for about 12 hours, when the melted metal is run off into pigs. After this first discharge or casting, the ore is added at the rate of 25lbs. for every 100lbs. of fuel, for a second period of 12 hours, when a second casting of pig iron is run off. After this second discharge, ore is added at the rate of 30lbs. for every 100lbs. of fuel during a third working period of 12 hours, and thus in each successive period of 12 hours, the quantity of ore is increased at the rate of five per cent. of the weight of the fuel, till eventually the proportion of ore amounts to about 65lbs. or 70lbs. for every 100lbs. of fuel. By proceeding in this way, and by throwing in the ore merely reduced to the size of peas, or thereabouts, but not roasted, if the furnace be well attended to by the workmen, it will turn out about 50lbs. of pure pig iron for every 100lbs. of fuel consumed. To convert the carburet or cast iron thus produced into steel of any degree of hardness, it is melted in a cast iron or cupola furnace, by the heat of coke or other fuel; but, in all cases, no more fuel is used than is requisite to melt the iron, so that the oxygen of the blast shall serve to burn away the carbon of the carburet in a considerable degree, while a further portion of the carbon is neutralized or removed by the addition of scraps of metallic iron, or by the oxides of iron or of manganese. To produce a superior cast steel from the pure cast iron, sesquioxide of manganese, or peroxide of manganese, which has been previously ignited, is introduced in quantities not exceeding five per cent. into the cupola: no more fuel is used than the blast can readily burn into carbonic acid, otherwise the excess of the carbonaceous flux would deoxidize the manganese, nullify its decarburating action upon the cast iron, and thus prevent it from reducing the metal to that lower stage of carburet which constitutes cast steel. Sometimes, for the same decarburating purpose, a portion, not exceeding five per cent., of chrome ore may be used. When the decarburation has been carried in the cupola to the proper pitch, the steely metal is to be run out, and cast into iron moulds. The ingots thereby formed, are now to be converted into steel of any desired degree of mildness, by a further process of decarburation, which consists in stratifying the said ingots along with peroxide of iron, or peroxide of manganese, without charcoal, in a steel cementing furnace, which should be lined with sheet iron, if it is constructed of fire bricks or stone, to prevent the action of the peroxides upon the stone or bricks of the furnace. The ingots are to be here subjected to a cementing heat for a certain period, proportional in duration to the softness required in the metal. Mr. Heath further improves the quality of malleable or bar iron, by adding" to the pig or plate iron in the puddling furnace, while in fusion, from one to five per cent., or thereabouts, of any pure oxide of manganese, the sesquioxide being preferred. An improved quality of cast steel is made, by putting into a crucible bars of common blistered steel, broken as usual into fragments, along with from one to three per cent. of their weight of carburet of manganese, and exposing the crucible to the proper heat for melting the materials, which are, when fluid, to be poured into an ingot mould in the usual manner. RANKIN'S IMPROVED RAILWAY CARRIAGE WHEEL. Sir, I send you herewith, the drawing and description of an improved railway carriage wheel, with the results of a series of experiments I have made with it, which I trust will be interesting to your readers. As it would occupy too much of your valuable Magazine to give a full detail of the experiments I have made, I shall be as brief as possible. The object had in view was to diminish the friction which the wheels in present use have on curves, and which I consider I have by my improvement accomplished. Many engineers are of opinion that the cone of the wheel is sufficient to adjust the axletree to a right angle with the rails, and that the flange seldom or ever touches the outer rail of the curve. I grant this hypothesis, if a curve be of the same radius, the engine always travelling at the same velocity, and the carriages of the same weight; but even then they will have a tendency to run in a straight line, for the centrifugal force will cause them to fly to the outer rail, and the flange being on the inner edge of the wheel now in use, will rub against it, and great friction is produced FINDING LENGTHS AND BEVELS OF HIP-ROOF TIMBERS. 39 and much power lost. I have found it so in my small experiments, and I am inclined to think that they are correct, from the fact that the outer rail is always more worn than the inner. When trains go off the rails in a curve, in most cases they take the outside; such was the case, for instance, in the accident which occurred shortly after the opening of the Eastern Counties Railway, on that line at Stratford. So different is the action of my wheel on the curves, by the flange being outside of the rail, that if the cone is not sufficient to counteract the centrifugal motion the flange comes in contact with the inner rail, and causes friction sufficient to adjust itself to any curve; thus the friction becomes useful, acting on the same principle as a rudder of a ship. The experiments I made were with a railway 24 feet long, with several curves on it, and inclined sufficiently to cause the carriages to run of their own accord. The wheels and carriages were all of equal weight and dimensions, and the cones and flanges exactly corresponding, except that the flange of my wheel was on the sinal part of the cone or tyer of the wheel as in the drawing, which position of the flange constitutes my improvement. The action of both plans on a straight line appears to be nearly the same, my wheel gaining but little, but on the curves it gains one foot in eight. I am, Sir, your very obedient servant, Poplar, July 2, 1839. A NEW SYSTEM OF LINES, FOR FINDING THE LENGTHS AND BEVELS OF THE TIMBERS IN A HIP-ROOF. Sir,-Having been rewarded by the Society of Arts with the Silver Isis Medal, for a system of geometrical lines, invented by me, for obtaining the length and bevels of the timbers in a hip-roof, I hope to be allowed, through the medium of your invaluable journal to communicate it to the public, hoping it may be the means of creating a discussion of the theory of roofing lines in general. I am not aware that any thing relating to this subject has been brought before the public since Nicholson published his Carpenter's Guide. The method I here introduce will be found to be on entirely different principles to the one in the Guide; how far it merits a claim of superiority is left for the public to determine. I am, Sir, yours respectfully, Leicester, September 2, 1839. JOSHUA JEAYS. Let A E D C, in fig. 1, represent the wall plates of a building; ABC, a vertical and transverse section of the roof, A B and B C representing common rafters; the dotted lines E F, DF, the seats of the hips, and the line qr the seat of a jack rafter; let also B K represent a line from the ridge-piece at right angles with A C, and m n op a section of the punlin placed in its proper position with respect to the common rafter. Then, with C as a centre and radius GB, cross the line A C in G, and with the same centre, and radius CF, cross the line C B in J, join the points D and G, and from the point J draw the line JH perpendicular to CB, meeting B K in H; set off the distance J H along the line A Cfrom Fto L, join the points K and Land produce the line q r to s: this being done the lengths and bevels are as follows: LENGTHS AND BEVELS OF THE TIMBERS IN A HIP-ROOF. Bevels of Timbers.-The angle CB'F is the bevel of the head, and the angle BCF, that of the foot of the common rafter. 41 The angle D G C is the bevel of the top or bottom side of that end of the jack-rafter that buts against the hip, and CBF is that of the vertical sides of the same. MAKING SUGAR BY STEAM AND IN VACUO. Sir,-In No. 468 of your Magazine for the year 1832, I find a letter on the above subject, by a Mr. Booth; he says, "the process is likely to revive the spoiled fortunes of the West India planters; that they are indebted for it to the indefatigable exertions of Mr. W. Oaks, of Houndsditch, and that jus at the period the new apparatus for crystalizing the cane juice, reached Demerara, the Board of Commerce was discussing the propriety of giving 10,000%. to some French adventurers, for divulging a process, thought to be similar." He does not, however, affirm that Mr. Oaks is the actual inventor. An article on the same subject, written by a Mr. T. Dodson, of Demerara, and inserted in the Demerara Gazette, follows Mr. Booth's communication, and that gentleman observes, "It is the first of many scientific experiments and much indefatigable perseverance of a late very eminent chemist. The invention is not absolutely ascribed to this gentleman.' He further adds, "that four gallons of sugar made in the teache weighs 24lb., but that the same quantity made in the vacuum pan weighs 32lbs., and that the Hon. Edward Charles Howard was the inventor of the said pan, and that it had been in use amongst refiners for twenty years.' That is, for 20 years before 1832. Another communication without a signature, succeeds Mr. T. Dodson's which remarks, "that the new method makes twice the quantity of sugar which can be produced by the old method, and that it fetches twelve shillings per cwt. more in price in the market. Here then is one of the most unfortunate inventions that ever appeared on earth, and not only not patented, but the West India planters and the community are left in doubt to whom they owe this invaluable obligation, for it is not absolutely conferred on either Mr. Oaks or the chemist. If it originated with the gentlemen here mentioned, they are entitled to receive from the West India planters and from the government, the largest premium that has ever yet been conferred for any discovery during the last 200 years! Mr. T. Dodson ought, at any rate, to have favoured the world with the name of the "eminent chemist," to whom it is so much indebted, that a public tribute might have immortalized his memory. - I will now, Sir, proceed to give you a short and a very faithful history of this invention, but without the smallest desire to withdraw a particle of merit from any one who may have been actively engaged in carrying it into effect; for even supposing that the vacuum pan had been in use for twenty years amongst refiners, it had never been employed in crystalising the juice of cane until a period subsequent to that, nor did the actual inventor of the new method of making sugar, know that such a machine existed at the period of his experiments. In 1822, ten years previously to the date of these letters, I was resident in Bahia. The Brazilians were then fighting for their independence. The above city was the last the Portuguese held, and it was many months besieged before they capitulated. During that time all commercial pursuits were suspended. I never was an idle man, so that after leaving my office I usually passed two or three of my evening hours in my small laboratory, analysing and synthesising, or distilling for my amusement. During this protracted leisure therefore, I found this a very acceptable source of gratification. One morning it occurred to me, that although sugar and salt are articles produced from alınost a colourless fluid, yet the one was brown and the other exquisitely white. After frequently reflecting on what could possibly be the cause of this difference, I came to the conclusion that the saccharine particles must be carbonised in the operation of crystalising the cane juice, which was the only reason I could form for their being thus browned and discoloured. I therefore had some apparatus constructed to evaporate the said juice by steam, and in vacuo in order that I might boil it at the lowest possible temperature. My first experiment was successful. The sugar formed into crystals as clear as glass, but were much larger than any I have seen from Demerara. I resolved in consequence to take out a patent for it in the Brazils, wrote my own specification in Portuguese,—(a copy of which, Sir, I will show you, the ink by time and a change of climate being much faded)-I placed it in the hands of a judical friend who promised to convey it to Rio, and to secure it every requisite attention. The government, however, was at that time so unsettled, that I heard nothing more about it up to my departure for England in 1825, and nothing since, although I have written from time to time for information.* Before I quitted that country, however, I very thoughtlessly adinitted a Frenchman into the secret, as my family are fully aware, to whom I promised half the benefits resulting from the patent, on condition that he would undertake its entire management. This gentleman shortly after disappeared, and *We have inspected the specification referred to. It is dated" Bahia, 25 Junho 1822"-and there can be no doubt of its perfect genuineness.-ED. M. M. |