2026-10-08 Internet Archive (archive.org): Lorentz's own works

Method: scripted search through the archive.org advancedsearch API. The full-text (djvu.txt) files were fetched with curl into research/pages/ and grepped. No PDFs were downloaded. Queries: - creator:(Lorentz, H*) AND mediatype:texts (217 hits, most unrelated) - title:(Relativitätsprinzip) AND (Lorentz) (no hits) - Lorentz AND ("drei Vorlesungen" OR Teylers) (1 hit)

Lorentz items found (priority 1: the inventor's own work)

[web] https://archive.org/details/cu31924005244615 ; https://archive.org/details/bub_gb_89PPAAAAMAAJ ; https://archive.org/details/in.ernet.dli.2015.78238 ; https://archive.org/details/problemsofmodern0000halo

Finding 1. The first edition (1909) already reports Bucherer's confirmation (bears on claim 3)

The 1909 text has Note 87 "(Page 230)" [web] https://archive.org/stream/cu31924005244615/cu31924005244615_djvu.txt:

"Recent experiments by Bucherer, on the electric and magnetic deflexion of β-rays, made after a method that permits a greater accuracy than could be reached by Kaufmann (§ 179) have confirmed the formula (313) for the transverse electromagnetic mass, so that, in all probability, the only objection that could be raised against the hypothesis of the deformable electron and the principle of relativity has now been removed. In the mean time, this principle has already been the subject of several important theoretical investigations." It cites Bucherer, Phys. Zeitschr. 9 (1908) p.755, "Die experimentelle Bestätigung der Lorentz-Einstein'schen Theorie".

The 1916 edition replaces this with Note 86 "(Page 230) [1915]" [read: PDF p.348]: "Later experiments by Bucherer, Hupka, Schaefer and Neumann and lastly Guye and Lavanchy have confirmed the formula (313)...", and the rest of the sentence is the same. In the 1909 edition, §179 still says the Kaufmann data are "decidedly unfavourable to the idea of a contraction, such as I attempted to work out" and that "it seems very likely that we shall have to relinquish this idea altogether" (grep of the 1909 djvu text).

So: Lorentz's judgement that the deformable electron was confirmed dates from the first edition (1909, on Bucherer 1908 alone). The 1915 note widened the list of experiments. claims.md claim 3 and facts.json ("in 1915 he cites ...") are correct as far as they go, but a reader could take 1915 as the date of his change of mind. Also, the note number changed (87 in 1909, 86 in 1916). See "Corrections to earlier documents" in sites.md.

Other 1909 checks (grep counts in the 1909 text): "simply postulates" 1 (so the Einstein comparison of p.230 is in the 1909 text); "chief cause of my failure" 0 (so Note 72* is new in 1915, as claims.md says); "substantiality" 2; "Voigt has applied" 1 (the Voigt footnote is already in 1909); "Hupka" 0; "Guye" 0.

Finding 2. Lorentz, Das Relativitätsprinzip (Haarlem lectures, 1913; Teubner 1914) (bears on claims 5 and 6)

[web] https://archive.org/stream/bub_gb_89PPAAAAMAAJ/bub_gb_89PPAAAAMAAJ_djvu.txt (OCR is noisy; the quotes below are cleaned). Lorentz's argument in this passage runs as follows. Observers A and B, who can exchange their thoughts, could argue about which of them has moved. If there is nothing but them and their laboratories, the question is meaningless. "But if there is an ether that still possesses so much substantiality that it makes sense to speak of motion relative to it", the question "who has moved relative to the ether" would have a meaning, yet A and B could still not decide it. The relativity principle is assumed valid throughout. The same holds for their rods, and for their clocks and simultaneity. Then:

"Einstein says, briefly and well, that all the questions just named have no meaning. He thus arrives at an 'abolition' of the ether. The latter is, by the way, to a certain degree a dispute about words: it makes no great difference whether one speaks of the vacuum or of the ether." "...it will depend to a large extent on the way of thinking one is used to, whether one feels most drawn to the one view or the other. As for the lecturer himself, he finds a certain satisfaction in the older views, that the ether at least still possesses some substantiality, that space and time can be sharply separated, that one may speak of simultaneity without further specification." He ends by saying that the "bold assertion" that no speed greater than light will ever be observed contains "a hypothetical restriction of what is accessible to us, which cannot be accepted without some reserve."

This is Lorentz's own 1913 statement of the position summarised in claim 6 (Theory of Electrons p.230 [read: PDF p.239]). It adds two things the book does not say: (a) he calls the choice between the views largely a matter of habit of thought and partly "a dispute about words"; (b) he keeps a reservation about the light-speed limit.

The same lecture series discusses Maxwell's proposal to find the solar system's motion through the ether from the eclipses of Jupiter's satellites, citing de Sitter (MNRAS 71, 1911, p.388).

Finding 3. Lectures on Theoretical Physics vol. I, "Aether theories and aether models" (Leiden lectures, Eng. 1927)

Text fetched (ia-lectures-theor-phys-dli78238.txt, 322 kB). The preface says seven Leiden courses were published in Dutch up to 1922. Volume III is to hold "The Principle of Relativity for Uniform Translations (Special Theory...)" [web]. Volume I treats Fresnel and Stokes aberration, an ether at rest versus a dragged ether, and mechanical ether models. Only grepped, not read. Vol. III (Lorentz's Leiden relativity course of 1910-1912, Eng. 1931) is the next own-work item to find. It was not found in this search.

Not reached

• Problems of Modern Physics (1927) is lending-only on IA. Its relativity chapter is a known later own statement [memory, medium confidence]. Try HathiTrust.
• Collected Papers vols. 5-7 (relativity papers).