All About Engines

Fuel and Its Problems 333 (c) The stand-by losses are small. Very little coal is used when the engine is not draw- ing gas from the producer, and when the engine is needed it can be started up in a few minutes, while some time is required to get up steam in boilers. These advantages were so clear, even in 1880, that the total replacement of steam by gas within fifty years was prophesied by eminent engineers. What they did not foresee, however, was the diffi- culty of building very large gas engines, the invention of the turbine with its economy of steam and its evenness of effort, and the need for this evenness of effort in driving electrical machinery. Moreover, the enormous growth in the demand for power destroyed real competition even for small sizes, and kept en- gineers busy making both classes of engine. The cheapness of coal and the small proportion which the cost of power bears to the cost of manufacture, also prevented manufacturers from exerting them- selves in the direction of economy. Gas can, of course, be burnt in other ways than in the cylinder of an engine. It is used very exten- sively, not only for domestic heating, but also for furnaces in the factory. But until recently attempts to use it for raising steam have not been very success- ful. The amount of heat obtainable from any fuel is proportional to the weight burnt, and gases are so light in comparison with solids that they require a large furnace. The fierce flame playing directly upon the plates is also objectionable because it leads to