Kennedy, Alexander Blackie William

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Kennedy, Alexander Blackie William

(b., Stepney, London, England, 17 March 1847; d. London, 1 November 1928)

kinematics of mechanisms, testing of materials and machines.

As a young man Kennedy contributed significantly to the kinematics of mechanisms, which is a theoretical treatment in machine design of relative displacements of machine members, and to laboratory testing of machines as a part of engineering training. The latter half of his life, from 1889, was devoted to engineering aspects of electric power systems.

The eldest son of John Kennedy, a Congregational minister, and the former Helen Blackie, Kennedy attended the City of London School and the School of Mines until age sixteen. Successively as apprentice, draftsman, and consultant, he was for ten years concerned with marine steam engine design and construction in their embryonic stages. From 1874 to 1889 he was professor of engineering at University College, London, where in 1878 he organized the first mechanical testing laboratory intended primarily for the instruction of undergraduate students. He was anxious to give students experience in the laboratory so that they might recognize the problems and importance of precise measurements and thus use critically the data tabulated in reports and handbooks. Also during his teaching career he published his English translation of Franz Reuleaux’s Theoretische Kinematik (1876). Ten years later he published his own textbook of kinematics, in which appeared Kennedy’s law of three centers, which is fundamental to kinematic analysis employing instantaneous centers.

In 1889 Kennedy turned from mechanical to electrical engineering. As consulting engineer, he quickly became a leading authority in the design and construction of electric generating and distribution systems for both domestic and railway service. He was responsible for the design of numerous systems installed in the principal British cities.

After 1900 Kennedy was a member of several government technical boards and commissions. In 1894 he was president of the Institution of Mechanical Engineers and of Section G (Engineering) of the British Association for the Advancement of Science and in 1906 president of the Institution of Civil Engineers; he was also a member of the Institution of Electrical Engineers. Kennedy was elected fellow of the Royal Society in 1887 and was knighted in 1905. He received honorary degrees from the universities of Glasgow (1894), Birmingham (1909), and Liverpool (1913). He was married in 1874 to Elizabeth Verralls, eldest daughter of William Smith of Edinburgh.

Throughout Kennedy’s life there was a consistent thread of controlled quantitative testing of materials and machines, apparently stemming from his conviction, stated obliquely when he was president of Section G of the British Association, that “the essence of science may be rightly summed up in [the] one word ‘measurement.’”


I. Original Works. Kennedy translated Franz Reuleaux’s Theoretische Kinematik as The Kinematics of Machinery: Outlines of a Theory of Machines (London, 1876; repr. New York, 1963). Among his writings are“The Use and Equipment of Engineering Laboratories,”in Minutes of Proceedings of the Institution of Civil Engineers, 88 , pt. 2 (1886–1887), 1–153, including over 70 pp. devoted to discussion of the paper; “Experiments Upon the Transmission of Power by Compressed Air in Paris,” in F. E. Idell, ed., Compressed Air (New York, 1892), pp. 7–52; and The Mechanics of Machinery (London, 1886; 4th ed., 1902).

II. Secondary Literature. See Dictionary of National Biography, 1922–1930, pp. 464–466. The best biographical sketch is Minutes of Proceedings of the Institution of Civil Engineers, 227 (1929), 269–275, which cites a number of minor papers and addresses. A portrait appears as the frontispiece in Minutes of Proceedings of the Institution of Civil Engineers, 167 (1907).

Eugene S. Ferguson

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Kennedy, Alexander Blackie William