CHAP. 9.] PHYSICAL STRUCTURE. 35 
parallel ridges of the Nullamullays. “This fine sheet of water is about 
five miles long by three or four broad. It is nearly surrounded by 
picturesque hills, and several rocky islets stud its bosom."* It is a very: 
old tank, and the country below it for many miles is saved from being 
little else than a desert. 
In later times, the more extension scheme of irrigating a great 
area of country by means of a canal has been developed, and a grand 
ease of this kind is being tried in the very area under description. 
The irrigation of the great central hollow, the Khoond-air valley, is 
part of this scheme; the surface is peculiarly adapted for irrigation in 
having an elevated ridge of low ground, running for the greater part of 
the length of the valley down which the canal is being constructed, so 
as to throw water over the country on either side. There is, besides, the 
cross water-shed} between the Kistnah and Penn-air, and this is so very 
far to the north that, if water in sufficient quantity can be brought to it, 
the greater part of the valley to the south may be brought under water. 
This water is to be foundin the Toongabudra, several miles higher up the 
river, or to the west of the Khoond-air valley, and as it is necessarily at a 
higher level, there is good reason for hoping that this great engineering 
work will be a success worthy of all the labor and money which has been 
spent on it. The water of the Toongabudra is thus to be carried down 
to the Penn-air, north of Cuddapah, with which stream it flows until it 
is again brought up by a bund which is to be constructed at the mouth 
of the passage of the river, whence it will be distributed over the 
southern parts of the Nellore district. 
Not only have the physical features of the country been of use in 
this manner, but they have also been found to be especially adapted for 
the more improved communication by railway. The great barrier to 
* Captain Newbold, Jour., As. Soc., Vol. XV, page 392. 
T The waters of the Toongabudra have since been brought over the water-shed with 
marked success. 
o 
