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THE PADDLE-WHEEL AND SCREW-FURTHER EXPERIMENTS WITH HER H.M.S.

[Extracts of letters from an Officer at the Royal Naval College, Portsmouth.]

We have had a capital experiment to-day (6th Oct.) with Bee, Paddle versus Screw. I must tell you, however, that the screw sent from Woolwich yard for Bee, instead of being a left-handed one, was a righthanded one, and luckily it was so (not for screw advocates) for it enabled us to make a very pretty experiment, which was the following, I should have told you, first of all, that the Bee being fitted with paddle and screw, it is requisite to have a screw that goes the opposite way to the paddles. When I say opposite way, I mean one shaft to revolve with the sun, and the other against it; this arises from the mode of application. The experiment was this,—the paddle and screw were thrown into gear at one time, the paddles going the head way, and of course, the screw the back way. The paddles walked off with the screw in good style. An objection was started, that the screw was working in the broken water of the paddles. They then reversed the engine, going the back way with wheels, head way with screw. The result was the same,— paddles again walking off with the screw. Look at this, sir,-a more beautiful experiment never could be; here you had the same steam, revolutions, &c.; in fact, nothing could be better,-the circumstances perfectly the same in all respects. Not as when Rattler took Alecto in tow; the odds were against Alecto, her revolutions being about 9 per minute, Rattler 22 or 23, (about that); more steam-more power. After the above experiment, they hooked Bee on to dynamometer, paddles and screw working one against the other.

The pad

dles overcame the efforts of the screw by 317 16 lbs. Now, let me tell you, sir, that the direct pull of Bee by dynamometer with paddles alone, is 627 lbs., screw 583 lbs. Look here at the proportion that 317.16 lbs. bears to this. Is it not evident that we

might work " expansively" with paddle

and beat the screw?

It was a pretty sight to see the struggle for the championship. We tried also to-day, the screw with fuel, &c., &c., with steam maintained at 5 lbs. to ensure more blowing off having done the same with paddles. The fuel consumed in 2 hours was 205 lbs.; revolutions 26 per minute; pressure by dynamometer, 48 lb. x 11: 528 lbs. With paddles under the same circumstances precisely, but pressure 53 × 11 = 583 lbs., and revolutions per minute, 16; the fuel consumed was 140 lbs. in the same time, viz., 2 hours.

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66 BEE.

It may be said the Bee is not a good specimen of a screw boat; neither is she a paddle boat, for the slip of wheel is too great; it is a large wheel, over a short crank: that is, the paddle arm should be less, with a broader paddle float, so that the slip might be reduced.

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When the pressure of 317 lbs. was obtained by the paddle over the screw, the speed of the engine was only 14 revolutions per minute, but when the pressure of 583 lbs. was given off, the revolutions of engine were 28; this is double, you will perceive; but when working both together, the screw, of course, could only revolve with the paddle, that is, it had its multiple 4 to 1, the screw itself making 56 revolutions, and when the paddles were dismounted the revolutions were 112 per minute. This at once proves that the effect of the screw depended on its great number of revolutions. Let me not be understood to say, that the greater the number of revolutions the greater the speed; there is a limit, of course, for you may so spin the screw round that the fulcrum will be destroyed, or in other words, it will be working in a void. It may here be asked, perhaps, "What is to become of expansive force? Will you get the same proportion of speed with half steam as you do with paddle?" I say most emphatically, no; you must screw away, and so will your coals from the coal-boxes. In fact, in a screw vessel, it will be nonsense to talk about screwing out the coals. Very unfortunately, the shaft for driving the screw broke just as they were about to try the screw at the different steps of expansion, and it will be now some time before they can get a new one; so the experiments must stand over.

They have tried the paddles, having a long hawser the same length as they had for the screw; pressure by dynamometer, 704 lbs. ; revolutions per minute, 16; steam in boiler, 7lbs. ; barometer, 273. If ever the screw in any form achieves as much with the same quantity of steam, I shall be much surprised.

P.S.-The screw people about here are looking very blank since the trials with Bee, and, as a matter of course, do not think the experiments worth much! What would they have said if it had come out the other way? Why, it would have been a most beautiful experiment-under the same circumstance, same horse power, &c,, &c.

ELECTRIC LIGHT.

NOTES AND NOTICES.

Sir, I would be glad to describe the best mode of producing the continuous electric light, but I am unable to do so.

Mr. Weeks, of London, I believe, succeeded pretty well, about ten years ago. I understand that a very successful apparatus has been got up at Cincinnati, in America. And it was last year, or the year before, that an intense light, of a blueish tinge was procured in Paris, by galvanism acting on certain media.

Last year, in the Builder, and Literary Gazette, severally, two different forms of apparatus, one in which platinum cylinders, the other charcoal cylinders, were resorted to, were described, for the production of the electric light. I caused one of the descriptions, that describing the platinum cylinder, to be transcribed, and put it into the hands of an ingenious scientific friend for the purpose of arranging the best means of getting up the light, and determining the cost, which promised to be about 201. The experiment was given up on the score of expense, and the paper was mislaid.

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The following paragraph, the last I have seen on the subject, I copy from one of the periodicals of the day.

"At

a late meeting of the Paris Academy, a letter was read from M. de la Rive, on the possibility of rendering the electric light available for the use of workmen in mines. This gentleman states that five or six elements of a pile of copper, and an amalgam of potassium sufficed to render incandescent two cones of charcoal inclosed in a small glass globe."

It is very strange that so important a subject receives so little attention in this country. That the electric light is practicable, I have no manner of doubt. I doubt not, also, that its adoption in mines would be the means of saving very many lives. The electric light, if brought to comparative perfection, would be also adapted for lighting tunnels, streets, and probably private house, for which its beauty and cleanliness strongly recommend it. There are endless stores of this wonderful element (electricity) in earth and air, if we would only, as I am convinced we one day shall, fully avail ourselves of it. I am, sir, your obedient servant,

Belfast, Oct. 11.

H. M'CORMAC, M.D.

NOTES AND NOTICES.

271

Walking on the Water.-From Hanover, we hear of a practical discovery, of a kind so curious as to require some further explanation before we can quite understand it; and we are rather suspicious, inasmuch as we have, or fancy we have, some recollection of a somewhat similar story making the round of the continental papers several years ago. It is given, however, in this instance, with an imposing detail and the guarantee of names-if there be no borrowing of these for the occasion. The report is, that two young men, one a Swede and the other a Norman,-taking the hint from that sort of footgear of fir-planks called skies, by means of which, in those northern countries, the inhabitants pass through valleys and ravines filled with snow, without sinking-have been exhibiting, in that capital, the exploit of walking on the water by means of skies-made, however, for the latter purpose, with iron plates hollow within. Backwards and forwards, much at their ease, according to the report, did the exhibitors walk and run-going through the military exercise with knapsacks at their backs-and finally drawing a boat containing eight persons-all without wetting their shoes. The Minister at War has, it is said, put a portion of the garrison of Hanover under the training of these gentlemen, for the purpose of learning what might prove so useful a military manœuvre; and as MM. Kjellberg and Balcken propose carrying their invention into other countries, our readers will probably suspend their opinion till they have a nearer view of this novel meeting of sky and water.-Athenæum.

Flour and Potato Bread.-The attention of the French Academy of Sciences has been recently drawn to a new sort of bread made by a M. Clerget from wheaten and potato flour. The potato flour of M. Clerget, contains, not merely the farina, but also the fibre of the vegetable with its bran; it is free from unpleasant taste; it will keep for several years where the best wheaten flour would decay or deteriorate; and made into bread or biscuit, it is light of digestion and nutritious; mixed in the proportion of one part of potato flour to one part of wheaten flour, the bread is better than if made from the flour of wheat exclusively, and is about 30 per cent. cheaper.

Improved Locomotive.-It is gratifying to find that engineering skill continues to be applied, successfully, in the improvement of the locomotive engine. A new engine, called the Condor, has lately been constructed for the Liverpool and Manchester RailwayCompany, by their superintendant engineer, Mr. Durance. The improvements consist in having a double firebox, the combustible gases being consumed in the second, which would otherwise escape in an unconsumed state. By this means a considerable increase of heating power is obtained, and consequently, an increased speed. The most important feature of the new engine, however, is, that in addition to increased power and speed, the fuel used is coal instead of coke, and a considerable saving in expense is thereby obtained. This is, perhaps, the greatest improvement, as regards the economy of railways in Ireland that could have been suggested. Coke, the fuel used in England, must ever be a costly fuel in Ireland, particularly in the interior, inasmuch as the description of coal from which it is produced is not imported into this country; whereas ordinary coal, of good quality, is to be had on reasonable terms in all our seaports. The Condor now plying on the Manchester line, draws a greater number of wagons, at a higher velocity and at less expense, than any other engine.-Irish Railway Gazette.

The Avon steam-vessel, Commander Denham, is now nearly ready for sea, and being under orders to leave Woolwich on the 18th inst. for the Bight of Benin, considerable anxiety has been shown to in

spect a vessel fitted for an African station. The Avon is fitted with Captain Smith's paddle-box boats, and on the sides of the paddle-boxes, numerous cabins have been constructed for sleeping on deck. A platform has been constructed nearly 10 feet above the deck, joining the two paddle-boxes to each other, and of the dimensions of 21 feet by 20 feet. The platform is immediately over the engine room, and by the protection it affords to the engines, to preserve them from wet, the use of glass windows has been obviated, and wire gratings, about 2 inches and a half square, have been substituted, giving ample room for the circulation of air at all times, In the centre of the platform a window has been made, to add to the light of the deck underneath, and the whole has been joined, at Commander Denham's request, with marine glue. Commander Denham has also suggested that the cabin windows, and, indeed, every place for sleeping, should be supplied with extra frames, fitted with wire gauze, which permits the egress of the heated air of the rooms, while it checks the effects of the rays of the sun when the windows are open; and Mr. Lang, master shipwright, and Mr. Read, assistant to the master shipwright, have expressed their opinion that the application of the wire gauze, as recommended by Commander Denham, is one of the best plans of ventilation and protectors from extreme heat in tropical climates that could have been adopted. The Avon has been fitted with an invention by Churcher, for guiding the chain attached to the wheel when directing the helm; it appears to be very simple in its operation, prevents the chain getting foul, and is the first of the kind introduced into Her Majesty's service.

Alleghany Suspension Bridge.-This bridge is the work of a mechanic of Alleghany city. The suspension ropes which extend from pier to pier, in the form of an inverted arch, are to consist of seven strands of wire, each strand being about three inches in diameter. Four of these strands are already finished across the entire length of the structure, and the fifth will be completed to-day. The ropes will then be wrapped in annealed wire, (No. 14,) which will reader it one solid mass; and as each individual wire is varnished before it is put across, and as the whole will be painted when finished and wrapped, it will be impervious to water, and consequently not liable to be weakened or impaired by the weather. On these two immense wire ropes the structure is to be suspended. But this is is not the only reliance for strength. The trunk is to be constructed from pier to pier; the sides being of solid lattice-work; that is, strong beams placed in this form-XXX. The beams are to be placed contiguous to each other for greater strength, so that when finished the trunk alone, without the wire-ropes, will be a firm and strong structure, capable not only of sustaining its own weight, but also of bearing up as much additional work as a lattice-work bridge would do. In effect, the trunk is a lattice-work bridge without arches. The ropes, being suspended across strong stone towers placed upon the piers, are, in fact, inverted arches, capable of sustaining more than double the additional weight which the letting-in of the water would place upon the trunk; the trunk itself is an independent, strong, and immovable structure, so that when finished, the aqueduct will not be liable to be moved either from the swell of water or the effect of storms. The wires are carried across the river, from one pier to another, by a wheel which traverses the whole distance upon ropes, unbinding the wire from the reel as it goes. The ropes are moved by horse-power. The splices of the wire are made by placing the two ends together and winding them with fine annealed wire; and it is done so strongly that sufficient force will break the

wire, but will not affect the splice. - Pittsburgh Chronicle.

Machine for taking Soundings.-A very ingenious contrivance for taking soundings at sea has lately been discovered by a Mr. Richard Wing. It is the application of electro-magnetism to this purpose. The instrument must be seen to be fairly appreciated. It is not cumbrous or expensive, being made of wooden bars about two feet long, in which the apparatus is placed. It is to be used in conjunction with a sustaining galvanic battery and an electro magnetic bell. There are conducting wires, &c. The instrument is to be suspended by a strong line over the side of the vessel at any required depth, say 30 fathoms. The moment the instrument touches the bottom sufficiently to cause it to incline to an angle of about 22 degrees, indication is given by the ringing of a bell in any part of the ship most eligible for placing it. The great difficulty of ascertaining depths by the sounding lead in great depths of water and in strong currents would, it is asserted, be remedied by this invention, for the moment the machine from being perpendicular in the water fell horizontally, indication would be given.-Times.

Day and Night.-Nothing made so deep an impression upon our senses as the change from alternate day and night, to which we have been habituated from our infancy, to the continued daylight to which we were subjected as soon as we crossed the Arctic Circle. The novelty, it must be admitted, was very agreeable; and the advantage of constant daylight, in an unexplored and naturally boisterous sea, was too great to allow us even to wish for a return of the alternations above alluded to; but the reluctance we felt to quit the deck when the sun was shining bright upon our sails, and to retire to our cabins to sleep, often deprived us of many hours of necessary rest; and when we returned to the deck to keep our night watch, if it may be so called, and still found the sun gilding the sky, it seemed as though the day would never finish. What, therefore, at first promised to be so gratifying, soon threatened to become extremely irksome, and would, indeed, have been a serious inconvenience, had we not followed the example of the feathery tribe, which we daily observed winging their way to roost, with a clock-work regularity, and retired to our cabin at the proper hour, where shutting out the rays of the sun, we obtained that repose which the exercise of our duties required. At first sight it will no doubt appear to many persons that constant daylight must be a valuable acquisition in every country; but a little reflection will, I think, be sufficient to show that the reverse is really the case, and to satisfy a thinking mind that we cannot overrate the blessing we derive from the wholesome alternation of labour and rest, which is in a manner forced upon us by the succession of day and night. It is impossible, by removing to a high latitude, to witness the difficulty there is in the regulation of time-the proneness that is felt by the indefatigable and zealous to rivet themselves to their occupations, and by the indolent and procrastinating to postpone their duties, without being truly thankful for that allwise and merciful provision with which Nature has endowed the more habitable portions of the globe. -Beecher's Voyage of Discovery towards the North Pole.

INTENDING PATENTEES may be supplied gratis with Instructions, by application (post-paid) to Messrs. Robertson and Co. 166, Fleet-street, by whom is kept the only COMPLETE REGISTRY OF PATENTS.

LONDON: Printed and Published by James Bounsall, at the Mechanics' Magazine Office,
No. 166, Fleet-street.-Sold by A. and W. Galignani, Rue Vivienne, Paris;
Machin and Co., Dublin; and W. C. Campbell and Co., Hamburgh,

4

Mechanics' Magazine,

MUSEUM, REGISTER, JOURNAL, AND GAZETTE.

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GORDON'S PATENT FUMIFIC IMPELLER.

[Patent dated March 3; Specification enrolled, September 3, 1845.]

THE inventor of this impeller is Mr. Alex. Gordon, the author of the wellknown"Treatise on Elemental Locomotion." The present invention is stated to have been the result of a successful "course of experiments upon the action of the hot products of combustion when brought by rapid delivery into immediate contact with water;" and the general considerations which led Mr. Gordon to institute these experiments are fully explained in a pamphlet which he has just published.* We select from this pamphlet a few of its most striking pas

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In the steam-engine, water exists in every stage of its history or operation. The heat from the fire separates the ultimate molecules of the water, overcoming their mutual attraction, and endowing each of them with a force of repulsion in proportion to the amount of heat. Heat, then, is the source of that power.

All solids, liquids, and aëriform bodies, may be heated and cooled, expanded and contracted; very few of them, however, can be applied as an elemental power, and still fewer of them can be employed as a power for locomotion or navigation. Some of the solids are used where power without speed is required, as in the case of iron bolts, rivets, ties, wedges. Some liquids, as for instance, spirits of wine, ether, ammoniacal liquor, liquid carbonic acid, have been proposed and experimented upon, with the view of being employed as means for an available motive power, by the alternate application and abstraction of heat; but water has hitherto been found the most convenient and economical means for obtaining power from the chemical action of heat; and to this is due the general adoption of the steam-engine.

Many attempts have been made to employ air as the means for obtaining power from the chemical action of heat. Some inventors have followed the manner in which water is treated in the steam-engine-by keeping the air altogether distinct from the fire, and transmitting the heat of the furnace through the materials of a tight chamber (like a boiler). Of these the most successful have been the productions of Mr. Erics

* Description of the Fumific Impeller; showing the direct Application of the Hot Production of Combustion to the Bodies on which they are required to Act without the Intervention of Machinery. By Alexander Gordon, M.I.C.E. Dalton, 1845.

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son and Mr. Stirling.* Others have used the products of combustion by bringing them (without the intervention of any heating chambers like a boiler) at once to act in the piston-cylinder. This latter process was introduced in Sweden,† and more recently has been carried into experimental operation by Sir George Cayley under a patent.

But, prior to either the Swedish engine or that of Sir George Cayley, Mr. Robert Stein, of Edinburgh, had, in August, 1821, obtained a patent for improvements in steamengines, and his improvements consisted principally in directing the actual products of combustion in combination with the steam, at once into the piston cylinder. Sometimes Mr. Stein dispensed with a boiler and water, and used only the products of combustion from the close furnace.

All of these, and all other inventors of hot-air engines, have taken the steam-engine piston and cylinder as their models; and, although several of them proved clearly that air is more economically heated to the required temperature than water, and, although Sir George Cayley proved this economy of fuel in an extensive practice, and Mr. Stirling has shown the economy to be immense, no one has yet contrived how to maintain the durability, and, by consequence, the current economy of a hot air or caloric engine, when a piston and cylinder are operated upon at once by the products of combustion. And of Mr. Stirling's engine it may be said, it bids fair to rival the steamengine for manufacturing purposes, such as the impulsion of mill-machinery.

It is not necessary to enter into a tedious narrative of the hot-air or caloric engines just referred to, nor to enumerate the various attempts to make hot aëriform bodies actuate a piston in a cylinder.

It may be asserted that hot aëriform bodies have not been successfully employed hitherto as the agents, because the great sensible heat has speedily destroyed some part of the machine; and because water has been preferred as the material, on account

A full description of this elegant engine, with illustrative drawings, was presented to the Institution of Civil Engineers by Mr. Stirling, of Dundee, and a long discussion, on its construction, action, and economy, took place, to which I beg to refer. It will be seen that great difficulty was experienced by members in understanding the action of Mr. Stirling's air-engine. It appears to have been difficult of comprehension, principally because the steamengine is naturally taken by engineers as the standard of perfection.

+ See description by Mr. Ericsson, in a paper existing in the Institution of Civil Engineers.

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