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Re-recording history

So The Legal Genealogist is in the last stages of preparing for a really fun webinar, taking place later today, sponsored by the Friends of the National Archives-Southeast Region.

Cotton.ginIt’s called “Inventing America – Records of the U.S. Patent Office” — and let me tell you, going through patent records gives you a bird’s eye view of the development of America like almost nothing else will.

But there’s a real anomaly in those records, one that often confuses people.

It’s the numbering system for some of the early patents, and the dates recorded on the records.

Take, for example, Eli Whitney’s patent for a cotton gin — shown in the patent drawing you see here.

Now we all learned about that invention in school:

Designed to separate cotton fiber from seed, Whitney’s cotton gin, for which he received a patent on March 14, 1794, introduced a new, profitable technology to agricultural production in America.

The cotton gin is a device for removing the seeds from cotton fiber. Such machines have been around for centuries. Eli Whitney’s machine of 1794, however, was the first to clean short-staple cotton, and a single device could produce up to fifty pounds of cleaned cotton in a day. This made cotton a profitable crop for the first time.

After this invention, the yield of raw cotton doubled each decade after 1800. Demand was fueled by other inventions of the Industrial Revolution, such as the machines to spin and weave it and the steamboat to transport it. By mid-century America was growing three-quarters of the world’s supply of cotton, most of it shipped to England or New England where it was manufactured into cloth. During this time tobacco fell in value, rice exports at best stayed steady, and sugar began to thrive, but only in Louisiana. At mid-century the South provided three-fifths of America’s exports—most of it in cotton.1

So… if this patent was issued in 1794, why is there a section down at the bottom of the patent drawing that reads “Patent Office March 18th 1845. Made under the direction of the Commissioner of Patents in conformity with act of 3d March 1837”?2

Well, let’s see just what the act of 3d March 1837 has to say about that:

Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled, That any person who may be in possession of or in an way interested in any patent for an invention, discovery, or improvement, issued prior to the fifteenth day of December, in the year of our Lord one thousand eight hundred thirty-six, or in an assignment of any patent, or interest therein, executed and recorded prior to the said fifteenth day of December, may, without charge, on presentation or transmission thereof to the Commissioner of Patents, have the same recorded anew in the Patent Office, together with the descriptions, specifications of claim and drawings annexed or belonging to the same ; and it shall be the duty of the Commissioner to cause the same, or any authenticated copy of the original record, specification, or drawing which he may obtain, to be transcribed and copied into books of record to be kept for that purpose ; …3

Uh oh.

You know what that sounds like, don’t you?

Yep. You’re right.

A minor little matter of a fire at the Patent Office building. On 15 December 1836, the building being used as both the main Post Office building and the Patent Office building in Washington, D.C., was destroyed in what contemporary reports described as a “disastrous conflagration.”4

So under the 1837 law any inventor who’d had a patent recorded before the fire was able to get it re-recorded afterwards.

But now think about it. You’re the patent officer there in 1837. One guy comes in to re-record a patent. Another guy comes in to record a brand new one, never before recorded. How do you distinguish between those two?

You can’t give the old patents the numbers they originally had — because they didn’t have any numbers at all. The pre-fire patents were only recorded by the name of the inventor.5 But now here you are, all modern in 1837, and patents are getting numbers. How do you number the old ones, while still numbering the new ones?

That’s where the X files come in. The re-recorded patents were given X numbers, and whenever you see an X designation in a patent record, you know it was one of the ones initially recorded before 15 December 1836 and then re-recorded after 3 March 1837.

Which explains how a patent issued in 1794 bears a date of 1845.

The X files. Fun stuff.


  1. Patent for Cotton Gin (1794),” Our Documents, National Archives ( : accessed 8 Dec 2014).
  2. Eli Whitney, patent no. 72X (14 Mar 1794); Restored Patent Drawings, compiled 1837 – 1847, documenting the period 1791 – 1836; Records of the Patent and Trademark Office, Record Group 241; National Archives II, College Park, Md.
  3. “An act in addition to the act to promote the progress of science and useful arts,” 5 Stat. 191 (3 Mar 1837).
  4. See e.g. The New York Evening Post, “Disastrous Conflagration,” p. 2 (17 Dec 1836); ( : accessed 8 Dec 2014).
  5. See “Records of the Patent and Trademark Office,” Guide to Federal Records, National Archives, ( : accessed 8 Dec 2014).
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