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a disk of the same color as the ballot that he wishes to throw, and which closes the opening. By the interior arrangement of the machine, a vote being once made prevents the expression of a second, so that it is impossible to vote twice. When the president is sure that every one has taken part in the vote, he touches a special button placed at the side of the machine, and instantaneously the work of addition begins. In this operation, by an ingenious contrivance, the white balls are separated from the black, and the totals. thus formed occupy two appropriate places upon the table. At this moment the little covers remove themselves, and allow one to see the figures resulting from the addition. At the moment when the president sets the process of addition into operation, all voting is suspended, so as not to derange the work. Upon the back of the machine there is a system of needles corresponding to each of the openings, which, as soon as the vote is terminated, prints the result upon a sheet of paper prepared for this. A lateral lever permits the reinstating of every thing in its initial condition, ready for a new operation. All these operations are performed by electricity and instantaneously, and the author says that one minute will suffice to count the votes of an assemblage of seven hundred and fifty persons. The complete machine is now manufactured to order in Paris, the cost being about twenty dollars per voter. -1 B., 1875,

206.

THE THEORY OF THE ELECTRICAL MACHINE.

Poggendorff states that few problems in physics have as yet defied all theories so completely as those offered by the electric machines. Theories there are in plenty; but none explain all the facts, and none are free from unwarranted assumptions. He himself inclines to the opinion that it will not do to assume that the particles of electricity are spherical, and exert their action equally in all directions; but that it is more likely that they are polarized; that they have a definite range on the electrified surface; and that in consequence of the movement of this surface the particles themselves turn. The development of this idea, which is in opposition to the assumption of two electric fluids, as commonly held in Germany, seems, however, to him to be attended

with insuperable difficulties. He appears to have been led to this suggestion by observing the effects produced by turning the revolving plate of an electric machine of the second class through measured angles of 45°, 90°, 135°, etc., instead of turning it steadily throughout the entire circumference.Berlin Akad. Monatsb.

THE ELECTRIC CONDUCTIVITY OF LIGNEOUS SUBSTANCES,

Count Du Moncel has investigated the question as to whether the conductivity of wood fibre, if electrified, is due to the humidity with which bodies are more or less impregnated. His experiments, being conducted with extremely sensitive apparatus, have led him to the following conclusions: A small frame of oak, regarded by the cabinet-maker as being very dry, furnished, when it was brought to him, a deflection of 55° of the scale of the galvanometer. This same small frame, when it had been dried for two hours in the stove, gave not the least deflection, and being kept in a sunny chamber for several hours did not increase its conductivity. Exposed to the air during a dry July night, it gave in the morning a deflection of 13°. It appears from his experiments that it is to the humidity aspired through its pores that the wood owes its relative conductivity, and that this conductivity is proportionate to the degree of pressure upon the metallic plates by means of which the electric current is communicated to the block of wood.Proc. Soc. Teleg. Engineers.

CIRCULAR MAGNETIC NEEDLES.

A report has been presented by Duchemin on the experiments made on board of the French vessels Faone and Savoie, upon the properties of magnetic needles made in the form of a circular disk, instead of a pointed or lozenge-shaped one. Two series of experiments were made: first, with reference to the comparative steadiness of the simple and the circular needles; second, with reference to the correction of the circular needle for local influences by the addition of a concentric movable circular magnet. The sensibility of the circular needle, according to him, leaves nothing to be desired, being superior to that of the ordinary compass, although its friction is greater, since its weight is more than twice as great. The

stability of the circular needle, as shown by its oscillations. to the right and left, is greater than that of the ordinary needle; and its moment of inertia is, in fact, equal in all positions. No difficulty is experienced in locating the position of the magnetic axis of the circular needle. These needles are magnetized instantaneously by means of a powerful softiron electro-magnet. He concludes that the circular compass-needle is an instrument worthy of navigators; and by perfecting its construction we shall come into possession of a simple, sensitive, stable instrument, constituting a veritable improvement on the present arrangement. It is even stated that the extreme sensibility that can be given to this instrument may render it advantageous in magnetic observations. A portion of the errors of the instrument, due to local attractions, may be corrected by means of a circular magnet; but this is not to be recommended, as new complications are thereby introduced.—Bull. Hebd. Assoc. Scientifique.

CORRECTIONS OF THE COMPASS ON IRON SHIPS.

From an elaborate memoir, by Garbich, on the theory and practice of the deviation in compasses on iron ships, we take the following directions for effecting the compensation of the compasses. In order to avoid the employment of large masses of iron, it is best to use two iron rods placed diametrically opposite to each other. To determine exactly the distance of these rods from the centre of the compass, it is best to turn the ship's head toward that point in the horizon at which the quadrantal deviation is a maximum, after first allowing for the semicircular deviation; then, by moving the rods to or from the centre of the compass, to annul the maximum quadrantal deviation. This error being thus compensated, it will be found that a portion of the rolling or heeling deviation is also removed. The semicircular deviation is then best compensated, by means of two magnets, as follows: Under the centre of the compass is fastened a non-magnetic metallic parallelopipedon of square section, one side of which is parallel to the keel; the lower side of this should be fastened to a metallic disk of the same material, and this so fastened by screws to the base of the binnacle that its position can not be altered with reference to the keel of the vessel. On the upper end of this parallelopipe

don must be fastened a cross-piece, by means of which the whole may be kept always vertical. A steel magnet is provided with a square slit, such that it can be placed any where and in any position upon the parallelopipedon. According, then, as certain co-efficients in the expression for the magnetic disturbance are larger or smaller, the magnet is to be placed either parallel or transverse to the parallelopipedon, and is to be moved up or down until the needle points accurately north and south, when the magnet is to be fastened in that position. The ship is then to be swung, and a third magnet is also to be fastened to the same parallelopipedon in a certain manner described by Garbich, until when the ship heads east and west the needle still points correctly north and south, when this third magnet is to be fastened in its place. With this adjustment the correction of the compass is finished, except in so far as there may still remain a slight error, due to the want of symmetry in the apparatus, and which may be corrected by swinging the ship to the west as well as to the east. In order to compensate for the remaining rolling or heeling deviation, a cylindrical steel magnet, about seven inches long and two thirds of an inch thick, is appropriate, which is to be placed before the needle and inclined to the vertical, at an angle whose tangent is a wellknown co-efficient. This compensation becomes of great importance in high latitudes. In passing into magnetic southern latitudes, the vertical compensating magnet must be reversed end for end. The easiest method of directing the ship toward any given point of the horizon will be attained by the use of a compass described by Garbich, combining in itself both magnetic and azimuthal compass, having three concentric azimuthal circles, and which is to be used in connection with the azimuthal tables computed by Labrosse, which give, for every latitude of the ship and every position of the sun, and for every hour of the day between sunrise and sunset, the angle between the meridian and the sun's vertical." Mittheilungen" Austr. IIydrog. Office, 1874, 167, 257, 426.

ANCIENT MUSICAL INSTRUMENT IN CHINA.

Among the ancient musical instruments of the Chinese is the pien king, which is an assortment of sixteen stones ar

ranged on strings in two series of eight each, one above the other, and each giving out, when struck successively, the system of sounds employed by the ancient Chinese in their music. The size and shape of these stones have been very carefully determined by them after a minute analysis of the sounds peculiar to each one. In order to render the sound graver, the thickness of the stone is diminished to the proper amount, and, to render it more acute, something is cut off from the length. The stones thus arranged remind one in effect of a series of steel bars, as exhibited in acoustic apparatus to illustrate the fact that vibrations above a certain pitch are inaudible to the human ear. Frequent endeavors have been made to decide what kind of stones were employed in the fabrication of the pien king, since they were customarily paid as tribute money more than two thousand years before Christ by certain provinces of China. Certain authors have thought that they recognized in them a kind of black marble; and the editor of the works of Father Amiote asserts that the king, or musical stone, constructed in France from the black marble of Flanders, was quite as sonorous as those of China. Lately a discovery was made at Kendal, in England, of some musical stones, which, when struck with a piece of iron or another stone, gave out sounds of very different pitch, and with eight of which it would be possible to attain a very distinct octave.-13 B, III., 203.

REMARKABLE IMPROVEMENTS IN STRINGED INSTRUMENTS,

Some very remarkable results of persistent investigation have been just communicated to the Physical Society of London by Mr. Hamilton, of Oxford. In prosecuting these researches Mr. Hamilton has for over two years resigned all other work, and he announces finally that, by means of stringed instruments reinforced by reeds, he has been able to secure for these all the advantages of organ pipes, in addition to those which they already possessed. In short, the strings vibrating on the sounding-board are made to imitate exactly in volume, quality, and sustained sound either an open diapason pipe or the largest organ pipe in use, his hearers being satisfied that not only can a string do all the work of an organ pipe in volume and sweetness, but also afford the exquisite sympathetic and blending power hitherto con

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