Of all the problems which have been submitted to my friend, Mr. Sherlock Holmes, for solution during the years of our intimacy, there were only two which I was the means of introducing to his notice — that of Mr. Hatherley’s thumb, and that of Colonel Warburton’s madness.
The Engineer’s Thumb is singular for how immaterial Holmes is to the plot. His photographic memory is useful in linking the engineer’s strange story to a past crime, and his lateral thinking helpful in locating the site of the crime, but by and large the story is taken up with Watson’s discovery of the engineer and the recitation of his experience. Holmes and Watson travel outside of London, but somehow the story seems less dynamic than many a mystery solved entirely within the confines of 221B.
Inspector Bradstreet, one of the Yard’s more creditable detectives, realises almost as quickly as Holmes which criminal gang is behind the engineer’s curious tale, and yet Conan Doyle still has them escape, rendering the reader’s disappointment two-fold: they are robbed both of an involving deduction and of a satisfying resolution. The Engineer’s Thumb reminds one of The Five Orange Pips: Holmes illustrates his simple solution by pulling a book from a shelf, and the villains remain both anonymous and a little preposterous.
The machine which Victory Hatherley, our dethumbed engineer, is asked to inspect is an absurd McGuffin, designed primarily, it would seem, for the scene, belonging more in a horror story than in detective fiction, in which poor old Hatherley is almost crushed to death, like Han Solo and Luke Skywalker in the trash compactor. “Had I the nerve to lie and look up at that deadly black shadow wavering down upon me?” he asks, and yet we are later informed that this press the size of a room was designed for pressing coins.
Still, at least Conan Doyle here shapes his story around an actual substance – fuller’s earth – rather than a fictional type of snake, as in The Speckled Band. Where his stories are often fantastical, they are at least always stronger when they are rooted in something more than Victorian derring do. And this story contains nuggets of moderate interest: the paragraph about Hatherley’s despair as his new small business fails to take off feels as heartfelt as it surely should coming from Doyle, who famously failed to persuade many patients to use his early practice; and likewise Watson’s wry comment that a full and, dare we say it, flowery account of a crime will always tease more from a narrative than a dry newspaper column on the same subject.
The story is not without wit, then, but it is without much in the way of a real mystery. Watson seems to admit this early on – “it gave my friend fewer openings for those deductive mthods of reasoning by which he achieved such remarkable results” – but we are therefore left wondering why Conan Doyle wrote the story in the first place. Perhaps he was in a Poe patch – that central scene in the pressing room recalls The Pit and the Pendulum. If so, the reader is left wishing for a return to Holmes over horror.