National Geographic : 1960 Feb
© NATIONALGEOGRAPHICSOCIETY spars themselves could be manipulated by ropes, pulleys, and a shaft. As Lincoln explained: "By turning the main shaft... the buoyant chambers will be forced downwards into the water and at the same time expanded and filled with air for buoying up the vessel by the displacement of water." Returning to his home in Springfield, Lincoln whittled a model of a steamboat (upper left) and tested his invention in a public water trough. In Washington at the close of the second session of the 30th Congress, inventor Lincoln filed an application for patent, together with the model. He won his patent in May, 1849, but nothing came of it. Today the Smithsonian Institution displays the model (left), complete with hull-riding chambers and deck-topping spars; and ore boats, here reversing Globe's course, sail past the new Mackinac Bridge between Lakes Michigan and Huron.