In their observations upon the prices of corn, three different circumstances seem frequently to have misled them.
First, in ancient times, almost all rents were paid in kind; in a certain quantity of corn, cattle, poultry, etc. It sometimes happened, however, that the landlord would stipulate, that he should be at liberty to demand of the tenant, either the annual payment in kind or a certain sum of money instead of it. The price at which the payment in kind was in this manner exchanged for a certain sum of money, is in Scotland called the conversion price. As the option is always in the landlord to take either the substance or the price, it is necessary, for the safety of the tenant, that the conversion price should rather be below than above the average market price. In many places, accordingly, it is not much above one half of this price. Through the greater part of Scotland this custom still continues with regard to poultry, and in some places with regard to cattle. It might probably have continued to take place, too, with regard to corn, had not the institution of the public fiars put an end to it. These are annual valuations, according to the judgment of an assize, of the average price of all the different sorts of grain, and of all the different qualities of each, according to the actual market price in every different county. This institution rendered it sufficiently safe for the tenant, and much more convenient for the landlord, to convert, as they call it, the corn rent, rather at what should happen to be the price of the fiars of each year, than at any certain fixed price. But the writers who have collected the prices of corn in ancient times seem frequently to have mistaken what is called in Scotland the conversion price for the actual market price. Fleetwood acknowledges, upon one occasion, that he had made this mistake. As he wrote his book, however, for a particular purpose, he does not think proper to make this acknowledgment till after transcribing this conversion price fifteen times. The price is eight shillings the quarter of wheat. This sum in 1423, the year at which he begins with it, contained the same quantity of silver as sixteen shillings of our present money. But in 1562, the year at which he ends with it, it contained no more than the same nominal sum does at present.