Picked this up at a muddy March flea market for two dollars. It has numbered notches and a rotating top plate, but no obvious way to attach it to anything. What is this thing?

the primary material was the first clue. Known for its durability and resistance to corrosion, brass has been a favored material in various industries, particularly in agriculture and nautical applications. The presence of numbers suggested a need for precision, perhaps in measurement or calibration.
The rotating top plate was meticulously crafted, fitting smoothly over the base. This design hinted at an adjustable function, likely related to aligning the numbers with specific markers or settings. This combination of features pointed toward a tool of some sort, yet its exact role remained