Never blow out the boiler under high steam pressure or fill it again
with cold water when the boiler is hot, as either one of these is
likely to fracture the transverse riveting and is dangerous.
Do not feed the water to the boiler irregularly. The slower the water
goes through the heater the more heat it takes up. To fill the boiler
to three gauges and then shut off the feed until the water level is
again down, the exhaust steam, after it has heated the water standing
in heater, passes off without leaving any of its heat, and then turning
on the feed water again much faster than needed, the water has not time
to take up so much heat as if the feed were slow and regular. Much bad
effect on the boiler is due to the difference in temperature at the
time when the feed is off and on.
_Never calk a boiler under steam pressure unless you are tired of
life._