Mr. W. Morgan obtained a patent for an "improved Construction of Conical Valves," which remedies the objection of the great pressure to which they are subject, when large, in a very simple and ingenious manner. The eduction valves are so placed, that the steam in the cylinder acts upon their under surfaces, whilst the steam from the boiler presses upon the upper surfaces of the steam valves; and the upper steam valve being connected with the lower eduction valve, and the lower steam valve with the upper eduction valve, the pressure upon the under surfaces of the eduction valves nearly neutralizes the pressure upon the upper surface of the steam valves; the pressure being merely equal to the difference between the areas of the two surfaces; so that it requires but little force to move the largest valves.
The annexed sketch will help to convey an idea of these valves, a is the upper steam valve; b the lower steam valve, and c the steam pipe; d is the upper eduction valve, and fthe eduction pipe. The lower compartment g of the upper valve box communicates with the upper steam passage of the cylinder; and the lower compartment h of the lower valve box communicates with the lower steam passage of the cylinder; the tail or spindle of the steam valve a passes through a stuffing box in the lower compartments of the upper valve box, and is connected by a coupling nut k with the spindle of the eduction valve e. The tail of the eduction valve d, in like manner, passes through the stuffing-box in the lower compartment of the upper valve box, and is connected by the coupling nut l with the lower steam valve b. The lifting rods m and n pass through stuffing-boxes in the covers of the valve boxes, and are wrought by means of two revolving cams, on a way shaft. By this arrangement the motion of each steam valve and its corresponding eduction valve is rendered simultaneous; and the pressure downwards upon the surface of the steam valves, is nearly counterbalanced by the upward pressure upon the eduction valves: a slight preponderance being given to the former, in order to keep the latter firmly to their seats when closed.