the head of the steel ram, 18 inches in diameter, is fitted; the ram itself being built up of steel cylinders or tubes, 11 feet 3 inches in length, which are connected together by internal screws.  There is also a central rod within the ram, as an additional security.  The ram descends into a very strong cast-iron cylinder, 21 inches internal diameter, which is suspended in a boring 40 inches internal diameter, and carried down to a depth of over 100 feet in the rock.  The two iron girders under the frame of the ascending-room or cage cross the entire lift space, and then at their outer ends are attached to four chains which rise over pulleys fixed about 12 feet above the floor of the upper booking-office.  These chains thence descend to suspend two heavy counterweights, so arranged as to work in guides and to pass the ascending-room in the 12 inch interspace between the cage and the side walls of the shaft.  These chains are of 1-1/8 inch bar iron, and have each been tested with a load of over 15 tons.  The maximum load which can ever come as a strain upon any chain is about three tons.  Two chains are attached to each counter-weight, and special attention has been paid to the attachments of these chains to the cage girders.  The stroke of each hydraulic lift is 96 feet 7 inches.  In the engine-room there are three marine boilers, each 6 feet 6 inches diameter and 11 feet 6 inches long, and three pairs of pumping engines of patented type, each capable of raising thirty thousand gallons of water per hour from the waste tanks below the engine-room to the top tank of the tower above ground.  There are three suction and three delivery mains, and these are connected direct to the lifts by a series of change sluices, admirably, neatly, and handily arranged in the engine-room by Mr. Rich, and in such a way that any engine, any lift, or any supply main can be disconnected without interference with the rest of the system.  When the tower tank is completed, it alone, under any circumstances, would be able to supply the lifts if every pumping engine were stopped.  But if any or all the engines were working, they would automatically assist the top tank, for nominally they will keep the top tank exactly full, and will then stop of themselves.  The tower, as we have indicated, is not yet completed, and the pumping engines are consequently doing all the work of the lifts.  The ascent and descent of the cages is effected by the attendant who accompanies the passengers, by means of a rope arrangement.

Each cage or room is intended ordinarily to take a maximum freight of 100 passengers, calculated at about 15,000 lb.  The hydraulic ram weighs about 11,000 lb., the iron frame and cross of the cage about 6,500 lb., and the cage itself about 13,200 lb., the total being about 30,700 lb.  The mass in motion when a cage is fully loaded is estimated at 63,000 lb. dead weight.  The journey of elevation will ordinarily be made within one minute, but in the experimental