CHAPTER 3: WASHINGTON UNIVERSITY IN ST. LOUIS

The next and perhaps most significant chapter of Evans’ academic development took place at Washington University in St. Louis. This institution, rich with intellectual rigor and pioneering educators, was the proving ground where Evans honed his analytical abilities, built critical relationships, and encountered mentors who would shape his thinking for decades.

Among those mentors were three key professors: Alexander Langsdorf, Frank Bubb, and Roy Glasgow. These men were not just instructors; they were intellectual guides who introduced Evans to the nuances of engineering analysis, mathematical rigor, and practical problem-solving. They instilled in him a disciplined approach to thinking—one that would later manifest in his groundbreaking work in control systems. Fortunately, copies of letters he wrote to his professors, decades after graduation, elucidate the impact these men had on him in his own words. 

To Roy Glasgow, on the occasion of his retirement in 1966, he wrote,

“Dear Dean Glasgow. Fond memories provided by you are so numerous that I will have to limit this letter to those comments which triggered some key decisions in my life, or remarks that I have modified for various occasions. It is hard to believe now that, as a sophomore, I was planning on Engineering Administration. You advised that it would be better to prove myself as an engineer first and worry about the vice-presidency later. The choice at graduation was between GE and Wagner Electric. You advised me of the glowing comments from alums of GE's Advanced Course but warned about the tough entrance exam. Fortunately, the exam was loaded with your kind of problem (which had) set the hook on my liking to attack any problem to achieve as much of a solution as permitted by the initial conditions of knowledge and the time allowed to respond. The (1947 summer) job you set up at Emerson Electric set the stage for root locus by requiring a real working-over of the complex plane in trying to get the frequency response cult off their j axis.”

In a 1961 Evans letter to Dean Langsdorf, he shared what he learned through observation of other students. Evans had a keen interest in understanding how other people ticked throughout his life. Here are his observations.

“At Washington University I found that most students could memorize, something like the vector diagram of a synchronous machine …if the subject was repeated about three times. A basically simpler situation which was not specifically discussed, however, would lose most of them. 

A mid-semester quiz, in DC machinery … involved all dimensions of a motor being doubled. Several students said the test was "unfair" because we had not studied that. I personally learn most effectively by starting with simple examples and working up. Washington University was excellent in that professors such as yourself, Professor Glasgow, Dr. Bubb, or Dr. Middlemiss could and did take a student all the way back to the beginning if necessary and work up to the question at hand….I find that working with my children is a good testing ground for teaching methods because the subject matter is simple, the opportunities frequent, and the reaction clear.”

Frank Bubb was known for his innovative thinking and ability to challenge conventional methodologies. He encouraged students to look beyond textbook solutions and explore new ways of approaching engineering problems.

The relationships Evans forged with his professor went beyond the classroom. Their influence provided him with a foundation that he would later use to reshape the field of control engineering. Although not a straight-A student as Arline may have been, he earned more A’s in the majority of his classes, even English and History. Somewhat surprisingly, his lowest grades, gentlemen “C’s” were in two mechanical engineering classes.

At Washington University, Evans also met John R. Moore, a fellow student and intellectual peer who would become one of the most influential figures in his early career. Moore would later become a key collaborator and professional ally.

The 1930s and 1940s were a period of profound growth in the fields of engineering and mathematics. Universities like Washington University played a pivotal role in fostering the next generation of innovators. Evans’ time at Wash U coincided with a surge in research on servomechanisms, feedback control, and stability theory—topics that would later define his contributions.

While Root Locus was still years away from being formalized, the foundational elements were all present in Evans’ early life:

• Intellectual discipline, inherited from a family that      prized education.
• A network of influential mentors, who nurtured his engineering      abilities.
• A partnership with Arline, whose support provided      stability
• The analytical rigor of      Washington University, which taught him to think.
• John R. Moore, which would later influence his      professional trajectory.

Each of these elements was a root in its own right. Together, they nourished the intellectual ground from which Root Locus would eventually emerge.

By the time Walter Evans graduated from Washington University, he was not just an engineer—he was a thinker shaped by a rich lineage of scholars, strategists, and innovators. His early experiences in St. Louis provided him with the skills, relationships, and intellectual curiosity necessary to make groundbreaking contributions to control systems engineering.

Just as Root Locus would later provide engineers with a visual and intuitive way to understand system behavior, Evans’ own path was shaped by clear and distinct influences. His family, his mentors, his education, and his lifelong partnership with Arline were all essential elements of the equation. These were the roots of Root Locus—deep, interconnected, and essential to the innovation that would follow.

As Evans embarked on the next stage of his journey, he carried these influences with him. His story would soon move beyond St. Louis, but its foundation would always remain firmly rooted in the experiences, relationships, and institutions that had shaped his early years.