B R 1 D G F. 



P^rtu^J. in the year i ; 15, and nniilicd ilie Ctli of Ai.gud The width of the different Arches are as under : 



t7,-j.^ 'iv arch\tcft, under whofe iiifpcClion it was begun 

 aid fini.'Tied, was the brigadier Miiifel de Maya. 'l"he 

 ftrram! whiih p.ifs through this diid, for theufeofihe 

 i .habinnts of the eity of L\(bi>ii and vUla^ei adjacent,^ have 

 their cliicf fopply from a fprinfj r.far the Riberia de Caran- 

 que, about three le:ic:Hes and a h.ilf from Liibon, whtie the 

 atjiiTdjft eommtrees; and the water is conveyed from thence 

 throu^jh the hills by fubttrnneoiis patTages, where fome 

 other f:jriiij,"i unite with it, and acrofs m.iny valleys on the 

 lopj of ranges of very ma^nuicent arches, of which that 

 crf>ninj tlie'vale of .\lcantaia is the chitf. l"rom a fnb- 

 trrraiieoiii omrfe the w.ittr is conveyed through the build- 

 jnij on tlie top of tlic arches by nuaiisof two channels, each 

 of^which is nSoiit 1 2 niches deep ; it generally flows about 

 the depth of feven inches, and is an abundant and never tail- 

 ing fiipplv of water to Lifb.in. The interior height of the 

 buil«iin^ i» about i %, feet ; and through tlie centre, betv.een 

 the tlrcanis, is a wide handfoine walk or foot-path, paved 

 with beautiful free-llonc. The building is continued the 

 iime height and width through the whole of the aqvi^Jnft 

 from I.iiSon to the fpring, near the Riberia de Caranque, fo 

 that if by accident any part becomes out of repair, the 

 workmen have eafy acccfs to it. The fubterraneous palTages 

 are iighttd and ' ventilated by frequent op-nings made 

 from til', furface of t!ie earth into liie aquiedud ; and over 

 each of thcfe openings turrets or fqnare towers are ereft- 

 ed, which have windows latticed w.lh iron bars to admit 

 the light and air, and at the fame time to prevent mifchiev- 

 ous perfons from throwing any thing into the building to 

 injure it. 



This pile is lighted and ventilated by 79 windows and 16 

 turrets ; the former are three feet feven inches long by 13 

 inches wide, railed with iron and latticed with bars ; the lat- 

 ter rife 2j feet fix inches above the roof, and arc i6fectfquare ; 

 beneath every fecond turrtt is an arched door-way into the 

 aqusducl on each fide of the building, wherein the water 



flows, and between that building and a parapet wall is a foot 

 path leading from Liibon towards the very pleafant village 

 of Bemfiqne, about four miles from Lifbon, where feveral 

 •jcntlenieii have their cpiintas or countiy-fcats : one in parti- 



eular, the quiiita of Gerard de Vifme efq. an Englifli mer- 

 chant of the firll eminence, mull not pafs unnoticed ; it is a 



ptrfeft palais enchantc, whofe fliady bowers, beautiful 



gardens, fine ponds, purling llreams, and fportive fountains, 



.ire frequently honoured with vifiis by tbe queen and royal 



family. 



The water channel under the grand arch is about 24 feet 



wide and feven feet deep, but, except in very rainy feafons, 



no water pafics through this channel ; the fmall running 



ilrcam conllantly pafiing through the va'e of Alcantara is 



conveyed by a very narrow channel under the pavement 



through the grand arch, and then continues its courfe 



tlirough th.e valley, in a dream between two and three feet 



wide, till it empties ilftlf into the Tagus at Alcantara 



bridge, about the diftaiice of two miles from tlie uqnxdudt. 



The i^pence attending the e.^tecntion of fo magnificent a 



work, and keeping the fame in repair, has been immenfe, 



yet the fmall tax of a fingle rey on every pound of meat, 



raifcs a fund fufficient for the purpofe. There is a chapel 



feen through the eleventh aich, dedicated to Notla Scnhora 



dos Terramotos, our Lady of the Earthquakes ; in com- 

 memoration of that dreadful event the earil-.quake in 175J, 



Vihen the gieatefl part of tlie city of Liibon, with moll of 



her ftately buildings, and magnideeiit temples, were levelled 



with the ground. 



The height of the grand arch is 227 feet, and the total 

 length of the piers and arche? 2464 feet. 



.Several of the bridges in France are remarkable for their 

 fi/'.e and boldnefs of conftruft:on, a:nnng which may be 

 mentioned the bridge of Ntuilly, built by M. Perronct, over 

 the Seine, on the alignment ot the great avenue of the 

 Champs Elyfces, in front of the palace of tiie Tuilleries. 

 This bridge, which is level at top, confiflf! of five equal 

 arches of 120 feet French (12S ieet Englifli) in fpan, and 

 30 feet French (32 feet Englilh) rife. The arshes are oval, 

 compofed of i i arcs of circles of different diametL-rs; thus 

 the upper portion of the arch was formed with a circle of 

 160 feet radius, which, by its fettlement during the building, 

 and after the ftriking of the centres, was flattened, till it be- 

 came an arc of a circle of 259 feet radius, differing fo little 

 from a platband, that, as Perronet oblerves, the rife of the 

 curve, in a length of 33 feet, amounted only to 6 inches 9 

 lines. The piers are 14 feet wide, and the breadth of the 

 bridge 48 feet. It was begun in the year 176S, and tei- 

 minated in 1780. 



The bridge on the Seine, at Mantes, confifts of three 

 arches, that in the centre having an opening of 120 feet 

 French (128 Englilh), and the two others loS feet French 

 (n6 Englifh); the piers being 2^ feet 6 inches wide, and 

 the abutments 29 feet. This ilrufture was begun by I^L 

 Hupeau in 1757, and completed by Perronet. 



The bridge of Pont-Sainte-Maixence, on the rrver Oife, 

 on the great road from Paris into Flanders, is alfo a work of 

 Perronet's. This bridge, which is 41 feet wide, has three 

 arches of 77 feet opening each, being a fegment of a circle 

 defcribed with a radius of 1 18 feet. Each pier is fingularly 

 compofed of four cylindrical pillars 9 feet diameter, leaving, 

 therefore, three fpaces or intercolumniations between them, 

 which are arched over, the two txtenial ones clofed with a 

 thin walling, and the middle one left open. 



The bridge over the Loire, at Orleans, is compofed of 

 nine arches, which fpring at j 2 inches above low water ; 

 the middle arch is 106 feet in fpan, with a rife of 30 feet ; 

 the two arches at the extremities beiug 98 feet wide and 26 

 feet high, and the others in proportion ; the four middle piers 

 19 feet, the four others 18 feet, and the abutments 23 

 feet 6 inches thick, making the whole length iicofect; 

 the arches are o\-dl, defcribed from three centres. This bridge 

 was built by M. Hupeau, begun iu 175O; and finiflied in 176^. 



We 



