We shall now give a description of a double corn mill, of the most common sort. Sec Plate Mill-Work.
A B is a water-wheel, which is over shot 11 feet 6 inches in diameter, with 36 buckets to receive the water, whose weight puts it in motion. The wheel is fixed upon a very strong axis or shaft, C, one end of which rests 'on D, and the other on E, within the mill-house. On this shaft or axis, and within the mill-house, is a wheel, F, about 8 or 9 feet in diameter, having cogs, 72 in number, all round, which work in 23 upright staves, or rounds of a trundle, C, fixed on a strong upright shaft, T, which has a cog-wheel, W, with 56 teeth fixed on its upper end, to give a rotatory motion to the two small trundtes,gg, on each side, and which are exactly similar to each other. Each trun dle is fixed upon a strong iron axis, called the spindle, the lower end of which turns in a brass toot fixed at H, in a horizontal beam, II, called the bridge-tree; the up per end of the spindle turns in a wooden bush, fixed into the nether millstone, which lies upon the beams in the floor, I. The top of the spindle above the bush is square, and goes into a square hole in a strong iron cross, a, b, called the rynd, under which, and close to the bush, is a round piece of thick leather upon the spindle, which it turns round at the same time as it does the rynd. The rynd is let into grooves in the under surface of the running millstone, K, and so turns it round in the same time as the trundle, g, is turned round by the cog-wheel, W : this millstone has a large hole quite through its middle, called the eye of the stone, through which the middle part of the rynd and upper end of the spindle may he seen, whilst the four ends of the rynd lie below the stone in their grooves. One end of the bridge-tree, which sup ports the spindle, rests upon the wall, whilst the other is let into a beam called the brayer, L, M. The brayer rests in the wall at L; the other end, M, hangs by a strong iron rod which goes through the floor, I, and has a screw-nut at its top ; by the turning of which nut the end, M, of the brayer is raised or depressed at pleasure, and consequently the bridge tree and the upper millstone. By this
means the upper millstone may be set as close to the under one, or raised as high from it, as the miller pleases. The nearer the millstones are to each other the finer the corn is ground, and the more remote from one another the coarser The up per millstone is inclosed in a round box, which does not touch it any where, and is about an inch distance from its edge all round. On the top of this box stands a frame for holding the hopper, P, to which is hung the shoe, Q, by two lines fasten ed to the hinder part of it, fixed upon hooks in the hopper, and by one end of the string, R, fastened to the forepart of it ; the other end being twisted round a pin, in a convenient place, within the reach of the miller; as the pin is turned one way, the string draws up the shoe closer to the hopper, and so lessens the aperture between them ; and as the pan is turned the other way, it lets down the shoe and enlarges the aper ture.
If the shoe is drawn up quite to the hopper, no corn can fall from the hopper into the mill ; if it is let clown a little, some will fall, and the quantity will be more or less, according as the shoe is more or less let down ; for the hopper is open at the bottom, and there is a hole in the bottom of the shoe, not directly under the bottom of the hopper, but nearer to the lower end of the shoe, over the middle eye of the mill-stone. There is a square on the top of the spindle, on which is put the feeder, f ; this feeder, as the spindle turns round, jogs the shoe three times in every revo lution, and so causes the corn to run con down from the hopper, through the shoe, into the eye of the millstone, where it falls upon the top of the rynd, and is, by the motion of the rynd and the leather under it, thrown below the upper stone, and ground between it and the lower one. The violent motion of the stone creates a centrifugal force in the corn going round with it. by which means it gets further and flu ther from the centre, as in a spiral, in every revolution, until it is quite thrown out, and being then ground, it falls through a spout., called the mill-eye, into a trough. placed to receive it.