WORLD AREAS 33 
of America, only one third of the whole surface 
receives above 20 inches of rainfall annually; one 
third receives from 10 to 20 inches, and one third 
receives less than 10 inches. That is, about 
1,267,000,000 acres in Australia are subject to 
“reclamation by dry-farming methods. This condi- 
tion is not far from that which prevails in the United 
States, and is representative of every continent of the 
world. The map on pages 30-31 shows graphically 
the approximate rainfall over the various parts of the 
earth’s land surface. The following table gives the 
proportions of the earth’s land surface under various 
degrees of annual precipitations : — 
ANNUAL PREcIPITATION PROP OBEN OF ) Hare Lanp 
Under 10 inches So 25.0 per cent 
From 10 to 20 inches . . 30.0 per cent 
From 20 to 40 inches . . 20.0 per cent 
From 40 to 60 inches . . 11.0 per cent 
From 60 to 80 inches . . 9.0 per cent 
From 80 to 120 inches. . 4.0 per cent 
From 120 to 160 inches. 0.5 per cent 
Above 160 inches... 0.5 per cent 
100.00 
Fifty-five per cent, or more than one half of the 
total land surface of the earth, receives an annual 
precipitation of less than 20 inches, and must be 
reclaimed, if at all, by dry-farming. At least 10 
D 
