Abstract: A viscometer wherein a sample of the material to be tested is introduced into the annular clearance between a stationary cylinder and a vertical shaft which carries several weights. As the shaft descends at a speed which is a function of the combined mass of weights and the viscosity of the sample in the clearance, successive weights are automatically detached from the shaft, either by piling up on top of each other after the lowermost weight comes to rest on a platform, or by being intercepted by plates which are mounted at different levels. Means is provided for centering the weights prior to start of a multi-stage test and for returning the shaft and the weights to starting positions upon completion of a multi-stage test.