158 A Brief Sketch of the Geology of the West Indies, 



found dwelling among the reed all round the lake, and on the banks of all the 

 rivers to the north. 



With the periodical flow of the rivers great shoals of fish descend. The 

 people could give no reason for the rise of the water, further than that a chief, 

 who lives in a part of the country in the north, called Mazzekiva, kills a man 

 annually and throws his body into the stream, after which the water begins to 

 flow. 



The sketch which I enclose is intended to convey an idea of the river Zonga 

 and the lake Ngami. The name of the latter is pronounced as if written 

 with the Spanish ii, the g being inserted to shew that the ringing sound is 

 required. The meaning is " Great Water." The latitude, taken by a Sextant 

 on which I can fully depend, was 20° 20' south, at the north-east extremity, 

 where it is joined by the Zonga; longitude about 24° east. We do not, how- 

 ^ever, know it with certainty. We left our waggon near the Batavana town, and 

 rode on horseback about six miles beyond it to the broad part. It gradually 

 widens out into a Firth about 15 miles across, as you go south from the town, 

 and in the south-south-west presents a large horizon of water. It is reported to 

 be about 70 miles in length, bends round to the north-west, and there receives 

 another river similar to the Zonga. The Zonga runs to the north-east. The 

 thorns were so thickly planted near the upper part of this river, that we left 

 all our waggons standing about 180 miles from the lake, except that of Mr Os- 

 well, in which we travelled the remaining distance ; but for this precaution our 

 oxen would have been unable to return. I am now standing at a tribe of 

 Bakurutse, and shall in a day or two re-enter the desert. 



The breadth marked is intended to show the difference between the size of 

 the Zonga, after its junction with the Tamunakle and before it. The farther it 

 runs east, the narrower it becomes. The course is shewn by the arrow-heads. 

 The rivers not seen, but reported by the natives, are put down in dotted lines. 

 The dotted lines running north of the river and lake, shew the probable course 

 of the Tamunakle, and another river which falls into the lake at its north-west 

 extremity. The arrow-heads shew also the direction of its flow. At the part 

 marked by the name of the Chief Mosing it is not more than 50 or 60 yards in 

 breadth, while at 20° 7' it is more than 100, and very deep. 



The principal disease reported to prevail at certain seasons appears, from the 

 account of the symptoms the natives give, to be pneumonia and not fever. 

 When the wind rises to an ordinary breeze, such immense clouds of dust arise 

 from the numerous dried-out lakes called salt-pans, that the whole atmosphere 

 becomes quite yellow, and one cannot distinguish objects more than two miles off. 

 It causes irritation in the eyes, and, as wind prevails almost constantly at certain 

 seasons, this impalpable powder may act as it does among the grinders in Shef- 

 field. We observed cough among them, a complaint almost unknown at Kolo- 

 beng. Musquitoes swarm in summer, and the Banyan and Palmyra give in 

 Bome parts an Indian cast to the scenery. 



(Signed) David Livingston. 



A Brief Sketch of the Geology of the West Indies^ from Dr 

 Davy's Lectures on the Study of Chemistry y drawn up 

 chiefly from the Author^ s own Observations * Communi- 

 cated for the Philosophical Journal. 



In the preceding lecture, I brought under your notice the anta- 

 gonist and compensating, or correcting influences of animal life in 



* Lectures on the Study of Chemistry, in connection with the Atmosphere, 

 the Earth and the Ocean, and Discourses on Agriculture, with Introductions on 

 the present state of the West Indies, and on the Agricultural Societies of Bar- 

 bados. By JoHM Davy, M.D., F.R.8., &c. London, Longmans. 1850. 



