484 



BRIDGE. 



Ejridge. arc 103 French, or lld.4 English feet span, and rise 

 32 feet 6 inches French, or 34.9 English; thebieadth, 

 including the parapets, is 33 French, or 35.3 English 

 feet. It was also designed by M. Hupeau ; begun 

 under his direction in 1757 ; and during that and 

 1758, raised to the level of the sixth course of arch 

 stones : the work was then suspended on account of 

 a war. It was recommenced in 1763 under the di- 

 rection of Perronet, (M. Hupeau having died in that 

 interval,) and was opened in 176,5. 



One of the finest of the French bridges, and the 

 greatest work of Perronet, is that upon the Seine at 

 Bridge at Neuilly. It consists of five arches, each 120 French, 

 or 128.2 English feet span, and SO French, or 32 

 English feet rise ; the breadth, including the para- 

 pets, is 45 French, or 48 English feet. It was begun 

 in April 1768, and opened in October 1773; the 

 masonry was completed in 1774 ; the roads, and other 

 operations connected with this bridge, were finished in 

 J780. A great peculiarity in this bridge, well de- 

 serving the attention of engineers employed in similar 

 works, is, that the soffits of the arches are shaped to 

 suit the contracted vein of water, as formed in the 

 entrance and exit of pipes. This is accomplished, by 

 making the general form of the body of the arch el- 

 liptical, with a rise of 30 French, or 32 English feet, 

 or of the span ; but making the headers follow the 

 segment of a circle, the versed ^ine of which is only 

 13f French, or 14.5 English feet, or about ^ of the 

 span. This, besides affording facility for the passage 

 of flood waters, gives a great appearance of lightness 

 to the whole fabric. The effect will be seen in the 

 elevation, onehalf of whichis given in PlateLXXXIV. 

 In the bridges at Orleans, Mantes, and Neuilly, 

 we find the rise of the arches to be between -J- and 

 of the span ; but rendered confident by success, and 

 desirous of giving a variety to his works, Perronet, 

 in the bridge over the Oise, at St Maxence, consist- 

 ing of three arches, each 72 French, or 76.10 Eng- 

 lish feet span, makes the rise only 6 French, or 6.5 

 English feet, or T ' T part of the span ; also, instead of 

 making the piers each a solid, right lined on the sides, 

 he divides each pier into two distinct parts, with an 

 open space between them, and composes each part of 

 two columns united by a piece of plain wall. The 

 deviation from former works of a similar kind is here 

 certainly sufficiently distinct ; but the propriety of this 

 measure will be discussed under the head of Practice. 

 This bridge was begun in 1774 ; the operations were 

 suspended in 1775 ; they were recommenced in 1780 ; 

 and the centers were struck in 1785. See Plate 



LXXXV. 



The bridge built upon one of the arms of the Loire 

 at Saumur, from a design of M. do Voglio, and exe- 

 cuted chiefly under the inspection of L. A. de Ces- 

 sart, may also be classed amongst the first of the 

 French bridges. It consists of 12 elliptical arches, 

 each 60 feet span, and 21 of rise : the piers are 12 feet 

 thick, and the breadth of the bridge, including the 

 parapets, is 42 French, or 44.9 English feet. It was 

 begun in 1756, and finished in 1770. 



^he progress of bridge-building in England seems 

 to have kepi pace witu the same art on the conti- 

 nent. The very singular bridge at Croyland in Lin- 

 colnshire, is said to have been built in 860. This 



PLATE 

 1.XXX1V. 



Bridge at 

 Maxence. 



PIAT 

 l.XXXV. 



Bridge at 

 Saumur. 



j 



Bridges in 

 Kngland. 



date is likely to be correct ; for Croyland Abbey was 

 founded in 716, and the Abbey of Rumsey, in Hun- 

 tingdonshire, in 974. (Bentham's Essays.) This 

 bridge has three distinct approaches, formed by three 

 segments of a circle, which meeting in the middle, 

 compose pointed arches, their bases or abutments 

 standing upon the points of an equilateral triangle. 



It is worthy of remark, that the bridge of Avig- 

 non was begun under the direction of Saint Benezet in 

 1 176, and that of London begun to be built of stone un- 

 der the direction of Peter of Colchester, a priest, in 

 the same year (1176.) The French " Brothers of 

 the Bridge" accomplished their magnificent and use- 

 ful work in 12 years, the labours of the English 

 priest occupied 33 years ; but this may be accounted 

 for, by considering the interruptions which must be 

 experienced in a river, where the tide rises twice every 

 day from 13 to 18 feet. We may further remark, 

 that as the constructions of the bridges of St Esprit 

 and Lyons immediately succeeded to that of Avig- 

 non, so the bridge at Newcastle-upon-Tyne was built 

 of stone in 1281, and that over the Medway at Ro- 

 chester, consisting of 11 arches, much about the same 

 time. 



In London bridge there are now 19 arches, and it 

 is 45 feet in breadth. For many ages there were 

 houses along each side of it ; but these were remo- 

 ved, the middle pier was taken away, and the space, 

 including the two adjacent arches, converted into one 

 arch of 72 feet span, in 1758. The remaining old 

 arches are very narrow, and the piers enormously 

 large, being from 15 to 25 feet in thickness above the 

 sterlings. The passage over the bridge is very com- 

 modious, but in other respects it is very inferior to the 

 before mentioned old French bridges. See Plate 

 LXXXIII. 



Many other old English bridges might be descri- 

 bed, which, in conformity with the turbulence of the 

 times, were generally fortified with gateways. It 

 would be curious to trace their history, and delineate 

 their features ; but as the limits of our present article 

 will not admit of this, we shall pass on to those of 

 modern times, from which our readers will derive 

 more useful information. 



In 1636, the English Palladio (Inigo Jones) gave 

 a design for a bridge, which was erected at Llanwst 

 in Denbighshire. It consists of 3 arches, segments 

 of circles ; the middle one is 58 feet span, and rises 

 17 feet, the piers are 10 feet thick, and the breadth of 

 the soffit of the middle arch is 14 feet. The arch, 

 stones of the largest arch being only 18 inches deep, 

 the covering over them being little, and the ap- 

 proaches very steep, the bridge has a very light ap- 

 pearance. 



The bridge over the river Thames at Westminster, We 

 being not only the greatest work of the kind in Eng- ste 

 laud, but having, in what regards laying foundations 

 in deep water, and constructing centers for large 

 arches upon navigable rivers, formed a new school for 

 bridge-building in this island, we shall give a detailed 

 account of it. 



From reports made by Mr Labalye, (1751) it ap- 

 pears, that from 1734 to 1738, the time was employ- 

 ed in obtaining acts of parliament, and determining 

 the precise situation and plan of this great work. 



BH 





I.X 



