Monday, 8 June 2009

Wigwell Aqueduct

Wigwell Aqueduct (aka Derwent Aqueduct)
Cromford Canal

You can't accuse William Jessop of a lack of variety. He seemed to see relish variety and after the earthwork with stone arches of Amber Aqueduct, he tackled the crossing of the River Derwent in great style using Crich Limestone.

Captain's own collection

He started work on Wigwell Aqueduct in 1790 but by 1793 his part completed structure started to fail and serious cracks were found, which were attributed to the use of a lime mortar from a quarry in nearby Crich. The mortar didn't ever set and, at his own expense, he rebuilt the structure using iron cramps, which continue to hold the masonry together to this day.

Jessop was a man at the forefront of his profession, having previously been John Smeaton's deputy and was keen to establish his reputation as an engineer, hence his willingness to remedy the defects on the Cromford aqueducts at his own expense. Whilst the Wignwell Aqueduct was being rebuilt cargo was carried via tramway on a temporary bridge. His own account of this failure places the blame squarely on his own shoulders:

"The failure happened for want of a sufficient strength in the front walls and I blame no one but myself for the consequence, having often seen profusion of expense by an unnecessary consumption of materials."

The aqueduct has an overall length of 182.9m, carrying the northern end on the Cromford Canal 38ft above the level of the River Derwent, using three arches. The central elliptical span in an impressive 73m with smaller accommodation arches at either end.

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