he substitution of the material for others in uses different from
those in which it is now employed;

(2) The substitution of it for other materials in the marginal parts
of its present field, where it is already nearly as available as other
things;

(3) The substitution of the finished consumers' goods made of it for
other consumers' goods.

In addition to all these there is the direct increase in the use of
finished goods wholly or partly made of the material by persons who do
not, for this reason, discard any other goods.

This statement places the different influences in the order of their
relative efficiency in the majority of cases in which they act.

_Effects of cheapening Tools of Industry._--What is true of a raw
material which enters into many completed products is true of the
tools of industry which are used for many purposes. A turning lathe, a
planing machine, or a circular saw helps to make a large number of
products, and the assertions we have made concerning steel, stone, or
wood apply to it. As it becomes cheaper it gains an enlargement of its
market by a combination of the four influences just enumerated. It is
brought into new uses, is employed more in its present marginal uses,
and is required in greater quantity because its products are
substituted for other things and are also required in greater amounts
independently of these substitutions.

_Cheap Motive Forces._--Motive power is so nearly universal in its
applications that developing a cheap source of it is much like
improving the method of producing everything and securing a universal
increase of products. We shall see why such a general enlargement of
the output of all the shops creates no displacements of labor which
entail hardships. If the power is used more in the upper subgroups
than in the lower ones,--if it is more frequently available for
fashioning raw materials than for producing them through agriculture
or mining,--the development of it checks in some degree the drift of
labor from the lower subgroups toward the upper ones, which has been
referred to in an earlier chapter.

Utilizing the power of Niagara, that of Alpine torrents and other
unused streams, that of the waves of the sea, and that which has long
slumbered in the culm heaps of coal mines, will give increased
facility for producing nearly everything; and though the amount of the
enlargement of output will vary in different cases and some effect on
the movements of