托福英语 托福阅读 水电的发展.docVIP

小编给你一个美联英语官方免费试听课申请链接： /test/waijiao.aspx?tid=16-73675-0 美联英语提供：托福英语 托福阅读 水电的发展 【1】By the eighteenth century, Britain was experiencing a severe shortage of energy. Because of the growth of population, most of the great forests of medieval Britain had long ago been replaced by fields of grain and hay. Wood was in ever-shorter supply, yet it remained tremendously important. It served as the primary source of heat for all homes and industries and as a basic raw material. Processed wood (charcoal) was the fuel that was mixed with iron ore in the blast furnace to produce pig iron (raw iron). The iron industry抯 appetite for wood was enormous, and by 1740 the British iron industry was stagnating. Vast forests enabled Russia to become the world抯 leading producer of iron, much of which was exported to Britain. But Russia抯 potential for growth was limited too, and in a few decades Russia would reach the barrier of inadequate energy that was already holding England back. 【2】As this early energy crisis grew worse, Britain looked toward its abundant and widely scattered reserves of coal as an alternative to its vanishing wood. Coal was first used in Britain in the late Middle Ages as a source of heat. By 1640 most homes in London were heated with it, and it also provided heat for making beer, glass, soap, and other products. Coal was not used, however, to produce mechanical energy or to power machinery. It was there that coal’s potential wad enormous. 【3】As more coal was produced, mines were dug deeper and deeper and were constantly filling with water. Mechanical pumps, usually powered by hundreds of horses waling in circles at the surface, had to be installed Such power was expensive and bothersome. In an attempt to overcome these disadvantages, Thomas Savery in 1698 and Thomas Newcomen in 1705 invented the first primitive steam engines. Both engines were extremely inefficient. Both burned coal to produce steam, which was then used to operate a pump. However, by the early 1