The Will-with-a-Wisp.
This phenomenon, known also as "Jack-with-a-Lantern" and "Ignis fatuus," has terrified many a simple-minded rustic, whereas it is simply the phosphuretted hydrogen gas which rises from stagnant waters and marshy grounds. Its origin is believed to be in the decomposition of animal substances. Collins has left us some fine lines upon this phenomenon, beginning—
"Ah, homely swains! your homeward steps ne'er lose;
Let not dank Will mislead you to the heath;
Dancing in murky night o'er fen and lake,
He glows to draw you downward to your death,
In his bewitch'd, low, marshy willow brake."
At Bologna, in 1843, the painter Onofrio Zanotti saw this phenomenon in the form of globes of fire, issuing from between the paving-stones in the street, and even about his feet. They rose into the air and disappeared; he even felt their heat when they passed near him.