The Patent and Trademark Office has issued nearly seven million patents; the first 10,000 are known as the X-patents. They were issued from July 1790, when the United States patent system was created under an order signed by George Washington, to July 1836, when every one of them burned in a fire.

In the 168 years since the fire, only about 2,800 have been recovered. Over time, the appearance of missing X-patents grew fewer and farther between, so that now no one at the patent agency, which does not have an official historian, can remember the last time it happened.

Until this spring, that is, when two lawyers with a passion for patent history uncovered a clue to several important patents from the 1790’s – including one from 1826 for the first internal combustion engine. Following the trail to Dartmouth College, they discovered inventor copies of 14 patents that had been written off as lost forever.

“We found them by accident,” said Scott J. Asmus, a partner in the law firm of Maine & Asmus in Nashua, N.H., who found the documents with an associate, Andrew P. Cernota.

When they told the Patent and Trademark Office what they had found, the agency was immediately interested in adding the documents to its archives.

More here.