  We report the observation a continuous rotation of the polarization in
Mn$_{0.95}$Co$_{0.05}$WO$_{4}$ under magnetic field. At zero field, this
compound shows a transition into the spiral magnetic and ferroelectric phase at
12.2K, which is the ground state, with the polarization oriented along the
b-axis. Increasing b-axis magnetic fields rotate the ferroelectric polarization
continuously toward the a-axis, indicating a rotation of the spin spiral plane.
This rotation extends over a large field and temperature range. At a constant
magnetic field of 3 Tesla, the polarization also rotates from the a-axis at the
ferroelectric transition toward the b-axis upon decreasing temperature.
