184 • IEEE TRANSACTIONS ON EDUCATION. VOL. E-28. NO. 4. NOVEMBER 1985 From Computor to Electrical Engineer: The Remarkable Career of Edith Clarke JAMES E. BRITTAIN, SENIOR MEMBER, IEEE Abstract-Edith Clarke's electrical engineering career had as a cen­ the development of electronic computers beginning with tral theme the development and dissemination of mathematical meth­ the ENIAC that was introduced during the same year that ods that served to simplify and reduce the time spent on laborious cal­ culations in solving problems encountered in the design and operation she retired from General Electric. of large electrical power systems. As an engineer with the General Elec­ Clarke helped to develop and teach mathematical models tric Company from the early l920' s to 1945, she worked during a time that took advantage of such electromechanical aids as cal­ when power system analysis was evolving from being labor intensive to culating tables and alternating current network analyzers. being machine intensive, with much of the labor of problem solving In effect, she wrote what now would be called software being shifted from human computors, often women, to electromechan­ ical computers, such as the network analyzer and differential analyzer. for the machines that set the stage for electronic digital This trend culminated in the development of electronic computers be­ computers. She became highly skilled in the manipulation ginning with the ENIAC that was completed during the same year that of hyperbolic functions and symmetrical components, and she retired from GE. As a woman who worked in an environment tra­ was able frequently to simplify their use by preparing ditionally dominated by men, she demonstrated that women could per­ graphs and tables. Early in her career, she invented and form engineering analysis at least as well as men if given the opportu­ patented a graphical calculator for the solution of trans­ nity. Her achievements provided an inspiring example for the next generation of women with aspirations to seek a career in electrical en­ mission line problems. Her contributions made the "wom­ gineering. an's work" of unmechanized computing less necessary and, in the process, initiated the arduous task of opening INTRODUCTION the traditionally male-dominated electrical engineering DITH CLARKE (1883-1959) began her career as a culture to women. EComputer Assistant to a Research Engineer at the Am~rican Telephone and Telegraph Company. Eventually, EARLY LIFE AND EDUCATION she overcame formidable entry barriers to women and be­ Edith Clarke was born on February 10, 1883 and spent came a professional Electrical Engineer. She specialized her early years on a farm in Maryland near Ellicott City. in the analysis of electrical power systems and was em­ She was one of nine children of Jolfn R. Clarke, a lawyer­ ployed by the General Electric Company from the early farmer, and Susan Owings Clarke. In her early childhood, 1920's until her retirement in 1945. She then became a Edith Clarke suffered from what probably now would be Professor at the University of Texas where she taught until diagnosed ·as a "learning disability" in reading and spell­ her second retirement in 1956. Clarke was the.fi;st woman ing, but she exhibited a good aptitude for mathematics and to receive a degree in electrical engineering from the Mas­ enjoyed puzzles and card games, especially duplicate sachusetts Institute of Technology (MIT), Cambridge, and whist. Both her parents died by the time she was 12 and the first woman to present a technical paper before the an uncle served as her legal guardian. She attended a American Institute of Electrical Engineers (AIEE). boarding school in Montgomery County, MD, until 1899. Clarke directed much of her work as an engineer toward At the age of 18, she received a modest inheritance from the simplification and mechanization of laborious calcu­ the estate of her parents and decided to use it to continue lations encountered in the analysis of transmission lines her education. She enrolled at Vassar College in Pough­ and power systems. Somewhat ironically, her most impor­ keepsie, NY, a college that had opened in 1865 and that tant contributions to engineering analysis tended to reduce provided "the real impetus toward the full collegiate ed­ or eliminate the need for skilled human computors, an oc­ ucation of women" [.l]. At Vassar, she concentrated on cupation that had come to be regarded as suitable work for mathematics and astronomy, areas where the college al­ women at a time when engineering was not. During the ready had established a strong reputation. Many Vassar time spanned by Clarke's working career, power systems alumnae in the late 19th and early 20th centuries found analysis evolved from being labor intensive to being ma­ employment at observatories as computational assistants chine intensive, with much of the labor of problem solving to male astronomers [2] . being shifted from human computors, often women, to After receiving an A.B. q.egree from Vassar in 1908, electromechanical computers. This trend culminated in Clarke taught mathematics and physics for a year .at a school for girls in San Francisco, CA. She then taught Manuscript received July 16, 1985. The author is with the School of Social Sciences, Georgia Institute of mathematics for two years at Marshall College in Hun­ Te_chnology, Atlanta, GA 30332. tington, WV. She expressed her discontent at the pros- - 0018-9359/85/1100-0184$01.00 © 1985 IEEE l•. •' BR!TT.' IN: REMARKA3LE CAREER OF EDITH CLARKE 185 pects of a career as a mathematics teacher by enrolling as plify difficult concepts and mathematical methods and ex­ a sophomore in civil engineering at the University of Wis­ press them in terms that the average engineer could un­ consin in the fall of 1911 at age 28 [3]. derstand, a talent that Clarke also displayed as an engineer [7] . Bush came to MIT as a Professor in 1919 and achieved A COMPUTOR AT AT&T AND A STUDENT AT MIT a reputation for his skill in electrical analysis by After spending an enjoyable year as an undergraduate means of operational calculus and for developing the net­ engineering student, Clarke was hired for the summer as work analyzer and the differential analyzer, electrome­ a Computer Assistant to George A. Campbell (1870- chanical calculators of the type exploited by Clarke and 1954), an outstanding if somewhat reclusive Research En­ her colleagues during the 1930's [8] . gineer with AT&T. Clarke found the computing work suf­ ficiently interesting so that she abandoned her plan to re­ A COMPUTOR AT GE AND AN INVENTION turn to Wisconsin to complete the requirements for an Despite her newly acquired graduate degree, Clarke ex­ engineering degree. Campbell had been a Bell employee perienced difficulty finding employment ·as an engineer. since 1897 and already had played a major role in the de­ Again she became a computor, this time with the Turbine velopment of the loading coil, a major innovation in tele­ Engineering Department of the General Electric Company communication [4]. At the time Clarke was assigned to in Schenectady, NY. During the period from 1919 to 1921, work for Campbell, his efforts were directed to the anal­ she trained and directed a small team of women compu­ ysis of problems related to the use of vacuum-tube ampli­ tors in the calculation of mechanical stresses in high­ fiers on long distance telephone lines. The Bell Company speed turbine rotors. As in her earlier computing job at had embarked on a crash program to complete a transcon­ AT&T, the position with GE resulted from an anomalous tinental line from New York to California, to be opera­ situation that created a temporary need for skilled calcu­ tional in time for a planned celebration of the completion lators. The increasingly large turboalternator units man­ of the Panama Canal. Consequently, the telephone com­ ufactured by GE just prior to 1920 developed unantici­ pany was e;v.panding its research P.ffort on related innova­ pated problems caused by rotor vibrations and metal tions such as repeater amplifiers. Thus, the job opportu­ fatigue. In response, GE launched an intensive research nity for Clarke was in the context of this accelerated effort directed by C. E. Eveleth that involved the efforts of research program that provided work fo r several women several engineers and members of the GE Research Lab­ with credentials in mathematics [5] . oratory. The group carried out a program that included Clarke· s time as assistant to Campbell provided her with both experiments and theoretical analysis. The GE re­ an excellent apprenticeship in the mathematical theory of searchers developed a comprehensive theory of rotor vi­ transmission lines and electric circuits. Campbell was the brations and developed techniques to overcome the prob- ­ company's leading authority on these topics that involved lem at normal operating speeds. They disseminated their the manipulation of hyperbolic functions, equivalent cir­ findings in a number of technical papers published during l cuits, and graphical analysis, areas that Clarke pursued for 1924-1925 [9]. I the rest of her career. Among the computational tasks as­ In June 1921, Clarke filed a patent application describ­ l signed to her was to calculate the first seven terms of an ing her invention of a graphical calculator to be used in infinite series that represented a probability function. An­ the solution of transmission line problems. The invention other woman computor, Sallie E. Pero, extended the series probably was based on her earlier work at AT&T or as a to eleven terms while Lucy Whitaker used a different student at MIT. Since she was not a salaried engineer, she method to provide an independent check of the work done was not required to assign the patent rights to GE.