Brush-Charles · Source catalogue

The PDF is a scan of 10 pages with no text layer (pdftotext returned effectively nothing). I rendered all 10 pages at 150 dpi and ran OCR (tesseract), then read the output. It contains the opening of the founding paper of Brush's gravitation theory; the OCR text agrees closely with the Nature (23 March 1911) version reproduced in brush-rexresearch.pdf, which I read in full in its text layer. Brush argues that a falling body gains kinetic energy that cannot reasonably have been stored in the cold motionless body (illustration: a pound of iron lifted to the neutral point between earth and moon has 'lost' its potential energy yet cost work to lift), so the energy must reside in the aether. He postulates that the aether carries vast intrinsic kinetic energy in wave form, propagated isotropically in all directions, of such low frequency (in the 1910 version) that atoms cannot absorb it as heat. Each atom casts a spherical 'energy shadow' falling off as inverse square of distance; two bodies shield each other partly from the waves, so are pushed together by the excess wave pressure on their far sides (a wave-based variant of the Le Sage shadow theory). Gravitation is therefore a push, not a pull; a falling body's speed tends asymptotically to the wave velocity. He also considers longitudinal aether waves. He proposes to look for resonance heating (e.g. in the upper atmosphere) as an experimental test and says his early attempts were 'unsatisfactory'. Mentions the steel-cable illustration (earth-moon attraction equals a steel cable about 500 miles diameter).

Key claims

• The kinetic energy gained by a falling body is taken from intrinsic kinetic energy of the aether, not from 'potential energy of position' stored in the body.
• The aether carries vast kinetic energy in isotropic waves that pass through matter almost unobstructed.
• Every atom casts an inverse-square 'energy shadow' in these waves, and two bodies are pushed together by the unbalanced wave pressure on their outer sides, reproducing the inverse-square law with force proportional to mass.
• Gravitation is a push toward the attracting body and a falling body's speed approaches a limit equal to the wave velocity.
• Resonance of atoms or molecules with the aether waves could give a small, detectable heating effect.

Relevance: The founding statement of the theory that the whole Brush project rests on. All later experiments (pendulums, falling containers, calorimetry) were presented as tests or support of it.

Mainstream conflict: Conflicts with general relativity and the absence of a detectable aether (Michelson-Morley null result, 1887) [memory high]; shadow (Le Sage-type) theories are generally held to fail because the absorbed energy would heat bodies and a moving body would feel drag, and Brush's low-frequency, non-absorbed waves do not by themselves remove the energy-conservation problem [memory high]. Conservation of energy in Newtonian gravity is already accounted for by the potential energy of the gravitational field.

A 21-page browser print (dated 6/4/12; PDF metadata author is the repository owner) of the rexresearch.com page 'Charles F. Brush: Kinetic Theory of Gravitation'. It bundles four items, listed as separate entries here. The first is the Nature article of 23 March 1911, which is the published form of the 1910 AAAS paper. Contents as described in the entry for Kinetic-Theory-Gravitation.pdf: the energy-in-the-aether argument, isotropic aether-wave energy, spherical energy shadows, push-not-pull gravitation, optional transverse or longitudinal waves, instantaneous attraction claimed 'to be reserved for a future paper', and a proposed resonance-heating test, with the admission that a year of experiments on the upper atmosphere 'have thus far been unsatisfactory'.

Key claims

• Gravitation is a push produced by isotropic aether waves, with each atom casting an inverse-square energy shadow.
• A falling body's energy comes from the aether.
• Waves of very low frequency could pass through matter without heating it, so heating bodies is not a necessary consequence.
• Gravitational attraction acts effectively instantaneously.

Relevance: Primary-source text of the theory. Machine-readable, so it is the text this project can quote with confidence.

Mainstream conflict: See Kinetic-Theory-Gravitation.pdf: aether, Le Sage-type push gravity, and instantaneous action all conflict with relativity and with observation [memory high].

Lodge welcomes the subject but calls Brush's idea a modification of Le Sage's shadow theory in which waves replace corpuscles, notes that 'there is nothing new in a shadow theory' and that all such theories face the difficulty of explaining the absence of noticeable screening (shadowing). He says the potential-versus-kinetic distinction for stored energy is of little importance. He objects that a heat-radiation origin of the waves would make the gravitation constant secularly increasing and larger in hot enclosures, and asks which is cause and which effect. He closes by predicting that explanations based on external agents (particles or waves impinging on matter, 'grit in the aether') are doomed and that something internal and intrinsic to the atom is needed.

Key claims

• Brush's theory is a Le Sage shadow theory in wave form and shares the screening difficulty of all such theories.
• If the waves come from accumulated stellar radiation, G should increase with time and be larger in a hot enclosure.
• External-agent theories of gravitation are doomed to failure.

Relevance: The only contemporary expert comment preserved in the folder. It identifies the central theoretical difficulty in 1911 and shows the theory was not ignored at launch.

Mainstream conflict: none (Lodge is critical of Brush, from within the aether tradition).

Brush's final summary (he died in 1929). He restates the theory and adds (i) a frequency chart in octaves (1 Hz upward through Hertzian, infrared, light, ultraviolet, X-ray, gamma, cosmic rays) with the gravitation waves placed far above cosmic rays and a 'quanta waves' line near 6.54e27 Hz (the chart itself is an image in the printout), (ii) a claim that interstellar bodies would settle at 'the temperature of space' of 50-100 K (from his 1927 paper), and (iii) the experimental programme. The experimental evidence is two linked claims. First, some natural and artificial substances, notably complex silicates, nickel-cobalt silicate, Sandusky clay and barium aluminate, continuously generate a small amount of heat in his ice calorimeters, not attributable to radioactivity. Second, the same substances fall slightly slower than lead in his twin-container drop apparatus (containers of about 30.6 g dropped about 110-122 cm; the slower container is photographed in silhouette with a spark; the loaded materials form 30.8 % or 40.3 % of container mass). Quantitative example: barium aluminate container was slower by a mean 0.099 mm over 110 cm (1 part in 11,000), which Brush scales by the loaded mass fraction (40.3 %) to 1 part in 4450 for the barium aluminate itself. Controls described: containers swapped left/right, loads exchanged, lead sawdust as a comparison load; he acknowledges the scatter is partly due to lateral air currents and friction in the guide tubes for the first millimetre, and plans to eliminate air currents. He states that 'substances which have shown no generation of heat show no impairment' and that the Bureau of Standards had reported that Sandusky clay does generate measurable heat in its own ice calorimeter and was about to test the nickel-cobalt silicate. He concludes that the heat-gravity correlation is 'very strong evidence' and that he is 'justified in dismissing doubt'. A bibliography lists his Proc. APS papers 1914, 1921, 1923, 1924, 1926-1929, Nature 1911, J. Franklin Inst. 1928, Phys. Rev. 1917, Am. J. Sci. 1914, Proc. Royal Soc. 1917 (with Hadfield and Main), and US patents.

Key claims

• Substances that generate heat continuously in a calorimeter (complex silicates, nickel-cobalt silicate, barium aluminate, Sandusky clay) also fall measurably more slowly than lead.
• The slowness of fall correlates qualitatively with heat output: no heat, no impairment; larger heat, larger impairment.
• The effect is about 1 part in 4450 for barium aluminate relative to lead over a 110 cm drop.
• The heat comes from conversion of gravitation-wave energy by resonance, not from radioactivity.
• Space has a floor temperature of about 50-100 K because bodies absorb radiation from all stars.
• The US Bureau of Standards had confirmed continuing heat generation in Sandusky clay (reported privately to Brush).

Relevance: The only text-layer source for the experimental part of Brush's late programme and his best statement of the claim that mass and weight differ among materials.

Mainstream conflict: Equality of free-fall acceleration for all materials (the weak equivalence principle) has been tested to about 1 part in 1e9 by Eotvos and later workers, and to far better precision recently, so a 1 in 4450 (about 2e-4) difference is orders of magnitude larger than modern limits [memory high]. A body does not slow its fall by absorbing heat from isotropic waves in mainstream physics. The interstellar floor temperature is also at odds with the measured 2.7 K cosmic microwave background [memory high]. The Bureau of Standards claim is secondhand and unverified here.

A bibliography of Brush's gravitation-related publications as compiled on the site, plus an advertisement for the site's 'Civilization Kit'. The bibliography contains some transcription errors (for example a page range printed as 251-166) so exact citations should be checked at source.

Relevance: Index to Brush's other papers; useful for future acquisition of missing works (1921, 1923, 1924, 1926, 1927, 1928 Proc. APS papers).

Mainstream conflict: none

An 8-page scan with no text layer; all pages were rendered at 150 dpi and OCR'd, and I read the OCR text (a ~3,900-character passage was missed in Step 1 and is now covered by the deep read of pp.4-7). Copy from Case Western Reserve University Special Collections. Brush begins with the history of his storage-battery patent (No. 337,299, issued 2 March 1886, sustained in court, expired 1903), his retirement from the electrical field in the early 1890s to do pure-science research, and his businesses (portland cement, Linde Air Products). He then restates the 'ether-wave, or energy-shadow' theory and presents the experimental evidence: continuous heat generation by some rocks and minerals (complex silicates; nickel-cobalt silicate strongest) in two calorimeters, the earlier discovery of spontaneous heat generation in recently hardened steel, and the correlation with slower fall. The drop apparatus: two aluminium containers dropped about 122 cm side by side, each breaking an electrical contact in series so only the earlier break produces a spark; a spark appears when one container leads by as little as 0.0125 mm, which he converts to a time difference of about 1/400,000 s (this checks: fall time from 1.22 m is about 0.5 s and 0.0125 mm is 1.0e-5 of the distance, so the time difference is about 2.5e-6 s). The photographic method with spark illumination and horizontal-line background is also described. States that the Bureau of Standards is checking his calorimetry. DEEP READ (pp.4-7): the paper gives NO calorimeter design, sensitivity, run length or heat data; every heat claim is qualitative ('easily observable amount', 'very large activity'). Only one silicate is named, an artificial silicate of the protoxides of nickel and cobalt, 'nearly two years aging' and 'appears to be permanent'. 'Not due to radioactivity' is asserted with no method given, and the aether-wave explanation is offered 'in the absence of other explanation'. Brush claims every heat-generating material tested impaired falling velocity relative to lead and non-heating materials did not, but gives no table, no materials list and no numbers; the quantitative relation is 'to be ascertained'. Bureau of Standards wording: 'is working with some of these minerals for the purpose of checking my findings', so work in progress, NOT a reported confirmation (do not cite as confirmation). Only numbers: ~122 cm drop, 0.0125 mm lead, ~1/400,000 s (arithmetic checks: 1.22 m fall is ~0.5 s, v about 4.9 m/s, 1.25e-5 m / 4.89 m/s = 2.6e-6 s). He proposes gravity waves have 'a wide range of frequencies as do the well-known X-rays' with fortuitous resonance in some matter, a gradual step toward the 1929 position (frequencies above cosmic rays).

Key claims

• Some complex silicates generate heat persistently, not from radioactivity.
• Materials that generate heat fall more slowly than lead when dropped in twin containers.
• 'Spontaneous generation of heat in recently hardened steel' was a discovery arising from this research and is now recognised in metallurgy.
• The same class of isotropic aether waves that cause gravitation also cause the heat generation.
• Every heat-generating material tested impaired falling velocity relative to lead, and materials showing no heat show no impairment (asserted; no data given in the paper).
• The Bureau of Standards is checking the calorimetry with a calorimeter of its own design (statement of work in progress; no result reported in this paper).

Relevance: Companion to the 1929 paper; gives the earlier, cleaner statement of the falling-container method and Brush's own biography of his work and finances.

Mainstream conflict: Same as the 1929 paper: weak equivalence principle tests rule out material-dependent free fall at this size [memory high]; steel-hardening heat is not disputed in principle (stored energy released on ageing/tempering) but is not evidence for aether waves [memory medium].

A one-page typed letter (catalogue title attached to the PDF describes it as acknowledgements for Brush's address 'Some Experimental Evidence Supporting the Kinetic Theory of Gravitation'). Todd, an anatomist at Western Reserve, thanks Brush for the reprint, says he knew in general what Brush was doing but had been unable to formulate the experiments exactly until now, and calls it 'a very fortunate opening of a new line of thought'. He also mentions his association with the Brush Foundation. The file name suggests this is item spcbru00769 of the Case Western Reserve Special Collections Brush papers.

Relevance: Shows supportive but non-physicist reception; no technical content.

Mainstream conflict: none

A 7-page scan. Letter 1 (Brush to Miller, Feb 1926): Brush says the Eotvos experiment, 'on which the Relativists pin their faith', is fallacious; the true effect is 'a hundred times too small' in Eotvos's results; he suggests Miller, then at Mount Wilson for ether-drift work, mount an Eotvos torsion balance on one arm of his interferometer and compare lead with sulphur or selenium, where Brush says he found nearly the maximum mass-weight difference. Letter 2 (Miller to Brush, 2 March 1926): 11 days on the mountain, 34,000 readings; Miller knows the Eotvos apparatus only from manufacturers' circulars, says mounting one on the interferometer 'would be easy' and that mercury-flotation conditions could be arranged in his Cleveland laboratory, has 'already begun to look up the literature', and asks Brush for further information. This is the whole of Miller's response on the proposal: non-committal and interested, neither a refusal nor a commitment. Letter 3 (Brush to Miller, 21 March 1928, typed carbon copy, misdated 1926 in the earlier summary): thanks for bullet-in-flight photographs; Brush's containers fall about 16 ft/s so tip haziness is no worry; mentions Compton visiting his home. Pages 4-5 (Miller to Brush, 5 March 1928, handwritten): thanks for the APS Memorial Volume with Brush's last paper, sends bullet photographs (spark about 1/1,000,000 s, best reading) and refers to an evening at Brush's home laboratory. Page 7 (Miller to Brush, 17 March 1929, handwritten): birthday congratulations, and hopes Brush's health lasts because 'your help is needed in behalf of the "ether", now more than ever'. DEEP READ result: pp.4-7 contain no mention of the Eotvos test, lead, sulphur or selenium and no report that any torsion-balance test was ever run or refused; whether Miller ran it elsewhere is unknown from this PDF.

Key claims

• The Eotvos torsion-balance experiment's null result for material-independence of gravity is flawed or too insensitive, and a better apparatus would show lead and sulphur or selenium differing.
• Brush found the maximum mass-weight difference between lead and sulphur or selenium.

Relevance: A documented proposed-but-never-reported test of the Eotvos claim. It also shows that Miller (ether-drift experimenter) and Brush viewed each other as allies on the ether in 1928-29.

Mainstream conflict: Eotvos-type torsion balances have repeatedly confirmed equal gravitational and inertial mass to high precision [memory high]. Brush's assertion that Eotvos's experiment is fallacious is not supported by any document in the folder.

A 29-page scan from the Case Western Reserve Special Collections, no text layer. I rendered every page at 130 dpi and ran OCR; pages 1-13 (the printed reprint, read April 24, 1914) and the typed abstract on pp.14-16 are readable. Pages 17-29 are a 13-leaf handwritten draft ABSTRACT of the same paper (read by deep read from page images), not new material: it states the modified force law as 1/D^(2+x) (x positive for a body absorbing energy from the aether, negative when giving energy to it), hopes the 'alternately plus and minus deviation' explains Mercury's perihelion advance (x 'increases in importance with eccentricity') and lunar perturbations, and repeats the Laplace argument and the 'very few seconds of arc in a century' lunar retardation. It gives NO formula or numerical value for x, no orbit calculation and no data. Note the sign convention: the form is 1/D^(2+x), not 1/D^(2-x) as QE phrased it, and the printed pp.1-13 text should be checked for the same form. The draft abstract cites Science 10 March 1911 and Nature 23 March 1911 for the original outline. Content: (1) Gravitation is due to the intrinsic energy of the aether: he re-argues using Kelvin's example of two cold bodies falling together to make a sun's worth of heat, with the claim that potential energy of position must reside in the aether, the golf-ball-with-rubber-thread analogy. (2) A corollary: bodies that are accelerating along the line of attraction absorb aether energy and so cannot obey the exact inverse-square law; the force varies as 1/r^2 times (1 + x), with x a very small quantity that grows with velocity of fall (zero for circular orbits, alternately positive and negative for eccentric ones). He hopes this could explain part of Mercury's anomalous perihelion advance (accepted at that time as an unexplained anomaly, resolved later by general relativity [memory high]) and lunar perturbations. (3) He disputes Laplace's argument that gravitation must propagate with essentially infinite speed (otherwise the moon's orbit would spiral); using a diagram of forces he argues that with a finite propagation speed equal to that of light the moon's mean motion would be retarded by only a few seconds of arc per century, a displacement of the earth's centre of about 52 feet, and a tangential force about 1/24,000,000 of gravity at the moon's distance, and that this is partly cancelled by his deviation from the inverse-square law. He also says this is considered further in another discussion on motion through the ether.

Key claims

• Bodies accelerating along the line of attraction feel a force differing slightly from inverse-square, with a correction that depends on the rate of energy transfer to or from the aether.
• This correction could account for the anomalous advance of Mercury's perihelion and for lunar perturbations.
• A finite speed of gravity equal to that of light would retard the moon's mean motion by only a few seconds of arc per century, not excluded by observation.
• Laplace's infinite-speed conclusion rests on premises that do not apply to the energy-shadow theory.
• Force varies as 1/D^(2+x), with x very small and depending on the rate of energy transformation or velocity of fall (draft abstract; no formula for x).

Relevance: The theoretical elaboration of the project and the only place in the folder where Brush makes numerical astronomical predictions, which can be checked by calculation.

Mainstream conflict: Mainstream view is that Laplace's bound applies to any gravity that behaves like a static central force with finite speed; general relativity solved this by a consistent field theory in which aberration effects cancel to first order [memory high]. Mercury's perihelion advance of about 43 arcsec per century is explained by general relativity [memory high]; Brush offers no calculation of the size of x. A correction that depends on velocity and changes sign makes the force non-conservative; the pages give no calculation showing a net secular perihelion advance [read: deep read].

A Google Books scan of the whole volume (text layer contains only Google's front matter). The volume contents page shows Brush's paper at p.167; it appears near the PDF page 184. The whole Brush paper (PDF pp.184-204) was read in full; the rest of the volume is other authors' unrelated work, except the Minutes (below). The paper is the second experimental paper on a mass-weight difference, the 'zinc-bismuth effect'. Apparatus: two matched 2.284 m steel-rod pendulums on a common rigid plate with knife edges, bobs of zinc, bismuth and pure iron of about 1.377 kg each, driven by clocks; the bobs are exchanged between pendulums, and the time for one pendulum to gain a beat (oscillation) on the other is observed with a telescope. Result: after the bobs are swapped the bismuth pendulum gains one beat in a few hours (7.3 h in Table I; 5 h 11 min after zinc and bismuth masses were equalised), which Brush states corresponds to a zinc-bismuth effect of about 1 part in 32,000 in the pendulum period after subtracting 22 % for centre-of-gyration effects of the zinc bob's greater diameter. He claims iron lies between zinc and bismuth, that coarse-grained recrystallised bismuth differs from fine-grained bismuth by about 2.5 % of the zinc-bismuth effect, and that electrolytic zinc differs from commercial zinc. Controls reported: equal bob masses (unequal masses were his largest source of error, which he warns can reverse the sign), air vanes to equalise drag, large vanes to double the drag (effect changed by roughly 50 %, which is large), a soft-iron cylinder placed near a bob (11 % acceleration), rigid support tests (no phase change in 3 h), and a glass plate between the pendulums (about 1.7 % change). The shortened-pendulum runs show reversed time orderings which he attributes to errors in exchanging bobs and says he has not had time to repeat. He interprets the result as an unequal weight per unit mass in different materials and previews the falling-container experiment. DEEP READ (Opus) results: (1) Bobs were matched by WEIGHT on a 2 kg Becker balance sensitive to 0.1 mg (weights 1,383.705 to 1,383.893 g, spread 1.4e-4); the paper never says 'in air' or 'in vacuo' and applies no buoyancy correction, but describes only an ordinary balance, so weighing in air is the only consistent reading; this supports the premise of the arbiter's buoyancy plus added-mass calculation. The bobs differ in size: zinc 72 mm and bismuth 61 mm diameter, both 48 mm high. (2) The original 1921 pair was 7 g (about 1/2 per cent; OCR misread as '14 per cent') unequal in weight, corrected by a soldered zinc band. (3) Brush states vacuum would shorten both periods equally and 'To this I can confidently answer no' to an air effect, never ran a vacuum test, yet also writes that the air vanes on the bismuth 'slightly lengthen its period', i.e. air inertia at the 2-4e-5 level is present in his own apparatus; all reported runs carry compensating vanes on the bismuth. (4) The corrected effect is not independent of pendulum length: 31-32e-6 for long pendulums but 19.4 and 25.9e-6 for short ones; the short-pendulum runs show reversed orderings that Brush calls 'strong suspicion of experimental errors' and did not repeat, while the same paper says 'in no instance has there been any negative or equivocal result'. (5) The 1921 value was revised: Table I's 7.3 h per beat (about 17,432 swings at 2,388 oscillations per hour; 'one part in 35,000' uncorrected), Table II 1/51,000 after correction, 1/32,000 for equal weights; the centre-of-gyration correction rose from about 10% to 22% because a doubling 'was inadvertently overlooked'. (6) The three-metal closure (1/17 + 1/13 = 1/7.36 h) is a timing consistency check, not an independent gravitational check, and the iron bob was never re-weighed. (7) Same-metal controls are not null: new bismuth gained on old bismuth (about 2.5 per cent of the zinc-bismuth effect by Brush, about 1.7 per cent by a small-angle reading), attributed to crystal grain size; new electrolytic zinc beat old commercial zinc. (8) A soft-iron cylinder 10 cm from a bob accelerated the nearer bob at 11 per cent of the exchange effect, unexplained. (9) Glass-plate test: bismuth sped up 6 minutes, 1.7 per cent, attributed to room air currents. (10) The date is April 1922 (signed), printed 16 November 1922 (an earlier summary said 'read Nov 1922'). (11) The drop apparatus (journal pp.182-183): two aluminium containers, about 120 cm fall, loaded to exactly equal weight; 'the one containing bismuth strikes its target just a little before the zinc one', time difference 'of the order of a hundred thousandth part of a second'; 'a persistent collateral phenomenon developed, which promises to be of great interest', not described and reserved for a future paper (probably the start of the heat-generation work; that link is inference). The paper gives bismuth falling faster than zinc, while the 1928-29 papers have heat-generating silicates falling slower than lead; the two sets of results are not reconciled in any document. MINUTES (deep read, PDF pp.328-335): the Marquis Antonio de Gregorio, Palermo, corresponding member, wrote a covering note dated 20 July 1922 asking the Society to print a paragraph 'On Gravitation's Kinetic Theory'; it was read at the Stated Meeting of 3 November 1922 [read: p.330-332]. He claims he proposed the same theory in 1892 to the Palermo Academy (printed 1893 in 'Nuovi Strumenti fisici...'; re-discussed 1914): ether is a pressure ('tension') medium passing through matter, matter absorbs part of its energy, so the pressure between two bodies is lower than outside and they are pushed together. He also complains that Olinto De Pretto (1921) reproduced part of his theory without citation, and closes that Brush's work is 'valuable and commendable' but that his own contains the priority [read: p.331-332]. Brush's reply, signed 'Cleveland, November, 1922', was read at the Stated Meeting of 1 December 1922, so the exchange spans two meetings [read: p.333-334]. Brush worked not from the letter but from a translation by Prof. Borgerhoff (Western Reserve) of Gregorio's 1895 Atti papers (last chapter, pp.177-181), which also give a rotary-molecular-vibration alternative; the 1914 paper recasts the ether as a dynamic fluid of 'superatoms'. Brush states his own theory (Dec 1910) rests on (1) vast intrinsic ether energy and (2) ether energy in isotropic wave form with inverse-square intensity, which he calls 'original with me' and finds nowhere in Gregorio. He does not dispute that Gregorio wrote first, only that it is the same theory, and makes two substantive objections: Gregorio does not explain how the pressure deficit persists once absorption has stopped, and offers no source for the energy gained by falling bodies [read: p.334]. The words Le Sage, shadow, screening and corpuscle never appear in these pages; calling Brush's theory Le Sage-type is an outside interpretation [memory high]. The originals (1893, 1895) are not in the folder, so neither priority claim is checked. No verdict impact.

Key claims

• Equal masses of zinc, iron and bismuth do not have equal weight: gravity acts more strongly per unit mass on bismuth than on zinc.
• In swapped-bob pendulum tests bismuth's pendulum gains one beat in about 5-7 hours, a zinc-bismuth effect of about 1 part in 32,000 after corrections.
• The effect depends on crystalline structure and purity of the metal.
• Neither unequal air drag, magnetic distortion nor support coupling accounts for the effect.
• Brush's own pendulum data show air inertia from small vanes of the same size as the claimed effect (vane shifts of about 2-4e-5 in period; deep read), so the effect is not shown to be independent of the air.
• Bismuth falls slightly faster than zinc in twin aluminium containers, by about 1e-5 s over a 120 cm drop (stated, no data given).
• Marquis de Gregorio (letter of 20 July 1922, read 3 Nov 1922) claims to have proposed in 1892 an ether-pressure theory of gravitation in which matter absorbs ether energy; Brush (reply read 1 Dec 1922) answers that his isotropic inverse-square wave-flux postulate is original and that Gregorio explains neither persistence of the pressure deficit nor the energy of falling bodies.

Relevance: The core pendulum experiment of the project, with full procedure and numbers, and the earliest quantitative result Brush offered against the weak equivalence principle. It is also the source of the 1921 NYT report (see einstein-wrong-109803810.pdf). Also carries the Gregorio priority exchange (a push-theory priority dispute; the Le Sage label is an outside interpretation, not in the text) and the first mention of the drop apparatus and its 'collateral phenomenon'.

Mainstream conflict: A pendulum period depends on the moment of inertia and centre of mass of the whole bob-and-rod system, on drag and on support compliance; apparent period differences between exchanged bobs of different shape are the usual signature of systematic effects rather than of different g [memory medium]. Equality of gravitational and inertial mass is confirmed to at least about 1e-9 by Eotvos-type and later experiments, whereas the pendulum effect corresponds to a relative difference near 6e-5 (twice 1/32,000) in g [memory high for Eotvos limit; the 6e-5 conversion is my arithmetic from T proportional to g to the power -1/2].

A scan of the whole volume; the text layer has only front matter. The complete Brush paper (PDF pp.241-249) was read by OCR; the rest of the volume is other authors' unrelated work. The paper continues a 1915 paper in Proc. APS (vol. 54, No. 217). Apparatus: two silvered Dewar vessels placed in a 52 lb copper cylinder in cork inside a thermostatted box; one copper can holds twelve half-inch, five-inch bars of steel just after quenching (oiled to prevent oxidation heat), the other can holds water of equal thermal capacity; iron-constantan and copper-constantan thermocouples feed a reflecting galvanometer calibrated at 55 scale divisions per degree C. Results: hardened carbon tool steel and tungsten-chromium steel generate heat for days to weeks after quenching, at a falling rate (maximum temperature excess in the figures on the order of 100+ galvanometer divisions, i.e. about 2 K, from the plotted curves). Hadfield nickel-chromium steels (sent by Sir Robert Hadfield) show similar behaviour, strongly dependent on quench temperature and composition; a third quench just below recalescence still gave about 3/4 of the heat. A control in which the bars were heated, slowly cooled in the furnace (not quenched) and treated identically produced no heat, which Brush takes as showing the heat is due to hardening and not oil or oxide reactions. He also measured the lengths of test bars (to 1/20000 inch) and found spontaneous shrinkage after second hardening but none after first hardening, so shrinkage is not the cause. He attributes the heat to relaxation of molecular strain in the quenched steel. DEEP READ of PDF pp.94-97: the APS Cleveland meeting (27-28 Oct 1916, Nela Park, 22 papers, 45 registered) lists Brush's title only; no abstract of his paper is printed in this volume, so nothing is added to the full paper. The paper is dated Cleveland, October 1916, the month of the meeting, so it was probably the text of the talk (inference). It quotes Part I (April 1915, Proc. APS 54): hardened carbon tool steel and a tungsten-chromium steel generated heat 'for at least several weeks', the rate steadily diminishing.

Key claims

• Quenched steel spontaneously releases heat for days to weeks after hardening, at a decreasing rate.
• The heat is not due to shrinkage, to oil or oxide reactions, or to recalescence.
• A control specimen cooled slowly (not hardened) generates no heat in the same apparatus.
• Quench temperature and alloy composition strongly affect the amount of heat released.

Relevance: The earlier calorimetry that led Brush to his later interest in heat-generating substances; it shows his method, his controls and his calibration. Note that the hardened-steel work is mainstream-compatible, unlike the later extension to rocks and gravitation.

Mainstream conflict: Little conflict at this stage: release of stored strain and phase-transformation energy from quenched steel (retained austenite transformation, martensite tempering) is plausible as an exothermic aging process [memory medium, unchecked]. The conflict arises only when Brush links such heat to gravitational aether waves, which this paper does not do.

A 2-page scan, no text layer, OCR'd from 150 dpi renderings. The article, from Philadelphia on 22 April 1921, reports Brush's paper at the American Philosophical Society meeting on gravitation experiments with pendulums made of bismuth and zinc (of the same 'units of mass'), saying Earth's gravitational field 'grips bismuth stronger per unit of mass than it grips zinc'. A. G. Webster (Clark University) is quoted as saying that if the experiments are accurate they 'absolutely disprove the Einstein theory' and calls it a 'startling fact', saying that for 200 years it was believed that inertia is proportional to mass. Another unnamed scientist said no one would be better pleased than Einstein if his theory were disproved. Brush says the results would upset calculations of the earth's density. Headline claim (the New York Times headline 'Einstein wrong, Brush indicates') exceeds what the quoted material justifies. The continuation also reports other APS papers (e.g. Monroe B. Snyder on 'universal volcanism').

Key claims

• Brush's pendulum experiments show gravity acts unequally per unit mass on bismuth and zinc.
• If accurate, this disproves Einstein's theory (per Webster, as quoted).
• The result would require revising the earth's computed density.

Relevance: Documents the public reception and how the claim was framed in the press in 1921; the Webster quote shows at least one physicist found it worth serious attention.

Mainstream conflict: The newspaper's reading that a composition-dependent g would 'disprove Einstein' is accurate in the sense that general relativity builds on the equivalence of inertial and gravitational mass [memory high]. The article is a secondary source and does not establish the experiment was correct.

A 2-page scan of a typed biography (partly obscured by marginal marks), OCR'd; the opening lines are garbled but it reports Brush's death at his Cleveland home in 1929 from complications following bronchitis, and calls him a charter member of the AIEE and Edison Medalist (1913). Facts given: born at Euclid, Ohio, 17 March 1849; graduated in mining engineering from the University of Michigan in 1869; M.S. and Ph.D. (Western Reserve), honorary LL.D.; designed a dynamo by 1876 shown at the Paris Exposition; compound field winding 1877; Boston 1878 arc lighting; differential arc lamp, automatic cut-out; copper-plated carbon electrodes; Brush Electric Company incorporated 1881 ($3,000,000), absorbed into General Electric about ten years later; storage-battery improvements; Chevalier of the Legion of Honor 1881; Rumford medal (1889); numerous society memberships.

Relevance: Establishes Brush's standing as a major electrical inventor and businessman, which explains why his gravitation experiments received a hearing from the APS and the Franklin Institute.

Mainstream conflict: none

A 2-page scan, OCR'd. A short biography written six weeks before his AAAS paper: born in Cuyahoga County, 17 March 1849; Michigan mining-engineering degree 1869; arc-light development and the 1881 Brush Electric Company; Legion of Honor 1881; Rumford medal 1889; president of the Linde Air Products Company, director and trustee of several institutions, three children. The second page carries unrelated magazine items and an excerpt of an AIEE biographical text duplicating the biography entry. No mention of gravitation (it predates the 1910 paper).

Relevance: Background on Brush's career and wealth, which financed his private laboratory.

Mainstream conflict: none

A one-page scan, OCR'd from a 150 dpi rendering and read in full. A Cleveland Press feature on Brush at age 78 (born 17 March 1849) who splits his days between his office in The Arcade and a laboratory in his home at 3725 Euclid Avenue. It says that over about ten years of experiments he believes he has evidence that bodies of different materials do not fall at exactly the same rate, and that he thinks his results, once complete, will upset Einstein's theory ('I am not working to disprove Einstein... I am only seeking for facts'). It also says he finds that certain rocks spontaneously generate small amounts of heat, which he attributes to absorption of energy from the aether, and that he has financed a repetition of the rock-heat experiment at the US Bureau of Standards in Washington so that other scientists' findings can be obtained. Gives career facts (Brush Electric Co. founded in Cleveland, 1880, one of four companies forming the nucleus of General Electric; Rumford and Edison medals; Legion of Honor).

Key claims

• Bodies of different composition do not fall at exactly the same rate.
• Certain rocks spontaneously generate small amounts of heat from aether energy.
• Brush financed a repetition of the rock-heat experiment at the US Bureau of Standards.

Relevance: Press-level statement of the two experimental claims, and evidence that the Bureau of Standards check was financed by Brush himself, which matters for judging how independent that replication was.

Mainstream conflict: Same as the 1928 and 1929 papers: free fall is universal to high precision [memory high]; rock heat from aether waves is not accepted (rock heat is attributed to radioactive decay) [memory high].