The reversible transverse susceptibility χt of a ferromagnet having a positive uniaxial anisotropy has been measured as a function of the applied magnetic field. The presence of peaks in the χt (H) curve of a polycrystal was predicted by theoretical calculations based on the Stoner and Wohlfarth model [A. Aharoni, E. M. Frei, S. Shtrikman, and D. Treves, Bull. Res. Counc. Isr. A 6, 215 (1957)]. Unlike previous measurements, our data verify the predictions of such a theory. An explanation for the failure of previous attempts to detect the peaks in the χt (H) curve is given. It is also experimentally shown that the χt (H) measurement allows a precise determination of both coercive and anisotropy fields in a uniaxial ferromagnet provided it is made by single domain particles.