One of Dr. Watson’s patients who works at Paddington Station brings him another patient one morning, a passenger who had just arrived at the station missing his thumb. The young man has a strange story to tell, and Dr. Watson takes him to his friend Sherlock Holmes. The young man is a hydraulic engineer. Work has been scarce, so he jumped at an opportunity that presented itself the day before to examine a machine in a Berkshire village used for processing fuller’s earth. The fee offered seems too good to be true. That should have been the engineer’s first cue to decline the job. He goes where he’s instructed, and he pays for his experience with the loss of his thumb. Sherlock Holmes sees behind the bizarre events of the night before to determine their cause. Conan Doyle uses the descending ceiling trope in this story. Perhaps it wasn’t as much of a cliché then as it has become now. ( )

Another superb short story from Sir Doyle. Plot is quite interesting:
In his narration, Dr. Watson notes that this is one of only two cases which he personally brought to the attention of Sherlock Holmes.
The story, set in 1889, mainly consists of a young London consultant hydraulic engineer, Mr. Victor Hatherley, recounting strange happenings of the night before, first to Dr. Watson, who dresses the stump where Mr. Hatherley's thumb has been cut off, and then to Sherlock Holmes himself.
Hatherley had been visited in his office by a man who identified himself as Colonel Lysander Stark. He offered Hatherley a commission at a country house, to examine a hydraulic press used, as Stark explains, to compress fuller's earth into bricks. Stark warned Hatherley to keep the job confidential, offering him 50 guineas (£52 10s, an enormous sum at the time, worth over £4000 today[1]). Hatherley felt compelled to take this work, despite his misgivings, as his business was newly established and he had very little work.
Upon arriving late at night at the appointed train station, Hatherley is met by Colonel Stark and is driven a considerable distance in a carriage with frosted glass windows to the house where he is to examine the machine. (A minor detail is that the house was actually quite near the station; Holmes realizes that the carriage drove "six [miles] out and six back" to disguise the house's location from Hatherley.) Hatherley is still under the spell of the 50 guineas and does not become afraid even when a woman at the house warns him to flee. He is presently shown the press and makes his recommendations as to needed repairs. Then, he rashly decides to inspect the press more closely. His discovery that its floor is covered by a "crust of metallic deposit" confirms his suspicion that the machine is not used for pressing fuller's earth. Hatherley narrowly escapes getting crushed to death when Stark turns the machine on him, but he escapes the press with the aid of the woman. Pursued by the murderous Stark, Hatherley is forced to jump from a second story window, in the process getting his thumb severed by Stark's cleaver. Hatherley survives the fall but passes out in the rose-bushes, coming to hours later by a hedge near the rail station.
Holmes then makes sense of the happenings, recognizing Stark and his allies as counterfeiters, but he, Watson, and the police arrive too late: the house is on fire, and the perpetrators have fled. Ironically, the press was destroyed when Hatherley's lamp was crushed inside it, setting the machine on fire and ruining the criminals' operation, although they escaped with several "bulky boxes" presumably containing counterfeit coins.
This case is one of the few where Holmes fails to bring the villains to justice. (Others include The Five Orange Pips, The Adventure of the Greek Interpreter and The Hound of the Baskervilles, though in all these cases Providence exacts vengeance on the villains.)
I recommend this book to all readers that love a well written mystery and of course to those who appreciate Sherlock Holmes adventures. ( )