While Benjamin Franklin was still the deputy postmaster general for the colonies in America, he received many complaints about the longer time it took to get mail to the colonies. Franklin had a cousin that was a whaling captain, and he put the questions to him. The cousin responded that it was a warm ocean current that flowed away from the Americas toward Britain. This was the beginning of Franklin's interest in the subject and one that he made observations on during his many trips between the continents. They measured water temperatures at varying depths and charted out the results. This map is the result of his efforts and shows the American coast, and the situation of the Gulf Stream as well as an inset that shows gyre as it circulates around the Atlantic, specifically through the UK , and back toward the coastal US.
This map is commonly referred to as the first chart of the Gulf Stream. A rare map that shows the river in the ocean. Complete with the American Philosophical Society text from which it is derived.
Condition is very good, with light offsetting (exaggerated by our photos). The text is complete without boards and light foxing throughout. Image size is approximately 8.5 x 14 (inches)