Wave-lengths of hydrogen lines and determination of the series constant

Abstract

The Balmer or series spectrum of hydrogen possesses a special interest and importance for several reasons. In the first place hydrogen occupies a unique position among the elements, on account of its chemical properties and atomic weight. Secondly, the spectrum itself is notable as having been the first series to be recognised and represented by a formula, by Balmer in 1885. Many other series have since been found, but in no other case is the formula so simple in character or capable of representing the series with such great accuracy. Since Balmer published his "law" improved wave-lengths have been obtained by Ames, and the series has been greatly extended (in the chromospheric spectrum) by Dyson, Evershed, and Mitchell, but the formula remains completely satisfactory; that it to say, the observed and computed wave-lengths never differ by a greater amount than may reasonably be attributed to experimental error. From the above considerations it is clear that this spectrum cannot fail to offer a particularly attractive field for the work of the theoretical investigator who seeks to throw light on the mechanism of radiation. The problem in the case of the hydrogen series is evidently reduced to its capable of extension to the series of other elements, for these series can all be represented by generalisations of Balmer's formula.