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Re-enactment of the George Washington – Thomas Paine
discovery that the Will-o'-the Wisp was a flammable gas
on the date of the 225th anniversary, November 5, 2008 

On the Millstone River at Rocky Hill: the First Scientific Experiment in the United States 

The Millstone River Valley was the location of what can be considered the first scientific experiment in the United States, the demonstration by George Washington and Thomas Paine that what people called "setting the river on fire" was setting on fire an inflammable gas that arose out of the mud.  At left: Portrait of George Washington, John Trumbull, 1780, Metropolitan Museum of Art; at right: Portrait of Thomas Paine, Laurent Dabos, c. 1792, National Portrait Gallery, Smithsonian Institution

"...a wandring Fire Compact of unctuous vapor, which the Night Condenses, and the cold invirons round, Kindl'd through agitation to a Flame, Which oft, they say, some evil Spirit attends, Hovering and blazing with delusive Light, Misleads th' amaz'd Night-wanderer from his way To Boggs and Mires, & oft through Pond or Poole, There swallow'd up and lost, from succour farr.”
― John Milton, Paradise Lost 

The "fire compact of unctuous vapor", called "Will-o'-the Wisp" or "Jack-o-Lantern", has been given many other names, and legend has it that it haunts moors and bogs all over the world. But the conversation at Washington's headquarters in the Berrien House at Rocky Hill that led to the 1783 experiment on the Millstone River was of a more scientific nature. Country folk said that the water in the river by the mill at Rocky Hill could be set on fire. Was that true? And if so, what was the cause? General Washington was in residence at Rocky Hill as the Revolutionary War ended, waiting for the newly-signed Treaty of Paris to arrive. Thomas Paine visited Washington there. Paine believed that the flame in the water was caused by flammable air, but others disagreed. To test the hypotheses, Washington and Paine, with the help of General Lincoln and Colonel Cobb, set out in a boat to try to set fire to the Millstone River. (photo courtesy of Ron Morris)

The Experiment on the Millstone River

On November 5th, 1783, Washington, Paine, Lincoln, and Cobb set out in a scow on the Millstone River near Rocky Hill. Each man had a roll of cartridge paper, so-called because it was used for making paper cartridges for breechloading guns. They set fire to the paper and held it 2 or 3 inches above the surface of the water. They were accompanied by soldiers who disturbed the bottom of the river with poles, causing bubbles to rise to the surface. Holding the flaming paper over the rising bubbles, they observed that the gas within burned as it rose above the surface of the water. This demonstrated that it was not the water or organic matter from the river bottom that burned, but the "flammable air" that rose out of the water. (photo courtesy of Robert Barth)

The photos above were taken on Nov. 5th, 2008, at a re-enactment of the Washington-Paine experiment. The re-enactment was performed by Doug Eveleigh, Theodore Chase Jr., Craig Phelps, and Lily Young, professors in the School of Environmental and Biological Sciences at Rutgers University. The professors also wrote a paper in the form of a letter to President George Washinton and Thomas Paine, describing the contribution to science represented by the experiment. The paper is available as a web page titled Magical Mud, Microbes, and Methane.  For a primary source description of the experiment, see Thomas Paine's own description below.  A complete text detailing further experiments by Paine can be found on the web at the Thomas Paine National Historical Association.

The Washington-Paine Experiment, described by Thomas Paine in his essay
"The Cause of Yellow Fever," written in 1806

      In the fall of the year that New York was evacuated ( 1783), General Washington had his headquarters at Mrs. Berrian's, at Rocky Hill, in Jersey , and I was there; the Congress then sat at Prince Town. We had several times been told that the river or creek, that runs near the bottom of Rocky Hill, and over which there is a mill, might be set on fire, for that was the term the country people used; and as General Washington had a mind to try the experiment, General Lincoln, who was also there, undertook to make preparation for it against the next evening, November fifth. This was to be done, as we were told, by disturbing the mud at the bottom of the river, and holding something in a blaze, as paper or straw, a little above the surface of the water. Colonels Humphreys and Cobb were at that time aides-de-camp of General Washington, and those two gentlemen and myself got into an argument respecting the cause. Their opinion was that, on disturbing the bottom of the river, some bituminous matter arose to the surface, which took fire when the light was put to it; I, on the contrary, supposed that a quantity of inflammable air was let loose, which ascended through the water, and took fire above the surface. Each party held to his opinion, and the next evening the experiment was to be made.

      A scow had been stationed in the mill dam, and General Washington, General Lincoln and myself, and I believe Colonel Cobb (for Humphreys was sick), and three or four soldiers with poles, were pub on board the scow. 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.
As General Washington sat at one end of the scow, and I at the other, I could see better anything that might happen from his light than I could from my own, over which I was nearly perpendicular. 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.


The gas that Thomas Paine called "flammable air" is now called "methane". It is the main component of natural gas, and is familiar to us as the gas now used for heating, cooking, and generating electricity. The methane that rises from rivers, lakes, and swamps is produced by the decomposition of organic matter and is called "biogas". The organic matter can be agricultural waste, manure, plant material, sewage, or food waste.

The organisms that digest organic matter to produce methane are called methanogens. Washington and Paine found "flammable air" in the Millstone River over 250 years ago, but scientists have only recently discovered the organisms that can live in an environment under water without oxygen to make it. In the 1970s a scientist named Carl Woese discovered some organisms very different from other known forms of life like bacteria and eukaryotes.