This branch of the engineer's work includes all the processes where the hammer, chisel, file, and scraper are used. These are necessarily very numerous and diversified, but not so much so as in past years, because of the introduction of so many machine tools. When small, the work is held in the vice, with soft metal grips interposed to prevent damage to the surfaces in contact with the jaws. The old form of tail vice is still very widely employed - in fact in some workshops nothing else is met with - but during recent years the constant cry about the absence of parallelism in the hold has led to the introduction of many parallel jawed vices, some worked by screws and others by instantaneous grip arrangements. These are quickly growing in favour, and in many works already hold entire sway. For medium weight of work the surfaces operated upon should not be higher than the workman's elbow, so that he may secure the best possible command over them. Engineers' hammers vary chiefly in weight and form of pane, the latter being made of three different kinds - cross, straight, and round. The weight of the hammer will be determined by the strength of the workman and the kind of work to be performed, while the size and shape of the chisel will be guided by similar considerations. Chisels are of several shapes, the most useful being the flat chipping chisel, the cross-cut, and the foals-foot or round nosed chisel. For much of the ordinary run of work, chisels are made of 7/8 in. octagonal steel, from 9 to 10 ins. long. Flat chipping chisels, necessary for all sorts of flat work, are broad and parallel to the point, and sharpened on the grindstone equally on both sides, so as to make an angle of from 6o° to 700 with one another -larger and smaller angles being used when advisable. The cross-cut is a narrow chisel broadening slightly towards the point and sharpened like the flat chisel, though often on one side only. It is required for cutting out flat, narrow grooves, key-ways, and such like. The foals-foot is of the same shape as the cross-cut, except in one respect, viz., that one of its edges is curved, and so made suitable for cutting a semi-circular groove, and performing such like work as centre shifting at the drilling machine. Steadiness of position and regularity of stroke in the direction of the axis of the chisel are leading elements in easy and correct chipping. The aim of the fitter is to produce as flat a surface as possible with the chisel, and so save work with the file. This, however, is no easy matter, for the slightest alteration of the chisel's position will produce a corresponding variation on the surface, the truth of which will be tested, in the first place, by steel straightedges.