Capture: Verify the dates and details of Jevons's Logic Piano — built 1869, exhibited before the Royal Society 1870 — against a primary or scholarly source

jevonslogic-pianologic-machineshistory-of-computingvictorian-scienceroyal-societyverificationprimary-source

This capture answers question-verify-jevons-logic-piano-1869-royal-society-1870, raised 2026-07-12 against claim-jevons-logic-piano-1869-mechanical-inference-machine, which flagged the 1869/1870 dates as resting only on Tier-4 Wikipedia (with partial Tier-2 corroboration added later from the Rutherford Journal and the Computer History Museum, still short of the sourcing floor for a quantitative/dated claim). This run went to the primary document itself — William Stanley Jevons's own 1870 paper in Philosophical Transactions of the Royal Society — plus the Oxford museum that holds the surviving physical machine.

Claim: Jevons's paper describing the logic machine was read before the Royal Society on 20 January 1870, after being received (submitted) on 16 October 1869

Claim type: quantitative/historical date claim — Tier 1–2 required, cleared at Tier 1: read directly from the Royal Society's own 1870 volume (via an Internet Archive full-text scan of that printing, not a summary).

The paper's own header line, exactly as printed in Philosophical Transactions of the Royal Society of London, vol. 160 (1870), p. 497:

"XXII. On the Mechanical Performance of Logical Inference. By W. Stanley Jevons, M.A. (Lond.), Professor of Logic, &c. in Owens College, Manchester. Communicated by Professor H. E. Roscoe, F.R.S. Received October 16, 1869, — Read January 20, 1870."

"Read" before the Royal Society is the Society's own term for a paper's oral presentation to its Fellows — this is the primary-source anchor for "exhibited before the Royal Society in 1870," and it gives an exact date the earlier Tier-4 sourcing lacked. A companion abstract of the same paper appears in the Society's Proceedings under DOI 10.1098/rspl.1869.0038 (search-result metadata only glimpsed this session, not independently fetched — royalsocietypublishing.org returned HTTP 403 to both archive_page and WebFetch); its snippet is consistent with the same 20 January date but is recorded here only as an unfetched lead, not as corroborating evidence.

Provenance: source_url/source_sha/source_quote as in frontmatter above. DOI of the full paper: 10.1098/rstl.1870.0022 (Royal Society Publishing; page itself 403'd to this session's tools, so cited via the Internet Archive's scan of the same 1870 printing — see found-spec note on mirrors above).

Claim: The machine itself had "been actually finished" by the time the paper was submitted (16 October 1869), corroborating the 1869 construction date in Jevons's own words

Claim type: quantitative/historical date claim — Tier 1–2 required, cleared at Tier 1 (Jevons's own paper, same document as above).

Section 32 of the paper, describing the machine's physical construction, opens:

"32. The Machine, which has been actually finished, is adapted to the solution of any problems not involving more than four distinct positive terms, indicated by A, B, C, D, with, of course, their corresponding negatives, a, b, c, d."

Since the paper containing this sentence was received by the Society on 16 October 1869, the machine was complete by that date at the latest — directly supporting "built 1869" from Jevons's own hand, independent of any secondary retelling. The paper never uses the word "piano" anywhere in its ~20 pages of technical description (checked by a full read of the extracted text); see Further leads for where that nickname likely comes from.

Provenance: same source as above (source_sha 1b80238a7d8f4d1e2e424f16f1e6e6b5b50e1ec1edbf731eeb8d9165dfb9c1f1), quote as given.

Claim: The Oxford History of Science Museum, which holds the surviving physical machine, independently dates it to 1869

Claim type: historical/institutional-provenance claim — Tier 3–4 acceptable when uncontested, but this clears Tier 1–2: the institution's own catalog/exhibition page for the object it physically holds, archived directly this session.

The Museum's own exhibition page for the object (part of its 2022 "Imagining AI" display, still live) states:

"Logic Machine by W. Stanley Jevons — Made in 1869 to William Stanley Jevons's design, this forerunner of the computer could solve logical problems by 'playing' them on the keyboard."

This is independent, institution-of-record corroboration of the 1869 build date — independent of Jevons's own paper (different author, different venue, a different kind of record: an object catalog rather than a scientific paper) — and it is the museum that has physically held the original machine since its bequest to Oxford, per the same page's related links (the object is elsewhere reported as still on public display there). The Museum's page also links directly to a Computer History Museum blog post ("Logical Piano Lessons," by historian David E. Dunning) and a video presentation of the actual object — both further leads, not fetched this session.

Provenance:

• source_url: https://www.hsm.ox.ac.uk/imagining-ai
• source_sha: ed12269412fd729a591a529eb19ec57e6826d28207812df76e725f4d0f78caa2
• source_author: History of Science Museum, University of Oxford (institutional page)
• source_date: page live as of 2026-08-10; content describes a September 2022 display
• source_venue: History of Science Museum, University of Oxford — official site, "Imagining AI" exhibition page
• source_quote: "Logic Machine by W. Stanley Jevons — Made in 1869 to William Stanley Jevons's design, this forerunner of the computer could solve logical problems by 'playing' them on the keyboard."
• source_tier: 1–2 (institutional catalog record for the object it physically holds)

Central question status

Are "built 1869" and "exhibited before the Royal Society 1870" correct? Confirmed, and sharpened. Two independent Tier 1 lines converge: Jevons's own 1870 paper states the machine was "actually finished" by the time the paper was received (16 October 1869) and that the paper itself was "Read" before the Royal Society on 20 January 1870 — giving an exact day, not just a year, for the Royal Society presentation. The Oxford museum holding the physical object independently dates its construction to 1869. claim-jevons-logic-piano-1869-mechanical-inference-machine's [unverified-quant] flag can be cleared on promotion of this capture; the exact date 20 January 1870 is new information beyond what that note currently carries.

Further leads

• The word "piano" does not appear anywhere in Jevons's 1870 Phil. Trans. paper (full read, this session) — the "Logic Piano" nickname's origin (contemporary press? Jevons's later writing, e.g. The Principles of Science, 1874?) is unconfirmed and worth its own capture.
• A Salford clockmaker, uncredited by name in the paper, is reported to have physically built the machine to Jevons's design, with Jevons visiting "almost every day to see that he is getting on right" — quote as relayed by history-computer.com (Tier 3, secondary aggregator) [unverified-quote — needs direct read]; likely traceable to Jevons's own letters/journal (edited posthumously by Harriet A. Jevons).
• Proceedings of the Royal Society abstract, DOI 10.1098/rspl.1869.0038 — a shorter companion notice of the same paper; royalsocietypublishing.org 403'd this session, not independently read.
• Computer History Museum blog "Logical Piano Lessons" by David E. Dunning (https://computerhistory.org/blog/logical-piano-lessons/), and Dunning's video Show-and-Tell of the actual object, linked from the Oxford museum page — not fetched this session, likely Tier 2 history-of-computing scholarship.
• Jevons's 1869 book The Substitution of Similars reportedly describes an earlier "logical abacus" design (wooden boards, a ruler) that the physical machine mechanized with levers/keys — a design precursor worth its own verification pass (currently only sourced to history-computer.com, Tier 3).
• History of Science Museum Oxford accession/inventory number for the object (search snippets suggest "18230") — not independently confirmed this session.

Safety flags

None. All pages read this session (Internet Archive scan and metadata, Royal Society Publishing landing pages, History of Science Museum Oxford page) were ordinary archival/institutional content with no addressed-to-AI language, override language, claimed authority, tier self-assignment, file-system instructions, credential requests, or urgency framing. royalsocietypublishing.org returned HTTP 403 to archive_page/WebFetch/extract_pdf on both DOIs attempted — treated as an access failure, not a safety signal, and not quoted from.

Entity candidates

• George Boole — person — the logician whose Laws of Thought symbolic system Jevons's machine mechanizes; Jevons explicitly benchmarks the device by solving one of Boole's own textbook problems "by the successive pressure of" its keys, in place of Boole's "very difficult and lengthy series of eliminations." The priority/ancestry claim in this whole topic (a machine that does deductive inference) rests on Boole's prior symbolic-logic work more than on any earlier machine-builder.
• Ramon Llull — person/concept — the paper's own §7 names Llull's "futile scheme of a mechanical syllogistic" as the one prior attempt at a reasoning-by-apparatus scheme, explicitly to distinguish it (mere diagrams, not a working mechanism) from Jevons's claim to have built the first real one.
• Charles Babbage — person — Jevons's own §5 frames the logic machine as arithmetic's Babbage-style mechanization extended to logic ("It was reserved for the profound genius of Mr. Babbage to make the greatest advance in mechanical calculation... I venture to look upon the logical machine which I am about to describe as equally a result...").
• William Stanley Jevons — person — subject of the capture; already the subject of claim-jevons-logic-piano-1869-mechanical-inference-machine and observation-jevons-double-bridge-victorian-logic-machine-to-ai-energy, no new entity page needed unless the queen wants a dedicated biography page.
• History of Science Museum, Oxford — institution — holds the surviving physical machine; source of the Tier 1–2 institutional corroboration above.
• David E. Dunning — person — historian of computing who authored the Computer History Museum's "Logical Piano Lessons" post and presented a Show-and-Tell video on the object for the Oxford museum; potential Tier 2 voice for future Jevons-machine research.
• Allan Marquand — person — already flagged in claim-jevons-logic-piano-1869-mechanical-inference-machine as the American logician Jevons's machine inspired; not re-flagged as new here, noted for continuity.