3 2o MY LIFE 



information as to how he estimated his distances. In a river 

 flowing through a densely wooded country, with nowhere 

 more than a few hundred yards of clear ground on its banks, 

 with a very crooked and twisted course, and with a current 

 varying from being scarcely perceptible to such rapidity that 

 a whole crew of paddlers can hardly make way against it, it 

 is exceedingly difficult to ascertain the rate of motion in miles 

 per hour. 



Canoes of different sizes do not travel at very different 

 rates, when each has its complement of men, and I had 

 taken many opportunities to ascertain this rate in still water. 

 Then, by noting the time occupied for a particular distance, 

 say between two of the cataracts, both during the ascent and 

 descent of the river, the mean of the two would be the time 

 if there were no current. Making a little allowance for the 

 load in the canoe, the number or the quality of the rowers, 

 etc., this time multiplied by. the rate of travel in still water 

 would give the distance. This was the plan I adopted in 

 making my map of the Uaupes. It is, of course, a mere 

 approximation, and liable to considerable errors, but I did 

 not think they would lead to such a large difference of dis- 

 tance as that between the Count's map and my own. We 

 have no doubt erred in opposite directions, and the truth lies 

 somewhere between us; but until some traveller takes a good 

 chronometer up the river with a sextant for determining local 

 time, or a telescope of sufficient size to observe eclipses of 

 Jupiter's satellites, the true length of the river will not be 

 settled. 



In one of the latest atlases, " The Twentieth Century Citi- 

 zens' Atlas," by Bartholomew, the position of the Jurupari 

 fall is 62 per cent, further from the mouth of the river than 

 on Stradelli's map, which seems to show either that some 

 other traveller has determined the longitude, or that they con- 

 sider my distances more correct than his. 



Another traveller, Dr. T. Koch, only last year (1904) 

 ascended the Uaupes to beyond the Jurupari fall, and also 

 went up the Codiary branch where he reached an elevated 

 plateau. But it is not stated whether he made any observa- 



