66 ON THE UGANDA ROAD part ii 



with some of the stronger porters, had to go on to get water 

 and return with it to the rest. While lying on the ground 

 waiting for the tea, I could not help contrasting my feeble 

 condition with Thomson's rescue of his men, and thinking that 

 African explorers should be made of tougher stuff. 



In the evening a party of Wa-kamba passed with some 

 donkeys, which they were driving to Mombasa to sell. I sent 

 Omari to try to buy one, but the natives demanded the pre- 

 posterous price of half a load of cloth, a load of iron wire, 

 and twenty shaddas (or 2000 strings) of beads. We declined 

 the offer, and charitably wished they might get their price in 

 Mombasa. 



Next morning I was sufficiently better to achieve the march 

 of nine miles in a little over four hours. Camp was pitched 

 before my arrival beside the famous " Ngurunga," or water-holes 

 of Taro. These Ngurunga are a series of holes in sandstone, 

 and they are often the only source of water in this part of the 

 Duruma country. They resemble in form the " pot-holes " 

 formed in boulders and in the rocky beds of mountain streams 

 by the swirling round of a stone resting in a hollow. The 

 Ngurunga have certainly not been formed in this way, and the 

 exact method of their origin has often been discussed. They 

 appear to be due simply to the gradual deepening of slight 

 depressions in the surface of a rock ; water collects in these, 

 and its solvent power is increased by the organic acids derived 

 from the decay of vegetable matter ; the cement between the 

 sand grains is dissolved, and the grains thus loosened are 

 removed by the wind when next the water has evaporated 

 from the hollow. A continual repetition of the process results 

 in the formation of a deep hole. Mr. Joseph Thomson suggests 

 that man aids in their formation by scraping away the sand 

 from the bottom when drawing the water. This, no doubt, has 

 often happened ; but Ngurunga as large and deep as those of 

 Taro occur in districts and in positions where human agency 

 cannot have aided in their erosion. 



At Taro begins the worst march in this stage of the 

 journey. From this point there is often no more water to be 

 had until a pool is reached on the summit of Maungu, thirty- 

 five miles away. The water-hole there is sometimes dry, and 

 then a caravan has to drag on for twelve more weary miles to 



