2 14 



NATURE 



Jan. 2. 1890 



strain curves of the same material when hardened to different 

 ■degrees by heating and immersion, &c., it was concluded that 

 the increase of (p) during " yield " is the same for all the speci- 

 mens, and that the "yield" is a measure of the "hardness." 

 The question of discontinuity of the curves about the "yield 

 point " was next discussed, and evidence to the contrary given 

 by specimens which show conclusively that the yield does not 

 take place simultaneously at all parts of the bar, but travels 

 along the bar as a strain wave. In these specimens the load had 

 been removed before the wave had traversed the whole length ; 

 and the line between the strained and unstrained portions could 

 be easily recognized. As additional evidence of continuity, the 

 ■close analogy between the stress-strain curves of steel of various 

 degrees of hardness, and the isothermals of condensible gases at 

 different temperatures when near their point of liquefaction, was 

 pointed out ; the apparent discontinuity in the latter probably 

 being due to the change from gas to liquid taking place piece- 

 meal throughout the substance (see Prof. J. Thomson, Proc. 

 Roy. Soc, 71, No. 130). In seeking for an explanation of the 

 hardening of steel by permanent strain, the author was led to 

 believe this due to the displacement of the atoms within the 

 molecules of the substance. To test this hypothesis, experiments 

 on magnetization by stretching a bar in a magnetic field were 

 made ; these show that the magnetization increases with the 

 stress up to the "yield point," and is wholly permanent when 

 approaching that point. On comparing his results with Joule's 

 experiments on the elongation of loaded wires produced by 

 magnetization, the author infers that there are two kinds of 

 elongation — firstly, that produced by relative motion of the mole- 

 cules, and secondly, an elongation resulting from a straining of 

 the molecules themselves. To this latter straining the hardening 

 by permanent strain is attributed, and this view seems com- 

 patible with the results of Osmond's researches on the hardening 

 of steel. — Mr, F. C. Hawe's paper was postponed. 



Mathematical Society, Dec. 12. 1889.— Mr. J- J.iWalker^ 

 F.R.S., President, in the chair. — The following papers were 

 read : — On the radial vibrations of a cylindrical elastic shell, by 

 A. B. Basset, F.R.S.— Note on the 51840 group. Dr. G. G. 

 Morrice. — The President then vacated the chair, which was 

 taken by Mr. E. B. Elliott, Vice-President. — Complex multi- 

 plication moduli of elliptic functions for the determinants - 53 

 and - 61, by Prof. G. B. Mathews (communicated by Prof. 

 Greenhill, F.R. S.). — On the flexure of an elastic plate, by Prof. 

 H. Lamb, F.R.S. — Notes on a plane cubic and a conic, by R. 

 A. Roberts (communicated by the Secretary). — ^Dr. Larmor and 

 Mr. Curran Sharp made brief communications. 



Edinburgh. 



Royal Society, December 16, 1889.— Sir Arthur Mitchell, 

 Vice-President, in the chair. — Dr. Thomas Muir read a note on 

 Cayley's demonstration of Pascal's theorem. He has succeeded 

 in simplifying the proof. — Dr. Muir also read a. paper on self- 

 conjugate permutations, and one on a rapidly converging series 

 for the extraction of the square root. — Prof. Tait read a note 

 on some quaternion integrals, and also a note on the glissette of 

 a hyperbola. When a given ellipse slides on rectangular axes, 

 any point in its plane traces out a definite curve, and the same 

 ■curve can be similarly obtained as the trace of a definite point 

 in the plane of a certain hyperbola sliding between axes in 

 general inclined to the former. — Dr. Woodhead communi- 

 •cated a paper, written by Dr. Herbert Ashdown, on certain 

 substances, formed in the urine, which reduce the oxide of 

 copper upon boiling in the presence of an alkali. Dr. Ashdown 

 was led to search for these substances in the human subject as 

 the result of observations made upon lower animals. — Dr. G. E. 

 Cartwright Wood discussed enzyme action in the lower organisms. 

 —Dr. Woodhead communicated a paper, by Mr. Frank E. 

 Beddard, on the structure of a genus of OligochsetK belonging 

 to the Limnicoline section. 



Paris. 

 Academy of Sciences, December 16, 1889.— M. Hermite 

 in the chair. — Note on the eclipse of December 22, by M. J- 

 Janssen. The arrangements are described which were made 

 at the Observatory of Meudon for observing this event. — 

 On the effects of a new hydraulic engine used for irrigation pur- 

 poses, by M. Anatole de Caligny, The general disposition of 

 this apparatus was fully described in the Comptes rendus, Novem- 

 ber 19, 1887. The present note has reference to an improve- 



ment introduced for the purpose of remedying a serious defect 

 in the original design. It has now the advantage of giving as 

 good results as any of the systems in general use, while superior 

 to them in simplicity and economy. — On the production of films 

 of ice on the surface of the alburnum of certain species of plants, 

 by M. D. Clos. Early in December, after a hard frost, when 

 the glass fell to - 6° C. at night, Verbesina virginica, Helian- 

 thus orgyalis, and several other plants exhibited the same phe- 

 nomenon of glaciation at the Toulouse Botanical Garden as 

 was observed and described by Dunal at Montpellier in 1848. 

 An explanation is here given of the phenomenon, which occurred 

 on a much larger scale on the present than on the previous 

 occasion. — Observations of Borrelly's new comet (g 1889), made 

 at the Paris Observatory with the equatorial of the west tower, 

 by M. G. Bigourdan. The observations were taken on Decem- 

 ber 15, when the comet presented the appearance of a nebulosity 

 indistinctly round, of 2' diameter, slightly more _brilliant in the, 

 central region, but without notable condensation. In its expanse 

 were clearly visible two stellar points, and the presence of 



several others suspected. — On the series ^-^j "St' by M. 



Andre Markoff. From the nature of these series the author 

 establishes a formula which yields the equation — 



I -f- 



+ - -;, + 



+ 



= I -202 056 903 159 594 285 40, 



correct to 20 decimals, M. Markoffs paper forms a sequel to 

 Stirling's memoir "De Summatione et Interpolatione Serierum 

 Infinitarum."— On magnetic potential energy and the measure- 

 ment of the coefficients of magnetization, by M. Gouy. The 

 mechanical action of magnets on isotropous substances dia- 

 magnetic or feebly magnetic isotropous bodies has often been 

 utilized for measuring or comparing the coefficients of magnetiza- 

 tion assumed to be constants. On this hypothesis has been 

 established the expression of the potential energy which serves 

 to calculate the mechanical action in question. Here M. Gouy 

 proposes to supply a somewhat more complete theory by regard- 

 ing these coefficients, not as constants, but as variable with the 

 magnetizing force, and utilizing the experimental data for 

 measuring the variations. — On the colour and spectrum of 

 fluorine, by M. Henri Moissan. The colour of fluorine as here 

 determined is a greenish -yellow, much fainter than that of 

 chlorine under like conditions, and inclining more to the yellow 

 tint. Thirteen rays have been determined in the red region of 

 the spectrum. With hydrofluoric acid several bands have been 

 obtained in the yellow and violet, but very wide and not suffi- 

 ciently distinct to fix their position with accuracy. — Action of 

 ammonia on the combinations of the cyanide with the chlorides 

 of mercury, by M. Raoul Varet. The paper deals severally 

 with the action of ammonia on the cyanochloride of mercury ; 

 the action of absolute ammoniacal alcohol ; the action of 

 ammoniac gas ; the cyanochloride of mercury and zinc ; and the 

 cyanochloride of mercury and copper. — On an adulteration of 

 the essence of French turpentine, by M. A. Aignan. This 

 fraud, which consists in the addition of a small quantity of the 

 oil of resin, is not easily detected, but may be discovered by 

 studying the rotatory power of the liquid, as is here shown. — 

 Papers were submitted by M. Besson, on the temperature of 

 solidification of the chlorides of tin and arsenic, and on their 

 faculty of absorbing chlorine at a low temperature ; by M. 

 Seyewitz, on the synthesis of dioxidiphenylamine and of a red- 

 brown colouring substance ; by M. Pierre Mercier, on a general 

 method of colouring photographic proofs with the salts of silver, 

 platinum, and the metals of the platinum group ; and by MM. 

 G. Pouchet and Bietrix, on the egg and first development of the 

 alose, a fish allied to the sardine. 



December 23. — jSI. Hermite in the chair. — On the discovery 

 of a fossil ape, by M. Albert Gaudry. On presenting to the 

 Academy the skull of an ape recently discovered by Dr. 

 Donnezan at Serrat d'en Vaquer, M. Gaudry remarked that, 

 except those from Pikermi in Greece, these are the only cranial 

 remains of a fossil Simian hitherto brought to light. Many 

 other fossils have been found in the same place, which evidently 

 contains large accumulations, especially of extinct vertebrate 

 animals. — Observations of the comet discovered by M. Borrelly 

 at the Observatory of Marseilles, on December 12, by M, 

 Stephan. The observations are for December 12, 13, and 14, 

 during which period the comet steadily increased in brightness, 

 and assumed more distinct outlines. On the 12th it was 



