Small but accurately shaped prolate spheroids of ferromagnetic substances, almost uniformly magnetized by direct current in a large coaxial solenoid, are subjected to alternating axial applied magnetic fields produced by high frequency current in a smaller coaxial solenoid. Measurements of the impedance of this high frequency coil with a specially designed Maxwell bridge, give, as the driving frequency is varied through the frequency of mechanical resonance in the fundamental mode of longitudinal vibration of the center‐supported spheroid, precise data for analyzing the distribution of electromagnetic driving forces and of magnetic, electrical, and mechanical losses by a theory to be given elsewhere. Since the spheroid dimensions are about 10 millimeters for length and one millimeter for diameter, the resonant frequencies of interest are near 300 kilocycles per second. Optical measurements of vibration amplitude, possible in principle, have not yet been effectuated.