BRIDGE. 



tiaj given fcvfral jiidicioas precfpls, which, with little altcra- 

 tii'ii, wcro sfurwards Lidilownby Paliadio, Scrlio, aiiJ Sca- 

 n'o/.7,i. Tlic bcft of thcfe ruks air alfo given by Goldman 

 i iJ Baukhiirft, and by Hawiitfinoor in his hiiloiy of Lon- 

 Ju'i biiilge. M. Gamier has a cimliJerable volume upon 

 bridg.s ancient anil moiltrn. M. Bclidor has treated on this 

 lubjctt, in his "Arc-hit. HydraulJque ;" and M. Paiint, in 

 his " i'lrais and Rcchcrchcs Mathcniat." vol. iii. Dc la Hire, 

 too, has touched upon the fubjeft, in his " TraJte de Me- 

 cliaiiique ;" Perronet alfo has given the refu't of his experience 

 in a ma^i'.itieent work, which has actjuircd great credit in 

 Kranet ; Boli'nt has given an excellent Ireatife iu tht " Me- 

 nioiresdci'Acadeniic ;" and Regemoites, in tlie year 1771, 

 pnbliried an account of a hridjje cor.ftrui^ted by h'm on 

 the river il'Allier at Monhns. This bridi^e confills of 

 thirteen archss, G4 feet fpan each, and 24 tcet hij^h. ; femi- 

 ellipfls. — The top of the bridge is level. Mr. Rion pub- 

 iiflitd, in i;6a, " jjliort Principles for the Architedure of 

 Stone Bridg.s ;" and Mr. Semple has given fome e.^cel- 

 lert practiciil remarks in his " Triatifc on Building in 

 Water," piiblilhed in 1776. Other writers on the fubje£l 

 of arches and bridge* arcMuller, I^abelye, Atwood, Emerlon, 

 and Dr. Hntton in his " Principles of Bridges." 



Hijhry of BiiJ-^ii. — We have no records which will en- 

 able lis to trace the art of bridge -building from its firil rude 

 and imperfect Uate, through its various Itagcs of improve- 

 ment, to its prefont maturity and grandeur. It cannot, liow- 

 ever, be doubted, that men in the carliefi. ages would do 

 ai our villagers do at prefent: the accidents of nature would 

 prefent a model; a fallen tree, or a wave- worn cavern would 

 frequently form a natural bridge, and the fn 11 bridges were 

 compofed of lintels of (lone or wood, either of length fuf- 

 ficiciit to llrctch from bank to bank, or when this was im- 

 praflicable, fiipported by piers or polls placed in the bed of 

 the river. There are dill confidcrable ilruiftures of this kind 

 in China, and many of them in this country on a rural 

 fcale. This method, however, would in many iituations be 

 oppofiJ by infupcrable difficulties: the frequent piers re- 

 quired for the fupport of lintels would, by contrafting the 

 xvater-way, increafe a ftrong current to a dangerous, rapid 

 torrent, impeding navigation, and undermining and dcflroying 

 the piers themfelvcs. It would, therefore, be found neceliary, 

 in conllruAirg bridges over rapid rivers, to have thefupports 

 a; few and dillant, and the openings as wide as poiTible ; this 

 could only be effeiled by the ufe ot arches of llone and truffes 

 of wood ; accordingly thefe inventions mull have been com- 

 pleted before bridges of importance had become common. 



The origin of a-ches is fo obfcure, and our lights fo few, 

 that it i>) perhaps, impoHible at this time to determine to 

 whom this invention is due. The Egyptians, fkilful as they 

 were in archittflure, do not appear to have poirciFcd arches; 

 their temples were roofed •.vith /labs laid horizontally from 

 colum!i to column, and the openings covered with malTy 

 lintels, or, as in the pafTagcs within the great pyramid, with 

 courfes of (lones projcfllng over one another like inverted 

 Heps, till they met at top. Some of their tombs, however, 

 which arc excavated in the fclid rock, have the appearance of 

 vaults, as the ceilings are hollowed out in a circular form, 

 and there arc inftanccs of hemifpherical niches. Similar forms 

 alfo prevail in the Hindoo excavations at Ellore, in the Dec- 

 can, and in the idanu of Salfette. See Mr. Daniel's Plates of 

 Indian Antiquities and Hindoo Excavations. This praftice, 

 though it has the form, has not the principle of an arch ; for it is 

 evident that a fohd lintel gains no llrengtii by being hollowed 

 in the middle, neither is the execution more difficult ; and 

 though both the Hindoos and Egyptians attained this flep, 

 they never, at Itaft, there arc no remains which authorize 



us to fuppofe tliat they ever did make any further progrefs 

 in the difcovery of arches. 



The Chinefe arc acquainted with the ufe of arches, and 

 from the known adherence of this nation to ancient modes, 

 we may attribute a veiy high antiquity to this praftice among 

 thein. Their arclus are of various forms, pointed, femi- 

 circular, femi-elliptical, and horfe-flioe ihaped ; their con- 

 ilruCtion, as dtfciibtd by Mi. Barrow, is curious, " each 

 ttone, from five to ten feet in length, is cut fo as to form a 

 feL'ment of the arch, and, as in iiich cafes there is no kcy- 

 ftoiie, ribs of wood fitted to the convexity of the arch are 

 bolted tlirough the Hones by iion bars, fixed fall into the 

 folid parts of the bridge. Sometimes, however, they are 

 without wood, and the curved ftonc:; are morticed into lonj 

 tranfverfe blocks of (lone." Mr. Barrow proceeds to oh- 

 lln-e, that " there are, however, arches wherein the (lone^s 

 are fmaller, and pointed to a centre as in ours. I have under- 

 (lood from the late captain Pari(h, that no malonry could 

 be fupcrior to that in the great wall, and that all the arched 

 and vaulted work in the old towers was exceedingly well 

 turned." 



However, the moil ancient arches, of whofe creftion w^e 

 have dates, arc thofe in the cloacx of Rome, which were 

 begun by Tarquiuius Prifcus. There are alfo arches in 

 fcvcral Greek theatres, lladia, and gymnafia, among others^ 

 the theatre of Bacchus at Athens, ereftcd, probably, 400 

 years before the Chriftian era. 



The Greeks, it is well known, often neglefled the moft 

 necelfary objedls to lavifli enormous funis on works of mag- 

 nificence, though deditute of any efTential utility. Pericles, 

 fo far from thinking of aquxducis, could licver be prevailed 

 upon even to conllruft a bridge over the little Cephifus. 

 The Romans difcovercd, in this refpeft, a more folid man- 

 ner of thinking ; they were, it is true, much attached to 

 pomp, but they never negledled works of public utility : 

 they never riflved their lives unneceflTarily in crofGng a tor- 

 rent, as the Athenians mull have done previous to the arrival 

 of the emperor Adrian; tor it was Adrian who undertook to 

 form, by a bridge, a fafe communication acrofs the Cephi- 

 fus, between the territories of Attica and Eleufis, on the 

 mod frequented road of Greece. While, therefore, we 

 afcribe to the Greeks the ufe of arches and vaults, properly 

 conftruficd for covering various openings in their buildings, 

 we mull look to the Romans for the application of arches to 

 bridges, and for the chief improvements in thofe ufeful 

 ftructures. 



The condruftion of the Roman bndges is bed defcribed by 

 Bergier: they poiFeffedall the requifites which are met with 

 in a modern bridge ; they confided of /;'/«, or piers, fonike!, 

 or arches, fublkes, or butments, pninmenta, and aggsres ; the 

 roads over in the middle for carriages, on each fide of which 

 were dicurforia, or banquets, fomewhat liigher than the relt 

 of the road for foot palfengers, and feparated from it by a 

 fpoiule, or railing, and fometimes even covered over to (helter 

 paflengcrs from the rain, as in the Pons .^lius. Among the 

 Romans, the building and repairing of bridges was fird com- 

 mitted to the prieds, thence -namti, ponufcss , then to the cen- 

 fors and curators of the roads, and laltly, the emperors took. 

 the care of the bridges into their own hands. 



The ancient bridges of Rome were eigh* in number. The 

 bridge of Fcihrichu, which joins the ifland of the Tyber to 

 the city ; it is now called Panic Quntro Cap], from the four 

 heads o: Janus, which are placed upon it. The bridge of 

 Ceflius, now called of Sun Barihvlomeo, which frcm the 

 other fide of the iflaud palTcs to Trans-Tevcre. The firft 

 bridge built at Rome, which was of wood, and thence called 

 Puns SiiiUciiis, was afterwards rebuilt of done by .^milius 



Lepidui ; 



