Bui. 852, U. S. Dept. of Agriculture 



PLATE I. 



Fig. I. — Excessive Roughness Ob- 

 tained with Poorly Made Wood 

 Forms. 



Ellipsed outlet to 60-inch round siphon pipe. 



Fig. 2. — Flow Obstructed with 

 Accretion of Sand and Gravel, 

 Cemented by Carbonate of 

 Lime. 



Note "mortar squeeze" at the joints; typical 

 of very old lines. View taken after 14 years' 

 use. 



Fig. 3. — Pipe Unit for Victoria Aqueduct, British Columbia. 



Exceeding smoothness obtained with oiled steel forms and omission of any wash coat. 



