This document describes an experimental observation of the evanescent wave phenomenon in a Smith-Purcell free-electron laser. The experiment used two different gratings and measured spectra at various electron beam energies between 26-34kV. It observed the evanescent wave directly and saw it radiate at the second harmonic, indicating electron beam bunching. Particle simulations also predicted this behavior of the evanescent wave growing anti-parallel to the electron beam and scattering harmonics off the grating.