Landmarks of Human Thought I - Catalog - Page 53
The Key can be used to identify 昀椀rst editions and especially
later editions of U.S. patents.
Photographic copies and thus later reprints can easily be identi昀椀ed by the fact that unlike in a printing process there are no
impressions of any letters and the text sheet feel very smooth.
If the imprint at the bottom of the drawing sheet of an U.S. patent from a certain issue date does not match the lithographer
from the Key, it is a print from a later edition.
Figure 3: Of昀椀cial Gazette
of the USPTO, Vol. 126,
No. 5, January 29, 1907:
pages 1779, 1780
