Griffith, Sir John Purser (1848–1938), civil engineer, was born 5 October 1848 at Holyhead, north Wales, the only son of William Griffith (1801–81), Congregational minister, and Alicia Griffith (née Evans), a member of a leading Welsh Moravian family. John's elder sister died in 1854 of scarletina. Purser Griffith became an influential member of the Moravian church, rising to become a brother advocate, and took great pride in his Welsh-Moravian ancestors. His father, William Griffith, had formed strong ties with the Purser family in Dublin, being a close friend of John Tertius Purser (1809–93), head brewer at Guinness and himself a prominent member of the Moravian community in Dublin. John was given the second name Purser in recognition of these family links. Like his father, Purser Griffith was a competent mathematician and had an excellent command of language. He was educated at a preparatory school in Devizes, Wilts., and at Fulneck School in Leeds, before entering TCD (1865) to read civil engineering.
On leaving college (1868), he became a pupil (trainee) under Bindon Blood Stoney (qv), chief engineer at Dublin port. After a brief period as an assistant surveyor in Co. Antrim, he returned in 1871 to Dublin port as Stoney's assistant. During a partnership of twenty-seven years, many important improvements were made to the port, including improvements to the riverside quays, the extension of the North Wall to form deep-water berths in Alexandra Basin, and a major programme of dredging.
In 1871 Griffith married Anna Benigna Purser, the only daughter of his father's lifelong friend John Tertius Purser and Anna Benigna Fridlezius, and went to live at ‘Greenane’ in Temple Road. In 1903 Anna inherited the Purser family home, Rathmines Castle, from her brother, and she and Griffith moved there with their daughter Alice (1876–1936). Their elder son, John William (1875–1936) was by then married and continued to live at ‘Greenane’. A younger son, Frederick (1878–1939), lived nearby in Temple Gardens.
In January 1899 a reconstituted Dublin Port & Docks Board took office and in the same month Griffith formally took over from Stoney, who had retired on health grounds. He set about reorganising the dredging operations, using a new suction dredger to straighten, widen, and deepen the approach channel to the port, much of the dredged material being used to reclaim land to the north of the river. Between 1900 and 1907, all the north and south quays were reconstructed to provide deep-water berths at all states of the tide. Electrical equipment was provided throughout the port, which had its own power station, commissioned in 1907. An 80 ft high (24 m) 100-ton capacity electric crane was installed in 1905.
Griffith was knighted in 1911, not for his work at Dublin port, but for his work as Ireland's representative on a royal commission appointed in 1906 to report on the state of the canals and inland navigations of the United Kingdom. Being in total disagreement with board policies on engineering work in the port, he took early retirement in 1912, and in 1917, with his two sons as partners, established a small engineering consultancy, Sir John P. Griffith & Partners, with offices at 6 Dame St., Dublin. The work of the consultancy was never extensive, but became a base for the development of a number of projects of national importance, in particular the development of the country's water-power and peat resources.
Fuel shortages during the first world war resulted in consideration being given to alternatives to the use of imported coal. A sub-committee of the UK commission on water-power resources, set up in 1918 with Sir John Griffith as its chairman, established a prima facie case for the greater use of waterpower to generate electricity. He advocated the development of the power potential of the River Liffey, on the basis that electricity would be generated near to the largest concentration of potential users. However, the Free State government, having been persuaded to adopt a plan put forward by Thomas McLaughlin (qv), proceeded instead with the construction of a large hydroelectric power station on the River Shannon at Ardnacrusha, Co. Clare. The Shannon scheme was completed in 1929, the Electricity Supply Board having been set up in 1927. The power of the Liffey was eventually harnessed in 1943.
A committee of inquiry, set up in 1917 under Griffith's chairmanship, investigated the utilisation of Irish peat deposits. The conclusion – that the winning of peat for fuel was feasible if combined with land reclamation for agricultural purposes – was not acted on. Griffith decided to mount a personal campaign to show what could be achieved and, at Turraun Bog near Ballycumber, established in 1924 one of the earliest machine peat operations in Ireland.
He was made a freeman of the city of Dublin in 1936 and was a member of Seanad Éireann from 1922 to 1936. The acceptance of his amendment to the jury service bill in 1927 resulted in professional engineers being exempted from jury service. He was president of the Institution of Civil Engineers of Ireland (1887) and of the Institution of Civil Engineers (1918), a member of the RIA, and a recipient in 1922 of a Boyle Medal from the RDS. In 1914 he received an honorary degree of MAI from the University of Dublin, and in 1936 an honorary doctorate from the NUI.
He died at Rathmines Castle, Dublin, on 21 October 1938, having rightly earned the epithet ‘Grand Old Man of Irish engineering’. A portrait in oils by his niece Sarah Purser (qv), RHA, hangs in the Museum Building in TCD.