Previous to the year 1844 these breakers were unknown. Several experiments had been made in the matter of breaking coal by machinery, but there had been no practical results, and the breaking still continued to be done by hand. In that year, however, a breaker after the modern plan was erected at the mines of Gideon Bast, in Schuylkill County, by J. & S. Battin of Philadelphia. It was started on the 28th of February, 1844. There were two cast-iron rollers in it, each about thirty inches long and thirty inches in diameter, and on the surface of these rollers were set iron teeth or projections about two and one half inches long and four inches from centre to centre. These rollers were placed horizontally, side by side, and were so geared that, as they revolved, their upper surfaces turned toward each other, and the teeth on one roller were opposite to the spaces on the other. These rolls were afterward improved by being perforated between the teeth, thus presenting less of solid surface to the coal, and causing less crushing. Another set of rollers was afterward added, being placed above the first set, and having the teeth larger and wider apart, so that large lumps of coal might first be broken into pieces small enough to be crushed readily by the lower set. After the perfecting of the rolls came the perfecting of the screens for the purpose of separating the broken coal into grades according to size. Before the introduction of coal breakers a hand screen was used. This screen was set in a frame, was cylindrical in form, and was slightly inclined from the horizontal. It was turned by a crank at one end, in the manner of a grindstone. The screen placed in the breaker was of much the same pattern, except that instead of being from five to eight feet long the length was increased to twenty feet, and the diameter correspondingly enlarged. Mr. Henry Jenkins of Pottsville then invented a method of weaving thick wire into screen plates about three feet wide, having the proper curve. These curved plates being joined together formed the necessary hollow cylinder. These separate plates are called jackets, and when one of them wears out it may be taken from the cylinder and replaced, with but little trouble and delay. The screen is set in heavy framework, and is inclined slightly from the horizontal. The first segment at the upper end of the screen is made of wire woven into a mesh so fine that only the smallest particles of coal will pass through it; the mesh of the next segment is larger, and that of the next larger still. The screen may contain from two to five segments in its length. Now the coal, being poured in on top of the revolving rolls, comes out from under them broken into small pieces, and passes immediately into the upper or highest end of the hollow cylindrical screen as it would pass into a barrel. But, as the screen revolves on its axis, the finer particles of coal fall out through the fine mesh of the first segment,