THEORY OF CLOUDS. 
361 
Ostroc, it was remarked, were capped with clouds, 
which remained in a state of apparently calm re¬ 
pose upon the summits, while a breeze, little short 
of a gale of wind, carried all other clouds along 
with great velocity. This is a circumstance so 
common in these islands, and indeed in all moun¬ 
tainous countries, that it would scarcely have me¬ 
rited observation, had it not formerly suggested 
to me an explanation of the phenomenon of the 
suspension of clouds, which, as far as I know, is 
new * The force acting against the suspension 
of clouds, is gravity, which, on account of the re¬ 
sistance that very minute substances, such as the 
almost invisible particles of vapour in clouds, meet 
with in their descent, from the air, can be pro¬ 
ductive of no great velocity; but the force acting 
against the retention of clouds on the tops of 
mountains, in boisterous weather, is the wind, 
which may have a velocity of fifty miles an hour, 
or upwards. Hence whatever cause is sufficient for 
the retention of clouds upon mountains, against 
the action of the wind, must be sufficient (all 
other circumstances being the same) for the sus- 
* The first observation of this circumstance occurred 
in 1820, while passing the Faroe Islands, in a gale of wind. 
The theory of die suspension of clouds diat was suggested 
by it, was first communicated to the Liverpool “ Society of 
Travellers into Foreign Countries," about two years ago. 
