The apparatus employed at Codnor Park, for heating the blast, is composed of two pipes, placed one above the other, in which are inserted small pipes, having the same centres as the large pipes. These pipes are connected by elbows, so that the air, in passing from the blast-engine through the interior pipe, spreads itself over the circular space between the pipes; passing then into the second interior pipe, is transmitted to the furnace by traversing the second circular

space.

This disposition of double pipes, one within the other, was adopted to remedy a serious inconvenience experienced at Butterly, an inconvenience incident to pipes of large diameter, in which the air being heated unéqually, a current of cool air passes along the centre of the pipe, and renders it impossible to raise the temperature sufficiently.

The large pipes are of cast-iron, 30 inches diameter outside, and 1 in. thick; the small pipes are of boiler iron, ths of an inch thick, and 18 inches diameter in the clear. The construction of the furnace is the same as at Butterly. The air is heated by means of this apparatus to 400° Fahr., with a consumption of 6 cwt. coal.

We have already stated that all the metal made at Codnor Park is made into malleable iron: this iron is used in the machine shops of Mr. Jessop. It serves equally well for boiler iron for steam-engines, a use which requires the very best metal.

Environs of Birmingham.

The introduction of the hot-air blast has scarcely commenced in the Staffordshire iron district, the opinion being still prevalent that the quality of the iron is deteriorated by its use, has retarded the trial of it until within a year past. One work only, near Wednesbury, belonging to Messrs. Lloyd, Forster, and Co., uses the heated air. The success attending this experiment determined the proprietors of the other works to make similar trials.

The apparatus employed here is placed above the trunnel head of the furnace, and is the only one at which such an arrangement has been effected in England. It is composed of a solid pyramidal ring, and a series of small tubes, which penetrate into the furnace.

The interior surface of the ring is a castiron cylinder, 4 feet in diameter, and 12 feet in height, in place of the chimney which usually surmounts the trunnel head of the furnace. The exterior surface of the pyramid is octagonal, and made of boiler plates, riveted together, like a steam-boiler, its dia

*This is an error, as large quantities of pipes are cast at this work for the London Market. Trans.

meter at the middle being 6 feet; a space is left between the surfaces of 1 foot on all sides; to protect the outer surface from the cooling action of the air, it is encased in brick-work.

The air passing from the blast-engine is carried to the top of the furnace, circulates through a circular pipe, on a level with the top of the furnace, then divides itself among eight vertical pipes, placed round the outer surface of the casing, which are connected with the circular pipe; each of these vertical tubes communicates with the interior of the case, or pyramid, by six small tubes, which pass into projections within the interior of the furnace.

The air, after being heated in the tubes, and in the circular heater, re-ascends to the tuyeres. To prevent the air from cooling during the transit, the conductor is placed in the chimney of the steam-boiler, 12 or 15 feet distant; a kind of brick work connects the furnace with this chimney.

With all these precautions, the temperature of the blast cannot be raised higher than to 360° Fahr., and they are obliged to heat it again in a furnace, within a few feet of the embrasure of the furnace.

The consumption of this fire is nearly 4 cwt. of coal to the ton of iron.

This apparatus is very costly, and requires frequent repairs; the little saving of fuel effected by it (about 3 cwt. of coal per ton of iron), is more than compensated for by the expense of construction and repairs, and, above all, by the numerous interruptions which take place in consequence of repairs required almost daily.

The introduction of hot air has effected, in these works, the same economy as in the others cited, where this plan is adopted. One ton of iron required, in 1831,3 tons of coke, equal to 5 tons 9cwt. of coal; now, the same quantity of iron consumes 2 tons 14 cwt. of coal, as the following statement shows.

On the 20th of July, there passed through the furnace twenty charges, composed of→ 10 cwt. crude coal, roasted ore,

9 6

Aux.

ous odours. Before the introduction of hot air, the daily production of the furnace was only 6 tons. They have, therefore, obtained, besides an economy in fuel, a diminution of the general expenses, and of labour. The quantity of blast has not been changed, but the tuyeres have been enlarged from 2 inches 9 lines, to 3 inches 6 lines.

Part of the iron produced at the works of Mr. Foster is used for the foundry, and part for fine metal; the same running gives both kinds of iron; that which flows first from the hearth is No. 1, pig metal; the last running gives No. 2. They distinguish the two kinds of iron by the manner in which they run from the furnace, and by the furrows produced on the surface when it cools.

Wales.

There are in Wales but two works using the heated air-that of Warteg and BlaenAvon, ten miles from Abergavený. None of the Merthyr Tydvil works have introduced it, though the Dowlais and Pen-y-danau have made experiments thereon.

The abandonment of heated air in so extensive an iron country, and in which improvements are sought after with care, has led many to doubt the reality of the advantages claimed for it. Some have thought that, while so much saving was effected by this plan in the furnaces of Scotland, where the metal was destined for the foundry, it could not be employed by other works, the product of which is converted into bar or malleable iron.

The examples furnished by the Newcastle, Codnor Park, and Wednesbury Works, in which they make bar-iron of very good quality, prove that this opinion is not well founded. The partial abandonment of the plan in Wales, should, in part, be attributed to the bad construction of their heating apparatus, but more especially to the diminished saving which would result to them, since the employment of crude coal has been effected; a saving which the cost of the patent would almost balance. To appreciate these reasons, it is necessary to enter into some details upon the expense of making iron in that country. From all the information gained upon the experiments made at Dowlais, or Pen-y-danau, it appears that, the apparatus being of bad construction, the temperature of the air could not be raised to more than 300° Fahr. Notwithstanding this, they attempted, with success, the substitution of crude coal for coke. An accident happening to the apparatus, obliged them to suspend the use of hot air for several days, and showed them that, without difficulty, the crude coal could be worked even with cold air. The saving which resulted from this substitution was such, that the proprietors

Add to this, the quantity consumed by the blast-engines, about the same for each, varying from 5 to 6 cwt.

The average quantity of coal consumed in each of these works, is, therefore, 2 tons for each ton of iron. By the employment of heated air, it is not probable that a saving would be effected over this expense of more than 33 per cent., or 17 cwt. of coal for each ton of iron; deduct from this, the fuel consumed to heat the apparatus, estimated at 6 cwt., and the actual saving would be reduced to 11cwt., costing at 3s. 7d. or 86 cents per ton, at the works, 44 cents; and as the patent right is charged at one-half, or 24 cents per ton of iron, the saving would be diminished to 20 cents per ton. This economy, itself very small, would scarcely be appreciated in a district where all the materials are so cheap, that iron may be produced at a less price than in any other district in Great Britain.

I believe, therefore, that the non-adoption of this plan in Wales, is no evidence that, it does not effect any saving in fuel; but, on the contrary, it leads me to think that there would be economy, as in other works where the plan is used; but it is evident that, the expense of coal being very small in Wales, the economy would not be as marked as in the works of Scotland.

*

The Warteg Iron- Works, which have been named at the beginning of this section, sustain this opinion. In this establishment the heating apparatus is composed of a very short development of pipes, so that the air cannot acquire a temperature of more than 400° Fahr. The coal, which is very bituminous, and loses 500 per 100 in the coking, cannot be employed crude in the furnace, with the air at so low a temperature; it results from

The author should have attributed this difference, in a great degree, to the superior quality of the Taff Vale coal over the Scoich, the former yileding more than 75 per cent. of carbon, while the proportion in the latter is less than 65 per cent.; some varieties even as little as 51 per cent.Trans.

these circumstances, that the saving is not so great as at the furnaces of Scotland, but it is to be compared to the saving in those works where the apparatus is not so perfect, and where coke is still used. Nevertheless, the diminution in the cost is very marked; before the introduction of heated air, one ton of iron required a consumption of two tons of coke; the produce of 4 tons 3 cwt. of coal. The consumption of coke is still about the same, but, as there is no necessity for carbonising it so completely, it is now produced by only 3 tons of coal.

The yield of the furnace has been augmented from 6 to 8 tons of iron each in 24 hours.

(To be continued.)

NOTES AND NOTICES.

Mr. Nash.-This celebrated architect died on Wednesday last, at his seat, East Cowes Castle, Isle of Wight, in his 834 year. In private life Mr. Nash was a warm-hearted and generous man; of his professional rank and talent, it is more difficult to speak soberly and justly. He was, as is well known, especially patronised by his late Majesty, who had a somewhat strange and fantastic taste in architecture, and was certainly not a man to be dictated to or controlled. After all, these are matters of comparative unimportance, when it is remembered, that to one or the other, probably to the one for suggesting and authorising, and to the other for elaborating out and carrying into effect, we are indebted for the magnificent improvements which have of late years taken place in Londonimprovements which contribute equally to the beauty and health of the town-to the luxury of the rich and the comfort and enjoyment of the poor. -Athenæum.

Canal between the Atlantic and Pacific.-Baron Thiery, of Panama, has addressed a memoir to the President of the Republic of New Grenada, on the subject of connecting the Atlantic with the Pacific. The Baron prefers a canal to the contemplated railroad, and pledges himself to complete one within two years.-American Railroad Journal.

The

The India- rubber Boat. The boat was invented, says the Providence Journal, by Mr. Caleb Williams, jun., of this city, and was manufactured at the India-rubber factory on Eddy's Point. It is constructed very much on the plan of Burden's steam-boat, with two inflated cylinders of Indiarubber cloth, connected upon the top by five or six beams of light portable plank, which supports a deck of boards, which may be procured at almost any place where the boat is to be used. The whole apparatus weighs about twenty pounds. cylinders may be both inflated in from five to ten minutes, and when the air is discharged, may be folded in a valisse. The rest of the apparatus may be conveniently carried in the bottom of a waggon or chaise. In addition to the whole is a seat, on which the angler may sit, and hold his dominion over the finny race. This boat will sustain at least one ton weight, and by enlarging the deck would accommodate quite a party. The elasticity of the cylinders has been proved to be a protection against their being punctured by snags and rocks.

Teams v. Steam.-"Quite an animated contest has been carried on for several weeks past," says the Frederick Md. Herald," between those enterprising mail-coach proprietors, Stockton and Stokes, and the Baltimore and Ohio Railroad Company, in the transportation of passengers between this city and

Baltimore, which has caused considerable excite ment among our citizens, who watch the arrival of cars and stages with much interest. On one day the stage will arrive, full of passengers, at a slapping pace, full 30 minutes before the cars-the next they come out neck and neck, or rather neck and hoiler-on the third the steamer is ahead, and dashes on to the depot like a thunder-cloud, with a streak of lightning attached to it-or a dog with a tin-pot to his tail. 'Hurrah, Stokes !' Hurrah Steam!' are now screamed out from many a throat, with as much fervour as ever was the battle-cry of Richard Cœur de Lion. How long this steam and team contest will last, we cannot say-for one of the parties seems to delight in hot water, and the other is determined not to break down whilst a wheel is left between this and Wheeling. But little we reck if it continues as long as the Trojan war, for it is rife with benefits to the editors on the route, and enables us to receive the eastern mail some hours sooner than formerly. The opposition of Messrs. Stockton and Stokes was caused by an extravagant demand by the railroad company for carrying the mail between Frederick and Baltimore."

English and French Ship-building. -"Those writers who contend for the superiority of the French in the art of ship-building, on the ground of the superior sailing qualities of their ships of war, have not gone sufficiently into the philosophy of the thing -not paid attention enough to the opposite national characteristics involved in the question. With the English seaman the great object has always been to come to close quarters-with the French to get away. Clerk, in his Naval Tactics, places this fact beyond all question, by a critical review of a whole century of rencontres between English and French ships of war. The shipwrights of the two nations took each their cue -very naturally-from their respective employers; one built for fighting, the other for flying and so it has happened-as surely as supply is always according to demandthat no ships sail so well as the French, and none fight better than the English."-Anglicus.

The small sketch which accompanied Mr. Gilbert's communication has unfortunately been mislaid. Could he oblige us with another?

Communications received from A Friend to Railways-Mr. W-n-W. H.-Mr. Jos. Gibbs -M. N.-T. D. E.-A Subscriber residing in Paris -Vigilans.

The Supplement to our last Volume, containing Titles, Index, &c., with a Portrait, on Steel, of Samuel Clegg, Esq., C. E., is now published, Price 6d.; also the Volume complete, in boards, Price 8s. 6d.

Our Publisher will give One Shilling and Sixpence for copies of the Supplement to Vol. IX.

Patents taken out with economy and despatch; Specifications prepared or revised; Caveats entered; and generally every Branch of Patent Business promptly transacted. Drawings of Machinery also executed by skilful assistants, on the shortest notice.

LONDON: Published by J. CUNNINGHAM, at the Mechanics' Magazine Office, No. 6, Peterbo rough-court, between 135 and 136, Fleet-street. Agent for the American Edition, Mr. O. RICH, 12, Red Lion-square. Sold by G. G. BENNIS, 55, Rue Neuve, Saint Augustin, Paris.

CUNNINGHAM and SALMON, Printers,
Fleet-street.

MESSRS. CLARK, NASH, AND LONGBOTTOM'S PATENT MACHINE FOR MAKING BRICKS, ACID-DROPS, LOZENGES, &c. The accompanying engravings represent a very ingenious machine, which has been patented by Messrs. Clark, Nash, and Longbottom, of Leeds and Market Raisin, for manufacturing bricks, tiles, acid-drops, lozenges, &c. It obviates effectually the principal difficulties which have hitherto attended the application of machinery to the manufacture of plastic materials, and is, we understand, coming into very general use. Fig. 1 represents a front view of the machine, and fig. 2 a back view. It is 9 feet high, and 5 feet by 4 wide. A vertical shaft a a, is made to re. volve in the cylinder, or pug-mill b, by the application of an adequate force from any first mover, which may be effected through the medium of gear applied to the bevel-wheel c, or by the employment of any other suitable mechanical agency. To this shaft are fixed broad steel or iron knives, or blades ddd; circular holes are made in the shaft, through which the rounded extremities of the large blades are passed, and secured on the opposite side by screwed nuts e e e, in such a manner as to allow of the position of the blades being easily adjusted, or inclined to the angle best suited to the preparation and passage through the cylinder or pug-mill, of a given quantity of clay or other plastic material, in a given time. When the mill is charged, the motion of the knives or blades, produced by the revolution of the vertical shaft, gradually tempers the plastic material, and forces it into the hopper f fixed to the lower extremity of the puginill. This hopper is divided into two equal chambers by a vertical blade or knife, which separates the clay, or other material; so that equal quantities are supplied to the moulds, and in a much stiffer and more homogeneous state than is practicable by the application of manual labour. The moulds employed are separate, that is, they may be detached at pleasure from the cavities in which they are lodged. Recesses for the reception of these moulds are formed around the peripheries of two pairs of wheels, with broad brims iii (one pair of which is plain, and is brought into view in the front figure; the other pair is

toothed, as seen at k k k in the back figure), and being in gear with each other, are made to revolve in opposite directions, by a motion communicated to one of them. At equal and proper distances are fixed two distinct wedge-formed boxes, denominated hollow sectors, marked 117. When so arranged, the form of the sectors causes a similar number of rectangular spaces to be left alternately between them, as denoted from A to L in the right-hand wheel, front view, and in the left-hand wheel, same view, by the figures 1 to 12. Into these the separate or detached moulds are put during the operation of the machine. The form and dimensions of the moulds are varied, according to the nature of the articles to be produced therefrom, and the moulds themselves (after being filled with plastic material) are pushed out from their recesses by means of pistons at m m easily fitting the recesses, and sliding upon parallel rods fixed to the rims of each wheel. To the bottom of each piston, and connected with the parallel rods, is attached a flat shaft, which carries a small anti-friction wheel P, which, by the motion given to the machinery, on approaching the place of delivery, comes in contact with a larger wheel q placed eccentrically, from the wheels of the mould receivers, and raises the moulds rr, containing the tiles, bricks, or other moulded articles, within them, which are then to be taken off and removed by the hand. During the latter process the emptied mould receivers will have passed over the centre of the eccentrically placed wheel, and the piston will have descended, or be descending, when the person in attendance replaces the emptied mould to its former situation, to be filled again from the hopper as it passes under it. The rims of the wheels for the mould receivers are made polygonal, or flatsided, at the edges, between the hollow sectors and the axis ss. These wheels revolve in plumber-boxes, mounted on pedestals or blocks, which slide horizontally between guiding grooves, made in a strong metallic framing or rails underneath. To one end of each pedestal is attached a helical spring t t; the other end of each spring abutting against a regulating screw, which passes through the extremity of the fixed rail; the re.. sult of which is that the pedestals and