An 18th-century Gulf Stream chart, with a Ben Franklin connection

Jonathan Williams, [Untitled map of the Atlantic Ocean and Gulf Stream.] [Philadelphia, 1793.]

A scarce and interesting 1793 chart depicting the Gulf Stream, as well as thermometric observations of the Atlantic made on several trans-Atlantic voyages by Jonathan Williams, Jr.

A grand-nephew of Benjamin Franklin, Williams (1750-1815) served as his personal secretary during Franklin’s time as American agent in England in the early 1770s and as ambassador to France during the Revolution. He later served the U.S. Army as a senior military engineer, overseeing the fortification of New York Harbor and eventually becoming the first superintendent of the Military Academy at West Point.

This chart accompanied an article by Williams, that appeared in 1793 in the third volume of the Transactions of The American Philosophical Society. There he explains how his hydrographic interests developed during his time with his uncle, who made regular thermometric observations during his trans-Atlantic voyages and was one of the first Americans to describe the Gulf Stream.

“In the months of August and September, 1785 I was a fellow passenger with the late Doctor Franklin from Europe to America, and made, under his direction, the experiments mentioned in his description of the course of the gulph stream, an account of which was annexed to his maritime observations, and published in the Philosophical Transactions Vol. II. Page 328, I then determined to repeat these experiments in my future voyages.” (pp. 82-83)

Williams’ core finding is that the water temperature tends to decline as one approached banks or shoals… if confirmed, certainly a useful finding for mariners. From this he infers that “by noticing the changes in the heat of the sea water, a navigator might always know when he is in soundings, and thereby be able to escape the dangers arising from unexpected currents, and erroneous reckoning.” (ibid.)

Per Wheat and Brun this is the first state of the chart, though a friend has brought to my attention the existence of an earlier state, lacking the binding instructions above the upper neat line. Wheat and Brun identify a “second” state (i.e., the third) with the shading for the Gulf Stream extended and directional arrows added, appeared in Thermometrical Navigation (Philadelphia, 1799), a revised version of Williams’ earlier article in the Transactions.

Wheat and Brun, Maps and Charts Published in America before 1800, #724. Background on early American Gulf Stream research may be found in Louis de Vorsey, “Pioneer Charting of the Gulf Stream,” Imago Mundi no. 28 (1976), pp. 105-120.


Some light foxing, one fold reinforced on verso, and a few tiny nicks and edge tears. Very good overall.