How did England control trade in the 18th century?

I know that this is probably a digression from the topic of today’s lecture, but it is worth noting that although England no longer ruled her former colonies in the eighteenth century she controlled trade with them by selling products so cheaply that it was not possible for the new countries to manufacture and compete with English prices. To maintain this favorable balance of trade, England went to fantastic lengths to keep secret the advance manufacturing processes upon which such a monopoly depended.
    Enterprising Americans made all kinds of ingenious attempts to smuggle drawings for the most modern machines out of England, but it was an Englishman, Samuel Slater, who finally succeeded.
    Determined to talk nothing in writing, Slater memorized the intricate designs for all the machines in an English textile mill, and in partnership with Moss Brown, America had changed from a country of small farmers and craftsmen to an industrial nation in competition with England.