All About Engines

34° All About Engines which has gone on and is going on in Great Britain will be repeated in other lands. They may learn from our experience, but the process of exhaustion, though slower, is inevitable. Are the resources of human knowledge equally limited ? Has man struggled all these years to master Nature only to be beaten in the end ? When he has swept bare the forests, won the last seam of coal, drained the last oilfield of its precious liquid, will lie then be reduced to his former dependence upon the sun for light and warmth, and upon muscle and nerve for things of use and beauty which are not found ready made ? By no means. So long as the sun shines, and the wind blows, and the rain falls he can wring a sustenance from the soil and hold at bay the savagery which would otherwise enfold him. But for this he must have power. How, then, is he to obtain it ? The exact way in which petroleum has been formed in Nature’s vast manufactory is not fully understood, but all solid fuel is of vegetable origin. So long as plants will grow there will be a source of fuel. It does not follow, however, that it will be of timber. Forest trees are of slow growth, and half the world devoted to forestry would fail to keep the factories of the other half going. But all plants con- tain cellulose, which they build up out of the carbon dioxide and moisture of the air. When cellulose is fermented it forms ultimately sugar as one of its products ; when sugar is fermented it forms alcohol;