These objects are found all over the Mediterranean, especially at Halikarnassos, Naukratis, and Delos, and the last-named place has been regarded as the centre of their manufacture. They are all of the same brick-like, coarse, red clay. Some bear the name of their maker, Hekataios or Nikolaos. Besides the heads already mentioned, heads of goats or oxen, or of Sirius, thunderbolts and rosettes are used by way of devices. They have been collected together, and illustrations of all the different types given by Conze in the _Jahrbuch_ for 1890, p. 118 ff.: two specimens are given on Plate IV. They belong to the Hellenistic Age. Other objects that exemplify the use of clay or terracotta in Greek daily life are: moulds for vases and terracotta figures, lamps, weights, and stamps for various purposes. Many flat discs of terracotta have been found at Tarsus, Gela in Sicily, Tarentum, and other places, pierced with two holes and about three inches in diameter.[368] They are stamped with various devices and inscriptions, but their use is unknown. Other discs of convex form found at Halikarnassos and stamped with heads in relief are supposed to have been weights ([λεῖαι) to hold down the threads of the loom (ἀγνύθες),[369] such as are used by the Greeks at the present day; others again may be the weights used for keeping the ends of the folds of a himation in position. Small pierced cones of terracotta often found in the fields of Greece have been supposed to have been suspended round the necks of cattle, but are probably weights of some kind.[370] Lastly, terracotta egg-shaped objects have been found in Sicily inscribed with various names, and are supposed to have been voting-tickets used for the ballots of the tribes.[371] Many examples have been found of terracotta impressions from coins, which may have been the trial-pieces of die-sinkers or forgers, since persons of that class, as among the Romans, seem to have employed this material for their nefarious practices. They are more fully discussed in Chapter XIX. The British Museum contains a large collection of these found in the Fayûm in Egypt, all of Roman date; also a copy of a coin of Larissa from Acarnania. Terracotta medallions with impressions of gems or seals are not uncommon, especially in Asia Minor and at Naukratis, and among the latter are many lumps of clay actually used as seals, with the pattern of the substance in which they were impressed adhering to the back of them, while on the front is a design from a signet-ring.[372] * * * * * The subject of =Lamps= is one that is more conveniently and appropriately treated in the Roman section of this work (see Chapter XX.), almost all existing examples in terracotta being of that period; it may not, however, be out of place to include here a few general remarks on the subject, pointing out the distinctive features of those of purely Greek origin.