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The Encyclopedia of Horology

Chronometer · Place not recorded

Decimal chronometer (tropometer)

Verified

The chronometer has a polished silver case and is fitted in a mahogany box reinforced with varnished brass on the corners.

Technical facts

Inventory number
MIH IV-83
Object type
Chronometer
Dating
c. 1901
Materials and techniques (catalogue wording)
Bois, Argent, Émail, Maillechort, Laiton
Dimensions (catalogue)
dimensions min/max: 71 x 80 mm; H: 60 mm L: 98 mm P: 123 mm (coffret); D: 59,8 mm E: 18 mm (chronomètre)
Inscriptions (catalogue)
Paul Ditisheim La Chaux-de-Fonds N° 16815 Grand Prix Paris 1900 (Boîtier); Tropomètre N° 16815 Paul Ditisheim Fabricant (Cadran); N° 16815 (Mouvement)

Historical significance

  • The chronometer has a polished silver case and is fitted in a mahogany box reinforced with varnished brass on the corners.
  • The white enamel dial is graduated according to the system of dividing a circle into four hundred degrees. The movement of the two central hands is calculated by one rotation for each quarter of the circle (one hundred degrees corresponds to one revolution of the hour hand and ten revolutions of the minute hand), with the milligrades being read on the exterior circle of the dial.
  • There are two small offset dials. The lower one indicates the milligrade (one revolution of the seconds hand corresponding to one hundred milligrades), and the upper one, divided into four hundred degrees, corresponds to the length of the day.
  • The movement has a spring detent escapement, a heavy bimetallic balance with gold weights and screws, and a cylindrical palladium balance spring fitted with an anti-tripping device.
  • This chronometer reflects the work carried out by the French navy around 1900 to extend the decimal system by applying the division of the quarter circle to navigation. The name tropometer is applied to this kind of chronometer because it measures the angle that the sun's average horary circle turns in relation to one meridian line on the earth.

Photographs

Decimal chronometer (tropometer) (MIH IV-83)
Decimal chronometer (tropometer) (MIH IV-83) — Musée international d'horlogerie, La Chaux-de-Fonds, Museum collection photograph, rights review pending. MIH collection record
Decimal chronometer (tropometer) (MIH IV-83)
Decimal chronometer (tropometer) (MIH IV-83) — Musée international d'horlogerie, La Chaux-de-Fonds, Museum collection photograph, rights review pending. MIH collection record
Decimal chronometer (tropometer) (MIH IV-83)
Decimal chronometer (tropometer) (MIH IV-83) — Musée international d'horlogerie, La Chaux-de-Fonds, Museum collection photograph, rights review pending. MIH collection record

Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.

Sources & references

  1. Musée international d'horlogerie, online collection record, inv. IV-83: https://collection.mih.ch/fr/collection/item/32887/

Where sources disagree, the disagreement is stated rather than resolved silently.