Note 13 — Chapter X · SPECTROSCOPE ADAPTED FOR THE AURORA.

There seems to be some confusion as to the W.L. here given; 5567 is usually accepted as Ångström’s line, while Prof. Smyth refers to it as 5579. The position, too, when examined with a spectroscope of greater dispersion, is not exactly over the citron-line of acetylene, both the above referred to lines lying somewhat more towards the violet end of the spectrum (see Plate V. fig. 7).