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Abraham Lincoln was the only US president to be granted a patent. When he
filed his application for a “device for buoying vessels over shoals”, US patent
examiners still required inventors to provide a working model, as well as a
technical description of the invention. Lincoln’s filing has been gathering dust
in a vault since the mid-19th century. The US Patent Office in Arlington,
Virginia, has now found the original model and is putting it on public display
as a museum exhibit, along with his patent, number 6469.