The object ground should be continually traversed backwards and forwards to use the stone alike all over, the stones should not be allowed to remain long out of condition, as they get rapidly worse, neither should they ever remain partially immersed in the water in the trough, which would soften those parts and expose them to more rapid wear, than the remainder.

In almost every case the grindstone is made to revolve away from the workman, so that should the work slip from his grasp it may be carried away from his person and not against him. But this direction of motion leaves a wiry film on tools with thin cutting edges, and which the regular grinder occasionally avoids, by holding the tool back-handed, or with the edge towards his person. Many of the tools used in turning metal do not require to be sharpened on the oilstone, and to avoid the wiry film, such tools are usually ground with the stone running towards the workman.

The Bilston grindstone has the preference for small tools from the comparative smoothness of its grain, and occasionally, a coarse and a fine stone are fixed on the same spindle; and when the shop grindstone is driven by power, the workman goes to the front or back of the stone accordingly as the motion is best suited to his immediate want.

19. - General Remarks on Grinding Various Kinds of Tools. - The general position of the grinder described under article 9, serves for grinding all ordinary tools, such as chisels, axes, and many others of ordinary kinds, which are simply held to the stone by the hands, and receive the pressure of the arms and upper part of the person.

20. - Massive works, such as anvils, are suspended loosely by a chain, the man has then only to guide them, and their own weight supplies the pressure.

21. - Large heavy plates, such as the bright cast-iron fronts of stoves, are allowed to rest in an oblique position, jointly upon the surface of the horse and the stone, the grinder slides them about, to expose all parts of the surface to equal action, and often bears on them with his knees to increase the pressure.

22. - Saws are too thin and elastic to be thus treated, and such flexible objects are applied on a flat board to give them support, the man leans upon the board with his whole weight and moves them up and down at an inclination of about 45 degrees to grind each part successively and equally.

23. - The blades of table knives are before being handled ground on the side of a stick, about 2 1/2 by 1 1/2 inches and 2 feet long with a staple under which the shank of the blade is placed, the stick is rounded at the ends to serve for the two hands, and the workman sometimes applies also his knees to the central part, and the effect of the stone is then very rapidly felt on the blade.

24. - Small works that are ground lengthways, are sometimes nipped between the horse and the stone, an enormous pressure may be then given much less laboriously than by the arms, this is often done in grinding the surface of files preparatory to their being cut with teeth, and in stripping the teeth from old ones, prior to re-cutting them; but this practice throws a great pressure on the stone, sometimes enough to check the speed of the steam engine. 25. - Small works are in many cases difficult to be held unassistedly, because of the risk of grinding through the skin of the fingers, or of burning them from the heat of the work, a small pointed stick is frequently used to press the work on the stone, and in some cases a small square piece of thick leather or felt, called a patch, is similarly employed. Sometimes also small tools are temporarily fixed by their tangs in a wooden handle to facilitate their presentation to the stone; the handle is called a "haftpipe" and is commonly a short piece of hazel rod. But the more usual course at Sheffield is to employ a pair of tongs or pliers, the reins of which do not cross as pliers and scissors generally, but consist simply of two rods of iron retained by a link across their middle. The work is fixed by being inserted between the rods at the one end, and a wooden wedge driven in between the opposite extremities, binds the whole together very securely. The sliding tongs, fig. 861, page 862, Vol. II., are also used occasionally. 26. - Adaptation of Grindstones to the Forms of Works. - Convex works may of course be ground upon the cylindrical edge of the grindstone, as by rolling the work about, every part of the same may be brought into contact with the stone, in the same manner that round or convex works may be filed with a flat file; but in grinding concave works, it is of course needful that the stone if not altogether a counterpart of the work, should be sufficiently modified in form to penetrate to the bottom of the hollow.

Thus in grinding a pruning bill, the hook of which is of small radius, it is indispensable the one edge of the stone should be rounded to the fourth of a circle; in grinding that part of a table knife where the blade is united to the shank, a similar curvature in the stone is also required. In grinding hollow or fluted works such as the concave parts of gouges, it is necessary to turn the grindstone to the exact counterpart form, or into beads of different width and sweeps, and various other examples might be quoted.

In order to reach within that keen edge in the blade of a penknife which unites the square shank for the joint to the remainder of the blade, (which angle is technically called the chorl,) the edge of the stone is kept remarkably keen and sharp, this is assisted by waxing the side of the dry grindstone close to the edge, and which tends to prevent the same from crumbling away, and also prevents the stone cutting into the shoulders of the blade. 27. - Wet and Dry Stones. - Grindstones are almost always used with water, as in the humid state they cut more quickly, because the wet prevents the grain of the stone being choaked with particles of metal, but when the stone is used dry, although it cuts somewhat more slowly, it leaves a smoother grain upon the work, and on which account the dry stone is always resorted to by fork-grinders and needle pointers. 28. - The dry stone is somewhat used also by most grinders, but only for a small part of their work, as when vigorously applied it gives rise to so much friction; that it frequently heats the work to a blue, or almost to a red-heat, and would destroy the temper of the tools, its use is therefore nearly restricted to the roughing-out of tools, before they are hardened, an operation called "scorching": at this early stage of the manufacture of tools they receive no injury from the great heat sometimes thus given them. 29. - Hardened and tempered blades that have been ground on the wet stone, are often smoothed on a dry Bilston stone, in order to leave less work to be accomplished in the next stage of manufacture, by the metal lap with fine emery; but the judicious cutler then applies the dry stone so moderately as not to reduce the temper of the blades, but only to smooth them. 30. - Danger of Using Dry Stones. - A still worse and more fatal mischief than spoiling the work attends the continual practice of dry grinding, as the fine particles of stone and steel that are given off, raise clouds of dust which are inhaled by the workmen, and so commonly does this contaminated atmosphere induce pulmonary complaints, that it is considered rare for a needle or fork grinder to live beyond the age of twenty-five or thirty, at which period they generally become afflicted with asthma and premature decay, 31. - To avert this calamity Mr. Abraham of Sheffield invented magnetic guards which were placed close to the grindstone, and sometimes also around the mouth and nostrils of the individual. (See Trans. Soc. of Arts, vol. 40, plate XXIII). The magnet attracted the particles of steel and together with them drew the greater part of the stone dust, but the men were too heedless to avail themselves of this philanthropic invention, notwithstanding its complete success. 32. - The only contrivance now employed is also due to Mr. Abraham, the stone is enclosed in a wooden case that only exposes a part of its edge, and from the box a horizontal tube also of wood, proceeds as a tangent from the upper surface of the stone to the external atmosphere. The current of air generated by the motion of the stone makes its escape through the tube, and carries with it nearly the whole of the dust arising from the process; sometimes the tube alone is retained.

But even this contrivance, (which may be viewed as comparable with the revolving fan now used in blowing furnaces,) although so much less elaborate than the magnetic guards, yet nearly as effective, is also for the most part neglected, owing to the unpardonable heedlessness of the workmen themselves.

Mr. W. Lund invented an apparatus almost identical with Clark's revolving blower with a small fan, it was driven by a short band from the stone, and was described, in the Mechanic's Magazine under the signature "Gulielmus," this also merely obtained a very limited use.