February i6, 191 i] 



NATURE 



DO 



condenser itself being supposed to have a perfect non- 

 dissipative dielectric of the same dielectric constant. — 

 Prof. J.. A. Fleming: and G. B. Dyke : Some resonance 

 curves taken with impact and spark-ball dischargers. In 

 the course of the experiments described in the previous 

 paper on the measurement of energy losses in condensers, 

 a large number of measurements had to be made with the 

 cymometer of the frequency of oscillations in, and the 

 inductance of, the secondary or condenser circuit. It was 

 then an easy matter to draw complete resonance curves in 

 each case, and this has accordingly been done with both 

 the impact and spark-ball dischargers in the primary 

 circuit, and for various resistances in the secondary circuit. 



Mathematical Society, February 9. — Dr. H. F. Baker, 

 president, in the chair. — E. Cunning^ham : The applica- 

 tion of the mathematical theory of relativity to the electron 

 theory of matter. — G. B. MatheiMS and W. E. H. 

 Berwick : The reduction of arithmetical binary forms 

 which have a negative determinant. — H. Bateman : 

 Certain vectors associated with an electromagnetic field 

 and the reflection of light at the surface of a perfect 

 conductor. 



Cambridge. 



Philosophical Society, January 23. — Sir George Darwin, 

 K.C.B., F.R.S., president, in the chair. — ^W'. A. D. 

 Rudg:e : (i) A constant temperature, porous plug experi- 

 ment ; (2) observations on the surface tension of liquid 

 sulphur. — A. E. Oxiey : The magnetic susceptibilities of 

 certain comp)ounds. 



M.ANCHESTER. 



Literary and Philosophical Society, January' 24. — 

 Mr. Francis Jones, president, in the chair. — Dr. A. N. 

 Meldrum : The development of the atomic theory : (5) 

 Dalton's chemical theory. The paper deals first with the 

 principles, and afterwards with the genesis, of Dalton's 

 chemical atomic theory. It is shown that it is impossible 

 to suppose that the hypothesis of Avogadro had any 

 influence on Dalton whilst engaged on the theor\-, the 

 main principles of which are : — (i) that atoms of different 

 kinds tend to combine in the proportion i : i rather than 

 in any other, that the next proportion to occur is 1:2, 

 then I : 3, and so on, and (2) that when two compounds 

 of the same two elements are gaseous, the lighter is binary 

 and the heavier tertiary. Dalton's explanation of them 

 shows that Newton's postulate of similar particles, which 

 are " mutually repulsive," was the fundamental idea of the 

 chemical as it had been of the' physical atomic theory. 

 The author concurs with Roscoe and Harden in rejecting 

 the account of the genesis of the theory which connects it 

 with the discovery of the composition of marsh gas and 

 olefiant gas, but is unable to accept their view, the gist 

 of which is that Dalton first satisfied himself that the 

 atoms of different gases have different sizes, and then 

 devised the chemical theory. He concludes that it was 

 Dalton's experiments on the combination of nitric oxide 

 and the oxygen of the air that aroused his attention and 

 made him apply his physical theorj- to the purfKJses of 

 chemistn.-. — Prof. A. H. Gibson : The behaviour of bodies 

 floating in a free or a forced vortex. The main conclusions 

 drawn from the experimental results embodied in the paper 

 are : — (i) In a free vortex, (a) Very small floating 

 particles rotate in spiral paths, approaching with a con- 

 tinually increasing velocit)', and finally disappearing down 

 the funnel of the vortex. {Jo) If of moderate dimensions, 

 the behaviour depends on the shape, size, weight, and 

 position of the centre of gravit},- of the object, the lighter 

 particles approaching more rapidly than those of a lower 

 specific gravity. With homogeneous bodies of the same 

 specific gravity, depth of immersion, and shape of plane 

 of flotation, the larger shows the greater tendency to 

 approach the centre. (2) In a forced vortex : — (a) Small 

 bodies approach the centre with a radial velocitv which 

 is greater the greater the radius of rotation. {Jo) In 

 homogeneous bodies of the same size and shape, the 

 heavier shows the lesser tendency to approach the centre, 

 (c) A non-homogeneous body shows a lesser tendency to 

 approach the centre than does a homogeneous bodv of the 

 same size, shape, and weight. If the centre of gravity of 

 the non-homogeneous body is sufficientlv low, the bodv 

 works out to the outer edge of the vortex, (d) The shape 

 of the body in itself has no effect on its behaviour so long 

 as the vortex is a true forced vortex. As in the case 

 NO. 2155. VOL. 8^1 



of the free vortex, the knowledge of the forces called into 

 play is adequate for an explanation of all the observed 

 phenomena. 



DUBUN. 



Royal Irish Academy, Jaruary 23. — Dr. H. F. Barry, 

 vice-president, in the chair. — D. R. Pack-Beresford and 

 Nevin H. Foster : The woodlice of Ireland, their distri- 

 bution and classification. Twenty-five species of woodlice 

 (Crustacea Isopoda Terrestria) are found in Ireland, and 

 of these four species have been recorded from and are 

 common in every county. Sketch-maps are given which 

 show at a glance the various Irish countj* divisions in 

 which each species has been taken. A series of synoptical 

 tables is also included in the paper, which should prove 

 useful in enabling students to diagnose any British species. 

 Two plates illustrating Metoponorthus melanurus, B. L., 

 and Eluma purpurascens, B. L. (species which have not 

 yet been found in England), and a comprehensive biblio- 

 graphy, are also included. — John MacNeill : The early 

 population-groups of Ireland, their nomenclature and 

 chronology. The object of the paper was to distinguish 

 the different classes of group-names found applicable to 

 Irish population-groups in early times, and to assign an 

 approximate period of origination to each class of names. 

 The formulae of the earlier names were distinguished and 

 discussed, and a list drawn up under each formula. The 

 paper dealt with the classification of the groups as free, 

 tributary, and unfree, and identified the civil and military 

 organisations of the petty States in ancient Ireland with 

 the earliest traditional form of tne Roman State. 



Koyal Dublin Society, Januaiy 24. — Prof. T. Johnson 

 in the chair. — ^Prof. W. Bro«vn : Mechanical stress and 

 magnetisation of nickel, part ii., and the subsidence of 

 torsional oscillations in nickel and iron wires when sub- 

 jected to the influence of longitudinal magnetic fields. 

 The results of experiments on magnetisation and torsion 

 of nickel wire showed that a limit to the twist of the 

 free end of the wire is reached with a certain definite 

 longitudinal load. It was also shown by means of the 

 subsidence of torsional vibrations that the greatest internal 

 friction in the wire took place when it was surrounded by 

 a longitudinal magnetic field of the same value as thar in 

 which the maximum twist occurred with a given load on 

 the wire. — Dr. W. E. Adeney : The estimation of the 

 organic matters in unpolluted and polluted waters with 

 potassium bichromate and sulphuric acid. The investiga- 

 tions have been made with the view of discovering a rapid 

 and accurate method of estimating the total oxidisability 

 of the organic matters in unpolluted and polluted waters. 

 The water is treated under suitable conditions, which are 

 detailed in the paper, with a decinormal solution of 

 potassium bichromate and sulphuric acid, and, after 

 evaporation and digestion for a sufficient time in the water 

 bath, the excess of bichromate remaining is determined 

 by means of a decinormal solution of ferrous sulphate. 

 The results of a number of estimations of a variety of 

 waters are given, and they show that the method is cap- 

 able of yielding concordant and accurate results. — Prof. 

 Henr>' H. Dixon : The thermo-electric method of cryo- 

 scopy. The apparatus used in this method was devised in 

 order to determine the freezing points of small quantities 

 of solutions. With special devices for eliminating thermo- 

 electric errors, it has been found possible, using one pair 

 of junctions formed of copper and " eureka " alloy, to 

 determine the freezing points of a i c.c. of solution with 

 accuracy to o-oi° C. With a greater number of junctions 

 greater accuracy may be attained. The method is particu- 

 larly suitable for detf^cting very small differences of freezing 

 point. 



Paris. 



Academy of Sciences, February 6. — M. Armand 

 Gautier in the chair. — ^P. Idrac : New observa- 

 tions on the spectrum of Nova Lacertas (see p. 523). 

 — Henri Villat : The discontinuous motion of a fluid in a 

 canal containing an obstacle. — .\. Korn : The helicoidal 

 state of electrical matter : some new hypotheses for ex- 

 plaining mechanically electromagnetic phenomena. — Gaston 

 Gaillard : Researches on the influence of velocity on the 

 compass. At the high speeds attained in modern destroyers 

 there is a possibilitv- that the velocity may affect the 

 indications of the compass. Some experiments in this 

 direction have been carried out on a railway at speeds 



