Nev. 24, 1887] 



NATURE 



89 



ceptible is the same for a ball as for a fine point. It occurs 

 with extremely smooth surfaces, and so cannot be attributed to 

 discharges in consequence of roughness of surface. With equal 

 potential the loss of electricity has the same magnitude, what- 

 ever the dimensions of the balls used as conductors. In air 

 saturated with vapours of insulating substances, the loss of 

 electricity of a conductor is nearly the same as in dry air. 



The large Russian ironclad Tchesme, now being finished at 

 Sebastopol, and having a displacement of over 10,000 tons, is to 

 have boilers heated with petroleum. If the results correspond 

 to what the Sebastopol engineers expect, the example is likely to 

 be followed elsewhere. In this connection we may note an 

 account in La Nature of November 5, of a gas-boat, as it may be 

 called, the Volapuk, recently constructed by M. Forest, in which 

 a gas-engine of six horse-power is driven, not by coal-gas, but 

 by air charged with carbureted hydrogen, by passage through 

 petroleum-oil. There are two pistons, and the explosive mixture 

 is ignited by means of a spark from a magneto-electric arrange- 

 ment. The engine consumes six litres of petroleum-oil per 

 hour, giving a speed of sixteen kilometres per hour. 



Among the various uses of celluloid, it would appear (accord- 

 ing to the Annates Industrtelles) to be a suitable sheathing for 

 ships, in place of copper. A French Company now undertakes 

 to supply the substance for this at 9 francs per surface-metre 

 and per millimetre of thickness. In experiments by M. Butaine, 

 plates of celluloid applied to various vessels in January last were 

 removed five or six months after, and found quite intact and free 

 from marine vegetation, which was abundant on parts uncovered. 

 The colour of the substance is indestructible ; the thickness may 

 be reduced to 0*0003 metre ; and the qualities of elasticity, 

 solidity, impermeability, resistance to chemical action, &c., are 

 all in favour of this use of celluloid. 



The following interesting observations with regard to the 

 mobility of loess have been made by M. Potanin during his last | 

 journey through the region south of the Ordos. As wind 

 steadily moves the shifting sands, so also water steadily moves 

 the loess, transporting it from higher to lower ^levels. The 

 underground water which filtrates through the loess, begins by 

 making in it a kind of cavern ; then a circular crevice appears 

 on the surface over the cavern, and a cylindrical vertical hollow, 

 which soon becomes a deep well, is formed through the thick- 

 ness of the upper layers of the loess. The whole surface of the 

 loess deposits is dotted with such wells, very dangerous to cattle. 

 By and by the formerly cylindrical well begins to extend in the 

 direction in which the underground water flows, and a narrow 

 ravine grows until it joins the main valley. Then masses of 

 loess continually fall down into the ravine, increasing its width. 

 The fall of these masses is favoured by the numerous crevices in 

 the loess, and it is so frequent that natives warn foreigners not 

 to approach the borders of a ravine. Of course the fallen 

 masses are further dislocated by water, and the loess is thus 

 steadily transported at a remarkable speed to lower levels. 



Hitherto it has been generally supposed that the glaciers of 

 the Caucasus are far from having the same development as those 

 of the Alps. It appears, however, from the last researches of 

 Abich, that, although no glaciers of the Caucasus are as long as 

 the Aletsch and Unteraar glaciers, or the Mer de Glace, there 

 are a great many of them. From tables compiled by M. Smirnoff" 

 in a recent issue of the Bulletin of the Moscow Naturalists' Society, 

 it appears that the average lowest levels of the Caucasus glaciers 

 are : 2504 metres in the Elburz Chain ; 2176 metres in the chain 

 to the west of the Adai-kokh ; 2266 metres in the high valley of 

 the Ingur ; 2898 metres on the eastern slope, and 2238 on the 

 northern slope, of the Kazbek ; from 2428 to 2658 metres in 

 Daghcstan ; 2776 metres on the Great Ararat ; and as much as 

 from 3162 to 3194 metres on the Shah-dagh. Comparing 



these heights with those reached by the lower extremities of 

 glaciers in other highlands, M. Smirnoff" concludes that in the 

 main Caucasus ridge the altitudes of the snow-line and the 

 glaciers are intermediate between the corresponding altitudes in 

 the Alps and those in the chains of Central Asia (Thian Shan and 

 Hindu Kush) ; and that in the western parts of the Caucasus the 

 altitudes of the perennial snow-line are nearer to those of the 

 Austrian Alps. There is some analogy between West Caucasus 

 and the Himalayas, inasmuch as the lowest limits of perennial 

 snow in both chains are higher on the northern slope than on 

 the southern. 



A " panorama-bijou" (or toy panorama), has been recently 

 brought before the French Societe d'Encouragement, by M. 

 Benoist, It is meant to give a succession of connected views of 

 photographed scenery, &c. Externally the instrument appears 

 as a cylindrical case with a handle projecting from its carved 

 surface. The observer looks through a lens, in the axis, towards 

 a mirror inclined 45', which reflects a panoramic view fixed 

 round the interior of an inner cylinder which is rotated by 

 clockwork. The back of the case is of ground glass, admitting 

 diffuse light. The instrument may be found a suitable com- 

 panion to the stereoscope on the drawing-room table. 



Frozen fish are now imported into France, and a Society 

 formed in Marseilles for the purpose of developing the trade (the 

 Societe du Trident) has a steamer and a sailing-vessel engaged in 

 it. The steamer Rokelle lately came into Marseilles with some 

 30,000 kilogrammes of frozen fish in its hold, the temperature of 

 which is kept at 17° C. below zero by means of a Pictet machine 

 (evaporating sulphurous acid). The fish are caught with the 

 net in various parts of the Mediterranean and Atlantic. After 

 arrival they are despatched by night in a cold chamber. Ex- 

 periment has shown that fish can be kept seven or eight months 

 at low temperature without the least alteration. These fish are 

 wrapped in straw or marine AlgK, and have been sent on to 

 Paris, and even to Switzerland. 



At the establishment of the National Fish-Culture Associa- 

 tion, Delaford Park, the American char, S. fonlinalis, spawned 

 as early as October 15. The thriving capacity of these 

 beautiful fish is becoming yearly more and more marked. Their 

 rate of growth at Delaford has been extraordinarily rapid. 



Dr. R. Baltzer, Professor of Mathematics at Giessen Univer- 

 sity, died at Giessen on November 7. He was born January 27, 

 1818. 



On October 22 a monument to Prof. Oswald Heer was 

 unveiled in the Zurich Botanical Gardens. The bust of the 

 great Swiss naturalist has been executed in a masterly manner by 

 Prof. Hoerbst. 



The additions to the Zoological Society's Gardens during the 

 past week include fifty-nine Pleurodele Newts {Molge walti), 

 seven Marbled Newts {Molge marinoratd) from Spain, presented 

 by the Lord Lilford, F.Z. S. ; two Moufflons ( Cwj musimon <J ? ) 

 from Sardinia, two Barbary Wild Sheep (Oz/zV tragelapkus S 9) 

 from North Africa, two South American Flamingoes {P/iceni- 

 copterus ignipalliatus) from South America, deposited j ten 

 Silky Bower Birds {Ptilonorhynchus violaceus) from New South 

 Wales, eight received in exchange, and two deposited ; an 

 African Wild Ass {Equus tceniopus) born in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



American Observatories. — It is reported that the Dear- 

 born Observatory of the Chicago Astronomical Society is to be 

 removed to Evanston, 111., the North- Western University at 

 Evanston having made an advantageous offer with respect to it. 

 A large astronomical Observatory is proposed to be erected in 

 connection with the Lake Forest University, Governor Ross, 



