INTRODUCTION. ix 



so keen was backed by so much perseverance to shield it 

 from a mere superficial habit of noticing. .Let his adven- 

 tures speak for themselves. 



Amongst the greatest facts recorded here the Geographer 

 will perceive that the Doctor has placed it beyond doubt 

 that Lake Nyassa belongs to a totally distinct system of 

 waters to that which holds Lake Tanganyika, and the rivers 

 running north and west. He was too sagacious to venture 

 the surmise that Tanganyika has a subterranean outlet 

 without having duly weighed the probabilities in the scale 

 with his elaborate observations : the idea gathers force when 

 we remember that in the case of limestone cliffs, water so 

 often succeeds in breaking bounds by boring through the 

 solid rock. No more interesting problem is left to solve, 

 and we shall yet learn whether, through the caverns of 

 "Western Kabogo, this Lake adds its waters to the vast 

 northerly flow of rivers we now read of for the first time, 

 and which are undoubtedly amongst the largest in the world. 



I cannot close these remarks without stating how much 

 obliged I am. to Mr. James Young, F.E.S., of Kelly, for 

 having ensured the presence of the Doctor's men, Chuma 

 and Susi. Ever ready to serve his old friend Livingstone, 

 he took care that they should be at my elbow so long as 

 I required them to help me amidst the pile of MSS. and 

 maps. Their knowledge of the countries they travelled in 

 is most remarkable, and from constantly aiding their master 

 by putting questions to the natives respecting the course 

 of rivers, &c, I found them actual geographers of no mean 

 attainments. In one instance, when in doubt concerning a 

 particular watershed, to my surprise Susi returned a few 

 hours afterwards with a plan of the whole system of rivers 

 in the region under examination, and I found his sketch 

 tally well with the Doctor's map. Known to me previously 

 for years on the Zambesi and Shire it was a pleasure to 

 have them with me for four months. Amongst other good 



