The question of a medium of exchange leads us to mention the very small gold penannular rings, the largest being about an inch in diameter, frequently found in Ireland, which are known as 'ring-money.' There are fifty-six in the National Collection; and a find made near Belfast of a socketed bronze celt in association with some of these objects shows they were in use during the late Bronze Age.[23] Attention has been called to the similarity of these Irish gold rings to the penannular copper rings plated with gold often found in early Japanese burials.[24] [23] Archaeologia, lxi, p. 153. [24] See Munro, "Pre-historic Japan," p. 435, fig. 276. Many attempts have been made to equate the weights of a series of these rings with some known standard; and in his valuable work "The Origin of Currency and Weight Standards," Professor Ridgeway devotes several pages of his Appendix C to a discussion of the subject, and gives a table of the weights arrived at by grouping the rings in multiples of 18. While there can be no reasonable doubt that these objects were used as a medium of exchange, we are not inclined, in the absence of literary evidence, to go any further into the question of what standard they may represent. Some of these rings are evidently forgeries of ancient times, as they are composed of bronze rings covered with a thin plate of gold. The rings as a rule are plain; but some are ornamented with small strips of darker metal let into the gold, and two examples are twisted like small torcs. [Illustration: PLATE VI. Gold Ring-Money. _p. 70._] CHAPTER VII LEAF-SHAPED SWORDS