Henley's Quadrant Electrometer
branch of study: electricity / electrostatics
inventor: William Henley, 1770
Henley's variation of a quadrant electrometer consists of an upright column with a brass stand. Attached to the column is a wire with an elder pith ball. If the instrument is charged, the ball will be repelled from the brass stand due to electrostatic forces. The magnitude of pepulsion can be read from a hemisphric scale.
The instrument was developed by William Henley and supposedly the first of its kind.