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_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 ridges. Sometimes ingrained dirt will cause a similar
condition between the ridges. These lines are not considered r