# Charles Babbage ### Inventor, Mathematician — 1791–1871 — England > _"The Analytical Engine weaves algebraical patterns just as the Jacquard loom weaves flowers and leaves."_ — Ada Lovelace, describing Babbage's machine --- ## Why This Matters You cannot understand the history of computation without understanding Charles Babbage. A century before ENIAC, before vacuum tubes, before electricity powered anything but parlor tricks, Babbage designed a fully programmable, general-purpose computer. His Analytical Engine — conceived in the 1830s — contained a central processor (the "mill"), random-access memory (the "store"), conditional branching, and looping. It was programmed with punched cards borrowed from Jacquard looms. The machine was never built, but the design was complete. When you write a program that separates data from instructions, when your CPU executes operations stored in memory, you are implementing ideas Babbage articulated in Victorian England. --- ## Quick Reference | Attribute | Value | |-----------|-------| | **Registry #** | 18 | | **Born** | December 26, 1791, London, England | | **Died** | October 18, 1871, London, England (age 79) | | **Active Period** | 1812–1871 | | **Fields** | Mathematics, Mechanical Engineering, Economics, Philosophy | | **Known For** | Difference Engine; Analytical Engine — first general-purpose computer design | | **Influenced By** | Jacquard (punched card mechanism), Leibniz (mechanical calculation), Newton | | **Influenced** | Ada Lovelace, Howard Aiken (Harvard Mark I), all modern computer architecture | --- ## Table of Contents 1. [Origins & Formation](#1-origins--formation) 2. [Intellectual Genealogy](#2-intellectual-genealogy) 3. [The Work: Chronological](#3-the-work-chronological) 4. [Core Ideas & Contributions](#4-core-ideas--contributions) 5. [Impact & Legacy](#5-impact--legacy) 6. [Study Guide: The Mental Model](#6-study-guide-the-mental-model) 7. [Going Deeper: Sources](#7-going-deeper-sources) --- ## 1. Origins & Formation ### A Note on Historical Sources > **On Documentation:** Unlike ancient figures, Babbage left extensive documentation — personal memoirs, thousands of engineering drawings, correspondence, and his autobiography _Passages from the Life of a Philosopher_ (1864). We have detailed records of his work, disputes, and frustrations. The challenge with Babbage is not scarcity of sources but evaluating his occasionally bitter and self-aggrandizing accounts against other evidence. ### Early Life & Context > _Etymology: **Babbage** derives from an English surname of unclear origin, possibly from a medieval personal name "Bab" or a place name. The family had roots in Devonshire banking._ Charles Babbage was born on **December 26, 1791**, in London, likely at 44 Crosby Row, Walworth Road, Southwark. His father, Benjamin Babbage, was a banking partner in Praed's & Co., providing the family with substantial wealth. His mother, Elizabeth Plumleigh Teape, came from a Devonshire family. **England in the Late 18th Century:** - The Industrial Revolution was transforming manufacturing - Mathematical tables (navigation, astronomy, engineering) were calculated by human "computers" — clerks who performed arithmetic by hand - Errors in these tables caused real harm — ships ran aground, engineering calculations failed - Mechanical automation was advancing: Jacquard's punched-card loom (1804) had demonstrated programmable machinery - The British Empire depended on navigation, which depended on accurate astronomical tables This was the era of Watt's steam engine, of factories replacing craftsmen, of the Napoleonic Wars. The Enlightenment faith in rational progress was meeting industrial capability. If you could mechanize weaving, why not mechanize thinking? ### Education & Training | Period | Context | Focus | Institution | |--------|---------|-------|-------------| | Childhood | Frail health; private tutors | Early mathematics, classics | Home education | | 1810–1814 | Cambridge University | Mathematics | Trinity College, then Peterhouse | | 1812 | Co-founded Analytical Society | Reform of British mathematics | Cambridge | | 1814 | Graduated | Without honors examination | Peterhouse | **The Cambridge Context:** When Babbage arrived at Cambridge, British mathematics was in decline. Newton's notation for calculus (fluxions) had become a nationalist badge of honor, while Continental mathematicians using Leibniz's superior notation had advanced far beyond. British mathematical education was stagnant. Babbage recognized this immediately. In 1812, with John Herschel and George Peacock, he founded the **Analytical Society**, dedicated to promoting "the principles of pure d-ism as opposed to the dot-age of the university" — a pun on Leibniz's "d" notation versus Newton's dots. They translated Lacroix's treatise on calculus and campaigned for reform. This youthful insurgency succeeded: within a decade, Cambridge adopted Continental notation. This experience shaped Babbage's character: he was a reformer by temperament, impatient with institutions, willing to fight for better methods against entrenched opposition. ### Formative Influences **The Error Problem:** The origin story Babbage told repeatedly: around 1812, he was checking astronomical tables at the Analytical Society rooms when he grew frustrated by errors. "I wish to God these calculations had been executed by steam," he exclaimed. From this moment, he dated his obsession with mechanical computation. This was not idle frustration. Mathematical tables — for navigation, surveying, insurance, engineering — were essential infrastructure. They were computed by human calculators using the method of differences, then typeset by printers. Errors crept in at both stages. A ship's captain using a faulty navigation table could wreck his vessel. The need was real. **Jacquard's Loom:** In 1804, Joseph Marie Jacquard perfected the punched-card loom. Patterns were encoded on cards; the loom read the cards and wove accordingly. The weaver had become a machine operator. Babbage saw a portrait of Jacquard woven in silk using 24,000 cards and was transfixed. Here was proof that complex patterns could be stored externally and read mechanically. The leap to storing computational instructions on cards was, in retrospect, inevitable. --- ## 2. Intellectual Genealogy ### The Lineage: Who Influenced Babbage ``` Mechanical Calculation Tradition │ ▼ ┌───────────────────────────────────────┐ │ Pascal (Pascaline, 1642) │ │ Leibniz (Stepped Reckoner, 1694) │ │ Thomas de Colmar (Arithmometer, 1820) │ └───────────────────────────────────────┘ │ ▼ ┌───────────────────────────────────────┐ │ Jacquard (Punched-card loom, 1804) │ │ Stored external program │ └───────────────────────────────────────┘ │ ▼ ┌────────┐ │ BABBAGE │ └────────┘ │ ▼ ┌───────────────────────────────────────────────────────────────────┐ │ Ada Lovelace (Programming concepts, 1843) │ │ │ │ ───────────── 100 year gap ───────────── │ │ │ │ Howard Aiken (Harvard Mark I, 1944) ←── Directly inspired by │ │ Babbage's designs │ │ von Neumann (Stored-program concept) ←── Independent reinvention │ │ │ │ All modern computer architecture │ └───────────────────────────────────────────────────────────────────┘ ``` **Direct Influences on Babbage:** - **Leibniz:** The stepped-drum mechanism for multiplication; the dream of mechanized reasoning - **de Prony's Tables:** Gaspard de Prony's massive French logarithm project (1790s) used division of labor — showing how calculation could be broken into simple steps - **Jacquard:** The punched card as external program storage - **Method of Differences:** The mathematical technique that made polynomial approximation amenable to mechanical iteration **Contextual Influences:** - **Industrial Revolution:** The principle that complex work could be decomposed into simple, mechanizable operations - **British manufacturing precision:** The existence of skilled machinists capable of producing precision parts - **Government interest:** The Admiralty and other bodies needed accurate tables, creating potential funding ### The Lineage: Who Babbage Influenced **Direct Collaborators:** | Person | Era | Contribution | |--------|-----|--------------| | **Ada Lovelace** | 1833–1852 | First programmer; understood the machine's generality beyond mathematics | | **Luigi Menabrea** | 1840 | First published description of the Analytical Engine | | **Joseph Clement** | 1823–1833 | Master machinist who built Difference Engine components | **Later Influence:** - **Howard Aiken** (1930s–40s): Explicitly acknowledged Babbage while designing the Harvard Mark I - **Leslie Comrie** (1930s): Used Babbage's concepts in scientific computation - **Doron Swade** (1990s): Built a complete Difference Engine No. 2 to Babbage's designs, proving they worked **Ideas That Persist:** | Babbage Concept | Modern Manifestation | |-----------------|---------------------| | Mill (processor) | CPU | | Store (memory) | RAM | | Punched-card programs | Software/programs stored separately from hardware | | Conditional branching | if-then-else logic | | Separation of engine from cards | Hardware/software distinction | --- ## 3. The Work: Chronological ### Master Timeline | Period | Work | Type | Significance | |--------|------|------|--------------| | 1822 | Difference Engine No. 1 proposal | Engineering | First automatic calculator design | | 1823–1833 | Difference Engine construction | Engineering | Partial construction; government funding | | 1833–1834 | Analytical Engine conception | Engineering | First general-purpose computer design | | 1834–1871 | Analytical Engine development | Engineering | 300+ drawings; never completed | | 1847–1849 | Difference Engine No. 2 | Engineering | Simplified design; never built in his lifetime | | 1864 | _Passages from the Life of a Philosopher_ | Memoir | Autobiography; source of many Babbage stories | ### The Difference Engine > _Etymology: **Difference** refers to the mathematical method of finite differences, which allows polynomial functions to be computed through repeated addition alone._ **What It Was:** The Difference Engine was designed to compute polynomial functions using the method of differences. This method reduces polynomial evaluation to a sequence of additions — no multiplication or division required. Since mechanical addition is straightforward (just gear rotations), the entire calculation could be mechanized. **The Problem It Solved:** Mathematical tables were computed by human "computers" — clerks who performed calculations according to fixed rules. Errors were endemic. The Difference Engine would compute tables automatically and print the results directly, eliminating both calculation and typesetting errors. **The Method of Differences:** For a polynomial of degree n, the nth differences are constant. Working backward, you can compute any polynomial value by repeated addition: ``` To compute f(x) = x²: x f(x) 1st diff 2nd diff 0 0 1 2 1 1 3 2 2 4 5 2 3 9 7 2 4 16 ... ``` The second differences are constant (2). To get the next value, add the first difference (7) to the previous value (9), then add the second difference (2) to update the first difference (9). Only addition, ever. **What Happened:** In 1823, the British government funded the Difference Engine at 1,500 pounds, eventually spending over 17,000 pounds (millions in today's currency). Babbage hired Joseph Clement, the finest machinist in England, to build it. By 1833, about one-seventh of the engine was assembled — a working demonstration section. Then disaster. Babbage quarreled with Clement over ownership of tools and drawings. Clement stopped work. The government, exasperated by delays and cost overruns, eventually withdrew funding in 1842. The Difference Engine No. 1 was never completed. But the small section that was built worked perfectly. In 1991, the Science Museum in London constructed Difference Engine No. 2 (Babbage's improved design from the 1840s) using only techniques available in Babbage's time. It worked flawlessly on its first try. The failure was not technical. It was managerial, political, and financial. ### The Analytical Engine > _Etymology: **Analytical** reflects the machine's ability to perform analysis — to break problems into steps, to branch conditionally, to operate on abstract quantities rather than just computing tables._ **What It Was:** Conceived around 1834, the Analytical Engine was something fundamentally new: a general-purpose, programmable computing machine. Unlike the Difference Engine (which could only compute polynomials), the Analytical Engine could execute any calculation that could be expressed as a sequence of operations. **Architecture:** | Component | Name | Function | Modern Equivalent | |-----------|------|----------|-------------------| | Processor | **Mill** | Performed arithmetic operations | CPU | | Memory | **Store** | Held numbers (1,000 numbers of 50 digits each) | RAM | | Program | **Operation Cards** | Specified which operations to perform | Machine code | | Data | **Variable Cards** | Specified which store locations to use | Memory addresses | | Output | **Printing apparatus** | Output results | Printer/display | **Key Features:** 1. **Separation of Program and Data:** The operation cards (program) were distinct from the variable cards (data addresses). This separation is the foundation of all programming. 2. **Conditional Branching:** The engine could skip forward or backward in the card sequence based on results — the "if-then" of computation. 3. **Looping:** Combined with conditional branching, the engine could repeat operations — the "while" of computation. 4. **General Purpose:** It could compute anything that could be expressed as a sequence of arithmetic operations. Ada Lovelace recognized this meant it could manipulate any symbols, not just numbers. **Why It Was Never Built:** - **Funding:** After the Difference Engine debacle, the government would not fund another machine - **Scale:** Thousands of precision parts, beyond contemporary manufacturing capacity for a single project - **Babbage's temperament:** He kept improving the design rather than freezing specifications - **No urgent sponsor:** Unlike wartime code-breaking, there was no existential pressure to complete it Babbage worked on the Analytical Engine until his death in 1871. He produced hundreds of detailed drawings and thousands of pages of notes. The design was complete. The machine was not built. --- ## 4. Core Ideas & Contributions ### The Central Insight Babbage understood that **computation is mechanical** — that any calculation following fixed rules could be performed by a machine following those same rules. More radically, he grasped that the rules themselves (the program) could be stored externally and fed to the machine, making it general-purpose. This is the insight that underlies: - All stored-program computers - The separation of hardware and software - The concept of programming itself - The universality of computation Babbage didn't just design calculators. He discovered the architecture of general computation. ### Key Concepts #### The Mill > _Etymology: **Mill** from the grinding action of a flour mill — taking raw material (numbers) and processing them into product (results)._ **Definition:** The central processing unit of the Analytical Engine, where arithmetic operations were performed. Numbers were loaded from the Store, processed in the Mill, and results returned to the Store. **Design:** The Mill used columns of gear-wheels representing decimal digits. Operations were performed by mechanical rotation — addition by concurrent rotation, multiplication by repeated addition with shifting. **Modern Application:** The CPU. The Mill's architecture — fetch operands, perform operation, store result — is exactly how modern processors work. #### The Store > _Etymology: **Store** in the sense of warehouse — a place where quantities are held until needed._ **Definition:** The memory of the Analytical Engine. Babbage planned for 1,000 columns, each holding a 50-digit decimal number. Any column could be accessed for input to the Mill or to receive output. **Design:** Vertical columns of gear-wheels, each column representing one number. The columns could be read from or written to by the Mill through mechanical linkages. **Modern Application:** RAM (Random-Access Memory). The key insight was that memory locations were interchangeable and addressable — you could read or write any location. #### Operation Cards and Variable Cards > _Etymology: Borrowed from Jacquard's loom, where **cards** with punched holes controlled the pattern._ **Definition:** Punched cards that controlled the Analytical Engine's behavior. Operation Cards specified which operation to perform (add, subtract, multiply, divide). Variable Cards specified which Store columns to use as operands and where to put results. **Modern Application:** Machine code and memory addresses. The separation of "what operation" from "what data" is the foundation of instruction sets. #### Conditional Branching **Definition:** The ability of the Engine to change which card it processed next based on the results of computation — specifically, whether a result was positive, negative, or zero. **Example:** If a subtraction produces zero, skip the next ten cards and continue from card 47. This allowed loops (go back to an earlier card) and conditionals (skip cards based on conditions). **Modern Application:** if-then-else, while loops, function calls. All control flow descends from this idea. ### Theoretical Framework The Analytical Engine operates as a **stored-program machine**: ``` INPUT: Operation Cards (program) + Variable Cards (addresses) + Initial Store values │ ▼ ┌─────────────────────────────────────┐ │ Card Reader reads next Operation │ │ and Variable cards │ │ │ │ │ ▼ │ │ Mill fetches operands from Store │ │ addresses specified by Variable │ │ cards │ │ │ │ │ ▼ │ │ Mill performs operation specified │ │ by Operation card │ │ │ │ │ ▼ │ │ Result written to Store address │ │ specified by Variable card │ │ │ │ │ ▼ │ │ Conditional: check result, │ │ possibly skip or repeat cards │ └─────────────────────────────────────┘ │ ▼ OUTPUT: Final Store values → Printing apparatus ``` This is the **fetch-decode-execute cycle** of modern processors, conceived in 1834. ### Innovations & Firsts | Innovation | Description | Prior State | What Changed | |------------|-------------|-------------|--------------| | General-purpose design | Same machine executes any program | Special-purpose calculators | Universality | | Stored program | Instructions external to machine | Operations built into hardware | Software concept | | Separation of processor/memory | Mill distinct from Store | Integrated calculating devices | CPU/RAM architecture | | Conditional branching | Machine changes behavior based on results | Fixed sequence only | Control flow | | Punched-card programming | Programs stored and reusable | No concept of programming | Programming itself | --- ## 5. Impact & Legacy ### Immediate Impact **In Babbage's Lifetime:** The Difference Engine demonstration section impressed visitors and established Babbage's reputation. But the failure to complete either machine meant the immediate impact was limited. The British government wrote off their investment. Other inventors pursued calculating machines, but none attempted Babbage's ambitious generality. **Ada Lovelace's Notes (1843):** The most significant immediate impact came through Ada Lovelace. In 1843, she translated Luigi Menabrea's article on the Analytical Engine and added her own notes — longer than the original article. In these notes, she: - Explained why the Engine could compute anything expressible as operations - Recognized it could manipulate any symbols, not just numbers ("The engine might compose elaborate and scientific pieces of music") - Published what is considered the first computer program (calculating Bernoulli numbers) - Distinguished the Engine from mere calculators: "The Analytical Engine has no pretensions to originate anything. It can do whatever we know how to order it to perform" These Notes are the first published discussion of computer programming. ### Long-Term Influence **The 100-Year Gap:** After Babbage's death in 1871, his work was largely forgotten. His son Henry Babbage assembled a small portion of the Analytical Engine's Mill and demonstrated it could perform multiplication, but there was no continuation of the project. The next general-purpose computers — Zuse's Z3 (1941), the Colossus (1943), ENIAC (1945), the Manchester Baby (1948) — were developed independently by people who often did not know Babbage's work in detail. **Howard Aiken and the Harvard Mark I:** The exception was Howard Aiken. In the 1930s, Aiken encountered Babbage's work and explicitly modeled his Harvard Mark I (1944) on Babbage's concepts. He later wrote: "If Babbage had lived seventy-five years later, I would have been out of a job." The Mark I was electromechanical (relays instead of gears) but conceptually descended directly from Babbage. **Modern Recognition:** As computer science developed as a discipline, Babbage was recognized as a founding figure: - The Analytical Engine is now understood as a genuine general-purpose computer design - Babbage's notebooks and drawings have been thoroughly analyzed - The Science Museum's construction of Difference Engine No. 2 (1991) proved the designs were practical - Computer science curricula typically include Babbage as historical context ### The Counterfactual > What if Babbage had completed the Analytical Engine? If Babbage had secured funding, frozen the design, and managed the project to completion, a working programmable computer might have existed by 1850. What then? - **Immediate:** Accurate mathematical tables; scientific calculations previously impractical - **Programming culture:** Ada Lovelace and others might have developed programming as a discipline - **But:** Without electronics, mechanical computers would have been slow, expensive, and rare. The Victorian era lacked the telecommunications infrastructure to connect them. The Analytical Engine was ahead of its time — not in concept, but in the supporting technologies that would make computation ubiquitous. Babbage invented the computer, but the world wasn't ready to mass-produce it. ### Recognition & Honors | Era | Recognition | |-----|-------------| | Lifetime | Lucasian Professor of Mathematics at Cambridge (1828–1839) | | 1871 | Obituaries recognized his genius but emphasized his failures | | 20th century | Gradually recognized as computing pioneer | | 1991 | Difference Engine No. 2 built; worked perfectly | | Modern | "Father of the Computer"; computing history canon | --- ## 6. Study Guide: The Mental Model ### The One Sentence > **Babbage designed the first general-purpose programmable computer in the 1830s — complete with CPU (Mill), RAM (Store), and punched-card programs — a century before electronics made such machines practical to build.** ### The Three Things to Remember 1. **First General-Purpose Design:** The Analytical Engine was not a calculator. It could execute any program, branch conditionally, loop, and operate on abstract data. It was a universal computer. 2. **The Architecture Persists:** Mill/Store/Cards maps directly to CPU/RAM/Software. Babbage's architecture is, in essence, still how computers work. 3. **Failure to Complete =/= Failure of Ideas:** Babbage never built his machines, but the designs were sound. Difference Engine No. 2 was built in 1991 and worked on its first try. The ideas were right; the execution environment was wrong. ### The Visual ``` ┌────────────────────────────────────────────────────────────────┐ │ THE ANALYTICAL ENGINE (1837) │ │ First General-Purpose Computer Design │ │ │ │ PROGRAM PROCESSOR MEMORY │ │ ┌──────────┐ ┌───────────┐ ┌──────────┐ │ │ │ Operation │ │ │ │ │ │ │ │ Cards │───────▶│ MILL │◀──────▶│ STORE │ │ │ │ (what to │ │ │ │ │ │ │ │ do) │ │ Arithmetic│ │ 1,000 │ │ │ ├──────────┤ │ Operations│ │ numbers │ │ │ │ Variable │───────▶│ │ │ (50 digits│ │ │ │ Cards │ │ │ │ each) │ │ │ │ (which │ └───────────┘ └──────────┘ │ │ │ data) │ │ │ │ └──────────┘ ▼ │ │ │ ┌───────────┐ │ │ │ │ Printing │ │ │ │ │ Apparatus │ │ │ │ └───────────┘ │ │ │ │ │ └──────▶ Conditional branching: │ │ Skip/repeat cards based on results │ │ │ └────────────────────────────────────────────────────────────────┘ ``` ### Connecting to Other Figures | If You Know... | Then Understand That Babbage... | |----------------|--------------------------------| | 17-Jacquard | Borrowed punched cards for programming — external stored programs | | 19-Ada Lovelace | Collaborated with her; she understood his machine's generality better than most | | Alan Turing | Anticipated the universal machine concept 100 years before Turing formalized it | | John von Neumann | Independently reinvented stored-program architecture in the 1940s | | Modern CPUs | Designed the Mill — the processor that fetches, computes, and stores | ### Common Misconceptions | Misconception | Reality | |---------------|---------| | "He only designed calculators" | The Analytical Engine was fully general-purpose, not a calculator | | "His designs were impractical" | Difference Engine No. 2 was built in 1991 and worked perfectly | | "He failed because he wasn't good enough" | The failure was funding, politics, and manufacturing limits — not design | | "Ada Lovelace did all the real work" | Babbage designed the machine; Lovelace understood and explained its implications | | "He was just a dreamer" | He produced hundreds of detailed engineering drawings; the designs were buildable | ### Test Your Understanding 1. **Conceptual:** Why is the separation of Operation Cards (what operation) from Variable Cards (which data) such a fundamental idea? What would computing look like without this separation? 2. **Connection:** How does Babbage's Mill/Store distinction anticipate the CPU/RAM distinction in modern computers? 3. **Genealogy:** Trace the path from Jacquard's loom to modern software — what concepts were borrowed, and what was new? --- ## 7. Going Deeper: Sources ### Primary Sources | Source | Type | Access | Notes | |--------|------|--------|-------| | Babbage's drawings and notebooks | Engineering | Science Museum, London | 300+ detailed drawings of the Analytical Engine | | _Passages from the Life of a Philosopher_ (1864) | Autobiography | Archive.org | Babbage's own account; entertaining but self-serving | | Ada Lovelace's "Notes" (1843) | Technical | Widely reprinted | First description of programming concepts | | Menabrea, "Sketch of the Analytical Engine" (1842) | Technical | Archive.org | First published description | ### Essential Secondary Sources | Source | Author | Type | What It Covers | |--------|--------|------|----------------| | _The Cogwheel Brain_ | Doron Swade | Historical | Definitive modern biography; Swade led the Difference Engine No. 2 project | | _Charles Babbage: Pioneer of the Computer_ | Anthony Hyman | Biography | Comprehensive life and work | | _Ada's Algorithm_ | James Essinger | Biography | Babbage-Lovelace collaboration | | _The Difference Engine_ | Doron Swade | Technical | Detailed account of building Difference Engine No. 2 | | _Irascible Genius_ | Maboth Moseley | Biography | Earlier biography with focus on personality | ### Modern Introductions - **For beginners:** Doron Swade's _The Cogwheel Brain_ is accessible and authoritative - **For programmers:** Ada Lovelace's Notes remain the best conceptual introduction to what the Analytical Engine could do - **For engineers:** The Science Museum's documentation of the Difference Engine No. 2 construction ### Online Resources - [Computer History Museum](https://computerhistory.org) — Babbage materials and context - [Science Museum, London](https://sciencemuseum.org.uk) — Difference Engine No. 2 and Babbage collection - [Fourmilab's Analytical Engine Emulator](https://fourmilab.ch/babbage/contents.html) — Interactive simulation - [Charles Babbage Institute, University of Minnesota](https://cse.umn.edu/cbi) — Computing history archive --- ## Appendix: Handling Uncertainty > **Note on Sources:** Unlike ancient figures, Babbage is well-documented. The uncertainties concern interpretation rather than fact: How close was the Analytical Engine to modern concepts? Was Babbage a genius ahead of his time or a talented engineer who failed to deliver? Scholars debate these questions, but the historical record itself is clear. | Claim | Confidence | Source | |-------|------------|--------| | Birth date and place | High | Parish records | | Difference Engine design and partial construction | High | Surviving machine section; drawings | | Analytical Engine design details | High | 300+ surviving drawings | | Never completed either machine | Certain | Historical record | | Designs would have worked if built | High | Difference Engine No. 2 built 1991, worked | | Influenced Aiken directly | High | Aiken's own statements | --- _Last updated: 2026-03-26. This is a living document._