Technical knowledge of electricity and its behavior under different circumstances is hardly necessary to a farmer, because the manufacturers have simplified the mechanics of electric power and lighting to such an extent that it is only necessary to use ordinary precaution to run the plant to its capacity. At the same time it is just as well to know something about generators, switchboards and the meanings of such terms and names as volt, ampere, battery poles, voltmeter, ammeter, rheostat, discharge switch, underload circuit breaker, false fuse blocks, etc., because familiarity with these names, and the parts they represent gives the person confidence in charging the batteries. Such knowledge also supplies a reason for the one principal battery precaution, which is not to use out all of the electricity the batteries contain. Those who have electric lighting plants on the farm do not seem to feel the cost of running the plants, because they use the engine for other purposes. Generally manufacturers figure about 1 H.P. extra to run a dynamo to supply from 25 to 50 lights. My experience with farm engines is that for ordinary farm work such as driving the cream separator, working the pump and grinding feed, a two-horse power engine is more useful than any other size. Farmers who conduct business in the usual way will need a three-horsepower engine if they contemplate adding an electric lighting system to the farm equipment. Among the advantages of an electric lighting system is the freedom from care on the part of the women. There are no lamps to clean or broken chimneys to cut a finger, so that when the system is properly installed the only work the women have to do is to turn the switches to throw the lights on or off as needed. The expense in starting a farm electric light plant may be a little more than some other installations, but it seems to be more economical in service when figured from a farmer's standpoint, taking into consideration the fact that he is using power for generating electricity that under ordinary farm management goes to waste. A three-horsepower engine will do the same amount of work with the same amount of gasoline that a two-horsepower engine will do. This statement may not hold good when figured in fractions, but it will in farm practice. Also when running a pump or cream separator the engine is capable of doing a little extra work so that the storage batteries may be charged with very little extra expense.