More recent examination, notably by Richard Atkinson, has proved Hawkins largely wrong, as it is now established that the different features at the monument that he tried to incorporate into many of his alignment theories were in use at different times and could not have worked alone, the lateness of the installation of the Heel Stone being the final nail in the coffin. Furthermore, the 56-year period is not in fact a reliable method of predicting eclipses and it is now accepted that they never repeat their date and position over three consecutive 18.61 year-long lunar cycles. Hawkins' theories also required strict observance of the phases of the moon which further complicated predictions using his model.