November 14, I'Qo;] 



NATURE 



4« 



Herbert Spenxer's claims as a mathematician form the 

 subject of discussion and criticism at the hands of Dr. 

 J. S. Mackay in the Proceedings of the Edinburgh Mathe- 

 matical Society (xxv.). The author, referring to the geo- 

 metrical theorems which Spencer claimed to have dis- 

 covered, shows that these were well known before 

 Spencer's time, and were not very clearly or lucidly 

 enunciated by Spencer himself. An account of Spencer's 

 views of antipathy towards the metric system and his 

 advocation of the duodecimal system are also given, but 

 his present critic considers that " his outfit of mathematical 

 (or indeed any other) knowledge was both slender and 

 scrappy." 



The occurrence of spinel in blast-furnace slags appears 

 to have been first determined in 1880 by Muirhead, who 

 found that highly aluminous slags left a proportion of 

 verv intractable residue, varying from 5 per cent, to 

 17J per cent, of the whole weight. This when analysed 

 proved to be spinel with about one-third of the magnesia 

 replaced by iron. .'\n interesting instance of the occurrence 

 of spinel in a Hungarian blast-furnace slag is recorded in 

 an abstract of a paper by Mr. J. Krenner in the October 

 issue of the Journal of the Chemical Society. In a white, 

 enamel-like slag obtained on smelting iron ores rich in 

 manganese, very hard brown octahedral crystals were 

 found. The analysis is in accord with the spinel formula ; 

 but this spinel contains more manganese than any artificial 

 or natural member of the spinel group hitherto analysed. 



Mr. G. H. Gulliver has contributed to the Proceedings 

 of the Institution of Mechanical Engineers (1907, pp. 519- 

 524) a paper on some phenomena of permanent deformation 

 of metals, the object of which is to correct a hypothesis 

 suggested in a previous paper in 1905 to explain the origin 

 of the " contractile cross." It was then suggested that 

 while the somewhat analogous " Liiders' lines " were due 

 to slipping of the elementary crystals within the crystal- 

 line grains of the metal, the contractile cross w'as the 

 result of the slipping of the irregular crystalline grains 

 themselves over each other. It is now established that 

 for aluminium, and probably for other ductile metals, the 

 phenomena of constriction and fracture are due to 

 excessive " slip-band " deformation, and that the contrac- 

 tile cross passes through the crystalline grains of the 

 metal. It is somewhat influenced by the degree of coarse- 

 ness of the crystalline structure, but is independent of the 

 directions of the boundaries of the crystalline grains. 



\ COMPREHENSIVE review of the design, construction, 

 and performance of the Cunard turbine-driven quadruple- 

 screw Atlantic liner yiaurcXania is given in Engineering 

 of November 8. The description is accompanied by 186 

 illustrations, many of which are two-page plates. A 

 similar description was recently published of the Lusitania. 

 The Mauretania and the Lusitania are sister-ships. They 

 are, however, the production of different firms, and differ 

 in numerous details, and particular attention is given in 

 the description to these variations. The Mauretania, 

 which has a length over all of 790 feet, a length between 

 perpendiculars of 760 feet, a breadth of 88 feet, a depth, 

 moulded, of 60 feet 6 inches, a gross tonnage of 32,000 

 tons, and a draught of 33 feet 6 inches, carries 563 first- 

 class passengers, 464 second-class, and 1138 third-class. 

 The average speed on the sea-going trial was 2603 knots 

 for 1200 miles. 



A SI.MPLE method of generating an alternating current of 

 any desired frequency is described by Dr. Rudenberg in 

 the Pliysikalische Zeitschrift for October 15. It consists 



NO. 19H5, VOL. 77] 



in placing a capacity, and if necessary an inductance, in 

 series with a series-wound dynamo, and running the 

 machine in the ordinary way. The frequency of the 

 current produced is determined by the capacity and in- 

 ductance of the circuit, while the power is derived from 

 the machine, which should have its field magnets lamin- 

 ated. A slight modification of the arrangement converts 

 it into a sensitive receiver for wireless telegraphy. 



The Verhandlungen der deutschen physikalischen Gesell- 

 schaft for September 30 contains an extensive study, by 

 Mr. L. W. Austin; of the conditions which influence the 

 production of rapid electrical oscillations by means of the 

 arc. He finds it possible to generate with carbon, or 

 better with graphite, electrodes currents having frequencies 

 of several hundred thousand per second, which, however, 

 are not sinusoidal. The frequency with a direct-current 

 arc increases with the current strength and with diminu- 

 tion of the arc length, but seems to be independent of the 

 intensity of the oscillations. The effect is greatly increased 

 by running the arc in hydrogen. The author recommends 

 for telegraphic work an arc between silver or copper 

 electrodes in air at about six atmospheres pressure, which 

 possesses many of the properties of a rapid spark dis- 

 charge, and allows a considerable resistance to be intro- 

 duced into the shunt circuit. 



An important contribution to the study of the chemical 

 changes occurring when air is submitted to the influence 

 of electricity is contained in a paper by E. Warburg and 

 G. Leithauser in the Annalen der Physik (vol. xxiii., 

 p. 210). It is shown that, contrary to the general opinion 

 held hitherto, nitrogen pentoxide is always formed as 

 well as ozone when air is subjected to the so-called 

 " silent " discharge. The action of ozone on nitrogen 

 pentoxide gives a strongly coloured gas " Y " having the 

 same absorption spectrum as the substance supposed by 

 Hautefeuille and Chappuis to be N,Os ; the amount of 

 " Y " formed is, however, always small in comparison 

 with the quantity of nitrogen pentoxide present, a fact 

 which makes it doubtful whether " Y " really has the 

 composition N,0, as first supposed, when the assumption 

 was made that it was the only oxide of nitrogen produced 

 by the discharge. Measurements are given of the absorp- 

 tion of light by the substance " Y " in the region of the 

 visible spectrum, and also of the absorption by nitrogen 

 pentoxide in the infra-red. The prominence of an absorp- 

 tion band at 5.75 /j. in the latter case affords a very delicate 

 means of detecting nitrogen pentoxide when present with 

 other oxides of nitrogen. 



The Industrial Society of Mulhouse has issued a pro- 

 gramme of prizes to be awarded by the society during the 

 year 1908. The subjects open for competition this year 

 remain practically the same as those for 1906, already 

 summarised in Nature (vol. Ixxiii., p. 164), but a few 

 minor alterations have been introduced. The programme 

 can be obtained on application to the secretary at 

 Mulhouse. 



Mr. Gustav Fischer, Jena, has just published the 

 fourth revised edition of Prof. W. Kukenthal's " Leitfaden 

 fur das zoologische Praktikum." A short section on 

 spiders has been added after the chapter on insects. The 

 character of the work was described in a review of the 

 second edition published in Nature of April 24, 1902 (vol. 

 Ixv., p. 581). 



The process of transmitting photographs by electricity 

 devised by Prof. Korn, of Munich, and described in 

 Nature of August 29 (vol. Ixxvi., p. 445), has been adopted 



