chunk: During their stay on the island, the group endures bad weather, and domesticates an orangutan, Jupiter, abbreviated to Jup (or Joop, in Jordan Stump's translation). There is a mystery on the island in the form of an unseen deus ex machina, responsible for Cyrus' survival after falling from the balloon, the mysterious rescue of Top from a dugong, the appearance of a box of equipment (guns and ammunition, tools, etc.), and other seemingly inexplicable occurrences.
  The group finds a message in a bottle directing them to rescue a castaway on nearby Tabor Island, who is none other than Tom Ayrton (from In Search of the Castaways). On the return voyage to Lincoln Island, they lose their way in a tempest but are guided back to their course by a mysterious fire beacon.