Final answer:
The author is using irony when Gulliver praises the emperor to criticize the emperor.
Step-by-step explanation:
The author is using the literary device of irony when the character Gulliver praises the emperor. Irony is a figure of speech in which words are used in such a way that their intended meaning is different from the actual meaning. In this case, the author is actually criticizing the emperor, despite Gulliver's praise.
For example, when Gulliver praises the emperor's wisdom and generosity, the author is using irony to show that the emperor is actually lacking in these qualities.
This use of irony creates a contrast between what is said and what is actually meant, adding depth to the author's criticism of the emperor.