Abraham Lincoln had traveled on boats that would run aground in shallow water. These events inspired him to invent and patent a device with adjustable air chambers that would lift boats over shoals. The invention consisted of a set of bellows attached to the hull of the ship just below the water line. The bellows would fill with air and the boat could maneuver through the water. Lincoln was granted the patent on May 22, 1849, but the invention never sold. The wood model Lincoln made for his patent application is on display at the Smithsonian Institution National Museum of American History.