Not P but Moby-Dick (14)

[Mike Jing]

Still more from Chapter 36:

“Drink and pass!” he cried, handing the heavy charged flagon to the nearest
seaman. “The crew alone now drink. Round with it, round! Short
draughts—long swallows, men; ’tis hot as Satan’s hoof. So, so; it goes
round excellently. It spiralizes in ye; forks out at the serpent-snapping
eye.

What does "It spiralizes in ye; forks out at the serpent-snapping eye" mean?