eam consumption. The ordinary steam gland is in
reality a pressure gland. At both ends of the turbine casing is an
annular chamber, surrounding the turbine spindle at the point where it
projects through the casing. A number of brass rings on either side of
this chamber encircle the spindle, with only a very fine running
clearance between the latter and themselves. Steam enters the gland
chamber at a slight pressure, and, when a vacuum exists inside the
turbine casing, tends to flow inward. The pressure, however, inside the
gland is increased until it exceeds that of the atmosphere outside, and
by maintaining it at this pressure it is obvious that no air can
possibly enter the turbine through the glands, to destroy the vacuum.
The above principle must be borne in mind during a test upon a turbine
having steam-fed glands. Perhaps the best course to follow--in view of
the economy of gland steam consumption necessary--is as follows:

During the preliminary non-test run, full steam is turned into both
glands while the vacuum is being raised, and maintained until full load
has been on the turbine for some little time. The vacuum will by this
time have probably reached its maximum, and perhaps fallen to a point
slightly lower, at which hight it may be expected to remain, other
conditions also remaining constant. The gland steam must now be
gradually turned off until the amount of steam vapor issuing from the
glands is almost imperceptible. This should not lower the vacuum in the
slightest degree. By gradual degrees the gland steam can be still
farther cut down, until no steam vapor at all can be discerned issuing
from the gland boxes. This reduction should be continued until a point
is reached at which the vacuum is affected, when it must be stopped and
the amount of steam flowing to the gland again increased very slightly,
just enough to bring the vacuum again to its original hight. The steam
now passing into the glands is the minimum required under the
conditions, and should be maintained as nearly constant as possible
throughout the test. Practically all steam entering the glands is drawn
into the turbine, and thence to the condenser, and under the
circumstances it may be assumed the increase in steam consumption
arising from this source is also a minimum.

There is one mechanical feature which has an important bearing upon the
foregoing question, and which it is one of the tester's duties to
investigate. This is illustrat