Upsetting-blocks that are required to form the extremities of rods or levers to particular shapes are made with recesses and gaps in the upper sides. Fig. 265 represents a block of this class, having a few recesses for shaping convex extremities of rods and bolts; also for forming joint bosses at the ends of levers and solid fork-ends. A rectangular recess also is shown for shaping T-heads by upsetting. Such blocks may also have recesses for angling bars and plates, and recesses of any forms that are suitable to produce the particular forgings desired.

When an upsetting-block or any other shaping-implement is intended to shape a great number of forgings, it is advisable to make the implement of Bessemer steel or of hard cast iron. Bessemer steel is more suitable than soft wrought iron which is case-hardened, because the hard Bessemer product does not need any additional hardening process; also because, when soft iron is case-hardened, the soft portion which is beneath the hard part allows the hard thin crust to be hammered out of its proper shape.

The Learner

It is now necessary to conclude this treatise on forging with a few remarks to beginners who may not have had patience to read the brief details given concerning the various processes. A knowledge of forging is more useful to any beginner in engineering than a knowledge of moulding and casting without forging; because a number of the parts of small engines may be forged instead of cast, when casting is inconvenient; also because, when casting is convenient, a large number of engine components cannot be, or ought not to be, made by casting. Guides, slides, plummer-blocks, supporters, pedestals, cams, and wheels may be either cast or wrought; but rods, axles, and levers must be in all cases made of wrought iron or steel, that the homogeneous character imparted by the original casting may be destroyed, and tough fibrous rods and axles thereby produced. A beginner may thus perceive that forging is the first thing to practise or commence with, whether or not it may be absolutely necessary to him. And whatever branch of engineering he intends to enter, whether as designer, draughtsman, or constructor, he will be liable to commit many mistakes without a knowledge of forging and casting.

Every beginner in engineering should first learn the names, forms, and definitions relating to that particular branch which he intends to study. To attempt to study the whole of engineering would result in acquiring merely a variety of confused ideas of drawings, mathematics, and the vast crowd of inventions in actual use at the present moment. Therefore, because the branch of engineering treated in the "Mechanician" is engine-making, a learner is directed to learn the definitions concerning those things of which and with which engines are made. And even with this, his alphabet, properly so named, he must not be overburdened at any one particular stage of his progress, but should, refer, at one time and at another time, to any definition or description that he may require as he gradually advances in his work, and develops to practice the verbal knowledge he has acquired. By thus frequently adding to his knowledge of a subject at one time and at another time, instead of learning too much at once, he will be enabled to retain that which he has found to be true, and to neglect and endeavour to unlearn any false notions he may have imbibed. And this remark applies not only to progress in engineering, but also to the gradual acquisition of every other art and method now in existence or which will be developed at a future day.