AQU 



served the longitude and latitude of the 

 stars in A pus, which Hevelius in his pro- 

 dromus reduced with some alteration to 

 the year 1700. P. Noel has also given the 

 places of these stars, with their right as- 

 censions and declinations for the year 

 1687, but his observations differ widely 

 from those of Dr. Halley. Hevelius has 

 represented the figure of Apus, and its 

 stars, in his Firmamentum Sobiescianum, 

 according to Halley's account ; Noel has 

 done the like, according to his own ac- 

 count. Wolfius, with what justice we 

 will not pretend to say, gives the prefer- 

 ence to this last. 



AQUA fortis. Another name for NI- 

 TRIC ACID, which see. This name is ap- 

 plied to denote the common nitric acid 

 used by workmen, which often contains a 

 slight portion of muriatic acid. See CHE- 

 MISTRY. 



AQ.UA res-la, another name for the nitro 

 muriatic acid. See MURIATIC ACID. 



AQUJEDUCT, a conduit of -water, in 

 architecture and hydraulics, is a construc- 

 tion of stone or timber, built on an un- 

 even ground, to preserve the level of wa- 

 ter, and convey it, by a canal, from one 

 place to another. Some of these aque- 

 ducts are visible, and others subterrane- 

 ous. Those of the former sort are con- 

 structed at a great height, across vallies 

 and marshes, and supported by piers and 

 ranges of arches. The latter are formed 

 by piercing the mountains, and construct- 

 ing them below the surface of the earth. 

 They are built of stone, brick, &c. and 

 covered above with vaulted roofs or flat 

 stones, serving to shelter the water from 

 the sun and rain. Of these aqueducts 

 some are double, and others triple ; that 

 is, supported on two or three ranges of 

 arches. Of the latter kind are the Pout- 

 'clu-garcl, in Languedoc, supposed to have 

 been built by the Romans to carry water 

 to the city of Nismes; that of Constanti- 

 nople, and that which, according to Pro- 

 copius, was constructed by Cosroes, King 

 of Persia, near Petra, in Mingrelia, and 

 which had three conduits in the same di- 

 rection, each elevated above the other. 

 Some of these aqueducts were paved, 

 and others conveyed the water through a 

 natural channel of clay : and it was fre- 

 quently conducted by pipes of lead into 

 reservoirs of the same metal, or into 

 troughs of hewn stone. Aquxducts of 

 every kind were reckoned among the 

 wonders of ancient Rome : their great 

 number, and the immense expense of 

 bringing water 30, 40, or 60, and even 100 

 miles, either upon continued arches, or 

 by means of other works, when it was 



AQU 



necessary to penetrate mountains and 

 rocks, may well astonish us. If we con- 

 sider the incredible quantity of water 

 broyght to Rome for the uses of the pub- 

 lic, for fountains, baths, fish-ponds, pri- 

 vate houses, gardens, and country-seats ; 

 if we represent to ourselves the arches 

 constructed at a great expense, and car- 

 ried on through a long distance, moun- 

 tains levelled, rocks cut through, and 

 vallies filled up, it must be acknowledged 

 that there is nothing in the whole world 

 more wonderful. For 440 years, the Ro- 

 mans contented themselves with the wa- 

 ters of the Tiber, and of the wells and 

 fountains in the city and its neighbour- 

 hood. But when the number of houses 

 and inhabitants was considerably aug- 

 mented, they were obliged to bring water 

 from remote places by means of aque- 

 ducts. Even Tiberius, Claudius, Caligula, 

 and Caraccalla, though in other respects 

 not of the best character, took "care of the 

 city in this useful article. There are still 

 to be seen in the country about Rome 

 wonderful remains of the ancient aquae- 

 ducts, some elevated above the ground by 

 arches continued and raised one above 

 the other, and others subterraneous, pass- 

 ing through rocks ; such is that seen at 

 Vicovaro, beyond Tivoli, in which a canal 

 pierces a rock to the extent of more than 

 a mile, and about five feet deep and four 

 broad. At certain distances vents were 

 provided, so that the water which was 

 accidentally obstructed in its passage, 

 might be discharged till its ordinary pas- 

 sage was cleared ; and in the canal of the 

 aqueduct itself there were cavities, into 

 which the water was precipitated, and 

 where it remained till its mud was depo- 

 sited ; and ponds, in which it might purify 

 itself. In the construction of these aquae- 

 ducts, there was a considerable variety : 

 that called the Aqua Martia, had an arch 

 of sixteen feet in diameter; it was con- 

 structed of three kinds of stone, and was 

 formed with two canals, one above the 

 other. The most elevated was supplied 

 by the waters of the Tiverone and Anio- 

 novus ; the lowest by the Claudian water. 

 The entire edifice was 70 Romanfeet high. 

 The arch of the aqueduct, which brought 

 to Rome the Claudian water, w r as con- 

 structed of beautiful hewn stone. This is 

 represented by Pliny as the most beauti- 

 ful of all that had been built for the use ot" 

 Rome. It conveyed the water through a 

 vaulted canal, through the distance of 40 

 miles, and was so high, that it sup, 

 the hills of the city. According to him, and 

 the computation of Budseus, the charge of 

 this work amounted to 1,385,500 crowns. 



