on Rivers and Canals. 
This form is that of the excavation of the canals in 
the Low Countiies, and approaches to that of the natural 
beds of rivers inafmuch as they are regular* Here 
ab = 37 Englifh inches, DC— 16 inches; and the length of 
the whole canal, as we faid before, was twenty feet* 
z reprefents the fection of a pulley fixed at one end of 
the canal, upon which palled a fmall cord, one end of 
which was tied to the round rod at the fore part of the 
boat, and at the other end was a piece of lead which 
weighed eight ounces. This ferved for an equable force 
to give an uniform motion to the boat throughout all the 
experiments, x ■ and y are, fections of two other cords 
ftretched parallel to each other at about one inch and a 
half diltance, and reaching from one end of the canal to 
a the- 
