[ 494 ] 
locity, that, moving uniformly therewith , will in 
the next fecond of time move the length of 2 a feet . 
II. The fpaces run thro ’ /£y falling bodies are propor- 
tional to one another as the fquares of their lajl or 
acquired velocities. 
Thefe two principles are demonflrated by the 
writers on mechanics. 
III. Water forced out of a larger chanel thro ’ one 
or more fmaller pajjages , will have the Jlreams thro ’ 
thofe pajfages contracted in the ratio of 25 to 21. 
This is {hewn in the 36th prop, of the ad book 
of Newton’s Principia. 
IV. In any ftream of watery the velocity is fuch y as 
would be acquired by the fall of a body from a 
height above the furjace of that Jlr earn. 
This is evident from the nature of motion. 
V. The velocities of water thro ’ different pajfages of 
the fame height , are reciprocally proportional to 
their breadths. 
For, at fome time, the water mull: be delivered 
as faft as it comes ; otherwife the bounds would 
be overflowed. 
At that time, the fame quantity, which in any 
time flows thro’ a fedtion in the open chanel, is 
delivered in equal time thro’ the narrower paf- 
fages ; or the momentum in the narrow paflages 
muft be equal to the momentum in the open 
chanel ; or the redtangle under the fedtion of the 
narrow paflages, by their mean velocity, mull be 
equal to the redtangle under the fedtion of the 
open chanel by its mean velocity. 
Therefore 
