PRESIDENTIAL ADDRESS. 437 
perceptibly more favourable than it was. In Lord Strathcona’s view, there was 
some change even before the settlers came in, as soon as the rails and telegraph 
lines of the Canadian Pacific Railway were laid. He told me that in carrying 
the line across a desert belt it was found that, within measurable distance of 
the rail and the telegraph line, there was a distinct increase of dew and 
moisture. I must leave it to men of science to say whether this was the result 
of some electrical or other force, or whether what was observed was due simply 
to a wet cycle coinciding with the laying of the rails and the erection of the 
wires. I am told that it is probably a coincidence of this kind which accounts 
for the fact that in the neighbourhood of the Assouan dam there is at present 
a small annual rainfall, whereas in past years the locality was rainless. Re- 
ference has already been made to the effect of cultivation in the Kalahari Desert 
in increasing the storage of moisture in the soil. But itis when we come to the 
division between healthy and unhealthy climates that the effect of science upon 
climate is most clearly seen. The great researches of Ross, Manson, Bruce, and 
many other men of science, British and foreign alike, who have traced malaria 
and yellow fever back to the mosquito, and assured the prevention and gradual 
extirpation of tropical diseases, bid fair to revolutionise climatic control. Note, 
however, that in our penitent desire to preserve the wild fauna of the earth we 
are also establishing preserves for mosquitos, trypanosomes and the tsetse fly. 
Nowhere have the triumphs of medical science been more conspicuous than 
where engineers have performed their greatest feats. De Lesseps decided that 
Ismailia should be the headquarters of the Suez Canal, but the prevalence of 
malaria made it necessary to transfer the headquarters to Port Said. In 1886 
there were 2300 cases of malaria at Ismailia; in 1900 almost exactly the same 
number. In 1901 Sir Ronald Ross was called in to advise; in 1906 there were no 
fresh cases, and malaria has been stamped out. Lesseps’ attempt to construct 
the Panama Canal was defeated largely, if not mainly, by the frightful death- 
rate among the labourers; 50,000 lives are said to have been lost, the result of 
malaria and yellow fever. When the Americans took up the enterprise they 
started with sending in doctors and sanitary experts, and the result of splendid 
medical skill and sanitary administration was that malaria and yellow fever were 
practically killed out. The Panama Canal is a glorious creation of medical as well 
as of engineering science, and this change of climate has been mainly due to 
reclamation of pools and swamps, and to cutting down bush, for even the 
virtuous trees, under some conditions, conduce to malaria. Man is a geographical 
agency, and in no respect more than in the effect of his handiwork on climate, 
for climate determines products, human and others. Science is deciding that 
animal pests shall be extirpated in the tropics, and that there shall be no 
climates which shall be barred to white men on the ground of danger of infec- 
tion from tropical diseases. 
If we turn to products, it is almost superfluous to give illustrations of the 
changes wrought by man. As the incoming white man has in many places sup- 
planted the coloured aboriginal, so the plants and the living creatures brought 
in by the white man have in many cases, as you know well, ousted the flora 
and fauna of the soil. Here is one well-known illustration of the immigration 
of plants. Charles Darwin, on the voyage of the Beagle, visited the island of 
St. Helena in the year 1836. He wrote ‘that the number of plants now 
found on the island is 746, and that out of these fifty-two alone are indigenous 
species.’ The immigrants, he said, had been imported mainly from England, 
but some from Australia, and, he continued, ‘the many imported species must 
have destroyed some of the native kinds, and it is only on the highest and 
steepest ridges that the indigenous flora is now predominant.’ 
Set yourselves to write a geography of Australia as Australia was when first 
made known to Europe, and compare it with a geography now. Suppose 
Australia to have been fully discovered when Europeans first reached it, but 
consider the surface then and the surface now, and the living things upon the 
surface then and now. Will not man be found to have been a geographical 
agency? How much waste land, how many fringes of desert have been 
reclaimed? The wilderness has become pasture land, the pasture land is 
being converted into arable. The Blue Mountains, which barred the way to the 
interior, are now a health resort. Let us see what Sir Joseph Banks wrote 
after his visit to Australia on Captain Cook’s first voyage in 1770. He has a 
