;26 



NATURE 



[August 24, 19 16 



function of supplying visual purple to the cones, and 

 thus increasing the sensitiveness of the latter to the 

 light. The movement seen on gazing at the rotating 

 cylinder is due to currents of photo-chemical liquid 

 (visual purple) flowing towards the fovea in order to 

 sensitise it. 



In Memoirs of the Geological Survey of New South 

 Wales, Ethnological Series, No. 2, Mr. Etheridge, 

 curator of the Australian Museum, Sydney, discusses 

 the remarkable cylindro-conical and cornute stones 

 found in the valley of the Darling. All kinds of ex- 

 planations of their use have been given, some utilita- 

 rian, as, for instance, that they were employed as 

 grinders, tombstones, records of the dead, challenge 

 stones, or hora message stones; others magical, as used 

 in rain-making and snake-producing, as death bone 

 pointers, and so on. On the whole, it seems clear that 

 they were used by the aborigines for some magical pur- 

 pose, which may have varied among the different groups 

 which possessed them. But the balance of evidence 

 indicates that they were of a phallic type, and that 

 they were used in some form of fertility rites. 



Calcium carbonate in its crystalline forms gains 

 further interest from a paper by Messrs. J. Johnston, 

 H. E. Merwin, and E. D. Williamson {Amer. Journ. 

 Set., vol. xli., 1916, p. 473). It is shown that the 

 presence of calcium sulphate determines the precipi- 

 tation of aragonite, a small quantity of the sulphate 

 becoming associated in solid solution in the crystals. 

 Aragonite has been thus obtained at as low a tempera- 

 ture as 19°. A form styled // — CaCO,, in scales and 

 hexagonal plates, has been obtained under conditions 

 which are not fully determined. It has refractive 

 indices between 1*550 and 1650, a density of 2'54, and 

 is unstable in the presence of nuclei of calcite or ara- 

 gonite, which are less soluble. This form behaves like 

 aragonite with Meigen's test. Useful warnings are 

 given as to the use of this test in the case of 

 mixed , materials. Calcium carbonate hexahydrate 

 (CaC03.6H20) is precipitated as monocHnic crystals 

 at temperatures below about 20° ; it can be preserved 

 for months in isolated crystals in clove oil as a micro- 

 scope preparation, but it changes rapidly at ordinary 

 room temperature into calcite and water. The natural 

 forms are carefully considered, and it is suggested 

 that the preservation of aragonite in any but recent 

 geological formations may depend upon its having 

 been kept dry. It may be mentioned that this agrees 

 with the observations of Horwood, Cole, and Little, 

 who show that geologically old aragonite shells are 

 -preserved in clays rather than in limestones. 



"The Data of Geoch'^mistry," by Mr. F. W. Clarke 

 (U.S. Geological Survey, Bull. 616, 1916) now appears 

 in its third edition, enlarged by some fort}- pages. The 

 guarded discussion of Brun's results on volcanic gases 

 in the edition of 191 1 here receives important modifi- 

 cations ; additional references are given to the prob- 

 lems of radio-activity ; and even in the treatment of 

 the deposition of carbonates by organisms new ob- 

 servations have been noted. It is remarkable how this 

 book, embodying an enormous range of facts, and 

 without a single illustration, retains its philosophic 

 character and is readable throughout. We turn to it 

 from the ordinary manual of petrography as we might 

 turn from a stained-glass window to a conference with 

 the cathedral founders. 



The peridotite with rhombic pyroxene that traverses 

 gneiss in the Sierra de Ronda in Malaya proves to be 

 the source of platinum in the sandy alluvium of the 

 streams. This occurrence is contrasted by 'MM. L. 

 Duparc and A. Grosset (M^m. Soc. de physique et 



NO. 2443, VOL. 97] 



d'hist. nat. de Geneve, vol. xxxviii, 1916, p. 253) with 

 the platiniferous dunite of Tagilsk in the Urals; the 

 parent rock and its products of weathering are shown 

 to resemble far more closely those of Khrebet Salatim, 

 which lie farther north on the east flank of the Urals, 

 and were discovered by M. Duparc in 1907. Maps 

 are given of these three localities ; the numerous small 

 landscapes from the Ronda district have no great 

 geological interest. 



A VERY interesting and important paper by P. H. 

 Galle on the relation between fluctuations in the 

 strength of the trade winds of the North Atlant-c 

 Ocean in summer and departures from the normal of 

 the winter temperature in Europe appears in a 

 recent issue of the Proceedings of the Amsterdam 

 Royal Academy of Sciences. In a previous paper the 

 author had shown that variations in the strength of 

 the trade winds (15^-25° N., long. 25°-45° W.) were 

 apparent two or three months later in some hvdro- 

 graphical phenomena in northern Europe. The subse- 

 quent variations in winter temperature have now been 

 investigated. From an exhaustive comparison of vari- 

 ous groups of months for the period 1899— 1914 for 

 combinations of five Dutch , stations, three German 

 stations, and three in the Far North-west, it was found 

 that the largest correlation was obtained between the 

 fluctuations of the trade wind for the six months May 

 to October on one hand, and those in the tern- 

 p>erature for the three winter months December to 

 F"ebruary following, on the other. The results, based 

 on values computed for 135 stations, are graphically 

 shown by iso-correlational lines on two charts which 

 apply to the trade winds of May to October and of June 

 to November respectively. P'or the first period the 

 maximum positive value of r, o~o, is obtained in East 

 Germany, the largest negative, o'6o, in North Iceland 

 and East Greenland. The largest correlation factor 

 for any period was found in that part of Germany 

 embracing the stations Berlin, Gorlitz, Posen, and 

 Ratibor, where the relation between the strength of 

 the trade winds over the months June to November 

 and the following winter temperature gave r = o'85 

 and /=o'04. By this method a successful prediction 

 was made of the temperature over north-western 

 Europe last winter. 



The Meteorological Office has issued a chart dealing 

 with temperature scales which is evidentlv intended 

 for the use of meteorological observers, but might with 

 great advantage be suspended in every physical labora- 

 tory in the country. On the left-hand side of the 

 chart the absolute, the Centigrade, and the Fahrenheit 

 scales of temperature are drawn alongside each other 

 from the absolute zero to 1500° A. of the absolute 

 scale, the divisions being at 10° intervals on the abso- 

 lute and Centigrade, and at 20° intervals on the 

 Fahrenheit scale. A number of important thermo- 

 metric points are indicated on the absolute scale, e.g. 

 4° A. helium boils ; 43° A. oxygen melts ; 90° A. oxygen 

 boils; 234° A. mercury melts; 37265° A. water boils 

 under one-bar pressure; 505° A. tin melts; 717° A. 

 sulphur boils ; 800° A. bodies just red-hot, etc. On 

 the right-hand side of the chart the three scales, from 

 180° to 330° on the absolute scale, are drawn together, 

 the divisions on the absolute and Centigrade scales being 

 one, and those on the Fahrenheit scale two degrees 

 apart. A number of important meteorological tem- 

 peratures are indicated — e.g. 219° A. the mean tem- 

 perature of the stratosphere over England, 246° A. the 

 lowest, and 311° A. the highest, temperature observed 

 in the British Isles, etc. The strength of the solar 

 heat stream is gi\-en as 135 milliwatts per sq. cm., but 

 there is no indication as to where it has this particular 

 strength. 



