Mar ell 20, 1884] 



NA TV RE 



495 



on electric conductivity of gases (first part). — A. 01j2rbeck, on 

 electric oscillations and on phenomena of polarisation caused 

 thereby. — A. Toepler, on the estimation of horizontal magnetic 

 intensity by use of the balance. — W. von Bezold, a simple experi- 

 ment on the connection between the temperature of an incan- 

 descent wire and the composition of the li?ht emitted by it. A 

 platinum wire is stretched horizontally through the tip of a Bunsen 

 burner and examined in a spectroscope with horizontal slit. — E. 

 Ketteler, reply to Herr Voigt's criticisms. 



No. 2, February. — S. Czapski, on the thermal variation of the 

 electromotive force of galvanic batteries, anditsrelatim to their 

 free energy. — J. Kollert, on the properties of flame in their elec- 

 trical relation. Confirms the previous measurements of Elster 

 and Geitel. — F. Fuch«, on a compensation-method for estima- 

 tion of the resistance of unpolarisable elements. A modification 

 of Po Jgendorff's well-known method. — E. Budde, on the theory 

 of thermo-electric forces. — H. Lorberg, on eltctrostriction. A 

 discussion of Quincke's results. — B. VVeiustein, on the calcula- 

 tion of the potential of cMls. A mathematical paper. — A. von 

 Waltenhofen, on an instructive expn-iment which may be made 

 with asymmetrical thermopiles. On passing an independent 

 current through the therm ipile certain non-reversible phenoaiena 

 of polarisation are observed ari-ing from the asymmetry of the 

 junctions that are heated. — -C. Cliri^tiansen, on the emission of 

 heat from uneven surfaces. — A. Tschirch, researches on chloro- 

 phyll and some of its derivatives. — W. Iloltz, a lecture experi- 

 ment in pro -if of the law that the velocity of rotation increases as 

 the rotating masses approach the axis. 



yournal de Physique, tome iii. No. 2, February. — G. Lipp- 

 mann, physical definition and determination of absolute tempera- 

 tures. This is the first part of a communication in which the 

 author seeks to find stricter thermodynamic definitions of tem- 

 perature. He attributes to Carnot the discovery of the scale of 

 absolute temperature ! — D. Gernez, researches on the duration 

 of the solidification of sulphur, and on a new variety of sulphur. 

 The crystallisation in octahedra takes from 25 to 100 times as 

 long as the crystallisation in rhombic prisms. The new crystal- 

 line kind obtained by M. Gernez is in the form of very elongated 

 prisms of a nacreous texture. They are produced by rubbing 

 the side of the test-tube containing the surfused sulphur with 

 the end of a platiiium wire or glass rod. When these crystals 

 are introduced into surfused sulphur, they determine a growth of 

 similar crystals throughout the mass ; and the formation is much 

 more rapid than that of either of the previously known forms. — 

 E. Mathieu, suspension of a liquid by a capillary vertical tube. 

 — E. Mathieu, modification of the pressure of a liquid by capil- 

 lary forces. 



Rendiconti del R. IstUufa Lomhardo, Milan, January 24. — 

 Biographical memoir of Emilio Cornalia (1824-1S83), by Prof. 

 I-eopoldo Maggi. — Necrological notice of the late Camillo 

 Hajech. — A'A«'«^'of the meteorological obsei-vations made at the 

 Brera Observatory, Milan, during the year 1883, by E. Pini. — 

 Some applications of Cournat's principle of least effort to the 

 equilibrium of linked systems (theoretical mechanics), by Prof. 

 G. BarJelli. — Meteorological observations made at the Brera 

 Observatory during the month of January, 1884. 



SOCIETIES AND ACADEMIES 

 London 

 Mathematical Society, March 13. — Prof. Henrici, F.R.S., 

 president, and subsequently Mr. S. Roberts, F. R.S., vice-presi- 

 dent, in the chair. — The Rev. A. C. E. I51omfield, Messrs. J. 

 Chevallier, E. H. Hayes, R. S. Heath, and Prof. J. Larmor 

 were elected Members. — Mr. Tucker read a paper by Prof. M. 

 T. M. Hill on the closed funicular polygons belonging to a 

 system of coplanar forces having a single resultant ; and commu- 

 nicated a paper by Prof. J. Larmor, on the direct application of 

 the principle of least action to dynamical analogues. — Mr. J. W. 

 L. Glaisher, F. R.S. , read a paper on the square of Euler's 

 series. — Mr. J. J. Walker, F.R.S., communicated a note by 

 Mr. J. Griffiths, further results from a theory of transformation 

 of elliptic functions. — Mr. S. RoToerts, F.R.S., read a note con- 

 cerning the Pellian equation. 



Physical Society, March S. — Prof. Guthrie, president, in 

 the chair. — Lord Rayleigh read a paper on the electro-chemical 

 equivalent of silver. The determination was made by a method 

 described to the last meeting of the British Association at South- 

 ampton, which consists in using two fixed coils and a movable 



coil stispended between these from one end of a balanied beam. 

 These coils are in circuit with the current and voltameter. The 

 current is reversed in the fixed coilsat intervals of five minutes, and 

 the weight required to bring the balance even is noted. The calcu- 

 lation of the effect by this method is independent of the precise 

 metsurement of the coils. Two or more silver voltameters were 

 ia circuit, nitrate of silver being the solution used. Careful 

 precautions of various kinds were taken, and the result was that 

 unit C.G.S. current deposits I'ii8 X 10--. It follows that i 

 ampere will deposit 4'025 grm. of silver per hour. — Lord Ray- 

 leigh also read a paper on the absolute electromotive force of 

 Clark's cell. Experiments made at the Cavendish Laboratory 

 gave the electromotive force of this cell as i'453 volts. The 

 accepted value is i'457 volts. If the B.A. unit (as Lord Ray- 

 leigh believes) is ab mt '9867 of a true ohm, the result, i'453, 

 becomes I "434 volts. — Lord Rayleigh also mentioned that he 

 had been making experiments on the rotation of the plane of 

 polarised light in bisulphide of carbon, and obtained a result 

 agreeing more nearly with Gordon's than with Becquerel's. — 

 Profs. Guthrie and Ayrton spoke on the papers, the former 

 eliciting the reply that electro-corrosion was less saMsfaetory 

 than electro-deposition for determining the equivalent ; and the 

 latter that silver was better than copper for accurate results in 

 the voltameter. — Mr. Shelford Bidwell, M.A., read a paper on 

 some experiments illustrating an explanation of Hall's pheno- 

 menon. By these experiments Mr. Bidwell sought to explain 

 Hall's effect through a combination of mechanical stress and the 

 well-known Peltier effect on the thin metal plate which is placed 

 between the poles of the magnet. He repeated many of the 

 experiments, and showed how he had obtained the same results 

 as Hall, except in the case of aluminium, which he found to be 

 -I- like iron, whereas Hall made it — . Mr. Bidwell reversed 

 the effect by cutting two slits in the strip of metal, thereby alter- 

 ing the stress on it. Righi's effect was also exolained on the 

 same grounds. Mr. Walter Browne said that difference in the 

 quillty of the aluminium might explain tie anomaly with this 

 metal. Prof. Perry criticised the explanation of the slitted 

 plate, and Prof. G. C. Foster suggested that results in absolute 

 measure should be obtained. 



Edinburgh 

 Royal Society, February iS. — Sheriff Forbes Irvine, vice- 

 president, in the chair. — Prof. Tait read a paper on radiation, 

 in which he called attention to Stewart's papers of 1858 as 

 containing, so far as it has yet been developed, the theory of 

 exchanges. Yet, in the most recent authoritative treatise on the 

 subject, the name of Stewart is not even once mentioned. The 

 basis of the whole theory is Carnot's principle, ani therefore no 

 demonstration can be considered absolutely rigorous. Thus it is 

 probable that as there are very hot particles in a gas at ordinary 

 temperatures, so there may be feeble radiation of high wave- 

 lengths from a black body at ordinary temperatures. — Mr. Sang 

 read a paper on the need for decimal subdivisions in astronomy, 

 trigonometry, and navigation, in which he pointed out the 

 inconvenience of the sexagesimal system, and estimated it as 

 doubling the labour of calculation. The decimal division of the 

 second, used throughout the Nautical Aim mac, was appealed to 

 as evidence of the need for a change. The paper was accom- 

 panied by a number of tables .suited to the decimal division of 

 the quadrant, or useful therefor. — Prof. Ewing communicated 

 a paper by A. Tanakadate on an electromagnetic declinometer. 

 — Prof. Tait showed that when one polygon has 'ts corners at 

 the middle points of the sides of another, the condition that the 

 first, second, or «th derived polygon shall be similar to the 

 original, involves a singular equation in quaternion differences. 

 — Prof. Tait also made some remarks on the basis of the theory 

 of vortex atoms, pointing out that there is not nece-sarily any 

 direct action between vortices in a perfect fluid ; the pre- 

 sent theory, which indicates such action, being based upon the 

 assumed continuity of motion throughout the fluid. 



Paris 

 Academy of Sciences, March 10. — M. RoUand in the chair. 

 — The election of M. G. Darboux was announced, as successor 

 to the late M. Puiseux in the Section of Geometry. — On the 

 forms presented by the nucleus of the Pons-Brooks comet on 

 January 13 and 19 (one illustration), by M. Faye. The author 

 rejects the explanation of these remarkable forms proposed by 

 Bessel, who attributed to the nucleus a polarity like that of the 

 magnetic forces. In virtue of this polarity the nucleus and ante- 



