Sec. 6] VALUE OF CAPITAL 211

misnomer. We can imagine an article which suffers no
material change, and of which the services will nevertheless
last only a limited period. On the Atlantic coast the fishermen
 sometimes construct temporary platforms which
are pretty sure to disappear in the September gales. It
is evident that the value of such a property will decrease
rapidly as the end of the fishing season approaches, without
this decrease being due in the least to any physical deterioration.
 The “World's Fair” buildings at St. Louis depreciated,
 during the brief period of the fair, from $15,000,000,
which was first paid for their construction, to $386,000, for
which they were sold after they had served the purpose for
which they were built. In like manner, a small wooden
bridge, which is to be supplanted by a larger and better
structure near by, will decrease in value rapidly as the time
approaches for the other structure to divert its traffic,
without any corresponding physical deterioration. Examples
 are common enough of productive instruments losing
their value, because of its being known that better devices
are soon to displace them. “Wear and tear,” therefore, is
a phrase which we must use only in a metaphorical sense.
Even when the wear and tear take place because of physical
 deterioration, this deterioration acts upon the value only
in so far as it decreases or terminates the flow of income,
and not because of a physical change in the capital which
bears this income! The value of the capital depends exclusively
 on the income from it, and not directly upon its
physical condition. ;

§7
Having considered the case of a terminable annuity, we
turn to the case of a bond, which entitles the holder
not only to a terminable annuity, but also to a single deferred
 sum called the principal.” Thus, a so-called * five

1 Of. Bohm-Bawerk, Positive Theory of Capital, English translation,
1801, p. 347.