Ferraris's first publication was in March 1888, entitled Electrodynamic rotations produced by means of alternate currents. After expounding the geometric theory of the rotatory magnetic field, he suggested that a simple way of procuring the desired phase-currents would be to branch the circuit of an alternate current into two parts, into one of which should be inserted a resistance without self-induction, into the other a coil of much self-induction but of small resistance. The two windings of the motor should be respectively introduced into these two branches. The difference of phase thus produced would be sufficiently near to 90° to be effective. He expressed the opinion that in this way one might obtain all the effects that can be obtained by the rotation of a magnet. He then described the following experiments which were made in the autumn of 1885.