THURSDAY: WHAT IS THIS?

Today's "what is this" comes from the Victorian pasture where most relics and coins are dated mid 1800s.

This is made of brass.  It is supposed to sit on something?  Is it a sight of some kind?

Upside down side view

Looking from the top

Upright side view.  Did that round part cradle something?

View from underneath

This one has me stumped.

If you have any idea, please let me know.

Until tomorrow, KEEP IT REAL.