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An Encyclopedia of the History of Technology part 57

An Encyclopedia of the History of Technology part 57. This one of a kind encyclopedia presents the entire field of technology from rudimentary agricultural tools to communication satellites in this first of its kind reference source. Following an introduction that discusses basic tools, devices, and mechanisms, the chapters are grouped into five parts that provide detailed information on materials, power and engineering, transportation, communication and calculation, and technology and society, revealing how different technologies have together evolved to produce enormous changes in the course of history | PART THREE TRANSPORT for the same purpose and coastal views and outlines of hills are usually to be found on charts or in sailing directions. Until the late eighteenth century in fact specialized marks were rare and such views often show also church towers to mention the most obvious. The relative scarcity of proper lights incidentally casts a different angle on the many stories of false lights used by wreckers for a deep sea seaman would be far more likely to avoid a light than to steer for it. As in other matters the first lights were established by the ancients usually in the form of towers upon the top of which a coal or wood fire was kept burning the Pharos of Alexandria being the best known while Roman towers survive at Corunna and Dover. Similar methods continued throughout the Middle Ages the fire usually being in an iron brazier. Most of these lights were on headlands or offshore islands but their distribution was purely fortuitous sometimes being the work of a public-spirited local notable at other times perhaps due to a religious foundation or to a nearby port s corporation. Passing ships could be charged light dues so that the profit motive could also bring lights into being. The efficiency of all however could be very variable. In England the Corporation of Trinity House was given powers in the sixteenth century to supervise matters nautical including the provision of lights. From the eighteenth century a steady improvement began. In the same way that it became possible to build breakwaters to withstand the sea so lighthouses could be built on outlying rocks the Eddystone being the classic example with the first house swept away the second burned down and the third with its interlocked stonework still extant though now moved ashore. Better illuminants were found oil paraffin gas and elaborate systems of mirrors and lenses were brought into use to give better direction and power to the light. The provision of lights was taken over by official bodies .