air-head

See also: airhead

English

Etymology

From air +‎ head.

Pronunciation

• (Received Pronunciation) IPA^(key): /ˈɛːhɛd/

• Audio (RP)

  (file)

• (General American) IPA^(key): /ˈɛɹˌ(h)ɛd/

Noun

air-head (plural air-heads)

1. (mining, archaic) A horizontal channel providing ventilation in a mine.
   • 1839, Andrew Ure, “PITCOAL”, in A Dictionary of Arts, Manufactures, and Mines: Containing a Clear Exposition of Their Principles and Practice, London: Printed [by A[ndrew] Spottiswoode] for Longman, Orme, Brown, Green, & Longmans, […], →OCLC, page 990:

     A narrow gallery, termed the air-head, is carried in the upper part of the coal, in the rib walls, along one or more of the sides. In the example here figured, it is carried all round, and the air enters at the bolt-hole e. Lateral openings, named spouts, are led from the air-head gallery into the side of work; and the circulating stream mixed with the gas in the workings, enters by these spouts, as represented by the arrows, and returns by the air-head at g, to the upeast pit.

   • 1847 April 17, “Institution of Civil Engineers”, in The Literary Gazette and Journal of Belles Lettres, Arts, Sciences, &c., number 1578, London: Printed by Henry Silverlock, […]; published for the proprietor, at the Literary Gazette office, […], →OCLC, page 300, column 3:

     [T]he method introduced by Mr. [Benjamin] Gibbons in Staffordshire of exhausting the foul air, by air-heads cut in the lop of the coal, connected with a channel in the side of the shaft, terminating in a chimney on the surface, was received as a decided improvement upon the ordinary system in use in that coal-basin, where the extraordinary thickness of 30 feet of the vein coal renders a peculiar plan indispensable.

   • 1851 April 23, Benjamin Gibbons, “On the Ventilation of Mines”, in Institution of Mechanical Engineers. Proceedings, Birmingham: Published by the Institution [of Mechanical Engineers], […], →OCLC, page 13:

     [T]he mine then becomes exposed to the most fearful results, where the workings have been opened, by the Air being driven backwards along the Airhead into the reservoirs of Gas formed in the upper cavities of the workings, and issuing into the Gate-road charged with the Gas to the firing point, causing an explosion, of which many familiar instances might be adduced.

   • 1861, [Edward Headlam] Greenhow, “[Appendix.] IV. Dr. Greenhow’s Second Report on Districts with Excessive Mortality from Lung-diseases.”, in Public Health. Fourth Report of the Medical Officer of the Privy Council. With Appendix (Reports from Commissioners (Session 6 February – 7 August 1862); 6 (Emigration Commission; Factories; Mines; Public Health)), volume XXII, [London: Her Majesty’s Stationery Office?], published 11 April 1862, →OCLC, page 157:

     The ventilation of the mines near Wolverhampton is said to have been much improved through the agency of Her Majesty's Inspectors, especially as regards the more regular and better construction of "air-heads" or ventilating channels.

Alternative forms

• airhead