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155 pp. With 4 plates at rear. (4to) 30x23 cm (12x9") modern half maroon morocco and marbled boards, gilt spine. First Edition.

First edition of the memoir in which Rydberg developed the empirical formula relating the frequencies of spectral lines, and introduced the universal constant that now bears his name, thereby helped to develop the theory of the quantum atom. It was later derived by Niels Bohr using his quantum theory of the atom. "His major spectral work, 'Recherches sur la constitution des spectres d’émission des éléments chimiques', published in 1890, mapped out Rydberg’s total approach with remarkable clarity. He conceived of the spectrum of an element as composed of the superposition of three different types of series - one in which the lines were comparatively sharp, one in which the lines were more diffuse, and a third that he called principal series even though they consisted mostly of lines in the ultraviolet. The first lines were located in the visible spectrum and were usually the most intense. The members of each series might be single, double, triple, or of higher multiplicity. Any particular elementary spectrum might contain any number (even zero) of series of each of the basic types."(DSB)