PRESSES 193

The guiding of the wire is much simpler and, in fact, presents practically
no difficulty with a suction roll, and the danger of running the wire out of
square, due to uneven weights on opposite sides of the couch press, does not
arise when a suction roll is used. Much longer life is generally obtained from
the machine wires, and in most cases a drier sheet is delivered on to the wet
felt, which latter in turn naturally has a longer life, by reason of the fact that it
has not so much water to deal with.

There are now several very satisfactory7 suction couch rolls available, and
experience seems to show that they will run for many years without any atten-
tion whatsoever. While some of these rolls consume a fair amount of power
through their vacuum pumps, very efficient pumps are now available, and the
power consumed is nothing when compared to the efficiency of the roll and

IM.
Be. 71.—THE PSESS PAKT OF A MODE*N MACHINE: PLAIN PBESS Rosxs
its many advantages in the saving of time and the maintaining of production
at a high level.
Presses.—After passing through the couch rolls, though the sheet is now,
for the first time, in condition to be handled, it must be further pressed, so as
to be so far freed from water as to stand the heat of the dryers.
This is accomplished by running it on woollen felts between 'press rolls'.
Two sets of press rolls and felts are used, though machines designed for high
speed or for making special papers may have three or four. Since pressure
means loss of bulk, it is not desirable for machines making high-class paper or
bulky printings to have more than two sets. The first set of press rolls and
the Vet felt*, as it is called, do the bulk of the work. The second set is so arranged
as to smooth out the wire mark.
Underneath the bottom roll is placed an oblong box or tray to catefa and