  We present a kinematic proof that the Andoyer variables in rigid body
dynamics are canonical. This proof is based on the approach of "virtual
rotations" by H. Andoyer. The difference from the original proof by Andoyer is
that we do not assume that the fixed in body frame is the frame of principal
moments of inertia, and do not use explicit formulas for the kinetic energy of
the body that include moments of inertia.
