An analysis is presented of a plane turbulent far wake of an incompressible fluid with a modified expression for eddy viscosity. Considering the kinematic eddy viscosity is expressed as the time average of the product of the mixing length and the lateral fluctuation velocity, it is assumed that the latter varies laterally like its rms value, which has been measured, and is approximated by a power of the mean velocity defect. Suitable values of the exponent are inferred by applying the TOWNSEND's data.The semi-empirical formula obtained finally for the mean velocity defect is similar to the formula obtained by SCHLICHTING, but is free from any singularity, and is found to express the available experimental measurements rather well with some variation of the value of the exponent to each measurement.