Greifswald 2024 – scientific programme

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GP: Fachverband Geschichte der Physik

GP 8: Closing Session

GP 8.3: Talk

Wednesday, February 28, 2024, 17:30–18:00, ELP 3: HS 2.33

Unclear crystals: 18th century projections of crystal formation — •Peter Heering — Europa-Universität Flensburg

"Which is beyond doubt one of the most pleasant observations that can be made with a solar microscope." With these words Wilhelm Friedrich Freiherr von Gleichen genannt von Rußwurm characterized the demonstration of crystallizations with a solar microscope. These projection microscopes were particularly popular in the second half of the 18th century. As I have already discussed, this popularity can be related to a significant degree to the instrument's ability of meeting the cultural standards of the Enlightenment. This understanding benefitted significantly from the practice with two original instruments at the Deutsches Museum. In the meantime, I had the opportunity of continuing to work with a reconstructed solar microscope - this enabled me to work on projecting the above mentioned crystallizations. In this talk I am going to present some of the experiences made in observing crystallisations, In doing so, I am facing a challenge that was already made explicit by the 18th century demonstrators: the projections with a solar microscope go 'beyond the expectation of those who have not seen it'.

Keywords: Enlightenment; crystals; replication method; solar microscope