The Science of Fingerprints | Page 8

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 the line crosses an island, both sides are counted. Fragments and dots are counted as ridges only if they appear to be as thick and heavy as the other ridges in the immediate pattern. Variations in inking and pressure must, of course, be considered.
Figures 72 to 97 and figures 98 to 101 show various loop patterns. The reader should examine each one carefully in order to study the cores and deltas and to verify the count which has been placed below each pattern.
[Illustration: 72. 12 counts.]
[Illustration: 73. 2 counts.]
[Illustration: 74. 16 counts.]
[Illustration: 75. 7 counts.]
[Illustration: 76. 4 counts.]
[Illustration: 77. 7 counts.]
[Illustration: 78. 15 counts.]
[Illustration: 79. 16 counts.]
[Illustration: 80. 9 counts.]
[Illustration: 81. 3 counts.]
[Illustration: 82. 9 counts.]
[Illustration: 83. 20 counts.]
[Illustration: 84. 6 counts.]
[Illustration: 85. 2 counts.]
[Illustration: 86. 8 counts.]
[Illustration: 87. 14 counts.]
[Illustration: 88. 5 counts.]
[Illustration: 89. 12 counts.]
[Illustration: 90. 12 counts.]
[Illustration: 91. 3 counts.]
[Illustration: 92. 16 counts.]
[Illustration: 93. 14 counts.]
[Illustration: 94. 16 counts.]
[Illustration: 95. 18 counts.]
[Illustration: 96. 2 counts.]
[Illustration: 97. 1 count.]
[Illustration: 98. 1 count.]
[Illustration: 99. 2 counts.]
[Illustration: 100. 8 counts.]
[Illustration: 101. 13 counts.]
Figure 102 is a sketch reflecting the various types of ridges which the classifier will encounter when engaging in counting loop patterns.
In figure 103, the lighter lines are caused by the splitting or fraying of the