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THE THEORY OF SPECTRA
AND
ATOMIC CONSTITUTION
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CAMBRIDGE UNIVERSITY PRESS
C. F. CLAY, Manager
LONDON: FETTER LANE, E.C. 4
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THE THEORY OF SPECTRA
AND
ATOMIC CONSTITUTION
THREE ESSAYS
BY
Professor of Theoretical Physics in the University of Copenhagen
CAMBRIDGE
AT THE UNIVERSITY PRESS
1922
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PRINTED IN GREAT BRITAIN
AT THE CAMBRIDGE UNIVERSITY PRESS
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PREFACE
THE three essays which here appear in English all deal with theapplication of the quantum theory to problems of atomic structure, andrefer to the different stages in the development of this theory.
The first essay "On the spectrum of hydrogen" is a translation of aDanish address given before the Physical Society of Copenhagen on the20th of December 1913, and printed in Fysisk Tidsskrift, XII. p.97, 1914. Although this address was delivered at a time when the formaldevelopment of the quantum theory was only at its beginning, the readerwill find the general trend of thought very similar to that expressedin the later addresses, which form the other two essays. As emphasizedat several points the theory does not attempt an "explanation" in theusual sense of this word, but only the establishment of a connectionbetween facts which in the present state of science are unexplained,that is to say the usual physical conceptions do not offer sufficientbasis for a detailed description.
The second essay "On the series spectra of the elements" is atranslation of a German address given before the Physical Societyof Berlin on the 27th of April 1920, and printed in Zeitschriftfür Physik, VI. p. 423, 1920. This address falls into two mainparts. The considerations in the first part are closely related tothe contents of the first essay; especially no use is made of thenew formal conceptions established through the later development ofthe quantum theory. The second part contains a survey of the resultsreached by this development. An attempt is made to elucidate theproblems by means of a general principle which postulates a formalcorrespondence between the fundamentally different conceptions of theclassical electrodynamics and those of the quantum theory. The firstgerm of this correspondence principle may be found in the first essayin the deduction of the expression for the constant of the hydrogenspectrum in terms of