Because, in the meantime, many skills required special knowledge, other tradesmen were gradually employed in mining and in the pits: initially metalworkers and, later, electricians.
en.wikipedia.org The new owner had the castle and an infrastructure of key houses (such as smithy, bakery, peat-cutter, brewery, etc.) were built up around it and appropriate tradesmen were attracted.
en.wikipedia.org The towns were chiefly inhabited by tradesmen and mechanics, who seem in those days to have been of servile, or very nearly of servile condition.
en.wikipedia.org Additional factors in the time and cost increases were a lack of tradesmen skilled in naval construction, overly bureaucratic management, and low labour productivity.
en.wikipedia.org The medical ward now has 17 private rooms and one twin bed room, all of which have been refurbished by local tradesmen.
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