Career
After teaching in the University of the Philippines, he became a professor at Caltech in 1923, remaining there until he retired in 1964 as professor emeritus. His research focused on "electromagnetic studies, the separation of isotopes, isolation of radioactive potassium and other elements, and the isotope ratio of oxygen." In 1926, Smythe was the first to propose ion-velocity spectrometers, which he eventually built with Josef Mattauch. He authored a textbook on electromagnetism called Static and Dynamic Electricity, which was a widely-used reference in the field during the 20th century.