Air-head

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.

[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.

[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.

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.