Page:Popular Science Monthly Volume 11.djvu/38

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28
THE POPULAR SCIENCE MONTHLY.

them on arcades, and therefore differed essentially from the aqueducts that we have been considering. And, besides, the statements as to their length should not be received without caution, for, at the time that the Spaniards first visited the country, their belief in the marvelous had been very greatly enlarged by the discovery of a new world.

PSM V11 D038 The aqueducts.jpg

Fig. 1.—The Aqueducts. The Crossing in the Campagna near the Piscinæ and Roma Vecchia.

The longest aqueduct proper is that now building to convey the waters of the Somme-Soude, Soudon, and Dhuis, to Paris. It will be about 110 English miles long. The aqueduct of Roquefavour, already referred to, is 60 miles long, the longest in actual use.

The Romans appear to have got their knowledge of aqueduct building, like most of their other knowledge, from the Greeks; for, while their first aqueduct, the Aqua Appia, was not constructed until 441 years after the building of the city, or 312 b. c, the Greeks had built aqueducts at Megara and Samos as early as 625 b. c, and at Athens in 560 b. c. But there is this difference, that the Greeks did not use arcades, which, however, were not rendered necessary by the topography of the country. At Samos, a tunnel four-fifths of a mile long, eight feet high and eight wide, was cut through a hill between the city and the water-source. A channel three feet wide was built within the tunnel, and an opening of the same width made to the surface from end to end, so that the fresh air came in contact with the water, which flowed into a conduit of masonry at the lower end, and thence directly to the baths, fountains, etc., of the city. This work