May 20, 1880] 



NATURE 



67 



OUR ASTRONOMICAL COLUMN 



The Transit of Mercury, May 5-6, 1S7S.— An Appendix 

 to the "Washington Observations, 1876," is devoted to reports 

 on telescopic observations of this transit and discussions of 

 them. There are individual reports from Professors Asaph 

 Hall, Harkness, Eastman, and Holden, and from Dr. Henry 

 Draper and Mr. H. M. Paul. Probably no other ] henomenon 

 of the kind ha> been watched by so large a number of observers, 

 109 names appearing in the general record. They \yere, with 

 very few exceptions, stationed at different points in United States 

 territory. The observations have been calculated by Prof. 

 Eastman and Mr. Paul : the former, attaching greater \i'eigh.t to 

 a certain number made by more expe -ienced observers, finds for 

 the Washington geocentric times those given in the second 

 column below; Jlr. Paul deduces for the most probable values 

 those given in the third column (the time of first external con- 

 tact depending on only two or three observations being omitted; 

 the other contacts depend on 57, 52, and S obiervatious 

 respectively) : — 



EVSTMAN. 



First external contact 

 First internal ,, 

 Second internal ,, 

 Second external ,, 



22 4 42 'o 



22 7 42-1 



S 35 27-8 



5 38 257 



Paul. 

 h. m. 5. 



227 40'6l ± 0'45 



5-35 2S'83±o-4S 

 5-3S 29-52 ± riS 



If the first series of times are compared with the figures in the 

 American Ephemei-is, which depend upon the earlier theory of 

 Mercury of Leverrier, the errors of prediction are respectively 

 + 77s., + 84s., + :ios., and + 119s. These differences are 

 greatly diminished if the times are compared with those resulting 

 from Leverrier's later theory involved in the tables in the Paris 

 Annales, vol. v., as u-ed ia the Nautical Almanac, more 

 especially if the solar semi-diameter employed is diminished by 

 2"'o, so as to make the results more strictly comparable with 

 those of the American Ephemeris : we have then for the errors 

 of computation, + 2s., + 9s., + 25^., + 34s. The superiority 

 of the later theory is thus evident, and it will be remembered 

 that this theory involves the increased motion of the perihelion 

 of mercury, which induced Leverrier to suspect the existence of 

 one or more planetary bodies, or of matter in some form between 

 Mercury and the Sun. 



We may add that if the positions of the planet in the Niaiti:al 

 Almanac are combined with the semi-diameters of sun and planet 

 inferred by Leverrier from the transits, the computed times of 

 the internal contacts exhibit differences of + i9'Ss. and + i6'4s., 

 the first agreeing closely with the corresponding one deduced 

 from observations in Europe. 



The Second Comet of 18S0 (Schaberle, April 6).— On 

 the evening of May 8 this comet pa;sed nearly over a star of the 

 eighth magnitude, No. 6S15-6 of Oeltzen's Argelander {- 901 

 of Fedorenko), and Major Tupman, K.M.A., availed himself of 

 this somewhat unusual opportunity for fixing the place of a comet 

 with great precision. By twenty comparisons, ten before and 

 ten after the conjunction in declination, it was found that at 

 loh. l6m. :7s. Greenwich mean time, the comet followed the 

 star 2'8os. and wa5 2''2 south of it. 



The following ephemeris, for Greenwich midnight, is derived 

 from elements which represent the observations pretty accurately 

 up to May S : — 



Right T-i 1- .• Log. distance frcm the 



Ascension. Declination. jj|„^ Sun. 



h. m. s. o , 



May 20 ... 6 22 53 ... +56 437 ... 0-38965 ... 0-27695 

 22 ... 6 23 57 ... 55 49-4 



24 ... 6 25 3 ... 54 56-6 ... 0-39725 ... 0-27379 

 26 ... 6 26 10 ... 54 5-2 



28 ... 6 27 17 ... S3 15-1 ... 0-40432 ... 0-27090 

 30 ... 6 28 24 ... 52 26-4 

 June I ... 6 29 32 ... +51 38-S ... o*4io84 ... 0-26S29 



It appears not improbable that this comet may be observed 

 until ton ards the end of the year, arriving at its least distance from 

 the earth early in November, and at the same time attaining its 

 greatest intensity of light. It will be lost from proximity to the 

 sun's place for several weeks about the perihelion pas.-age, which 

 is likely to occur abcut July i, becoming visible again at the 

 beginning of August in the morning sky. The orbit upon which 

 the above places are calculated gives for the position on August 

 5 at I2h. G.M.T., right ascension 6h. 58-7m.. declination + 



31° 52'. The intensity of light on May 8 was about one-third 

 less than is assigned for the first week in November. 



Prof. C. A. F. Peters. — We regret to have to record the 

 death of Prof. Christian August Fiiedrich Peters, formerly of the 

 Russian Central Observatory at Pulkowa, subsequently Professor 

 of Astronomy in the University of Konigsberg, and Director of 

 the Royal Ob.-ervatory at Kiel, and for upwards of twenty-five 

 years editor of the Astronomische Nachrichlen. After a long 

 illness he died on the 8th of the present month, in his seventy- 

 fourth year. We reserve a notice of Prof. Petera' principal 

 astronomical work until next week. 



GEOGRAPHICAL NOTES 



Before starting on his journey fro-m Lake Nyanza to Lake 

 Tanganyika, which we have previously referred to, Mr. J. 

 Stewart, of Livingstonia, spent some time in examining the 

 country on the west of the upper portion of the former lake. 

 He started from Kaningina, and cros-ed the mountain of the 

 same name at an elevation of about 5,000 feet. After a visit to 

 Chipatula's village he entered Mombera's territory in the Kasitu 

 Valley, and shortly reached the junction of the Kasitu with the 

 Rikura, which comes from the west through a wild and moun- 

 tainous country. The valley of the Rikuru north of the junction 

 is called Ntanta, and is exceedingly fertile ; the elevation is 

 about 3,700 feet, and the climate is cool and pleasant. Here 

 Mr. Stewart noticed an important change in the geological for- 

 mation, the granite and quartz giving place to soft shale and 

 clay schists ; and he is of opinion that the Kasitu foi-ms the 

 geological boundary, and that it runs in the trough of some 

 great fault or nonconformity in the formation. Ten miles further 

 north regularlv stratified beds of hard, dark grey sandstone were 

 met with. The Rikuru A'alley, which Mr. Stewart thought 

 would have taken him gradually down to the lake-level, is at its 

 north end blocked by hills forming the lake coast, and the river 

 flows through winding precipitous valleys, falling 2,000 feet in 

 the last fifteen miles. The water enters the gorge clear and 

 sparkling, and leaves it heavily laden with bluish clay silt, which 

 is visible far into the lake. Mr. Stew art reached the lake at the 

 mouth of this river in S. lat. 10° 45' 15". Marching northwards, 

 he visited Mount Waller, which he examined thoroughly, and 

 then, after keeping inland for four days arrived at the Kambwe 

 lagoon, his starting-point for Lake Tanganyika. The country 

 from Mount Waller to this place is very poor, consisting of 

 swamp and hard clay plain, broken here and there by dry gravel 

 ridges, and occupied chiefly by large game. 



The International African Association have just issued the 

 third part of their pei iodical publication, which contains extracts 

 from the reports of their travellers in East Africa. M. Cambier 

 fives an account of recent earthquakes on Lake Tanganyika and 

 some details of the work at the station at Karema, the position 

 of which he has fixed as in S. lat. 6° 47' 50". M. Popelin nar- 

 rates the particulars of his journey from Tabora to Karema, and 

 some of the plans for the future. There are also other letters 

 from them, as well as from Mr. Carter and M. van den Heuvel 

 and a medical report by Dr. Dutrieux. M. Burdo, the leader 

 of the third expedition, announces his arrival at Mpwapwa on 

 February iS, and sends a report on the route followed from 

 Saadani. His caravan consists of loS persons and fourteen 

 asses. 



The German branch of the International African Society 

 intends establishing the first German station at the southern 

 extremity of Lake Tanganyika. The expedition, in which Capt. 

 SchoUer, the well-known zoologist, Herr Boehm, and Dr. Kaiser 

 take part, has already left Berlin. Dr. Nachligal made several 

 communications on the subject at the last meeting of the Berlin 

 Geographical Society. 



News has been received concerning the expedition of Dr. 

 Mook and Herr von Holzhausen to the Pettit and Atbara rivers. 

 The travellers left Kassala on January 9, and reached Tomat on 

 the l6tb, after crossing the Pettit and the Atbara. Tomat is 

 the winter camp of the Sheikh of Dabanya bea )uii.s. Here 

 they were detained for eight days. Then they proceeded along 

 the left bank of the Atbara as far as the mouth of the .Hacher 

 Salam River, but were then compelled to return on account of 

 the absolute uncertainty of the country, and the indisposition of 

 Herr von Holzhausen. The country near the Bacher Salam is 

 completely deserted on account of hordes of Abyssinian brigands. 



