556 POPULAR SCIENCE MONTHLY. 



They exploded a small quantity of gunpowder in a large vessel with 

 escape valves, which after the explosion caused a partial vacuum to re- 

 main in the vessel. This partial vacuum was then used to actuate a 

 piston or engine and perform useful work. Subsequently several other 

 inventors worked on the same lines, but all of these failed on account 

 of two causes which now are very evident to us. Firstly, gunpowder 

 was then, as it still is, a very expensive form of fuel, in proportion to 

 the energy liberated on explosion; secondly, the method of burning 

 the powder to cause a vacuum involves the waste of nearly the whole of 

 the available energy, whereas, had it been burned under pressure, as in 

 the cannon, a comparatively large percentage of the energy would have 

 been converted into useful work. But even with this alteration, and 

 however perfect the engine had been, the cost of explosives would have 

 debarred its coming into use, except for very special purposes. 



We come a century later to the first real gas-engine. Street, in 

 1794, proposed the use of vapor of turpentine in an engine on methods 

 closely analogous to those successfully adopted in the Lenoir gas-engine 

 of eighty years later, or thirty years ago. But Street's engine failed 

 from crude and faulty construction. Brown, in 1823, tried Huygens's 

 vacuum method, using fuel to expand air instead of gunpowder, but 

 he also failed, probably on account of the wastefulness of the method. 



Wright, in 1833, made a really good gas-engine, having many of the 

 essential features of some of the gas-engines of the present day, such as 

 separate gas and water pumps, and water-jacketed cylinder and piston. 



Barnett, in 1839, further improved on Wright's design, and made 

 the greatest advance of any worker in gas-engines. He added the 

 fundamental improvements of compression of the explosive mixture 

 before combustion, and he devised means of lighting the mixture 

 under pressure, and his engine conformed closely to the present-day 

 practise as regards fundamental details. No doubt Barnett's engine, 

 so perfect in principle, deserved commercial success, but either his 

 mechanical skill or his financial resources were inadequate to the task, 

 and the character of the patents would seem to favor this conclusion, 

 both as regards Barnett and other workers at this period. Up to 1850 

 the workers were few, but as time went on they gradually increased in 

 number; attention had been attracted to the subject, and men with 

 greater powers and resources appear to have taken the problem in hand. 

 Among these numerous workers came Lenoir, in 1860, who, adopting 

 the inferior type of non-compression engine, made it a commercial 

 success by his superior mechanical skill and resources. Mr. Dugald 

 Clerk tells us: " The proposals of Brown (1823), Wright (1833), Bar- 

 nett (-1838), Bansanti and Matteucci (1857), show gradually increas- 

 ing knowledge of detail and the difficulties to be overcome, all leading 

 to the first practicable engine in 1866, the Lenoir." This stage of the 



