Its specific name is a Crotal bell. But some people call them "jingle-bells" because of the Christmas season song and what you see in the horse-&-sleigh photo helpfully posted by digging440years. They are known to exist in various sizes, from about 1/2-inch to about 2-plus inches. Your Crotal bell, being solid-cast brass instead of thin stamped sheetbrass, is significantly old. I'm not sure whether the solid-cast ones go back as far as the 1600s (or earlier), but they've been found at 1700s, 1800s, and early-1900s sites... so yours could be between one and three centuries old.