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2026-10-08 Epsilon (The John Tyndall Collection), epsilon.ac.uk

Investigator, STEP I, first run. Access: letter pages fetch by script; keyword search works only in Chrome (results rendered by JavaScript). Saved pages: research/pages/ep-*.html, epsilon-Tyndall1627.html.

Queries: "calorescence"; "Magnus aqueous"; "Strachey vapour" (no results); "Lecher Pernter" (no results); "Magnus vapour" with collection filter (no results; the filter value is wrong, search without it).

Findings

A. The 1859 announcement and the first reaction (priority 1 and 2)

Tyndall1627, J. D. Forbes to Tyndall, Pitlochry, 15 July 1859, on the 1859 Note: "I confess I am surprised at the magnitude of the effects you have obtained." Forbes asks for the tube length and "estimated percentage stopped", and suggests testing "condensed gases ... whether it follows the degree of condensation". RI MS JT/1/F/33. [web] https://epsilon.ac.uk/view/tyndall/letters/Tyndall1627 Bears on claim 1 (the effect's size) and claim 5 (Forbes's question about condensation is the question Tyndall later answers with the long-tube/short-tube and vapour/liquid experiments).

B. Tyndall versus Magnus on water vapour (claim 2)

Tyndall1815, Tyndall to Sir John Herschel (late 1861): air is "a practical vacuum" for radiant heat; the opacity once attributed to air is "mainly" aqueous vapour; "The negative results recently obtained by that eminent experimenter, Professor Magnus of Berlin, have induced me to reinvestigate this point ... prove this action to be comparatively enormous." Editor cites G. Magnus, 'On the Passage of Radiant Heat Through Moist Air', Phil. Mag. 23 (1862) 249-52. [web] https://epsilon.ac.uk/view/tyndall/letters/Tyndall1815
Tyndall1941, Tyndall to J. D. Hooker (1862): "Herschel and Airy have both said to me that it is a grand step in meteorology! Magnus denies the action; but he has not a foot to stand upon." Third memoir 'On the Relation of Radiant Heat to Aqueous Vapour', Phil. Trans. 153 (1863) 1-12. Herschel letter of 12 April 1862 = letter 1878 (vol. 7). [web] https://epsilon.ac.uk/view/tyndall/letters/Tyndall1941 (Tyndall's own report of others' approval: interested party.)
Tyndall2029, G. B. Airy to Tyndall, 27 Aug 1863: wants the rate at which vapour "disseminates itself through the air ... we should be in a way for beginning Meteorology"; "much interested in the account of your interview with Magnus". [web] https://epsilon.ac.uk/view/tyndall/letters/Tyndall2029
Tyndall1881, Tyndall to Stokes (1862): defends criticism of Melloni's and Magnus's lamp-black-coated rock salt; asks Stokes to soften anything about Magnus. Cambridge UL MS Add.7656/T553. [web] https://epsilon.ac.uk/view/tyndall/letters/Tyndall1881
Tyndall1847, Tyndall to Stokes, 29 Dec 1861: plans "a critical analysis of the last papers of Magnus" (Magnus, 'On the propagation of heat in gases', Phil. Mag. 22 (1861) 1-11, 85-106; German original Ann. Phys. April 1861). [web] https://epsilon.ac.uk/view/tyndall/letters/Tyndall1847
Tyndall2040, Louis Soret to Tyndall, Heidelberg 26 Oct 1863 (French): the Geneva Archives printed a translation of Magnus's memoirs but not Tyndall's reply (Phil. Mag. July 1863); Soret regrets this. Shows the controversy's reach on the Continent. [web] https://epsilon.ac.uk/view/tyndall/letters/Tyndall2040

C. Calorescence: the Akin priority dispute and Stokes's objection to the name (claim 4)

Tyndall2075, C. K. Akin to Tyndall [March 1864]: sends proofs of his British Association paper on "the converse phenomenon of Fluorescence" (Akin, 'Account of Preliminary Experiments on Calcescence', BA Report 1863; later 'On Calcescence', Phil. Mag. 29 (1865) 28-43). [web] https://epsilon.ac.uk/view/tyndall/letters/Tyndall2075
Letters 2076, 2162, 2165, 2167, 2170, 2173, 2177, 2197 (Sabine), 2208 (William Armstrong): the Tyndall-Akin dispute, Nov 1864 to early 1865, recorded by Tyndall in 'On the History of Calorescence', Phil. Mag. 29 (1865) 218-31. Tyndall2170 (7 Nov 1864, Tyndall): "no possible good can arise from a continuance of this correspondence." Tyndall2167 (3 Nov 1864) mentions an experiment held back "nearly nineteen months". Tyndall2208 (Armstrong): the British Association "could not ... confer upon Dr. Akin any exclusive privileges in the matter." Editors: "Between November 1864 and 1865, Tyndall did not write or publish on the subject." [web] https://epsilon.ac.uk/view/tyndall/letters/Tyndall2177
Tyndall2215, G. G. Stokes to Tyndall, 13 Jan 1865: "I am glad you have changed the term, which I don't think was quite correct. For if Calorescence = - Fluorescence we ought to have - Calorescence = Fluorescence". Stokes: a concentration of blue rays heating a solid to red heat "is not a little different from fluorescence, where blue rays of very moderate concentration cause a cold body ... to give out red light." The short paper: 'Note on the Invisible Radiation of the Electric Light', Proc. RS 14 (1865) 33-5, demonstrated at the RS. [web] https://epsilon.ac.uk/view/tyndall/letters/Tyndall2215 Bears directly on claim 4: Stokes, the authority on fluorescence, says heating-to-glow by focused rays is a different process from fluorescence (it is heating, not one-step wavelength conversion). This is what the claim turns on.
Tyndall2216, Tyndall to James Croll, 14 Jan 1865: "negative fluorescence" (I have changed this term to Calorescence); Croll had objected to "breaking up long periods into short ones"; Tyndall replies "you hit the mass with waves of slow recurrence, and ... obtain, in return from the mass, waves of quick recurrence." Wellcome MS. 7777/08. [web] https://epsilon.ac.uk/view/tyndall/letters/Tyndall2216 Shows Tyndall's own reading of the principle: a conversion through the body's heat (like a hammer heating iron), not a direct change of each ray.

Not reached here

Letters after 1866 (vols 10+ not yet online?); Herschel letter 1878; Stokes 7 May 1861 (RI MS JT/1/S/221) on Franz; letters 2182-2214; searches "Kirchhoff", "Balfour Stewart", "regelation", "Forbes glacier", "Akin" alone.