TWO:Wind-power, aside from the objections of uncertainty and irregularity, is the cheapest kind of motive-power. Steam machinery, besides costing a large sum as an investment, is continually deteriorating in value, consumes fuel, and requires continual skilled attention. Water-power also requires a large investment, greater in many cases than steam-power, and in many places the plant is in danger of destruction by freshets. Wind-power is less expensive in every way, but is unreliable for constancy except in certain localities, and these, as it happens, are for the most part distant from other elements of manufacturing industry. The operation of wind-wheels is so simple and so generally understood that no reference to mechanism need be made here. The force of the wind, moving in right lines, is easily applied to producing rotary motion, the difference from water-power being mainly in the comparative weakness of wind currents and the greater area required in the vanes upon which the wind acts. Turbine wind-wheels have been constructed on very much the same plan as turbine water-wheels. In speaking of wind-power, the propositions about heat must not be forgotten. It has been explained how heat is almost directly utilised by the steam-engine, and how the effect of heat is utilised by water-wheels in [42] a less direct manner, and the same connection will be found between heat and wind-wheels or wind-power. Currents of air are due to changes of temperature, and the connection between the heat that produces such air currents and their application as power is no more intricate than in the case of water-power.A great reformer of the last generation, finding that the idea of Nature was constantly put forward to thwart his most cherished schemes, prepared a mine for its destruction which was only exploded after his death. Seldom has so powerful a charge of logical dynamite been collected within so small a space as in Mills famous Essay on Nature. But the immediate effect was less than might have been anticipated, because the attack was supposed to be directed against religion, whereas it was only aimed at an abstract metaphysical dogma, not necessarily connected with any theological beliefs, and held by many who have discarded all such beliefs. A stronger impression was, perhaps, produced by the nearly simultaneous declaration of Sir W. Gullin reference to the supposed vis medicatrix naturaethat, in cases of disease, what Nature wants is to put the man in his coffin. The new school of political economists have also done much to show that legislative interference with the natural laws of wealth need by no means be so generally mischievous as was once supposed. And the doctrine of Evolution, besides breaking down the old distinctions between Nature and Man, has represented the former as essentially variable, and therefore, to that extent, incapable of affording a fixed standard for moral action. It is, however, from this school that a new49 attempt to rehabilitate the old physical ethics has lately proceeded. The object of Mr. Herbert Spencers Data of Ethics is, among other points, to prove that a true morality represents the ultimate stage of evolution, and reproduces in social life that permanent equilibration towards which every form of evolution constantly tends. And Mr. Spencer also shows how evolution is bringing about a state of things in which the self-regarding shall be finally harmonised with the social impulses. Now, it will be readily admitted that morality is a product of evolution in this sense that it is a gradual formation, that it is the product of many converging conditions, and that it progresses according to a certain method. But that the same method is observed through all orders of evolution seems less evident. For instance, in the formation, first of the solar system, and then of the earths crust, there is a continual loss of force, while in the development of organic life there is as continual a gain; and on arriving at subjective phenomena, we are met by facts which, in the present state of our knowledge, cannot advantageously be expressed in terms of force and matter at all. Even if we do not agree with George Sand in thinking that self-sacrifice is the only virtue, we must admit that the possibility, at least, of its being sometimes demanded is inseparable from the idea of duty. But self-sacrifice cannot be conceived without consciousness; which is equivalent to saying that it involves other than mechanical notions. Thus we are confronted by the standing difficulty of all evolutionary theories, and on a point where that difficulty is peculiarly sensible. Nor is this an objection to be got rid of by the argument that it applies to all philosophical systems alike. To an idealist, the dependence of morality on consciousness is a practical confirmation of his professed principles. Holding that the universal forms of experience are the conditions under which an object is apprehended, rather than modifications imposed by an unknowable object on an unknowable subject, and that these50 forms are common to all intelligent beings, he holds also that the perception of duty is the widening of our individual selves into that universal self which is the subjective side of all experience.