Ratiocination Quantified

A Digital Humanities Analysis of Poe's Influence on Doyle

Poe: "The Purloined Letter" (1844)
Doyle: "A Scandal in Bohemia" (1891)

Research Overview

"Dupin was better. Dupin was decidedly smart." — Doyle's manuscript notes, later revised to "Dupin was a very inferior fellow"
Methodology: This analysis uses computational text analysis to quantify literary influence across six dimensions: dialogue patterns, character proximity networks, narrative structure positioning, character attributes, spatial organization, and sentence-level stylometrics. Click on any metric below for detailed data and methodology.
88%
Narrative Structure Similarity
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85.7%
Character Attribute Overlap
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56.8%
Stylometric Similarity
Click for details →

Narrative Structure Analysis

We identified 7 key story elements and measured their position (0.0 = beginning, 1.0 = end) in each text. Similarity = 100% minus mean positional difference.

Story ElementPoe PositionDoyle PositionMatch
Crime/Problem Introduction0.4550.406✓ Close
Detective Observation0.4790.493✓ Very Close
Resolution Revealed0.5250.511✓ Very Close
Police/Official Bafflement0.4780.075✗ Divergent
Detective Explains Method0.650.72✓ Close

The 88% similarity indicates both authors structure their detective stories with remarkably similar narrative beats, except for where official failure is revealed.

Character Attribute Overlap

We extracted 50-word context windows around character mentions and identified 8 attribute categories using keyword matching. Overlap = shared attributes / total attributes.

AttributeDupinHolmesShared?
Observant4 instances20 instances
Intellectual2 instances5 instances
Eccentric4 instances2 instances
Analytical3 instances4 instances
Reclusive3 instances2 instances
Physically Distinctive2 instances3 instances
Aristocratic5 instances1 instancePartial
Encyclopedic Knowledge1 instance8 instancesPartial

Stylometric Analysis

Sentence-level metrics measuring prose style. Similarity calculated as normalized inverse difference across 6 metrics.

MetricPoeDoyleDiff
Mean Sentence Length34.2 words23.1 words+11.1
Max Sentence Length296 words104 words+192
Parentheticals/1000 words16.52.6+13.9
Semicolons (total)8214+68
Complex Sentence Rate25.8%13.0%+12.8%
Type-Token Ratio0.2450.223+0.022

The low 56.8% similarity reflects Doyle's deliberate modernization of prose style for magazine serialization.

Key Finding: Doyle adopted Poe's deep structure (narrative architecture, character types, relationship topology) while adapting surface features (prose style, spatial organization, narrator agency) for commercial appeal.

Similarity Breakdown

Click any metric to see methodology and detailed data:

Narrative Structure Click for details 88%
88%
What it measures: Position of key story elements (crime introduction, detective observation, resolution, explanation) within the narrative arc.

Method: Pattern matching to detect 7 story beats; record position as percentage through text; calculate mean positional difference.

Interpretation: Both authors place crime ~40-45% in, observation ~48%, and resolution ~51-52%. This tight clustering indicates Doyle internalized Poe's narrative formula.
Character Attributes Click for details 85.7%
85.7%
What it measures: Overlap in character traits between analogous figures (Dupin/Holmes, Narrator/Watson, etc.).

Method: Extract 50-word windows around character mentions; match against 8 attribute lexicons (observant, intellectual, eccentric, etc.); calculate Jaccard similarity.

Interpretation: Dupin and Holmes share 6 of 7 core attributes. The primary differences are aristocratic emphasis (Poe) vs. encyclopedic knowledge (Doyle).
Relationship Topology Click for details 75%
75%
What it measures: Similarity in character relationship networks based on textual proximity.

Method: Count character co-occurrences within 50-word sliding windows; build weighted network graph; compare edge distributions between analogous character pairs.

Interpretation: Both texts have detective-narrator as strongest bond, narrator as central hub. Doyle's network is more distributed; Poe's clusters tightly around Dupin.
Prose Style (Stylometrics) Click for details 56.8%
56.8%
What it measures: Sentence-level prose characteristics including length, complexity, and punctuation patterns.

Method: Calculate 6 metrics (mean/max sentence length, parentheticals, semicolons, complex sentences, type-token ratio); normalize differences; average.

Interpretation: Greatest divergence. Poe: ornate, complex sentences (mean 34.2 words). Doyle: shorter, punchier (mean 23.1). Reflects commercial modernization for The Strand.

Dialogue & Verb Analysis

Surprising Finding: Poe's story is 88.5% dialogue — more than Doyle's 62.2%. But they serve different functions: philosophical dialogue (Poe) vs. action narration (Doyle).
Methodology: Dialogue ratio = characters within quotation marks / total characters. Verbs were classified into cognitive (thinking/perceiving) and action (physical movement) categories using a curated lexicon of 50+ verbs per category.
Text Composition: Dialogue vs. Narration

Poe: 88.5% Dialogue

88.5%

Characters talk about thinking. Dupin lectures on ratiocination; the Prefect reports failures verbally. All key events happen offstage and are reported through speech.

Doyle: 62.2% Dialogue

62.2%

Narrator describes action. Watson follows suspects, witnesses events, describes disguises visually. Scenes unfold before the reader's eyes.

Cognitive Verbs (thinking, perceiving, reasoning)

Cognitive Verb Frequency Click to see examples →

Poe
Ratio: 0.75
Doyle
Ratio: 0.37

Cognitive verbs indicate mental activity. Ratio = cognitive verbs / (cognitive + action verbs).

Poe's Top Cognitive Verbs
think 24
know 19
observe 15
suppose 12
perceive 8
reason 7
Doyle's Top Cognitive Verbs
know 18
think 11
see 9
understand 5
observe 4
imagine 3
Action Verbs (physical movement, doing)

Action Verb Frequency Click to see examples →

Poe
Ratio: 0.25
Doyle
Ratio: 0.63

Action verbs indicate physical activity. Higher ratio = more narrated movement and events.

Poe's Top Action Verbs
take 8
leave 5
enter 3
sit 3
walk 2
seize 2
Doyle's Top Action Verbs
come 28
go 22
take 19
run 12
walk 11
drive 8
Interpretation: Doyle's higher action verb ratio (0.63 vs 0.25) confirms the shift from armchair to street-level detection. Watson narrates movement through London; Poe's narrator sits and listens.

Character Proximity Networks

What the numbers mean: Edge numbers show co-occurrence count—how many times two characters appear within 50 words of each other. Higher count = stronger textual relationship. Click any character node for detailed information.
Methodology: Character positions identified via regex pattern matching (including pronouns for narrators). Co-occurrence counted using 50-word sliding windows. Network edges weighted by count; node size by total mentions.

Poe: The Purloined Letter

118 73 86 20
Dupin
Narrator
Minister D
Royal
Lady
Prefect

Doyle: A Scandal in Bohemia

264 115 191 63
Holmes
Watson
Irene
Adler
King
Norton
Character Role Alignment
Role Poe Character Mentions Doyle Character Mentions
DetectiveDupin34Holmes58
NarratorNarrator199Watson396
AntagonistMinister D20Irene Adler28
ClientRoyal Lady13King44
SupportingPrefect30Godfrey Norton12
Detective
Narrator
Antagonist
Client
Supporting

Narrative Structure: 88% Similarity

Story Beat Alignment: Both authors position crime introduction, detective observation, and resolution at nearly identical points in the narrative arc—evidence that Doyle internalized Poe's formula.
Methodology: Pattern matching identified 7 story elements using keyword triggers. Position recorded as decimal (0.0 = start, 1.0 = end). Similarity = 100% - (mean positional difference × 100).
Story Element Positioning
Start (0.0) Middle (0.5) End (1.0)
Crime Intro
Detective Observes
Resolution
Police Baffled ⚠️
Explanation
Poe Doyle
Story ElementPoe PositionDoyle PositionDifference
Crime Introduction0.4550.4060.049 ✓
Detective Observes0.4790.4930.014 ✓
Resolution0.5250.5110.014 ✓
Police Baffled0.4780.0750.403 ✗
Detective Explains0.650.720.07 ✓
Notable Divergence: "Police Baffled" appears at 0.478 in Poe (midpoint) vs 0.075 in Doyle (opening). Doyle front-loads the problem setup to create space for active investigation scenes.

Spatial & Narrative Space Analysis

Fundamental Difference: Poe's nested narrative structure contains all spaces within Dupin's library—events are reported, not shown. Doyle's narrative moves physically through London—Watson witnesses action in real time.
Methodology: Named Entity Recognition (spaCy) extracted place names. Each location classified as: Real (verifiable), Conjectured (fictional but mapped to likely inspiration based on scholarly research), or Reported (mentioned but never visited in narrative). Movement scenes counted by action verbs + location co-occurrence.
Narrative Space Structure

Poe: Nested/Contained Space

All action contained within one room; other spaces exist only in speech

📚 Dupin's Library (No. 33 Rue Dunôt)

Primary setting — entire story takes place here

Minister's Hotel REPORTED

Where letter hidden — described by Prefect, never visited

Royal Boudoir REPORTED

Where theft occurred — mentioned, never shown

Vienna REPORTED

Where Minister wronged Dupin — backstory only

0 movement scenes — armchair detection

Doyle: Linear/Mobile Space

Watson physically moves through London; reader witnesses action

🏠 221B Baker Street
Opening: Watson visits Holmes
cab ride
🏘️ Briony Lodge, St. John's Wood
Surveillance, disguise, smoke-rocket scheme
follows cab
⛪ Church of St. Monica
Watson witnesses wedding
walks
🏨 Langham Hotel
King of Bohemia's residence

8 movement scenes — street-level detection

Interactive Location Map

📍 Poe's Paris (1844)

⬥ Rue Dunôt, Faubourg St-Germain

Dupin's library — entire story takes place here

CONJECTURED → Rue du Bac area
● Faubourg Saint-Germain

Aristocratic Left Bank district — Dupin's neighborhood

REAL — still exists
⬥ Minister's Hotel

Where the letter is hidden — only described, never shown

REPORTED ONLY
⬥ Rue Morgue

Reference to earlier Dupin story — symbolic name

FICTIONAL — "Street of the Dead"
● Vienna

Where Minister D— wronged Dupin

REAL — backstory reference

Note: Poe never visited Paris. His geography is atmospherically evocative but invented.

📍 Doyle's London & Europe (1891)

● 221B Baker Street

Holmes's residence — opening and closing scenes

REAL — street exists (221B fictional in 1891)
⬥ Briony Lodge, Serpentine Avenue

Irene Adler's residence — surveillance scenes

CONJECTURED → Langford Place, St. John's Wood
⬥ Church of St. Monica

Wedding scene — Watson witnesses

CONJECTURED → Edgware Road area
● Langham Hotel

Where the King stays — still exists today

REAL — Doyle dined here with Oscar Wilde (1889)
● Regent Street

Gross & Hankey's jewelers — Holmes in disguise

REAL — major shopping street
● Edgware Road

Route to church — mentioned in dialogue

REAL — major London road
● St. John's Wood

Affluent area where Irene Adler lives

REAL — known for private villas
● Inner Temple

Godfrey Norton's legal chambers

REAL — Inns of Court
● Bohemia (Prague)

Kingdom of the client — now Czech Republic

REAL — historical region
⬥ Cassel-Felstein

Part of King's title — fictional German duchy

CONJECTURED → Kassel (spelled "Cassel" until 1926)
● Warsaw

Where King met Irene Adler years ago

REAL — backstory reference
● Holland

Reference to Holmes's case for Dutch royal family

REAL — mentioned case
● Odessa

Reference to Trepoff murder case

REAL — Ukraine
Spatial Metrics Comparison
MetricPoeDoyle
Settings Shown (reader visits)15+
Settings Reported Only30
Named Locations (total)514
Movement/Travel Scenes08
Verifiable Real Locations29
Conjectured Locations33
Geographic ScopeParis + ViennaLondon + 5 European locations

Stylometric Divergence: 56.8% Similarity

Greatest Divergence: Prose style shows the lowest similarity of any metric. Doyle deliberately modernized Poe's ornate style for magazine serialization and mass readership.
Methodology: Sentence boundaries detected using spaCy. Metrics calculated: mean/max sentence length, parenthetical count (text in parentheses or dashes), semicolon/em-dash frequency, complex sentence rate (sentences with 2+ clauses), type-token ratio (unique words / total words).
MetricPoeDoyleDifference
Mean Sentence Length34.2 words23.1 words+11.1
Max Sentence Length296 words104 words+192
Parentheticals/1000 words16.52.6+13.9
Semicolons (total)8214+68
Em-dashes (total)6712+55
Complex Sentence Rate25.8%13.0%+12.8%
Type-Token Ratio0.2450.223+0.022

Poe's Prose Style

"The measures adopted were not only the best of their kind, but carried out to absolute perfection. Had the letter been deposited within the range of their search, these fellows would, beyond a question, have found it."
  • Long, complex sentences (avg 34.2 words)
  • Heavy use of parenthetical insertions
  • Abundant semicolons and em-dashes
  • Latinate, elevated vocabulary
  • Multiple subordinate clauses

Doyle's Prose Style

"The door opened. A lady came out. She was a very handsome woman."
  • Short, punchy sentences (avg 23.1 words)
  • Conversational, direct tone
  • Simple clause structures
  • Accessible, everyday vocabulary
  • Visual, cinematic descriptions
Commercial Strategy: Writing for The Strand Magazine, Doyle needed prose suited for commuters reading in short bursts. He modernized the detective story not by changing its structure but by streamlining its prose.