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same as that of the axes. The statuettes consist of copper 903, tin 74, iron 2'1; the axes, of copper 87'4, tin 12'0, lead 05, with traces of iron.

IN the new number of Petermann's Mitteilungen Prof. Vambéry has a valuable paper on the geographical nomenclature of Central Asia. He gives a list of names, his spelling of which may safely be accepted as authoritative. The list is to be extended on some future occasion.

AT a recent meeting of the Field Naturalists' Club, Victoria, Mr. C. G. W. Officer read a paper on supposed human footprints on.Eolian rocks at Warrnambool. In introducing the subject, Mr. Officer described in detail the formation and nature of the sand dunes, and their connection with the underlying strata, as shown by the similarity of the stone now being quarried there. From an analysis of the stone made by Mr. Avery, of Queen's College, it appears that it contains about 94 per cent. of carbonate of lime. Last December a slab was discovered in one of the quarries bearing impressions which suggested that they were made by human beings. This slab was secured by Mr. Archibald, and placed in the Warrnambool Museum. The determination of the age of the rocks is of importance, and from the evidence of subsidence and elevation which have probably taken place since the impressions were made, Mr. Officer is of opinion that a considerable lapse of time has occurred since the rocks were laid down, and he suggests that the impressions were made by two individuals sitting close together and somewhat obliquely to each other. Mr. J. Dennant, discussing the paper, pointed out that it was necessary to be very guarded in accepting any but the strongest evidence on such questions as those relating to the supposed footprints. Amongst limestone rocks it was well known that mimetic forms were common. In the Eolian rocks of Cape Bridgewater occurred the so-called fossil forest, which the casual observer could hardly be persuaded to believe was an accidental resemblance, and nothing more. At the same time Mr. Dennant congratulated Mr. Officer on having produced an interesting and highly suggestive paper. The rocks were well described, and whether his conclusions concerning the impressions were accepted or not, he had succeeded in drawing renewed attention to one of the most striking formations in Victoria.

MR. J. B. TYRRELL, Ottawa, of the Canadian Geological Survey, has spent the last two summers in examining the shores of Lake Winnipeg, Winnipegosis, and Manitoba; and he has issued a few notes on his observations, in advance of a more

detailed report to the Survey. Speaking of striation, Mr. Tyrrell refers to many distinct and characteristic glacial stria which show that during the Ice Age a great glacier, or lobe of the Laurentide glacier, moved south-south-eastward across the lacustral plains of Manitoba, along the valley of Red River to the height of land, and onward to near Des Moines, Iowa, sending off branches up the valleys of Swan and Red Deer rivers. The total length of this glacier or lobe, from the north end of Lake Winnipeg to its extreme southern limit in Iowa, would be about 850 miles. With reference to moraines, Mr. Tyrrell says the highest at present known in Northern Manitoba are those capping the summits of portions of the Duck and Riding Mountains, with altitudes of 2500 to 2700 feet above the sea, or 1800 to 2000 feet above the surface of Lake Winnipeg. On the shores and islands of Lake Winnipeg a distinct moraine has lately been recognized. In a section on shore lines Mr. Tyrrell describes Kettle Hill, on the south side of Swan Lake, as one of the most interesting monuments of ancient shore phenomena in the whole district. Swan Lake has an estimated elevation of 27 feet above Lake Winnipegosis, or 855 feet above the sea; and the hill, which appears to have been largely composed of Dakota sandstone, rises 275 feet above it. On the face of this

hill are five distinct terraces, representing six different shore lines, at elevations of 920, 955, 995, 1015, 1070 feet above the sea, those at 955, 995, and 1070 being most strongly marked, the last being the most distinct.

MR. D. MORRIS, Assistant Director of the Royal Gardens, Kew, lately sent to the Entomologist's Monthly Magazine for identification specimens of a Coccid, supposed by him to be Icerya Purchasi, received from St. Helena. They were found there on some rose bushes which had been imported from the Cape of Good Hope. In a note in the new number of the Entomologist's Monthly Magazine, Mr. J. W. Douglas says there is not the least doubt that the specimens received are females of Icerya Purchasi; and he adds that if the brood of which they are samples be not extirpated at once by burning all the plants on which they exist, so as to destroy all eggs and young larvæ, they will form the beginning of a pest that must be intensely serious in such a small island. The probability is that they were introduced as eggs or larvæ, and so escaped observation.

THE fourth volume of the entomological publication issued by the Russian Grand-Duke Nicholas, under the title of "Mémoires sur les Lépidoptères, rédigés par N. M. Romanoff,' contains a very valuable work by M. Gr. Grum-Grshimailo"Le Pamir et sa Faune lépidoptérologique," with twenty-one coloured plates and a map of the Pamir. Besides its special entomological part, the work contains some interesting deductions concerning the geological history of the Pamir. The author came to the conclusion, confirmed afterwards on geologi. cal grounds by Prof. Mushketoff, that during the Miocene period the Pamir plateau and Tibet formed a continent which rose isolated above the great Tertiary sea. It was separated at that time from the Tian-Shan Mountains, but seems to have been connected with the Altai Mountains, probably through the BeiShan highlands. The hypothesis seems probable on orographi cal grounds as well—the Pamir and the Altai Mountains belonging to the great plateau of Asia of which the Great Altai is one of the border ridges, while the Tian-Shan belongs to the series of ridges parallel to the border ridges, and is separated from them by deep valleys, which must have been filled by the waters of a Tertiary sea. The same structure may be observed in East

Siberia also.

LISTS of the Macro-Lepidoptera and birds of Winchester and the vicinity have been compiled by members of the Winchester College Natural History Society, and have now been published evidently taken great care to be accurate, and their work together in the form of a pamphlet. The compilers have

cannot fail to be of service to students of natural history in the locality. Mr. A. W. S. Fisher, who signs the preface to the list of Lepidoptera, points out that it contains 425 species, which have all occurred within six miles of Winchester College. Mr. S. A. Davies, in the list of birds, indicates by an asterisk the cases in which the birds recorded have been bred within a radius of a quarter of a mile of the College. In most cases, Mr. Davies himself has found the nest within the last three years.

ACCORDING to Hering's views, the optical stimulation-value, or "valence," of a coloured radiation, is made up of one white and one or two colour valences (the greater the former, the less the saturation). And he has sought to measure the white valences; one useful means lying in the fact that to an eye kept long in the dark all coloured rays of a certain low intensity seem colourless, but of very different brightness. Hering has lately had an opportunity of taking measurements on a person having sight, but totally blind to colours (a very rare case). This was a music-teacher, twenty years of age. The experiments (described in Pflüger's Archiv) brought out the fact that

the spectrum of the totally colour-blind is considerably
shortened; in this case it began about 665 μ, and ceased about
420 μ. The greatest intensity was in the green. Further, it
appeared that all coloured radiations had the same relations of
brightness to each other for the adapted normal eye as for the
eye
of the colour-blind person. With any two spectral lights,
again, an equality of sensation could be produced in this
person, when a suitable ratio of intensities was established;
and when the two different colours, which seemed equal to the
colour-blind, were examined with the normal eye (adapted to
darkness), it was found that these two colours had equal white
valences. In general, the brightness-curve of the spectrum of

the colour-blind had the same course as the curve of white
valences for the normal eye. These facts are regarded as a
strong confirmation of the author's views.

THE Morgue in Paris now has a medico-legal institute attached to it, with courses of lectures, &c. The need of frigorific apparatus has been long felt, and in a recent competition for the supply of it, the arrangement proposed by MM. Mignon and Rouart (Carre's system) has been selected by a Committee, and will be worked out. According to the Report (Bulletin de la Soc. d'Encouragement), Prof. Brouardel imposed three conditions: (1) to submit bodies, on arrival, to a temperature of -15° to -20° C. (this on account of bad conductivity and slowness of freezing internally, also the advanced state of decomposition often met with); (2) to take them into a room with temperature varying between - 4° and -1°; and (3) to keep ten bodies at a temperature of -4°. Further, vibration was to be avoided, and the air kept still. The method of Carré, it is known, depends on changes in an aqueous solution of ammoniacal gas, the gas being driven off by heat, liquefied by its press ure, vaporized, and absorbed by water. Chloride of calcium is used to transmit the cold; this liquid passing through pipes in the wooden walls of a freezing cell, into which the body is pushed on a carriage. Ten hours is enough for the largest body: it becomes hard as wood. The after-process is easier. Bodies can be kept thus more than eight months, though decomposition had begun before freezing. When an autopsy is to be made, the body is put into a case which is heated with gas burners, and after wards it may be relegated to the frozen state to be kept longer. To keep bodies at -2° in a hall, for exhibition to the public, presented special difficulties. How these were overcome may be learned from the above-mentioned Report.

THE new number of the Journal of the Marine Biological Association of the United Kingdom (new series, vol. ii., No. 2) opens with the Council's report for 1890-91 and the Director's report. The weather was extremely unfavourable for continuous and systematic dredging; nevertheless the boats of the Laboratory were constantly employed on every suitable day, and a considerable amount of material was collected. The preservation of specimens has been much more carefully attended to than formerly. One man now devotes almost his entire time to this work. The following are the other contents of the present number:-The egg and larva of Callionymus lyra, by J. T. Cunningham (with plate v.); experiments on the production of artificial baits, by Frank Hughes; the rate of growth of some sea fishes and their distribution at different ages, by J. T. Cunningham; on some Ascidians from the Isle of Wight-a study in variation and nomenclature, by Walter Garstang (with plates vi. and vii.); on the development of Palinurus vulgaris, the rock lobster or sea crayfish, by J. T. Cunningham (with | plates viii. and ix.); the reproduction and growth of the pilchard, by J. T. Cunningham (with plate x.); the distribution of Crystallogobius nilssonii, by J. T. Cunningham; physical investigations, preliminary paper, by H. N. Dickson (with plate xi.); notes on meteorological observations at Plymouth, by H. N. Dickson; notes on the herring, long-line, and pilchard

fisheries of Plymouth (continued), by William Roach, Associate Member; note on a British Cephalopod-Illex eblanæ (Ball), by William E. Hoyle; notes and memoranda.

PROF. KAUFMANN, of Liége, has issued a useful "Student" Guide" to the Liége School of Mines and Engineering, the Montefiore Electro-technical Institute, and the principal engineering firms in Liége and the environs. He quotes from an official report by Mr. Vice-Consul Menzies a statement to the effect that the advantages offered by Liége from an educational point of view do not seem to be duly appreciated in the United Kingdom. While the youth of almost all the other European nations are fairly, and in some instances largely, represented at the Liége University, the British students rarely number more than five or six at a time, and sometimes not even that.

A "Handy List of Books on Mines and Mining" has been compiled and published by Mr. H. E. Haferkorn, of the Milwaukee Public Library. He describes it as an alphabetical reference catalogue, arranged under authors and subjects, and including analytical references to the contents of important works.

MESSRS. WHITTAKER AND Co. have issued the fourth edition

of the "Working and Management of an English Railway," by George Finlay. In June 1890 the author read a paper at the Royal United Service Institution, on the transport of troops by rail within the United Kingdom. The substance of this paper he has embodied in the chapter on railways as a means of defence. To the present edition he has also added, as an appendix, a lecture (with emendations) delivered at the Society of Arts, on modern improvements of facilities in railway travelling.

MESSRS. WHITTAKER AND Co. have in the press a second edition of Dr. A. B. Griffiths's "Treatise on Manures." It is a little more than two years since the work appeared. Fifty pages of new matter have been added.

THE third edition of "Electricity, treated Experimentally for the Use of Schools and Students," by Linnæus Cumming, has been published by Messrs. Longmans, Green, and Co. The author has made such additions and alterations as seemed necessary to bring the book up to date.

A NEW edition of Prof. A. Humboldt Sexton's "Elementary Inorganic Chemistry" (Blackie and Son) has been issued. To meet the alterations in the syllabus of the Science and Art Department, the author has recast the part dealing with qualitative analysis.

THE American Association for the Advancement of Science has just issued the Proceedings of its meeting (the thirty-ninth) held at Indianapolis, Indiana, in August 1890.

PART 38 of Cassell's "New Popular Educator" has been published. Besides the illustrations in the text, it includes a good map of Spain and Portugal.

THE second series of lectures given by the Sunday Lecture Society begins on Sunday afternoon, December 6, in St. George's Hall, Langham Place, at 4 p.m., when Mr. Eric S. Bruce will lecture on "Fogs and their Prevention." Lectures will subsequently be given by Prof. J. F. Blake, Prof. Vivian B. Lewes, Prof. Percy Frankland, F.R.S., Dr. Benjamin W. Richardson, F. R.S., Mr. Whitworth Wallis, and Mr. Willmott Dixon.

THE additions to the Zoological Society's Gardens during the past week include a Barbary Mouse (Mus barbarus) from Barbary, a Chinese Blue Magpie (Cyanopolius cyanus) from China, two Brown Thrushes (Turdus leucomelas) from South America, purchased; a Vulpine Phalanger (Phalangista vulpina), born in the Gardens.

OUR ASTRONOMICAL COLUMN. MOTION OF STARS IN THE LINE OF SIGHT.-In a paper read before the Royal Society in January 1890, Prof. Lockyer described a new method of observing spectra of stars and nebula which did away with errors due to the collimator of the spectroscope not being exactly in the optic axis of the telescope owing to the flexure of the telescope tube. It consisted in using a siderostat to reflect the light of the body under observation to a vertical object-glass, whence it was converged on the slit of a fixed spectroscope. By this means perfect stability can be secured. This method has been utilized by M. Deslandres, of Paris Observatory, for the photographic determination of the displacements of lines in stellar spectra due to motion in the line of sight (Comptes rendus, November 23). Comparison spark spectra are taken above and below the spectrum of the star, and the difference of position of the lines common to the star and these spectra afterwards measured. The elements used for comparison are iron, calcium, and hydrogen, and the best results have been obtained with the first of the three. The lines in a spectrum of Sirius, taken on March 3, 1891, in this manner, exhibited a displacement which corresponded to a velocity of recession relative to the earth of 19 kilometres per second. But as the earth's motion towards Sirius at the time of observation was 20°2 kilometres per second, the approach of the star to the sun was 12 kilometres per second. The results indicate that considerable advantage is to be gained by the use of the siderostat in the study of the radial motions of stars.

THE VARIATION OF LATITUDE.-Some determinations of the latitude of Cambridge, U.S., made in 1884-85 exhibited a progressive variation, from which, however, no inference was drawn at the time. The stars observed were contained between -5° and +5° of declination, but a subsequent discussion based on more northerly stars (+5° to +50°) gave an exactly corresponding variation in latitude. Mr. S. C. Chandler, in the Astronomical Journal, No. 248, gives the results of a recent examination of his values, and from the curve connecting the residuals finds the minimum latitude to have been on September 1, 1884, and the maximum latitude on May 1, 1885, with a range of about 0"'7.

PHOTOGRAPHY OF THE ECLIPSED MOON.-During the lunar eclipse of November 15, M. Courty, of Bordeaux Observatory, took four photographs of the moon after it had entered the earth's shadow. The exposure given was about two minutes, and the disk of the moon could be easily traced on the negatives, and on some positives presented with a note by M. Rayet to the Paris Academy on November 23. M. Janssen remarked that by photographing the eclipsed moon and the full moon on the same plate, and determining the times of exposure necessary to obtain both images of equal density, a good idea of the relation of the light intensity in the two cases may be obtained.

PROPOSALS FOR A SCHEME OF CO-OPERATIVE OBSERVATION OF THE SO-CALLED LUMINOUS CLOUDS.

SINCE 1885 curious cloud formations have been seen on summer nights in both the northern and southern hemispheres, in evident connection with those phenomena which followed the great volcanic eruption at Krakatao. The intense brightness of these formations, considering the position of the sun, denoted that they were situated very far above the earth's surface. Probably these clouds consisted of erupted particles thrown to a very great height and there illuminated on summer nights by the sun.

These cloud-like formations, commonly called luminous clouds, are extremely interesting, both on account of the extraordinary height at which they have for years been moving above the surface of the earth (more than 80 kilometres) and of the movements themselves. A very important point about these clouds is that they are-so far as we yet know-visible in each hemisphere only in the summer. It is the more important that these phenomena should be carefully and widely observed, since it is believed that they are gradually breaking up, so that probably in a very few years no distinct traces of them may remain (see also O. Jesse on so-called luminous clouds, in the journal Himmel und Erde, vol. i. p. 263).

Photographic results of the researches of O. Jesse are given in

Part xl. of the Transactions of the Berlin Academy of Science for 1890, and Part xxvi. for 1891. It is very desirable that such photographs should be taken in as many different localities as possible, because from them we get the surest basis for con

But

sideration of the situation and movements of the clouds. valuable aid may be given by the co-operation of numerous observers in various regions of the earth without the aid of any apparatus.

The principal points upon which stress is to be laid in this inquiry are:

(1) By what method can the so-called luminous clouds be ordinary cirrus cloud? most surely distinguished from others, especially from the

Clouds or cloud-like formations which after sunset and before

sunrise stand out brightly from the dark ground of the heavens, no earthly or unearthly sources of light being present on the horizon, can only produce this effect by means of their own light or else by light which they receive directly or indirectly from the

sun or moon below the horizon.

Cloud-like formations which shine at night by their own light have doubtless been formerly observed above the surface of the earth. To these formations belong not only thunder and lightning clouds, but also some polar light and meteoric phenomena.

But the so-called luminous clouds do not belong to the various species of self-luminous clouds, for finer measurements of their light are wanting, besides which the fact that they are only seen within the zone of twilight proves that the sun below the horizon is the principal source of their light.

It is well known that there are clouds within this twilight zone which resemble high mountain peaks, and which in the first stages of twilight shine in the light of the sun, though the latter is below the horizon of the observer. It is easy to determine the relation between the position of the sun below the horizon, and the height of those layers of atmosphere which receive the sun's light and reflect it.

But the laws which govern the whole course of twilight are modified when the distribution of the sunlight-reflecting particles in the atmosphere is altered to any great extent. If, for instance, numerous minute atoms produced by volcanic eruption or by the breaking up of meteoric bodies find their way into those heights. above the earth's surface in which usually the gaseous elements of the atmosphere are present in a very scattered form, it may happen that such a layer, which reflects the sunlight very strongly, may curiously alter the course of the twilight.

So long after sunset as the masses of air beneath such a layer receive direct light from the sun and reflect it, the observer will not distinguish any deviation from the usual course of twilight. But as soon as the further sinking of the setting sun gradually deprives the lower layers of air of the direct light, the higher layer of dust still receiving light from the sun stands out in astonishing brightness, the particles of dust having strong reflecting power, thus giving to the close of twilight the curious effect of the sudden appearance of shining clouds on the broad surface of the heavens.

The phenomena of the luminous clouds corresponded when first perceived to the above description. At present they are no longer so strong or so extensive, but only form thin whitishblue shining veils, similar in form to the so-called cirrus or feather clouds, occupying but a comparatively small part of the floor of the heavens inside the twilight segment, and in our zone mostly near the horizon. Probably, the layers are now so thin that very near and exactly above us they can no longer be

seen.

From the above considerations it is clear in what way these clouds differ from those situated nearer to us, and especially from the cirrus clouds floating scarcely more than 13 kilometres above the earth's surface. All these lower clouds appear in the later twilight grey and shadowy on a light ground, because the layers of atmosphere above them are the chief source of the remaining twilight. The luminous clouds differ too in shape and structure from the other kinds of clouds.

We must guard, however, against the error of mistaking cirrus for luminous clouds, when, in exceptional cases, the former look very bright, in consequence of receiving light either directly or indirectly from the moon or other sources. In this case, the question is decided by the relatively high degree of stability in position and form of the very high and distant luminous clouds, as ordinary clouds lie lower and nearer, and show much more rapid changes of position.

(2) When convinced of beholding so-called luminous clouds, to what points shall attention be especially directed, and what simple measurements of place, time, form, &c., shall be carried out in order to aid most usefully in the inquiry ?

In answering this question we will first consider those methods of research in which the observer can obtain no instrumental aid, except only a watch, which should be a sufficiently good timekeeper to estimate the time of observation to one minute, when compared with the correct time within eight to twelve hours after the observation.

Such simple observations are the more useful, since it frequently happens that in the well fitted up and prepared stations, observation of the phenomena is prevented by bad weather, or else that the phenomena stretch over too large an extent of the earth's surface to be included in an organized series of observations. The farther the stations are apart, the more valuable are the most simple methods. For instance, in order to get corresponding photographic observations from two stations, 35 kilometres apart, such as Berlin and Nauen, the most rigid exactness, both as to time and place, must be observed.

If, however, observations are taken in East Prussia and in the Rhine province respectively, a from twenty to thirty times larger margin of difference as to time and place can be allowed than in the foregoing case, without in any way lessening the value of the result.

So, if without preparation and instruments to hand an ob server believes he beholds luminous clouds, he must not imagine that he can render no service to science by examining them closely, for very possibly the most simple method may, taken in conjunction with other similar observations, prove to be of the greatest service.

It is desirable, too, to look out for luminous clouds at all seasons of the year, though, so far, they have only been seen in summer. In the northern hemisphere they have only been seen from the end of May to the beginning of August, with greatest frequency and brightness in the month of July.

During these weeks, usually two stars are seen simultaneously with the luminous clouds, a star of the first magnitude, Capella, and a star of the same constellation, of the second magnitude, B Auriga.

The brighter of the two stars, which is characteristic of summer nights, in the northern horizon, sets towards the end of June soon after eleven, and towards the middle of July before ten, on account of the northerly direction of the meridian, and, in North Germany, at a distance from the horizon of 10 to 12 diameters of the full moon. At almost as great a distance from this bright star, and at a not very different distance from the horizon, the second magnitude star follows towards the

west.

By estimating the distances and directions of these two stars, an excellent means is afforded of determining the outlines of a group of luminous clouds. It is only necessary to determine how great the distance of a certain part of the outline of the cloud group is from one or the other star, and in what direction this line lies with regard to one or the other star, or how far the line in question is above or below the prolongation of the connecting line of the two stars. A simple drawing of the course of the outlines and their situation with regard to the two stars is useful, even when it cannot be completed on the spot but must be finished from memory. The time at which the drawing was

made should be noted within one half-minute.

If the group of clouds should be so far from the above-mentioned two stars as to make the determinations inexact, it is advisable to determine the outlines of the clouds for a certain time in the following way. Take up a position from which the outlines of houses, trees, &c., can be seen close to the position of the clouds, and fix thus the relative position of these earthly objects to the position of the clouds by a simple drawing, describing the spot from which the observation is made in such a manner that the place occupied by the head of the observer can be found again. The lines drawn from the position of the observer to the outlines of the earthly objects, and the resulting localization of the outline of the clouds in the heavens can then be determined at once by means of simple instruments for measuring angles, or on succeeding nights by the aid of a good star chart.

It is necessary to verify the exact point of time of these observations by comparison of the watch used with the time at a telegraph office, and correction of any errors should be made to the fraction of a minute.

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In communicating these observations, the exact place at which they have been made must be accurately described.

Should a complete observation be impossible, owing to the time during which the luminous clouds are visible being too short for careful measurements and drawings or to any other cause, the observer should nevertheless communicate briefly to the Society of Friends of Astronomy and Cosmic Physics that he has seen what he believes from the foregoing considerations to be luminous clouds from a certain place, in a certain direction in the heavens, and within a certain quarter-hour.

The peculiar movements hitherto observed of the clouds in question lead to the suggestion that perhaps a period consisting of several days exists, within which one and the same group of clouds is visible at the same hour from the same place, other conditions of the heavens being favourable. Every communication as to these phenomena will be valuable in the decision of this important point, which it has hitherto been impossible to settle, owing to the uncertainty of the weather and the fewness of the observers.

Those co-operating in our branch of research who are in possession of astronomical, photographic, or other physical apparatus, will of course be able to give more exact details as to place, movement, and constitution of the luminous clouds.

Suggestions for these observations cannot be given so briefly and simply but for the sake of full and complete agreement between different observers, especially as to the point of time selected for taking photographs and measurements, members of the Society of Friends of Astronomy and Cosmic Physics are invited to communicate with O. Jesse, Steglitz bei Berlin, Albrechtsstrasse 30. This course would also be advisable in the close optical examination of the clouds with regard to the peculiar changes in strength of light and the degree and kind of self-luminosity which they perhaps send out together with the reflected sunlight.

In the night from June 25-26 of this year the summer reappearance of the luminous clouds was observed very brightly from Berlin and the neighbourhood.

More detailed particulars on the whole subject of inquiry are contained in a small paper by W. Foerster, which has been sent to all the members of the Society of Friends of Astronomy and Cosmic Physics.

UNIVERSITY AND EDUCATIONAL
INTELLIGENCE.

OXFORD.-Mr. G. C. Inge, Magdalen College, has been appointed to the Studentship offered to the University by the Managing Committee of the British School of Athens, from the Newton Testimonial Fund.

The death is announced of Dr. Evan Evans, Master of Pembroke College, who filled the office of Vice-Chancellor of the University from 1878-82.

Convocation has granted £25 towards the cost of the antiquarian researches at Chester, which are throwing great light upon the obscure period of the military occupation of Britain in the time of Agricola. Prof. Mommsen has appreciated the

value of these researches.

At a meeting of the Junior Scientific Club, Mr. A. Colefax, Christ Church, read a paper on the investigation of the change taking place in acidified solutions of sodium thiosulphate. The subject of hypnotism was treated by Mr. E. L. Collis, of Keble; and P. C. Mitchell had an exhibit, and offered some remarks concerning primitive man in the Torquay caves.

The University has published the official Calendar for 1892. The arrangement and information contained differ little from former years. We learn that the number of undergraduate members of the University has increased from 3110 to 3212. The number of matriculations in 1890 were 771, as compared with 787 in the preceding year. The number of B. A. and M.A. degrees is very nearly the same as in 1889.

SCIENTIFIC SERIALS.

American Journal of Science, November 1891.-The solution of vulcanized india-rubber, by Carl Barus. Experiments have been made by the author on the solubility of india-rubber in different solvents at different temperatures. Elastic sheet india-rubber, such as is used for rubber bands and tubing, is not fully soluble in CS, at 100° or 160°, but is quite soluble at 185°, and extremely soluble at 210°. It is also easily dissolved by liquids of the paraffin series at 200°. Various other substances

and at the same time strongly reflect rays of the same periods as those which they absorb. Thus in fuchsine the order of the colours going up the spectrum is blue, indigo, violet; then there is an absorption band, followed by red, orange, yellow. The experimental laws relating to substances of this class may be summarized as follows: (1) the rays which are most strongly absorbed, when light is transmitted through the substance, are most strongly reflected; (2) when the incident light is plane polarized in any azimuth, the reflected light is elliptically polarized; (3) when sunlight is reflected, the colour of the reflected light, when viewed through a Nicol's prism whose principal section is parallel to the plane of incidence, is different from what it is when viewed by the naked eye. The phenomena of absorption, anomalous dispersion, and the like, have formed the subject of numerous theoretical investigations by German mathematicians. It is not the object of the present paper to propose any new theory upon the subject, but to discuss and extend the theory of von Helmholtz. The theory of von Helmholtz is an elastic-solid theory, which is based upon certain assumptions respecting the mutual reaction of ether and matter. The potential energy of the system may be conceived to consist of three distinct portions, viz. W1, W, W3, of which W, is the ordinary expression for the potential energy of an isotropic elastic solid; W, is a homogeneous quadratic function of the displacements of the matter; and W, is a similar function of the relative displacements of ether and matter, and is supposed to arise from the mutual reaction of ether and matter. Having obtained the expression for the energy of the system, the equations of motion can be at once written down; and it will be found, on integrating them, that the index of refraction, μ, of light of period 7, is given by the equation—

have been used as solvents, and many remarkable results obtained. The importance of the paper may be gathered from the fact that in it is described "a method by which vulcanized india-rubber of any quality or character whatever, as well as the undecomposed or reclaimable part of rubber-waste, may be dissolved or liquefied in a reasonably short time, the solutions possessing any desirable degree of viscosity or diluteness, from which india-rubber may be regained on evaporation of the solvents."-Report of the examination by means of the microscope of specimens of infusorial earths of the Pacific coast of the United States, by Dr. Arthur M. Edwards. Seven new fluviatile fossiliferous deposits from Oregon, California, and Washington are described. -The Tonganoxie meteorite, by E. H. S. Bailey. An analysis of the meteorite gave the percentage composition: Fe 9118, Ni 7'93, Co 0:39, Po'10, and a trace of copper. The weight is 231 lbs., specific gravity 7:45, shape an irregular triangular pyramid 9 inches long by 6 inches wide by 4 inches deep. A fine figure showing numerous pittings on the surface of the meteorite accompanies the paper.-Proposed form of mercurial barometer, by W. J. Waggener.-Colour photography by Lippmann's process, by Charles B. Thwing. The results obtained seem to indicate (1) that mixed colours may be reproduced with a fair degree of accuracy; (2) that an exposure sufficiently long to give a clear image of the red is quite certain to obliterate the blue by over-exposure; and (3) that an over-exposure may completely reverse the colours, causing the original colours to appear on the reverse, and the complementary colours on the film side of the plate. -New analyses of uraninite, by W. F. Hillebrand. From the analyses it appears that the species may be broadly divided into two groups, one characterized by the presence of rare earths and the almost invariable presence of nitrogen, the other containing little or no nitrogen and no rare earths. Varieties of the former group occur in more or less well defined crystals, whilst members of the latter group are usually devoid of crystalline form. The Tertiary silicified woods of Eastern Arkansas, by R. Ellsworth Call. The investigation has led to the following conclusions (1) The silicified woods of Eastern Arkansas are all of Tertiary age. (2) They are derived from the beds of Eocene clays that underlie the sands and gravels in which they commonly occur. (3) They are silicified lignite; the process of silicification has occurred either while they were still in clays, or most often after they were removed and buried in the sands or gravels. (4) They possess as yet no taxonomic value in deter-parent medium (such as fuchsine) which has a single absorption mining the relative ages of the members of the Tertiary series.Occurrence of sulphur, orpiment, axd realgar in the Yellowstone National Park, by Walter H. Weed and Louis V. Pirsson. Mineralogical notes, by L. V. Pirsson. cimens of cerussite, hæmatite, and cassiterite, gypsum, and pennine are described.-Peridot dykes in the Portage sandstones, near Ithaca, N. Y., by J. F. Kemp.-A new locality of meteoric iron, with a preliminary notice of the discovery of diamonds in the iron, by A. E. Foote. The existence of black and white diamonds in the meteorite appears to be established by indifference to chemical agents and hardness. Carbon in the form of an iron carbide also occurs with the diamonds. The meteorite was found in Cañon Diablo, Arizona. Three figures accompany the paper.-The South Trap Range of the Keweenawan series, by M. E. Wadsworth.Geological facts noted on Grand River, Labrador, by Austin Cary.

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SOCIETIES AND ACADEMIES.
LONDON.

Mathematical Society, November 12.- Prof. Greenhill, F.R.S., President, in the chair.-The President announced the recent decease of Mr. H. M. Jeffery, F. R.S., who was elected January 14, 1875.-The following gentlemen were elected to serve on the Council for the ensuing session: Prof. Greenhill, F. R. S., President; Dr. J. Larmor, Major P. A. MacMahon, F. R.S., and J. J. Walker, F. R.S., Vice-Presidents; A. B. Kempe, F.R.S., Treasurer; M. Jenkins and R. Tucker, Hon. Secs. ; other members, Messrs. A. B. Basset, F.R.S., E. B. Elliott, F.R., S. J. Hammond, C. Leudesdorf, A. E. H. Love, S. Roberts, F. R.S., Drs. A. R. Forsyth, F. R. S., J. W. L. Glaisher, F.R.S., and M. J. M. Hill.-The following communications were made :On selective and metallic reflection, by A. B. Basset, F.R.S. It is well known that most transparent substances, which produce anomalous dispersion, exercise a strong selective absorption,

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In this equation p is the density of the ether when loaded with matter, po is the density of the ether in vacuo, and p1 is the density of the matter; is the free period of the matter vibrations, and a is a constant depending on the mutual reaction of ether and matter. If we suppose that the value 7 of 7, which makes the denominator vanish, corresponds to the double sodium line D of the spectrum, whilst a value 72, which makes μ = 0, corresponds to the hydrogen line F, u will be negative when T lies between D and F, and (1) accordingly represents a trans

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band in that portion of the spectrum. Moreover, the dispersion
is anomalous, since the value of u when 7 is a little greater than
is much greater than its value when is a little less than 7.
To explain selective reflection, I have provisionally adopted Sir
W. Thomson's hypothesis, that the ether is to be treated as an
elastic medium, whose resistance to compression is a negative
quantity, whose numerical value is slightly less than rds of its
rigidity. Under these circumstances, the amplitudes of the re-
flected light will be given by Fresnel's sine and tangent formulæ,
according as the incident light is polarized in or perpendicularly
to the plane of incidence. When is a negative quantity,
these formulæ become complex quantities of the form
and, and this indicates that reflection is total, and is
accompanied by a change of phase; moreover, since the changes
of phase, f, fi, are different, according as the incident light is
polarized in or perpendicularly to the plane of incidence, it
follows that if the former is polarized in any azimuth the re-
flected light will be elliptically polarized. From these results it
appears that the colour of the reflected light is of a greenish
yellow when viewed by the naked eye; but when it is viewed
through a Nicol, whose principal section lies in the plane of
incidence, a considerable portion of the yellow rays are refused
transmission by the Nicol, and the light under these circum-
stances is of a much richer green. Cauchy's formulæ for metallic
reflection may be obtained from Fresnel's sine and tangent
formulæ, by assuming that μ (= sin i sin ) is a complex quantity
of the form Rea; but the experiments of Jamin, and the calcu-
lations of Eisenlohr, show that the real part of u must be
negative, which requires that a should lie between 45° and
90°. In fact, for silver, Eisenlohr finds that a = 83. Lord
Rayleigh, on the other hand, has shown that, if we attempt to
explain metallic reflection by introducing a viscous term into the
ordinary equations of motion of an elastic solid, physical con-
siderations require that the real part of u should be positive;
he has also shown that a similar objection lies against attempt-
ing to explain metallic reflection on the electro-magnetic theory,

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