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Professor Bertram Hopkinson (1874-1918), mechanical and aeronautical engineer
1874 January 11th. Born at Woodlea, Birmingham, the eldest son of John Hopkinson (1849 - 1898), electrical engineer
1893 Read mathematics at Trinity College, Cambridge (1893–6)
1896 Entered the legal profession
1897 Called to the bar.
1898 On his father's death Bertram returned to engineering
By 1903 Had been elected to the Cambridge chair in mechanism and applied mechanics (a chair that his father had once refused). On 31 December he married Mariana Dulce Siemens, a distant cousin to the founders of the German firm of electrical engineers; they had seven daughters.
1910 elected FRS
1914 Became a professorial fellow of King's College, Cambridge.
WWI commissioned in the Royal Engineers. Applied his knowledge of explosions to various problems including the best form of bomb to be dropped from aircraft; the invention of a "blister" to be added to the hull of a ship, to absorb the energy of an exploding torpedo or mine.
1915 he was appointed to the Department of Military Aeronautics. He established an experimental station for the Royal Flying Corps at Orford Ness, and later at Martlesham Heath, where the testing of aircraft was under his control. Responsible for the development of bombs, guns, gunsights, and ammunition, and also the systematic study of night flying, and of navigation in clouds and bad weather.
1918 Died on a flight from Martlesham Heath to London.
1918 Obituary 
Colonel BERTRAM HOPKINSON, C.M.G., F.R.S., was born in Birmingham on 11th January 1874, the eldest and only surviving son of the late Dr. John Hopkinson, F.R.S., Member of Council, I.Mech.E., and grandson of the late Mr. Alderman John Hopkinson, M.I.Mech.E., of Manchester.
He was educated at St. Paul's School and at King's College, London, and then proceeded to Trinity College, Cambridge. Owing to illness he took an aegrotat degree in the first part of the Mathematical Tripos of 1895 but in the following year he obtained a first class in the first division of Part II. He then read for the Bar and was called in 1897.
After the death of his father, through the tragic accident in Switzerland in 1898, which occurred while Bertram was on his way to Australia on legal business, he determined to give up his career at the Bar and to take up engineering to conserve his father's large practice as a consulting engineer, and joined his uncle Mr. Charles Hopkinson, M.I.Mech.E., and the late Mr. E. Talbot, a former assistant of Dr. John Hopkinson, as a partner in the firm of Hopkinsons and Talbot, of London and Manchester.
During his five years association with the firm he was jointly responsible for the electrification and extension of the Newcastle-on-Tyne Tramway system, described in a Paper before the Inst.C.E., and of the Leeds Tramway system; and also advised upon or carried out electric lighting or tramway schemes for the Corporations of Salford, Stockport, and Crewe, and the District Councils of Sale, Hindley, and Ambleside. During this time he was also frequently engaged as an expert in patent cases in the Law Courts. The position he attained in work of this character was recognized in later life by his frequently acting as assessor to the Judge in technical cases.
In 1903 Professor Ewing (now Sir J. Alfred Ewing, K.C.B.) retired from the Chair of Mechanism and Applied Mechanics in the University of Cambridge, and Bertram Hopkinson was appointed his successor, and held the Chair until his death. Under his guidance the Cambridge School of Engineering grew in numbers and prospered, and greatly extended its influence and repute, particularly as a home of advanced research. Professor Hopkinson was himself devoted to research and inspired his students with something of his own enthusiasm and originality, many of whom subsequently came to occupy positions of importance and responsibility in engineering industries.
His researches were very varied in character, and the papers he communicated to scientific societies and the technical institutions very numerous. They were all characterized by great originality, refusal to be bound by traditional methods and doctrines, directness of attack and a singular appreciation of the essential points involved.
He contributed to this Institution a series of Papers on "Indicated Power and Mechanical Efficiency of Gas-Engines," 1907; "Effect of Mixture Strength and Scavenging upon Thermal Efficiency," 1908; "Cooling of Gas Engines," 1913, and was awarded the Willans Premium for the first two of these.
Professor Hopkinson was co-inventor of the Hopkinson-Tring torsion meter, now largely used for measuring the shaft power of turbine-driven ships.
On the outbreak of war he threw himself unreservedly into the National Service, disregarding all other interests which would interfere therewith. He was then a Major of the O.T.C. at Cambridge.
First he took up R.E. work at Chatham, but a little later became attached to the Admiralty, where his work on explosions found full application and enabled him to undertake further work of great national importance. Afterwards he directed his attention to the equipment of air-craft, and was appointed to positions of successively increasing importance in connexion with the control of experimental work, at first with the War Office and then with the Air Ministry, where he became Deputy Director of Air-Craft Equipment. Here again his knowledge of internal-combustion engines and explosives, and originality of conception, were of the greatest value to the Nation. To quote from a letter of condolence to the University of Cambridge written by command of the Air Council, they place "on record their deep sense of the high and permanent value of the work done for the Flying Force by the late Colonel Hopkinson, and their recognition of the patriotic self-abnegation with which he devoted his great abilities and scientific attainments to the Public Service."
He was made a Companion of the Order of St. Michael and St. George in 1917. He was a Fellow of the Royal Society and held a professorial fellowship at King's College, Cambridge. He became a Member of this Institution in 1904; he had served on the Council of the Institution of Electrical Engineers, and was a Member of the Council of the Royal Society, and of the Institution of Civil Engineers at the time of his death, and was an original member of the Advisory Council for Scientific and Industrial Research appointed by the Privy Council.
Colonel Hopkinson was killed in an accident whilst flying in England on military duty on 26th August 1918, at the age of forty-four.
1919 Obituary 
BERTRAM HOPKINSON, C.M.G., F.R.S., Lieut.-Colonel R.A.F., was killed while flying in discharge of his duties as Deputy Controller of the Technical Department of the Royal Air Force on the 26th August, 1918.
An authoritative and comprehensive account of Professor Hopkinson's life and work by Sir Alfred Ewing has been published recently in the Proceedings of the Royal Society (Series A, vol. 95, p. xxvi), consequently it is considered desirable that this notice should deal more particularly with Hopkinson's work in electrical engineering and his activities during the last four years. A brief sketch of his life is, however, necessary.
He was born in Birmingham 11th January, 1874, his father being John Hopkinson, F.R.S., the first and greatest of electrical engineers and some time President of the Institution.
After a brilliant career at St. Paul's School and Trinity College, Cambridge, ending in a first class in Part II of the Mathematical Tripos, Hopkinson was called to the Bar in 1897 and began to practise.
In August 1898 his father, with three of his children, was killed in climbing the Petite Dent de Veisivi. Bertram Hopkinson left the bar to carry on his father's consulting practice with Messrs. Charles Hopkinson & E. Talbot. This was a bold step, but Hopkinson had absorbed a good deal of engineering from his father, and he continued in practice till 1903, when he became Professor of "Mechanism and Applied Mechanics" in the University of Cambridge.
In the same year he married the eldest daughter of Mr. Alexander Siemens.
Practical patriotism is hereditary in the Hopkinson family; John Hopkinson was the first colonel of the Corps of Electrical Engineers, and his son, with the rank of Major (Territorial), commanded the Engineer Section of the Cambridge O.T.C. When the war fell upon us Hopkinson at once relinquished all other activities. He was instructor at Chatham, later was engaged on some wireless work at the Admiralty, was a member of various technical committees as they were formed, devised a means of protecting ships against torpedo attack, and finally settled down to the Flying Corps, at first in connection with bombs and bomb sights. The power of his personality and attainments was such that he rose from one position to another till at the time of his death he was Deputy Controller of the Technical side of the Air Force Equipment Branch, and the most influential man in all that concerned the development of air fighting on the Equipment and Experimental side.
He considered it his duty to learn to fly, though he was over 40 years old, and in this no doubt he was right. He used to claim that he could get about so much more quickly by flying that he could accomplish two or three times as much work as was possible without it, and in addition that it gave him a better standing with his staff.
In his youth Hopkinson had been a keen small-boat sailor, and he looked upon flying as a sort of improved boat-sailing. He was very fond of it, and soon ceased to be satisfied with what he called "a family bus." On the morning of the 26th August, 1918, the weather was threatening and the clouds low, but Hopkinson was anxious to get to London. He started in a Bristol Fighter from Martlesham Heath, but as he approached London the clouds got lower and it is supposed that he lost control in descending through them, and had not height enough to recover; he fell near Hainault Farm, and must have been killed instantly.
Hopkinson's first paper was mathematical and dealt with discontinuous fluid motion, but on joining his father's firm his attention was naturally directed to such matters as came before him professionally. Among the works in which the firm was engaged were:- Tramways at Leeds, Liverpool, Newcastle-on-Tyne, electric lighting of St. Helen's, electricity supply at Crewe, Sale, Faversham, and Ealing. In the work on the Newcastle tramways and the extension of the tramways at Leeds, Hopkinson found scope for all his energy. There were still some tramway problems to be tackled at the opening of the twentieth century, and Hopkinson experimented on tensions in overhead wires, earth leakage currents and their corrosion effects, and similar matters. A paper on electric tramways by the members of the firm in which these matters were dealt with was read at the Institution of Civil Engineers in November 1902, and gave rise to an interesting discussion.
Hopkinson was also very interested in the subject of the hunting of alternating-current motors, and read a paper on the subject (Proceedings of the Royal Society, 18th June, 1903). His mathematics, were still at his finger ends, and the subject suited his powers - like his father he preferred analytical methods - and this makes the paper unattractive to those (and they are in the majority) who are not facile mathematicians. However, this was followed by a paper on the same subject to the British Association (Electrician, I 903 vol. 51, p. 886) in which a more readable account of the matter is given, and this paper is perhaps the clearest statement of a rather complicated subject which is to be found anywhere. The work is interesting as the effect of resonance appears as a particular case only in a general treatment. The writer at all events has used it for many years whenever the subject, cropped up.
Hopkinson's active life at Cambridge extended from 1903 till the outbreak of the war, and of course his main work was in connection with the duties of his chair, but an immense amount of original work was carried out. This was on four main lines, gas engines, measurement of shaft horse-power, properties of steel - especially magnetic properties - and researches on the dynamical aspect of explosions. The researches on gas engines are extensive, and taken together cover most of the ground. The investigation is very thorough, from both the physical and engineering point of view; of particular interest was the discovery of the great influence of radiation on heat losses in the cylinder and the explanation of the fact - too familiar to all acquainted with gas engines - that if pre-ignition once occurs the tendency is for it to get worse rather than better.
The measurement of shaft horse-power led to a successful invention of a new horse-power indicator in corroboration with Mr. L. G. P. Thring.
It was, however, in the work on explosions that Hopkinson's characteristic powers may be said to be fully exhibited. The work is described in the Transactions of the Royal Society, Series A, vol. 213, p. 437, and in a lecture at the Royal Institution, 26th January, 1912, under the title "The pressure of a blow" (see also "The Effects of the Detonation of Guncotton: Proceedings of the North-East Coast Institution of Engineers and Shipbuilders, 1913-1914, vol. 30). Hopkinson's attention was no doubt attracted to the subject by the fine work "On the Longitudinal Impact of metal-rods with rounded ends" (Cambridge Philosophical Society, 1907, vol. 14, p. 257) by Mr. J. E. Sears - which itself was suggested by Hopkinson's previous work on the "Momentary stresses in metals" (Proceedings of the Royal Society, vol. 74). Of this work it must suffice to say that measurement of the momentum conferred on bodies by explosions taking place near them have of course often been measured and the time integral of the forces thus ascertained. The separation of the time from the pressure element, however, in such a manner that both could be inferred simultaneously had not hitherto been accomplished directly. The method invented by Hopkinson consisted in firing a charge of explosive near to one end of a steel bar suspended so that it lay horizontal; at the remote end of the bar similar pieces of steel of various lengths were held very lightly by magnetic forces. Under certain circumstances the free "pieces" flew off as a result of explosion and were caught in a ballistic pendulum. From a knowledge of the velocity of sound in the steel used and measurements of the momenta acquired both by the bar and the end piece, at all events the maximum pressure and duration of pressure at the face near the explosion can be deduced. It is obvious that a new and valuable method has been invented for comparing the effects of explosive charges, for instance, and full advantage of this was taken during the war. Important and original as was the work done at Cambridge, it really amounted only to an apprenticeship for what was to follow during the war.
Hopkinson's services to the country are not to be associated with any particular invention. They lay in his contribution to the building up of the greatest and most formidable air power in the world. In the struggle for aerial supremacy no one factor was more important than keeping the lead in technical equipment and air fighting tactics. This of course rested ultimately on experimental work, and it was the general organization and direction of this work which constituted Hopkinson's contributions to his country's victory. When he was first connected with the Air Force, experimental and training work were carried on together at one or two air stations, but by the establishment of the Experimental Station at Orfordness Hopkinson was able to bring a concentrated effort to bear on experiment unhampered by the exigencies of training. For this no one could have been more fitted either by nature or by training.
Tall, of a commanding presence, with immense physical strength and energy, with ripe engineering experience and great originality of mind, of a perfect and unruffled kindliness and serenity, he commanded respect and confidence in all those who worked with him. His character was in keeping with the external attributes of manliness, without a trace of self-seeking, without a thought that was not directed to the country's good, obviously ready to make any personal sacrifice, and as obviously of a strong, independent, and fearless personality, he was born to command, and command he did. The war has brought to light a great reserve of nobility and talent in the nation, but no more conspicuous example is to be found than in the life and work of- Bertram Hopkinson.
He was elected an Associate of the Institution in 1897 and a Member in 1902, and served on the Council from 1914 to 1916.