But more especially, the revolution in modes of production of industry and agriculture made necessary a revolution in the means of communication and transportation. These, in the form in which they had been handed down from the earlier period, became unbearable trammels on modern industry, with its feverish haste of production, its enormous extent, its constant flinging of capital and labor from one sphere of production into another, and its newly established connections with the markets of the whole world. Hence, apart from the radical changes introduced in the construction of sailing vessels, the means of communication and transportation became gradually adapted to the modes of production of mechanical industry, by the creation of a system of river steamers, railways, ocean steamers, and telegraphs. But the huge masses of iron that had now to be forged, to be welded, to be cut, to be bored, and to be shaped, demanded, on their part, monster machines, for the construction of which the methods of the manufacturing period were utterly inadequate.

Modern industry had therefore itself to take in hand the machine, its characteristic instrument of production, and to construct machines by machines. It was not till it did this, that it built up for itself a fitting technical foundation and stood on its own feet. Machinery, simultaneously with the increasing use of it, in the first decades of this century, appropriated by degrees the fabrication of machines proper. But it was only during the decade preceding 1866 that the construction of railways and ocean steamers on a stupendous scale called into existence the cyclopean machines now employed in the construction of "prime movers," or motors.

The most essential condition for the production of machines by machines was a prime mover capable of exerting any amount of force, and yet under perfect control. This condition was already supplied by the steam engine, but at the same time it was necessary to produce the geometrically accurate straight lines, planes, circles, cylinders, cones, and spheres, required in the detail parts of the machines. This problem Henry Maudsley solved in the first decade of this century by the invention of the slide rest, a tool that was soon made automatic, and in a modified form was applied to other constructive machines besides the lathe, for which it was originally intended. This mechanical appliance replaces not some particular tool but the hand itself, which must, in order to produce a given form, hold and guide the cutting tool along the iron or other material operated upon. Thus it became possible to produce the individual parts of machinery with a degree of ease, accuracy, and speed that no accumulated experience of the hand of the most skilled workman could give.