The rollers or cylinders were formerly made of wood; they are now usually of paper or cast iron. The paper cylinders are formed by packing a great number of circular pieces of stout pasteboard upon an iron axis, and compressing them very tightly by means of iron bolts passed through them, acting upon circular end-plates of cast iron. The surface is brought to a perfectly even and polished state by turning in a lathe. Iron rollers are made hollow and when necessary heated from the inside. When a glazed or polished surface is required on the goods to be calendered, mechanism is employed to cause two adjacent rollers to revolve with different velocities, so as to produce a rubbing action. [Illustration: Printing Press. Chair with Rollers. Tin Block.] The _furnace_ for heating the _rollers_, the _chair with rollers_, the _presses_ and _tin blocks_ for hotpressing, and the _windlass_ for turning, are easily understood in relation to this trade. The _printing press_ and _embossed cylinder_ have been mentioned in the trade of calico printing. The _mill_, turned by a horse, is used where steam power is not employed to put the machinery in motion. [Illustration: Furnace.] THE CUTLER AND FILE-CUTTER. [Illustration: GRINDING.] Amongst all the trades that occupy the attention of mankind, that of the Cutler, which also includes the tool maker, is certainly one of the most essential, since without tools no other manufactures could be carried on. Cutting instruments of various kinds have been in use from the earliest ages, if for no other purposes, for cutting food, slaughtering animals, and making war upon each other. In ancient times, as well as amongst some barbarous tribes at the present day, these implements were frequently made of shells, edged flints, or hardened wood, fashioned into sharp weapons; at a late period, cutting as well as warlike instruments were formed of brass or bronze; but at the present time, in all civilized nations they are formed exclusively of steel or iron. Steel is formed from the purest bar iron—that which comes from the Swedish mines being preferred. This is buried in powdered charcoal and heated to whiteness for several days, without exposure to the air; during this time the metal becomes much harder, whiter in colour, crystalline in texture, and blistered on the surface. The blistered steel so produced is prepared for use, either by binding several bars together and hammering them into one, or by melting them in earthenware pots, called crucibles, and pouring the melted metal into moulds of the size required. In the latter state it is called cast steel.