Recently, an antique dealer informed me that I own a Stella Moderator
that is only worth $500. I was just a bit surprised at the very low
estimation. Can any of you well informed experts give me some advise
and/or appraisals as to whether this is a true estimate or is this guy
a pirate I need to toss overboard?

The patent on Sept 22, 1885.  Serial number# 11848. All this is written
inside the box.  Here is Stella that looks remarkably like my own:
   http://www.finest1.com/meekins/stella.html

Thanks to all of you help in this matter.
Steve