26 THE POPULAR SCIENCE MONTHLY. 



AQUEDUCTS. 



THE remains of the lofty arcades upon which the aqueducts of 

 ancient Rome were carried to the city have been justly classed 

 among the finest and most picturesque ruins of the Roman Empire. 

 Stretching across the plain eastward of the city, and towering high 

 above the landscape, they are the first objects to fix the gaze and 

 command the admiration of the stranger approaching the home of 

 the Cajsars, and to fill his mind with visions of the strength and grand- 

 eur of the nation which mastered the world two thousand years ago. 

 But these ruins speak not only of the mechanical skill and physi- 

 cal greatness of that vanished people, but also of their refinement 

 and their acquaintance with the deeply-hidden laws of hygiene ; for 

 they well knew what has become known to us only after a lapse of 

 twenty centuries, after the measurement of the heavens, and the dis- 

 covery of the steam-engine, that for every large city an abundant 

 supply of pure, fresh water is indispensable to the preservation of 

 health. At the zenith of her grandeur, Rome had eleven distinct 

 aqueducts, w^hose aggregate discharge was equivalent to a stream 

 twenty feet wide by six deep, with a fall six times as rapid as that 

 of the river Thames, The daily supply was in the proportion of 

 332 gallons to each inhabitant, and it was distributed to the palaces 

 and humbler dwellings in every part of the city, as well as to innumer- 

 able fountains, many public wells and large reservoirs, to the numer- 

 ous baths, and to several artificial lakes, where the emperors held 

 their naumachice, or sham naval battles. These eleven constituted 

 the most extensive and perfect system of aqueducts that has been pos- 

 sessed by any city even up to the present time. Their combined 

 length was over 300 miles, 50 of which were above-ground either upon 

 low substructures or more imposing arcades. The loftiest arcade was 

 that belonging to the Aqua Claudia and the Anio Novus ; it was in 

 one place 109 feet high.* In respect to height of arcades, however, the 

 aqueducts of Rome were less remarkable than several built by the 

 emperors, about the same time, for certain provincial cities of the em- 

 pire, and others of more recent times. Thus the Emperor Agrippa 

 built an aqueduct for the city of Nemausus (Nimes) in France, and 

 carried it across the river Gard upon an arcade 180 feet high, and 

 about 900 feet long. This splendid structure, still perfect, is now 

 called the Pont du Gard, and is an object of attraction and aston- 

 ishment to modern travelers. It consists of a triple row of arches, 

 which in the two lower tiers are of wide span, and in the upper one 

 narrow. This arcade "has no rival for lightness and boldness of 



' The Roman foot was 11.6496 English inches ; 5 feet made one passus ; 1,000 passus 

 one mile, or 1,618 English yards. 



