36 



tropic, l3ut in the heart of the continent, the climate partakes of 

 the extremes of moist heat and cold dryness. The moisture is 

 brought by the monsoon winds, which follow the sun down from 

 the north coast, but the intense cold is due entirely to radiation 

 under a clear sky after the monsoon has abated. At the head of 

 the Hale River on the lltli September the thermometer ranged 

 from 85° F. during the day to 19° F,, or 13° below freezing, during 

 the night. No snow or hoarfrost ever accompanies this cold, be- 

 cause there is not sufficient condensable moisture present in the- 

 air. Humidity follows on the great heat, and then is precipitated 

 in torrents of rain, accompanied by electrical disturbances. 



Vegetation of special nature only could withstand such climatic 

 vicissitudes, and for this reason the perennial plants are feAv in 

 species, though individually numerous and identical with those 

 found in the terraced ranges to the southward. 



The rainfall of the plateau, expressed in terms of mean annual 

 average, is not suggestive in itself of aridity or drought, but when 

 it is considered that this rainfall, though amounting to from 15 

 to 20 inches, falls in torrential showers of short duration, while 

 the normal climatic conditions are those of excessive evaporation,, 

 it is immediately evident that the country's surface cannot par- 

 take of that moist condition essential to the continued growth of 

 herbage. Beyond this also is the occurrence of long intervals 

 without rain, when the only surface waters are those of some 

 rock hole in a gorge whose precipitous sides shut out the sun's 

 rays, or a hollow scooped in the creek sands by an eddy due to a 

 projecting ledge of rock, marking the jDosition of a rocky bar 

 across the channel. 



The creeks on the plateau are sliort and shallow, and at a few 

 miles from the ridge, which gave them birth, they become lost by 

 spreading over the level country. The plateau is a most arduous- 

 stage for travellers. Three times did Stuart essay to cross it 

 before he succeeded, and still later Warburton and his party 

 striking westward, fleeing as it were for their lives, succeeded in 

 crossing it, possessed indeed of their lives, but destitute of almost 

 every other thing with which they started. To the westward 

 the scrubs give way to sand and spinifex to within the West 

 Australian borders, but the north-west limit of scrub which turned 

 back Stuart is unknown. Descending the eastern slope of the 

 plateau, at no great distance from the telegraph line the traveller 

 is again on the great Austral plain, so called first by Favenc, who 

 crossed it from the coast range of Queensland througli its full 

 width to the plateau on which runs the telegraph line. The great 

 plain there is a smiling country now rapidly becoming covered 

 with cattle stations. The portions lying within South Australian 

 territory is well known to the commercial world as the Herbert 



