This is a refractometer - it's an optical instrument that is used to determine the refractive index of a substance. They are used for measuring fluid concentrations such as the sugar content in honey.
Honey is hygroscopic; that is, it has excellent water absorbing properties.
Beekeepers as well as honey buyers know that the water content of honey varies greatly - it can range between 13 and 25 percent. According to the US Standards for Grades of Extracted Honey, honey may not contain more than 18.6 percent moisture to qualify for U.S. grade A (U.S. Fancy) and U.S. grade B (U.S. Choice).
The point in all this - at the meeting Tues night, our president had a refractometer and I had taken a jar of my honey - the moisture content was 16.9! That means if I entered my honey in the State Fair, I would be okay for the moisture content.