Local weavers specialised in the production of kersey, a hardwearing and inexpensive woollen fabric that was often used for military uniforms; by the 16th century Halifax and the surrounding Calder Valley was the largest producer of the material in England. In the final part of the manufacturing process the cloth was hung outdoors on large structures known as tenterframes and left to dry, after having been conditioned by a fulling mill. Daniel Defoe wrote a detailed account of what he had been told of the gibbet's history during his visit to Halifax in Volume 3 of his "A tour thro' the whole island of Great Britain", published in 1727.