An outer disk (1) is divided into 24 sectors representing the 24 hours of a day. A second smaller disk (2) is may be rotated on the outer disk about a common axis (3) and is divided into 24 time zones with indication of the Greenwich meridian (10) and the international date line (13). If the two disks are rotated to make the local time at a known time zone coincide, the local time and universal time for any other time zone is indicated An Independent claim is also included for : Utilisation of the instrument in offices, aircraft and boats
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