Develofiment of a Hollowed Stone into a the course of time the cavity of the stationary stone became deepened, and a handle was attached to the ball, whereby there resulted the mortar and pestle; so, again, when the upper stone was enlarged and provided with a central hole and a handle, by which the stone was rotated on a peg or pivot in the lower stone, there was produced the quern or hand-mill, which is the germ of the modern flour-mill.
Ancient consist of a single pair of stones of similar form, with fitting surfaces, one of which (the upper stone or runner) is caused to revolve in near contact with the other (nether or bed-stone), the grain being ground between the two while passing in a direction from the centre to the circumference. By both ancient and modern writers the term " corn-mill " has been applied to a mortar-and-pestle mill as well as to a mill composed of a pair of stones, one of which is fixed while the other revolves. In connection with the earliest Scripture reference to the "mill" (Num. xi. 8) there is mention of the use of the "mortar," both of which implements were employed for reducing manna to powder. We have no description of the form of the mill in which the manna was "ground," hut we may presume that revolving millstones were employed. At an earlier date the " king of Salem brought forth bread and wine " (Gen. xiv. 18), from which we may infer that mills for grinding grain and machines for expressing the juice of grapes were employed in the earliest times. This is the first Biblical reference to the use of machinery for the preparation of food.
Though there is a difference of opinion as to the size and weight of the stones, it is evident that the running stone must have been sufficient for crushing the grain; this weight, however, can be obtained in a stone of small as well as in one of large diameter, if the thickness be propor tioned to the diameter—a well-known fact in milling-mechanics.
Considering its construction in detail, the mill of the ancient Hebrews may be regarded as a very simple machine. A hand-mill of twin-stones cannot exist in many forms nor be complex in its essential features, since it is composed chiefly of a revolving part, called by the Hebrews a "chariot" and by the Arabs a "rider;" it is turned by the hand over a nether or sta tionary part, whose upper surface may be flat or convex, and this surface may also be even or grooved, but must always be hard and porous, for preserv ing the cutting-edges. In either case the central orifice of the upper stone
may vary in shape, and yet fulfil its office equally well. If the hole be conical, it can be more easily cut, and will serve as a hopper to receive and hold the little charge of grain to be ground. The pivot upon which the rider turns may have been of stone, wood, or metal, rudely shaped or cunningly carved, fitting a guiding-bar or not, according to the ingenuity and skill of the millwright who built it ; and the handle may also have been a mere wooden peg stuck loosely or fitting tightly ill a hole in the stone, or it may have been a smooth, round handle of metal firmly fixed therein, probably covered with a loose leathern sleeve or shield of metal, to prevent abrasion of the hand—a refinement of mechanism easily born of necessity from painful experience, as the labor of turning it was mani festly severe, and necessarily required daily repetition, to meet the con stantly recurring demands for bread.
In course of time, that the mill might be driven by cattle, shafts were added for turning the heavy pestle. At first the mills had no spouts for conducting the corn to the eye of the upper stone, and were without troughs for receiving the meal as the grinding progressed. Primarily, the human hand served the purpose of a hopper, and every woman employed at a mill was a miller. The hopper was a late invention, referred to, it is said, only in the Mishna, where, also, mention is made of a miller, indi cating that grinding corn vas recognized as a distinct occupation ; but if millstones with central openings had been previously used, the hopper, as a separate invention, was thereby anticipated.