This experiment investigated the wave properties(or motion) of electrons. They were accelerated through a cathode ray tube with varying potential, and passed through graphite unto a screen which by displaying concentric rings instead of a scatter reflecting an intuitive crystaline geometry with the separation increasing with potential (This would be the expectation of a particle motion through the lattice.), it in fact did the opposite,i.e. dispersed with voltage decrease. The experiment was consistent with theoretical expectation (Bragg,De Broglie).
The value given for the lattice spacing "d" became slightly more deviant from the accepted value most likely due to the lack of correction of curvature of the receiving surface from which the Poisson rings were measured. The first set of points were the closest match.