A PUZZLE FOR THE SCIENTIFIC. 373 



an isthmus, as I may call it, of the Great Thirst Land, 

 where we were convinced not a drop of liquid could be 

 obtained for three days, and, possibly, if a certain vley 

 were dry, for a longer time. 



As it was moonlight, and that is the coolest time for 

 trecking, and your cattle with such light seem to steal 

 more rapidly over the ground, we made excellent pro- 

 gress, so that we were outspanned by the last water by 

 nine o'clock. 



The pits in which the water was contained we had 

 learned were in the source of a dry river-bed one of 

 those extraordinary phenomena peculiarly representative 

 of this part of Africa. That water flowed in them once 

 constantly cannot be doubted ; but what has become of 

 it ? Well I had better leave the scientific to explain. 



However, all over the country they are to be found, 

 some large, very large two hundred and more yards 

 across ; others small, not greater than a little Scotch 

 burn. Submerged in the hungry sand here ever ready 

 to swallow all it can engulf you discover boulders 

 and rocks, marked with the indelible and indisputable 

 lines that tell so plainly that they have been submitted 

 to the action of water from time immemorial. And the 

 vegetation on their margins the trees, and more espe- 

 cially the reeds, tell of the presence of water, but where 

 is it to be found ? 



My boys discovered some old pits made by the bush- 

 men ; they were at least twenty feet deep, and all we could 

 say of them was that the soil at their bottom was damp. 

 However, they commenced to dig and scratch till they 

 had made excavations as large as badger earths ; then a 

 little water trickled in to reward their labours, and they 

 went to work more energetically. In an hour they had 



