https://www.legalzoom.com/intellectual-property-rights/intellectual-property-basics/selling-patent-copyright-or
http://info.legalzoom.com/renew-patent-23430.html
"Plant patents and utility patents last up to 20 years from the date of
application, while patents for designs last up to 14 years from the date of
application. Plant and utility patents granted prior to 1995 last 17 years."
Interestingly they must be renewed every 20 years, however they can be sold
to others. I'd be curious how 150 years has worked for this patent as well,
considering it is unlikely the guy lived this long and renewed every time, or
that the new holder was so vigilant. :s
