5g BULLETIN 173, U. S. NATIONAL MUSEUM 



MILLER ROTARY STEAM ENGINE, 1859 



U.S.N.M. no. 251294; original patent model, transferred from the United States 

 Patent OflSce; not illustrated. 



This model was submitted with the application for the patent is- 

 sued to Charles Miller, of Belleville, 111., May 3, 1859, no. 23852. 



The engine has two oval pistons or cams each running in a sepa- 

 rate circular cylinder or casing. Sliding abutments in the casing 

 bearing on the edges of the cams direct the steam in the forward 

 direction around the casing. Admission of steam is controlled by 

 two flat slide valves working in steam chests on top of the casing. 

 The valves are operated by two eccentrics on the engine shaft. The 

 engine is reversible. 



JAMES PLATT ROTARY STEAM ENGINE, 1862 



U.S.N.M. no. 251292; original patent model; transferred from the United States 

 Patent OflBce ; not illustrated. 



This model was submitted with the application for the patent 

 issued to James Piatt, of Utica, N. Y., April 15, 1862, no. 34981. 



The engine consists of a rotating cylinder in the form of a hollow 

 ring within which are a stationary abutment face and two pistons. 

 The pistons are caused to move by the force of the steam admitted 

 between the face of the abutment block and each piston in turn as 

 it comes around. The cylinder turns with the pistons, and the power 

 shaft is bolted to the cylinder. A stationary cam causes the pistons 

 to move in and out in a radial direction so that they will clear th© 

 abutment as they approach it from the back during each revolution. 



GABRIEL ROTARY STEAM ENGINE, 1867 



U.S.N.M. no. 309196; original patent model; transferred from the United States 

 Patent Office ; not illustrated. 



This model was submitted with the application for the patent issued 

 to Matthias Gabriel, of Newark, N. J., August 6, 1867, no. 67527. 



The engine represented in the model is one of a great many similar 

 designs for rotary steam engines, in which a vane or paddle on a 

 rotary drum fits closely in the annular chamber between the drum 

 and an outer casing and is driven around the chamber by the pressure 

 of steam expanding between the paddle and an abutment that tem- 

 porarily closes the chamber back of the paddle. 



This engine has two sliding abutments, which are moved in (to 

 close the chamber) and out (to clear the paddle as it passes) by 

 means of a cam on the shaft of the engine and a system of followers 

 and yokes. A plain D-slide valve is operated by pinions and rack 

 from an eccentric on the shaft. Two expansions per revolution are 

 obtained. 



