ON THE FLOW OF WATER IN PIPES, CONDUITS, ETC. 185 



Class 9. 



Cast iron and wrought iron mains in use several years, ordinary 

 service pipe mains with some valves, bends, vertical curves, not perfectly 

 clean, but slight deposit uniformly distributed. Channels and conduits 

 of ordinary brickwork of good construction. Flumes of sawed boards of 

 ordinary construction. Channels of uniform section, straight alignment 

 and grade, of the best smooth ashlar masonry. 



Class 10. 



Old iron pipes not clean, slightly incrusted, with some deposit uniform- 

 ly distributed. Small flumes and channels whose roughness is like that 

 of stout coarse canvas, with r = .035. Channels constructed of good 

 ashlar masonry. 



Class 11. 



Riveted sheet iron pipes and conduits of various construction, coated 

 with asphalt, clean and new with, diameters from 2.5 to 4 feet. Channels 

 of ordinarj' ashlar masonry. 



Class 12. 



Riveted sheet iron pipe in ordinary service, coating in fair condition, 

 or but slightly damaged. Channels of roughness equivalent to boards 

 with laths lx% inches nailed crosswise on bottom and sides % inches apart. 



Class 13. 



Old riveted sheet iron pipe in fair condition. Ashlar masonry not 

 smooth, with some deposits, but in fair order. Channels whose roughness 

 is of the character of pebbles % to Ys of an inch held in place with cement. 

 Channels of dry rubble of the very best construction. Channels of best dry 

 rubble side walls and clay bottom in good order. 



Class 14. 



Unclean old iron pipes, somewhat foul, but fine and uniformly dis- 

 tributed deposits. Ordinary dry rubble masonry channels of good con- 

 struction, with rubble bottom or good clay bed. 



