A history of inventions is a history of the progress of mankind, of a progress to which every race may have contributed in primitive times, though all the later contributions have come from a few of the most civilised. Every great invention marks one onward step, as one may see by enumerating a few, such as the use of fire, cooking, metal working, the domestication of wild animals, the tillage of the ground, the use of plough and mattock and harrow and fan, the discovery of plants or trees useful for food or for medicine, the cart, the wheel, the water-mill (overshot, undershot, and turbine), the windmill, the distaff (followed long, long after by the spinning-wheel), the loom, dyestuffs, the needle, the potter’s wheel, the hydraulic press, the axe-handle, the spear, the bow, the shield, the war-chariot, the sling, the cross-bow, the boat, the paddle, the oar, the helm, the sail, the mariner’s compass, the clock, picture-writing, the alphabet, parchment, paper, printing, photography, the sliding keel, the sounding-lead, the log, the brick, mortar, the column, the arch, the dome, till we come down to explosives, the microscope, the cantilever, and the Röntgen rays. [Illustration: THE FIRST SETTLEMENT OF A NEW CITY Many flourishing cities in South Africa, Australia, and America have grown up around the sites where the first gold-seekers pegged out their claims in unexploited territories and began digging for the precious metal. ] The history of the successive discovery, commixture, and applications of the metals, from copper and bronze down to manganese, platinum, and aluminium, or of the successive discovery and utilisation of sources of power--the natural sources, such as water and wind, the artificially procured, such as steam, gas, and electricity--or of the production and manufacture of materials available for clothing, wool, hair, linen, silk, cotton, would show how every step becomes the basis for another step, and how inventions in one department suggest or facilitate inventions in another. Recent discoveries in surgery and medicine, such as the use of antiseptics, tend to improve health and to prolong life; and in doing so, they increase the chances of further discoveries being made. [Sidenote: The Prolonging of Life]