Illustrations xv 



PAGE 



Junction of a Branch Ditch with a Lined 

 Ditch 143 



Burning Grass from the Side of a Ditch; 

 Crude Oil Used as Fuel . . . 144 



Condition of the Ditch Two Months after 

 Burning. ...... 146 



Ditch Cleared by Hand Labor, Showing 

 Condition Two Months after Removing 

 Grass 148 



A Gate to Impound Water for Flushing a 

 Ditch: Empire ..... 150 



Removal and Destruction of Larvae and 

 Matted Alg^e in a Ditch by Flushing: 

 Empire ....... 150 



A Simple Form of Oil Drip . . . 158 



The Flat Lampwick Drip for Heavy Oils . 160 



Oil Drip Applied to a Hillside Stream . 162 



Oiling Obstructed Streams on Cut-Over 

 Lands ....... 164 



B rush in Valley of Pedro Miguel River . 164 



Application of Larvacide or Oil by Knap- 

 sack Sprayer: Miraflores . .166 



Spray Nozzles 167 



Field Supply Tank 168 



Oil-Cart for Applying Oil to Roadside 

 Ditches 168 



