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HISTORY OF ENGINEERING.

Book I.

when excellent, makes up for this defect, but we frequently find in reticulated work-openings and cracks, which prove it is not calculated to support a heavy and constantweight. At every 4 feet in height, two courses of brick bonded or tied the work together,the bricks being 2 inches in thickness, andtwenty-two inches square. The quoinsof the piers are formed of squared stone,but as these were not properly worked,they have been detached and created con-siderable injury.

Tlie voussoirs of the arches are com-posed of stone, 3 inches in thickness,and an alternate one of brick ; over theextrados is laid a brick, which by its pro-jection forms a label, on this two coursesof tile or brick are bedded, which continuethrough the whole length without pro-jecting. On this course of double tilethe water channel is built.

The valley between Soucieu and Cha-ponost has a depth of nearly 200 feet, andfor nearly 2500 feet the water is con-ducted over an aqueduct composed of fivestories of arches ; that between Chaponost and St. Foi is nearly 300 feet in depth,has eight stories of arches, and the thirdvalley between St. Foi and Fourviereshad three stories of arches.

Some of the leaden pipes found at theextremity, where the water entered thepalace, were from 15 to 20 feet in length,and bore the marks of Tiberius ClaudiusCiesar.

The Aqueduct near Frejus , called Esterelle, where it passes through the country of Gar-gallon, or Agreeable Valley, is a noble structure. Its piers are strengthened by buttresses,the winds of this valley being at times powerful and very destructive: the water is brought

Fig. 211.

ESTEltELLE ARCHE:

Fig. 210.

PIER AT LYONS.

from the river Siagne , running near Mons, 5 miles from Frejus . The country is veryuneven, and full of rocks, which in many parts have been tunnelled. The whole circuitmade by this aqueduct, in consequence of the difficulties presented by the country throughwhich it passes, is more than ten leagues.

All the provinces in the south of France were as well supplied with water as Rome itself, and the various engineering works as admirably performed as in the imperial city.Rich, indeed, is this district with amphitheatres, theatres, temples, baths, and public build-ings, and no one can doubt, who has travelled through this delightful district, of the pro-gress made in the arts and civilisation at a very early period.

Aqueduct at Metz, was another beautiful piece of construction that conducted the springsfound in a valley beyond Gorze, now called les Bouillons , for a distance of 11,373 toises, witha face of about 70 feet. They are first led through a channel 3 feet in breadth, and 6feet deep, formed in a bed of masonry, composed of rough stones and mortar. On the inte-rior the walls are faced with masonry in regular courses, and where the watercourse is laidagainst the side of the hill, an additional wall, varying in thickness from one to two feet, is