INDEX TO ILLUSTRATIONS 



xv 



United States (continued) : Page 



Sewerage Commission on a tour of inspection 



through the sewer: Baltimore 370 



Sheathing of a deep trench in Baltimore sew- 

 erage system 367 



South side of Carrizo Mountain, in the Colo- 

 rado Desert 697 



The lake that disappeared: Near l£l Toro 



Indian Reservation 684 



Upper end of Colorado Desert before the in- 

 flow of Colorado River 688 



Using the brush drag to obliterate mouse 



holes 482 



"View along the edge of the upper mesa of 



Tsankawi, New Mexico 809 



United States (continued) : Page 

 View in one of the great siphons of the Balti- 

 more sewerage system 366 



View of Otowi, New Mexico, showing strange 



tent rocks 815 



View of Tacoma's narbor, Washington 655 



Views of original boundary stones of District 



of Columbia 358-359 



View of the outfall sewer, showing method of 



reinforcement: Baltimore 371 



Views of the steep slopes: Wheeler National 



Park, Colorado 840 



Water line that marks the shore of the lake 



that once occupied Colorado Desert... «. 682 

 Yakima Indian, a large land owner on the 



Yakima Reservation 653 



