22 



NATURE 



[March 2, 191 1 



In the February number of rdcrmanns Mitteilungen, 

 with which Globus is now incorporated, Dr, V. Paschinger 

 discusses the results of an investigation of the snowline in 

 different regions. The present article is but a summary, 

 since the full discussion is to be published later, but the 

 main results are here given. The principal determining 

 factor he considers to be temperature, except in regions 

 where the snowfall is exceptionally heavy, when precipita- 

 tion is more influential climatically. For a certain 

 number of places he has been able to compare the position 

 of the snowline in different years, and finds that generally 

 in the northern hemisphere at the beginning of the 'seventies 

 it occupied a position of minimum altitude, and has reached 

 a maximum level since 1890. 



The results of Dr. K. Sapper's journey in the island of 

 South Mecklenburg of the Bismarck Archipelago, under- 

 taken in 1908 for the German Colonial Office, are pub- 

 lished in the third Erganzungsheft of the Mifteilungen aus 

 den deutschen Schutzgebieten. The topography and 

 physical conditions of the island and others near it were 

 principally studied, but the climate, the densely wooded 

 nature of the region, and the short time available only 

 admitted of a rapid reconnaissance, while the botany and 

 zoology could be scarcely attempted. Using the charts of 

 the German Admiralty as a basis, compass and aneroid 

 were used to determine the land features, which are given 

 in orographically coloured maps ; but these, for the above 

 reasons, can only represent the general relief of the island 

 without claiming accuracy of detail. Geological investiga- 

 tion was rendered difificult by the vegetation, and gravel in 

 the stream-beds furnished specimens of rocks which were 

 not otherwise met with. Oligocene limestones and glauco- 

 nitic sandstones were found ; but. most of the sedimentary 

 rocks, consisting of sandstones, limestones, tuffs, and clays, 

 are considered to be Pleistocene. Diorite, syenite, gabbro, 

 and granite were met with, but a far larger area is 

 occupied by the younger eruptive rocks, principally 

 andesite. 



In Nature, vol. Ixxix., p. 234, M. Paul Macey's descrip- 

 tions of subterranean waterways in Indo-China were re- 

 ferred to. He now supplements his paper in Spelunca by 

 an illustrated account of the " Tunnels naturels du Laos " 

 in La Nature, 191 1, p. 102. We are surprised that he 

 gives no reference to his previous paper, where his adven- 

 tures and explorations underground were described so 

 cheerfully. 



Herr H. Habenicht, of Gotha, has circulated a pamph- 

 let, " als Manuskript gedruckt," entitled " Spuren der 

 Eiszeiten in Norddeutschland und Versuch ihrer Deutung " 

 (Gotha : Andreas Perthes, 1910). It is accompanied by an 

 excellent map in colours. The author directs attention to 

 the absence of true terminal moraines along the margin 

 of the northern glacial drift in its most southerly extension. 

 The deposits in this region, unlike such moraines, show 

 curved forms that are convex towards the north, while 

 their terminations reach down into the valleys that notch 

 the Thijringian, Saxon, and Sudetic border. The author 

 believes that the facts require the occurrence of a great 

 flood between two ice-ages, whereby the deposits of the 

 older ice-age were swept into their present pwDsitions against 

 the southern hills. An interglacial diluvium was thus de- 

 posited ; but an older one also exists. Loess was formed 

 in pre-glacial times during an epoch of continental eleva- 

 tion, and of consequent dryness through remoteness from 

 the sea. A catastrophic falling in of the surface swept the 

 sea water over this, and led to the formation of an old 

 diluvium. Then followed the first ice-invasion, a second 

 NO. 2157, VOL. 86] 



uplift and a steppe epoch, and a second general sinking 

 and " Sturmflut des \Veltmeere<!" The consequent rains 

 brought on the second ice-age, when the glaciers only 

 reached the Baltic region. The mixture of the remain*; of 

 Arctic and tropical or steppe animals is attributed to fl<< mI- 

 action. It is clear that Buckland's early views have lived 

 on, in spite of the conversion of their author. 



■.i- 

 In a paper contributed to the Spanish Institute of Gil I 



Engineers (Barcelona : Guinart et Pujolar), Dr. PauUi 1 

 Castells Vidal describes an ingenious balance for findii [ 

 the real roots of an algebraic or similar equation. Tli 1 

 apparatus consists of a horizontal shaft on which a 1 

 attached cams in the form of equiangular spirals or similj ' 

 curves, from which may be suspended weights represeil ' 

 ing the coefficients of powers of x in an algebraic equa- 

 tion ; on the other hand, the arms of the levers formed ■<\ 

 the cams are for difterent values of the angular coordii ,i:' 

 proportional to the values of i, x, x^, for different v;il : - 

 of X. Consequently, when the apparatus has come i; lu 

 a position of equilibrium, the pointer attached to the s!. fi 

 at once gives a real root of an algebraic equation 'iu 

 coefficients of which are the weights of the loads suspend d 

 from the cams. 



We have received the reprint of a paper, by Mr. t \ ;il 

 F. Lan-Davis, read before the Optical Society last 

 December, and reprinted from The Optician and Photo- 

 graphic Trade Journal, dealing with the theory of the iris 

 diaphragm. Hitherto these useful optical accessories have 

 been mainly designed by trial, with the result that in many 

 cases it has been stated to be impossible to give sufficiently 

 large ranges of aperture for the requirements of modern 

 lenses and their fittings. The author now shows how the 

 problem can be treated by the methods of elementary 

 geometry, and the conditions for maximum range of 

 aperture, as well as for other impor*;ant requisites, such 

 as a long scale with equal divisions, can be made the 

 subjects of exact calculation. Neglecting the dimensions 

 of the pins which carry the leaves, it is shown that the 

 maximum aperture obtainable is 0-823 ^^ the diameter of 

 the diaphragm itself, and that for this twenty-five leaves 

 are required. This is a good example of a problem where 

 a little mathematics may save a great deal of random 

 experimenting. : 



Intending purchasers of microscopes and microscopic 

 apparatus will be well advised to consult the list issued 

 by Messrs. R. Winkel, of Gottingen, obtainable from their 

 London agents, Messrs. H. F. Angus and Co., 83 Wig- 

 more Street. Attention is specially directed to the micro- 

 scope stand No. id, the fluoride objectives that originated 

 in Gottingen, and an excellent series of complanatic eye- 

 pieces giving a particularly flat field. The general 

 workmanship and finish compare favourably with those of 

 other leading makers. The object marker is a new piece 

 of apparatus similar in shape to an objective, and in place 

 of which it is inserted, for marking a circle round any 

 desired spot on a slide. The type supplied for marking 

 covered objects is provided with a diamond point set in 

 a mount that can be rotated. 



In the September (1910) number of the Journal of the 

 Franklin Institute, Philadelphia, Mr. J. H. Dellinger, of 

 the Bureau of Standards, made a preliminary announce- 

 ment of an interesting relation he had discovered between 

 the electrical resistivity, the coefficient of increase of the 

 resistivity with temperature, and the density of specimens 

 of copper of all makes submitted to the bureau for test. 

 According to Mr. Dellinger, the product of the threea 

 quantities mentioned is constant for all specimens of copper 



