For an elastic material for tubing suited to the conveyance of gas, and not liable to be affected by alterations in temperature, or to be acted upon by the gas itself.

For improvements in the oxy-hydrogen microscope, and the means by which a bright object may be presented on a dark ground.

For a rapid means of reproducing artistic designs or sketches, without the intervention of hand labor, for surface printing by machinery.

For a means of producing impressions from copper-plates by machinery, without the intervention of hand labor.

For the invention of a simple electrometer, to be sold at a moderate price, for determining the amount and kind of atmospheric electricity; and which will show uniform results under uniform circumstances.

For the invention of a marine mercurial barometer, which will obviate the oscillation of the mercury, and fulfill all the conditions necessary to make it a good and reliable instrument; and be sold at a moderate price.

For the invention of an anemometer for determining the direction of the wind, and its pressure in pounds on the square foot, to be sold at a moderate price.

For the invention of an anemometer for measuring the force and direction of the wind on board ship correctly, distinguishing the amount due to the wind and that due to the ship's velocity, varying with the angle.

For an instrument that will detect the local attraction of a ship at sea, with reference to the compass, by direct observation of the heavenly bodies, with out the process of turning the ship.

For the production of a lustrous wool, to be used in lieu of silk, in the manufacture of fringes, carriage laces, etc.

For the successful application of some new means (as electricity, or photography, for instance) for producing ornamental designs in woven fabrics, which shall be cheaper, and easier of application, than those at present employed.

For an efficient means of removing the fatty matters from skins, so as to render them capable of receiving mordants by the ordinary printing process. For the best mode of dressing kid for the upper leather of boots; the improvements required are, strength of the grain and a good firm black dye. For the best specimens of cisterns, suitable for household or other purposes, made of glass in one piece.

For a chair or couch affording the greatest possible amount of support to persons of weak physical powers while writing.

For a means of rendering the plaster used for casts, less absorbent, and more adhesive, so as to facilitate its use for repairing purposes.

For the best means of turning to useful account, slag of furnaces, in a coarse, refined, or combined state.

For the best design for a flower trough or vase, ornamented in bas-relief, and capable of being cast from a mold in one piece, and of being produced in terra cotta.

SUBMARINE TUNNEL BETWEEN ENGLAND AND FRANCE.

M. Favre, a distinguished French engineer, has recently brought before the public an extraordmary plan for constructing a submarine tunnel under the channel from France to England; and what is no less extraordinary, the enterprise finds supporters, and may be considered as seriously entered upon. : The length of the proposed tunnel will be about 18 miles in length, to which must be added about 1 mile that will run under the shore on each side in order to give the necessary gradual ascent from the tunnel to the surface of the earth. The distance between the top of the arch of the tunnel will be less than 27 yards, so that all danger of the ocean breaking through will be avoided by this enormous thickness of what may be called the wall of the tunnel. This tunnel will be lined with a double arch, the first of granite and of impermeable cement, the second of thin iron plates pierced like a colander with small holes, so that the slightest leakage will be instantly discovered. Through this tunnel it is intended that an atmospheric railroad shall be established, thereby avoiding the smoke consequent on the use of the ordinary locomotive, by which the transit from end to end will be performed in 27 minutes. The natural objection which arises to the practicability of this stupendous work is the difficulty of getting rid of the earth and stone quarried out of the bowels of the subterranean chamber. In the ordinary course of engineering, every barrow-load of earth would have to be brought to one of the mouths of the tunnel, which operation would consume so much time and labor as to add enormously to the expenses. This difficulty M. Favre proposes to surmount by sinking along the course of the tunnel what he calls "Maritime Wells," which will divide this subterranean gallery into sections of about 11,000 yards each in length. By these wells all the encumbering earth will be thrown into the sea, forming islands about the wells themselves, and so strengthening them. These wells will serve the purpose of ventilating the tunnel. The cost of the whole is estimated in round numbers at 100,000,000f, or $20,000,000, and the cost of each yard will be 2,695f., or $539. The soundings that have been made in the English Channel, show that the soil is very favorable to such an undertaking. At a certain depth freestone has been found, so that the vault of the tunnel will be formed of a stone impermeable to water, and capable of sustaining, in a thickness of 27 yards, an enormous weight.

The estimates of the produce of this submarine railway, are based on the supposition that 200,000 passengers now travel backward and forward between France and England at the present day. Of course this number would be increased by the facilities offered by the submarine railway. France now consumes 80,000,000 of metrical quintals of pit coal, 8,000,000 of which is furnished by England, the remainder by Belgium and Prussia. As the superior facility for transport would enable England to supply much of this coal now brought from those countries, the Company calculate that their transport of coal will amount at least to 10,000,000 of tons, which will yield a profit for transport of 10,000,000 of francs yearly for this branch of commerce

alone. Besides, the 3,000 ships that now annually enter the harbors of Calais, Boulogne, and Dunkirk, with a tonnage of 40,000 tons, will, of course, yield a great portion of their traffic to this railway, which will be safe, expeditious, and comparatively inexpensive.

Engineers are at present engaged making surveys and soundings for the purpose of estimating, as accurately as possible, the utmost cost, and contractors, offering guarantees of responsibility, are ready to take work.

The following is the conclusion of a recent report on the subject:

"In conclusion, we are impressed with the conviction that we have proved, not only that this project is possible, but that it will be comparatively easy to construct a railway under the Channel. We have now developed our system of maritime 'wells,' which would divide the subterranean tunnel into different sections. Our plan of a double vault would give as ample securities as any of the ordinary railways possess. The tunnel would set aside the arm of the sea which separates France from England. It would bind, upon the most solid foundation, the Continent with Great Britain, which is at present isolated from the rest of Europe. Our project has been received every where with the most lively sympathies, and an Anglo-French Company will be immediately organized upon the most powerful basis to execute the railway of Calais."

NEW METHOD OF REPAIRING A SHIP WITHOUT DOCKING.

The immense British screw steamer, Himalaya, having become seriously damaged in the Black Sea, it became requisite that repairs should be made at Malta. There being no dry-dock at the place of sufficient capacity to receive her, this difficulty was surmounted in the following manner: The Himalaya is an iron vessel, constructed on the life-boat principle, with water-tight compartments. She was taken into the dock about noon, and water introduced into her fore compartment with syphons, for about two hours. At that time a powerful purchase was fixed aft to four derricks, and hove taut, when she started up 18 inches. Three hours later the purchase was hove again, when she moved up 12 inches, and so continued until half past eleven P. M., when it was found that the shaft-hole of the propeller was 15 inches out of water. At this time her immersion was 7 feet 10 inches aft, and 27 feet forward, with about two feet of water under her forefoot; and this was accomplished so easy that persons witnessing the operation almost doubted their own eyes. She strained nothing whatever, and when her defects had been made good, she was let down, the water in her fore-compartment pumped out, and in 12 hours she regained her natural position. It will be seen that she was waterborne the whole time, and that by destroying the buoyancy forward the assistance she required aft to raise her was comparatively small. This operation, probably, would answer only for an iron vessel, inasmuch as any wooden vessel, as ordinarily constructed, would be found deficient in longitudinal strength.

The Nautical Magazine, in this connection, also recalls to remembrance an ingenious plan adopted some years since, at the Navy Yard at Norfolk, for

repairing a vessel without docking. The United States' ship of the line, Delaware, immediately after launching, lost a portion of her copper. There being no government dry-dock at that time, the ship was allowed to remain in that condition until orders came to fit her for sea, when, in order to make her outfit as complete below as above water, Mr. Broadie, the foreman of the yard, proposed and obtained leave to make a box, with open top and side, to cover the part to be repaired, one side to fit the side of the ship. The locality of the spot from which the copper was removed being known, there was little difficulty in preparing timbers of the shape of the side of the vessel, upon which a box, or diving-bell, was projected, of sufficient size and strength to sustain the pressure of the water from without when the water from within was removed. When finished, the edges, coming against the side of the ship, and forming the margin of the open side, were padded with canvas, so as to be brought close to prevent the passage of the water, and the whole fabric being provided with ring-bolts, for securing the box to its place, by means of ropes passed under the keel and up the opposite side, in like manner it was secured firmly fore and aft; and when thus made fast, the water was pumped out, and workmen went down to the place, when the copper and worm-eaten plank were removed, a new plank inserted, fastened, caulked, and re-coppered. All this while the ship was afloat, and the defective part from 15 to 18 feet below the surface of the water. The ship went to sea and performed the usual cruise of three years, more or less, and Mr. Broadie was awarded $500 by Congress, for his mechanical skill.

IMPROVEMENTS IN SHIPS AND STEAMERS.

Cunard Steamship Persia.-During the past season, a new iron steamer, the Persia, has been launched by the Cunard Steamship Company, at Glasgow, Scotland. This vessel, at present, is the largest steamer afloat, far exceeding in length, strength, tonnage, and steam power, the Great Britain or the Himalaya, and exceeding also by no less than 1200 tons the internal capacity of the largest of the present splendid Cunard liners. Her chief proportions may be summed up as follows:—

Stupendous as the Persia is, the lines of beauty have been so well worked out in the preparation of her model that her appearance is singularly graceful and lightsome. Yet this mighty fabric, so beautiful as a whole, is made up of innumerable pieces of ponderous metal, welded, jointed, and riveted into each other with exceeding deftness. The keel consists of several bars of iron about 35 feet in length each, joined together by long scarfs, and as a whole 13 inches deep by 4 inches thick. The framing is constructed in a manner at once peculiar, and securing the greatest possible amount of strength.

The iron stern-post is 13 inches in breadth, by 5 inches in thickness, carrying the rudder, the stock of which is 8 inches in diameter. The framing of the ship is very heavy. The space between each frame is only 10 inches, and the powerful frames or ribs are themselves 10 inches deep, with double angle irons at the outer and inner edges. The bow is constructed in a manner at once peculiar and affording the greatest possible strength to this important part of the ship. The framing is placed normally to the stern, the effect of which is that, in the case of collision with other ships or with rocks, or icebergs, the strain would fall upon the very strongest material within the structure. The plates or outer planking of the ship, so to speak, are laid alternately, so that one adds strength to the other, and they form a whole of wonderful compactness and solidity. The keel plates are of an inch in thickness; at the bottom of the ship the plates are of an inch in thickness; from this section to the load water line they are of an inch, and above this they are of an inch in thickness. The plates round the gunwale

are of an inch in thickness.

The Persia has seven water-tight compartments. The goods are to be stowed in two of these divisions. These goods' stores, or rather tanks, are placed in the center line of the ship, with the coal cellars or bunkers on each side of them. At the same time, the vessel is so constructed as to have in reality a double bottom under these goods' chambers-so that if the outer were beat in or injured, the inner would, in all likelihood, protect the cargo dry and intact. The chambers are perfectly water-tight; and in the event of accident to the hull, these tanks would of themselves float the ship.

Steamer Ocean Bird.-About three years ago the project of establishing a line of European steamers from New York, to make the passage across the Atlantic to the nearest port on the coast of Ireland, within one week, was broached by Mr. William Norris, an eminent engineer of Philadelphia, who, together with several distinguished gentlemen of New York, commenced the enterprise. Mr. John W. Griffiths (now editor of The Nautical Magazine), marine architect of New York, was instructed to build a steamship capable of going 20 nautical miles an hour, that would accommodate from 60 to 80 passengers, and coal enough for 3,000 miles of steaming, at a cost of not more than $120,000. Mr. Griffiths submitted his plans for a steamer capable of attaining this speed, with a mean draught of water of 7 feet, so modeled that she would lift her bows over the wave instead of cleaving it, and be sustained by the middle of her length rather than by the ends, thus removing the main cause of pitching or divergence from the horizontal position, and enabling the hull to glide over instead of cutting through the water. The plans were approved, the work progressed satisfactorily toward completion, and the vessel was nearly ready for launching, when the failure of Mr. Norris brought her under the hammer of the United States Marshal. The present owner not choosing to complete her according to this original plan, Mr. Griffiths declined proceeding with her construction, and she was consequently finished by other parties, with modifications. These consisted in a reduction of five per cent. of the propelling power, the addition of another deck weighing 194 tons, making four decks altogether, and a curtailment of three feet in the