=Cylinder Cocks= are used in connection with the cylinder to allow the
water accumulated by the condensing of steam in the cylinder to escape,
and should be opened every time the engine is started or stopped.
This should never be neglected, as great damage may be caused by the
breaking of the follower plate or cylinder head. They should also be
left open when engine is shut down, and at night in cold weather to
prevent freezing and the consequent damage.
[Illustration: Lunkenheimer Cylinder Cock.]