38 



BULLETIN 119, U. S. NATIONAL MUSEUM. 



water in a water jacket surrounding the upper portion of the cyl- 

 inder is kept in circulation by a pump whose piston is connected with 

 the main beam on the same side of the center of oscillation as the 

 " working " piston. 



By the arrangement of the crank shaft, the centers of motion of 

 the beam and bell-crank lever, and their individual connections a 

 long crank with a short stroke of the " worldng " piston is obtained. 



Cat. No. 251.286 U.S.N.M. 



FIG. 14. PKRUY GAS ENGINE, 184G. 



Model of Stuart Perry Gas Engine. U. S. Patent, No. 4800, October 7, 

 1846. Transferred from United States Patent Office. 



This engine is "to be operated by the explosive mixtures of in- 

 flammable gases or vapors," the particular explosive mixture used, 

 however, being that of air and gas generated from spirits of tur- 

 pentine. The gas generator is part of the equipment and is situated 

 within a water tank which also surrounds the engine cylinder. 



Cylindrical tanks beneath the engine bed contain air under pres- 

 sure filled at first by a hand pump, but after the engine is in motion 

 by a pump operated by the engine. To operate the engine it is 

 first necessary to heat the water in the tank by some outside means 

 in order to vaporize the turpentine. Gas having been generated, 

 the extraneous supply of heat is removed and air from the air-supply 

 tanks is admitted into a valve box located above the retort. Through 

 a slide valve some of this air enters the retort, is mixed with the 

 gas, and exits through suitable apertures to passages leading to 

 opposite ends of the cylinder. The admission of the gas to the- 



