gold leaf electroscope pair
Date: circa 1850
Inventory Number: DW0780
Classification: Electroscope
Dimensions:10.5 × 18.7 × 13.5 cm (4 1/8 × 7 3/8 × 5 5/16 in.)
DescriptionTwo identical, elegant electroscopes. Each consists of a fine brass housing with an arched top, with four drop-shaped little feet and an insulated, helmet-shaped brass cap ending in a ball on top. The front and back of each electroscope is in glass, but can be covered entirely with perfectly fitting brass plates.
Both sides of each instrument are identical: directly behind the glass is a fine metal sheet semicircle covering the upper half of the instrument except for a round hole near the top where the glass is etched with a cross-sight. Directly below the edge of the semicircular metal sheet the glass is etched with fine graduations that would meet at the cross-sight. Their scale has a zero at the center and goes up to 3 on both sides.
Apparently, both instruments are missing their gold leaves, which would hang from the top inside.
A metal column passes through each instrument from top to bottom right at its center, ending in an adjustable brass screw below.
The electroscopes are stored in their original, elegant wooden box with leather straps purple velvet lining.
Signedunsigned
Inscribedfinely engraved on one electroscope: Schlagintweit 55
finely engraved on other electroscope: Schlagintweit 56
brass covers marked with "a","b","c" and "e" letters to help setting them up properly
FunctionGold leaf electroscopes indicate the amount of electric charge on an object that is put in contact with them. Originally (missing in these instruments) two fine gold leaves would hang inside the instrument. As an object touches the instrument, the gold leaves acquire its electric charge and repel each other, making an angle. This angle is proportional to the amount of electric charge and can be determined with the graduations etched on the glass. The two identical sides of the instrument and cross-sight are probably meant to diminish parallax errors (errors caused by not looking from exactly in front of the instrument).
Historical AttributesThis instrument apparently was used during the Schlagintweit Expedition to Central Asia, 1854-58. In the field, the most likely use for this instrument would be for meteorology.
ProvenanceAcquired in Germany in 1959 along with other instruments from the Schlagintweit Expedition to Central Asia. (Object 17).