The Science of Fingerprints: Classification and UsesUnited States. Federal Bureau of Investigation
Science
The Science of Fingerprints: Classification and Uses
United States. Federal Bureau of Investigation
Fingerprints
THE SUBSECONDARY CLASSIFICATION (GROUPING OF LOOPS AND WHORLS): In
classifying prints it is necessary to subdivide the secondary groups.
This is accomplished by grouping according to the ridge counts of
loops and the ridge tracings of whorls. The first of the groups filed
in order, which it will be necessary to so subdivide, would ordinarily
be the
1 R
---
1 R
group where no small letters appear. The Federal Bureau of
Investigation, however, has found it necessary to extend this division
to many of the small-letter groups which become cumbersome. The
subsecondary is placed on the classification line just to the right of
the secondary. Ridge counts are translated into small and large,
represented by symbols I and O. The whorl tracings are brought up as
I, M, or O denoting inner, meeting or outer ridge tracings of the
whorl types. Only six fingers may be involved in the subsecondary--numbers
2, 3, 4, 7, 8, and 9.
A ridge count of 1 to 9, inclusive, in the index fingers is brought up
into the subsecondary formula as I. A count of 10 or more is brought
up as O. In the middle fingers a count of from 1 to 10, inclusive, is
brought up as I, and 11 or more is O. In the ring fingers a count of
from 1 to 13 is brought up as I, and 14 or more is O. A loop
subsecondary could appear in the classification formula as
OIO.
---
IIO
Analyzing this example of a subsecondary, one will know that in the
index, middle, and ring fingers of the right hand there are counts of
over 9, under 11, and over 13, while in the left hand there are in the
index, middle, and ring fingers, counts of under 10, under 11, over
13, respectively. The subsecondary classification, therefore, relates
to the groupings of the prints, and no difficulty should be
experienced in ascertaining whether the I and O arrangement in the
subsecondary relates to loops or whorls when analyzing a
classification, because this information can be obtained from the
primary classification. Figure 350 is an example illustrating the
subsecondary in addition to other divisions of the classification
formula.
[Illustration: 350]
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