CHAP. XIII. THE DEAN BRIDGE, EDINBURGH. 465 



archstones, being in the form of a segment, have the 

 same chord, with only 13 feet rise. " This complex 

 form," says Mr. Telford, " converts each side of the vault 

 of the arch into the shape of the entrance of a pipe, to 

 suit the contracted passage of a fluid, thus lessening the 

 flat surface opposed to the current of the river whenever 

 the tide or upland flood rises above the springing of the 

 middle of the ellipse, that being at four feet above low 

 water ; whereas the flood of 1770 rose twenty feet above 

 low water of an ordinary spring-tide, which, when there 

 is no upland flood, rises only eight or nine feet." l The 

 bridge was finished and opened in 1828. 



The last structures erected after our engineer's designs 

 were at Edinburgh and Glasgow ; his Dean Bridge at 

 the former place, and his Jamaica Street Bridge at the 

 latter, being regarded as among his most successful 

 works. Since his employment as a journeyman mason 

 at the building of the houses in Princes Street,. Edin- 

 burgh, the New Town had spread in all directions. At 

 each visit to it on his way to or from the Caledonian 

 ("anal or the northern harbours, he had been no less sur- 

 prised than delighted at the architectural improvements 

 which he found going forward. A new quarter had 

 risen up during his lifetime, and had extended northward 

 and westward in long lines of magnificent buildings of 

 freestone, until in 1829 its further progress was checked 

 by the deep ravine running along the back of the New 

 Town, in the bottom of which runs the little Water 

 of Leith. It was determined to throw a stone bridge 

 across this stream, and Telford was called upon to supply 

 the design. The point of crossing the valley was imme- 

 diately behind Moray Place, which stands almost upon 

 its verge, the sides being bold, rocky, and finely wooded. 

 The situation was well adapted for a picturesque structure, 

 such as Telford was well able to supply. The depth of 



1 <Telford'sLife,'p. 261. 

 VOL. II. 2 H 



