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X-Patent number 72, Eli Whitney’s cotton gin.

The X-Patents are all the patents issued by the United States Patent and Trademark Office from July 1790 (when the first U.S. patent was issued), to July 1836. The actual number is unknown, but the best estimate is 9,957. The records were burned in a fire, in December 1836, while in temporary storage. No copies or rosters were maintained by the government at the time, leaving only the inventors’ copies to reconstruct the collection.

The USPTO and its earliest days[edit]

The Patent Commission of the U.S. was created in 1790. Its first three members were Secretary of State Thomas Jefferson, Secretary of War Henry Knox, and Attorney General Edmund Randolph.

On July 31, 1790 inventor Samuel Hopkins of Pittsford, Vermont became the first person to be issued a patent in the United States. His patented invention was an improvement in the “making of Pot Ash by a new apparatus & process.” The earliest patent law required that a working model of each invention be produced in miniature.

The Patent Law was revised for the first time in 1793. It adopted a simple registration system where a patent would be granted for a $30 fee. The Patent Board was replaced by a clerk in the Department of State. James Madison, Secretary of State, created a separate Patent Office within the State Department and he appointed Dr. William Thornton as its first superintendent in May 1802.

The Patent Office was the only major government building to survive the British invasion of Washington, D.C. during the War of 1812. This is credited to Dr. William Thornton who was building a musical instrument in the same building. He persuaded British officers that they would be destroying the shared intellectual record of mankind if the patents were burned. [1]

The 1836 fire[edit]

The Patent Office 1836 fire occurred on December 15 when the patents were in temporary storage while a new (more fireproof) facility was being built. A fire station was located next to the temporary storage facility, but the hoses and pumps were frozen, and the firemen were unable to prevent the loss.

Recovery of the X-Patents[edit]

The United States Congress immediately passed a law to aid re-issuing of the missing patents after the fire. About 2,800 such patents have been recovered,[2] and 1,989 are online.

Following the 1836 fire, a serial numbering system was instituted. This system is still in use today. When an earlier patent was recovered and re-issued, the USPTO sometimes gave it a fractional number (e.g. 2960½X, issued on June 2, 1818; 8736¾X, issued on March 27, 1835) to preserve the correct sequence. Most, but not all, fractional patents are X-Patents.

Prior to this, U.S. patents were identified by titles and dates. Since then, all new patents issued are preserved and given a serial patent number started from 1. The recovered patents are also numbered from 1, however, these numbers have an “X” added to them. The X is generally added to the end of the number except for the first patent which has the X in the beginning of the number. Therefore, they are called X-Patents.

The latest X-Patents were recovered in 2004 from the Dartmouth College archives.[3] Of the 14 found, 10 were granted to Samuel Morey including the first known patent for an internal combustion engine.

A list of some X-Patents[edit]

1XPotash productionSamuel HopkinsJuly 31, 1790U.S. Patent X1First U.S. patent
72XCotton GinEli WhitneyMarch 14, 1794U.S. Patent X72Revolutionized cotton farming and textiles industry
4378XGas Or Vapor EngineSamuel MoreyApril 1, 1826U.S. Patent X4,378 
9000XGrateN. WinslowJuly 2, 1836U.S. Patent X9,000 
9430XImprovement in Fire-ArmsSamuel ColtFebruary 25, 1836U.S. Patent X9,430A key patent in revolver history
9899XBrick MachineC. WatermanJuly 2, 1836U.S. Patent X9,899 
9894XPlow MoldboardI. SniderJuly 2, 1836U.S. Patent X9,894 
9893XLockA. RoffJuly 2, 1836U.S. Patent X9,893 
9890XThrashing Mach.A. ParsonJuly 2, 1836U.S. Patent X9,890 
9889XCook StoveW. ParmaleeJuly 2, 1836U.S. Patent X9,889 
9887XPlowT. MillerJuly 2, 1836U.S. Patent X9,887 
9886XDressing StaresC. McGregoryJuly 2, 1836U.S. Patent X9,886 
9885XCotton GinJ. McCreightJuly 2, 1836U.S. Patent X9,885 
9884XDoor LockJ. Mo CloryJuly 2, 1836U.S. Patent X9,884 
9882XClover HullerW. LoomisJuly 2, 1836U.S. Patent X9,882 
9879XFeather DresserF.P.KnowltonJuly 2, 1836U.S. Patent X9,879 
9878XPlatform BalanceJ. HortonJuly 2, 1836U.S. Patent X9,878 
9877XNail ExtractorR. HaynesJuly 2, 1836U.S. Patent X9,877 
9876XCotton PressH.G. GuyonJuly 2, 1836U.S. Patent X9,876 
9875XCook StoveC. GrangerJuly 2, 1836U.S. Patent X9,875 

See also[edit]


  1. ^ "Great Patent Fire of 1836". The United States Patent and Trademark Office. Retrieved 2007-11-23. 
  2. ^ Riordan, Teresa. "Lawyers Unearth Early Patents". New York Times. 
  3. ^ Riordan, Teresa (August 9, 2004). "Lawyers Unearth Early Patents". New York Times. Retrieved 2009-07-18. [dead link]

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