COOPERAGE, the art of making casks, barrels, and other rounded vessels, the sides of which are composed of separate staves, held together by hoops surrounding them. The art is one of great antiquity, being mentioned by Pliny, who ascribes its invention to the inhabitants of the Alpine valleys. The cask or barrel form is at once the strongest, tightest, and most convenient form into which wood can be fashioned as a vessel for storing either liquid or solid substances, and the manufacture has attained great preftision and perfection. The trade is one in which there are numerous subdivisions, the chief of which are tight or wet and dry or slack cask manufacture. To these may be added white cooperage, a department which embraces the construction of wooden tubs, pails, churns, and other even-staved vessels. Of all departments, the manufacture of tight casks or barrels for holding liquids is that which demands the greatest care, experience, and skill; as, in addition to perfect tightness when filled with liquid, the vessels must bear the strain of transportation to great distances, and in many cases they have to resist considerable internal pressure when they contain fermenting liquors. Cooperage is still most commonly pursued as a handicraft with the tools and appliances which have been employed from the earliest times ; but many expedients of the greatest ingenuity and efficiency have been introduced or performing the numerous operations by mechanical means. Tight casks are generally made of well-seasoned oak of the best quality, free from twists and warping. Whether accomplished by hand or machinery the following are the essential operations. 1st, The preparation of the staves is the most important and difficult task of the cooper, inasmuch as a cask being a doable colloid, having its greatest diameter (technically the bulge or belly) iu its centre, each stave must be accurately curved to form a segment of the whole. The taper from the centre to the extremities must be curved ; in cross section it must be, double concave, and the joints, or edges, must be so bevelled that when bent into position they shall form a true piano through the central axis of the vessel. 2d, Trussing consists of setting the separate staves, properly bevelled and jointed, upright in a frame in order to receive trussing hoops at both ends, which serve to keep them together for the permanent hooping. The lower ends of the staves are set together in a frame and a hoop passed round them. A rope is then carried round the upper part and gradually tightened till the joints are brought quite close, when a hoop is dropped over and the rope removed. 3d, Chiming and crozing consists in finishing the two ends for receiving the heads. The chime is the bevel formed on the extremity of the staves, and the cruse consists of the groove into which the ends or heads fit. 4th, Hooping, and 5th, Preparing heads or ends, are the other operations to be noticed. For wet casks hoops are generally made of iron, although wooden hoops also are employed. The heads, when made of two or more pieces, are jointed by means of dowel pins, and after being cut' to the proper size they are chamfered or bevelled at the edges to fit into the crone grooves. Drawings and descriptions of a very elaborate and complete series of machines made by Messrs Allen, Rausome, Sr, Co. of Chelsea, from the designs of Mr John Richard, for performing these various operations, will be found in Engineering (vol. xxi. January - June 1876).

The quantity of tight casks required in certain industries is incalculable. On the continent of Europe they are in most extensive demand in the wine-producing districts. In Great Britain, brewers and distillers must have enormous stocks, and both in Great Britain and in the United States the mineral oil and petroleum trade employ vast quantities. Slack barrels are almost as extensively employed in connection with chemical industries and the fruit and fish trades. In America slack barrels are the form most generally adopted for packing almost all kinds of dry goods for storing and transport, and the flour, rosin, fruit, and other products sent to Europe are almost invariably inclosed in such vessels.