Chart of the Atlantic Ocean
Williams, Jonathan (1750-1815)
1799

Published in Thermometrical Navigation... etc. by Robert Aitken (1734-1802), who was born in Scotland and moved to Philadelphia in 1769. There he became a bookseller, printer and engraver.

Jonathan Williams' great uncle was Benjamin Franklin the first person to popularize the temperature observations in and adjacent to the waters of the Gulf Stream. He also made observations about the color of the water and its differences in conjunction with the temperature changes. Jonathan Williams continued the temperature measurements and recorded them on this chart, the original of which was only 5 1/4" X 8 3/4". The image, however, included the west coasts of Europe and northern Africa and the temperature recordings extended east of the Gulf Stream (as shown here). Arrows show the routes going south of the Azores and on to Bermuda.

This map is quite rare.