The Development of Material Knowledge 345 AN EARLY WEAVING MACHINE {From an engraving by W. Hincks in the British Museum) in the time distances of one place from another. They are merely- one aspect of a much profounder and more momentous enlargement of human possibility. The science of agriculture and agricultural chemistry, for instance, made quite parallel advances during the nineteenth century. Men learnt so to fertilize the soil as to produce quadruple and quintuple the crops got from the same area in the seventeenth century. There was a still more extraordinary advance in medical science ; the average duration of life rose, the daily effi- ciency increased, the waste of life through ill-health diminished. Now here altogether we have such a change in human life as to constitute a fresh phase of history. In a little more than a century this mechanical revolution has been brought about. In that time man made a stride in the material conditions of his hfe vaster than he had done during the whole long interval between the palaeolithic stage and the age of cultivation, or between the days of Pepi in Egypt and those of George III. A new gigantic material framework for human affairs has come into existence. Clearly it demands great readjustments of our social, economical, and political methods. But these readjustments have necessarily waited upon the develop- ment of the mechanical revolution, and they are still only in their opening stage to-day.
