The Ear in the Wall by Arthur B. Reeve

This Halcyon Classic ebook is THE EAR IN THE WALL, a Craig Kennedy novel by American detective and mystery writer Arthur B. Reeve. Craig Kennedy is a scientific detective at Columbia University who uses his knowledge of chemistry and psychoanalysis to solve cases, and uses exotic devices in his work such as lie detectors, gyroscopes, and portable seismographs to uncover the truth.