The fuels most widely used in this country are coal, gas, and kerosene. Wood is still used for cooking by those who own wood lots, or who live in a district where wood is abundant, but in a sense it is the fuel of the past. Electricity is generated from coal except in the few communities where the electric current is derived through machinery from the energy of falling water but electricity is not in common household use, and is still the method of the future for the average family. Other substances are burned for fuel occasionally or in restricted localities. Corn cobs are used sometimes in the corn belt. Peat is an old-world fuel. It is a vegetable substance taken in blocks from marshes, in reality the first stage of coal formation. It is a slow-burning fuel which is cheap in its own locality.

Economy of fuel is a world problem, for it is evident that the coal supply will be exhausted in course of time, and this is true also of coal oil or petroleum. Scientists are experimenting to discover practical methods, not dependent upon the burning of coal, for generating electricity. Water power is the only practicable method so far, and to make it permanently available we must conserve the forests still remaining to us, and thus safeguard the sources of our rivers.

Another effort toward economy is seen in the use for fuel of waste products treated in some way to make them readily combustible. The briquet is used in Europe where the fuel supply is limited. It is made of sawdust or waste coal, with d 33 some petroleum, tar, resin, or other substance, heated together and molded. Good briquets yield a large amount of heat in proportion to bulk and weight. The problem here, as with all waste, is to find a manufacturing process that will make the product cheap enough to be practical for common use.

It is a natural impulse to use lavishly whatever is at hand in abundance, and it is only a highly civilized community that takes thought for the economy of the future. Considered only from a selfish point of view, however, with coal and petroleum at the high prices that are likely to prevail, the saving of fuel is one of our most important economies.