158 BULLETIN 173, U. S. NATIONAL MUSEUM 



when it was given the serial number 1501 and sold as the first one of 

 thousands of its type. 



Stuart and Binney patented the hot-bulb vaporizer and igniter in 

 England in 1890, and in the same year they introduced an engine in 

 which fuel oil was sprayed into the cylinder after the compression 

 of pure air. United States patents were granted in 1890 and 1893. 

 The hot-bulb vaporizer is an uncooled chamber extending from the 

 cylinder and connected to it by a constricted passage. This chamber 

 is maintained at red heat by the combustion in the cylinder. 



The engine operates on a 4-stroke cycle, drawing in a charge of air 

 on the back stroke of the piston, compressing the air on the return 

 stroke. Ignition is caused by the increase in temperature due to 

 compression aided by the hot surfaces of the vaporizer. Combustion 

 drives out the piston on the power stroke and the spent gases are 

 exhausted on the return. Oil is injected into the vaporizer just 

 before the end of the compression stroke. 



A torch and hand-driven blower are provided to heat the vaporizer 

 for starting the engine. The oil pump supplies a constant quantity 

 of oil at each stroke. Governing is accomplished by diverting part 

 of the oil back to the reservoir, through a bypass valve that is 

 controlled by a fiyball governor. 



CHARLES MANLY RADIAL ENGINE, 1901 



Plate 33. Figuee 2 



U.S.N.M. no. 248651 ; original ; deposited by the Smithsonian Institution ; photo- 

 graph no. 30592A. 



This is the 5-cylinder, 4-cycle, radial, water-cooled, gasoline engine 

 built by Charles M. Manly in the shops of the Smithsonian Institution 

 at Washington for the full-size Langley Aerodrome. The engme 

 was completed in December 1901 and was tested in January 1902. 

 Under a Prony brake load of 52.4 horsepower at 950 revolutions per 

 minute, it ran continuously during three 10-hour tests. The net 

 weight of the engine proper is 124.2 pounds ; with the two flywheels, 

 140 pounds ; and with 20 pounds of cooling water and accessories the 

 total weight of the airplane power plant was 207.5 pounds, or 3.96 

 pounds per horsepower. 



The following account of the building of the Manly engine, its de- 

 scription, and tests is based on Langley Memoir on Mechanical Flighty 

 pt. ^, 1897-1903, by Charles M. Manly, Smithsonian Contributions to 

 Knowledge, vol. 27, no. 3, pp. 123-284, 1911. 



Wlien Dr. Langley decided to build a full-size flying machine as 

 a result of his success with small models, he required an assistant 

 with engineering ability. Accordingly, Charles M. Manly was em- 

 ployed at the suggestion of Dr. R. H. Thurston, director of Sibley 



