I know I promised the answer yesterday but Life just got in the way...
So here I am with the answer to the " WHAT IS IT?"
This is an OPISOMETER ......
It is a Nautical milage" calculator" for drafting map scales
The roller on the left side of the photo measures the distances on a map and turns the figures from centimetres (German spelling) to kilometres.
Turning the meter over the instrument figures statute miles...kilometers ...and nautical miles
It also has a mechanical pencil.
I have no idea where we got this antique but we are ready to sell it on eBay.
I am amazed how many there are up for sale at the current time.
Thanks for playing along.
If and when it does sell, I will certainly let all of you know.