The Science of Fingerprints by United States. Federal Bureau of Investigation (books to read in a lifetime txt) 📕

class="c1">Fig. 294

Figs. 295-296

[Figs. 294-296]

CHAPTER III Questionable Patterns

 

No matter how definite fingerprint rules and pattern definitions are made, there will always be patterns concerning which there is doubt as to the classification they should be given. The primary reason for this is the fact that probably no two fingerprints will ever appear which are exactly alike. Other reasons are differences in the degree of judgment and interpretation of the individual classifying fingerprints, the difference in the amount of pressure used by the person taking the prints, and the amount or kind of ink used. Nothing can be done about faulty inking or pressure once the prints are taken. The patterns which are questionable merely because they seem to have characteristics of two or more types can be classified by strict adherence to the definitions in deducing a preference. The following section is devoted to such patterns with an explanation of each.

Figure 297 has two loop formations. The one on the left, however, has an appendage abutting upon the shoulders of its recurve at a right angle. The left portion of the impression, therefore, is of the tented arch type. The combination of two different types of patterns would be classified in the whorl group (accidental), but this impression has only the one delta. The right portion of the pattern detail contains a true loop which fulfills all the loop requirements, i.e., a sufficient recurve, a delta, and a ridge count across a looping ridge. In the choice existing between a tented arch and a loop, preference is given to the loop classification and this impression would be classified as a loop.

 

Fig. 297

[Fig. 297]

 

Figure 298, at a glance, seems to fulfill the requirements of a whorl (two deltas and a ridge making a complete circuit). The part of the circuit in front of the right delta, however, cannot be construed as a recurving ridge because of the appendage abutting upon it in the line of flow. This pattern, therefore, is a one-count loop.

 

Fig. 298

[Fig. 298]

 

Figure 299 is a very difficult and unusual pattern. It has characteristics of three types, the whorl, the loop, and the tented arch. It is given the preference of an accidental type of whorl (loop over a tented arch). This pattern should be referenced both as a loop and as a tented arch.

 

Fig. 299

[Fig. 299]

 

Figure 300 is shown for the purpose of explaining that in the whorl, as this print is, appendages at the top of the recurve will not spoil or affect the recurve. Hence, the impression is a good whorl of the central pocket loop type and needs no reference.

 

Fig. 300

[Fig. 300]

 

Figure 301 is classified as a whorl of the double loop type. There are present two distinct loops and two deltas (the right delta is not present as the impression was not rolled sufficiently). The pattern is unusual because the loops are side by side and flowing in the same direction. The tracing is an inner tracing.

 

Fig. 301

[Fig. 301]

 

Figure 302 should present no difficulty. It is classified as a plain arch for its ridge construction follows the rule of a plain arch, i.e., "enter one side and flow or tend to flow to the other."

 

Fig. 302

[Fig. 302]

 

Figure 303 is a plain arch. The dot at the center is not elongated enough to be considered an upthrust. A dot, even though as thick and heavy as the surrounding ridges, is not considered for any purpose but ridge counting or fixing a delta.

 

Fig. 303

[Fig. 303]

 

Figure 304 is a pattern somewhat similar to the previous illustration. As indicated before, dots are considered as ridges only in ridge counting and fixing a delta. This pattern, therefore, must be classified as a plain arch, rather than a tented arch with two ending ridges and a delta formation.

 

Fig. 304

[Fig. 304]

 

Figure 305, although showing an appendage upon each recurve on the left side, is classified as a whorl of the central pocket loop type, with two deltas and a recurve in front of each. To spoil the recurve of a whorl the appendage must be connected to the recurve at the point of contact with the line of flow.

 

Fig. 305

[Fig. 305]

 

In figure 306, the impression has two equally good loop formations. As it has but one delta, it cannot be classified as a whorl of the double loop type nor as a loop since it would be difficult to make a preferential choice between the two looping ridges. It is arbitrarily given the classification of a tented arch.

 

Fig. 306

[Fig. 306]

 

In figure 307, the difficulty lies in locating the delta. The only ridges answering the definition of type lines (ridges running parallel and then diverging to enclose the pattern area) have three ending ridges between them. The type lines, the delta, and the core are located as indicated. The pattern is classified as a six-count loop.

 

Fig. 307

[Fig. 307]

 

Figure 308 is classified as a tented arch, although it appears at first glance to be a loop. Closer inspection shows that the looping ridge does not tend to go out the side from which it entered but rather seems to proceed downward ending in an abutment forming a definite angle of 90°.

 

Fig. 308

[Fig. 308]

 

In figure 309, an impression is shown which at first appears to be a loop. Closer inspection will show that one of the elements of the loop type is missing, namely, a ridge count across a looping ridge; for it is to be borne in mind that the recurve of the innermost loop should be free of appendages abutting between the shoulders at right angles. The core, in this illustration, therefore, is placed where the appendage of the innermost loop touches the next ridge which is a good recurve. If an imaginary line is placed between delta and core, it will be seen that there are no intervening ridges; hence, there is no ridge count.

 

Fig. 309

[Fig. 309]

 

Figure 310 is a pattern which contains two elements of a loop but lacks the third. It is classified as a tented arch. Thus an impression having a delta and a recurve, but not having a ridge count across a looping ridge, falls into this classification.

 

Fig. 310

[Fig. 310]

 

It will be noticed that although this pattern has the resemblance of a plain arch, the center of the impression actually contains a partially formed loop. A recurving ridge enters from the right side and exits in the same direction. A delta also appears just below the recurve. In attempting to obtain a ridge count, it is seen that the imaginary line drawn between the delta and the core runs directly along the ridge emanating from the former and which is joined onto the side of the recurving ridge. For this reason, no ridge count is possible.

Figure 311 is a tented arch. There are three loop formations, each one of which is spoiled by an appendage abutting upon its recurve between the shoulders at a right angle. It cannot be classified as an accidental as the patterns are all of the same type, i.e., tented arches. An accidental type of whorl is a combination of two or more different types of patterns exclusive of the plain arch.

 

Fig. 311

[Fig. 311]

 

Figure 312 is a loop. It cannot be classified as a whorl of the double loop type because the formation above the lower loop is too pointed and it also has an appendage abutting upon it at a right angle.

 

Fig. 312

[Fig. 312]

 

Figure 313 at first glance appears to be a whorl of the double loop type. Upon closer inspection, however, it will be noticed that there are no delta formations other than on the recurves. There are, then, two tented arch formations. As two patterns of the same type cannot form an accidental whorl, the impression must be classified as a tented arch.

 

Fig. 313

[Fig. 313]

 

Figure 314 is an accidental whorl, combining a loop and a tented arch. The tented arch is directly beneath the innermost loop, and is of the upthrust type.

 

Fig. 314

[Fig. 314]

 

Figure 315 consists of a loop over a dot with an apparent second delta. This pattern must be classified as a loop, as a dot may not be considered an upthrust unless elongated vertically.

 

Fig. 315

[Fig. 315]

 

Even though a dot may be as thick and heavy as the surrounding ridges, it may be considered only in ridge counting or fixing a delta.

Figure 316 at first glance appears to be an accidental whorl, but on closer inspection it proves to be a loop. Although there are three delta formations present, it should be observed that recurving ridges appear in front of only one (D-1).

 

Fig. 316

[Fig. 316]

 

Figure 317 has the general appearance of a loop. The looping ridge A, at the center, has an appendage B abutting upon its recurve. The abutment is at right angles and therefore spoils the recurve. The pattern is a tented arch.

 

Fig. 317

[Fig. 317]

 

Figure 318 is a tented arch which approaches both the loop and the whorl type patterns. It cannot be considered a whorl, however, as the recurve on the left is spoiled by an appendage (figs. 58 and 59). Nor can it be a loop because there is no ridge count across a looping ridge. The pattern, then, is a tented arch of the type possessing two of the basic characteristics of the loop and lacking the third. The delta and the sufficient recurve are present but the ridge count is missing.

 

Fig. 318

[Fig. 318]

 

Figure 319 seems at first glance to be a double loop. It will be noted, however, that the inner delta formation would be located upon the only looping ridge of the upper loop formation. Since the delta would be located on the only recurve, this recurving ridge is eliminated from consideration. The pattern is classified as a loop.

 

Fig. 319

[Fig. 319]

 

Figure 320 is a loop of two counts, with the delta at B. There is a ridge making a complete circuit present, but point A cannot be used as a delta because it answers the definition of a type line. It should be considered a delta only if it presented an angular formation. Placing the delta upon the recurve would spoil that recurve.

 

Fig. 320

[Fig. 320]

 

Figure 321 shows two separate looping ridge formations appearing side by side and upon the same side of the delta. The core in such case is placed upon the nearer shoulder of the farther looping ridge from the delta, the two looping ridges being considered as one loop with two rods rising as high as the shoulder. The ridge count would be four (fig. 49).

 

Fig. 321

[Fig. 321]

 

Figure 322 is an accidental whorl. It is classified thus because it contains elements of three different patterns, the loop, the double loop, and the accidental. In such case the order of preference governs. The delta at the left is point A. The delta at the right is point C. This point becomes the delta since it is the point nearest the center of the divergence of the type lines. Point B is eliminated from consideration as a delta since type lines may not proceed from a bifurcation unless they flow parallel after the bifurcation and before diverging.

 

Fig. 322

[Fig. 322]