74 JESSOP. 



Brentford, and by a branch starting five miles above at Bullbridge, 

 stretching to Paddington, from whence the Eegent's Canal proceeds 

 round the north side of London to the Thames at Limehouse, thus 

 completing the connection between the main line and the lower 

 part of the river. The execution of this canal necessitated the 

 construction of many heavy works, consisting of tunnels, deep 

 cuttings, embankments, aqueducts, reservoirs, and weirs. Of these 

 works one of the most famous is the Blisworth Tunnel, 3080 yards 

 in length, cut through the inferior oolite and the shales of the lias. 

 Its internal width is 16 feet, the depth below the water-line to the 

 inverted arch being 7 feet, while the soffit or crown of the arch is 

 11 feet above the same line. The cost of this great undertaking, 

 with all its branches and attendant works, amounted to about two 

 millions sterling. 



During the execution of this work, Mr. Jessop was also called 

 into Ireland, and was taking an active part in carrying on the public 

 works which had been undertaken by the authority of Parliament in 

 that country. 



The year 1793 originated several great projects, in furtherance of 

 which Mr. Jessop's aid was secured. Amongst these were the 

 Grantham Canal, supplied by vast artificial reservoirs, and extend- 

 ing from the river Trent, through a rich pasture district of the new 

 red sandstone, winding for many miles through the broad and 

 fertile vale of Belvoir, up to Grantham at the base of the Lincoln- 

 shire hills, the furthest point to which it is possible to penetrate in 

 this direction. 



The Barnsley Canal, which opens up an immense amount of 

 mineral wealth in the Yorkshire coalfield, and brings it into com- 

 munication with the river Calder, and the Dearn and Dove Canal ; 

 and finally, the Great Ellesmere Canal, which completes a commu- 

 nication between the Severn and the Mersey, and ramifies in 

 numerous directions amongst the rugged hills and valleys of North 

 Wales. 



In the carrying on of this last named undertaking, Mr. Telford 

 was likewise engaged under Mr. Jessop. Two of its most important 

 works are the great aqueducts of Chirk and Pont-y-cysylte, the 

 former of which carries the canal over the river Ceriog, at an 

 elevation of 70 feet, while the latter carries it across the Dee at an 

 elevation of 127 feet. The grand peculiarity in these aqueducts 

 consisted in constructing a water-tight trough of cast iron for 

 carrying the canal across the arches, instead of an immense puddled 

 clay trough, as was the practice until that time in use. The execu- 

 tion and management of the numerous works here mentioned occu- 

 pied the greater part of Mr. Jessop's time during the next few years. 

 But the commencement of the present century was the signal for 

 another torrent of speculation, which, in addition to canals, began 

 now to be directed towards docks and railroads. The promoters of 



