iron in consequence of the difference in specific gravity of the two. When the furnace is tapped, the iron runs off to the pig. bed to be cast into the well-known form. The slag is usually run

THE ELECTRICAL EXHIBITION.

66

As the

ness which in the present day characterizes nearly all engineering operations of this nature, has extended to slag handling, so that a box will sometimes hold as much as four tons of slag. When the mass is sufficiently cool to stand alone the sides of the mould are lifted off by a crane, and the bogie is drawn away to the "tip," or 66 slag mountain," by a locomotive. land covered by the "tip" is often very valuable, in some localities being worth as much as 1000 per acre, it is desirable for this reason alone that the slag should be dealt with in some other way. When the iron-works have a sea outlet, the slag is often taken away in vessels constructed for the purpose, and dropped in deep water. The difficulty here is that the big lumps, or "slag-balls," are difficult to handle. To lower them gently into the barge is too costly, and if they are shot in they are likely to start the rivetting. Hand-breaking was, therefore, had recourse to-a tedious and costly process. In order to overcome this difficulty, an ingenious plan, known as the dry core ystem, has been devised. A hollow iron casting was placed so that the slag would flow round it when run in the mould. This was done so that the slag in cooling would contract round the casting and break up into pieces small enough to be tipped into the barge without injury to the plates and rivetting. Mr. Hawdon has not found this method to be successful; but it is stated that others have followed the plan with advantage. In America a method known as slopping" is used, and undoubtedly with success. The molten slag is run on to a surface, and a large but comparatively thin cake is so obtained. When this layer is sufficiently cool, another is formed above it, and then other layers, so that the whole forms a stratified mass, with planes of demarcation between. Such a body is broken up with comparative ease. Sometimes the slag is taken away in the molten state in "boats" which are simply tanks on wheels. It is then poured away, leaving a problem for the engineers, and perhaps the geologists, of future generations to solve. There have been other methods of dealing with slag, but these we have not space to describe. Mr. David Joy, a well-known mechanical engineer, took the matter up about twenty years ago, and spent a year or two upon the problem. Some of the devices he originated were extremely ingenious, but for reasons of a commercial nature, his efforts were not continued. There are some uses for furnace slag. It is made into bricks, it is drawn into slag-wool, it is made into cement, and is broken up for ballasting railways, pitching streams, or, when made into concrete, for harbour and breakwater works. In spite of these uses, the great bulk of the 12,000,000 tons produced each year has to be tipped to waste, and the disposal of this useless by product is no small part of the iron-master's expense in running his works. It is to aid this that the apparatus before referred to has been devised by Mr. Hawdon. It consists mainly of two large pulleys, over which there runs an endless chain or a metal belt. The pulleys are mounted on horizontal shafts, parallel to each other, and placed in the same horizontal plane. The pulleys are driven by a steam-engine, and the chain is made to travel in this way. The latter is composed of solid bar links, joined by pins, and on it is mounted a continuous series of shallow pans or trays. At one end of the apparatus the stream of molten slag is directed into the pans, and, as the chain is moving continuously, each pan carries off a part of the material. The pans overhang, so that the metal will not spill on to the links. Between the two pulleys there is placed a large flat tank filled with water, and this is so arranged that the upper part of the endless travelling chain or belt dips into the water, the sag of the belt being sufficient for the purpose. There are guide rollers, but these are details which may be neglected in our explanation of principles. The slag flows into the trays just before they dip into the water, so that the molten metal is at once rapidly cooled. This has the effect of cracking the pieces so much that when they fall out of the trays-which they naturally do when the belt turns over the further pulley-into the barge or waggon, they are broken into convenient sized fragments. Mr. Hawdon claims that by this system a very large saving is effected in transporting slag, and a material of some commercial value is obtained, the pieces being of suitable size for railway ballast or concrete mixing. From what we hear of the apparatus it appears to do its work well so far. The summer meeting of the Institution will be held this year at Portsmouth, on July 26 and three following days.

Mayoress, accompanied by Mr. Sheriff Tyler, Mr. Sheriff Foster, Sir John Monckton, and many others, went to the Crystal Palace to inspect the Electrical Exhibition. After their walk round, which lasted about an hour and a half, the visitors were entertained at dinner in the large saloon off the south transept. Among the company were the Attorney-General, Sir Robert Rawlinson, Sir Frederick Abel, F. R. S., Prof. W. E. Ayrton, F.R.S., Major-General Webber, Prof. W. Crookes, F.R.S., Mr. Tesla, Mr. W. H. Preece, F.R.S., Sir James N. Douglass, F.R.S., Major-General Festing, F.R.S., Dr. Hopkinson, F.R.S., Mr. A. Siemens, Prot. Kennedy, Prof. Forbes, Prof. Robinson, Prof. Perry, Prof. Hughes, and Prof. Silvanus Thompson, F. R.S. In the unavoidable absence of the Chairman of the Crystal Palace Company, the Hon. D. J. Monson, the chair was taken by the Deputy-Chairman, Mr. G. T. Rait. After the usual loyal toasts, the Lord Mayor proposed "Success to the Exhibition." In doing so he said there was sufficient evidence to warrant him in predicting that the Exhibition would prove a very great success. He recollected how, ten years ago, the electric light occupied the minds of many people, and how at that time the light had what proved to be a very bad start. The light was then undertaken more as a speculation. This checked for a time electrical enterprise, though, in his opinion, it had done no great or permanent harm. He admitted, with some degree of shame, that in the City of London they had been very slow to move in the matter. It was possible that they might have hesitated to commit themselves to some appliance that might have been changed on the morrow. They were, however, in favour of the electric light, and the City had been handed over to the new lighting, which in a short time would be an accomplished fact.

Dr. Hopkinson, in giving "Electric Science and Industry," remarked that the reaction between these two had been very intimate.

Prof. Ayrton, President of the Institute of Electrical Engineers, who responded, said that it was impossible to imagine what progress would be made in electricity in another ten years. At present two conductors were necessary for every electric tramcar (laughter). They had anticipated his joke (renewed laughter). One conductor took the current, while the other took the current coin (laughter). It might be that in ten years street lamps would be no longer necessary, as vacuum tubes would be used for walking-sticks (laughter). The smoke plague and fog would no longer trouble us, for there would be no coal fires when we could bask in the rays of the electric field, repose in the genial warmth of an equipotential surface, and put our feet on a fender composed of horizontal lines of force (loud laughter). One suggestion he would make-that the electric light might be introduced into that room, for the warmth they had borne during the dinner had been surpassed only by the warmth of their reception by the Directors of the Crystal Palace (laughter).

Mr. R. E. Crompton, President of the Electrical Section of the London Chamber of Commerce, also responded.

Mr. E. Clark proposed "The Health of the Honorary Council and Committees of the Exhibition."

Sir F. Abel, in responding, declared that we were on the threshold of great advances in our knowledge of electricity and its applications.

Mr. W. H. Preece also responded, and congratulated the promoters of the Exhibition upon the fact that they had brought to bear upon the present position of electrical science a fierce and an impartial criticism.

Mr. Tesla acknowledged some compliments paid to him in the course of the evening.

Sir James Douglass gave "The Crystal Palace Company," and the Chairman responded.

UNIVERSITY AND EDUCATIONAL
INTELLIGENCE.

CAMBRIDGE.-Mr. J. J. Lister, of St. John's College, late Assistant Superintendent of the Museum of Zoology, has been appointed Demonstrator in Animal Morpho.ogy, in place of Mr. S. F. Harmer.

Mr. Alexander Scott, of Trinity College, has been appointed

Demonstrator to Prof. Dewar. The grace for establishing the office was opposed, but carried by 76 votes to 70.

Prof. Macalister has been appointed Chairman of the Examiners for the Natural Sciences Tripos in the present year. The Fitzwilliam Museum Syndicate report that the catalogue of the Egyptian Collection, prepared by Dr. Budge, is now ready for printing, and will forthwith be published.

SCIENTIFIC SERIALS.

THE American Meteorological Journal for December last contains six memorial articles upon the work of the late Prof. W. Ferrel, read at a meeting of the New England Meteoro. gical Society in October last. Prof. W. M. Davis states that Ferrel's view of the general circulation of the atmosphere is now accepted in its essential features by most meteorologists; and were it not for the silence regarding it on the part of some of the British school, it would be regarded as universally acceptable. But in Great Britain it finds little recognition; nfortunately, Prof. Davis thinks, for the advance of the science in this country. The essential part of Ferrel's theory, irst stated in 1859, is that an equatorial-polar convectional circulation on a rotating earth must consist chiefly of oblique winds from a western quarter, with high velocities nearly at right angles to the gradients; and that the initial high pressure about the poles, due to low temperature, will be reversed to low pressure by the excessive centrifugal force of the whirling winds, thus leaving a belt of high pressure near the tropics. He draws a sharp contrast between the general circulation and the cyclonic rculation. Both are cyclonic, inasmuch as they whirl, but one has a cold centre, and the other a warm one.-H. Helm Clayton contributes an article on the verification of weather forecasts. Among the elements to be considered he includes (1) the kind of phenomenon, e.g. cloud, rain, &c.; (2) the time of occurrence; (3) the duration of the phenomenon; (4) the intensity; (5) the length of time in advance that the phenomenon is predicted. He also describes the methods of verification adopted in some countries.-Cold waves, by Dr. A. Woeikof. The object of the paper is to disprove Prof. Russell's theory that cold waves are not due chiefly to radiation from the ground, but to extreme cooling of the upper air. Dr. Wocikof shows from observations from various sources that the cold waves are certainly due to radiation, not necessarily at the place where the ald is felt, but at a distance-in the United States to the northwest, in Europe to the north-east.

SOCIETIES AND ACADEMIES.

LONDON.

Royal Society, January 21.-" On the Mechanism of the Closure of the Larynx a Preliminary Communication." By T. P. Anderson Stuart, M. D., Professor of Physiology, University of Sydney, Australia.

The epiglottis having been displaced from its time-honoured function of closing the larynx as a lid, the paper proceeds to show how after all the larynx is closed. Briefly, the closure is effected by, on the one hand, a folding up of the margins of the entrance and an obliteration of the channel of the vestibule from the entrance downwards to the level of the glottis, and, on the other band, by the well-known movement upwards and forwards of the entire larynx against the base of the tongue-the lower part of the epiglottis intervening, but taking no active part in the process. The observations, &c., were made as follows: (1) on a man who has a large hole in the side of the neck, a result of an operation for epithelioma, through which deglutition, simple closure of the larynx, &c., can be observed proceeding in a manifestly perfectly normal manner; (2) on healthy persons examined by the laryngoscope by the author and by two professed laryngoscopists; (3) experiments on the different classes of animals; (4) the anatomy and comparative anatomy of the parts; (5) the clinical and post-mortem records of morbid conditions.

When simple closure is to be effected in man, the arytenoid cartilages, inclosed in the mucous membrane, (1) are rotated, so that the vocal processes (eventually) come into apposition; (2) glide forwards on the cricoid articular surface, so that the posterior broad part of their articular surface comes to rest on

the cricoid; (3) approach each other, so that their inner faces are, in part at least, in contact; (4) fold forwards at the cricoarytenoid joint, so that their tips come into contact with the lower part of the epiglottis. At the same time the aryepiglottic folds become tense, pulling inwards the lateral margins of the epiglottis, and so deepening its groove to receive the tips of the arytenoids and the Santorinian cartilages. Thus the entrance assumes the form of a squat T-shaped fissure, its transverse limb bounded in front by the epiglottis, behind by the ary. epiglottic folds, and its vertical or antero-posterior or mesialthe more primitive-limb by the arytenoid cartilages. The head of the T is curved concave backwards and its stem is short. A slight movement of the entire larynx upwards and forwards takes place-not nearly so much as in deglutition. The epiglottis does not actively move, and in deglutition, for instance, the bolus is seen to glide over its laryngeal surface, its lingual surface being closely pressed against the dorsum of the tongue. But all animals are not alike, and too little account has been taken of differences in the anatomy of the parts, these carrying foregoing account applies only where, as in man, the arytenoids with them, as they do, differences in their physiology. are long and narrow where they are high and broad they move more bodily forwards, and where they are low and narrow, suffice to close the orifice, and there the lower part of the i.e. small, neither folding nor movement forwards would epiglottis is permanently bent backwards, so that the contact of the arytenoids with the front wall of the laryngeal cavity is effected with a minimum of movement of the arytenoids and the true vocal cords are, as it were, under cover of a sort of hood portion of the epiglottis varies; so does the value of the moveformed by the epiglottis. The exact behaviour of the distal

The

ment upwards and forwards of the entire larynx, even in individuals of the same species. The arytenoids in their mucuous membrane thus form a valve which, when it stands backwards, closes the food-channel and drafts the air forwards into the larynx, and when it lies forwards in deglutition closes the air channel and opens the food-channel. The external thyroarytenoid muscles with the transverse arytenoid muscle, are the agents by which the before-mentioned four movements of the The aryepiglottic arytenoid cartilages are brought about.

muscles tense the edge of the aryepiglottic fold, and cross to the base of the opposite arytenoid cartilage to avert the tendency they would otherwise have to pull asunder the arytenoids' tips. As worked out in the paper, it is seen that a very large number of details in the anatomy of the larynx receive an adequate explanation by this account of the closure of the larynx, e.g. the detailed anatomy of the muscles just mentioned, the sacculus, the structure of the false cord, the crico-arytenoid joint, its surfaces and ligaments, the anatomy of the larynx and its cavity in the different classes of animals, the ephithelial lining the cavity, &c.

"Birds are extremely instructive in this connection. Here the vocal function is entirely removed from the larynx, so that the larynx has for its sole office the guarding of the entrance of the trachea. Inspection and experiment show the entrance to be closed by the arytenoid cartilages, or bones, and the thyroarytenoid muscles. Since this is their function in Birds (and the same applies to Tortoises, Lizards, Reptiles, Frogs, &c.) is it not all the more likely to be at least a function in Mammals?" The plane of the larynx at the level of the glottis corresponds to the larynx in its more primitive forms-linear when closed, lozenge-shaped when open, bounded exclusively by cartilage and In man the vocal function has been superadded: all that lies above the level of the glottis has been built on that level, and the vibrating property has been got at a physiologically cheaper rate through fibrous than through muscular tissue. For details we must refer to the paper in the Proceedings.

muscle.

January 28." Note on some Specimens of Rock which have been exposed to High Temperatures." By Prof. T. G. Bonney, D.Sc., LL.D., F.K.S.

The first described were two specimens of the microgranite of Threlkeld (Keswick): the effect of heating (probably to about 20c0° F.) had been to melt down the felspathic and the micaceous constituents, cracking, but not materially affecting, the quartz. Next, in overburnt brick (composed mainly of disintegrated granite) from Les Talbots (Guernsey) similar effects: partial melting of larger fragments of felspar in one case twin planes could be traced within the melted part. Thirdly, five specimens of melted basalt from Rowley Regis. Four of these

were glasses (one with spherulites), the fifth exhibited skeletal crystals of felspar with a peculiar grouping, rarely and imperfectly seen in naturally-cooled basalts. With these were compared two specimens of magma-basalts, obtained by the author from the Rowley mass, which exhibited a very different structure. The author suggested that this difference might be due to the absence of water from the artificially melted rock, which might also account for the rarity of tachylites in nature.

February 4.-"On the Mechanical Stretching of Liquids: an Experimental Determination of the Volume-Extensibility of Ethyl Alcohol." By A. M. Worthington, M.A. Communicated by Prof. Poynting, F.R.S.

After adverting to the three known methods of subjecting a liquid to tension, viz. (i.) the method of the inverted barometer, (ii) the centrifugal method devised by Osborne-Reynolds, (iii.) the method of cooling discovered in 1850 by Berthelot, and pointing out that the first two afford means of measuring stress but not strain, while the third gives a measure of strain but not stress, the author proceeds to describe the manner in which he had used the method of Berthelot in combination with a new

mode of determining the stress, and had succeeded in obtaining simultaneous measures of tensile stress and strain for ethyl alcohol up to a tension of more than 17 atmospheres, or 255 pounds per square inch.

The liquid, deprived of air by prolonged boiling, is sealed in a strong glass vessel, which it almost fills at a particular temperature, the residual space being occupied only by vapour. On raising the temperature, the liquid expands and fills the whole. On now lowering the temperature, the liquid is prevented from contracting by its adhesion to the walls of the vessels, and remains distended, still filling the whole and exerting an inward pull on the walls of the vessel. The tension exerted is measured by means of the change in capacity of the ellipsoidal bulb of a thermometer sealed into the vessel and called the "tonometer." This bulb becomes slightly more spherical, and therefore more capacious, under the pull of the liquid, and the mercury in the tonometer-stem falls. tension corresponding to the fall is previously determined from observation of the rise produced by an equal pressure applied over the same surface.

The

The liquid is caused at any desired instant to let go its hold and spring back to the unstretched volume corresponding to its temperature and to its saturated vapour pressure, by heating for a moment, by means of an electric current, a fine platinum wire passing transversely through the capillary tube that forms part of the vessel. The space left vacant in the tube represents the apparent extension uncorrected for the yielding of the glass vessel.

The measures obtained show that, within the limits of observational error, the stress and this apparent strain are proportional up to the highest tension reached (17 atmo spheres); but, since the small yielding of the nearly rigid glass vessel must itself be proportional to the stress, it follows that the stress and absolute strain are proportional.

By subjecting the liquid to a pressure of twelve atmospheres in the same vessel, it was found that the apparent compressibility was the same as the apparent extensibility, whence it is deduced that between pressures of + 12 and 17 atmospheres the absolute coefficient of elasticity is, within the limits of observational error, constant. Its actual value is best obtained by observations of compressibility.

The paper concludes with a description and explanation of a peculiar phenomenon of adhesion between two solids in contact when immersed in a liquid that is subjected to tension.

Physical Society, January 22.-Prof. O. J. Lodge, F. R.S., Vice-President, in the chair.-Prof. G. F. Fitzgerald, F.R.S., read a paper on the driving of electromagnetic vibrations by electromagnetic and electrostatic engines. The author pointed out that as the electromagnetic vibrations set up by Leyden jar or condenser discharges die out very rapidly, it was very desirable to obtain some means whereby the vibrations could be maintained continuously. Comparing such vibrations with those of sound, he said the jar discharges were analogous to the transient sound produced by suddenly taking a cork out of a bottle; what was now required was to obtain a continuous electromagnetic vibration analogous to the sound produced by blowing across the top of a bottle-neck. In other words, some form of electric whistle or organ-pipe was required. These considera

tions led him to try whether electromagnetic vibrations could be maintained by using a discharging circuit part of which was divided into two branches, and placing between these branches a secondary circuit turned to respond to the primary discharge. This did not prove successful, on account of there being nothing analogous to the eddies produced near an organ-pipe slit. The analogy could, he thought, be made more complete by utilizing the magnetic force of the secondary to direct the primary current first into one of the two branches and then into the other. If spark gaps be put between two adjacent ends of the branches and the main wire, then the magnetic effect of the secondary, current should cause the spark to take the two possible paths alternately. Electrically-driven tuning-forks and vibrating spirals were cases in which magnetic forces set up vibrations, but here the frequency depended on the properties of matter, and not on electrical resonance. The frequency of delicate reeds could, however, be controlled by resonance cavities with which they were connected, and he saw no reason why the same action could not be imitated electromagnetically, using an electric spark as the reed. Referring to the properties of iron in connection with electromagnetic vibrations, he pointed out that vibration of about one-millionth of a second, and, as this was a prism of steel I millimetre long had a period of longitudinal comparable with the rates of electromagnetic vibrations, the immense damping effect which iron had on such vibrations might be due to the setting up of sound vibrations in the mate

rial.

nators.

Other methods of driving electromagnetic vibrations had suggested themselves in the shape of series dynamos or alterThe polarity of a series dynamo driving a magnetic motor would, under certain circumstances, reverse periodically, and thus set up an oscillatory current in the circuit. Similar effects can be got from series dynamos charging cells or condensers. In an experiment made two weeks before, with Plante celis and a Gramme dynamo, reversals occurred every fifteen seconds. Greater frequencies might be expected with condensers. The latter case he had worked out theoretically. He had also tried experiments with Leyden jars and a dynamo, but got no result. This might have been expected, for the calculated frequency was such as would prevent the currents and the magnetism penetrating more than skin deep. Calling the quantity of electricity on the condenser Q, the differential equation for a dynamo of inductance L, and resistance r, and a condenser of capacity .r is Q = LQ,

or

LQ + rQ +

x

and the rate of degradation of amplitude depends on the factor

If, however, L be greater than r, the exponent of e becomes +, and hence Q would go on increasing until limited by the saturation of the iron or the increased resistance of the conductors due to heating. A dynamo without iron, provided one could be made to run fast enough to send a current through itself, would be likely to give the desired effect. The author thought that by making such a dynamo large enough and its armature very long, it would be possible to get a frequency of about one million. Electrostatic machines seem, however, to be more promising driving agents. Like series dynamos, their polarity depends on the initial charge, and can be easily reversed. Hitherto such machines have been inefficient mainly on account of the sparking in them, but Maxwell had shown how this could be obviated. There was the same kind of difference between electromagnetic and electrostatic machines as between Hero's engine and the modern pressure engine. Like modern engines electrostatic machines worked by varying capacity, but the effect of this variation in electrostatic machines was only to vary the frequency and not the rate of degradation. From the fact that electrostatic multipliers could be driven by alternating currents, he thought they might be made to drive alternating currents. If magnetic currents could be obtained, then electrostatic engines would easily be produced. In conclusion, the author described a modified electrostatic multiplier which he

-

bel ved offered a feasible solution of the problem. In this machine the collectors were supposed joined to the ends of the vibrating circuit, and would therefore become + and alternately. Inductors and brushes were to be so arranged that an insulating cylinder turning between them should have many + and charges distributed alternately round its periphery. By suitable adjustment these charges could be collected at the proper instants so as to keep up the vibration.-The chairman, Prof. Lodge, said the paper was very suggestive and full of interesting points. The subject of electromagnetic vibrations was attracting great attention in America in connection with the manufacture of light. Hertz's oscillations die out too soon to be satisfactory, for their duration rarely exceeds a thousandth part of the interval between consecutive discharges. The theory of dynamos charging condensers he considered extremely interesting, and thought the fact that the damping factor could be changed in sign must have tremendous consequences.-Dr. W. E. Sumpner asked a question about a method of doubling frequency of alternation recently described by Mr. Trouton, in which the armature of one alternator excites the

felds of a similar machine. Mr. Trouton had said that after once doubling the frequency it was not possible to go on doing so. He (Dr. Sumpner) thought that by adding other machines the frequency could be still further increased, and gave a proof of the fact. In reply, Prof. Fitzgerald said that adding another machine increased the Frequency by a given amount and did not double the preceding Hence to increase the frequency a thousand-fold, a thousand machines would be required, and on this account Mr. Trouton considered it impracticable. Prof. S. P. Thompson thought the paper very suggestive, and the acoustic analogies very interesting. Melde's apparatus was an instance of doubling or halving a frequency. On reading the title of the paper, he had expected hearing of a method of maintaining electromagnetic vibrations by giving occasional impulses in some such way as that in which a tuning-fork could be kept vibrating by allowing the hammer of a trembling bell to knock against it. There was another method of intensifying electric oscillations which he had only seen mentioned in a patent specification by Sir W. Siemens, who suggested using a series dynamo with a telegraph cable to augment the signalling currents. On the subject of ironless dynamos he (Prof. Thompson) desired further information. Some years ago he had made calculations and found the speed at which they would require to run was so enormous as to be beyond the range of engineering possibility. Mr. C. V. Boys, referring to the author's suggestion of using an electric spark with alternate paths to maintain vibration, said that he Ead tried whether an oscillatory spark was displaced by a magtetic field, but the displacement, even when photographed by a revolving mirror, was barely appreciable. Prof. Perry asked for an explanation of the term skin-deep magnetism." He was not previously aware that Sir W. Siemens had described a method of improving cable signalling by using a series dynamo. He himself had patented a somewhat similar arrangement. He had also made a dynamo without iron, but had not got it to work. In reply to Prof. Perry the author of the paper said that in electromagnetic vibrations the magnetic force alternates so rapidly that it could not penetrate far into the field magnet of a dynamo before it is reversed; hence the magnetism would only be skin-deep. Dr. Burton suggested that a commutator with many segments, something like that used by Mr. Gordon in his researches on specific inductive capacity, might possibly be employed for producing high frequencies. —A communication on supplementary colours, by Prof. S. P. Thompson, F. R. S., was postponed.

Entomological Society, January 27.-The fifty-ninth annual meeting, which had been adjourned from the 20th inst. on account of the death of H. R. H. the Duke of Clarence.Mr. F. DuCane Godman, F. R. S., President, in the chair.-An abstract of the Treasurer's accounts, showing a good balance in the Society's favour, having been read by one of the Auditors, the Secretary, Mr. H. Goss, read the Report of the Council. It was then announced that the following gentlemen had been elected as Officers and Council for 1892:-President: Mr. Frederick DuCane Godman, F.R.S. Treasurer: Mr. Robert McLachlan, F. R. S. Secretaries: Mr. Herbert Goss and the Rev. Canon Fowler. Librarian: Mr. George C. Champion. And as other Members of the Council: Mr. C. G. Barrett, Mr. Herbert Druce, Captain Henry J. Elwes, Prof. Raphael Meldola, F.R.S., Mr. Edward B. Poulton, F.R.S., Dr. David

Sharp, F. R.S., Colonel Charles Swinhoe, and the Right Hon. Lord Walsingham, F.R.S. It was also announced that the President would appoint Captain Elwes, Dr. Sharp, and Lord Walsingham, Vice-Presidents for the session 1892-93-The President then delivered an address. After alluding to the vast number of species of insects, and to the recent calculations of Dr. Sharp and Lord Walsingham as to the probable number of them as yet undescribed, he referred to the difficulty experienced in preparing a monograph of the fauna of even a comparatively small part of the world, e.g. Mexico and Central America, and certain small islands in the West Indian Archipelago, upon which he, with a large number of competent assistants, had been engaged for many years. The examination of the collections recently made in St. Vincent, alone, had obliged him to search the whole of Europe and North America for specialists; and similar collections from Grenada were still untouched in consequence of the number of workers being unequal to the demands upon their time. He observed that the extent of the subject of entomology was so vast that nothing but a systematic and continuous effort to amass collections, work them out, and preserve them, could place us in a position to proceed safely with the larger questions which followed the initial step of naming species: and it would only be by the steady effort of our Museum officials, not only to work at the subject themselves, but to enlist the aid of every available outside worker, that substantial progress could be made. The President concluded by referring to the losses by death during the year of several Fellows of the Society and other entomologists, special mention being made of M. André, the Duke of Devonshire, Mr. F. Grut, Mr. E. W. Janson, Prof. Felipe Poey, Sir William Macleay, Mr. H. Edwards, Mr. Robert Gillo, and Dr. J. M. J. Af Tengström.

66

Geological Society, January 27.-Dr. W. T. Blanford, F.R.S., Vice-President, in the chair.-The following communications were read:-On the hornblende-schists, gneisses, and other crystalline rocks of Sark, by the Rev. Edwin Hill and Prof. T. G. Bonney, F. R.S. The authors refer to Mr. Hill's paper, published in 1887, for a general description of the island. They were led to examine Sark again in the hope that its rocks might afford some clue to the genesis of the hornblende-schist of the Lizard. They describe the structure, macroscopic and microscopic, of the various foliated rocks. These are :—(a) The basement gneiss, a slightly foliated, somewhat granitoid rock, probably of igneous origin, but with some abnormal environment, and possibly intrusive into, instead of older than the rock which succeeds it. (b) The hornblende-schists, almost identical with those of the Lizard, but in one case yet more distinctly banded. (c) Banded gneisses, sometimes rather finegrained, variably banded; quartzofelspathic layers alternating with those rich in biotite or occasionally hornblende. Some of these gneisses resemble the granulitic group" of the Lizard; others recall certain of the less coarse, well-banded gneisses of Scotland, e.g. south of Aberdeen. Sometimes they are much 'gnarled" by subsequent earth-movements, by which, however, as a rule, the crystalline rocks of the island do not appear to have been very seriously affected. (d) A very remarkable group of local occurrence which exhibits great variety. In some places large masses of a dark green hornblende-rock are broken up and traversed by a pale red vein-granite or aplite. The former rock is drawn out into irregular lenticles, elongated lumps, and finally streaks, and has been melted down locally into the aplite. This then becomes a well-banded biotite gneiss, which macroscopically and microscopically agrees with types which are common among the Archæan rocks. Sark therefore presents an example of the genesis of such a gneiss, and the authors are of opinion that probably all the above-named rocks are of igneous origin, but became solid ultimately under somewhat abnormal conditions, to which the peculiar structures (which distinguish them from ordinary igneous rocks) are due. They attribute the banding to the effect of fluxional movements, anterior to final consolidation, in a mass to some extent heterogeneous. This hypothesis they consider may be applied to all gneisses or schists which exhibit similar structures-that is, to a considerable number (but by no means all) of the Archæan rocks. The second part of the paper consists of notes on some of the dykes and obviously intrusive igneous rocks of the island. Among these are four (new) dykes of "mica-trap," one of which exhibits a very remarkable pisolitic" structure. The variety of picrite described by Prof. Bonney in 1889 (from a boulder in Port du Moulin) has also been discovered in situ. The reading of this paper was followed

by a discussion, in which Major-General McMahon, Prof. Judd, Mr. Hudleston, Mr. Barrow, the Rev. Edwin Hill, and Prof. Bonney took part.-On the plutonic rocks of Garabal Hill and Meall Breac, by J. R. Dakyns and J. J. H. Teall, F.R.S. (Communicated by permission of the Director-General of the Geological Survey.) The plutonic rocks described occur in a complex forming a belt of high ground south-west of Inverarnan. They vary considerably in composition, and though gradual passages are sometimes found between more or less acid rocks, at other times the junction is sharp. The more acid are always found to cut through the less acid when the two rocks are found in juxtaposition, and fragments occurring in a rock are less acid than the rock itself. Though thus shown to be of different ages, they must evidently be referred to one geological period. The first rocks to be formed were peridotites; then followed diorite, tonalite, granite, and eurite in order of increasing acidity. The specific gravities, colours, and textures of the rocks are considered, and a detailed account of the constituent minerals given. The essential minerals are arranged in the following order, based on their general distribution in the different types of rock: olivine, pyroxene, hornblende, biotite, plagioclase, orthoclase and quartz, microcline. The following is the order in which the principal constituents commenced to form in the rocks: iron ores, olivine, pyroxene, hornblende, biotite, plagioclase, orthoclase, microcline, and quartz. The chemical composition of the rocks is discussed, data being furnished by a series of analyses made by Mr. J. H. Player, and a diagrammatic repre sentation of the molecular relations of the different bases and silica is given. The relations between mineralogical composition, chemical composition, and geological age are then considered; and the following conclusions are reached :-(1) That the various rocks have resulted from the differentiation of an originally homogeneous magma. (2) That the chronological sequence from peridotite to eurite is connected with the order of formation of minerals in igneous magmas. The paper was discussed by Dr. Hatch, Prof. Bonney, and Mr. Barrow. -North Italian Bryozoa; Part II. Cyclostomata, by Arthur Wm. Waters.

PARIS.

Academy of Sciences, February 1.-M. D'Abbadie in the chair. Note on a structure placed on the summit of Mont Blanc, by M. J. Janssen. It will be remembered that, after failing to reach the rock through the snow on the top of Mont Blanc, M. Janssen, last October, made some observations in a temporary hut for the purpose of testing whether it was displaced appreciably by the movement of the snow. The observations failed to indicate any movement. On January 2 the hut was visited by M. Dunod, and some observations made in it at M. Janssen's request show that no change of place has occurred during this interval of four months.-Observations of solar spots and faculæ made with the Brunner equatorial (o'16 metre aperture) of Lyon Observatory during the latter half of 1891, by M. Em. Marchand. (See Our Astronomical Column.)-Temperate regions; local conditions of persistency of atmospheric currents; derived currents; origin and translation of certain cyclonic movements, by M. Marcel Brillouin.-On an extension of Sturm's theorem, by M. E. Phragmén.-On Laplace and Lavoisier's apparatus for measuring the linear expansion of solids, by M. E. Grimaux. The author has come into the possession of some copper-plates drawn by Lavoisier in illustration of his method of determining the coefficient of linear expansion. Pulls have been obtained from these plates and presented to the Academy.-On the compressibility of saline solutions, by M. Henri Gilbault.-On electro-capillary phenomena, by M. Gouy. -On the optical determination of high temperatures, by M. H. Le Chatelier. Some experiments have been made with the idea of measuring high temperatures by determining the intensity of the radiations emitted by a pyrometer of platinum, or clay, or other material, when compared with the light of a standard lamp. The results obtained indicate that the method is a good one. principal difficulties, of course, depend upon the fact that the radiations emitted by an incandescent body are affected by conditions other than temperature. M. Le Chatelier, however, seems to have satisfactorily overcome these difficulties. -On achromatism, by M. A. Broca.-Barium and strontium nitrides, by M. Maquenne. These nitrides are formed by the direct action of nitrogen at a red heat upon the metals obtained from amalgams formed by electrolysis. The analyses given prove their composi tion to be represented by N,Bag and N,Sr, respectively. They yield ammonia on treatment with water, and may be viewed as

The

metallic ammonias. Barium nitride does not give ethyl bases when treated with alcohol. It reacts energetically at a red heat with carbon monoxide, producing barium cyanide and oxide. Strontium nitride similarly yields only a trace of strontium cyanide, the chief products being the oxide, carbonate, and carbon.-Carbon chlorobromides, by M. A. Besson. (See Notes.)-Action of metals on salts dissolved in organic liquids, by M. Raoul Varet. Certain metals, able to precipitate others from their salts dissolved in water, lose this property when certain organic liquids are used as solvents. This difference of action is due somewhat to the water and somewhat to the formation of molecular compounds formed by the union of the products present.-On monosodium mannite, by M. de Forcrand.-Transformation of sulphanilic into sulphanilocarbamic acid in the animal economy, by M. J. Ville. — Chemical study of the chlorophyll bodies of the pericarp of the grape, by M. A. Etard.-Researches on the adherence to the leaves of plants, and notably to the leaves of the potato, of copper compounds used to prevent their diseases, by M. Aime Girard.-Development of the organe vibratile of Composite Ascidia, by M. A. Pizon.-On the locust (Schistocerca peregrina, Oliv.) and its changes of colour; rôle of the pigments in the phenomena of histolysis and histogenesis which accompany the metamorphosis, by M. Kunckel d’Herculais.—On the commencement and extinction of cambial activity in trees, by M. Emile Mer.-Absolute surfaces and relative divisions of the earth occupied by the principal geological groups, by General Alexis de Tillo. The author states the relative surfaces, of each of the present continents, which existed in different geological periods.—Investigation of the nature of the waters and mud of Lake Annecy, by M. L. Duparc.