Description

MICHELL’S PATENT VISCOMETER, English / Australian, c. 1920, signed on the lid including the UK patent number (117234). Contained in the 6-7/8″ (17 cm) wide fitted mahogany case is a hollow steel cylinder with hard rubber grip and lower weighted steel assembly with three tiny polished steel grasping “pads” arranged on a cup-like segment of a sphere. There is also a polished steel ball which mates to these pads, a 0 – 100° C. thermometer, and instruction sheet. The outfit is complete and in fine condition. To determine the viscosity of lubricating oils or other liquids, one places a couple of drops on the pads, and noting the temperature of the unit, presses the ball onto the pads, quickly inverts the assembly, and measures precisely the time required for the ball to drop free of the cup. That duration in seconds, divided by the constant of the instrument (engraved on its plaque), gives the true viscosity of the liquid in C.G.S. units. Patented in the UK in 1918, it is the invention of A.G.M. Michell of Melbourne.