“As soon as I saw Balmer’s formula, the whole thing was immediately clear to me.” -Niels Bohr
“I’m fully convinced that the problem of spectral lines is intimately tied to the question of the nature of the quantum.” -Max Planck, 1908
FIRST PRINTING IN ORIGINAL WRAPPERS of Balmer’s two papers providing the formula for describing the spectral lines of hydrogen; of profound influence for Niels Bohr and the beginnings of quantum theory.
“Although trained as a mathematician and working as a mathematics teacher, Balmer became interested in spectroscopy, which was very much at the cutting edge of scientific research at the time, and was encouraged by colleagues at Basle University to try to find an explanation for the way lines in a spectrum are distributed--at first sight, in a random pattern. Although many other scientists had tried and failed to find some order in these patters, in 1884, in his sixtieth year, Balmer succeeded in finding an equation that not only reproduced the relationship between the four bright lines known in the spectrum of hydrogen at the time, but also predicted the existence of a fifth line, at the edge of visibility, that was soon detected. The formula was published in 1885, the year Niels Bohr was born.
“The five lines became known as the Balmer series... Although Balmer’s results were entirely empirical, based on the mathematical relationships alone with no attempt to find their underlying physical cause, this discovery that there was a mathematical order in the pattern of spectral lines was an important step towards developing an understanding of the spectrum in quantum terms” (Gribbin, Q is for Quantum).
“Shortly after 7 February  Bohr heard of the Balmer formula. By 6 March he had completed a paper containing its interpretation. That event marks the beginning of the quantum theory of atomic structure” (Pais, Niels Bohr’s Times).
IN: Verhandlungen der Naturforschenden Gesellschaft in Basel, vol. 7, pp. 548-560; 750-752. Basel: H. George’s Verlag, 1885. Octavo, original yellow printed wrappers, uncut and largely unopened; custom box. Stamp on front wrapper. Wrappers chipped around edges, front wrapper neatly re-attached and gatherings archivally stabilized at spine. SCARCE, particularly in original wrappers.
Price: $5,000 .