One of the most popular and widely known characters in all of fiction, Sherlock Holmes has an enduring appeal based largely on his uncanny ability to make the most remarkable deductions from the most mundane facts. The very first words that Sherlock Holmes ever says to Dr. Watson are, "How are you? You have been in Afghanistan, I perceive." Watson responds, "How on earth did you know that?" And so a crime-solving legend is born.

In The Scientific Sherlock Holmes, James O'Brien provides an in-depth look at Holmes's use of science in his investigations. Indeed, one reason for...