1. Explore the psychological theories prevalent in the late nineteenth century and analyze how Doyle integrates these concepts into his story. You might choose to focus on a specific area of psychology, a related discipline like criminology, or the theories of a particular psychologist.

2. Investigate German composers whose works were commonly performed towards the end of the nineteenth century. Use this research to infer additional insights into Sherlock Holmes' character based on the story's mention of his musical preferences. You could also look into Italian and French music from the same period, which Holmes does not favor. What does this contrast in musical tastes reveal about Holmes?

3. Study the cultural dynamics in turn-of-the-century America that might explain the popularity of the Sherlock Holmes stories. You could identify particular developments in American society that parallel the British ones noted in this entry. Alternatively, you might explore distinctive aspects of American life, thought, or preferences during this period that would make Doyle's stories appealing to American readers for different reasons than those of British readers.