The efficacy of such a remedy, if it
possesses any, is in fact inversely as the piston speed.
[Illustration: Fig.1]
Fig. 1 is a perspective of the piston itself, or the "spider," with its
follower and its rings removed, which are shown in Fig. 2. Fig. 3 is a
cross section of another form of the piston, to be presently described,
but which will serve to explain that shown in Figs. 1 and 2. Next to the
core of the spider are two narrow internal rings, A, in Figs. 1 and 3;
surrounding these two outer rings, B, the cross section of which is of
L-form, as seen in Fig. 3. The lips of these outer rings extend to the
whole thickness of the piston. The flange head of the piston, and also
the follower, are turned beveling on their edges to admit the steam
around the annular space thus formed under the rings, B. These spaces
are plainly exhibited at C, in Figs. 2 and 3. Both inner and outer rings
are adjusted to the bore of the cylinder by means of the gibs, D, and
set screws seen in Fig. 1.
[Illustration: Fig.2]
The section, Fig. 3, represents a modification intended for use in
vertical cylinders, if considered necessary.
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