io6 
TRAVELS IN 
fpiral horns are three feet in length, and feem to be very ill 
adapted for the convenience of the animal in the thick covert 
which it conftantly frequents. The hind part of the duiky 
moufe- colored body has feveral clear white ftripes, and differ- 
ent from moft of the genus : on the neck is a (hort mane : the 
flefh is dry and without flavor. 
The beds of fand, upon the margin of the valley, were all 
covered with faltpetre as white as fnow. The production of 
this fubftance has certainly an influence upon the temperature 
of the air, caufmg a confiderable degree of cold. A full hour 
after the fun had rifen the thermometer flood, in the fhade, at 
26°, or fix degrees below the freezing point. At Little Loory 
fonteyn, where the foil was hard, dry, and ftoney, it was ten 
degrees above freezing ; and about the fame time on the pre- 
ceding morning, on the banks of the Traka, where there was 
alfo much nitre, the mercury was five degrees below the freez- 
ing point. The weather during the three days was per- 
fectly clear, and the wind had not fhifted a point. That the 
great changes in the temperature of the air upon the defert, 
whilft the weather apparently remains the fame, arife from 
fome local rather than general caufe, is pretty evident from an- 
other circumftance : in travelling at night upon the Karroo, if 
the wind fhould happen to blow upon the fide, it is very com- 
mon to pafs through alternate currents of hot and cold air, 
whofe difference of temperature is moft fenfibly felt. Whether 
the cooler columns of the atmofphere may have been owing to 
the fubjacent beds of nitre, which frequently occur on the Kar- 
roo plains, or to fome remoter caufe, I have no grounds fuffi- 
ciently 
