JuTie 13, 1878] 



NATURE 



179 



inhabitants of the Tanganika shores and the artistic 

 people of Manyema, with their elaborately coiffeured 

 heads. To speak of these people, and even many of 

 the tribes on the banks of the Livingstone, as savages is 

 a misuse of language. People who can build houses and 

 organize villages and towns such as they do, who can work 

 their native iron, ivory, wood, and bone, into all sorts 

 of artistic and useful shapes, and who can reason and 

 speak as Mr. Stanley shows us they do, have raised them- 

 selves to a level considerably higher than the savage. 

 West of Tanganika, especially, the tribes seem very much 

 mixed up, and there are many evidences that the Living- 

 stone with the neighbouring region is a sort of border- 

 land where several races meet, and where a constant 

 struggle is going on. What can be made of these Africans 

 under competent direction, Mr. Stanley himself has 

 shown us in the case of his own people. 



Of the various products, mineral, vegetable, and animal, 

 of the country through which Mr. Stanley passed we 

 have many glimpses. The natural wealth of the country 

 is extravagant, and the botanist especially will find much 

 that will interest him, especially as Mr. Stanley has been 

 at the trouble of frequently giving the scientific names of 

 the plants which he mentions. 



There is ample furniture of maps in the work, all of 

 them well-executed, though in Mr. Waller's two large 

 maps there are occasional signs of carelessness in the 

 spelling of names, and, very strangely, the memorable 

 Vacovia of Sir Samuel Baker is omitted from the names 

 on the east shore of Albert Nyanza. Beside the two 

 large maps of East and West Equatorial Africa, by Mr. 

 Waller, there are also an interesting series of five maps 

 by the same hand, showing the progress of discovery in 

 Equatorial Africa. There is, first, a portion of Dapper's 

 map of 1676, very similar to that of 1701, which we gave 

 last week, showing two great central lakes, from the most 

 westerly of which, Zaire lacus, issue both the Nile and 

 Congo. The next one shows our knowledge between 

 1849-56, with all the features of Dapper's maps swept 

 away, and the first rude indication of Tanganika given. 

 Then, between 1856-63, we have the work of Livingstone, 

 Burton, Speke, Grant, enabling us to more correctly 

 define Tanganika, locate Victoria Nyanza, and shadow 

 out Albert Nyanza. The next stage, 1866-75, shows a 

 great advance. By the labours of Schweinfurth, Baker, 

 Livingstone, Stanley (first journey), and Cameron, the 

 main features, from 10° N. to 15" S., east of 25° E. long. 

 — rivers, lakes, and mountains— are filled in more or less 

 accurately. Last of all come the results of the journey 

 described in these two volumes, and which we have 

 endeavoured to summarise in this notice. There is also 

 a chart of the Lukuga creek, and two beautiful large-scale 

 charts, by Stanford, of the Livingstone or lower falls 

 (thirty-two in number), and of the upper or Stanley falls. 

 Mr. Cooper has, as usual, done his part well in repro- 

 ducing the numerous and varied illusti-ations ; and alto- 

 gether the get-up is thoroughly creditable to the publisher. 



In conclusion, let us repeat that Mr. Stanley has done 

 a great work, and told us all about it in a great book. 



OUR ASTRONOMICAL COLUMN 



The Transit OF Mercury, 1868, November 4.— The 

 second internal contact at this transit was well observed 

 in many European observatories, though at others the 

 bad definition and tremulousness of the sun's limb 

 vitiated the results. If we calculate strictly from Le- 

 verrier's tables of sun and planet, with Prof. Newcomb's 

 value of the mean solar parallax, 8"-848, we shall have 

 the following formula for reduction of the observed 

 Greenwich mean time at any place to the centre of the 

 earth : — 



/^ = 2oh. 5901.51-95. -F [1-4056] r sin / - [i-7232]/-cos/, ccs(Z. -(- 55° si'-s). 



where / is the geocentric latitude, r the radius of 

 earth at the place, and L the east longitude from Green- 

 wich. 



A comparison with observations shows difierences as 

 below : — 



Observed 

 Place of G.M.T. Error of the 



Observation. reduced to Calculatioa. 

 earth's centre, 

 h. m. s. 



Bonn 



21 o 3*4 - 11-5 



Three observers : extreiaes. 

 differ, 13-55. 



Christiania — 6*3 — 14*4 " Four observers 

 Durham — 12*2 — 20*3 



Greenwich — 6'9 — 15*0 Six observers. 

 Leyton — 12*6 — 20*7 



Lund — 14*4 — 22-5 



Madrid — I3'8 — 21*9 Merino. Rupture of ring. 



Marseilles 20 59 57-6 — 5*7 Leverrier. 

 „ 21 o 12-6 — 207 Stephan. 



Paris - 7-6 " ^ 57 j'^rnd Wotff!^"^'' '''"'"""'' 



.. 20 59 57-0 - 5-1 Rayet. 



Rome 21 o 10*4 — 18*5 Secchi and Mancini. 



Vienna 20 59 55*5 — 3-6 Oppolzer. 



.At the Royal Observatory, Cape of Good Hope, where 

 the transit was very completely observed, the sun' s limb, 

 is stated to have been tremulous at the second internal 

 contact, which probably accounts for the larger differ- 

 ence, -32'2s., between calculation and observation, 



Brorsen's Comet of Short Period. — When the 

 elements of this comet, at its first appearance in 1846^ 

 had been satisfactorily determined, it was pointed out by 

 Mr. Hind, in a communication to the Royal Astronomi- 

 cal Society, that the comet must have made a very close 

 approach to the planet Jupiter about May 20, 1842, and 

 that probably to this near approximation the form of the 

 orbit in 1846 might be attributed. The late Prof. 

 D' Arrest examined this question more closely in the 

 year 1857, and by the formulae of the Mecaniqiie Celeste^. 

 which had been already applied in the case of Lexell' s- 

 comet of 1770, he ascertained that a great change of 

 elements was then caused by the action of Jupiter^ 

 assuming the mean motion given by the observations of 

 1846 to be affected with no material error, as we now 

 know to have been the case. He found that the greatest 

 proximity occurred May 20'69, Berlin time, when the 

 distance of the comet from Jupiter was only o"o5ii of 

 the earth's mean distance from the sun, and that previous 

 to April 19, 1842, the elements of the comet's orbit were 

 as follows. The elements of 1 846 are added for com- 

 parison : — 



Elements before the Elements ia 



great perturbation. 1846. 



Mean longitude, 1842, April 19*5... 23716 ... " — 



Longitude of perihelion 133 27 ... Il6 2S 



,, ascending node ... 107 44 ... 102 40 



Inclination to ecliptic 40 51 ••• 3° 57 



Eccentricity o*59275 ••• o'793S6 



Semi-axis major 3*68645 ... 3'i5352 



These figures prior to 1842 are necessarily only a first 

 approximation to the orbit then described, but they suf- 

 ficiently explain the circumstance of the comet not having 

 been observed before that year, since the perihelion dis- 

 tance was then greater than 1*5, and as Prof. D' Arrest 

 remarked, under this condition Brorsen's comet would 

 hardly be observable. 



According to Dr. Schulz's elements for 1873, when the. 

 comet was last visible, the nearest approach of its orbit 

 to that of Jupiter now takes place in 283° 30', when the 

 distance is o'i24, and thirteen revolutions of the comet 

 are almost exactly equal to six revolutions of Jupiter. 

 D' Arrest, from a rough calculation, considered that thei 

 orbit might again undergo great or complete change frora 

 the action of this planet in the year 1937. The only 



