Setting out from Kolobeng, the most advanced of the English missionary stations, he arrived, after having crossed some three hundred miles of a region without water, at the beautiful river Zouga, which issues from the western extremity of Lake Ngami. "A region of drought, where no river glides, Nor rippling brook with osiered sides, Nor sedgy pool, nor bubbling fount, Nor tree, nor cloud, nor misty mount Appears, to refresh the aching eye; But barren earth, and the burning sky, And the blank horizon round and round."[81] Lake Ngami is from 45 to 60 miles long, and from 56 to 110 in circumference. Its direction is N.N.E. to S.S.W. Its southern portion curves westward, and it receives from the north-west the Teoughé. The water, very fresh when the lake is full, grows brackish during the dry season. At the latter period it is very shallow, and at eighteen or twenty miles from the shore canoes can be manoeuvred with the help of a pole. The banks are everywhere low. At the west a considerable space, utterly bare of trees, proves that the lake was formerly larger. During the months which precede the arrival of the northern waters, cattle, to quench their thirst, make their way with difficulty through the belt of reeds dried up by the sun. The natives, says Livingstone, who reside on the shores of the lake, tell us that trees and antelopes are carried down by the waters during the annual inundation. The same traveller informs us that the vast regions lying to the north of the lake at such great distances--regions copiously watered, and deluged every year by the heavy tropical rains--pour towards the south the excess of the waters which saturate their soil; and a certain quantity of these waters, encountering the lake on their way, flow into it. It is in March and April that the inundation begins. The waters, on descending, find the rivers dried up, and the lake itself exceedingly shallow. The rivers in this part of Africa flow in channels capable of containing a far greater volume of water than they generally hold. When looking at them, you might believe yourself in some desolated Oriental garden where all the irrigating canals still exist, but where the dams permit only a mere thread of water to take its course. "The water," adds Livingstone,[82] "is less absorbed by the earth than lost between banks too wide apart, where the air and the sun evaporate them. I am persuaded that there is not in the whole of this country a river which loses itself amid the sands."