348 



NATURE 



{Feb. 13, 15^79 



the days named, by an orbit, the elements of which Dr. 

 Oppolzer gives as follows : — 



Epoch 1850, January i*o, Paris M.T. 



Mean anomaly 



Longitude of perihelion . . . 

 ,, ,, ascending node 

 Inclination to ecliptic 



Angle of excentricity 



Log. semi-axis major 



Mean diurnal motion 



... 356 o 



27 45 ) Equinox of 



... 178 o\ 1850. 

 7 O 

 14 13 or <f = 02456 



... 9"09o6 



... 22°789529 



The period of revolution would therefore be 15797 

 days. Comparing with the observations employed the 

 following are the differences shown by the above orbit in 

 geocentric longitude ; the calculated geocentric latitude 

 is annexed : — 



1800, March 29, Fritsch 

 1802, Oct. 10, ,, 



1819, Oct. 9, Stark 



1839, Oct. 2, Decuppis ... 

 1849, March 12, Sidebotham 



1857, Sept. 12, Ohrt 



1859, March 26, Lescarbault 

 1862, March 20, Lummis 



But it is unfortunate that notwithstanding this almost 

 perfect representation of the longitudes assumed and the 

 circumstance that the latitudes point to a transit across 

 the sun's disk on every date, there are apparently fatal 

 objections to our admitting the existence of a planet with 

 these elements, several of which are pointed out by Dr. 

 Oppolzer. It may be sufficient to mention here the first 

 of them : — With so short a period and small inclination, 

 a transit across the sun's disk would occur every year, and 

 we know that observation by no means supports such a 

 condition. However, the existence of a body moving in 

 this orbit will admit, as Dr. Oppolzer states, of very early 

 decision : — On March 18 a nearly central transit should 

 -occur — 



h. m. o 



Ingress at 18 8 Berlin M.T. ... Angle of position 74 

 Egress at 23 15 „ ... „ 254 



We give these particulars as aff"ording another illustra- 

 tion of the difficulties attending any trustworthy infer- 

 ences from the observations of suspicious spots upon the 

 sun's disk. The above orbit, it should be mentioned, will 

 not accord with either of Prof. Watson's presumed 

 planets, though possibly, by increasing the excentricity, 

 elements might be found which would agree with one or 

 other of his positions, while representing most of the 

 observations used by Dr. Oppolzer. We ignore the idea 

 ■of a want of bona fides on the part of the observers on so 

 many occasions, but there is still to be remembered the 

 fact that comets hare traversed the sun's disk, and with 

 •small perihelion distances might do so without our disco- 

 vering them except in the course of transit, supposing 

 them to possess the degree of condensation which some 

 have indicated. The object observed by M. Coumbary 

 at Constantinople in May, 1865, could only have been a 

 •comet, with a perihelion distance so small as, like the 

 great comet of 1843, almost to graze the sun's surface. 



GEOGRAPHICAL NOTES 



At the meeting of the Geographical Society on Monday, 

 when the Earl of Dufferin occupied the presidential chair 

 for the second and last time, Mr. T. J. Comber, of the 

 Baptist Missionary Society, who is about to lead an ex- 

 pedition above the Yellala Falls of the Congo, gave some 

 account of his explorations inland from Mount Cameroons, 

 in the course of which he visited a district of country 

 previously unknown, and discovered a small lake to the 

 northward of the mountain ; he also ascertained that 

 there was a broad valley there instead of a continuous 



mountain range. He mentioned one fact with regard to 

 Mount Cameroons, which goes far to show that there 

 may be some difficulty in finding a suitable spot for the 

 proposed missionary sanatorium. When at an eleva- 

 tion of 2,000 feet there were such heavy mists, that, 

 although he slept between two fires, his blanket was 

 wet through. It is, of course, possible that here, 

 as in the Neilgherry Hills, and other places, posi- 

 tions may be found to which the miasmatic influences 

 do not extend. Mr. Comber next gave some brief and 

 interesting notes of a journey which he made through 

 Congo to Makuta, the place which Lieut. Grandy saw 

 from the brow of a neighbouring hill, but was not allowed 

 to enter. Sir Henry Barkly afterwards read some obser- 

 vations on the Bamangwata country in South Africa, to 

 which a melancholy interest attached from the fact of 

 their having been drawn up by the late Capt. R. R. Pat- 

 terson, who recently met with his death by poison when 

 some three days' journey from the Victoria Falls of the 

 Zambesi. The country would appear to be of a not very 

 promising nature, for its soil is sand, covered with 

 stunted bush, and there are few mountain fastnesses, 

 except those near Shoshong, the capital ; in the winter 

 it is badly watered, as the Limpopo, Zambesi, and Zouga 

 (or lake river), are the only rivers which run continuously, 

 while the Tati, Shasha, and Makalapogo, are sand rivers. 

 The open country is sparsely inhabited by Veld-people 

 of two classes, the Bakala and Masarwa, of whom the 

 former enjoy the right of possessing cattle and gardens, 

 but the latter neither ; they are, in fact, slaves, living on 

 game and roots. The Bamangwata country is ruled by 

 a chief named Khame, whom Capt. Patterson described 

 as a very good man, an opinion in which Sir H. Barkly 

 concurred. 



In connection with the meeting on Monday at Preston 

 in reference to a Central African railway, the letter in 

 yesterday' s Titties from the Alexandria correspondent of 

 that paper is of interest. It seems that the Khedive had 

 some time ago devised an excellent scheme for bringing 

 the riches of the great lake district to the outer world by 

 way of the Indian Ocean, at the mouth of the Juba river. 

 The distance between that point and Victoria Nyanza is 

 only 280 miles, and McKillop Pasha was instructed to 

 work gradually from the coast, planting colonial stations 

 at regular distances, while Gordon Pasha was to co- 

 operate from the lake side. Though the plan seems to 

 have been ably, but too secretly devised by the Khedive, 

 it rather unfortunately fell through, we think on account 

 of the jealousy of the Sultan of Zanzibar and his friends. 

 There is no talk by the Khedive of a railway, and we 

 think with the Titties correspondent, that something more 

 elementary should be attempted, with a country so totally 

 undeveloped as that of Africa. That it will be opened to 

 trade soon by some nation is evident. English, Germans, 

 Italians, French, Portuguese, are all striving from various 

 points. There is plenty of room for all. 



A LARGE amount of material for arriving at some 

 approximately correct notion of the mean depth of the 

 sea, has accumulated in recent years. In a note to the 

 Gottingen Academy, Dr. Kriimmel has lately attempted 

 this, in view of the vague and variable statements on the 

 subject in text-books. Soundings were wanting for the 

 Antarctic and a part of the North Polar Sea, i.e., about 

 475,000 square miles, or 7 per cent, of the entire sea- 

 surface, so that he gives his estimate only as a closer 

 approximation. He estimates, then, the mean depth of 

 the sea as 1,877 fathoms, or 3,432 metres, or 0-4624 geo- 

 graphical miles. It was natural to compare the mean 

 height of dry land above the sea-level. Humboldt's 

 estimate of 308 metres is regarded as quite out of date. 

 Leipoldt has since estimated the mean height of Europe 

 as 300 metres. Accepting this number for Europe, 500 

 for Asia and Africa, 330 for America, and 250 for 



