Early American "NX" Patents
The United States of America began issuing patents in 1790. Over the next 46 years, somewhere between 9000 and 1000 patents were issued. These early patents were not numbered. In 1836 new patent legislation was passed that, among other things, established a process of numbering newly issued patents. A short time later, the already-issued patents were retroactively numbered and this series of pre-July-1836 patents are now known as X patents. This process was complicated by a fire in December 1836 that destroyed the paper records of the Patent Office. At least partly because of those lost records, the process of assigning numbers was imperfect and quite a few patents were missed in the numbering.
Where such an omission was belatedly recognized by the Patent Office, the patent was assigned a “fractional” patent number such as X3015½. (The datamp database uses the prefix “FX” for these fractional patents.) However, researchers have identified a number of pre-1836 patents that were not assigned numbers by the Patent Office, fractional or otherwise.
The datamp database used the prefix “NX” for these X-patents that do not have numbers. The numbers have been somewhat arbitrarily assigned. We do not know whether they were actual patents as all that we have are the listings. They are entered here for reference and further research.
We believe that some NX patents are actual patents that were issued by the Patent Office but that were never assigned a number by the Patent Office. Others are due to errors or inconsistencies in the data and do not represent an actual patent that was not already assigned a patent number. Some may be due to reports of patents that had been applied for (or claimed to have been applied for) but were never issued. It is very likely that for most of the NX patents we will never know for certain whether they represent an actual issued patent or whether they are a phantom. All we can hope to do is try to narrow down the likelihood of an NX patent representing a real patent.
Information Sources
Information on X patents and NX patents have come from various sources. It is helpful to researchers to know exactly where the information here came from, and we are working to better document these sources for each patent. We are in the early stages of adding that information to each NX patent entry.
A major challenge is that the 1836 fire at the Patent Office destroyed all of the paper records of patents issued up to that time. A relatively small minority of the patents had their records restored, mainly by the original filer re-submitting their paperwork; most of those restored patents were from 1829 or later.
Our sources on NX patents primarily consist of the following, which we have divided into contemporary sources, i.e., sources that predate the Patent Office fire of 1836 and which were likely based on the records of the Patent Office, and secondary sources which were not directly based on those records.
Contemporary Sources
(Working on adding links to scans of these sources)
- Patent Office Reports.
- Annual Reports of the Commissioner of Patents. These may have only begun in 1836 with the new patent legislation. Hathi Trust has a collection that goes back only to 1842.
- Journal of the Franklin Institute.
Secondary Sources
- (1880s) Register of Name and Date Patents 1790–1836: (List of inventions patented 1790-1836, that in the 1880s was photolithographed from old Patent Office Reports. The document title varies. Still looking for a scanned version.)
- (1979) Jim Shaw's spreadsheet: X-Patents (names, dates, PNs only) X-Patents (with added fields). Jim Shaw is a patent attorney who created this document, the first digitized list of X patents.
- (?) IP Mall's list of X Patents. Based on Jim Shaw's spreadsheet?