or ink-stamp pads. These inks are either too light or too thin, and they take too long to dry.

The roller is used to spread a thin film of printer's ink evenly on the inking plate. A roller of the type used by printers to make galley proofs is very satisfactory, and it may be obtained at any printer's supply house. It should be about 6 inches in length and 2 inches in diameter.

A satisfactory inking plate can be made by inlaying a piece of plate glass about 14 inches long, 6 inches wide, and one-fourth of an inch thick in a piece of wood; the wood is not necessary, but it will help to protect the glass against breakage. The plate should be located at elbow height, to make easier the task of applying ink evenly to the entire inner surface of a man's fingers. In order to hold out of the way fingers not being inked, the inking plate should be placed near the edge of the table. An inking plate so located prevents accidental strain in inking the fingers, and it enables you to make uniform impressions.

Figure 3-2 shows the necessity for a fully-rolled impression. A and b are impressions of the same finger. A, being fully and properly rolled, shows the pattern to be what the classifier calls an accidental whorl; while b,

which is only partly rolled, shows only enough of the pattern to lead the classifier to believe it is a tented arch. The larger surface of the fully-rolled impression not only allows accurate classification but it also gives more points for comparison.

When ready to take fingerprints, place a small daub of ink on the inking plate and roll it thoroughly until a thin, even film covers the entire surface. Place the person whose prints are to be taken directly in front of the plate and at a forearm's length. To make a rolled impression, place one side of the finger on the inking plate; then roll it to the other side, facing the opposite direction. You must see that each finger is inked from its tip to below the first joint. Press the finger lightly on the card, and roll it carefully. This method of fingerprinting gives a clear rolled impression of the finger. Ink and print each finger separately, and, to avoid the danger of smudging, wipe the ink from the finger directly after you have made the impression. Begin with the thumb, and then print the index, middle, ring, and little fingers, in order.

Making Rolled Impressions

Because of the arrangement of the bones in the forearm, the thumb should always be rolled towards the center of the man's body; the fingers should be rolled away from the center of the body. Rolling the fingers and thumbs in this manner so relieves them from strain that they are relaxed at the end of the roll. This procedure enables you to lift a finger or the thumb from the card with ease, without danger of the card's slipping (blurring the print).

Figures 3-3 and 3-4 show the proper method of holding a finger for inking, and for printing a rolled impression.

Light pressure is used in making rolled impressions. Practice making them, and determine through experience

just how much pressure is required. Furthermore, caution the man whose prints are being taken to relax. Request that he refrain from trying to help you by exerting any pressure on the ink plate, as such assistance prevents your applying the proper amount of pressure. You can usually get him to relax by requesting that he look at the opposite wall, rather than at his hands.

Plain Impressions

To make plain impressions, press lightly on the inking plate all the fingers of the right hand. Then press them in the space provided on the lower right hand corner of the card. After you complete this operation with the left hand, ink and print (without rolling) the thumbs of both hands. Figure 3-5 shows the correct method of taking plain impressions.

Fingerprinting appears to be a very simple process, but at times the quality of prints submitted to the FBI is so poor that identification is delayed, or is even impossible.

Mistakes

Poor impressions are usually caused by one or more of the following mistakes:

1. The use of poor, thin, or colored ink, resulting in impressions too light or too faint, or with obliterated ridges. The best results are obtained by using heavy, black printer's ink. This is a paste, and it should not be thinned before using. It dries quickly and does not blur or smear in handling.

2. Failure to clean the person's fingers thoroughly before inking. If foreign matter (or perspiration) adheres to the fingers, false markings appear and characteristics disappear.. Carbon tetrachloride is very good for cleaning the fingers; windshield cleaner, alcohol, benzine, and gasoline are also good cleansing agents. In warm weather all perspiration must be wiped from the fingers before inking. 3. Failure to clean the inking apparatus after each

use. The same liquids described above may be used for removing ink.

4. Failure to roll the fingers fully from one side to the other, and failure to ink the entire finger area from the tip to below the first joint. Such failures result in important areas not being shown on the print. The impression should show the whole finger, from the first joint to the tip, and from one side to the other side.

5. The use of too much ink, resulting in the obliteration of ridges. Just a touch of the tube of ink to the plate is sufficient for several sets of prints. It must be spread with a roller into a thin, even film. 6. The use of too little ink, resulting in ridge impres

sions too light and too faint for tracing or counting. 7. Slipping or twisting of the fingers, causing smears, blurs, and false patterns. Hold the fingers lightly, using little pressure, and caution the man against trying to help. laxed.

Ask him to remain quiet and re