A triangular cloud appeared in a storm on Dec. 17, 1852, according to the London Roy. Soc. Proc., 6-276. It was about half the apparent diameter of the moon, and had a red nucleus and a long tail. It was visible for 13 minutes before the nucleus exploded.
–Charles Fort, The Book of the Damned, p101 (The Complete Books of Charles Fort, Dover, c1974).