84 
On Irrigation in Tasmania . 
rice to the acre without intermission, and support a popu¬ 
lation of 300 to 400 to the square mile. 
From these statements an idea may be formed of what 
has been effected in the way of works of irrigation in 
India, even by the natives without the advantage of 
European arts and science; and, consequently, of what 
may be done in countries occupied by Englishmen. 
Tasmania lias peculiar facilities for irrigation—in some 
respects incalculably superior to those of India. 'The 
most remarkable difference between the two countries, 
in reference to this subject, is in the formation of their 
surfaces : while, in the peninsula of India, no single 
instance is known of a natural reservoir of water from 
a pond to a lake, in Tasmania I have not heard of an 
individual river or creek which has not in the upper part 
of its course a proportionally extensive lake or lagoon. 
Hence, while in the formation of tanks in India the 
embankments must generally be of great extent; in the 
latter country there are innumerable natural basins, 
where, by a very short bank, a very large body of water 
may be collected. This is especially the case with the 
large rivers : they all, I believe without exception, rise 
in extensive lakes, the mouths of which can be shut up 
at the most insignificant expense. One of these contains 
probably 100 square miles of surface : a dam at the outlet 
of this, sufficient to retain the water at 1 yard above its 
natural level, would collect 300,000,000 of cubic yards 
of water, sufficient to water through the whole summer 
150,000 acres. Another of these (Lake Sorell, at the 
head of the Clyde,) has a surface of 20 square miles, 
and an outlet of 9 feet broad ; across this a timber dam 
has been built, probably for £25 or thereabouts, which, 
if the doors were 2 feet higher, would retain in this lake 
above its natural surface 60,000,000 cubic yards, or 
