NEW STEAM-VESSELS.

THE following are the most important constructions of the past year, either as regards stupendous size, or novelty of principle:

The Great Britain, iron Steam-ship, nearly completed, by a Company, at Bristol, (Humphreys, engineer,) is minutely described by Mr. J. R. Hill, C.E., in the Mechanics' Magazine, No, 996. The cut shows a longitudinal vertical section of the entire vessel: AB. Surface line of upper deck. CD. Principal promenade and dining Saloons, 110 and 100 feet long. E. Cargo-deck,_ 65 ft. long by 9 ft. high. F. Iron Freshwater tank. G. Coal-store, and room for engineers. H. Elevation of Engines. I. ditto of boiler. JJ. Iron deck over boiler for cooking apparatus. K. fore or second-class Saloon. L. lower-fore Saloon. M. & N. Iron-floored Cargodecks. O. Air-chamber, from boiler to fore bulk-head. P. Officers' berths, &c. Q. Sailors' Mess-room. R. Sailors' berths. S. Water-closets. T. Ship's stern-post, through which the screw passes, and to which the side plates are riveted. U. Shaft from engines to screw. V. Diagonal stay from the ship's side to the sternpost, in which the end of the screw spindle revolves. X. Keel under the screw, uniting the stern-post to the vessel. Y. Hollow rudder-foot to receive the stern-post, which forms its pivot. Her main dimensions are, length of keel, 289 feet; from figure-head to taffrail, 320 feet; beam, 51 feet; total depth, 31 ft. 4 in.; tonnage, about 3,500 tons. The hull is divided into 5 distinct compartments, by water-tight iron bulk-heads: the decks, of wood, are the cargo, two cabin, and an upper: her lines are very beautiful, and adapted for the highest speed; and, although, perhaps, she is the strongest vessel ever built, she has a remarkable air of grace and lightness. Her engines will be 1000-horse power; she will accommodate 490 persons, and there are to be six masts. She is to be propelled by the Archimedean screw, shown in the first and second of the annexed figures. Mr. Hill states: " allowing the diameter to be fifteen feet, the diameter of the circle of effect would be about 12 feet 6 inches, or about 39ft. 6 inches circumference: therefore, the mechanical constructions, if developed to a straight wedge, would be represented by AB, in the third figure-line of axis; CD, distance passed over by one revolution, (13ft. 2in.): DE, circumference of circle of total effect; and CE, acting face of the screw.

The amount of resistance caused by the adhesion of the water on the face of the screw will very much depend on the smoothness of the surface; or probably, a thin disc of water will be carried round with the screw, and the

friction take place amongst the particles of water at some slight distance from the face; FG, (in the next fig.) shows the divergent lines of the cone of motion communicated to the water; and if the above premises be correct, it appears to promise a greater effect than has generally been expected, inasmuch as the direction of impact of the screw does not make so great an angle from the line of the axis."

The Great Northern, built at Londonderry by Coppin, is fitted with Smith's Archimedean screw, and is one of the largest vessels to which that principle has been hitherto applied. Her dimensions are:-Extreme length 247 feet; length between perpendiculars 222 feet; extreme breadth 37 feet; depth in hold 26 feet; draft of water 16 feet, with a dead weight of 1,300 tons, consisting of coals, ballast, machinery, &c. The diameter of the cylinder is 68 inches, the length of stroke 4 feet 6 inches, and the number of strokes per minute 17; the diameter of the propelling screw is no less than 11 feet. The Great Northern is frigate-built, pierced on her upper deck for 44 guns, and fully rigged as an ordinary sailing-vessel. The main mast is 90 feet high, and its diameter 33 inches. The length of main-yard 79 feet, and the diameter 224 inches. When in full sail, she spreads no less than 6,700 yards of canvas. Her speed under steam power only is nine and a half statute miles per hour. Her machinery is near the stern, leaving the hold entirely free for mercantile purposes; and the boilers and furnaces are all placed below the water-line. The machinery occupies about one-sixth of the tonnage of the vessel. The consumption of fuel is about one ton per hour; and with six hundred tons of coals on board, she will take in one thousand tons of measurement goods, and accommodate between decks eight hundred troops.

The Cormorant, (Government) Steam-frigate is fitted with a pair of engines of 300-horse power, by Fairbairn and Co. The diameter of the cylinder is 65 in., and length of stroke 5ft. 3 in.; the average number of strokes, during trial, was 214, the boilers amply generating steam; speed through still water, 11 miles per hour, but greater speed will be attained.

The Montezuma Steam-frigate,-built for the Mexican Government by Wigram and Green, has engines of 300-horse power, on a similar principle to those on board the Gorgon, Driver, Styx, &c., by 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, 68-pounders, 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. She has a new disconnecting apparatus, for releasing paddle-wheels. The East India Company's Steam-frigate Acbar, is of the first class, armed with two eight-inch guns, and four long 32-pounders, with a complement of 160 men; carrying five boats, on two of which are mounted brass 12lb. howitzers. The engines are of the collective power of 350 horses, by Napier, of Glasgow. She carries 500 tons of coal, which, with a consumption of a ton an hour, will enable her to steam 20 successive days.

The Hindostan, of 1,800 tons burden, built by Messrs. Wilson, of Liverpool, for the Oriental Steam Navigation Company, is intended to ply between Suez and Calcutta direct, calling at Aden, and Point de Galle, in the island of Ceylon; so that the whole distance from England to Calcutta will be performed in 30 days. Though larger than the Oriental, the Hindostan is on precisely the same plan; and another steamer, of the same size and construction, to be called the Bentinck, also intended for the line from Suez to Calcutta, is in progress.

The Guadaloupe, built for the East India Company's navy, is the largest iron Steamer yet constructed. Her length from the figure-head to the taffrail is 201 feet, and her breadth of beam 30 feet 1 inch; and her tonnage, per ad measurement, nearly 800 tons. She only draws 9 feet of water, with provisions and water for 120 men. and 10 days' coal on board. She carries two large pivot guns, one forward and the other aft, 68-pounders, on sliding carriages of oak, the under-frame working on circular rails of brass, secured to the deck. The weight of each gun, including the carriages, is from 5 to 6 tons. She is brigantine-rigged, and is a very handsome vessel.

The Memnon Steam-frigate, (E. I. C.) of 1,100 tons, mounting two 64pounders and four 32-pounder guns, has been built by Fletcher, and fitted with engines of 400-horse power by Maudslays and Field. The boilers, which are of copper, are furnished with a change-water apparatus, by which the salt water is kept from exceeding a certain point of saturation. There are four steam cylinders working in pairs, the piston-rods being attached to a T-piece, from the lower end of which a long connecting-rod proceeds up to the main crank-shaft. The engines are fitted with expansion gearing, so as to admit of the consumption of fuel being regulated to suit every circumstance of slow or quick steaming. The paddle-wheels, 26 feet in diameter, are fitted with the disconnecting gear by Maudslay. The engines work with a beautiful motion, the vibration being scarcely perceptible. The vessel, with her heavy cargo, with 300 tons of coals, is propelled by steam alone at 114 miles per hour.

The Trent West India Mail Steam-ship has engines of 430-horse power, by Miller and Ravenhill; diameter of cylinder, 74 inches; length of stroke, 7 feet. The condenser, cylinder bottom, air-pump bottom, and support for the main centre, are cast upon the foundation-plate. The framing has metallic joints, and brass and copper are unsparingly substituted for iron. The engines work very smoothly, with a consumption of only 16 cwt. of coals per hour; with a pressure in the boiler of only 3'78 lbs. per square inch; the mean pressure on the piston is only 14.17 lbs. per square inch. The difference between the vacuum in the condenser and the vacuum, is only 28 lbs. of pressure per square inch.-Cin. Eng. and Arch. Journ., No. 55.

The Queen iron Steamer, built by Pasco, has engines by Messrs. George and Sir John Rennie. She is 160 feet long between perpendiculars; of 16 feet 6 inches beam; 8 feet 9 inches deep; and draws about 4 feet 3 inches water; her cylinders are 29 inches in diameter, and the length of stroke 4 feet 5 inches; the average number of strokes per minute, 34; pressure of steam in boiler 8 lbs. ; the condenser vacuum, equal 273 inches mercury; the diameter of paddlewheels 16 feet 6 inches; width of ditto, 8 feet; her speed about 16 miles per hour, with the entire absence of vibration in the vessel.-Mechanics' Mag. No. 992.

The Little Western, built at Bristol, by Acramans, Morgan, and Co., of 721 tons burthen, measures between perpendiculars 200 feet, and over all 216 feet; keel admeasurement, 195 feet; breadth clear of paddle-boxes, above 27 feet;

over all, exceeding 47 feet; deck, flush from stem to stern, and she has two masts. Her engines are horizontal and low-pressure, and 80-horse power each. Her trial speed was nearly 15 miles per hour.

The Anti John Scott Russell is a small iron vessel, 53 feet long, by 6 feet beam, and 3 feet 3 inches deep; and draws 17 inches at stern, and 13 inches fore, or 15 inches mean. The paddle-wheels are 6 feet 5 inches diameter, out and out; with 10 float-boards on each wheel, 2 feet 9 inches, by 74 inches. She is propelled by one rotatory steam-engine, patented by Beale; the cylinder 14 inches diameter, and 94 inches long, (measured transversely,) in the clear of the casing. The drum is 12 inches diameter, with 3 indents for 3 rollers, 4 inches diameter, and 94 inches long, which perform the office of piston. At the top is the steam-pipe: when the aperture is opened, the steam passes down the pipe, and acts against the back of the roller, pressing it forward until it reaches the aperture on the opposite side, where the steam is allowed to escape into the eduction-pipe, and thence into the condenser. The apertures are always open-one for the reception of steam, the other for its exhaustion. The admission is regulated by a throttle-valve in the steam-pipe, before it enters the casing of the engine. The reversing of the engine is extremely simple: it is done by turning a screw, or by a lever, which pushes forward the D slide-valve, when it reverses the flow of the steam, which passes through the cylinder. The engine generally makes from 250 to 300 revolutions per minute, by which rapid motion the centrifugal force causes the rollers to press against the outer casing, and allows the steam to act upon the back of them, as before explained. To the engine of the above boat there are two air-pumps, 8 inches diameter and 11 inches stroke. The condenser forms a pedestal in the bottom of the boat, upon which the engine and pumps are placed. The boiler is as compact as the engine: it is cylindrical, 2 feet 6 inches diameter, and 7 feet high over all, and contains numerous tubes about one inch diameter, and an inch apart, through which the heat and smoke pass from the furnace to the chimney immediately over. The area of the grate is about 4 square feet, or half a foot per horse; the water occupies only a very small height of the boiler, the other portion forming a receptacle for the steam, which is usually generated to a pressure of from 40 to 50 lb. in the boiler. The consumption of coke is stated to be about 60 lbs. per hour, depending upon the speed. The air for the supply of the furnace is driven in by the aid of a fan. Motion is communicated to the paddle-wheel by a pinion-wheel on the outside of the shaft or axis of the engine, which drives a larger wheel upon the shaft of the paddle-wheels, in the proportion of 1 to 44; so that when the engine makes 270 revolutions per minute, the paddle-wheels make 60 revolutions. The total weight of the engine, condenser, air-pumps, paddlewheels, boiler, and water, is 24 tons. In a trial trip, this boat has performed 7 miles in 37 minutes, with the tide. The engine is very simple, compared with previous patents of the same kind, is very powerful in working, and must be very economic in construction, particularly when used as a non-condensing engine. Besides the engine on board the "Anti John Scott Russell," Mr. Beale has one of a similar size and description at his manufactory at East Greenwich, worked at the low pressure of 4 lbs. to 6 lbs.; it stands on the ground, and is hardly perceptible among the numerous machinery in the shop, although it drives the blast-fan of a foundry, and sets in motion numerous lathes, planing machinery, &c.-Civ. Eng. and Arch. Journ., No. 57; abd. The Atmospheric, built by Ditchburn and Mair, is entirely of iron in the hull, but with deck and fittings of timber, and is for river navigation. Her length between perpendiculars is 150 feet; breadth of beam, 18 feet; depth of hold, 9 feet 9 inches; draught of water, 4 feet 8 inches: her engines, 365-horse power, by Seaward and Capel, are upon the old atmospheric principle; they work most efficiently, and the boat is of unrivalled speed.

The Locomotive, No. 1, for running between the Adelphi Pier and Greenwich, is fitted by Braithwaite and Co., with a locomotive engine, the same as those working on railways, except that it is taken off its wheels, and set upon bearers laid across the bottom of the boat; and instead of the railway wheels, there are fixed upon each end of the driving or cranked axle, a pinion-wheel, 2 feet 4 inches diameter, which works into a cog-wheel 7 feet diameter, keyed on to the shaft of the paddle-wheels; the shaft being one piece, with a bearing in the centre on the top of the boiler. The engine is 10 tons, with two cylin

ders 12 inches diameter, and 18 inches stroke; the pistons making from 100 to 130 revolutions per minute. The length of the boat, of iron, is 103 feet on the water-line; beam, 11 feet 6 inches; drawing 2 feet 2 inches when light. The speed is equal to about 12 miles through the water; and the consumption of fuel is about the same as on railways. As the engine is fixed in the boat, instead of moving at such high velocities as it does on rails, there is nothing like the same wear or liability to derangement.-Civ. Eng. and Arch. Journ., No. 59.

Il Peloro is a compact steam-vessel, built by Pitcher, for the Neapolitan Government, for conveying the mails. Her dimensions are 130 feet in length between perpendiculars, 19 feet 6 inches in moulded breadth, and 20 feet 24 inches extreme breadth; burthen, 252 tons; pair of 50-horse engines by Bolton, Watt, and Co.; cylinders, 3 feet 3 inches diameter, and stroke 33 feet; paddle-wheels, 15 feet 6 inches diameter; average speed, 10 miles per hour, with a very small consumption of fuel. The indicator figures show a vacuum of 12 to 13 lbs., with a pressure of 3 lbs. of steam.-Civ. Eng. and Arch. Journ., No. 56.

Portable Steam Tug.-Captain Carpenter, of the Geyser, has had her pinnace fitted with his own patent propeller and a small engine of 5 or 6 horsepower from the Disc Company. The pinnace is 30 feet in length, 9 feet wide, and is capable of carrying 8 tons. The disc engine with which she is fitted weighs altogether but 6 cwt., and measures 3 feet by 1 foot 6; leaving ample space for a full complement of men. The connexion between the engine and the propellers is by means of grooved pulleys and catgut bands. The velocity of the engine-shaft was 200 revolutions a minute; and more than that is not, we understand, desired from the propelling shafts. The engine and boiler are so fitted to the pinnace, that they can be taken out in five minutes, and replaced ready for operations in the same brief space of time.

ATMOSPHERIC RAILWAY.

THE Report on this invention, of Sir F. Smith, R.E., and Prof. Barlow, has been presented to Parliament. The summary of their opinion is thus given: "1. That we consider the principle of Atmospheric propulsion to be established, and that the economy of working increases with the length and diameter of the tube. 2. That the expense of the formation of the line in cuttings, embankments, bridges, tunnels, and rails, will be very little less than for equal lengths of Railway to be worked by locomotive engines; but that the total cost of the work will be much greater, owing to the expense of providing and laying the atmospheric tube, and erecting the stationary engines. 3. That the expense of working a line on this principle, on which trains are frequently passing, will be less than working by locomotive engines, and that the saving thus effected will, in some cases, more than compensate for the additional outlay; but it will be the reverse on lines of unfrequent trains. However, there are many items of expense of which we have no knowledge and can form no opinion, such as the wear and tear of pistons, valves, &c.; on these further experience is wanted. 4. That with proper means of disengaging the trains from the piston in case of emergency, we consider this principle, as regards safety, equal to that appertaining to rope machinery. There appear, however, some practical difficulties in regard to junctions, crossings, sidings, and stoppages at road stations, which may make the system of less general application."

Mr. Brunel has become a convert to the merits of this Railway, so far, at least, as to recommend it to be the only practicable method of