s-lamp. The
foundation of this room is a very stiff structure, consisting of two
wrought-iron special-form girders crossing beneath it, the cross, 14
inches deep, connecting them being of steel, and forged from a single
ingot. The central boss of the cross is 22 inches in diameter, and in
this is bored out a central cavity, into which 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