Dana is describing a light seen atop one of the masts:
"When we got down we found all hands looking aloft, and there, directly over where we had been standing, upon the main top-gallant-mast-head, was a ball of light, which the sailors name a corposant (corpus sancti), and which the mate had called out to us to look at. They were all watching it carefully, for sailors have a notion that if the corposant rises in the rigging, it is a sign of fair weather, but if it comes lower down, there will be a storm. Unfortunately, as an omen, it came down, and showed itself on the top-gallant yard-arm."
This is a discharge of static electricity, ionizing the air. I have heard it called "St.Wlmo's Fire". Never heard
"corposant" before. Hou about you, Faldage?
