While serving in Congress in 1848, Abe Lincoln conceived a way to help boats that became stranded on sandbars. If bellows were attached to a craft below the waterline, these could be inflated when it got stuck, buoying the craft and allowing it to float over the shoal.

Lincoln whittled a 20-inch model from a cigar box and a shingle. His law partner, W.H. Herndon, didn’t think much of it, but Lincoln presented it to lawyer Z.C. Robbins, who arranged a patent in 1849. This makes Lincoln the only president to hold a patent.

Apparently it never went to market, though. “Railroads soon diverted traffic from the rivers,” Robbins recalled, “and Lincoln got deep in law and politics, and I don’t think he ever received a dollar from it.”