SOUTHERN AFRICA. 39 
A fingle glance at the topography of the Cape and the adja- 
cent country will be fufficient to explain the caufe of this phe- 
nomenon which has fo much the appearance of fmgularity. 
The mountainous peninfula is connedted with a ftill more 
mountainous continent, on which the great ranges run parallel 
to, and at no great diftance from, the fea-coaft. In the heat of 
the fummer feafon, when the fouth-eaft monfoon blows flrong 
at fea, the water taken up by evaporation is borne in the air to 
the continental mountains, where, being condenfed, it refts on 
their fummits in the form of a thick cloud. This cloud, and a 
low denfe bank of fog on the fea, are the precurfors of a fimi- 
lar, but lighter, fleece on the Table Mountain, and of a ftrong 
gale of wind in Cape Town from the fouth-eaft. Thefe effeds 
may be thus accounted for 1 The condenfed air on the fummit 
of the mountains of the continent rufhes, by its fuperior gra- 
vity, towards the more rarified atmofphere over the ifthmus, and 
the vapor it contains is there taken up and held invifible or in 
tranfparent folution. From hence it is carried by the fouth- 
eaft wind towards the Table and its neighbouring mountains, 
where, by condenfation from decreafed temperature and con- 
cuflion, the air is no longer capable of holding the vapor with 
which it was loaded, but is obliged to let it go. The atmof- 
phere on the fummit of the mountain becomes turbid, the cloud 
is ftiortly formed, and, hurried by the wind over the verge of 
the precipice in large fleecy volumes, rolls down the fteep fides 
towards the plain, threatening momentarily to deluge the town. 
No fooner, however, does it arrive, in its defcent, at the point 
of temperature equal to that of the atmofphere in which it has 
floated over the ifthmus, than it is once more taken up and 
" vanifhes 
