A mechanical model in the form of a gyroscope may be made to simulate the path of an electron in a uniform magnetic field acted upon by transverse electric fields. In using the model, one employs the following substitutions: The uniform magnetic field is replaced by the spin velocity of the gyroscope, the electric fields are replaced by magnetic fields which give the same field configuration, and the electron is replaced by one pole of a permanent magnet mounted on the axis of the gyroscope. The spin velocity may be arbitrarily chosen for convenient observation. Then, depending upon the value of the spin velocity, the dimensions of the gyroscope, the strength of the permanent magnet and the scale factor used in setting up the model, the strength of the magnetic field in the model is adjusted to correspond to the strength of the electric field in the actual case. The path described by the magnetic pole, under these conditions, corresponds to the actual path of the electron. Since the error involved in identifying the equations of motion of the gyroscope with those of the electron is of the order of θ2, where θ is the half‐angle of the cone through which the spin axis is allowed to move, the range of observations must be restricted accordingly. Some familiar structures for which electron paths have been observed and photographed are deflection plates in a uniform magnetic field, a diode in an axial magnetic field, and a split‐anode magnetron. By periodically reversing the current through the field magnets, it is possible to observe the effect of alternating electric fields. In one arrangement, in which the field was alternated in resonance with the revolution of the electron about the magnetic field lines, a path similar to that of charged particles in a cyclotron was obtained.