its distance from its armature, is least, the greatest possible portion of the work being thus put upon the clockwork, and the least upon the battery. This spring aids the electro-magnet, but does not in any wise reduce the effect of the reversing spring in holding the clutch to its work; so long as the base of that spring is unmoved, its action is unimpaired. The resistance of these springs occurs only during the ascent of the needle-bar, which is, therefore, counterpoised to excess, and the resistance and the motion are thus rendered uniform. By reason of the form of the clutch-teeth before described, there is no outward thrust upon the clutches while in action, and hence the reversing spring requires only to be strong enough to throw the arm over and to shift the clutches. The stop of the clutch-arm next the electro-magnet is an insulated plate, to which the battery-wire leading from the magnet is connected, so that as soon as the arm has left the stop the circuit is again broken, although the needle may for a short time remain in contact with the mercury; the recording-point is at once withdrawn, and thus makes upon the paper a single perforation which must be a true record of the position of the mercury in the tube, unaffected by friction or other disturbing cause, since this action must always take place at the moment of contact of the needle with the mercury, and these dots or perforations are repeated at the end of each interval of time required for the needle-bar to ascend and descend the required distance, which will be about two minutes with the wheel-motion designated. The graduation of the scale upon the paper must correspond with the movement of the mercury in the tube of the thermometer as accurately as the graduation of the scale of an ordinary thermometer corresponds with the movement of the mercury in its tube. If but one instrument of this sort is to be made this is very easy, the rate of motion is a certained, a scale is made to fit it, and the paper is ruled to that scale. In all thermometers heretofore made the scale has been made to fit the tube, but if more than one of these instruments is to be made, it becomes necessary, or at least very convenient, to have one set of ruled papers that will fit all the instruments, and it then becomes necessary to reverse the practice and to make the tubes to fit the scale. The rise and fall of mercury in a thermometer depends upon the proportion between the diameter of the tube and the volume of mercury in the tube and bulb, and while it is possible to construct these parts in such proportion as to obtain proximately a given motion, it is not possible thus to obtain it exactly. The tube and bulb are made in separate parts, as shown in Fig. I, of such size that when the tube is thrust half way into the bulb, the volume of mercury filling the tube half way at 32° Fahrenheit is as nearly as may be properly proportioned to the diameter of the tube. If now there be found too much motion, the capacity of the bulb is diminished by thrusting the tube further in, and vice versa, and the proper height of mercury at 32° for that purpose is marked upon the tube. Mercury exposed to the air will slowly form a coating of oxide upon its surface. To prevent this, a small quantity of glycerin or of oil free from oxygen is placed in the thermometer tube above the mercury. If, notwithstanding, the oxide shall accumulate to an inconvenient extent, the observer in charge of the instrument will remove the thermometer from its place, and will put the bulb in warm water until the oxide is floated off. He will then supply the loss with pure mercury, determining the proper quantity by inmersing the bulb in broken ice, when the mercury column should stand at the mark for 32°. The whole apparatus, except the thermometer itself, can be inclosed, and so protected from the weather and dust, while the thermometer is exposed to the air below. The system is equally applicable to a barometric record, in which case, on account of the small range of motion, the needle-bar is connected to a lever, thus increasing the range of the record. SCIENCE IN BOHEMIA1 THE Bohemian Society of Science continues its useful career, which has already lasted for eighty-four years, and its latest publications (the Memoirs, the Proceedings, and the annual "Abhandlungen der Mathematish-Wissenschaftlichen Classe der K Böhmischen Gesellschaft der Wissenschaften, vom Jahre 1879-1880, vi Folge, Band x. (Prag. 1881). 'Sitzungsberichte" of the same Society, for 1879 and for 1880. 'Jahresberichte" of the same, for 1879 and 1880. Reports) contain many valuable papers, devoted partly to science in general, but mostly to the exploration of Bohemia itself in its various aspects. The last volume of its Memoirs ("Abhandlungen " for 1879-1880, series vi. vol. x.) contains a series of very interesting papers, each of them being the result of careful and extensive research. Prof. Franz Farsky gives the results of varied experiments which were undertaken at the experimental agricultural station at Tabor, on the growth of food-plants in water containing solutions of those salts which constitute the ash of the plant. The influence of alkaline and acid solutions, and especially that of chlorine, which proved to be a most important element of vegetation, were submitted to varied experi ments, all the results of which are published in full. The general reader will notice with interest the beautiful results obtained by the culture of oats and barley in glasses of water, which contained the necessary salts, the plant being simply planted in a bit of cotton. Dr. F. J. Studnicka publishes in the same volume the complete tables of observations on the amount of rain in Bohemia during the years 1879 and 1880, at no less than 312 stations in 1879 and at 289 stations in 1880. If we remember that besides these stations there are very many others established by the Bohemian Foresters' Society, and that the whole number of stations where the amount of rain is accurately measured day by day, amounts to 800, we can see that Bohemia has probably the widest network of ombrological observations in Europe. We notice that the most rainy places in Bohemia are Maader, Rehberg, and Neuwelt (1744, 1572, and 1505 millimetres per year respectively), all these situated at great heights (985, 848, and 683 metres), whilst the less rainy places are Kapic, Slaten, and Kladno (431, 438, and 456 millimetres), situated respectively at altitudes of 322, 246, and 380 metres. Dr. F. Ullik contributes a paper on the matter suspended and dissolved in the water of the Elbe, at Tetschen. Samples of water were taken three times every day, and the samples of each day were analysed separately with regard to the matter sus pended, as well as to the quantity of chlorine, ammonia, nitric acid, and organic substances. Besides, 22 complete analyses of different types of water, and 12 of ooze, were made. The water passing through the Elbe at Tetschen proved to be 9,903,510,660 cubic metres during the year October 15, 1876, to October 15, 1877), which contained 776,309,959 kilograms of suspended or dissolved matter. During the year 1877, the amount of water run was 9,456,939,810 cubic metres, which contained 36,557 metrical tons of K2O, 69,631 tons of Na10, 266,081 tons of CaO, 48,915 tons of MgO, 120,553 tons of SO3, 83,336 tons of chlorine, 778 tons of ammonia, and 11,196 of nitric acid. As to the sources of these immense quantities of mineral substances, Dr. Ullik points out that the amount which is supplied by waste water of manufactures and sewage is usually over-rated. Thus, if the well-known sulphuric acid manufacture at Aussig would pour all the acid it produces into the Elbe, it would give only 5000 tons of SO3 per year, that is, only the 24th part of sulphuric acid anhydride contained in the waters of the river. The amount of mineral substance poured into the river by all the breweries of Bohemia would give only 401 tons per year, that is, the 1562nd part of all the minerals contained in the Elbe water. And, if all mineral substance contained in the sewage from the 5,000,000 inhabitants of Bohemia would reach the Elbe, it would yield only 33,250 tons, that is, 1-20th of what is really contained in the water of the river. Therefore, it is obvious that the chief source of these substances in the riverwater must be sought for in the supply brought in by springs.Dr. Siegmund Günther contributes to the same volume an interesting notice on the "Algorithmus Linealis," by Heinrich Strömer, which appeared in 1512, being one of the products of the revival of taste for mathematics which characterises, in Germany, the beginning of the sixteenth century. The same volume contains an elaborate paper on the Christian Calendar and on the methods of improving it, by Dr. W. Matzka; and a notice on the electrical clock of Rebicek, by Dr. A. Waltenhofen. It is worthy of notice that all papers that appear in the Abhandlungen are written in German, and are sold by the Society as separate pamphlets. The Sitzungsberichte, or Proceedings, contain such a mass of valuable papers that we can notice only the more important of the volume for the year 1879) papers by Dr. S. Günther, on the them. They are especially rich in mathematics, and we find (in application of orthogonal co-ordinates to one problem of the potential theory; on the normals to parabola, by Dr. K. Zahradnik; a very interesting paper by Prof. Carl Pelz, on the construction of radii of curvature of conic sections, all considered as mere corollaries of one theorem of Steiner; and several papers, by Dr. Franz Studnicka, concerring the theory of determinants and polynomes; and by Prof. J. Solin, on graphical integration.; Prof. A. Safarik contributes a paper giving the results of his observations on the Transit of Mercury on May 6, 1878. After having compared the photographs of the sun during the years 1875 to 1878, with observations on storms at Greenwich, Prague, and Vienna, Prof. Zenger arrived, as is known, at the conclusion that the 12'6 days' periodicity of "storms" on the surface of the sun had the effect of producing the same periodicity in the appearance of tornadoes in the West Indian and of typhoons in the Indo-Chinese Seas. Now, he discusses the storms noticed at Windsor (Australia) during the years 1863-75, and discovers in their appearance the same periodicity; the average deviations from it for the 29 duodecades of each year, being mostly but fractions of one day. But it must be observed that, for calcu lating the average error of these deviations, Prof. Zenger not only does not make use of the methods of least squares, but takes into account the signs, positive or negative, of the deviations, which method considerably diminishes the errors. Discussing Quetelet's tables of falls of meteorites, he arrives at the conclusion that these last also show the same periodicity. An elaborate paper, by Prof. Augustin, gives the results of thirtyeight year's observations of temperature at Prag, the averages being: winter, -0°56 Cels.; spring, 8°77; summer, 19° ́01; autumn, 9o60; year, 9°18. Several communications are devoted to mineralogy, and we notice among them the papers of Prof. Krejci on the crystallisation of quartz, and on the homomorphism of Sphalerite, Wurtzite, and Greenokit; on transformation-symbols, by Dr. N. Daubrawa; and on minerals from the Kuchelbad diabase, by MM. Preis and Urba. The papers on paleontology, geology, zoology, and botany, mostly deal with the fauna and flora, fossil or existing, of Bohemia itself. Dr. Ant. Fric gives a list of all fossil animals found in the coal and limestone of the Permian formation in Bohemia; whilst only two species were known from this formation in 1868, M. Fric's list includes no less than 87 species, mostly labyrinthodonts and fishes. Dr. O. Novak publishes his researches on hypostoms of trilobites; and Dr. O. Freismantel contributes three papers: on Nöggerathias of the Bohemian coal-fields; notices on the Nöggerathia, Stbg., Noggerathiopsis, Fstm., and Rhiptozanistes, Schmalh., and the description of a new Calamaria, Discinites bohemicus. M. K. Taranek gives a description of Diatomaceæ from Bohemian marshes; Dr. J. Schöbl publishes the results of his researches on the reproduction of Isopod crustaceans; and Dr. Ullik, the results of several analyses of Bohemian waters. In the Ethnographical Department we notice a paper by Dr. Jirecek, on Walachians and Mauro-Walachians, according to documents found at Ragusa. The next volume of the Sitzungsberichte, for the year 1880, is as rich as the preceding one. Dr. F. Studnicka continues his researches on the theory of determinants, and describes a new property of them, already observed by M. Catalan; and M. F. Mertens gives a new geometrical application of the rule of multiplication of determinants. Dr. A. Seydler studies the movement of a point oa given curves and superficies. In the domain of physics we notice but one paper, by Dr. K. Domalip, on the alternating discharges of electricity in rarefied space, in which paper the author deals especially with luminous backcurrents. The researcees of Prof. W. Zenger on the 12'6 days' periodicity, are continued in this volume. He remarks that this period is equal to one-half of the duration of each rotation of the sun, and tries to prove that the earthquakes in Southern Italy, from 1349 to 1873, as given by Prof. Suess, also fell on such days as closely coincide with the 126 days' period. He discovers the influence of the same periodicity in the dates of the passage of comets, from A.D. 371 to 1864, through their perihelium, as well as in the dates of meteoric showers. In further papers he tries to establish that the same periodicity might be discovered as to the maxima and minima of atmospheric pressure, of temperature, &c., and of magnetic disturbances. Finally, he shows that the sidereal durations of the revolutions of all planets are but multiples of the half rotation of the sun, and he finds that the same number appears also in the lengths of the months of the moon and of the satellites of Jupiter, Saturn, and Uranus. He concludes that "the cause of the movements in our solar system must be sought for in the rotation of the sun," and that all phenomena of gravitation, magnetism, and electricity are but modifications of the same cause which occasions the rotation of the sun. Dr. F. Augustin contributes a paper on the climate of Prag, being a résumé of the meteorological observations made since 1840, and another paper on the influence of clouds on the diurnal march of temperature at Prag. Among geological papers we notice: the communication by Dr. Fric on the discovery of fossil remains of a bird, Cretornis Hlavaci, in the chalk of Bohemia ("Iserschichten"); the description of a new Tertiary Batrachian, Paleobatrachus bohemicus (H. v. Meyer), from the brown coal at Böhmisch-Kamnitz, very similar to the Paleobatrachus Goldfussi, but different from it in the structure of several parts of the skeleton. M. Carl Heistmantel contributes two papers on the fossil flora of the Hangend-ridge of the Kladno-Rakonitz coalbasin, characterised by the abundance of Filices, Alethopteris Serii, and Cyatheites arborescens, being most common, and appearing in masses, whilst the Sphenopteris is scarcely represented, the Neuropteris, so characteristic of the lower deposits, completely disappears, and the Lepidodendrons become very rare. The group of Leiodermaria becomes, on the contrary, most usual, and acquires a new representative in the Permian Sigillaria denudata, Göpp., whilst Conifers become more numerous. The flora acquires thus a decidedly Permian characMr. J. Woldrich contributes a paper on the diluvial fauna at Sudslavic, close by Vimperk; it bears a decidedly northern character, as it contained remains of Myodes torquatus, Nyctea nivea, Leucocyon lagopus, Fætorius Erminea, Lepus variabilis, Arvicola nivalis, A. gregalis, Lagopus alpinus, &c. Prof. A. Belohoubek gives an interesting sketch of the influence of geological structure on the chemical composition of water in very many springs and wells from different geological formations : old gneisses, Huron, Silurian, Carboniferous, Permian, Chalk, Tertiary, and Diluvium in Bohemia. The best water, as far as can be concluded from M. Belohoubek's researches, which le considers himself as only preliminary-is given by the Gneiss, Permian, and partly also by the Chalk; the worst, by the Carboniferous and Silurian. Dr. Vejdovsky gives a list of Rhizopods inhabiting the wells at Prag, several species of Amaba, Centropyrix, Euglypha, Trinema, &c., being characteristic for special wells. M. Taranek gives a description of Diatomaceæ at Warnsdorf. Prof. J. Dedecek gives a sketch of Bohemian Polytrichaceæ, and deals in another paper with the distribution of Hepatic mosses in Bohemia. ter. In the Annual Reports we notice, besides the public lectures read at the annual meetings, a most useful, complete biblio. graphical indexes of works and papers published by different members of the Society since the beginning of their scientific careers. UNIVERSITY AND EDUCATIONAL CAMBRIDGE. From the annual report on the local lectures in populous centres, we learn that 12 out of 23 courses of lectures in the Michaelmas Term of 1881, and 10 out of 20 courses in the Lent term of 1882, were on scientific subjects, and were delivered to audiences amounting in all to 1042 persons in the former term and 645 in the latter. This refers only to the work exclusively conducted from Cambridge, without including the courses of lectures in London and in the counties of Durham and Northumberland, which are also largely under the influence of the Cambridge system. University College, Nottingham, has applied to be affiliated to Cambridge. A further report of no progress has been made by the Sedgwick Museum Syndicate. It is estimated that 14,7167. is the present value of the investments and balances of the Memorial Fund. All that can be said as to the prospects of building is that further acquisitions of sites near the new museums make satisfactory proposals more possible. Prof. Hughes has addressed a letter to the Vice-Chancellor showing that a considerable proportion of the funds for building the present Woodwardian Museum and Library was sought and given expressly for a geological museum, so that the University may fairly be expected to find 15,000l. as the value of the present museum if it takes possession of it for the use of the Library. The first part of the Natural Sciences Tripos has placed 24 men in the first class, 20 in the second, and 10 in the third, while 7 receive an ordinary degree, and 5 are excused the general examination. Six lady students are formally classed, the three in the first class being Girton students. Thus we have the unprecedented total of 72 names in one tripos list in natural science at Cambridge. Of those in the first class, Trinity and Christ's Colleges furnish 6 each, St. John's 5, Caius and King's 2 each, and Emmanuel and Clare and the non-collegiate students one each. UNIVERSITY COLLEGE, LONDON.-Mr. L. F. VernonHarcourt, M. Inst. C. E., has been appointed Professor of Civil Engineering and Surveying. Mr. Kennedy retains the Professorship of Engineering and Mechanical Technology. SCIENTIFIC SERIALS Annalen der Physik und Chemie, No. 5.-On the relations between galvanic polarisation and the surface-tension of mercury, by A. Koenig.-On the work of external forces furnished in a closed circuit, by R. Colley.-On galvanic polarisation, and on the Smee element, by W. Hallock.-Theory of circulatory and elliptically-polarising media, by E. Ketteler.-On the change of the colour-tone of spectral colours and pigments with decreasing intensity of light, by E. Albert.-On the influence of deformation on electric conductivity, by A. Witkowski.-Researches on the height of the atmosphere and the constitution of gaseous heavenly bodies, by A. Kitter. Journal de Physique, May.-Electro-chemical figuration of equipotential lines on any portions of a plane, by A. Guébhard -Note on the tangent-compass, by M. Mascart.-Variation of the ccefficient of viscosity with the velocity, by B. Elie.—Apparatus for showing and measuring in projection, and simultaneously, the plane of polarisation of the analyser and of the crystalline plate, by L. Laurent.-Register of the duration of rain, by M. Schmeltz. Bulletin de l'Académie des Sciences de St. Pétersbourg (vol. xxviii. fasc. 1).-Analysis of samples of water from lakes aud sources in Tibet, by Dr. C. Schmidt.-Measurements of crystals of Datolith, Amphibol, and Vanguelinit, by B. Koksharow. On the necessary degree of sensibility of magnetic variation instruments, by H. Wild.-Galvanic phenomena in the cerebrospinal axis of the frog, by J. Setschenow.-Remarks on the Amphishanids, by Dr. A. Strauch.-New researches on the hypothesis of a resisting medium, by O. Backlund.-Effects of the tension on the electrical resistance of copper-wires, by O. Chwolson. WE notice in the last number of the "Journal of the Russian Chemical Society" (vol. xiv. fasc. 4), an interesting paper by M. Radoulowitch, on the formation of peroxide of hydrogen during the oxidation of the terpenes, in which he tries to establish, contrary to the opinions of MM. Berthelot and Papasogli, that the oxidation processes manifested by the turpentine oil are not due to the presence of oxygenated compounds of nitrogen, but to the presence of peroxide of hydrogen. In the same number of the "Journal" Prof. Menshutkin gives a summary of his extensive work on the formation of ethers. M. Schwedoff contributes a paper in which he refutes the opinions as to the tails of comets being the result of the repulsive force of the sun on the matter of the comets, and especially the conclusions arrived at by Prof. Bredikhin on the subject; and M. Jouk publishes numerical results as to the temperatures of boiling of methyl alcohol and amylene. SOCIETIES AND ACADEMIES Mathematical Society, June 8.-S. Roberts, F.R.S., president, in the chair.-Messrs. J. W. Berry, A. R. Forsyth, and J. Wood were elected Members, and Mr. R. A. Roberts was admitted into the Society.-The following communications were made-On the extension of certain theories relating to plane cubics to curves of any deficiency, A. Buchheim [the object of the paper was the extension, by the use of Abelian functions, of certain theories which, in the case of plane cubics, are immediate consequences of the representation of the co-ordinates of a point of the curve as elliptic functions of a parameter. The theories considered were: (1) the theory of Steiner's polygons, and (2) Prof. Sylvester's theory of derived points (cf. Clifford's Classification of Loci ")].—On the differentiation with respect to the modulus of the amplitude of elliptic functions, Rev. M. M. U. Wilkinson.-Two notes: (1) a definite integral; (2) equation of the director circle of a conic, Prof. Wolstenholme [(2) got, in the case of oblique cartesian co-ordinates, in the form deus d'ut d2 ur cos ].-Theory of orthoptic loci, Rev. = 2 + dx2 dy's du dy Dr. Taylor [the orthoptic locus of any curve is the locus of intersection of tangents at right angles]. Linnean Society, June 1.-Frank Crisp, LL.B., treasurer, in the chair.-Mr. H. C. Burdett was elected a Fellow of the Society. Mr. H. N. Ridley drew attention to an Equisetum maximum from Swanage, having a spike of fructification surmounted by a branch bearing portion, and remarkable on account of the transition of the sporophores along with the brown acuminate leaves..-The Rev. G. Henslow exhibited malformed specimens of wallflower, of rhododendron, and of the Garden Ranunculus.-Mr. Marshall Ward read a paper on his researches on the life history of Hemileia vastatrix, the fungus of the coffee-leaf disease. The phenomena attendant thereon shows great analogy to those of the Uredine fungi. The spores, under favourable conditions, viz., moisture, a due supply of oxygen, and a temperature of 75° F., usually germinate in from twelve to twenty-four hours.-Complete infection or establishment of the mycelium in the intercellular passages of the leaf occurs about the third day after the formation of the germinal tubes. The so-called yellow spot or ordinary outward visible appearance of the disease manifests itself about the fourteenth or fifteenth day, but may be delayed; its development and course being dependent on secondary causes, such as atmospheric conditions, monsoons, age of the coffee-leaf, &c. By watching the progress of the spots it has been ascertained that the spores therefrom may be continuously produced for from seven to eleven weeks or even more. Some 150,000 spores have been estimated as present in one yellow cluster spot, and as 127 disease spots have been counted in one pair of leaves, the quantity of spores thus regularly produced must be enormous. According to the amount of diseased spots, the sooner the leaf falls; and though young leaves arise, the fruit-bearing qualities of the plant necessarily are seriously interfered with. The various sorts of coffee plant are all able to infection; the only possible remedy is the difficult one of destruction of the spores, and these are supposed originally to have been introduced from the native jungle, and rapidly spread under the favourable conditions of artificial cultivation.-Dr. Hoggan read a paper on some cutaneous nerve-terminations in mammals. He related observations on the habits of ths mole (Talpa), with reference to its nasal organ, as a special sense of touch, and of the tail as a tactile organ. The so-called " Organ of Eimer" in the mole's nose, its fibres and cells, are similar in character to the ordinary sub-epidermic nerve-cells nd their intrapidermic fibrillar prolongations. There is a probability that the inner circle of fibrils possesses the power of touch, and that the centre ones and those of the outer circle provide the sense of temperature, pain, and other sympathetic functions. The Paccinian bodies at the root of the organ probably register pressure.-Mr. C. B. Clarke read a paper on two Himalayan ferns erroneously described in the ferns of British India. A communication was made on the Ascidians collected in the cruise of the yacht Glimpse in 1881, by Mr. H. C. Sorby and Prof. W A. Herdman. Twelve species were noted, one Molgula capiformis, from near Poole, being new.—Mr. P. H. Carpenter followed by descriptions of new or little-known ComaHamburg Museum. The author institutes the new genus Eudiotulæ, being material derived from the Challenger expedition and crinus for Semper's Ophiocrinus.—Two other papers read were :— Notes on recent additions to the New Zealand flora, by Mr. Thos. Kirk, and descriptions of four new species of Donax, by Mr. Sylvanus Hanley. Physical Society, June 10.-Prof. Clifton, pre ident, in the chair. New member, Major-General Martin, R.E.-Mr. W. F. Stanley read a paper on sonorous vibrations, especially those of the tuning-fork. The larger and more visible movements of a soundingbody do not appear to be best fitted to propagate musical-sounds as was shown by placing disks on the prongs of a powerful fork, which, when vibrating, could then only be heard a short distance, whereas, by its smaller longitudinal motions, when placed on its resonator, it produced a penetrating sound. The vibration down the stem of the fork was shown not to depend upon a vibrating ventroid, as suggested by Chladni, for a fork cut in the end of a solid steel bar communicated sonorous vibrations equally well to the resonator. To set a fork in vibration it was necessary to This bow one prong only, therefore, in this case, the vibration must proceed along the prongs. A light fork I metre long was fixed in a heavy vice, and it was shown by it that vibrations passed down one prong and up the other alternately. By means of dust, ripples were shown to run down an ordinary fork in vibration. Light pieces of metal were fitted to the ends of a powerful fork, and the e immersed in mercury, the reflected surface of which was shown on a screen, where it was seen that the whole mercury surface was broken into fine ripples. It was suggested that such small waves are also perceived by the ear. By these, certain conditions of harmonics could be better accounted for, as, for example, by division in smaller waves, the rarefaction of a note in space would not suffer interference by the condensation of its octave falling in the same space and time. -Lord Rayleigh explained several of Mr. Stanley's experiments on the known theory of sound.-Mr. Walter Bailey then exhibited a model of a new "integratiug anemometer." apparatus contains a horizontal plane, in which are two slits forming a cross with arms towards the cardinal points. Each slit is fitted with a sliding-piece, and the two slides are connected by a bar; the arrangement being that of the well-known instrument for drawing ellipses. The slides carry beneath them wheels with their planes perpendicular to the slits, and passing through the pivots of the bar. The wheels rest on a horizontal disk, whose centre is beneath the centre of the cross. centre of the bar is to be connected to a weathercock which will keep it in the direction of the wind when looked at from the centre of the instrument. The disk is to be revolved by Robinson's cups. The number of revolutions of the wheels then give the integral of the resolved parts of the wind in the direction of the cardinal points. In the working model of the instrument exhibited there was an electrical arrangement connected with four indicators, one for each of the cardinal points. At each turn of a wheel a circuit was completed, and the corresponding iudicator moved. Recording instruments are to be substituted for indicators, and the amount recorded on each in a given time will be proportional to the total motion of the wind towards the corresponding cardinal point.-Mr. Lecky pointed out that a good anemometer was a great desideratum at present. The Society meets at Oxford on the 17th, and South Kensington on the 24th of this month. The Anthropological Institute, May 23.-General Pitt-Rivers, F.R.S., president, in the chair.-A paper was read by the Right Hon. Sir H. Bartle Frere, Bart., on systems of land tenure among aboriginal tribes of South Africa." The author indicated the points regarding which further inquiry is needed, and urged the importance of recording observations whilst it is still possible to obtain information from sources which in the course of another generation may be closed for ever by the extinction of races. The Zulu title to the lands in South Africa rests simply on force, the land being his property only so long as the occupant can hold it by himself, or with the assistance of the chief who protects him. The tenure cannot be transmitted by inheritance without being constantly sapped by the influence of two institutions universal among the Zulus, viz., polygamy and slavery. Christianity has a special bearing on the subject of land tenure, because it is mainly through its agency, indirect as well as direct, that we may look for such changes in the customs of the races of South Africa as may civilise and settle them, and put an end to the ceaseless wanderings which have tended so powerfully to keep them in a state of ever-recurring barbarism. The author's impression was that the advancement and civilisation of the native tribes of South Africa depend greatly upon the extent to which individual tenure of property can be extended, whilst some patriarchal authority such as seems inherent in the head of a family or kraal is recognised, and invested with some sort of magisterial and judicial functions, sufficient to meet the everyday exigencies of village life. The President opened the discussion with some remarks on the peculiarities of land tenure in various parts of the world, and was followed by Dr. Rae, Mr. Hyde Clarke, and Miss Buckland.-On the motion of Prof. Flower, a cordial vote of thanks was given to the president and Mrs. Pitt-Rivers for their kind ess in allowing the meeting to be held at their house. EDINBURGH Royal Society, June 5.-The Right Hon. Lord Moncrieff, president, in the chair.-Obituary notices of Dr. Lauder Lindsay, Mr. David Smith, and Prof. Peirce of Harvard, were read.The Council announced the award of the Keith Prize for the Biennial Period 1879-81, to Prof. Chrystal, for his paper on the differential telephone, which is published in the Society's Transactions (1879-80), and gives a new, simple, and accurate method of measuring capacities and co-efficients of mutual and self-induction (see NATURE, vol. xxii. p. 331); and of the Neill prize, for the triennial period 1877-80, to Mr. John Murray, for his paper on the structure and origin of coral reefs and islands, communicated to the Society on April 5, 1880, and printed (in abstract) in the Proceedings of that date (see NATURE, vol. xxii. P. 351).-Prof. Tait conmunicated Part II. of his paper on mirage. Having formerly shown that the observed phenomena could be explained in a general way by assuming a certain relation to exist between the refractive index of the air at any point, and its situation between two planes of approximately stationary density; the author, in his second paper, proceeded to investigate the conditions more carefully, so as to find, if possible, a distribution of atmospheric density which should be at once probable, and produce mirage phenomena the same in all important particulars as those observed by Scoresby, Vince, and others, and at the same time be capable of easy mathematical treatment. Two horizontal strata of uniform but different densities, separated by a stratum whose density varies continuously from the one to the other, were found to give results in close agreement with observation. That a stratum of air should remain of practically uniform density through even a comparatively small height requires a lowering of temperature to compensate for the dimi nution of pressure as the height increases; but this rate of change of temperature Prof. Tait showed was not greater than had been observed in balloon ascents. With given thicknesses of strata, there was a critical minimum distance at which mirage could be obtained. For greater distances there were three images, two direct and one inverted. The inverted one was always larger than the lower direct one, but only appreciably so when the distance of the object approached this critical minimum value, for which the phenomenon known as "looming" became evident. The second direct image is usually much the smallest, being, except at distances near this same critical distance, so small as to be practically invisible. This seems fully to account for the comparatively few instances in which the three images have been observed. Multiple inverted images, as observed by Scoresby, were explained as due to thin successive layers of varying density at different heights. It was shown that Wollaston's illustrative experiment, in which three images are produced, is not quite analogous to the state of affairs which produce them naturally. In order to make it so, the tank must be greatly diffusing fluids greatly diminished; so that the lays may enter increased in length, and the difference of density of the interand leave the transition stratum by its lower side, and not by its ends. The rest of the paper showed how Wollaston's arrangement could be simply and accurately applied to measurement of rates of diffusion.-Mr. Milne Home communicated the Eighth Report of the Boulder Committee, This dealt mainly with the boulders around Ben Nevis, which had been examined by Prof. Heddle, Prof. Duns, and Mr. Livingston of Fort William. BERLIN Physical Society, May 26.-Prof. du Bois-Reymond in the chair.-Prof. I andolt showed a new polarisation-apparas, whose polarising part is formed according to the method of M. Cornu, modified by Herr Lippich, and which has this advantage over others, especially, that it is not mounted on a foot, but on a solid base, whereby bending and torsion of the tube which holds the liquid are avoided. This tube is inclosed in a cylindrical envelope, in which water of any desired temperature can circulate. By a simple lever movement, the tube filled with the experimental liquid can at any time be directly replaced by an empty tube, and conversely; so that the zero point can be controlled as often as desired. In its present form, the apparatus is pretty perfect for scientific research es; further improvement must be directed principally to the production of a good lightSome proposed alterations of the apparatus, now in hand, will afford the opportunity of examining vapours in reference to their rotatory power.-Dr. Hagen reported on experiments for measuring the vapour-tension of mercury at different temperatures. He first indicated briefly the apparatus Regnault used, and the results obtained with it, by that physicist. The values given by Regnault are met with in all text-books of physics; yet they differ very considerably from the amounts found by Regnault in his experiments, and these do not agree together. The author, therefore, undertook a new determina source. tion of these values. The apparatus consisted of a U-shaped tube, having at the lower part a long straight tube, united to it by fusion, while above, either branch terminated in a tube twice bent at a right angle, and closed at the lower end. By means of a Hagen air-pump this tube-system was gradually evacuated to a pressure of 1-12,000,000 mm. mercury, and the long straight tube opened under mercury at the lower end. The mercury rose in both branches of the U-tube to barometric height. One of the lateral ends of the apparatus was now kept constant at o°; while the other was first cooled to - 42°, and then heated to various temperatures; each time the position of the mercury in the two branches was observed with a cathetometer, and the difference of their heights gave the vapour-tension. The values so obtained for the vapour-tension of mercury_were less for all temperatures than those given by Regnault. Thus, e.g. Herr Hagen found the tension at 0° 0°015 mm., Regnault 002; at 20°, Hagen o'021, Regnault o'037; at 100°, Hagen 061, Regnault 0.75; at 200°, Hagen 16, Regnault 19.9 mm. Though the values now found have no claim to absolute accuracy (owing to the difficulty of taking readings with the cathetometer, through round glass), these experiments at least make certain that the Regnault values for the vapour-tension of mercury, which have passed into all text-books, are considerably too large. PARIS Academy of Sciences, June 5.-M. Jamin in the chair.— The following papers were read :-On double salts prepared by fusion, by MM. Berthelot and Ilosvay.-Report on the expedition to Cape Horn, by H. Milne-Edwards. This meteorological mission, to start soon, for a year's sojourn at Cape Horn, will have two medical men, Drs. Hyades and Han, who have undertaken to collect and make observations as the Academy may indicate. A Committee of the Academy has urged the Government to add a preparer of collections, and nominated M. Sauvinet for this post; total additional cost 3625 fr. The wish is expressed that specialists in zoology, botany, and geology could have been appointed; but the resources did not allow of this. Zoological instructions drawn up for the members of the Cape Horn Mission by M. Alph. Milne-Edwards. Special attention should be given to the large mammalia-seals, seaelephants, otaries, cachalots, &c., some of which are rapidly disappearing. Various penguins and other sea-birds call for study; the fishes are imperfectly known, and a good harvest from dredging operations may be looked for.-The true puceron of the vine (Aphis vitis, Scopoli), by M. Lichtenstein.-History of standards of the metre, by M. Wolf.-On the waves produced by the emersion of a solid at the surfac of a quiet wave, when there is occasion to take account of two hori zontal co-ordinates, by M. Boussinesq. On the boilingtemperature of selenium, by M. Troost. Employing a method described March 29, 1880, he arrives at the figure 665° C. for pressure near 760 mm. It is shown that glasses of small fusibility, such as Bohemian and certain French glasses, may be kept at that temperature without deformation, and so used for long chemical reactions.-On a calorimeter dependent on cooling, by M. Violle.. This is for use where the initial temperature is between ICO° and 400° or 500°. It consists of a small, narrow-necked bottle of thin glass, with double envelope, and a vacuum produced in the interval before closure. Through the neck is introduced a thermometer and a stirrer.-Determination of the specific heats of small quantities of substances, by MM. Thoulet and Lagarde. The method is designed for pure mineral species (o'I gr. to o'5 gr.). Its principle is this: If two thermoelectric junctions be put in tubes holding a liquid of known specific heat (eg. water, or oil of turpentine), one may measure, by the deflection in a galvanometer, the rise of temperature resulting from immersion in one of the tubes of a body raised to a known temperature, and compare it with that in a second experiment made with a typical body (e.g. copper). The method (which is illustrated by a figure) is shown to be exact.On a new condensation-hygrometer, by M. Crova. A small tube of nickel-plated brass, carefully polished within, is closed at one end with ground glass, and at the other with a lens of long focus, through which one looks along the tube towards a light-source. Through two terminal tubulures, the air to be examined is drawn through the tube, which is cooled by means of sulphide of carbon traversed by an air current in a metallic envelope round the tube. The changes of aspect in the tube at the temperature of saturation, enable one to estimate the dew-point to one-tenth of a degree. - Law of freezing of The aqueous solutions of organic matters, by M. Raoult. molecules of different organic matters, dissolved in the same quantity of water, cause sensibly the same retardation in its freezing-point.-Method for determination of the ohm, by M. Joubert.-Influence of the positive electrode of the battery on its chemical work, by M. Tommasi.-On oxychlorides of zinc, by M. André.-Action of sulphide of carbon on silicium, by M. Colson.-Preliminary note on didymium, by M. Cleve. This points to the existence of a new element accompanying didymium. The author proposes to designate it provisionally by the symbol Diß; it is characterised by the strong line = 4335 ̊5.—On - On a new monochlorinated camphor, by M. Cazeneuve. spontaneous fermentations of animal matters, by M. Béchamp. He reviews past researches, and indicates a number of deductions from them.-MM. Cazeneuve and Daremburg called attention to the fact of proof having been given by them in 1874, that in general all the substances called colloid by Virchow and his school, strongly decompose oxygenated water.-On the nervetissue of the spinal cord, by M. Ranvier.-Experimental attempt at anatomical localisation of symptoms of toxical delirium in the dog, by M. Danillo.-Essence of absinthe was injected into dogs. The integrity of the optic thalami is not necessary for production of toxical delirium. The cortical region throughout is exclusively concerned.-M. Larroque furnished some data regarding the thunderstorm of May 30. In some regions there was torrential rain, in others hail.-On a new combination of the lenses of the microscope, by M. Zenger. With a great focal distance he obtains a magnification equal to 2000. VIENNA Imperial Academy of Sciences, May 11.-L. I. Fitzinger in the chair.-H. Hammerl, contributions to the knowledge of the formation of hydrates of salts.-P. Wesselsky and R. Benedikt, on some nitro-products from the pyrocatechin series.-F. Exner, determination of the ratio-electrostatic and electromagnetic absolute unit.-A. Tschinkel, communication on experiments relating to the action of electricity on the growth of plants.-F. Heger, continuation of the fifth report of the Prehistoric Commission on two excavations near Chotzen (Boh.) and near Hallein (Salzburg).-G. Bruder, contributions to a knowledge of the Jurassic deposits in Northern Bohemia.-E. Stefan, on the lines of force of a field symmetrical round an axis. May 25.-Anniversary Meeting.-E. v. Bruecke was elected vice-president in room of V. Burg.-In the Mathematical class, Theodor v. Oppolzer (Vienna), Julius Wiesner, and Emil Weyr Vienna, were elected Members.-Fr. E. Schultze (Gratz), V. v. Ebner (Gratz), M. Neumayr Vienna), L. v. Pebal (Gratz), H. Durège (Prague) Correspondents, Friedrich Woehler (Göttingen) Honorary Member, L. Pasteur (Paris) G. G. Stokes (Cambridge) and T. Lovén (Stockholm) foreign correspondents.-The meeting was opened by the curator of the Academy, Archduke Rainer. The reports for the past year were read by the general secretary, Prof. Siegel and the secretary of the Mathematical Class, Prof. Stefan. Then Prof. E. Much (Prague) gave an address on the economic nature of physical research. |