Part 20 (2/2)

It can be ascertained that the pattern in figure 376 is a loop, but an accurate ridge count cannot be obtained because the left delta does not appear. The approximate ridge count of this loop is 14 to 16.

This approximation is sufficient for a fingerprint expert to place this loop in the ”O” group of any finger of the subsecondary. The correct ridge count of this loop is 19, and it appears in ill.u.s.tration 377. The approximate ridge count is not sufficient to place this print properly in the large files of the FBI because in certain general complete cla.s.sification formulas the accurate ridge count is needed to obtain an extension. These extensions use a smaller grouping of ridge counts to form a valuation table, and in this way, differ from the larger grouping of ridge counts which form the basis of the subsecondary cla.s.sification. These extensions are called the second subsecondary and the special loop extension and are outlined in chapter VI.

[Ill.u.s.tration: 374. Improper.]

[Ill.u.s.tration: 375. Proper.]

[Ill.u.s.tration: 376. Improper.]

[Ill.u.s.tration: 377. Proper.]

There are two additional points which ill.u.s.trate the FBI's need for the delta, ridges, and core to show clearly in loops. The first point is set forth: the ridge count of the loop may be needed to obtain the key cla.s.sification. The key cla.s.sification is an actual ridge count, and no valuation table is used to obtain a subdivision. The key cla.s.sification is used as an integral part of the fingerprint filing system. The second point is as follows: the ridge count may be needed to obtain the final cla.s.sification. The final cla.s.sification is an actual ridge count, and no valuation table is used to obtain a subdivision. The final cla.s.sification is used as an integral part of the fingerprint filing system.

The following are just a few examples to ill.u.s.trate the completeness of the cla.s.sification formula used in the FBI fingerprint file:

12 M 9 R OIO 11

S 1 R IOI

Key Major Primary Secondary Subsecondary Final

6 17 aW IIO 9

1 U OII Key Primary Small letter Subsecondary Final Secondary

8 S 1 Ua II 6 S 1 U III

Key Major Primary Small letter (Subsecondary Final Secondary Extension)

SML (Second SML Subsecondary) 5 0 5 U IOO 14

I 17 U IOO

Key Major Primary Secondary Subsecondary Final

245 (Special Loop 332 Extension) 14 M 1 U IOO 16

S 1 U OII

Key Major Primary Secondary Subsecondary Final

15 I 29 W IOO 19

I 28 W OOI

Key Major Primary Secondary Subsecondary Final

These several examples should help to ill.u.s.trate the FBI's extended cla.s.sification formulas for cla.s.sifying and filing fingerprints. The larger collection of fingerprints must of necessity call for a more detailed a.n.a.lysis of all fingerprint characteristic details. The closer examination to obtain further fingerprint subdivisions is dependent on ten legible inked impressions.

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