318 DAVID LIVINGSTONE. [chap. xv. 



bloodthirstiness sometimes ascribed to it, which, however, 

 Livingstone held to be, at Dahomey for example, purely 

 exceptional. 



Another subject that occupied him was the natural 

 history of the country. He would account for desert 

 tracts like Kalahari by the fact that the east and south- 

 east winds, laden with moisture from the Indian Ocean, 

 get cooled over the coast ranges of mountains, and having 

 discharged their vapour there had no spare moisture to 

 deposit over the regions that for want of it became 

 deserts. The geology of Southern Africa was peculiar ; 

 the geographical series described in books was not to be 

 found here, for, as Sir Roderick Murchison had shown, 

 the great submarine depressions and elevations that had 

 so greatly affected the other continents during the 

 secondary, tertiary, and more recent periods, had not 

 affected Africa. It had preserved its terrestrial condi- 

 tions during a long period, unaffected by any changes 

 save those dependent on atmospheric influences. There 

 was also a peculiarity in prehistoric Africa — it had no 

 stone period ; at least no flint weapons had been found, 

 and the familiarity and skill of the natives with the 

 manufacture of iron seemed to indicate that they had 

 used iron weapons from the first. 



The travellers had got as far as the river Loangwa (of 

 Nyassa), when a halt had to be called. Some of the natives 

 had been ill, and indeed one had died in the comparatively 

 cold climate of the highlands. But nothing would have 

 hindered Livingstone from working his way round the 

 head of the lake if only time had been on his side. But 

 time was inexorably against him ; the orders from Govern- 

 ment were strict. He must get the " Pioneer" down to 

 the sea while the river was in flood. A month or six 

 weeks would have enabled him to finish his researches, 

 but he could not run the risk. It would have been 

 otherwise had he foreseen that when he got to the ship 



