1886. Kron (9885).—A device for securing better circulation of the pulp, the stuff leaving the beater roll being divided into two streams which are brought together again in front of the roll.
1886. Horne (10237).—A long rectangular vessel with a large beater roll at one end, contrived so as to force the pulp leaving the beater roll to pass down a partition separating it from the pulp going towards the beater roll.
1886. Macfarlane (11084).—An engine fitted with two beater rolls which rotate in opposite directions, the stuff being mixed between them.
1887. Nacke (746).—A centrifugal circulating wheel rotating horizontally in the centre of the beating engine is used in combination with a parallel cutting disc.
1887. Marshall (1808).—A conical refiner having in addition at its large end a pair of grinding discs fitted with knives and rotating vertically.
1887. Voith (6174).—An alteration to the covers of the beater rolls which prevent stuff from being carried round the cylinder, and cause it to pass over the backfall freely.
1890. Hemmer (17483).—A beating engine provided with a separate return channel for the pulp, the circulation through the channel being effected by a small centrifugal pump.
1890. A. E. Reed (19107).—A beating engine in which the pulp discharged over the backfall is delivered to the front of the beater roll by a screw propeller.
1891. Karger (11564).—A beater similar to the Umpherston, but provided with a circulating roll fitted with radial projections which delivers the stuff to the front of the beater roll.