364 A JOURNEY INTO THE 
little moisture during the dry winter season, the quantity of snow is 
very small, on account of want of moisture to be condensed in the at- 
mosphere. It seems also, that the currents of air, carrying moisture 
from an equatorial climate towards the polar regions, have lost already 
their waters before they can reach the considerably elevated regions of 
the interior: those moist currents of air generally suspend and arrive 
during the winter months in lower regions, and on that account dis- 
~ charge their contents below the marks of elevation of a high continent, 
- lying a considerable distance from the southern tropic line. The rainy 
* season here commences, as in many other parts of South Afriea, to- 
. wards the middle of November, being the beginning of the summer, 
. and occurs chiefly in the form of thunder-showers. It is difficult to 
oe . decide if the fall of rain during the summer months, towards the ele- 
vated interior regions, is caused by currents of moist air returning from 
a tropical climate towards the polar regions, and that they hang in a 
much higher atmosphere during the summer months, and have no ob- 
stacles in their way during that time, to hinder their reaching those 
regions. Thunder-showers are very frequent, as soon as the rainy 
season has set in; they take place often every day, nearly for a whole 
week, as long as the atmosphere is impregnated with moisture, which 
. becomes generally heated to a high degree by the effect of the powerful 
rays of a burning sun, until on a sudden, thunder-clouds accumulate, 
. and torrents of rain burst forth from the clouds, which make the tem- 
perature moderate and agreeable. 
— A climate, as just now described, has a great influence on vegetation : 
it seems to be most favourable to the Natural Orders Graminee and 
_ Cyperacee ; and many useful grasses are predominant, as well in these 
regions as over large tracts of countries lying between here and the 
colony. They turn dry as soon as the rainy season is over; but it is 
not likely that the usual degrees of cold in these parts should hurt 
these orders of plants. It is the custom of the natives here to set the 
fields ux fire as soon as the grasses turn dry, a practice which is very 
annoying, on account of the dense smoke filling and darkening the at- 
mosphere, which lasted for many weeks, and was a great hinderance, 
preventing our seeing any distant view. As the vegetation is very 
luxuriant, the grasses grow in many places to a considerable height, 
concealing often lions and other dangerous animals, which may reason- 
ably inspire. the natives to burn down the dried vegetation; and as 
