A Falling-sphere Viscometer for use with Opaque Liquids

A method is described for indicating the passage of the sphere past the reference marks of a falling-sphere viscometer. The method applies to opaque liquids and depends on the alteration of the inductance of a coil as the steel sphere passes through it. Two coils are used for each reference mark. They are connected in a bridge circuit which is balanced when the sphere passes the reference mark. Indication is obtained from a phase-selective rectifier and meter.