magnifying glass

There are magnifying glass-like apps available for smartphones. The (free) one I've experimented with uses the camera lens and the camera zoom software, providing a single-finger user interface and a flashlight option. Might be a useful tool...

Wondering if anyone can help me with this brass magnifier. It had no markings and the handle is made of an odd wood or shell. Came from an antique shop in Florida. Any info would be greatly appreciated.