1) In coal-mining contexts this verb had the same meaning as ‘to hole’.
Commenting on a case from 1713 W.B. Trigg said that ‘the defendant paid 30s for hollowing to the new pitt’, which suggests that this gallery linked the two shafts and was intended as a ventilation gate. He employed the term ‘hollow work’ for when colliers or sinkers broke through into ground where the coal had already been mined: 1815 ‘the coal had been worked from the Cold Harbour pit and the hurrying road led … from the hollow work to Cold Harbour pit’. Gresley defined ‘hollows’ as old abandoned workings. In Colsterdale, the term ‘old man’ was used in such cases by both coal-miners and lead-miners: 1707 The field is the hardest I have worked … but should last long after I am dead. The Old Man has worked the field so it was either drowned out or nipped.