FORE:To construe the term "transmission of power" in its full sense, it will, when applied to machinery, include nearly all that has motion; for with the exception of the last movers, or where power passes off and is expended upon work that is performed, all machinery of whatever kind may be called machinery of transmission. Custom has, however, confined the use of the term to such devices as are employed to convey power from one place to another, without including organised machines through which power is directly applied to the performance of work. Power is transmitted by means of shafts, belts, friction wheels, gearing, and in some cases by water or air, as various conditions of the work to be performed may require. Sometimes such machinery is employed as the conditions do not require, because there is, perhaps, nothing of equal importance connected with mechanical engineering of which there exists a greater diversity of opinion, or in which there is a greater diversity of practice, than in devices for transmitting power.The evolution of Greek tragic poetry bears witness to the same transformation of taste. On comparing Sophocles with Aeschylus, we are struck by a change of tone analogous to that which distinguishes Thucydides from Herodotus. It has been shown in our first chapter how the elder dramatist delights in tracing events and institutions back to their first origin, and in following derivations through the steps of a genealogical sequence. Sophocles, on the other hand, limits himself to a close analysis of the action immediately represented, the motives by which his characters are in91fluenced, and the arguments by which their conduct is justified or condemned. We have already touched on the very different attitude assumed towards religion by these two great poets. Here we have only to add that while Aeschylus fills his dramas with supernatural beings, and frequently restricts his mortal actors to the interpretation or execution of a divine mandate, Sophocles, representing the spirit of Greek Humanism, only once brings a god on the stage, and dwells exclusively on the emotions of pride, ambition, revenge, terror, pity, and affection, by which men and women of a lofty type are actuated. Again (and this is one of his poetic superiorities), Aeschylus has an open sense for the external world; his imagination ranges far and wide from land to land; his pages are filled with the fire and light, the music and movement of Nature in a Southern country. He leads before us in splendid procession the starry-kirtled night; the bright rulers that bring round winter and summer; the dazzling sunshine; the forked flashes of lightning; the roaring thunder; the white-winged snow-flakes; the rain descending on thirsty flowers; the sea now rippling with infinite laughter, now moaning on the shingle, growing hoary under rough blasts, with its eastern waves dashing against the new-risen sun, or, again, lulled to waveless, windless, noonday sleep; the volcano with its volleys of fire-breathing spray and fierce jaws of devouring lava; the eddying whorls of dust; the resistless mountain-torrent; the meadow-dews; the flowers of spring and fruits of summer; the evergreen olive, and trees that give leafy shelter from dogstar heat. For all this world of wonder and beauty Sophocles offers only a few meagre allusions to the phenomena presented by sunshine and storm. No poet has ever so entirely concentrated his attention on human deeds and human passions. Only the grove of Col?nus, interwoven with his own earliest recollections, had power to draw from him, in extreme old age, a song such as the nightingale might have warbled amid those92 inviolable recesses where the ivy and laurel, the vine and olive gave a never-failing shelter against sun and wind alike. Yet even this leafy covert is but an image of the poet��s own imagination, undisturbed by outward influences, self-involved, self-protected, and self-sustained. Of course, we are only restating in different language what has long been known, that the epic element of poetry, before so prominent, was with Sophocles entirely displaced by the dramatic; but if Sophocles became the greatest dramatist of antiquity, it was precisely because no other writer could, like him, work out a catastrophe solely through the action of mind on mind, without any intervention of physical force; and if he possessed this faculty, it was because Greek thought as a whole had been turned inward; because he shared in the devotion to psychological studies equally exemplified by his younger contemporaries, Protagoras, Thucydides, and Socrates, all of whom might have taken for their motto the noble lines��