250
HISTORY OF ENGINEERING.
Book L
Trenzi, where there arc seven locks, which are supposed to be the first introduced intoFrance , by the engineer Hugues Cromier; they are from 125 feet in length to 165, andin breadth 14 feet 6 inches ; their rise varies from 5 feet 4 inches to 14 feet; the breadthof the canal also varies from 25 to 32 feet, the boats draw a little less than 3 feet water.
Canal of Orleans is in length about 45 miles, and has 28 locks, varying from 136 feetto 178 feet in length, and from 5 feet 6 inches to 12 feet 6 inches rise. The breadth ofthe canal varies from 25 feet to 32 feet at the surface, and the depth is about 4 feet 6 inches.The boats are about 100 feet in length, and nearly 14 in breadth; this work was completedby ltegimorte in 1725.
Bridges. The examples left in the southern districts of France by the Romans havebeen partly described ; and after the dismemberment of the western empire scarcely anyconstructions in stone were commenced till the twelfth century, when necessity producedthroughout France and Germany a religious association, which took the name of “Brothersof the Bridge ; ” they established houses of accommodation for travellers, and built bridgeswhen the rivers were dangerous or difficult to ford. One of the earliest constructed wasat Durance, below the ancient Chartreuse at Bonpas, but due consideration not having beengiven to the water-way, it was soon demolished by the floods to which this river is subject.
Another was built at Avignon about 1177, and the funds were obtained by a pretendedmiracle, the proces verbal of which is still retained in the Town Hall.
The bridge of St. Esprit and of Guillatiere at Lyons, built at the time Bope Innocent1 V. inhabited France , and that of the Saut du Rhone, on the road from Vienne to Geneva ,were erected by the “ Brothers of the Bridge.”
During the reigns of Charles VIII. , Louis XII. , and Francois I. , many bridges wereconstructed, which sustained mansions or buildings of defence, and it became generalthroughout Europe to adopt this system, particularly in cities, where building sites for theincreasing inhabitants could not be obtained.
The Bridge cmd Chateau of Chenonceaux , commenced by the chamberlain, ThomasBolder, who died in 1524, is an excellent example of such structures ; upon the piers ofthis bridge the architect Ducerceau constructed a gallery for the Queen Catherine de Medicis , who was charmed with the beauty of the surrounding scenery.
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CHENONCEAUX.
To the great bridge built on the Rhone succeeded some of single arches of great span :those of Ceret , Nions, Castellano, Ville Neuve d’ Ag<»n, are from 98 to 164 feet span. Thebridge of Vieille Brioude, over the Allier , was the boldest of all; its single arch is above177 feet. It was built in 1454 at the expense of a lady of that place. In 1545,Cardinal de Tournon constructed a bridge near the town of that name over the torrent ofthe Daux of a single arch, 160 feet span.
These bridges are built very economically, and have nearly the same character. Iheirbreadth is generally from 13 feet to 16 feet, and few exceed 20 feet. Except thoseon the Rhone, which are very well constructed, the faces only of the arches are ofsquared stone, and the voussoirs are very small; the rest is of rubble. 'Hie haunchesare filled with earth. The piers are always very thick, and above high water theirfacings only are of stone. The interior is generally filled with earth or sand ; theyseldom have side walls; some portions of walls, founded upon piles, and attached to theabutments in the line of the heads, generally take their place ; the erection of all thesebridges may be dated between the thirteenth and sixteenth centuries, and, considering theextreme economy of their construction, it is surprising that they have lasted so long.
Arches of great span, consisting of the segment of a circle, whose height is nearly equalto the diameter, could hardly be erected in towns, where they would encumber the neigh-bouring houses ; in such cases a greater number of arches and less span is far preferable ;the most ancient of the kind now remaining is the bridge of Notre Dame at Baris, builtin 1507. Until this date the city had only wooden bridges, which were frequently carriedaway by the ice and inundations, which in 1196 occurred to them all. In 1280, two