It has been shown that the sign and magnitude, of the Weissenberg effect in a viscoelastic liquid depends on the method of observation, namely, through the shape of the free surface or through the height difference of radial tappings. The Oldroyd A and the Walters A′ fluids display the negative Weissenberg effect as far as the free surface is concerned, but they display the positive effect in radial tappings. The Oldroyd B as well as the Walters B′ fluid display identical positive effect in both types of observations. The second order fluid displays the positive effect in radial tappings, but may display either effect when the free surface is observed.