Within a year or two, and extending to the present time, the manufacture of iron has greatly increased; and the construction of new works on the largest scale, and the enlargement of old ones, are pushed with such activity that it would be impossible to enumerate them, were it necessary, in a work like this. The attention of the traveller is attracted by the appearance of new works in unexpected places, and announcements of the more prominent ones are constantly made in the newspapers. Of these, we condense from the Public Ledger the following in relation to the Cambria Iron Company's Works.

"These works are situated at the confluence of the Little and Great Conemaugh rivers, immediately below the thriving borough of Johnstown, near the western slope of the Alleghany mountain. The property embraces about twenty-five thousand acres. The lands, with four charcoal furnaces, and other improvements, were purchased a few years ago, for the sum of three hundred thousand dollars. They are accessible by the western division of the Pennsylvania Canal, the Portage Railroads of the State, and by the Pennsylvania Railroad, which traverse them east and west. The country has been here upheaved by some internal convulsion, and with it on both sides of a narrow valley, the richest deposits of iron ores, bituminous coal, hydraulic cement, fire brick clay, and limestone, in strata contiguous to each other. The principal vein, adjoining the furnace and rolling mill, (carbonate of iron,) lies over the coal measures, about two hundred feet above the bed of the Conemaugh, and sixty feet above the tunnel head of the furnaces. It covers an area of one hundred and sixty acres, and contains an inexhaustible deposit of ore, which smelts very freely, requiring but little limestone, as a flux. It makes a superior quality of pig, either for forge or foundry. There are five coal veins besides, four above the level of the canal, and seven feet vein below, which the company will have to work with a shaft fifty or sixty feet deep, if ever they should need it. The second vein lies upon a bed of hydraulic cement, which is five feet thick and of good quality, and the third upon a bed of limestone, two feet thick, which is used for fluxing the ores in the furnaces. The great advantage of the estate is, that it presents one of the most eligible sites for furnaces, rolling mills, foundries, and other iron working establishments in the world, nature having provided an exuberant store of wealth, and left it to the art of man to take it out easily and roll it down to the tunnel head of the furnaces, a labour-saving machine, worked by the power of gravitation. The Cambria Iron Company has a capital

of a million of dollars, fully paid in. Besides the four blast furnaces, which have lately been enlarged and improved, and are now yielding a product of two hundred tons of pigs per week, the company have nearly completed four other blast furnaces, for smelting with coke the iron ores taken from the face of the hill, and calculated to produce each five thousand tons of pigs per annum, making an aggregate of about twenty-eight thousand tons per annum. They have also finished a large rolling mill, six hundred by three hundred and fifty feet in extent, in the shape of a cross, with sixty puddling stacks, twelve heating furnaces, four scrap furnaces, &c., and which, when in full operation, will produce more than one hundred tons of railway iron per day, or thirty thousand tons per annum. This, we believe, is the largest single mill in existence. The engine for the four blast furnaces is four hundred horse power. To drive it, there are eight boilers to each furnace, thirty-two boilers in all, sixteen of them forty feet long and thirty-six inches in diameter, and sixteen thirty-four feet long and thirty inches in diameter. The steam cylinders are two of twenty-eight inch bore and eight feet stroke, and the blast cylinders are seventy-two inches bore and six feet stroke, making at full speed seventy thousand cubic feet of blast per minute. The fuel for making steam and heating the hot blast pipes, is furnished by the gas extracted from the furnace stack flues below the tunnel head, and ignited under the boilers. The aggregate horse power of the mill is four hundred and forty, driving four engines. The engine for the squeezers is forty-two inch stroke, eighteen inch bore and eighty horse power; for the roughing rolls, it is six feet stroke, twenty-six inch bore, and one hundred and fifty horse power; for the rail mill it is four and a half feet stroke, twenty-six inch bore, and one hundred and fifty horse power; and for driving blowers, shears, pumps, saws, &c., the engine is forty-two inch stroke and sixteen inch bore. There are sixteen boilers of thirty-six inches diameter, and forty feet long."

Gas, as an auxiliary in smelting iron, in Pennsylvania.

The quantity of coal [anthracite] usually required in the iron works, has of late been reduced by the process of heating the blast by the gas from the top; and the steam engine is worked by heat derived from the same source-the boiler being at the top of the fur

nace.

The following account of the construction of blast furnaces for smelting iron with anthracite, was prepared by the editor of this edition, for the American Journal of Science, in which it appeared in 1848. The details are those of the Chikiswalungo furnace, near Columbia, Pennsylvania, of which the editor is senior proprietor.

"The anthracite which we have found best adapted for smelting iron, is that of the Big Vein of Wilkesbarre, furnishing the coal of the 'Baltimore Company;' the 'Diamond,' of M. C. Mordecai; and the 'Black Diamond,' of Robarts, Walton & Co.; all of which are

from the same strata and of the same quality. These coals command about twenty-five cents a ton more in the general market, than the others in this part of the coal region. The Pittston coal is of a good quality, but being softer, it makes more waste in handling, and being more distant, transportation downwards is somewhat higher, and boatmen will not go there for freight, if they can get it lower down. The North Branch canal extension being completed, this coal will in future have its natural outlet northwards.

"The Pine-Grove region supplies an excellent coal for domestic purposes and the generation of steam. It is not hard enough for smelting iron, although it can be used.

"Some of the Shamokin beds, or those of the Coal Mountain Company, we judge to be well adapted for smelting iron. We have not been successful in using Plymouth coal.

"Passing eastward to the Schuylkill and Lehigh region, we again meet with good iron smelting coal. Most of the Lehigh coal will answer this purpose, except that of Buck Mountain, which is a free burning white-ash, well adapted for generating steam. The Broad Mountain white-ash coal is among the best for iron smelting. Redash coal generally burns too freely for this purpose, although well adapted for steam purposes.

"The occurrence of inexhaustible strata of anthracite coal in Pennsylvania, has attracted the attention of miners and practical men generally, to its use in smelting iron. With charcoal, this process requires a peculiar location, and a large capital, to be invested in extensive woodland tracts, which are generally mountainous, and consequently cheaper, being unfitted for agriculture. This renders the construction of the necessary roads difficult, and transportation expensive. The number of workmen employed in wood-cutting, coaling, and hauling, is large, and the expense of horses and wagons, forms a considerable item. Charcoal being a soft, porous material, much of it is wasted in transportation and handling, and large sheds are required to store and keep it dry. These various contingencies. require the general manager to have industry, judgment, and good business habits. In using anthracite, the exact expense of the fuel is known, the transportation being by railways or canals extending to most of the mines, and if the furnace is placed near such public works, there will be but little waste of coal in its final transportation. There is but little waste in the transportation of ore, which is of course common to both kinds of fuel.

"The earlier attempts at smelting iron with anthracite in the ordinary furnace, failed so completely, that it was by some deemed impossible to accomplish it; while others, looking to a different construction for a solution of the problem, devised various structures, more remarkable for ingenuity than utility; later experiments having proved that no such modifications are necessary, except perhaps a higher inclination of the bosh and a less contracted tunnel-head."

"Incandescent anthracite has the peculiarity of being rapidly extinguished when struck with a blast of cold air, the loss of heat

from this source exceeding that resulting from combustion; and although this phenomenon does not take place when the temperature exceeds a certain point, the vast accession of cold air in a blast furnace, may be sufficient under slightly unfavourable conditions, to produce it at any time. Hence a hot blast, which is economical when charcoal is used, becomes an essential element of success with anthracite; and its temperature should not be less than is sufficient to smelt a slip of lead opposed to a jet of it near the twiers. Anthracite being a very dense and concentrated fuel, the amount of air thrown in must be much greater than when charcoal is used. Success, therefore, depends upon the quantity as well as upon the temperature of the blast.

"The necessary amount of oxygen can be secured only by means of the proper machinery, and a certain velocity of the blast; and in consequence of this fact, the false opinion that the effect depends merely upon the velocity or sharpness of the jet, is universally maintained. In consequence of this view, the exit pipe is reduced to a small size, and the quantity secured by increased velocity under a high pressure; which causes much of the blast to be lost, as among the multitude of joints to be made air-tight, it is impossible to secure them all. Besides this, the machinery is liable to injury from the great and unnecessary strain upon it.

"The stack or main structure of a blast furnace, is a quadrangular pyramid, the lower portion of which has an arched passage through the middle of each side, leaving four large piers of masonry. Three of these passages (A, fig. 1) are named twier-arches. The junction of these arches forms an open square about one-third the diameter of the stack, in which the hearth, (which requires renewal from time to time,) is built up with large cut stones of siliceous conglomerate or sandstone. Near the top of the hearth, the inner portion of the four arches is closed by forming a square with eight large sows or iron beams, four of which are shown in section at S in fig. 2, their position nearly corresponding with the dotted square in fig. 1. The dotted circle in fig. 1, indicates the internal face of the fire-brick lining (1, fig. 2) at its widest part, and also the top of the bosh,* (b, fig. 1, 2.) The lining being circular and the lower portion a square, the former is supported upon four plates (q) of such a form as to close the angles of the latter, and at the head of the furnace it is continued in an ordinary brick-work chimney, (z, fig. 3,) leaving one or two large vacant spaces for the purpose of filling. The chief use of this chimney is to protect the workmen from the heat.

"The two posterior piers have a circular passage (fig. 1, 2, g) for the admission of the blast pipe, p, which descends from the hot-oven (o, fig. 3) at the head of the stack. This passage is sometimes continued through the front piers, which renders the front or working arch, cooler, and gives more ready access to the twiers. The blast pipe is carried by appropriate branches to the posterior and lateral

This word is from the German word böschung, a slope.

twiers, t, t, t, fig. 1, the former being seen in longitudinal and one of the latter in transverse section, at t in fig. 2.

"To prevent the twier from being destroyed by contact with the fire of the hearth, it is made of an interior and exterior cone of wrought iron, with a stream of water circulating between them. The twier receives the nozzle, and this the belly-pipe, which is attached to the terminal upright portion of the blast-pipe, called the ball-and-socket joint, from having a connexion of this kind. Behind this, at k, there is a small aperture, to insert an iron rod to detach any slag that may cling to the twier. As the smelted materials within the hearth frequently rise above the twiers, it is evident that, in case the blast should be accidentally checked, they would flow into the blast-pipe. To prevent this, a valve (v, fig. 2,) is interposed, which is kept open by the blast, but falls the moment the pressure is removed.

"The cavity of the hearth, (Hh, fig. 1, 2) where the metal is reduced and retained, bears a very small proportion to the size of the stack. In the figures, which are drawn to a scale of one-eighth of an inch

to a foot, it is two feet wide, and five and a half feet long, but enlarges upwards in a slight degree. The back and front of the hearth are separated by a partial partition called the temp, (m, fig. 1, 2,)