can be contained in one waggon, or in two placed side by side, the carrying capacity may be increased by constructing the cage with two or more platforms, technically called decks.

As a rule, the full waggon is drawn out of the cage at the top of the shaft, and is trammed to some convenient place where it is tipped; of late years the ingenuity of American inventors has led them to introduce methods of tipping the waggon automatically on reaching the surface, without its leaving the cage, in order to save time in winding. Russell and Parson's automatic dumping cage, said to be doing good work in the United States, has its platform movable upon an axle underneath, which allows it to be tilted on one side or the other. The cage has the usual shoes at the top and bottom, which cover 5 inches of the wooden guides or conductors; the tilting platform has its own two separate shoes, which clasp only 2 inches of the guides. Whilst the cage is in the shaft, the platform is held in a horizontal position by its shoes running upon the guides. At the surface the wooden conductors are cut away for a depth of 22 inches, so that, although the cage itself is guided, the small shoes are free to move sideways and permit the tilting, when the platform touches a properly arranged stop. The flap-door of the waggon is released automatically at the same time, and the mineral is shot out into a large bin at the pit-top.

4. OTHER APPLIANCES-Keps.-On arriving at the surface the cage is usually lifted a little higher than the landing platform, and supports of some kind (keps) are brought underneath it, so as to hold it up while the full waggon is drawn off and an empty waggon pushed on. The cage is then slightly raised, the supports (keps) are drawn back by a lever, and the descent begins.

Several methods of simplifying the work have been devised, and among them is that of Messrs. Haniel and Lueg,* which has been found to act satisfactorily at the well-known Mansfeld copper mines.

The kepa, which is made of steel (Figs. 483 to 485), has an inclined face b, and is provided with two slots, one horizontal and the other d inclined. The former acts as a guide to the block e, which is loose upon the axle f; ƒ is supported by the bearing g. The pin i, surrounded by a steel roller h, can slide in the slot d; it connects the two levers k, one on each side of the kep a, which are keyed to the axle f. These are kept in a horizontal position by a lever m provided with a spring catch. The steel shoes ll, attached to the bottom of the frame of the cage, will, if desired, rest upon the inclined faces b b of the keps. As long as the lever m is held in the position shown in Fig. 483, the keps cannot open under the pressure of the load, because the pin i prevents any motion in a horizontal direction.

*

The explanation and figures are borrowed from their description.

When the lever m is being drawn back, as shown by Fig. 484, the pin i with its roller h is forced up the slot and the keps slide back on the bed-plate of the bearing g, until the cage has room enough to pass; when it has gone down, the keps are returned to

FIG. 483.

FIG. 484.

FIG. 485.

their original position (Fig. 483) by moving the lever m forwards. The ascending cage opens the keps by itself, for the shoes ll turn them upwards (Fig. 485), the lower part of the slot d being concentric to the spindle f. As soon as the cage has passed, they fall back into their normal position (Fig. 483), and the cage is lowered so as to rest upon them. The advantage claimed for keps of this kind are: Economy of steam and saving of time, besides the increased duration of the rope, which no longer has to undergo the strain of starting the cage upwards before it begins its downward journey.

Signals. It is necessary to have some means of communi

cation between the various on-setting places and the top of the shaft, so that the man at the bottom (on-setter, hooker-on) may be able to inform the man at the top (banksman, lander, or engine-man), when he is ready for the cage, skip, or kibble to be drawn up.

In shallow workings shouting is sufficient; when the pit becomes deeper a speaking-tube is sometimes put in, but the commonest method of signalling is by a cord made of seven galvanised wires, and varying in diameter from to inch. The object of the zinc coating on the wire is of course to prevent or delay rusting, which would otherwise go on rapidly in the damp atmosphere of many shafts.

The cord is carried round curves and corners by means of cranks similar to those used for house-bells, only larger and stronger, and when it is pulled by a lever at the bottom, it moves a hammer which strikes a bell at the surface. Instead of a bell, a loose plate of iron is sometimes used, which makes a very audible signal; the number of strokes indicates what is required. The usual code is as follows:

Various signals can be arranged to indicate when men are to be drawn up in place of the ordinary load of mineral; and sometimes a visible signal is combined with an audible one, a hand upon a dial recording the number of times the bell has been sounded. When persons are raised and lowered, there must also be means of signalling from the surface to the on-setting places; the object is to assure the men at the bottom that their signal has been correctly received and understood.

Electricity can also be called to the aid of the miner, and electric bells are common. Telephones* of various descriptions are some. times used, but for the ordinary purposes of winding, the simple signal given by a bell is quite sufficient.

In addition to the signal for starting and stopping, there is an indicator which shows the engine-man the exact position of the load in the shaft.

The indicator may be a dial with a hand, worked by gearing connected with the crank-shaft of the winding-engine; the various stopping places are denoted in the same way as the hours on the face of a clock, the gearing being arranged so that the hand does not travel more than the entire circumference during the longest journey of the load.

Another form of indicator is an upright standard, 6 or 8 feet in height, with a slot, in which a pointer moves up and down. It is worked by a cord, or a steel band connected to the crank-shaft. The standard has horizontal lines, numbered according to the depths of the different stopping-places; the gearing is contrived so that when the finger points to one of these lines, the cage is at the corresponding stopping-place.

The arrival of the load near the surface may be brought to the engine-man's notice in several ways: by a mark on the rope, by the pointer on the indicator, and by some audible signal, worked automatically by the winding-engine. A travelling hammer may be carried along by a screw, connected by gearing

The first time the telephone was used for transmitting speech from underground workings of a mine was in September 1877, when Mr. Arthur Le Neve Foster made some experiments at West Wheal Eliza, in Cornwall.

with the crank-shaft, and eventually brought up against a bell; it works in the same manner as the device upon typewriters which warns the operator that he is coming to the end of a line. Instead of striking a bell, the traveller may open a cock and start a steam whistle.

5. SAFETY APPLIANCES - Overwinding -In rapid winding with large drums, a slight inadvertence on the part of the engine-man may cause the load to be drawn up against the pulley, and this is what is commonly known as over-winding. In the case of a drum 18 feet in diameter, a single revolution raises the rope 56 feet; therefore, if even half a revolution is allowed beyond the proper number, an accident will ensue, unless the pulley frame gives a margin of nearly 30 feet.

There are various contrivances for preventing disasters of this FIG. 487.

FIG. 485.

kind; one method consists in interposing between the rope and the cage a special appliance, called a detaching hook, which will sever the connection between them, allow the former to be wound up, and at the same time hold up the latter safely without damage to the load or persons inside.

Some well-known detaching hooks are those of King and Humble, Walker, and Ormerod (Fig. 475).

King and Humble's consists of an outer framework of two cheeks or sides, containing two inner plates which can move about a central bolt b (Fig. 486). Each plate has a wing a, projecting beyond the framework. When in use the two plates are prevented from coming apart by a small pin or rivet, c.

If the cage attached to e is wound beyond a certain height, the detaching hook is drawn into a round hole in a strong iron plate (Fig. 487), and when the projecting wings, a a, strike against this plate, they are forced to move inwards, the

rivet is cut, the shackle d at the end of the rope is set free, and two catches ff are thrown out; these drop upon the plate and hold the cage firmly suspended.

Walker's detaching and suspending hook is like a pair of tongs, which hold the shackle at the end of the rope; the legs of the tongs are bent out, and if they are brought together the tongs open.

FIG. 488.

FIG. 489.

In Figs. 488, 489 and 490, L is the end of the winding rope, and A the shackle attached to it by the pin P. D D are the two jaws of the tongs, and F F are projecting hooks. E is the centre pin about which the jaws can move, and H an annular clamp which prevents the jaws from opening, as long as it is kept up by the two supporting pins I I. The cage or skip is hung on to the link B, and the weight of the load acting upon the two legs of the tongs tends to bring them together and open the jaws D D.

When winding is going on properly, the jaws are kept together