CLIMATE. 
667 
from continuing more than a few days at a time, and, in fact, 
breaks up the summer into a number of short periods with, 
as geologists would say, a glacial one intervening. Climates 
change by the increase or decrease of forests ; artificial causes 
arising from the agency of man, by the introduction of 
domestic animals, cattle and sheep, which clear the ground 
of its natural excessive vegetation, and thus by exposing the 
surface to the sun’s rays dry up former swamps, and diminish 
the fall of rain, often rendering climates warmer than they 
were before; this has been the case in New Zealand, to a 
great extent; when I first went to Wanganui, the ground 
having never been trodden by animals, was so light and 
spongy from the matted roots of plants, that in walking 
over it, the foot frequently sank ancle deep, this caused it to 
retain moisture for a long time, but now being thoroughly 
trodden and eaten down, the rain is either at once absorbed, 
runs off, or is evaporated by the sun’s rays ; the scrubby 
ground and underwood likewise disappear before the flocks 
and herds ; this also contributes to change the climate, in- 
dependently of the draining and breaking up of the ground, 
and cutting down forests. Climates likewise, in some respects, 
are deteriorated by man ; this has been remarkably evident 
in our colonies ; when I first knew Australia, hot as the 
climate is, it was still remarkably healthy and free from 
disease ; before I left, scarlet and typhus fevers appeared, 
and now Sydney is never free from the former ; the same 
was the case with New Zealand, and the Islands of the 
Pacific, but many of the diseases of the old country are now 
quite naturalized ; this appears in no small degree to be 
owing to the class of emigrants introduced, the emigration 
agents have naturally gone to the Union workhouses first, 
and although the parties may have landed without any 
apparent disease, yet they have had the germs of many 
which strength of constitution hindered from being deve- 
loped, but when they came into contact with the native he 
has taken them, or when any circumstances have impaired 
the emigrant’s health, then first one complaint or another 
has made their appearance; this natural healthiness of climate 
