430 



NATURE 



[March 5, 1896 



SCIENTIFIC SERIALS. 



Wiedemann's Antialen der Physik tind Chemie, No. i, 1896, 

 — Absorption and emission of electric waves by resonance, by 

 Max Planck. When a secondary circuit is excited by waves of 

 a period equal to that of the circuit, resonance takes place. 

 Three stages may be considered. In the first, the circuit absorbs 

 energy from the external wave system until it has acquired a 

 maximum of oscillation. The next stage is stationary, the 

 circuit absorbing as much energy as is necessary to compensate 

 for energy radiated and converted into heat. The third stage 

 represents the dying out of the oscillation after the primary wave 

 has ceased. Maxwell's equation enables us to calculate the 

 distribution of energy during each of these stages.— Propagation 

 of electric waves in water, by E. Cohn and P. Zeeman. The 

 method used is an improvement on the apparatus previously 

 employed, the parallel wires being taken through the trough of 

 water and passing beyond it direct into the bolometer. The 

 most important results are that for frequencies ranging from 

 27 to 97 millions no dispersion is observable, and that the index 

 of refraction for such vibrations equals the square root of the 

 dielectric constant.— On the alleged dissipation of positive 

 electricity by light, by J. Elster and H. Geitel. The illumina- 

 tion of the anode in a vacuum leads apparently to a dissipation 

 of an electric charge similar to that observed when a liquid 

 alkali alloy is illuminated as a kathode. This is, however, due 

 to the effect of the light on the platinum kathode or the interior 

 of the tube after it has acquired a slight coating of alkali metal 

 vapour. When this is obviated, no dissipation takes place.— 

 Change of resistance of a contact by electric irradiation, by 

 V. V. Lang. When a rod of carbon is lightly stood upon a 

 block of carbon, a certain sensitive degree of contact may be 

 found which abruptly diminishes in resistance when electric 

 waves are produced in the neighbourhood, say by an influence 

 machine or even an electrophorus. Any slight concussion tends 

 to restore the original resistance. Similar results are obtained 

 with zinc and aluminium, but the very least shock spoils the 

 experiment in this case.— Longitudinal light, by G. Jaumann 

 (see p. 374).— On the electric arc, by L. Arons. It is well 

 known that an alternate current arc light is much more difficult 

 to produce between metallic than between carbon electrodes. 

 This may be due to the lower thermal conductivity of the carbon, 

 which enables it to retain its heat while the current passes 

 through wires, or to the volatile gases which are always given off 

 by carbon, or to the oxidation of the metals during the passage 

 of the current. & i^ b 



Symons's Monthly Meteorological Magazine, February. —The 

 mild winter, by the editor. Figures are given to show that, 

 though mild, there has been nothing very exceptional in the 

 present winter, although it bears a great contrast to the severe 

 frost of 1895. The temperature of December last in London 

 was only about 1° above the average; the temperature of 

 January 1896 was about 3° above the average, but it has been 

 exceeded m eleven years out of the last thirty-six. In January 

 1884, the lowest air temperature was 32° -2, and the whole month 

 was 3° warmer than January 1896.— The high monthly mean 

 pressure m January. The mean for the month in Camden 

 Square was 30-360 mches. This has only been exceeded twice 

 smce the Camden Square record began in 1858, viz. in January 

 1880, when the mean was 30-370 inches, and in February 1891, 

 when It was 30-472 inches. A table is given showing the high 

 monthly pressures of 30-360 inches or upwards in the vicinityof 

 -ondon smce 1779. This value has only been reached or 

 exceeded on nme occasions, and the mean of February 1891, 

 above quoted, is the highest. 



SOCIETIES AND ACADEMIES. 



London. 



, Royal Society, Januarj- 16. — " Memoir on the Theory of 



the Partitions of Numbers." Part I. By Maior P A Mac- 



Mahon, R.A., F.R.S. 



This memoir presented is a natural sequel to the memoirs of 

 i»9i, 1593. and 1894, published in extenso in the Philosotkical 

 Transactions. In fundamental idea it is graphical, resting, on 

 the one hand, upon the method of the memoir on the " Com- 

 positions of Numbers," of 1893, and, on the other, upon 

 Sylvesters graphical method, set forth in his "Constructive 

 Theory of Partitions," of 1882, published in vol. v. of the 

 A uierican Journal of Mathematics. 



NO. 1375, VOL. 53] 



The memoir is divided into four sections. In § i the author 

 gives new notions concerning the partitions of ordinary unipartite 

 numbers, and shows that the theory of the separations of a 

 partition necessitates the consideration of the partitions of multi- 

 partite numbers. The two theories proceed in parallel paths. 

 One-to-one correspondence can be established at any point. 



In § 2 he is engaged with the graphical representation of 

 unipartite partitions. The graph that, in the memoir of 1893, 

 was employed to denote a principal composition of a bipartite 

 number is shown to be the graph also of a unipartite partition. 



A new theory of unipartite partitions is evolved with algebraical 

 developments in correspondence. 



In § 3 he investigates a similar correspondence between the 

 compositioiwof tripartite numbers and certain regularised 

 partitions of bipartite numbers. 



The method is of general application, and indicates a one-to- 

 one correspondence between the compositions of w-f i -partite 

 numbers and contain regularised partitions of w-partite numbers. 

 In § 4 he takes up the question of the graphical representation 

 of completely regularised multipartite numbers. He follows 

 Sylvester, proceeding from two to three dimensions. Whereas 

 Sylvester employed nodes in a two-dimensional corner, the author 

 employs nodes piled up in a three-dimensional corner. Sylvester 

 obtains a two-fold correspondence from the permutations of his 

 axes X, y. The author obtains a six-fold correspondence from 

 the permutations of the three axes x, y, z. Even Sylvester's 

 two-dimensional graphs permit of six interpretations when viewed 

 from the three-dimensional standpoint. 



Physical Society, February 28.— Prof. John Perry, Vice- 

 President, in the chair. — Sir D. Salomons showed some experi- 

 ments with incandescent lamps. A large electro-magnet is 

 excited by means of a continuous current, while an alternating 

 current is passed through an incandescent lamp. On bringing 

 the lamp near the magnet the filament is set in vibration, which, 

 if the lamp is brought sufficiently near the magnet, is suffi- 

 ciently intense to break the filament. The number and position 

 of the nodes formed in the vibrating filament are found to be 

 independent of the natural period of the filament, but depend on 

 the frequency of the alternating current. Prof. S. P. Thomp- 

 son asked whether it was not found that the number of seg- 

 ments into which the filament divides, depended to some ex- 

 tent on the natural period of the filament. Prof. Ayrton said 

 that the magnetic leakage was very large with the arrangement 

 adopted, and he would like to know whether this method was a 

 more sensitive one for mapping out the field than those ordinarily 

 employed. In an instrument designed by Prof. Perry and him- 

 self, an alternating current was passed through a wire stretched' 

 between the poles of a magnet, and the tension of the wire was 

 altered till the vibrations set up were a maximum. The natural 

 period of the wire, and hence the frequency of the alternating 

 current, was then deduced from the tension, &c. In Prof. 

 Ewing's magnetic curve tracer, on the other hand, the natural 

 period of the stretched wire was made as different as possible 

 from the period of the alternations which were to be observed, 

 so that the natural vibrations of the wire did not influence the 

 results. The author's arrangement appeared to him (Prof. 

 Ayrton) to be intermediate between these two, and it 

 would seem that the natural period of the fila- 

 ment would to a certain extent influence the results. 

 Prof. Perry suggested that the lamp might be held in a very 

 steady support, so that after the large vibrations due to the 

 natural period of the filament had died out, the vibrations of the 

 period of the alternations alone could be observed. Sir D. 

 Salomons, in his reply, said that the arrangement was not in- 

 tended for making measurements. A lamp had been fixed in a 

 steady clamp, and the current passed for many hours, but the 

 character of the vibrations remained unaltered. He had found 

 the vibrating filament useful for microscopejwMK wllcie a surface 

 rather than a line of light was requi red. -y Prof. Fleming read a 

 paper by himself and Mr. Petavel, oh an analytical study of the 

 alternating current arc. The first part of the paper consisted of 

 an analytical study of the distribution of light throughout the 

 various radiating regions in the arc, when supplied with electric 

 power of known constant amount, the periodic variations of the 

 current through the arc and of the potential difference between 

 the carbons being at the same time recorded. The power was 

 measured by means of a bifilar watt-meter ; while by means of a 

 series of mirrors and a rotating disc carried by a synchronising 

 alternate current motor, the mean value of the light taken from 

 any part of the arc was compared with the instantaneous 



