Augustus the aureus weighed 1-40 of a pound of gold, and under Diocletian it weighed but 1-60. Under Constantine it fell to 1-72, when the coin was taken only by weight (Sabatier, Monnaies Byzantines, i, 51–2; Brooks Adams, Law of Civilization and Decay, 25–8). It was this steady loss of capital, to replace which no new wealth was produced, that led finally to the abandonment of Rome and to the transfer of the capital at the end of the 3d century to Nicomedia and soon afterward to Byzantium.
Coin of Nero commemorating the opening of the harbor-works at Ostia.
In the Madras Government Museum there is nearly a complete series of the coins of the Roman Emperors during the period of active trade with India, all of them excavated in southern India. A notable fact is that there are two distinct breaks in the series; which may of course be supplied by later discovery, but which seem to indicate a cession of trade due to political turmoil in Rome. The coins of Tiberius, Caligula, Claudius and Nero are numerous. There are very few of Vespasian and Titus anywhere in India. Those of Domitian, Nerva, Trajan and Hadrian are frequent; then there comes another break lasting until the time of Commodus. This indication, so far as it has any value, points again to the dating of the Periplus during the reign of Nero rather than during those of Vespasian and Titus.
For a full account of Roman coins discovered in South India, see E. Thurston, Catalogue No. 2, Madras Government Museum, pp. 1–47.
56. Crude glass.—The origin of the glass industry in India is uncertain. According to Mitra, Antiquities of Orissa, I, 101, it was made in Ceylon in the 3d century B. C., and Pliny (XXXVI, 66) refers to the glass of India as superior to all others, because "made of pounded crystal." Mirrors, with a foil of lead and tin, were largely used there at the time of the Periplus, and Pliny indicates (XXXVII, 20)
