ceed to give some particulars of the performances of those ships which have already adopted it.

Summary of the Performances of the "Archimedes."

(237 tons, 70-horse power.)

May 14, 1839.-Made the passage from Gravesend to Portsmouth in twenty-one hours, against a strong westerly breeze.

October, 1839.-Beat the Hon. East India Company's steamer Queen, of 220-horse power, upwards of three quarters of a mile in a run of eight miles.

April 18, 1840.-She was ordered to Dover for the purpose of trying her powers with her Majesty's packets at that station, on which occasion the fastest of them, the Widgeon, was beaten nine minutes between Dover and Calais, and five minutes on the return trip, which was done in one hour and fifty-three minutes-being the quickest passage ever made between England and France, by fourteen minutes. The Dover boats vary from 70 to 90 tons less, their engines from 5-horse to 10-horse power more, and the draught of water from four to five feet less than the Archimedes.

June 5.-Ran from Milford to Liverpool (200 miles) in nineteen and a half hours. Surpassed the swiftest boats on the Mersey; and on one occasion beat to windward up that crowded river with as much facility as an ordinary sailing ship. From Liverpool to the Isle of Man she beat the Mona's Isle packet (a vessel of superior power) nearly two hours-running the distance of seventy miles in seven hours and fifteen minutes.

August 1840.-She performed the passage from Plymouth to Oporto in sixty-eight and a half hours, and the homeward trip between those places in eighty-eight hours, with wind a-head nearly the whole distance.

November, 1841.-During her passage from Bristol to London, made headway at the rate of three and a half knots per hour against a tremendous sea, whilst other steamers of much larger power bore up, as shown by the pilot's certificate.

"Princess Royal."

(Steam-tug boat, on the screw principle, 45-horse power.) After beating the fastest of that class of boats on the Tyne, performed a passage from that river to Brighton in forty-eight and a half hours, a distance of nearly 400 miles. She has towed out of Shoreham Harbor, at one time, two large brigs, against the wind, and tide setting in, at the rate of four miles per hour; on another occasion, towed out a brig, which carried away both topmasts immediately the steamer had cast off. This little vessel, also, went to sea with comparative ease, whilst the Dart steamer, of 120-horse power, was more than half an hour before she could accomplish the same object, owing to the sea and tide running at the time.

"The Great Northern."-Extracts from her Log.

Sunday, Dec. 25, 1842.-Sh. 5m. Weighed anchor in Cowes Roads, and put the ship on her course for London, under steam and canvass.

9 50 a. m. Massey's log put overboard; revolution per minute of engine, 18; rate per common log, 10 knots; Massey's log, 10 do. 11 50 a. m. Stopped engines abreast of the Ower's light-ship, and disconnected the screw; ship put on her course up channel, with sails only. Noon. Fresh breezes and cloudy. 2 30 p. m. Abreast of Beachy Head; ship brought to her course. 5 5 p. m. Massey's log hauled in. (Note-The distance run from the Ower's light-ship, by chart, sixty-six nautical miles, in five hours and two minutes.) Hove to, and fired guns for a pilot. 5 50 p. m. Took pilot on board; wind increasing. 7 50 p. m. Anchored in the Downs in eight fathoms

water.

Monday, Dec. 26. -4 a. m. The wind blowing a gale, down royal and top-gallant yards. 8 50. Changed pilots. Noon. Gale increasing, and a great number of ships running for the Downs. Midnight. Weather about the same.

Tuesday, Dec. 27.-9 a. m. Gale suddenly moderated; steam raised to assist in getting the anchor. 11 40 a. m. Got under weigh, and proceeded through the Downs, setting fore and aft sail, wind being directly a-head. 5 17 p. m. Abreast of the Nore light. 9 p. m. Anchored nearly opposite the Chapman beacon.

Wednesday, Dec. 28.-7 a. m. Got under weigh, steaming only; wind a-head. 9 5 a. m. Stopped off Gravesend and changed pilots. 9 17 a. m. Started for London against ebb tide and light wind. 12 a. m. Abreast of Woolwich. 12 20 p. m. Arrived at Blackwall, and moored ship, having stopped six minutes in Longreach to adjust machinery, thus accomplishing the run from Gravesend to Blackwall (twenty-one miles) in two hours and fifty-seven minutes, the mean rate of the tide being taken at two miles per hour.

Since the Great Northern's arrival at Blackwall, considerable improvement has beer. effected in her engines, by Messrs. Miller and Ravenhill, which was satisfactorily shown in her trials on the 11th instant, in the presence of a large party of gentlemen connected with science and the shipping interests. We subjoin the following particulars of her dimensions

It will be seen from the above extracts from her log, that the Archimedes, though not built for extreme speed, but more to show the practicability of uniting sailing and steaming qualities in one vessel, has succeeded in beating many vessels of superior power, built expressly for steaming. Her utmost speed under steam alone was nine

and a quarter knots; with steam and sails combined, under the most favorable circumstances, it was upwards of eleven knots. This is particularly worthy of consideration, as showing the utility of a moderate steam-power on board sailing vessels in case of calms or contrary winds, while the expenditure of fuel need not be resorted to during favorable winds merely for the trifling gain above stated. Upon twenty out of thirty-two points of the compass a ship would be able to dispense with her steam power altogether.

The great superiority of the screw is most apparent in causing the ship immediately to answer her helm; the stream of water thrown astern by its action keeps the helm steadily amidships, and the slightest movement of the wheel is sufficient to govern her. In turning about, the effect of the screw is surprising; on the Archimedes putting the tiller hard over, she performs a complete circle in two and a half minutes, and two and three quarter minutes the second-the rudder acting as a drag on the stern, it takes longer time to make a second circle than the first, yet the space occupied is less, until the vessel seems to turn on a pivot-an entirely new manœuvre in navigation.

Lond. Mining Journ.

Historical notices of Screw Propelling.

(Ante) 1727. In the "Machines et Inventions approuvées par l' Academie Royal des Sciences depuis 1727, jusqu' an 1731," there is described a machine by one Duquet, for forcing a vessel up a river against the current by MEANS OF THE SCREW.

1768. In a French work by Paucton, on the "Theory of the Screw of Archimedes," the author proposes to substitute for the common oar an instrument which he calls a "pterophore," composed of the circumvolution of the thread of a screw round a cylinder.

1792. Baron Seguier states that some time before this date, there was to be seen at the Conservatoire des Arts et des Metiers of Paris, the plan of a steamboat which was to be propelled by a screw fixed in, or connected with, the rudder. Jobard's Bulletin, 1842.

1802. A propeller was successfully applied by John Shorter, to H. M. S. Doncaster, at Gibraltar, which Mr. Galloway, on the authority of Mr. Napier, states, was on the principle of the screw. Galloway's Appendix to Tredgold, p. 4.

1804. In "Memoire sur les Bateaux á Vapeur des Etats Unis d' Amerique," by Marestier, it is mentioned that a vessel had been propelled, or proposed to be propelled, by means of a "helicoidal surface," nearly as long as the vessel, enclosed in a channel running fore

and aft.

1816. Mr. Robertson Buchanan in his Treatise on Propelling Vessels by Steam, says, "Experiments have been made on a kind of screw, but this I believe, after a trial on a considerable scale in America, was rejected. Some mechanics, however, still think favorably of it, and suppose that if a screw of only one revolution were used, it

would be better than where a longer thread is employed." The American experiments here alluded to, are, no doubt, those spoken of by Marestier.

1818. About this time an English engineer, of the name of Brain, settled in Belgium, is said to have announced that he had discovered a new means of propelling vessels, namely, "by screwing them through the water." Jobard.

1819. October 1, a Mr. Whytock announced (Edin. Phil. Journal, vol. ii, p. 19,) that he had five or six years before made various experiments in propelling boats by means of two screws; the lines of which were obtained from the circumvolution of a thread round a cylinder. The screws would seem to have been applied one on each side of the boat; but Mr. Whytock's description is so worded as to leave this in some doubt.

Mr. Scott, of Ormiston, proposed to employ a screw working in a cylinder entirely immersed in the water. Thompson's Annals, vol. xi, p. 438.

1824. August 9; Mr. Jacob Perkins patented "certain improvements in propelling vessels," which consisted in fixing at the stern two sets of revolving oars, having their centre of rotation above the water, and entering it obliquely at the same time on opposite sides of the rudder, and after each revolution leaving the water at the sides opposite to the respective entrances.

1825. Mr. Samuel Brown applied to an experimental boat a propeller on the principle of the screw, consisting of two flat blades affixed to a longitudinal shaft at an angle of 45°, and placed in the bow of the boat.

1826. Nov. 18; Mr. Bennet Woodcroft, of Manchester, patented certain "improvements in wheels and paddles for propelling boats," the nature of which improvements is thus described by Mr. Woodcroft in his specification: "I declare that my said invention consists in a spiral paddle, made of wood, metal, or any other suitable material of the following construction, by the revolution of which boats, or other vessels may be propelled on water; that is to say, a spiral worm-blade, or screw, coiled round a shaft, or cylinder, of any convenient length and diameter, in such form that the angle of inclination, which the worm makes with the axis of the cylinder, continually decreases, and the pitch, or distance, between the coils, or revo-. lutions of the spiral, continually increases throughout the whole length of the shaft, or cylinder, upon which the spiral is formed, the effect of which construction is as follows: The spiral paddle being made to rotate in the water, when the commencement of the spiral blade, or that part of it which forms the greatest angle with the shaft, acts upon the water, it gives to it an impetus, or motion, towards the back end of the paddle, thus creating a current in the direction of the spiral. If this current were to reach the succeeding, or following, parts of the spiral paddle, before those parts take their action upon the water, such following parts would move in, or keep pace only with the current, and would, therefore, meet little or no resistance from the receding water, and a part, or whole, of their action would

be lost, or without effect; but by previously elongating the pitch of the spiral, each successive part of the spiral begins to act before it is overtaken by the current given to the water by the action of the preceding part of the spiral, and, consequently, every part meets resistance from the water, and thereby gains a proportion of propelling power."

1827. Tredgold, in his work on Steam Navigation, notices several of the preceding plans, and enters into a full investigation of the properties of the screw as a marine propeller.

1828. Dec. 10; Charles Cummerow, of London, merchant, patented "certain improvements in propelling vessels," which he stated were "communicated by a foreigner residing abroad." These improvements consisted in the application of a screw at the stern, placed in the dead-wood immediately before the keel.

1829, Nov. 20. American Letters Patent were granted to Benjamin M. Smith, for the application of "sculling wheels, or screw propelling wheels to boats."

1831, April 27. American Letters Patent were granted to Doctor Giraud, for "a screw, or spiral lever, for the propelling of vessels."

1836, May 31. Mr. F. Petit Smith patented "an improved propeller," consisting of "a sort of screw, or worm." According to the description given in the specification, and the accompanying drawings of this sort of screw," it differed in nothing from any other sort of screw; and so far, therefore, as the "propeller" was concerned, no improvement was shown. The drawing, however, represents the screw as being placed in a recess cut in the dead-wood immediately before the rudder; and on this peculiarity of position, though both Cummerow and Woodcroft had before proposed the same thing, has been founded a claim to novelty! At first, indeed, the patentee laid no stress whatever on this circumstance, for his original claim was in these words: "I claim, as my invention, the propeller herein-before described, whether arranged singly in an open space in the deadwood, or (in duplicate) one on each side of the same, or more forward, or more aft, higher up, or lower down, completely, or partially, immersed;" but afterwards (May 28, 1839,) he entered a Memorandum of Alteration, in which he represented the placing of the propeller in the dead-wood, as being the principal feature of his invention. "Since the enrolment of my specification," he says, "I find that the deadwood, or run of the vessel, is the only place in which the said propeller can be advantageously placed, and that a screw of one turn, or two half turns, as a propeller, will be sufficient for every purpose." And for this reason," and in order to limit his claim accordingly, he substitutes for the words which have been just quoted, the following: "I claim as my invention the propeller described in figs. 1, 2, 3, of the drawing annexed to this memorandum of alteration, and placed singly in the centre of the dead-wood, or run of the vessel, as shown in the figures of the drawing annexed to the original specification." As represented in the drawing annexed to the original specification, the screw is of a single thread; but in the drawings which accompany the Memorandum of Alteration, it is shown as be