SHAPE OF CLOUDS. 
105 
When these clouds are at some distance and we 
look at them edgewise, they appear to be in layers, or 
at other times they rise into the higher air and spread 
out into smoky bands; when they take on this form 
we call them cumulo-stratus. 
The cumulus, it seems to me, is the most wonder¬ 
ful of all clouds. Moving as slowly as it does, about 
twenty-five miles an hour, the vapors are constantly 
settling; as they drop down into the lower and 
w^armer air they as constantly evaporate again and 
rise to the top of the cloud, ever changing its crest 
from one form to another. They are the playground 
of the sheet lightning on warm summer nights. In 
their folds the evening sunbeams seem to revel. “ We 
often see the pink Alpine glow,” Van Dyke says, 
“ suffusing the white castellated tops; and the shadows 
caused by sharp breaks of form often show blue, lilac, 
and even pale green in hue.” 
The nimbus is the earth cloud, for it catches the 
smoke and dust, which give it a dark-gray appearance, 
but it is never black, according to the same excellent 
authority on color quoted above. The heavy storm- 
cloud may border on purple,” he continues, ‘‘and 
sometimes preceding cyclones it is sea-green, but it is 
never black.” 
Though the nimbus is the homeliest of all 
clouds, it is the most beneficent, for it is this 
cloud that brings us the refreshing showers and 
the steady rains. The nimbus often has a dark 
dust - cloud as an advance guard, carried along by 
a strong wind. Often during days of rainy weather 
