Abraham Lincoln was a tinkerer. He loved all things mechanical. "He evinced a decided bent toward machinery or mechanical appliances, a trait he doubtless inherited from his father who was himself something of a mechanic and therefore skilled in the use of tools." Henry Whitney, a lawyer friend of Lincoln's, recalled that "While we were traveling in ante-railway days, on the circuit, and would stop at a farm-house for dinner, Lincoln would improve the leisure in hunting up some farming implement, machine or tool, and he would carefully examine it all over, first generally and then critically." Abe was a man of considerable mechanical genius. He had The Knack. His patent, Patent No. 6469, a device for buoying vessels over shoals, makes him the only U.S. president to hold a patent. What kind of innovator was Lincoln? Was he a PROBLEM-TO-SOLUTION inventor? Did he first observe problems and then create solutions? Or was he a SOLUTION-TO-PROBLEM inventor whereby he first envisioned hypothetical solutions and then connected them to worthy problems? My sense is he was both. He was "ambidextrous," a two-way innovator.