or Coos, in Ancient Geography, a noble island on the coast of Caria, in the Hither Asia, 15 miles to the west of Halicarnassus, 100 in compass, called Meropis; and hence Thucydides joins both names together, Cos Meropis; it had a cognominal town Cos, but originally called Astypalaea, mentioned by Homer; with a port locked or walled round. (Scylax, Melis.) The island was fruitful, and yielded a generous wine, (Strabo). It boasted of Hippocrates and Apelles; each at the head of his several profession. It was the country of Philetas, an excellent elegiac poet, who flourished in the time of Philip and Alexander: the preceptor of Ptolemy Philadelphus: so thin and light that he was obliged to wear lead to prevent the being blown away by a puff of wind (Ælian, Athenæus); much commended by Propertius. The vestes Cosæ, made of silk, were famous for their fineness and colour, (Horace, Propertius, Tibullus). In the suburbs of Cos stood the temple of Æsculapius, a noble structure, and extremely rich.

Whetstone, in Natural History, a genus of vitreous stones, consisting of fragments of an indeterminate figure, sub-opaque, and granulated.

Of this genus there are several species, some consisting of rougher, and others of smoother, or even of altogether impalpable particles; and used not only for whetstones, but also for mill-stones, and other like purposes.

Cos turcica, Turkey-stone, a species of stones which is arranged in the siliceous class. It is of a dull white, and often of an unequal colour; some parts appearing more compact than others. Its specific gravity is 2.598: it strikes fire with steel, and effervesces with acids. Mr Kirwan found that 100 parts of it contain 25 of carbonate of lime, and no iron. Cronstedt is of opinion that there are probably two sorts of stones known by this name, as that described by Wallerius neither gives fire with steel nor effervesces with acids. It is used as a whetstone; and those of the finest grains are the best bones for the most delicate cutting tools, and even for razors, lancets, &c.