E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The employment of two metals, silver and gold, of fixed relative value. Now gold is the only standard metal in England and some other countries. Silver coins are mere tokens, like copper coins; and if given in payment of large sums are estimated at the market value, so much an ounce; but a gold sovereign is always of one fixed legal value.