It may be possible to find editions, states and printed amendments in Admiralty charts which are not represented elsewhere. Names of places and coastal features were sometimes recorded, some of which have since become obsolete.
Many of the charts have been amended and added to as a result of their use. Additionally, charts can accompany correspondence suggesting corrections or indicating errors. Besides full charts, our collection contains pieces of charts cut out to illustrate certain points. In the course of their duties, military and civilian personnel sometimes copied or traced charts.
British Admiralty Charts are continuously updated so that they remain accurate and useful, and obsolete charts are destroyed to prevent navigational hazards. A record of the survey and compilation dates was kept, as well as any correction dates. Charts were often corrected by making minor changes to the copper plates from which they were printed and publishing them again as a new edition; other times, charts were redrawn.
In the early days of the Hydrographic Office, Admiralty charts often drew on older surveys, which, in extreme cases, meant that some charts were based on surveys made over a century ago.
Using a geographical area or a place name to search
The following methods can be used to find Admiralty charts in our catalogue:
- Search by place names, rather than towns or other features, rather than broad search terms like “English Channel”
- Using the advanced search function, you can refine your search by date
As well as tracings and partial charts, these methods will also find records linked to charts that have been cataloged in detail.
In a four-volume published catalogue consisting of a Summary Catalogue and Supplementary Map Catalogue (card index), charts are listed alongside descriptions of other types of maps and are arranged topographically, making geographical searches relatively straightforward.
Using Admiralty chart numbers to search
The Map and Large Document Reading Room has a numerical card index to Admiralty charts. Our online catalog does not yet describe many charts. The following information is provided on each card:
- The chart’s geographic area is briefly explained
- The chart’s document reference
You should be aware though, that it does not contain:
- When the survey was conducted
- Publish or revise dates
- Chart, tracing, or copy details
First, the area covered on an admiralty chart was given a title. Charts have also been attributed a number since 1839, printed in the bottom right corner of each sheet, and this number is now considered to be the most important referential indicator. Prefixes and suffixes may be included in chart numbers.
As the Admiralty frequently reused chart numbers, make sure the area indicated on the index card corresponds to the area you’re looking for. Chart 483 was associated with a chart of St. Jago in the Cape Verde islands and Thursday Island in the Torres Straits west of Australia, and chart 695 with the Cook Straits and Madagascar at different times.
Under the header “Charts: Admiralty”, you can find a list of charts in the subject indexes of the Summary Calendar of Maps and Plans. Our card index and published catalogues do not yet include some of these charts.