw may have 

 been the same that was seen by Prof. Watson, who was 

 located at Rawhns, Wy. T. 



Mr. Swift possessed a comet eye-piece of very flat and 

 large field, and distinct to the very edge. It was made 

 in Rochester, and to it and his blunder in faihng to untie 

 his instrument, he believes he owes his success. 



The instrument used in the search for Vulcan by Prof. 

 Holden proved to be inadequate to show all the stars on 

 the Washington star map, owing to the brightness of the 

 corona. The space where the planet seen by Prof. 

 Watson was, was four times swept over, but so near to 

 the sun as this, a four and a-half magnitude star was not 

 to be seen. A space of io° in declination by 35° in right 

 ascension was twice swept over. 



Here, again, we get an idea of the thoroughness with 

 which the work has been planned and executed. 



It would be wrong to conclude these hurried notes 

 without stating that, from the day in which I landed in 

 New York to the present time, I have become every- 

 body's debtor for acts of kindness, which have touched 

 me greatly. This great country is a land of true courtesy, 

 for which I here express my gratitude, not only to my 

 scientific brethren, and chiefly to Dr. Draper, General 

 Myer, and Prof. Newcomb, whose guest I have been, but 

 to hundreds to whom I have been a stranger and unknown. 

 As significant of the keen interest taken in the eclipse 

 by all classes here, I may mention, in conclusion, that on 

 the Sunday before the event prayers for fine weather were 

 offered in all the churches of Denver. 

 Washington, D.C., Aug. 8 J. Norman Lockyer 



AS \ have been recently giving attention to the subject 

 of solar spectroscopy in consequence of my dis- 

 covery of oxygen in the sun, it seemed desirable to take 

 advantage of the total eclipse of July 29, to gain as 

 precise an idea as possible of the nature of the corona, 

 because the study of that envelope has been regarded as 

 impossible at other times. The main point to ascertain 

 was whether the corona was an incandescent gas shining 

 by its own light, or whether it shone by reflected sunlight. 



For this purpose I organised an expedition, and was 

 fortunate enough to secure the co-operation of my friends 

 Professors Barker and Morton, and Mr. Edison, The 

 scheme of operation was as follows : (i) the photographic 

 and photo-spectroscopic work, as well as the eye slitless 

 spectroscope were to be in charge of my wife and myself; 

 (2) the analysing slit spectroscope was in charge of Prof. 

 Barker, with the especial object of ascertaining the 

 presence of bright lines or else of dark Frauenhofer lines 

 in the corona; (3) the polariscopic examinations were 

 confided to Prof. Morton, who was also to spend a few 

 moments in looking for bright or dark lines with a hand 

 spectroscope ; (4) Mr. Edison carried with him one of his 

 newly-invented tasimeters with the batteries, resistance- 

 coils, Thomson's galvanometer, &c., required to deter- 

 mine whether the heat of the corona could be measured. 



This entire programme was successfully carried out, 



