Answer:
It provides a contrast between what Morrison had known all his life as normal, and what he now sees in the rich lady's house.
Explanation:
Hoover's vacuum cleaner was the common and most popular vacuum cleaner at that time, which had to be heated by fire before it could work. Seeing a vacuum cleaner that was not heated by fire in the lady's house was new to Morrison.
He generalized and categorized all vacuum cleaners as working in the same manner as Hoover's vacuum cleaner. Now seeing a different kind of vacuum cleaner was strange to Morrison
