February 8, 1900] 



NA TURE 



359 



in the Manchester Museum — to which they were presented by 

 Prof. Williamson — Mr. Seward has subjected to a renewed 

 critical examination, with the result that he finds many of them 

 identical with fossil plants described previously under other 

 names by Brongniart. Thus, Sphcnopteris arguta, Lindley 

 and Hutton = Coniopteris hynienophylloides, Brongniart ; 

 Pecohteris dentata, L. and H. = Todiies williamsoni, Brong. ; 

 Otopteris aineata, L. and H. = Sagenopteris pkillipsi, Brong. 

 Some other specimens figured by Lindley and Hutton under one 

 name are, according to the author, identical with other plant- 

 remains which had been differently identified. Thus, Thuites 

 expanstts, figured on PI. 167, is specifically identical with 

 Brachyphyllum uianillare, figured on Pis. 188 and 219 

 Other Jurassic plant-remains in the Manchester Museum were 

 also described by Mr. Seward, and their systematic position 

 critically discussed. 



Cambrhjge. 

 Philosophical Society, January 22.— Mr. Larmor, Pre- 

 sident, in the chair. — Experiments on the periodic movement 

 of plants. Miss D. F. M. Pertz and Francis Darwin. The 

 first part of the paper is practically a continuation of the 

 authors' research on the artificial production of rhythm in 

 plants, published in the Annals of Botany, 1891. The second 

 part deals with a new example of periodic movement. If a 

 "sleeping" plant is placed in a dark room after its leaves have 

 assumed the nocturnal position, it will "awake" next morn- 

 ing, i.e. its leaves will return to the diurnal position, in spite 

 of the darkness. In the experiment described, the procedure 

 was varied by exposing the plants to one- sided illumination ; in 

 these circumstances the leaves are well known to assume 

 certain characteristic oblique positions. The point of the ex- 

 periment is that if a plant is darkened after having responded 

 in the above manner to one-sided illumination, it returns to the 

 oblique position on "awaking" next day in complete darkness. 

 — Wealden plants from Bernissart, A C. Seward. A brief 

 account was given of a collection of plants in the Natural 

 History Museum of Brussels which was obtained from argil- 

 laceous rocks at Bernissart, a locality rendered famous by the 

 discovery in 1877 of more than twenty complete skeletons of 

 Iguanodm. The beds containing the Iguanodons and plants 

 occupy a gorge, 250 m. deep, bounded on either side by car- 

 boniferous strata. A short list of species of Bernissart plants 

 was published in 1878 by M. Dupont (Bull. Ac. R. Belg., vol. 

 xxvi. [2] 1878, p. 387), the identifications being made by the 

 late Marquis of Saporta. Through the courtesy of M. Dupont, 

 the Director of the Brussels Museum, the writer has recently 

 examined the collection, which consists of numerous small frag- 

 ments of typical Wealden species. The flora is represented by 

 fragmentary samples which appear to have been transported for 

 a considerable distance, and finally deposited in a fine freshwater 

 argillaceous sediment. A striking feature of the flora is the 

 scarcity of Gymnosperms ; nearly the whole of the material 

 consists of fragments of fern fronds, Weichselia Mantelli being 

 by far the commonest species. The evidence afforded by the 

 plants points unmistakably to a Wealden age, nearly all the 

 species being identical with those described from the Wealden 

 rocks of the Sussex coast, the north German area and else- 

 where.— On the biology of Bulgaria polymorpha, R H. 

 Biffen. The life-history of this fungus has been studied in 

 detail by means of cultures grown on blocks of sterilised oak- 

 wood. 



Edinburgh. 

 Royal Society, January 22. -Prof. Copeland in the chair.— 

 Dr. Peddie. in a communication on the torsional constants of 

 iron and steel, stated that he obtained for steel results similar 

 to those already obtained for iron. A linear relation was found 

 to hold between log b and «, where x and n are the parameters 

 in the oscillation equation yn{x-^a) = b, in which x is the 

 number of oscillations reckoning from the commencement 

 of any experiment, and y is the amplitude of oscillation. 

 The hne representing this linear relation varies in inclination 

 with the state of fatigue of the wire; but, for the same 

 wire, these lines all pass through one point. This gave a 

 quantity which might be regarded as measuring a definite elastic 

 quality of the metal. The results showed that iron was, as 

 regards elastic properties, about six times worse than steel.— 

 Prof. Kuenengave a simple proof of Gibbs' phase rule, that a 

 system of n independent substances existing in r phases in 

 equilibrium is capable of (« - r-|-2) independent variations. It 

 NO. 1580, VOL. 61] 



was first shown that the total number of variables wats 

 («-i)r-f2. Then, by a simple application of the second law 

 of thermodynamics to the conditions of equilibrium, it was 

 shown that these conditions were (r-i)«. The differen'ce 

 of these two expressions gives the phase rule. — Prof. Kttenen 

 also read a paper on the change with temperature of the ' co- 

 efiicient of absorption of a gas in a liquid. Several experi- 

 menters had obtained evidence that in some cases the coefficieVit 

 of absorption passes through a minimum as the temperature 

 rises. Having been asked by Prof. Ramsay if the phenometion 

 might not be connected with the approach to the critical poiV^t, 

 he had looked into the question, and by a comparison oflthe 

 vapour-pressure curve for a mixture with the curve for the 

 solvent in the case of hydrogen and carbon dioxide he fourici 

 that the coefficient must increase as the critical temperature' is 

 approached. Then, the coefficient of absorption being in the 

 vast majority of cases high at low temperatures, it follows thiat 

 it must pass through a minimum as the temperature rises.— Mr. 

 W. B. Blaikie exhibited his " Cosmosphere," which consists of 

 a terrestrial globe surrounded by a concentric celestial sphere of 

 celluloid. The instrument is useful for demonstrating a great 

 variety of problems in astronomy and navigation. From the 

 cosmosphere in its complete form had been evolved a slide- 

 rule, which solved by inspection many of these problems. It 

 consisted of two celluloid sheets inscribed with projections 6f 

 the hemisphere with longitude and latitude lines. The hemi- 

 spheres were accurately superposed, and the upper one coutd 

 be rotated and clamped in any position relatively to the under. 

 Mr. Blaikie demonstrated the value of the slide-rule by solving 

 with great ease problems requiring, as usually treated in books, 

 a considerable amount of intricate mathematics. The solutions 

 were correct to about a quarter of a degree. 



Paris. 

 Academy of Sciences, January 29.— M. Maurice Levy 

 in the chair. — Contribution to the study of the radium radi- 

 ations, by M. Henri Becquerel. Different preparations ,of 

 radium salts emit rays which are equally deviated in the 

 magnetic fields, differing only in intensity. The results are 

 independent of the presence of air. — Note on the crystallifie 

 and volcanic rocks of Southern China, by MM. Michel 

 Levy, A. Lacroix and Leclere. The results of an examination^ 

 of the specimens collected by M. Leclere on his recent expedi- 

 tion in China. From Hien-Bai to Tali-Fou the rocks are 

 chiefly felspathic and micaceous schists. In the stanniferous 

 region of Ko-Tiou the granitic schists are traversed by tourmaliiip 

 pegmatites, whilst the line of fracture of I\hin-Gan is marked by 

 the appearance of a coarsely crystalline granite containing biotite. 

 — The Gard coal basin, by M. Marcel Bertrand. The author 

 combats the generally accepted view that the break between the 

 upper and lower coal-measures (Stephanian and Westphalian) 

 is the chief fact dominating the history of the chain, and puts 

 forward a view co-ordinating and explaining in a simple manner 

 all the anomalies of the basin. — On the molecular volumes of 

 some camphor derivatives, by MM. A. Ilaller and P. Th. 

 Muller. The results of the densities of eighteen camphor 

 derivatives, partly pure, and partly taken in toluene solution, 

 are tabulated and the results compared with those calculated by 

 Traube's formula — Materials of topological study for Algeria 

 and Tunis, by M. Bassot. Remarks on the tenth volume of the 

 " Cahiers du Service geographique de I'Armde." — M. Mittag- 

 Leffler was elected a Correspondent for the Section of 

 Geometry, and M. Bienayme for the Section of Geography 

 and Navigation. — The President announced to the Academy 

 the loss by death of M. Marion, Correspondent for the 

 Section of Anatomy and Zoology, and of Mr, D. E. Hughes,— 

 Remarks by M. Milne-Edwaids on the work of M. Marion.— 

 Observation of the Leonids of 1899 in Russia, by M S. de 

 Glasenapp. Although the conditions were unfavourable, owing 

 to the state of the sky, observations of 745 Leonids were made, 

 394 of which were seen during the night of November 14. — On 

 the proper motion of stars near the sun, by M. Duponchel.— On 

 some partial differential equations, by M. H. Duport. — On the 

 existence of second differentials of potential, by M. Henrik 

 Petrini. — On the law of the resistance of the air to the motion 

 of projectiles, by M. Paul Vieille. A comparison of the resist- 

 ance per square centimetre observed for a cylindrical projectile, 

 having a plane face at right angles to the direction of motion, 

 and calculated from the formulae of MM. Riemann and 

 Hugomot, shows that these are practically identical. The 



