See C. Smith, _Ancient and Present State of the County and City of Cork_ (1750), edited by R. Day and W. A. Copinger (Cork, 1893); C. B. Gibson, _History of the City and County of Cork_ (London, 1861); M. F. Cusack, _History of the City and County of Cork_, 1875.
CORK (perhaps through Sp. _corcha_ from Lat. _cortex_, bark, but possibly connected with _quercus_, oak), the outer layer of the bark of an evergreen species of oak (_Quercus Suber_). The tree reaches the height of about 30 ft., growing in the south of Europe and on the North African coasts generally; but it is principally cultivated in Spain and Portugal. The outer layer of bark in the cork oak by annual additions from within gradually becomes a thick soft homogeneous mass, possessing those compressible and elastic properties upon which the economic value of the material chiefly depends. The first stripping of cork from young trees takes place when they are from fifteen to twenty years of age. The yield, which is rough, unequal and woody in texture, is called virgin cork, and is useful only as a tanning substance, or for forming rustic work in ferneries, conservatories, &c. Subsequently the bark is removed every eight or ten years, the quality of the cork improving with each successive stripping; and the trees continue to live and thrive under the operation for 150 years and upwards. The produce of the second barking is still so coarse in texture that it is only fit for making floats for nets and for similar applications. The operation of stripping the trees takes place during the months of July and August. Two cuts are made round the stem--one a little above the ground, and the other immediately under the spring of the main branches. Between these three or four longitudinal incisions are then made, the utmost care being taken not to injure the inner bark. The cork is thereafter removed in the sections into which it has been cut, by inserting under it the wedge-shaped handle of the implement used in making the incisions. After the outer surface has been scraped and cleaned, the pieces are flattened by heating them over a fire and submitting them to pressure on a flat surface. In the heating operation the surface is charred, and thereby the pores are closed up, and what is termed "nerve" is given to the material. In this state the cork is ready for manufacture or exportation.