USAPat Subscriber Notice

A unique collection of "fraction" patents was added to USAPat with the USP 2001 W22 issue. Approximately 106 patents, the majority of which issued between 1812-1839, were given patent numbers that ended with a fraction when they issued. One such "fraction" patent is X3766 1/2 that issued in 1823.Most, but not all, of these patents are "X" patents having issued between 1790 and 1836, before the USPTO began numbering patents.

Eighty-one of these 106 patents are now part of the USAPat collection. Collecting images for these numbers is an on-going project and images will be added to USAPat, as they become available. If a particular number is in the cumulative index without an image, a message page is displayed indicating that "Image data was not available when the disc was made."

These patents have not been a part of any USPTO electronic collection because of the difficulty of accounting for the fraction in the patent number. This problem was recently resolved by substituting a letter at the end of the patent number for the fraction. Once the problem was resolved, the patents were scanned and loaded into the USPTO's electronic systems using the following codes:

Letter  Fraction
A 1/16
B 1/8
C 3/16 
D 1/4
E 5/16
F  3/8
G 7/16
H 1/2
I 9/16
J 5/8
K 11/16
L 3/4
M 13/16
N 7/8
O 15/16

Using this code, the previously mentioned "fraction" patent X3766 1/2 would appear as X3766H in the USAPat cumulative index, with the H standing for 1/2. The letter is now a part of the patent number for electronic searching purposes.

As with most of the older patents issued prior to 1836, parts were destroyed in the USPTO fire of 1836. Therefore, some of these patents may be missing text or drawings. The USAPat images contain everything that is currently available. Note that the "X" patent numbers are at the end of the index. To jump to these numbers, begin typing the letter and the index will automatically move to that place in the index.

Please contact us [the uspto] if you have any questions.

2001 June 26