A History of Linear Electric Motors by Eric R. Laithwaite

Abstract

TECHNOLOGY AND CULTURE Book Reviews 337 A History ofLinear Electric Motors. By Eric R. Laithwaite. San Francisco: San Francisco Press (Box 6800 94101), 1987. Pp. x + 389; illustra­ tions, references, bibliography, index. $30.00. Although Eric Faithwaite does not claim explicitly that his book is a contribution to the growing literature on nonverbal thought in invention and engineering design, I found it to be such—and a fascinating one. He combines an unusual topological interpretation of the history of rotary and linear electric machines with an intensely personal perspective on the recent history of linear motors and efforts to use them in high-speed ground transportation. He is professor of heavy electrical engineering at Imperial College, London, and is a leading authority on electromagnetic levitation, linear electric motors, and magnetic topology. Laithwaite reviews the history of electrical machines during what he terms the “first age of topology” from 1830 to around 1890. He includes a discussion of rotary versus linear motion and points out that every type of rotary motor has its linear counterpart. He uses three-dimensional topology to show that all 19th-century electric machines can be placed in one of six fundamental classes. He identifies the earliest reference to a linear motor as an 1841 patent issued to Charles Wheatstone, who had also developed the first known linear motor by 1845. The author discusses various applications of linear motors such as in liquid-metal pumps and stirrers and the remarkable “Electropult” tested by the Westinghouse Company in 1946. The latter was de­ signed to launch jet planes and was described as the world’s “longest induction motor” (p. 45). British engineers experimented with a linear motor that achieved a terminal velocity of 1,300 mph in supersonic tests reported in 1954. Laithwaite was introduced to linear motors when he tried to apply them to propel flying shuttles in the textile industry. He provides interesting insights into the inventive process, observing that “inven­ tion is seldom the cool, premeditated, clever process usually assumed by those who have never invented” (p. 70). He examines differences between science and engineering and the importance of “fringe subjects” in the history of engineering. He also treats the topic of “engineering fashion” and uses a “fashiongraph” to show how fashion and the like can determine the success or failure of a particular innovation (p. 88). He suggests that the emergence of a new fashion may serve to deplete the ranks of engineers in an old-fashioned held in a sort of brain-drain process. Thus electronics depleted the field of heavy electrical engineering and made more difficult the introduction of linear motors. He speculates on the basis of “our obsession for cylindrical geometry” that perhaps hindered acceptance of levitators 338 Book Reviews TECHNOLOGY AND CULTURE and linear motors. In a segment suggestive of Thomas Kuhn’s model applied to engineering, he considers the activities of “clean-up men” who follow pioneers into new areas “exploring every corner of it, classifying it, making it fit existing knowledge” (p. 113). In the final chapters, Laithwaite treats the “second age of topology” that began with the concept of transverse flux motors for use in high-speed transportation in 1969. Much of this segment deals with developmental activities at Tracked Hovercraft Limited, a British firm organized in 1967. During the project phase, the author and his colleagues introduced the “magnetic river” technique that combined levitation and propulsion. However, soon after a public demonstra­ tion of this system in May 1972, the British government decided to stop funding the project. The author argues that it was “political manoeuvring” rather than technological constraints that served to “play havoc” with transportation applications of linear motors after 1973 (p. 166). The book includes a fifty-page bibliography on linear motors and related topics. A History of Linear Electric Motors should be of interest to many historians of technology as well as scholars in technology policy. James E. Brittain Dr. Brittain (caches the history of technology at the Georgia Institute of Technol­ ogy ancl is chairman of the IEEE History Committee. Science and Corporate Strategy: DuPont and RLH), 1902— 1980. By David A. Hounshell and John Kenly Smith, Jr. New York: Cam...