654 Aft*. mann’s 7 reatife 
from what was found by actual levels made from the 
Lys to Ipres by the French engineers during the time 
that lewis the xivth was mailer of the country, when 
there were propofals for opening a canal from the one to 
the other. 
85. I fhall venture to carry my conjectures Hill far- 
ther, and grounding them upon the principles laid down 
above (N° 78. 79.) I fhall take a general view of the 
elevations of continents along the courfe of the principal 
rivers in the known world. I cannot, however, repeat 
too often, that I give this as a matter of mere conjecture 
and curioiity. It has not been, nor ever will he, in my 
power, or in that of any other particular perfon whatfo- 
ever, to follow the courfes of all the rivers mentioned in 
the enfuing table from their mouths to their fources. 
All that can poffibly be done on this head, is to examine 
the relations of voyagers and geographers concerning 
each river as far as it is known, and to reduce it by that 
means within the compafs of the hydrometrical princi- 
ples laid down in this effay. This is what I have done as 
far as I could ; and therefore, allowing that I make great 
miftakes therein, yet I do not think that I merit much 
blame on that account, as I have done what I was able to 
do. If I am blame- worthy, it is for having launched out 
too 
x 
