TOPOGRAPHIC MAPS 



219 



FIG. 115. A CONE REPRESENTED BY CONTOUR LINES 



The upper figure is a profile of a cone cut into 3 horizon- 

 tal sections, as described in 239. The lower figure represents 

 by its outer circle the base of the cone; the second circle 

 (1) represents the base of the portion of the cone above 1, the 

 lower section being removed. 1. What circle would represent 

 the journey of an insect around the base of the cone? 2. 

 Around the cone at the point 2? 3. If the insect crawled to 

 the summit, where would it be in respect to the circular figure? 



