Hendrik Johannes van der Bijl, physicist and industrialist, was the son of Pieter Gerhard van der Bijl, a grain and produce merchant, and his wife Hester Elisabeth, born Groenewald. During the Anglo-Boer War (1899-1902) the family moved from Pretoria to Gordon's Bay in the Cape Colony. Hendrik received his secondary schooling at the Boys' High School, Franschhoek, and matriculated through the University of the Cape of Good Hope in 1905. He spent the next three years as a student at Victoria College, Stellenbosch (later the University of Stellenbosch), qualifying (again through the University of the Cape of Good Hope) as Bachelor of Arts (BA) with honours in physics in 1908. He also won the Van der Horst prize as the most meritorious student in mathematics and physics. During his student days, in 1907, he presented a paper before the Victoria College Scientific Society on "Universality of the law of gravitation." The next year he proceeded to Germany for further studies. He first spent a semester at the University of Halle where he studied philosophy and inorganic chemistry. He then moved to the University of Leipzig, where he spent three years of intensive research on the nature and behaviour of the ions produced by a strong radium source in liquid dielectrics such as hexane and carbon disulphide. Concentrating on the ionization of pure liquids he extended to liquids the methods which Sir William Thomson had applied to gases. For this work he was awarded his PhD degree in March 1912, with a thesis entitled Das Verhalten ionisierter flüssiger Dielelektrika beim Durchgang electrischer ströme. He was then appointed as assistant in physics at the Royal School of Technology in Dresden under Professor Wilhelm Hallwachs, a pioneer investigator of the photo-electric effect, who directed him to evaluate the sources of error in the determinations of the velocity of emission of photoelectrons. This investigation was successfully completed and published in the Verhandlungen der Deutschen Physikalishen Gesellschaft in 1913.
At that time Van der Bijl was offered an appointment in the just established research organization of the American Telephone and Telegraph Company (which in 1925 became the famous Bell Telephone Laboratories). He moved to the United States, accepted the offer and started work in September 1913. During the next seven years he was mainly involved in studying the performance of the recently patented thermionic valve and in adapting its design for various applications and for commercial production, work for which he was ideally equipped by his research in Dresden. He showed that the behaviour of the thermionic valve could be described in a now well-known fundamental equation. With this equation, and his experimental finding that the amplification factor of the valve is a parameter that depends only on its structural arrangement, he laid the foundations for the future design and development of the three-electrode valve to function either as, among others, an amplifier or as a detector of high frequency currents. His work on the design and theory of the thermionic valve was published in the form of a landmark paper, "Theory and operation characteristics of the thermionic amplifier", in the Proceedings of the Institute of Radio Engineers (1918) and more fully in The thermionic vacuum tube and its applications in 1920 - the first book on the subject and a standard work for many years. He also published various other scientific papers, contributed to the development of the cathode ray oscilloscope and other devices, and delivered a series of lectures on thermionics at the University of Chicago.
As a researcher van der Bijl was a hard worker who concentrated on his research problem with single minded purpose and great attention to details. He gave little indication of his future breadth of vision and management skills. His years in the United States brought him into contact with modern industrial methods and led him to publish a paper on "Scientific research and industrial development" in 1919. In this paper he advocated the development of secondary industry in South Africa. The next year General J. C. Smuts*, then prime minister of South Africa, offered him an appointment as scientific and industrial advisor on industrial development in the Department of Mines and Industries. He returned to South Africa in 1920 to take up this post. He reported directly to Prime Minister Smuts, which caused some friction with the established civil servants. Early on he applied his expertise to evaluate two proposals to link South Africa with other countries in the British Empire by means of either long wave or short wave radio telegraphy. He also considered ways and means to produce high-power tubes for radio transmitters. However, his first major achievement, suggested to him by Smuts, was the drafting (in collaboration with Sir Robert Kotzé*) of the Electricity Act No. 42 of 1922 and the creation of the Electricity Supply Commission (Escom), a non-profit public utility company. Escom was to supply electrical power to the whole of South Africa, but particularly for industrial use and for electric traction on the railways. He remained its chairman from 1922 to his death in 1948.
Van der Bijl's next major contribution to industrial development, with the assistance of C. F. Delfos*, was the creation of the South African Iron and Steel Corporation (Iscor), based on Act No. 11 of 1928. The venture met with considerable opposition at the time and during its early years, among others because steel could be imported cheaply during the depression years of the early nineteen-thirties. However, despite problems with the supply of raw materials and a shortage of adequately trained staff the enterprise proved successful in the end. Van der Bijl headed the Corporation from its creation in 1925 until his death. He spent much of his time for many years studying Iscor's technical problems and visiting overseas steel plants.
His next industrial enterprise was the establishment of the Industrial Development Corporation, again a public utility company funded by the government, to provide financial and technical assistance to industrial ventures with sound prospects but a lack of capital or in need of technical guidance. It was created in 1940, based on the Industrial Development Act No. 22 of 1940, and he was its first chairman from October 1940 to November 1944.
During World War II (1939-1945) van der Bijl was appointed director-general of war supplies, heading a government organization set up to arrange for the purchase or manufacture of all the requirements of the Department of Defence. This entailed the creation of a large buying organization and the exploitation of all of the country's sources of production. Under his leadership an efficient war supplies organization was developed in South Africa. At the end of 1942 he took over in addition the organization and supply of civilian goods and raw materials, and his designation changed to director-general of supplies. He relinquished control of both military and civilian supplies in September 1945.
After the war van der Bijl directed the expansion of Iscor's steel production by the creation of a new steelworks at present Vanderbijlpark, a town planned by him and named after him. He was also involved in the establishment of the Vanderbijl Engineering Works Corporation (Vecor) for the manufacture of heavy engineering equipment and assisted in establishing the African Metals Corporation (Amcor) to increase the exploitation and processing of metals. However, these projects were still incomplete when he became ill with cancer and died in 1948. His work in industry left him little time to pursue his scientific interests, but his wide interests included radio communication, improved farming methods and merchant shipping. For example, he published "A brief sketch of the development of radio telephony" in the Transactions of the South African Institute of Electrical Engineers in 1937. All his undertakings were characterized by his foresight and brilliant intellect.
Van der Bijl was elected a Fellow of the Royal Society in 1944, a fellow of the Royal Society of South Africa in 1927, a foreign associate of the National Academy of Sciences of the United States in 1943, and an honorary member of Het Koninklijk Instituut van Ingenieurs of the Netherlands in 1937. He served as vice-president of the Institute of Radio Engineers (1945), was president of the South African Institute of Electrical Engineers (1927), and was an honorary vice-president of the South African Forestry Association from 1938 to his death. He was awarded honorary degrees by the University of Stellenbosch (DSc, 1931) and the University of Cape Town (Ll D), served on the council of the Transvaal University College from 1921 and was chancellor of its successor, the University of Pretoria, from 1934 to his death.
In 1915 Van der Bijl married Florence Lisette Wagner, an American girl, but they had no children. In 1942, after the dissolution of his first marriage, he was married again, to Ethel Buxton, with whom he had a son and two daughters. He had considerable presence and dignity, a keen sense of humour, and a strong interest in the welfare of all who worked under him.
