This capital contrivance for admitting the steam to the ends of the cylinder, and exhausting the same therefrom, consists in constructing the valve so as to enable the steam to be admitted through the ste'm on which it oscillates and through its body, and to be exhausted by simply exposing the openings alternately, thereby producing a perfectly balanced and highly simplified valve. In our engraving, Fig. 1 represents a vertical section through the center of the valve and steam oscillating cylinderj Fig. 2 is a view of the circular face plate and cylinder, and Fig. 3 is a view of the face of the valve which oscillates over the same. A represents an oscillating steam cylinder, supported on suitable bearings, and having a circular face with two openings, B C, as shown in Fig. 2, communicating by steam channels with the front and back ends of the cylinder respectively. D is the exhaust steam chest furnished with a stuffing-box, E, through which the stem of the valve, F', passes. This stem is hollow, and communicates at one end with the steam pipe, G, and the steam passage withinr it is diverted from its straight course at its end through the valve, so as to open upon the face of the same on the same circle that the openings, B C, are situated, said valve face being kept against the circular face, I, of the cylinder, L, by a set screw, c H. I is a crank secured by a bar or hub to 1 the valve stem, and connected by a rod to the ordinary eccentric on the main crank shaft of the engine. K is the escape pipe. When the steam is admitted to the valve, F', it is caused to pass through the stem, and divergent opening in the body of the same, and to be alternately admitted, with the respective oscillations of the valve, into the steam passages and valve being in reverse directions, and the extent of the movements of the two being sufficient to produce this effect. The cylinder may be made stationarY) and the valve can have a revolving motion over the face of the cylinder if desired, in which case the openings in said face will be made opposite each other, and the outlet opening extended in length as represented in dotted lines in Figs. communicating with the ends of the cylinder, and to be exhausted therefrom in the same alternate manner by the exposure of the openings in the circular face of the cylinder, the respective oscillations of the steam cy!inder 2 and 3, for giving the cut-off to the steam. This is an extremely simple and durable valve, economizing greatly in friction, and not liable to get out of order. It was patented on the 27th af April,'1858. Any further information on the subject can be had by addressing the inventor, Thomas Scott, New York, up to the 1st of July, aud after that period at San Francisco, Cal.