Answer: Lincoln

In addition to his skill as a statesman and leader, Abraham Lincoln was a talented mariner and a life-long tinkerer. It was a merging of these last two that led Lincoln to work quietly in his spare time on a device intended to assist boats on the Mississippi River free themselves from shoals.

The device relied on buoyant chambers attached to sturdy timbers being forced down into the water in order to raise the mass of the boat up above the shoal–think of the mechanism like a pontoon boat that could lift itself upon its pontoons to clear obstacles in the water.

Although Lincoln applied for and received a patent for his design, the device was never manufactured or brought to market.