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

Figure 323 is a loop. There are two delta formations but the dots cannot be considered as obstructions crossing the line of flow at right angles. This precludes the classification of the central pocket loop type of whorl.

Fig. 323

[Fig. 323]

Figure 324 is a loop, the two recurving ridges have appendages and are considered spoiled. The pattern cannot, therefore, be a whorl even though two delta formations are present.

Fig. 324

[Fig. 324]

Figure 325 is classified as a tented arch. If examined closely the pattern will be seen to have an appendage abutting at a right angle between the shoulders of each possible recurve. Thus no sufficient recurve is present.

Fig. 325

[Fig. 325]

Figure 326 is a plain arch. There is present no angle which approaches a right angle. Points A, B, and X are merely bifurcations rather than an abutment of two ridges at an angle.

Fig. 326

[Fig. 326]

Figure 327 is a tented arch, not because of the dot, however, as it cannot be considered an upthrust. The tented arch is formed by the angle made when the curving ridge above the dot abuts upon the ridge immediately under and to the left of the dot.

Fig. 327

[Fig. 327]

Figure 328 consists of two separate looping ridge formations in juxtaposition upon the same side of a common delta. This pattern cannot be called a double loop as there is no second delta formation. In order to locate the core, the two looping ridges should be treated as one loop with two rods in the center. The core is thus placed on the far rod (actually on the left shoulder of the far loop), resulting in a ridge count of four (fig. 49).

Fig. 328

[Fig. 328]

Figure 329 is a loop of three counts. It cannot be classified as a whorl as the only recurve is spoiled by the appendage abutting upon it at the point of contact with the line of flow.

Fig. 329

[Fig. 329]

Figure 330 is a plain arch as there is no upthrust (an upthrust must be an ending ridge), no backward looping turn, and no two ridges abutting upon each other at a sufficient angle.

Fig. 330

[Fig. 330]

Figure 331 is a plain arch. The ending ridge at the center does not rise at a sufficient angle to be considered an upthrust, and it does not quite meet the ridge toward which it is flowing and therefore forms no angle.

Fig. 331

[Fig. 331]

Figure 332 is a plain arch. There are two ending ridges, but no separate delta formation is present.

Fig. 332

[Fig. 332]

Figure 333 is a plain arch. The rising ridge at the center is curved at the top forming no angle, and does not constitute an upthrust because it is not an ending ridge.

Fig. 333

[Fig. 333]

Figure 334 is a whorl of the double loop type. Two loops and two deltas are present. It is unusual because the loops are juxtaposed instead of one flowing over the other, and one delta is almost directly over the other. The tracing is a meeting tracing.

Fig. 334

[Fig. 334]

Figure 335 is a tented arch. Although there is a looping ridge, no ridge count can be obtained. The core is placed upon the end of the ridge abutting upon the inside of the loop, and so the imaginary line crosses no looping ridge, which is necessary.

Fig. 335

[Fig. 335]

Figure 336 is a plain arch. The ending ridge at the center cannot be considered an upthrust because it does not deviate from the general direction of flow of the ridges on either side. No angle is present as the ending ridge does not abut upon the curving ridge which envelopes it.

Fig. 336

[Fig. 336]

Figure 337 is a plain arch because the dot cannot be considered a delta as it is not as thick and heavy as the surrounding ridges.

Fig. 337

[Fig. 337]

Figure 338 is a tented arch consisting of two ending ridges and a delta. The short ending ridge is considered a ridge because it is slightly elongated and not a mere dot.

Fig. 338

[Fig. 338]

In figure 339, the only question involved is where to stop tracing. The rule is: when tracing on a ridge with an upward trend, stop at the point on the upward trend which is nearest to the right delta. X is the point in this pattern.

Fig. 339

[Fig. 339]

In figure 340, the question involved is also one of tracing. In this pattern, the tracing is not on a ridge with an upward trend. The tracing, therefore, is continued until a point nearest to the right delta, or the right delta itself, is reached. This tracing is a meeting tracing.

Fig. 340

[Fig. 340]

There are a few constantly recurring patterns which, though not questionable or doubtful as they appear, present a peculiarly difficult problem in classifying. The patterns referred to are usually double loops, though accidental whorls and loops sometimes present the same problems. The difficulty arises when a loop is so elongated that the recurve does not appear until near the edge of a fully rolled impression or an impression that is rolled unusually far, as in figures 341 to 344.

Figs. 341-342

Figs. 343-344

[Figs. 341-344]

Figure 341, if classified as it appears, would be an accidental whorl. Figures 342 and 343 would be double loops, and illustration 344, a loop. It will be observed that these prints are rolled more fully than normal. If, however, the next time the prints are taken, they are not rolled quite so far, the patterns would require a very different classification, and would show no indication of any need for referencing to their true classification. The result would be a failure to establish an identification with the original prints. The only way in which such an error may be avoided is to classify such impressions as they would appear if not so fully rolled, and to conduct a reference search in the classification which would be given to the prints when rolled to the fullest extent. Applying this rule, illustration 341 is a tented arch, referenced to a whorl. Figures 342 and 343 are loops, referenced to whorls. Figure 344 is a plain arch, referenced to a loop.

No set rule can possibly be devised to enable a classifier to know with certainty where to draw the line when it is doubtful which classification should be given such a print. Individual judgment is the only standard. The test is: if the pattern, in the opinion of the classifier, is rolled to only a normal width, it should be classified as it appears. If it seems to be rolled to a width beyond the normal degree, it should be classified as if rolled only to the normal degree. Age, weight, size of fingers (as seen in the plain impressions), heaviness of the ridges, and experience of the technician in taking fingerprints are all factors in arriving at the correct conclusion. The necessity for exercising the utmost care in dealing with this type of pattern cannot be too highly emphasized.

The patterns in figures 345 and 346 also have a second loop near the edge of the impression. In these two patterns, however, the second loop is very near the delta and consequently will almost invariably appear even though not rolled to the fullest extent. The foregoing rule is not applied to this type of impression. Both are classified as a whorl and referenced to a loop to take care of the rare contingency of nonappearance.

Figs. 345-346

[Figs. 345-346]

At this point it is necessary to mention that when prints are classified, markings are indicated at the bottom of each finger block to reflect the type. The following symbols are used: