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NATURE 



[July ,17, 1919 



dynamics," L. Bairstow; "Aeroplane Structures," 

 A. J. S. Pippard and Capt. J. L. Pritchard; "The 

 Design of Propellers for Aircraft," H. C. Watts; 

 "Telephonic Transmission, Theoretical and Applied," 

 J. G. Hill; "Principles and Practice of Electrical 

 Testing as applied to Apparatus, Circuits, and 

 Machines," R. G, Allen; "Engineering Machine 

 Tools and Processes," A. G. Robson; and "Efficient 

 Boiler Management," C. F. Wade. 



Erratum.— We regret that in the article on " Some 

 Recent Atomic Weight Determinations " in Nature for 

 Julv 3, p. 346, the name of Prof. T. W. Richards was 

 incorrectly given as "Theodore Williams," the sur- 

 name being omitted. 



OUR ASTRONOMICAL COLUMN. 

 The Movement of the Earth's Pole. — The issue 

 of Scientia for July contains an article by the Astro- 

 nomer Royal on this subject, which comprises a con- 

 cise statement of the movement predicted by Euler, and 

 of suggestions that have been made to show why the 

 observed movement does not conform to this. The 

 Eulerian principle enunciates that the axis' round 

 which the earth would turn, assuming it to be a 

 rigid body set spinning about an axis other than 

 the axis of figure, would always point in the same 

 direction in space {i.e. among the stars) within a very 

 little, but would describe a cone in the earth in a 

 period of 305 days, the radius of the circle described 

 by the wandering pole being about 10 metres. Ob- 

 servations show that the movement is compounded of 

 two circular motions of periods of a year and of 

 432 days respectively. Sir Frank Dyson writes that 

 the dynamical causes underlying these movements are 

 probably to he found in the changes of distribution 

 of matter on the earth, and quotes Newcomb, who 

 thought the amplitude of the Eulerian movement was 

 increased or diminished irregularly by meteorological 

 changes. Mr. Harold Jeffreys has lately shown that 

 a shift of matter symmetrical about the earth's axis 

 will not have any effect in shifting the earth's axis 

 of rotation, and. looks for the cause in an unsym- 

 metrical increase of mass, such as is caused by the 

 high barometer over Siberia in the winter, which, 

 however, is not sufficient of itself to produce the 

 observed effect. The lengthening of the free Eulerian 

 period from 305 days, on the assumption of a rigid 

 earth, to 432 days supplies information as to the 

 possible amount of elasticity of the earth. 



The Masses of Binary Stars.— There is a well- 

 known formula by which the total mass of a binary 

 system can be found if the parallax is known, as well 

 as the elements of the orbit. The modern method 

 of deducing stellar parallax by examination of the 

 spectrum therefore provides much data for determina- 

 tion of mass, and Prof. Aitken, of Lick Observatory, 

 has lately (Pub. Ast. Soc. Pac, June) used the 

 parallax of tvvrelve binaries taken from Messrs. Adams 

 and Joy's list to find their masses. These had been 

 already found by help of the trigonometric parallax, 

 and though considerable discordance was shown for 

 individual systems, the agreement of the mean mass 

 of the twelve binaries, which was r6i times that of 

 the sun bv the one method and 167 times by the other, 

 showed that the new parallaxes might be considered 

 trustworthy for mean results. Prof. Aitken, there- 

 fore, determined the mass of seven other stars which 

 are common to the list above cited and his own list 

 of binary systems. These, with Sirius and aCen- 

 tauri and the twelve before mentioned, make a list 

 of twenty-one systems the mass of which is known. 

 Thev range from 0-21 to 7-21 times that of the sun, 

 NO. 2594, VOL. 103] 



the mean value being i-88; and though some of the 

 individual mass-values must still be regarded as un- 

 certain, the mean result may be taken as confirmatory 

 evidence that the short-period visual binary systems 

 near to us are about twice as massive as our sun. 

 It may be noted that five stars of classes K and M 

 are, on the average, only half as massive as the 

 sixteen stars of classes A to G, and are, on the 

 average, nearly four magnitudes (absolute) fainter. 



SCIENCE IN INDUSTRY. 



Lectures at the British Scientific Products 

 Exhibition. 



SIR WILLIAM TILDEN, in his lecture on 

 "Chemistry in Reconstruction" at the British 

 Scientific Products Exhibition on July 7, remarked 

 that a visitor to the exhibition could not fail to 

 experience the comforting conviction that British 

 chemical manufacturers are now quite capable of 

 holding their own in regard to quality and variety of 

 products. They will undoubtedly be able to supply 

 the wants of this country if they continue to exhibit 

 the same skill, energy, and resource which have been 

 gradually developed during the last five years, and 

 to be protected for a time from foreign imports. 

 With regard to trade outside the United Kingdom, 

 it is too soon to indulge freely in optimism. The 

 Prime Minister, in his recent speech in the House of 

 Commons on the Peace Treaty, pointed to the condition 

 of German territory, which has not been damaged or 

 disturbed to any appreciable extent by the operations 

 of the war, and still retains the famous chemical 

 establishments with plant and machinery in working 

 order, and even increased in power by the material 

 stolen from Belgian and French factories. Moreover, 

 Germany has the services of a very large body of 

 technical chemists of great skill and experience. Ger- 

 many will, naturally, make greater efforts than ever 

 to penetrate into foreign markets. Then there is 

 Switzerland, with good schbols of chemistry and an 

 already established chemical industry. The United 

 States of America during recent years has vastly 

 extended the chemical departments of its universities 

 and technical schools, and devoted huge sums to 

 the development of chemical manufactures. Japan 

 also with a well-equipped university and many natural 

 products, combined with cheap labour, will certainly 

 appear in the field. 



All these will undoubtedly prove very formidable 

 competitors in the race in which the British chemist 

 will have to enter. In this country also there is still 

 a great deficiency in the number of well-qualified 

 chemists available for the service of industry. The 

 manufacturer has too long been satisfied with the 

 services of the laboratory boy, who can be taught to 

 perform routine testing" without any knowledge of 

 more than the most elementary chemical principles. 

 We require a large number of well-educated men 

 equipped with the fullest possible knowledge of 

 modern chemistry in every branch. Lord Crewe 

 referred at the opening of the exhibition to the several 

 methods which have been so far employed for con- 

 verting the academic into the industrial chemist. 

 There can be little doubt that this is best accom- 

 plished in the works, and in the long run manufac- 

 turers will find it pav best to employ the academic 

 chemist thoroughly drilled in the practice of analysis 

 and well acquainted with all the methods of research, 

 who must be assumed also to possess common sense, 

 and give him facilities for gaining that knowledge^ of 

 constructive materials and elementary engineering 

 which is reouisite for his work. 



The exhibition contains a most instructive and 



