Agricultural Hall, a building in the Centennial Exhibition, was spe cially remarkable for the originality of its design. The structure consisted of a long nave crossed by three transepts, all composed of Howe truss arches of Gothic form. The four courts between the nave and the transepts, as well as the four spaces at the corners of the structure, having the nave and the transepts for two of their sides, were roofed, and formed spaces for ex hibits. The nave ran north and south, and was Szo feet long, r25 feet wide, with a height of 75 feet from the ground at the top of the arch. The remaining three transepts ran-east and west, one at each end of the build ing 54o feet long and 3o feet wide, and one in the centre 54o feet long and 6o feet wide. The building was thus divided into sections, each of which had aisles r97 feet long and r3 feet wide extending through it and com municating with the avenues and passage-ways. The entire structure covered ten and a quarter acres of ground, and the arrangement was much admired for its novelty and grace, the general appearance resembling that of a great cathedral.
Roads and Streets The Orient, the cradle of civilization, yields us the earliest referencesto artificial roadways. Those built by Semiramis are the first of which history makes mention, and an artificial road is known to have been built between the ancient cities of Snsa and Sardis, a distance of about t WO thousand miles. The Carthaginians, a people noted for their commer cial and military spirit, were also builders of roads, and the oldest Chinese works of this description were made so substantial and enduring that thev are serviceable to the present day. The Greeks, particularly the Athe nians, built excellent highways, certain of which, as the sacred road to Delphi, were dedicated to religious uses; at Cyrene, also, was a notable work of the saine kind.
Roman Romans, however, far surpassed all their prede cessors and all their contemporaries in the magnitude and excellence of their works of this character. Built primarily for the purpose of facilitat ing their vast military operations, to which they rendered most import ant aid, they were esteemed so essential that, notably under Augustus, Vespasian, and Trajan, highways were made from Rome to all parts of the Empire, even through regions where Nature had interposed the most seri ous obstacles. Imposing remains of these works, which may even yet be found in nearly every country of Europe, testify to the pre-eminence of the Romans as builders of roads. The care which they bestowed upon their great highways will appear from the following analysis of their construc tion. The base of the roadway was formed of one or two layers of stone
laid in mortar (statumen); upon this followed a course of broken stone and mortar (rua'lls); over this was placed a layer of finely-broken stone with freshly-slaked lime (nucleus), which served as the bed of the stone pave ment proper, composed of polygonal stone slabs (S7111111111111 a'orsum); or the stone pavement was sometimes omitted, in which case the third course of the road was formed of the largest obtainable cobbles, and the road-surface becanie summa crusta. In the Middle Ages the Roman roads were allowed to fall into decay, and, save in rare cases, no new ones were laid out.
Modern down to modern times. the building of road 149 wavs was begun first in Holland; afterward they were constrncted in Spain and England. In Germany the first highway was built in 1753, between Oettingen and Nordlingen. About the same period much activity WaS dis played in France in the construction of works of this character.
The Ectrik roadways in respect of the mode of constrnction, it will be proper to proceed from the crudest forms—the sim ple earth roads, or the rough temporary structures intended to facilitate the conveyance of heavy materials for industrial or military operations—to the established highways constructed in the most substantial manner and con stituting the principal channels of trade. The earth road, which is com mon in all countries, and is necessarily the chief dependence for intercom munication in all new countries, is formed by excavating the natural soil from lateral ditches and spreading this ont to constitute the covering of the roadway, the side-ditches serving- for draining the surface. In many cases, especially where the soil is sandy or gravelly, no provision for other than natural drainage is attempted, and the road is simply a wagon-track on the natural surface of the gronnd.
Cordhroy the passage of swamp- or marsh-land the expe dient usually is adopted of forming for vehicles a roadway of straight either round or split, whose length is suited to the required width of the road; these log-s are laid side by side, the joints or openings between them being- levelled up as evenly as possible with smaller pieces haying the same length as the larg-er logs, but split to a triang-tilar cross-section and inserted into the interstices with one edge down, so as to form a flat surface. In the United States such roads are called " corduroy roads." A modification of the corduroy road is the timber causeway shown in Figure (i5/. zo).