MAGAZINE OF SCIExNCE AND ART. 
143 
all the statistics connected with them, which I shall 
have great pleasure in submitting to the Society here¬ 
after. 
The second mode in which supplies of water can he 
obtained is by the construction of reservoirs, in which. 
the drainage of the country is collected, and stored up, 
as it were, for future use. There are several countries 
where the streams are not perennial, but are merely 
the outlets hv which the periodical or casual falls of 
rain are discharged. In the southern parts of India, 
within the tropics, the Tains are periodical and very 
heavy ; but although the earth is thoroughly saturated 
while these rains last, and though rich crops are pro¬ 
duced after they have ceased, yet the beneficial effect is 
only partial and temporary, and for several months the 
ground is parched and dried up for want of a supply 
of moisture, which can only be obtained by irrigation. 
The supply from these periodical rains would probably 
be quite sufficient, if distributed over the whole year, 
to keep up a constant fertility: all that has to he done, 
therefore, is to arrest as much as possible of the water 
on its way to the sea, for the purpose of doling it out 
during the dry season, as the wants of the community 
may desire it. 
• This system of storing water is not, however, limited 
to those countries in which the rains are periodical and 
certain. It is quite as applicable to countries like Aus¬ 
tralia, where the fall of rain is casual, uncertain, and 
scanty in amount. The following abstract of the effects 
produced in the. hill country in Central India, by' a 
judicious system of tank embankments, will enable the 
Society to judge of the possibility of adopting a similar 
system in New South Wales, and of the advantages 
which may accrue from it. 
In the district of Mairwara water was the great de¬ 
sideratum. From the hilly character of the country 
the rain which falls speedily' flows off. The rains, too, 
are exceedingly precarious, and bad seasons in this 
respect are the rule, good the exception. The amount 
even in favourable seasons rarely exceeds 22 inches, 
and it often ranges from 8 to 12 inches. In 1832 not a 
single shower fell, and a fearful famine was the conse¬ 
quence. Some small embaukments had been made, 
and the good effects produced by them encouraged 
Colonel Dixon, the Resident-officer in charge of the 
district, to submit to the Government a scheme for 
carrying out the system of tank embankments on a 
large scale. The reservoirs formed by these would 
supply irrigation to the lands at a lower level through 
sluices; and to those situated above the level of tlio 
reservoir by the wheel and bucket, or by' any other 
simple machinery. The percolation of the water 
through the ground would supply wells formed in rear 
of the embankment, from which, again, water might be 
raised to supply land which could not be reached by 
the sluices, The Government entered into the scheme 
proposed, and gave encouragement and assistance to the 
inhabitants of the district, who set to work energeti¬ 
cally ; in the course of a few years constructed no less 
than 290 dams, holding up 9675 acres of water, and 
irrigating nearly 15,000 acres of land. The following 
table will give, at a glance, the expenditure of the Go¬ 
vernment, and the results of the expenditure^ adding 
to the happiness of the people:— 
1 jj 
js 
Ploughs. 
Village 
Tanks. 
Population 
O 
d 
o 
fl 
Total in 1835 
Total in 1846 
2233 
6148 
2742 
9691 
2065 
39,648 
100,282 
£9,680 
21,022 
Difference 
(increase 
3915 
0979 
2065 
60,034 
£11,342 
Expenditure by the Government, which has 
produced these results ... ... £24,111 
Natural springs form the third source from which 
water for irrigation may be obtained. It is not neces¬ 
sary' that I should say anything as to the mode of 
making use of the water derived from these, the pro¬ 
cess of distributing it being of course similar to that 
adopted with regard to like quantities of water from 
any r other source ; means, of course, wonld be taken to 
enhance the supply as much as possible, but the 
quantity of water must be so entirely' contingent upon 
local peculiarities in the geological stmeture of the 
country as to render it impossible for me to do more 
than to allude to springs as a means which may, under 
certain circumstances, be made very extensively 
useful in irrigating land. 
In many countries, especially in those where the 
upper surface of the soil is of a light and porous cha¬ 
racter, the rain which fulls speedily disappears; it 
percolates thvough the upper strata, and is either col¬ 
lected in subterranean basins, formed by undulations 
of the strata, oris discharged lower down when the 
watertight stratum crops out. 
In such countries wells Mill be the principal source 
upon which dependence can be placed for the snjjply of 
an adequate quantity of water. In the account given 
of the works in the Mairwara district, in Central India, 
wells form a prominent feature. Here again a know¬ 
ledge of the geological structure of the locality is indis¬ 
pensable to those who would engage in the construction 
of wells, for the purpose of applying the water derived 
from them, to irrigation. When proper judgment, 
however, is exercised in the selection of sites for Wells, 
and in the application of the most economical and 
effective means for raising the w r ater, there is no doubt 
but that they will be found most useful and available 
sources of supply for irrigating small tracts of land 
which would otherwise be condemned to sterility. 
The last, and, under certain circumstances, the most 
valuable source of water supply, is the drainage or 
sewerage from large towns. The quantity of water is 
limited, of course, but it is charged with the richest 
aud most nutritive matter, so that a much smaller 
quantity of water produces the most marked effects 
upon the vegetation of the land to which it is applied. 
In the vicinity of Milan the seworage initer is poured 
into the Vettabbia, aud the land irrigated with this 
water produces eight crops iu the year, and such land 
is let at from £8 to £22 per acre. Similar results 
have been arrived at in the neighbourhood of Edin¬ 
burgh, where laud, worth originally £4 per acre annu¬ 
ally'. has been Ipt for £20 per acre, the increased value 
being due altogether to the fertilizing effects of the 
sewerage w’ater. 
Having given a brief description of the various 
systems of irrigation which have been, and still are 
practised in various parts of the world, I will now 
draw your attention to the practical application which 
it is possible to make of some, if not all, of these 
sy'stems to the circumstances of this colony. 
* It is quite true that the state of things here is essen¬ 
tially different from that which does or has prevailed, 
either in India, or in the North of Italy, so far I mean 
as regards the tenure! of land and the power of the 
Government to undertake works of the kind to which 
allusion has been made v but in come respects the differ¬ 
ence is to the advantage of this colony, The amount 
of land in the possession of the Government is a very 
great advantage; it not only does away with the neces¬ 
sity of purchasing the land required for tho works, but 
it places at the disposal of the Government an amount 
of capital which may bo most usefully expended upon 
works of improvement generally, and more especially 
upon those by which the value of this capital may be 
enhanced Labour, it is true, is dear, but the materials 
for the different descriptions of work aro easily pro¬ 
curable. I will not, however, attempt to institute a 
comparison which must necessarily be imperfect; and 
which, even if it were possible, would not, in any way, 
affect the question to he decided, namely, the amount 
of advantage which may reasonably be expected frora, 
