Pontcysyllte Aqueduct World Heritage SitePosted: 2009-06-28
I just read with interest the story that the Pontcysyllte aqueduct near Wrexham has been named a World Heritage Site. The aqueduct thus joins other British icons like Stonehenge, Hadrian's Wall, and the Tower of London in being awarded that distinction.
The aqueduct was designed by Georgian engineer Thomas Telford and William Jessop to carry the Llangollen Canal over the River Dee. At 126 feet in length it is the longest (and highest) aqueduct in the UK.
Telford is widely regarded as an architectural genius, a man given to creating solutions to what his contemporaries thought to be impossible engineering challenges. But for the aqueduct, Telford used a mix of state-of-the-art engineering and traditional materials. It was important to seal the joints of the iron castings. Telford devised an intriguing solution that used flannel and lead dipped in boiling sugar. The mortar was made from a mixture of lime, water and ox blood.
It took 10 years to build the Pontcysyllte aqueduct, with construction beginning in 1795 and ending in 1805. The entire project cost £45,000, an enormous sum at the time. The aqueduct is supported on 18 large stone columns, and still carries almost a quarter of a million boat passengers each year.