pedestal for Beall's compass deviascope
Date: 1900-1915
Inventory Number: DW0141b
Classification: Deviascope
Subject:
Maker: Henry Hughes & Son, Ltd. (1903 - 1947)
User: Institute of Geographical Exploration (1929 - 1952)
Cultural Region:
Place of Origin:
Dimensions:
assembled deviascope: 103 x 102.5 x 54 cm (40 9/16 x 40 3/8 x 21 1/4 in.)
storage box: 33 x 34 x 26.5 cm (13 x 13 3/8 x 10 7/16 in.)
Material:
wood,
Accessories: instruction manual for instrument is in box of disassembled parts.
Description:
DW0141b--the rectangular pedestal of ebonized wood for the compass deviascope. It supports the large pelorus and ship's deck model.
Signedunsigned
FunctionThe deviascope is a device that simulates the magnetic forces to which a compass is subjected on board an iron ship and shows how to cancel them out. It was used not just for illustrational purposes, but also for training navigators in using compasses onboard ships. They were questioned with it before getting their degrees and working on an actual ship. It was a standard examination tool for many seafaring-related institutions in the British Empire and several other countries.
The model consists of a pedestal that can hold the platform above in different angles and inclinations by a metallic arm. The platform represents the ship and has the compass close to its center. The many groves that extend radially from the compass are the places where one can position specially designed magnets to simulate or counterbalance the permanent magnetization of the ship. The small holder below the compass, the iron globes, and the square apertures below the platform with iron cylinders in it are all used to represent different components of the disturbances that a compass would be exposed to at sea.
An accessory called the pelorus or "dumb card," which stands behind the compass, is used to indicate the true direction of the ship.
The illustrator would place several magnets and iron objects in particular grooves and holders and show the effects that this had on the compass needle. An examiner would present a previously prepared arrangement to a student that would be required to ascertain the direction of the ship, which could include changing the direction and inclination of the platform (the ship) during the examination.
The model consists of a pedestal that can hold the platform above in different angles and inclinations by a metallic arm. The platform represents the ship and has the compass close to its center. The many groves that extend radially from the compass are the places where one can position specially designed magnets to simulate or counterbalance the permanent magnetization of the ship. The small holder below the compass, the iron globes, and the square apertures below the platform with iron cylinders in it are all used to represent different components of the disturbances that a compass would be exposed to at sea.
An accessory called the pelorus or "dumb card," which stands behind the compass, is used to indicate the true direction of the ship.
The illustrator would place several magnets and iron objects in particular grooves and holders and show the effects that this had on the compass needle. An examiner would present a previously prepared arrangement to a student that would be required to ascertain the direction of the ship, which could include changing the direction and inclination of the platform (the ship) during the examination.
Historical AttributesThe compass deviascope was first exhibited in 1886 and won a gold medal at the Liverpool Exhibition. It was a popular training tool for navigators until the early 20th century.
This example was purchased by David P. Wheatland in 1957 from the Geographic
This example was purchased by David P. Wheatland in 1957 from the Geographic
Curatorial RemarksStored in four parts--the deck and large pelorus; the pedestal; the iron rods; and a box containing the binnacle, small pelorus, cannon balls, and small magnets.
Primary SourcesGeorge Beall, I.S.O., F.R.G.S., Hand-Book to Beall's Compass Deviascope Together with a Few Explanatory and Practical Remarks on Magnetism and the Deviation of the Compass in Iron Ships, 4th ed. (London: J. D. Potter, Admiralty Agent for Charts, 1913).
ProvenanceInstitute of Geographical Exploration, Harvard University. Acquired by David Wheatland in 1957.
