Chains are made up of separate links of rigid metal which having no flexibility in themselves are yet so united that each shall move freely on the next links to it, and thus produce a flexible whole. For ornamental purposes there is almost an endless variety of patterns, as may be seen in jewellery-work--but for the purposes of business and machinery there are chiefly but two, the ordinary, as fig. 1, and that which will only bend in one plane, as in fig. 2--this is chiefly made use of in passing round wheels, as in clocks. Chains are used where rough wear is required, in which case rope would be rapidly worn through. Cables of chain are now much more generally used than hempen ones, as they are more to be depended on, take up less room, and are not so liable to be cut or worn by rough rocks at the bottom. In chain cables a “stay” is placed in every link (fig. 3), which greatly increases its strength, but the best form of chain cable is shown at fig. 4; in this the links are somewhat angular, and the stays longer. Chains are chiefly made by machinery; the rods are first drawn out of the proper size, pieces of the required length are then cut off and bent to the right form, and the stay and this link are then both made white hot, placed in their right position, and welded together by pressure. CRANES. Illustration: (‡ YARD CRANE.) Illustration: FIG. 1. (‡ WHEEL ASSEMBLY.) Illustration: FIG. 2. (‡ FLOOR CRANE.) Illustration: FIG. 3. (‡ LANDING CRANE.) Illustration: FIG. 4. (‡ LANDING CRANE.) Illustration: FIG. 5. (‡ JIB CRANE.) Illustration: FIG. 6. (‡ SWING CRANE.)