Major James Rennell's diary, or the 'Journal of Major James Rennell (1764-67)', is an invaluable document of the geographical and social history of Bengal. From 1764, when he was appointed as the Surveyor General of Bengal, for the next three years, the precise descriptions he provided of Bengal's rivers, basins, and topography added a new dimension to contemporary research. This book does not merely highlight the technical aspects of map-making, but rather captures a detailed picture of the social system of rural Bengal at the time, the hostile weather conditions, and the early administrative period of the East India Company. From Rennell's writings, we learn how he surveyed the basins of the Ganges and Brahmaputra with immense courage, which eventually earned him recognition as the 'Father of Indian Geography.'