_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 labor will be produced, few serious hardships will result, and a majority of the persons who will suffer from these changes at all will get an offsetting benefit from the enlarging productiveness of industry. CHAPTER XVII FURTHER INFLUENCES WHICH REDUCE THE HARDSHIPS ENTAILED BY DYNAMIC CHANGES