e safety valve and steam gauge should be checked
daily. In small plants the steam pressure should be raised sufficiently
to cause the safety valves to blow, at which time the steam gauge should
indicate the pressure at which the valve is known to be set. If it does
not, one is in error and the gauge should be compared with one of known
accuracy and any error at once rectified.

In large plants such a method of checking would result in losses too
great to be allowed. Here the gauges and valves are ordinarily checked
at the time a boiler is cut out, the valves being assured of not
sticking by daily instantaneous opening through manipulation by hand of
the valve lever. The daily blowing of the safety valve acts not only as
a check on the gauge but insures the valve against sticking.

The water column should be blown down thoroughly at least once on every
shift and the height of water indicated by the glass checked by the
gauge cocks. The bottom blow-offs should be kept tight. These should be
opened at least once daily to blow from the mud drum any sediment that
may have collected and to reduce the concentration. The amount of
blowing down and the frequency is, of course, determined by the nature
of the feed water used.

In case of low water, resulting either from carelessness or from some
unforeseen condition of operation, the essential object to be obtained
is the extinguishing of the fire in the quickest possible manner. Where
practicable, this is best accomplished by the playing of a heavy stream
of water from a hose on the fire. Another method, perhaps not so
efficient, but more generally recommended, is the covering of the fire
with wet ashes or fresh fuel. A boiler so treated should be cut out of
line after such an occurrence and a thorough inspection made to
ascertain what damage, if any, has been done before it is again placed
in service.

The efficiency and capacity depend to an extent very much greater than
is ordinarily realized upon the cleanliness of the heating surfaces,
both externally and internally, and too much stress cannot be put upon
the necessity for systematic cleaning as a regular feature in the plant
operation.

The outer surfaces of the tubes should be blown free from soot at
regular intervals, the frequency of such cleaning periods being
dependent upon the class of fuel used. The most efficient way of blowing
soot from the tubes is by means of a steam lance with which all parts of
the surfa