242 A. G. HAMILTON. 
In 1886 the Royal Commission on Conservation of Water 
estimated that the carrying capability of the Colony of New South 
Wales was 55,000,000 of sheep if irrigation were carried out; but 
in 1890 the Government Statistician gave the number in the 
Colony as 55,986,431—nearly a million over the Royal Commiss- 
ion’s estimate under irrigation. I think it is not too high an 
estimate to say that New South Wales is capable of carrying at 
least 100,000,000 if the two last courses were resorted to viz. :— 
converting on overplus of feed into hay and silage, and conserving 
the rainfall for irrigation. If, as we have been told, he who makes 
two blades of grass grow where one grew before, is a benefactor 
to his species, what could be said of a plan which would do that 
over most of the vast area of Australia, and so double the wealth 
of our land 2 
Before leaving the subject of the effect of pasturing stock, I 
may quote the following passages from Wallace :—“ We know for 
example that the introduction of goats into St. Helena utterly 
destroyed a whole flora of forest-trees”; and ‘“ Cattle will in many 
districts prevent the growth of trees.”’* And again Charles 
Darwin says: ‘‘ But how important an element enclosure is I 
plainly saw near Farnham in Surrey. Here there were extensive 
heaths, with a few clumps of old Scotch firs on the distant hilltops: 
within the last ten years large spaces have been enclosed, and 
self-sown firs are now springing up in multitudes so close that all 
cannot live. When I ascertained that these young trees had not 
been sown or planted, I was so much surprised at their numbers 
that I went to several points of view whence I could examine 
hundreds of acres of the unenclosed heath, and literally I could 
not see a single Scotch fir, except the old planted clumps. But 
on looking closely between the stems of the heath, I found a mul- 
titude of seedlings and small trees which had been perpetually 
browsed down by the cattle. In one square yard, I counted thirty- 
two little trees; and one of them with twenty-six rings of growth 
had, during many years tried to raise its head above the stems of 
* Geographical Distribution of Plants, 1st Ed., Vol. 1., p. 44. 
