Chart of the southern part of the Amazon Gulf.

The chart marks soundings, hazards of the sea, and the position of lighthouses (highlighted in red and yellow), with principal ports and rivers marked.

The surveying was carried out by the talented surveyor Lieutenant Louis-Francois-Marie de Tardy-Montravel (1811-1864) of the French Navy, whose survey of the northern coast of Brazilian in the 1840s became the benchmark for all subsequent surveys carried out in the nineteenth century. The British Admiralty first published this chart in 1853, some seven after Tardy Montravel completed his work. The present work has been updated to 1896. The inset shows the mouth of the River Guam in greater detail with the city of Para or Belém, to the right is a profile of the port.

The British Hydrographic Office was founded in 1795 by George III, who appointed Alexander Dalrymple as the first Hydrographer to the Admiralty. The first charts were produced in 1800. Unlike the U. S. Coast Survey the Hydrographic Office was given permission to sell charts to the public and they produced a great number of sea charts covering every corner of the globe. Most of the Admiralty charts produced by the Hydrographic Office delineated coastline as well as high and low water marks and record depth of water as established by soundings. In addition these charts included information on shoals, reefs, and other navigational hazards that plagued mariners across the world. Thanks to the innovations of Sir Francis Beaufort, who developed the Beaufort Scale of wind strength, the British Hydrographic Office became one of the leading producers of sea charts. In fact, such was their accuracy that the phrase 'Safe as an Admiralty Chart' was coined.