The Pequod discovers by signaling that the other ship is the Jeroboam, another Nantucket whaling ship.
The Jeroboam launches a boat over to the Pequod, but stays a short distance away. Captain Mayhew explains that his ship has a contagious disease on it and he’s observing quarantine, but he’s come to exchange some news and conversation with the Pequod’s crew.
One of the rowers in the boat from the Jeroboam is a man Stubb recognizes, about whom he heard a story from the crew of the Town-Ho (what gossips those Town-Ho sailors are). Here’s the story:
This man was raised in a Shaker community (by the way, the Shakers were a Protestant separatist denomination relatively prominent in the eighteenth and nineteenth centuries) in New York where he was heralded a prophet.
One day, though, this man decided to go on a whaling voyage.
The man seemed normal enough when he signed up, but after the Jeroboam set sail, he went crazy, announced he was the Archangel Gabriel, and gave everyone the heebie-jeebies.
The captain wanted to leave "Gabriel" at the next port, because he refused to work or follow orders, but everyone else was so afraid that Gabriel would curse the ship if they did that the captain had to keep him on so the whole crew didn’t desert.
Now Gabriel has the run of the ship, especially because he’s convinced some of the men that he controls the disease epidemic they’re experiencing. This concludes the story.
Back to the Pequod. Captain Ahab tells Captain Mayhew to come on board in spite of the disease, but Gabriel objects and drones on about the plague.
Luckily, the sea drowns out most of what he says.
Ahab asks if the Jeroboam has seen Moby Dick, and Gabriel starts prophesying destruction. Captain Mayhew takes this as his cue to tell his own story about Moby Dick:
After the Jeroboam left harbor, they hear about Moby Dick. Gabriel instantly decides that the White Whale is "the Shaker God incarnated" and warns everyone not to attack it.
A year or two later, they sight Moby Dick, and the chief mate, Macey, insists on hunting him.
With Gabriel standing on the masthead shouting prophecies of doom, Macey heads out with his boat and crew to hunt the White Whale. The whale turns on his boat and knocks him fifty yards away into the water, where he drowns; the boat and everyone else were left unharmed.
Gabriel convinces the rest of the men to call off the hunt, and everyone is more afraid of his prophecies than ever.
Ahab asks so many questions about Moby Dick that Captain Mayhew and Gabriel figure out he wants to hunt the White Whale; Gabriel continues to prophesy doom to anyone who tries.
Ahab orders Starbuck to look through the Pequod’s mailbag and find any letters for the Jeroboam’s crew. There’s only one—for the dead Macey. Gabriel tells Ahab to keep it, since he’ll be following Macey to destruction soon.
Ahab sticks the letter on a pole and holds it out to the boat, but Gabriel takes it, stabs through it with a knife, and throws the knife and letter together at Ahab’s feet. Symbolism…
The Jeroboam continues on its voyage, and the crew of the Pequod goes back to butchering Stubb’s whale.