admission.

Passing now to the other great type of engines, those covered under the
general designation of marine engines, this gear has been applied to
nearly 40,000 H.P. indicated, built and building, and to all classes and
sizes, from the launch engine with cylinders 8 inches by 9 inches, running
at 600 to 700 revolutions per minute, up to engines for the largest class
of war ships, such as her Britannic Majesty's steel cruiser Amphion, of
5,000 H.P., with cylinders in duplicate of 46 inches and 86 inches
diameter, and 3 feet 3 inches stroke, running 100 revolutions per minute.
An examination of the indicator diagrams taken from these engines shows
that no wire-drawing takes place, and that, though the expansion is
carried to a point beyond the ordinary requirements, the compression is
but slightly increased. In all the diagrams taken from this valve motion
there is seen the clear, full upper line showing an abundant admission of
steam without any wire-drawing, and also the distinctly marked points
where "cut-off" or "suppression" and where "release" takes place, showing
the rapid action of the valves at those points.

It is well known to engineers that to obtain the maximum advantage out of
compounding, it is necessary to cut off in the low pressure cylinder at a
point corresponding to the relation between the low and the high, and that
point should be unaltered, whereas the point of cut-off in the high may at
the same time be varied to suit the work to be done.

In an ordinary link motion engine (where both links are connected to the
same weigh shaft), when linking up the high pressure cylinder to cut-off
short, the same change is necessarily made in the low. By the use of the
Joy gear, cut-off valves may be fitted to both cylinders, that for the low
pressure being fixed at the constant position required by the proportion