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rexresearch: Charles F. Brush, "Kinetic Theory of Gravitation" (related work, priority 3)

Visit: 2026-10-07, Investigator run (STEP I). URL https://www.rexresearch.com/brush/brush.htm (an HTML compilation; read in Chrome). How reached: Google 1902 1903 "Whittaker" gravitation longitudinal waves aether history Stoney Lorentz "kinetic theory of gravitation" surfaced T. J. J. See's book quoting "the Kinetic Theory of Gravitation [of] Dr. Brush". Then Charles F. Brush "kinetic theory of gravitation" 1911 aether waves. Note: rexresearch1 (the History Vol. 2 PDF host listed in sites.md) was not rechecked this run. Vol. 2 is also on archive.org (2026-10-07-archive-org.md).

What the page holds [web]

  1. C. F. Brush, "A Kinetic Theory of Gravitation", Nature 86, 130-132 (23 March 1911); read at the AAAS Minneapolis meeting, December 1910. - The aether holds "very great kinetic energy" as waves "propagated in straight lines in every conceivable direction" (isotropic). Bodies cast "spherical shadows" and are pushed together: a wave form of Le Sage's theory. "Gravitation is a push toward the attracting body, and not a pull." - He considers longitudinal waves explicitly: "Let us now consider longitudinal waves -- waves of compression and rarefaction ... So far as I am aware, longitudinal waves in the aether are unknown, but that such waves have not been observed is not convincing argument that they do not exist." The proposed grip on atoms is "the locally alternating flow and ebb -- acceleration and retardation of the aether". - He holds that gravity must act, in effect, instantaneously.
  2. Oliver Lodge, letter to Nature, 30 March 1911. Lodge calls it "a modification of Le Sage's theory" and says that "all such theories are faced with the difficulty of plausibly explaining the absence of noticeable screening". He gives objections: G would increase over time, and would be greater in a hot enclosure. His own view is that "An atom of matter, by its very existence, sets up a fixed stress in the aether".
  3. Brush, "Gravitation", Proc. Amer. Philos. Soc. 68, 55-68 (May 1929). Gravitation waves lie above cosmic-ray frequencies. Experimental claims, quoted from his 1926-1928 Proc. APS papers: - Calorimeter results: some complex silicates (nickel-cobalt silicate, barium aluminates) generate heat continually, "none of these substances is more than minutely radioactive". - Free-fall comparison: two aluminium containers of equal weight are dropped together about 122 cm and the order of arrival is detected by a spark circuit; later he photographed the container tips. "The container holding the silicate was always slow"; containers were swapped after each drop. He claims a correlation between heat generation and "impairment of their gravitational acceleration", over more than 50 plates. - "The Bureau of Standards, with a calorimeter of its own design, is working with some of the heat-generating substances for the purpose of checking my findings." No result of that check is on the page. - Lateral air currents disturbed the results, by his own account.

How it bears on the claims

  • Claim 4 / Q07: Brush is a contemporary (1910-1929) who, like Whittaker, put gravity into aether waves and openly allowed longitudinal ones. His model is a push (shadow) model, not Whittaker's superposition, so the two are related in principle but different in mechanism.
  • Brush's composition-dependence claim is a direct test of the kind A07 weighed with MICROSCOPE (all materials fall alike to about 1e-15). His claimed effect was at the level of about 0.0125 mm in 122 cm (about 1e-5) for some silicates. That is far larger than any later limit, so later Eötvös-type and MICROSCOPE results bear on it. The record of what the Bureau of Standards found has not been located. It is an absence to check (NBS archives, Proc. APS 1929-1932, Physical Review), not a refutation by silence.
  • Lodge's "fixed stress in the aether" is the static alternative to both Brush's and Whittaker's wave pictures.
  • Brush's papers are a Case Western Reserve University collection (OhioLINK finding aid, "The Charles F. Brush, Sr., Papers", seen in Google results only).