is diffused the fainter it becomes; but it is still the effect of the flame, the continuation of its action, the dilated effect of its image. We might, therefore, very fairly call these circles reiterated images, because they constitute the successive boundaries of the action of the light, and yet at the same time only present an extended image of the flame.
383.
If the sky is white and luminous round the sun owing to the atmosphere being filled with light vapours; if mists or clouds pass before the moon, the reflection of the disk mirrors itself in them; the halos we then perceive are single or double, smaller or greater, sometimes very large, often colourless, sometimes coloured.
384.
I witnessed a very beautiful halo round the moon the