There were two types of water mill known to the ancients: the horizontal wheel, called the Greek or Norse mill, and the vertical wheel, or Roman mill. The Greek mill was thought to be an invention of the Greeks, because the earliest known description of it is by a Greek writer, Antipater of Thessalonica, about 85 B.C. It was either borrowed from the Greeks by the Northern people, or reinvented, and introduced into Britain by the Saxons. I think, however, that there is good reason for believing that this type of water mill is of much greater antiquity than the year 85 B.C. It is well known that the Chinese were conversant with water-motors from a very early period; that the horizontal wheel water mill was so widely distributed as to be found in Ireland, Scotland, Shetland, Orkney, Sweden, Norway, France, Spain, Italy, Roumania, the Morea, the Holy Land, and throughout Asia Minor and Western China; and as the western plains of China adjoin the great central plateau of Asia, from whence the earliest migrations of a civilized race are said by some writers to have proceeded towards the west, it seems probable that the use of this type of water mill was known to the inhabitants of central Asia, and passed with successive hordes of emigrants into Europe.

In the Ulster Journal of Archaeology are descriptions of water mills with horizontal wheels seen in Shetland, the Hebrides, the Isle of Man and Ulster, but the simplest description which I have found is that by Sir Walter Scott, of a mill which he saw near Lerwick when he accompanied the Commissioners of Lighthouses on their visit to the lighthouses in Scotland and the Northern and Western Islands. He writes: “ The little lake of Cleik-him-in is divided by a rude causeway from another small loch, communicating with it by a sluice for the purpose of driving a mill; but such a mill! The wheel is horizontal, with the cogs turned diagonally to the water; the beam stands upright, and is inserted in a stone quern of the old-fashioned construction. This simple machine is enclosed in a hovel the size of a pigstye, and there is the mill! There are about 500 such mills in Shetland, each incapable of grinding more than a sack at a time.”