The History of Waterpower
gg是什么意思Moving water was one of the earliest energy sources to be harnesd to reduce the workload of people and animals. No one knows exactly when the waterwheel was invented, but irrigation systems existed at least 5,000 years ago, and it ems probable that the earliest waterpower device was the noria, a waterwheel that raid water for irrigation in attached jars. The device appears to have evolved no later than the fifth century B.C., perhaps independently in different regions of the Middle and Far East.travelling
The earliest waterpower mills were probably vertical-axis mills for grinding corn, known as Nor or Greek mills, which em to have appeared during the first or cond century B.C. in the Middle East and a few centuries later in Scandinavia. In the following centuries, increasingly sophisticated waterpower mills were built throughout the Roman Empire and beyond its boundaries in the Middle East and northern Europe. In England, the Saxons are thought to have ud both horizontal0 and vertical-axis wheels. The first documented English mill was in the eighth century, but three centuries later about 5,000 were recorded, suggesting that every ttlement of any size had its mill.gero
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Raising water and grinding corn were by no means the only us of the waterpower mill, and during the following centuries, the applications of waterpower kept pace with the developing technologies of mining, iron working, paper making, and the wool and cotton industries. Water was the main source of mechanical power, and by the end of the venteenth century, England alone is thought to have had some 20,000 working mill. There was much debate on the relative efficiencies of different types of waterwheels. The period from about 1650 until 1800 saw some excellent scientific and technical investigations of different designs. They revealed output powers ranging from about 1 horpower to perhaps 60 for the largest wheels and confirmed that for maximum efficiency, the water should pass across the blades as smoothly as possible and fall away with minimum speed, having given up almost all of its kinetic energy. (They also proved that, in principle, the overshot wheel, a type of wheel in which an overhead stream of water powers the wheel, should win the efficiency competition.)
But then steam power entered the scene, putting the whole future of waterpower in doubt. An energy analyst writing in the year 1800 would have painted a very pessimistic p
icture of the future for waterpower. The coal-fired steam engine was taking over, and the waterwheel was fast becoming obsolete. However, like many later experts, this one would have suffered from an inability to e into the future. A century later the picture was completely different: by then, the world had an electric industry, and a quarter of its generating capacity was water powered.
The growth of the electric-power industry was the result of a remarkable ries of scientific discoveries and development in electrotechnology during the nineteenth century, but significant changes in what we might now call hydro (water) technology also played their part. In 1832, the year of Michael Faraday’s discovery that a changing magnetic field produces an electric field, a young French engineer patented a new and more efficient waterwheel. His name was Nenoit Fourneyron, and his device was the first successful water turbine. (The word turbine comes form the Latin turbo: something that spins). The waterwheel, unaltered for nearly 2,000 years, had finally been superded.
Half a century of development was needed before Faraday’s discoveries in electricity wer
e translated into full-scale power stations. In 1881 the Godalming power station in Surrey, England, on the banks of the Wey River, created the world’s first public electricity supply. The power source of this most modern technology was a traditional waterwheel. Unfortunately this early plant experienced the problem common to many forms of renewable energy: the flow in the Wey River was unreliable, and the waterwheel was soon replaced by a steam engine.rook
From this primitive start, the electric industry grew during the final 20 years of the nineteenth century at a rate ldom if ever exceeded by any technology. The capacity of individual power stations, many of them hydro plants, ro from a few kilowatts to over a megawatt in less than a decade.
Paragraph 1: Moving water was one of the earliest energy sources to be harnesd to reduce the workload of people and animals. No one knows exactly when the waterwheel was invented, but irrigation systems existed at least 5,000 years ago, and it ems probable that the earliest waterpower device was the noria, a waterwheel that raid wat三年级作文补习
er for irrigation in attached jars. The device appears to have evolved no later than the fifth century B.C., perhaps independently in different regions of the Middle and Far East.
1. The word “harnesd” in the passage is clost in meaning to
O known
O depended on
O recognized
O utilizedcan u speak english
2.In paragraph 1, uncertainty is expresd about all of the following aspects of the early development of waterpower EXCEPT
O when exactly the very first waterpower devices were invented
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