mentioned articles but little, if any, doubt exists in the minds of our most eminent chemists. The difference in the cost of a seventy-four gun ship between iron and copper would be as 810l. to 64801. The saving in her Majesty's Navy and in the mercantile marine of this country would consequently be enormous.

Under the second process, zinc paint would be employed wherever the bulk of the article to be protected or the difficulty of displacing it would render an immersion of the iron into the heated metal impracticable. Bridges, therefore, already constructed, boats already built, in short all articles already fixed may be preserved from further decay by the use of the patent paint. This paint will not be dearer than white lead.

By means of the third process, the finer sorts of iron and steel will be preserved. All articles of hardware and cutlery are subject to the most serious deterioration by exposure to moisture; but by applying to them the galvanic powder, or wrapping them in paper prepared with it, they may be exposed with safety to any weather, or exported with security to any climate.

It remains only to repeat that the processes are not expensive. However numerous and important are the admitted advantages of these discoveries, they would be less striking were they to be obtained only at a high price. The process of coating with the metal in a liquid state is cheaper than tinning. Tin is worth 98s. per cwt., zinc 20s. per cwt. Supposing that galvanized sheet iron should be sold at the price of tin-plate, the profit would be at least 100 per cent.

GAS COKE AS A FUEL FOR MELTING IRON. (From the Franklin Journal for Dec. 1837.) The following communication possesses much interest for all concerned in the manufacture or use of iron casting. In the preparation of this material, time is emphatically money, and the experiments at the Franklin Works show that a saving may be effected of one-half the time usually required in melting.

Franklin Works, Philadelphia, January 1, 1838. Dear Sir,-At the suggestion of Mr. Cresson, Superintendant of the Gas Works, we made, some weeks since, a few trials of gas coke as a fuel for melting iron. They were not made with reference to exact results because having never heard of gas coke being used in England for this purpose, we doubted the success of the experiments.

A few days, however, convinced us that the coke presented advantages over the anthracite which would render it an important

fuel for iron founders, and we determined upon making some exact comparative experiments upon the use of the two fuels. The results of which we deem it proper to send you, with liberty to make such use of them as the Board may deem expedient.

Our cupola is thirty inches in diameter. The blast is urged into it by a fan with four wings having an aggregate area of 384 inches of fan surface moving 1800 revolutions per minute through three tuyeres, two of them 4 inches in diameter, and one of 5 inches; the aggregate area being fifty-one inches and a half.

The trial was made in two heats with each kind of fuel, and the results given are the aggregate of both heats respectively.

1st. Anthracite Coal, white ash of very excellent quality,

Time of blowing 1st heat 3 hours 15' 2nd .. 3

30

Aggregate 3 12' or 192 min. Metal melted 14.342 lbs. or 4450 lbs. each h. Cokeused 3.056 lbs. or 470 lbs. to ton of iron.

The weight of fuel used to each ton of iron melted, was in both cases precisely the same, but the quantity melted in the same time was nearly double. The importance of time in a shop where many hands are employed, can readily be appreciated, and would of itself be a sufficient inducement to ensure it a preference even at an advanced

cost.

The capacity of a cupola for large castings is increased in proportion to the increased rapidity of melting-while with the anthracite our operations were confined to castings weighing not more than from 30 to 3500; we should have no hesitation of undertaking a piece of work weighing from three to four tons from our cupola using coke as fuel, MERRICK & AGNEW, Iron Founders, Southwark.

Dr. R. M. Huston,
President, Philadelphia Gas Works.

SPECULATIONS RESPECTING ELECTRO-MAGNETIC PROPELLING MACHINERY. (From the Franklin Journal for Jan.) In our number for November last, (Mech. Mag. vol. xxviii, p. 322) we published the specification of Mr. Davenport's patent for a machine intended to furnish a motive

power by the agency of electro-magnetism, to which we appended some remarks upon the subject generally. We had hoped, ere now to have received more definitive information than has transpired, respecting the progress of the experiments which are being made in New York with a view to its testing the utility by applying it to drive a Napier Press, requiring a two horse power; we have hitherto learnt nothing of the result of this proposed experiment; and suppose, therefore, that the trial has not yet

been made.

Since publishing the article above alluded to, it has appeared to us that should a much less power be attained by such a machine than that which is now sought for, say the power of a man only, it would still be equally valuable with the steam-engine, and would produce a great, if not a greater change, in the economy of the useful arts, as has been produced by that instrument; this, however, is under the proviso that the cost of materials consumed in performing the work of a day should be less than that giving for the labour of a man. Who is there that would not under such circumstances, need such a machine? If we hire a man by the day we must not allow him to be idle, as in that case we give our money for nothing. The current of his life flows on, and he must be fed and clothed or the stream will stop. But give us a machine which is not costly at first, and which if it works but one hour in the twenty-four, will itself be a consumer in that proportion only; a machine which we can at any moment set to turn our lathes, our grindstones, our washing machines, our churns, our circular saws, and a catalogue of other things which it would be no easy task to make out; such a machine would also perform a million of other operations by the conversion of the rotary into a reciprocating motion; and we again ask who is there among us who would not want one? our farmers, our mechanics, and our housekeepers generally, must all be supplied. We could no more submit to live without it, after it had once been introduced, than we can now submit to travel at the slow rate of ten miles an hour, an event which we have learnt to think one of the miseries of human life.

With such a machine at our command we should soon wonder how we could have lived so long without it; and if taken from us it would leave a most awful chasm in the necessaries of life, of the existence of which our fathers never dreamed, and which happily we could not be called upon to witness so long as the store house of nature would enable us to obtain zinc and sulphuric acid at a cheap rate.

The steam engine cannot be used to ad vantage where it has not the labour of several horses to perform, as, whether large or small, it requires the constant attention of the engineer, or of the fireman, and is kept at work at an expense which is relatively increased as its power is diminished. One giving the power of a man only would be employed, at a cost which would pay the hire of two or three men, and if used but for an hour or two in the day, the expense would be incalculably increased; of course it is not, and never will be used under such circumstances.

Let it not be said that we are prophesying about what is to happen; not so by any means; but be it remembered that we are speaking of what is a possible contingency. We have no doubt respecting the practicability of obtaining the power of a man by the agency of electro-magnetism; we believe that such a machine may be kept at work without any considerable tax upon the time of the person using it; and we further believe that the only thing which can prevent its coming into use is, the cost of the materials employed in operating it; the statements which we have heard upon this point are extremely contradictory, and upon the whole, are far from encouraging; the time, however, is not remote when this point will be determined.

LIST OF ENGLISH PATENTS GRANTED BE TWEEN 26th OF APRIL AND THE 24th OF MAY, 1838.

John Paterson Reid, power loom manufacturer, Glasgow, and Thomas Johnson, mechanic, of the same place, for certain improvements in preparing yarn or thread by machinery, suitable for warps, in preparation for weaving in looms. April 28; six months to specify.

Joseph Jepson Oddy Taylor, of Gracechurchstreet, machinist, for an improved mode of propelling ships and other vessels on water. May 1; six months.

Miles Berry, of Chancery Lane, for a new and improved method, or process of alloying metals by cementation, particularly applicable to the preservation of copper, wrought or cast iron, and metals, and thereby operating a change in the appearance of their surface, and giving them more brilliancy, being a communication from a foreigner residing abroad. May 3, six months,

John Ball, of Finsbury Circus, merchant, for improvements in carriages, being a commnnication from a foreigner residing abroad. May 3; six : months.

Edward Cobbold, M.A., of Long Melford, Somerset, for certain improvements in the manufacture of gas for affording light and heat, and in the application of certain products thereof to useful purposes. May 5; six months.

Edmund Shaw, of Fenchurch-street, stationer, for improvements in the manufacture of paper and paper boards, being a communication from a fo reigner residing abroad. May 5; six months,

Thomas Joyce, of Camberwell New Road, gardener, for certain improved modes of applying prepared fuel, to the purposes of generating steam and evaporating fluids. May 5; six months.

Pierre Armand Lecomte de Fontainemoreau, of Charles-street, City Road, for an improved method of preventing the oxydation of metals, being a communication from a foreigner residing abroad. May 5; six months.

William Gossage, of Stoke Prior, Worcester, manufacturing chemist, for certain improvements in manufacturing sulphuric acid. May 8; six months.

William Henry James, late of Birmingham, and now of London, Civil Engineer, for certain improvements in machines or apparatus for weighing substances or fluids, and for certain additions thereto, applicable to other purposes. May 8; six months.

William Crofts, of Radford, machine maker, for improvements in the manufacture of lace. May 10; six months.

Miles Berry, of Chancery Lane, for a new or improved method of applying certain textile and exotic plants, as substitutes in various cases for flax, hemp, cotton, and silk, being a communication from a foreigner residing abroad. May 14; six months.

Jean Francois Isidore Caplin, of Portland-street, artist, for improvements in stays or corsets, and other parts of the dress, where lacing is employed, and in instruments for measuring for corsets or stays, and for the bodies of dresses. May 14; six months.

Alexandre Happey, of Basing-lane, London, gent., for a new and improved method of extracting tar and bitumen from all matters which contain those substances, or either of them, being a communication from a foreigner residing abroad. May 14; six months.

Thomas Mellodew, of Wallshaw Cottage, near Oldham, Lancaster, mechanic, for certain improvements in looms for weaving various kinds of cloth. May 15; six months.

James Vincent Desgrand, of Size-lane, London, merchant, for a certain new pulpy product, or material, to be used in manufacturing paper and paste board, prepared from certain substances not hitherto used for such purposes, being a communication from a foreigner residing abroad. May 15; six months.

Francis Thorpe, of Knaresborough, in the county of York, flax spinner, for certain improvements in machinery or apparatus for heckling, preparing, or dressing hemp, flax, and other such like fibrous materials. May 15; six months.

David Stead, of Great Winchester-street, London, merchant, for an invention for making or pa ving public streets and highways, and public and private roads, courts and bridges, with timber or wooden blocks, being a communication from a foreigner residing abroad. May 19; four months.

Samuel Seaward, of the Canal Iron Works, Poplar, for certain improvements in steam engines. May 21; six months.

Augustus Applegath, of Crayford, calico printer, for improvements in apparatus for block-printing. May 22; six months.

Henry Adcock, of Liverpool, for improvements in raising water from mines and other deep places, or

from a lower level to a higher, which improvements are applicable to raising liquids generally, and to other purposes. May 22; six months.

John Ratcliff, of Birmingham, lamp manufacturer, for improvements in Lamps. May 22; six months.

Robert Martineau, of Birmingham, and Brook Smith of the same place, both in the county of Warwick,, cock founders, for improvements in cocks for drawing off liquids. May 24; six months.

John Radcliffe, of Stockport, Chester, machine agent, for a new method of removing the fly droppings, waste and other matters, which, being separated from the material falls below the cylinders and beaters, in the respective processes of carding, willowing, devilling, batting, blowing, scutching, opening, or mixing of cotton-wool, silk, flax, wool, or any other fibrous material or substances. May 24; six months.

Charles Searle, of Fitzroy-street, London, for a new description of aerated water, or waters, and which method of aerating is applicable also to other fluids. May 24; six months.

LIST OF IRISH PATENTS GRANTED IN
APRIL, 1838.

John Clarke the younger, of Mile-end, Glasgow, cotton-spinner, for improved machinery for turning, some part or parts of which may be made applicable to other useful purposes.

Sir James Caleb Anderson, bart., of Buttevant Castle, Cork, for improvements in locomotive and stationary engines, and in the mode of applying the same to tillage of land.

Luke Barton, of Arnold, Nottingham, for certain improvements in machinery for frame-work knitting.

William Fothergill Cooke, of Breeds-place, Hastings, Sussex, and Charles Wheatstone, of Conduit-street, Hanover-square, for improvement in giving signals and sounding alarms at distant places by means of electric currents, transmitted through metallic circuits.

Richard Tappin Claridge, of Regent-street, Middlesex, gen., for a mastic cement or composition applicable to paving and road-making, covering buildings, and the various purposes in which cement, mastic, lead, zinc, or composition is employed.

NOTES AND NOTICES.

Useful Discoveries.-The Brussels journals mention that Dr. Bernhardt has discovered processes, by means of which he is enabled to form out of the refuse of fish, a pure and limpid oil without any odour, soap of superior quality, fish glue, Prussian blue, and bone black, in quantities sufficient to produce a profit of 400 per cent.; and has founded a factory on an extensive scale for carrying his processes into effect.-Mining Journal.

Complete Sets of the Mechanics' Magazine may now be had, twenty-seven volumes, half-cloth, price 11 7s.

UP OF

ACCOUNT OF THE BLOWING
THE WRECK OF THE BRIG WIL-
LIAM" OFF GRAVESEND, AND OF
THE APPARATUS EMPLOYED, BY
COL. PASLEY.

The navigation of the Thames, it has been generally asserted, has, for a considerable time, been impeded by the wreck of a collier brig of 400 tons burthen, the William of Sunderland, which was run down by a steamer at Gravesend, near Tilbury Fort, in the winter of 1836. That this wreck, however, was ever found to be an actual impediment is very questionable, as at the lowest neap tide, she was covered with 23 feet of water, and lay in a spot where the sweep of the current would effectually prevent the formation of any sand bank. Various plans have been tried to raise the vessel, but owing to the weight of the cargo with which it was loaded -300 tons of coals-as well as other circumstances, all failed. Amongst other methods which were tried, was that invented and patented by Mr. Kemp, and described in our 763rd Number, and which it was expected would succeed, but the cylinders and apparatus were broken away by a vessel coming in collision with them. An attempt was also made to weigh the wreck by means of mooring chains and lighters furnished by the Admiralty, but unsuccessfully, owing entirely to the scanty material afforded by the Government. Instead of two lighters, and a few hands, there ought to have been one lighter on each bow, and one lighter on each quarter, each furnished with not fewer than thirty hands. Had these necessary means been supplied, that highly talented officer Mr. Purdo, of the Dock Yard, Chatham,would long ere this, have recovered the vessel from her bed.

Un

der these circumstances, it was at last deemed advisable to destroy the wreck by blowing it up with gunpowder. The superintendence of this difficult and novel operation was intrusted to Colonel Pasley. The means and apparatus employed by this gentleman we shall now proceed to lay before our readers.

The wreck was proposed to be blown up by the explosion of two large leaden cylinders of gunpowder, protected by outer casings of wood, and each charged with 2500lbs. of gunpowder, to be placed

against the sides of the brig. These cylinders were constructed by the Royal Sappers and Miners at Chatham. After being filled with the powder, the two holes by which it was poured in were covered with pieces of tin, which were soldered to a flange from a leaden case inside, with red-hot iron, in a perfectly safe, and therefore, we need scarcely add, ingenious, manner.

The engraving on our front page, will give a better idea of the operation than can be conveyed by words alone. A is the exploding cylinder, ready to be lowered to the wreck, to which it is to be rove by tackle, passed through ring bolts fixed in the side of the brig by the diver; B, the air tube to supply the divingbell K, containing men to assist the diver; C sappers, lowering the diving bell; D a small lighter to attend the diver; E the tube to supply the diver with air; F a ladder formed of rope, with wooden staves, by which the diver ascends and descends; G H the wreck of the brig; I the diver, a sapper, shown attaching the ring bolts to the hull of the brig, to secure the exploding cylinders in their proper places. This diver is equipped with Dean's diving helmet, and an India rubber dress; M the life-line, fastened round the body of the diver to haul him up in case of accident to the apparatus. The principal object in the operation is the cylinder, of which the following is a detailed description: Fig. 2 is an elevation of the cylinder. The wooden casing was made of elm, 3 inches in thickness, 10 feet in length, and 4 feet in diameter; it was bound with iron hoops 3 inches wide and gths of an inch thick, and strengthened and protected by longitudinal bars, and framed ends, as shown in fig. 2 and 4. Figure 3 is a section of the cylinder, showing the fuse. Fig. 4 an end view of cylinder. Fig. 5 the cylinder shown placed against the side of the wreck, completely prepared and ready to explode. The central hoops of the cylinder were cut nearly through on the side next the hull (see fig. 2), in order that by making this the side of least resistance, the vessel might be subject to the greater force from the powder. The cylinder was to be exploded by means of a fine powder hose in a flexible leaden pipe attached to the cylinder, the upper end of which