57. Valuations of lands by the proportion of their revenue,
with the sum of personal property, or the value for which they
are exchanged: this proportion is called the price of lands.
It is evident, that if land, which produces a revenue
equivalent to six sheep, can be sold for a certain value, which
may always be expressed by a number of sheep equivalent to that
value; this number will bear a fixed proportion with that of six,
and will contain it a certain number of times. Thus the price of
an estate is nothing else but its revenue multiplied a certain
number of times; twenty times if the price is a hundred and
twenty sheep; thirty times if one hundred and eighty sheep. And
so the current price of land is reckoned by the proportion of the
value of the revenue; and the number of times, that the price of
the sale contains that of the revenue, is called so many years
purchase of the land. They are sold at the price of twenty,
thirty, or forty years purchase, when on purchasing them we pay
twenty, thirty, or forty times. their revenue. It is also not
less evident, that this price must vary according to the number
of purchasers, or sellers of land, in the same manner as other
goods vary in a ratio to the different proportion between the
offer and the demand.
