42 
Central Africa. 
the cost of others, to examine the West Coast, and its 
, adjacent countries ; but the deadly cHmate succeeded, in 
almost every case, in putting an end to the work. Still, 
with every attempt, fresh knowledge was gained, and with 
it, fresh zeal to pursue the quest. Meanwhile, in South 
Africa, missionary explorers were at work, travelling among 
the natives, and examining into their customs, country, 
climate, modes of life, and superstitions. 
Little however was known, until Dr. Livingstone, leaving 
for a time his station at Kolobeng, penetrated into the heart 
of the Kalahari desert, and discovered Lake Ngami. This 
inland sea had been talked of, dreamt of, and delineated 
upon maps, for some long years before its existence and 
its whereabouts were finally settled. Dr. Livingstone had 
been for eight years settled among a tribe of the Bechuanas, 
doing quiet, steady missionary work, and not without 
pleasing results. But in 1849, he arose, in company with 
Messrs. Oswell and Murray, to seek out new fields for the 
exercise of mission effort. He measured the distances 
travelled by a " trocheamer," an instrument which, when 
fastened on the wheel of the wagon, records and registers 
the number of revolutions made. By multiplying the num- 
ber of revolutions with the circumference of the wheel, the 
actual distance travelled on a journey can be at once found. 
He first of all came to the river Zouga, a beautiful stream 
with well-wooded banks. The natives told Livingstone that 
this river came from a country full of rivers and large trees. 
He says, "This was the first confirmation of statements I had 
heard from the Bakwains, who had been with Sebituane, that 
the country beyond was not ^ the large sandy plateau ' of the 
philosophers. The prospect of a highway capable of being 
traversed by boats to an entirely unexplored and very popu- 
lous region, grew from that time forward stronger and stronger 
