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Admiralty chart
Admiralty charts are nautical charts issued by the United Kingdom Hydrographic Office (UKHO) and subject to Crown Copyright. Over 3,500 Standard Nautical Charts (SNCs) and 14,000 Electronic Navigational Charts (ENCs) are available with the Admiralty portfolio offering the widest official coverage of international shipping routes and ports, in varying detail.
Admiralty charts have been produced by UKHO for over 200 years, with the primary aim of saving and protecting lives at sea. The core market for these charts includes over 40,000 defence and merchant ships globally. Today, their products are used by over 90% of ships trading internationally.
The British admiralty charts are compiled, drawn and issued by the Hydrographic Office. This department of the Admiralty was established under Earl Spencer by an order in council in 1795, consisting of the Hydrographer, Alexander Dalrymple, one assistant and a draughtsman. The initial remit was to organise the charts and information in the office, and to make it available to His Majesty's ships.
The Hydrographic Department began printing charts in 1800, with the acquisition of its first printing press. Initially charts were produced only for use by the Navy, but in 1821, Thomas Hurd, who had succeeded Dalrymple as Hydrographer in 1808, persuaded the Admiralty to allow sales to the public. The first catalogue of Admiralty charts was published in 1825, and listed 756 charts.
Charts were printed from copper plates. Plates were engraved, in reverse, with a burin. The plate was inked, and the excess ink wiped from the flat surface before printing, so that ink remained only in the engraved lines (intaglio printing). The process allowed very fine detail to be printed, but was slow. When corrections or alterations were needed to a chart, the copper was hammered from behind, the raised section scraped and smoothed, and the new information engraved on the smoothed area. This allowed plates to continue in use for long periods, in some cases for over a hundred years.
Charts often showed a great deal of detail of features on land as well as sea. Depths were shown by individual soundings while hills and mountains were shown by hatch marks. Printing was in black and white, but some charts were hand-coloured, either to emphasise water depth or terrain, or to indicate specific features such as lighthouses.
Experiments were made with the use of lithography from the 1820s, but results were not entirely satisfactory. Lithography was less expensive, and some charts were printed in this way, but printing from copper plates continued to be the main method into the 20th-Century, and in both cases from flat-bed printing machines. The most common chart size was early established as the "Double-elephant", about 39 X 25.5 inches, and this has continued to be the case. Chart design gradually simplified over the years, with less detail on land, focusing on features visible to the mariner. Contours were increasingly used for hills instead of hatching.
All printing of Admiralty charts was carried out in England until the first World War. In 1915, the survey ship HMS Endeavour was sent to support the Gallipoli campaign, and carried printing equipment so that charts from her surveys could be rapidly made available to the fleet. In 1938 trials were made with the rotary offset process, using a zinc plate copied from the copper original. These were successful, and by the outbreak of World War II all chart production used this process, which was faster, and reduced wear and tear on the copper original. This development was crucial in meeting the increased wartime demand for charts. During World War II the distribution of printing facilities was on a much larger scale than previously. There was also concern about the safety of the original printing plates in the event of air raids, and high quality baryta paper proofs were made as backups.
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Admiralty chart
Admiralty charts are nautical charts issued by the United Kingdom Hydrographic Office (UKHO) and subject to Crown Copyright. Over 3,500 Standard Nautical Charts (SNCs) and 14,000 Electronic Navigational Charts (ENCs) are available with the Admiralty portfolio offering the widest official coverage of international shipping routes and ports, in varying detail.
Admiralty charts have been produced by UKHO for over 200 years, with the primary aim of saving and protecting lives at sea. The core market for these charts includes over 40,000 defence and merchant ships globally. Today, their products are used by over 90% of ships trading internationally.
The British admiralty charts are compiled, drawn and issued by the Hydrographic Office. This department of the Admiralty was established under Earl Spencer by an order in council in 1795, consisting of the Hydrographer, Alexander Dalrymple, one assistant and a draughtsman. The initial remit was to organise the charts and information in the office, and to make it available to His Majesty's ships.
The Hydrographic Department began printing charts in 1800, with the acquisition of its first printing press. Initially charts were produced only for use by the Navy, but in 1821, Thomas Hurd, who had succeeded Dalrymple as Hydrographer in 1808, persuaded the Admiralty to allow sales to the public. The first catalogue of Admiralty charts was published in 1825, and listed 756 charts.
Charts were printed from copper plates. Plates were engraved, in reverse, with a burin. The plate was inked, and the excess ink wiped from the flat surface before printing, so that ink remained only in the engraved lines (intaglio printing). The process allowed very fine detail to be printed, but was slow. When corrections or alterations were needed to a chart, the copper was hammered from behind, the raised section scraped and smoothed, and the new information engraved on the smoothed area. This allowed plates to continue in use for long periods, in some cases for over a hundred years.
Charts often showed a great deal of detail of features on land as well as sea. Depths were shown by individual soundings while hills and mountains were shown by hatch marks. Printing was in black and white, but some charts were hand-coloured, either to emphasise water depth or terrain, or to indicate specific features such as lighthouses.
Experiments were made with the use of lithography from the 1820s, but results were not entirely satisfactory. Lithography was less expensive, and some charts were printed in this way, but printing from copper plates continued to be the main method into the 20th-Century, and in both cases from flat-bed printing machines. The most common chart size was early established as the "Double-elephant", about 39 X 25.5 inches, and this has continued to be the case. Chart design gradually simplified over the years, with less detail on land, focusing on features visible to the mariner. Contours were increasingly used for hills instead of hatching.
All printing of Admiralty charts was carried out in England until the first World War. In 1915, the survey ship HMS Endeavour was sent to support the Gallipoli campaign, and carried printing equipment so that charts from her surveys could be rapidly made available to the fleet. In 1938 trials were made with the rotary offset process, using a zinc plate copied from the copper original. These were successful, and by the outbreak of World War II all chart production used this process, which was faster, and reduced wear and tear on the copper original. This development was crucial in meeting the increased wartime demand for charts. During World War II the distribution of printing facilities was on a much larger scale than previously. There was also concern about the safety of the original printing plates in the event of air raids, and high quality baryta paper proofs were made as backups.
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