Two stupid Englishmen afterwards broke through the cake in spite of the entreaties of the natives, and the well and the whole valley dried up hopelessly.

Here the water, oozing forth from the surface of the sponge mantle, collects in the centre of the slightly depressed valley which it occupies, and near the head of the depression forms a sluggish stream; but further down, as it meets with more slope, it works out for itself a deeper channel, with perpendicular banks, with, say, a hundred or more yards of sponge on each side, constantly oozing forth fresh supplies to augment its size.
When it reaches rocky ground it is a perennial burn, with many aquatic plants growing in its bottom.

One peculiarity would strike anyone: the water never becomes discoloured or muddy.

I have seen only one stream muddied in flood, the Choma, flowing through an alluvial plain in Lopere.

Another peculiarity is very remarkable; it is, that after the rains have entirely ceased, these burns have their largest flow, and cause inundations.