32 BULLETIN 119, U. S. NATIOjSTAL MUSEUM. 



heavy expense in wear and tear and the burning out of parts coun- 

 teracted its fuel efficiency. 



The great restriction to the development of the hot-air engine 

 has been the necessity of keeping the temperature low within the 

 cylinder, with the result that its efficiency is limited. 



John Ericsson of New York constructed an air engine in 1834 

 of simple design in which hot air admitted to a cylinder moved a 

 piston while expanding down to atmospheric pressure. In 1852 

 Ericsson built some large engines to be used in propelling trans- 

 Atlantic vessels, A ship was so equipped but never made an ocean 

 trip other than from New York to Washington. For the reasons 

 noted, large hot-air engines have since Ericsson's time been aban- 

 doned but small-powered engines are being made for light work. 



The earliest internal-combustion engine was the gun. The use of 

 gunpowder, however, as a means of obtaining mechanical power is 

 of comparatively recent date, such experiments having been made 

 during the latter part of the seventeenth century by Hautefeuille, 

 Huygens, and Papin. Huygens in 1678-79 exploded a charge of 

 gunpowder in the bottom of a vertical cylinder. The greater part of 

 the air and of the gaseous products were expelled through nonreturn 

 valves, but the remaining gas in cooling produced a partial vacuum 

 below a piston, which then descended owing to the atmospheric 

 pressure on the outside and in so doing did work by means of a cord 

 over a pulley, 



A period of over a hundred years ensued before any further ex- 

 periments were made utilizing the explosion of inflammable gases. 

 In 1794 an English inventor, R. Street, secured a patent, No. 1983, 

 which involved the vaporizing of spirits of turpentine on a heated 

 metal surface, mixing the vapor thus produced with air in a cylinder, 

 firing the mixture by an outside flame, and driving a piston by the 

 explosion produced. Another fifty years passed, when in 1844 one 

 Stuart Perry of New York procured a United States patent for 

 " an engine to be operated by the explosive mixtures of inflammable 

 gases or vapors," Two years later a second patent was granted to 

 Perry for improvements made on the original engine. 



The first practical gas engine was developed in France by J. J. E, 

 Lenoir and patented in 1860. Although it did not embody any new 

 features, it was successful. To start the engine the fly-wheel was 

 pulled over, thus moving the piston, which drew into the cylinder a 

 mixture of gas and air through half its stroke. The gas was then 

 exploded by an electric spark and moved the piston to the end of 

 its stroke, the pressure meanwhile falling by cooling and expansion 

 to that of the atmosphere when exhaust took place. In the return 

 stroke the process was repeated, thus resembling a double-acting 



