January 13, 1910] 



NA TURE 



319 



the ions. The path may be deviated by means of a 

 magnet. When a point reaches an electrode it appears to 

 attach itself and take a crystalline form. None of these 

 appearances is observed in the case of a non-electrolyte, 

 and the author considers he has proved beyond the possi- 

 bility of doubt that the ultramicroscope provides a powerful 

 means of studying directly the motions of the ions in 

 electrolysis. 



A SEPARATE copy has reached us of Prof. Zceman's 

 paper on the degree of completeness of the circular polar- 

 isation of magnetically divided lines, which was com- 

 municated to the Academy of Science of Amsterdam on 

 October 30, 1909. It will be remembered that a luminous 

 gas in a strong magnetic field gives a spectrum which, 

 when viewed along the lines of the field, consists in the 

 simplest case of two lines, which according to Lorentz's 

 elementary theory of their production should be circularly 

 polarised, one right-, the other left-handed. On examina- 

 tion of lines which normal to the field become triplets, 

 quartets, sextetfc and nonets. Prof. Zeeman finds that in 

 each case, whether along the field a line becomes a doublet 

 or a quartet, the lines so produced are circularly polarised, 

 and the degree of circular polarisation found approaches 

 more and more to completeness as the intensity of the 

 light transmitted by the instrument increases. The orbits 

 of the electrons in planes perpendicular to the magnetic 

 field are therefore almost exactly circular. 



In an article in Engineering for December 31, 1909, on 

 the command of the air and its effect on land warfare, 

 some interesting points are dealt with. We may probably 

 quite disregard the idea of balloons being used to drop 

 bombs into towns for the sake of wantonly destroying 

 private property. There are other and more legitimate 

 ways in which the command of the air may probably be 

 the deciding factor in a war. There is the facility it gives 

 for ascertaining an enemy's disposition and movements, 

 and flying machines may be of great use in w^ar by acting 

 on an enemy's communications. There is no reason why 

 such machines should not start from a ship as well as on 

 land, and, if capable of fiying 300 miles, would have a 

 striking distance of 150 miles inland from an enemy's 

 coast. At present it looks as if the aeroplane rather than 

 the navigable balloon would become universal, owing to 

 its being faster, quicl^er at turning, harder to hit, and 

 very much cheaper. 



In an article on latter-day developments of the American 

 locomotive in the Engineering Magazine for December, 

 igog, Mr. H. Keith Trask deplores the fact that American 

 locomotive practice has followed rather than led European 

 practice in matters of design relating to increased efficiency 

 from the standpoint of economy. Thus European designers 

 had long considered the advantages offered by superlieated 

 steam before the question was seriously taken up in 

 America. Cheap .American fuel was responsible for this 

 neglect, but the recent developments of the compound 

 locomotive have rendered the American designers alive to 

 the benefits resulting from the use of superheated steam. 

 .As developed for use on American railroads, the super- 

 heater is of two types, the smoke-box and the fire-tube. 

 While both types were originally introduced several years 

 ago, it is only within the past twelve or eighteen months 

 that the American railroad world in general has awakened 

 to their possibilities, and they are being applied to many 

 new engines now building for various roads. The 

 Canadian Pacific was the first road to adopt the fire-tube 

 superheater exclusively, and the Santa Fe, although not 

 the first road to test the smoke-box design, was the 

 pioneer in adopting this device as a standard. 

 NO. 2098, VOL. 82] 



One of the chapters in the recent report of the U.S. 

 Commissioner of Education deals with education in 

 Central Europe. Among much other information of 

 interest in this chapter is a reference to the attempt of 

 Prof. Du Bois-Reymond, in his work on inventions and 

 iiiventors, to prove that inventive productivity in different 

 countries depends on social factors. General education, 

 density of population, transportation facilities, social 

 organisation, and so on, he maintains, determine this 

 productivity, and despite the participation of working men 

 in State affairs comparatively few patent appUcations come 

 from them. The result of an inquiry made in 1900 shows 

 that in England 15,300 applications for patents were made, 

 or 37 to every 100,000 of inhabitants, and that the per- 

 centage of illiteracy was 37. In the United States the 

 corresponding numbers were 22,900, 30, and 6-2, the per- 

 centage of illiteracy in this case being of the white popula- 

 tion above ten years of age. In Germany the numbers 

 were 14,800, 26, and 005. In France, however, only 

 7020 patents were applied for, or 18 per 100,000 in- 

 habitants, the percentage of illiteracy being 4-6. The 

 numbers in Italy, again, were 1030, 3, and 338 per cent, 

 of illiteracy. Race characteristics, in other words, do not 

 predetermine the inventive productivity of a country, nor 

 does the high proportion of literates, but social factors, 

 especially the high status of industry, do determine it. 

 England', the United States, and Germany, the countries 

 having the best developed systems of industry, are the 

 most productive in inventions. Germany alone had, in 

 1900, 1500 patent applications concerning technical con- 

 trivances relating to electricity. 



Owing to the death of the late Colonel Bingham, editor 

 of the " Fauna of British India," no volume of the series 

 has been issued for some time. This month, however, 

 Mr. Malcolm Burr's half-volume on the earwigs of British 

 India will appear, which is the first monograph on the 

 Dermaptera which has been published since De Borman's 

 monograph in " Das Tierreich." It will contain a descrip- 

 tion of a number of new and recently established genera, 

 and will be well illustrated. 



UUR ASTRONOMICAL COLUMN. 



Halley's Comet, 1909c.— Some interesting measures of 

 Halley's comet, made with the micrometer of the » erkes 

 40-inch refractor, are published by Prof. Barnard in No. 

 60s of the Astronomical Journal. With this large telescope 

 the comet was quite an easy object, and the measures 

 should be good ; but, as Prof. Barnard suggests, the edges 

 of such a nebulous bodv are not easy to set on. 



The measures extend up to November 30, 1909, when 

 the estimated magnitude was about ii-o, and the comet 

 showed a condensation of some 7" diameter. The d'a^eter 

 of the whole object was 41", and possibly an ill-dehned 

 nucleus was seen, but this feature w.as very doubtful. 

 From September 17 to November 14 the measured 

 diameters, reduced to miles, ranged from 16,400 to 9200 

 miles, the mean being 12,600 miles, or about i^ times 

 the earth's diameter. 



At the December (1909) meeting of the Royal Astro- 

 nomical Society, reported in No. 41S of the Observatory, 

 the Astronomer Royal announced that a photograph secured 

 with the Reynolds reflector at Helwan, on August 24, 

 shows the comet's image ; its position agrees within o-i2s. 

 in R.A. and 1-7" in declination w^ith the position calculated 

 from the Cowell-Crommelin orbit corrected by the Green- 

 wich observations. Messrs. Keeling and Knox-Shaw are 

 to be congratulated heartily upon securing the first known 

 photograph of the comet. 



In No. 25 of the Gazette astronomique, Signor Pio 

 Emanuelli discusses the probable encounter between the 

 earth and the comet's tail in May next. At 10 a.m. 

 (G.M.T.) on May 18 the comet will pass the descendin* 



