Armored Explorers in Toxic Cavern — Victorian Sci-Fi Engraving c.1870s

A team of heavily armored explorers stands in silent deliberation inside a vast subterranean dome, their breathing apparatus and sealed helmets suggesting a poisonous or airless atmosphere. Some carry long poles or rifles; one figure stands arms-crossed in apparent command. Strange luminous streaks rain down from above like falling fire or radiation. The scene pulses with the quiet dread of men standing at the threshold of the utterly unknown.