Accession No

3089

Brief Description

universal equinoctial helio-chronometer, English, 1/4 20th C

Origin

England

Maker

Class

dials

Earliest Date

1900

Latest Date

1925

Inscription Date

Material

metal (oxidised brass, white metal); glass; paper

Dimensions

length 114mm; breadth 99mm; thickness 37mm (thickness 57mm; 3-2-2000)

Special Collection

Steward collection

Provenance

Collection purchased from member of the Steward family, 1974.

Inscription

Description Notes

Oxidised brass case with 3 levelling screws and pair of bubble levels set into the base. Inset compass with engraved paper card; 16-point rose; 32 lettered points; degree scale divided 0 - 90˚ - 0 - 90˚ - 0, numbered by 10˚, divided to 1˚. (Needle stop mechanism (?); 3-2-2000). Latitude arc divided 0 - 90˚, numbered by 10˚, divided to 1˚. Watch dial face divided I - XII, numbered by I, divided to 1 minute, with hour, minute and second hands running from knurled key via multi-train gears (not working?; 3-2-2000). Rod gnomon.

Condition: fair (part of glass broken off inside; hands not working?); complete.

References

Events

Description
Chronometers are very accurate clocks which were taken on board ship as a means to find longitude. A ‘Two Day’ chronometer is one that must be wound every two days.

The chronometer is set to show time at the port of departure, and during the voyage is compared with the ship’s local time as given by the sun. The earth rotates around its axis – 360° in longitude – every 24 hours, or 15° every hour. Thus a difference of four minutes between the time shown by the chronometer and local time by the sun is equal to a change of 1° of longitude.

04/08/2008
Created by: Dr Anita McConnell on 04/08/2008

FM:43557