on slide valve
into an automatic cut off. The cut off would not be as quick as in
other cases we have cited, depending here upon the movement of the
lower valve alone, and that, too, is in its slowest movement; whereas
in the other cases, the edges approaching each other, by the differing
movement of the valves the cut off is very rapid, provided the
distance to travel is not long. In this device considerable noise must
result by the cut off valve striking the cut off blocks, and a
considerable amount of leakage is likely to occur past this valve.

But there is one great objection in the valve gears thus far cited,
that the travel of the expansion valve upon the main valve is
variable. I have in mind the case of a Kendall & Roberts engine, which
had been run for a long time at no better economy than would be
obtained from a plain slide valve engine, and when it was attempted to
get an earlier cut off by separating the two cut off valves, they had
worn so much in their old place on the valve that shoulders were found
sufficient to cause a disagreeable noise and a leaky valve. This is
very apt to occur, not only where the valve is run for a long time on
one seat, but in cases of variation of the travel of the expansion
valve. The result is that a change will bring about a leaky valve,
something that every engineer abhors.

The construction of the Buckeye engine, which is also of this type, is
such that the travel of the valve on the back of the main valve is
always the same, no matter what the cut off may be. Then this engine
makes use of our second proposition as a means of effecting the cut
off, viz., by advancing the eccentric. You will readily observe that
anything that will cause the cut off valve to reach a certain point
earlier in the stroke will bring about an earlier cut off as it
hastens everything all around. This is the plan pursued in the
Buckeye, in which the governor, of the shaft type, turns the eccentric
forward or back according as the load demands. Then, in addition, the
valve is balanced partially, the attempt not being made to produce an
absolutely balanced valve, on the ground that there should be friction
enough to keep the surfaces bright and to prevent leakage. The most
perfect valve will, of course, be entirely balanced under all
conditions of pressure so as to move with perfect ease. With the
riding cut off valve in connection with the plain slide valve, this is
not accomplished, and it does n