52 METEOROLOGICAL 
phorescent properties :—“ It is not improbable,” 
says Humboldt, “that the Moon, Jupiter, and 
comets shine with an independent light besides 
the reflected, solar light, visible through the po- 
lariscope.”’ 
We cannot do better than quote the following 
passage also, by the same author :— 
“Without speaking of the problematical, but 
yet ordinary mode in which the sky is illuminated 
when a low cloud may be seen to shine with an 
uninterrupted flickering lieht for many minutes 
together [see further on], we still meet with other 
instances of terrestrial development of hght in our 
atmosphere. In this category we may reckon the 
celebrated luminous mists seen in 1783 and 1831; 
the steady luminous appearance exhibited without 
any flickering in great clouds observed by Rozier 
and Beccaria; and, lastly, as Arago well remarks, 
the faint diffused light which guides the steps of the 
traveller im cloudy, starless and moonless nights, 
in autumn and winter, even when there is no snow 
on the ground.” 
Indeed, any attentive observer of Nature may 
assure himself that in the darkest mghts of winter, 
at the hour of midnight, when the influence of 
solar light 1s altogether withdrawn from the at- 
mosphere, and in the absence of moonlight, a 
sufficient quantity of hght is always diffused to 
render objects around us faintly visible, and to 
