in the middle ages, it might be done with clubs wielded by hand, striking the cloth in a trough. The significant change came in the eleventh century, when these clubs were taken out of human hands and were powered instead by a water-wheel. A pair of heavy wooden hammers, several feet long, went up and down on the cloth, activated alternately by a trip mechanism powered directly from the rotating water-wheel. As the wheel turned so did its spindle. On the extended spindle there was often attached another, smaller, wheel, also mounted in a vertical axis and made of solid wood. This solid wheel lay between the two fulling hammers and as the wheel turned, two wooden tappets projecting on either side tripped the hammers alternately. In its various versions, it was a brilliantly simple utilisation of the water-wheel, which was so familiar a part of the medieval scene. 4 Water not only gave the power; it was also an essential element in the cleansing process. This double need for water meant that the windmills which were introduced into Britain in the late-twelfth century powered only stones to grind corn and were never used for fulling. Although in 1743 an ingenious Dutchman demonstrated how a windmill could full, this is a mere curiosity. 5 In all normal circumstances mechanised fulling, unlike mechanised flour- making, was entirely dependent on a good water supply. In an influential passage, Miss Carus-Wilson defined the typical sites of fulling-mills, and therefore of the cloth industry, as being 'on the swift, clear streams of the north and west, in remote valleys far beyond the bounds of the ancient chartered cities of the plains'. 6 In 1944 Mr. R. A. Pelham published the first distribution map of fulling-mills in England and Wales and followed this with a much more densely populated map in 1958. On the basis of these maps, Mr. Pelham, like Miss Carus-Wilson, concluded that narrow, steep-sided valleys were both most suitable and most 4 Cf. Carus-Wilson, op. cit., pp. 40-43 (185 89); E. Kilburn-Scott, 'Early Cloth Fulling and its Machinery', Transactions ofNewcomen Society for the Study of the History of Engineering and Technology, XII for 1931-2 (1933), 30-52; R. Patterson, 'Spinning and Weaving' in C. Singer et al. (eds.), A History of Technology: the Mediterranean Civilizations and the Middle Ages, c. 700 B.C. to c. A.D. 1500 (Oxford, 1957), II, 214-20. For a description of a Welsh fulling-mill, still in working order half-a-century ago, cf. I. C. Peate, 'A North Cardiganshire Woollen Yarn Factory', Y Cymmrodor, XXXIX (1928), 77 78 and fig. I facing p. 89. For Esgair Moel, re-erected in the Welsh Folk Museum at St. Fagans, see J. G. Jenkins, Esgair Moel Woollen Mill (Cardiff, 1975). 5 Kilburn-Scott, op. cit., p. 51. The wind-powered fulling-mill was first described in J. Van Zyl and J. Schenk, Groot Algemein Moolen-Boek (Amsterdam, 1734), plates 16-19. 6 Carus-Wilson, op. cit., p. 51 (198). 7 R. A. Pelham, 'The Distribution of Early Fulling-Mills in England and Wales', Geography, XXIX (1944), 52 56; idem, Fulling Mills (Society for Protection of Ancient Buildings, Wind and Watermill Section, pub. V ), plate IV facing p. 9.