volutions been practically exhausted? The belief impressed upon the Author's mind, by facts and considerations evoked during the collection of materials for this book, is that the march of industrial progress is only just beginning, and that the twentieth century will witness a far greater development than the nineteenth has seen.

The great majority of mankind still require to be released from the drudgery of irksome, physical exertion, which, when power has been cheapened, will be seen to be to a very large extent avoidable. Pleasurable exercise will be substituted for the monotonous, manual labour which, while it continues, generally precludes the possibility of mental improvement. Hygienic science will insist more strenuously than ever upon the great truth that, in order to be really serviceable in promoting the health of mind and body, physical exertion must be in some degree exhilarating, and the bad old practice of "all work and no play," which was based upon the assumption that a boy can get as much good out of chopping wood for an hour as out of a bicycle ride or a game of cricket, will be relegated to the limbo of exploded fallacies.

The race, as a whole, will be athletic in the same sense in which cultured ladies and

gentlemen are at present. It will, a century hence, offer a still more striking contrast to the existing state of the Chinese, who bandage their women's feet in order to show that they are high born and never needed to walk or to exert themselves!-the assumption being that no one would ever move a muscle unless under fear of the lash of poverty or of actual hunger. The farther Western civilisation travels from that effete Eastern ideal, the greater will be the hope for human progress in physical, mental and moral well-being.

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CHAPTER II.

NATURAL POWER.

NATURE," remarked James Watt when he set to work inventing his improved steamengine, “has always a weak side if we can only find it out." Many invaluable secrets have been successfully explored through the discovery of Nature's "weak side" since that momentous era in the industrial history of the world; and the nineteenth century, as Watt clearly foresaw, has been emphatically the age of steam power. In the condenser, the high pressure cylinder and the automatic cutoff, which utilises the expansive power of steam vapour, mankind now possesses the means of taming a monster whose capacities were almost entirely unknown to the ancients, and of bringing it into ready and willing service for the accomplishment of useful work. Vaguely and loosely it is often asserted that the age of steam is now giving place to that of electricity; but these two cannot yet be logically placed in opposition to one another. No method has yet been discovered whereby the heat of a

furnace can be directly converted into an electric current. The steam-engine or, as Watt and his predecessors called it, the "fireengine" is par excellence the world's prime motor; and by far the greater proportion of the electrical energy that is generated to-day owes its existence primarily to the steamengine and to other forms of reciprocating machinery designed to utilise the expansive power of vapours or gases acting in a similar

manner to steam.

The industrial revolutions of the coming century will, without doubt, be brought about very largely through the utilisation of Nature's waste energy in the service of mankind. Waterfalls, after being very largely neglected for two or three generations, are now commanding attention as valuable and highly profitable sources of power. This is only to be regarded as forming the small beginning of a movement which, in the coming century, will "acquire strength by going," and which most probably will, in less than a hundred years, have produced changes in the industrial world comparable to those brought about by the invention of the steam-engine.

Lord Kelvin, in the year 1881, briefly, but very significantly, classified the sources of power available to man under the five primary

headings of tides, food, fuel, wind, and rain. Food is the generator of animal energy, fuel that of the power obtained from steam and other mechanical expansive engines; rain, as it falls on the hill-tops and descends in long lines of natural force to the sea coasts, furnishes power to the water-wheel; while wind may be utilised to generate mechanical energy through the agency of windmills and other contrivances. The tides as a source of useful power have hardly yet begun to make their influence felt, and indeed the possibility of largely using them is still a matter of doubt. The relative advantages of reclaiming a given area of soil for purposes of cultivation, and of converting the same land into a tidal basin in order to generate power through the inward and outward flow of the sea-water, were contrasted by Lord Kelvin in the statement of a problem as follows: Which is the more valuable-an agricultural area of forty acres or an available source of energy equal to one hundred horse-power? The data for the solution of such a question are obviously not at hand, unless the quality of the land, its relative nearness to the position at which power might be required, and several other factors in its economic application have been supplied. Still, the fact remains that very large quantities of the