(11)"factory" means any premises including the precincts thereof, wherein twenty or more workers are working, or were working on any day of the preceding 12 months, and in any part of which a manufacturing process is being carried on with the aid of power or is ordinarily so carried on but does not include a mine, subject to the operation of the [Indian Mines Act, 1923] [See now the Mines Act, 1952 (35 of 1952).] (IV of 1923);
