The main characteristic of the Celtic brooch is that it is penannular, that is, its ring has an opening, if not real, at least apparent, between its two ends. For even when the narrow opening left between the enlarged ends is closed by a bar, or is finally closed altogether, the flattened plaques are ornamentally treated as if they were still disunited. Of this class of brooches with continuous rings there have survived two world-famed examples, one from Ireland and the other from Scotland. The first of these, known as the Tara brooch, was found in 1850 on the seashore near Bettystown, Co. Louth, and received the title of "Tara" on account of its beauty, and after the celebrated hill of that name. It is composed of white bronze thickly gilded. The ring and expanded head of the pin are divided into a number of panels ornamented with examples of nearly every technical process, being enriched with enamel-work, niello, and inlaid stones; while the metal is hammered, chased, and engraved, and filigreed with extraordinary delicacy. The enamels, of the cloisonné kind, have been made separately and mounted like gems. Attached to the brooch on one side is a finely plaited chain; a similar chain upon the other side has been lost. The reverse of the brooch is unadorned with settings, but decorated with a divergent spiral ornament known as the Celtic trumpet pattern, executed with very great perfection. The probable date of this extraordinary jewel is the tenth century. It is now the chief treasure of the museum of the Royal Irish Academy, for which it was bought in 1867 for the sum of £200. [Illustration: _PLATE XIV_ THE TARA BROOCH (NATIONAL MUSEUM, DUBLIN)] The finest after the Tara brooch, and the most famous of Scottish brooches, is known as the Hunterston brooch. It was found in 1826 on the estate of Mr. Robert Hunter, of West Kilbride, Ayrshire, and is now in the National Museum of Antiquities of Scotland. It is somewhat similar to the Tara brooch, and of the same gilt metal, but rather less ornate, and unprovided with enamels, glass pastes, or chain. Its main ornamentation consists of varieties of interlaced work in fine gold filigree, of singularly beautiful design and of remarkable execution. The back is decorated with the trumpet pattern, and engraved with Runic characters. The presence of the trumpet pattern upon the backs of these two famous brooches determines their date as prior to the eleventh century; for the old Celtic pattern disappears from brooches and from most Irish and all Scottish metal-work after the year 1000 A.D., and is succeeded by varieties of interlaced work and zoomorphic designs.[26] The later Celtic brooches differ besides in form, for the pin is longer in proportion to the size of the ring, and its head is hinged upon a constriction of the ring, which itself becomes partly filled up. [26] Anderson (J.), _Scotland in early Christian times_, 2nd Series. 1881.