File:Norton mechanical filter.png

The text and illustrations of US patents published before March 1, 1989 are in the public domain unless the patent text contains a specific notice that portions are copyrighted. See 37 CFR 1.71(d), 37 CFR 1.84(s) The original patent contains no such notice, so its contents are in the public domain. Note: This only applies to images published before March 1, 1989. Patents published after that date are most likely copyrighted, unless in the public domain for another reason, such as {{PD-ineligible}}.

Transferred from en.wikipedia to Commons by Wdwd using CommonsHelper.

• 2009-06-25 22:30 Spinningspark 715×498× (35668 bytes) {{Information |Description=A mechanical filter designed using electrical network theory |Source=US patent US1792655 |Date=31st May 1929 (filed) |Author=[[Edward Lawry Norton]] |other_versions= }} == Licensing == {{PD-US-patent}} {{KeepLocal}}