Two new instruments are described for investigating the rheological properties of clay-water mixes. One involves the axial compression at constant rate of a cylindrical specimen between oiled parallel plates; the other subjects an extruded cylindrical rod to sinusoidal strains in torsion at frequencies in the range 0.01-0.16 c/s. In each case the response of the specimen is measured by the amount of deformation of an elastic element using a Philips displacement pick-up, and the results are recorded automatically on an X-Y recorder as load-compression or torque-deflection curves respectively.