I r 4 



NATURE 



[September 26, 19 12 



113 of the map (price \s. 6d.). Both in the memoir 

 and in the section on the map, the position of the 

 concealed coalfield under Sherwood Forest is well 

 emphasised. Perhaps- in anticipation of the compre- 

 hensive publication that we expect from the Inter- 

 national Geological Congress of 1913, Mr. E. F. 

 Pittman has prepared a handy volume on "The Coal 

 Resources of New South Wales" (Geol. Surv., 

 X.S.W., 1912, price is.). 



The series of papers on the development of the 

 theories of mathematical logic and the principles of 

 mathematics, by Mr. P. E. B. Jourdain, appearing in 

 The Quarterly Journal of Pure and Applied Mathe- 

 matics, forms a useful contribution to mathematical 

 literature. The sections dealing with Leibniz and 

 Boole appeared some time ago, and we have now 

 received the part {Quarterly journal, No. 171, 1912) 

 dealing with the work of Hugh McColI (1837-1909), 

 Gottlob Frege (born 1848), and Giuseppe Peano. All 

 these sections have been revised, both by the respective 

 authors with whose work they deal and by Mr. 

 Bertrand Russell. 



A PAPER contributed to the Atti del Lincei, xxi. (2), 

 I, by Prof. S. Salaghi bears the title "On the vul- 

 garisation and application of mathematical physics in 

 medicine." It constitutes a plea for the application of 

 hydrodynamical principles to the study of the circulation 

 of the blood, the formulae for the purpose being the 

 ordinary equations of hydraulics applicable to the 

 motion of liquids in tubes, a subject which the author 

 claims to have introduced into Italy for the first time, 

 but which is now being investigated by Dr. Morandi 

 under the name hasmodynamics. 



A sM.Ai.L pamphlet on " Rubies," written by Mr. Noel 

 Heaton, has been issued by the Burma Ruby Mines, 

 Ltd. In the course of a few concise paragraphs, Mr. 

 Heaton explains how the natural ruby may be distin- 

 guished from other red gem-stones, and especially from 

 the reconstructed and synthetic rubies. The difference in 

 structure between the natural and the artificially pre- 

 pared stones is clearly brought out by some admirable 

 illustrations. The pamphlet will be found invaluable 

 bv jewellers and dealers in precious stones, to whom 

 of late vears the identification of rubies has been a 

 troublesome problem. The salient items of the pamph- 

 let are also reprinted in the form of a chart, which may 

 be framed and hung in a convenient position on a 

 wall. 



The Journal of the Institution of Electrical 

 Engineers for July contains a description of a portable 

 instrument for the detection of combustible gases and 

 vapours in air, devised by Messrs. A. Philip and 

 L. J. Steele. It depends on the possibility of causing 

 the gas or vapour to combine with the oxygen of the 

 air by bringing the mixture into contact with a 

 platinum spiral raised to the necessary temperature by 

 the passage of an electric current through it. The 

 combustion thus brought about produces heat which 

 raises the temperature of the platinum spiral still 

 further. The electric current passes through a second 

 spiral identical with the first, but protected from 

 contact with the mixture of gases. By combining the 

 NO. 2239, VOL. 90I 



two spirals in any of the well-known ways, the differ- 

 ence of their electrical resistances may be made to 

 indicate the presence of the combustion. In the in- 

 strument described, the spirals are in series with the 

 coils of a differential relay, and the redistribution of 

 current which results from the heating of one spiral 

 actuates the relay and a red lamp lights up. 



In the Chemical Society's Journal Prof. Pope and 

 Mr. C. S. Gibson give an account of their successful 

 resolution of sec-bitylamine, C„Hj.CH(NH J.CHj, a 

 simple substance which had resisted earlier attempts 

 to separate it into two optically-active isomerides. 

 Although the base behaves normally, and its hydro- 

 chloride is highly dispersive, a series of sulphonic 

 derivatives were found to produce practically constant 

 rotations in the yellow and green regions of the 

 spectrum. This absence of rotatory dispersion is very 

 exceptional, though some parallel is found in sub- 

 stances such as ethyl tartrate, which show a maximum 

 of specific rotatory power in the yellow or green region 

 of the spectrum. 



The current issue of Science Progress contains a 

 second article by Dr. Charles Walker on theories and 

 problems of cancer, and a long article by Dr. F. G. 

 Hopkins on Dr. Paw and diabetes. Prof. Love con- 

 tributes an article on tides and the rigidity of the 

 earth, and Mr. J. N. Worthington gives a critical 

 review of the possibilities and limitations of observa- 

 tions of the planet Mars, to be followed in a later 

 article bv an account of what these observations have 

 revealed. Chemists will welcome an extremely lucid 

 exposition, by Mr. F. W. Aston, of Sir J. J. Thom- 

 son's new method of cliemical analysis, which pre- 

 cedes a second article by Mr. D. L. Chapman on 

 conditions of chemical change. Dr. Desch contri- 

 butes an illustrated article on the structure of metals, 

 Mr. C. T. Gimingham discusses variations in pas- 

 tures, with special reference to the "fatting" and 

 " non-fatting " pastures of the Romney Marshes, and 

 the "teart" lands of Somersetshire, and Mr. Allan 

 Ferguson gives an historical account of the genesis 

 of logarithms. 



The latest addition to the handy little subject lists 

 issued by the Patent Office, London, W.C., is the 

 subject list of works on horology in th-- library of the 

 office. The list comprises works on the determination 

 and division of time, dialling, clocks, watches, and 

 other timekeepers. 



OUR ASTRONOMICAL COLUMN. 



Comet 19120 (Gale).. — From observations made on 

 September S, 11, and 15, Dr. Ebell has calculated a 

 set of elements and an ephemeris for comet 1912a. 

 The time of perihelion is given as October 4'7o88 

 (Berlin M.T.), and the following is an extract from 

 the ephemeris given in the Kiel Centralstelle Circular, 

 No. 135 :— 



Ephemeris I2?i. {Berlin M.T.) 



R.A. Decl. S. R.A. DecL.S. 



n. m. . , h. m. 



Sept. 27 



