No apology need be made for setting out in full a list of the silver coins found in the course of seven years' digging (1906 to 1912) on the Romano-British site of Corstopitum near Corbridge-on-Tyne, three miles south of Hadrian's Wall, in Northumberland. So much attention has been paid to coin-hoards, so little to the general character of coins found on Roman sites, that we are in danger of neglecting half the evidence which excavation is able to furnish. For hoards and general coin-finds naturally differ in their character. A hoard furnishes evidence as to what coins were in circulation together, or were in circulation during a limited if indefinite period, namely, the period of hoarding. Lost unhoarded coins—lost because they were not hoarded—tell a different tale. Whereas in hoards the latest years are, normally, most plentifully represented, lost coins may be taken to bear a constant proportion to the total amount of money circulating throughout the period of occupation. They furnish better historical evidence in regard to a site, for, whereas the period of occupation can usually be settled by other data, the period of hoarding can only be arrived at from the evidence of the hoard itself taken in conjunction with other hoards of different date: the terminus ad quem of a hoard can be easily ascertained, but the terminus a quo is bound to remain indefinite. Hoards are usually composed of coins of a single denomination, but in unhoarded coin all classes of currency are, or may be, equally represented; the personal factor is excluded, and different denominations are found in much the same proportion to that in which they circulated.
THE EXTREME WEIGHTS IN THE INDEX PORTFOLIO OF CONSTANT-PROPORTION STRATEGIES
