148 BULLETIN 173, U. S. NATIONAL MUSEUM 



solids, such as undistilled turpentine or rosin, generated in the retort 

 that was part of the engine. 



The model shows an engine with a 'horizontal double-acting cyl- 

 inder. The piston transmits its motion to a vertical walking beam 

 from which a connecting rod drives the motor crankshaft. Beneath 

 the cylinder is located a pump beam. Below the engine cylinder also 

 is a rectangular tank or retort for vaporizing the fuel. This retort 

 has tubular openings through which the hot exhaust gases are di- 

 rected. The pump supplies air to the retort and directly to the 

 engine cylinder in proportions regulated by hand cocks. The com- 

 bustible mixture from the retort and additional air from the pump 

 are admitted to the engine by a rotary cylindrical valve. The valve 

 is driven by gearing from the crankshaft, and the engine may be 

 reversed by shifting the valve gears. Ignition is effected by flames 

 from lamps at either end of the cylinder. The ignition valves are 

 operated by pins on the piston. A lamp is also provided below 

 the retort for vaporizing the fuel in starting the engine. 



In operation a mixture of vapor and air from the retort is admitted 

 with a quantity of pure air as the piston moves away from the cylin- 

 der head. Ignition occurs at the same time, and combustion continues 

 for a part of the stroke when admission stops and the piston is car- 

 ried to the end of the stroke by the expanding gases. 



Perry operated the engine with a retort heated solely by the heat 

 of the cylinder, and he also suggested jacketing the cylinder and 

 cooling it with a stream of air from a blower. 



STUART PERRY GAS ENGINE, 1846 



U.S.N.M. no. 251278 ; original patent model ; transferred from the United States 

 Patent Office; not illustrated. 



This model was submitted with application for Patent no. 4800, 

 issued October 7, 1846. 



This engine is very similar to the Perry engine of 1844. It differs 

 in that the cylinder is water-jacketed and the hot cooling water is 

 used to heat the fuel retort. Ignition is effected by heated platinum 

 exposed to or separated from the explosive mixture by a valve. 



Tlie model shows a horizontal double-acting engine completely 

 water- jacketed. Beside the cylinder is the retort for generating the 

 vapors. Air is mixed with the vapor in a valve box above the retort, 

 and valves operated by cams from a lay shaft admit the explosive 

 mixture to passages leading to the cylinder. The gas is ignited 

 by incandescent platinum, and combustion continues during about 

 one-third of the stroke, the expansion of the products of combustion 

 forcing the piston to the end of the stroke. 



