gunpowder Melville here refers to the commonly held theory that gunpowder -- an explosive combination of saltpeter and sulfur -- originated in Asia. Gradually, it moved westward eventually reaching Europe sometime in the 13th century.
halyards One of various ropes or tackles used for raising and lowering a sail, yard, spar, or flag.
Ham Most commonly, Ham refers to the third of Noah's sons and the father of Canaan. The story in Genesis (9:18-27) relates the following: When Noah, drunk and naked, fell asleep, Ham saw him in his tent and reported the sight to his brothers. Averting their eyes, the elder sons covered their father with a garment. As a punishment for his voyeuristic son, Noah pronounced a curse upon him and his descendants: "Cursed be Canaan [the son of Ham]; a servant of servants shall he be to his brethren."
hands The term stands for members of a ship's crew.
hatchways Hatchways are the openings in a ship's deck through which cargo can be moved to the hold. More generally, hatchway is the term for any passageway from one deck to another.
Hauser, Caspar Hauser (1812?-1833) appeared mysteriously in Nuremberg, Germany in 1928, Popularly imagined to be of noble birth, his presence aroused international attention. He was assassinated in 1833.
Hawthorne, Nathaniel Hawthorne (1804-1864), with Melville a giant of American literature, was especially concerned with probing the darker side of human nature. A sometime friend of Hawthorne's, Melville here refers to the short story "The Birthmark."
Hyperion The Titan who was god of the sun until Apollo defeated him. Once again, Billy's comparison to a mythical figure serves to elevate his stature.
heinous Grossly wicked or reprehensible; abominable: a heinous crime.
helmsman The sailor charged with piloting the ship.
Hercules The demigod son of Zeus and the mortal Alcemene whose very name evokes the idea of physical strength. He used his great abilities to perform the Twelve Labors, including killing the Nemean Lion, capturing the Ermanthian Boar, and freeing Prometheus. As he states explicitly, Melville uses Hercules as the prototypical strong man.
Hesperides The Hesperides, the Nymphs of the Setting Sun, were the three sisters who lived in the extreme west near the edge of the ocean at the foot of Mount Olympus. Their primary purpose was to guard the garden of Zeus's wife, Hera, in which the golden apples grew. After Hercules successfully carried away the golden apples, they were turned into trees. Melville here refers to the painting by Renaissance artist Fra Angelico, The Garden of the Hesperides. Melville recalls the classical beauty of Fra Angelico's painting.