so small that the fabric is entirely dissolved
and converted into short fibers. The rags are for this purpose first
cut into pieces, which are again reduced by special machines. The rags
are cut in a rag cutting machine, which was formerly constructed
similar to a feed cutter; later on, more complicated machines of
various constructions were employed. It is not our task to describe
the various kinds, but we remain content with the general remark that
they are all based on the principles of causing revolving knives to
operate upon the rags. The careful cleansing of the cut rags,
necessary for the manufacture of paper, is not required for roofing
paper. It is sufficient to rinse away the sand and other solid
extraneous matter. The further reduction of the cut rags was formerly
performed in a stamp mill, which is no longer employed, the pulp mill
or rag engine being universally used.

The construction of this engine may be described as follows: A box or
trough of wood, iron, or stone is by a partition divided into two
parts which are connected at their ends. At one side upon the bottom
of the box lies an oakwood block, called the back fall. In a hollow of
this back fall is sunk the so-called plate, furnished with a number of
sharp steel cutters or knives, lying alongside of each other. A roller
of solid oakwood, the circumference of which is also furnished with
sharp steel cutters or knives, is fastened upon a shaft and revolves
within the hollow. The journal bearings of the shaft are let into and
fastened in movable wooden carriers. The carriers of the bearings may
be raised and lowered by turning suitable thumbscrews, whereby the
distance between the roller and the back fall is increased or
decreased. The whole is above covered with a dome, the so-called case,
to prevent the throwing out of the mass under the operation of
grinding. The roller is revolved with a velocity of from 100 to 150
revolutions per minute, whereby the rags are sucked in between the
roller and the back fall and cut and torn between the knives. At the
beginning of the operation, the distance between the roller and the
back fall is made as great as possible, the intention being less to
cut the rags than to wash them thoroughly. The dirty water is then
drawn off and replaced by clean, and the space of the grinding
apparatus is lessened gradually, so as to cut the rags between the
knives. The mass is constantly kept in motion and each piece of rag
pass