On this day in history : 25th July 1795 – The first stone of the Pontcysyllte Aqueduct, which carries the Llangollen Canal over the valley of the River Dee in Wrexham, North East Wales, is laid….
Pontcysyllte means ‘the bridge that connects’…. Designed and built by Thomas Telford and Williams Jessop it was considered a masterpiece of creative genius….and took around 10 years from design to completion….
Conceived as a waterway without locks the 307m long, 3.7m wide cast and wrought iron construction allows a cast iron trough to be supported 38m above the river on arched iron ribs…. The light but strong archways are in turn supported by 18 hollow masonry pillars; each of the 18 spans being 16m wide….
The mortar used was a mixture of lime, water and ox blood…. This may sound macabre but blood had been used in mortar for centuries; the haemoglobin found in blood helps strengthen mortar which is exposed to the elements – as it protects from breaking up in the freeze-thaw temperature cycles of climates such as ours here in Britain….
Above the 1.60m deep water trough a towpath was built and railings added to prevent pedestrians and horses from falling…. The project cost around £47K to complete – that is less than £4m in today’s terms…. The aqueduct was officially opened to traffic on the 26th of November 1805…. Since then it has been closed once every 5 years and the water drained to allow inspection and maintenance…. On the 27th of June 2009 the Pontcysyllte Aqueduct was made a World Heritage Site and is now a major tourist attraction….