Just occasionally, there is a moment in an archive when the gasps are audible. Such was the case on 16 January 2017, when Charlotte New, the Curator of Collections at the Royal Institution, brought out a couple of uncatalogued boxes of material labelled ‘Tyndall’, with no other provenance. They presumably contained papers relating to John Tyndall, but apparently by unknown hands. We were not looking for anything in particular, though there is always the hope that random letters can turn up anywhere.

*Marburg in the 1840s*

Charlotte opened the box, which contained five substantial bound journals. I took the first one and looked inside. It was obviously Tyndall’s handwriting. I may have emitted a polite expletive. To find a whole, uncatalogued journal, is quite something. But before examining it closely I opened the next one at a random page. Tyndall as well. And the third, fourth, and fifth.

It was immediately apparent that they were Tyndall’s extensive notes, surprisingly neat, from his time in Marburg University in 1848–9. They had simply been left mistakenly unattributed, decades ago, when Tyndall’s papers had been deposited in the archive.

Four of the five journals were mathematical, containing notes on Friedrich Stegman’s lectures. He would soon supervise Tyndall’s PhD. The fifth was of lectures from the physicist Hermann Knoblauch, who would shortly invite him to collaborate on the experiments on magnetism which established his initial scientific reputation and set him on a scientific career.

T*yndall's Marburg journals (Roland Jackson)*

But where were the notes on Robert Bunsen’s chemistry lectures? It was Bunsen who had invited Tyndall and his colleague Edward Frankland to Marburg, and Tyndall found his lectures inspirational.

Two days later we found them. Another uncatalogued box, this time just labelled ‘19th and 20th Century’. Inside this one were three journals. Halfway through one of them, which started with notes on the physicist Christian Gerling’s lectures, was the title ‘Lectures on Chemistry by Professor Bunsen’. A third box yielded two more notebooks, making ten in all.

So now we have a total of seven notebooks from Tyndall’s lectures in Marburg, with three more covering other experimental and lecture work. And we found several new letters.

By chance I was due to give a talk on Tyndall’s journals a few days later as part of the Royal Society’s ‘Scientific Diaries Workshop’, so the find had an early public airing. These journals will repay study by anyone interested in the curriculum of a German university at this time, and of course in Tyndall’s own education and development.

The journals are mostly in German, including substantial portions in Kurrentschrift, the old German form of handwriting. Though Tyndall took some time to develop confidence in spoken German, he quite quickly gained a facility in listening and writing it.

One aspect of particular interest is the extensive emphasis on mathematics, including many exercises in calculus. Tyndall, like his later mentor Michael Faraday, was never a mathematical physicist in the mould of William Thomson (later Lord Kelvin) or James Clerk Maxwell. That lack of a deep mathematical approach led to criticism of his abilities as a physicist by some of the ‘North British’ contingent like Maxwell himself and Peter Guthrie Tait. It is sometimes forgotten that Tyndall’s PhD was in mathematics, though not one requiring complex calculus. His interest was in a physical understanding of the natural world, explored through experiment. But he could perfectly well understand the mathematics if he wanted to.

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