eC 
roa 
296 M. P. S. Girard on Navigable Canais. 
Itis evident that the volume of water u’,+-u’,, gained by 
“se levels B, and B,, has been taken from the following lev- 
© Butt the volume of water ‘gained by the level B,=Bw’,, 
that gained by the level 
‘he level B,, will therefore have undergone a depres- 
sion 
_Bw +B Ww’, 
B, 
Consequently the fall of the lock E,,, will have become 
( 
wu, ,/u a : 
a alt 
The descent of the boat through this lock will occasion & 
neering rise of its level : 
Ss S (Bw +B,’ uw) 
Be i Fae Bi 
ct we have : 
: (Bw +B.u,) 
ie? ar 8. 
Therefore 
5 Ss ; (Bu +B,u',) 
“0B, +S Bas oe) (B,,+5S) ° 
~ Inthe same manner we shall find 
Ay D (Bw +B,’ ,+B,,u le 
69 (Bw-+S) 
And, generally 
Ss “ ‘ee wu +B, uv’, +B, Pig haces 
*™)=Bo +S" =2/n))— (B,.) +8) 
ss eS 1) 
If we suppose ag extent and rise of water in each of t 
levels which precedes the last B (,,), to be prer ager 
the above equation expresses, as we see, the general rele 
eae are the indeterminate aete B (n)o U () 
and a’ 
hiker te first boat shall have passed through all the ler 
els B, B, B,,, the falls of the locks E,E,, Ew Ev 
