cap lamp

Electric hand and cap lamps were introduced in mines in the early 1900s and by the middle of the 20th century were used almost exclusively in mines. A safety device in the headpiece of the electric lamps shuts off the current if a bulb is broken. Double-filament bulbs…

In the 1930s battery-powered cap lamps began entering mines, and since then various improvements have been made in light intensity, battery life, and weight.