An Irish engineer designed a diving bell so that men could work underwater, excavating and levelling a site. His work transformed Dublin's docklands, writes Mary Mulvihill.
An odd metal structure stands on Sir John Rogerson's Quay in Dublin's docklands.
Most passers-by don't give it a second glance, yet this is a historic Victorian diving bell that deserves to be better known.
In 1860 it was at the heart of a new, and internationally acclaimed way of building dock walls from pre-cast concrete blocks. And this revolutionary technique was pioneered by an ingenious Irish engineer, Bindon Blood Stoney, who was born 175 years ago this week, on June 13th 1833.
Stoney (1828-1909), from Clareen in Co Offaly, had studied engineering at Trinity College, Dublin and made his name as a young engineer in the 1850s working on the Boyne railway viaduct at Drogheda, which was an engineering triumph in its day. But it was as a port engineer that Bindon Blood Stoney came to greater fame.
Until 1860, men building a dock wall first had to construct a timber dam around the site. The water was pumped out from inside the dam, and the men could then build the traditional stone and rubble wall.
Stoney did away with all that. He designed a diving bell so men could work underwater excavating and levelling the site.
This enabled him to replace the stone and rubble with concrete blocks.
The design called for precision engineering to ensure a tight fit between blocks.
The diving bell, big enough to take a crew of six, was lowered into position in the river, and the men entered via an access tunnel from the surface. Compressed air was fed in from an adjacent barge. Even though the air was cooled, the temperature inside quickly rose and shifts lasted only 30 minutes.
The men prepared the river bed exposed at their feet, and all the excavated soil was stashed in baskets hanging inside the bell. These were brought up and emptied when the bell was lifted.
Meanwhile, the concrete building blocks were cast on-site. These monoliths weighed an unprecedented 350-tonnes, and took four weeks to make and a further 10 to "cure" before they could be lowered into place.
Once part of the new quay wall was built, the blocks for the next section could be made there, and so the wall inched forward.
Under Stoney, Dublin's docklands were comprehensively rebuilt from 1860 to the 1890s.
The additions included several kilometres of new quays, plus graving (dry) docks and the Alexandra Basin.
The development was fuelled by Ireland's increasing overseas trade - all of which went by sea then - and the latest steamships which needed enormous berths.
International interest in the new Dublin docks was considerable, as the berths were independent of the tides offering depths that were unsurpassed anywhere. When the British Association for the Advancement of Science met in Dublin in 1878, an expedition visited the docks to inspect the work.
Amazingly, Stoney's diving bell was still in use a century later to repair dock walls.
By this time it had a telephone link to the surface. When it was renovated in 2000, holes were cut to give a view of the interior.
Stoney Road near the East Wall is named after the Irish engineer who designed the bell and pioneered the use of pre-cast concrete as a building material, but Bindon Blood Stoney's most enduring monument is surely Dublin's docklands.