Some persons unaccustomed to gasoline may wonder if a gasoline engine is as safe as a steam engine. The fact is, they are very much safer, and do not require a skilled engineer to run them. The gasoline tank is usually placed outside the building, where the danger from an explosion is reduced to a minimum. The only danger that may be encountered is in starting the engine, filling the supply tank when a burner near at hand is in flame, etc. Once a gasoline engine is started and is supplied with gasoline, it may be left entirely alone without care for hours at a time without danger and without adjustment.
With a steam engine there is always danger, unless a highly skilled man is watching the engine every moment. If the water gets a little low he is liable to have an explosion; if it gets a little too high he may knock out a cylinder head in his engine; the fire must be fed every few minutes; the grates cleaned. There is always something to be done about a steam engine.
So here is another point of great saving in a gasoline engine, namely, the saving of one man's time. The man who runs the gasoline engine may give nearly all his time to other work, such as feeding a corn-sheller, a fodder chopper, or the like.
Kerosene may also be used in the same way with a special type of gas engine.
The amounts of fuel required of the different kinds possible in a gas engine are compared as follows by Roper:
Illuminating gas, 17 to 20 cubic feet per horsepower per hour.
Pittsburg natural gas, as low as 11 cubic feet.
74° gasoline, known as stove gasoline, one-tenth of a gallon.
Refined petroleum, one-tenth of a gallon.
If a gas producing plant using coal supplies the gas, one pound of coal per horsepower per hour is sufficient on a large engine.
DESCRIPTION OF THE GAS OR GASOLINE ENGINE.
The gas engine consists of a cylinder and piston, piston rod, cross-head, connecting rod, crank and flywheel, very similar to those used in the steam engine.
There is a gas valve, an exhaust valve, and in connection with the gas valve a self-acting air valve. The gas valve and the exhaust valve are operated by lever arm or cam worked from the main shaft, arranged by spiral gear or the like so that it gets one movement for each two revolutions of the main shaft. Such an engine is called "four cycle" (meaning one power stroke to each four strokes of the piston), and works as follows: