Colonial Semi-Circumferentor With Engraved Trough Compass

Description

This colonial era unsigned Semi-Circumferentor is one of the more common varieties - trough compass, brass semi-circle, brass alidade  and sight vanes, and a wood block.   The engraved compass card is another story, however.  Wow.  Semi-Circumferentors made largely out of wood were supposed to be a fairly cheap way for a surveyor to buy an instrument that could measure independently of the needle.  So why would an affordable instrument have such a wonderfully engraved compass card???
I came across a fair number of pre-1825 Semi-Circumferentors during my research for the Theodolite and Semi-Circumferentor website addition,  and the Semi-Circumferentor offered here is the only one (by far) to have an elaborately engraved compass card.
If you look closely at the engraving, there appears to be an "M" engraved.  I can also make out a much smaller "L" if I squint hard enough.  These are probably just random scratches.  But there is an "L. M." who would be capable of this level of engraving - Lewis Michael.   I can't think of a single reason why Lewis Michael would make this instrument, however.  And he never advertised Semicircles for sale in his newspapers ad.   So I view this as an unsigned but VERY cool Semi-Circumferentor.
You can see my new Theodolite and Semi-Circumferentor website addition at:  http://compleatsurveyor.com/EarlyEuro/CollectingEarlyTheodolitesSemis.html
(Keywords -
Gurley, Berger
, Surveying, Surveyor, Transit, Circumferentor)