The properties of screened plasma oscillations of the $d$ band, which Fr\"ohlich first suggested could lead to superconductivity, are investigated. Specific-heat anomalies in the normal and superconducting state, normal-state resistivities, pressure-induced and pressure-dependent superconductivity, M\"ossbauer-effect studies, lattice transformations, and the occurrence of superconductivity in transition metals are compared with the theory. These diverse properties indicate that the Fr\"ohlich mechanism is operative in high-${T}_{c}$ transition elements and constitutes a new mechanism for superconductivity.