But when, under all those occasional fluctuations, the market price either of gold or silver bullion continues for several years together steadily and constantly, either more or less above, or more or less below the mint price, we may be assured that this steady and constant, either superiority or inferiority of price, is the effect of something in the state of the coin, which, at that time, renders a certain quantity of coin either of more value or of less value than the precise quantity of bullion which it ought to contain.