The rate of transfer of energy to the vortex-wake pattern is calculated for isolated thin airfoils and cascades of thin airfoils in unsteady flow. This part of the work parallels earlier investigations by Garrick (7) and Keller (1). Application is made to the elementary two-row stages treated in an investigation (2) of the induction effects due to relative motion of the blade rows. The results show that the energy transferred to the wake pattern is a small fraction of the work absorbed by the rotor. Cross-induced contributions for a two-row stage may be negative but are small. By far the greatest contribution to the wake energy is that due to the circulation fluctuations induced in a blade row by the relative motion of the adjacent downstream row.