Air Fronts: FM 21-25, Elementary Map and Aerial Photograph Reading - CHAPTER 3. What is on a Map?

CHAPTER 3: WHAT'S ON A MAP?

A map is a picture, but it is not a photograph. It is a drawing in ink on paper, and a big difference between a map and a photograph is that the map has signs and symbols instead of photographs of objects. We do the same thing with a football game. For example, below is a diagram, or map of a football play.  It may look like a puzzle but it really isn't, and it is very simple. The "X's" stand for the players on one team, the "O's" stand for the players on the team having the ball, and the lines are the paths the players take in the play. A little study of the diagram, and it is easy to figure out that it illustrates an off-tackle play and shows each man's job.

Figure 14

A map is not much different. On a map there are sign, like the "X's," and "O's," which stand for things on the ground, just as the football symbols stand for the players on the ground.

To read a map, then, we have to learn what these various signs mean. Map signs all look something like the actual thing they stand for. All the signs are simple to draw and are easily recognized. The following few pages show you some of the more common signs which are found on maps. There is reason for their shape, and the pictures with the signs show what they stand for.

Objects on the Land

For example, figure 15 shows a pick crossed with a sledge-hammer, the sign for a mine, such as a coal mine. These two tools are used in mining. Figure 16 shows the sign for a schoolhouse, a black block with a flag flying from it. Most schools have a flag on a flagpole, and the sign gives you the idea of a school.

Let us put these signs on a map and see what they look like. Figure 29 shows you the mapping signs for the things you saw in the photograph of the land in figure 13. Identify the signs shown.

The map, however, is still incomplete. So far, we just have our objects on a flat, blank piece of land, but our land is not like that. It has much more on it than these signs alone can show us.

Figure 15                      Figure 16

The Playing Field-Or the Land Itself

On the gridiron or playing field, we see the players not on a blank area, but against a background marked off with lines. These lines mean something to us, and we can tell where the players are by watching how far they are from these lines, the goal lines, the yard lines and the sidelines. The lines form a pattern which connects the different objects on the field.

Figure 29

Now on the land on which our signs are placed, there are already certain main lines which make a general pattern. These main lines are also shown by signs, and they stand for such important land marks as streams, roads, railroads, and fences. We try to make these lines look different from one another, so that we don't get them confused. At the same time we try to make them look something like what they are.

Following are examples of these main lines and the signs used to show them on a map.

Figure 30                      Figure 31

The heavy line in figure 30 is a primary or firstclass highway; the second line is a secondary highway; these are sometimes red on your map. The two parallel lines mean other surfaced roads, while the dotted lines mean a dirt road. The heavy single dotted line in figure 31 means a trail, while the light dotted line means a footpath or poor pack trail.

Telegraph or telephone wires are often on tall T-shaped poles across the country. The sign is also T-shaped. (See fig. 38.)

In figure 39, the sign is given for a barbed-wire strand fence, not the kind that is a military entanglement. The sign for a smooth-wire fence has "O's" in place of the "X's" like --o--o--o-o--.

Figure 38                      Figure 39

This covers the signs that are most used in mapping. It is important to remember the colors used with these signs. All water, such as swamps, rivers, lakes, and other bodies of water are in blue. Woods and other heavy vegetation are in green. Cuts, fills, and some cultivated fields are in brown. Some good roads may be in red. Other roads, railroads, buildings, bridges, and most man-made things are printed in black.

If we put all these signs on a map and give them some names, we find ourselves with the land picture you see in figure 40. This is more like it! Now we have a pattern of ground against which our other signs begin to make some sense. This map is still a simple one, but it can tell us a good deal about the land.

Figure 40