Feb. 28, 1889] 



NATURE 



421 



GEOGRAPHICAL NOTES. 



The paper read at Monday's meeting of the Royal Geo- 

 graphical Society was by Captain Vangele, giving an account of 

 his exploration of the Welle-Mobangi river, the great northern 

 tributary of the Congo. His first exploration was made in the 

 end of 1886 in a flat-bottomed boat, the Henry Read, with a stern 

 paddle-wheel. On this first journey Captain Vangele did not 

 succeed in getting beyond Mr. Grenfell's furthest, the Zonge 

 Fails, just where the river turns sharply to the east. He gives 

 an interesting account of the Ba- Ati, the people who inhabit the 

 banks of the river, and who are in every way of a superior type, 

 though cannibals. A little distance above its mouth the Mobangi 

 or Ubangi measures about 2730 yards in breadth ; its greatest depth 

 is 5 fathoms, its lowest I fathom ; it flows at the rate of 3^ feet a 

 .•second. Under the 4th degree, just below the rapids, it still has 

 a breadth of 1300 yards, a depth of 4 fathoms, and a velocity of 

 4 feet a second. Between these two points, though continually 

 varying in breadth, it never exceeds about 4000 yards, including 

 the islands. The general appearance of the river is pretty much 

 the same as that of the Congo near Bolobo — strewn with islands, 

 and having low wooded banks. The colour of the water is a 

 light brown. Captain Vangele's second journey was made a 

 year later, and with better means of forcing his way up the 

 rapids of the Mobangi. This time, though he encountered 

 several obstacles, he managed to push his way up 

 the river to over 22° E. longitude, and to within sixty 

 miles of Junker's furthest point on the Welle. This has been 

 accepted as clearly proving the identity of these two rivers, so 

 that the long-standing problem of the Welle may be regarded as 

 solved. At his furthest point[Captain Vangele had to turn back 

 owing to the hostility of the natives, the only instance in which 

 he met with real opposition. Between rocks and islands, rapids 

 and cataracts, the navigation of the lower Mobangi is beset 

 with difficulties, though it is evidently practicable with suitable 

 vessels, and a thorough knowledge of the river. The river is 

 subject to great variations of level, according to the season of 

 the year. Above the Zongo Falls, the people, named Bakombe, 

 differ considerably from those on the lower river, and evidently 

 spread far inland. From above the Zongo rapids the river opens 

 out, flowing straight from the north-east, and the outlook is 

 described as superb. It is free from all obstacles, from 900 to 

 1000 yards wide, with a depth of 12^ fathoms, flowing between 

 banks 6 to 10 feet high, grassy plains alternating with clusters of 

 trees. After thirty miles in the northeast direction the river 

 turns due east, which direction it maintained to the end of the 

 voyage, 170 miles. The banks are densely inhabited, and pro- 

 visions of all kinds abound. Between the Zongo Falls and the 

 steamer's furthest point only one tributary was met with— the 

 Bangasso— coming from the north. After the paper was read, 

 Sir Francis De Winton made some remarks with regard to the 

 position of Mr. Stanley. He totally disbelieves the conjecture 

 of Lieut. Baert that Stanley has any intention of taking Khar- 

 toum. On the contrary. Sir Francis believes he is now on his 

 way home by the east coast. 



In the last issued number (4.0 trimestre, 1888) of the Bulletin 

 of the Paris Geographical Society will be found a very complete 

 examination of the route for a proposed Euphrates Valley Rail- 

 way, by M. A. Dumont. M, Adrien Blondel contributes a 



detailed account of the Island of Reunion. M. Jules Marcou, 

 in concluding his paper on the origin of the name of America^ 

 decides against Vespucci and in favour of an aboriginal place- 

 name. 



It has been arranged that the eighth German Geographe ntag 

 shall be held at Berlin from April 24 to 26 next. 



The Ceylon Observer sutes that Mr. Stephens, who has recently 

 been amongst the Veddas of Ceylon, and who subsequently 

 explored New Guinea, is now in Ceylon on his way to Singa- 

 pore to organize an expedition at the instance of Prof Virchow 

 to explore the unknown portions of the Malayan Peninsula. Mr. 

 Stephens's instructions are to start from Malacca and travel north- 

 north-west through the vast expanse of unexplored territory which 

 stretches northwards for some 500 miles. There are on the coast 

 various settlements near mines and plantations, but the greater 

 portion of the interior has been hitherto unexplored. T.he 

 inhabitants are said to be jealous and bloodthirsty." 



Jlf. LCE WrS INVENTIONS AND RESEARCHES.^ 

 T T is now my pleasing duty to lay before you the grounds on 

 which the Council have awarded the gold medal to M. 

 Maurice Lcewy for his invention of the equatorial coude, of a 

 new method of determming the constant of aberration, and for 

 his other astronomical researches. 



On examining the series of memoirs in which M. Loewy has 

 set forth his new methods of astronomical research, we are at 

 once impressed by the originality of conception which charac- 

 terizes all his ideas, and by the thoroughness with which he has 

 worked out the details necessary for the practical application of 

 his new methods of observation. Observational astronomy has 

 for many years past proceeded on such well-defined lines, that 

 we have not unnaturally come to look rather to improvements 

 of detail than to the introduction of new instruments for the 

 advancement of our knowledge. It is, therefore, a matter of 

 great satisfaction to find that M. Loewy has placed at our dis- 

 posal various methods of observation based on entirely new 

 principles, and calculated to give astronomers improved and 

 quite independent means of attacking several of the most 

 important problems in our science. 



The first of these new instruments with which I will deal is 

 the equatorial coude. 



It was in the year 1871 that M. Loewy proposed his new form 

 of equatorial, to which the name of "equatorial coude" has 

 been given, and M. Delaunay, then Director of the Paris 

 Observatory, was so struck with the value of the principle that 

 he arranged for the construction of an instrument on this plan. 

 M. Delaunay's death, however, interrupted the work, and the 

 first equatorial coude, having an object-gla^is of 0*27 metre, or 

 about 10 j inches aperture, was not completed till the year 1882. 

 The success of this instrument was so marked that its value could 

 not fail to be recognized, and it was not long before the con- 

 struction of several larger equatorials on the same principle was 

 commenced. At the present time six equatorial cotides have 

 been completed, and four of these are already mounted and in 

 regular use at the Observatories of Paris, Lyons, Besan^on, and 

 Algiers. The other two are intended for the Observatories of 

 Paris and Vienna. 



In principle the equatorial coudi may be described as an 

 adaptation of the form of transit instrument with axial view to 

 the requirements of an equatorial, by the addition of a plane 

 mirror inclined at 45° outside the object-glass, this mirror being 

 capable of rotation about the axis of the telescope, so as to 

 reflect into the latter the rays from any object in a perpendicular 

 plane. The axis of the instrument is mounted as a polar axis 

 between two piers, the telescope being broken at a right angle 

 near the lower pivot, so that the rays from the object-glass are 

 reflected by an internal mirror up the polar axis to the hollow 

 upper pivot, where the image is formed. The rotation of the 

 outer mirror thus brings into the field the image of any object 

 in the hour-circle perpendicular to the object-end of the tele- 

 scope, and by the rotation of the polar axis, as in an ordinary 

 equatorial, the telescope is directed to any hour-angle. The 

 declination-axis in the equatorial coude is the axis of the object- 

 end of the telescope about which the outer mirror turns, and the 

 declination-circle placed at the eye-end, in the same plane with 



' Address delivered by the President of the Royal Astronomical Society, 

 Mr. W. H. M Christie, F.K.S. Astronomer-Royal, on presenting the Gold 

 Medal of the Society to M. M. Loewy at the anniversary meeting on February 

 8,1889. 



