An unprecedented need for a new source of mechanical power in 18th-century England, capable of functioning at rates beyond horsepower capacity, was met by coal-fueled atmospheric engines. They propelled the country into an industrial revolution. Economic forces exerted by big population changes greatly altered husbandry, industry, and transportation. Acts of Parliament relating to surveying and draining of lands, and construction of roads and canals multiplied six-fold in the second half of the century.

William Smith, a land drainer and mineral surveyor, in the course of canal-building in the east Somersetshire coal field, discovered and then exploited the stratigraphical principle of natural order and regularity in fossil occurrence--"each Class assigned to its peculiar Stratum." He had employed the prime stratigraphical principle of order and regularity among the strata, drawing on colliers' lore and probably a published record, during underground surveys of the mines (1791-1793). Seventy-two years earlier a wide-ranging description of the same coal field by John Strachey had illustrated a definitive succession, strike, dip, subcrop, outcrop, concealed faulting, and unconformity, and established by direct measurement underground that--"the Strata lye shelving and regular, and obser e a regular course." This account codified the colliers' tradition. A century later the knowledge it contained, unchanged in principle but enlarged in scope, achieved generality in the academic realm.