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pendent on temperature in quite the same way as that of hydrogen, but increases more quickly with the temperature. The value of these results in the theory of gases is very considerable.—Poggendorff's Annalen, 1876.

CREMATION IN FRANCE, In December, 1875, a committee was appointed by the Council of Health and Hygiene of the Department of the Seine to consider and report upon the subject of cremation. This committee consisted of MM. Baube, Bouchardat, Boussingault, and Troost, the latter being the rapporteur. The report of this committee, after noting that the letter of the Prefect of Police did not suggest any special direction which the investigation should take, states that they confined their attention to the following points: (1) The possibility of effecting the incineration of bodies without production of smell or smoke or deleterious gases; (2) the advantages such incineration might offer as regards salubrity; and (3) the inconveniences it would present as regards criminal investigations, They did not have to concern themselves with the propriety of respecting the celebration of religious ceremonies; that propriety having been recognized by the municipal council, and by the administrative committee which fixed the programme of the competition for the invention of the best process for incinerating dead bodies, or of any other sys. tem giving a like result. It is, further, well understood, they say, that incineration would be in no wise obligatory, but simply optional, under conditions to be determined by a special law. With reference to the first question examined by the committee, the report is very brief. They do not doubt that by having recourse to gas furnaces, like those used in metallurgy, a rapid incineration could be had. It would be possible also to obtain, without any admixture of foreign matters, the ashes of bodies subjected to cremation. No fetid odor or smoke would be evolved, these furnaces being essentially smoke-consuming. Thus there would be no danger to public health to be feared. The conditions of the municipal council's programme might therefore be easily fulfilled, except perhaps that of economy, it being evident that until these furnaces can be occupied continuously they can not be operated economically. On the second point examined, the committee say that in their opinion cremation would present advantages over the mode of inhumation in a common graveyard, where insufficient space is reserved for each body. Fetid emanations and the alteration of subterranean waters may, in fact, result where the earth is saturated with organic matter in decomposition, and the air can not penetrate in sufficient quantity to produce a complete combustion. The most serious inconveniences of our present cemeteries, however, disappear where only a limited number of bodies sufficiently separated are contained in properly per meable strata. The land thus used might be returned to agriculture, after having been closed for a number of years ; for the bodies buried in permeable soil are subjected to a sort of slow and indirect combustion, which does not present any inconvenience so long as the intermediate and dangerous products do not reach the surface of the ground. On the third point, the report asserts that inhumation presents guarantees for society which are not found in cremation, if the question be considered with reference to the investigation and determination of poisons, the existence of which is often not suspected till long after death. Dividing poisons into two classes, those which cremation would cause to disappear and those which it would not destroy completely, the committee say that in the case of the former class, in which rank all toxical substances of organic origin, and also arsenic, phosphorus, and corrosive sublimate--the very poisons, by the way, most commonly employed-cremation would obliterate all traces of the crime, would thus insure immunity from punishment, and so encourage the repetition of crime. In the case of the second class of poisons, which includes copper and lead, for example, while the metal might be found in the ashes, yet the persons interested would, it is clear, always have the opportunity of dispersing those ashes, or of replacing them with others; so that, in this event, the traces of crime would also be easily obliterated. For these reasons criminals might find in cremation a security which they have not in the present process of inhumation, and which it is important not to afford them, for it would be a source of more serious danger to the population than the insalubrity of cemeteries. The objections thus raised against cremation, however, would disappear if the law required that before any

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such operation an autopsy of the body should be made and a chemical examination bad of its principal organs, so as to ascertain the presence or absence of poison. But these examinations, which have value only when they are conducted in a truly scientific manner, are always delicate, even when the field of investigation has been limited by judicial instructions; and they would become extremely long and troublesome in the absence of any preliminary indication. Moreover, even if it be admitted that they would be conducted with the necessary care and skill so long as the number of cremations is small, it by no means follows that this would be the case when the demands for incineration multiplied. Annales de Chimie et de Physique, V., viii., August, 1876,571.

THE DIETHEROSCOPE. Professor Luvini, of Turin, exhibited at the Scientific Loan Exhibition in London, and also at the International Exposition at Philadelphia, an instrument on a totally new principle for measuring atmospheric refraction. Its construction is as follows: If one half of a lens be covered, the image produced by it will differ only in brightness from that formed by the uncovered lens. Moreover, if we take two lenses of unequal focal length, and place them at a distance from each other equal to the sum of their focal lengths, the rays emerging from the second will have the same degree of convergence as those entering the first; i.e., the object looked at will appear in its natural size and position. Any agency-such as irregular refraction of the atmosphere-which alters the path of the light from the object to the system of lenses will alter the position of the image formed. If now we have a telescope of such a size that the lenses of the dietheroscope cover half of the aperture of the object-glass, two images of the distant object can be formed-one as seen through the dietheroscope, the other as seen beside it ; the latter image being formed by the rays coming directly from the object to the telescope. If the telescope is astronomical the latter image will be reversed, while that transmitted through the dietheroscope will be in its natural position. The distance between these two images will depend upon the refraction of the atmosphere, and so the instrument may be used to meas. ure that refraction. Professor Luvini proposes that four of his instruments be placed at each observatory, directed to the four cardinal points, and that by their means observations be taken at regular intervals of the condition of atmospheric refraction all around the observatory. He believes that by this method information of coming changes of weather can be obtained earlier than by the means now at the disposal of meteorologists.—18 A, August, 1876,558.

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IMPROVED MODE OF MOUNTING MICROSCOPIC OBJECTS. Professor Hamilton L. Smith, of Hobart College, New York, has communicated to the Journal of the Microscopical Club a new method of making cells of moderate depth, designed for opaque objects, which is at once simple and easily put in practice. The wall of the cell is made of a brass curtainring. Out of a sheet of dark-green or black wax a disk is punched, a trifle larger than the ring, which is fastened to the centre of the slide by melting. The ring is pressed into this, centred, pressed quite through, and the whole finished with Brunswick black. The object is attached to the wax by previously moistening it with turpentine. The cover is dropped just within the ring, its surface being flush with it, and fastened with the black varnish. The soft and delicate appearance of these wax backgrounds gives an exquisite finish to the slide, the absence of obvions cementing material for the object lending an additional charm. Dr. Smith also uses the sheet wax for cells, cutting rings out of it of any desired color, and attaching these both to the slide and cover by slight fusion. The rings are prepared by means of a specially devised press, consisting of a plunger the size of the hole, a centring and a supporting plate. Disks of the sheet wax are dropped in and the hole made in them, the plunger being wetted to prevent adherence.

CURIOUS JAPANESE COMPASS. Captain J. H. Murray, of the screw-steamship Scaresbrook, obtained from a Japanese pilot at Yokohama, in 1874, a remarkable compass, a description of which has been given to the public by Buckland. The compass was taken from the wreck of a junk which had been lost on the island of Vries, a volcanic island at the entrance to Yokohama, the smoke of which, with the snow-capped peak of Fusiyama, indicates the

entrance to the barbor. The pilot could give no information about the compass, except that it was found on board the wreck. It is of a circular form, measuring 13.5 inches across, is cast in bronze, and weighs twenty-one pounds. It has a thick rim, in which two ordinary compasses are set, one on each side. The centre of this remarkable plate-like looking object is considerably raised from the surface, and is covered with a number of raised spots or stars of various sizes, each more or less connected by lines with its neighbors. The shapes of these star-like objects are remarkable; in the centre there are five which are larger than the rest. Then there is another group very like a net; another group represents almost a complete circle of these stars; another represents a Y, with the arms closed together; another a Y with the arms extended. Altogether there are no less than two or three hundred of these elevated spots of different sizes. Running throughout the whole series are several lines radiating from a circle drawn around the centre. The brass rim on which the compasses are set is divided into 360 degrees, the same as in an English compass. At every thirty degrees there is a Japanese character. Neither Captain Murray nor any one to whom he has shown this curiosity at home or abroad has any idea whatever of the meaning of the star-like bodies in the centre, or for what purpose the Japanese used them; but it is quite certain that they must have been of some use to them. It is most interesting that these rude characters should be united in the same instrument with the 360 degrees of modern civilization. The casting of the instrument is marvelous.-2 A, 1876.

CLAMOND'S HERMO-ELECTRIC BATTERY. The latest form of the Clamond battery consists of an alloy of two parts of antimony and one of zinc as the negative metal, and ordinary tinned sheet-iron as the positive element, the current at the heated juuction flowing from the iron to the alloy. This alloy is cast in the form of a flat bar, broader in the middle than at the ends, and measuring from two inches to two and three-quarter inches in length, by three eighths to one inch in thickness. The sheet-iron, properly stamped out, is placed in a mould into which the melted alloy is poured; before the alloy has cooled the mould is open

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