WILL-with-a-wisp, or Jack-with-a-lanthorn, a meteor known among the people under these names, but more usually among authors under that of ignis fatuus.
This meteor is chiefly seen in summer-nights, frequenting meadows, marshes, and other moist places. It seems to arise from a viscous exhalation, which being kindled in the air, reflects a sort of thin flame in the dark, without any sensible heat.
It is often found flying along rivers, hedges, &c. by reason it there meets with a stream of air to direct it. The ignis fatuus, says Sir Isaac Newton, is a vapour shining without heat; and there is the same difference between this vapour and flame, as between rotten wood shining without heat and burning coals of fire.