The Science of Fingerprints | Page 8

one side of the impression and then
recurves, containing two rods within it, each of which rises as high as
the shoulder of the loop. From our study of cores, we know that the top
of the rod more distant from the delta is the core, but the recurving
ridge does not pass the imaginary line. For that reason the pattern is not
classified as a loop, but is given the preferential classification of a
tented arch due to the lack of one of the loop requisites. The proper
location of the core and delta is of extreme importance, for an error in
the location of either might cause this pattern to be classified as a loop.
Figure 64 reflects a similar condition.
[Illustration: 61]
[Illustration: 62]
[Illustration: 63]
[Illustration: 64]
[Illustration: 65]
[Illustration: 66]
In figure 65, there is a looping ridge A which enters on one side of the
impression. The ridges B and C are the type lines. As determined by
rules already stated, the location of the core and the location of the
delta are shown, and if an imaginary line were placed on the core and
delta, the recurving ridge A would cross it. This is another figure
showing a ridge which does not terminate on the side of the impression
from which it entered but tends to do so, and, therefore, is considered
as a loop.
In figure 66, we have a print which is similar in many respects to the

one described in the preceding paragraph, but here the recurving ridge
A continues and tends to terminate on the opposite side of the
impression from which it entered. For this reason the pattern is not a
loop, but a tented arch. The recurving ridge must touch or pass the
imaginary line between delta and core and at least tend to pass out
toward the side from which it entered, so that a ridge count of at least
one can be obtained.
[Illustration: 67]
Figure 67 shows a ridge which enters on one side of the impression and,
after flowing toward the center, turns or loops on itself and terminates
on the same side from whence it entered. This pattern would be
classified as a loop. This pattern should be distinguished from the
pattern appearing in figure 139. Careful study of the pattern in figure 67
reveals that the core is located at C and the delta D. The imaginary line
between these points will be crossed by the ridge forming a loop. In
figure 139, the core is located on the recurve and an imaginary line
between the delta and the core does not cross a looping ridge. Figure
139 is thus classified as a tented arch, as will be seen later.
Figure 68 shows at the center of the print a ridge which forms a pocket.
It will be noticed that ridge A does not begin on the edge of the print,
but this is of no significance. The ridge A within the pattern area
recurves or loops, passing the imaginary line between the delta and the
core, and tends to terminate toward the same side of the impression
from whence it entered. This is a loop pattern possessing all of the
requirements.
In figures 69 and 70, it will be observed that there is a ridge entering on
one side of the pattern which recurves and then turns back on itself.
These patterns are different from any others which have been shown in
this respect but are classified as loops. In each of the patterns the core
and delta are marked "C" and "D". The reader should trace the type
lines in order to ascertain why the delta is located at point D, and then
apply the delta rule.
[Illustration: 68]

[Illustration: 69]
Figure 71 is an example of loops as they appear on the rolled
impression portion of a fingerprint card.
[Illustration: 70]
[Illustration: 71]
Right Hand
-------------------------------------------------------------------------- 1. Thumb
| 2. Index | 3. Middle | 4. Ring | 5. Little | finger | finger | finger | finger
[Illustration]|[Illustration]|[Illustration]|[Illustration]|[Illustration]
-------------------------------------------------------------------------- Left
Hand -------------------------------------------------------------------------- 6.
Thumb | 7. Index | 8. Middle | 9. Ring | 10. Little | finger | finger | finger
| finger
[Illustration]|[Illustration]|[Illustration]|[Illustration]|[Illustration]
--------------------------------------------------------------------------
Ridge counting
The number of ridges intervening between the delta and the core is
known as the ridge count. The technical employees of the Federal
Bureau of Investigation count each ridge which crosses or touches an
imaginary line drawn from the delta to the core. Neither delta nor core
is counted. A red line upon the reticule of the fingerprint glass is used
to insure absolute accuracy. In the event there is a bifurcation of a ridge
exactly at the point where the imaginary line would be drawn, two
ridges are counted. Where