_Electricity_ is not a fuel, but is classed here as a source of heat. It may be supplied for cooking purposes by any company that furnishes electric light, and should be available in the country wherever an electric trolley runs. The energy supplied is measured and paid for by the kilowatt; that is, one thousand watts. The terms used for electrical measurements cannot be really understood until one has studied electricity. It may be said, however, that the _ampere_[6] is the unit of current strength, the _volt_ is the unit of electrical pressure or electromotive force, the _watt_ is the unit of electrical power and the basis of payment for current supplied for heating or lighting. Voltage, amperage, and watt or kilowatt are the terms in common use. If you read the circulars that advertise electric cooking apparatus, you will find the request to state the voltage of your electric current in ordering a piece of apparatus. Or again, the number of watts used per hour is given, with the catalogue number and the size of an electric stove. The cost of electricity per kilowatt (usually from ten to fifteen cents) varies in different localities. The great advantage of electricity is that little heat is lost in radiation, and that the degree of heat is well under control. There are also no products of combustion present, and this is the only source of heat for cooking of which this is true. Both gas and kerosene vitiate the air to some extent. =Cooking apparatus.=——The wastefulness of cooking operations, past and present, is due largely to the defects of the apparatus used. The open fireplace for wood, and the open grate for coal, are two arrangements that permit most of the heat to pass up the chimney, and into the room. See Frontispiece and Fig. 14. In Fig. 14 there is illustrated at the right a brick oven with a flue opening into the chimney. This was one of the earliest inventions for saving fuel and heat. This oven was lined with brick or stone, and the fire of wood was built in it, and allowed to remain until it had burned out. The coals and ashes were removed, and when the brick had cooled somewhat cakes and pies were put in to bake. This oven retained its heat for twenty-four hours, and beans put in Saturday afternoon were taken out hot for the Sunday morning breakfast. The method was clumsy, but a good heat saver. [Illustration: FIG. 14.——A colonial fireplace. _Courtesy of the Historical Society, Ipswich, Mass._] Figure 15 is an American stove, early nineteenth century, wood the fuel; and from this form, modified for using coal, has developed the modern American coal range (Fig. 18). Even the latest types are very wasteful of heat. Stoves like that shown in Fig. 19 have been devised for use with gas. Even with these only a small percentage of the heat generated is available for cooking. [Illustration: FIG. 15.——An early American stove, 1823. _Courtesy of the Bryson Library._]