**The** **spectrum** **of** **helium** **has** **been** **very** **carefully** **studied** **by** **Runge** **and** **Paschen**.

**The** **careful** **measurements** **of** **Kayser** **and** **Runge** **of** **the** **carbon** **bands** **show** **that** **the** **successive** **differences** **in** **the** **frequencies** **do** (1900), **I**, **p**. 399.

**The** **question** **has** **been** **fully** **discussed** **by** **C**. **Runge** **in** **the** **second** **volume** **of** **Kayser'****s** **Handbuch** (**see** **also** **Magneto-Optics**), **and** **we** **may** **therefore** **content** **ourselves** **with** **the** **mention** **of** **the** **law** **discovered** **by** **Th**.

**Preston** **that** **all** **the** **lines** **of** **the** **same** **series** **show** **identical** **effects** **when** **measured** **on** **the** **frequency** **scale**, **arfrl** **the** **fact** **recently** **announced** **by** **Runge** 3 **that** **even** **in** **the** **more** **complicated** **cases** **mentioned** **some** **simple** **relation** **between** **the** **distances** **of** **the** **components** **exists**.

**Runge** **and** **F**.

**Runge** (**Pogg**.