Chap. IV.

ROMAN.

185

The Aqueduct at Constantinople was erected by Hadrian before the foundation of the newcity by Constantine; afterwards it bore the name of Valens, as well as that of Theodosius .It consists of two tiers of arches, built with alternate layers of stone and brick, in a similarmanner to the walls of the city.

The Aqueduct at Lisbon , where it crosses the valley of the Aliantara, about a milefrom the city, consists of thirty-five arches, one of which, measured to the soffite, is 231feet, and the entire height of the structure at this place is said to be 263 feet. Thespan of the principal arch is 108 feet, and the thickness 23 feet 8 inches. A vaulted cor-ridor, 9g feet high, and 5 feet in breadth, passes over three arches, on each side ofwhich corridor is a semicircular channel for the water to flow, 13 inches in diameter.

Aqueducts were built throughout the eastern as well as western provinces, and Pliny , inone of his letters to the emperor, says, that the inhabitants of the city of Nicomedia hadexpended 3,000,229 sesterces (about 24,000£) in building an aqueduct, which did notanswer the purpose, and, consequently, was abandoned to ruin. A second attempt inanother situation was made, at an expense of more than 2,000,000 of sesterces, which alsofailed. Pliny himself then examined some springs from whence the water might be con-veyed over arches, as was attempted in the first design, and in such a manner, that thewhole city might be supplied; he recommends the use of brick for turning the new arches,as it was cheaper and easier to carry up a work in that material; he also requested theemperor to send some engineer skilled in the management of waterworks to undertake theconstruction. Trajan , in his reply, observes, that every province is provided with men ofskill and ingenuity, and that Greece supplied most of the architects that came to Rome .

Canals in Italy and the Roman Empire. —Canals in the early history of Italy seem to havebeen formed, either for the transport of an army, or for draining a morass or marsh : thatcut through the Pontine marshes, 162 years before Christ, was for the purpose of renderingthe country more salubrious. Before this period the Etruscans had cut many canals, andthey executed the Fossa Phillistina and the Fossa Carbonania, which drew their watersfrom the Po; indeed the country watered by this river has always been the scenewhere the great undertakings in Italy connected with inland navigation have been car-ried out.

The consul Caius Marius, about 51 years before Christ, was sent into Provence at thehead of an army, to defend it against the incursions of the northern barbariaps, and establishedhimself in the neighbourhood of Arles , on a spot where he could with facility receive hissupplies by means of the Rhone from the sea. The river was difficult of entry, in conse-quence of the shoals thrown up at the mouth, and this consul undertook to dig a canal, andconduct the waters of the Rhone from the left bank, opposite his camp, into a haven calledFos, where the vessels lay. This canal, called the Fossa Mariana , supplied him with allthat was required, and may be traced to Marseilles , where the inhabitants benefited con-siderably from it.

j The difference of level between two seas was not so readily overcome by the Greeks,when they attempted to cut through the Isthmus of Corinth, in the time of DemetriusPoliorcetes , at which period it was the practice to transport light vessels across the isthmus,a distance of five miles, on machines constructed for the purpose, which was continued inthe wars of the Turks and Venetians. Julius Caisar, Caligula, and Nero , renewed the at-tempt to unite the Ionian Sea with the Archipelago , but were frustrated, by finding that thewater in the Corinthian Gulf was much higher than at Cenchrese, and, consequently, theIsland Egina would have been flooded, and the canal rendered unserviceable.

It was the important part of the business of the Roman proconsuls in the distant parts ofthe empire to lay before the emperors the best method of changing the courses of rivers, forthe purpose of more readily communicating from the sea to the centre of the provinces ;of this we have many examples. Lucius Verus , general of the Roman army in Gaul, under-took to unite the Saone and the Moselle by a canal, and to open a communication to theMediterranean and German Ocean, by means of the Rhone, the Saone, the Moselle , andthe Rhine ; his death prevented the execution of this project.

The object of these works was to facilitate, in the first instance, the expediting the pro-consular legions, which every year were sent from Rome to the remote provinces. Thegreat Fossa Drusiana, supplied by the Rhine, was executed by Drusus Germanicus , to in-crease the river Yssel , by which he transported his army into the north.

Corbulon afterwards, either to establish a more convenient passage for his troops into theBritish Isles, or to drain the stagnant waters of the Rhine , which overflowed extensive tracts,made so large a cut in that river at Batavodurum, that he diverted almost all the waterfrom it, and led it into his canal, which acquired the name of Fossa Corbulonis, nowcalled the Leek, the waters of which, under the name of the Meuse, run into the NorthernSea .

Emilius Scaurus united the waters of the Po, near Placentia, to drain the marshes, andthere is no river in Italy that was not made by the Romans useful for the passage oftroops or provisions. The river Marrechia, near Rimini, was ennobled by Augustus Oesar