presidential blunders

Many historians rank Abraham Lincoln as the best president. Despite the almost universal acclaim for having held the country together through the Civil War, Lincoln's failures and mistakes are well known: failing in business, suffering nervous breakdowns, and losing many elections. But one of his failures is famously obscure and, perhaps, the most interesting. Lincoln is the only president to successfully obtain a U.S. Patent. On March 10, 1849, Lincoln filed a patent application for his invention designed to help raise boats off sand bars and shoals through the use of inflatable horizontal floats. In addition to a detailed description, Lincoln's patent application included a drawing of his invention and a wooden model with his signature. On May 22, 1849, Lincoln's ambitious invention was awarded U.S. Patent 6,469. To Lincoln's disappointment, his contraption was never built, but he visited the Patent Office during his presidency to view his original model. Here's two fascinating links relating to Lincoln's failed invention:

• Original patent drawing and application
  
• Photograph of Lincoln's wooden model