of the auroral light, it is not yet clearly known. There is also as much dispute as to whether any sound accompanies the aurora. The northern nations believe in the existence of this sound, like the rustling

of silk or of straws, a "crackling" coinciding with the darting of the rays. This also is not well proved. In arctic regions it is probably confounded with the incessant crackling of fields of snow and the faint clicking of small needles of ice in the process of their