Final answer:
In Chapter III of The Great Gatsby, the narrator describes the scenes at one of Gatsby's parties using a simile of a grand orchestra, conveying the grandeur and extravagance of the parties.
Step-by-step explanation:
In Chapter III of The Great Gatsby, the narrator describes the scenes at one of Gatsby's parties using a simile. He says, 'By seven o'clock, the orchestra has arrived, no thin five-piece affair, but a whole pitful of oboes and trombones and saxophones and viols and cornets and piccolos, and low and high drums.' This simile compares the size and variety of the orchestra to a whole pitful of instruments, creating a vivid image of the grandeur and extravagance of Gatsby's parties.