Abraham Lincoln received patent #6469 on May 22, 1849 for a device to lift boats over shoals. His device was never manufactured but he did become the only president to hold a patent.
Lincoln had considerable experience as a boatman. Once while taking a boatload of merchandise down the Mississippi River, his boat slid into a dam. Traveling the Great Lakes on another trip, his boat ran afoul of a sandbar. Lincoln noticed that the efforts to free the boat were similar on both occasions. Lincoln began working on an invention to solve this problem between sessions of Congress in 1848. His solution was a set of bellows attached to the boat just below the water line. When the boat came upon shallow water, the bellows were filled with air that moved the vessel and made it float higher. Continue reading “Presidential Patents – Lincoln’s Invention for Lifting Boats”