5th. May 1862
My dear Helmholtz,
I have received your note1 in company with a letter from Mr. Fessel2—When I visit the Exhibition,3 which I hope to do in a few days, I shall make it my business to discover the instrument of Mr Fessel, and to see that it is properly arranged.
And now I have a request to prefer to you. I know you have paid a good deal of attention to the history of the Mechanical theory of heat. A short time ago I finished a course of twelve lectures on Heat,4 and treated the subject throughout from the mechanical theory points of view. I intend to publish these lectures and should like to make myself perfectly acquainted with what Mayer has really done. Did he attempt to determine the mechanical equivalent of heat; or was Joule5 the first? If you could give me a list of the papers of Mayer and their dates I should be extremely obliged to you.
Present my kindest regards to Professor Bunsen, and also my respects to Kirchhof.
Yours very sincerely | John Tyndall.
RI MS JT/1/T/480
LT Transcript Only
Your note: letter 1890.
Mr. Fessel: Friedrich Fessel.
the Exhibition: International Exhibition or Great London Exposition, South Kensington, London sponsored by the Royal Society for the Encouragement of Arts, Manufacture and Trade. The Exhibition opened on 1 May and ran until 1 November 1862. See letters 1890 and 1893 for additional references.
twelve lectures on Heat: Tyndall delivered a course of twelve lectures on heat at the Royal Institution, starting 23 January and running to 10 April 1862. They appeared in 1863 as Tyndall, Heat.
Joule: James Prescott Joule (1818–89), British physicist (ODNB).
Please cite as “Tyndall1891,” in Ɛpsilon: The John Tyndall Collection accessed on