282 



NATURE 



{July 20, 1 88: 



ness, and shares with Tibet the honour of being among the least- 

 known countries in the world. Now, however, that both England 

 and the United States have persuaded the Coreans to throw 

 open four of their ports to commerce, we hope that our ignorance 

 of an interesting land will soon be dispelled. Corea is almost 

 half the size of France, and its population is variously estimated 

 at from nine to fifteen millions. M. Elisee Reclus, in his 

 " Geographie Universelle," compares the peninsula to Italy. 

 Like Italy, it has a mountain chain running down the centre of 

 the ^country, and giving off lateral valleys ; as in the Apen- 

 nines, the gentlest slopes and most fertile valleys are in the west, 

 while the east is more precipitous and barren. As with Italy, 

 Corea has in the north-west an Alpine mass, which guards her 

 from intrusion there, though the mass does not really cover all 

 the boundary. Of the geology we know but little, though many 

 valuable minerals, including coal, are supposed to abound, and 

 the country as a whole is capable of great development with 

 proper guidance and suitable machinery. We trust before the 

 inevitable Europeanising process is complete, that accurate 

 information on the habits and customs, language, and ethnology 

 of the Coreans will be obtained. 



In presence of the numerous and contradictory hypotheses as 

 to the former geological history of the delta of the Amu-daria, 

 it is obvious that no satisfactory scientific result as to the change 

 of beds in the basins of the Amu and Syr-daria can be arrived 

 at, without a thorough geological study of the different deposits 

 of the rivers of the great Aral depression. A first step in this 

 direction was made by the Amn-daria expedition ; and now M. 

 Hedroitz publishes, in the Izvestia, a valuable paper, giving the 

 result of his researches in the same direction. Of course, one 

 year is too short a time for thoroughly exploring this u ide Geld ; 

 and M. Hedroitz's researches, however safe his method, and 

 valuable his observations on the geological structure of alluvial 

 deposits of different rivers of the Aral depression, on the motion 

 of sand-dunes in the steppe, &c , are not yet sufficiently advanced 

 to bring the author to a few general conclusions from his obser- 

 vations. His paper contains more valuable data than ready- 

 made theories, and we hope that he will again return to the 

 Amu to continue his researches. But one of his conclusions 

 is worthy of notice. He doe, not admit that the Uzboy was a 

 branch of the Amu-daria, as was admitted by the first explorers 

 of this old bed. He supposes that there was a time (before the 

 tenth century) when the Amu reached the Caspian, but by means 

 of another bed which was situateo south of the Sary-kamysh 

 depression, leaving here the beds of "Amu-alluvium," which 

 are seen in the lower parts of the Uzboy, but are missing in its 

 upper parts. As to the Uzboy, it was but a temporary and 

 irregular outflow of Lake Aral towards the Caspian, being rather 

 a series of salt lakes and ponds, than a true river. Its name, 

 Uz-boy (or " Uz-boyu," " along ponds"), would seem to confirm 

 this hypothesis. The geological exploration would thus again 

 call in question our established theories as to the former aspect 

 af the Aralo Caspian basin. 



Hartleben, of Vienna, is issuing in parts a seventh 

 German edition of Balbi's Universal Geography, under the 

 editorship of Dr. Josef Chavanne, whose name is well-known as 

 a scientific geographer and cartographer. Dr. Chavanne, to 

 judge from the parts issued, is doing his work of editor con- 

 scientiously. In the mathematical and physical sections he 

 seems to us to have brought the clas-ical work abreast of the 

 latest researches ; and among the good points in the political 

 geography are the statistics obtained at the recent censuses of iSS I 

 and 18S2, of all the leading countries of the world. While 

 neither so detailed nor so picturesque as Reclus' "Geographie 

 Universelle," the new edition of Balbi is perhaps more syste- 

 matic and better adapted as a text-book, though it is published 

 as a " house-book." With an exhaustive index the work will 

 serve all the purposes of a succinct gazetteer. 



The leading article in Pelcrmann's Miitheihtngen for July is 

 a long account of the unfortunate Jeannette expedition, with a 

 map showing its drift from East Cape, north-west, to Bennett 

 Island, and the route of the boats south-west to Lena mouth, 

 after the loss of the vessel. The course of the exped tion within 

 two years was thus within very narrow limits, and the gains to 

 science can be of comparatively small moment. A long letter 

 from Dr. Emin-Bey describes his journey in the east of Babr-el- 

 Jebel, in March, [April, and May of last year. Among the notes 

 is a letter from Dr. Schweinfurth, describing the results of his 

 journey in April and May this year, along the Nile above Siut, 



for the purpose of collecting data for his map of the Nile valley ; 

 he gives some notes on the geology of the region. 



The following extract from a letter from Mr. W. Thomas, 

 Meteorological Office Reporter at Scilly, to Mr. Robert H. Scott, 

 F.R.S., Secretary to the Meteorological Council, has been sent 

 us for publication : — "Scilly, July 14, 18S2. I beg to inform 

 you of a curious disturbance of the sea at 9 a.m. yesterday, 

 July 13, about low water, the wind S.S.W. The water flowed 

 rapidly up to 3 feet perpendicular, and then ebbed out again. 

 It flowed and ebbed three times ; the second and third time was 

 not so high as the first. From the first to the last was about 

 half an hour. 



The Bolktino of the Italian Geographical Society for May 

 and June contains a detailed account of the work of the expedi- 

 tion under Capt. Cecchi in Shoa, with a map. 



The Danish Arctic Exploring Expedition under the command 

 of Naval Lieut. Hovgaard, sailed on Tuesday on her expedi- 

 tion. 



The Geological Society of Stockholm has despatched an 

 expedition to Spitzbergen, having for its special object the 

 increase of our knowledge of the vegetable palaeontology of the 

 island. 



BAROMETERS 



T , 



HE subject is so old and well-worn that it is impossible to 

 add anything new to it, still it is so large that there is no 

 fear of its being exhausted by the few following notes. It will 

 be going back quite far enough if we begin with Hook (Phil. 

 Trans, i., 218, 1666), who invented the wheel barometer, and point 

 out that his (1666) method consisted in using a mercury trough 

 formed of two short open cylinders communicating near the 

 bottom). Into one of these the lower end of the barometer tube 

 was inserted while the float connected with the index rested on 

 the mercury in the other. Derham (Phil. Trans, xx., 45, 1698), 

 avoided the uncertainty caused by the float, cor I, and index- 

 bearings, and took his readings by means of a rod (terminating 

 in a point) connected with the index by a rack and pinion. Gray 

 (Phil. Trans, xx, 176. 1698) in the same year proposed the very 

 method that is now in use for taking observations with the stan- 

 dard barometers, for he left the barometer tube free of all 

 fittings and attachments, and read off the actual height of the 

 mercurial column by means of a microscope (sic) sliding on a 

 vertical scale. Fitzgerald (Phil. Trans, lii., 146, 1761) attached 

 two movable indexes to the dial of the wheel barometer to show 

 the highest and lowest points reached during any given period ; 

 and he also gave the float nearly the fall range by having the 

 upper part of the tube three inches in diameter, while the short 

 upturned end was only half an inch diameter. In 1770 (Phil. 

 Trans. lx., 74) he increased the range of the index by introducing 

 a system of levers with arms of unequal length. 



The earliest suggestion for increasing the sensitiveness of the 

 barometer was made (1668) by Hook, who fixed over the mer- 

 cury a narrow tube containing spirit. Descartes also proposed 

 that same form of instrument which was made by Huyghens ; 

 but the uncertainty caused by the vapour-tension of the spirit 

 rendered the readings so valueless that Huyghens (and this 

 method was also claimed by De la Hire) connected the 

 capillary tube with the shorter upturned end of the baro- 

 meter, and thus did not interfere with the vacuum. Rowning 

 employed the same principle, but bent the fine tube over, so 

 that (though still parallel to) it was below the mercurial column ; 

 Hook's (Phil. Trans, xvi., 241, 16S6) method of 1686 consisted 

 in having enlargements at both surfaces of the mercury and 

 another, open, over the capillary. Above the coloured spirit and 

 water which came to a convenient height in the fine tube, he 

 placed turpentine sufficient to partly fill the open enlargement. 

 As the rise in the spirit-column was thus compensated (or nearly 

 so) by the shortening of the turpentine column, it had no appre- 

 ciable effect on the level of the mercury. The conical or pendant 

 birometer of Amontons (1695) consists of a conical tube of very 

 fine bore, containing the mercurial column, suspended with the 

 wider end downwards. When the pressure of the air increases the 

 mercury ri^es in the tube, but owing to the diminished diameter 

 it occupies a greater length ; when the pressure is less the column 

 descends, until on reaching a wider part of the tube it is suffi- 

 ciently shortened to restore equilibrium. Theoretically the 

 range may be increased to any extent by having a tube of only 



