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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 marvel- 

 ous had been very greatly enlarged by the discovery of a new world. 



Fia. 1. The AqtrEDUCTS. The Crossing in the Canipagna near the Piscina; and Koma 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 A2)pia, 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 sur- 

 face 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 



