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At the close of the Revolutionary War in 1783, General George Washington suddenly found himself, uncharacteristically, with lots of time on his hands. Late that summer he took up residence at a farm house outside of Princeton, New Jersey, where Congress was meeting while awaiting the arrival from France of the signed Treaty of Paris, formally ending the war. Meanwhile, Washington found the time to conduct a scientific experiment to solve a mystery.

In September, the general wrote a friendly invitation to Thomas Paine to join him at his Rocky Hill, New Jersey, headquarters: “...if you will come to this place, and partake with me, I shall be exceedingly happy to see you.”1 Paine had served in Washington’s army as a volunteer aide-de-camp to Nathanael Greene during the Continental Army’s desperate retreat from New York across New Jersey and the Delaware in the fall of 1776, and wrote his American Crisis series of pamphlets in support of the Revolutionary War and Washington’s leadership of the army. Now he needed Washington’s help in seeking remuneration from Congress for his literary contributions to the war’s success, having previously directed that any profits earned from his publications be given to help clothe Washington’s troops. In his invitation, Washington promised to help.

After delaying his trip due to scarlet fever, Paine finally arrived at Rocky Hill in October. During the visit, Washington decided to conduct an experiment in response to persistent rumors: How could a creek close by possibly catch on fire? Benjamin Franklin, in a letter to Dr. Joseph Priestley, who discovered oxygen, described the mystery: “When I passed through New Jersey in 1764, I heard it several times mentioned, that by applying a lighted candle near the surface of some of their rivers, a sudden flame would catch and spread over the water, continuing to burn for near half a minute.”2

A friendly argument got going at Rocky Hill over what might cause the flaming water, so Washington and Paine, accompanied by some soldiers, took a boat and went to the mysterious creek nearby to see if they could find the answer. Washington and others held that the water caught on fire because of “bituminous matter” rising to the surface when the creek bottom was stirred up with poles, but Paine thought it was due to “inflammable air” surfacing.  Paine recalled the experiment in 1806:

General Washington placed himself at one end of the scow and I at the other; each of us had a roll of cartridge paper, which we lighted and held over the water about two or three inches from the surface when the soldiers began disturbing the bottom of the river with the poles….When the mud at the bottom was disturbed by the poles, the air bubbles rose fast, and I saw the fire take from General Washington’s light and descend from thence to the surface of the water, in a similar manner as when a lighted candle is held so as to touch the smoke of a candle just blown out the smoke will take fire and the fire will descend and light up the candle. This was demonstrative evidence that what was called setting the river on fire was setting on fire the inflammable air that arose out of the mud.3

Recently, scientists duplicated the experiment at Rocky Hill and more accurately described the cause of the flaming water.4 The “inflammable air” turned out to be methane gas released from disturbing the mud at the bottom of the creek. But what Washington’s experiment clearly shows is that he, along with other leading figures of the Enlightenment, was keenly interested in scientific experimentation and discovery.

When the signed Treaty of Paris finally arrived in America, Paine accompanied Washington to New York (as the entourage retraced the route of the army’s retreat across New Jersey seven years before), marched with the general as he entered the city to reclaim control of it from the departing British, and participated in festivities as Washington resigned his command of the army before returning to Mount Vernon to resume his life as a farmer. In time, their friendship would come to an abrupt end, Paine having published a bitter letter years later accusing President Washington of abandoning him as he set in a French prison cell awaiting his fate while Robespierre’s Reign of Terror raged during the French Revolution.5

Washington never answered Paine’s letter. But in the fall of 1783, their time together at Rocky Hill had been especially friendly, even if Washington’s hypothesis about what caused the river to alight lost out to Paine’s, as their scientific experiment proved.


Jett Conner
Professor of Political Science Emeritus
Metropolitan State University



1. Library of Congress, “George Washington to Thomas Paine, September 10, 1783,” American Memory. George Washington Papers at 1741-1799, Series 4, General Correspondence, 1697-1799., (accessed January 13, 2016).

2. Founders Online, “From Benjamin Franklin to Joseph Priestley, 10 April, 1774,”, (accessed January 14, 2016). 

3. Philip Foner, The Complete Writings of Thomas Paine, 2 vols. (New York: The Citadel Press, 1969), 2:1062-1063.

4. See, for example, Doug Eveleigh, “George Washington, Scientist,” Chemical & Engineering News, Vol. 92, Issue 38, p.2, Letters, September 22, 2014,, (accessed January 13, 2016).

5. Foner, Complete Writings of Thomas Paine, 2:691. 


Chernow, Ron. Washington, A Life. New York: Penguin Books, 2010.

Ellis, Joseph J. His Excellency, George Washington. New York: Vintage Books, 2004.

Foner, Philip S.  The Complete Writings of Thomas Paine, 2 vols. New York: The Citadel Press, 1969.

Library of Congress.  George Washington Papers, American Memory, Manuscript Division.

Nelson, Craig. Thomas Paine: Enlightenment, Revolution, and the Birth of Modern Nations. New York: Viking, 2006.

Thomas Paine National Historical Association, New Rochelle, NY.