m, and makes the impression. Before the cylinder
completes its revolution, the grippers open and release the sheet, and
at the same instant another set of grippers on an adjoining cylinder,
called the "delivery cylinder," seize the sheet. From this delivery
cylinder the sheet runs down over a set of strings, and is lifted off
the strings by a sort of fan, or "sheet flier," and deposited on a
table at the rear of the press. This method of delivering the sheets
is known as the cylinder or rear delivery. This press may also be
fitted for "front delivery." By this method the sheet of paper after
being printed is carried around on the impression cylinder until the
front edge comes again to the feeding point. Just as the impression
cylinder comes to a stop, a set of grippers seize the front edge of
the printed sheet, draw it over and away from the impression cylinder,
and deposit it, with the printed side up, upon a table near the front
of the press and above the ink-fountain and distributing rollers.

The average speed of one of these presses is from one thousand to
fifteen hundred impressions an hour, depending upon the desired
quality of the work.

Notwithstanding the excellent qualities of the stop-cylinder press,
commercial necessities often demand a sacrifice of quality to speed,
and this has brought the two-revolution press into very general use.
As the name implies, the cylinder makes two revolutions, one to print
the sheet, and the other, an idle one, to allow the bed to return.
While the bed is returning, the impression cylinder is lifted to clear
the type-form. As the cylinder rotates continually at a uniform speed,
the type-bed must also travel at a constant speed. The reversal of the
movements of the bed must, therefore, take place in a short space of
time.

The study of inventors has been concentrated upon this subject more
than upon any other connected with flat-bed presses, and hundreds of
patents for "bed motions" have been taken out. Considering the fact
that in the larger presses the weight of the bed and form is about one
and a half tons and that this weight moving at a speed of about six
feet in a second must be brought to a full stop and put into motion
again in the opposite direction at full speed in about one-quarter of
a second, it is obvious that the problem was not an easy one,
especially when the reversal of the bed must be accomplished without a
jar or vibration. The mechanism employed has alwa