All this points to an immense recrudescence of irrigation in the near future. Already the Californians and other Americans of the Pacific Slope have demonstrated that irrigation is a practice fully as well suited to the requirements of a thoroughly up-to-date people as it has been for long ages to those of the "unchanging East". But here again the question of cheap power obtrudes itself. The Chinese, Hindoos and Egyptians have long ago passed the stage at which the limited areas which were irrigable by gravitation, without advanced methods of engineering, have been occupied; and the lifting of water for the supplying of their paddy fields has been for thousands of years a laborious occupation for the poorest and most degraded of the rural population.
In a system of civilisation in which transport costs so little as it does in railway and steam-ship freights, the patches of territory which can be irrigated by water brought by gravitation from the hills or from the upper reaches of rivers are comparatively easy of access to a market. This fact retards the advent of the time when colossal installations for the throwing of water upon the land will be demanded. When that epoch arrives, as it assuredly will before the first half of the twentieth century has been nearly past, the pumping plants devoted to the purposes of irrigation will present as great a contrast to the lifting appliances of the East as does a fully loaded freight train or a mammoth steam cargo-slave to a coolie carrier.
At the same time there must inevitably be a great extension of the useful purposes to which small motors can be applied in irrigation. Year by year the importance of the sprinkler, not only for ornamental grounds such as lawns and flower-beds, but also for the vegetable patch and the fruit garden, becomes more apparent, and efforts are being made towards the enlargement of the arms of sprinkling contrivances to such an extent as to enable them to throw a fine shower of water over a very large area of ground. Sometimes a windmill is used for pumping river or well-water into high tanks from which it descends by gravitation into the sprinklers, the latter being operated by the power of the liquid as it descends. This mode of working is convenient in many cases; but a more important, because a more widely applicable, method in the future will be that in which the wind-motor not only lifts the water, but scatters it around in the same operation. Long helical-shaped screws, horizontally fixed between uprights or set on a swivel on a single high tower, can be used for loading the breeze with a finely divided shower of water and thus projecting the moisture to very long distances. A windmill of the ordinary pattern, as used for gardens, may be fitted with a long perforated pipe, supported by wire guys instead of a vane, a connection being made by a water-tight swivel-joint between this pipe and that which carries the liquid from the pump. In this way every stroke of the machine sends innumerable jets of water out upon the wind, to be carried far afield.