Detailed chart of the north half of Koh Sichang Island, Thailand.

The chart shows not only considerable maritime information, including soundings, banks, rocks, and other hazards of the sea, but also much topographical information, such as heights of mountains, forests, plantations, houses, roads, and telegraph lines.

The chart is the work of Captain Alfred John Loftus (1834-1899), merchant seaman and hydrographer to the King of Siam. As merchant seaman, he regularly commander ships plying their trade between England and the Far East. For several years he operated out of Singapore. In 1870, whilst sailing in the South China Seas, his ship was "captured and burnt by pirates on the coast of Hainin and I lost all - all I had in the world; I had not a dollar at my disposal." Having survived the ordeal he managed to take command of steamship Viscaount Canning, which he sailed to Siam, and there entered into the the Siam Navy, as chief hydrographer, a position he would hold until 1891. In the post he was responsible for not only surveying the coasts and, but also the rivers, telegraph lines, and railways.

The chart bears the stamp of the Hartwig & Co., Singapore, a publisher's and stationers active at the end of the nineteenth century.

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.