Edison's cap lamp
Carbide lamps were only used for a short time before they were replaced by battery lamps. After some tragic disasters, Congress created the U.S. Bureau of Mines to improve safe working conditions in mines. The Mine Safety Appliances Company was then created, and Thomas Edison was enlisted to help invent a safe electric lighting technique. Edison created the electric cap lamp. The battery for this lamp was enclosed in a steel case and would be hung on the belt. A cord ran up the miner's back and connected to their helmet.