IV

PREFACE.

lies before him. To enable him to perform his multifarious functions with honourto himself and satisfaction to his country is the great object of this Encyclopaedia:and, without further preface, we shall proceed to lay before the reader an outlineof its contents, and the plan we have adopted in its compilation.

The first portion of the work is devoted to the history of the past; for it hasbeen thought that a knowledge of the manner in which others have accomplishedworks similar to those we are called upon to execute at once facilitates our labourand inspires us with confidence in what we are about to undertake.

In treating of Geology , Mineralogy, and Chemistry, the only aim has been topoint out the nature of these subjects, and give a general idea of the properties ofthe materials which form the earth’s crust, with an account of their composition, asfar as might be generally serviceable to those who employ them in the arts ofconstruction, or operate upon them mechanically.

Geometry, as the very foundation of the acquirements of the Civil Engineer,—embracing, as it does, levelling, surveying, the mensuration of planes and solids;trigonometry in all its practical applications; drawing, perspective, mapping, layingdown charts, and all the preliminary steps to great undertakings, as well as theirexecution,—should be made the first study of all who are desirous of becomingacquainted with the other sciences ; for without it, in fact, no portion of them canbe rightly comprehended.

Mechanics are also a most important subject. The ancients, indeed, knew theprinciples of the inclined plane, the wedge, the screw, the lever, and the pulley,and by their application were enabled to move the vast weights accounts of whichare transmitted to us; but the improvements made in machinery in modern timeshave undoubtedly enabled us to execute works of vast magnitude with a greatsaving of manual labour. From experiments upon the strength and properties ofthe metals, and the application of geometry to mechanics, we can construct machines,which from their variety of movement, and the useful purposes to which they areapplied, are inventions and novelties which belong to the present age. The toolsand engines employed by the Civil Engineer are instances of the advancement inthis branch of physics.

Hydrostatics, with the theory of the motion of fluids, and the various hydraulicmachines that have been invented, facilitate the operations of the Engineer inraising water, directing its course usefully and efficiently, whether for sanatory,domestic, or agricultural, purposes; and without an almost complete command overthis element, he can scarcely be considered worthy of his high vocation.

The nature of the Atmosphere, and its properties as a moving power, has greatlyoccupied the attention of mechanics in all ages, and its services cannot be toohighly appreciated. For the construction of windmills and similar contrivances,numerous experiments have been made, replete with benefit to the millwright.

Warming and Lighting are daily becoming matters of public attention, and musttherefore occupy the consideration of every man of science; but the Civil Engineer must beware of fanciful theories: whatever may be his system, it must be based ona thorough knowledge of the elements which he is to direct, and he must never losesight of the requisite balance to be maintained between the heat generated and theventilation. Lighting our coasts has occupied the attention of such philosophers asProfessor Faraday , whose interesting discoveries have greatly improved our light-houses, and elevated this subject into an important science.

Gas Lighting has its engineers, who have improved the methods of distilling coal,and laid down principles to direct the proportions of every part of the establishmentwhere such works are conducted.

Steam, considered as a moving power, is the most extraordinary discovery of thisor any other age. liy its application manual and horse labour have been greatlyeconomised; machinery of every kind is set in motion; and millions of humanbeings are transported in a short space of time from one end of the empire to theother. This branch of our subject, it is unnecessary to add, particularly deservesour study.

Carpentry, which embraces the construction of timber roofs, _ bridges, centres,scaffolding, ifc., with a thorough knowledge of the use and properties of timber, hasbeen treated at considerable length; though not more so than the importance ofthe subject demands. Although iron has in this country superseded the employmentof timber in many instances, there are occasions in which the carpenter’s art