M. DELESSE, a member of the Institute, vice-president of the Geographical Society of Paris, and author of a number of works and papers on geology, died in Paris at the age of sixty-three

*years.

THE death is announced on the 25th inst. of Sir Charles Reed, M.P., the much-respected chairman of the London School

Board.

A METEOROLOGICAL observatory has been erected at Port-auPrince, Haiti, under the care of the Rev. Father Wiek, on ground granted by the State. It is an octagon of two stories and a platform. Besides the indispensable instruments it has

working of the public elementary school system, head-masters of secondary schools, persons experienced in education, and others interested. Invitations have been accepted by the chairmen of the Education and School Management Committees of the School Boards for London, Liverpool, Birmingham, Leeds, Sheffield, Bristol, Bradford, Leicester, and Nottingham; also by Dr. Abbott, Dr. Caldicott, Mr. Eve, Professors Max Müller, Carey Foster, Henrici, Gladstone, and Meiklejohn; Sir U. Kay-Shuttleworth, Sir. John Lubbock, the Rev. Mark Pattison, and numerous others.

MR. STEPHEN BRETTON, F.M.S., writes from Eastbourne to the Times, under date March 28, that he saw a meteor of great

THE inaugural meeting of a Society of Chemical Industry will be held in the rooms of the Chemical Society, Burlington House, Piccadilly, on April 4, at 4 p.m. This Society is not intended to represent any one particular branch of chemical industry. It is hoped that it will be representative of many manufactures-alkali-making, manure-making, the textile colour industries, the glass and pottery manufactures, tar distilling, soap-making, sugar-making, brewing, metallurgy, the manufacture of fine chemicals, and all other industries which show any connection with chemical science.

THE newly-issued part of the Medical Reports which are from time to time issued by order of the Inspector-General of Chinese Maritime Customs, contains an elaborate monograph by Dr. Duane B. Simmons on the subject of Beriberi, or the Kakké of Japan, which includes some interesting notes on the history and geographical distribution of the disease, and is illustrated by a sketch.map.

MR. BOWDLER SHARPE, F.L.S., delivered on Thursday last the concluding lecture of a series on the "Birds of the World," which he has been giving at Tonbridge School. Throughout the winter lectures have been given on various literary and scientific subjects by Prof. Henry Morley, Rev. A. Lucas, and others, and large and attentive audiences have shown great interest in all the series. The school already possesses a small museum, which is increasing under the auspices of the present head-master, the Rev. T. B. Rowe, who is evidently doing his best to encourage a taste for science and literature in the institution under his charge.

EVERY ornithologist should read a little pamphlet recently sent to us by the Dundee Naturalists' Society, entitled "The Grallatores and Natatores of the Estuary of the Tay; the great decrease in their numbers of late years; the causes; with suggestions for its mitigation. A paper read by Col. Drummond Hay.” The author, whose long residence in the district alluded to renders his experiences doubly interesting, makes out a good case for his friends the birds in regard to their alleged destruction of fish and spawn, and no doubt some natice will be taken of his statements at the approaching Fisheries' Exhibition at Norwich. The principal cause in the decrease of the birds on the Tay he attributes chiefly to the increased number of gunners on the river, who disregard the close-season, while the wilful destruction of the sea-birds' eggs also plays sad havoc amongst their numbers. Drainage and cultivation of the land has also altered the conditions under which certain species nested, and has driven them further afield.

A Conference on the reform of the Educational Code is to meet in London in the third week in April, and to sit for two days, for the purpose of drawing up a series of recommendations, to be submitted in the form of a memorial to the Vice-President of the Committee of Council. The gentlemen invited to attend are persons conversant with the practical

finest he ever observed. Its size was apparently rather larger than Venus at her brightest, and for two or three seconds illuminated the heavens very brilliantly. Its colour was of an intense purple white, and moved somewhat slowly. He first noticed it a little south of Regulus, and going in direction of Castor. When immediately below Prosepe it burst into about five or six frag. ments, each about the size of a star of the third or fourth magnitude, these assuming a deep fiery red. It then immediately disappeared. The night was especially clear; temperature in air about 30°; barometer about 29.850.

THE Committee of the "Frank Buckland Memorial Fund" have decided that the memorial shall take the form of a bust to be placed in the Fish Museum at South Kensington; the purchase of an annuity to be presented to Mrs. Buck land; and, if there be any surplus, it will be applied in some way to promote the welfare of the fishermen of this country. The honorary secretaries are Col. Bridges and Mr. T. Douglas Murray, to whom subscriptions may be sent at 34, Portland Place.

SMART shocks of earthquake occurred at Agram on March 21 at 3h. 40m. a. m., duration three seconds, and on March 24 at 6h. 45m. a.m., both accompanied by loud subterranean noises.

THERE was another earthquake shock at 'Casamicciola on Sunday morning at 6.45.

M. VAN MALDEREN, who was the electrical engineer of the Alliance, and constructed the so long unrivalled magneto-electric machine belonging to this Company, died at Brussels at the age of seventy a few days ago.

ALL the obstacles which have prevented the reconstruction of the Sorbonne being accomplished, have been removed by M. Jules Ferry, and the work will begin immediately. The same may be said of the isolation of the Public Library of Paris, all the required expropriations having been decreed.

THE date for admission of exhibits to the International Exhi• bition of Electricity at Paris has been prolonged to April 15.

THE Geologists' Association Easter Excursion will, be on Monday and Tuesday, April 18 and 19, to Salisbury, Stonehenge, and Vale of Wardour.

COLONEL PARIS, the head of the Paris fire brigade, 'has concluded his report on the destruction of the Printemps Establishment by proposing that large warehouses be compelled to light by electricity. The burning of the Nice Theatre, which was occasioned by a gas explosion, has given a new importance to that movement.

M. DE MERITENS has completed the construction of one of his magneto-electric engines intended for lighthouse illumination. An experimental trial took place on March 25 before MM. Becquerel, Gornu, Mascart, and other members of the Technical Commission of the International Exhibition. It was proved that with fifteen horse-power his machine illuminates at once more than thirty Jablochkoff lights, and that it could, at a moment's notice, be used in a regulator for marine purposes.

MR. THOMAS EDWARD, the Banff naturalist, has reprinted in a separate form some useful and interesting papers on the Protection of Wild Birds. The pamphlet is to be had at the Banffshire Journal Office.

THE additions to the Zoological Society's Gardens during the past week include an Egyptian Gazelle (Gazella dorcas) from Egypt, presented by the Earl of March, F.Z.S.; a Common Genet (Genetta vulgaris), South European, presented by the Rev. F. P. Voules; a Giant Toad (Bufo agua) from Brazil, presented by Mr. Carl Hagenbeck; a Long-snouted Snake (Passerita mycterizans) from India, presented by Mr. H. H. Black; an Amherst's Pheasant (Thaumalea amherstia) from Szechuen, China, a Black Swan (Cygnus alratus) from Australia, purchased; a Tiger (Felis tigris), a Bactrian Camel (Camelus bactrianus), a Sambur Deer (Cervus aristotelis), born in the Gardens.

OUR ASTRONOMICAL COLUMN

A NEW VARIABLE STAR.-On July 26, 27, and 29, 1783, D'Agelet observed a star which he twice estimated 6m., and on 'the last night 6'5m.; it is No. 5057-9 in Gould's reduced catalogue, the mean of the three observations giving for 1800, R. A. 19h. 23m. 47 57s. and Decl. +17° 19′ 42′′8. The only subsequent observation we have yet found of this star is in the Durchmusterung, where it is rated as low as 9'4m.; there is consequently a high probability that it will prove to be a remarkable variable. The position brought up to the beginning of 1880 will be R.A. 19h. 27m. 22 Is., Decl. + 17° 29′ 28′′. D'Agelet's original observations will be found at pp. 542, 544, and 546 of the Histoire Céleste of Lalande.

MINIMA OF ALGOL, ETC., IN 1880.-Prof. Julius Schmidt has published his observations, or rather the results of his observations, of Algol and other variable stars, made at Athens during the past year. On comparing his epochs of minima with the formula in Prof. Schönfeld's last catalogue, it will be found that according to the most completely determined minima the calculation is too late by nearly half an hour. But the differences between calculation and observation are very irregular, so that if we take a mean of the whole, the true minimum would appear to be earlier than that computed by only nineteen minutes. The minima between August 28 and December 21 are here compared.

According to the observations of the same indefatigable astronomer Mira Ceti was at a maximum between July 20 and 25, but in 1880 it only attained about 4:2 m. A maximum of R Leporis occurred about November 9; the determination is not very certain. The intervals between maximum and minimum, and vice verså of a Herculis were as irregular as usual.

THE RED SPOT UPON JUPITER'S DISK. Dr. Jedrzejewicz has published some inferences from observations for ascertaining the time of rotation of the eastern extremity of the large red spot upon the disk of Jupiter, made at his private observatory at Plonsk during the winter of 1880-81. The instrument employed is a refractor six-inches aperture, with powers 225 to 300. In December he measured the length of the spot 9" 8, and considers that his own observations compared with those of Prof. Schmidt at Athens, indicate that the length of the spot remained unchanged during the winter. On this assumption he finds for the time of rotation 9h. 55m. 34:4145.013s, by 174 rotations between November 25, 1880, and February 5, 1881. Prof. Schmidt from 1021 rotations between July 23, 1879, and September 17, 1880, obtained the value 9h. 55m. 34'4225.005s. for the middle of the spot. In 1862, by observations upon a spot which he says was much darker and a more favourable object for the purpose than the spots observed by Airy and Mädler in 1834-35, and which was not much larger than the shadow of the third satellite he had found for the time of rotation 9h. 55m. 251684s. agreeing with the previously-determined values. While the period from observations of the red spot is gs. greater, Prof. Schmidt remarks that it agrees very nearly with that already obtained by Mr. Pratt.

THE MINOR PLANETS.-It appears that the object detected by Herr Palisa at the new Observatory of Vienna on the 23rd of

last month, and which was announced as No. 220 of the smallplanet group, may prove to be No. 139 Fuera, which had not been observed since 1874. It was discovered by the late Prof. Watson at Pekin on October 10 in that year, while he was engaged upon one of the United States expeditions for the observation.of the transit of Venus, and as was reported at the time, without the aid of a chart of telescopic stars, but from his memory of their configuration about the particular spot occupied by the planet. It was observed on November 8 by Rümker at Hamburg, but the length of observation was not sufficient to determine the mean motion with any degree of accuracy: hence although the elements had been several times brought up to more recent dates by Watson, the planet had not been recovered up to last month. By the last Berlin circular it would seem that Ismene will fall little short of Hilda in the length of its revolution, and these two minors will thus stand out as exceptional members of the group. By the latest elements the period of Hilda is 2860 days or 7.832 years, and that of Ismene 2854 days or 7.814 years. Calculation has assigned the shortest period to No. 149 Medusa, but this awaits confirmation, perhaps in the next summer, when the planet should again come into opposition according to the imperfect elements at present available.

PHYSICAL NOTES

M. PLANTAMOUR continues to study with his sensitive levels the phenomena of periodic rise and fall of the ground which he has observed in Switzerland. He believes he has established a connection between these periods and those of the changes of temperature of the earth's surface, there being an annual change of level, in an east-west direction corresponding with the mean temperatures of the surface during the year.

M. ROSENSTIEHL concludes from his researches on the sensations of colour recently noticed that the three fundamental colour sensations of the Young-Helmholtz-Maxwell theory correspond to the following tints of the pure spectrum. Orange-red, threefourths of the distance from C to Damongst the Fraunhofer lines, a yellow-green three-quarters of the distance from D to E, and a blue situated at one-third from F towards G. The principle upon which this selection is made is that the selected tint fulfils the following conditions: (a) it is equidistant between two tints which are complementary to one another; (b) it produces with either of the other selected tints another colour having a chosen is midway between that yellow and that blue which minimum of white admixed with it. Thus the yellow-green produce the best white with one another, and it gives with the selected orange-red a yellow more intense than any known yellow pigment under equal illumination, and with the selected blue gives a green more intense than the richest green pigment.

M. HENRI BECQUEREL observes that the specific magnetism of ozone exceeds that of oxygen, and is much greater than could be accounted for by the difference.in.density of these two-allo. tropic forms of the gas.

IN view of recent terrible colliery explosions in Belgium, M. Cornet has called attention (in the Belgian Academy) to a possible interference of winds, blowing in an inclined direction, with the proper ventilation of mines. Most of the "fiery" Belgian mines have two shafts, one for raising the coal and for descent of air, which, passing along the galleries, is drawn up the other shaft by a ventilating engine. The orifice of the latter shaft is generally (unlike that of the other) unsheltered by buildings; it debouches directly in the air a little above the ground. Obviously, then, a strong wind, blowing with downward inclination towards this orifice, might seriously affect the ventilating action. It is noted that one explosion in Hainaut on November 19, 1880, followed a night of very high wind, which M. Cornet shows to have been capable of depressing ventilation considerably. Mines with large sections are more dangerous than others in atmospheric perturbations. The true remedy, however (in the author's opinion), is not increasing the resistance to the air-currents, 'but sheltering the orifices of the ventilating shafts against descending winds.

IN a recent paper on the optical structure of ice (to the the ice individuals the plane of the secondary axes is fixed by the Freiburg Society of Naturalists) Prof. Klocke finds that while in position of the principal axis, they are subject to no law as ito direction in that plane.

THE phenomenon of verglas occurred at Urbino in Italy twice in January; and from his observations of it Prof. Serpieri con

Icludes (Real. Ist. Lomb. Rend.) that surfusion of the raindrops is not indispensable to its production. Surfusion indeed accelerates it, as do also violence of wind and intense cold; but a rain with temperature not so low as zero falling into an aircurrent in rapid motion and below zero gives the phenomenon. It is pointed out, however, that the mist which usually accompanies verglas being driven against objects by the wind, and its particles being in a state of surfusion (the temperature being below zero), probably contributes to the general result, helping to make the ice-layer regular and uniform. If the verglas be such that the drop freezes wholly at once, the latter has probably contained many small crystals of ice.

M. MERCADIER sums up his researches on Radiophony by saying that he believes that the phenomena are due to a vibratory movement set up by the alternate heating and cooling, due to the intermittent beams of heat-rays, of the gaseous layer adjacent to the solid surface at which the radiations are absorbed; being an anterior layer in the case of solid bodies, a posterior layer in the case of transparent bodies.

M. JANSSEN has succeeded in photographing the lumière cendrée, or earth-shine" on the moon when three days old: in the photograph the "continents" were to be distinguished clearly from the " seas. "This disposes of the view sometimes advanced, and held, we believe, by some most eminent astronomers, that the 66 new moon in the arms of the old" was an optical illusion.

PROF. D. W. BEETZ, of the Technical High School of Munich, wishes us to say that in the note (vol. xxiii. p. 442) on the modulus of elasticity of rods of carbon, he, and not Herr Holtz, should have been mentioned as the author of the paper on the subject in Wied. Ann.

GEOGRAPHICAL NOTES

AT the meeting of the Geographical Society on Monday Mr. J. B. Minchin, who has spent some seven years in the country, read an excellent paper on Eastern Bolivia, which also included some observations on the Gran Chaco. After some preliminary remarks Mr. Minchin dwelt at length on the water-system of the country, and, speaking first of the lakes, he mentioned that between the Rivers Pilcomayo and Paraguay, in the unexplored Chaco, the Indians report the existence of a lake which no white man has ever yet seen, but which is perhaps near 22° S. lat. The rivers belong to Amazon and Plate systems, and with the exception of the Paraguay and the Itenez, they mostly have their sources among the highest summits of the Andes. The Parapite, Mr. Minchin added, is the most southerly affluent of the Amazons, which in some maps has been made to flow across the Chaco into the Paraguay. The Pilcomayo also does not, as has been thought, receive any tributaries on its course through the Chaco, so far as can be learned from the Indians. Mr. Minchin afterwards alluded to his expedition over the Matto Grossi Mountains, which he succeeded in crossing for the first time. The latter part of the paper was largely devoted to the animal and vegetable productions of Eastern Bolivia and to the commercial condition of the country. The discussion which followed turned chiefly on the route of the future into Bolivia, whether it would be most advantageous to follow the Paraguay route or develop a new one by the Madera.

MR. E. G. RAVENSTEIN has nearly completed for the Council of the Geographical Society the large map of Eastern Equatorial Africa, on which he has been engaged for nearly three years under the direction of their Scientific Purposes Committee. The original drawings will be reduced before they are engraved, and the map when published will be in twenty-four sheets, and on a scale of 1 : 1,000,000. It will take in the lake region, the Upper Congo, and the Upper Nile, and on the east coast will extend from Somali Land to a little south of the Zambesi, the precise limits of the map being from 10° N. to 20° S. lat., and from 25° to 52° E. long. A very complete bibliography of authorities, compiled pari passu with the map, will be published afterwards.

MR. BROUMTON, an agent of the China Inland Mission at Kweiyang-fu, in the province of Kweichow, has lately sent home an account of a visit which he had paid by invitation to the Miao-tsze tribes a short distance off. He had been told by one of them, from whom he had been learning something of the language, that in the third moon of the year his people had large gatherings in the hills, and was asked to be present at these

festivities. He accordingly went and had an excellent opportu nity for observing the manners and customs of this section of this comparatively unknown people. He describes their dress, the character of the festivities witnessed, the singular musical instruments used, &c. The particular tribes visited by Mr. Broumton are known as the Black (from the colour of their clothes) and the Ka-teo tribes, and live near Hwangping-chow.

MR. CARL BOCK is leaving for Siam next week, where he intends to make an excursion into the interior. His book, "The Headhunters of Borneo," will be published shortly by Messrs. Sampson Low and Co.

WE hear that Mr. Edward Whymper, who has already given an account of some phases of his South American journey to the Alpine Club and the Society of Arts, will read a paper on the Andes of Ecuador before the Geographical Society on May 9.

PRIZES OF THE PARIS ACADEMY OF SCIENCES

AT the public séance of the Academy on March 14 the annual distribution of prizes took place. While many of these prizes are offered for particular subjects, others are devoted to rewarding the most important advances made during the year in special departments of science.

The Grand Prize of the Mathematical Sciences was awarded to M. Halphen for work on the theory of linear differential equations.

In astronomy Mr. Stone receives the Lalande prize for his stellar researches, following those of Abbé de Lacaille, at the Cape of Good Hope; and the Valz prize goes to M. Tempel for his observations on comets. M. Vinot's labours in starting and editing Le Ciel are recognised by the award of the Tremont prize.

The Montyon prize of the mechanical arts is given to M. Cornut for his study of the faults of iron plates; the Poncelet prize to M. Leauté for various works; while a recompense of 1500 francs on the Bordin foundation is given to M. Lan for improved modes of combustion, diminishing the trouble and harm from smoke, &c. (in steel heating). The extraordinary prize of 6000 francs (for improving the efficacy of naval forces), and the Plumey prize, are not awarded.

In physics we find a recompense of 3000 francs given to M. Ader, on the Vaillant foundation, for improvements in phonetic telegraphy. The grand prize for researches on elasticity of crystalline bodies is not awarded.

The Jecker prize goes to M. Demarçay for important work in organic chemistry; the Gegner prize to M. Jacquelain for skill in preparing a large number of substances in a pure state, &c.

Two prizes on the Bordin foundation are awarded in geology, one to M. Gosselet for a geological sketch of the North of France, the other to MM. Falsan and Chantre for their geological monography of ancient glaciers and erratic deposits in the middle of the Rhone Valley. Recompenses on the Gay foundation are awarded to MM. Delage and Chevremont for observations on movements of the coast-line in France.

In medicine and surgery three Montyon prizes are awarded: one to Dr. Charcot for his work on localisation of disorders of the brain; another to Dr. Sappery for researches on the lymphatic apparatus of fishes; the third to Dr. Jullien for important medical researches. On the Bréant foundation M. Colin is awarded 5000 francs for physiological researches. Dr. Segond receives the Godard prize for an important work in surgery; Dr. Quinand the Barbier prize for researches on the_quantity of oxygen in human blood in health and in disease. The Dusgate prize (having regard to prevention of premature burial) is not given, but MM. Onimus, Peyrand, and Le Bon are recompensed for their researches. The Boudet prize is awarded to Prof. Lister.

In experimental physiology the Montyon prize is given to M. Bonnier for researches on the nectaries and colours of plants. The Fons-Melicocq prize for botanical research in the north of France is gained by M. de Vicq; and M. de la Chapelle receives 1000 francs on the Desmazières foundation for studies on French cryptogams.

In anatomy and zoology the Grand Prize with reference to distribution of marine animals on the French coast is withheld

instrument for producing the new induction current; (2) sonometer or balancing coils; (3) rheotome and battery; (4) telephone.

The essential portion of this new balance is that wherein a coil is so arranged that a wire of iron or copper can pass freely through and forming its axis, the iron or copper wire rests upon two supports 20 centims. apart; at one of these the wire is firmly clamped by two binding screws; the opposite end of the wire turns freely on its support, the wire being 22 centims. long, having 2 centims. projection beyond its support, in order to fasten upon it a key or arm which shall serve as a pointer upon a circle giving the degrees of torsion which the wire receives from turning this pointer. A binding screw allows us to fasten the pointer at any degree, and thus preserve the required stress the time required.

The exterior diameter of the coil is 5 centims., having an interior vacant circular space of 3 centims., its width is 2 centims. upon this is wound 200 metres of No. 32 silk-covered copper wire. This coil is fastened to a small board so arranged that it can be turned through any desired angle in relation to the iron wire which passes through its centre, and it can also be moved to any portion of the 20 centims, of wire, in order that different portions of the same wire may be tested for a similar

stress.

The whole of this instrument, as far as possible, should be constructed of wood, in order to avoid all disturbing inductive influences of the coil.

The iron wire at its fixed end is joined or makes contact with a copper wire, which returns to the front part of the dial under its board and parallel to its coil, thus forming a loop, the free end of the iron wire is joined to one pole of the battery, the copper wire under the board is joined to the rheotome and thence to the battery.

The coil is joined to the telephone; but, as in every instance we can either pass the battery through the wire, listening to its inductive effects upon the wire, or the reverse of this, I prefer, generally, in order to have no voltaic current passing through the wire, to join the iron wire and its loop direct to the telephone, passing the voltaic current through the coil.

In order to balance, measure, and know the direction of the new induction currents by means of a switching key, the sonometer (Proc. Roy. Soc., vol. xxix. p. 65) 1 described to the Royal Society is brought into the circuit. The two exterior coils of the sonometer are then in the circuit of the Dattery,, and of the coil upon the board containing the iron wire or stress bridge. The interior or movable coil of the sonometer is then in the circuit of the iron wire and telephone. Instead of the sonometer constructed as described in my paper to the Royal Society, I prefer to use one formed upon a principle I described in Comptes rendus, December 30, 1878. This consists of two coils only, one of which is smaller and turns freely in the centre of the outside coil. The exterior coil being stationary, the centre coil turns upon an axle by means of a long (20 centims.) arm or pointer, the point of which moves over a graduated arc or circle. Whenever the axis of the interior coil is perpendicular to the exterior coil no induction takes place, and we have a perfect zero; by turning the interior coil through any degree we have a current proportional to this angle, and in the direction in which it is turned. As this instrument obeys all the well-known laws for galvanometers, the readings and evaluations are easy and rapid.

If the coil upon the stress bridge is perpendicular to the iron wire,, and if the sonometer coil is at zero, no currents or sounds in the telephone will be perceived, but the slightest current in the iron wire produced by torsion will at once be heard; and by moving, the sonometer coil in a direction corresponding to the current,, a new zero will be obtained, which will not only balance the force of the new current, but indicate its value. A perfect zero however will not be obtained with the powerful currents obtained by the torsion of 2 millims. diameter iron wire; we then require special arrangements of the sonometer, which are too complicated to describe here.

The rheotome is a clockwork having a rapid revolving wheel which gives interruptions of currents in fixed cadences in order to have equal intervals of sound and silence. I employ four bichromate cells or eight Daniell's elements, and they are joined through this rheotome to the coil on the stress bridge, as I have already described.

The magnetic properties of iron, steel, nickel,, and cabalt have been so searchingly investigated by ancient as well as by

modern scientific authors, that there seems little left to be known as regards its molar magnetism. I use the word molar here simply to distinguish or separate the idea of a magnetic bar of iron or steel magnetised longitudinally or transversely from the polarised molecules which are supposed to produce its extemal magnetic effects.

Molar magnetism, whilst having the power of inducing an electric current in an adjacent wire, provided that either has motion or a change in its magnetic force, as shown by Faraday in 1832, has no power of inducing an electric current_upon itself or its own molar constituent, either by motion or change of its magnetic moment. Molecular magnetism (the results of which I believe I have been the first to obtain) has no, or a very feeble, power of inducing either magnetism or an electric current in an adjacent wire, but it possesses the remarkable power of strongly reacting upon its own molar wire, inducing (comparatively with its length) powerful electric currents, in a circuit of which this forms a part.

We may have also both cases existing in the same wire; this occurs when the wire is under the influence of stress, either external or internal; it would have been most difficult to separate these two, as it was in my experiments with the induction balance without the aid of my new method.

Ampère's theory supposes a molecular magnetism or polarity, and that molar magnetism would be produced when the molecular magnetism became symmetrical; and his theory I believe is fully capable of explaining the effects I have obtained, if we admit that we can rotate the paths of the polarised molecules by an elastic torsion.

Matteucci made use of an inducing and secondary coil in the year 1847 (Compt. rend. t. xxiv. p. 301, 1847), by means of which he observed that mechanical strains increased or decreased the magnetism of a bar inside this coil.

Wertheim published in the Comptes rendus, 1852 (Compt. rend. t. xxv. p. 702, 1852), some results similar to Matteucci; but in the Annales de Chimie et de Physique, 1857 (Ann: de Chim. et de Phys. (3) t. 1. p. 385, 3857), he published a long series of most remarkable experiments, in which he clearly proves the influence of torsion upon the increment or decrement of a magnetical wire.

Vilari showed (Poggendorff's Annalen, 1868) increase or diminution of magnetism by longitudinal pull according as the magnetising force is less or greater than a certain critical value.

Wiedermann (Wiedermann's "Galvanismus," p. 447), in his remarkable work, "Galvanismus," says that an iron wire through which an electric current is flowing becomes magnetised by twisting the wire. This I have repeated, but found the effects very weak, no doubt due to the weak battery I use, viz. four quart bichromate cells.

Sir W. Thomson shows clearly in his remarkable contribution to the Phil. Trans. Roy. Soc., entitled "Effects of Stress on the Magnetisation of Iron, Nickel, and Cobalt" (Phil. Trans. May 6, 1878), the critical value of the magnetisation of these metals under varying stress, and also explains the longitudinal magnetism produced by Wiedermann as due to the outside molar twist of the wire, making the current pass as in a spiral round a fixed centre. Sir William Thomson also shows clearly the effects of longitudinal as well as transversal strains, both as regards its molar magnetism and its electric conductivity.

My own researches convince me that we have in molecular magnetism a distinct and separate form of magnetism from that when we develop, or render evident, longitudinal or transversal magnetism, which I have before defined as molar.

Molecular magnetism is developed by any slight strain or twist other than longitudinal, and it is only developed by an elastic twist; for however much we may twist a wire, provided that its fibres are not eparated, we shall only have the result due to the reaction of its remaining elasticity.

If we place an iron wire, say 20 centims. long, I millim, diameter, in the axis of the coil of the electro-magnetic balance, and if this wire is joined, as described, to the telephone, we find that on passing an electric current through the inducing coil no current is perceptible upon the iron wire; but if we give a very slight twist to this wire at its free end-one-eighteenth of a turn, or 20°-we at once: hear, clear and comparatively loud, the currents passing the coil; and although we only gave a slight elastic twist of 20° of a whole:turn, and this spread over 20 centims, in length, making an extremely slight molar spiral; yet the effects are more powerful than if, using a wire free from stressy we