English Wikisource, 2026-10-06 (Investigator, Step I, run 1)
Site: https://en.wikisource.org (reached through Chrome; no blocks). Six pages read. Searches: arrived via Google queries (see 2026-10-06-google.md), then the Poincare author page and on-page find for "gravitation", "Mercury", "perihelion".
1. The project document itself, with its date and French original (priority 1)
URL: https://en.wikisource.org/wiki/The_New_Mechanics_(G%C3%B6ttingen) - The header gives the exact source: "The Monist (1913), Vol. 23, pp. 385-395". The French original is "La Mecanique nouvelle" in Sechs Vortrage uber ausgewahlte Gegenstande aus der reinen Mathematik und mathematischen Physik. This is the volume of six lectures Poincare gave in Gottingen on 22-28 April 1909 at the invitation of the Wolfskehl Commission. It was printed in 1910, pp. 49-58 [web, URL above]. - The Wikisource text matches the project PDF word for word as far as compared: the opening sentence, the 1/200 000 000 figure, Kaufmann, 38" and 32", the "pedagogic danger" ending. So the project PDF is Halsted's 1913 Monist translation of the Gottingen lecture of April 1909 [web; compared with deep/TheNewMechanics-7c45ca.md]. - Bearing: facts.json gives the year as unknown, with a [memory, medium] guess of "about 1910". The web record is The Monist vol. 23, 1913, which is posthumous: Poincare died in 1912 [memory, high]. The lecture is dated 28 April 1909 (see the google notes for a second source on the date). JSTOR lists it as Vol. 23, No. 3, July 1913 (Google snippet, see google notes). - The page title says "(Gottingen)", which separates it from two other Poincare texts with the same title: "The New Mechanics (1908)", the Science and Method chapter, and the Lille lecture (see fr-wikisource notes).
2. Poincare's author page: his own related works (priority 1)
URL: https://en.wikisource.org/wiki/Author:Henri_Poincar%C3%A9 Relevant own works listed [web]: - The Theory of Lorentz and the Principle of Reaction (1900) - The Measure of Time (1898). Clock synchronisation by light signals, the idea behind the Paris/Berlin example in the essay. - The Principles of Mathematical Physics (1904; St Louis lecture) - On the Dynamics of the Electron (1905 short note; 1905/6 Palermo memoir) - The End of Matter (1906). Same theme as the essay's "no matter, only gaps in the ether". - The New Mechanics (1908). The Science and Method book III version. - The New Mechanics (1909, tr. 1913 Halsted). The project document.
3. "On the Dynamics of the Electron" (1905/6), Poincare's technical version of the essay's claims (priority 1)
URL: https://en.wikisource.org/wiki/Translation:On_the_Dynamics_of_the_Electron_(July) Source: Rendiconti del Circolo matematico di Palermo 21: 129-176; received 23 July 1905, published January 1906 [web]. What it adds to the essay's points [web, quotes from the translation]: - Claim 2 (relativity without restriction): Poincare names the "Postulate of Relativity" and admits it "without restriction". He adds that it "may be either confirmed or disproved later by more precise experiments". In the essay it has "absolute value". Here it is a postulate open to test. - Claim 3 (deformation): here the contraction is attributed by name: "An explanation was proposed by Lorentz and FitzGerald ... this contraction, which we will call Lorentz contraction". The essay names nobody for it. - Claim 4 (electromagnetic mass, Kaufmann): "if the inertia of matter is exclusively of electromagnetic origin, as it is generally admitted since the experiment of Kaufmann". Poincare finds that a non-electromagnetic "constant external pressure" on the deformable electron is needed (the later "Poincare stress"). The essay says only the ether is inert; the memoir requires one extra force that is not electromagnetic. - Claim 5 (gravity): "we are forced to suppose that the propagation of gravitation is not instantaneous, but happens with the speed of light ... this propagation effect is mainly compensated by a different cause, so that there is no more contradiction between the proposed law and the astronomical observations". If gravity propagates at light speed, this "must be due to a function of the ether" (section 9, "Hypotheses on gravitation"). - The memoir has the full mathematics the essay leaves out: the Lorentz transformation x' = kl(x + et), t' = kl(t + ex), k = 1/sqrt(1 - e^2) in units with c = 1; the Lorentz group (section 4); the principle of least action (sections 2-3); the invariant x^2 + y^2 + z^2 - t^2. The reviewers can use it to check the essay's qualitative claims. - A second link, "On the Dynamics of the Electron (1905)", leads to the short Comptes rendus note of June 1905 (listed on the author page, not opened).
4. Lorentz 1900, "Considerations on Gravitation": the source of the law in the essay (priority 3)
URL: https://en.wikisource.org/wiki/Considerations_on_Gravitation Source: Proceedings of the Royal Netherlands Academy of Arts and Sciences, 25 April 1900, 2: 559-574 [web]. - This is the "new law of attraction containing the velocities of the two bodies" that the essay credits to Lorentz [read: p.9]. - Section 10 [web: page image of the Wikisource rendering]: for Mercury, Lorentz takes the apex of the Sun's motion at RA 276 deg, Dec +34 deg. Per revolution he gets Delta-varpi = 162 x 10^-10 (varpi = longitude of perihelion). He then says: "The changes that take place in a century are found from these numbers, if we multiply them by 415 ... introduce the factor 2,06 x 10^5. The result is, that the changes in phi, theta, varpi, and kappa' amount to a few seconds". The investigator's arithmetic on Lorentz's own numbers: 162e-10 x 415 x 2.06e5 = about 1.4" per century for varpi. - His conclusion: "our modification of Newton's law cannot account for the observed inequality in the longitude of the perihelion -- as Weber's law can to some extent do -- but ... there is nothing against the proposed formulae". He adds: "gravitation may be attributed to actions which are propagated with no greater velocity than that of light". He discusses Laplace's limit on the speed of gravity and argues that his theory avoids it. - Bearing on claim 5: the 1900 Lorentz figure (about 1.4"/century, with the Sun's motion included) is not the 6" in Poincare's Lille text. Poincare's later figure seems to come from a different, Lorentz-invariant version of the law (see de Sitter below). The reviewers should not assume that "Lorentz's law" means one fixed number.
5. de Sitter 1911, independent calculation of the relativistic gravity laws (priority 2)
URL: https://en.wikisource.org/wiki/On_the_bearing_of_the_Principle_of_Relativity_on_Gravitational_Astronomy Source: Monthly Notices of the Royal Astronomical Society, Vol. 71, pp. 388-415 (1911) [web]. - Footnote 3 names the two laws he treats: Poincare, "Sur la dynamique de l'electron", Rend. Palermo xxi p.129 (Dec. 1905), and Minkowski, Gottinger Nachrichten 1908 p.53 [web]. - Equation (37), "The motion in one century", law II: "For Mercury: = +7".15", with Venus 1.43, Earth 0.639, Mars 0.225, Jupiter 0.0104, etc. A second column gives Mercury +1".470 [web: page screenshot]. With law I, de Sitter says there are no secular terms of that kind. - Footnote 10: "This was also found by Mr. Wacker, who gives for Mercury 7".2 per century". Footnote 11: "The value 6".69 quoted by Professor Lorentz in his Gottingen lecture (Physikalische Zeitschrift vol. xi p.1234, October 1910, cited p.1239) was a first approximation" [web]. - Bearing on claim 5: an independent astronomer (de Sitter) and Wacker each got about 7" per century for Mercury from a Poincare/Minkowski-type relativistic gravity law. Lorentz quoted 6".69 in 1910. Poincare's Lille text says the new mechanics gives "6"" and leaves "32"". All three figures are of the same size and are per century. This supports reading the essay's 38" and 32" as arcseconds per century, which the essay itself never states (deep read section 1). Footnote 2 also records that Plummer (M.N. Jan 1910) and Whittaker (M.N. Feb 1910) still used the word "aether", while de Sitter says the principle is "essentially independent of the concept of an aether".
6. Bucherer 1908: the experiment Poincare names at Lille (priority 2)
URL: https://en.wikisource.org/wiki/Translation:Measurements_of_Becquerel_rays Source: A. H. Bucherer, "Messungen an Becquerelstrahlen. Die experimentelle Bestatigung der Lorentz-Einsteinschen Theorie", Physikalische Zeitschrift 9, 755-762 (1908), with the printed discussion [web]. - Bearing on claim 1: this is a measurement of the essay's radium "projectiles" (beta rays) deflected by electric and magnetic fields [read: p.3]. Bucherer used a velocity-selecting condenser inside a 140-gauss solenoid with radium fluoride. At beta = 0.3178 to 0.6879, e/m0 from the Lorentz formula stays at 1.695-1.706 x 10^7. The Abraham ("Maxwell") formula drifts from 1.676 to 1.578. Bucherer concludes "the decision turns out in favor of the Lorentz-Einstein theory". A supplement corrects the values to 1.730 [web, table]. - Bearing on claim 4: Bucherer records that Kaufmann "drew the conclusion with certainty, that the relativity theory shall be considered as disproved by his experiments". Kaufmann's results were therefore used both ways. Poincare's essay cites Kaufmann only for "constant real mass ... null" [read: p.8]. It does not mention Kaufmann's own anti-Lorentz conclusion, and the Gottingen text does not mention Bucherer at all. - Dissent in the printed discussion: Bestelmeyer says he is "not convinced that the mentioned sources of error actually play no role". He estimates that about +/-10% of rays pass with off-nominal speed, and that the Lorentz-Abraham difference is "only a few tenths of a millimeter". Bucherer lists errors he sees in Kaufmann's work: a 5% asymmetry, condenser resistance of several megohms, plate pressure, and drift of a permanent magnet. Minkowski calls the rigid electron "a monster" and "a working hindrance". Voigt and Minkowski note that Voigt had the transformation in 1887. - The question of how good the Kaufmann and Bucherer data really were is itself studied by historians. Google showed "Hazy Spots on Photographic Plates" (Historical Studies in the Natural Sciences, UC Press, 2023), which was not opened.