Glossary · Regulation

Chronometer rate book

A record of comparisons used to follow a chronometer’s error over time.

Explanation

A rate book can preserve comparison dates, instrument identity, reference time and the evolution of error. Its evidential value depends on those fields and on the conventions used by the writer. Distinguish copied observations from later calculated averages. A daily rate derived from two observations is the change in error divided by elapsed days; it does not reveal every variation between those endpoints. Retain original units, blank entries, corrections and uncertainty, and do not infer naval service from a rating table without provenance.

Diagram

Schematic: chronometer rate record. Rate-book schematic: each entry is an observation record. It should be cited as documentary evidence, not converted into an unsupported performance claim.

Photographic reference

E. Barthet No. 10 — gimballed box, L2015-3496 — © The Board of Trustees of the Science Museum / Science Museum Group / The Clockmakers’ Museum, CC BY-NC-SA 4.0 as stated by source; commercial-use permission review pending. Official museum or publication source

E. Barthet No. 10 — dial and canister — © The Board of Trustees of the Science Museum / Science Museum Group / The Clockmakers’ Museum, CC BY-NC-SA 4.0 as stated by source; commercial-use permission review pending. Official museum or publication source

E. Barthet No. 10 — exposed movement — © The Board of Trustees of the Science Museum / Science Museum Group / The Clockmakers’ Museum, CC BY-NC-SA 4.0 as stated by source; commercial-use permission review pending. Official museum or publication source

E. Barthet No. 10, L2015-3496: exact chronometer context, not evidence of a recorded rate or a lunar-distance observation.

Held photographic references

The Chronometer Rate Book - Maritime Printing - Ship Log Books and Ship ... — maritimeprinting.com, Rights unverified — web image search result, review pending. Web page (maritimeprinting.com)

E. Barthet No. 10, L2015-3496: exact chronometer context, not evidence of a recorded rate or a lunar-distance observation.

Cross-references

Nearby regulation terms

Chronometer correction: The signed adjustment applied to an indicated chronometer reading.
Chronometer rate: The known daily rate of a marine chronometer.
Compensation balance: A balance wheel designed to counteract the effects of temperature changes.
Concentric hairspring: A hairspring whose coils are centered on the axis of the balance.
Crown positions: Vertical timing positions named by crown orientation.