But Robert Peck, curator of art and artifacts at the Academy of Natural Sciences, decided to give it one last try.
What he and Eric Newman, a numismatic historian from St. Louis, found has rocked the world of Audubon scholars, who are calling their discovery "a eureka moment."
Their quest began about a decade ago, when Newman visited the academy as part of a tour of libraries and important collections. He and Peck met. They had lunch.
A year later, Peck wrote to him. Had Newman ever seen a New Jersey banknote with a bird on it?
Newman was an expert on the early paper currency of America and had written a definitive work on the subject. He didn't know of any, but he began looking.
Meanwhile, Peck investigated the Audubon side of the mystery.
That first diary reference had been on July 12, 1824. Audubon had since moved from Mill Grove, but he was back in Philadelphia to garner support - from the academy, the preeminent scientific institution in the country at that point - for his bird watercolors.
That never happened, due to what historians contend were jealousies involving another bird artist, Alexander Wilson.
But Audubon wrote that "I drew for Mr. Fairman a small grouse to be on a banknote belonging to the State of New-Jersey."
"Mr. Fairman" would have been Gideon Fairman, a principal in a Philadelphia engraving firm that specialized in making paper currency for financial institutions.
At that time, each bank made its own currency.
Right there!
On a trip to Chicago, Peck checked another diary, and found an entry from 1826. Audubon was in England, where his landmark book, The Birds of America, with full-size printings of his bird watercolors, was eventually produced, beginning in 1827.
He noted that he presented a friend "with a copy of Fairman's Engraving of [my] Bank Note Plate."
But had the money ever been printed? Or was it a plate that never got used?
