A gasoline engine of 2-1/2 horsepower is the most useful size for a general purpose farm engine. It is convenient to run the pump, washing-machine, fanning-mill, cream-separator, grindstone, and other similar farm chores that have heretofore always been done by human muscle. A small engine may be placed on a low-down truck and moved from one building to another by hand. One drive belt 20 or 30 feet long, making a double belt reach of 12 or 15 feet, will answer for each setting. The engine once lined up to hitch onto the pulley of any stationary machine is all that is necessary. When the truck is once placed in proper position the wheels may be blocked by a casting of concrete molded into a depression in the ground in front and behind each wheel. These blocks are permanent so that the truck may be pulled to the same spot each time. [Illustration: Figure 110.--Kerosene Farm Engine. This is a very compact type of engine with heavy flywheels. A longer base might sit steadier on a wagon, but for stationary use on a solid concrete pier it gives good service.] A gasoline engine for farm use is expected to run by the hour without attention. For this reason it should have a good, reliable hit and miss governor to regulate the speed, as this type is the most economical in fuel. It should have a magneto in addition to a six-cell dry battery. It should be equipped with an impulse starter, a device that eliminates all starting troubles. The engine should be perfectly balanced so as to insure smooth running, which adds materially to the life of the engine. With a good, solid pump jack, a 2-1/2 horsepower engine will pump water until the tank is full, whether it requires one hour or half a day. It is easily moved to the dairy house to run the separator. As the cream-separator chore comes along regularly every night and every morning, the engine and truck would naturally remain inside of the dairy house more than any other place. If the dairy house is too small to let the engine in, then an addition is necessary, for the engine must be kept under cover. The engine house should have some artistic pretensions and a coat of paint. KEROSENE PORTABLE ENGINES The kerosene engine is necessarily of the throttle governor type in order to maintain approximately uniform high temperature at all times, so essential to the proper combustion of kerosene fuel. Therefore, a kerosene engine of the hit-and-miss type should be avoided. However, there are certain classes of work where a throttle governor engine is at a decided disadvantage, such as sawing wood, because a throttle governor engine will not go from light load to full load as quickly as will a hit-and-miss type, and consequently chokes down much easier, causing considerable loss of time.