THE FALL 1990 ISSUE of Invention & Technology contained an article called “The First U.S. Patent.” It told the story of Samuel Hopkins of Pittsford, Vermont, and how his innovative method of extracting potash from wood ashes (which were plentiful in a young nation whose settlers spent much time clearing trees from their land) earned the first patent ever granted by the United States government. The author was Henry Paynter, a retired MIT professor who lived, and still lives, in Pittsford. He went into great detail about the importance of potash in early America, describing the chemistry behind Hopkins’s advance, giving statistics on the growth of potash production, and explaining its importance in industry.

To this day we recall Paynter’s article as one of our best ever, a model of both thoroughness and concision. Even so, we must now report that another historian has recently discovered a flaw in the piece: It’s about the wrong man. The first U.S. patent was granted not to Samuel Hopkins of Pittsford, Vermont, but to Samuel Hopkins of Philadelphia, Pennsylvania.

A number of facts point to this conclusion, not least the wording of the patent itself, which begins (as anyone can see by reading our article): “Whereas Samuel Hopkins of the City o Philadelphia. …” Yet neither Paynter nor our editors can be blamed for the mistake since everyone involved was relying on official information from the U.S. Patent Office. The confusion arose in the 1840s, when this office was reconstructing its records after a disastrous 1836 fire. For unknown reasons, a clerk at that time mistakenly attributed the first patent to the wrong Samuel Hookins.

The slip attracted little attention until the 1930s, when a cousin of the Vermont Hopkins, in a family history, named his forebear as the patent holder. On the basis of this privately published genealogy, the Vermont Historical Society repeated the error in an article in its newsletter, and in 1956 a plaque was erected in Pittsford. From then on, the mistaken identification was accepted as established fact.

The confusion was finally cleared up by David Maxey, a Philadelphia lawyer and historian. Maxey, a retired partner in the firm of Drinker Biddle and Reath, was looking through some papers at the Historical Society of Pennsylvania that had belonged to Henry Drinker, a wealthy eighteenth-century Quaker merchant. He noticed repeated references to one Samuel Hopkins, also a Quaker, who was employed by land speculators to supervise potash production on their tracts using his patented process. As Maxey delved deeper into Philadelphia Sam’s past and activities, he came across our 1990 article and learned of the Vermont plaque, as well as a second plaque near the site of Vermont Sam’s grave (which, to add to the confusion, is in Pittsford, New York). At that point he determined to set the record straight and identify his Hopkins as the real patentee. The clinching piece of evidence came when Maxey showed that the signer of a 1791 marketing prospectus for the patent was the son-in-law of the Philadelphia Hopkins.

In response to Maxey’s discovery, the plaque in Vermont has been taken down, and a new one has been erected in Philadelphia at Second and Arch Streets, near the site of Hopkins’s residence. Paynter is goodnatured about the corrections and points out that except for the mistaken material about the inventor, his article remains accurate. A corrected version can be read at www.hankpaynter.com . Maxey has treated the subject much more thoroughly in his 1998 articles in Pennsylvania Magazine of History and Biography and Journal of the Patent and Trademark Office Society. As for Invention & Technology , we are happy to make this correction, thereby adding another name to the long and distinguished roll of Philadelphia inventors—from Ben Franklin, John Fitch, Tom Paine, and Oliver Evans to J. Presper Eckert and John Mauchly—who have graced our pages through the years.