35 
conditions are recognisable by our senses, others by delicate 
instruments ; but there are conditions that neither barometer, 
thermometer, nor any other artificial means enable us to 
detect. We recognise some of these in their influence upon our 
bodily comfort, on our sensations, and so on. Others, how- 
ever, make themselves known by particular forms of maladies 
which may affect plants or animals, or the more terrible epi- 
demics which devastate humanity, as do tropical hurricanes 
forest tracts that lie in their course. Is it not the case that 
irregularity or derangement in the order of what by general 
consent is designated “ seasonable weather,” is accompanied 
or speedily followed by deranged health conditions in plant 
and animal life ? Popular proverbs indicate that such is the 
fact. 
5. Although, upon their grand scale, such changes in 
climatic conditions as have occurred in the progress of time 
have been brought about altogether independently of human 
agenc} r , instances are numerous in which by the intervention 
of man and by other physical agency such alterations have 
been effected. A very few instances must suffice. In the 
Cape de Verd Islands, destruction of the forests by burning 
had the effect of drying up the springs and rendering the 
climate sultry. Persia, Greece, and other countries have 
from a similar cause had their climate deteriorated. In the 
Pyrenees the cutting down of the forests had rendered tracts* 
unhealthy by the destruction of the barrier which formerly 
had excluded the southern winds. In Castile and Arragon 
similar complaints were made long ago. In America cutting 
down the forest has rendered localities drier and more 
healthy, as ee the wood fever ” has disappeared. f And there 
are many other examples of climate being affected by means 
of forest denudation. While these notes are being arranged, 
a striking illustration of the subject now in hand occurs in 
Italy. In certain districts, during the last ten years, terrible 
inundations have destroyed much life and property, and have 
moreover caused considerable sickness where formerly the 
localities were healthy. Public inquiry has established the 
point that these unfortunate changes were due to what is 
described as “ the mania which has impelled proprietors to 
cut down forests.” J Mountains which for centuries had been 
covered with pine and oak-trees were reduced to bare rocks ; 
picturesque valleys were converted into swampy marshes. As 
a result of measures taken to restore the original state of 
* The Valley of Azun. f Hopkins’ Atmospheric Changes , p. 83. 
+ Morning Post , Nov. 3, 1881. 
I) 2 
