# Dictionary of National Biography, 1885-1900/MacNeill, John Benjamin

​MACNEILL, Sir JOHN BENJAMIN (1793?–1880), civil engineer, son of Torquil P. MacNeill of Mount Pleasant, co. Louth, where the family had long been settled, was born about 1793, and in early life served in the Louth militia. His name appears as a lieutenant from 29 April 1811 until the disembodiment of the militia at the general peace. Through the parliamentary interest, it is believed, of Robert King, first viscount Lorton, a neighbour of the family, MacNeill obtained employment under the engineer, Thomas Telford, then engaged in road and bridge making in Scotland and England, and became one of Telford's principal assistants or 'deputies.' He was entrusted with the improvement of turnpike roads in the north of England, having his headquarters at Daventry, Northamptonshire. He carried out important experiments relating to traction and road maintenance, and arrived at the conclusion that the iron-shod feet of horses are more destructive to roads than any other accessory of swift travelling. He devised an instrument to be drawn along roads, to indicate their state of repair by the deflections produced by the irregularities of road-surface, in the trace of a continuous curve line. A similar instrument was afterwards invented by Charles Babbage [q. v.], and tried without success on the Brighton railway.
Under Telford (who remembered him in his will), MacNeill acquired great technical and parliamentary experience in engineering matters. About the time of Telford's death (1834) MacNeill set up as a consulting engineer, with offices in Whitehall Place, London, and in Glasgow, where for a short time he was in partnership with Thomas Thompson, C.E. He constructed the Wishaw and Coltness railway and other small lines in Scotland, and conducted a series of important experiments in canal-boat traction, suggested by the swift boats carrying sixty passengers and drawn by two horses at the rate of eight miles an hour, placed by Walter Hunter [q. v.] on the Forth and Clyde canal. The experiments were published in 'Transactions of Institute of Civil Engineers,' London, vol. i. (1836). In 1837 MacNeill made known his system of 'sectio-planography,' whereby the heights of all embankments, depths of all cuttings, width of land required, and the necessary gradients were shown at one view. The system was adopted for railway plans by the standing orders of the House of Commons. A new system of nomenclature introduced by him, in which slopes (clivities) were distinguished as 'acclivities' and 'declivities,' has now found adoption. When the Irish railway commission began work, MacNeill was entrusted with the surveys of the north of Ireland. He at that time resided with his wife and young family at Mount Pleasant, where he introduced lime works on the Scottish model, with many improvements, and was thus enabled to redeem much unproductive land in the neighbourhood, from which for some years he obtained a large return. When Dr. Kane [see Kane, Sir Richard John] published a project for the establishment of a great technical school at Dublin, the council of Trinity College hurriedly decided, in 1842, to found a chair of civil engineering, to which MacNeill, lately made an honorary LL.D. of Trinity College, Dublin, was appointed. He held the appointment nominally until 1852, when he was succeeded by his assistant, Samuel Downing. The completion of the Dublin and Drogheda line of rauway, which had got into financial difficulties, was entrusted to him about 1843. He was knighted by Earl de Grey, then lord-lieutenant, on the completion of the first section to Kildare of the Great Southern and Western railway in 1844. During his later years MacNeill was blind, and withdrew from professional pursuits. For some years he lived in England, at Surbiton, and afterwards in Cromwell Road, South Kensington, where he died 2 March 1880.
MacNeill was married, and had two sons and two daughters. The sons, Torquil and Telford, predeceased their father (Torquil was the author of a project for supplying London with water from the Bagshot sand, which was printed in 1866). Of the two daughters, the younger, Grace, became the second wife of Major the Hon. Augustus ​Jocelyn, second son of Robert, second earl of Roden, and died in 1852.
MacNeill was tall and strikingly handsome. Although self-taught in technical and scientific subjects, he had a strong liking for exact science. He was a fellow of the Royal Society and other learned bodies, and a constant attendant at their meetings.
MacNeill was the author of the following works and papers: 1. 'Influence of Attraction on the Magnetic Needle' ('Quart. Journal of Science,' 1823, vol. xv.) 2. 'Tables for Computing Cubic Quantities of Earthwork in Cuttings for Canals, Railways, &c.,' London, 1833; a second edition of this useful work was printed on yellow toned paper, London, 1846. 3. 'Recent Canal Boat Experiments — Description and Tabulated Results of Experiments to ascertain the actual Traction-Power in drawing Canal Boats' ('Trans. Inst. Civ. Eng.' 1836, i. 237-82). 4. Translation of Navier's 'Means of Comparing the Advantages of different Lines of Railway,' London, 1836. He was patentee of 'A Method of preparing and applying Materials for making Roads more durable' (No. 5662, 6 May 1828); 'Making and Mending Roads' (No. 7077, 3 May 1836); the same (No. 7278, 11 Jan. 1837); 'Improvements in Locomotive Engines and Railways' (No. 12768, 6 Sept. 1849).
[Dod's Knightage, 1879; Engineer, 19 March 1880; Times, 5 March 1880; Brit. Mus. Cat. Printed Books; Cat. Scientific Papers; Official Lists of Patentees.]
H. M. C.