cockermeg

A cockermeg is a framework of wooden pit props arranged to support the roof and sides of a coalface during extraction. It consists of two or more vertical props (typically timber) with horizontal cross-members or caps, built directly against the coal seam to prevent collapse as coal is removed from below. The structure remains in place only as long as that particular section of the face is being worked; once the coal is extracted from that area, the cockermeg is dismantled and the timber is often moved forward to support the next working area.

The arrangement varies depending on seam height, roof condition, and the rate of extraction. In thicker seams, multiple cockermeg structures may stand side by side along the coalface, sometimes connected by additional props or cross-bracing to form a more rigid support line. The props themselves are normally softwood poles, ranging from 4 to 8 inches in diameter, cut to length on site or brought in pre-cut from the pit timber yard. The cap or cross-member sits on top of the vertical props and bears the immediate weight of the overlying coal and strata.

Ground pressure, water infiltration, and prop decay cause cockermeg failure. Timber that has been in the pit for months can rot or lose strength; a prop that appears sound may snap suddenly under load, particularly in wet conditions or where coal dust and moisture have weakened the wood. When a cockermeg fails, the coal above may subside or the face may slump, trapping workers or forcing an evacuation of that section. Regular inspection and replacement of props is therefore essential, and many pits employed specialist timberers whose job was to erect, inspect, and maintain cockermeg structures.

The term cockermeg appears to be a regional or dialect word, with usage concentrated in British coalfields. The word is obscure in origin; some sources suggest it may relate to an old word for a support frame or cage, though the exact etymology is not well documented. By the mid-twentieth century, as steel arches and other mechanized supports became available, cockermeg remained in use in smaller or shallower seams where timber was still adequate and steel was not justified by cost or ease of installation.