Analytical engine

Charles Babbage begins work on the Analytical Engine

The earliest surviving drawing lays the new machine out in a circle — not the linear architecture used to illustrate Babbage today.

No single day to point at

After work on the government-backed Difference Engine stopped, Babbage began developing a new calculating engine; the historian Allan Bromley dates the first notes to mid-1834.

The earliest surviving Analytical Engine drawing is dated September 1834 and shows a circular arrangement for what the archive calls the "new engine."

The Science Museum nevertheless catalogues the broader first design phase as beginning in 1833, so this is a design transition rather than a one-day invention.

A design that would not hold still

Drawings made in November and December 1834 show Babbage already exploring carriage, stepping and multiplication mechanisms, with the design still in rapid evolution.

The surviving first-phase series runs from September 1834 to 6 March 1849 and holds 183 drawings across about 30 distinct plans; storage capacity, control mechanisms and physical arrangement all changed between them.

The mature vocabulary of "mill," "store" and punched-card programming describes that later development better than it describes the first 1834 sketches.

What he told Brussels

By May 1835 Babbage told the Royal Academy in Brussels that he had spent six months drawing a machine of much greater power than the Difference Engine.

The capacity he claimed then was 100 variables of 25 decimal figures each — not the 1,000 forty-digit numbers of a later configuration often quoted as the design's specification.

Bromley notes that Babbage spent the engine's early decades refining designs and made no sustained attempt to construct the whole machine.

Sources

Researched 24 Aug 2026 7 sources not yet audited Date disputed

How this was checked

Researched from the web into a fact sheet and rewritten from that sheet. This article has not yet had an independent model audit. How the pipeline works →

Date disputed. Sources disagree; the research places it at ~1834.

What the sources leave uncertain

There is no secure single day on which Babbage “conceived” the Analytical Engine.
Bromley places the first notes in mid-1834, and the first surviving formal drawing is dated September 1834. The Science Museum nevertheless catalogs the broader first phase as beginning in 1833.
The event is therefore best treated as a design transition during 1834, not a one-day invention.