Observation and Deduction

Where it surfaces

• The Red Thumbmark

  Thorndyke's methodical approach to the evidence exemplifies the power of careful observation and logical reasoning.

• My Learned Brother

  Thorndyke keenly observes Jervis and the visitors, demonstrating his deductive skills even in casual settings.

• II: The Suspect

  Thorndyke's careful examination of Reuben's hands and his note-taking demonstrate his methodical approach to uncovering the truth.

• III: A Lady in the Case

  Thorndyke and Jervis deduce from Miss Gibson's phrasing that someone has spoken ill of Reuben, highlighting the importance of perceiving the essential underneath the obvious.

• V: The “Thumbograph”

  Thorndyke deduces key facts from Jervis's notes, highlighting the importance of careful observation and inference.

• A Suspicious Accident

  Jervis constructs a hypothesis based on financial motives and Thorndyke's inductive method is praised.

• X: Polton Is Mystified

  Thorndyke demonstrates deductive reasoning by identifying a former stationmaster from his gait, critiquing Jervis's use of 'guess' and emphasizing conclusions based on data.

• The Ambush

  Thorndyke deduces the shooter's identity and method from minimal clues, and Jervis's careful observation of the projectile underscores the theme.

• XIII: Murder by Post

  Thorndyke uses careful observation of the label's typewriting, paper cutting, and other details to deduce the sender's identity and motives.

• A Startling Discovery

  Jervis uses the broken 'e' on the typewriter to deduce a possible link to Walter Hornby, demonstrating forensic observation.