Missing Patent for Wright Bros' 'Flying Machine' Found in Cave The 'holy grail' of lost documents hadn't been seen in decades By Michael Harthorne, Newser Staff Posted Apr 2, 2016 4:15 PM CDT 49 comments Comments The Wright brothers conduct a test of their Flying Machine in 1904 in Ohio. (Shutterstock) (Newser) – Missing for decades, the Wright brothers' patent for their "Flying Machine" was found last month in a manila envelope among 15-foot-high stacks of patent files in a limestone cave outside a small Kansas city. The Washington Post has a fascinating story on how the "holy grail" of missing documents, which was supposed to be stored in Washington DC with other priceless papers, was finally recovered. The Wright brothers applied for the patent in 1903—nine months later their Flying Machine would spend 12 seconds airborne. One document in the patent file notes the brothers "invented a new and useful machine for navigating the air.” But when officials tried to find the patent file for a commemoration in 2000, it had disappeared. Officials realized the patent hadn't been seen since 1980, when it was returned to the National Archives following an exhibit at the Smithsonian. While it's possible the patent file could have been stolen, officials assumed it had simply been misfiled, which can be even worse when you're dealing with millions of patent papers. “If somebody puts something back in the wrong place, it’s essentially lost," the chief operating officer of the National Archives says. Sixteen years of hunting ended when archivist Bob Beebe—close to giving up during a search of a cave used to store records outside Lenexa, Kansas—opened one final box on March 22. "We found it," Beebe emailed a colleague. The Flying Machine patent is scheduled to be exhibited next month at the National Archive Museum. Read the full story here.