This paper is a report on an experimental investigation of the resistance to the uniform motion of a solid through a viscous liquid, the results of which appear to indicate that the liquid slipped on the surface of the solid. The apparatus was a straight, closed, glass tube containing a steel ball and the liquid being studied. The tube was arranged so that it could be inclined at various angles with the horizontal, and the only motion of the ball that was considered in working up the observations was one of pure rolling. The liquids employed were mixtures of glycerine and methyl alcohol. The analysis of the data is based upon Stokes' and Oseen's forms of Rayleigh's law of resistance, and the results of the investigation are interpreted in the light of theories due to A. B. Basset and to H. Brillie´.