# Dictionary of National Biography, 1927 supplement/Hopkinson, Bertram

​HOPKINSON, BERTRAM (1874–1918), engineer and physicist, was born at Birmingham 11 January 1874. He was the eldest son of Dr. John Hopkinson, F.R.S. [q.v.], by his wife, Evelyn Oldenbourg, and inherited his father's combination of mathematical power with insight into physics, and with the ability to apply scientific ideas to practical problems. The family soon moved to London, and Bertram was educated at St. Paul's School, living at home in close association with his father, from whom he imbibed scientific habits of thought as well as much engineering knowledge. At the age of seventeen he went to Cambridge, entering Trinity College with a major scholarship. He missed the first part of the mathematical tripos through illness; in the final part he was placed in the first division of the first class. Soon after taking his degree (1895) he was called to the bar, but the tragic death of John Hopkinson in 1898 led Bertram to turn to engineering, in order to continue, so far as he could, his father's unfinished professional work. By 1903 he had acquired a considerable reputation as an engineer, and when, in that year, the chair of mechanism and applied mechanics at Cambridge became vacant, Hopkinson was selected to fill it. He held the professorship until his death fifteen years later. In 1903 he married Mariana, eldest daughter of Alexander Siemens, a former president of the Institution of Civil Engineers, and by her he had seven daughters.
As professor of mechanism, Hopkinson became responsible for the school of engineering at Cambridge, which, thanks to the establishment ten years earlier of a mechanical science tripos, was already vigorous. Under his management its progress was maintained, its numbers were doubled, and its position advanced both in the university and in the profession outside. Hopkinson was an effective teacher, with a passion for research which students found inspiring. A collected volume of his scientific papers, published by the Cambridge University Press in 1921, contains twenty-nine items and gives evidence of unflagging industry, originality of outlook, and ingenuity in devising methods of experiment. His chief investigations relate to the endurance of metals under varying stresses, the magnetic properties of iron and its alloys, the action of internal-combustion engines and the process of explosion in gases, and the pressure produced in the detonation of high explosives. His work is characterized by clear appreciation of practical issues, and by direct attack on the essential features of the problem in hand. He was elected F.R.S. in 1910 and became a professorial fellow of King's College, Cambridge, early in 1914.
On the outbreak of war in 1914, Hopkinson accepted a commission in the Royal Engineers. Use was soon found for his powers of experiment and design. In particular he was able to apply his previous study of explosions to the improvement of methods of attack and defence. His ‘pressure bar’ became a standard appliance for testing at Woolwich. His investigations determined the best form of bomb; other experiments, which he carried out for the Admiralty, led to the adoption of his invention for protecting ships of war by means of a projection or ‘blister’, so constructed as to absorb the energy of an exploding torpedo or mine without damage to the inner shell. For a time he was secretary of a committee set up by the Royal Society to advise the government on the scientific problems of the War, and he also took part in an organization for dealing with enemy cipher. Later he was appointed to the department of military aeronautics, where he was soon entrusted with the supply to aircraft of all items of ​their offensive armament. His experimental head-quarters were at Orfordness, and afterwards at Martlesham Heath where the testing of aeroplanes was put under his control. In order to carry out these duties to his satisfaction he found it was necessary to learn to fly, and very frequently took solitary flights to other air stations and to France. In one of these flights, in bad weather, he was killed by a fall near London 26 August 1918. Some months earlier he had been promoted colonel, and had received the C.M.G.
Apart from his scientific eminence, Hopkinson was a born leader of men, with a personality that was at once commanding and attractive, winning regard by his unselfishness, his fine temper, and his own constant enjoyment of work and of life.
[The Scientific Papers of Bertram Hopkinson, 1921; Proceedings of the Royal Society, vol. xcv, A, 1918–9 (portrait); Alpine Journal, vol. xxxii, no. 219; personal knowledge.]
J. A. E.