144 
MAGAZINE OF SCIENCE AND ART. 
the development of something approximating to a 
general system of irrigation in New South Wales. 
Before I attempt to -describe the mode in which such 
a system may be carried into effect, I must direct yonr 
attention to the results which may reasonably be ex¬ 
pected from its adoption : and it will he time enough 
to go into detailed explanations when I have proved 
that advantageous results may fairly bo anticipated. 
I may observe, in the first place, that there are two 
classes of persons who will bo most specially benefitted 
by the development of auy simple and easily managed 
system by which the produce of the soil may he in¬ 
creased. These are the agriculturist and the flock- 
owner. The former has often to regret the loss ot his 
crop from the droughts which too frequently interfere 
between seed time and harvest. The latter has _ to 
mourn over the loss of flocks and herds which perish 
during a drought, partly from want of food to eat, hut 
principally from want of water. 
The flockowner, again, even when not affected by 
drought, is obliged to distribute his flocks and herds 
over a large area. The produce of the natural pas¬ 
turage of the country is too scanty to admit of thedc- 
pasturage of one-tenth part of the stock which might 
he kept upon it, were proper means taken to increase 
its fertility, among which means irrigation ranks 
highest. The agriculturist is obliged to content him¬ 
self with inferior crops from the want of means of ap¬ 
plying the proper stimulus to the soil, which means 
would bo afforded were he placed in a position to 
irrigate his farm. 
& The soil and the climate of Lombardy are not more 
favourable to cultivation than those of many parts of 
this colony; and the district between Lilian, Lodi, and 
Pavia, containing about 100,000 acres, supports 100,000 
head of cattle, 28,000 horses, and 100,000 head of 
smaller stock—an amount which would in tins country 
depasture an area at least twenty times as great. The 
increased capacity of maintaining stock is due entirely 
to the mode in which advantage has been taken of the 
water by which this district is surrounded to irrigate 
the whole of it perfectly. 
I will not pretend to estimate the actual amount of 
the benefit which would accrue to New South 'Wales 
by the adoption of a good system of irrigation; the 
facts, however, which have been laid before you are 
sufficient to prove that they are of sufficient impor¬ 
tance to warrant a large outlay of money. If it were 
in the power of any owner of an estate to increase 
the annual value of his property tenfold, he would act 
wisely in expending an amount of capital on the under¬ 
taking, the interest of which would he equivalent to 
five times the rental; or, to put this into a numerical 
shape, if the annual value of a property amounted to 
£100 the owner would act wisely in expending £10,000 
upon improvements, if by such improvements he could 
raise the annual value to £1000. Assuming then, that 
the colony would he benefitted were it possible to carry 
out an extensive system of irrigation, I trill now pro¬ 
ceed to establish the possibility ot doing so. I do not 
of course mean that it would he possible to irrigate 
even one-tenth part of the land of the colony, or that 
it won Id he wise to look forward to the probability 
of operations even upon, the whole of this tithe of the 
area for many years to come. My object is rather to 
show from whence the supply of water for such a 
purpose maybe derived, and to give a sketch of the 
works which would he required to make it available— 
and first a$ to the quantity of water. Judging from 
the experience of other countries it would seem that a 
supply of water equivalent to one cubic foot per second 
is sufficient, if properly administered, to irrigate 100 
acres of land. N ow, 100 acres of land contain 4,356,000 
square feet, and 1 cubic foot of water per second in two 
hundred days (during which period it may be neces¬ 
sary to apply water to the land) will amount to 
17,280,000 cubic feet, or about four cubic feet of water 
to each foot of land—tills quantity must be applied at 
regular intervals, and it remains to he seen how this 
amount is to be procured. It is evident that in this 
the principle which has been; acted upon so successfully 
in Central India, and draining the rain "Water, must be 
adopted. The livers are too few in number, and the 
stream flowing in their channels during the dry season 
is too scanty to ho depended upon as the sole source o? 
supply for a system of irrigation. ^ 
What then is the quantity of rain w hich falls m this 
colony, and what proportion of this amount can be con- 
I side red available; that is, what proportion of the ram 
which falls finds its way into the watercourses? In 
order to reply to these questions satisfactorily, I ought! 
to be in possession of the records of meteorological 
observations made in all parts ot the country, and of 
simultaneous observations upon the discharge of the 
outlets carrying off the surplus waters of any known 
area of drainage, a comparison of the quantity ot rain 
with the amount of the discharge in various parts of 
the colony, would afford data of the utmost importance 
in such an invest!cation as that which I am now 
attempting. Luckily, I am in possession of a senes of 
meteorological observations giving the quantity of ram 
which has fallen at the South Jfead, and I have aLo 
been furnished with the area from actuql surveys of 
the ground which drains itself in to, the Lachlan Swamp, • 
also into the Botany Swamp. Experiments which have 
been carried on by Mr. Bell for some time past ip the 
actual discharge of water from the area of drainage 
have given me the means of making an approximation 
to the proportion between the quantity of rain and the 
amount of discharge. The following are the facts upon 
which the calculations are based. The annual quantity 
of rain, as indicated hv the pinvioineterafc the South 
Head has been on an average of 15 years 49'209 inches; 
the largest amount in any one year was 7 6**31 inches in 
1841; and the smallest quantity was in 1819, when the 
rain-gauge only marked 21* 485 inches. 
Tlie area of drainage into the Lachlan and Botany 
Swamp is said to be 4737 acres, or say roughly 5000 
acres, or 217,800,000 square feet The mean daily dis¬ 
charge during the month of September, as measured at the 
sluice at Botany, was 1,869,500 gallons ; to this must 
be added 000,000 gallons for the amount furnished to 
Svdnev from the Lachlan Swamp, The waste through 
the dam and soil at the outlet at Botany is estimated 
at 100,000 gallons, and the discharge through a tan- 
yard is said to he at least 220,000 gallons. Hie main 
daily discharge to waste may amount to the total oj 
these items, that is, to 2,889.500 gallons, or 402,330 
cube feet, and in the month to 13, 869 ,fp 0 cube feet. 
Now*, tie area of drainage, as given above, is 21 , ,dUO, OO 
square feet, and the fall of ram in September was dvlb 
inches. The actual quantity of water over the whole 
of this area was about G1 millions of cube foot; and as 
tbo discharge was, as befoie stated, I3,8b9,600 cube 
feet, the ratio between the supply and waste is as 1 to 
•227 ; so that, between one-fourth -and one-fifth oi the 
rain which falls may he considered available for irri¬ 
gation. . . . 
' The quantity of water which is required to irrigate 
thoroughly anr quantity of land during 200 days has 
been stated at'48 inches, and as the average quantity 
of rain shown in the returns for the whole year is 
49-209 inches, the quantity falling in 200 days may be 
taken at.27 inches, of which the available amount, ac¬ 
cording to the proportion determined before, of 1 : -o<, 
will be about G inches; Irat as 48 inches are wanted, it 
follows that the rain which falls upon 8 acres is suffi¬ 
cient to irrigate one acre fallv, or that a proprietor ot 
tOO acres might, by making use of the water tailing 
upon his own property, irrigate 100 acres perfectly. 
I live these numbers, of coarse, only as approxima¬ 
tions’; but they are founded upon satisfactory data so 
far as regards the land in the immediate vicinity ot 
Sydney. The Government has received twelve sets ot 
meteorological instruments, and as instructions have 
been given to the surveyors to take every opportunity 
of "aagin" the streams which they meet with, 1 .rust 
;h;U in the course of a few years we may be in posses- 
