ight in a circular frame, and round their
lower halves are fitted truss hoops which serve to keep them together
for the permanent hooping. The upper ends are then drawn together by
means of a rope which is passed round them and tightened by a windlass,
and other truss hoops are dropped over them, the wood being steamed or
heated to enable it to bend freely to shape. The two ends of the cask
are next finished to receive the heads by forming the chime, or bevel on
the extremity of the staves, and the croze or groove into which the
heads fit. Finally the heads and permanent hoops are put in place. The
heads, when made of two or more pieces, are jointed by wooden dowel
pins, and after being cut to size are chamfered or bevelled round the
edge to fit into the croze grooves. The hoops are generally of iron. The
manufacture of slack casks proceeds on the same general lines, but is
simpler in various respects, both because less accurate workmanship is
required, and because softer woods, largely fir, may be employed.
Machinery of the most elaborate and specialized character has been
devised to perform most of the operations in making both slack and tight
casks, and though it involves considerable capital outlay it effects so
great an economy of time that it has largely superseded hand labour.
(For an account of such machinery see L. H. Ransome, "Cask-making
Machinery," _Proc. Inst. Civ. Eng._ vol. 115; also an article in
_Engineering_, 1908, 85, p. 845.) Barrels without separate staves are
made by bending a sheet of wood, sawn from a log in a continuous strip,
into the required circular shape, the bulge at the centre being obtained
by cutting out V gores from the ends. Barrels are also sometimes made of
steel, either of the ordinary bulging form or consisting of
straight-sided drums provided near the middle with rings on which they
may be rolled. Immense numbers of casks of different shapes and sizes
are employed in various industries. Tight barrels are a necessity to the
wine and cider maker, brewer and distiller, and are largely used for the
transport of oils and liquid chemicals, while slack barrels are utilized
by the million for packing cement, alkali, china, fruit, fish and
numerous other products.

CO-OPERATION, a term used particularly both for a theory of life, and
for a system of business, with the general sense of "working together"
(_con_, with, and _opus_, work). In its narrowest usage it means a
combination o