1. Compilation drawing; 2. Enamel zinc plate; 3. Lithographic zinc plate; 4. Printed chart. All for Admiralty Chart 1446, Aberdeen Harbour

Here is shown the sequence of charts and plates that go into the production of an Admiralty chart today. The hydrographic Department of the Admiralty, established in 1795, is responsible for the collection of the information and the production of the finished chart.

Formerly after the Fair Chart was obtained a copper engraving was made of it and the published charts obtained direct from this engraved copper plate; this was a very laborious process.

Lithographic processes were later used, originally the copy of the chart on the engraved copper plate was transferred to Bavarian Limestone, and later still, from 1925, zinc plates were used instead of the limestone plates.

Today the copper plate is seldom used, the enamel zinc plate is used instead, and the copy of the chart is transferred from it to the lithographic zinc plate which is then used in a rotary offset printing machine for printing the published chart.