To prevent misapprehension it may be necessary to state that the 

 expression vena contracta has been used (improperly) in this paper, to 

 denote the least section of the contracted vein. 



In the note of page 10, an erroneous statement has been made, 

 which I beg leave to correct. Euler has given the equation applicable 

 to the uniform motion of incompressible fluids in the Memoirs of the 

 Acad, of Berlin 1755. Mr. Moseley has been the first, I believe, to 

 observe that a like equation is true of compressible fluids. 



