m of the cage and catch, now in use in the mines of the Comstock le. The platform P P is five feet long and three feet eight inches de. It is surmounted by a hood, HI H, of boiler-iron, firmly secured H. Ex. Doc. 207-37

by hinges to the top of the frame, and designed to protect the miners. from falling bodies. The height of the cage from the top of this hood to the bottom of the platform is eight feet. The ends of the rubbers are seen at R R and R' R'; the clamps, or safety catches, at C C; and the arms A A, connecting these with a cross-piece above, B' B'. A safety hook, S, for detaching the cage in case of overwinding, is placed at the top and turns in the head of the suspending rod. When the cage is at rest at the bottom of the shaft, or whenever it is not suspended by the winding cable, the cross bar B B, and cross-piece B' B', are pressed downward by a long and powerful steel plate spring, and this throws the points of the catches C C into the sides of the guide-timber, and not into the face, as is the case with Fontaine's and other safety catches. The construction of the upper part of the cage, including the spring and the suspension rod, is not shown in the side view of the cage, but will be seen in the second figure, giving a front view.

During hoisting or lowering the spring is compressed, and this serves to relieve the cage and load from the shock which attends a sudden commencement of hoisting.

The hand-lever just above the platform controls iron rods which rise through the floor of the cage and hold the cars securely in place during the ascent and descent of the cage.

The whole construction is light and simple, and has given general satisfaction. It is not closed in at the top and sides as closely as in the foreign mining cages, and is high enough to allow miners to stand upright as they ascend and descend. The hood is hinged to prevent the imprisonment of miners in case of accident, or drowning, if, as some times happens, the cage is lowered into water.

EUROPEAN GUIDED CAGES.

In Europe cages are made in a much more substantial and cumbrous manner, and they are generally arranged to receive several cars, either one above another upon separate platforms or, when the shaft is wide enough, two or three abreast. At Mons, in shaft No. 12 of Grand Hornu, eight wagons have been put into one cage of four stories. When the wagons are large, as, for example, those of twelve hectolitres at Blanzy, the cages are only two stories high.

They are usually made of iron, on account of both lightness and strength; and the angle irons and T-irons are found to be well adapted to the purpose. The cage of four stories was the form in use a few years since at Anzin. It is made of angle iron, strongly riveted, and weighs as follows:

This cage will carry 2,000 kilogrammes of coal in the four wagons, which themselves weigh 720 kilogrammes, thus making the dead weight as much as 1,845 kilogrammes.

The cage used at Charleroi holds four wagons, like those at Anzin;

but they are here placed end to end upon two floors only, and the cage weighs 900, the four wagons 780, and the charge 1,600 kilogrammes.

At the Paris Exposition of 1867 Nicholas Libotte, constructor, of Silly, near Charleroi, exhibited some cages intended for the collieries of Charleroi, Belgium. These cages are remarkable for their extreme lightness and strength, and for the perfection of the forging. They are made of steel, are intended for a narrow shaft, and are capable of taking six wagons, one above another. The cage weighed as follows:

Cage...
Parachute

Total.....

Kilogrammes.

1, 434
128

1,562

Another cage, similarly constructed, was made in two stages only, but was also designed to receive six wagons, three on each stage:

Weight of cage
Weight of parachute

Total

This cage was made for a shaft near Liege, Belgium.

Kilogrammes.

1,268

164

1,432

In order to diminish the shock which results from the sudden descent of a cage upon the platform at the bottom of a shaft, especially when the cage is used for the descent of miners, caoutchouc springs have been placed under a false platform or landing, so as to prevent violent concussions when the motion of the cage is not sufficiently arrested in season to avoid a shock. So also, in order to avoid the sudden shock at the commencement of hoisting, spiral springs have been placed between the end of the cable and the top of the cage, so that the spring would be compressed before the cage began to move. But such springs require to be very strong and heavy to be of any service where such great weights are to be lifted; and this has led to the plan of placing large steel plate springs under the axle bearings of the great pulleys at the top of the shaft. But it is also desirable to have an elastic form of attachment to the cages; and this is secured to a certain extent by the use of the safety-catch, which requires a spring.

CABLES, WIRE ROPE, WINDING DRUMS, &c.

The leading mines upon the Comstock lode extend from 1,000 to 1,300 feet below the surface. In nearly every one the companies have changed their hoisting works several times, increasing their power and improving their construction to suit the increased duty of winding from constantly augmenting depths. Hemp cables have given way in part to round wire ropes, and these in turn to flat wire cables, some of them made of steel wire. The dimensions of these flat cables are 3 by inch to 6 by 13 inches for iron, and 2 by inch to 4 by inch for steel. The length is usually 1,500 feet.

The manufacture of wire cordage and flat winding cables for mines is carried on in San Francisco upon an extensive scale at the works of A. S. Hallidie, erected in 1857. Their capacity of production is now over 1,200 tons of rope and cable annually. Their manufactures embrace

every description of wire cordage, from the delicate bell and signal cord to those of a single piece 3,000 feet long and weighing nearly 40,000 pounds. Most of the hoisting works upon the Comstock lode have been supplied with winding cables from this establishment.

This firm has recently made a cable for the Imperial mine 1,600 feet long, 6 inches wide, and inch thick, weighing 8,400 pounds. This cable is wound upon a 6-foot drum, but as generally several layers of the cable remain on the drum, not being unwound, the diameter is increased to 6 to 7 feet. The sheaves for flat cables are usually only 7 feet in diameter, but this is too small; they should not be less than 12 feet.

DIAMETER OF WINDING DRUMS.

It is a common defect in all the hoisting works of California and Nevada that the winding drums and pulleys are too small. In Europe the diameter of winding drums has been greatly increased, and there are many examples of drums 20 feet in diameter. At the Casimir Perier colliery at Somain the round wire rope is used upon a drum with a diameter of 7.14, or 25 feet. Twenty-five turns of this drum winds up 600 metres of cable. The weight of cable is four kilograms per metre. These large drums are particularly desirable for wire ropes, which are destroyed very fast by a short bend. On these large cirumferences the turns are fewer, and the cable need not be coiled several times over itself, which causes great wear and destruction of the strands. Each turn of a drum 22 feet in diameter represents 66 feet of length of cable, and 25 rounds will reach 1,650 feet deep. With a rope one and a half inch thick the drum would have to be a little over three feet in length. In such a case the radius of the drum in winding would remain the same when wire rope is used; but this is not the case with hemp rope, which has a much greater diameter, and when winding up around the drum it must coil upon itself several times, and thus increase considerably the radius of the drum, and, on the other hand, in unwinding or lowering into the shaft the radius of the drum is rapidly reduced.

The difference of radius is insufficient to compensate for the weight of the unwound cable, and such an arrangement requires powerful engines to lift up the dead weight of cable at the start. From that moment less and less power is required until the two buckets or cages meet in the shaft; then the descending cable gradually takes the advantage of the ascending one, and the steam-engine, instead of driving, is soon driven with an increased velocity by the increasing weight of the descending cable. To avoid these inconveniences a system of counterpoises is used. Ropes carrying a counterpoise are wound around sheaves placed on the shaft of the drum; these counterpoises play up and down the shaft for about fifty or sixty metres; the cable unrolls as it goes down, and the radius of the sheaves diminishes. It is so arranged that when the entire cable is paid out and the counterpoise is down the two buckets or cages pass each other in the shaft. At that time the strain upon the hoisting drum changes, as also the action of the counterpoise. The rotary motion of the hoisting drum continues in the same direction, as also that of the sheave, which now winds up the rope of the counterpoise in the opposite direction. The force required to raise up this counterpoise counterbalances the weight of the descending cable. Another way, which gives better results, consists in using a very heavy cast-iron chain as a counterpoise.

M. Quillacq, a Belgian engineer, after having visited the hoisting