The Paper describes a method for calculating the path followed by a pile, conductor or string of sounding rods as they are driven or jacked into the ground. The path is shown to depend on the initial lack of straightness, eccentricity in the driving mechanism and asymmetric failure of the soil at the toe, Experience indicates that the induced curvatures can be significant, and in such cases conventional beam-column theory much be replaced by a more general theory for the torsional/flexural behaviour of thin rods due to Kirchoff, Using this in conjunction with conventional subgrade reaction theory, the path taken can be calculated and the stresses determined, The method is applied to a cone penetrometer which deviates from the vertical during pushing.