May 2, 1918] 



NATURE 



The electromotive force of the cell is 118 volts, and a 

 coll giving 90 ampere-hours weighs only 21 kilograms. 



The work begun by Pollok and Leonard in 1905, on 



liie speotrographic determination of metallic elernents 



when present in solution in small quantities, has lately 



been extended to lithium, rubidium, caesium, and gold 



by Messrs. A. G. G. Leonard and P. Whelan. The 



results are stated in a paper which appears in the 



scientific Proceedings of the Royal Dublin Society, 



>!. XV. (N.S.), No. 25. In each case solutions of 



irious strengths down to 0001 per cent, were 



Kcimined, and the tables sihow the relative persistency 



t the various lines as the concentration was 



iininished, thus providing a basis for quantitative 



lalysis. Lithium and caesium could be detected in 



001 per cent, solutions, but rubidium and gold 



lowed no lines in solutions of strength less than 



I per cent. Some of the photographs are re^ro- 



iLiced, but, in the absence of a scale, comparison with 



die tables is somewhat difficult. A line at 2478 in the 



-pcctra of metallic lithium and rubidium, which the 



iithors were unable to identify, was probably due to 



11 impurity -of carbon. 



We have examined a new astronomical model de- 

 siijned for use in schools and colleges by Dr. William 

 Wilson. Those wiho sa\y the model at the Royal 

 Astronomical Society last year must have been struck 

 l>y its educational value, and will welcome the an- 

 )uncement that copies of it are to be placed on the 

 larket after the war, the matter of price being left 

 r determination later. The model represents, with 

 irect relative angular velocities and axial poses, the 

 lational and revolutionary movements of sun, earth, 

 iid moon, and the changes in the moon's Oibit plane. 

 (Jlockwork and cog-wheels are not employed, the 

 movements feeing effected by taut endless strings pass- 

 ing over pulleys; each string has a tension regulator, 

 r.isilv adjusted 'to give the necessary tension. By 

 slackening some of the tensions the corresponding 

 iMvements are put out of action, so that the student 

 ill study simple cases, such as a planet revolving 

 s\ iihout rotation or a moon moving in the same plane 

 as its primary. Fine adjustments are obtainable by 

 >light alteration of the distance between the two half- 

 liscs into which the pulleys are divided; thus the 

 Mvere test of the Saros eclipse cycle of 18 years 11 days 

 was shown to be satisfied within a very small quantity ; 

 the machine is not a mere toy, tout is capable of 

 Jving graphical solutions of problems. The phases 

 ii the moon are shown by covering half of the white 

 lunar globe by a black cap, which always keeps on 

 ilic side opposite to the sun. Cones of different lengths 

 can also W' put on the moon to represent its shadow, 

 and the production of total or annular solar eclipses. 

 As Prof. Eddington has pointed out, the chief difficulty 

 ' xperienced by astronomical students is generally that 

 of picturing relations that cannot be represented on a 

 plane surface, but involve three dimensions.' For such 

 the model should prove very helpful. Full particulars 

 of the model are given in an illustrated pamphlet to 

 !>.! obtained (post free 6d.) from Dr. Wilson, 43 Fellows 

 Road, London, N.W.3. 



We have received a copy of a recent publication of 

 the United States Bureau of Standards (Circular 67), 

 entitled "Combined Table of Sizes in the Principal 

 Wire Gages." This table includes the numbers and 

 sizes in the following- systems of wire gauges : Ameri- 

 can B. and S. (Brown and Sharpe), Steel (Stl.W.G.— 

 known under the various names "Washburn and 

 Moen," "Roebling," "American Steel and Wire 

 Co."), Birmingham (Stubs'), British legal standard, 

 and Metric. It gives the diameters of all the gauge 



NO. 2531, VOL. lOl] 



numbers in these five systems in mils, inches, and 

 milhmetres, also the cross-sections in square mils, 

 circular mils, square inches, and square millimetres. 

 Ihe table will probably be found useful by manufac- 

 turers who wish to determine the nearest equivalent in 

 American or British sizes of wires, specified in milli- 

 metres or square millimetres, or vice versa. It should 

 be noticed that the Stubs' Birmingham gauge is not 

 the same as the series of sizes legalised in the United 

 Kingdom in 1914 under the denomination " Birming- 

 ham gauge (B.G.)." The latter system is p.-aoticallv 

 identical with the series of numbers and sizes issued 

 by the South Staffordshire Ironmasters' Association 

 in 1884, and is chiefly used for sheet and hoop iron 

 and steel; but it is quite different from the legal 

 American system ("Standard Gage for Sheet and 

 Plate Iron and Steel," Bureau Circular No. 18). 

 It is an excellent idea to issue in a handy 

 form lists of the principal wire-gauge systems of 

 America and the United Kingdom, and this table is 

 likely to havw a wide sphere of utility. A copy may be 

 obtained on application to the Bureau of Standards, 

 Washington, D.C., U.S.A. 



The tendency to utilise drop stampings has become 

 very marked in recent years, and the advantages of 

 these substitutes for forgings and castings have led 

 to considerable developments in connection with muni- 

 tions. Of the two chief methods of lifting the stamp 

 steam is the older, but friction lifting is becoming 

 more popular. Until recently the heaviest weight of 

 tup and die dealt with by friction was about five tons, 

 of which the tup weighed four tons. Messrs. B. and 

 S. Massey, of Manchester, have now ibuilt two stamps 

 capable of dealing with weights up to 95 tons, and 

 these machines form the subject of an illustrated 

 article in the Engineer for April 19. The stroke of 

 the itup is 7 ft., and the lifting speed is 320 ft. per 

 minute. Power is supplied by a 200-h.p. electric motor. 

 The lifting mechanism consists essentially of a heavy 

 clutch operated through a light relay clutch. The 

 connection between the lifter and tup is made with 

 strong woven belting 15 in. wide. When the tup is 

 held suspended, the power delivered by the motor is 

 dissipated in work done against friction and converted 

 into heat; hence the necessity arises for cooling the 

 clutch by circulating w^ater, which in these machines 

 is maintained in circulation by means of a pump. 



Among the announcements of forthcoming books of 

 science we notice tjhe following: — "Tidal Lands: A 

 Study of Shore Problems," A. E. Carev and Prof. 

 F. W. Oliver {Blackie and Son, Ltd.) ; "The Produc- 

 tion and Treatment of Vegetable Oils," T. W. 

 Chalmers, and a new edition of " Industrial Elec- 

 trical Measuring Instruments," K. Edgecumbe {Con- 

 stable and Co., Ltd.); "Modern Engineering Measur- 

 ing Tools," E. Pull, " Military Observation Balloons," 

 E. J. Widnor, and " Seasoning of Wood : A Treatise 

 on the Natural and .'\rtificial Processes employed in 

 the Preparation of Lumber for Manufacture," J. B. 

 Wagner (Crosby Lockwood and Son); "Savage Sur- 

 vivals," J. Howard Moore, and a selection of the lec- 

 tures and essays of the late Prof. W. K. Clifford 

 (Watts and Co.). 



Messrs. Macmillan and Co.'s new list of forth- 

 coming books includes a new edition of "An Elemen- 

 tary Treatise on Curve Tracing," Dr. P. Frost, revised bv 

 Dr.R. J.T. Bell; "The Statesman's Year Book, 1918," 

 edited by Sir J. Scott Keltic, assisted by Dr. M. 

 Epstein; "The Military Map: Elements of Modern 

 Topography " (French School of War), complete in one 



