Becher's pendulum artificial horizon
Datecirca 1850
Inventory Number5323
ClassificationArtificial Horizon
Subject
Maker
George Whitbread
fl. 1828 - 1877
Inventor
Alexander B. Becher
1796 - 1877
Cultural Region
Place of Origin
Dimensions12.3 × 16.5 × 7.3 cm (4 13/16 × 6 1/2 × 2 7/8 in.)
Material
Accessoriesarticle containing description and operating instruments (in instrument file)
Bibliography
DescriptionThis device consists of four main components:
a) A brass scope (4" long) with a glass lens at one end and ground glass at the other end that diffuses light entering from that direction. Inside the tube is the horizon bar, a metal vane that is magnified by the lens at the observer's end. A brass cover can slide to block the light on the ground glass end.
b) Pendulum, which attaches to the horizon vane, perpendicular to it.
c) Oil cistern in which the lower end of the pendulum is immersed to dampen its swings. It consists of two chambers that meet at approximately right angles.
d) a nautical lantern, painted black, with a corrugated hood and a horizontal brass tube to illuminate the ground glass side of the brass tube with the horizon bar.
Black metal arms connect the lamp to the oil tank and and the brass scope.
a) A brass scope (4" long) with a glass lens at one end and ground glass at the other end that diffuses light entering from that direction. Inside the tube is the horizon bar, a metal vane that is magnified by the lens at the observer's end. A brass cover can slide to block the light on the ground glass end.
b) Pendulum, which attaches to the horizon vane, perpendicular to it.
c) Oil cistern in which the lower end of the pendulum is immersed to dampen its swings. It consists of two chambers that meet at approximately right angles.
d) a nautical lantern, painted black, with a corrugated hood and a horizontal brass tube to illuminate the ground glass side of the brass tube with the horizon bar.
Black metal arms connect the lamp to the oil tank and and the brass scope.
Signedunsigned
Curatorial RemarksTo assemble: remove cap from the oil cistern, insert the pendulum and square post on cistern bracket in the socket on the tube mount. Insert lamp rod in the socket on the cistern.
FunctionBecher's artificial horizon is designed to replace the need of a clear view of the horizon when using a sextant, while maintaining a very similar experience.
The artificial horizon would be attached to a sextant in front of that instrument's line of sight to the horizon. The user would see a vane indicating the orientation of the sextant with respect to the horizontal, as a result of the vane being connected to a pendulum.
The pendulum is immersed in an oil cistern to dampen its swings, as it is required to point straight down.
The user can diminish the illumination of the inside of the tube by sliding the cover, or increase it by attaching the lamp.
The artificial horizon would be attached to a sextant in front of that instrument's line of sight to the horizon. The user would see a vane indicating the orientation of the sextant with respect to the horizontal, as a result of the vane being connected to a pendulum.
The pendulum is immersed in an oil cistern to dampen its swings, as it is required to point straight down.
The user can diminish the illumination of the inside of the tube by sliding the cover, or increase it by attaching the lamp.
American
Date: late 19th century
Accessories: mahogany box with brass hinges, handle, lock, hooks; iron bottle filled with mercury
Object number: 5257
L. Casella
Date: circa 1860
Accessories: two brass spirit levels on legs; mahogany case
Object number: 5255
American
Date: late 19th century
Accessories: mahogany box
Object number: 5325
George Whitbread
Date: 1828-1844
Accessories: Mahogany keystone box, telescopes (3), sight tube (1), adjustment tool, tube
Object number: 5307
L. Casella
Date: late 19th century
Accessories: brown leather case with belt and buckle closure
Object number: 5322
Zeiss-Aerotopograph
Date: circa 1950
Accessories: instrument is in original wood storage/carrying case. listed accessories: base plate, mirrors (2) and tubular holders (2), anchors (2), prism yoke, monocular adapter, lighting set with bulbs (3, one currently in lamp, its box in box of 2009-1-0002b), 2 monoculars (4 or 6 power) [6x24 (infinite) L or R Zeiss aerotopo logo), "fork"-shaped support (V rather), green filters (2) , dioptre lenses (2), strabismus-correcting lenses (2), photo holder, permanent magnets (8)
Object number: 2009-1-0002a
Benjamin Martin
Date: 1764
Accessories: small brass scope with brass and ivory holder.
Object number: 0007
Spencer, Browning, & Company
Date: 1843-1850
Accessories: box with key, adjustment tool, telescope, eye tube, eyepiece shade
Object number: 5248