An experimental facility is described which enables the power drawn by each of two impellers to be determined separately by means of strain gauges. In addition by using a flat-bottomed Perspex vessel in a square Perspex water jacket, good bulk flow visualisation is achieved. By means of a derotational prism and a TV camera, good pictures of flows relative to impeller blades are possible. Examples of the quality of pictures obtainable is given for a Rushton turbine and 45° pitch blade turbine in water and for a Rushton turbine in a pseudoplastic, viscoelastic C.M.C. solution.