HYDRAULIC ENGINEERING.
As the earliest works for the protection of the land from overflow by water grew out of the necessity of guarding the settlements and the habi tations of mankind from destruction by inundations, so the necessity of supplying-vegetation with the water needful for its growth gave rise to the construction of works for providing artificial supplies of this element, and for the irrigating of districts naturally destitute of it or whose supplies were uncertain in quantity; and so, likewise, the desire to transform unwhole some and useless marsh-lands into fertile fields and to reclaim from the waters lands suited for agricultural purposes originated extensive works for drainage.
With advancing culture, communication by water increased, and to facilitate the navigation of streams various works for their regulation and correction became necessary. Navigable canals were at length constructed, establishing, by convenient water highways, communication between rivers or between rivers and distant oceans and their ports. The ever-increasing
population of cities and towns in time rendered it necessary to provide extensive hydraulic constructions in the form of aqueducts, canals, etc. for conducting and distributing their water-supplies, and the rapid growth of the industries called into existence many forms of construction and appli ances for utilizing water as a motive-power. Filially, the execution of the various works—such as bridges, aqueducts, locks, and the like— needed in the construction of roads, railways, canals, etc., has demanded the invention and perfection of many modes of securing- artificial founda tions, which are sufficiently important to constitute of themselves a special branch of hydraulic engineering, to the consideration of which the reader's attention is invited.