Final answer:
The sentence is an example of a simile.
Step-by-step explanation:
The sentence, 'The desert traveler's hopes were dashed, as when at last he reached a well, it was as dry as a bone,' is an example of a simile. A simile is a figure of speech that compares two things using the words 'like' or 'as'. In this sentence, the well being as dry as a bone is being compared to the desert traveler's dashed hopes.
Learn more about simile