Articles, Maritime History

The Dublin Port Diving Bell

The Dublin Port Diving Bell

by Cormac F. Lowth

This article was first published in The International Journal of Diving History, Volume 3, Number 1, July 2010

Diving Bell

The restored bell


In  the  nineteenth  century,  several  factors  combined,  which  both  facilitated  and  necessitated  the expansion of the Port of Dublin. The seaward approaches to Dublin Port have always been hazardous to shipping. There are several offshore impediments to safe navigation that include the Kish Bank and Burford Bank, upon which hundreds of ships have been lost while attempting to reach the port.

Having braved all of these dangers, shipmasters now had yet another danger to face as they approached the mouth of the River Liffey. During the preceding centuries, access to the port was impeded by a hazard to navigation in the form of a large sandbank, known as the Bar of Dublin, which lay across the entrance to the main navigable channel of the River Liffey where it flows into Dublin Bay. The depth of water over this obstruction was as little as a few feet at times of low water spring tides, and ships approaching the port were frequently obliged to stand off or anchor to await high tide. When onshore winds blew up, many were thus caught on a lee shore and wrecked on the broad sandy expanses on either side of Dublin Bay, known as the North and South Bull. These areas are literally paved with the remains of the wrecks of sailing ships that were dependant upon the winds and tides and were equally, at times, at their mercy.


The  first  notable  improvements  to  the  port  entrance  were  carried  out  in  the  latter  half  of  the eighteenth century when the Great South Wall, which ran from Ringsend to the Poolbeg Lighthouse was built.  This  helped  to  define  the  channel  and  to  render  it  more  navigable,  however,  a  great breakthrough came in the early nineteenth century. Various reports had been submitted to the Port Authorities  as  to  how  to  overcome  the  problem  of  the  Bar,  one  of  which  was  prepared  by  Captain William Bligh of the famous Bounty Mutiny in 1801. He had undertaken, on behalf of the Admiralty, a comprehensive hydrographic survey of Dublin Bay and its approaches and one of his recommendations was for the building of a further wall on the north side of the channel. Other engineers had made similar suggestions and as a result, the North Bull Wall, which runs from Clontarf to the Bull Lighthouse, was built between 1819 and 1824. The tidal water thus enclosed by these walls created a sluicing action on  the  ebb  tide,  which,  over  the  next  few  decades,  shifted  the  sands  of  the  Bar  of  Dublin  around northwards to form what is now known as The Bull Island, which remains today as a wonderful amenity for the citizens of Dublin with beautiful dunes and sandy beaches. This engineering work, combined with new dredging techniques, now gave free access at all stages of the tide to the port to bigger and more deeply laden ships.

Bindon Blood Stoney

Bindon Blood Stoney

Up to this time, berthage in the port was confined to the north and south quay walls that ran from Ringsend right into the heart of the City. These had been adequate in the past to accommodate the size of vessels and the volume of trade that then existed, however, with the advent of steam powered merchant ships and advances in the technology of iron and steel shipbuilding, and a consequent huge upsurge in world trading patterns, the existing berthage and facilities for loading and discharging cargoes were soon found to be hopelessly inadequate. At first improvements were made to the existing quay walls by limited rebuilding and deepening but the pressing need for deep-water quays quickly resulted in various proposals being examined as to how this could be best achieved. Initially, traditional methods of coffer-damming and dry building were proposed by the resident port engineer George Halpin, whose duties also included being Inspector of Works and Superintendent of Lighthouses. With the onerous schedule of these duties, much of his work in the Port of Dublin was devolved upon his Assistant Engineer, an innovative genius who was to revolutionise the work of building the new quay walls in Dublin Port, Bindon Blood Stoney (1828–1909).


Stoney was born at Oakley Park near Birr (formerly Parsonstown) in County Offaly in the Irish Midlands.  He attended Trinity College in Dublin where he graduated with great distinction as a civil engineer. His first working appointment was as assistant to William Parsons, the third Earl of Rosse, in his observatory at Parsonstown where the Earl had designed and built a giant seventy-two inch telescope, known as the Leviathan, which is still in existence today. The Earl’s son, Charles Parsons, perfected the steam turbine which came to be adopted in many warships and other vessels. There can be little doubt that Stoney must have benefited from association with such inventive geniuses. He next took an appointment on a railway project near Aranjuez in central Spain and on his return to Ireland; he worked on the River Boyne railway crossing near Drogheda. In 1856, at the age of twenty-eight, after several interviews, he was appointed as Assistant Engineer of the Port and Docks Board of Dublin.


The Diving Bell and Float

The senior engineer of the port George Halpin, had many other duties to perform in his capacity as Director of Works and Superintendent of Lighthouses for the many coastal lights that were then in the care of the Port Authorities and because of Halpin’s prolonged absences, Stoney became in effect the de facto port engineer. One of his first major tasks was to supervise the completion of a new graving dock. In 1862, Stoney submitted a counter proposal to Halpin’s to the board, using a method which he  maintained  would  cost  only  half  of  that  of  the  traditional  cofferdam  system  with  the  necessity of laboriously hand laying cut stone blocks. He also contended that the work could be done much quicker with his method. Stoney proposed to build huge prefabricated concrete blocks on the shore and to lay them on a prepared seabed by the use of a large floating shear-crane. He further proposed that workmen operating in a large diving bell, slung from a floating barge, be used to level the seabed.  Halpin, understandably, was none too pleased at his subordinate’s attempts at a counter-proposal to his own and he attempted to scupper Stoney’s plan from the outset. He maintained that the idea was not feasible and urged them to accept his own suggestions. Perhaps the idea of saving so much money on the project, coupled with Stoney’s forceful arguments, must have swayed the members of the Board as, after much discussion, it was decided to adopt Stoney’s proposals. Halpin, whose health was at that time failing, decided to retire shortly after and Stoney was officially appointed as Senior Engineer.


It  took  several  years  before  Stoney’s  plans  for  the  deep-water  docks  came  to  fruition. There  was urgent work needed in underpinning and re-building the existing quay walls and deepening the channel alongside. By 1871 the work on the new docks had been started and the first section to be built was what is known today as the North Wall Extension, which runs eastwards from the Point Bridge. The work was not put out to tender as it was decided to use direct labour within the port, a decision that was to pay dividends by the accumulation of useful skills among the workforce. The photograph of Bindon Blood Stoney shows an almost patriarchal looking figure and in some ways this was true. During his time as Port Engineer, Stoney gained working conditions and pension rights for the labourers and tradesmen in his care that were far in advance of those which generally prevailed at the time.


The Shear Float

Provision of the equipment to carry out the works was put out to tender and the firm of Harland and Wolff in Belfast was granted the contract to supply the shear float while the contract for the bell float went to the engineering firm of Thomas Grendon & Co. of Drogheda in County Louth. The shear float measured one hundred and thirty five feet long by forty-eight feet beam by fourteen feet overall depth and the bell float was eighty feet long by thirty feet beam by eight feet depth. The bell chamber was twenty feet square and the access shaft with its airlock chamber was three feet in diameter. There was six and a half feet of headroom inside. The overall depth of the bell including the shaft and air-lock chamber was forty-four feet. The horizontal air pump, and the lifting gear on both barges were driven by steam engines mounted inside the barges. The surrounding water had a cooling effect on the air going to the bell chamber, nevertheless, men working in the bell chamber found the atmosphere oppressively warm. The concrete blocks measured twenty-two feet wide by twelve feet in linear length. They stood twenty-seven feet high and they were designed to give a working depth of twenty feet below ordinary spring tide low water level.


The Block Wharf

All of the equipment including the shear float and the bell was designed by Bindon Blood Stoney.  He also designed the machinery to mix the concrete that went into the making of the blocks. The large-scale use of concrete using Portland cement was still in a basic stage of development in the middle nineteenth  century.  The  concrete  mixer  designed by  Stoney  was  capable  of  delivering  about  twelve cubic yards of concrete per hour and it was powered by  a  three  horse-power  motor.  The  blocks  were cast  on  a  specially  built  block  wharf  and  allowed to  cure  for  several  weeks.  Large  cast  iron  girders were  incorporated  into  the  bottom  of  the  blocks and the wrought iron lifting bars were attached to these.  Large  stones  were  used  in  the  construction to  bulk  out  the  cast  concrete.  The  procedure  for lifting  the  blocks  involved  the  shear-float  moving bow-first  up  to  the  platform  of  the  block-wharf,  which was set low near the water. After the crane was  attached,  the  ballast  tanks  in  the  after  end  of the shear float were filled and this tilted the barge enough to lift the block. The barge was then towed to the laying position. The shear float was described as…  A  powerful  tubular  girder…which  distributed the shearing strains over the whole area…


The area for the new quay was first dredged down to the solid substrate and the crew in the diving bell  then  levelled  the  seabed  by  distributing  the  gravel,  or  in  some  cases,  loading  any  surplus  onto platforms in the bell, which was then disposed of elsewhere when the bell was again moved. The normal crew consisted of six men and incredibly accurate results were achieved when the blocks were joined together.  Grooves  cast  into  the  blocks  were  subsequently  filled  with  concrete  to  key  them  together.  Large rebates were also cast into the blocks to take stone facing blocks for the new piers and in some instances, part of the stone facing work was completed on the blocks while they were still on dry land.  Each concrete block weighed three hundred and fifty tons. There are fine scale models of the shear float and the diving bell in the Engineering Department Museum in Trinity College Dublin.

The physiological effects of working in compressed air may not have been fully understood by the crews working in the bell as there are several accounts of men suffering with ear trauma and bleeding from the nose and ears, particularly when working with colds or congestion, something that would be unthinkable in the present day. Nevertheless, throughout the history of the operations using the diving bell in the port, there is no recorded instance of any serious accident or fatality. The blocks were laid in parallel rows where berthage was required on either side of the new quay walls and space between was filled with spoil from the dredging operations. The walls above water were then built up in the conventional manner.

An old photo with Shear Float in the distance

From the ‘Illustrated London News’, showing the Prince and Princess at the naming ceremony with Bindon Blood Stoney in attendance. The diving float and bell are featured.

Stoney persisted throughout in his design concepts with the idea of building for the future as he foresaw the days when bigger ships would use the port. It stands to his credit that all of the new quays and docks that were designed and built by him are still able to take the biggest ships that are capable of entering the port. By the time the first blocks were laid, trade in Dublin Port had more than trebled over a period of thirty years. Over the following fifteen years, all of the North Wall Extension and the deep-water basin were completed. Many prominent people and members of various scientific and engineering organisations visited the port to see the new quays being built. Stoney was awarded the Telford Medal by the British Institution of Civil Engineers in 1877. Also in that year, William Gladstone visited the works in progress and he was shown around by Stoney. The Prince and Princess of Wales visited Dublin in 1885 and officiated at the naming ceremony for the new deep-water docks. Princess Alexandra broke a bottle of wine and christened the dock ‘Alexandra Basin’, the name it still bears. There is a contemporary illustration from the  ‘Illustrated London News’ that shows the Prince and Princess at the naming ceremony with Bindon Blood Stoney in attendance and the diving float and bell in the background. While there, they were given a demonstration of the shear-float laying one of the blocks.

The Opening of Beresford Swing Bridge in 1879

The shear float and diving bell were used for several other improvements in the port including laying the pre-cast foundations for the new Bull Wall Lighthouse and laying concrete reinforcing blocks around the Poolbeg lighthouse. The decision to adopt Stoney’s method of using pre-cast concrete blocks was vindicated as the work was finished within both the stated time frame and the budget that was allowed for the works. Many more improvements and innovations were carried out by Stoney during his tenure as Port Engineer. He designed the dredging equipment and the great hopper floats that were used for deepening the channels. Several of the bridges upstream from the port were in need of replacement, notably the old Essex Bridge, for which Stoney designed and built a fine wide replacement in 1873. He also designed the steam-powered Beresford Swing Bridge which has since been replaced by the present Butt Bridge. The latticed iron balustrade of the Essex bridge was regarded as very ugly by many of the citizens of the day. No such inference could be attached to one of the most visible of Stoney’s achievements in Dublin, that of the new Carlisle Bridge in the very heart of Dublin. Today known as O’Connell Bridge, it replaced an older narrow hump-backed bridge that was totally inadequate for the volume of traffic that daily thundered along the capital’s main street. The contractor, Doherty, used caissons and cofferdams that were designed by Stoney. The bridge, like O’Connell Street which it adjoins, is exceptionally wide, and with its elliptical arches and stone balustrades, it remains a pleasing architectural gem and a fitting monument to its designer, Bindon Blood Stoney.

Joe Murphy in srandard Dress

Stoney retired in 1898 after forty-two and a half years of service, leaving behind him an efficient, modern, deep-water port. During his working life he received many honours and accolades from several sources including an Honorary Doctorate from Trinity College Dublin. He was the president of the Institution of Civil Engineers for many years. His opinions were sought and respected far and wide on civil engineering matters and port development. He died on May 5th 1909 and there were many tributes to him that mentioned his great achievements and his sincere humanitarian personality. There is a road in the Docklands area named after Stoney.  Such was the scale of development achieved by Stoney and the port workers that no further expansion was required until well into the twentieth century. The shear float was laid up and it was scrapped in 1919.

The bell with its attendant float was retained in the port and it was to experience a renewed career from the 1920s on. A new method of building quay walls was instigated by the Dublin Port Engineer who was appointed in 1917, Joseph H. Mallagh. This consisted of building large hollow concrete blocks on the shore and floating them into position where they were sunk and filled with dredging spoil. These blocks became known as ‘caissons’ in the port. Again, the diving bell was used to level the seabed and the new development continued until the 1950s with the building of oil and timber jetties and the Ocean Pier extension to Alexandra Basin, after which, the bell was laid up in the corner of the port dockyard.

Two of the Crew of the Bell

The last foreman to work in the Dublin Port diving bell was a renowned Ringsend boat-builder named Joe Murphy who worked in the port as a shipwright. Joe is retired now but he has remained active as a builder of traditional boats. When interviewed by the author he described what it was like to work in the diving bell. There was electric light and a telephone connection in the bell and a stint normally took about five hours. They also had to do shift work to take account of the tides, which sometimes involved going down in the bell in the small hours of the morning or late at night. The squad were experienced and tough and many newcomers fell by the wayside when they encountered the compressed atmosphere and the cramped working conditions.  Ear and sinus problems were frequent.

The Crew of the Original Bell

The last job carried out by Joe and his team in the diving bell was to lay the caissons for a new lead-in jetty and it was a particularly arduous job as the area had been prepared by a bucket dredger and there were many ridges. Sometimes the team, working in thigh boots and overalls, had to move as much as ten tons of material on the seabed on a single shift and this frequently involved shovelling much of this onto the side platforms to be disposed of later. Joe developed a unique method of levelling by driving pegs into the seabed and relating them to the depth gauge in the bell.

The work on each caisson involved moving the bell about six times. Sometimes the hot compressed air reacted with the cold water and created a fog that blotted out all visibility in the bell. One of the few perks of working in the diving bell was to find a few plump flatfish that had been left behind on the bottom when the water receded, for their supper. The access shaft of the bell was lengthened at this time to take account of the greater depth in which it was being used.

Joe Murphy with the Bell model

Joe Murphy had taken over as supervisor in the bell from John Reilly, another port shipwright, who had graduated to standard dress diving. When the bell was laid up and John Reilly received further promotion, Joe took over his duties as the port diver, in which capacity he served for several years before eventually becoming a Senior Technical Supervisor. The bell was in danger of being scrapped in the 1980s but due to strongly voiced opinions from many people including Joe Murphy, the decision was made to save this unique artefact for posterity. A large floating crane, the Mersey Mammoth, was on charter in the port and this was used to transport and lift the bell to its present location on Sir John Rogerson’s Quay. The lift and placement of the bell onto a prepared plinth was supervised by Joe Murphy. In 1989, the Dublin Docklands Development Authority decided to donate money to have the bell restored. The Dublin Port Company also contributed to the project. The nearby St. Andrews Resource Centre formed a committee, which included Joe Murphy, now retired, to supervise the refurbishment. The bell was shot blasted and painted inside and out and a viewing port was cut into one side of the bell through the massive eight-inch thick iron plating of the chamber. The access shaft with the airlock was adjudged to be beyond repair and it was faithfully replicated by the Fingal Steel Company. There is a scale model of the bell in the St. Andrews Resource Centre. Although lacking a plaque to explain its original purpose, the bell stands today as a unique piece of industrial archaeology and a testament to the men who built the modern port of Dublin.



Bindon Blood Stoney, Biography of a Port Engineer.

Ronald Cox. Monograph 1990.

Dublin’s Diving Bell, a History. St. Andrews Resource Centre monograph 2003.

Joe Murphy, Ringsend Boatbuilder and Master Shipwright, Autobiography, 1989.

History of the Port of Dublin, Harry Gilligan. 1989.

Dublin Diving Bell, Cormac F. Lowth, SUBSEA, no. 81 Autumn 1995.

Joe Murphy, Personal Interview.

Wreck and Rescue on the East Coast of Ireland, John de Courcy Ireland. 1983.

Illustrated London News.


Joe Murphy, Desmond Branigan, Tony Brennan, and The Late Robbie Brennan of the Maritime Institute of Ireland.


Cormac Lowth is a building contractor who has been a sport diver for many years. He has written many articles of historical and travel interest for several diving and historical magazines and journals.

He is a member of the Maritime Institute of Ireland, The Old Dublin Society, and the Irish Maritime Archaeological Society.  He is well known as a lecturer to many historical and diving societies.