This file contains 55 letters and postcards from Joseph Needham and Lu Gwei-Djen to Ho Peng-Yoke and 1 copy letter and 1 postcard from Ho Peng-Yoke to Joseph Needham. These letters relate to the gunpowder sub-section of Science and Civilisation in China Volume 5 Part 1, proposed meetings, and the future Directorship of the Needham Research Institute.