[bovev] 



BACKWATER PRODUCED BY WEIRS 

 12th May, 1903. 



131 



Width of vvinp: dam 



Depth at point of dis 

 charge 



Increment of depth at 

 point of discharge 



Increment of depth at 

 4' 2" from point of dis- 

 charge . 



Increment of depth at 

 19' from point of dis 

 charge 



Per cent, change of ve 

 locity 



24 



100 



•35 



•26075 



•09035 



18-8 



12th May, 1903. 



Width of wing dam 



Depth at point of dis- 

 charge 



Increment of depth at 

 point of discharge 



Increment of depth at 

 4' 2" from point of dis- 

 charge 



Increment of depth at 

 19' from point of dis- 

 charge 



Per cent, change of ve- 

 locity 



1467 



0298 



18 

 1.82 



•55 



• 456555 



•2345 

 5-6 



24 

 2 15 



•68405 



•41345 



8 



For example, the sketch shows approximately the bottom of the 



river between the Chaudière Falls (at Booth's Milk) and the Little 

 Cliaiidiere Falls. B D is a horizontal line. As soon as the surface of 

 the water at the Chaudière Falls rises above D, backwater will be pro- 

 duced at B. Before the dam was built at A the depth of water at D 

 was between 9 and 10 feet, when the water surface at D was on a level 

 vnth B the foot of the O'Connor dam. 



The experiments then show that the introduction of a dam at A, 

 150 ft. wide, produces more than 10 ins. of backwater at B, which 



