April 19, 1906] 



NA TURE 



599 



supposed tidal influence. The rate at which the day in- 

 creases appears to be 0005s. per century, this being about 

 ten times greater than previous estimates. — Planetary in- 

 version : F. J. M. Stratton. The author had been led to 

 this investigation by Prof. Pickering's suggested explan- 

 ation of the cause of the retrograde motion of Phcebe, the 

 ninth satellite of Saturn. It was assumed that at the time 

 this satellite was thrown off from its primary the latter 

 had a retrograde motion of rotation, which subsequently 

 became changed to a direct motion by the inversion of the 

 planet's axis. The author concluded that while the theory 

 remains for the present a speculative hypothesis, it is sup- 

 ported by the theory of tidal friction, and gives the only- 

 explanation of certain facts that has so far been put for- 

 ward. — High-level chromospheric lines and their behaviour 

 in sun-spot spectra : Prof. A. Fowler. The observations 

 showed that enhanced lines appear as high-level lines in 

 the chromosphere, and that the corresponding Fraunhofer 

 lines are generally enfeebled in the spectra of sun-spots. — 

 Discussion of the Harvard observations of the eclipses of 

 Jupiter's satellites, 1878-1901 : Prof. R. A. Sampson. 

 The author gave an account of this discussion, which will 

 be published by the Harvard Observatory. 

 Cambridge. 

 Philosophical Society, March 12 — Dr. F^-ntnn. vice- 

 president, in the chair. — A theory of the widening of lines 

 in the spectrum : Prof. J. J. Thomson. The view put 

 forward is that the widening of the lines is due to re- 

 sonance. The luminous molecules emit waves of light, and 

 as these are also waves of electric and magnetic force, a 

 luminous particle produces a strong electrical field in its 

 neighbourhood ; this will act on the vibrating electrified 

 particles in a neighbouring luminous molecule, while this 

 second molecule will exert similar forces on the first mole- 

 cule. Two adjacent luminous particles thus exert forces 

 on each other, and, if the natural periods of the two are 

 equal, the action between them may result in a consider- 

 able change in the period. As the vibrating systems are 

 surrounded by many systems, some at one distance and 

 others at another, the changes produced in the periods will 

 not be constant, but may have any value included between 

 certain limits, the range between the limits increasing with 

 the number of luminous molecules. This range in the 

 value of the periods causes the original bright line to be 

 spread out into a band. — The transmission and reflection 

 of the radiation from radio-active substances: Prof. J. J. 

 Thomson. The amounts of secondary, tertiary, and 

 radiation of a higher order transmitted through and re- 

 flected from a plate of matter placed in the path of 

 radiation from radio-active substances are calculated, and 

 methods obtained for comparing the total ionisation pro- 

 duced by the secondary and other rays with that produced 

 by the primary rays. — (1) The asymptotic expansion of the 

 integral functions 



g £^i±f») and 2 *T(' + »» 



„t r(i+«) „=o r(T + ra + «e) 



(2) The asymptotic expansion of integral functions defined 

 by generalised hypergeometric series : Rev. E. W. Barnes. 

 — A method of following the course of certain chemical 

 actions, and a period of induction in the action of water 

 on monochloracetic acid : P. V. Bevan. The method de- 

 scribed was to determine the resistance of the solution in 

 which the chemical action was taking place. In dilute 

 solutions, when an acid such as hydrochloric acid is set 

 free as the action progresses, this method affords a very 

 delicate way of observing the rate of decomposition. The 

 action of water on monochloracetic acid was investigated, 

 and was found, except just at the beginning, to follow the 

 normal monomolecular course. — The radio-activity of 

 metals and their salts : N. R. Campbell. Measurements 

 of the activity of metals and their salts show that the 

 radio-activity of ordinary materials is an atomic property. 

 The identity in respect of this property of samples of the 

 same salt prepared by different methods shows that the 

 apparent activity cannot be due to impurity. — A relation 

 between the velocity and the volume of the ions of certain 

 organic acids and bases : T. H. Laby and G. A. Carse. 

 A method of finding the relation between the velocity and 



NO. 1903, VOL. 73] 



linear dimensions of an ion is to calculate the latter 

 by taking the cube root of the ionic volume found from 

 the molecular and atomic volumes, and combine this with 

 the ionic velocity. It is found that the product of these 

 two quantities is approximately constant for the members 

 of the homologous series which the authors have examined, 

 viz. the fatty acids, amines, pyridines, and anilines, but 

 varies from series to series. — A preliminary note on the 

 maiotic phenomena in the eggs of the hermaphrodite Angio- 

 stomum nigrovenosum (Ascaris nigrovenosa) : S. A. 

 McDowaii The synapsis of the chromosomes is very 

 clearly shown in this animal. — The reduction of the general 

 ternary quintic to Hibbert's canonical form : H. W. 

 Richmond. 



Dublin. 



Royal Dublin Society, February 20. — Dr. W. E. Adeney 

 in the chair. — The vapour pressure of a pure liquid at 

 constant temperature : Prof. Sydney Young. In ord,er to 

 find whether the statement contested by Battelli and others, 

 that the vapour pressure of a pure liquid is independent of 

 the relative volumes of liquid and vapour, is borne out by 

 experimental observations, the author has collected together 

 the results of his determinations of the vapour pressures 

 of twenty-seven carefully purified liquids. He points out 

 (1) that errors due (<i) to the presence of dissolved air and 

 other impurities, (b) to the vaporisation of mercury, and 

 (c) to readings being taken too rapidly, would have the 

 effect of making the observed pressures higher at small 

 than at large volumes ; {2) that those errors must be smaller 

 when readings are taken during evaporation than during 

 condensation ; (3) that the errors are likely to be greater 

 at high temperatures than at low ones. With twenty-one 

 out of the twenty-seven pure substances, forty-five series of 

 determinations were successfully carried out, the liquids 

 having been almost free from air, and no signs of de- 

 composition having been observed. There were 493 deter- 

 minations of vapour pressure, each being the mean of, as 

 a rule, four readings taken at different volumes. That the 

 mean observed fall in pressure during evaporation for the 

 257 determinations at temperatures up to 180 was less 

 than 1 in 10,000 may be regarded as a proof that the vapour 

 pressure is really independent of the volume. At tempera- 

 tures above 180° the mean fall in pressure for 236 deter- 

 minations was 1 in 1450. — Views illustrating the permo- 

 Carboniferous glaciation of South Africa : Prof. G. A. J. 

 Cole. 



March 20. — Prof. Sydney Young, F.R.S., in the chair. — 

 Electromagnetic mass : Prof. A. YY. Conway. This was a 

 continuation, in an expanded form, of the paper read at 

 the meeting held January 16. 



Paris. 



Arademv o' Sciences, April 9. — M. H. Poincare in the 

 chair. — Some problems in mathematical physics appertain- 

 ing to the equation of M. Fredholm : Emile Picard. — A 

 means of controlling a system of clocks synchronised elec- 

 trically : G. Bigourdan. In a system of clocks controlled 

 electrically the synchronism may be disturbed owing to 

 various causes. By the use of a galvanometer attached to 

 each controlled clock, and the suppression of the directing 

 current once in each minute, at the zero second, any 

 deviation can be measured. — Concerning the presentation 

 of a number of the " Catalogue photographique du Ciel " 

 from the Observatory of Toulouse: M. Lcewy. This 

 number is chiefly devoted to the measurements of the recti- 

 linear coordinates of stellar images taken photographically 

 with a view to the determination of the solar parallax by 

 means of the planet Eros. — The transformations of systems 

 of partial differential equations of the second order : J. 

 Clairin. — The dichroism, double refraction, and conduc- 

 tivity of thin metal plates obtained by kathode pulver- 

 isation : Ch. Maurain. The effects described were shown 

 most strongly by bismuth, but similar results were obtained 

 with gold and nickel. — Gaseous osmosis through a colloidal 

 membrane : Jules Amar. From the experiments described 

 the author concludes that gaseous osmosis through the 

 tissue employed is in accord neither with the experimental 

 laws of Bunsen and Graham nor with the theories of Stefan 

 and O. Meyer. — The variations of the absorption bands of 

 a crystal in a magnetic field : Jean Becquerel. Some of 



