An appliance for measuring viscosity. It consists of a copper funnel, about 30 cm long with a 15-cm diameter at the top, that has a 10-mesh screen over half its diameter to remove debris and a 6-mm-diameter exit tube at the bottom through which the rate of flow is timed. It takes 26 s for a quart of clean water to flow through and correspondingly longer for muds of greater viscosity. Gel strength is measured by comparing the rate of flow of freshly agitated mud with that of mud that has been allowed to remain quiescent for 10 min.