Abraham Lincoln's homemade tool - photos and patent

[Jon]

Only one United States president ever held a patent: Abraham Lincoln.

Lincoln, who had also worked as a patent attorney, created an invention to lift riverboats over shoals and other obstructions. Though the patent was issued in 1849, the documentation was not discovered for 150 years.

As part of the patent process, Lincoln created a 2-foot model of his invention. I believe the original model is considered too fragile to display publicly. However, there is a more commonly-displayed reproduction of the model at the Smithsonian:

Be it known that I, Abraham Lincoln, of Springfield, in the county of Sangamon, in the state of Illinois, have invented a new and improved manner of combining adjustable buoyant air chambers with a steam boat or other vessel for the purpose of enabling their draught of water to be readily lessened to enable them to pass over bars, or through shallow water, without discharging their cargoes;

As a teenager, Lincoln had worked as a hired hand on a flatboat ferrying passengers and cargo down the Ohio and Mississippi rivers. During this time, he experienced a common annoyance of river navigation: getting the boat stuck on a shoal.

A river shoal, also known as a sandbar, is simply a portion of the river bed that is raised enough to cause the sides and/or bottom of riverboats to get hung up on it. The common solution to free a stuck ship was to offload the cargo from the ship, un-stick the now-lighter ship, and then re-load the cargo back onto the ship.

Lincoln's invention consisted of large expandable bellows on the side of a steamship, which would essentially function as buoyant chambers. When a ship was stuck on a river shoal, the chambers would be forced down into the water via a "series of ropes and pullies or their equivalents". Once the ship was freed, the bellows were lifted back up and stowed securely on the side of the riverboats.

Here's Lincoln's patent, US patent 6,469, entitled: "Buoying vessels over shoals":



And here's the fullsize patent drawing: Fullsize drawing for US patent 6,469.

Lincoln's patented invention was never really put to use. There is some debate over the amount of force necessary to push the buoyant chambers down into the water. Of course, Lincoln eventually abandoned his career as an inventor to pursue politics.


Previously:

The H.L. Hunley, the first submarine to sink a warship
Salving a 50,000 ton ship by slicing it
Airplane fuel tanks turned into Vietnamese boats
Boat that pulls itself ashore