THE PHYSICAL GEOGRAPHY OF AUSTRALIA. 269 



part of the colony. The three or four summer months are naturally 

 hot, but there are no sudden changes at any time; there is a remark- 

 able uniformity of temperature; the nights are comparatively cool and 

 hot winds entirely unknown. In winter the weather is most delight 

 ful, the climate then being even superior to that of Naples; beautifully 

 clear sky and dry atmosphere are the ruling climatic features of this 

 season of the year in southeastern Queensland. The only slight dis- 

 comfort felt is during the westerly winds, which are seldom of longer 

 duration than three days. From the early days of settlement on the 

 shores of Moreton Bay the climate of the district has always been con- 

 sidered exceptionally healthy. In The Geographic History of Queens- 

 land the author quotes an interesting extract bearing upon this subject 

 from a report written in 1845 by Dr. Keith Ballow to the Bev. Dr. Lang. 

 Dr. Ballow, who had spent some eight years in Moreton Bay as Gov- 

 ernment medical officer, says: "The district of Moreton Bay is alto- 

 gether an extremely healthy one, there being only a few deaths from 

 disease of any kind. The climate in the winter season is one of the 

 finest in the world. This district is not a profitable field for doctors." 

 This seems to be the general verdict of those who are qualified to 

 express an opinion upon the subject. The most important factor of our 

 Australian climate is that of rainfall. Land without an adequate rain- 

 fall is useless for either pastoral or agricultural purposes unless arti- 

 ficially watered by irrigation. Although the total area of the continent 

 is about 2,941,628 square miles, a vast portion of that area has an 

 annual rainfall of less than 10 inches, and consequently it is of little or 

 no value whatever in its present state. This is notably the case with 

 the great central depression where immense areas of waterless desert 

 country obtain. Considering its compactness and wide climatic range, 

 the rainfall of Australia is very unequally distributed over the whole of 

 the territory, even in places where there is a regular wet and dry season. 

 A glance at the rainfall map will readily show that this is indeed very 

 marked along the eastern Pacific slope, where the greatest pluvial 

 measures have been recorded. The Cardwell and Mackay districts top 

 the score, the former with an average annual rainfall of some 150 inches ; 

 Arnhems Land follows with about G3 inches; the Australian Alps, the 

 Tweed and Mary rivers come next, each with 50 inches. These isolated 

 and somewhat limited areas are, however, distributed over a wide geo- 

 graphic range, extending from the most northern to the southern limits 

 of the continent, and they are separated by extensive tracts of country 

 or climatic zones, over which the average annual rainfall is not greater 

 than 30 inches. In the Cardwell and Mackay districts, which lie 

 wholly within the tropical rain belt, the former between the parallels of 

 15 and 20 degrees, the isopluvoise lines of 40 to 70 inches are very 

 closely packed together, so that the heavy rains in these zones seldom 

 extend beyond the Coast Bange, but are mostly precipitated over the 

 deltaic lands of the river and valleys and on the Pacific slope of the 



