the percentage of large sizes (lump, steamboat, and broken) sent to market, etc., etc.

While at a few collieries coal is sometimes prepared at a cost of eight or ten cents a ton, the average cost is probably between fifteen and twenty cents. At some collieries the cost is very much in excess of these figures, but I have not been able to obtain figures showing the cost of preparing wet dirty coal for domestic use.

I have not been able to obtain the percentages of different sizes shipped from the whole region.

At some collieries all the coal is broken down and shipped for domestic use in sizes smaller than steamboat; at others 40 or 50 per cent. or more of the output is shipped as lump, (for furnace use, etc.,) and eight or ten per cent. shipped as steamboat for manufacturing and other purposes.

CHAPTER XXVII.

The Anthracite Coal Breaker.

The term "coal breaker" was at first applied to the rolls or crushers (jaws) by which the coal was broken or crushed down to small sizes. These crushers or rolls were commonly located in a structure containing the screens and other machinery for separating and cleaning the coal, and in a short time these structures received the name applied at first to the crusher or rolls; so that the term "Breaker," "Coal Breaker," or "Anthracite Breaker" is a name now given to the structure containing the crushing, separating, and preparing appliances, and is sometimes also understood to in clude these appliances,-in the same way that we commonly use the term "mill" (flour-mill, woolen mill) to include both the structure and machinery.-but the term "breaker" is now never applied to the rolls by which the coal is broken. These latter are called "rolls" or "crushers."

Two very different styles of breaker are shown by Atlas plates Nos. XVI and XVIII; breakers in process of con

struction by Page plates Nos. 45 and 46, and finished structures (in perspective) by Page plates Nos. 43 and 44.

The height of a breaker is necessarily governed by the method of preparation. It is always desirable to handle the coal entirely by gravity, by allowing it to slide down shutes from each set of bars, or rolls, or screen, etc., until it reaches the pockets; but when the coal is very dirty, the method of preparation is so complex that to handle the coal in this way would require structures of inordinate height. Thus at the Lehigh Coal and Navigation Company's Breaker No. 10 one part of the coal passes through the following appliances:

Bars 5", shute, bars 3", shute, mud screen, shute, jigs, shute, small monkey rolls, shute, elevator, main screen, shute, jigs, shute, picking table, shute, pocket.

Under such circumstances an elevator is commonly used to raise the coal to the main screen, which is placed at sufficient height to allow the coal to run by gravity through the shutes, etc., to the loading pockets; but when the coal is dry, or when it comes from a colliery opened on dips less than thirty or thirty-five degrees, the method of prepa ration is more simple and elevators are not often necessary.

Anthracite breakers as built at present range from sixty to one hundred and fifteen feet in height; large breakers are seldom less than eighty feet high.

The necessary height is estimated from the level of the railway track on which the coal is loaded. The base of the coal pockets must be from nine to twelve feet or more above the track, so that the loading apron will project nearly over the center of the car when at an angle of twenty-five or thirty degrees, and will still be about one to two feet above the top of the car.

The pockets are made hopper (V) shaped with a slope of from twenty to thirty degrees so that they can be readily emptied. Their depth depends on the capacity of the breaker and its width, the facility for obtaining a regular supply of railway cars, etc., varying from ten to twenty feet or more.

The shutes through which the coal runs in passing through