M. A. Mannheim. In a preceding communication the author shown how to transform the properties relating to the discent of a straight line, of which the points describe tray surfaces; he now extends his method to the case the points of the movable line describe trajectory only, and taking as examples several theorems relating he fermer case, derives therefrom corresponding theorems in atter.-On a generalization of Euler's theorem relating to drons, by M. R. Perrin. Attention is drawn to ons bearing upon Euler's formula, published by the author $2 Bulletin de la Société Mathématique de France, t. x.).— shes which give a tension of dissociation equal to the a of the vapour of their saturated solutions, by M. H. Lesar Experiments are referred to which are antagonistic to theory of M. Bakhuis-Roozeboom. According to experi+, the curves representing the tensions referred to as func some I the temperature are tangential, and do not intersect at acute angle as required by the theory.-Action of fluorine different varieties of carbon, by M. Henri Moissan.-A method for the preparation of fluorides of carbon, by M. babne. On the blue flame of common salt and the atracopic reaction of copper chloride, by M. G. Salet. The finds that the bands seen in the spectrum of salt burning ten fire, and of which the strongest are situated in the and blue-green, are due to copper chloride, and coincide heads given by Lecoq de Boisbaudran in his "Spectres aux."On the electrical resistance of iron and its alloys ch temperatures, by M. H. Le Chatelier. The electrical ances for a considerable range of temperature of a number alloys have been examined. When the results are cally shown, the curve for ferro-manganese (13 per cent. a found to be regular, just as is the case with platinum or -rhodium alloy, while the curves for mild and hard show distinctly two singular points at 820 and 710°, and a steel (Si = 3 per cent.) shows the former only. Ferro25 per cent. Ni) behaves very peculiarly, as below 550 ochfications having quite distinct properties exist, and itself shows a sudden change of curvature at 340°. chemical researches upon silk, by M. Léo Vignon. Inon have been made to determine the heat disengaged various reagents are absorbed by raw and prepared silk. ssion of the results seems to indicate that the method yle employed to elucidate the theory of dyeing.-Estimation estum and humus in soil, by M. J. Raulin. A method mating potassium by weighing it on a tared filter as phos ybdate is described, together with the application of the permanganate process of J. H. Schmidt to the deteron of humus.-On a colouring-matter from Diaptomus, s to the carotin of vegetables, by M. Raphael Blanchard. colouring-matter, isolated from these animal organisms, is ip differ considerably in spectroscopic properties and in ability in alcohol from the lipochromes, and it does not e to be identical with any of the red pigments from the Lamerata, Echinodermata, Bryozoa, or Mollusca; while on Entrary it is found to show many analogies to carotins , which are so marked as to lead to the conclusion that sell a carotin and so possesses great interest as a colouring tance common to both the animal and vegetable kingdoms, as an instance of the production of a hydrocarbon by animal On the intercellular substance, by M. Louis Mangin. It an that among Phanerogams and Cryptogams (with the on of Fungi and many Algae) the tissues of the softer parts composed of cells cemented together by an intercellular subvar composed of insoluble pectates.-On the localization of g-matters in the seminal integuments, by M. Louis -Formation of quartz at the spring of Maubourot at rets, by M. Beaugey.-On the existence of leucite rocks A Minor, and on some hypersthene rocks from the , by M. A. Lacroix. It is found that the leucitic rocks near Trelizonde fall under two main types, leucitite and ➡phnte -Upon the composition of some pseudo-dolomitic from the north of France, by M. L. Cayeux. BERLIN. Meteorological Society, January 7.-Dr. Vettin, Presi at in the chair,.-Dr. Wagner spoke on the behaviour of in the soil. The relationships between surface water and and deposits, possessing as they do a distinct meteoroal interest, have as yet been but slightly investigated, probably Cause the behaviour of water in soil occupies the border-land between the subjects of meteorology, geology, agriculture, and hygiene. A review of scientific investigations which have so far been made on the subject of surface water and the formation of springs, shows that the problems of most importance are still awaiting their solution. In the speaker's opinion the task to be undertaken in the interests of meteorology is the establishing of as many lysimeters as possible, so that by keeping a continuous record of their indications a continued set of observations on surface water would be provided. He further considered it to be essential that the relationship of water to the soil should be investigated at depths far greater than has as yet been the case. A lengthy discussion followed the above communication, which turned chiefly upon a consideration of the forces, as yet but little known, which determine the collecting of water on internal impervious layers of the earth.-Prof. Spörer gave a short statistical statement on sun-spots during 1889. The chief point of interest was that the spots appeared during the first half of the year in the lower latitudes and in the second half in the higher. Taking the year as a whole, there were considerably more spots in the southern than in the northern hemisphere; this has been the case in each year since 1883.-The Secretary then handed in his annual report, and the Society proceeded to elect its officers for the year 1890. Prof. Schwalbe was elected President. Physical Society, January 27.-Prof. Kundt, President, in the chair.-The President opened the meeting by a short address Logelbach in Alsace.-Dr. Lehmann spoke on the testing of in memory of civil engineer G. A. Hirn, who died recently at tuning-forks. After the International Congress met for the establishing of a uniform standard of tone, and selected for this purpose a vibration frequency of 435, it devolved upon Government to construct a standard fork, and to devise some ready method for testing ordinary forks to an accuracy within half a vibration per second, and standard forks within o' of a vibration. The speaker discussed the various methods in use for comparing two forks and for counting the number of vibrations per second which they yield. For the first purpose the vibrations of the respective forks are employed, these being observed either acoustically or optically; a further means of effecting the comparison is by the stroboscopic method or by the acoustic wheel. The vibration frequency of a fork is determined either graphically or by means of a tuning-fork clock, or by means of the undulations obtained by oscillating or rotating acoustical instruments. An important factor in all these methods is the temperature of the fork. To determine this a special thermostat is employed, by means of which the fork can be set in vibration in an air-bath whose temperature is constant and accurately known. The standard fork for reference is one of König's, whose vibration-frequency has been accurately determined by several methods. The comparison of any new fork with the standard is made by means of the acoustic wheel, and by a simultaneous graphic recording of the movements of the fork which is vibrating inside the thermostat, and of the magnetic interrupter; the latter consists of a tuning-fork vibrating to the octave below the note yielded by the standard fork.-Dr. Eschenhagen exhibited curves of the three elements of terrestrial magnetism recorded by the new instruments in the Observatory of Potsdam, and gave a short description of the arrangement of the apparatus. The curves were taken on white photographic paper, and were of such dimensions that the greatest variations which have as yet been observed were completely recorded. -Prof. Kundt exhibited some quartz-fibres which he had received from Prof. Weinhold. He made, in addition, some remarks on the preparation of these fibres by Boys's method, and gave some data as to the dimensions of an apparatus which Prof. Weinhold had constructed for the measurement of gravitation constants, and had employed in several determinations. AMSTERDAM. Royal Academy of Sciences, Dec. 28, 1889.-Prof. van de Sande Bakhuyzen in the chair.-M. Hugo de Vries related the results of the scientific researches made by the Committee of Advice, appointed in July 1887 at Rotterdam, to report on the appearance of Crenothrix in the drinking-water of the Rotterdam water-supply. He gave an account of the organisms met with in the mains and basins before and after the filtration of the water, and of the degree of the pollution caused by these creatures in the colder and warmer months of the year. He spoke also of the influence of darkness on the water-organisms, which, under ordinary circumstances, live in the sunlight; of the proposals made by the Committee to mitigate or remove the evil; and of the improvements effected, or about to be effected, in accordance with those suggestions.-M. Kapteijn treated of chronographical observations for the purpose of determining parallaxes of fixed stars. After having explained the precautions taken to prevent systematic error, he gave the results and subjected them to several tests showing their absolute trustworthiness within the limits defined by the probable errors. Jan. 25.-Prof. van de Sande Bakhuyzen in the chair.-M. Hoogewerff, giving an account of joint work by himself and M. van Dorp, spoke of the action of potassium hypobromite on succinphenylamide, and on the amide of cinchonic acid.-M. van Bammelen communicated certain results of a research relating to the composition of volcanic and other soils, on which, in Deli and Java, tobacco is cultivated. The extraordinary fitness of the soil of the cleared forest grounds in Deli for the production of exquisite tobacco is to be attributed, he thinks, to the peculiar composition of the amorphous silicate occurring therein, to the looseness of the forest soil, and to the auspicious climate with regard to the rainfall. He concluded by insisting on the urgent need for the establishment of a scientific experimental station at Deli. Such an establishment would be favourable to the culture of tobacco, and would enlarge our knowledge of the soil, of the vegetable world, and of geological formations. GEOLOGICAL SOCIETY, at 3.-Annual General Meeting. INSTITUTION OF CIVIL ENGINEERS, at 7.30.-Some Types of American ROYAL INSTITUTION, at 9.-Magnetic Phenomena: Shelford Bidwell, F.R.S. SATURDAY, FEBRUARY 22. ROYAL BOTANIC SOCIETY, at 3.45. SUNDAY, FEBRUARY 23. SINDAY LECTURE SOCIETY, at 4-Our Ancestors, the Sea-Kings: Justin H. McCarthy, M. P. MONDAY, FEBRUARY 24. SOCIETY OF ARTS, at 8.-Stereotyping: Thomas Bolas. TUESDAY, FEBRUARY 25. ANTHROPOLOGICAL INSTITUTE, at 8.30.-Exhibition of Stanley's Spiro- ROYAL INSTITUTION, at 3.-The Post-Darwinian Period: Prof. G. J. or " WEDNESDAY, FEBRUARY 26, GEOLOGICAL SOCIETY, at 8.-On a Crocodilian Jaw from the Oxford Clay of Peterborough: R. Lydekker.-On the Relation of the Westleton Beds Pebbly Sands" of Suffolk to those of Norfolk, and on their Extension Inland; with some Observations on the Period of the Final Elevation and Denudation of the Weald and of the Thames Valley, Pari III.: Prof. Joseph Prestwich, F.R.S.-On a Deep Channel of Drift in the Valley of the Cam, Essex: W. Whitaker, F.R.S. SOCIETY OF ARTS, at 8.-The English in Florida: Arthur Montefiore. THURSDAY, FEBRUARY 27. ROYAL SOCIETY, at 4.30. SOCIETY OF ARTS, at 5.-The Northern Shan States and the E INSTITUTION OF ELECTRICAL ENGINEERS, at & ROVAL INSTITUTION, at 3-The Three Stages of Shakspeare's ki AMATEUR SCIENTIFIC SOCIETY, at &-Practical Coal-uning ESSEX FIELD CLUB, at 7.-Micro-Fungi of Epping Forest. how n BOOKS, PAMPHLETS, and SERIALS RECEIVE Elementary Dynamics of Particles and Solids: Prof. W M. Hirks * millan)-La Vie des Oiseaux: Baron D'Hamoa ville (Paris, J. A. A Naturalist's Voyage round the World, new edition, last: Darwin (Murray)-A Naturalist among the Head Hunters: CA ford (Philip).-Geology of the Quicksilver Deposits of the Par and Atlas to accompany same: G. F. Becker (Washington) —‡es and Fossil Plants of the Triassic Rocks of New Jersey and the Valley: J. S. Newberry (Washington).-II Tecrema del Paralele delle Forze Dimostrato Erroneo: G. Casazza (Brescia) — Mater Flora of the Malayan Peninsula: Dr. G. King (Calcuttal-! Physiology, vol. xi. Nos. 1 and 2 (Cambridge)-Transactions of the W. Free Institute of Science of Philadelphia, vol. 2 (Philadelphial-ciones Magnéticas y Meteorológicas del Real Colegio de Belea dede Jesus en La Habana, Julio-Dic. 1887 (Habana)-Bullens Geological Survey, Nos. 48 to 53 (Washington).-Department o ture, Melbourne, Bulletin No. 4 (Melbourne).- Timenn.“ ber. Journal of the Royal Agricultural and Commercial Society 41 Guiana, December 1889 (Stanford). Ettingshausen: "Das australische Florenelement in Cassedy: "Is the Copernican System of Astronomy Emerson: "Naturalistic Photography Letters to the Editor: Acquired Characters and Congenital Variation Easy Lecture Experiment in Electric Resonance Galls.-Prof. George J. Romanes, F.R.S. Shining Night-Clouds.-Robert B. White A Greenish Meteor.-T. D. A. Cockerell. The Molecular Stability of Metals, particularly of Iron and Steel. By Carl Barus Christoforus Henricus Diedericus Buys Ballot Notes Our Astronomical Column: Objects for the Spectroscope.-A. Fowler The Maximum Light-Intensity of the Solar Spectrum On the Star System & Scorpii. Geographical Notes. On some Needless Difficulties in the Study of Natural History. By Dr. C. T. Hudson, F. R.S.. The Total Eclipse. By Prof. David P. Todd. Scientific Serials P A. & C. BLACK'S LIST A. J. JUKES-BROWNE. Next Week, in Fcap. 8vo, Cloth, pp. 436, Price 45. 6d. SCHOOL MANUAL OF GEOLOGY. By the late J. Beete Jukes, F.R.S., Director of the Irish Geological Survey. A New (Fifth) Edition. Fnlarged and partly rewritten by A. J. JUKES-BROWNE, B.A., F.G.S., of the Geological Survey of England and Wales. Illustrated with 80 Woodcuts and Engravings. This handy text-book is intended, by the style of its treatment, to convey the elements of Geology in such a manner as will introduce the student at once to a practical and a sound owledge of the science. PROF. CHRYSTAL. Now Ready, in Two Parts, Crown 8vo, pp. 588, Price 235. ALGEBRA. An Elementary Text-book for the Higher Classes of Secondary Schools and for Colleges. By Geo. Chrystal, M.A., LL.D., Honorary Fellow of Corpus Christi College, Cambridge; Professor of Mathematics in the University of Edinburgh. PROF. TAIT. In Crown 8vo, Cloth, pp. 304, Price 6s. Second Edition, Revised and Enlarged. fessor of Natural Philosophy in the University of Edinburgh. BY THE SAME. In Crown 8vo, Cloth, Price 7s. 6d. THE PROPERTIES OF MATTER. MISS CLERKE. In 1 Vol., Crown 8vo, Price 12s. 6d. A HISTORY OF ASTRONOMY DURING THE NINETEENTH CENTURY. By Agnes M. Clerke. Second and Enlarged Edition. SIR WILLIAM TURNER. In One Volume, Crown 8vo, pp. 907, Price 16s. INTRODUCTION TO HUMAN ANATOMY. By Sir William Turner, M. B., F. R.S. Professor of Anatomy in the University of Edinburgh. Illustrated with 235 Wood Engravings. A. C. L. GÜNTHER. In Demy 8vo, pp. 720, Price 245. ty Albert C. L. G. Gunther, M.D., Ph.D., F.R.S., Keeper of the Zoological Department, British Museum. Illustrated with 320 Wood Engravings. EDINBURGH: ADAM & CHARLES BLACK. NOW READY. 8vo, over 400 Pages, Cloth, 12s. 6d., Post Free. A CATALOGUE OF BRITISH FOSSIL BY ARTHUR SMITH WOODWARD, F.G.S., AND NOW READY. 152 Pages, 8vo, Cloth, 5s., Post Free. A BIBLIOGRAPHY OF THE FORAMINIFERA, RECENT AND FOSSIL, FROM 1565-1888; WITH NOTES EXPLANATORY OF SOME OF THE RARE AND LITTLE-KNOWN PUBLICATIONS. BY CHARLES Davies SherbORN, F.G.S. NOW READY. One Volume, Royal 8vo, 458 Pages of Text, with 47 Plates, some Coloured, Bound in Cloth Extra, Gilt Top, Frice £3 35., Carriage Free. BRITISH PETROGRAPHY: WITH SPECIAL REFERENCE TO THE IGNEOUS ROCKS. BY J. J. HARRIS TEALL, M.A., F.G.S. DULAU & CO., 37 Soho Square, London, W. With 378 Illustrations, Svo, Price 16s. A HAND-BOOK OF CRYPTOGAMIC BOTANY. By A. W. BENNETT, M.A., B.Sc., F. L. S., AND GEORGE R. MILNE MURRAY, F. L.S. Nature." The utility of a book presenting in clear outline the present state of our knowledge of the morphology of flowerless plants cannot be doubted.. This work is a useful summary of Cryptogamic morphology." Journal of Horticulture.-"We have no hesitation in saying that this is an extremely valuable contribution to the literature of Cryptogamic Botany, and it will become a text-book for students, as well as a useful compendium of existing knowledge for botanists generally." Journal of Botany.-"A work which supplies a long-felt want on the part of the Cryptogamic student, which reflects credit upon its authors, and which is a pleasing proof of the thoroughness with which the study of botany is prosecuted in this country... London LONGMANS, GREEN, & CO. LATEST EDITION OF MITCHELL'S ASSAYING. A MANUAL OF PRACTICAL By JOHN MITCHELL, F.C.S. Sixth Edition. Revised and Re-edited by WILLIAM CROOKES. F.R.S., with Improvements and Additions rendered necessary by the Progress of Chemical Science. London LONGMANS, GREEN, & CO. GALTON'S WHISTLES For Determining the Upper Limits of Audible Sound in Different Persons. Prices 10s. 6d. and 21s. GEORGE SPILLER, MANUFACTURING OPTICIAN, 3 WIGMORE Street, w. In Three Volumes, Price £2 25. Each. Vol. I. Now Ready. A DICTIONARY OF APPLIED CHEMISTRY By T. E. THORPE, B.Sc. (Vict.), Ph.D., F.R.S., Treas. C.S.. Professor of Chemistry in the Normal School of Science and Royal School of Mines, South Kensington. ASSISTED BY EMINENT CONTRIBUTORS. F. H. BUTLER, M.A. Oxon., A.R.S. Mines, &c. 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Waltham Bros, Brewers. London.S.W. PERKEN, SON, & RAYMENT, OPTIMUS ENLARGING APPARATUS. Patent Quick Acting Rack Adjustment. This Apparatus comprises superior Mahogany Body Lantern and Long Bellows Camera adjusted by Rack and Pinion. The Lantern is fitted with powerful Refulgent Lamp, with 3 wicks, giving brilliant illumination. Compound Condensers. If with Russian Iron instead of Mahogany Body. 30 London, E.C. 137 9 250 0 450 O Japanned Metal. OPTIMUS 45 Russian Iron Body, Brass Sliding Tubes, 45s. Each Magic Lantern is efficient for Exhibitions. The Lens gives crisp definition, being a superior achromatic photographic combination, with rack and pinion. Compound Condenser of 4 in. diameter. Three-wick Refulgent Lamp, yielding a brilliantly illuminated picture, Japanned Metal, complete in Box......£1 10 0 5-in., no lens 75 0 s. d. 100 O s. d. ... 115 3 ... 110 0 285 0 12-in., |