The herald., 1893-10-22

the Koveri delta system is about 800, 600.
The cost of keeping mp this work has
been 81 800, 600; the returns are $3.50, 600
year.
The Godovari delta system irrigates
100000 acres, and two crops are raised
each year.
One great feature that strikes the ex-
perienced traveller in Southern India is
the marked contrast OF the condition of
the people in the government irrigated
districts and that OF those living in the
non-irrigated districts. In the former
they are generally prosperous and COM
paratiyely contented. while in the nom
irrigated districts it is just the reverse.
To go outside of the Macras presidency
for further examples OF what the control
OF all waters and the carrying out OF ir-
rigation works on gigantic scale by the
government will do, we have wide
field to select from all over India.
For comparison with some of the Eu-
ropean works you may take the Cavour
canal in Italy and compare it with the
Ganges. The Csvour is admitted to be
the finest piece of solid irrigation work
in Europe. its syphon, $40 feet in
length, and the masonry acqueducts,
one of them 635 feet long, being the most
interesting features of this grand work.
In the Gangee system some oil the So
called minor or branch canals are each
as large as the Cavour, which is not
one-third the size of the Ganges canal.
The Solani acqueduct of the Gsnges
canal is 750 feet ia length, carried upon
15 arches. The total length of masonry
ie about 900 feet. The foundations
are 252 feet wide and the
wells are sunk 20 feet below
the bed of the river. The width
OF the channel carried on THE massive
foundation and arches is 164 feet be-
tween the inner faces of the walls, and
the water runs many feet deep. The total
length of the Gavour canal is about 1000
miles. The Ganges branch canals have
each over 5000 miles.
Another speciman of what the gov
eminent has done on the Ganges system
in trying to make the beat of the peo-
ple's heritage, and guard their interests
in the all-important factor OF water, is
the Ratman Torrent works, marvel
Gus piece of engineering in the shape of
great retaining walls, nearly q mile in
length, built for the purpose of receiv-
ing the flood waters of this mountain
torrent directly into the canal.
The large numbers OF mountain min
ing bitches in this country, some of
which / am acquainted with in this
state and also Nevada, show both
boldness OF design and fine en-
gineering in their workmanship and
construction, and 30 do some of
the recent irrigation works on this
coast. The finest and boldest have
seen Of this type are the Sweetwater and
Bear Valley systems. Under somewhat
similar physical but more trying clima-
tic conditions than existed in the Gaze
of these mining and irrigation works in
the Sierra and foot hills, the waters OF
the Ganges canal carrying cubit feet per
second for each minere' inch running
through the fumes and bitches on this
coast, or to put it in other words, about
fifty tim es bigger have been carried over
the first 20 miles in channel 200 feet
wide and 10 feet deep; now carried at
great depth below the service, and
then high above it, over and under, and
throng torrents which rage with the
fury OF tropical storms, collected upon
-npun the TANKS oil the hills and hurled
down with violence, which in itH titanic
onset threatens even the most massive
masonry.
1t is the question of intensity and
duration of flood which has so import
ant bearing on the design and con-
struction of all storage systeme. The
trouble lies in the fact that most reHer-
voirs depend greatly upon the storm
waters, and the maximum floods are SO
great and go irregular in occurrence that
it would be ruinous financially to at
tempt to store such occasional volu mes
of water.
The head-works of Indian canals are
generally located at the highest possible
point and the highest possible level
continued throughout as far as possible.
An even fall of in 800 feet is often
preferred. Direct irrigation is never
permitted from the canals themselves.
With velocity of more than two feet
per second weeds do not give any trouble
at all.
To get back to India again, however.
/ would now say something about the
great tank system of storing waters.
This system is peculiar to India, and is q
most important factor in Indian irriga-
tion. These reservoirs, which are largely
owned in many casee by native proprie-
tors or land owners, are generally
formed by means of earthen embsnk-
ments one-fourth to two or three miles
long, having an inner slope of one and
one-half, two or three to one. Shallow
tallow tanks, which may be classed as
those containing six to ten feet depth OF
water, are designed to hold sufficient for
one crop only. Evaporation is generally
taken so to go inches, and in some rare
cases as much as 20 inches. Plants of
the lotus family, with broad leaves
floating on the water, decrease evapora-
ton. Some of the tanks still existing in
the Madras presidency are very large.
Puniari (partially destroyed) 10 about so
miles long, and the Veranum IL miles
long and containing SO square miles.
This last named tank yields a revenue of
$50, 900. Shallow tank buns or dams are
never. or at least very rarely, faced with
stone. Some of the largest tanks have
smbankments or dams of earth 80 or
even 80 feet high, and the inner slope
formed with stone revettine of one to
one or one to two.
Irrigation by means Of open wells is
carried on over large area. These
wells are generally owned by the agri-
culturists themselves, and may cost
from $50 to 800.
/ have frequently been asked about
India's wheat crop. The acreage under
wheat is about 10000, 900. and OF this
about 15,000,000 acres are irrigated.
Within few years the wheat area under
irrigation will be increased by some
100000 of acres when the schemes
now in progress and proposed under the
great Sarda project and throughout the