tem, but it is unfortunately not well adapted to beds dipping more than thirty-five degrees.

The long-wall system is not adapted to thick steep-pitching beds, it is best adapted to the conditions from which the best results are now obtained in the ordinary pillar and breast workings.

Coal lost by becoming mixed with refuse and left in the mine (on moderate dips) is lost only because it would cost more than the coal is worth to separate it from the refuse. A discussion of this subject is unnecessary.

Much of the coal now lost by adhering to lumps of slate and other refuse rejected by the miner or at the breaker could be saved, but we cannot expect any operator to spend two or three dollars' worth of labor to save a ton of coal worth two dollars or less.

Waste made by blasting cannot well be decreased. At some collieries it might be somewhat diminished by limiting the amount of powder charged into a hole of a certain depth.

A certain percentage of fine coal must always be made by sliding the coal down shutes from the working place to the gangway. In loading the coal into cars and transporting it to the breaker, the amount of waste made varies with the softness or brittleness of the coal. In steep pitching beds this waste may be reduced to a minimum by drawing all the coal from the main shutes,-sending none down the manway, or by keeping the manway (which then becomes only a shute) constantly full of coal.

As this latter plan cannot always be adopted with satisfactory results, the former method is often used.

We now come to a consideration of the means by which the breaker waste may be reduced.

It is evident at first sight that the coal should be moved in shutes, elevators, screens, etc., no further than is absolutely necessary to properly size and prepare the coal. This subject has already received attention in the preceding chapter,

but I wish here to refer briefly to the use of very long screens. The percentage of waste always increases with the length of the screen, and while to insure proper sizing of the coal, long screens may be necessary with some varieties of coal, I am satisfied that good results might often be obtained with shorter screens. It also seems probable that the use of spiral screens might be feasible in some cases, and in others the larger sizes might be separated with less waste by double-jacked screens. However, as the amount of waste made by the screens is comparatively small, this is a matter of much less importance than the style of the rolls, their speed, etc.

It is a well demonstrated fact that the improved style of rolls with steel teeth, running at high speed, have effected a marked reduction in the percentage of breaker waste, and while we still look for further improvements in this direction, it is a matter of regret that the improvements already made have not been adopted at all anthracite collieries.

The waste made in loading the railway cars cannot well be avoided. I think the waste made by jarring during transportation is comparatively small,-probably much less than the waste made in loading and emptying the cars.

Utilization of Waste.

Of the total coal contained in the ground, I have estimated (see a preceding page) that

8 per cent. of waste is made by blasting and by hand

6.4

14.4

ling the coal; and that

is made by breaking and preparing the coal in the breaker, making

of coal wasted by being broken into fine dust or dirt, (culm.) This fuel is waste, because it is in too fine a state to allow an ordinary draught to pass through it a sufficient quantity of air to support active combustion, and a strong (pressure) draught cannot be used, because it lifts the fire from the grate, and carries a large portion up the smoke stack.

Several plans for utilizing anthracite dust have been tried, with more or less success. With one exception they all