many situations be get rid of at all, and the mines, after being worked to a little depth, must be abandoned: without ships or boats the sea could never have been crossed; without tools of some sort, trees could not be cut down, nor rocks excavated; a plough, or at least a hoe, is necessary to any tillage of the ground. Very simple and rude instruments, however, are sufficient to render literally possible most works hitherto executed by mankind; and subsequent inventions have chiefly served to enable the work to be performed in greater perfection, and, above all, with a greatly diminished quantity of labour: the labour thus saved becoming disposable for other employments.
The use of machinery is far from being the only mode in which the effects of knowledge in aiding production are exemplified. In agriculture and horticulture, machinery is only now beginning to show that it can do anything of importance, beyond the invention and progressive improvement of the plough and a few other simple instruments. The greatest agricultural inventions have consisted in the direct application of more judicious processes to the land itself, and to the plants growing on it: such as rotation of crops, to avoid the necessity of leaving the land uncultivated for one season in every two or three; improved manures, to renovate its fertility when exhausted by cropping; ploughing and draining the subsoil as well as the surface; conversion of bogs and marshes into cultivable land; such modes of pruning, and of training and propping up plants and trees, as experience has shown to deserve the preference; in the case of the more expensive cultures, planting the roots or seeds further apart, and more completely pulverizing the soil in which they are placed, &c. In manufactures and commerce, some of the most important improvements consist in economizing time; in making the return follow more speedily upon the labour and outlay. There are others of which the advantage consists in economy of material.
