BBC magazine has details on how.
Also found another article there in which John Gray tries to explain the long-standing appeal of Sherlock Holmes -
"Aside from a few relics of Victorian rationalism who find a curious comfort in Darwinism, most of us now accept that reason can't give meaning or purpose to life. If we're not content with the process of living itself, we need myths and myths very often contain contradictions.
Holmes is one such myth. Seeming to find order in the chaos of events by using purely rational methods, he actually demonstrates the enduring power of magic."