These logbooks record two voyages (to Corunna, Spain, 1789-1790, and to Oporto, Portugal, 1791, and returns to Philadelphia), with observations of differences in temperature between air and water, especially when passing the Gulf Stream or any land or banks.

Written from China to his family, the letters of James Bancker contain descriptions of the social life of the Americans and English in China, of Hong Kong after the British acquisition of that place, and of anti-British riots in Canton. A long letter describes the outward voyage from New York to Canton; several letters given an account of a visit to the Philippines; and there is a partial journal of Bancker's return home through the Red Sea.

These letters and papers include ten small volumes of letterbooks (1752-1781), and ca. 100 pieces of correspondence with Joseph Shippen (1750-1778). Topics discussed are business in Philadelphia and Lancaster, provincial politics, army supply in the French and Indian War, land purchases and speculation, housebuilding, and family affairs.