principle from an ordinary twin machine.

[Illustration: BORSIG'S IMPROVED COPOUND BEAM ENGINE. FIG. 1]

The steam passes from the stop-valve, A, Fig. 4, through the steam pipe,
D, to the high pressure cylinder, C, and having done its work, goes into
the receiver, R, where it is heated. From the receiver it is led into
the low-pressure cylinder, C1, and thence into the condenser. Provision
is made for working both engines independently with direct steam when
desired, suitable gear being provided for supplying steam of the proper
pressure to the condensing engine, so that each engine shall perform
exactly the same amount of work. The starting gear consists of a
hand-wheel, H, which controls the stop valve, A, and of another h, which
opens the valves for the jackets of the cylinders and receiver. The
hand-wheel, h1 and h2, govern the valves, which turn the steam direct
into the two cylinders. There are also lever, g, which opens the
principal injection cock, H1, and the auxiliary injection cock, H2, the
function of which is to assist in forming a speedy vacuum, when the
engine has been standing for some time.

[Illustration: BORSIG'S IMPROVED COPOUND BEAM ENGINE. FIG. 2]

The drum is 6.08 m. diameter, the breadth being 2.04 m., with a total
weight of 33,000 kilos. The beams are of cast iron with balance weights
cast on. The connecting rods and cross beams are of wrought iron, and
the cranks, crank shaft, piston rods, valve rods, etc., of steel. The
bed-plate for the main shaft bearings are cast in one piece with the
standards for the beam, which are connected firmly together by the
center bearing, M M1, which is cast in one piece, and also by the
diagonal bracing piece, N N1. The construction of the cylinder and valve