The Science of Fingerprints Part 3

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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 s.p.a.ce 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.

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_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 cla.s.sified as a loop. This type of pattern is the most numerous of all and const.i.tutes 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 pa.s.s 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 ab.u.t.ting 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 ab.u.t.ting upon its recurve between the shoulders and at right angles, as in ill.u.s.tration 56, will appear sometimes as in ill.u.s.tration 57 with the recurve totally destroyed. For further examples see figures 161 to 184.

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The same is true of a whorl recurve, as in figures 58 and 59.

It is necessary, therefore, to consider and cla.s.sify 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, pa.s.ses 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 pa.s.ses 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 cla.s.sified as such.

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Figure 62 shows a ridge entering on one side of the impression, recurving, and pa.s.sing beyond an imaginary line drawn from the delta to the core, although opposite from the pattern shown in figure 61.

After pa.s.sing 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 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 pa.s.s the imaginary line. For that reason the pattern is not cla.s.sified as a loop, but is given the preferential cla.s.sification 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 cla.s.sified as a loop.

Figure 64 reflects a similar condition.

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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 pa.s.s the imaginary line between delta and core and at least tend to pa.s.s out toward the side from which it entered, so that a ridge count of at least one can be obtained.

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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 cla.s.sified 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 cla.s.sified 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, pa.s.sing 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.