Benjamin Franklin Was the First to Chart the Gulf Stream

Franklin’s cousin, Timothy Folger, knew how the then-unnamed current worked from his days as a whaler

This copy of the first chart of the Gulf Stream was printed in 1786, ten years after Benjamin Franklin first drew it up. Library of Congress

Benjamin Franklin is known for shaping the Constitution, writing letters as a woman, chowing down on native foods and hosting an anatomy school in his home. What doesn’t often get mentioned is that he was also the first to chart the Gulf Stream. He completed the first scientific study of the current on this day in 1775, according to Today in Science History.

The Gulf Stream is an ocean current that moves clockwise through the Gulf of Mexico and up along the eastern coastline of North America. It is part of a large system of five circular gyres in the North Atlantic, according to Kim Ann Zimmermann for LiveScience. “Because it altered sailing patterns and shaved time off a typically long and treacherous trip, the Gulf Stream was instrumental in the colonization of the Americas,” Zimmermann writes.

It was also found early on by colonists. The first European to observe and write about the Gulf Stream was Juan Ponce de León, writes Jared Lloyd for the Coastal Review Online. After leaving the Spanish colony of Puerto Rico, de León and his crew sailed north searching for new lands to plunder and pillage. In April 1513, de León wrote in his journal that the ships he was captaining were caught up in a strange current that seemed to be stronger than the wind.

But “despite the magnitude of this discovery, neither Ponce de León nor the Spanish Crown paid heed to it,” Lloyd writes. “Back in Spain, the only thing that came of this expedition was the acknowledgment that Ponce de León had failed to find gold.” European explorers did continue to use the current and build on their knowledge of it, but it wasn’t mapped or named until Franklin came along.

In true Franklin fashion, he came to study the Gulf Stream because of a question, writes Laura Bliss for City Lab. It was 1768, when he was working in London as deputy postmaster general for mail to and from the American colonies. Franklin was talking to his cousin, Timothy Folger, who was the captain of a merchant ship. He asked why it took ships like Folger’s so much less time to reach America than it took official mail ships.

“It struck Folger that the British mail captains must not know about the Gulf Stream, with which he had become well-acquainted in his earlier years as a Nantucket whaler,” writes Bliss. Folger told Franklin that whalers knew about the “warm, strong current”and used it to help their ships track and kill whales.

“In crossing it [we] have sometimes met and spoke with those packets, who were in the middle of it, and stemming [sailing against] it,” Franklin later wrote that Folger told him. But the mail ships “were too wise to be counselled by simple American fishermen,” and kept sailing against the current, losing time as they did so.

“Folger sketched out the rough location for Franklin, who soon made prints, along with his cousin’s directions for how to avoid what he dubbed the ‘Gulph Stream,’” Bliss writes.  Franklin gave copies to his mail ships, but they seem to have ignored the directions.

When Franklin shifted allegiances during the American Revolution, he gave ‘Gulph Stream’ directions to America’s French allies, cementing the importance of knowing the stream for European mariners.

Although Franklin did make observations of the stream and write them down, “the accuracy of the chart is really due to Folger and his inherited whaling knowledge,” Bliss writes. “But Franklin was the one with the good instincts to map it, and that, combined with his general eminence, has landed him with most of the credit.”

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