73 ' VOYAGE OF THE POTOMAC, [December, 
above the sea, on the shore ; grows, changes shape without change 
of place (although the wind, meantime, continues to blow most, 
violently), wastes, and vanishes. Dr. Arnott, in his elements of 
physics or natural philosophy, thus accounts for the singular 
beauty and density of the clouds which frequently envelop Table 
Mountain : — " The reason of the phenomena is, that the air con- 
stituting the wind from the southeast having passed over the vast 
Southern Ocean, comes charged with as much invisible moisture 
as the temperature can sustain. In rising up the sides of the 
mountain it is rising in the atmosphere, and is therefore gradually 
escaping from a part of the forngier pressure ; and on attaining the 
summit, it has dilated so much, and has consequently become so 
much colder, that it has let go part of its moisture: and it no 
sooner falls over the edge of the mountain, and again descends in 
the atmosphere, where it is pressed, and condensed, and heated as 
before, than it is re-dissolved and disappears, the magnificent apr 
parition dwelling only oi]i the inountain top." 
