The Science of Fingerprints | Page 7

of the loops. Again the two are treated as one,
with two rods, the core being placed at C. In figure 49, the two are
treated as one, with two rods, the core being placed at C.
[Illustration: 41]
[Illustration: 42]
[Illustration: 43]
[Illustration: 44]
[Illustration: 45]
[Illustration: 46]
[Illustration: 47]
[Illustration: 48]
[Illustration: 49]
[Illustration: 50]
[Illustration: 51]
[Illustration: 52]
In figure 50, the delta is formed by a bifurcation which is not connected
with either of the type lines. The first ridge count in this instance is
ridge C. If the bifurcation were not present, the delta would be a point
on ridge C and the first ridge count would be ridge D. In figure 51, the
ridge which bifurcates is connected with the lower type line. The delta
in this would be located on the bifurcation as designated and the first
ridge count would be ridge C. Figure 52 reflects the same type of delta
shown in the previous figure in that the ridge is bifurcating from a type
line and then bifurcates again to form the delta.
A white space must intervene between the delta and the first ridge

count. If no such interval exists, the first ridge must be disregarded. In
figures 53 and 54, the first ridge beyond the delta is counted. In figure
55, it is not counted because there is no interval between it and the
delta. Notice that the ridge running from the delta toward the core is in
a straight line between them. If it were not, of course, an interval would
intervene as in figures 53 and 54.
[Illustration: 53]
[Illustration: 54]
[Illustration: 55]
The loop
In fingerprints, as well as in the usual application of the word "loop,"
there cannot be a loop unless there is a recurve or turning back on itself
of one or more of the ridges. Other conditions have to be considered,
however. A pattern must possess several requisites before it may be
properly classified as a loop. This type of pattern is the most numerous
of all and constitutes about 65 percent of all prints.
A loop is that type of fingerprint pattern in which one or more of the
ridges enter on either side of the impression, recurve, touch or pass an
imaginary line drawn from the delta to the core, and terminate or tend
to terminate on or toward the same side of the impression from whence
such ridge or ridges entered.
Essentials of a loop
- A sufficient recurve.
- A delta.
- A ridge count across a looping ridge.
A sufficient recurve may be defined as that part of a recurving ridge
between the shoulders of a loop. It must be free of any appendages
abutting upon the outside of the recurve at a right angle.

Appendages--Some explanation is necessary of the importance attached
to appendages. Much care must be exercised in interpreting appendages
because they sometimes change the shape of the recurving ridge to
which they are connected. For example, a loop with an appendage
abutting upon its recurve between the shoulders and at right angles, as
in illustration 56, will appear sometimes as in illustration 57 with the
recurve totally destroyed. For further examples see figures 161 to 184.
[Illustration: 56]
[Illustration: 57]
The same is true of a whorl recurve, as in figures 58 and 59.
It is necessary, therefore, to consider and classify figures 56 and 58 as
if they actually appeared as in figures 57 and 59.
In figure 60, there is a ridge marked "A" which enters on one side of
the impression and, after recurving, passes an imaginary line drawn
from the core C to delta D, and terminates on the same side of the
impression from which it entered, marked "B", thus fulfilling all the
conditions required in the definition of a loop. X and Y are the type
lines. It will be noted in figure 61 that there is a ridge which enters on
one side of the impression, recurves, and passes an imaginary line
drawn from the delta to the core. It does not terminate on the side from
which it entered but has a tendency to do so. In this case, all the
requirements of the loop have been met, and consequently it is
classified as such.
[Illustration: 58]
[Illustration: 59]
[Illustration: 60]
Figure 62 shows a ridge entering on one side of the impression,
recurving, and passing beyond an imaginary line drawn from the delta
to the core, although opposite from the pattern shown in figure 61.

After passing the imaginary line, the recurving ridge does not terminate
on the side of the impression from which it entered, but it has a
tendency to do so, and the pattern is, therefore, a loop.
In figure 63, a ridge enters on