In the Sign of Three, we learn of a murder and an attempted murder in which the assailant had hidden an extremely sharp blade on the inside of a belt. The blade is so sharp that the victim doesn't notice the resulting wound, and does not bleed until the belt is removed, at which point he exsanguinates.
In the case of the first victim, why did he start bleeding in the shower, and not when he disrobed? Are we to understand that he didn't take his belt off until he was already in the shower?
Actually assailant didn't hide the blade inside the belt. He stabbed the victim with the sharp knife and because of the tightness in muscle victim didn't realize the wound until it began to bleed.
If you watch closely you can notice that Bainbridge's face was pale before going to the shower. So we can assume that internal bleeding had started. As he removed the belt bleeding started slowly. He just came out of a long over one hour guard without any muscle twitches. Thus not sensing external injuries. Even if you stand for 1 hour still you won't feel certain things.
Yes he had removed the belt before entering the shower but maybe he hadn't remove the inner shirt. So he can't see the blood.
The attempted murders in The Sign Of Three have some similarities with the real-life assassination of Empress Elisabeth of Austria, who was stabbed with a very thin blade.
Because of the sharpness and thinness of the file the wound was very narrow and, due to pressure from Elisabeth's extremely tight corseting, the hemorrhage of blood into the pericardial sac around the heart was slowed to mere drops. Until this sac filled, the beating of her heart was not impeded, which is why Elisabeth had been able to walk from the site of the assault and up the boat’s boarding ramp. Had the weapon not been removed, she would have lived a while longer, as it would have acted like a plug to stop the bleeding.
So perhaps it's not quite as absurd as it appears.
Yes, it is ridiculous. Also, I don't think that the blade was hidden on the inside of the belt but that the murderer stabbed through the belt with the "very sharp knife"
I also agree with you that the murder victim would not have turned the shower on and then dis-robed.
I'm also not sure that if this murder technique had worked that he would have died so fast.
Delta fibers (aka slow pain fibers) carry sensations of pressure, pain, and cold if I remember correctly. Applied pressure can "crowd out" slow pain conduction. What's the first action you take after stubbing your toe? You rub it. It's the same methodology that chiropractors use with "manipulations" very rarely is anything actually "manipulated" but rather a quick applied pressure occurs at the injury site which does the aforementioned small digression, but pertinent. Anyone who has experienced severe back pain can attest to an almost miraculous resolution of pain. Termed the "Gate theory of pain", while nerves can convey multiple signals at once, we process them singularly, meaning the "gate", or your processing of sensory data, has been confounded at the gate.
Apply this pressure to a stab wound and you'll likely get the same result. Unfortunately your fast pain fibers large and well myelinated (think of a large and well insulated conduit) has its own specific pathway that is difficult to occlude. Thus the victim may have felt the initial sharp stab of pain of the dagger, but would have been spared (and so confounding the victims perception of the event) the dull aching pain that would typically follow the initial sharp jolt of pain. Had the guard winced briefly (albeit they are likely trained not to, but physiology is a bitch) it would have made the entire event more plausible. That said, it is very possible that the guard could have stood for another hour with the pressure signals from his belt occluding the dull pain signals that were likely present, but not received so to speak.
There is also evidence - this is slightly tangential but again relevant - that we tend to receive the signals we are familiar with rather than ones we are not, creatures of comfort and habit we are. I.e. the guard was quite familiar with the pressure sensation of his belt while on duty - that makes sense to him - therefore the dull pain signals are being fought on 2 different fronts: 1. A real physiological mechanism, and 2. His own minds hard wiring to gravitate towards familiar sensations rather than foreign ones.
