All About Engines

Raising Steam $7 away in all directions, forming a mound of fuel which is more completely burned as it approaches the sides of the grate, though there is no grate in the ordinary sense of the word. In a case known to the writer a set of four old- fashioned Lancashire boilers, requiring six men and three boys to manage them, have been replaced by Babcock and Wilcox boilers fitted with chain-grate mechanical stokers and other improvements. In accordance with modern practice the coal is con- veyed to the boiler house by an endless belt, weighed, and delivered into the furnace without being touched by hand. Another travelling belt running under- neath the boilers collects the ashes and conveys them to a tip. And the point to which heavy and un- pleasant labour is avoided is indicated by the fact that the new plant is controlled by one man and one boy ! Mechanical stokers are used only with land boilers, and not with locomotives or on board ship, where the efficiency, in so far as it is determined by the method of stoking, depends entirely upon the intelligence of the man in charge. Forced Draught No one needs to be told that a fire burns more fiercely the more rapidly air passes through the bed of fuel. The use of the bellows to revive a dying fire in the household grate, or blocking up the front with a newspaper so that all the air which enters the chimney must pass through the fuel, are everyday