NOTES ON THE AYE-AYE OF MADAGASCAR HAVING recently passed through that part of Madagascar which is the habitat of the Aye-aye, and having made careful inquiries from the Malagasy respecting the habits of this strange creature in its native haunts, I have thought that the information gained might be of interest to the readers of NATURE, and therefore note down the result of my inquiries.

The Aye-aye lives in the dense parts of the great forest that runs along the eastern border of the central plateau of the island, but only in that part of it which separates the Antsihànaka province from that of the Bétsimisàraka, and which is about twenty-five miles from the east coast, in latitude 17° 22' S., or thereabouts. Possibly there are other parts of the country where the Aye-aye is found; but so far as my knowledge extends- and I have made inquiries in different parts of the island-this is the only region where the creature finds its home. In Carpenter's "Zoology" the Aye-aye is said to be "very rare in its native country"; and Mr. Gosse in one of his books conjectures that it is probably nearly extinct; but, from what I gathered from the natives, it seems to be pretty common,

copies an hour, of a journal specially composed for the occasion, viz., the Soleil Journal. This result, though not indicating a revolution in the art of printing, may enable one to judge of the services these insolators may render in climates with a radiation more powerful and constant.

its nocturnal habits and the superstitious awe with which it is regarded (and of which I shall presently speak), accounting for its apparent rarity.

The native name of the animal is Haihay (Hihi); but this is not derived from the "exclamations of surprise" which the natives "exhibited at the sight of an unknown animal," but is simply onomatopoetic, the creature's call being "Haihay, Haihay." The animal, as is well known, is nocturnal in its habits, prowling about in pairs-male and female. It has but one young one at a birth. It builds a nest of about two feet in diameter, of twigs and dried leaves, in the dense foliage of the upper branches of trees. In this it spends the day in sleep. The nest is entered by a hole in the side.

The teeth are used in scratching away the bark of trees in search of insects, and the long claw in dragging out the prey when found. A white insect called Andraitra (possibly the larva of some beetle) seems to form its chief food. I was told that it frequently taps the bark with its fore feet, and then listens for the movement of its prey beneath, thus saving itself useless labour. It does not flee at the sight of man, showing that for generations it has not been molested by him; which is indeed true, as the

following will show. The natives have a superstitious fear of the creature, believing that it possesses some supernatural power by which it can destroy those who seek to capture it, or do it harm. The consequence of this is that it is with the greatest difficulty one can obtain a specimen. With most of the people no amount of money would be a sufficient inducement to go in pursuit of the creature, "because," say they, "we value our lives more than money." It is only a few of the more daring spirits among them who, knowing the ddiny, i.e. the secret by which they can disarm it of its dreaded power, have the courage to attempt its capture. Cccasionally it is brought to Tamatave for sale, where it realises a good sum. Now and then it is accidentally caught in the traps which the natives set for lemurs, but the owner of the trap, unless one of those versed in the Aye-aye mysteries, who knows the charm by which to counteract its evil power, smears fat over it, thus securing its forgiveness and goodwill, and then sets it free. The story goes that occasionally, when a person sleeps in the forest, the Aye-aye brings a pillow for him-if a pillow for the head, the person will become rich; if for the feet, he will shortly succumb to the creature's fatal power, or at least will become bewitched. Such is the account which the natives give of the curious Cheiromys Madagascariensis. R. BARON, L.M.S. Missionary Antananarivo, Madagascar, April, 1882

THE AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (FROM A CORRESPONDENT)

THIS HIS body held its thirty-first annual meeting at Montreal during the week beginning August 23. under the presidency of Dr. J. W. Dawson, LL.D., F.R.S. Ample accommodation for the Association was found in the buildings of McGill University, and the attendance was very large, 939 persons having been registered. Besides the American and Canadian Fellows and Members of the Association, there were several guests from abroad, among them, Dr. W. B. Carpenter, Dr. J. H. Gilbert, Prof. Wiltshire, and Dr. Pheré, of London; Dr. Samuel Haughton and Prof. Fitzgerald from Dublin, together with Messrs. Szabo of Budapest, Kowalesky of Moscow, and König of Paris, all of whom made communications to the Association.

After the opening ceremonies on the morning of the first day, the nine sections into which the Association is now divided listened to the addresses of their respective vice-presidents. These sections are as follows:-A. Mathematics and Astronomy; B. Physics; C. Chemistry; D. Mechanical Science; E. Geology and Geography; F. Biology; G. Histology and Microscopy; H. Anthropology; and I. Economic Science and Statistics. According to custom, the retiring president of the Association, Dr. George J. Brush, gave his address on the first Wednesday evening, taking for his theme, The Progress of American Mineralogy. This was followed by a reception of the Members of the Association by the Local Committee, its chairman, Dr. Sterry Hunt, acting as host. On Thursday evening the New Redpath Museum of Natural History, lately erected at a cost of 100,000 dollars by Mr. Peter Redpath, and by him presented to the University, was formally opened with addresses by Mr. James Hall and Dr. W. B. Carpenter, a reception being given therein by the President and Mrs. Dawson to the Association and others. Thursday and Friday were devoted to the work of the sections, but Saturday was given to excursions to Ottawa and to Quebec, in both of which cities entertainments were provided by the citizens. Public lectures were given on Monday and Tuesday evenings by Dr. W. B. Carpenter and Prof. Meville Bell, on The Temperature of the Deep Sea, and On Visible Speech. The reading

of papers, however, occupied both the morning and afternoon of these days, and of Wednesday the 30th, on the evening of which day the closing meeting was held, 1' e Association adjourning to meet next August at Minneapolis, in Minnesota, under the presidency of Dr. C. A. Young, of Princeton, New Jersey. The number of papers entered was 256, of which nearly all were read either at length or in abstract, and will be published in the Proceedings.

In addition to the excursions already noticed was one provided by the Harbour Commissioners, and another through South-eastern Canada, to Lake Memphramagog at the close of the meeting. An entertainment in the galleries of the Montreal Fine Art Association should also be mentioned, and various garden parties and fétes by the citizens, who vied with each other and with the railways and steamboat lines in their hospitalities to the members of the Association.

Mention should here be made of a Handbook of Montreal, an illustrated volume of 159 pages, prepared for the meeting by Mr. S. E. Dawson, of the Local Committee, and presented to the members. This little book is remarkable for its excellent historical introduction, and also for a valuable coloured geological map of the environs of the city, prepared by Dr. Sterry Hunt.

After the meeting a small party, including Dr. Carpenter, Prof. Wiltshire, and Dr. Szabó, were conducted by Dr. J. W. Dawson and Dr. Sterry Hunt to the remarkable locality of Eozoon Canadense, near St. André Avellin, among the Laurentide Hills, not far from the City of Ottawa.

THE

Professor PLANTAMOUR

'HE daily journals notify the decease on the 7th instant, at Geneva, of Prof. Plantamour, for many years Director of the Observatory and Professor of Astronomy in the University of that city.

Emile Plantamour was born at Geneva in 1815, and received his early education in the old college founded by Calvin. He entered the Geneva Academy in 1833, where he became a pupil of Alfred Gautier, then in the Chair of Astronomy, and on graduating, adopted this science as his profession. He studied two years at Paris under Arago, and subsequently proceeded to Königsberg, where he became a pupil of the illustrious Bessel. His inaugural dissertation was upon the methods of calculating the orbits of comets, and he obtained the degree of Doctor in 1839. He subsequently visited Berlin where Encke was then one of the great masters of astronomical science of the day. On returning to Geneva he was appointed Professor of Astronomy and Director of the Observatory; these positions he continued to occupy nearly up to the time of his decease. The observations made under bis direction were published in various parts, commencing in 1843, and related to astronomy, magnetism, and meteorology. He took part in a number of geodetical operations in Switzerland, and was the representative of Geneva on the Swiss Geodesic Commission.

Plantamour was a man of considerable private means, and hence was independent of the very modest salary attaching to his official position. A few years since he presented a 10-inch refractor to the Observatory of Geneva, and a building suitable for it was erected at his expense. This instrument has already done good work in the hands of Dr. Meyer. Plantamour devoted much attention to cometary astronomy, one of his most elaborate investigations being his determination of definitive elements of Mauvais' comet of 1844, which was observed from July 7 in that year, to the middle of March, 1845, and therefore offered a favourable opportunity for the calculation of the true form of orbit. Plantamour's result was a somewhat notable one: after taking into account the effect of the attraction of the planets during the

comet's visibility, he concluded that at the passage through perihelion in October, 1844, the comet was moving in an elliptical orbit with a period of revolution of 102050 ± 3090 years. In 1846 he made extensive calculations bearing upon the motion of the two heads of Biela's comet, the results of which will be found in No. 584 of the Astronomische Nachrichten. He further discussed the elements of what was called at the time "Galle's second comet," 1840 II. (Astron. Nach., No. 475-6). In this paper he pointed out some anomalies in the intensity of the comet's light, similar to what has been observed from time to time in other comets.

Plantamour was placed on the list of Associates of the Royal Astronomical Society in 1844; he was a corresponding member of the Academy of Sciences of the Institute of France, and honorary member of the Academy of Turin. Few of those colleagues who were at work at the commencement of his astronomical life now remain.

ON SIR WILLIAM THOMSON'S GRADED

GALVANOMETERS

TWENTY years ago the experimental sciences of electricity and magnetism were in great measure mere collections of qualitative results, and, in a less degree, of results quantatively estimated by means of units which were altogether arbitrary. These units, depending as they did on constants of instruments and conditions of experimenting which could never be made fully known to the scientific public, were a source of much perplexity and labour to every investigator, and to a great extent prevented the results which they expressed from bearing fruit to the furtherance of scientific progress. Now happily all this has been changed. The absolute system of units introduced by Gauss and Weber and rendered a practical reality in this country by the labours of the British Association Committee on Electrical Standards has changed experimental electricity and magnetism into sciences of which the very essence is the most delicate and exact measurement, and enables their results to be expressed in units which are altogether independent of the instruments, the surroundings, and the locality of the investigator.

The record of the determinations of units made by members of the Committee, for the most part by methods and instruments which they themselves invented, forms one of the most interesting and instructive books in the literature of electricity, and when the history of electrical discovery is written the story of their work will form one of its most important chapters. But besides placing 0.1 a sure foundation the system of absolute units, they conferred a hardly less important benefit on electricians by giving them a convenient nomenclature for electrical quantities. The great utility of the practical units and nomenclature, which the Committee recommended, soon became manifest to every one who had to perform electrical measurements, and has led within the last year to their adoption, with only slight alterations, by nearly all civilised nations. Although it is not yet quite twelve months since the late Congress of Electricians at Paris concluded its sittings, the recommendations which it issued have been widely adopted and appreciated by those engaged in electrical work, and have thus begun to yield excellent fruit by rendering immediately available for comparison and as a basis for further research the results of experimenters in all parts of the world. Soon even the ord nary workmen in charge of dynamo machines or employed in electrical laboratories will be able to tell the number of volts and amperes which a generator can give at a certain speed and under certain conditions, to determine the number of amperes of current required to light an incandescence lamp to its full brilliancy, or to measure the capacity of a secondary cell in coulombs per square centimetre.

But in order that the full benefit of the conclusions of the Paris Congress may be obtained it is essential in the first place that convenient instruments should be used, adapted to give directly, or by an easy reduction from their indications the number of amperes of current flowing in a particular circuit, and the number of volts of difference of potentials between any two points in that circuit. To be generally useful in practice these instruments should be easily portable, and should have a very large range of sensibility; so that, for example, the instrument, which suffices to measure the full potential produced by a large Siemens or Edison machine, may be also avail able for testing, if need be, the resistances of the various parts of the armature and magnets by the only satisfactory method; namely by comparing by means of a galvanometer of high resistance the difference of potential between the two ends of the unknown resistance with that between the ends of a known resistance joined up in the same electrical circuit. In like manner the ampere measurer should be one that could be introduced without sensible disturbance into a circuit of low resistance to measure either a small fraction of an ampere, or the whole current flowing through a circuit containing a large number of electric lamps. These conditions are fulfilled by two instruments recently invented and patented by Sir William Thomson and called by him Graded Galvanometers. To give a short account of these instruments is the object of the present article.

I. The Potential Galvanometer.

The galvanometer used for measuring differences of potential in electrical circuits is shown in Fig. I which is engraved from a photograph of the actual instrument. It consists of two essential parts, a coil and a magnetometer. The coil is made of silk covered copper or German silver wire of No. 32 B.W.G. When made of German silver wire it contains about 2,200 yards of wire wound in 7,000 turns, and has a resistance of over 6,000 ohms. It is made in the form of an anchor ring having an outside diameter of fourteen centimetres and an inside diameter of six centimetres. The diameter of section is thus four centimetres. The coil is wound within a mould of proper shape and dimensions, and is then impregnated with melted paraffin under the receiver of an air-pump. A solid compact ring is thus obtained, which does not require a wooden case; and which served round with a covering of silk ribbon looks wel and is not at all liable to get out of order. The coil thus constructed is attached to one end of the horizontal wooden platform P shown in the drawing, and kept firmly in its place by a pair of wooden clamps fitted to the lower half of the coil, and screwed firmly to the end of the platform. When in position the plane of the coil is vertical, and at right angles to a v groove that runs along the middle of the platform. The centre of the coil is opposite to and about one and a half centimetres above the bottom of this groove.

On the platform P rests the magnetometer M (shown in plan in Fig. 2), which consists essentially of a system of magnets properly supported so as to be free to turn round a vertical axis, and shielded from currents of air by being enclosed in a quadrantal shaped box having a closely fitted glass cover. Each magnet is fully one centimetre in length, and is made of glass hard steel wire of No. 18 B.W.G. Four of these mag. nets mounted in a frame with their poles turned in similar directions from the "needle" of the instrument. The frame carrying the magnets is made of two thin bars of aluminium placed side by side with their planes vertical and about a centimetre apart; and connected by a bridge of sheet aluminium. The ends of the magnets are fixed in holes in the vertical sides of the aluminium frame so that the four steel needles form a set of four horizontal parallel edges of a rectangular prism.

In the bridge connecting the two sides of the frame a sapphire cap is fixed, and this rests on an iridium-tipped point standing up from the bottom of the containing box. The sides of the frame are made long enough to form when brought together at one end an index about nine centimetres long of the shape shown in Fig. 2. The point of the index ranges round a scale of tangents placed round the curved edge of the bottom of the box. To prevent error from parallax the bottom of the box, with the exception of the narrow strip occupied by the scale, is covered with a mirror of silvered glass. The observer when taking a reading places his eye in such a position that the point of the index just covers its reflected image, and reads off the deflection indicated by the position of the point of the index on the scale of tangents. The scale is engraved on paper, and firmly fixed to the bottom of the box by photograper's glue; and thus any change of length due to varying amount of moisture in the atmosphere is avoided.

The magnetometer box rests on three feet and a flat spring. Two of these feet, which are in a plane perpendicular to the plane of the box and passing through the supporting point and the zero of the scale, slide in the v groove cut along the middle of the platform: the third foot rests on the plane surface on one side of this groove, the spring on the other side. By this arrangement the magnetometer is rendered perfectly steady and can be moved with perfect freedom along, but only along the platform. A small circular level carried by the box shows when the plane of the magnetometer is horizontal. This adjustment is made by means of the two screws which support the platform at the end remote from the

coil.

To lift the system of magnets and index off the bearing cap when the instrument is not being used, or when it is being carried from one place to another, a small collarpiece free to move round the supporting point is raised up by a horizontal screw turned by a head outside the magnetometer box. When raised this collar-piece forms a supporting platform for the needles and securely prevents them from moving about and sustaining damage. To increase the directive force on the needles when required, the semi-circular magnet shown in the drawing is used with the instrument. This magnet is made of the best steel, and is tempered glass-hard. It is magnetised by sending a current through a semi-circular coil containing it. When in position on the instrument it is supported on two flat pieces of brass projecting from the radial sides of the magnetometer box. The magnet terminates at one end in a cross piece of brass having on its under side at one end a small projecting brass knob. This knob fits into a hollow in one of the projecting arms of brass, while the other end of the cross piece rests simply on the plane surface of the arm. The other end of the magnet is brought to a rounded point which rests in a v notch cut round a cylindrical shoulder on a screw spindle (seen on the right-hand side of Fig. 2), which works through a nut fixed to the other projecting arm of the magnetometer box. The magnet thus rests with its magnetic axis as nearly as may be in the horizontal plane through the axis of the needle, and nearly at right angles to the line joining the centre of the needle's axis with the zero of the scale. Its axis may be placed accurately at right angles to this line by turning the screw until the needle points accurately to zero. The magnet thus mounted remains in the same position relatively to the magnetometer.

The coil is so adjusted that its centre is on a level with the magnetic axis of the needle when the magnetometer is in position. The centre of the magnetic axis, the zero of the scale, and the horizontal v groove in the platform are in the vertical plane through the centre of the coil. Hence if the magnetometer guided by its feet in the v groove be moved along the platform it will carry its

magnet with it without disturbing its zero adjustment of the needle, and the magnets will in every position of the magnetometer be in the same field of force.

On the boxwood slip in which the V groove is cut is marked a series of positions of the front or circular edge of the magnetometer, for which the corresponding numbers of divisions of deflection for one volt difference of potentials, when the intensity of the magnetic field at the needle is one C.G.S. unit, are the terms of the geometric series.. . 8, 4, 2, 1, § . . . These numbers are stamped on the boxwood slip opposite the marks indicating the corresponding positions. The number of divisions of deflection for the nearest position of the magnetometer, that at which the centre of the magnetic axis of the needle is as nearly as may be at the centre of the coil, is not generally a term of this series, but it is determined in every case, and like the others is stamped on the platform.

The instrument is used for the measurement of high potentials with the semicircular magnet in position; but for low potentials the magnet is dispensed with, and the needle left under the earth's directive force alone. The field intensity given by the magnet of each instrument is determined before the instrument is sent out, and is painted on the magnet. The intensity of the field without the magnet, at the place at which the instrument is used has if necessary to be determined. In practice it will generally be found convenient to use some position of the magnetometer which gives a convenient number of divisions of deflection per volt for the field employed. This position is determined by the user of the instrument, who marks it on the platform by drawing two vertical lines on the sides so as to prolong two white lines which are marked on the sides of the magnetometer.

The instrument as thus constructed admits of a very wide range of sensibility. By diminishing the distance of the magnetometer from the coil from the greatest to the least, the sensibility of the instrument can be increased fifty fold: and by removing the field magnet from the instrument and leaving the needle under the influence of the earth's force alone, a sensibility fifty times still greater can be given to it. For the practical purposes for which these instruments are designed the suspension of the needle by cap and point is the most convenient; but with this suspension there is alwavs, with low directive forces, a slight error due to friction and it is therefore not advisable to push the sensibility of the instrument further by diminishing the directive force of the earth's magnetism. An instrument of this kind, however, made for special purposes with a silk fibre suspension could be rendered more and more sensitive up to the limit of instability by so placing a magnet or magnets as, while not interfering with the uniformity of the field at the needles, to diminish more and more the earth's directive force. This method of increasing the sensibility of a galvanometer although quite commonly used by scientific electricians is not, I have reason to believe, at all wellknown generally, and recourse is had, altogether unnecessarily in many cases, to troublesome astatic combinations in order to obtain sensibility.

An important feature of this instrument in connection with its use for the measurement of high potentials is the arrangement of terminals which has been adopted. In certain circumstances when the ends of the coil of a potential galvanometer are attached to terminals fitted with binding screws, it is convenient to connect the instrument with the circuit by wires attached to these screws; but in the case of a dynamo circuit giving between the terminals of the coil a potential difference of eighty or a hundred volts and upwards, this plan of connections has been found highly dangerous. If the wires are twisted together and are ordinary gutta percha covered wires there is always a liability to accidents which may cause conduction from