The fire bled upward from the cellar and swelled to an inferno overnight. Buckets and hoses proved no match for the blaze. A horrified crowd assembled outside Blodget’s Hotel, where the U.S. Patent Office shared space with the Post Office, and the sun rose on December 15, 1836, to find the entirety of the nation’s intellectual property records turned to ash: around 10,000 patents in total—every invention registered with the government since 1790. After the fire, the Patent Office—now the U.S. Patent and Trademark Office (USPTO)—implored inventors to send in their original documentation, to be duplicated. That effort formally ended in 1847, and to this day only around 2,845 of the lost patents have been fully replicated in the agency’s records.

But the USPTO has revived the rescue program­—and it’s going brilliantly. Most notable among the recent discoveries are two—authenticated this summer—belonging to 19th-century steamboat magnate Robert Fulton.

The papers, dating from 1809 and 1811, are Fulton’s own signed original copies of the patents. These were crucial in helping Fulton protect and expand the country’s first commercially successful steamboat enterprise, which he’d founded in 1807. The two patents are housed at the U.S. Naval Academy Museum in Annapolis, Maryland. Alex Roland, a retired Duke University history professor who is writing a Fulton biography, and St. John Courtenay III, a patent judge, whom Roland met in the course of his research, brought the patents to the USPTO’s attention.

These two finds represent “iconic X-patents,” says Adam Bisno, who became the agency’s first official historian in 2020 and went on to formalize and expand the recovery initiative.

Many of the records destroyed in 1836 are known as “X-patents”; they predated the patent numbering system and were retroactively assigned numbers appended with an “X.” (The Fultons are now known as 995X and 1434X.) Bisno believes more X-patents could be similarly hidden in plain sight in public and private collections. “They might even be framed on people’s walls just as examples of Americana.” Collectors needn’t worry about surrendering a treasure, though: Patent officials need only a high-resolution facsimile of an authentic document.

Bisno hopes these two Fulton finds will stir the interest and the help of the many caretakers of the nation’s paper trails. Archivists tend to know the value of what they have, he says. “They’ve been waiting for somebody to come looking for it.”