Poirot, M. Bouc, and Dr. Constantine reconvene. M. Bouc again stresses his confusion with the case and the opinion that none of the passengers’ testimony has given any definite evidence, or at least he “did not observe it.” Poirot responds, “That is because you did not listen.”
Here, Poirot chastises M. Bouc for discounting the evidence they’ve gathered, saying he “did not observe” because he “did not listen.” This echoes a classic line of Sherlock Holmes, who had chided Watson in a similar way: “You see, but you do not observe.” This places Poirot and M. Bouc in a Holmes/Watson relationship, which bears out as Poirot is consistently in a position of explaining his thinking to M. Bouc. More significantly, Poirot’s choice of verb (“listen” rather than Holmes’ “see”) distinguishes their approach to detective work. Sherlock uses the eye to detect fine elements of physical evidence while Poirot uses the ear to measure witness testimony and find clues to their psychological states.
Poirot offers a significant detail as an example: MacQueen said he was brought on to assist Ratchett with languages, yet the voice that answered from Ratchett’s cabin at twenty-three minutes to one spoke in idiomatic French. M. Bouc finds this to be proof that Ratchett was dead at this time, but Poirot cautions that they don’t know that definitively.
Poirot’s facility with languages makes him especially attentive to nuances, such as whether a French statement might have been spoken by a native speaker. Clearly, Ratchett was not the one answering. Whether Ratchett was alive or not at this time, a fluent French speaker was with him in his cabin.
They return to the matter of the stopped watch. Poirot reasons that if the watch was altered, it must have some significance, and that they should look for someone with a reliable alibi for that time.
Poirot continues with his exceedingly careful approach, speaking, as he did in the case of the conductor’s uniform, in terms of conditional statements. If the stopped watch was altered, it would have been done to turn suspicion away from someone who had a solid alibi for that time.
Then, Poirot assembles a list of the identities of the passengers, complete with alibis and distinguishing information. Each is vouched for by at least one other passenger and most have either no motive or no evidence against them. They are of various nationalities. Colonel Arbuthnot has the evidence of the pipe-cleaner in Ratchett’s room. Princess Dragomiroff has a strong motive, as she was very close to the Armstrongs.
The list of suspects and their essential information is as much a clarification for the reader of the novel as it is a helpful guide for Poirot. The amount of information involved is considerable, and a reader needs a way to synthesize it at a glance. The list primarily shows a web of alibis offered for each passenger by others, and no suspect seems likelier than another except Princess Dragomiroff, who seems incapable of the physical act of the crime.