C 498 ] 
So that the water-way will be reduced to 1967 
feet. 
Now b = 926 j c — 1967; ^ — 3^ > 4^ — 
&b355> 6 - 
Then 2 L» ,= 231*2 = 5,60532 
2If 4I3O 
. And 5,6o532 |2 = 314196; and 3.14.196 — 1 = 
3 «= 4^6 = |ff 
I. 
Alfo vv 
51 2 - ^ 1 . And — - 361 
6 ' 36 * 4 a 3 t> X 64^3596 
= 0,1 5581. 
Then 30,4196 x 0,1 5-581 = 4,739 feet, the fall, 
fought after. 
By the mod exadt obfervations made about the 
year 1736, the meafure of the fall was 4 feet 9 
inches. 
Example II. For Wejlminfier -Bridge 
Altho’ the breadth of the river at Weftminfter- 
bridge is 1220 feet ; yet, at the time of the greatefh 
fall, there is water thro’ only the thirteen large arches, 
which amount to 820 feet : to which adding the 
breadth of the twelve intermediate piers, equal to 
1 74 feet, gives 994 for the breadth of the river at 
that time : and the velocity of the water juft above 
bridge (from many experiments) is not greater than 
24 feet per lecond. 
Here b = 994 ; £ = 820; v = 2 * j 4*7 = 64,3596 
Now — 
21 e 
24850 
17220 
i> 443 - 
And 
