The mechanical arrangements of this new machine equally adapt it to the production of every quality of flour and meal that may be required; to grind and dress finer or coarser, at the pleasure of the operator; to grind, break, or crush only, without dressing; to dress only, without grinding; and may be equally well worked by any number of men or boys, from only one up to twenty, the quality of the products being the same, and the difference only in the quantity. A machine of this kind has now been in active operation for several months, at All Saints' Workhouse, of the Hertford Union, the guardians of which, as well as the master, Mr. Booth, have testified to the facts just mentioned. The framing of this machine is made partly of oak, but all those since constructed are entirely of metal, and combine other improvements, which add to their practical convenience; one of which may be seen in operation at Dr. Allen's excellent establishment for the cure of meutal diseases, at High Beech, near Woodford, Essex.
Sketch of the Patent Flour Maker, as in operation at the All Saints' Workhouse, Hertford.
The following description of an economical horse-mill, for grinding corn, is extracted from a communication in the Franklin Journal for July, 1826, addressed to the farmers and planters of the United States: - a a are the millstones; b the spindle, which supports the upper stone; c a drum upon the spindle made long to prevent the band slipping off; d. a large gin with its shaft, and arms (the lever to which the horse is yoked is not shown); e the bolt of tanned leather, five or six inches broad, with a buckle to give it the necessary tightness. It has not been thought requisite to show the hopper and other necessary appendages, as with these every country mechanic is well acquainted. The larger the diameter of the circle in which the horse travels the better but it should on no account be less than 18 feet; the proportion of the large and small drums must be regulated by the size of the stones and the diameter of the horse-track; and it would in most cases be found best to place the hopper and stones under cover, as in the corner of a barn, and the large gin outside, by which means a large horse-track might be formed, and the mill might likewise be driven in wet weather.
In the mill previously noticed at Dr. Allen's, the usual necessity of a horse-wheel is entirely obviated.
The largest description of corn-mills in the present day are driven either by water, wind, or steam. Watermills were in use amongst the Romans, who established several of them in this island; the mill-course of one of these was discovered some years back near Manchester. Windmills, we believe, were likewise known to them; but the application of steam to this purpose is of very recent date, the first steam-mills established in this or any other country being those erected by Bolton and Watt, near Blackfriars' Bridge, and named the Albion Mills. Whatever be the nature of the driving power, the grinding apparatus is nearly alike in all their mills; and as both windmills and water-mills are employed for various purposes besides that of grinding corn, we propose, under the head Watermill and Windmill, to notice the methods of applying the power derived from these sources, and shall, in this place, give a description of a mill of modern construction, as driven by steam: we should, however, observe, that under the head Barker's Mill, the reader will find a water corn-mill of a simple description.
We shall preface our description of the mill by a short account of the form and the manner of facing the millstones. In order to cut or grind the corn, both the upper and under millstones have channels or furrows cut in them, proceeding obliquely from the centre to the circumference, as shown in the figure on p. 155. The furrows are cut perpendicularly on one side, and obliquely on the other, into the stone, which gives to each furrow an inclined plane, up which the corn is forced by the revolution of the upper stone, which crushes it and bruises it so as to make it grind easier when it falls upon the spaces between the furrows. These are cut the same way in both stones, where they lie on their backs (as above represented), which makes them run crossways to each other, when the upper stone a is inverted, and its furrowed side applied to the furrowed side of b. When the furrows become blunt and shallow by wearing, the running-stone must be taken up, and both stones new dressed with a chisel; and every time that the stone is taken up, a small portion of tallow should be applied to the bush of the spindle.
The grinding surface of the under millstone is a little convex from the edge to the centre, as exhibited in the annexed section at b, and that of the upper stone a little more con-cave; so that they are furthest from one another in the middle, and come gradually nearer towards the edges. By this means, the corn at its first entrance between the stones is only bruised; but as it goes further on towards the circumference, or edge, it is cut smaller and smaller, but at last finely ground just before it comes out from between them.
But although, in the diagram above given, the concavity in the upper stone corresponds with that described by several authors, we believe that the upper stone is not usually cut away to a greater extent beyond the mill-eye than that shown in the figure in the margin p. 151, where the grain is shown entering the mill-eye, and passing through the apertures of the rind c, it enters the cavity underneath; here it gradually gets broken, bruised or coarsely ground, and from thence the finest portion enters between the parallel surface of the millstones, and by degrees passes from between them at their peripheries, being constantly urged outwards by the pressure of the grain in the middle, as well as by the centrifugal force. The rind c is an iron cross let into the upper mill-stone, and is fixed to the spindle e; and the cavity f is filled completely by a bush (generally of wood), in which the spindle revolves. The trundle g, (driven by a cogwheel, which is actuated by the .first mover,) gives motion to the spindle and the upper stone.