CHAPTER V.

Some qualities of the Aurora: pp. 33-51.

Noises attending Auroræ: pp. 33, 34.

Colours of Aurora: pp. 35-37.

Height of Aurora: pp. 37-40.

Phosphorescence attending Aurora: pp. 41-44.

Aurora and Ozone: pp. 44, 45.

Polarization of Aurora light: pp. 45, 46.

Number of Auroræ: p. 46.

Duration of Aurora: p. 47.

Travelling of Auroræ (Donati): pp. 47, 48.

Geographical distribution of Auroræ (Fritz and Loomis): pp. 48, 49.

Extent and principal zone of the Aurora: pp. 50, 51.