Water was the main source of mechanical power, and by the end of the seventeenth century, England alone is thought to have had some 20,000 working mills.
水是机械动力的主要来源，而到了17世纪末，人们认为仅英格兰就有2万个左右的工作磨坊。
2
Some scholars argue that the concentration of water within the urban core of these sites provided a centralized source of political authority for Maya elites based largely on controlled water access.