Moriarty (simile)
"He sits motionless, like a spider in the center of its web, but that web has a thousand radiations, and he knows well every quiver of each of them. He does little himself. He only plans.”
When Sherlock explains to Watson the powers which Moriarty wields over London, he uses the simile of a spider in the centre of a web. Moriarty is the centre of the crime web of London, controlling and benefiting off many of the smaller crimes committed by those in his hire. Although he himself never leaves his 'web' to commit crimes, Sherlock believes that Moriarty is one of the most powerful and dangerous figures in England and that he has the power to stop him.
Animals (simile)
"He bellowed like a bull and rushed for the door"
"Cringed alone at my companions side like a dog with its master"
Characters are often referred to casually as being like various animals in order for Doyle to explain their actions and mannerisms to the reader. The two examples show both the raging and docile side of this usage as the two characters react to Holmes in their own way.
A fire in a snow storm
"The sight of it was to me like a fire in a snow-storm"
This simile is used to express the joy of a prisoner in seeing a man who was calm and happy in his situation in jail. Surrounded by gloom and sadness left the speaker in a metaphorical snowstorm, yet his neighbouring prisoner, who later helps him escape but turns out to be cruel and murderous, is all warmth and fiery to him.
Professor (metaphor)
"He held it up and tapped on it with his long, thin fore-finger, as a profesor might who was lecturing on a bone"
Sherlock can easily be seen as a professor figure in the collection, as he can never help but teach others the methods with which he conducts his deductions. Although often he regrets his lecturing, as he finds people to be far less impressed when they convince themselves that the business was simple, he continues to take on the role of both detective and teacher for his clients.
As true as a stock to a barrel
"'I'd a partner,' said he, 'a rare good man, as true as a stock to a barrel'"
A criminal describing his partner in crime as "a rare good man" seems an oxymoron to most readers, yet to mind of the speaker he is a man that can be trusted in taken part in his fair share of murder and other such crimes.
