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SCIENCE PROGRESS 



of the total revenue of the companies irrespective of the character of the load 

 they carry. 



Vol. xiii of the Contributions from the Jefferson Physical Laboratory 

 (Harvard University) contains an account of Dr. P. W. Bridgman's work on 

 the effects of pressure on the resistance and thermo-electric properties of 

 metals. He finds that, under a pressure of 10,000 kilograms weight per sq. 

 cm., the resistance of cobalt and tungsten wires is i per cent, less than at 

 atmospheric pressure, while for lead, tin, and cadmium the decrease is no less 

 than 10 per cent. The law connecting the resistance and pressure is linear, 

 and the temperature coefficient of the resistance between 0° and 100° C. 

 appears to remain unaltered. The effective of increase of pressure on the 

 thermo-electric e.m.f. varies a good deal with diilerent metals, but as a rule 

 the thermo-electric power increases, both Peltier and Kelvin effects becoming 

 greater with larger pressures. 



In an article in Science (June 18, 1920), Langmuir puts forward arguments 

 favouring quite a new type of structure for the helium atom. He suggests 

 that the two electrons oscillate along arcs of the same ellipse (?) having the 

 positive nucleus as centre, the path of each electron extending 77° 58' each 

 way from the mid-point, and being so curved that the radius vector at the 

 end of an arc is 1-138 times the radius at the centre. According to his 

 calculations (to be published in the Physical Review) , this structure gives a 

 value for the ionising potential of helium which accords with the results of 

 recent experiments made by Franck and Knipping, namely 25-5 volts as 

 against the 28-8 volts demanded by Bohr's 1913 model. 



Prof. Raymond Pearl, of the Johns Hopkins University, contributed an 

 interesting article on the efiect of the war on the populations of France, 

 Prussia, Bavaria, and England and Wales to Science (June 4, 1920). During 

 the war there was no migration of the population of these countries, so that 

 the ratio of the deaths to the births serves as an indication of the change of 

 population. If this ratio, expressed as a percentage, exceeds 100, the 

 population is, of course, diminishing. Using data obtained from the quarterly 

 returns of the Registrar- General in the case of England and Wales, and from 

 the Journal of the Statistical Society of Paris for the others, he obtains the 

 following results : 



* Based on returns for first nine months of year only. 



It will be noticed that the proportionate change of the death-birth ratio is 

 approximately the same for France, Prussia, and Bavaria, in spite of the very 

 different pre-war values and the equally difierent psychological condition of 

 the peoples during the greater part of the war. The change in the index for 

 England and Wales shows the same general tendency, though to a much 

 smaller extent ; and while the index does not show any marked rise as a result 

 of the influenza epidemics of 19 18 in any one of the countries considered, 

 though such effect as is shown is greater for England than for any other. 

 Data for the post-war period is not yet available except for England and 



