Griffin & Tatlock Quadrant Electrometer (ca. 1920s)
Early twentieth century quadrant electrometer manufactured by Griffin & Tatlock Ltd. of London England (ca. 19" high).
This example is remarkably completed, the suspension wire (not a quartz fiber), the mirror, and vane are all intact.
A small metal weight can be seen suspended at the end of a wire beneath the vane in the bottom compartment of the electrometer. Normally the weight is immersed in a solution of sulfuric acid inside the small glass Leyden at the bottom. The inside is lined with tin foil to shield the system from stray electrostatic charges.