BEATERS 81

experience shows that if the maximum efficiency is to be obtained, great care
must be paid to details of design and dimensions.

For a hollander holding 450 Ib. of dry stuff and intended for general use,
such as the beating of wood pulp, wood and 'broke', wood and rag and all
rag furnishes, the weight of the roll should not exceed 3 tons and the circum-
ferential speed of the roll should be about 2000 feet per minute.

The Umpherston beater (Fig. 22) differs from the hollander in that it is
placed *on end' to save space; in other words, the stuff travels down from

[West End Et^ine Works Lli
FlG. 22.-—UMPHERSTON BEATING ENGINE
In this type of engine the stuff circulates in a trough beneath the bed-plate
the roll and underneath it, and then up and back again, instead of round the
trough. The midfeather is placed under the bed-plate and the roll is well
out of the stuff.
We are of opinion that there is litde to choose between a well-designed
hollander and an Umpherston, but the latter has three distinct advantages—
namely, its saving of space, its easier and quicker emptying facilities, and its
freedom from lodgers'; it is also much more shut in—i.e. the stuff is not nearly
so exposed, to the dust and dirt which are continually falling about in a beater
room, as is the case with the hollander. Owing to its being so much enclosed,
when beating hard fibres, the stock heats up very quickly.
The Umpherston is a compact, well-designed and thoroughly efficient
beater.