The first trial of the machine was made at a pit belonging to the North Staffordshire Coal and Iron Company, (Limited,) at Talke-o'-th'-Hill, in a heading in what is called the Eight-feet Banbury seam of coal, at a depth of 359 yards from the surface, and under ordinary working circumstances, so far as the place selected was concerned. Considerable difficulty is always found in fairly testing a machine under such circumstances as these, but, notwithstanding every disadvantage, the hole for the machine was drilled and about 4 tons of coal brought down in 25 minutes. Mr. Higson asked a workman in charge of the place how long it would have taken him to have drilled the hole and fired the shot according to the present system of blasting, and he considered that an hour would be required for the purpose, and a pound of gunpowder used, at a cost of 5d. The superiority of the machine was, therefore, evidenced by the saving of 35 minutes in time and 5d., the cost of powder, and the work was done without the smallest danger to any one. Two further trials of the machine were made in other parts of the workings, in both the Seven and Eight-feet seams, with results equally satisfactory. The mode of using the machine in the working of coal would be to provide each set of colliers with a pair of steel tension straps, and the machine could easily be carried about by a man like a double-barrelled gun under his arm from place to place. It would thus be necessary to have only one press for a large number of these places; the entire cost of the machinery is very small.

SECTION III-TRANSPORTATION, VENTILA

TION, ETC.

CHAPTER LXXI.

TRAMWAYS AND WAGONS.

As mines increase in depth and extent, the cost of sinking and maintaining shafts is much increased, and it is no longer economically possible to keep several hoisting-shafts in operation. It is therefore necessary to confine the hoisting to one central shaft, which thus becomes the only outlet of a constantly extending system of underground tramways, over which the minerals or débris are conveyed to the shaft in order that they may be raised to the surface. As the work of extraction of the ore or coal progresses, the distance of the mineral from the shaft, especially in collieries, is constantly increasing, being in some of the European collieries as much as 4,500 feet or more, and it is thus become a very important item in the expense of mining to move the mineral to the shaft. So, also, when, as is common in California and Nevada, veins are reached by long tunnels, the tramming or underground transportation forms a serious item of the cost of getting the mineral to the surface, and it is important to determine the best forms and sizes of the wagons and tracks to be used.

TRAMMING AND TRAM WAGONS IN CALIFORNIA.

Very little attention has been given in the mines of the west to this subject of tramming. The forms of wagons, or "cars," as they are usually called, are almost as numerous as the mines in which they are used. In general, they are made of wood (there are some of iron) banded with iron, and are supported upon small cast-iron wheels, running upon axles of the simplest form. The size varies with the size of the tunnels, but is never larger than a man can manage with ease when loaded, except when, as at the Mount Diablo coal mines in California, horses are employed for the haulage. These coal mines perhaps present the best examples of underground tramming upon the Pacific slope.

The average distance of underground hauling at these coal mines, is now perhaps not far from one-third of a mile. This distance varies, of course, in the different mines, and in different parts of the same mine. The maximum distance of underground haulage is in the old or upper Black Diamond gangway, which, from its face to the mouth of the tunnel, is now about 4,200 feet. This tunnel is about 400 feet long, before reaching the coal, and extends for the remainder of the distance on the coal and is constantly being worked further. The haulage upon the horizontal tramways is done by horses at an average cost of not less than fifteen cents, and probably as great as twenty cents, per ton per mile.

The sizes of cars, tracks, &c., vary considerably in the different mines, but the tracks are all alike in their construction, being made by spiking a tight strap-iron rail upon wooden stringers supported on wood cross-ties. A light I-rail would be a decided improvement. The cars at most of the

mines have to be made so that they can be used not only on a horizontal roadway, but also upon an incline. They are therefore built higher behind thanin front, in order to prevent the coal from falling back out of the full cars as they ascend the slope. At the Mount Hope slope, leading to the lowest level of the Black Diamond mines, and pitching at an angle of 37° 15' to the south, the cars, built of wood and sometimes of sheet. iron, have the following interior dimensions: Length, 6 feet 6 inches; width, 2 feet 5 inches; depth in front, 2 feet 5 inches; depth at rear end, 2 feet 11 inches. The width of track is about 36 inches. These cars hold about a ton of coal and they are drawn up the slope by a steam winding engine. Some details concerning this hoisting will be given beyond.

TRAMMING UPON THE COMSTOCK LODE.

The annexed figure, drawn to one-twentieth of the full size, shows the construction of a dumping car, made of wood, designed to run equally well on a horizontal track, upon a steep incline, or upon the surface. It is

the form used some

years since at the Ophir mine, on the Comstock lode. The body of the car is sup ported a little forward of its center upon the extreme end of a strong frame which turns upon a central pivot and rests upon a lower frame or truck, carrying the low wheels. This arrangement for turning the car upon a pivot allows its load to be dumped on either side of the raised track at the dump-pile of ore, or at the attle-heap. The forward end is closed by a flap-door opening outward, suspended on an iron rod, extending from one side of the car to the other. The back end of the car and half its length on top are closed with planks, secured by strong iron straps.

Dumping Car for inclined shaft or gallery.

UNDERGROUND TRAMMING ABROAD.

The next figure represents the tunnel car used at Freiberg, Saxony,

The load is sustained upon the axles by a on timber extending longitudinally in the center, To under the car.

The wheels are of good size, and the outer of ends of their axles are supported by the heavy

dado iron bands depending from the side of the box.

The next figure will recall to the minds of

the Freiberg mines the "hund," or dog, so commonly employed in that district. It is of wood, bound with iron, and

DE.

only on air

built higie ng back ope slope witching Sometimes th. 6 feet: es: depti

36 inches up the s

shoisting

constructed of such a size as to be managed, when loaded, by a single
man. The axles are fixed, and the car is turned, when necessary, by
tilting it so as to lift the forward
axle and leave the weight resting
on the two larger wheels only.
These dogs are particularly useful
in mines where tracks have not
been laid. Their broad wheels ena-
ble them to go through ordinary
galleries, or over the inequalities of
the surface. They are generally,
however, run on strips of boards,
or ways otherwise prepared, to
diminish the labor of the miners
propelling them.

The rapidly increasing production of the coal mines of Great Britain and the Continent has necessitated great improvements in the methods of transportation underground. The wagons used for the purpose and their running gear are no longer roughly and rudely constructed, but are made with great care. The wheels are accurately made, well bored, and fitted with carefully turned axles, and these are kept well lubricated by grease-boxes, so as to prevent loss of power, wear, and friction.

In France and Belgium a few years since a plain flat rail, set on edge and tightly wedged into the cross-ties or chairs, was preferred to any other. The size of the iron depended upon the weight to be sustained. For cars carrying 500 kilogrammes, 0.055 by 0.011 was sufficient; but if the track was to be used for a long time, heavier iron was preferred. The width of track was, and is, in general, from 0m.60 to 0m.80. At the Blanzy collieries, where the cars carry about 1,000 kilogrammes, (one ton,) the width is 0m.80, and the flat-bar rails measure 0m.07 by 0m.02.

At the Anzin collieries it is found advantageous to use iron cross-ties, with chairs welded or riveted to the ends, in preference to cross-ties of wood. Rails with a rounded summit, and thicker at the base than the top, were in use there in preference to the square-edged rail, but these have in turn given place to a light I-rail. It was calculated by Burat in 1861 that the tramways at Anzin, 0m.60 wide, and with cross-ties of iron at distances of Om.80, did not cost over five francs per lineal metre. But great improvements have been made since that time, and in the Supplément au Matériel des Houillères, Professor Burat states that the conclusions arrived at, after very careful investigations of the methods, are: 1. That the narrow-gauge tracks, those, for example, of 0.50, are the most desirable. 2. That the flat rails and bar rails on edge should be abandoned for rails presenting at least two centimetres of bearing surface to the wheels. 3. That the charges for the cars should not be greater than 400 kilogrammes, net weight, in order that the attendant may easily turn the car on curves of short radius, or put it upon the track in case of its running off. Light I-rails are in use in some of the collieries, as well as the method of oiling known as Evrard's, by means of an oil-box placed in a hollow axle.

SELF-LUBRICATING AXLES.

Evrard's contrivance is described in the reports upon the Paris Exposition. It is designed to supply oil in moderate and regular quantities to the journals or bearings of the wheels of wagons for underground tramming,