first-class separators in connection with a suitable
draining system, such as the Holly system which returns the moisture
separated from the steam, back to the boilers, a high degree of quality
may be obtained at the turbine with practically no extra expense during
operation. Frequent attention should be given the separators and traps
to insure their proper operation. The quality of the steam may be
determined from time to time by the use of a throttling calorimeter. Dry
steam, to a great extent, depends upon the good and judicious design of
steam piping.

Superheated steam is of great value where it can be produced
economically, as even a slight degree insures the benefits to be derived
from the use of dry steam. The higher superheats have been found to
increase the economy to a considerable extent.

When superheat of a high degree (100 degrees Fahrenheit or above) is
used special care must be exercised to prevent a sudden rise of the
superheat of any amount. The greatest source of trouble in this respect
is when a sudden demand is made for a large increase in the amount of
steam used by the engine, as when the turbine is started up and the
superheater has been in operation for some time before, the full load is
suddenly thrown on. It will be readily seen that with the turbine
running light and the superheater operating, there is a very small
amount of steam passing through; in fact, practically none, and this may
become very highly heated in the superheater, but loses nearly all its
superheat in passing slowly to the turbine; then, when a sudden demand
is made, this very high temperature steam is drawn into the turbine.
This may usually be guarded against where a separately fired superheater
is used, by keeping the fire low until the load comes on, or, in the
case where the superheater is part of the boiler, by either not starting
up the superheater until after load comes on, or else keeping the
superheat down by mixing saturated steam with that which has been
superheated. After the plant has been started up there is little danger
from this source, but such precautions should be taken as seem best in
the particular cases.

Taking up the exhaust end of the turbine, we have a much more striking
departure from the conditions familiar in the reciprocating engine. Due
to the limits imposed upon the volume of the cylinder of the engine, any
increase in the vacuum over 23 or 24 inches, in the case, for instance,
of a com