CATALOG OF THE MECHANICAL COLLECTIONS I45 



attempts to propel vehicles with internal-combustion engines. Reith- 

 man, of Munich, designed an engine similar in principle to that of 

 Lenoir in 1858, and Hugon, of Paris, who brought out a similar 

 engine in 1862, patented 1865, claimed that his patent of 1858 was the 

 Lenoir engine in principle. Gustave Schmidt in 1861 declared that 

 better economy would result from compression of the explosive mix- 

 ture, and Million the same year applied the principle of previous 

 compression of the gas and air by means of a separate pump. The 

 next important development was the descriptive patent of Beau de 

 Rochas, of France, in which were set forth the events of the 4-stroke 

 cycle and a discussion of its advantages. Fifteen years elapsed before 

 this cycle, which is the most common in use today, was carried out 

 in an engine. In 1866 Nicolaus Otto and Eugen Langen, of Cologne, 

 brought out their atmospheric, or free-piston, engine (see U. S. N. M. 

 no. 308675) constructed on the lines of the Barsanti and Mattenci en- 

 gine of 1857. It succeeded where the earlier engine failed because 

 of a more ingenious mechanical design. At the time of its introduc- 

 tion it was the most economical of gas engines. The Bisschop (Eng- 

 land) engine was of similar design, embodying improvements to 

 avoid noise and recoil. Brayton's engine of 1873 and Simon's (Eng- 

 land) of 1878 involved the principle of ignition at constant pressure 

 (see under "American Developments"). In 1876 Otto and Langen 

 abandoned the noisy, unsteady, and irregular free-piston engine and 

 patented one in which the important innovation was the compression 

 of the charge of air and gas before ignition (see U. S. N. M. nos. 

 251284 and 309556). In this engine the whole cycle advocated by 

 Beau de Rochas is effected in one cylinder. The engine was single 

 acting, and in it one explosion or impulse was obtained in every four 

 piston strokes. The first stroke compressed the explosive mixture 

 and explosion occurred near the end of this stroke, the force of the 

 explosion drove out the piston on the third stroke, and in the fourth 

 stroke the products of combustion were discharged. The earliest 

 trials of the Otto engine (Braner and Slaby in Germany, 1878) 

 showed a striking economy of 38 to 40 cubic feet of gas per horse- 

 power hour, as compared to 44-50 cubic feet with the Lenoir. Tlie 

 success of this engine was undoubted from the first, and for many 

 years few others were sold. It superseded all others and is the 

 design from which all the 4-stroke gas and gasoline engines of today 

 were developed. In 1880 Dugald Clerk of England introduced an 

 engine in which an explosion was obtained after every second stroke 

 or one explosion in every revolution. This was the 2-stroke cycle 

 engine. Compression of the mixture was obtained in a separate 

 pump cylinder. Atkinson introduced several engines that were of 

 more interest as ingenious mechanisms than as any great advance. 

 His engine of 1884 operated on the 4-stroke cycle effected in four 



