When Vitiges besieged Rome, A. D. 537, he cut off the supply of water from the aqueducts which fed the canals. Deprived of power from this source, Belisarius placed boats on the Tiber and on them erected mills. These consisted of two boats moored 2 feet apart, and, suspended on its axis between them, a water-wheel which was driven by the force of the current and put in motion the stones for grinding the corn. This appears to have been the origin of "floating mills." Roman mill (ffi. 3, fig. 2) in operation at the begin ning of the Christian era is described by Vitruvius as follows. Around the fronts of the wheels are affixed pinncr (A), which, when impelled by the current of the river, force the wheel to revolve. By these means the hydromylee (water-mills) are turned. On the water-wheel axis is a toothed tympanum (B) turning with the water-wheel. Adjoining this tympanum a larger one (D), also toothed, is placed horizontally; in this is contained an axis (E) having at its upper end an iron dovetail (F), which is inserted in the millstone (G); thus the teeth of the tympanum (B), that is in cluded on the axis impelling the teeth of the horizontal tympanum (D), cause the rotation of the millstone, to which the suspended hopper (II) furnishes the grain, and by the same rotation the meal is ejected. The expression aquimolum molendini, found in one of the charters, perhaps indicates that the mill referred to was a grinding-mill proper, and that as early as the eleventh century water-mills were used not only for grinding corn, but also for other purposes, although hand- and cattle- mills were employed for a long time after the erection of water-mills.
The mills found on Mount Lebanon and on Mount Carmel at the beginning of the eighteenth century nearly resembled those found in many parts of Italy; they were exceedingly simple in construction. To the same axis were fastened the millstone and the motor-wheel, the latter consisting of eight boards shaped like shovels and placed across the axis. The water, falling upon these boards, turned them round and put in motion the millstone, over which the corn was poured.
The Algerian 11'a/el.-mill shown in Figure 3 (pi. is an ingenious con trivance. Beneath a timber platform supporting the millstones is a funnel shaped boarded chamber for the wheel, which is driven by water from a pipe conduit. The runner-stone, which is of less diameter than the bed-stone, is rotated by the water-wheel spindle. The flour is discharged around the bed-stone and falls on a clay floor, from which it is gathered into sacks.
Persian the frontier between the Persian province of Khorassan and the Akhal-Tekin oasis there are some very curiously constructed grist-mills. Below an elevated lake a series of dykes is so built as to cause the water to fall over long steps, and at each place of descent is fixed a grist-mill with its turbine, through which the water passes. The mill-house (fig. 5) is a sort of mud hut lighted only by feeble lamps. The turbine turns the horizontally arranged stones, over which hangs a bag of pyramidal form, serving as a hopper; from an open ing in the lower stone the flour runs out upon the floor, whence it is taken up by a scoop.
of the British Johnson, in ]cis Jourmey to the Western Islands of Scotland, says, " There are water-mills in Sky and Raasa, hut where they are too far distant the housewives grind their oats with a quern or hand-mill, which consists of two stones about feet in diameter. The lower is a little convex, to which the concavity of the upper must be fitted. In the middle of the upper stone is a round hole, and on one side is a long handle. The grinder sheds the corn gradually into the hole with one hand, and works the stone around by the handle with the other. The corn slides down the convexity of the lower stone, and by the motion of the upper is ground in its passage." Water-mills were formerly common in Great Britain and Ireland, and continued in use well into the present century. Sir Walter Scott, in his voyage to the Shetland Islands in 1Sr4, visited a mill which he de scribed as follows: " In our return pass the upper end of the little lake of Cleik-him-in, which is divided by a rude causeway from another small loch, communicating with it, however, 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 about the size of a pig-stye, and there is the mill. There are about five hundred such mills in Shetland, each incapa ble of grinding more than a sack at a time." 1Vorse —On Plate 3 (fig. 4) is represented a perspective of one of the Shetland water-mills known as "Norse mills." Suspended from the roof by straw ropes is the hopper, which receives the necessary vibratory motion for feeding the stones by means of a stone, fastened to a cord, lying loosely on the surface of the runner millstone, whose roughness as it goes round makes the cord irregularly tight and slack as the result of its varying drag. The millstones are rarely more than 3 feet in diameter; the meal is delivered on the floor around the stones within a space laid off by a ledge of wood. The Norse mill is usually the property of a township or of several contiguous townships. All the families of the community have the use of the mill, and when meal is required carry their corn to the mill and are their own millers.
Mexican Iftaier- mill. —What may now be called the " old-time " machin ery of milling in Sonora, Mexico, consisted of single-run millstones, usu ally manufactured from the hard rock of the country; they were driven by the mountain-streams. The mill-house was usually a small adobe building of a single room, in which the stones were placed without a curb. The Mexican miller was ingenious, but not inventive. The wheat, with its admixture of stones, dirt, etc., was placed in the hopper, over the eye of the stone; the mill was then started, and left by the miller to its own devices. The result was a perfect cyclone of " chess " until the feed was exhausted, when the miller returned and swept up the flour.