96 MODERN PAPER-MAKING
by tliis method; a series of, say, Tower beaters would probably be more efficient
and use less power.
The refiner is a very excellent machine for certain purposes, if used with
extreme care and intelligence, but it produces disastrous results if carelessly
handled.
It is now the practice in some mills for the refiner to be placed in the
machine house and under the control of the machineman. The reason for this
is that it is becoming recognised that it is possible, by the use of refiners, to
alter slightly the appearance of the sheet and also assist the machineman in
closing up his sheet when necessary. Previously the use of a refiner was to
clear the stuff after it had been taken from the beaters into a refiner chest; the
stuff then passed from the refiner into a machine service chest. The new
practice calls for a different arrangement, which is as follows:
The refiner is placed after the stuff purnp and immediately before the head
box; the stuff is left slightly longer by the beaterman than would be the case
if there were no refiner. The machineman on starting up examines the sheet
and then sets his refiner to reduce the length of fibre if necessary, and to clear
the stuff of knots. The beaterman is thus relieved of the necessity of clearing
his engine, sometimes a long and difficult business with certain furnishes, and
a lot of power is saved in the beater room. It was quite a common thing,
especially in rag mills, for a knotty engine to be let down, and thus spoil a
whole chestful of stuff. There was no alternative other than to run the stuff
out as broke. With the refiner arranged as part of the machineman s equip-
ment this is not so likely to happen, as die stuff from the knotty engine can
usually be cleared in a minute or two. Further, the placing of a refiner in this
position, where it deals with the stuff immediately before it passes on to the
machine, gives a far better separation of fibres, and enables a much more close
and even sheet to be made.
We are of the opinion that the time is not far distant when this method
will be universally adopted for many classes of papers. The Marshall type of
refiner (Fig. 32) seems to be peculiarly well adapted for use in this position, as
it has the additional advantage of the disc as well as the cone.