The theoretical distribution of velocity across a liquid (Newtonian) between two coaxial cylinders and the velocity gradient at the inner cylinder is calculated in a new way. The equation used for calculating the coefficient of viscosity of the liquid is also given. The theory agrees with experiment for all values of &thgr;0/&fgr;0≤1/2 (where &thgr;0is the amplitude of deflection of the inner cylinder and &fgr;0is the amplitude of the oscillations inexorably imposed on the outer cylinder).