used in the preparation of coal have not been imp: ved upon to any great extent since they were first introduced. The plants have been enlarged in various ways, but the principle is much the same in all their parts. The buildings are frequently 100 feet in height, to allow the coal to pass from one set of toothed rolls to another, which it does through inclined passages lined with sheet iron to permit the coal to slide instead of rolling, which increases the waste. A first-class 'breaker has a double set of large and secondary rolls, double screens for each set, and storage capacity for, 800 tons of prepared coal. The cost of such works is about $50,000, and their duration is about twelve years, though the machinery is liable to be broken by various causes, and parts are frequently renewed. hauled out and dumped upon the culm-banks at some distance from the breaker. Among the few improvements made in breaker-machinery is a machine for picking slate, called a "jigger.' This machine moves up and down in a tank of water: it is virtually an iron basket with a grated bottom, into which coal and impurities intermixed are dumped, and is worked by means of a crank or eccentric motion. The resistance of the water acts upon the coal and slate in this rising and falling movement by their different specific gravities; the former, being lighter, is carried over the edge into one compartment of the tank, and the latter, being heavier and thin in shape, falls and works through the grate into the other compartment; each is then raised by a small elevator and carried to its place of deposit. The operation of this machine washes the coal, and is more economical than picking by hand, but is less effective in separating all impurities, as the difference in specific gravity is not sufficient to make the separation perfect. "The slate and other larger impurities which are carried through the rolls and screens are generally picked out by boys called 'slate-pickers,' who are seated beside the troughs leading the coal from the screens to the chutes, and check its flow while they gather the impurities and throw them into other The accompanying description and illustration (Plate troughs, which carry them to the dirt- and slate-chutes, XVIII.) of an anthracite colliery-breaker are repubwhence they are loaded into small dumping-wagons and lished, by permission, from the report of Heber & mixed with or adhering to it, is collected in the slatepicker hopper D, from which it is taken along the tramway Z to the boiler fires, and used as fuel. Thompson, E. M., to the Girard Estate Trust of Phila- picking, containing a considerable quantity of good cea delphia in 1879. The drawings of the Hammond colliery-breaker exhibit a ground plan and a front and side elevation, and show the arrangement of the machinery and method of cleaning, assorting, and breaking the coal. Coal as it comes from the mines is of all sizes mixed together, from lumps of one ton in weight down to fine powder, and carries with it harder impurities, such as slate and rock, which generally occur in seams of coal and cannot be retained conveniently in the mine, also varying in size from minute particles to slabs weighing nearly a ton. Coal so finely broken as to pass through a screen mesh three-eighths of an inch square is usually called "dirt," and is at present largely a waste product. It occurs quite often in the seam as dirt, but is more largely produced by the crushing of the coal during the processes of mining, handling, and transporting, The purposes for which a breaker is required, are First, to separate the dirt, slate, "bone," and rock from the coal; second, to separate small coals of different sizes from each other; third, to break down such pieces as are too large into suitable sizes. And it is desirable that these requirements should be fulfilled with as little cost of handling and waste of coal as possible. At the Hammond colliery the product of the mine is raised through the slope in small cars, called wagons, which run by gravity from the head of the slope to the breaker-tips or dumps, two in number, A, A, where they are dumped and emptied in the manner shown. The empty wagons are pushed back by hand to the foot of the automatic plane B, by which they are raised to a height sufficient to allow them to return by gravity to the head of the slope. The mixed coal, slate, and dirt taken from the mine enters the "dump-shute" C, C, and reaches first the "main dump-shute bars" C', which are narrow cast-iron bars so set as to allow a space of 24 inches between each two of them. Most of the material small enough to do so passes through these bars to the dump-shute "hopper" D, from which it is fed into the counter-screens E, E, one on each side, with their supplementary screens E', E', and E2, E. All breaker-screens are circular, revolving, and slightly inclined away from the end at which the material to be screened is allowed to enter, so that whatever will not pass through the meshes descends gradually as the screen revolves to the other extremity, and drops out, They are divided into as many compartments, called "segments," as required, and covered with wire meshes of different-sized openings. The smaller mesh, being placed next to the end at which material is fed into the screen, extracts the dirt, and allows all large sizes to pass to the next segment, which extracts the next size, and so on. In the counter-screens E, E, the first segments extract the chestnut coal and all smaller sizes. The pea coal and chestnut coal are separated from the dirt in the supplementary screens E', E'. The other segments separate the large and small stove from the egg coal and larger pieces, which pass out at the ends of the screens, while the stove coals are again cleaned of smaller particles and flat slates in the supplementary screens E2, E2. The dirt from all these screens passes down the counter dirt-shute D, and is hauled away on the tramway Z, across the trestling Y, Y, to the dirt-bank in small cars called "dumpers," which may be tipped on either side. The slate and bone separated from this coal, in part by the so-called slate-picker screens, and in part by hand When it leaves the counter-screens the coal descends by its own weight along the narrow troughs F, F, called ໄ telegraphs," the hand-picking being done by men and boys at convenient places along them, and is distributed thus: the pea and chestnut to the main pea and chestnut coal screens L', L', L'; the large and small stove to the main screens L, L; and the egg and broken to the prepared-coal rollers K1. As the counter-screen material is usually wet, and the dirt adheres to it, this second screening is necessary in order to clean it properly. This completes the distri bution of that portion of the wagon's contents which passes through the 24-inch openings between the bars (which is only the smaller sizes from egg down, with such of the larger thin slabs of coal as may turn edgewise and pass through the bars. That portion of the wagon contents which passes over the bars C, C',goes to the steamboat bars Con its way down to the dump-shutes, which are set 4 inches apart. All that passes through the bars C2 goes to the bars C, set 2 inches apart, through which all below (and including) the egg coal passes to the dirt-screen E3, where the dirt is separated from it, the coal going to the prepared-coal roller K' and main screens L, L, while the dirt goes into the hopper D', and thence to Ds. In this process coal that should have passed through the bars C', but has been crowded over them, is separated in the dump-shute C, C, by bars C2, and is removed and distributed as described. That portion which passes over the bars C goes to the principal steamboat bars C, where it joins the coal from the steamboat roller K. The remainder of the wagon's contents goes down the dump-shute to the platform bars C, and contains nothing smaller than lump coal The platform bars are set 9 inches apart, and that portion which passes over them goes to the first platform H, where such of the lumps as are suitable are pushed into the lump-coal shute I, and the slate and rock into the rock-shutes I', I', on either side. Here also such of the lumps as have streaks of slate or bone through them are broken by hand and the impurities removed. All that is not suitable for lump coal is thrown down a hole in the platform to the second platform H', where it joins that which passes through the bars C. Here the slate is carefully picked out again by hand, and sent down the rock-shutes I', I', to the point I3, where it is loaded into dumpers and hauled to the dirtor rock-bank. The lump coal passes down the lumpcoal shute I, I,to the point Is, where it reaches such a level as will allow it to be loaded into the railroad-cars for market. After the slate has been removed at H, the coal is thrown down a hole in the platform to the steamboat rollers K. These rollers are cast-iron cylinders with large, strong teeth, which revolve toward each other at a speed of from 90 to 120 revolutions per minute, and the coal dropping between them is broken into pieces of various sizes. The two rollers are set so near together that none of these pieces shall be larger than steamboat coal. The coal passes from the roller K to the principal steamboat bars C, set 4 inches apart, and all that will not go through them is steamboat coal, and goes to the steamboat shute G, whence it is loaded into the railroad-cars at G1 in the same man ner as is done with the lump coal at 13, the same track answering for both. The coal which passes through This completes the distribution of all the coal. It will be observed that in all the operations advantage is taken of the elevation of the tips A, A above the railroad-tracks to cause the coal to pass from one process to the next continuously by gravity; and the elevations necessary to do this are reduced to a minimum by cov ering the shutes and traversing floors with sheet iron, which soon becomes highly polished. the steamboat bars C goes to the prepared-coal rollers screen L. The buckwheat passes through the screen K', which are similar to the steamboat rollers, except and drops from the jacket to its proper bin N', while that they have smaller teeth and are set nearer together, the dirt passes through the jacket and goes to the so that they produce no coal larger than broken. From hopper D2. these rollers the coal enters the main screens L, L, which are similar in construction to the counter-screens described above, except that they are larger. The dirt and pea and chestnut coals are taken out in the first three segments, and go together to the pea and chestnut screens L', L', L', which are double screens having a surrounding mesh outside the screen called a "jacket.' All but the chestnut coal passes through the inner screen, the chestnut dropping out at the end, and the dirt passes through the jacket, while the pea coal drops out at the end of the jacket. The dirt drops into the dirt-hopper D2, and is hauled to the dirt-banks; the pea goes to the pea-coal bins N°, and the chestnut to the chestnut-coal bins N3, without further preparation. The next segment in each main screen separates the small stove, the next the large stove, the next the egg, and the broken coal falls out at the end. All the coal but the broken passes, each size separately, over short "dusting-bars" M', set ths of an inch apart, which remove the dirt made by attrition in the screens, and thence over the picking-floors M, M, which are so inclined that the coal slides over them by gravity, each size in its own compartment. These com partments are- -M3, M3, small-stove picking compartment; M, M', large-stove picking compartment; M3, M3, egg picking compartment; M2, M2, broken picking compartment. Across the picking-floors, seats, M, M, are placed at a slight elevation, so that the boys who pick the slate sit above the coal and separate the slate from it by hand as it passes them on its way to the bins. The slate picked out by the boys is collected in the slateshutes M', M', and carried by hand to the dirt-hopper D'. The bins N, N, are divided into compartments for each size of coal, N', N', being the broken-coal bins; N', N2 the egg-coal bins; N3, N3 the large stove-coal bins; N', N the small stove-coal bins; N5,N5 the chestnut-coal bins; N, N° the pea-coal bins; N' the buckwheat-coal bin. When it is desired to load this coal into the railroad-cars, they are run down under the breaker to the gates 0, 0, communicating with each bin, the car-loaders using the platform P for convenience in walking from bin to bin. Below each of the gates O is a short set of bars, called the "lip-screens," over which the coal passes on its way into the cars, which take from each size all particles smaller than it, as well as the dirt caused by attrition in the bins. There are also similar bars at the lump and steamboat loading The machinery is all moved by the stationary engine at K, with its belt and shaft connections. The daily output is 525 tons of prepared and lump coal: 77 boys and 15 men are employed solely in separating the impurities from it. This breaker is not offered as a model filling every requirement of a breaker in the best manner now known, but simply as exemplifying the process of preparing coal for market now generally in use. The different sizes are lump, as it comes from the mines; steamboat, that which passes through bars from 4 to 7 inches apart, and over 4-inch screen-mesh; broken or grate, that which passes through 4-inch mesh, and over 2- to 23-inch mesh; egg, that which passes through 24- to 23-inch mesh, and over 2- to 2-inch mesh; large stove, that which passes through 24- to 2-inch mesh, and over 13- to 14-inch mesh; small stove, that which passes through 1- to 12-inch mesh, and over 18- to 1-inch mesh; chestnut, that which passes through 18- to 1-inch mesh, and over - to 4-inch mesh; pea, that which passes through - to -inch mesh, and over - to -inch mesh; buckwheat; dirt. These dimensions vary with the nature of the coal. The following table shows the result of passing through the monkey" or smaller rolls 2000 pounds of coal, "broken size. The experiment was made at the Kalmia colliery with coal from the Lykens Valley beds. The first two columns show the size of open ings in the screens by which the coal was separated after passing through the monkey rolls: 56.8 6.8 4.2 4.2 9.8 100.0 100'00 points, I and G. All this loading chippings" and These figures show that nearly 10 per cent. of good "dirt," as it is called, is brought to the hopper of the coal is ground into dust, and so lost, in going through elevators R, R-the lump-coal chippings by means of the breaker. the swinging trough S; the steamboat chippings by a THE WASTE OF ANTHRACITE.-The preparation of trough not seen in the drawing; and the dirt from the anthracite coal is attended by great wastage in every lip-screens at O, O by wheelbarrows. It is then all ele- stage of the operation; the loss in breaking by the vated by the elevators R, R, and carried horizontally by crude toothed rollers generally used is not less than 25 the chain-carriers T, T to the bars V. That which per cent. of the clean, merchantable coal taken from passes over the bars goes to the so-called "monkey the mines; and at many of the collieries, where softer rollers," K', which are similar to the others described and more friable coal is mined, the waste is as much as above, but smaller; while that which passes through 40 per cent. At the screens a further small percentage goes directly to the elevators R', R'. After passing of loss is sustained. When the broken coal enters the through the monkey rollers, that portion goes also to the elevators R, R, and all together are elevated to the buckwheat screen W. All but the dirt and buckwheat coal passes through this screen and goes to the main screen the angles are all sharp, but these are soon rounded by the rotary movement, and much of the coal's efficiency for rapid combustion is lost. The loss in preparing anthracite amounts to about 45 per cent, and the total |