490 THE POPULAR SCIENCE MONTHLY. 



the expanding gases allowed to do the work of the remainder, the 

 piston is subjected to a pressure entirely similar to and as readily con- 

 trolled as that exerted by steam in the steam-engine. The piston 

 is lubricated by its lower edge dipping into a shallow pan, F, at the 

 bottom of the cylinder, containing oil, and the other parts in the or- 

 dinary mannei-. The motor is easily and quickly stopped and started, 

 and Avhen running requires but little attention. It is made in any size 

 desired under ten horse, but those constructed for the trade are of 

 three and five, the former being sold at four hundred and fifty dollars 

 and the latter at six hundred. They are of about the same weight as 

 the Otto, of corresponding power, and occupy a somewhat less space. 



The engine is economical in the consumption of fuel, and with the 

 present abundant supply of oil is the cheapest heat-engine of small 

 power yet made. Five gallons of crude jaetroleum are used, it is stated, 

 in the three, and seven and a half in the five-horse engine for ten hours' 

 running. This is at the rate of one sixth of a gallon or one and a quar- 

 ter pound an hour per horse-power in the smaller machine, and some- 

 what less in the larger. As the calorific effect of petroleum is almost 

 double that of coal, the engine is nearly as efiicient as a steam-engine 

 of large size, and much more so than one of the same power, while, 

 on account of the cheapness of petroleum, the expense for fuel is no 

 greater. The oil used can be obtained in comparatively small quanti- 

 ties at from six to seven cents a gallon, and at the latter price the cost 

 of a horse-power per hour would be a little less than one and a quar- 

 ter; cent, an expense considerably below the best results obtained in 

 any of the engines using gas. This comparison is with the present 

 cost of operating the latter motor, which is not one by which its pos- 

 sible economy is to be judged. The gas now used is the ordinary illu- 

 minating kind, and is high-priced. With a cheap fuel-gas, such as will 

 assuredly come largely into use at no distant day, the cost would 

 probably not be more than half that at present, and possibly less. This 

 would bring it quite near that of the Brayton near enough, at least, to 

 make the advantage of the greater cleanliness and convenience of gas 

 outweigh the gain in cheapness possessed by oil. An important objec- 

 tion to this engine is the one arising from the danger that accompanies 

 the use of coal-oil. The motor itself is indeed quite safe, as much so 

 as the gas-engine, and, if no more oil were stored than that in the tank 

 from which the supply is drawn while working, the danger would be 

 small. But when a considerable quantity is kept on hand in places 

 where there is much valuable property, as in city buildings, the danger 

 is sufficient to warrant increased insurance rates, and in some cases the 

 prohibition of the machine. In situations where gas can not be pro- 

 cured, and where the use of oil would not be attended with the danger 

 incident to crowded localities, it would probably be found one of the 

 most satisfactory motors that can be had. Made in sufficiently small 

 sizes of compact form, and with the oil receptacle and engine on one 



