158 TRANSACTIONS OF THE [mAT 23, 



built by Mr. Rennie, and is composed of nine elliptical arches, 

 each having a span of 120 feet. Its length is 1,380 feet. 



The first cast-iron arched bridge was built across the river 

 Severn at Golebrookdale, England, by Mr. Darby, in 1779. 

 Some years later Thomas Paine made preparations for erecting 

 a similar bridge at the same place, according to plans which he 

 had prepared in this country, and caused his bridge to be erected 

 for exhibition in a meadow near Golebrookdale, but having no 

 funds to erect the bridge across the Severn, it was removed from 

 the meadow and parts of it used for a bridge over the Wear in 

 1793. 



Vauxhall and Southwark bridges over the Thames were of 

 cast iron. The latter, built by Mr. Eennie, was composed of 

 three cast-iron circular arches, the central arch having a span of 

 250 feet. Ten years were occupied in its construction. 



Iron suspension bridges were constructed in Europe as early 

 as 1615, but this class of bridges had already existed in Asia, 

 Africa, and America at much older dates. The Spaniards found 

 a suspension bridge in Peru, built by the fifth Inca, the cables, 

 four in number, being composed of vegetable fibre, and the floor 

 made of rushes. This bridge was systematically repaired every 

 six months and remained standing and in use up to a very recent 

 date. 



Telford constructed a suspension bridge across the Menai 

 Straits, of 560 feet span, Avhich at the time was regarded as a 

 great achievement. All suspension bridges of the Old World are, 

 however, insignificant in comparison with the great bridge, 

 beautiful in design and appearance, as well as magnificent in its 

 proportions, erected by Mr. Roebling across the East Eiver be- 

 tween New York and Brooklyn. 



In timber bridges, America has taken the lead of all other 

 countries, the only structure in Europe comparable with the 

 great timber bridges built in this country during the early part 

 of this century being the Schaflhausen and Wittengen Bridges 

 across the Rhine, built by Ulric Grubenmann. A stone bridge 

 that had spanned the Rhine at Schaffhausen having fallen, a 

 model of a wooden bridge to supply its place was presented by 

 Grubenmann, and accepted. This extraordinary work was com- 



