All About Engines

CHAPTER XIII Fuel and Its Problems WE have repeatedly noticed how the steam engine, the oil engine, and the gas engine have effected a transformation of the habits and customs of the world, and we have seen that each and all of these are merely contrivances for utilising the heat pro- duced by burning fuel. The great problem for all nations, young and old, in the coming years is the supply of fuel, for upon it depends not merely their chances of growth, of increasing prosperity, and the happiness which ought to accompany it, but their very existence. We shall see in this chapter how it is that every nation which desires to make the most of the useful things which lie beneath the soil or grow upon its surface, will have to pay attention first of all to the supply of fuel, and to economy in its use. What is coal ? A geologist will tell you that it is a black rock, combustible or capable of being burnt, found in the ground at varying depths in layers of variable thickness. Some “ seams,” as they are called, may be no more than a few inches between the incombustible rock above and the incombustible rock below; while others may be 30 feet. Fre- quently a lump will show distinctly the trace of a 326