Proceedings of the Meeting on the History of Electrical Engineering

SUBJECT AREA: Electricity, Land transport, Railways and locomotives

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Davidson, son of an Aberdeen merchant, attended Marischal College, Aberdeen, between 1819 and 1822: his studies included mathematics, mechanics and chemistry. He subsequently joined his father's grocery business, which from time to time received enquiries for yeast: to meet these, Davidson began to manufacture yeast for sale and from that start built up a successful chemical manufacturing business with the emphasis on yeast and dyes. About 1837 he started to experiment first with electric batteries and then with motors. He invented a form of electromagnetic engine in which soft iron bars arranged on the periphery of a wooden cylinder, parallel to its axis, around which the cylinder could rotate, were attracted by fixed electromagnets. These were energized in turn by current controlled by a simple commutaring device. Electric current was produced by his batteries. His activities were brought to the attention of Michael Faraday and to the scientific world in general by a letter from Professor Forbes of King's College, Aberdeen. Davidson declined to patent his inventions, believing that all should be able freely to draw advantage from them, and in order to afford an opportunity for all interested parties to inspect them an exhibition was held at 36 Union Street, Aberdeen, in October 1840 to demonstrate his "apparatus actuated by electro-magnetic power". It included: a model locomotive carriage, large enough to carry two people, that ran on a railway; a turning lathe with tools for visitors to use; and a small printing machine. In the spring of 1842 he put on a similar exhibition in Edinburgh, this time including a sawmill. Davidson sought support from railway companies for further experiments and the construction of an electromagnetic locomotive; the Edinburgh exhibition successfully attracted the attention of the proprietors of the Edinburgh 585\& Glasgow Railway (E \& GR), whose line had been opened in February 1842. Davidson built a full-size locomotive incorporating his principle, apparently at the expense of the railway company. The locomotive weighed 7 tons: each of its two axles carried a cylinder upon which were fastened three iron bars, and four electromagnets were arranged in pairs on each side of the cylinders. The motors he used were reluctance motors, the power source being zinc-iron batteries. It was named Galvani and was demonstrated on the E \& GR that autumn, when it achieved a speed of 4 mph (6.4 km/h) while hauling a load of 6 tons over a distance of 1 1/2 miles (2.4 km); it was the first electric locomotive. Nevertheless, further support from the railway company was not forthcoming, although to some railway workers the locomotive seems to have appeared promising enough: they destroyed it in Luddite reaction. Davidson staged a further exhibition in London in 1843 without result and then, the cost of battery chemicals being high, ceased further experiments of this type. He survived long enough to see the electric railway become truly practicable in the 1880s.

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PJGR / GW

SUBJECT AREA: Electricity

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Although he developed dynamos for electroplating and lighting, Weston's major contribution to technology was his invention of a moving-coil voltmeter and the standard cell which bears his name. After some years as a medical student, during which he gained a knowledge of chemistry, he abandoned his studies. Emigrating to New York in 1870, he was employed by a manufacturer of photographic chemicals. There followed a period with an electroplating company during which he built his first dynamo. In 1877 some business associates financed a company to build these machines and, later, arc-lighting equipment. By 1882 the Weston Company had been absorbed into the United States Electric Lighting Company, which had a counterpart in Britain, the Maxim Weston Company. By the time Weston resigned from the company, in 1886, he had been granted 186 patents. He then began the work in which he made his greatest contribution, the science of electrical measurement.

The Weston meter, the first successful portable measuring instrument with a pivoted coil, was made in 1886. By careful arrangement of the magnet, coil and control springs, he achieved a design with a well-damped movement, which retained its calibration. These instruments were produced commercially on a large scale and the moving-coil principle was soon adopted by many manufacturers. In 1892 he invented manganin, an alloy with a small negative temperature coefficient, for use as resistances in his voltmeters.

The Weston standard cell was invented in 1892. Using his chemical knowledge he produced a cell, based on mercury and cadmium, which replaced the Clark cell as a voltage reference source. The Weston cell became the recognized standard at the International Conference on Electrical Units and Standards held in London in 1908.

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SUBJECT AREA: Electricity

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Kapp entered the Polytechnic School in Zurich in 1869 and gained a mechanical engineering diploma. He became a member of the engineering staff at the Vienna International Exhibition of 1873, and then spent some time in the Austrian navy before entering the service of Gwynne \& Co. of London, where he designed centrifugal pumps and gas exhausters. Kapp resolved to become an electrical engineer after a visit to the Paris Electrical Exhibition of 1881 and in the following year was appointed Manager of the Crompton Co. works at Chelmsford. There he developed and patented the dynamo with compound field winding. Also at that time, with Crompton, he patented electrical measuring instruments with over-saturated electromagnets. He became a naturalized British subject in 1881.

In 1886 Kapp's most influential paper was published. This described his concept of the magnetic circuit, providing for the first time a sound theoretical basis for dynamo design. The theory was also developed independently by J. Hopkinson. After commencing practice as a consulting engineer in 1884 he carried out design work on dynamos and also electricity-supply and -traction schemes in Germany, Italy, Norway, Russia and Switzerland. From 1891 to 1894 much of his time was spent designing a new generating station in Bristol, officially as Assistant to W.H. Preece. There followed an appointment in Germany as General Secretary of the Verband Deutscher Electrotechniker. For some years he edited the Electrotechnische Zeitschrift and was also a part-time lecturer at the Charlottenberg Technical High School in Berlin. In 1904 Kapp was invited to accept the new Chair of Electrical Engineering at the University of Birmingham, which he occupied until 1919. He was the author of several books on electrical machine and transformer design.

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SUBJECT AREA: Electronics and information technology, Public utilities, Telecommunications

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After education at King's College, London, in 1852 Preece entered the office of Edwin Clark with the intention of becoming a civil engineer, but graduate studies at the Royal Institution under Faraday fired his enthusiasm for things electrical. His earliest work, as connected with telegraphy and in particular its application for securing the safe working of railways; in 1853 he obtained an appointment with the Electric and National Telegraph Company. In 1856 he became Superintendent of that company's southern district, but four years later he moved to telegraph work with the London and South West Railway. From 1858 to 1862 he was also Engineer to the Channel Islands Telegraph Company. When the various telegraph companies in Britain were transferred to the State in 1870, Preece became a Divisional Engineer in the General Post Office (GPO). Promotion followed in 1877, when he was appointed Chief Electrician to the Post Office. One of the first specimens of Bell's telephone was brought to England by Preece and exhibited at the British Association meeting in 1877. From 1892 to 1899 he served as Engineer-in-Chief to the Post Office. During this time he made a number of important contributions to telegraphy, including the use of water as part of telegraph circuits across the Solent (1882) and the Bristol Channel (1888). He also discovered the existence of inductive effects between parallel wires, and with Fleming showed that a current (thermionic) flowed between the hot filament and a cold conductor in an incandescent lamp.

Preece was distinguished by his administrative ability, some scientific insight, considerable engineering intuition and immense energy. He held erroneous views about telephone transmission and, not accepting the work of Oliver Heaviside, made many errors when planning trunk circuits. Prior to the successful use of Hertzian waves for wireless communication Preece carried out experiments, often on a large scale, in attempts at wireless communication by inductive methods. These became of historic interest only when the work of Maxwell and Hertz was developed by Guglielmo Marconi. It is to Preece that credit should be given for encouraging Marconi in 1896 and collaborating with him in his early experimental work on radio telegraphy.

While still employed by the Post Office, Preece contributed to the development of numerous early public electricity schemes, acting as Consultant and often supervising their construction. At Worcester he was responsible for Britain's largest nineteenth-century public hydro-electric station. He received a knighthood on his retirement in 1899, after which he continued his consulting practice in association with his two sons and Major Philip Cardew. Preece contributed some 136 papers and printed lectures to scientific journals, ninety-nine during the period 1877 to 1894.

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GW / KF