M WollSLKY TO MAXCHKSTKII. 353 



strongly expressed lv tin; public. He characterised the 



phiii uf the Barton a<pird net and embankment as instinct 

 with recklessness ;m<l lolly; and after expressing his 

 unqualified opinion as to the impracticability of executing 

 tin* design, lie concluded his report to the Duke thus: 

 " 1 have often heard of castles in the air; but never 

 before saw where any of them were to be erected." 



It is to the credit of the Duke that, notwithstanding 

 these strongly adverse opinions, he continued to give his 

 confidence to the engineer whom he had selected to carry 

 out the work. Briiidley's common-sense explanations, 

 though they might not remove all his doubts, nevertheless 

 determined him to give him the full opportunity of 

 carrying out his design ; and he was accordingly autho- 

 rised to proceed with the erection of his " castle in the 

 air/' Its progress was watched with great interest, and 

 people flocked from all parts to see it. 



The Barton aqueduct is about two hundred yards in 

 length and twelve yards wide, the centre part being sus- 

 tained bv a bridge of three semicircular arches, the middle 

 one being of si xty-three feet span . It carries the canal over 

 thi i Irwell at a height of thirty-nine feet above the river 

 1 1 1 is 1 lead-room being sufficient to enable the largest barges 

 t < > pass underneath without lowering their masts. The 

 bridge is entirely of stone blocks, those on the faces being 

 < 1 K -sst M 1 on t he front, beds, and joints, and cramped with iron. 

 The canal, in passing over the arches, is confined within 

 a puddled " channel to prevent leakage, and is in as good 



1 We Lave heard the name of duced to a semi-lluid state, and ren- 



Smcaton mentioned as that of the en- dered impervious to water by manual 



gineer eonsulted on the occasion, but | labour, as by working and chopping 



we are unalile to speak witli certainty J it about with spades. It is usually 



on the point. Kxcepting Smeaton, applied in three or more strata to a 



however, there was then no other en- 

 gineer in the country of recognised 



depth or thickness of about three 

 feet; and care is taken at each opera- 



eminence in the profession. [ tion so to work the new layer of pud- 



- The process of puddling is of con- j dling stuff as to unite it with the 



siderablc importance in canal eimineer- stratum immediately beneath. Over 



ing. Puddle is formed l>y a mixture the top course a layer of common soil 



of well-tempered clay and sand re- is usually laid. It is only by the 



VOL. I. 2 A 



