Forms: see THIRL v.1 [f. THIRL v.1 + -ING1.]
1. The action of THIRL v.1; piercing, boring.
a. 1225. Ancr. R., 166. Þet, ȝif ȝe weren iðe worldes þrunge, mid a lutel hurlunge [MS. T. hurtlinge: MS. C. þurlunge] ȝe muhten al uor leosen.
1443. Durham Acc. Rolls (Surtees), 713. Cum thirlyng unius shafte, ut patet per bill. 10 li.
2. Coal Mining. See quots. and cf. THIRL1 4.
1686. Plot, Staffordsh., 148. Between the wallings there were ribbs left, and passages through them called thurlings.
1797. Encycl. Brit. (ed. 3), V. 101/1. The workings called rooms, turned off at right angles from the others, the workings called throughers or thirlings, 9 feet wide, wrought through at right angles from one room to another.
1839. Ure, Dict. Arts, 976. Let fig. 840 le a small portion of the pillars, rooms, and thirlings formed in a coal-field.