=The Bornholm Clay Period.=--Mention has already been made, in dealing with the early discoveries of Müller and the experiments he made, of the clay which he found in the island of Bornholm. This clay forms the body of some of the earliest-known pieces made by him. It may be readily recognized by its heavy weight and by its grey tone. It is easy, after making an examination of a great number of specimens of the old blue-and-white ware, to distinguish this Bornholm period, even although in the two years (1773-1775) prior to the adoption of the three blue lines as a factory mark, some pieces bear no mark whatever. It somewhat resembles certain heavy Japanese ware in its compact and solid body and grey-blue colour. The author has made a fairly exhaustive test of several hundred pieces, both in public and in private collections. The gradual development in regard to the perfection of the paste and the glaze is so noticeable that it is possible to place the old blue-and-white fluted ware in successive grades according to the stages of evolution. At first coarse, though never meaningless nor offensive, when the ware was obviously in an experimental period, it betrayed fire-cracks and warpings in form and slight departures from perfect symmetry. Later it became whiter and thinner, and was manifestly more completely under the control of the potter. When the perfected period was reached, there were tea caddies, pounce boxes, and, in particular, certain dishes, of which an example is illustrated (p. 169) which are not unworthy to be compared favourably with specimens of old blue-and-white Worcester of the early period. There is a delicacy and refinement in the modelling and potting, and that tenderness in the glaze and thinness in the body which at once betoken that the technique has been subjected to the patient potter's control. [Illustration: GROUP, PAINTED IN BLUE UNDERGLAZE. _Tea Caddy_, circular. Mark, three lines, figure 1 (blue); II (incised). _Teapot._ Fine rich blue. Mark, three lines and figure 3 on lid. _Tea Caddy._ Mark, three lines, figure 2 and two lines (blue); T (incised). (_In Museum at Royal Copenhagen Porcelain Factory._)] [Illustration: DISH (NATIONAL DANISH PATTERN), AND TWO PLATES. Decorated with underglaze blue painting.]