CHAP. VI. 



AQUEDUCT OF PONT-CYSYLLTAU. 



347 



trough for the canal. The model being approved, the 

 design was completed ; the ironwork was ordered for 

 the summit, and the masonry of the piers then pro- 

 ceeded. The foundation-stone was laid on the 25th July, 

 1 795, by Richard Myddelton, Esq., of Chirk Castle, M.P., 

 and the work was not finished until the year 1803, thus 

 occupying a period of nearly eight years in construction. 



The aqueduct is approached on the south side by an 

 embankment 1500 feet in length, extending from the 

 level of the water-way in the canal until its perpen- 

 dicular height at the " tip " is 97 feet ; thence it is carried 

 to the opposite side of the valley, over the river Dee, 

 upon piers supporting nineteen arches, extending for 

 a length of 1007 feet. The height of the piers above 

 the low water in the river is 121 feet. The lower part 

 of each was built solid for 70 feet, all above being 

 hollow, for the purpose of saving masonry as well as 

 ensuring good workmanship. The outer walls of the 

 hollow portion are only two feet thick, with cross inner 

 walls. As each stone was exposed to inspection, and 

 as both Telford and his confidential foreman, Matthew 

 Davidson, 1 kept a vigilant eye upon the work, scamping 

 was rendered impossible, and a first-rate piece of masonry 

 was the result. 



Upon the top of the masonry was set 

 the cast iron trough for the canal, with its 

 towing-path and side-rails, all accurately 

 fitted and bolted together, forming a com- 

 pletely water-tight canal, with a water-way 

 of 11 feet 10 inches, of which the towing- 

 path, standing upon iron pillars rising 

 from the bed of the canal, occupied 4 feet 

 8 inches, leaving a space of 7 feet 2 inches 

 for the boat. 2 The whole cost of this part of the canal 



Section of Top of Pont- 

 Cysylltau Aqueduct. 



1 Matthew Davidson had been Tel- 

 ford's fellow workman at Langholm, 

 and was reckoned an excellent mason. 



He died at Inverness, where he had a 

 situation on the Caledonian Canal. 

 2 Mr. Hughes, C.E., in his * Me- 



