Halle, November 28th | 1863.
My dear friend,
I take the liberty to send you 4 copies of my last inquiry,1 relative to the transmission of radiant heat through rock-salt etc. and the diffusion of rays, for you, my dear friend; our friend Hirst; Prof. Faraday and the London Royal Society.
It is a long time since I have nothing heard of you. I hope you are well and are satisfied with your experiments.2
My cousin3 who had the pleasure to make your acquaintance last year, has since last summer left London and is at present in New York.
As I have little hope to come over once more to your beautiful country, where I have spent so happy days, especially by your friendship. I think that you, who come over to the continent regularly every summer, will call upon Halle one day, take a view of our new established Institution for Natural Philosophy at our University4 and allow me to return your hospitality.
You will make the acquaintance of Miss Knoblauch5 and my little boys, John, Randolphe and Oscar and we will remember the good old Marburg-time.6
With my best compliments to Prof. Faraday, Dr. Hirst and who else may remember me in London.
Ever yours most truly | H Knoblauch
To Dr. John Tyndall | Royal Institution | London
RI MS JT/1/K/23
RI MS JT/1/TYP/7/2508
my last inquiry: K. H. Knoblauch (1820–95), ‘Ueber den Durchang der strahlenden Wärme durch polirtes, mattes und berusstes Steinsalz, und über die Diffusion der Wärmestrahlen’, Poggend. Annal., 120 (1863), pp. 177–286.
with your experiments: probably a reference to the work Tyndall was doing that would be published as J. Tyndall, ‘On the Passage of Radiant Heat through Dry and Humid Air’, Phil. Mag., 25 (1863), pp. 44–54.
My cousin: not identified.
our University: the University of Halle, where he had been since 1853.
Miss Knoblauch: Bertha Marie Emilie Knoblauch (née Winter, 1835–87) (Jan Mende,
Stadtmuseum Berlin, personal communication).
good old Marburg-time: Tyndall attended the University of Marburg from 1848–50, studying under Knoblauch, among others.
Please cite as “Tyndall2044,” in Ɛpsilon: The John Tyndall Collection accessed on