I think this is a really sweet Circa 1700 Butterfield Graphometer.

As discussed on my Butterfield Maker Webpage, Michael Butterfield (an Englishman who moved to Paris) was one of the premier instrument makers in France for roughly 50 years (1670 to 1720 or so). Only Nicolas Bion rivaled Butterfield in terms of fame.

While small, this Butterfield Graphometer has lots of charm. This Butterfield Graphometer has really nice engraving and a lovely patina as well. It can sit on a staff to measure horizontal angles or can hang from a hook to measure vertical angles. The Graphometer has two divided half-circles which are offset by 30 Minutes. So while small, a surveyor can easily read an angle to 10 or 15 minutes of a degree.

As for dating this instrument, I am told that Butterfield signed his name above the compass pre-1700 and on the fixed alidade post-1700. Since Butterfield signed this Graphometer about the compass, I'm calling this a Circa 1700 Graphometer. But it could have been made earlier.

Note that Butterfield also signed the compass plate underneath the face of the Graphometer. Nice.

This Butterfield Graphometer presents really well. If you want to own a pretty neat Graphometer made by a very famous maker, this one should merit serious consideration.