A Ball & Peg Oil Cap Lamp.
A Ball & Peg Oil Cap Lamp. A Brass cap lamp which would be filled with oil and tied to your cap for light on the coalface.
The Ball was the reservoir that contained the oil and had a thick round wick, the Peg was the handle that could be unscrewed from the Ball, turned upside-down and screwed over the wick for transportation and safe keeping. Used throughout the 1800s. Size 7″ x 2 1/2″ inches.
(This one has been heavily renovated and repaired).