In polishing plate glass and other substances on a polishing bed having an unbroken flat surface, and using therewith a fine polishing material in a moist state, all air is excluded from between the polishing bed and the slab, or substance under operation, consequently the pressure of the atmosphere on the back of the slab is the cause of great friction, which necessitates the exercise of very great power to produce the motion necessary for polishing. In order to overcome this difficulty, Phineas Burgess, of this city, has invented and patented (in Great Britain) an improvement which consists in grooving the surface of the polishing bed in circles, eccentric to its axis of rotation. By grooving or otherwise similarly reducing the surface of the polishing bed, for the purpose of admitting air under the slab, the retarding atmospheric pressure will be materially reduced. The above improvement was secured by patent through the Scientific American Patent Agency.