BRIDGE. 





This modi- of constructing centres, applicable to 

 llafl iron archee, being M rigirud id 



perfectly simple, anil the effects of all its operations 

 being more capable of correct dcmonstrati'm tli.m 

 those ot tlu 1 forme;- moil 1 of supporting from below, 

 we were glad of being enabled, \vlnle this article 

 was in the piv:;:i, to communicate the outlines of the 

 scheme, as given by the engineer in hi:; report to the 

 Lords of the treasury. If this should be successfully 

 practised on so large a scale at the Meuni, all difli- 

 cultics with regard to carrying bridges over inacces- 

 sible ravines or turbulent streams, will, in future, be 

 done away, and a nc\v ;cra formed in bridge building. 

 We have only given a Plate of the centering, be- 

 cause the construction of the iron work is precisely 

 the same in principle (though on a larger scale) as 

 what has been adopted by the same engineer in Bo- 

 re c. nar bridge. See Plate C. 



We have now given our readers a distinct view of 

 the progress of the practice of constructing bridges 

 with cast iron, as far as it has hitherto been carried. 

 We are well convinced that much more will still be 

 accomplished ; and when we come under the article 

 IKON', to treat generally of its qualities and different 

 modes of application, some light will be thrown upon 

 the subject, which we expect will tend, still fur- 

 ther to enhance its importance in the great practical 

 purposes of life. 



Although it is trusted the reader will, in this arti- 

 cle, have found bridge building as fully discussed as 

 he could expect in a work of this nature, yet if dis- 

 posed to prosecute the subject more at length, he will 

 be enabled to do so by consulting the following able 

 authors, who have written on the subject either gene- 

 rally, or in describing particular works. 



It is rather surprising, that although the Romans 

 had, before the time of Vitruvius, introduced the use 

 of the arch, not only in bridges and aqueducts, but in 

 theatres and temples, yet he has not been led to dis- 

 cuss, or even particularly to notice this principal fea- 

 ture in Roman architecture. 



a ) Vi Leoni Baptisti Albert! first wrote upon bridges in 



1481. Palladio followed about a century afterwards. 

 Serlio and Scammoz/,i also treated the subject, and 

 the latter gives useful rules respecting foundations. 

 See also Ferrari on Arches, in the Act. Sienn. vi. 143. 

 rancc. Blondel has described the bridge which h * built in 

 1665, in the tideway upon the Charante at Xaintes. 

 Gautier, in 1714, published a treatise expressly upon 



on. 



lystcmatii ;od, r.nd contain- T- 



>K|> useful ; ,ct, in ' ' V -' 



I7(is, published an elaborate work, containing very 

 minute *! I. ill, nt the [irngresi in building so. TIC of the I" Ffjnc*. 

 priii' ,..a- 



tion respecting mat< 1. it ions, centres, arches, 



scaffolding, and in.iehin-ry. Reg. --H an ac- 



count lit" a bridge of 1:{ large arches, built by Irm on 

 the Allicr at Moulins. Cessart, in his Travata Hi/. 

 ./(>, gives an account of the bridge of Saum'ur 

 of 1'J large arches, up"!, the Loire. Belidor, in the 4th 

 vol. of \\ii.liclttl. llt/draul., treatsof bridges. Parent, 

 De la Hire, and BosMit, treat the subject scientifically. 

 See also Abeille Mem. Acini, fur. i. l.VJ. Scbartien, 

 Do. i. 16H. De la Hire, !). \K>'2, 1712. Senes, Dn. 

 171!), :i:J. Couplet, Dn. 1729, 1730. Chardon, Do. 

 17:il. Bougucr, Do. 17:54-. Bofaot, 2)0, 1774, 584 1 

 1776', 587. Coulomb, Mrm. dot Sarnn.t Elrangers, 

 177:i, .'H:J. Giral, Stir Irs ciiiu-lnn-tinns ilex punts, 

 4to. Trembley in Rozier's Observations, torn, 

 xxxiii. p. 132. Montpetit in Rozier's Obsfn: torn, 

 xxxii. p. 430. 



TEpinus wrote on the abutments of arches in the j n i>r u .,; a 

 Mem. Acad. Jicrl. 1755, p. 386. ; and Euler.on the ir.d Ru-i... 

 method of judging of the strength of a bridge from a 

 model in the Nov. Comment. Pctrop. torn. xx. p. 271 . 

 See also Lorgna on the Curve of an Arch, in the 

 Ada Pt'trop. III. ii. ISO. 



Labelye published a short report respecting West- In England, 

 minster bridge. Goldman and Hawksmoor also 

 treated on the subject of bridges. Semple published 

 a detailed account of the mode of conducting the 

 building of Essex bridge in Dublin. He also treats 

 of building in water. Dr Hook, Emerson, and Mul- 

 ler, have discussed the principles of arches scientifical- 

 ly. Dr Hutton, in a separate treatise, and also in his 

 Dictionary, treats of the principles of bridges ; and his 

 valuable works contain many useful remarks and di- 

 rections respecting those edifices. The late Mr At- 

 wood published an essay upon the principles of arches, 

 in two parts, in which much science and originality 

 of mind are displayed. See likewise Robinson in the 

 Phil. Trans. lo'.S4, vol. xiv. p. 583. Robertson on 

 the fall of water under britlacs, in the Phil. Trans. 

 1758, p.' 492. ; and Dr Thomas Young's Natural 

 Philosophy, vol. ii. p. 175, &c. (-/) 



H3- For this valuable and original article on the theory and 

 practice of Bridge-building, which is the only complete trea- 

 tise on the subject that has yet been published, the Kditnr is 

 indebted to THOM>>. TF.LKIIRD. K. R.S. K., civil engineer, and 

 to ALEXANDER NIMHO, F. R. S. E. 



B R I 



gend. BRIDGEND, n town of South Wales, in the 

 county of Glamorgan, situated on both sides of the 

 river Ogmorc, uver which there isa good stone bridge. 

 The town, which consists of a street on each side of 

 the river, 13 tolerably well built, and is divided into 

 three parts, cahed N'.-w Castle, Old Castle, and Bridg- 

 cnd, the two first deriving their names from two caa- 

 ties, the remains of which arc still visible. The town- 

 hall ii ;i neat building, the market-place is very com- 



VOL. IV. PART II. 



B R I 



modious, and the parish church is well built, and Bridgend. 



commands a fine prospect. The soil of the adjacent w ' 



country is fertile, and in a state of good cultivation ; 

 and great quantities of salmon, sewin, trout, nnd flat 

 fish, are caught in the river. The chief trades car- 

 ried on in the town are tanning and tallow chandlery, 

 and a large woollen manufactory has been establish- 

 ed by the agricultural society of the county. Wool- 

 len cloths and blankets are manufactured by means of 

 Sz 



