We may fairly presume that the trade in the ancient metallic products of the island, tin and lead, was greatly extended during the Roman occupation. It seems to have been then that the tin-mines first began to be worked to any considerable depth, or rather that the metal began to be procured by any process which could properly be called mining. It has, been supposed that convicted criminals among the Romans used to be condemned to work in the British mines. Roman coins, and also blocks of tin, with Latin inscriptions, have been found in the old tin-mines and stream-works of Cornwall. The British Museum contains several pigs of lead stamped by the Romans, which have been discovered in different parts of the country. Britain then, as now, seems to have produced much more lead than all the rest of Europe. But we have no direct information as to any actual exports of the metals from Britain in the Roman times, and can merely infer the fact from the mention which we find made of them as important products of the country, and from the other evidences we have that they were then obtained in considerable quantities. On those grounds it has been supposed that supplies were in those days obtained from Britain not only of lead and tin, but also of iron, and even of the precious metals. Tacitus expressly mentions gold and silver as among the mineral products of the island.[1]
The same writer adds that Britain likewise produces pearls, the colour of which, however, is dusky and livid; but this he thinks may probably be attributed to the unskilfulness of the gatherers, who do not pluck the fish alive from the rocks, as is done in the Red Sea, but merely collect them as the sea throws them up dead. The pearls of Britain seem to have very early acquired celebrity. A tradition is preserved by Suetonius that Julius Cæsar was tempted to invade the island by the hope of enriching himself with its pearls; and Pliny speaks of a shield studded with British pearls which, after his expedition, he dedicated to Venus, and sus-
- ↑ Agric. 12.
