table-clamping vertical globe electrical machine - gearbox
Datecirca 1770
Inventory NumberDW0508a
ClassificationElectrical Machine
Subject
Maker
Edward Nairne
1726 - 1806
Cultural Region
Place of Origin
Dimensionsfully assembled: 51 x 27 x 11 cm (20 1/16 x 10 5/8 x 4 5/16 in.)
gearbox and crank: 11 x 27 x 33.7 cm (4 5/16 x 10 5/8 x 13 1/4 in.)
arm: 31 x 5 x 2 cm (12 3/16 x 1 15/16 x 13/16 in.)
gearbox and crank: 11 x 27 x 33.7 cm (4 5/16 x 10 5/8 x 13 1/4 in.)
arm: 31 x 5 x 2 cm (12 3/16 x 1 15/16 x 13/16 in.)
Material
Accessoriesglass globe (DW0508c) stored separately.
DescriptionTable-mounted brass gearbox (DW0508a) with worm gear drive and large external crank that would turn vertical glass globe (separate -- DW0508c). Separate slender brass arm holding a leather pad (DW0508b) clips to the side of the gearbox and lightly rubs surface of glass globe.
Crank axle is in the shape of a chess queen, handle is rounded and made of wood, and metal lever is simply sculpted. The axle that connects to the globe is flared at the bottom. The brass gearbox is square with a semicircular protrusion on one side for the gear housing. On the other side of the box from the protrusion is a spherical button that, when pressed, releases a latch and opens the door to the gearbox. The gear assembly consists of a circular gear with slanted, curved teeth meshing with the teeth of a cylindrical gear which turns the axle. This is the worm gear drive. The circular gear is mounted on one of two columns in the box.
The arm is made of thin brass with a hole at the top for a screw that attaches to the leather-lined rectangular strip. The bottom of the arm is forked and inserts into two slots toward the front of the box. Between the slots is a thicker arm with two screws in it that are used to adjust the distance of the sheepskin to the globe.
The assemblage is mounted to the table with a clamp that extends down from one side of the gearbox and under the table. A screw with a bone-shaped head is used to tighten the clamp.
Crank axle is in the shape of a chess queen, handle is rounded and made of wood, and metal lever is simply sculpted. The axle that connects to the globe is flared at the bottom. The brass gearbox is square with a semicircular protrusion on one side for the gear housing. On the other side of the box from the protrusion is a spherical button that, when pressed, releases a latch and opens the door to the gearbox. The gear assembly consists of a circular gear with slanted, curved teeth meshing with the teeth of a cylindrical gear which turns the axle. This is the worm gear drive. The circular gear is mounted on one of two columns in the box.
The arm is made of thin brass with a hole at the top for a screw that attaches to the leather-lined rectangular strip. The bottom of the arm is forked and inserts into two slots toward the front of the box. Between the slots is a thicker arm with two screws in it that are used to adjust the distance of the sheepskin to the globe.
The assemblage is mounted to the table with a clamp that extends down from one side of the gearbox and under the table. A screw with a bone-shaped head is used to tighten the clamp.
Signedin cursive on side of gearbox: Nairne London
FunctionContact between two different substances facilitates an electrostatic charge. Because the surfaces are usually rough, there is less contact, and therefore less charge transfer, than if the surfaces were completely smooth. Rubbing the two substances together facilitates a greater buildup of charge. Nonconductors are better at holding the charge.
The leather is pressed against the globe (stored separately) by tightening the screws against the bottom of the arm. The globe is turned by the crank, which turns the wormgear assembly which turns the globe. If the globe is evacuated, it begins to glow as it builds up charge.
The leather is pressed against the globe (stored separately) by tightening the screws against the bottom of the arm. The globe is turned by the crank, which turns the wormgear assembly which turns the globe. If the globe is evacuated, it begins to glow as it builds up charge.
ProvenanceDavid Wheatland purchased from Saul Moskowitz (Historical Technology, Inc.), Marblehead, Massachusetts, December 2, 1976. Donated to CHSI 1985.
Edward Nairne
Date: circa 1770
Accessories: glass globe (DW0508c) stored separately.
Object number: DW0508b
Charles Chardin
Date: 1870-1900
Accessories: key; mahogany case
Object number: DW0829
Department of Physics, Harvard University
Date: mid 20th-late 20th Century
Accessories: variety of spare parts cataloged as 2004-1-0408c-g
Object number: 2004-1-0408a
French
Date: circa 1880
Accessories: protecting case with glass window
Object number: DW0095
Parent/Child
