On that particular map contours separated by the distance
on the vertical scale show a slope of 1°; if separated by the distance
they show a 2° slope, etc. A slope of 1° is a rise of 1 foot in 57. To use this scale of slopes, copy it on the edge of a piece of paper just as you did the scale of distances and apply it directly to the map.
You will notice that where the contours lie closest the slope is steepest; where they are farthest apart, the ground is most nearly flat.
It has already been set forth how contours show height and slope; in addition to this they show the shape of the ground, or GROUND FORMS. Each single contour shows the shape at its particular level of the hill or valley it outlines; for instance, the 880 contour about the penitentiary shows that the hill at that level has a shape somewhat like a horse's head. Similarly, every contour on the map gives us the form of the ground at its particular level, and knowing these ground forms for many levels we can form a fair conception of what the whole surface is like.
A round contour like the letter O outlines a round ground feature; a long, narrow one indicates a long, narrow ground feature.
Different hills and depressions have different shapes. A good many of them have one shape at one level and another shape at another level, all of which information will be given you by the contours on the map.