When it was first printed in 1806, this very detailed chart of the eastern entrance to the Singapore Strait, was one of the earliest of Horsburgh's published charts. Showing the area from "Part of Sincapore Island" in the west to "Bintang Northeast Point", the chart is centered on the Pedro Branco, which would eventually be the location of an important lighthouse commemorating Horsburgh. Horsburgh knew these waters well, and the chart includes five panels of lengthy notes to help the wary sailor navigate them successfully: "To pass into the Great Inner Channel, between Romania Islands and the Reef, do not approach the latter nearer than the outer double line, or Transit of Pedro Branco and False Barbucit, till clear of the West end of the Reef marked A..."

This edition of the chart differs considerably from its first publication, with changes supplied by the surveys of Captain Daniel Ross (1780-1849). In 1807, Ross was tasked by the East India Company to survey the China Seas. He spent nine years surveying the coast between 1807 and 1816, and then spent a further four years charting the seas between 1816 and 1820. On his return to England in 1821 he was rewarded with a cash sum of £1,500 from the East India Company, for his tireless work out in the Far East. He would later appear before a government Select Committee investigating the possibilities of increasing Britain's trade with China.