The same rule applies to the frustrum of a cone. Elizabethan Architecture, the style which prevailed in England at the time of Queen Elizabeth, and immediately subsequent to the Tudor style of Henry VIII. Ellipse: this curve is one of the conic sections, and next in importance to the circle and the straight line Ellipsis, an oval figure generated from the section of a cone by a plane cutting both sides of the cone, but not parallel to the base, and meeting with the base when produced Elliptic compasses, a term given to any machine for describing ellipses Elliptograph, an instrument for drawing ellipses

Elvan, (in Cornish), a hard closegrained stone, said to be a bastard limestone Embankments, raised mounds or dykes to preserve the proper and useful course of rivers, &c.; and also for forming a level line of railway Embankments (some) executed on the Continent. On the banks of the Po, two sorts of dykes are used to prevent the river from overflowing during the winter, or the flood season. They are called in froldi' when immediately upon the banks of the river, and 'in golene' when at any considerable distance, as it is sometimes found advisable to allow the river to spread over a large surface of the adjacent valley, either for the purpose of admitting it to deposit the mud in suspension, or to allow it to lose its torrential character. The maintenance of the works of these dykes is confided to the Government engineers, who are under the control of a syndicate of the proprietors of the property most liable to be affected by inundations. When the river passes from one state to another, as from Piedmont to Modena, a mixed commission is charged with the joint superintendence.

Elm, atimber-tree, of European growth, and of which there are five species: mean size, 44 feet long, 32 inches diameter: it is not liable to split, and bears the driving of nails, bolts, &c. much used in building; also for the keels of vessels, and for wet foundations.

Elongation, the act of lengthening Elutriation, the separation of foul substances from pure, by pulverization

The Haarlem lake, besides the very remarkable steam engines described by Mr. Dempsey, merits observation for the extensive works executed for the defence of the land, and for the canals reserved for the navigation. The enclosure dyke is 50,000 metres long, or rather more than 31 miles. It has two outfall dykes, which serve for the navigation, 9000 metres, about 5 miles; one-half of which is 40m. (131 ft. 2 in.) wide at the bottom or floor line; the other 43m.20 (141 ft. 10 in.)

The ordinary tides are, at the flux, 2 ft. 4 in. above the scale or datum line at Amsterdam; at the reflux, 2 ft. 8 in. below the same datum: the difference between high and low water is then, on the

average, about 5 feet. With violent winds from the N. w. however, the tides rise sometimes 6 ft. 6 in. above the average. The tides of the Y, near the lake, are +16c (or 6 in.) and 23c. (or 9 in.), giving a total variation of 1 ft. 3 in.

The estimated cost of reclaiming the 18,000 hectares was 8 millions of florins, or £667,000 English, nearly, about £ 13 per acre. Previously to undertaking this colossal work, the Zind Plas, of 4600 hectares superficial (nearly 11,500 acres), had been reclaimed at a cost of 3 millions of florins, or £250,000; not far from £22 per acre.

The heights of the enclosure dyke are or the datum line at Amsterdam, or the mean level of the sea in that port. Embankment of the flooded part of the Amsterdam and Haarlem Railway. The bottom part consists of treble ranges of fascines, tied down by longitudinal poles 1 metre apart from centre to centre, and 0.25c. diameter; two double stakes at each end of the poles, and two ties in the intermediate distances. The interstices of the fascines and the space between the rows are filled in with sand. The upper part, forming the encasement for the ballast, is made of three rows of treble fascines, well staked, and wattled together.

A core of sand or clay, faced with step fascines, is made up to lowwater mark. Upon this a bed of rushes, fastened down by stakes and wattles, is laid; and the upper portion of the bank is faced with fascines of a regular slope of 1 to 1. Embattled, a term applied to any building with a parapet, and having embrasures to resemble a battery Emblema, an emblem, or inlaid ornament of divers colours Embolus, in mechanics, a wedge; anciently, among the Greeks, the prow or beak of a vessel, or a body of soldiers in the form of a wedge Embossing, forming work in relievo,

whether cast or cut with a chisel; or in modern times, the art of producing raised figures upon wood or other materials by means of pressure, either applied by a sudden blow, as in a stamping press, or in a more gradual manner, as by an ordinary screw or hydraulic press, or by means of revolving cylinders

Embrasure, the crenelles or intervals between the merlons of a battlement Embroidery, a mode of working devices on woven substances Emerald green is a new colour of cop

per green upon a terrene base: it is the most vivid of this tribe of colours, being rather opaque, and powerfully reflective of light: it appears to be the most durable pigment of its class Emissarium, a sluice, flood-gate, or channel by which an outlet is formed to carry off stagnant or foul water: according to Pliny, an artificial canal formed for the draining of stagnant waters

Emplecton, a method of constructing walls introduced by the Greeks and copied by the Roman architects, in which the outside surfaces on both sides were formed of ashlar laid in regular courses, and the central space between them filled in with rubble-work, layers of cross stones being placed at intervals in regular courses, and of sufficient size to extend through the entire thickness of the wall from side to side, and so act as girders to bind the whole together Emporium, a mart or factory, a large

building containing ranges of bonding warehouses, in which foreign merchandise brought by sea is deposited for sale Enamelling, the art of using enamel,

which is divided into transparent and opaque. The first is employed for the purpose of ornamenting gold and silver; the second, commonly in the manufacture of watch and clock dials, and of plates for pictures, &c.

Encarpa, according to Vitruvius, fes

toons of carved fruit and flowers, employed as decorative ornaments Encarpus, a festoon of fruit, flowers, &c., used as ornaments on friezes Encaustica, the art of encaustic painting, i. e. in colours mixed with wax, and afterwards hardened by the action of fire Encaustic painting, a kind of painting in which, by heating or burning in, the colours are rendered permanent in all their original splendour Enchasing, the art of enriching and beautifying gold, silver, and other metal work, by some design or figure represented thereon in low relievo

Enclosure, a fence, a wall, or hedge, or

other means of protection and security surrounding land Endecagon, in geometry, a plane figure of eleven sides and angles End-irons, andirons or dogs, articles of household furniture in earlier times, used in fire-places to sustain the ends of logs of wood Engineering, Civil. This profession

may be said to have originated in England about the middle of the last century. Before that period, whenever the prospects of great profit induced individuals or bodies to incorporate themselves for the purpose of undertaking extensive systems of drainage, or for the supply of water, requiring the assistance of an engineer, recourse was generally had to those great masters of hydraulic engineering, the Dutch. True it is that some solitary exceptions have occasionally been found; men who, like Sir Hugh Myddelton, combined a speculative turn of mind with some mechanical knowledge, and to these two qualities added an untiring energy of purpose, leading them to persevere in any undertaking, even under the most discouraging circumstances. But these men were rare instances of a peculiar talent, which, though it thus displayed itself occasionally, was far too uncommon a gift to allow the possessors of it to form a

class or profession. The case is very different now: a demand for this peculiar talent has been created of late years by the extraordinary development of our system of internal communication, as well as by the application of steam to the purposes of our manufactures; and employIment is now found for hundreds where one was sufficient, not fifty years since, for the whole business of the country. So great indeed has been the demand, that the profession may be said to be divided into two distinct bodies, viz. those who turn their attention to subjects which come more particularly within the scope of the duty of a civil engineer, such as docks, bridges, canals, railroads, &c., and those who devote themselves altogether to the manufacture of machinery. The duties which are involved in the practice of these two branches of the profession, though apparently dissimilar in character, are yet founded upon the same general principles; and the acquirements which are necessary to enable the individual of one class to distinguish himself, or even to practise his profession with a moderate chance of success, will be found equally necessary for those of the other class.

These acquirements are partly abstract and theoretical, and partly experimental or practical. A civil engineer should, in addition to the knowledge required to fit him as well as others for the active duties of life, have such a knowledge of mathematics as will enable him to investigate as well as to apply the rules laid down by writers on those branches of the mixed sciences to which his attention will most frequently be drawn. He should be well acquainted with the principles of mechanics, hydraulics, and indeed Iwith all the branches of natural philosophy; and a certain amount of chemical knowledge will be found very valuable: he should be able to

draw neatly, and should understand the principles of projection upon which all engineering drawings are constructed a general knowledge of the principles of architecture will also be essential. Having acquired the requisite amount of theoretical information, the next step is to gain that practical knowledge which is essential in order to the proper application of this information. The best mode of gaining this experience is to enter into the employment of some eminent man in the profession, in whose office there will be every opportunity offered to the young beginner of witnessing the mode in which the various descriptions of work are carried on. He will there be employed, first as a draughtsman, in copying drawings: as he becomes more acquainted with practical details, he will have more responsibility thrown upon him, and be placed in charge of works, at first of small importance, but, by degrees, of those of such magnitude as will require all his theoretical knowledge, and all the practical experience he may have gained, to enable him to carry out the work to the satisfaction of his employers: he should cultivate a habit of observation, and make a point of taking ample notes and sketches of whatever he may see which in any way bears upon his profession. Having thus by degrees acquired a sufficient amount of information to give him a confidence in his own judgment upon any subject which may be submitted to him, and having become known as an active and intelligent agent of others, he will very possibly be called upon to plan and execute a work himself, and then, by degrees, with industry and activity, may work his way upwards in a profession where merit alone can lead to distinction.

The course of the man who devotes himself to the machinery branch of the profession differs but little, up to a certain point, from

that just described: his theoretical acquirements should be the same, but the practical part of his education will commence at the bench, where he will learn the use of all the tools and machinery by working at them with his own hands: he will then be placed in the drawing room, and go through much the same routine of instruction as before described, and will by degrees work his way up to the position of foreman; then, distinguishing himself by a power of applying general principles to particular cases, he will show himself capable of assuming the direction of an establishment for the manufacture of machinery. Engineer, Steam-boat. A steam-boat engineer is a person employed for the purpose of keeping the engine or engines of a steam vessel in as efficient a state as possible, and to superintend their working.

He must set the engines to work, regulate their speed, and stop them as may be required. His duties while the engines are at work are various. He must take care that every moving part is properly lubricated; that no steam is allowed to pass through valves or joints that ought to be steam-tight; that no air is permitted to enter into any of the parts of the engine where it is essential that a vacuum should be kept up; and that none of the bolts, or pins, or keys, work loose by the vibration, and shift their position, or come out of their places. He must also take care that none of the working parts become overheated by any undue amount of friction, arising from any want of proper lubrication, any excessive tightness, or any other disturbing cause; and if they should become overheated, he must take prompt and energetic measures to remedy the evil, and prevent any serious consequences arising therefrom. He must from time to time carefully observe the effect produced by the gradual wear of the working parts, so that if the