much more than one half the above number of trips per day, so that the actual duty is probable from two hundred to two hundred and fifty tons of coal hauled one mile per day at a cost of four dollars and a half, the cost per ton per mile then being about two cents, and the cost of mule haulage from four to five cents, or less.

This table seems to contain some very conflicting data; thus the cost of feeding, shoeing, and attendance as given, ranges from 27 cents to $1 00 per day per mule; the cost for driving from 14 cents to 80 cents per day per mule, etc., etc.

An investigation by Messrs. Powell and Risdale, published in the School of Mines Quarterly, shows that at Drifton No. 1 colliery the cost of haulage by locomotive per ton per mile was 1.3 cents, and by mules 4.4 cents. At No. 2 colliery the cost was respectively one and three cents, the grade being more favorable.

The mine locomotive shown by Page plate No. 30 is manufactured by the Dickson Manufacturing company of Scranton. It weighs about seven tons when loaded for service, is three-foot gauge, and four feet three-inch wheel base. The cylinders are horizontal, eight inches in diameter by twelveinch stroke. Driving wheels twenty-six and a half inches in diameter, with steel tires one and three quarters inches thick. Cast centers twenty-three inches. Driving axles of hammered iron four inches in diameter.

Tubular boiler of charcoal iron, with fifty-six tubes and steel fire-box; no combustion chamber. Grate area somewhat less than five feet. Dome eighteen inches high, with safety valve, whistle, and balanced throttle.

The tank is mounted on top of the boiler and has a capacity of two hundred and twenty gallons.

This engine is rated for service, on a surface railroad, as follows:

Its performance underground will, of course, be gov erned by the condition of the road-bed. On ordinary mine roads the tonnage is not much more than half the weight that can be hauled on a surface road in average condition.

On a tolerably straight gangway road of average grade it will not be safe to estimate the average maximum efficiency at more than sixty tons.

The engine shown by Page plate No. 31 is manufactured by the Wyoming Valley Manufacturing company of Wilkes-Barre, and is in use at several collieries near that place. Its cylinders are eight by fourteen inches, horizontal, and outside connected. Weight in working order, eight to nine

tons.

Many other forms of mine locomotives have been built, and some of the older styles, of which a few still remain in use, are of unique construction. The Lehigh Coal and Navigation Company have used an engine in which the cylinders were set a steep angle of inclination in the body of the locomotive, and the power transmitted to the driving axles by cog gearing. Vertical boilers have also been used; and inside connected engines have not been uncommon.

All of these types are gradually being replaced by engines belonging to the same class with those illustrated by Plates 30 and 31. These engines have no tender; the coal is carried in a coal-box inside the cab.

The height and width of mine locomotives are, of course, governed by the size of the gangways on which they travel. The moving parts are, if possible, so placed that the water tank projects beyond them, thus affording protection from coal or rock that may fall from the gangway roof or from shutes or manways opening on the gangway. The wheelbase is, of course, governed by the gauge and curves around which the engine is to run. Mine engines as built at present are usually from five and a half to a little over six feet high.

CHAPTER XIV.

Winding Engines and Drums.

The engines in use for winding coal in the anthracite regions are usually built with horizontal cylinders and ordinary slide valves.

Steam engines of other types, the rotary, vertical, and oscillating, have been occasionally used, but the horizontal engines outnumber these ten to one.

A very large number of geared engines are in use, which are known as second and third motion engines, in contradistinction to the direct acting or first motion engines, but since the introduction of powerful double direct-acting engines, these are gradually disappearing, and at present the latter type is almost exclusively adopted at large newly opened colleries.

A general discussion of the steam engine is foreign to the objects of this report, but it is in place here to consider in detail some of the features peculiar to well-designed winding engines for colliery duty.

Since the opening, in the last few years by shaft collieries, of large areas of bituminous coal in Ohio, Indiana, Illinois, and other western States, a large number of western manufacturing firms have begun the manufacture of winding engines. These engines which are, many of them, extremely well-built steam engines seem to have been designed without reference to the fact that any good stationary engine geared to a drum may not make a good winding engine. In fact, the majority of such engines are unfit for

(227 AC.)

colliery work, and at present there are very few machine shops located at a distance from the anthracite fields turning out winding engines suitable for this class of work.

It will be understood that these statements are not intended to refer to the mechanical execution of the work, but to neglect of certain details which long and dearly bought experience in the manufacture and repair of winding engines has taught the mechanical engineers of the anthracite region, an experience as yet obtained at few localities in western coal-mining States.

The principal requirements of anthracite winding engines may be briefly stated:

1st. The engine must be thoroughly under the control of the engineer, so that it may

a, Be quickly stopped when running at full speed, and b, Be moved with certainty and nicety through a small fraction of a revolution. This is necessary in landing.

2d. It must be capable of being quickly started with full load at any part of the stroke.

3d. Must be capable of attaining full speed in two or three revolutions, (with average working load.)

4th. Great strength of every part is absolutely essential to prevent frequent breakage from the severe shocks to which winding engines are always subjected.

5th. The last object is best attained by simplicity.

6th. To facilitate repairs, every part of the engine and drum should be easily and quickly accessible.

7th. Economy in the use of steam is often the last feature considered. As the coal burnt under the boilers is usually fine coal of comparatively little value at the colliery, economy of fuel is often of not much importance, but when the water supply is very impure and often insufficient, (as is frequently the case,) economy in the use of steam is most desirable.

These being the requisites of a good winding engine, we may consider the details of construction by which they can best be fulfilled.

Valves and Valve motion.-Few mining engineers feel favorably disposed towards engines in which the steam is

used expansively. Under conditions most favorable to the use of engines of this class, the results attained cannot be considered satisfactory.

The valve gear cannot be arranged to act permanently for any considerable degree of expansion, because the engine may be required to start with full load from any point of the stroke at either the top or bottom landing, at intermediate landings, or at any point in the shaft during examinations or repairs.

Devices for bringing an independent cut-off automatically into action at a certain point in the run, are objectionable because they increase the cost and destroy the simplicity of the engine; the use of a cut-off that must be hooked up by the engineer is out of the question.

These objections to the use of an expansion valve-gear disappear when the engine is used to wind by friction gear, (as at the Cross Creek No. 2 colliery,) as the engine then runs continuously in one direction,-the speed is regulated by a governor.

The slide valve is used to the almost entire exclusion of other forms; the ports are large, and wire-drawing is especially guarded against.

The eccentrics are usually placed on the main driving shaft, which (in first motion engines being the drum shaft) is sometimes so large that the eccentrics are unwieldy and heavy, causing a considerable loss of power from friction, besides being in the way of repairs, and more or less difcult of access.

In the Pottsville shaft plant the eccentrics are carried on an independent shaft, taking motion from a reverse drag crank. Spur gearing to drive eccentric shafts is open to objection because the play of the teeth communicates a constant and injurious vibration to the valves; the noise they make is also a more or less serious objection.

Cornish valves have not been adopted,-with one exception, but in the future we shall probably see many large winding engines built with these valves. It will not be necessary to enumerate the reasons why the slide valve is not well adapted to large engines. On engines of moderate size the