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od of the canal of flanged cast-iron plates resting upon 

 walls built on the piers, and const met ed tin- sides of ma- 

 sonry. This work was executed between I71H! and 18111. 

 at a cost of 20.HU8/. The aqueduct-bridge over the valley 

 of the Dee, called the Pont-\-<'ysvltc, is still more remark- 

 able: it consists simply of a trough of cast-iron ;< 

 securely flanged tegttMr, and supported by eighteen piers 

 or pillars of masonry, the elev.ition of which i* a luuulreil 

 and twenty-one feet above low-water. These piers are 

 solid to the height of seventy feet, above which they are 

 hollow, with interior walls. The water-way in the cast- 

 iron trough js eleven feet ten inches wide, of which four 

 feet eight inches is covered by the towing-path, supported 

 upon cast-iron pillars, so as to allow the water free play 

 beneath it. The length, of the aqueduct is about one 

 thousand feet, and Hie height of the canal one hundred 

 and twenty-seven feet above the Dee; and at one end of 

 the aqueduct -bridge is a great embankment, fifteen hun- 

 dred feet Ions:, rising in parts to a height of seventy-five 

 feet above the natural surface. These gigantic works 

 were executed tn-tween 17!K>and 1805, at a cost of 47,018/. 

 hi the locks of this canal Telford introduced cast-iron 

 framing in lieu of timber ; and in one instance, where the 

 lock was formed in a quicksand, he made every part of 

 that material. 



The Caledonian Canal is another of Telfotd's princi- 

 pal worlfs. In 1773 the commissioners of the forfeited 

 estates in Scotland had engaged Watt to report on the 

 practicability of a ship-canal alone; the valley called the 

 Glen of Scotland, to be formed by connecting the lakes 

 which form a series of navigable waters extending a great 

 part of the distance ; but although the report was favour- 

 able, it was not acted upon, and the scheme was deferred 

 for some years by the restoration of the forfeited c- 

 throuirh which the line would pass, in 1784. In 1801 

 however Telford was deputed by srovernment to make 

 a survey of the coasts and of the interior of Scotland, and 

 to report generally upon desirable public works for the im- 

 provement of the country. In consequence of his reports 

 Commissions were formed to carry out the proposed canal. 

 and other improvements classed under the general title of 

 Highland Roads and Bridges; and the services of Telford 

 were engaged by both boards. The Caledonian Canal was 

 opened throughout in 1823. Its construction was delayed 

 by many untoward circumstances; and unfortunately its 

 utility has not hitherto answered the expectations of its 

 projectors. It forms however a noble monument of the 

 skill of the engineer. The locks are stated by Telford to 

 be the largest ever constructed at that time, being forty 

 feet wide, and from one hundred and seventy to one hun- 

 dred and eighty feet long ; and one of them, at Clachna- 

 carry, near Inverness, was made under circumstances of 

 especial difficulty, the earth being a soft mud, into which 

 an iron rod might easily be thrust to a depth of fifty-five 

 feet. The means adopted for conquering this difficulty are 

 fully detailed in the engineer's own narrative. 



Of other canals constructed wholly or part ially under Tel- 

 ford's superintendence it is sufficient to mention the Glas- 

 gow, Paisley, and Ardrossan (which was never completed to 

 the length originally intended) ; the Macclesfield ; the Bir- 

 mingham and Liverpool Junction ; the Gloucester and 

 Berkeley completed under his direction) ; the Birmingham, 

 which was completely rcnuxlcllcd and adapted to the con- 

 duct of a very extensive traffic, by him ; and the Weaver 

 navigation, in Cheshire. He also constructed a new tunnel, 

 yards long, 16 IVet lusrh, and 14 feet wide, at Hare- 

 castle, on the Trent and Mersey Canal, the original tunnel 

 of Brindley having been found too small [TUNNEL] ; and he 

 executed many important works connected with the drain- 

 age of the fen country, especially of Bedford Level. On 

 the Continent likewise he superintended the construction of 

 the (lot ha canal, in Sweden, a navigation of about one 

 hundred and twenty English miles, of which fifty-live are 

 artificial canal. This navigation rises one hundred and 

 sixty-two feet from the Lake Wenern, at one extremity, to 

 the summit-level, and falls three hundred ami seven f< 

 Hie Baltic, at the other : the rise and f.ill :, 

 by fifty-six locks. The canal is forty-two feet wide at the 

 ii, and ten feet deep. Telford visited Sweden in 

 1808 to make the surveys and preliminary arrangements, 

 and again in 1813, taking with him, under the sanction of 

 the Bnti>h government, several experienced worki; 

 instruct the natives in the works then in progress. Upon 



the completion of the canal a Swedish order of knighthood 

 and other honours we; 1 upon Tel: 



.Mirks executed by Telfonl under tin 1 < 'ommissioners 

 (if Highland Roads and It:. 



His survey was delivered to the Lord* ( the Treasury in 

 ISKIJ. and in the following year the Commission WHS ap- 

 pointed. Of the works committed to their superintendence 

 Telford observes that 'the whole of Scotland. In 

 southern boundary, near Carlisle, to the northern extremity 

 of Caithness, ana from Aberdeenshire on the east 10 the 

 Argyleshire islands on the west, has been intersected by 

 roads; its largest rivers, and even inferior streams, ironed 

 by bridges : and all this in the space of twenty-live \ 

 under the same board, and (with some few exception! 

 the same individual Comm. and all this was 



under the direction of Telford alone. The pi-.i 

 rations under this Commission embraced about a tho 

 miles of new road, with twelve hundred bridges, in a moun- 

 tainous and stormy region, of which five only, according 

 to Telford's narrative, have required to be renewed. It 

 should be explained that the operations of the Commission 

 were not confined to the objects defined in its title, but 

 embraced also the Glasgow and Carlisle road ; the Lanark- 

 shire roads; the improvement of several harbours, of which 

 the principal are those of Peterhead, Banff'. Frazcrburgh, 

 Fortrose, Cullen, and Kirkwall ; and the erection of several 

 Highland churches and manses under a parliamentary 

 grant of 1823. Nor were these Highland churches and 

 manses the only buildings in which Telfonl acted as an 

 architect ; he had, many years previously, erected a church 

 at Bridgenorth, from his own design. 



In the improvements of the great road from London to 

 Holyhead, under another parliamentary Commission, ap- 

 pointed in 11;~>, Telford had a further opportunity of 

 carrying into effect his system of road-making, of which 

 an account is given under ROAD, vol. xx., p. 2!t. Sec. This 

 road, and the works connected with it. is probably the 

 most perfect specimen of Telford's skill as an engineer, 

 and appears to have been regarded by him with much 

 satisfaction. The Menai suspension-bridge, especially, 

 is a noble example of his boldness in designing and prac- 

 tical skill in executing a work of novel and difficult cha- 

 racter : it is described under MENAI BRIDGK, vol. x\ .. p. 91, 

 and SrspKNsioN-Bunx.K. vol. xxiii., pp. :r.H-.Y 



Among the other works of Telford are many bridges ot 

 considerable size, in which he adopted the important prin- 

 ciple of making the spandrils hollow, and supporting the 

 roadway upon slabs laid upon longitudinal walls, instead 

 of filling up the haunches with a mass of loose rubbish, 

 which may press very injuriously upon the arch, and often 

 proves of serious inconvenience when the masonry of tin- 

 bridge needs any repair. He employed this mode of con- 

 struction in a large arch, of 112 feet span, erected uvcr 

 the Dee, near Kirkcudbright, in 18)).-. and I8IK). and in 

 many subsequent bridges. In his ' Life' will be found 

 particulars of the ingenious alteration of Glasgow old 

 bridge, by the addition of a projecting footpath of east- 

 iron on each side, so as to leave the whole width of the 

 stone structure for carriages: and of the new bridge 

 designed by him for crossing the ( 'lyde at Glasgow, and 

 commenced in 1833: of the light and elegant Dean bridge, 

 at Edinburgh ; Path-head bridge, of live arches of "Ml feet 

 span, over a ravine about eleven miles south of Kdinhurgh ; 

 Morpeth bridge : Tewkesbnry bridge, erected between 

 1823 and 182fi, with a light iron arch of 170 feet span and 

 only 1" feet rise ; the Over bridge at Gloucester, and many 

 others. The last-mentioned bridge lias an arch of peculiar 

 form, previously employed by Perronet in the Neuilly 

 bridge. The general body of the arch is an elliptical 

 curv e of 15)1 feet span and 35 feet rise, but the external arch 

 stones ut the sides of the bridge form scgmcnlal CUP 

 the same span, but of only 13 feet rise: the two arches 

 are coincident at the crown, and are connected by a 

 vaulted form on the haunches of the bridge. This com- 

 plex form.' observes 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 when- 

 ever the tide or upland tlood rises above the springing of 

 the- middle of the ellipse, lhal being at four feet above 

 low-water: a precaution rendered nee.v-sary in this in- 

 stance owing to the liability of the bridge to vc T y trying 

 floods.' 



