ES

ke

short-stroke engine, with balance valves and link motion; a pinion upon the crank-shaft; heavy spur-wheel, and flat winding cable.

The mines on the Comstock lode which have large hoisting works and wire cables include the Chollar-Potosi, Empire, Gould & Curry, Hale & Norcross, Imperial, Lady Bryan, Savage, and Sierra Nevada. An engine recently put up by the Risdon Iron and Locomotive Works, of San Francisco, has a 20-inch cylinder with 40-inch stroke, with 3 feet 6 inch pinion, 12-feet spur-wheel, 14-inch face by 34-inch pitch, a single winding reel for flat cable, 5 feet in diameter, sheave, or shaft pulley, 8 feet in diameter. With this it is intended to work from a depth of 2,000 feet.

HOISTING IN GUIDED CAGES.

In each of the methods described the mineral, having been taken to the shaft, is either dumped in a pile and then shoveled into the bucket or skip, or is dumped through a chute directly into the skip, and the dempty car is returned to the face. But this necessitates a rehandling of the mineral, which, when it reaches the surface, must be again dumped into a car or wagon, by which it can be delivered at the proper point away from the shaft.

These and other considerations have led to hoisting the car and load together to the month of the shaft. This effects a great saving in time, labor, and wear and tear of apparatus. It is the method adopted in the mines upon the Comstock lode, and in all well-appointed vertical shafts of any considerable depth elsewhere. To effect this, a compartment of the shaft is fitted with vertical stringers, or "guides" of wood or iron, extending from the top to the bottom, which serve to guide the movement of a platform cage, into which the car can be placed. The platform is fitted with rails of the same gauge as the track, and the car is rolled upon these and secured by bolts. The platform is a little smaller than the compartment of the shaft, and forms the bottom of a framework of iron, by which it is suspended. The frame rises above it on each side and connects with a cross-piece above the car, to which the hoisting cable is attached. The platform and the framework together form the "cage." By means of projecting ears or bars of iron or steel rubbers on each side, at the top and bottom, which partly embrace the guides, it is kept from contact with the sides of the shaft, and thus glides freely up and down. The only friction is between the rubbers and the guides, and this friction, in truly vertical shafts, is very slight. The shaft becomes, in fact, a vertical railway, and is a continuation of the tramways below, uniting them with the distributing tracks above. Tramming and hoisting thus become a connected and continuous operation. A carload of mineral is rolled to the bottom of the shaft and placed upon the platform, the signal is given to the engineman above, and the load starts upon its vertical journey.

Most of the mines at Virginia City and Gold Hill, upon the Comstock lode, and in other parts of Nevada, and the principal deep mines in California, with vertical shafts, now use the cage. It is single, large enough for one car only, but the hoisting is very rapid, from 500 to 1,200 feet per minute, (8 ft. to 20 ft. per second,) and with heavy loads weighing from 5,000 to 8,000 pounds.

The construction of the cage, as I have remarked, is very simple, being usually a square plank platform with a track, upon which the car stands, and suspended by a kind of stirrup-frame of iron at each side to an arched cross-bar of iron at the top, through the center of which the rod of suspension passes freely, and is firmly bolted just below to a

MOUN

cond iron cross-bar, free to move up and down in slots made in the ame on each side. This second cross-bar is connected at its two ends 7 arms on the outer side of the frame with the lever ends of dogamps or safety catches. The construction will be more readily underood by reference to the figure, giving a side view of the most approved

form of the cage and catch, now in use in the mines of the Comstock ode. The platform P P is five feet long and three feet eight inches wide. It is surmounted by a hood, H 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 dur ing 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 up right 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

Kilogrammes.
1, 434
128

of the

Total.....

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.

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 11⁄2 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