I really love measuring tools of all sorts, and know there are a few of you out there who do, too--and this is such an old one, I could not resist. I am quite sure it is a piece of a navigational instrument, and believe part of a sextant, used to measure the angle between an astronomical object and the horizon for the purposes of celestial navigation. (A moveable arm, probably made of brass, would have attached to the corner from the back.) Really rare to see one of these hand-carved of wood, here it looks to me with angle measures carved in along the far edge, 0-20, numbered in 5 degree increments. Plus other marks and notations along the near curve that I can't quite decipher. 17th-18th century I am confident, with a monograph carved into the reverse. What especially makes it for me is all that carved crosshatching! Feels quite evocative of the "Age of Discovery."

7 1/2" x 2 7/8" x 3/8" and in very good, very antique condition; missing the arm or larger mechanism to which it once attached, but this piece itself shows no losses, cracks, etc.