The liquid is placed on horizontal plate and a shallow cone placed into it.  The angle between the surface of the cone and the plate is around 1–2 degrees but can vary depending on the types of tests being run.  Typically the plate is rotated and the torque on the cone measured.  A well-known version of this instrument is the Weissenberg rheogoniometer, in which the movement of the cone is resisted by a thin piece of metal which twists—known as a torsion bar.  The known response of the torsion bar and the degree of twist give the shear stress, while the rotational speed and cone dimensions give the shear rate.  In principle the Weissenberg rheogoniometer is an absolute method of measurement providing it is accurately set up.  Other instruments operating on this principle may be easier to use but require calibration with a known fluid.
Cone and plate rheometers can also be operated in an oscillating mode to measure elastic properties, or in combined rotational and oscillating modes.