Antique Harris-Style Gold-Leaf Electroscope

Early 20th century Harris-Style gold leaf electroscope.  A fine single leaf electroscope used to demonstrate electrostatic charge. Mahogany housing with lacquered brass components, Bakelite insulator, and gold-leaf indicator. A pristine, custom build. Unsigned, English made. 

First invented by Abraham Bennet in 1786, this Harris-style electroscope is more sensitive and advanced in comparison to the older pith-ball style electroscope. The device works using a fixed horizontal brass rod and a vertical rod holding a gold leaf. The vertical rod has a long-ribbed insulator surrounding it, this insulation helps to keep the static charge on the metal rod as it travels from the terminal to the gold leaf, with a Bakelite insulator.

 When a charged object is brought close to touch the terminal of the brass rod on the top of the instrument, the charge is transferred from the charge object to the metal rod. This charge causes the gold leaf to then repel away from the rod. The angle or distance the leaf spreads from its vertical position is proportional to the amount of charge from the object. As the charge builds, the gold leaf will stray further away from the stationary rod.

The side-mounted resistor, labeled 'Dumetohm Holder' & 'Dumetohm 1.0 MΩ Patents Pending' are there to help control electrical discharge, it provides a slow path for the charge to leave, allowing the gold leaf to gradually return to its vertical stationary position. 

Similar Model Featured at The University of Leeds.

Dubilier Condenser Featured in The Science Museum Group. 

Overall Dimensions: 14.00" x 9.25" x 4.00"

Weight: 3 lbs. 3 oz.