This muffler, the invention of Mr. Thomas E. Hill, of Rahwl-.v, N. J., is for deadening or preventing the unpleasant hissing sound of escaping steam from the valves of steam engines. The main casting is formed with an outer circular casing and with inner upwardly projecting concentric 'flanges, which form annulai chambers and a central circular chamber, the bottom-of which is formed by a valve fitted in an opening in the casting. This valve is held to its seat against the pressure of steam by a spring arranged in a box that may be lifted against the pressure of the spring by suitable levers. The pressure of the spring upon the valve can be adjusted by means of a bolt, the upper end of which screws into the center of the top plate, and the lower end of which bears against a plate resting on top of the spring. It will be seen that by turning this bolt, which passes loosely through the upper or neck portion of the box inclosing the spring, the latter can be made to exert more or less pressure upon the valve. Held within the casing is a deflector formed with two downwardly projecting- concentric flanges, which enter the annular chambers formed in the. casting. This construction -compels the steam escaping from the valve to take a circuitous course through the chambers, in which it is diffused and its pressure reduced; it finally issues in many small jets from the numerous holes formed in the top plate.