An interesting chart of the Gulf Stream, based on Ben Franklin’s pioneering research.
The map depicts the Gulf Stream issuing through the strait separating Cuba and Florida, flowing northeast along the coastline, then turning eastward and gradually dissipating. The second, larger flow, which follows a circular, clockwise path, is almost certainly a depiction of the annual migration of herring around the Atlantic.
Franklin’s interest in the Gulf Stream came about as follows:
“About the year 1769 or 70, there was an application made by the board of customs at Boston, to the lords of the treasury in London, complaining that the packets between Falmouth and New-York, were generally a fortnight longer in their passages, than merchant ships from London to Rhode-Island…. Being then concerned in the management of the American post-office, I happened to be consulted on the occasion…. There happened then to be in London, a Nantucket sea-captain of my acquaintance [Franklin’s cousin Timothy Folger]…. He told he believed the fact might be true; but the difference was owing to this, that the Rhode-Island captains were acquainted with the gulf stream, which those of the English packets were not.” (Transactions, vol. II, p. 314)
Franklin had Folger draw the current on a chart, after which he
“had Folger’s chart printed and distributed to British packet captains in 1769 or 1770, but they tended to ignore it, perhaps because they couldn’t admit that colonial fishermen knew more about the ocean than did highly trained and experienced British mariners. When the American Revolution commenced, Franklin ceased distribution of the chart to prevent the British fleet from having the advantage of such valuable information.
“In March of 1775 Franklin left London and sailed for home. The next year he was sent as envoy to Paris to negotiate a treaty with the French government. During those two transatlantic crossings Franklin tested the temperature of the Gulf Stream and learned that it was warmer than the surrounding waters. The discovery renewed his interest in the Timothy Folger chart, and he had it copied and printed by Le Rouge following his arrival in Paris. He intended to provide copies to all French ship captains carrying arms and supplies to the American colonies.” (Captain John Lacoutere, USN, ret., “The Gulf Stream Charts of Benjamin Franklin and Timothy Folger”)
The London edition of Franklin’s chart from 1769 or 1770 is surpassingly rare, though the version printed by le Rouge—which was likely remaindered—appears on the antiquarian market with some frequency. The more affordable alternative offered here was issued in the third volume of The Works of Dr. Benjamin Franklin, compiled by his grandson William Temple Franklin (1762-1823) and published in Philadelphia in 1808.
It is worth noting that the depiction of herring migration on this map has nothing to do with Franklin. Rather, it was carelessly borrowed from a map in the Transactions of the American Philosophical Society (Vol. II, 1786) illustrating Franklin’s account of the Gulf Stream, which featured an inset illustrating John Gilpin’s “Observations on the annual Passage of Herrings.”
Folds flattened, with a couple of mends on verso including a 3 ¾” binding tear. Upper-right margin reinstated. Withal, nearly excellent in appearance.