Anomalous mechanical effects caused by a plane TE-polarized wave on an infinite perfectly conducting cylinder with an axial slit have recently been discovered. These effects occur when quasi-eigenvibrations are excited in a closed cylinder, and show up as a resonance-type increase in the ponderomotive force directed opposite to the axial slit. In this paper the authors report results of a calculation of the ponderomotive force for relative waave numbers k alpha less than equivalent to 2 pi , i. e. , lambda greater than equivalent to alpha , where a// alpha is the radius of curvature of the open spherical screen.