Chapter 1

Instead of being the warm center of the world, the Middle West now seemed like the ragged edge of the universe.

Nick uses this simile, comparing the Midwest to the far edges of the universe, to explain how his hometown no longer felt like home after he returned from World War I, and why he felt compelled to move East.

Twenty miles from the city a pair of enormous eggs, identical in contour and separated only by a courtesy bay, jut out into the most domesticated body of salt water in the Western hemisphere, the great wet barnyard of Long Island Sound.

In this metaphor, Nick compares Long Island Sound to a barnyard and East Egg and West Egg to a pair of actual eggs, suggesting that humans have tamed and domesticated this area for their own purposes.

She was extended full length at her end of the divan, completely motionless, and with her chin raised a little, as if she were balancing something on it which was quite likely to fall. . . . Miss Baker’s lips fluttered, she nodded at me almost imperceptibly, and then quickly tipped her head back again—the object she was balancing had obviously tottered a little and given her something of a fright.

Nick uses an extended simile to characterize the condescending way that Jordan looks down her nose at him when they first meet, comparing her snobbish posture to that of a person trying to balance something on her chin. 

. . . wedging his tense arm imperatively under mine, Tom Buchanan compelled me from the room as though he were moving a checker to another square.

Here Nick uses a simile to convey Tom’s brute strength and commanding nature, likening himself (Nick) to a piece in a game of checkers that Tom can push around the board with minimal effort. 

As for Tom, the fact that he “had some woman in New York” was really less surprising than that he had been depressed by a book. Something was making him nibble at the edge of stale ideas, as if his sturdy physical egotism no longer nourished his peremptory heart. 

In this metaphor, Nick derides Tom’s obsession with the white-supremacist book “The Rise of the Colored Empires,” comparing the book’s ideas to stale bread that Tom is using to feed his sense of entitlement.  

Chapter 2

At 158th Street the cab stopped at one slice in a long white cake of apartment houses.

This metaphor compares a row of apartment buildings in New York to a white cake in which each building is a slice, suggesting that all of the buildings are identical and white.

Chapter 3

My incredulity was submerged in fascination now; it was like skimming hastily through a dozen magazines.

Nick compares Gatsby’s far-fetched yet fascinating life story to the sensational stories often found in magazines, and his own interest to that of a person gobbling up these magazine stories.

Chapter 6

"Perhaps you know that lady." Gatsby indicated a gorgeous, scarcely human orchid of a woman who sat in state under a white-plum tree. Tom and Daisy stared, with that peculiarly unreal feeling that accompanies the recognition of a hitherto ghostly celebrity of the movies. 
"She’s lovely," said Daisy. 
"The man bending over her is her director."

In this metaphor, Nick conveys the beauty and elegance of a movie star by comparing her to an orchid (a tall, slender flower) sitting under a white-plum tree. The tree may be another metaphor for her director, who is said to be “bending over her.”

Chapter 7

The prolonged and tumultuous argument that ended by herding us into that room eludes me, though I have a sharp physical memory that, in the course of it, my underwear kept climbing like a damp snake around my legs and intermittent beads of sweat raced cool across my back.

In this simile, Nick compares the uncomfortable clinging of his sweaty undergarments to the feeling of a wet snake crawling up his legs. This simile may also speak to his displeasure at becoming entangled in arguments between Tom, Daisy, and Gatsby. 

Chapter 9

So we beat on, boats against the current, borne back ceaselessly into the past.

In this metaphor, Nick likens humans to rowers unsuccessfully paddling against the current, struggling to reach an unattainable future while being carried backward toward past failures.