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.