# XVIII: The Holmes Method explained — The Viaduct Murder

> Chapter companion for The Viaduct Murder by Ronald A. Knox.

## What happens

Gordon, Reeves, and Carmichael investigate the disappearance of the book containing the cipher. Carmichael uses deductive reasoning to deduce the physical characteristics of the thief from the arrangement of books and a used pipe-cleaner. Gordon and Reeves debate the plausibility of their theories about the murder, focusing on how Davenant could have known about Brotherhood's death and how the book ended up on the train.

## Themes in this chapter

### Detection and Rationality

Carmichael applies logical deduction to physical evidence (book arrangement, pipe-cleaner) to infer the thief's characteristics.

### Deception and Secrecy

The missing cipher book and the possibility of a club member or servant being the thief highlight ongoing secrecy and deception.

### Appearance vs. Reality

The apparent theft of the book and the debate over whether the book was left on the train on a different day challenge initial assumptions.

## Character check-ins

### Gordon Davenant

Debates the murder theory with Reeves, pointing out inconsistencies in the timeline and Davenant's knowledge.

### Mordaunt Reeves

Discovers the cipher book missing from his room; participates in the deduction of the thief's identity.

### Mr. Carmichael

Applies detective methods to examine Reeves' room, deducing the height and habits of the intruder.

### Marryatt

Mentioned in the context of the ongoing investigation, though not directly present.

### Miss Rendall-Smith

Referenced in the discussion about Davenant's motives and his interview with her.

## Key lines

> A book cipher is ordinarily prearranged between the two parties. Now, in this one it is very unlikely that it was prearranged, for the message looks as if it came from an enemy. Therefore the message could only be sent by someone who knew that Brotherhood was reading Momerie’s Immortality at the moment—knew, in fact, that the book was close to his hand.

Reeves argues that the cipher must have been sent by someone who knew Brotherhood was reading that specific book, making Davenant an unlikely suspect.

_Reeves deduces that the sender had intimate knowledge of Brotherhood's reading habits._

> I should say he was a man of about Gordon’s height.

Carmichael estimates the thief's height based on the position of the book on the shelf.

_Carmichael uses the shelf height and the need to balance to deduce the thief's stature._

> It suggests at least that he was a seriously minded person, and not all our fellow-residents are that.

Carmichael infers the thief's serious nature from the page the book was open to (Hamlet's 'To be or not to be').

_The choice of reading material provides a clue to the thief's character._

## Links

- HTML: https://www.betterreads.online/discover/the_viaduct_murder_se/chapters/xviii-the-holmes-method
- Book: https://www.betterreads.online/discover/the_viaduct_murder_se
- All chapters: https://www.betterreads.online/discover/the_viaduct_murder_se/chapters