704 



NATURE 



[February 26, 1920 



The scientific portion of the Central Zeitung fiir 

 Optik und Meckanik for January i contains the first 

 of a series of articles by Prof, von Rohr on the 

 principal points of optical systems and the graphical 

 methods of determining images. The constructions 

 given are those suitable for convex and concave 

 systems of which the principal planes and foci are 

 given. The industrial portion includes a reproduc- 

 tion of the new regulations under which optical 

 workers of eight years' standing may attend shortened 

 courses of instruction at the Government optical 

 school at Jena and, after a qualifying examjnation, 

 obtain the optician's diploma. A list of the optical 

 and other instruments for which there is at present 

 a demand in foreign countries is given. The wages 

 paid to the various grades of workers in metal in 

 the principal countries of the world form the subject 

 of a further article. .V list of the publications of the 

 German Committee on Standards for Industry is pro- 

 vided,, and the importance of the rapid adoption of 

 the new standards throughout the countrv is em- 

 phasised. Coloured wall-charts have been prepared, 

 so that the information may readily be placed before 

 the eyes of designers, foremen, and workmen. 



In a paper in the Chemical Age of February 14 

 Dr. Stephen Miall plots the atomic weights of the 

 elements against their atomic numbers, and shows 

 that all the elements lie upon a series of parallel 

 lines of three different slopes. The atomic weights 

 may be represented as hx + a, where x is the atomic 

 number, a a small integer ranging from o to 5, and 

 b has the value 2 for the elements from helium to 

 nickel, 25 from copper to tungsten, and 3 from 

 osmium to uranium. The first term, which con- 

 tributes to the chemical character, he terms "live- 

 weight," and the second term, which is of no influence 

 on the chemical character, "dead-weight." Similar 

 regularities have been previously pointed out, and, 

 indeed, since the atomic weights for the most part 

 conform to integral values, some such relation as the 

 above is necessarily true. But the diagrams have a 

 value apart from their interpretation. They suggest 

 a novel basis for classification, and arrange the 

 elements on parallel lines for which a and b have the 

 same values. They may be useful to those seeking 

 for regularities in the nuclear structure rather than 

 in the atomic shell. Hitherto chemists have been too 

 exclusively obsessed with the study of chemical 

 character to the neglect of the atomic weight—an 

 independent variable, as the studv of radio-active 

 change has made quite clear. The atomic weights, 

 however, as the author remarks, mean something. 

 They furnish the only present clue to the structure of 

 the nucleus. 



The Carnegie Institution of Washington has issued 

 another section of its monumental " Index of 

 Economic Material in Documents of the States of 

 the United States." The section, prepared by .Adelaid'^ 

 R. Hasse, is the first instalment of the index relating 

 to the State of Pennsylvania. Part i. contains the 

 titles of collected documents, mainly printed by 

 authority of the Senate and of the House of Repre- 

 sentatives. Part ii. is a topical analysis arranged 

 NO. 2626, VOL. 104] 



alphabetically from A to E. .Among the longer sec- 

 tions we find Agriculture, ("anals. Climate, Coals, 

 Coal-mining, and Education. The period covered is 

 from 1790 to 1904. The new volume has been pre- 

 ceded by twelve similar quarto volumes, and will be 

 followed by others, each devoted to a single State. 

 The index undertakes to deal only with the printed 

 reports of administrative officers, legislative com- 

 mittees, and special commissions of the States, and also 

 with Governors' messages. References are given by 

 volume and page to all material of economic import- 

 ance contained in the reports and messages indexed. 

 Under each sub-heading the arrangement is chrono- 

 logical. In the alphabetical part the compiler has 

 introduced, in addition to subject entries, the names of 

 persons who have exercised an important influence 

 on the development of the economic life of the State. 

 .Vfter each name there is reference to work done. 

 The amount of material which had to be examined 

 for the ])reparation of this volume must have been 

 very great. 



A SHORT but useful list of books on ornithology and 

 oologv (No. 3q8) has just been circulated by Mr. F. 

 Edwards, 83 High Street, Marylebone, W. i. It con- 

 tains some two hundred and fifty items, including^ 

 several long runs of serials such as the Ibis, 

 Transactions and Journals of the Royal Microscopical 

 Societv of London, Proceedings of the Zoological 

 Societv of London, etc. The list is sent free on 

 application. 



OUR ASTRONOMICAL COLUMN. 



Holmes's Comet. — Dr. Schorr reports that the 

 comctarv object 1919^ found on two plates t;dven at 

 Bergedorf by Dr. Baade on December 10, is de- 

 finitely not identical with Holmes's comet, as it failed 

 to appear on two plates taken on December 26, orr 

 which it would have been registered if it were moving 

 in accord with the ephemeris calculated for that 

 comet. 



Minor Planet GM. — This is the object discovered 

 bv Senor Comas .Sola on January 13, and considered 

 for a time to be a comet. .\s it is the brightest minor 

 planet discovered in recent years, it is of interest to 

 £?ive the elements which have been deduced at the 

 Observatory, California. 



T= 1920 March i6'36 G.M.T. 



o) =194° 28'1 



Berkelev 



j:! = 3oo^ oj- 1 920-0 



t = 17° 59'i 

 g =2326 

 e =o'iio9 

 Period = 4 23 1 5 years 



Mag. 



February 28 

 March 7 



Nova in Lyra.- 



Kphemcris for Greenwich Midnight. 



R.A. N. Detl. 



h. m. «. „ . 



.. 7 25 2r) 17 33 II 



•• 7 24 .54 16 44 



-Harvard Bulletin No. 705 reports 

 the finding of another nova on the Harvard photo- 

 graphs bv Miss Mackie. Position for 19000, K..\. 

 i8h. 49m. 3CS., N. decl. 29° 63'. Between Decem- 

 IxT 4 and 6 it rose suddenlv from mag. 16 or fainter 

 to mag 6-5; on January 6 it had sunk to 85. Messrs. 

 .Adams and Joy report from Mount Wilson that its 

 spectrum shows the striking nova characteristics. 



