248 Mr. Colebrooke on the 
cannot but be refreshed by the passage of such humid air over 
it. Its heat is mitigated, or that of the atmosphere above it is 
so, by cool breezes, which descend from high mountains, bring- 
ing’ humidity recently fetched off the sea. 
In a former visit to the Cape, while attentively observing the 
striking phenomena of the cloud on Table Mountain, during a 
south-east wind, I fell upon some speculations regarding visible 
vapour, to which I shall now advert. 
To preserve theirconnexion, some remarks are here repeated, 
which have been noticed in reference to a different subject in 
another place. 
I consider every stationary cloud, whether hanging on a 
mountain, or elevated in the upper regions of the atmosphere, 
as consisting of transient vapour, of which it receives accessions 
on the one side, and parts with the same on the other; it is 
vapour visible during its passage through a circumscribed 
space ; transparent before it reaches that place, and again after 
traversing it. A cloud in motion may, like a volume of smoke, 
be composed identically of the same vapour, continuing in 
progress until finally dissipated. Buta cloud at rest is, as the 
smoke of a chimney, a continuous object viewed from a distance, 
yet transient, seen from a nearer point of view. 
The cloud, which, during wind, hangs upon a mountain’s 
summit, certainly is so, as may be distinctly observed on a near 
approach. Vapour is continually passing over the summit and 
down the cliffs, becoming gradually attenuated, and vanishing 
into thin air, as it quits the mountain. 
Such, likewise, are clouds which appear immediately over a 
peak, at a certain elevation above it. A cloud suddenly shews 
itself, increases for a while, varies its form, yet remains in its 
position, (though the wind blow strongly,) and at length wanes, 
and finally vanishes, without change of place. 
This is often seen above lower mountains, in the vicinity of 
a loftier one, which, at the same moment, is enveloped in mist. 
The clouds suspended above inferior peaks, and the mists which 
cover the higher summits, are manifestly level, maintaining 
themselves at uniform height, and clearly marking diversity of 
