Measurement of the local skin friction coefficient and re-examination of the Reynolds-number-effect on the mean flow quantities were made in a zero-pressure gradient, smooth wall, turbulent boundary layer. In order to do this fairly, the two-dimensionality of the flow field was carefully adjusted. And, the wall shear stress τ_ω was determined by direct measurement using a floating element device. The Reynolds number based on the momentum thickness R_θ=U₁θ / ν ranges from 840 to 6 220. The present experimental results of c_f propose a new empirical formula which well represents the present experimental data and confirms that the Karman constant χ=0.41, which implies a slope of the logarithmic linear layer, is independent of R_θ down to R_θ=860, whereas the additive constant varies with R_θ. The magnitude of the wake parameter takes an asymptotic value of 0.62 if the Reynolds number is sufficiently high. The effect of R_θ on all the turbulent intensities is evident even within the viscous sublayer. The constant stress layer does exist in the Reynolds shear stress profiles despite that the constant value varies with R_θ.