TBANSACTIONS OF SECTION E. 321 



steppes of Tartary and Mongolia are nearly treeless, and have 

 less than lOin. of rain in the year. 



In Europe, man's action has been powerful enough to com- 

 pletely alter the face of the land, but we know from history 

 that till comparatively recent times it was covered with forest, 

 and this may be presumed to have been the effect of the rain- 

 fall with which the Continent is blessed, through its latitude, 

 its being intersected by great oceanic areas, and the action of 

 the Gulf Stream and the Eeturn Trades bringing copious mois- 

 ture from the Southern Hemisphere — a rainfall coming more or 

 less throughout the year, very heavy in particular spots, but 

 not tropically heavy anywhere, yet quite sufficient, considering 

 the high latitude, to promote vigorous arboreous growth 

 almost in every corner. 



Australia has a poor mean average of rainfall throughout 

 its vast interior (5iu. at Alice Springs, Gin. at Charlotte 

 Waters), the greater part of which lies within an anticyclonic 

 region of high pressure and the dry south-east trades. This is a 

 land, therefore, subject to very severe droughts, periodically 

 blighting the face of nature from the 18th to the 30th parallel 

 of latitude, and occasionally embracing the whole continent ; 

 and as a consequence — though Darwin ("Journal of Ee- 

 searches," p. 47), with scantier information than we possess, 

 speaks of the whole of Australia in spite of its arid climate as 

 being covered by lofty trees — I believe we should be correct in 

 saying that the interior for many thousands — yes, even hun- 

 dreds of thousands — ^of square miles is nearly absolutely tree- 

 less. Along the eastern coasts and mountains the rainfall is 

 heavier (4:8in. at Brisbane, 49in. at Sydney : compare 20in. at 

 Adelaide and 25in. at Melbourne), and the arboreous vegeta- 

 tion is more profuse ; while the x\ustralian Alps in the south- 

 eastern corner, being within the area and influence of the 

 cyclonic depressions that pass along the southern coast in 

 regular succession, are covered with Eucalyptus woods, and 

 there the massive E. amygdalina attains its gigantic size. 



This review is too cursory and sketchy, but, when taken in 

 conjunction with the more careful examination of the rainfall 

 and forest of New Zealand, previously given, it may perhaps 

 be considered enough to give semblance of truth to the propo- 

 sition that tJw native forests of a country are located in tJwse 

 districts blessed ivith abundant rainfall, and by tlic said rainfall 

 arc mainly brought into existence. That a reflex action of forest 

 in producing rain also may exist to a limited extent, I quite 

 believe ; but, as I have implied, I think it is a power supposed 

 by most people to be much greater than it actually is. Of 

 course, also, what constitutes sufficient abundance of rain for 

 arboreal development depends on latitude and several other 

 circumstances. 

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