I was an active caver during the "carbide lamp era." roughly the twentieth century up until about 1985 or so. The mechanism was a dependable source of light for long periods, as well as heat, a good thing in the typically chilly cave environment. With a loose fitting garment, one could sit on the ground, place the lamp between your legs, pull the garment over your knees, and voila! instant warmth. Also good for lighting a trail after dark, while keeping your hands warm, and a great fire starter....
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Geezer in Chief