April \% 1S75J 



NATURE 



467 



that the spot on which the celt was found should be within thirty be made simultaneously from La Villette gasworks, and 

 yards of the site of a Roman building dj^scovered by mejn 1864. the several tracks compared with each other. Some 



Gurnet Bay, April 9 



E. J. A'CouRT Smith 



Arctic Temperatures 



In your article on the Austrian Polar Expedition (vol. xi. 

 p. 397), it is stated that in January " the warm S. and S.W. 

 winds always brought great masses of snow, and produced a rise 

 in the temperature amounting to 30° — 35° R. in a few hours." 

 32 R. = 72 F. 



Such enormous fluctuations of temperature are unparalleled in 

 any other part of the world, and it seems quite impossible that 

 they can be due to any drift of warm air. I would suggest 

 that they are probably caused by the v.ind tearing up the 

 frozen surface of the sea, and liberating the heat of the unfrozen 

 water below. Dr. Kane, when wintering in Smith Sound, once 

 met with such a rise of temperature, and he says that open water 

 was near. This explanation of the phenomenon is supported by 

 the fact you mention in the same article, page 398, that in 

 the summer the temperature was remarkably constant. The same 

 cause could not act during summer, for the air is not then much 

 colder than the unfrozen water. 



There is no doubt of the power of a storm of %vind to tear up 

 a very thick sheet of ice. Joseph John Murphv 



Old Forge, Dunmurry, Co. Antrim, March 30 



AERONAUTICS 



M GASTON TISSANDIER has just finished the 

 • analysis of carbonic acid contained in the air col- 

 lected during his recent ascent (vol. xi. p. 429). He found 

 at Paris 37 cubic centimetres per 100,000 ; at a height of 

 2,700 feet, 27 ; and at a level of 3,300 feet, 30. The 

 difference of altitude between the two aerial stations 

 being too small to justify drawing any conclusions he 

 will shortly make another ascent with the sam.e balloon to 

 an altitude of 24,000 feet. 



M. Godard made an ascent in the balloon Saturn, from 

 Bayonne, on March 29, at half-past five, and was drifted 

 over the Pyrenees. The trip was difficult, as the balloon 

 was loaded with snow and hail, and all the ballast 

 w-as thrown over in order to keep the balloon afloat. 

 The cold was intense, and the wind very strong. The 

 landing took place at Azul Mayor, a small country 

 town east of Pampeluna, at half-past seven, the distance 

 run being 120 kilometres. The grapnel having been 

 broken, the aeronaut and the three passengers were 

 severely hurt. This is the first time that any balloon has 

 crossed the Pyrenees. The Sa/uni followed the French 

 valley of the Nive and the Spanish valley of Baztan on the 

 southern side. An interesting observation was made when 

 crossing the culminating point of the pass. The Larrate'ce 

 Neguya was surrounded by cirro-cumulus, which resisted 

 the force of the wind and seemed an obstruction in the 

 way of aeronauts, who found it necessary to throw out a 

 certain quantity of ballast, and to reach an altitude of 

 6,600 feet, in order to cross that sea of motionless clouds. 

 a' strong hissing noise was heard when travelling over 

 them ; whether it was produced by the friction of 

 the air on the peaks or on the masses of electrified 

 vapours, can only be decided by another experiment con- 

 ducted scientifically. 



On April 4 two ascents were made almost simul- 

 taneously. M. Triquet ascended from the Place du 

 Trone, Paris, and landed at Montreuil, 20 kilometers 

 from his starting-point, forty minutes afterwards, having 

 run in an E.S.E. direction. M. Duruof ascended from 

 Cahors, in the Lot, and landed at Catres, in the same 

 department, having run 22 kilometers in sixty-five minutes, 

 but in a N.N.W. direction. Both balloons having 

 ascended at the same moment, moved at right angles. 

 I have reason to believe that a number of ascents will 



interesting facts may be elicited by these comparative 

 trips. W. DE FONVIELLE 



ARCTIC GEOLOGY* 



II. 



Cryolite ef West Greenland Coast. — At Evigtok {ivik, 

 Eng. grass), twelve miles from Arksut (Eng. leeward), 

 in 61° 13' lat. and 48° 9' W. long., the mountains rise 

 to a height of more than 2,000 feet, enclosing a sort of 

 basin, with an area of more than a square mile, the 

 bottom of which is covered with grass and Salix 

 aretica, four feet in height, and other plants. This 

 is much freguentcd in summer by the Grecnlanders, 

 who catch large numbers of capelins and cod, which 

 frequent the coast in shoals, as well as the Sahno 

 arcturus, Linn, (the Lodde of the Norwegians). Weights 

 used in this fishery, taken by Danish missionaries to 

 Copenhagen at the beginning of the centur>', were found 

 to be composed of cryolite, which led to the discovery 

 of two veins of that mineral in the gneiss at the head 

 of the bay, which has since been worked by Mr. Tayler, 

 F.G.S. The white cryolite bed is about eighty feet in 

 width, dipping south with the planes of the gneiss in 

 which it occurs. Near its higher portion there is a 

 large quantity of galena, worked in 1854, which gave 

 82i per cent, of argentiferous lead, containing forty-five 

 ounces of silver to the ton of oie. Fifteen feet from 

 the surface the cryolite was of a dark colour, so that 

 it is probable that the black cryolite in the higher vein is 

 merely less decomposed, and not bleached. The Green- 

 landers value the white variety most, which they call 

 orksoksiksast {orso/c, blubber), from its soft greasy appear- 

 ance and feel ; they gradually pound tobacco leaves placed 

 between two pieces of it, the resultant powder consisting 

 of half of cryolite dust, which they consider superior to 

 any European snuff.f 



Large quantities of cryolite are now imported to Copen- 

 hagen, the mines being worked by Messrs. Thomsen, of 

 that city. Mr. Oualj e reports that pieces of gneiss and 

 trap are found imbedded in the cryolite, and states that 

 the mines are filled with snow and ice during the winter, 

 work being carried on by fifty men from May to October ; 

 5,000 tons are raised yearly. Cryolite, except at Miask, in 

 Siberia, does not occur out of Greenland. 



Crjolite is a fluoride of sodium and aluminium, and is 

 composed, according to Mr. Evan T. Ellis, of— 



13 per cent, of aluminium, 



34 » » sodium, 



53 J, J, fluorine. 

 In Denmark, it is largely used in the manufacture of 

 soda, which is procured by mixing it with lime and 

 applying heat, too tons of cr)olite yielding forty-four 

 of caustic soda. It was introduced into Philadelphia 

 by the Pennsylvania Salt Company, who imported 8,oqo 

 tons in 1867. By mixture with silica a very beautiful 

 glass is produced, capable of being moulded. Cryolite 

 was used by Deville as a flux in the manufacture of 

 aluminium, the process of extracting aluminium from 

 it was first used by Mr. Dick in 1856, but its use has since 

 been abandoned in favour of bauxite. The fluoride of 

 calcium is sent to Paris to be used in glass etching. 

 Associated with the Greenland cryolite brought over 



* Continued from p. 449. 



\ Giesecke, Edi-i. Pint. your. vol. vi. 1822 ; J, W. Tayler, Q:mr. your. 

 Ceol Soc. 1856; C/iemknl Nc-ms, i£68, p. E, &c. ; Procccdmgs Amer. 

 Pharm. Soc, 1868 See Rink's Memoir on Greenland, publi.-,hed by the 

 Koyal Danish Academy of Sciences, 1853, p. 71 ; L. Jacobsen's " Et Aar i 

 Gronland, 1862 " ; and Lieut. Bluhme, in the Danish magazine P'ra alle 

 Laude, vol. i. 



