GENERAL OBSERVATIONS, 339 
where the water is deepest. The current however in the 
mid-stream must have been greater than it is generally 
stated ; as it is admitted by the surveyor, that, with every 
desire to complete the survey of the river in all its parts, 
he found it impossible, even with the aid of Massey’s 
machine, to get the soundings in the mid-channel, 
though the river was, at that time, in its lowest state. 
Maxwell’s chart was found to be incorrect in many re- 
specls, especially as to distances, which are generally 
too great. With regard to the flat islands formed by 
alluvial earth, and overgrown with the mangrove and the 
papyrus, constant changes are taking place, some gra- 
dually forming and encreasing in size, while others are 
wholly or partially swept by the current into the ocean. 
The mistaken notion, which seems to have originated 
with the Portuguese, that the tide could make no impres- 
sion on the current of the Zaire, is but partially true; 
this mistake is now corrected by frequent observations of 
the tide forcing the reflux of the stream very perceptibly 
as high up as the commencement of the narrows at Son- 
die, where the rise and fall amounted from twelve to sixteen 
inches ; but though it caused the water to be dammed up, 
and a counter-current on one or both sides, yet, strictly 
speaking, the current in the middle of the river was never 
overcome by the tide. 
The distance at which the narrows commence is about 140 
English miles from the mouth of the river at Point Padron, 
and they continue as far as Inga, or forty miles nearly ; the 
_ width of the river being generally not more than from 
