482 Mr. C. Tomlinson on the Weathering of Rocks, 



black cloud which had formed suddenly emptied its contents 

 upon us, pouring down like a torrent, and drenching every- 

 thing with water. The parched earth became in the short 

 time of five minutes covered with ponds. The rain ceased as 

 suddenly as it came on, leaving me both startled and sur- 

 prised at this specimen of an African thunder shower. We 

 passed all at once from the deluged to the arid and dusty 

 ground, the distance of thirty or forty yards being all that 

 intervened between these extremes. Mention had often been 

 made to me, while in Cape Town, of the heavy thunder 

 showers of the interior ; but their sudden violence much 

 exceeded all that I had imagined." * 



Livingstone also describes a storm which overtook his 

 party while travelling by night from Linyanti to Sesheke. 

 He says : — " About ten o'clock it became so pitchy dark that 

 both horses and men were completely blinded. The lightning 

 spread over the sky, forming eight or ten branches at a time, 

 in shape exactly like those of a tree. This, with great 

 volumes of sheet-lightning, enabled us at times to see the 

 whole country. The intervals between the flashes were so 

 decidedly dark as to convey the idea of stone blindness. The 

 horses trembled, cried out, and turned round, as if searching 

 for each other, and every new flash revealed the men taking 

 different directions, laughing, and stumbling against each 

 other. The thunder was of that tremendously loud kind only 

 to be heard in tropical countries, and which my friends from 

 India have assured me is louder in Africa than any they have 

 heard elsewhere. Then came a pelting rain, which completed 

 our confusion."" f 



This excellent observer also describes some remarkable 

 effects of atmospheric electricity on the borders of the Kala- 

 hari desert. During the dry seasons which succeed the 

 winter and precede the rains, a hot wind occasionally blows 

 over the desert from north to south. It seldom blows for 

 more than three days at a time, and it has somewhat the 

 feeling of coming from an oven. " This wind is in such an 

 electric state that a bunch of ostrich feathers held a few 

 seconds against it becomes as strongly charged as if attached 

 to a powerful electrical machine, and clasps the advancing 

 hand with a sharp crackling sound. When this hot wind is 

 blowing, and even at other times, the peculiarly strong elec- 

 trical state of the air causes the movement of a native in 

 his kaross to produce therein a stream of small sparks. The 



* ' Travels in the Interior of Southern Africa/ by W. J. Burchell. 

 2 vols. 4to. (1822-24.) 



t Missionary Travels and Researches in South Africa ; 8vo, 1857. 



