1) To ‘loose’ a coal-pit was to carry out all the work that was necessary for coal to be ‘won’ there, with proper access and freedom from water.
1633 to loose or enable anyone else to get coals by means of the pits and soughs so made, Northowram
1733 convenient for the loosing and draining a coal myne, Whitley
1754 Toftshay coalmine … cannot be loosed without buying some coals which belong to the two Cordingleys [that is in the adjoining grounds]
1766 no sough was to be cut … so far to the extreme part of the grounds as to loose the works or coal of Mr Lister, Halifax. In his history of mining in Halifax, W.B. Trigg used the word ‘water-loose’ as an alternative to ‘watergate’ or ‘sough’ but the noun was absent from the documents that he quoted and may have come into use in the nineteenth century, c.f. 1760-1 Jos Cowburn and Jas Barker for feying and loosing the Water, Tong.