Page:Miscellaneous Papers on Mechanical Subjects.djvu/147

 on Staten Island, about nine miles from New York. The works are carried on under extensive sheds, near to the water side, and are connected with a wharf by a railway, which also extends to the bed from which the clay is dug. A large movable shed is erected on the bed of clay at the terminus of the railway.

In dry weather the clay is collected by slicing it from the surface with a kind of shovel having a sharp edge, which is drawn by two horses, and will hold about two barrowsful.

In wet weather the surface of the clay is harrowed to the depth of 2 or 3 inches by a triangular wooden frame, carrying nine teeth, a process which, in the powerful rays of an American sun, soon causes the moisture to evaporate. It is then taken off by the scoop or shovel above described, and conveyed to the shed, whence it is carried by rail to the machine shed. It is deposited close to a cylindrical screen, revolving on a fixed axis, which has projecting loose bars. The screen is about 8 feet long and 3 feet in diameter, and consists of bars ⅝ inch square, rivetted on two cast-iron wheels, which form the ends; the bars are about $1/16$ inch apart, and the clay is riddled through them. The screen is inclined and the clay is fed in between the arms of the wheels, and as it revolves the small pulverized particles fall