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Articles from The Science Of Fingerprints

Establishment Of A Local Fingerprint Identification Bureau

The Use Of The Fingerprint Camera

Classification Of Scarred Patterns

Latent Fingerprints

Death Notices

Central Pocket Loop

Interpretation

Fingerprinting Equipment

Questionable Patterns

Temporary Disabilities


The Classification Formula





At this point it is necessary to mention that when prints are
classified, markings are indicated at the bottom of each finger block
to reflect the type. The following symbols are used:

- Under the index fingers the appropriate capital letters
should be placed for every pattern except the ulnar loop.

- Under all other fingers, the appropriate small letter
should be placed for every pattern except the ulnar loop and
the whorl as follows:

Arch a
Tented Arch t
Radial Loop r

- Ulnar loops in any finger are designated by a diagonal
line slanting in the direction of the loop.

- Whorls in any finger are designated by the letter W. The
classification formula may be composed of the following
divisions:

1. Primary
2. Secondary
3. Subsecondary
4. Major
5. Final
6. Key

The positions in the classification line for these divisions when
completely applied are as illustrated:

Key Major Primary Secondary Subsecondary Final
--------------------------------------------------------------------------
Divisions Classification Classification Classification

20 M 1 U IOI 10
--------------------------------------------------------------------------
L 1 U IOI

Second subsecondary
classification
Key Major Primary Secondary Subsecondary Final
--------------------------------------------------------------------------
Divisions Classification Classification Classification

SLM
---
MMS
4 O 5 U IOI 10
--------------------------------------------------------------------------
I 17 U IOI

THE PRIMARY CLASSIFICATION: For the purpose of obtaining the primary
classification, numerical values are assigned to each of the ten
finger spaces as shown in figure 347. Wherever a whorl appears it
assumes the value of the space in which it is found. Spaces in which
types of patterns other than whorls are present are disregarded in
computing the primary.

The values are assigned as follows:

Fingers No. 1 and No. 2 16

Fingers No. 3 and No. 4 8

Fingers No. 5 and No. 6 4

Fingers No. 7 and No. 8 2

Fingers No. 9 and No. 10 1



LEAVE THIS SPACE BLANK SEX
+--------------+
FBI No. RACE
+--------------+ LAST NAME FIRST NAME MIDDLE NAME
---------------------------------------------------------------+----------
SIGNATURE OF PERSON CONTRIBUTOR ALIASES HT. WT.
FINGERPRINTED AND ADDRESS (IN.)

DATE OF
----------------------------- BIRTH
RESIDENCE OF PERSON
FINGERPRINTED HAIR EYES

--------------------------------------------------------------------------
OCCUPATION ARREST NUMBERLEAVE THIS SPACE BLANK

------------------------------------------
SCARS AND MARKS PLACE OF
BIRTH 29
-------------CLASS
-----------------------------CITIZENSHIP 19
SIGNATURE OF OFFICIAL DATE
TAKING FINGERPRINTS CHECK IF
NO CRIMINALREF.
RECORD IS
DESIRED
---------------------------------------------------------------------------
1. RIGHT THUMB2. RIGHT INDEX3. RIGHT 4. RIGHT RING 5. RIGHT LITTLE
MIDDLE
N 16 N 8
[Illustration][Illustration][Illustration][Illustration][Illustration]
D 16 D 8 D 4
---------------------------------------------------------------------------
W W W
---------------------------------------------------------------------------
1. LEFT THUMB 2. LEFT INDEX 3. LEFT 4. LEFT RING 5. LEFT LITTLE
N 4 MIDDLE
N 2 N 1
[Illustration][Illustration][Illustration][Illustration][Illustration]
D 2 D 1
---------------------------------------------------------------------------
W W / / /
---------------------------------------------------------------------------

In figure 347, it will be observed that the odd fingers (Nos. 1, 3, 5,
7, 9) contain the letter D, and the even fingers (Nos. 2, 4, 6, 8, 10)
contain the letter N. The D indicates that the values of these fingers
relate to the denominator, the N that they relate to the numerator.
The summation of the numerical values of the whorl type patterns, if
any, appearing in fingers 1, 3, 5, 7, 9, plus one, is the denominator
of the primary. The summation of the values of the whorls, if any, in
fingers 2, 4, 6, 8, 10, plus one, is the numerator of the primary.
Where no whorl appears in a set of impressions, the primary,
therefore, would be 1 over 1. The 1 that is assigned to the numerator
and the denominator when no whorls appear is also added, for
consistency, to the value of the whorls when they do appear. It will
be understood why it was originally assigned to the no-whorl group
when it is considered how easily a zero might be confused with an O,
which is the symbol used for an outer whorl tracing.

To obtain the primary for the prints in figure 347, the number of
whorls appearing in the odd fingers is ascertained to be 2. Their
positions are noted (1 in No. 1 and 1 in No. 7) and the values
assigned to whorls appearing in those fingers are added together (16
plus 2 = 18). To this sum the arbitrary 1 is added, giving us the
total of 19, which constitutes the denominator for this set of prints.
To get the numerator, it is ascertained that there are 3 whorls
appearing in the even fingers (2, 4 and 6), the values of which are
added together (16 plus 8 plus 4 = 28). To this sum the 1 is added,
giving a numerator of 29, and a complete primary of 29 over 19.

By the word whorl is meant all types of whorls, including plain
whorls, central pocket loops, double loops and accidentals. The
tracing of the whorl does not enter into the determination of the
primary.

The method of obtaining the primary can probably be shown best by
illustrations. For example, assume that there is a whorl in the right
index finger only. The value of a whorl in this finger is 16. When 1
over 1 is added the resulting primary is 17 over 1. If a whorl appears
in the right thumb and right index finger, the value is 16 over 16
plus 1 over 1 giving a primary of 17 over 17. If whorls appear in both
index fingers, the value is 16 over 2 plus 1 over 1 giving a primary
of 17 over 3. When whorls appear in both thumbs and both index
fingers, the primary is 21 over 19 and is obtained by the addition 16
plus 4 plus 1 over 16 plus 2 plus 1. If whorls appear in all 10
fingers, the primary is 32 over 32 (16 plus 8 plus 4 plus 2 plus 1
plus 1 over 16 plus 8 plus 4 plus 2 plus 1 plus 1). It will be noted
that the primary classifications extend from 1 over 1 in the no-whorl
group to 32 over 32 in the all-whorl group, providing 1,024 possible
combinations. This does not mean that there are 1,024 even
subdivisions of prints according to these primaries. Just as there is
a preponderance of loops when the types of patterns are considered,
there is also a preponderance of certain primaries, notably: the 1
over 1 primary, or no-whorl group; the 17 denominator; the 19
denominator; the 28 denominator, of which the 31 over 28 group is the
largest; and the 32 denominator, including 2 large primary groups
namely, 31 over 32 and 32 over 32. As a matter of fact, the 1 over 1
group, as a whole, contains over 25 percent of the total number of
prints filed in the FBI. On the other hand, there are a number of
primaries which rarely appear. It follows, therefore, that when a
print is classified in one of these larger groups it is necessary to
complete the classification to a greater extent than is necessary in
the more unusual primaries, so that the group to be searched is small
enough for convenience.

In connection with the counting of whorl values to obtain the primary,
it might be noted that when the whorls outnumber the other patterns
more speed can be achieved by counting those patterns and subtracting
rather than by adding the whorls. This procedure should not be
followed until enough experience is acquired so that it may be noted
at a glance where whorls are not present.

The experienced classifier can tell in what fingers whorls are present
by a glance at a primary classification. For example, a primary of 5
over 17 could mean that there are whorls in the thumbs only.



LEAVE THIS SPACE BLANK SEX
+--------------+
FBI No. RACE
+--------------+ LAST NAME FIRST NAME MIDDLE NAME
---------------------------------------------------------------+----------
SIGNATURE OF PERSON CONTRIBUTOR ALIASES HT. WT.
FINGERPRINTED AND ADDRESS (IN.)

DATE OF
----------------------------- BIRTH
RESIDENCE OF PERSON
FINGERPRINTED HAIR EYES

--------------------------------------------------------------------------
OCCUPATION ARREST NUMBERLEAVE THIS SPACE BLANK

------------------------------------------
SCARS AND MARKS PLACE OF
BIRTH 9 R
-------------CLASS
-----------------------------CITIZENSHIP 2 R
SIGNATURE OF OFFICIAL DATE
TAKING FINGERPRINTS CHECK IF
NO CRIMINALREF.
RECORD IS
DESIRED
---------------------------------------------------------------------------
1. RIGHT THUMB2. RIGHT INDEX3. RIGHT 4. RIGHT RING 5. RIGHT LITTLE
MIDDLE

[Illustration][Illustration][Illustration][Illustration][Illustration]

---------------------------------------------------------------------------
R W
---------------------------------------------------------------------------
1. LEFT THUMB 2. LEFT INDEX 3. LEFT M4. LEFT RING 5. LEFT LITTLE
18 10 MIDDLE I I 13

[Illustration][Illustration][Illustration][Illustration][Illustration]

---------------------------------------------------------------------------
/ R / W /
---------------------------------------------------------------------------

THE SECONDARY CLASSIFICATION: After the primary classification, the
fingerprints are subdivided further by using a secondary
classification. Before going into detail, it should be noted that
after the primary is obtained the entire remaining portion of the
classification formula is based upon the arrangement of the
impressions appearing in the right hand as the numerator over the
impressions appearing in the left hand as the denominator. The
arrangement of the even over the uneven fingers is discarded after the
primary is obtained. The secondary classification appears just to the
right of the fractional numerals which represent the primary. It is
shown in the formula by capital letters representing the basic types
of patterns appearing in the index fingers of each hand, that of the
right hand being the numerator and that of the left hand being the
denominator (fig. 348). There are five basic types of patterns which
can appear.

1. Arch A
2. Tented Arch T
3. Radial Loop R
4. Ulnar Loop U
5. Whorl W



LEAVE THIS SPACE BLANK SEX
+--------------+
FBI No. RACE
+--------------+ LAST NAME FIRST NAME MIDDLE NAME
---------------------------------------------------------------+----------
SIGNATURE OF PERSON CONTRIBUTOR ALIASES HT. WT.
FINGERPRINTED AND ADDRESS (IN.)

DATE OF
----------------------------- BIRTH
RESIDENCE OF PERSON
FINGERPRINTED HAIR EYES

--------------------------------------------------------------------------
OCCUPATION ARREST NUMBERLEAVE THIS SPACE BLANK

------------------------------------------
SCARS AND MARKS PLACE OF
BIRTH 1 R
-------------CLASS
-----------------------------CITIZENSHIP 1 aU
SIGNATURE OF OFFICIAL DATE
TAKING FINGERPRINTS CHECK IF
NO CRIMINALREF.
RECORD IS
DESIRED
---------------------------------------------------------------------------
1. RIGHT THUMB2. RIGHT INDEX3. RIGHT 4. RIGHT RING 5. RIGHT LITTLE
MIDDLE

[Illustration][Illustration][Illustration][Illustration][Illustration]

---------------------------------------------------------------------------
R
---------------------------------------------------------------------------
1. LEFT THUMB 2. LEFT INDEX 3. LEFT M4. LEFT RING 5. LEFT LITTLE
18 10 MIDDLE I I 13

[Illustration][Illustration][Illustration][Illustration][Illustration]

---------------------------------------------------------------------------
a / / / /
---------------------------------------------------------------------------

SECONDARY CLASSIFICATION (SMALL-LETTER GROUP): Prints with an arch or
tented arch in any finger or a radial loop in any except the index
fingers constitute the small-letter group of the secondary
classification. Such small letters, with the exception of those
appearing in the index fingers, are brought up into the classification
formula in their proper relative positions immediately adjacent to the
index fingers (fig. 349). A dash is used to indicate the absence of
each small letter between the index fingers and another small letter
or between two small letters, as

1 aUa-t 1 aU-t.
------- and ------
1 R-a 1 U-a

Thus, if a radial loop appears in the right thumb, the small letter
r would be brought up in the numerator column of the classification
formula and placed just to the left of the capital letter representing
the index finger. Similarly, if an arch or tented arch or a radial
loop would appear in the middle, ring, or little finger of the hand,
the small letter representing such a pattern would be placed on the
classification line to the right of the secondary in the numerator
column if the letter is present in the right hand, and in the
denominator column if in the left hand. When two or more small letters
of the same type occur immediately adjacent to each other, they are
indicated thus:

1 rU-2a 1 aTa-a.
------- and -------
1 tU3a 1 tA2at

The small-letter groups are of vital importance to the classification
system, as they are of relatively infrequent occurrence, constituting
approximately 7 to 10 percent of all patterns. Generally speaking,
since these patterns are of such rare occurrence, their very presence
often enables the classifier to dispense with the usual subsecondary
classification and the major division which in the majority of cases
are used in the larger groups.

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.



LEAVE THIS SPACE BLANK SEX
+--------------+
FBI No. RACE
+--------------+ LAST NAME FIRST NAME MIDDLE NAME
---------------------------------------------------------------+----------
SIGNATURE OF PERSON CONTRIBUTOR ALIASES HT. WT.
FINGERPRINTED AND ADDRESS (IN.)

DATE OF
----------------------------- BIRTH
RESIDENCE OF PERSON
FINGERPRINTED HAIR EYES

--------------------------------------------------------------------------
OCCUPATION ARREST NUMBERLEAVE THIS SPACE BLANK

------------------------------------------
SCARS AND MARKS PLACE OF
BIRTH 26 5 R OOO 12
-------------CLASS
-----------------------------CITIZENSHIP 12 W MOI
SIGNATURE OF OFFICIAL DATE
TAKING FINGERPRINTS CHECK IF
NO CRIMINALREF.
RECORD IS
DESIRED
---------------------------------------------------------------------------
1. RIGHT THUMB2. RIGHT INDEX3. RIGHT 4. RIGHT RING 5. RIGHT LITTLE
MIDDLE
26 12 0 17 12
[Illustration][Illustration][Illustration][Illustration][Illustration]
---------------------------------------------------------------------------
R W
---------------------------------------------------------------------------
1. LEFT THUMB 2. LEFT INDEX 3. LEFT 4. LEFT RING 5. LEFT LITTLE
MIDDLE
I M 18 I 15
[Illustration][Illustration][Illustration][Illustration][Illustration]
---------------------------------------------------------------------------
W W / W /
---------------------------------------------------------------------------

The chart, figure 351, will illustrate the manner in which the ridge
counts are translated into the symbols I and O so they may be grouped
and sequenced with the whorl tracings I, M and O.

THE MAJOR DIVISION: The major division is placed just to the left of
the primary in the classification formula. Where whorls appear in the
thumbs the major division reflects the whorl tracings just as the
subsecondary does. For example, a major division of I over M in the
primary 5 over 17 would reflect an inner-traced whorl over a
meeting-traced whorl in the thumbs. Where loops appear in the thumbs,
however, a table is used to translate the ridge counts into the small,
medium, or large groups, designated by the letters S, M, L. An
expanding table is used for the right thumb when large-count loops
appear in the left thumb, as shown in the chart (fig. 351). This table
is used because it affords a more equitable distribution of prints as
a whole, for filing purposes within the groups indicated.



--RIGHT HAND--
---------------------------------------------------------------------------
R THUMB R INDEX R MIDDLE R RING R LITTLE
---------------------------------------------------------------------------
WHEN LEFT THUMB 1-9 = I 1-10 = I 1-13 = I
IS 16 OR LESS 10 AND OVER = O11 AND OVER = O14 AND OVER = O
1-11 = S
12-16 = M
17 AND OVER = L
--------------------RIDGE COUNT OF SECOND SUBSECONDARY---------------------
WHEN LEFT THUMB 1-5 = S 1-8 = S 1-10 = S
IS 17 OR OVER 6-12 = M 9-14 = M 11-18 = M
1-17 = S 13 AND OVER = L15 AND OVER = L19 AND OVER = L
19-22 = M
23 AND OVER = L
---------------------------------------------------------------------------

--LEFT HAND--
---------------------------------------------------------------------------
L THUMB L INDEX L MIDDLE L RING L LITTLE
---------------------------------------------------------------------------
1-11 = S
12-16 = M <------------------VALUES SAME AS ABOVE------------------->
17 AND OVER = L
---------------------------------------------------------------------------

Table for major divisions of loops:

Left thumb denominator Right thumb numerator

{ 1 to 11, inclusive, S (small).
1 to 11, inclusive, S (small) { 12 to 16, inclusive, M (medium).
{ 17 or more ridges, L (large).


{ 1 to 11, inclusive, S (small).
12 to 16, inclusive, M (medium) { 12 to 16, inclusive, M (medium).
{ 17 or more ridges, L (large).

{ 1 to 17, inclusive, S (small).
17 or more ridges, L (large) { 18 to 22, inclusive, M (medium).
{ 23 or more ridges, L (large).

The fingerprint card appearing in figure 352 shows a major division of
L over L, which is obtained by counting the ridges (24 in the right
thumb and 18 in the left thumb) which, according to the table, is
translated into L in both thumbs.

THE FINAL: It is, of course, desirable to have a definite sequence or
order of filing the prints within the subdivided groups. This order is
attained through the use of the final, which is based upon the ridge
count of the loop in the right little finger. It is indicated at the
extreme right of the numerator in the classification. Note figure 352.
If a loop does not appear in the right little finger, a loop in the
left little finger may be used. It is then indicated at the extreme
right of the denominator (fig. 353). If no loops appear in the little
fingers, a whorl may be used to obtain a final, counting from left
delta to core if in the right hand and from right delta to core if in
the left hand. If there are two or more cores (usually applies to
accidental whorls), the ridge count is made from left delta (right
hand) or right delta (left hand) to the core which is the least
number of ridges distant from that delta. An exception is made in the
case of the double loop. The double loop is counted from the delta to
the core of the upright loop. Where loops of a double loop are
horizontal, the nearest core is used. Should both little fingers be a
or t, no final is used. The use of a whorl in a little finger for a
final is required only in connection with a large group or collection
of prints, such as the 32 over 32 primary.



LEAVE THIS SPACE BLANK SEX
+--------------+
FBI No. RACE
+--------------+ LAST NAME FIRST NAME MIDDLE NAME
---------------------------------------------------------------+----------
SIGNATURE OF PERSON CONTRIBUTOR ALIASES HT. WT.
FINGERPRINTED AND ADDRESS (IN.)

DATE OF
----------------------------- BIRTH
RESIDENCE OF PERSON
FINGERPRINTED HAIR EYES

--------------------------------------------------------------------------
OCCUPATION ARREST NUMBERLEAVE THIS SPACE BLANK
LLL
------------------------------------------ LMM
SCARS AND MARKS PLACE OF
BIRTH 24 L I R O O O 17
-------------CLASS
-----------------------------CITIZENSHIP L I R O O O
SIGNATURE OF OFFICIAL DATE
TAKING FINGERPRINTS CHECK IF
NO CRIMINALREF.
RECORD IS
DESIRED
---------------------------------------------------------------------------
1. RIGHT 242. RIGHT 133. RIGHT 314. RIGHT 215. RIGHT 17
THUMB INDEX MIDDLE RING LITTLE

[Illustration][Illustration][Illustration][Illustration][Illustration]
---------------------------------------------------------------------------
R
---------------------------------------------------------------------------
1. LEFT 182. LEFT 163. LEFT 134. LEFT 185. LEFT 20
THUMB INDEX MIDDLE RING LITTLE

[Illustration][Illustration][Illustration][Illustration][Illustration]
---------------------------------------------------------------------------
/ R / / /
---------------------------------------------------------------------------

THE KEY: The key is obtained by counting the ridges of the first loop
appearing on the fingerprint card (beginning with the right thumb),
exclusive of the little fingers which are never considered for the key
as they are reserved for the final. The key, no matter where found, is
always placed to the extreme left of the numerator of the
classification formula (fig. 353).





Next: Extensions

Previous: Questionable Patterns



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