Measures to secure a patent for improvements in the above have been taken by E. G. Hastings of New York City. The improvements consist in the employment of a cutter slider, which carries the necessary chipping tools, and works in an inclined slide, which is adjustable at different inclinations by means of screws, that serve to raise or lower either cross piece of which it is composed. The slider is raised up to a suitable height by a a cam on a rotary shaft, and is made to descend with a quick jerk by a spring or weight, the depth of the cut being regulated by the abovo-mentioned screws. The stone is placed on a table which slides on a stationary bed below the cutter slider,and the table has a regular feed motion communicated to it between every two blows of the cutters. These latter must be of suitable width or in sufficient number to cut across the entire surface of the stoue at every blow, which is given by the descent of the slider ; if requisite, the spring for aiding its descent may be dispensed with, and the slider may be caused to fall and strike by its own weight.