w.

740. _Q._--Will the unbroken engine, in the case of disarrangement of one
of the two engines of a screw or paddle vessel, be able of itself to turn
the centre?

_A._--It will sometimes happen, when there is much lead upon the slide
valve, that the single engine, on being started, cannot be got to turn the
centre if there be a strong opposing wind and sea; the piston going up to
near the end of the stroke, and then coming down again without the crank
being able to turn the centre. In such cases, it will be necessary to turn
the vessel's head sufficiently from the wind to enable some sail to be set;
and if once there is weigh got upon the vessel the engine will begin to
work properly, and will continue to do so though the vessel be put head to
wind as before.

741. _Q._--What should be done if a crack shows itself in any of the shafts
or cranks?

_A._--If the shafts or cranks crack, the engine may nevertheless be worked
with moderate pressure to bring the vessel into port; but if the crack be
very bad, it will be expedient to fit strong blocks of wood under the ends
of the side levers, or other suitable part, to prevent the cylinder bottom
or cover from being knocked out, should the damaged part give way. The same
remark is applicable when flaws are discovered in any of the main parts of
the engine, whether they be malleable or cast iron; but they must be
carefully watched, so that the engines may be stopped if the crack is
extending further. Should fracture occur, the first thing obviously to be
done is to throw the engines out of gear; and should there be much weigh on
the vessel, the steam should at once be thrown on the reverse side of the
piston, so as to counteract the pressure of the paddle wheel.

742. _Q._--Have you any information to offer relative to the lubrication of
engine bearings?

_A._--A very useful species of oil cup is now employed in a number of steam
vessels, and which, it is said, accomplishes a considerable saving of oil,
at the same time that it more effectually lubricates the bearings. A
ratchet wheel is fixed upon a little shaft which passes through the side of
the oil cup, and is put into slow revolution by a pendulum attached to its
outside and in revolving it lifts up little buckets of oil and empties them
down a funnel upon the centre of the bearing. Instead of buckets a few
short pieces of wire are sometimes hung on the internal revolving wheel,
the drops of oil which adhere on ri