All About Engines

Fuel and Its Problems 331 most out of them. The boilers, steam-pipes, and cylinders of a small engine have larger surfaces in proportion to their volumes than large engines, and they waste more heat even under the most skilful management. An engine working only part time is less efficient than one working full time, and a man that cannot fully employ an engine should not be allowed to have one. He should purchase electrical power or gas power from a large source of supply. (See Fig. 181, Plate 31.) The average amount of coal used per horse-power per hour in this country is 5 lb. or 6 lb., yet the great turbine built by Messrs. Parsons for Chicago, which was described in Chapter VI., requires less than 1 lb. If the consumption of the average engine is 5 lb. to 6 lb. the consumption of many must be much higher. As about 80 million tons of coal per annum are used for producing power, a reduction of the average con- sumption to, say, 3 lb. would save about 30 million tons per annum. And at 10s. a ton at the pit mouth this would amount to £15,000,000 a year. Just think, too, of the reduction of wear and tear on the railways, and the saving of wages which are now merely paid for moving stuff which ought not to need moving. If the men engaged in this, and the colliers who would also be liberated, went on the land, more food would be produced at home, we should import less, and we need not export 76 million tons of coal as we did in 1913. We are not so well off that we can afford to let it go unnecessarily. Germany has more than we have, and is raising it at