For heating the house, it is calculated that 2 watts is required for each cubic foot of air space in a room, during ordinary winter weather. Thus, a room 10 × 12, and 8 feet high, would contain 960 cubic feet, and would require 1,820 watts energy to heat it in cold weather. Five such rooms would require 9.1 kilowatts; and 10 such rooms, or their equivalent, would require 18.2 kilowatts. Electric heating devices are divided into two classes: (1) those which can be used on lamp circuits, _and do not draw more than 660 watts each_; and (2) those which draw more than 660, therefore _require special wiring_. The capacity of these devices is approximately as follows: Lamp circuit devices: Watts Electric iron 400 to 660 Toaster 350 to 660 Vacuum cleaner 200 to 400 Grill 400 to 660 Small water heater 400 to 660 Hot plates 400 to 660 Lamp circuit devices: Coffee percolator 400 to 660 Chafing dish 400 to 660 Electric fan 100 to 250 Special circuit devices: Hot water boiler heater 800 to 1,200 Small ovens 660 to 1,200 Range ovens 1,200 to 3,000 Range, hot plates 400 to 1,300 Radiators (small) 750 to 1,500 Radiators (large) 1,500 to 6,000 The only device in the above list which is connected continuously, is the hot water boiler, and this can be credited with at least one electrical horsepower 24 hours a day. It is a small contrivance, not much bigger than a quart can, attached to the back of the kitchen boiler, and it keeps the water hot throughout the house at all hours. Its cost will vary with the make, ranging from $8 to $15; and since it is one of the real blessings of the farm kitchen and bathroom, it should be included in all installations where power permits. Electric radiators will be used 24 hours a day in winter, and not at all in summer. They are portable, and can be moved from room to room, and only such rooms as are in actual use need be heated. The other devices are for intermittent service, many of them (like the iron) for only a few hours each week. The grill, chafing dish, coffee percolator, etc., which are used on the dining room table while the family is at meals, each draw an equivalent of from 6 to 10 carbon lights. By keeping this in view and turning off spare lights, one can have the use of them, with even a small plant. Thus, a one kilowatt plant permits the use of any one of these lamp circuit devices at a time, with a few lights in addition. _Power_