the crown of the fire-box, this opening being covered or exposed by a sliding cast iron door. Around this opening, a hopper or curb is raised up-large enough to hold coal, perhaps enough for once firing. A loose, swinging cover is placed on the top of this curb. When running, the back doors of the firebox are seldom open, but this hopper is filled, and its contents then dumped (by withdrawing the sliding door) over the grate.

It will be remembered that the fireman's footboards are on the tender, and that there are two decks or landings, one over the other-from one of which the lower doors may be fed, and from the other of which the coalhopper may be filled.

The ash pan has a tight bottom, so as to hold three or four inches of water, -into which the slag and loose coals drop and are extinguished. In the smoke box there is a variable exhaust. The chimney is straight,-has no deflecting cone, and only a grating over its top. For all the other coal boilers named, the chimney is mostly of this kind.

Millholland's Boiler.-The fire-box, variable exhaust and chimney are essentially like Winans'. There is, however, no coal feeding hopper on the back of the fire-box, as the fire-boxes on these boilers are square,-five feet each way. The peculiar feature of these boilers is the combustion chamber. This is a sort of smoke-box, placed within the boiler, surrounded by water and about five feet from the fire-box tube-sheet. One set of tubes lead from the fire-box into this chamber and another set lead from this to the smoke-box, there being thus two sets of tubes and four tube-sheets. A square leg comes down from this combustion chamber, through the bottom of the boiler, there being a water-space around this and a door on the bottom. Through this leg, a man may get into the combustion-chamber to set and caulk the flues. A few of the stay bolts in this leg are hollow, to admit air to complete the combustion of whatever gases have not been already burned over the grate.

O. W. Bayley's Boiler.-The novel feature is contained in the fire-box. This is divided into three chambers or compartments; a water space, four or five inches thick, passes from near the top of the back side of the fire-box, sloping downwards to below the tubes on the front side,—thus dividing the fire-box into an upper and lower chamber. The lower part is again divided in its width by a fore-and-aft vertical water bridge, connecting at top with the water space above described. A square opening is made through the vertical water space, so as to open the two lower chambers into each other. Two openings are also made and covered by sliding doors, in the sloping water space above. The fire doors open, one each into the lower chambers.

The mode of working is this. Fire is first made on the grates on both sides, or in both of the lower chambers, and both of the sliding doors above are opened. After the coal gets well to burning and when fresh coal is applied, the fire-box is managed as follows:-The left hand sliding door only, upon the sloping water space, is left opened. The right hand fire door, or feeding door is also opened, and coal applied to the right hand grate. The flame and gas from this coal pass through into the left hand lower chamber, over the burning coal on that side, thence up through into the upper chamber and off to the tubes. The firing is then reversed by shutting the left hand sliding door and opening the right hand one. Coal is then put upon the left hand grate. The gas passes through into the right hand lower chamber, over the hot fire, up into the upper chamber and again off through the tubes. By this means, the coal becomes partly coked before it is finally burned, and the gases are probably quite entirely consumed.

Latta's Boiler-A recent application of this boiler by the Boston Locomotive Works has attracted some attention. The furnace is a square chamber, seven or eight feet high and with a water space all around it. The water is contained in coils of tubing. A length of iron pipe, say of two inches diameter, is laid across the furnace above the grate. This pipe has a return coupling on one end, and another length of pipe is brought back, and so on for a few courses in height. Then the return couplings divide or throw out each

two return nozzles, thus doubling the area of tubing through which the steam and water circulate. After a few courses of these double tubes, the return couplings again divide and send back four lengths of tube, side by side, and all connected with the original tube. And after a few courses of these quadruple tubes, the couplings again divide and send back eight lengths of tube, with which number the pile is completed. As many separate and complete piles, or courses, of this kind, are laid up, as will occupy the whole width of the fire-box. These piles are connected at top and bottom with the water space of the furnace around them, and the heat of the fire circulates freely through them. The chimney surmounts the whole.

M. W. Baldwin & Co.'s Boiler.-Perhaps no other form of boiler in successful use, has been made to burn coal with so little change of form and structure from that of the common kind. The fire-box is five or six feet long, the back of the fire-box and fire-door the same as for an ordinary woodburner; the grate is stationary and of the common pattern, only heavier. The boiler has a variable exhaust and open chimney. About the only peculiar feature is a horizontal row of two-inch iron tubes running across the width of the furnace, just under the crown. These give an increase of heating surface and quicken the circulation of the water.

There are many other varieties of boilers now in experimental use, but we are not able to furnish as full particulars of them as we would wish. From those we have mentioned, leading ideas may be had of the forms of boilers already most prominently before the public.-R. R. Record.

COAL BURNING LOCOMOTIVES.

After a variety of experiments, A. S. Adams, master machinist of the Boston and Worcester Railroad, has now in operation a freight locomotive adapted to burning coal, which seems so well to meet the wants of the road that all the engines of the Company, used in drawing freight, are to be altered to the same style. The engine in question, the "Bison," has one of the Delano grates, by which the coal is forced from the bottom up through the bed of the fire. This grate is but 38 inches in length, but by its manner of operation all the gas is consumed, and the top of the bed of coal is kept always ignited, no new coal ever being thrown upon it. The draft is also kept good and is never obstructed by clinkers. Careful estimations of the precise cost of running this engine have been made, and it appears that with it, for 12 cents per mile, a common freight train can be run and make the usual speed. A wood engine to run the same train costs 30 cents per mile. The saving, as will be seen, is very great. The cost of altering a common wood engine to fit it for burning coal is but $150; and as we have before remarked, the Worcester Company have decided to have all the freight engines converted into coalers as speedily as possible.

IRON AND ZINC.

STATISTICS of IRON MANUFACTURE.

During the six months ending December 31st, 1855, the importation of Pig iron from all foreign ports reached only 29,839 tons. This is less than one third of the amount imported during the previous twelve months. Since the commencement of the present year the production of Pig iron east of the Alleghanies exceeds the quantity manufactured during the same period of any previous season.

It is computed that 280,000 tons of Pig iron will be produced in the West during the present year-this, of course, includes Western Pennsylvania. From the districts of Alleghany, Hanging Rock, and Clarkesville, about 200,000 tons will be sent to market. There will be a decrease of Charcoal Pig in the present year, when compared with the production of 1855, of 55,000 tons. The product of new coke and raw bituminous coal furnaces will, however, make good at least 15,000 tons of this deficit. The amount of Anthracite Pig consumed in the West in 1855, was 33,000 tons. There will be an increased amount needed during the present year.

According to a statement in the Iron Master's Review, the following is the quantity of iron consumed in the places named in the West:

The product of American rails this year promises to be at least 145,000 tons, and may possibly reach 175,000 tons. Brady's Bend works have commenced full operations; Cambria and the Lackawanna have added considerably to their puddling capacities.

By reports from sixty-one railroads, it is ascertained that they have an aggregate length between termini, of 5,840 miles, and of sidings and second tracks, 974 miles; making a total of 6,814 miles of track. These roads are to have an addition in 1856, of 873 miles, of which 300 miles is for renewals; the remainder, 573 miles, is for additional sidings and extensions. These sixty-one roads are laid with rails having an average weight of 91.3157 tons per mile, or 58.11 pounds per yard.

The weight of the whole of the old track, 6.814 miles, is
The weight of the track to be laid this year, 878 miles, is
The weight of old rails to be renewed, 300 miles, is

622.225 tons 79,718

66

27,394 "

If we estimate comparative figures from the aggregate miles of railway which were in operation in the United States, December 31, 1855, by the figures accurately obtained and given above, we have the following results:

Total number of miles of distance between termini,
Miles of sidings and second track,

Total number of miles of track,

Extensions, renewals, and additional sidings, to be laid in 1856,
Renewals of track in 1856,

Total weight of rails in 25,189 miles of track, 91.3 tons per mile,
Weight of rails required for 3,361 miles, in 1856,

Weight of old rails from 1,159 miles,

21,440 miles. 3,749

25,189

66

3,361

1,155

2,299,755 tons.

806,989 4

105,561

We have no satisfactory data by which to judge of the extent of new railways to be opened this year.

Statement exhibiting the Quantity and Value of Railroad Iron imported into the United States, from the 30th of June, 1889, to the 30th of June, 1855:

By recent arrivals we have accounts of important improvements in the manufacture of malleable iron and steel, from which a great revolution appears to be anticipated. The descriptions which have appeared are very numerous, and we annex such as appear to give the most complete view of the whole subject. The London Mining Journal thus briefly describes them :

Mr. Henry Bessemer, of Queen Street Place, has patented some improvements in the manufacture of cast-steel, which consists in constructing a furnace having a long rectangular chamber, the mouth of which is on a level with the floor of the foundry; the sides and ends of the chamber are vertical and parallel to each other, and the bottom of it is formed into an elevated ridge, which extends the whole length of the chamber. This ridge is formed by the apex of a pointed arch, which is made below it, and is called the cave. Along each side of the furnace there are arranged fire-bars, which extend from the lower parts of the ridge for some distance up the vertical sides of the chamber, there being no fire-bars at the bottom of the chamber; the central part of the ridge is flattened, and there are formed in it, at equal distances, several holes, over or into which the lower end of the pots or pot-stands is placed, so as to insure the proper position of the pots. The top of the chamber is covered with large fire tiles, or with an iron frame, in which fire bricks are fixed, several openings being left to afford access to the pots. Along one side of the furnace there is a row of square holes, leading into a chimney of sufficient height to insure a powerful draught. The pots preferred being of the form known as skittle pots, with a lid to each, and a tapping hole made in the bottom of them. The pots should be placed on a stand some 4 or 5 inches in height; or the lower parts of them may be elongated, so as to form a stand, and be of such a size as to fit the holes in the top of the ridge, so that access may be had to the underside of the pots from the cave below. The fuel used should be hard oven coke, which is supplied from the opening on the upper side of the furnace, the fuel filling up the spaces round about the pots, and rising as far as the top of them. The fire-bars are placed below the foundry floor, and the air for combustion is supplied from the cave below the furnace, which, when the draught of the chimney is alone depended on, must have a free communication with the outer air; but, in order to obtain a powerful combustion in the furnace, the cave below is usually closed, and a blowing fan employed, by means of which air is forced into the cave, and thus the draught of the furnace assisted. Access is obtained to the caves by means of a revolving door, which acts as a valve, and will allow a workman to walk through it on one side of the axis (which is vertical), while at the other side a small portion only of the compressed air escapes, the revolving door being in part enclosed in a cylindrical casing. At a convenient distance from this furnace a finery furnace is constructed, or a common cupola blast furnace, in either of which the pig-iron intended for conversion into steel is melted. From time to time the finery or cupola furnace is tapped, and the molten iron run into a ladle; the metal is poured from thence into the pots, where its high temperature will be still further increased. Above the furnace is an iron pipe, covered with brickwork, or otherwise protected by a bad conductor of heat. Into this pipe highly-heated atmospheric air alone, or air and steam mixed, or steam alone,

also highly heated, is forced under a pressure exceeding that of a column of metal equal to the depth of fluid metal in the pots. Although the action of highly-heated air or steam produces a more rapid change in the quality of the metal than cold air or steam of low pressure, and for that reason is to be preferred; it will, nevertheless, be understood that air less heated, or of the ordinary temperature of the atmosphere, and steam of the temperature due to a low pressure, may be used in all cases where it is desired to do so. The flow of air or steam into the pipe is to be regulated by a valve under the control of the workmen who attend the furnace. A small movable pipe is placed vertically over the centre of each pot, and passes freely through a hole into a branch of the air-pipe above, and is capable of sliding downward as far as the bottom of the pot, or nearly so. In order that the pipes, when they are withdrawn from the pots, may be moved on one side, and thus afford free access to the furnace mouth, they are constructed accordingly. The pots having been charged with molten iron, air or steam is passed through it, subjecting every part of it to the chemical action of the gaseous products passing through it, and it becomes steel.

On the other hand, the London Review goes into a very extensive sketch of the entire proceedings, which perhaps will be more acceptable with those less familiar with the manufacture of iron :—

When it was announced at the late meeting of the British Associatior, that a paper would be read on a new method of converting cast into malleable iron without the use of fuel, the intelligence was received by many with a smile of incredulity, and not a few "practical men" went to the meeting of Section G, expecting to be entertained by the visionary schemes of some ingenious but idle enthusiast. Their expectations were utterly falsified. Conviction was forced upon minds from which no ready assent could have been hoped; a great invention was lucidly and unostentatiously propounded; and men who went prepared for an exhibition of temerity, if not of folly, remained to express their concurrence in the graceful tribute of admiration paid by Mr. Nasmyth to one of the greatest discoveries of the age. Every one felt, after hearing Mr. Bessemer's paper, that, if any reliance could be placed upon the facts stated to the Association, a new era was at hand in all those numerous and important branches of manufacturing industry which concern the working of wrought iron and steel. Without further reference to the paper communicated to the association, we will now describe what we have seen at Mr. Bessemer's premises at Baxter House, leaving our readers to say whether we have overstated the importance of the subject.

It is necessary to premise that common cast iron contains somewhere about 4 or 5 per cent. of carbon, as well as a variable quantity of silicium and other earthy basis, phosphorus and sulphur. The object of every process for making malleable iron is the separation and removal of these foreign substances. The best malleable iron contains about per cent. of carbon; but the process of extraction is difficult and expensive. The fusibility of iron depends upon the quantity of carbon present; and no commercially available method has till now been discovered by which iron, after parting with a very large proportion of its carbon, can be brought to remain in a state more nearly approaching fusion than that of a pasty mass. Steel is produced from iron from which the carbon and other impurities have been extracted, by a tedious and costly process, the object of which is the restoration of a portion of the carbon which previous processes have removed. Steel contains, according to the purposes for which it is wanted, from rather more than per cent. to rather less than 2 per cent. of carbon. Malleable iron-or iron comparatively free from carbon-is usually produced, in this country, in the following manner:

The melted iron, as extracted from the ore in the smelting or blast furnace, is run out into bars a few feet in length, technically termed pigs. These pigs. when cold, are removed from the sand-holes into which they were run, and transferred to a second furnace, called "the fining furnace," where they