﻿Smithsonian 
  Report 
  1922. 
  — 
  Newell. 
  

  

  Plate 
  10. 
  

  

  I. 
  Excavation 
  by 
  Drag 
  Line. 
  

  

  2. 
  Cleaning 
  an 
  Irrigating 
  Ditch 
  while 
  in 
  Operation. 
  

  

  