NOTES AND NOTICES.

The Great Northern (launched last week at Belfast,) is the largest vessel ever built in Ireland. Her dimensions are 220 feet in length, 37 feet beam, and 26 feet deep in the hold; burden, 1,750 tons, B.M.; she is to be fully rigged as a 50 gun frigate, the length of mainmast to be 90 feet, and 36 inches diameter, mainyard 79 feet, and 22 inches diameter in the slings, foremast 83 feet, and mizenmast 76 feet; she will be able to spread 6,400 yards of canvass. There are three decks, the upper one to be left entirely clear for action, and to be pierced for 44 guns; the windlass and capstan gear will be placed between decks. She is to be propelled by Smith's Archimedean screw, which will be 12 feet diameter, and 14 feet pitch, but the length will be only 7 feet; it is to make 88 revolutions per minute; the gearing consists of a cog-wheel 20 feet diameter, working into a smaller wheel, of 5 feet diameter, upon whose axis is the shaft of the screw. The engine power consists of two cylinders, 68 inches in diameter, 4 feet 6 inches stroke, and to make 22 strokes per minute; nominal power about 370 horses; there are to be 4 air-pumps, 19 inches diameter, and 4 feet 6 inches stroke, and cylindrical boilers. The engines are to be placed close abaft the vessel, leaving the midships clear for passengers. Derry Standard.

The Great Britain (late Mammoth) is not now expected to be finished before the spring of next year. The Montezuma Steam Frigate-A very successful trial was made, last week, of a new steam-frigate, which has been built for the Mexican Government, and appropriately named the Montezuma. She was constructed at the yard of Messrs. Wigram and Green, and her engines, which are of 300 horses power, and on a similar principle to those on board Her Majesty's steam-frigates Gorgon, Driver, Styx, &c., were supplied and titted by the firm of Messrs. Seaward and Capel. Her burden is 1,100 tons, but she draws no more than nine feet water when fully equipped, and is built to carry two swivel guns, 68pounders, on the upper deck, besides the usual number of small guns. Although constructed rather for fighting purposes than for speed, she steamed at the rate of 10 miles an hour, against tide both ways, the engines making 21 strokes per minute. A new disconnecting apparatus, for releasing either paddlewheel, which was tried, was found to answer admirably.

High-pressure Boiler Explosion. The last arrivals from Canada bring an account of an explosion on board the steamer Shamrock, attended with a most frightful destruction of human life. The list of sufferers, "of the English portion" alone, includes 43 killed, and 20 wounded. The Shamrock was a new boat, and built at Niagara; and her engines, which were of 32 horses power, were on the high-pressure principle. The engineer of the vessel stated, at the coroner's inquest, that, "according to the directions of the builders of the engine, he was allowed to carry 85 lbs. of steam, but that at the period of the accident there were not more than 70 lbs. of steam." [Exactly the pressure at which the Locomotive, now working on the Thames, is said to be worked.)

Steam Pile Driver.-Among the many improvements in machinery which are daily taking place, we notice with pleasure the introduction recently, at the harbour works, of a self-acting machine for driving piles. The moving power is taken from a cylinder connected with the engine erected for pumping out the water in the dock, which does its work in a most admirable manner. There are two other pile-driving machines, wrought by manual labour, in operation alongside of it, requiring nine men to each; and this self-acting machine, attended by one man, gives seven strokes for every one that

the others give, so that it does the work of sixtythree men. It can be extended in the same proportion to any power. It is the invention of Mr. James Milne, engineer at the dock.-Montrose Review.

The Thames Tunnel was opened on Monday last for the first time on the Wapping side of the river, and upwards of 500 visitors, of all nations, passed through the tunnel as far as the shaft on the Rotherhithe shore. The Wapping shaft is about 90 feet in height, and is surmounted with a handsome dome, which is glazed, and light and air admitted. There are two staircases, one terminating close to the western arch, and the other leading to the eastern arch. The western arch only is opened for visitors; but the eastern one appears likely to be appropriated to the same purpose in a few weeks, and a great number of workmen are now actively employed in preparing it for the reception of the public. The erection of the circular staircases in the shaft on the Surrey side, now closed to the public, will be commenced forthwith by the contractors, Messrs. Peto and Grissell, who have completed the staircase on the Middlesex shore. The time allowed for the performance of the contract is three months, when the tunnel will be opened as a thoroughfare for foot passengers; the toll to be charged is, we understand, to be Id. each person. Some time, however, must elapse before the circular staircases and inclined planes for horses, cattle, and vehicles can be formed; but the plans are already framed, and the works will be conducted with all possible expedition. The engine and pumps are constantly at work in the Rotherhithe shaft, to clear the tunnel of the accumulation of water caused by the land springs. There is a culvert under the Western arch, into which the waters are collected and pumped out, which keeps that side of the tunnel always dry, and as a current of air now passes through the excavation, the place is rendered comfortable, and by the aid of the gas lights, which are always burning, the temperature of the atmosphere is nearly the same as it is on shore.-Times.

Progress of Steam Power in France.-We find by a recent statistical return, that at the end of last year there were in France 179 establishments having steam power, containing 5,600 boilers, of which 1,889 were for the purposes of heating, and 3,511 for giving motion to machinery. There were, besides, 2,637 engines, the aggregate of which was equal to 39,779-horses power. At the same period there were 260 steam-boats, being 128 more than in 1838, without comprising those belonging to the state. The number of engines was 400, of a force equalling together 45,000-horses power. The number of passengers conveyed by these vessels was 2,500,000, being 800,000 more than in the preceding year. The increase of merchandise sent by them on freight was equally remarkable, having exceeded by more than 60,000 tons the quantity thus conveyed in 1840. The locomotives employed on the rail-roads in the departments of the Seine, Rhoute, Herault, and Loire, were in number 118, and in force upwards of 300-horses power. Of these, about 35 were of French manufacture.

Erratum.-Mr. Jubber requests us to state, that his patent being dated 4th June, 1842, his specification could not have been enrolled, (as stated by mistake in our last,) on the 1st December, 1841.

INTENDING PATENTEES may be supplied gratis with Instructions, by application (postpaid) to Messrs. J. C. Robertson and Co., 166, Fleet-street, by whom is kept the only COMPLETE REGISTRY OF PATENTS EXTANT from 1617 to the present time).

[Patent dated 11th January, 1842.

The improvements which form the subject of this patent are remarkable for the union which they exhibit of great ingenuity of contrivance, with extraordinary simplicity in the working results.

The chief improvement consists in dispensing, in lifting-pumps, with the moveable valves in common use, and avoiding thereby the great liability to derangement to which such valves are necessarily subject. Mr. Jeffree's plan for this purpose presents an obvious analogy to the slidingvalve system adopted of late years in steam-engines; but differs very much from it in its details.

"To the side of the barrel of the pump, he affixes a plain-surfaced piece of wood or iron, of an oblong form, as represented by fig. 1, in the accompanying engravings, having six rectangular apertures in it, a, b, c, d, e, f, communicating with different passages made through the body of the said piece, and represented in the sectional views, figs, 2, 3, and 4. The apertures a and ƒ communicate with passages which lead into the barrel of the pump, one on each side of the piston, as shown in the horizontal section, fig. 2; the openings b and d lead upwards to the discharge-pipes, as shown in the vertical section, fig. 3; while the apertures e and e lead downward to the well, or other source of supply, as represented in the sectional view, fig. 4, (the discharge and supply pipes being omitted in the engravings, as unnecessary to a clear comprehension of the invention.) To the plain-surfaced piece fig. 1 is adapted another plain-surfaced piece, fig. 5, (the two pieces being ground true, to fit each other exactly,) and having six rectangular apertures, a2, b2, c2, d2, e2, and f2, leading to passages in the said piece 5, which communicate with each other in the manner shown in the horizontal section, fig. 6. To the outside of this piece, 5, is attached a rod, g, as shown in fig. 6, which rod is parallel to the piston-rod, and moved to and fro simultaneously with it, and by the same power, whatever that may be. The better to preserve the parallelism of the piece 5, it may be made to slide within flanges raised on the face of the piece 1; but when the pump is short, this is not thought to be necessary.

"The action of the pump is as follows. Suppose the piston is at the bottom, or farther end of the barrel, the two pieces I and 5 will then be face to face, or in full contact, and the apertures and solid parts of the two faces will be in such relative positions to one another, that one of each of the

three pairs of apertures, the pair leading to the barrel, (a and b,) the pair leading to the discharge-pipes, (b and d,) and the pair leading to the well, or other source of supply, (c and e,) will be open, and the other shut. The piston being now raised or drawn out, the vacuum produced causes the water to flow up from the well, or other source of supply, through the aperture e, in the face of the piece 1, into the aperture e, in the face of the piece 5, whence it passes through the aperture f, fig. 1, into the barrel of the pump; by the return stroke of the piston, the water which was raised by the preceding stroke is expelled from the pump-barrel, through the apertures ƒ and d, into the upward discharge-pipe connected with the opening d; while, at the same time, the vacuum produced behind the piston causes the water to flow up from the well, or other source of supply, and pass through the apertures b and a into the barrel, ready to be discharged at the next up or outward stroke of the piston. At every subsequent stroke of the piston there will, of course, be always one body of water supplied to the pumpbarrel, and one discharged from it, and that alternately, at opposite ends of the piston; and if the discharge-pipes connected with the openings b and d, are made to empty themselves into one common mouth-piece, the water will be discharged in one continuous stream."

A pump of this sort is obviously liable to no other derangement than what may occasionally arise from some of the apertures being obstructed; but in that case the evil can be at once got at, by simply taking off the upper piece, fig. 5, and when the obstruction is removed, the pump becomes as good as ever.

For water-closets on board ships, the patentee considers this pump to be particularly well adapted; since it requires no supply cistern, the space required for which is often an insuperable objection to the use of these conveniences at sea.

Another plan of construction, more nearly resembling the slide-valve used in steam-engines, and which might, in fact, be advantageously substituted for it in many instances, as it would do entirely with the ordinary jacket and stuffing-box, is shown in fig. 7 and 8.

Fig. 7 shows the pump as it would be, if fitted with a slide-valve of the ordinary construction; and fig. 8 shows the sort of valve which the patentee proposes to substitute for it. In a pump of the