Sir Marc Isambard Brunel (1769-1849), British inventor and engineer, was born at Hacqueville in Normandy on the 25th of April 1769. His father, a small landowner and farmer, intended him for the church, but his taste for mathematics and mechanics inclined him to another career, and he obtained a nomination for the navy, in which he served for six years. When his ship was paid off in 1792 and he returned to France, he found the Revolution at its height, and owing to his pronounced royalist opinions he was obliged to leave the country. Reaching New York in September 1793 he began to practise as an architect and civil engineer. His first employment was in land-surveying and canal-engineering. Later he submitted a highly ornamental design for the National Capitol at Washington, which, however, was not accepted, and was engaged to design and superintend the construction of the Bowery theatre, New York, burnt down in 1821. He fitted novel and ingenious machinery in the arsenal and cannon factory which he was commissioned to erect in New York, and he was asked to supply plans for the defences of the Narrows between the upper and lower bays of that port.

Early in 1799 he sailed for England in order to submit to the British government his plans for the mechanical production of ships' blocks, in substitution for the manual processes then employed. After the usual difficulties and delays his proposals were adopted, largely through the recommendation of Sir Samuel Bentham, and about 1803 the erection of his machines was begun at Portsmouth dockyard. They were constructed by Henry Maudslay, and formed one of the earliest examples of a complete range of machine tools, each performing its part in a long series of operations. Not only was the quality of the product much improved but the cost was greatly diminished, and the saving effected in the first year in which the machines were in full work was estimated at £24,000, of which about two-thirds was awarded to Brunel. A little later he was occupied in devising improved machines for sawing and bending timber, and in 1811 and 1812 he was employed by the government in erecting saw-mills at Woolwich and Chatham, carrying out at the latter dockyard a complete reorganization of the system for handling timber.

About 1812 he devised machinery for making boots which was adopted for the purposes of the army, but abandoned a few years later when, owing to the cessation of war, the demand became less and the supply of manual labour cheaper. At the same time he interested himself in the establishment of steam navigation on the Thames between London and Ramsgate. In 1814 he succeeded in persuading the admiralty to try steam-tugs for towing warships out to sea. The experiments were made at his own expense, for a few months after undertaking to contribute to the cost the admiralty revoked its promise on the ground that the attempt was "too chimerical to be seriously entertained." Another vain enterprise on which he wasted much time and money was an attempt to use liquefied gases as a source of motive power. His round stocking-frame or tricoteur was patented in 1816, and among his other inventions were machines for winding cotton-thread into balls, for copying drawings, for making small wooden boxes such as are used by druggists, and for the manufacture of nails, together with processes of preparing tinfoil for decorative purposes and improvements in stereotype plates for printing.

In 1821, partly as the result of the damage done by fire in 1814 to the saw-mills he owned at Battersea, and partly because his commercial abilities were far from equal to his mechanical genius, he got into financial difficulties and was thrown into prison for debt, only regaining his freedom through a grant of £5000 which his friends obtained for him from the government. Subsequently his attention was mainly devoted to projects of civil engineering, the most noteworthy being the Thames Tunnel. In 1820 he had prepared plans of bridges for erection in Rouen and St Petersburg and in the island of Bourbon. In 1823 he designed swing-bridges, and in 1826 floating landing-stages, for the port of Liverpool. A company, which was supported by the duke of Wellington, was formed in 1824 to carry out his scheme for boring a tunnel under the Thames between Wapping and Rotherhithe. The work was begun at the beginning of 1825, the excavation being accomplished by the aid of a "shield," which he had patented in 1818. Many difficulties were encountered. The river broke through the roof of the tunnel in 1827, and after a second irruption in 1828 work was discontinued for lack of funds.

Seven years later it was resumed with the aid of money advanced by the government, and after three more irruptions the tunnel was completed and opened in 1843. Aided by his son, Brunel displayed extraordinary skill and resource in the various emergencies with which he had to deal, but the anxiety broke down his health. He recovered sufficiently from one paralytic stroke to attend the opening ceremony, but he was able to undertake little more professional work. A second stroke followed in 1845, and four years later he died in London on the 12th of December 1849. He received the order of the Legion of Honour in 1829 and was knighted in 1841.

See Richard Beamish, Memoirs of Sir Marc Isambard Brunel (1862).