gold leaf electroscope pair
Datecirca 1850
Inventory NumberDW0780
ClassificationElectroscope
Subject
Maker
German
Owner
Schlagintweit Brothers
1854 - 1858
Cultural Region
Dimensions10.5 × 18.7 × 13.5 cm (4 1/8 × 7 3/8 × 5 5/16 in.)
Material
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.
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
Curatorial RemarksAccording to the instrument's card, one plate is missing.
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).
ProvenanceDavid Wheatland purchased in 1959 (#17). Donated to CHSI April 4, 1986.
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.
M. Leyser
Date: circa 1858
Accessories: vertical leather carrying case; battery (DW0779b)
Object number: DW0779a
John Wilkes
Date: after 1804
Object number: 1998-1-1178
Wm Gaertner & Company
Date: circa 1920
Accessories: heavy metal stand (attached)
Object number: 0522
Henry Plympton
Date: circa 1835
Accessories: troy weights (1998-1-0038b); instruction manual (1998-1-0038c)
Object number: 1998-1-0038a
Benjamin Martin
Date: 1764
Accessories: small brass scope with brass and ivory holder.
Object number: 0007
Buff & Buff Manufacturing Company
Date: circa 1905
Accessories: wood case; leather case; right-angle prism; plumb bob; oil flask; tripod (5174b)
Object number: 5174a
John Frederick Newman
Date: circa 1835
Accessories: mahogany case with brass hinges and hooks
Object number: 5239
Legey
Date: circa 1838
Accessories: shades with double tabs (4); shades with single tab (4); screwdriver and square key.
Object number: 5268