After seeing Niagara Falls he continued his journey homeward. At some point on the way, the vessel on which he had taken passage stranded on a sand bar. The captain ordered the hands to collect all the loose planks, empty barrels and boxes and force them under the sides of the boat. These empty casks were used to buoy it up. After forcing enough of them under the vessel she lifted gradually and at last swung clear of the opposing sand bar. Lincoln had watched this operation very intently. It no doubt carried him back to the days of his navigation on the turbulent Sangamon, when he and John Hanks had rendered similar service at New Salem dam to their employer, the volatile Offut. Continual thinking on the subject of lifting vessels over sand bars and other obstructions in the water suggested to him the idea of inventing an apparatus for that purpose. Using the principle involved in the operation he had just witnessed, his plan was to attach a kind of bellows on each side of the hull of the craft just below the water line, and, by an odd system of ropes and pulleys, whenever the keel grated on the sand these bellows were to be filled with air, and thus buoyed up, the vessel was expected to float clear of the shoal. On reaching home he at once set to work to demonstrate the feasibility of his plan. Walter Davis, a mechanic having a shop near our office, granted him the use of his tools, and likewise assisted him in making the model of a miniature vessel with the arrangement as above described. Lincoln manifested ardent interest in it. Occasionally he would bring the model in the office, and while whittling on it would descant on its merits and the revolution it was destined to work in steamboat navigation. Although I regarded the thing as impracticable I said nothing, probably out of respect for Lincoln's well-known reputation as a boatman. The model was sent or taken by him to Washington, where a patent was issued, but the invention was never applied to any vessel, so far as I ever learned, and the threatened revolution in steamboat architecture and navigation never came to pass. The model still reposes in undisturbed slumber on the shelves in the Patent Office, and is the only evidence now existing of Lincoln's success as an inventor.*