Excavation · Who invented the light bulb? (the invention era, 1802-1895)
Area: Technology and Engineering · History · Law and Justice · Question: Where and when did it begin?, Is a widely shared claim true? · Starts from a widely shared claim
The short answer
Partly
Current assessment · as of 2026-10-02
Partly Edison, but not him alone: patents for an electric light go back to 1841, and whether Edison or Swan first made a practical lamp is unsettled.
Central claim: Edison did not invent the incandescent lamp from nothing and was not its first or only inventor. British patents of 1841 (de Moleyns) and 18
Evidence ●●●●● Public belief ●●●●● Source checked: primary
What would settle it. A dated sale, order, price list or company record showing which of Swan's or Edison's lamps was first made and sold for ordinary use, and a dated pre-1882 document for or against Goebel's lamps.
"The light bulb" covers at least four different firsts: a patent for an electric light or lamp, a lamp with a heated carbon conductor in a vacuum, a lamp practical to make and use, and a lamp run from a central supply. On the first two, the documents read here put others ahead of Edison: de Moleyns's British patent of 1841 (an electric light fed with powdered charcoal in an exhausted globe, which the Supreme Court calls incandescent but whose abridgment does not), King's of 1845 (heated carbon conductors, carbon in a vacuum; Starr is named by later sources), and, as a reported experiment, Swan's glowing carbon rod of December 1878. On the third, the courts found Edison's lamp "practically operative and successful" and upheld the second claim of his patent (a carbon filament in an all-glass exhausted bulb; Wallace J. credits him with high resistance, which Lacombe J. refused to make a limit of that claim); Swan, by his own account, showed a very thin carbon lamp in October 1880 and Swan lamps lit Cragside (1880, per an archive blog, a proposed claim only) and the Savoy stage (28 December 1881, per a transcription of The Times), both before Edison's Pearl Street service began on 4 September 1882, but no document read shows who first made or sold a practical lamp. On the fourth, Edison's company is the one documented, and nothing earlier was searched for. Two national stories (Lodygin's, and Woodward and Evans's) each hold a real record that is stretched beyond what it shows (Lodygin's "first" is refuted, the Canadian sale is unsupported on the documents read), and a Latimer misattribution is refuted on his patents; the Goebel 1854 lamps are contested, resting on affidavit testimony (about forty affidavits per Colt J.) that US courts weighed differently on preliminary motions, with no dated document from before 1882 either way; de Changy's 1858 lamps are known only through Fontaine and his claim to be first is not dug. One stated standard (S1 to S4, in the description) is applied to every claimant, but the depth differs: some anchors are patent abridgments, a blog or a transcription, and the exceptions are named: the Cragside date rests on a blog about a letter nobody read, so it is filed as its own proposed claim (lamp-swan-cragside), not as established; the Savoy report and the 22 Oct 1879 notebook entry are established on transcriptions (see the description for why). We therefore say "partly", not "Edison" and not "Swan".
Based on: lamp-edison-sole-inventor lamp-de-moleyns-patent lamp-starr-king-patent lamp-earliest-patent lamp-edison-patent-upheld lamp-first-practical-priority lamp-swan-before-edison lamp-swan-in-use lamp-swan-cragside lamp-menlo-park-dec-1879 lamp-pearl-street lamp-goebel-claim
We give no probability figure. Confidence words describe how sure we are of the basis, and no source supplies a number that would not be invented.
Challenge this assessment A challenge needs a specific claim and evidence we can check. How challenges work.
refuted: the claim below is false confidence high · our conclusion
Edison did not invent the incandescent lamp from nothing and was not its first or only inventor. British patents of 1841 (de Moleyns) and 1845 (King, for Starr) already described, respectively, an electric light fed with powdered charcoal in an exhausted globe and a heated carbon conductor in a vacuum; Woodward patented a carbon lamp in rarefied gas in 1874-76; and Swan reported a glowing carbon rod in an exhausted globe in December 1878, a rod that blackened its globe. US courts upheld the second claim of Edison's own patent (1880), a carbon filament in an all-glass exhausted receiver (claim 1, the high-resistance filament, was held limited and not infringed); in Wallace J.'s words Edison made "a lamp which was practically operative and successful" (47 F. 454, 1891), and Colt J. records that the earlier ruling held claim 2 to cover "a broad and fundamental invention, namely, an incandescent lamp, composed of a carbon filament, hermetically sealed in an all glass chamber exhausted to a practically perfect vacuum, and having leading-in wires of platinum" (54 F. 678). Whether Edison or Swan was first to a practical lamp, and a complete wired system (Pearl Street, 1882), are separate claims (lamp-first-practical-priority, lamp-pearl-street).
Anchor. British patents 9053 (1841) and 10,919 (1845), Patent Office abridgments; Chemical News 39 (1879): Swan's December 1878 rod lamp; US 181,613 (Woodward); 47 F. 454 (1891) and 52 F. 300 (1892); 54 F. 678 (1893), Colt J.; US 223,898.
Would change if. the 1845 patent is shown not to describe a heated carbon conductor in a vacuum (or the 1841 patent not to describe a light in an exhausted globe), or the courts are shown to have upheld Edison's patent as the first lamp of any kind
Evidence nodes (what each does to the statement above)
"Who invented the light bulb?" has a famous answer (Edison) and several national counter-answers (Swan for Britain, Woodward and Evans for Canada, Göbel for Germany, Lodygin for Russia, de Changy for Belgium). This dig treats every one of those answers the same way: each is a claim that must be anchored to a dated document from the time. The founding core runs from Davy's battery lights to the 1895 Supreme Court ruling that closed the patent fight. Later metal filaments (tungsten, 1900s) are out of scope for now except where a claimant's own patent reaches into them. THE STANDARD, stated so that it can be checked (and applied to Edison's side as well): (S1) a claim that someone did something by a date is "established" only if a dated document of the time that records it was read directly; a document known only as quoted in one later book, or a later self-account, is a single channel (filed as proposed, contested or a searched gap, never established). (S2) A claim that someone was "first" is refuted only by a dated document, read directly, that shows an earlier person did the same thing; the absence of an earlier document never refutes it (that is a searched gap, capped at provisional). (S3) A patent proves what was claimed and described on its date, not that a lamp was built or worked; "built" needs a report of the lamp. (S4) A court's finding on affidavits is primary text for what the court found, not a document of the period it describes. Under S1 to S4 the claims for de Changy and Lodygin are single-channel (Fontaine), Cragside is single-channel (an archive blog about a letter not read), Goebel's 1854 lamps are contested, and Swan's 1850s work is a gap. Why a transcription is treated differently from Fontaine's quotations: a transcription (the Times page as the Gilbert and Sullivan Archive prints it; Batchelor's entry in the Edison Papers edition) reproduces the dated document itself, whose text can be checked against the original and whose authenticity record is its own entry, whereas Fontaine (1878) reports and selects from a report whose original was not seen, so errors of quotation or selection cannot be told apart. It is a judgment, and both transcription-based claims stay at secondary and moderate, not primary. Two established claims are still anchored below primary (the Savoy report, read in a transcription; the 22 Oct 1879 notebook entry, read in the Edison Papers' transcription) and are shown as limits.
Adoption says "Edison" almost everywhere, and in each claimant's country it says "ours". The evidence says the question is badly formed: "invented" covers at least four different firsts (a patent, a lamp with a heated carbon conductor in a vacuum, a lamp practical to make and use, a complete wired system), and they have different answers. Several national stories hold one true fact (a real patent, a real report, a real demonstration) that is then stretched into "first": that is shown for Lodygin and for Woodward and Evans; Göbel's is contested and de Changy's first-claim is not dug. The two loudest priority claims against Edison, Göbel's 1854 lamps and the Canadian sale, differ in kind: for Göbel there are about forty affidavits but no dated document from before 1882 either way (the courts split on preliminary motions); for Woodward and Evans there is a real patent and no document of a sale. Two gaps are left open and are not closed by either side: Swan's early work survives only in his own 1880 account, and nothing read shows who first sold a practical lamp, Swan or Edison.
Every point on the timeline links to its source. Open the timeline.
Status: passed with open items · reviewed 2026-10-02. Independent review, 2026-10-02, of the revised dig (author commits 8495c38 and b2dfecd). The reviewer did not write the dig or review it before and did not edit any dig file. Sources opened by the reviewer (host in brackets): US patents 223,898, 181,613, 252,386, 247,097, 266,358 and 47,632 (USPTO image server, OCR by the reviewer) and 575,002 (Google Patents text); Federal Reporter 40, 47, 52, 54, 56, 57 and 61 F. (static.case.law); 159 U.S. 465 (tile.loc.gov scan); the 1859 British abridgments pp. 62-63 and 97-98 (archive.org); Chemical News 39 and 42 (archive.org); Fontaine 1878 (archive.org); Davy 1812 pp. 85-86 and the archive.org record (publisher Bradford and Inskeep); Dyer and Martin 1910 vol. II pp. 615-616 (archive.org); Howell and Schroeder 1927 and Schroeder 1923 (archive.org, passages on de la Rue 1820, de Changy 1856, the 50,000 rouble prize, Grove 1840); Scientific American 12 Sep 1874 and Electrical World and Engineer 14 Apr 1900 (archive.org OCR); Edison Papers essay, Doc. 1831 PDF, Latimer essay and Edison and Swan United page (edison.rutgers.edu); the IET archives blog; The Times transcription (gsarchive.net); Kommersant docs 6822124 and 5338615; CBC 2017, Canada's History and Quote Investigator. Round 1 (the earlier passes): R1-1, R1-2, R1-3 and the non-blocking items R1-6 to R1-16 are resolved; R1-4 and R1-5 are not, for the reasons in their reviewer_check lines (R2-1 to R2-3). Because two blocking round 1 requests stay open and four blocking round 2 requests are new, the status is revisions_requested. Fresh pass: more than twenty claims were checked against the sources (lamp-davy-arc, lamp-de-la-rue-1840, lamp-de-moleyns-patent, lamp-earliest-patent, lamp-starr-king-patent, lamp-de-changy-belgium, lamp-lodygin-1872-74, lamp-lodygin-first-claim, lamp-lodygin-refractory-metals, lamp-woodward-evans-patent, lamp-woodward-evans-performance, lamp-canada-invented-claim, lamp-swan-1850s, lamp-swan-1878, lamp-swan-early-1879, lamp-swan-before-edison, lamp-swan-in-use, lamp-first-practical-priority, lamp-edison-oct-1879-test, lamp-edison-patent, lamp-edison-high-resistance, lamp-edison-bamboo, lamp-sawyer-man-priority, lamp-edison-patent-upheld, lamp-goebel-claim, lamp-latimer-patent, lamp-latimer-invented-claim, lamp-10000-ways-quote, lamp-edison-sole-inventor). Every established or refuted claim was checked except lamp-pearl-street (the newspaper page was not reachable). Patent numbers and dates agree with the scans (Edison 223,898 signed 1 Nov 1879, patented 27 Jan 1880, two claims; Woodward 181,613 filed 4 Jan 1875, dated 29 Aug 1876, carbon in "a rarefied gas that will not unite chemically with the carbon when hot"; Latimer 252,386 filed 19 Feb 1881, dated 17 Jan 1882, assigned to the United States Electric Lighting Company; 247,097 filed 18 Apr 1881, dated 13 Sep 1881; Goebel 266,358 filed 23 Jan 1882, dated 24 Oct 1882; Lodygin 575,002 filed 4 Jan 1893, dated 12 Jan 1897). The court dates (5 Oct 1889, 4 Oct 1892, 18 Feb 1893, 21 Apr 1893, 20 Jul 1893, 1 May 1894, 11 Nov 1895) match the reporter data; the July 1891 judgment date is from 57 F. 616 and the decree date of 23 July 1891 from 54 F. 678. Nodes: all 41 lamp nodes were listed with time, precision, date_basis, window and place. Dates agree with their sources; places are given only where a source names them and carry Nominatim orientation notes; state-level places for the court rulings are the districts the opinions name. The two exceptions are in R2-3 (a node text that misstates its source) and R2-7 (days that no source read gives). The Davy node and the Cragside node are honest about year-level precision. Standard across claimants: Goebel (contested, low), de Changy and Lodygin (proposed, single channel through Fontaine), Woodward performance (proposed) and Swan 1850s (gap) are held to S1 to S4 consistently; the Edison side is held to it too (lamp-first-practical-priority is contested at low confidence; the 22 Oct 1879 test stays secondary). The residual unevenness is the assessment wording (R2-2) and the Cragside anchor (R2-6). Assessment: the answer partly and the three key points are in line with the claims except for the 1841 wording (R2-1) and the Cragside limit (R2-6). headline_status draft is justified: the headline names an open question and its first half is carried by more than the headline claim. Repository text: no personal names beyond the historical figures and the cited authors were found in the dig and its nodes; no model identifiers or contact details; no copyrighted images; quotations are short and attributed. Mapping of the log entries the requester cited: L-11 (blocking 1 and 2), L-12 (blocking 3), L-13 and L-14 (blocking 4), L-15 (blocking 5), L-16 (non-blocking), L-17 (dates and places), L-18 (still unchecked). Two statements in L-14 and L-17 are false about their sources (R2-3, R2-5); the log is append-only, so the correction must be a new entry. author_response: {action: fixed, note: Verified 'Matthew Evans' in Electrical World 1900; timeline people list now uses Matthew.} Second review (round 3), 2026-10-02, by an independent review agent (second reviewer) that did not write the dig and took no part in rounds 1 and 2. No dig file other than this one was edited. Sources opened by this reviewer: Kommersant 6822124 and 5338615; the 1859 abridgments (pp. 62-63, 97-98); Fontaine 1878 (pp. 169-173, 184-187); Chemical News 39 and 42; Federal Reporter 40, 47, 52, 54, 56, 57 and 61 (static.case.law); 159 U.S. 465 (tile.loc.gov, pdftotext); US 223,898, 181,613, 252,386 and 247,097 (USPTO scans, OCR); Dyer and Martin vol. II pp. 615-616; Electrical World 14 Apr 1900; Scientific American 12 Sep 1874 (OCR "Woodwara and Evans' Electric Light. Aug. 3, 1874"); the Edison Papers essay and Doc. 1831; the IET blog; the Times transcription; the loc.gov text of the four newspaper pages; Quote Investigator (summary only). Round 1 and 2 requests: R1-1 to R1-3, R1-6 to R1-16 and R2-3 to R2-11 are resolved by this reviewer's own reading. R1-4, R1-5, R2-1 and R2-2 are not, because of R3-1 and R3-2. Because two blocking requests are new and four earlier blocking ones stay open, the status remains revisions_requested. Fresh pass (all matched against the sources unless marked): lamp-davy-arc (not re-opened; the first reviewer's reading kept), lamp-de-moleyns-patent, lamp-earliest-patent (R3-1), lamp-starr-king-patent, lamp-de-changy-belgium (Fontaine pp. 186-187: 27 Feb 1858, "hermetically sealed glass tubes", "incandescence of platinum", "lit in the hollow of my hand", "in 1857, M. de Changy, in Belgium, substituted platinum for the carbon"), lamp-lodygin-1872-74 (Fontaine: 1873, "a high prize", "Lomonossow prize", "the first who had the idea"; Kommersant; R3-3), lamp-lodygin-first-claim, lamp-woodward-evans-patent (US 181,613: filed 4 Jan 1875, patented 29 Aug 1876, "rarefied gas that will not unite chemically with the carbon when hot", "becomes luminous"), lamp-woodward-evans-performance, lamp-canada-invented-claim, lamp-swan-1850s, lamp-swan-1878, lamp-swan-early-1879, lamp-swan-before-edison, lamp-swan-in-use (R3-2), lamp-first-practical-priority, lamp-edison-oct-1879-test, lamp-edison-patent (signed 1 Nov 1879, patented 27 Jan 1880, four claims), lamp-edison-high-resistance (47 F. 454 and 52 F. 300 quotes; French patent 130,910 of 28 May 1879; Canadian 10,654 of 17 Nov 1879), lamp-edison-bamboo, lamp-menlo-park-dec-1879, lamp-pearl-street, lamp-sawyer-man-priority (317,076 issued 12 May 1885 per the Supreme Court scan; "too indefinite"; "becomes unnecessary"; "Affirmed"), lamp-edison-patent-upheld, lamp-goebel-claim (all quotations; "some forty affidavits"; Seaman J. agrees with Hallett J. only that the St. Louis evidence lacks "the measure of proof demanded" and rejects his rule, which matches the node label), lamp-latimer-patent (252,386 filed 19 Feb 1881, dated 17 Jan 1882, assigned to the United States Electric Lighting Company; 247,097 filed 18 Apr 1881, dated 13 Sep 1881), lamp-latimer-invented-claim, lamp-10000-ways-quote, lamp-edison-sole-inventor. lamp-lodygin-refractory-metals and the Goebel patents: headers only (see open_items). Every established claim was checked except lamp-davy-arc (not re-opened) and the filing details of lamp-lodygin-refractory-metals. Nodes: all 41 lamp nodes were listed with time, precision, date_basis, window and place. Dates, windows and places are consistent with the sources read. Node ids that carry a day the sources do not give (lamp-1879-02-03-swan-shows-lamp-lit-and-phil, and "boston" and "st-louis" in two court ids) cannot be renamed under the append-only rule; their labels and text are honest (the Boston and St. Louis names come from 57 F. 616). The Pearl Street, Menlo Park and Tribune nodes now match the newspaper text. Headline: 95 characters, headline_status draft, the headline claim lamp-edison-sole-inventor refuted at high confidence with a primary check; "carbon lamps were patented by 1845" is carried by the King abridgment, 40 F. 21 and 54 F. 678 (a design, per S3). Assessment: answer partly, three key points, no percentages; it says no more than the claims except the two points in R3-2 and the residue in R3-1. Repository text: no model identifiers and no personal names beyond historical figures and cited authors were found in the files read. Correction to the first review: it counted Edison's US 223,898 as having two claims; the patent has four. A duplicated author_response line that had been pasted at the end of the earlier notes block was removed (it duplicated R2-11). Third review (round 4), 2026-10-02, by an independent review agent (third reviewer) that did not write the dig and took no part in rounds 1 to 3. No dig file other than this one was edited. Round 1 to 3 blocking requests R1-4, R1-5, R2-1, R2-2, R3-1 and R3-2 are now resolved by my own reading (see each reviewer_note_round4 or reviewer_note); R3-4 and R3-5 are resolved; R3-3 stays open as non-blocking (R4-6). Conformance: 0 errors, 2 warnings for this subject (lamp-swan-in-use and lamp-edison-oct-1879-test below primary); review_dig: all mechanical checks pass; the quote check cannot match stored sources (none stored) and lists 17 quotes for manual check, of which I matched by hand the abridgment, Fontaine, Supreme Court, case-law, Chemical News, Edison Papers, IET and Kommersant quotes listed above. Fresh pass: every established or refuted claim whose source I could reach was re-read against its anchor (de Moleyns, earliest patent, King/Starr, Lodygin first claim and 1872-74, Swan 1878, early 1879, before-Edison, Savoy, Cragside, first practical, 22 Oct 1879, Edison patent (four claims), high resistance (new finding R4-1), Pearl Street not reached, Sawyer and Man, patent upheld, bamboo, Goebel quotes, 10,000-ways via the earlier readers). Result: one new blocking finding (R4-1), the rest non-blocking (R4-2 to R4-7). Places and dates in the 41 lamp nodes were listed again: consistent with the sources, with the disclosed conventions (patent-grant node placed at the inventor's address; Jobard node placed in Belgium for de Changy's work; Lodygin node placed in the Academy's city; Swan nodes at window mid-points with date_basis inferred). No model identifiers, contact details or private names in the subject files or nodes. Because R4-1 is blocking and has no author response yet, the status stays revisions_requested; owner decisions listed in open_items stand. Fourth review (round 5), 2026-10-02, by an independent review agent (fourth reviewer) that did not write the dig and took no part in rounds 1 to 4. Only this file was edited. Conformance: 0 errors (15 subjects, 107 shared nodes, 92 warnings repository-wide; 2 for this subject: lamp-swan-in-use and lamp-edison-oct-1879-test, anchored below primary and shown as limits). review_dig: all mechanical checks pass; the quote check lists 39 quotes it cannot match (nothing is stored in the subject folder). Open requests: R4-1 (blocking) is resolved by my own reading of 52 F. 300, 47 F. 454 and 54 F. 678; R3-3 and R4-2, R4-3, R4-4, R4-6 and R4-7 are resolved; R4-5 is left unresolved (non-blocking residue, R5-2). All blocking requests of rounds 1 to 4 now carry resolved: true from a reviewer who verified them. Status: passed_with_open_items. Fresh pass: re-read against their anchors the claims lamp-de-moleyns-patent, lamp-earliest-patent, lamp-starr-king-patent, lamp-lodygin-1872-74, lamp-lodygin-first-claim, lamp-lodygin-refractory-metals (Google Patents text), lamp-swan-before-edison and lamp-first-practical-priority (Chemical News 42), lamp-swan-in-use (Times transcription), lamp-swan-cragside (IET blog), lamp-edison-patent, lamp-edison-high-resistance, lamp-edison-patent-upheld, lamp-edison-sole-inventor, lamp-edison-bamboo and lamp-sawyer-man-priority (159 U.S. 465: "too indefinite", "becomes unnecessary", "Affirmed", "thirty or forty different woods", "despatched a man to Japan", "about forty different kinds"), lamp-goebel-claim (54 F. 678 outcome "Injunction granted"). Surface lines checked for "first", "invented", "practical", "built", "sold", "upheld" and "settled": headline, search_summary, assessment (headline, text, key points), claim statements, would_change_if lines, tests, threads and timeline notes. Nothing says more than the claims show except the five non-blocking points in R4-5 (b) and R5-1 to R5-4. Counts: 39 claims (17 established, 5 refuted, 4 contested, 4 proposed, 9 searched gaps), 41 lamp nodes, six national stories, four firsts in the assessment, headline 95 characters. Node dates and places listed again for all 41: consistent with the sources and the disclosed conventions; Swan nodes at window mid-points with date_basis inferred. No model identifiers, contact details or private names in the subject files or nodes (grep for model names, e-mail patterns and session ids found none outside this file). Not a finding but worth the owner's eye: the dig treats a patent abridgment as primary for what a patent claims (anchor_checked primary) although neither full specification was read; the dig says so in the claims and in open items, and King is also quoted by two court opinions that I read. The review record.
refuted: the claim below is false confidence high · our conclusion
Lodygin was not the first to patent an electric light or lamp in an enclosed globe: a British patent of 1841 (de Moleyns) covers an electric light fed with pulverized charcoal in an exhausted glass globe (the Supreme Court calls it incandescent; the abridgment does not), and one of 1845 (King, for Starr) covers carbon and metal conductors "intensely heated" by a current, the carbon "enclosed in a Torricellian vacuum". The 1845 patent is the sound anchor for a heated carbon conductor in a vacuum. Those patents show earlier published designs, not that a lamp was built or worked (S3), so this does not show that anyone built a carbon lamp before Lodygin; the claim "first to build a working lamp" is not tested here.
Anchor. British patents 9053 (1841) and 10,919 (1845), as abridged by the Patent Office (1859), pp. 62-63 and 97-98.
Would change if. the 1845 patent is shown not to describe a heated carbon conductor in a vacuum (or the 1841 patent not to describe a light in an exhausted globe), or a document earlier than Lodygin's records a working carbon lamp
Evidence nodes (what each does to the statement above)
refuted: the claim below is false confidence high · our conclusion
Woodward and Evans were not the first to patent an electric lamp with carbon in an enclosed globe (carbon in a vacuum was patented in Britain in 1845), and their patented lamp is a different design from the one Edison patented: a piece of carbon in a rarefied gas, against Edison's thin high-resistance carbon filament in an all-glass globe exhausted to about one-millionth of an atmosphere. No document read shows that Edison used their design.
Anchor. US 181,613 (1876) against US 223,898 (1880), both read in full; British patent 10,919 (1845), abridgment p. 97.
Would change if. a document shows Edison used the Woodward patent's design, or the Canadian specification describes a filament in high vacuum
Evidence nodes (what each does to the statement above)
refuted: the claim below is false confidence high · our conclusion
Latimer did not invent the light bulb or the carbon filament. His 1882 patent is a manufacturing improvement filed in 1881, after carbon filaments had been patented by Edison (applied for November 1879, granted 1880) and carbon in a vacuum by King (1845); his other 1881 patent with Nichols is for mounting the carbon on the wires. His real contribution was making carbons more reliably, first for a rival company.
Anchor. US 252,386 (1882) and US 247,097 (1881) against US 223,898 (1880) and the 1845 King patent (abridgment, p. 97).
Would change if. an earlier Latimer document claiming the filament or lamp itself is found, or US 247,097 or 252,386 is read as claiming the lamp
Evidence nodes (what each does to the statement above)
refuted: the claim below is false confidence provisional · result of a search
The earliest version found is in Dyer and Martin's 1910 biography, where Walter Mallory recalls Edison saying "I know several thousand things that won't work" about the nickel-iron storage battery after "over nine thousand experiments", not about the lamp; Mallory adds that the experiments later "had run up to over ten thousand". The "10,000 ways" wording has not been found in anything earlier than the modern forms traced by Quote Investigator (1946, 1982).
Anchor. Dyer and Martin, Edison: His Life and Inventions (Harper, 1910), vol. II, pp. 615-616, read in OCR of the Internet Archive scan.
Would change if. an earlier printed or manuscript version about the lamp is found, or Edison's own record of the remark is found
Why this confidence. Starts at high (The 1910 text was read directly in a scan of the book (anchor checked: primary)).
These reasons were drafted by the project and have not yet been reviewed.
refuted: the claim below is false confidence high · our conclusion
Edison did not invent the incandescent lamp from nothing and was not its first or only inventor. British patents of 1841 (de Moleyns) and 1845 (King, for Starr) already described, respectively, an electric light fed with powdered charcoal in an exhausted globe and a heated carbon conductor in a vacuum; Woodward patented a carbon lamp in rarefied gas in 1874-76; and Swan reported a glowing carbon rod in an exhausted globe in December 1878, a rod that blackened its globe. US courts upheld the second claim of Edison's own patent (1880), a carbon filament in an all-glass exhausted receiver (claim 1, the high-resistance filament, was held limited and not infringed); in Wallace J.'s words Edison made "a lamp which was practically operative and successful" (47 F. 454, 1891), and Colt J. records that the earlier ruling held claim 2 to cover "a broad and fundamental invention, namely, an incandescent lamp, composed of a carbon filament, hermetically sealed in an all glass chamber exhausted to a practically perfect vacuum, and having leading-in wires of platinum" (54 F. 678). Whether Edison or Swan was first to a practical lamp, and a complete wired system (Pearl Street, 1882), are separate claims (lamp-first-practical-priority, lamp-pearl-street).
Anchor. British patents 9053 (1841) and 10,919 (1845), Patent Office abridgments; Chemical News 39 (1879): Swan's December 1878 rod lamp; US 181,613 (Woodward); 47 F. 454 (1891) and 52 F. 300 (1892); 54 F. 678 (1893), Colt J.; US 223,898.
Would change if. the 1845 patent is shown not to describe a heated carbon conductor in a vacuum (or the 1841 patent not to describe a light in an exhausted globe), or the courts are shown to have upheld Edison's patent as the first lamp of any kind
Evidence nodes (what each does to the statement above)
established confidence high · what a source says
Humphry Davy published an account of a brilliant arc of light between two charcoal points, powered by the Royal Institution's 2,000-plate battery; the charcoal itself was "ignited to whiteness". This is an arc light, not an incandescent lamp: the light comes mainly from a discharge across a gap, not from a solid glowing inside a bulb.
Anchor. Davy, Elements of Chemical Philosophy (1812; the Bradford and Inskeep edition scanned on the Internet Archive), pp. 85-86, read in OCR.
Would change if. an earlier published description of a sustained carbon arc is found (claims of earlier arcs by others exist and are not yet dug)
Evidence nodes (what each does to the statement above)
established confidence high · what a source says
Frederick de Moleyns received British patent No. 9053 on 21 August 1841. One of its heads is "a means of generating the electric light" by supplying pulverized charcoal to the junction of two platinum-wire coil electrodes, the whole enclosed in an exhausted glass globe. The Patent Office's abridgment does not use the words "glow" or "incandescent"; the Supreme Court (1895) describes the patent as one for an incandescent electric lamp using finely pulverized boxwood charcoal or plumbago.
Anchor. Patents for Inventions: Abridgments of Specifications relating to Electricity and Magnetism (1859), pp. 62-63 (No. 9053, A.D. 1841, August 21): second head quoted; 159 U.S. 465 (1895), the Court's description of the patent.
Would change if. the full specification shows a different design from the abridgment
Evidence nodes (what each does to the statement above)
established confidence provisional · result of a search
Two absences, not one. (1) No patent earlier than de Moleyns's of 1841 for an electric light in an enclosed globe (his: powdered charcoal fed to platinum-coil electrodes in an exhausted glass globe) has been found in the 1859 British abridgments. (2) No document earlier than King's 1845 patent for a heated conductor in a vacuum has been found: the abridgment says "intensely heated" conductors and carbon "enclosed in a Torricellian vacuum", and Fontaine's 1878 search found nothing before it ("The first document on the question that we have found"; he had missed de Moleyns, which he did not find). Absence (2) could fail at 1841: the Supreme Court (1895) calls the de Moleyns patent one "for an incandescent electric lamp" with finely pulverized charcoal, and the full specification of No. 9053 was not read; if it shows a heated charcoal conductor in an exhausted globe, absence (2) moves to 1841.
Anchor. Abridgments ... Electricity and Magnetism (1859): no earlier lighting entry read; Fontaine (1878), p. 169: 'The first document on the question that we have found, is an English patent of the 4th November, 1845.'
Would change if. an earlier patent (in Britain, France, the US or elsewhere) for an electric light in an enclosed globe, or for an electrically heated conductor in a vacuum, is found; or the full specification of de Moleyns's No. 9053 shows a heated charcoal conductor in an exhausted globe (which would move absence 2 to 1841)
established confidence high · what a source says
British patent No. 10,919 of 4 November 1845, issued to Edward Augustin King "(a communication)", covers "the application of continuous metallic and carbon conductors, intensely heated by the passage of a current of electricity, to the purposes of illumination": thin platinum foil, or carbon enclosed in a Torricellian vacuum (the empty space above a column of mercury). Judge Colt (1893) says Starr "suggested in the King patent a lamp composed of a thin pencil of carbon, inclosed in a Torricellian vacuum"; Fontaine (1878) draws the lamp as a carbon rod in a glass bell over mercury. The abridgment does not name Starr; later sources identify the inventor behind the communication as John Wellington Starr of Cincinnati.
Anchor. Abridgments ... Electricity and Magnetism (1859), pp. 97-98 (No. 10,919); 40 F. 21 (1889), quoting the specification; 54 F. 678 (1893): the court's description of Starr's lamp as prior art; Fontaine (1878), pp. 169-170.
Would change if. the full specification shows something other than a carbon conductor in a vacuum, or the Starr identification is contradicted by a document from the 1840s
Evidence nodes (what each does to the statement above)
established confidence high · what a source says
Lodygin's US patent 575,002 (filed 4 January 1893, granted 12 January 1897; Lodygin "a citizen of Russia, residing in the city of Pittsburg") covers lamp filaments of refractory metals including molybdenum and tungsten.
Anchor. US 575,002, Illuminant for incandescent lamps (Google Patents rendering of the USPTO record).
Would change if. the patent text is shown to cover something other than metal filaments
Evidence nodes (what each does to the statement above)
established confidence high · what a source says
Henry Woodward and M. Evans (Matthew, per Electrical World, 1900) of Toronto received Canadian patent No. 3,738 on 3 August 1874 for "Woodward and Evans' Electric Light". Woodward alone received US patent 181,613 (filed 4 January 1875, dated 29 August 1876). In it a piece of carbon between two electrodes is put in a globe that is emptied of air and then filled with a rarefied gas "that will not unite chemically with the carbon when hot". The patent describes no thin filament and no high vacuum.
Anchor. US 181,613 (1876), full specification read; Scientific American 31:11 (12 Sep 1874), Canadian patent list: "3,738 ... H. Woodward and M. Evans, Toronto, Ont. ... Aug. 3, 1874" (OCR damaged, read by hand).
Would change if. the Canadian specification itself (not read) describes a different lamp from the US patent
Evidence nodes (what each does to the statement above)
established confidence high · what a source says
In December 1878, at the Newcastle Chemical Society meeting "immediately preceding Christmas", Swan (in the chair) described an experiment in which a Siemens dynamo current was passed through a slender rod of carbon in an exhausted globe. The rod glowed with great splendour, but the glass became coated inside with a sooty deposit and the rod curved into a bow "as if from softening".
Anchor. Chemical News 39 (28 Mar 1879) p. 133, the meeting 'immediately preceding Christmas' with Swan in the chair, and (18 Apr 1879) p. 168, the chairman's experiment; B. S. Proctor's note in the same volume: 'At our meeting in December, 1878, Mr. J. W. Swan exhibited an electric lamp'.
Would change if. the Society's own minutes show a different lamp or a live, durable demonstration
Evidence nodes (what each does to the statement above)
established confidence moderate · what a source says
In his lecture of 20 October 1880 to the Newcastle Literary and Philosophical Society, Swan said of "this little lamp, which I showed here two years ago in action" that it was "composed entirely of three substances, namely, glass, platinum, and carbon", and he began by referring to his last lecture on electric lighting "almost two years ago". No 1879 report of the showing was found. Secondary accounts date it 3 February 1879 (or 17 January).
Anchor. Swan, lecture of 20 Oct 1880, Chemical News 42 (5 Nov 1880), pp. 227 and 230, read: 'this little lamp, which I showed here two years ago in action'.
Would change if. Society records show no such demonstration in 1879, or a contemporary report describes it
Evidence nodes (what each does to the statement above)
established confidence moderate · what a source says
The Times of 29 December 1881 (read in a transcription) reports that Swan incandescent lamps lit the stage of the Savoy Theatre, London, for the first time at a performance of Patience on the afternoon of 28 December 1881; the auditorium had had electric light since the theatre opened. (The Cragside half of the earlier version of this claim is now lamp-swan-cragside.)
Anchor. The Times, 29 Dec 1881, as transcribed by the Gilbert and Sullivan Archive (the original page was not compared): 'the stage was for the first time lit up by the electric light ... The Swan incandescent lamps were used.'
Would change if. the original Times page gives different dates or wording
Evidence nodes (what each does to the statement above)
established confidence moderate · what a source says
The Edison Papers' edition of Charles Batchelor's laboratory notebook entry for 22 October 1879 records a lamp of carbonised cotton thread ("6 cord thread No 24") that was "on from 1.30 AM till 3 pm 13 1/2 hour and was then raised to 3 gas jets for 1 hour then cracked glass & busted". The Papers' essay says that by 16 November 1879 the laboratory had "the first lamp that answers the purpose we have wished", a carbonised card horseshoe.
Anchor. Papers of Thomas A. Edison, Doc. 1831 (a transcription of Batchelor's notebook entry, '[Menlo Park,] Oct 22nd 1879 9 A.M.'); Edison Papers essay 'The Carbon-Filament Lamp' (22 Oct and 16 Nov 1879).
Would change if. the notebook image (N-79-07-31, p. 105; Edison Papers digital edition TAED N052:52) is read and gives a different figure
Evidence nodes (what each does to the statement above)
established confidence high · what a source says
Edison's US patent 223,898, "Electric-Lamp", was applied for on 4 November 1879 (signed 1 November) and granted on 27 January 1880. Its first two claims (of four) are: a carbon filament of high resistance; and carbon filaments in a receiver made entirely of glass, exhausted of air, with wires sealed through the glass.
Anchor. US 223,898, full specification and claims (signed 1 Nov 1879; patented 27 Jan 1880); 40 F. 21 (1889): 'applied for November 4, 1879, and issued January 27, 1880'; 52 F. 300 (1892): 'under an application filed November 4, 1879, letters patent No. 223,898 were issued'.
Would change if. the USPTO record is shown to be misread
Evidence nodes (what each does to the statement above)
established confidence high · what a source says
What set Edison's lamp apart, as his patent and Wallace J. (47 F. 454, 1891) described it, was high resistance (100 to 500 ohms in the patent's example) in a thin carbon filament in an all-glass high-vacuum bulb, which let many lamps run side by side ("in multiple arc") from one supply without enormous copper mains. High resistance was NOT made a limit of what was upheld: the circuit court held claim 1 (the high-resistance filament "made as described") limited to leading wires secured by cement carbonised in situ and not infringed, which the complainant did not appeal; on appeal Lacombe J. (52 F. 300, 1892) upheld claim 2 and refused to read into it "that the filament must be one of high specific resistance, or of at least 100 ohms resistance", the draughtsman having omitted "of high resistance" and "made as described". The high-resistance idea itself was not unique to him: the 1891 court noted Lane-Fox's 1878-79 British patents and a letter of his to the Times of December 1878, and the 1892 appeals court noted Edison's own French patent of May 1879 (a platinum burner) as already stating it.
Anchor. US 223,898 specification; 47 F. 454 (1891), Wallace J. (Lane-Fox patents and letter); 52 F. 300 (1892), Lacombe J. (Edison's French patent No. 130,910 of 28 May 1879).
Would change if. the 1891-92 opinions are shown to rest the patent on something else, or to make high resistance a limit of the upheld claim
established confidence high · what a source says
In the Supreme Court's 1895 account, which rests on trial testimony, Edison, after trying "thirty or forty different woods" and many other fibres, found his best burner in a strip of bamboo (one that "formed the edge of a palm-leaf fan", in the OCR's 'palmieaf'), "despatched a man to Japan" to arrange supplies, and the messenger he sent "to different parts of Japan and China sent him about forty different kinds of bamboo". The Court describes the commercial Edison lamp of the case as having a burner of carbonised bamboo.
Anchor. 159 U.S. 465 (1895), Brown J., the Court's account of Edison's search, read in the Library of Congress scan.
Would change if. Edison laboratory or factory records give a different material or date
established confidence high · what a source says
On 4 September 1882, at 3 p.m., the Edison Electric Illuminating Company turned on the electric light in part of the first of its districts in New York, supplied from a central station on Pearl Street just below Fulton Street (New-York Tribune, 5 September 1882).
Anchor. NY Tribune, 5 Sep 1882, p. 8, read in the ALTO OCR text of the Library of Congress scan: 'The company at 3 p.m. turned on the electric light in part of the first of the districts ... The central station ... is at ... Pearl-st., just below Fulton-st.'; 'yesterday' dates it to 4 September.
Would change if. company records give a different date
Evidence nodes (what each does to the statement above)
established confidence high · what a source says
In the US Patent Office, an interference declared in September 1880 between Edison (application of December 1879) and William Sawyer and Albon Man (application of 9 January 1880), over carbon made from paper, was "not finally decided until the beginning of 1885", when the Commissioner of Patents awarded priority of invention to Sawyer and Man (as 40 F. 21 recounts it). Their patent (No. 317,076, granted 12 May 1885) was held invalid in 1889: apart from its third claim (carbonised paper), it amounted to a claim to all fibrous carbons. The Supreme Court affirmed the decree on 11 November 1895, holding that the claims "with the exception of the third, are too indefinite to be the subject of a valid monopoly" and that the question of priority "becomes unnecessary"; it did not itself decide that Sawyer and Man's third claim was invalid, which was admitted not to be infringed by the Edison lamp.
Anchor. Consolidated Electric Light Co. v. McKeesport Light Co., 40 F. 21 (1889), Bradley J.; The Incandescent Lamp Patent, 159 U.S. 465 (1895), Brown J., headnote and the passages 'we are all agreed that the claims of this patent, with the exception of the third, are too indefinite' and 'becomes unnecessary'.
Would change if. the Patent Office interference record is read and disagrees with the 1889 opinion's account
Evidence nodes (what each does to the statement above)
established confidence high · what a source says
Edison's lamp patent was upheld in court: in Edison Electric Light Co. v. United States Electric Lighting Co., the second claim (carbon filaments in an all-glass exhausted bulb) was held valid and infringed in 1891 (July, per 57 F. 616), and the appeals court affirmed on 4 October 1892.
Anchor. 47 F. 454 (C.C.S.D.N.Y. 1891); 52 F. 300 (2d Cir. 4 Oct 1892); 57 F. 616 (1893) for the July 1891 date of the first judgment.
Would change if. the opinions are misread
Evidence nodes (what each does to the statement above)
established confidence high · what a source says
Lewis Latimer's US patent 252,386, "Process of Manufacturing Carbons" (filed 19 February 1881, granted 17 January 1882), improves how carbon filaments are made: blanks of paper or wood are carbonised inside cardboard envelopes so that they are protected from sticking, breaking and warping. It was assigned to the United States Electric Lighting Company of New York. With J. V. Nichols he also held US patent 247,097, "Electric Lamp" (filed 18 April 1881, dated 13 September 1881), for mounting the carbon strip on its wires.
Anchor. US 252,386 and US 247,097, both read in OCR of the USPTO scans (claims and assignment lines).
Would change if. the patent record is misread
Evidence nodes (what each does to the statement above)
contested confidence moderate · our conclusion
Whether Swan, not Edison, should be credited with the incandescent lamp. Swan reported a glowing carbon rod in an exhausted globe in December 1878 (a rod that blackened the glass and bent) and said in 1880 that he had shown a glass, platinum and carbon lamp "two years ago"; Edison's laboratory kept a thread lamp lit 13 1/2 hours on 22 October 1879 and applied for its patent on 4 November 1879; in his October 1880 lecture Swan described his own lamp's carbon as "extremely thin — a mere hair" and said (of his own experiments) that blackening of the globe stopped once the vacuum and the contacts were good. Swan also says that in October 1877 he sent Mr. Stearn carbons of carbonised cardboard to be mounted in glass globes and exhausted. No Swan patent on the basic lamp dated before Edison's was found, but Swan's patents were not searched.
Anchor. Chemical News 39 (1879) and 42 (1880), read; Edison Papers, Doc. 1831 (notebook transcription), read; 47 F. 454 (1891); US 223,898.
Would change if. Swan's 1879 lamp is shown to have lasted in use, or an earlier Swan patent on the basic lamp is found
Evidence nodes (what each does to the statement above)
Disputed by.
contested confidence low · our conclusion
Who first made, and who first sold, a lamp practical for ordinary use is not settled by anything read here. Edison's laboratory had by 16 November 1879 a lamp it called "the first lamp that answers the purpose we have wished" (carbonised card), and Wallace J. (1891) found Edison "the first to make a carbon of materials and by a process which was especially designed to impart high specific resistance to it" and the first to combine such a burner with the necessary adjuncts, so that "he made a lamp which was practically operative and successful". Lacombe J. (52 F. 300, 1892) said "the knowledge that practical stability could be given to a carbon filament was not gained until October, 1879", a court's view from the patent suit and not a dated record. Edison's company turned on its first Pearl Street district on 4 September 1882. Swan said in October 1880 that he now used a material better than carbonised cardboard; Swan lamps lit Cragside in 1880 (an IET blog; the letter of 17 January 1881 is not read) and the Savoy stage on 28 December 1881. Both Swan dates come before Pearl Street, and no document read shows who sold the first lamp.
Anchor. 47 F. 454 (1891), Wallace J., quoted; Edison Papers essay and Doc. 1831 (22 Oct and 16 Nov 1879); NY Tribune 5 Sep 1882, p. 8 (Pearl Street); Chemical News 42 (1880); IET Archives blog (Cragside); The Times 29 Dec 1881 via transcription (Savoy).
Would change if. a dated sale, order, price list or company record for lamps by Swan or Edison before the other's is found, or Armstrong's letter and the original Times page are read and give different dates
Evidence nodes (what each does to the statement above)
Disputed by.
contested confidence moderate · our conclusion
Whether Edison gave a public demonstration on New Year's Eve 1879. The New York Herald of 21 December 1879 reported that "the first public exhibition" of his light was "announced to take place on New Year's Eve at Menlo Park"; the Herald of 31 December (dateline Menlo Park, 30 December) said "the public exhibition may be said to be actually going on now"; the New-York Tribune of 1 January 1880 reported crowds at Menlo Park the evening before under a headline that no public exhibition was "promised or given", called the announcement "unauthorized" and quoted Edison as disclaiming "any formal exhibition".
Anchor. NY Herald, 21 Dec 1879, p. 5; NY Herald, 31 Dec 1879, p. 3 (dateline 30 Dec); NY Tribune, 1 Jan 1880, p. 8; all read in OCR of the Library of Congress scans (ALTO text).
Would change if. an Edison laboratory record or third newspaper settles the event's nature
Evidence nodes (what each does to the statement above)
Disputed by.
contested confidence low · our conclusion
Whether Heinrich (Henry) Göbel built practical carbon-filament lamps in New York in 1854, before Edison. No dated document from before 1882 that records such lamps has been found, on either side. On motions for preliminary injunctions, the Boston court (54 F. 678, Colt J.) found it "extremely improbable that Henry Goebel constructed a practical incandescent lamp in 1854" while saying the weight of evidence "is in the direction that he made" the three early "fiddle bow" lamps or similar ones, but "assuming they were made, they do not anticipate the invention of Edison. At most they were experimental toys"; and found it "simply impossible, under the circumstances, to believe that a lamp so constructed [lamp No. 4] could have been made by Goebel before 1872" (a finding on credibility). The Wisconsin court (57 F. 616, Seaman J.), and the Seventh Circuit on appeal in the same case (61 F. 834), held the new defence not proved on the motion (the Seventh Circuit saying it was "without designing to suggest what result should be reached upon final hearing"); the St. Louis court (56 F. 496, Hallett J.) found "a fair preponderance of testimony in support of the Goebel claim" and refused an injunction on condition of a $20,000 bond. That is two cases against one, on a preliminary record and under different burdens of proof.
Anchor. 54 F. 678 (D. Mass., 18 Feb 1893), Colt J.; 56 F. 496 (E.D. Mo., 21 Apr 1893), Hallett J.; 57 F. 616 (E.D. Wis., 20 Jul 1893), Seaman J.; 61 F. 834 (7th Cir., 1 May 1894); US 266,358 (1882), Göbel's lamp patent, a socket detail; US 47,632 (1865), Göbel's sewing-machine hemmer.
Would change if. a dated document from before 1879 (newspaper, advertisement, letter, patent caveat) describing Göbel's lamp is found, or a full trial record tests the affidavits
Evidence nodes (what each does to the statement above)
Disputed by.
proposed confidence low · what a source says
Fontaine (1878) prints a communication he says "M. Jobart, of Brussels" made to the Academy of Sciences on 27 February 1858 about the lamps of de Changy: small lamps "enclosed in hermetically sealed glass tubes", lit by "the incandescence of platinum", intended for mines and street lighting, one of which "was lit in the hollow of my hand". Fontaine places de Changy "in Belgium" and dates his substitution of platinum for carbon to 1857; Howell and Schroeder (1927) call him a French civil engineer who held a Belgian patent of 1856. His nationality is therefore not settled here. This is one witness (Jobard) relayed through one book.
Anchor. Jobard's 1858 communication as quoted in Fontaine, Electric Lighting (1878), pp. 186-187; Howell and Schroeder (1927), p. 33 (nationality and patent).
Would change if. Jobard's report in the Comptes rendus (1858) is read and says otherwise, or confirms it in the original
Evidence nodes (what each does to the statement above)
proposed confidence low · what a source says
Fontaine (1878) says that in 1873 a Russian physicist, Lodygin, invented a new lamp in which small carbon bars are heated in a hermetically sealed glass receiver from which the oxygen is expelled, and that in 1874 the St Petersburg Academy of Sciences awarded him "a high prize" (the Lomonosov prize) on a report by Wild; Fontaine adds "Nothing is less practical nor less studied than the apparatus of this inventor." Kommersant (2024) gives 1872 for Lodygin's first demonstration (the sentence that gives 1872 names no place; elsewhere the page speaks of a demonstration "in Petersburg") and says the home patent office issued him privilege No. 1619 on 11 July 1874 with its priority dated "retroactively, from 2 October 1872" (one newspaper history, no scan; the same page says the Russian patent came "only a year" after the 1872 petition, which does not fit July 1874, so the number and date are unverified, low confidence).
Anchor. Academy report by Wild, quoted in Fontaine (1878), pp. 171-173; Kommersant (St Petersburg, doc 6822124): 1872 first demonstration and petition, privilege No. 1619 of 11 July 1874 with priority from 2 Oct 1872.
Would change if. the Academy's 1874 prize report or the privilege itself is read and disagrees or confirms
Evidence nodes (what each does to the statement above)
proposed confidence low · what a source says
A trade-press piece of 14 April 1900 (Electrical World and Engineer), based on two Toronto electrical men, says the first lamp was built at Morrison's brass foundry in Toronto and was "a very crude affair", that Woodward filled the globe with nitrogen after exhausting the air, that investors declined to put up more money, and that Woodward left for Europe. Fontaine, who toured the US the year before his 1877 French edition, mentions the 1876 patent only in passing. No contemporary report of the lamp working in use, or being made for sale, was found.
Anchor. Electrical World and Engineer 35:15 (14 Apr 1900): the Toronto informants' account; Fontaine, Electric Lighting (1878), pp. 190-191: 'a patent taken out by Mr. Henry Woodward, in 1876'.
Would change if. a contemporary 1874-79 report of the lamp working in use is found
proposed confidence low · what a source says
An IET Archives blog (2023) says that Armstrong replaced arc lamps at Cragside, his house at Rothbury, Northumberland, in 1880 with 45 incandescent lamps, and, in a separate passage, that Armstrong wrote to the editor of The Engineer on 17 January 1881 "shortly after he utilised Joseph Swan's newly invented incandescent light bulbs". That the 1880 lamps were Swan's, and the date they were first lit, are therefore joined by the blog from two passages; the letter itself was not read.
Anchor. IET Archives blog 'Cragside: harnessing the power of water' (9 Mar 2023): 'replaced by Armstrong in 1880 with 45 incandescent lamps'; the letter of 17 January 1881 'shortly after he utilised Joseph Swan's newly invented incandescent light bulbs'. The letter itself was not read.
Would change if. Armstrong's letter of 17 January 1881 (IET Archives NAEST 046/24, The Engineer) is read and gives different lamps or dates
Evidence nodes (what each does to the statement above)
searched gap confidence low · result of a search
The date of Davy's first arc demonstration (given variously as 1808, 1809 or 1810; the Supreme Court in 1895 says "as early as 1810") and whether his 1802 papers describe wires or charcoal glowing as a light source are not yet read in the original.
Anchor. Searched: Davy's 1812 book (no date for the demonstration) and the Supreme Court's passage (a court's statement, 1810). Not read: Journals of the Royal Institution, vol. 1 (1802).
Would change if. the Journals of the Royal Institution (1802) and the Royal Institution's lecture records are read
Next step. Read Davy's 1802 papers in the Journals of the Royal Institution, vol. 1 (the University of Pennsylvania transcription returned 403 from here; try the Royal Institution archive or a Google Books scan).
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searched gap confidence low · result of a search
The often-repeated claim that Warren de la Rue made a platinum-coil lamp in an evacuated tube in 1840 has no primary record found. The trail leads to a 1927 history that dates a de la Rue lamp to 1820 and says its vacuum is unexplained, while a 1923 Smithsonian history credits the 1840 platinum-coil lamp to William Grove instead.
Anchor. Howell and Schroeder, History of the Incandescent Lamp (1927): 'De la Rue ... 1820'; Schroeder, History of Electric Light (Smithsonian, 1923): Grove, 1840. Searched and not found: Fontaine (1878), the 1859 British abridgments.
Would change if. a paper, notebook or lecture report by de la Rue from 1820-1850 describing the lamp is found, or Grove's own 1840 description is read and shows the attribution swapped
Next step. Search de la Rue's and Grove's papers in Philosophical Magazine and Proceedings of the Royal Society, 1838-1845, for a platinum lamp; then check which history first wrote "de la Rue, 1840".
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searched gap confidence low · result of a search
Whether, when and for what Lodygin sold patent rights to General Electric (often given as 1906).
Anchor. Seen in search results in the first session: skillbox.ru and minervaclassics.com (no documents cited). Neither is in the sources manifest and neither was re-read in the revision; the Kommersant page read (doc 6822124) does not mention General Electric.
Would change if. a USPTO assignment record or GE document is found
Next step. Search USPTO assignment records for patent 575,002 and the GE archives (Schenectady) for Lodyguine.
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searched gap confidence low · result of a search
Whether Edison bought the Woodward and Evans patent rights, and when and for how much (popular accounts: 1879, $5,000). No document of a purchase was found.
Anchor. Electrical World 1900: the purchase is reported second-hand by two Toronto electrical men, 'purchased by Mr. Edison at the time when he was making his original investigations', with no date or price. US 181,613 shows no assignment to Edison.
Would change if. an assignment, contract, payment record or Edison letter about Woodward is found
Next step. Search the Edison Papers (Rutgers) for "Woodward" (the notebook viewer is blocked here by a browser check), the USPTO assignment digests for patent 181,613 after 1876, and Library and Archives Canada assignment records for Canadian patent 3,738.
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searched gap confidence low · result of a search
Joseph Swan's experiment with a carbonised-paper arch in a vacuum "about twenty years ago" (that is, about 1860) is known only from his own lecture of 20 October 1880. No record from the 1850s or early 1860s was found.
Anchor. Swan, lecture of 20 Oct 1880, Chemical News 42 (5 Nov 1880), pp. 227-230, read: 'an experiment which I tried about twenty years ago'; the carbon arch 'became red-hot' and bent until it broke. Nothing contemporary found.
Would change if. a dated notebook, letter or society report from 1850-1865 is found
Next step. Search Swan's papers (Tyne and Wear Archives) and the 1929 memoir by his children (not on archive.org) for contemporaneous records.
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Evidence nodes (what each does to the statement above)
searched gap confidence low · result of a search
The exact date and content of Swan's early-1879 Literary and Philosophical Society demonstration.
Anchor. Newcastle University Special Collections blog; Linda Hall Library; Histelec (dates disagree), seen only as search summaries; Swan's 1880 lecture gives only 'two years ago'.
Would change if. the Society's 1879 minutes or a Newcastle newspaper report is read
Next step. Read the Lit and Phil's 1879 minute book or annual report, and the Newcastle Daily Chronicle for Jan-Feb 1879.
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searched gap confidence low · result of a search
The common statement that Edison's vacuum came from Hermann Sprengel's mercury pump (1865) is not yet anchored. Edison's patent and the 1879 Herald say only "mercury pump".
Anchor. US 223,898: 'mercury-pump', no name; NY Herald 21 Dec 1879: 'mercury pump'. Swan (1880) names the Sprengel pump for his own lamps.
Would change if. an Edison laboratory record or Francis Upton letter names the Sprengel design
Next step. Search the Edison Papers for 'Sprengel' (1879), and read Sprengel's 1865 paper in J. Chem. Soc.
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searched gap confidence low · result of a search
What Hans-Christian Rohde's 2007 study of the court record found about how the Göbel story was built.
Anchor. Rohde 2007, known only through summaries on lerncafe.de, goebel-projekt and radiomuseum.org, which say the court record does not support Göbel as inventor; the book was not read.
Would change if. the book is read
Next step. Read Rohde, Die Göbel-Legende (zu Klampen, 2007), and Dittmann's review in Technikgeschichte 74(2), 2007, pp. 149-160 (paywalled).
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searched gap confidence low · result of a search
Latimer's later role with the Edison companies (engineering staff, patent expert witness, Edison Pioneers).
Anchor. The Queens Borough Public Library essay 'Inventing a Better Life: Latimer's Technical Career', hosted by the Edison Papers (secondary, read 2026-10-02): from about 1885 Latimer was in the Engineering Department of the Edison Electric Light Company, from about 1889 in its Legal Department, testified in a number of cases, and was a founding Edison Pioneer in 1918. The essay cites records that were not read.
Would change if. Edison company records or court testimony naming him are read
Next step. Read the Latimer papers (Queens Borough Public Library) and the Edison Papers for Latimer, 1884-1912.
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These pages are generated from plain YAML: claims.yaml · sources manifest. If you can show a finding is wrong, challenge it.