Macneill, Sir John Benjamin (1793–1880), civil engineer, was born 5 May 1793 at Mount Pleasant, Ballymascanlan, Dundalk, Co. Louth, the only son of Torquil Parks Macneill, a captain in the Louth militia, and his wife, Suzanna Macneill (née Thomson) of Ravensdale. He had two sisters, Hester and Maria. He enlisted in the Louth militia in 1811, was educated as a military engineer, and studied mathematics. About 1821 he married Isabella Mercer, daughter of Robert Mercer of Dublin, with whom he had six sons and four daughters. From 1816, when the militia was disembodied, to 1826 Macneill worked as a civil engineer in Louth and Meath under John Foster (qv), the last speaker of the Irish house of commons and foreman of the grand jury. He also worked as a surveyor for Alexander Nimmo (qv) in the west of Ireland. On the recommendation of these two men he was appointed assistant to Thomas Telford on the London–Shrewsbury section of the London–Holyhead road. During this time he took out a patent for a mass concrete road and designed a dynamometer which indicated the tractive force required to draw carriages along roads. One of the principal uses for this instrument was to assess the deterioration of roads over time. Telford wrote in the seventh report of the commissioners for the Holyhead and Liverpool roads: ‘I consider Mr. Macneill's invention, for practical purposes on a large scale, one of the most valuable that has been lately given to the public.’
The railway era had started but Telford, who had spent much of his working life on roads and canals, was not in favour of railways. Macneill supported him loyally. Initially under Telford's direction he carried out experiments on model canal boats and shortly afterwards on canals in Scotland and England. His experiments showed that ‘passengers and light goods may be carried by canals at a velocity hitherto supposed to be impracticable’ (Canal navigation (1833), introduction). Telford also promoted steam carriages on roads and Macneill was an important witness to a parliamentary commission set up to investigate the high tolls charged to these vehicles. Macneill's contract with the commissioners of the London–Holyhead road allowed him to engage in private practice; in the early 1830s he set up offices in London and Glasgow and somewhat later in Dublin. In Scotland he built railways in the coal and mineral districts, notably the Slamannan railway, and also acted as consultant on harbours and canals. In 1833 Macneill published Tables for calculating the cubic quantities of earth work in cuttings and embankments, a second edition of which appeared in 1846, and contributed an appendix on his traction measuring device to Sir Henry Parnell's A treatise on roads. He also published a translation from the French (1835) of Claude-Louis Navier's book on comparing lines of railway.
In 1836 Macneill was asked to survey for laying railways in the northern half of Ireland by the Irish railway commission, who indicated where they wanted the lines to run. The commission's report issued in 1838 was not well received by the railway speculators, who were prepared to invest in a coastal line from Dublin to Drogheda, for which an act had been obtained in 1836, whereas the commission recommended an inland route via Navan. The start of work was considerably delayed owing partly to the report and also to the state of the money market. The speculators won out and Macneill was appointed chief engineer in February 1840 for the coastal line. The work went well and one of Macneill's major innovations was the use of iron, for the first time, in two lattice girder bridges near Dublin, which performed very satisfactorily. The railway was opened on 24 May 1844 by Earl de Grey (qv), the lord lieutenant, who knighted Macneill on the occasion. When recommending the opening of the line Major-General C. W. Pasley, the inspector general of railways, stated: ‘I never saw a line in a more satisfactory state, and it is universally admitted that it will be of the greatest benefit to the country’ (Pasley to lords of privy council for trade, 22 May 1844, TNA, Kew (MT 6/1/299). Macneill was also the engineer for the Dublin and Belfast Junction Railway, but the line was not completed until 1855, when the magnificent Boyne viaduct was built, using the lattice girder principle. James Barton (qv), the resident engineer, claimed credit for the bridge, but there is no doubt that the concept and responsibility were Macneill's.
Macneill was chief engineer for many railways in Ireland and Britain, both built and not built. He was chief engineer for the Great Southern and Western Railway Co., and in 1843 he moved from London to Dublin, where he had his residence and office in 27 and 28 Rutland Square (later Parnell Square). The first line was to Carlow and it was opened on 8 April 1846. About sixty engineers and 5,000 labourers were employed on this section. The line which eventually ended in Cork was under construction at the same time. Blackpool, north of Cork, was reached on 18 October 1849 by a directors’ train in five hours from Dublin.
In spite of his very large practice Macneill was persuaded to become the first professor of practical engineering at TCD in November 1842. He could not have been present daily, but he certainly took part in the examinations – in 1851, for example, spending a day examining in drawing, surveying, and practical engineering, three weeks after the main examination period. He was made professor extraordinary in 1852. Besides his busy practice and educational commitments he had a lime works and a flax mill at Mount Pleasant which gave much employment in the area.
In 1856 Sir John travelled to the Middle East with General Francis Chesney (qv) who was promoting the Euphrates Valley Railway as a means of shortening the route to India. Sir John, ‘the celebrated engineer’, was brought along to undertake the surveys. Chesney described him as a delightful companion, full of buoyant spirits, amused by the little incidents of travel, and full of wit and anecdotes. Macneill had to return home early and his son Telford completed the survey, though the government refused to support the scheme.
Macneill was an accomplished architect. In 1852 he designed the unusual Egyptian arch at Newry and the Craigmore viaduct. The latter is a fine piece of architecture as well as engineering, and is certainly one of the most impressive railway structures in Ireland. The original station at Portadown, built in 1861–2, is a good example of his station design and it is also probable that he designed the Palladian-style extension to his house at Mount Pleasant.
His heavy involvement in railways led to financial difficulties for he often had to take shares in lieu of payment and to subscribe for shares. He was heavily involved in the railway mania of the mid 1840s and there must have been many companies that failed to pay him for surveys. Although he was certainly entrepreneurial, he was not good at managing his financial affairs. In 1868, at the age of seventy-five, he had to sell his house and lands at Mount Pleasant and go to live in London with his sons. The very substantial contents of the house, including 10,000 books, were sold over a fortnight. He remained active and during the period 1868–76 took out seven patents. Towards the end of his life he lost his sight, and invented a writing system for the blind. He died 2 March 1880 of heart failure at his residence, 186 Cromwell Road, London, in his eighty-seventh year; he was buried in Brompton churchyard.
Macneill was elected an associate of the Institution of Civil Engineers in February 1827 and a member in 1831. He was elected MRIA (1833), FRAS (1833), FRS (1838), and MICEI (1846). He was awarded an honorary LLD (1843) and MAI (master in engineering; 1862) by the University of Dublin.