Johann Jakob Balmer (1825–1898) was a Swiss mathematician and physicist best known for his work in the field of spectroscopy and for formulating the Balmer series, which describes the wavelengths of light emitted by hydrogen atoms. In 1885, Balmer derived a simple mathematical formula that accurately predicts the wavelengths of the visible spectral lines of hydrogen.
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A mathematician.[ref]
https://mathshistory.st-andrews.ac.uk/Biographies/Balmer/. Independent professional profile
Portrait of Johann Jakob Balmer
. F. Brandseph, photograph circa 1865; Basel University Library, UBH Portr BS Balmer JJ 1825, 2c/2b/2a; contributed with Wikimedia CH. Public domain in Switzerland under expired-term rule and in life-plus-70 jurisdictions; library declares document public domain. Source usage terms, via Wikimedia Commons. Source.