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NATURE 



[June 15, 1916 



Although figures of equilibrium of rotating liquids 

 have already been fairly thoroughly studied by the 

 late Sir George H. Darwin and others, a fresh method 

 of approximate solution of the problem, by Prof. A. 

 LiapounofT, appears in the Bulletin of the Petrograd 

 Imperial Academy of Sciences, vi. (April 15). The 

 principal feature of this method is that, after obtain- 

 ing an equation which is not in itself soluble, the 

 author substitutes an approximate formula, which may 

 be taken as equivalent to the previous one to a 

 sufficient degree of accuracy within the limits involved 

 in the calculation and overcomes the mathematical 

 difficulties. 



The May issue of Section A of the Proceedings of the 

 Royal Irish Academy contains three papers by Prof. 

 McClelland and his assistants which deal with 

 methods of production and detection of ions in the 

 atmosphere. In the first of the series it is shown 

 that leaves exposed to the ultra-violet light of an 

 electric spark between aluminium electrodes show the 

 photoelectric effect to an extent which in some cases 

 is a tenth of that shown in the same circumstances 

 by copper. A cold-water extract from the leaves may 

 show an activity a third of that of copper, while an 

 acetone extract shows no activity. A few drops of the 

 acetone solution will, however, render a large volume 

 of water strongly active. The other papers relate to 

 the ions produced when water is sprayed into air or 

 air bubbled through mercury. In both cases the 

 saturation curves of the air show that there are four 

 or five kinds of ions present in it with mobilities which 

 vary from those of the large Langevin ions to those 

 of the ordinary small ions, while there appear to be 

 present in addition at least two types of ions with 

 still greater mobilities. 



A VERY timely and valuable essay on " Zinc, its 

 Production and Industrial Applications," by Mr. J. C. 

 Moulden, was recently read in abstract at a meeting 

 of the Royal Society of Arts. This essay was the re- 

 sult of a prize founded by Mr. Reginald Le Neve 

 Foster in memory of his father, a former secretary 

 of the society from 1853 to 1879, the subject being 

 determined by the council. The publication is one 

 of considerable length, and extends over two weekly 

 issues of the society's journal. It opens with an 

 account of the physical and chemical properties of the 

 metal, and then passes to a consideration of its his- 

 tory, from which it appears that although it played no 

 part of any importance in the economics of the 

 ancients it was known to them both as the metal and 

 in the form of alloys. The first zinc smelting works 

 were established in this country at Bristol in 1743 

 by John Champion. He also secured a patent in 

 1758 for the winning of brass and zinc from blende 

 as a substitute for calamine, which hitherto had 

 been the sole source of the metal. Succeeding sec- 

 tions deal with zinc ores, their nature, occurrence, 

 and distribution, and the metallurgy of the metal. 

 The essay should be of great service, appearing, as it 

 does, at a time when the possibility of establishing 

 a great zinc industry in this country is being care- 

 fully considered. 



The U.S. Bureau of Standards has recently issued 

 a circular (No. 58) entitled " Invar and Related 

 Nickel Steels," which is mainly a compilation from 

 sources, many of them inaccessible, as to the pro- 

 perties of nickel steels, with particular reference to 

 the properties of the non-expanding alloy known as 

 "invar." This should prove to be an exceedingly 

 useful publication. After a brief historical introduc- 

 tion the following properties receive attention : 

 (a) Reversible and irreversible nickel steels, their 

 equilibrium diagram, microstructure, and constitu- 



NO. 2433, VOL. 97] 



tion. (fc) Magnetic properties, (c) Electrical proper- 

 ties, (d) Thermal expansion, (e) Transitory length 

 variations following temperature changes. (/) Per- 

 manent changes in length at constant temperature. 

 (^) Elongation of invar with time. {Iri) Rapidity of 

 invar transformations, (i) Effect of composition on 

 instability. (;) Reproducibility of properties of invar, 

 (fe) Density. (Z) Mechanical properties, (tn) Resist- 

 ance to corrosion, (n) Applications, sources of supply, 

 and bibliography. The knowledge of ferro-nickels 

 goes back to the year 1822, when Stodart and Fara- 

 day published a paper. It was in 1889 that James 

 Riley, of Glasgow, described, before the Iron and 

 Steel Institute, his epoch-making investigation which 

 disclosed the remarkable mechanical properties of 

 nickel steels. His alloys contained various amounts 

 of nickel up to 49 per cent., which had been prepared 

 for him in France by Marbeau. The above circular 

 may be obtained free by addressing a request to the 

 Bureau of Standards. 



OVR ASTRONOMICAL COLUMN. 



Comet 1916b (Wolf).- — The following ephemeris is 

 a continuation of that given in Nature of June i for 

 Greenwich midnight : — 



R.A. Decl 



h. Ml. s. „ , 



Correction. — The comet's distance on July 3 will be 

 400 million miles, i.e. ten times the figures given by 

 error in the note referred to above. 



The Solar Activity. — Another very large, active, 

 spot disturbance has appeared. The following spot 

 has developed considerably since Monday. The larger 

 spot has been seen with ease, using a small glass 

 magnifying five times. Extremely bright faculae have 

 been noticed (June 13) on the eastern limb. 



The New Draper Catalogue. — ^The seventieth 

 annual report of the Harvard Observatory contains 

 the extremely interesting announcement that the first 

 step in the formation of the monumental New Draper 

 Catalogue — the classification of the stellar spectra — 

 has been completed. The number of spectra classified 

 is 233,050, covering the entire sky from the North 

 Pole to the South. 



The Spectrum of Coronium. — The new red line in 

 the spectrum of the corona, shown by M. Carrasco 

 to be a member of the same series as A 5303-3, has 

 enabled Prof. Nicholson to extend his analysis of the 

 coronal spectrum to include the six outstanding lines, 

 whence the conclusion is arrived at that the Coronium 

 atom is a simple-ring system with nucleus ye. When 

 it has eight electrons or a single negative charge it 

 emits the lines AA 6374-5, 5303-3. 4566-0, 4359-0, 3642-5, 

 and 3534-0. The lines in the spectra of neutral or of 

 positively charged atoms are found to be situated too 

 far in the ultra-violet for observation (No. 5, Monthly 

 Notices, Royal Astronomical Society). 



The Visibility of Stars in Daylight. — M. 

 Bigourdan's researches in the history of astronomy 

 have brought to light some interesting facts concern- 

 ing early modern observations of stars in da5'light 

 {Comptes rendus, No. 22). The earliest record ap- 

 pears to be a note found by Zach among the papers 

 of J. Gaultier, stating that the latter at Aix-en-Provence 

 observed Mercury on March i, 1611, at 6h. 30m. a.m. 

 - — the sun would then be above the horizon. The day- 

 light observation of stars proper appears to date from_ 

 May 2, 1632, when W. Schickhard first saw Regulus. 



