Practical Essays on Mill Work, and other Machinery, and on the Shafts of Mills, by Robertson Buchanan, Civil Engineer, 1814. The transactions of the Society of Arts and Manufactures; several of the volumes of which contain improvements in millwork. See also the Repertory of Arts, in various places. MULLERS for grinding colours, according to the common construction, are too well known and too simple to need a particular description here. But Mr. James Rawlinson, of Derby, has invented a concave muller, for which the Society of Arts presented him a silver medal and ten guineas, on account of its ingenuity. He has used his machine for several years, and has found it much more effectual and expeditious in reducing the colour to extreme fineness than the usual method, and much less injurious to the health of the workman, who frequently has done as much with it in three hours as he could in twelve with the muller and slab. The machine consists of a flat cylinder of black marble, sixteen inches and a half diameter, and four and a half thickness, with an axle traversing its centre (thus somewhat resembling a common cutler's grindstone). It is suspended on a similar frame, in a vertical position, and turned round in the same mauner by a winch: a concave piece of marble is provided, of the same breadth as the circular stone, forming a segment of the same circle one third of the circumference in extent: this, which may be considered as the muller, is fitted into a piece of solid wood of similar shape, one end of which is secured loosely by a hinge or otherwise to the frame; the other end, rising over. the circular stone and supported by it, is further pressed down on it by a long spring bent over from the opposite extremity of the staud, and regulated as to its pressure by a screw, whose end turns against the concave muller: a slight frame of iron in front, moveable on a hinge, by which it is secured to the frame, supports a scraper, for taking off the colour, formed of a piece of watch-spring, which is turned back out of the way when not in Mr. R. thinks the circular grindstones might be made much larger than he used, to advantage, and that one of twofeet diameter would not occasion too much labour to one man to turn it: he computes that in his machine there are seventy square inches of surface of the concave muller in constant work on the paint, while in the common muller not more than sixteen square inches are usually in contact with the slab. The machine will be found equally serviceable for the colours ground in water as for those prepared with oil, according to Mr. R., who highly recommends its use to all colourmen. use. Mr. R. advises, in making up the colours in bladders, to in sert a bit of quill or reed in the neck of the bladder, which will thus bind better in tying; and, admitting of a secure stopper, will be more cleanly and less wasteful than the usual method of stopping with a nail, and keep the colour more safe from the air. (Retrospect, &c. No. 1.) NORIA. See HYDRAULIC-machines, No. 3. ODOMETER, a mechanical contrivance for measuring the way passed over by a carriage. An apparatus of this kind, by Mr. R. L. Edgworth, may be easily attached to the axle-tree bed of a post-chaise, gig, or any other carriage. One turn and a half of a screw is formed round the nave of one of the hinder wheels by a slip of iron, which is wound round the nave, and fastened to it by screws passing through five or six cocks, that are turned up at right angles on the slip of iron. The helix so formed on the nave of the carriage-wheel acts as a worm or screw upon the teeth of a wheel called A, which should have 20 teeth, if the carriage-wheel be 5 feet 3 inches in circumference. On the arbor of the wheel A there is a brass endless screw called B, which acts upon a brass wheel c of 80 teeth; this latter wheel serving as a dial-plate, and is divided into miles, halves, quarters, and furlongs. The figures indicating the miles are nearly 3 of an inch long, so as to be quite distinct; they are pointed to by an index which projects from a fixed point a little way over the plate, in such a manner as to be easily seen from the carriage, as well as the figures passing successively beneath it. The two brass wheels a and c are mounted by irons with pivots upon a rectangular block of wood, which is to be screwed upon the axletree bed, and, if the carriage permits, in such a manner that the dial-plate may front the eye of the person who looks from the carriage. There is a ratchet-wheel attached to the arbor of the wheel A, which by means of a click allows the wheel to be set with a key or handle fitted to the square end of the arbor. There are two springs, one adapted to the wheel A, and the other to the dialplate wheel c, to prevent them from shaking by the motion of the carriage. Such an apparatus will estimate distances for 5 miles, and an additional wheel of 81 teeth would render it fit to count 400 miles. If the carriage-wheel be either larger or smaller than 5 feet 3 inches in perimeter, it will still be easy to adapt an odometer to it. OIL-MILL, a mill for expressing the oils from fruits, or grains, &c. As these kingdoms do not produce the olive, it would be needless to describe the mills which are employed in the southern parts of Europe. We shall content ourselves, therefore, with a description of a Dutch oil-mill, employed for grinding and pressing lint-seed, rape-seed, and other oleaginous grains. Further, to accommodate our description still more to our local circumstances, we shall employ water as the first mover; thus avoiding the enormous expense and complication of a windmill. In plate XXI. fig. A. 1. Is the elevation of a wheel, over or under-shot, as the situation may require. 2. The bell-metal socket, supported by masonry, for receiving the outer gudgeon of the water-wheel. 3. The water-course. Fig. B. 1. A spur-wheel upon the same axis, having 52 teeth. 2. The trundle that is driven by No. 1. and has 78 staves. 3. The wallower, or axis for raising the pestles. It is furnished round its circumference with wipers for lifting the pestles, so that each may fall twice during one turn of the waterwheel, that is, three wipers for each pestle. 4. A frame of timber, carrying a concave half-cylinder of bell-metal, in which the wallower (cased in that part with iron plates) rests and turns round. 5. Masonry supporting the inner gudgeon of the water-wheel and the above-mentioned frame. 6. Gudgeon of the wallower, which bears against a bellmetal step fixed in the wall. This double support of the wallower is found to be necessary in all mills which drive a number of heavy stampers. Fig. c, is the elevation of the pestle and press-frame, their furniture, the mortars, and the press-pestles. 1. The six pestles. 2. Cross pieces between the two rails of the frame, forming, with these rails, guides for the perpendicular motion of the pestles. 3. The two rails. The back one is not seen. They are checked and bolted into the standards No. 12. 4. The tails of the lifts, corresponding to the wipers upon the wallower. See the article WIPER. 5. Another rail in front, for carrying the detents which hold up the pestles when not acting. It is marked 14 in fig. M. 6. A beam a little way behind the pestles. To this are fixed the pulleys for the ropes which lift and stop the pestles.. It is represented by 16 in fig. M. 7. The said pulleys with their ropes. 8. The driver, which strikes the wedge that presses the oil. 9. The discharger, a stamper which strikes upon the inverted wedge, and loosens the press. 10. The lower rail with its cross pieces, forming the lower guides of the pestles. 11. A small cog-wheel upon the wallower, for turning the spatula, which stirs about the oil-seed in the chauffer-pan. It has 28 teeth, and is marked No. 6. in fig. M. 12. The four standards, mortised below into the block, and above into the joists and beams of the building. 13. The six mortars hollowed out of the block itself, and in shape pretty much like a kitchen pot. 14. The feet of the pestles, rounded into cylinders, and shod with a great lump of iron. 15. A board behind the pestles, standing on its edge, but inclining a little backwards. There is such another in front, but not represented here. These form a sort of trough, which prevents the seed from being scattered about by the fall of the pestles, and lost. 16. The first press-box (also hollowed out of the block), in which the grain is squeezed, after it has come for the first time from below the mill-stones. 17. The second press-box, at the other end of the block, for squeezing the grain after it has passed a second time under the pestles. 18. Frame of timber for supporting the other end of the wallower, in the same manner as at No. 4. fig. B. 19. Small cog-wheel on the end of the wallower, for giving motion to the mill-stones. It has 28 teeth. 20. Gudgeon of the wallower, bearing on a bell-metal socket fixed in the wall. 21. Vessels for receiving the oil from the press-boxes. Fig. D. Elevation and mechanism of the mill-stones. 1. Upright shaft, carrying the great cog-wheel above, and the runner mill-stones below in their frame. 2. Cog-wheel of 76 cogs, driven by No. 19. of fig. c. 3. The frame of the funners. 4. The innermost runner, or the one nearest the shaft. 5. Outermost ditto, being further from the shaft. 6. The inner rake, which collects the grain under the outer runner. 7. The outer-rake, which collects the grain under the inner runner. In this manner the grain is always turned over and over, and crushed in every direction. The inner rake lays the grain in a slope, of which fig. o is a section; the runner flattens it, and the second rake lifts it again, as is marked in fig. P; so that every side of a grain is presented to the mill-stone, and the rest of the legger or nether mill-stone is so swept by them, that not a single grain is left on any part of it. The outer rake is also furnished with a rag of cloth, which rubs against the border or hoop that surrounds the nether mill-stone, so as to drag out the few grains which might otherwise remain in the corner. 8. The ends of the iron axle which passes through the upright shaft, and through the two runners. Thus they have two motions: 1mo, A rotation round their own axis; 2do, That by which they are carried round upon the nether mill-stone on which they roll. The holes in these mill-stones are made a little wide; and the holes in the ears of the frame, which carry the ends of the iron axis, are made oval up and down. This great freedom of motion is necessary for the runner mill-stones, because frequently more or less of the grain is below them at a time, and they must therefore be at liberty to get over it without straining, and perhaps breaking, the shaft. 9. The ears of the frame which lead the two extremities of the iron axis. They are mortised into the under side of the bars of the square frame, that is carried round with the shaft. 10. The border or hoop which surrounds the nether mill stone. 11. and 12. The nether mill-stone, and masonry which supports it. Fig. K. Plan of the runner mill-stones, and the frame which carries them round. 1, 1. Are the two mill-stones. 8, 3, 3, 3. The outside pieces of the frame. 4, 4, 4, 4. The cross-bars of the frame which embrace the upright shaft 5, and give motion to the whole. 6,6. The iron axis upon which the runners turn. 7. The outer rake. 8. The inner ditto. Fig. L. Represents the nether mill-stone seen from above. 1. The wooden gutter, which surrounds the nether mill stone. 2. The border or hoop, about six inches high, all round, to prevent any seed from being scattered. 3. An opening or trap-door in the gutter, which can be opened or shut at pleasure. When open, it allows the bruised grain collected in and shoved along the gutter by the rakes to pass through into troughs placed below to receive it. 4. Portion of the circle described by the outer runner. 5. Portion of the circle described by the inner one. By these we see that the two stones have different routes round the axis, and bruise more seed. 6. The outer rake. 7. The inner ditto. 8. The sweep, making part of the inner rake, occasionally let down for sweeping off all the seed when it has been sufficiently |