Electric Buoy.

M. Duchemin proposes to construct Ampêre's electric boat upon a sufficiently large scale, and to use it as a warning buoy on shoals, &c. He proposes to float, by means of cork, a carbon cylinder within a hollow cylinder of zinc, the connecting wire to be made to strike a bell in the usual way. He speaks of small cylinders, but gives no suggestion as to the size necessary to operate a bell large enough to be heard at any distance.

The Stereo-phantasmascope.

From the London British Journal of Photography, No. 280.

Perhaps the most expressive description of the reality of the scene which the stereoscope presents to our senses is conveyed in the brief but terse words of The Times-" Seems? nay, is!"

To increase still more the delusion under which, for the time being, a person labors while inspecting a stereoscope picture, attempts have been made to add to the already marvellous relief of the images in the stereoscope, the additional marvel of apparent motion. For several years binocular pictures have been vended in our bazaars and printshops, in which the effect of motion is obtained in the following manner: If it be required to produce a reciprocating motion, such as a smith engaged in hammering a piece of metal, one view of the pair is taken with the hammer raised, and the other with it down upon the metal then being operated upon. So with sawyers at work; in one view the saw is up, in the other it is down. Other subjects of a similar nature will readily suggest themselves. To see these in motion, the most ready way is to wave between the eyes and the picture a piece of cardboard, or any similar material, which will have the effect of allowing only one picture to be seen at a time, when, on account of the persistence of vision, a stereoscopic image will be seen of an object in apparent motion.

In the cases which we have cited, the motion, it is obvious, will not be of a continuous nature, seeing that only the two extremes of the motion are represented. When more than two positions are to be depicted, some arrangement must be made by which each picture in succession can be presented to the eye.

There is a well known optical toy, the phenakitiscope, in which a series of pictures of the objects to be exhibited in motion are pasted on a disc, which is made to revolve, and the pictures on which are viewed through a slit. This instrument has been employed by our ingenious friends on the other side of the English Channel for the exhibition of "moving photographic images." The defects inherent in this method of viewing stereographs are very ably set forth in an interesting paper by M. Claudet read last week in one of the sections of the British Association, which will be found in the present number of the Journal, and to which we invite the attention of the reader.

It does not, however, appear to be generally known, that an instrument was invented and patented in America some years ago, by which the effects of either rotary or reciprocating motion can be exhibited in perfect stereoscopic relief. The instrument was, at the time of its invention, described by Mr. Coleman Sellers, of whose fertile brain it is the offspring; yet, seeing that the subject has been deemed worthy of being brought before the notice of the British Association, an apology is hardly required for again reviving the subject, and giving a description of Mr. Seller's phantasmascope, by means of which we have seen, in all the stereoscopic relief of nature, a mill wheel majestically revolving with beautiful regularity.

One form of phantasmascope consists of a cylinder D, not more than an inch in diameter, around which are arranged six wings, E E, like the paddles of a water-wheel, and on these wings the stereographs are fixed.

Around the outside of these wings passes a band of tin, G, four inches wide, through which are cut slits, I I, each a quarter of an inch wide and an inch long, the centre of each pair of slits being three inches apart. These slits are close to each of the wings and immediately at the back of each picture, so that through the slits may be seen the picture on the face of the next wing. The ordinary stereoscopic prisms placed at cc combine the pictures as they pass in succession before the eye. The whole of each picture cannot be seen at one time, but according to whether it is turned to or from the observer, so the picture is seen at its lower or upper edge first, and then the vision passes over the card, which has scarcely gone before another is presented to the view. On account of the "persistence of vision " the pauses between the pictures are not perceived.

By the instrument which we have just described, the most wonderful effects of combined motion and relief are obtained; and we are glad of this opportunity of again calling attention to the ingenious and, perhaps, partially forgotten phantasmascope of our friend, Mr. Sellers, and of testifying to the ingenuity displayed in this interesting instrument.

Another new Process of Engraving.

From the London Builder, No. 1159.

A layer of finely pulverized chalk is compressed and smoothed by hydraulic power on a metal plate. The artist draws on this with an ink which makes the lines hard. A soft brush or a piece of velvet rubbed over the plate leaves the inky portion in relief. The whole plate is then saturated with a chemical solution, which turns the chalk into stone, somewhat analogous to Ransome's principle seemingly. From this, impressions may be taken, or stereotypes or electrotypes obtained. The cost of these "graphotypes" is said to be something like one-tenth the cost of wood-blocks, to which the Morning Herald says they are fully equal; but whether this process be likely to come to anything practical, or whether it is to follow so many others into oblivion, we cannot yet say; surely something useful will come of all

these inventions at last.

FRANKLIN INSTITUTE.

Proceedings of the Stated Monthly Meeting, November 15th, 1865. The meeting was called to order with the President, Mr. Wm. Sellers, in the chair.

The minutes of the last meeting were read and approved. The minutes of the Board of Managers were reported, including the following donations to the library: From the Chemical Society, the Statistical Society, the Society of Arts, and the Royal Geographical Society, London; the Natural History Society, Montreal, Canada; Young Men's Association, Milwaukie, Wisconsin; the Commissioner of Agriculture, Washington, D. C.; the Legislature of Pennsylvania; the Schuylkill Navigation Company, Wm. Biddle, and Prof. John F. Frazer, Philadelphia.

The minutes of the various Standing Committees were reported. The Special Committee on experiments in steam expansion, reported progress.

The Report of the Secretary on new discoveries and inventions, &c., was then read as follows:

SECRETARY'S REPORT.

Engineering Works.-The tunnel for supplying Chicago with water from Lake Michigan is making steady and rapid progress, the average rate being 12 feet per day. The cribs for the inlet pier, about two miles out from shore, have been successfully placed, and the iron tubing for the descending shaft at that point is in a finished state.

The Barmouth viaduct, crossing the mouth of the river Maw, North Wales, is a work of considerable extent now in course of construction. Its length is one mile; 770 yards consists of a solid embankment, 740 are of timber, divided into 117 spans of 19 feet each, 109 yards of iron, divided into 7 spans of 40 feet each, and one of 47 feet.

It appears from a paper read before the Mechanical Section of the British Association, during their late meeting at Birmingham, that a coal-cutting machine worked by compressed air has been successfully operated in a colliery (the Blaina works) upon coal of a very refractory and unpromising character. Its rate of cutting is 8 yards per hour, 3 feet deep. The great advantage of compressed air, as a motor for such machines, is its effect upon the ventilation of the mine, while its great drawback is the loss of power consequent upon the loss of the heat developed by the compression, which is largely abstracted before the air reaches the scene of its labors.

A regulating stopcock for use with burning gas and fluids generally, invented by G. G. Percival, of this city, has been this evening submitted to your notice. Its novel feature consists in the insertion of a set screw into a lug on the barrel of the cock, which arrests the motion of the lug which has a pin or plug attached to it in the manner already generally used. By turning this set screw, its projection through the lug is altered so that it arrests the motion of the plug at a different point, and thus the opening of the cock may be regulated.

This is of consequence, 1st. In public buildings, where the lowering of the lights with a common cock is a matter of great difficulty.

2d. In hotels, and even in private houses, waste of gas often occurs from turning the cock too far. This is rendered impossible in this cock by so arranging the set screw that it can only be turned by a key in the possession of the proprietor, or other responsible person, the movement of the cock being then limited by a proper adjustment, cannot be made to exceed this bound by any one else.

3d. Where consumption of gas is calculated by the "average meter system," this contrivance furnishes an easy means of adjusting different burners to a proper average.

Chemistry. An improvement in the process for extracting precious. metals from their ores by amalgamation has been introduced by Professor Crooks, the discoverer of thalium, and the editor of the Chemical News.

This consists in the addition of a very small quantity of sodium to the mercury. By this means, its power of extracting the valuable metal is increased, first, we believe, because its cohesion is decreased, making adhesion to other bodies easier; second, because the strong chemical affinites of the sodium for common impurities keep these from the mercury; and, lastly, because the attraction of this and like amalgams for metals is very strong. Thus we have often noticed the tenacity with which a sodium or potassium amalgam will adhere to the blade of a penknife when preparing this mixture for the development of the ammoniacal amalgam; and with this last substance have even made iron filings into a consistent ball.

From a paper read before the British Association, by Dr. D. S. Price, we learn that the blackening effect produced on lead paint by sulphuretted hydrogen may be counteracted or removed by free exposure to sunlight.

Contact with sodium or potassium causes instantaneously the explo

sion of gun-cotton, according to Mr. W. S. Scott, in a paper read before the British Association at their last meeting. We would call attention to the methods of printing (mechanically) photographs, invented by Messrs. Walter Woodbury and J. W. Swan, independently, which form the subject of an interesting paper, in the Mechanics' Magazine, for September, page 194.

Messrs. Paul and Ernest Depouilly have published a new method of obtaining benzoic acid from naphthaline. The naphthaline is oxidized into phtalic acid; this is combined with lime to form a neutral salt; this is then mixed with an additional equivalent of lime, and heated to 626° or 662° for ten hours in iron cylinders which are immersed in a bath of lead.

A platinum medal has been awarded by the Parisian Society for the Encouragement of Industry to M. Ozouf, a celebrated manufacturer of soda and other effervescent waters, for a process by which pure carbonic acid may be readily supplied. Coke being burned in an appropriate furnace, the carbonic acid generated is absorbed in a solution of carbonate of soda, which is thus converted into bicarbonate. By heating this, the second equivalent of C O, is disengaged, and the solution is then ready for a fresh dose of the gas.

Another substitute for india rubber has made its appearance under the name of Parkesine, which is prepared as follows: Gun-cotton is dissolved in wood naphtha and mixed with oil or resin; it is then vulcanized by use of chloride of sulphur, and may be readily colored by the aniline dyes. Many beautiful specimens of this substance were exhibited at a late soirée of the British Association. We should think that the cost of the materials used would prevent any general application of this compound.

Mr. R. W. Artlett has been experimenting largely with the process for preparation of oxygen from hypochlorite of lime, (CaO, CIO,) mentioned a few months since, and finds that oxides of copper and iron act like that of cobalt in liberating the oxygen from the lime salt. A few drops of nitrate of copper will serve for this purpose.

Another process for oxygen is announced by a M. Carlevaris. This consists in heating together black oxide of manganese and silica, (MnO2 +SiO,,) when silicate of manganese is formed, and one equivalent of oxygen set free, (MnO, SiO, +0.)

3

The equivalent of niobium has lately been determined by Deville and by Blomstrand; the former makes it 47 or 48.3, the latter 39. Night photography having been introduced by means of magnesium, seems to be extending its range of applications, with other bodies. By burning of a pound of a mixture containing phosphorus and nitre, which continued its combustion six minutes, a Mr. Wilkinson, of Chelsea, succeeded in taking a picture of a windmill at the foot of his garden, and even found the neighboring houses to "come up" with great sharpness.

Photographs of the interior of a lead mine have been successfully taken in England by Mr. Alonzo Grant. One in the Wasses MillClose Mine, shows two pipe veins and the surrounding surface over an area of 4 by 6 feet.