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The Encyclopedia of Horology

Archive · Washington, D.C., United States

US Naval Observatory

Records relating to time service and chronometer testing.

Overview

US Naval Observatory is a archive based in Washington, D.C., United States. Records relating to time service and chronometer testing.

As an archive, its value lies in documents rather than displayed objects: ledgers, registers, patents, correspondence, drawings or production records.

Production and sales ledgers can confirm when and to whom a specific numbered watch was delivered — evidence that marks on the object alone cannot give.

Diagram

12345let downstripcleanoilregulateorder of work; never skip letting down the mainspring
Schematic: order of work at the bench. An outline schematic drawn to show the arrangement of the parts discussed here. It is not a dimensioned working drawing and does not depict a particular maker's calibre.

Using it for research

  • Ask whether the archive issues extracts or certificates for individual serial numbers, and on what terms.
  • An extract confirms what the records state about the original object; it does not by itself prove that every part of a watch today is original.

Before you visit

  • Archives are usually accessible by written request or appointment only.