| 释义 |
topit|ˈtɒpɪt|
[app. f. phrase top it (top v.1).]
An attachment at the top of a boring rod by means of which it is withdrawn.
1839Ure Dict. Arts 966 The boring tools..13. The topit, or top-piece. Ibid., The runner, for taking hold of the topit. 1883Gresley Gloss. Coal Mining, Topit, a kind of bracehead, but much smaller, which is screwed on to the top of boring rods when withdrawing them from the hole. It is attached to a rope worked from a jack-roll. |