rect acting
screw engine should have a cock of water laid on to it, which may be
immediately opened wide should heating occur; and it is advisable to work
the engine constantly, partly with water, and partly with oil applied to
the bearings. The water and oil are mixed by the friction into a species of
soap which both cools and lubricates, and less oil moreover is used than if
water were not employed. It is proper to turn off the water some time
before the engine is stopped, so as to prevent the rusting of the bearings.

MANAGEMENT OF LOCOMOTIVES.

745. _Q._--What are the chief duties of the engine driver of a locomotive?

_A._--His first duties are those which concern the safety of the train; his
next those which concern the safety and right management of the engine and

boiler. The engine driver's first solicitude should be relative to the
observation and right interpretation of the signals; and it is only after
these demands upon his attention have been satisfied, that he can look to
the state of his engine.

746. _Q._--As regards the engine and boiler, what should his main duties
be?

_A._--The engineer of a locomotive should constantly be upon the foot board
of the engine, so that the regulator, the whistle or the reversing handle
may be used instantly, if necessary; he must see that the level of the
water in the boiler is duly maintained, and that the steam is kept at a
uniform pressure. In feeding the boilers with water, and the furnaces with
fuel, a good deal of care and some tact are necessary, as irregularity in
the production of steam will often occasion priming, even though the water
be maintained at a uniform level; and an excess of water will of itself
occasion priming, while a deficiency is a source of obvious danger. The
engine is generally furnished with three gauge cocks, and water should
always come out of the second gauge cock, and steam out of the top one when
the engine is running: but when the engine is at rest, the water in the
boiler is lower than when in motion, so that when the engine is at rest,
the water will be high enough if it just reaches to the middle gauge cock.
In all boilers which generate steam rapidly, the volume of the water is
increased by the mingled steam, and in feeding with cold water the level at
first falls; but it rises on opening the safety valve, which causes the
steam in the water to swell to a larger volume. In locomotive boilers, the
rise of the water level d