What made Holmes the perfect hero for his times?
He exemplified all that the British admired. He was mentally brilliant, but pragmatically so. He had good taste, a good social and cultural background, the status of a scientist, with a love for good music--especially the violin--and fine tobacco (he can easily identify dozens of types of ashes). He has family connections in Europe, but is completely English, whereas most other detectives of the previous 50 years, such as Dupin, Tabaret, Lecoq and Vidocq, had been French.
In keeping with the European fascination with James Fennimore Cooper's Indian trackers, Holmes was a fine reader of footprints, hoof marks, and wheel tracks. Tracking constitutes a great deal of his stories, hence the deerstalker cap. Holmes has little use for modern criminology and often whines about a trail being ruined. In one case, he uses plaster to preserve footprints. He is often compared to a dog such as a foxhound or retriever. Watson has a bull pup (who we never see), and some suggest it is a figure of speech for a bad temper or an illegitimate son. Anyway -- like Cooper's Indians, Holmes goes tracking without food or water for days, and enters a trance-like concentration when working out a case.
Like Vidocq, he is a master of disguise and an actor, fooling Watson into believing he is an old man or an Italian priest. Also like Vidocq, he has remarkable physical strength and endurance, though he never works out. He prefers to lounge about in his famous robe, and he tends to smoke heavily: cigarettes, cigars, and his trademark calabash pipe.
Like Dupin, he has encyclopedic knowledge of criminal history. He is full of technical information, regards detection as a science, uses newspaper ads to bring suspects out into the open, breaks into people's thoughts, and believes that the more grotesque a mystery appears, the simpler the answer is. They both smoke, take long walks in the city at night, avoid women, and have eccentric interests.
For example, Holmes plays the violin while he's thinking. He studies philology, ancient manuscripts, and music of the Middle Ages. In "Scarlet", he says he has no use for the humanities and other impractical intellectual pursuits, and in "Hound" Watson recalls he is even uninterested in astronomy. But in later stories he quotes Shakespeare and Carlyle, and retires to bee-keeping and the study of Buddhism. He is a fine boxer, but we never see him exercise or practice. Instead, we see him struggle with a cocaine habit in "Sign of Four" and Watson, the good doctor, persuades him later in the canon to give it up. This would not strike Victorian readers as harshly as us, since cocaine at the time was openly marketed as a painkiller and was even advertised as a nerve-calming ingredient in Coca-Cola.
Poe has a Romantic notion of the bi-part soul, which Doyle adapted for Holmes. He is a rational drug addict, a lazy athlete, and he works with sloppy precision. He does not practice Japanese judo, yet he is an expert. He embodies men's fantasies of being an expert in things without working on it.
Both Dupin and Holmes have admiring, faithful chroniclers. Dupin's narrator reveals little about himself, but over 4 novels and 56 stories we learn much about Watson. Contrary to the bumbling Oliver Hardy image given to him in earlier movies, he is a handsome and strong (though injured) man, not as quick-minded as Holmes but not as dim-witted as some presume. He is always ready for an adventure (he went to Afghanistan, after all), and shows good humor and an eye for the ladies. Watson is perhaps Doyle's most pleasing innovation.
The contrasts to Poe are dramatic, too. Poe uses the tales to illustrate a point about the power of pure analysis, using a near mathematical approach with little narrative detail or action. The characters are lightly drawn, and they do not converse or act normally. Dupin is never wrong, never misled. But Doyle's stories are full of movement. People of all classes bring their problems to Holmes. Much of the action takes place before our eyes: chasing hansom cabs in the streets, running over fields, inspecting rooms. Holmes is, on occasion, baffled. In one story he is wrong.
Poe was unfamiliar with Paris and it is used merely as a backdrop. But Doyle knew Victorian London and made it part of his plots, with its fog, cabs, gaslights, docks and train stations, cathedrals and opium dens (hmmm--shades of Dickens).
Doyle managed to restrain sensation to acceptable limits and explain Holmes' deductions in an entertaining way. By doing this, he appealed to two kinds of mystery readers: the uncritical public interested in crime stories for their own sensational sake to forget about their miserable factory jobs for a while, and intellectual readers who found satisfaction in the closely reasoned puzzles.
At first, it appears that Doyle, himself a doctor, is creating the first 'scientific' detective in an age enamored with scientific progress. We meet him in a chemistry lab at Bart's Hospital, elated about a test for detecting hemoglobin in stains. However, he does not reason as a scientist or use scientific experiments to solve cases (one one occasion he uses test tubes and litmus paper). Yet readers of the 1890s were not ready for Quincy M.E. or Scarpetta or CSI or NCIS and all the shows that have forensic labs. In "Scarlet", Holmes believes Drebber was poisoned but he does not analyze the pills. He gives them to the landlady's dog, and the terrier's instant death proves the drug is lethal. In "The Devil's Foot" he suspects a burning brown powder has killed Brenda Tregennis and driven her brothers insane, but does he send it to a lab? Nope. He tests it on himself and Watson with nearly fatal results!
Early on, we see Holmes beating corpses to test for bruises, but he never uses post-mortem tests in a case. The public was not ready for a detective with a scalpel. They could understand one with a magnifying glass.
So, Holmes' use of 'science' is a veneer pasted over romanticized plots that exalt Watson's common sense and Holmes' intuitive genius. Like his heroes in the historical novels that flopped, Holmes is a chivalrous man who is fearless before the strong and humble to the weak, Victorian qualities found most often in schoolboy stories of the period. Doyle successfully applied the morality of schoolboy stories like "Tom Brown's Schooldays" and "Boy's Own Paper" that show a strong upperclassman and an awestruck tag-along underclassman. It is no wonder that Lord Baden-Powell, founder of the Boy Scouts, found Holmes to be a perfect role model of self-reliance, loyalty, and moral fitness for English boys responsible for the future of an empire. In these schoolboy stories we learn that public schools are for the moral training and character-building of 'gentlemen' who will 'quit themselves like men', 'do their duty', and influence generations yet unborn by a deportment that will 'strike out if necessary for whatever is true and manly'. Boys were taught to oppose bullies and take one's licks with a proper stiff upper lip when he feels he is in the right.
So Holmes stories are not innocent entertainment. They are, like other schoolboy stories of the period, filled with an imperial ideology meant to uphold and justify the values of Victoria's Empire. Like other detective stories in general, they declare that good wins over evil and order over chaos, but more than that, these declare that British order and efficiency will win over the chaos of the world. Not even World War I shattered this artifice.