corn required no less productive region can force the normal
price above what will keep western farmers raising corn. When the western
crop fails, the price is far above normal value, and may even go above the
cost of the most costly corn in market, under a principle called the law
of supply and demand.

Since improvements in method so constantly lessen the normal value of
products, Mr. Carey made the effort to measure value by "cost of
reproduction," meaning, I suppose, that any article produced at any time
and place is likely to bring in any market a price equal to the cost of
similar articles produced under the most improved methods anywhere used in
the present. This, of course, does not apply to articles not desired in
the present, because deteriorated or out of fashion or less useful than
some new device for a similar use, but only to those articles of full
utility in having all the qualities needed to meet the desire of
purchasers. Even a diamond like the famous "Kohinoor" would have its
almost priceless value reduced to the cost of securing similar jewels
equally desirable if a process of crystallizing carbon were suddenly
discovered. It is easy to see, then, that cost measures value only so far
as it is directly connected with the available supply in any market. Under
ordinary circumstances the supply cannot be increased unless the cost is
met, but the rule is modified by any peculiarity of season, or conditions
of trade, or production by cheaper methods or cheaper labor, or by the
changing wants of a community. The application of all these influences may
be studied under the so-called law of supply and demand.

_Supply and demand; markets._--The law of supply and demand is only a
statement of the general fact that market value tends to increase with
increase of demand and to decrease as the supply to meet the demand
increases. It must be understood that a market means a particular spot
where buyers and sellers of any article of commerce meet at a particular
time. The supply is the amount offered for sale at a given price. The
demand is the amount buyers will purchase at the same price.

Thus, if on a certain day sellers offer in Chicago 10,000 hogs, with a
willingness to take $5 per cwt., they represent the supply. If on the same
day in the same place buyers are willing to take 10,000 hogs at $5 per
cwt., $5 will be the market price, and the supply and demand will be
equal. If, however, only 5,000 hogs would b