MODELS AND MAPS 



147 



one passes from one to another, the steeper must be the slope 

 along the route taken. The shortest route from one contour to 

 another will generally be that at right angles to the contour, in 

 other words, directly down the hill, along the path that water 

 would flow, or the direction in which hachures would be drawn. 

 To descend a slope easily one would walk obliquely from the 

 higher to the lower contour, and the more obliquely the gentler 

 would be the slope of the path chosen. 



Any two contours are not necessarily parallel throughout 



FIG. 45. Sections along the line A, B, Fig. 45. In X the vertical scale is 

 exaggerated ten times, in Y five times, while in Z there is no exaggeration 

 and horizontal scales are the same, i inch to a mile. 



their whole range. When they approach one another the slope 

 will be steeper than when they are farther apart. If two contours 

 touch, the slope must be a vertical precipice. The profile of the 

 ground should be drawn to scale across contours in several parts 

 of the map, to obtain a notion of the relief of the country. At 

 first perhaps, on an exaggerated vertical scale to bring out the 

 heights and hollows, and, afterwards, on a true scale to get the 

 exact gradients (Fig. 45). A good deal of practice should be 

 devoted to section drawing, in order to attain proficiency in the 



