All About Engines

272 All About Engines articulated locomotive is very largely used, and in Western Australia the Garrett is used. The latter is really two engines on separate trucks with a boiler between. Again, while coal is the usual fuel, many engines are constructed to use oil or tar. The only English company which adopts this plan is the North Eastern, which uses tar or tar oil. The liquid fuel is sprayed through a jet, by the aid of steam, so that it issues in a fine spray which burns rapidly and completely if the oil supply is properly adjusted, and with an absence of smoke. In America, where petroleum residue—the thick heavy oil which remains after the lighter oils have been distilled off—is plentiful and relatively cheap, the South Pacific use over 3,000,000 gallons per annum. And in South America, where coal and oil are expensive, wood is used. A powerful locomotive (Fig. 155, Plate 26) will weigh over 100 tons and develop 1,500 horse-power, so that in the ninety-nine years which have elapsed since the “ Rocket ” achieved success the locomotive has grown considerably. Heavier and more powerful than this it is not likely to be on British railways, because of the limitations imposed by gauge, tunnel, and bridge ; but it may well become more economical. Every year our railways consume 13,000,000 tons of coal, and though we were endowed with a wonderful stock of this fuel it will not last for ever. That is why locomotive engineers have adopted superheating, and it will probably lead to feed water heating, which has already been tried on the L. & S.W.R.