Manual of Military Training Part 152

(3) At station 2 he locates and draws in all details between station 1 and 2, to include about 300 yards on each side of the road.

(4) The traverse is then continued forward as described for 1 and 2.

(5) After some practice of horizontal sketching, as just described, the sketcher will be able to take up contouring in combination. The methods are as described in the paragraph on contouring.

(6) When the traverse runs off the paper as at A, Fig. 10, the following method is followed: Reorient the board so that the road forward will lie across the long dimensions of the paper; draw a meridian parallel to the compa.s.s needle and a.s.sume a point on the new sheet corresponding to the last point (A) plotted on the first sheet.

(7) On completion of the sketch various sections will be pasted together, so that all the meridians are parallel.

=1892. Combined sketching.= Let us suppose that we have the rectangle W, X, Y, Z, Fig. 11, a.s.signed to us to map and that we have been given four sketching parties, and that the locations and elevations of A and B have been previously determined by triangulation and are plotted to scale on our rectangle.

A logical step would be to carefully plot the line a' b', and then the lines c' c" and c" d.

If the area is densely wooded we run "line of level" by using the slope board or clinometer and by taking elevations at points arbitrarily selected. Our lines will look something like this:

[Ill.u.s.tration: Fig. 11]

Each party will be given its rectangle with the traverses sketched in.

They will each then run similar traverses over the other two sides of their area and then fill in. In this manner the whole work is tied up to the original lines.

Another method

The line A B, Fig. 12, is carefully plotted. Each of the four sketching parties has two sketching groups. One group of party No. 1 traverses line a' Y; then the other group of the party traverses the line a" y'. The first group of party of No. 2 accompanies them. The second group of party No. 2 traverses the line c" d, accompanied by the first group of party No. 3; the second group of party No. 3, and the first group of party No. 4 traverse b" z', and the second group of party No. 4 traverses b' Z. When the first group of party No. 1 arrives at Y, it traverses Y y'. The second group of party No. 1, arriving at y', cuts the sheet along traverse and gives the first group of party No. 2 the part which shows their area; and then traverses toward Y from y'. Upon meeting the first group of party No.

1, they join forces and proceed to fill in their area.

[Ill.u.s.tration: Fig. 12]

In the same manner areas W X a' b' are filled in.

[Ill.u.s.tration: Fig. 13]

The method described above is useful in working over country which is densely wooded, and in which a general view cannot be obtained, for example, in mapping jungles.

An additional article of the sketcher's equipment is a holder for his pencils, alidade, eraser, knife, pins, etc. This consists of a series of small pockets sewed on to a piece of canvas about 7 inches by 4 inches. This can be attached to the left breast of the sketcher's coat or shirt by means of two pins. In addition to keeping all of his implements in a handy place the holder prevents the loss of the several articles. Nothing is so discouraging to the sketcher as to look for his pencil, eraser, knife or even alidade and find that he has left it several hundred yards back where he sat down last to sketch in details. By using the holder the sketcher gets into the habit of replacing articles after they are used and consequently always has them with him when needed. These holders ready made can be obtained from the Secretary, Army Service Schools at Fort Leavenworth, Kansas.

In sketching a good quality of paper should always be used as erasures will be frequent. A specially prepared paper that has the appearance of oiled paper can be obtained commercially and is excellent for sketching in damp weather. It has considerable resistance to rain.

Sheets of celluloid prepared for sketching are invaluable in sketching in the rain. These are a part of the equipment of the case of sketching instruments supplied battalions in the regular army. These sheets may be procured at most any dealers.

Points for Beginners to Remember

=1893.= 1. Always keep your pencils sharpened and have an eraser handy. No one but an expert can sketch with a dull pencil.

2. Use hard pencils when learning to sketch--4H to 6H--and go over your work afterwards with a softer pencil--2H.

3. Do not try to put down on your sketch a ma.s.s of small details that are too small to be shown on the scale at which you are sketching. For example, if you are making a sketch on a scale of 3 inches = 1 mile, do not try to show each house in a row of houses; simply indicate that there is a row of houses, by putting down several distinct conventional signs for houses in a row; nor should you try to show every little "cut" through which the road may run. Only use about one sign to the inch of telegraph or telephone lines, for wire fences, etc.

4. When first practicing sketching only plot the route over which you walk, indicating it by a single line. When you can do this with facility, go back over one of these plotted routes and fill in the woods, houses, streams and the other large features.

5. The beginner should sketch the same ground several times over--at least three or four times. Practice alone will make perfect.

6. Always try to compare your finished sketch with an accurate map of the ground, if one is obtainable. Try to practice on ground of which you can obtain a map.

7. Make each course (the distance you go between points where the direction of your route changes) as long as possible.

8. Do not try to contour until you are expert at making a sketch showing all the flat details (roads, streams, woods, houses, etc.).

9. Never try to "sketch in" the contours until you have plotted the stream lines or the direction of the valleys, ravines, etc. The contours are fitted to or sketched around the drainage system; not the drainage system to the contours.

10. Always "size up" ground before you sketch it; that is, take a general view of it, noticing the drainage system (the direction in which the streams flow or ravines run), the prominent hills and ridges, the direction the roads run, etc.

11. Above all things, DON'T FAKE ANY PART OF YOUR MAP.

If the man using your map happens to strike the faked portion, he immediately condemns your whole map as incorrect. Every other part may be highly accurate, but your whole map is discredited because the user strikes the bad part first. You will naturally put little faith in the man who has told you something you know to be untrue. You will always suspect him. So it is with maps. Don't put down anything that you don't know to be correct. If any guess work is to be done, let the man using the map do it,--he knows that he is guessing and will be governed accordingly, but if you do the guessing, he doesn't know where the guessing begins and the accurate work leaves off. Don't fudge. Your name is on the map,--_don't have any questionable work hitched up to your name_.

FOOTNOTES:

[22] Sheets of working scales reading in paces, strides, minutes, etc, at a scale of 3 and 6 inches to the mile can be obtained at little cost from the Secretary, Army Service Schools, Fort Leavenworth, Kansas