With this factor properly considered, the power required for beating becomes an interesting study. Many detailed experiments have been published from time to time, the most recent being those described by Beadle. PATENTS TAKEN OUT IN CONNECTION WITH BEATING ENGINES. 1855. PARK (1170).--A small steam engine was attached to the shaft of the beater roll, so that it could be driven direct. 1856. KINGSLAND (2828).--A form of refiner in which the pulp was beaten by a vertical disc rotating in an enclosed case. 1860. JORDAN (792).--A machine devised for mixing size with pulp, made like a conical refining engine, the rubbing surface being provided with teeth or cutters. 1860. JORDAN (2019).--An engine of the refiner type, constructed with a conical drum rotating in a conical casing. The knives at the larger end of the drum are placed closer together than those on the smaller end. 1863. PARK (1138).--Two beaters placed side by side are driven by one steam engine placed between them, the operations being so timed that one rag engine is used for breaking while the other is finishing. 1864. IBOTSON (2913).--The pulp is passed continuously from one engine roll to another, or from one part of a beater roll to another part of the same roll through slotted plates. 1866. ROECKNER (140).--A beating engine of the refiner type with conical drum and casing. 1866. BERHAM (3299).--A beating engine of the conical type with the beater roll rotating vertically instead of horizontally. 1867. CROMPTON (482).--Device for raising the bars in the beater roll as the edge of the plate wears away. 1867. WOOD (914).--Modification in the form of the beater bars (of little importance). 1867. EDGE (3673).--The knives of the beater roll distributed at equal distances apart all round the roll, alternated with strips of wood. 1869. GRANVILLE (1041).--Substitution of a second beater roll for the stationary bed-plate, the knives being set spirally round the roller. 1869. NEWELL (2905).--Weight of the beater roll counterpoised to allow of the exact regulation of the pressure on the stuff in the beating engine. 1870. ROSE (997).--An intercepting plate fixed to the cover of the beating engine which causes that part of the stuff which was usually carried right round by the roll to fall back behind the backfall. 1870. BENTLEY AND JACKSON (1633).--A beater roll having the same width as the engine, and provided with a cover fitted with a pipe which conducted the material back to the front of the roll. 1871. PATTON (1336).--Bottom of beating engine curved in order to prevent the stuff settling or accumulating at any portion of the machine. 1872. SALT (1901).--A beating engine of usual type, but having two beater rolls and two drum washers, one pair in each of the two channels.