ics be occasionally looked at to see that they have not shifted on
their axles, though this defect will be generally intimated by the
irregular beating of the engines. The tubes should also be examined and
cleaned out, and the ashes emptied out of the smoke box through the small
ash door at the end. If the engine be a six-wheeled one, with the driving
wheels in the middle, it will be liable to pitch, and oscillate if too much
weight be thrown upon the driving wheels; and where such faults are found
to exist, the weight upon the drivings wheels should be diminished. The
practice of blowing off the boiler by the steam, as is always done in
marine boilers, should not be permitted as a general rule in locomotive
boilers, when the tubes are of brass and the fire box of copper; but when
the tubes and fire boxes are of iron, there will not be an equal risk of
injury. Before starting on a journey, the engine man should take a summary
glance beneath the engine--but before doing so he ought to assure himself
that no other engine is coming up at the time. The regulator, when the
engine is standing, should be closed and locked, and the eccentric rod be
fixed out of gear, and the tender break screwed down; the cocks of the oil
vessels should at the same time be shut, but should all be opened a short
time before the train starts.

753. _Q._--What should be done if a tube bursts in the boiler?

_A._--When a tube bursts, a wooden or iron plug must be driven into each
end of it, and if the water or steam be rushing out so fiercely that the
exact position of the imperfection cannot be discovered, it will be
advisable to diminish the pressure by increasing the supply of feed water.
Should the leak be so great that the level of the water in the boiler
cannot be maintained, it will be expedient to drop the bars and quench the
fire, so as to preserve the tubes and fire box from injury.

754. _Q._--If any of the working parts of a locomotive break or become
deranged, what should be done?

_A._--Should the piston rod or connecting rod break, or the cutters fall
out or be clipped off--as sometimes happens to the piston cutter when the
engine is suddenly reversed upon a heavy train--the parts should be
disconnected, if the connection cannot be restored, so as to enable one
engine to work; and of course the valve of the faulty engine must be kept
closed. If one engine has not power enough to enable the train to proceed
with the blast pipe full